CN117256159A

CN117256159A - Solid-state imaging device and camera equipment

Info

Publication number: CN117256159A
Application number: CN202280000991.6A
Authority: CN
Inventors: 山下雄一郎; 小林篤
Original assignee: Beijing Xiaomi Mobile Software Co Ltd
Current assignee: Beijing Xiaomi Mobile Software Co Ltd
Priority date: 2022-04-15
Filing date: 2022-04-15
Publication date: 2023-12-19
Also published as: WO2023197333A1; JP2024516752A

Abstract

The present application provides a solid-state imaging device including a plurality of first pixels and a plurality of second pixels different from the plurality of first pixels, each of the plurality of first pixels and the plurality of second pixels including: one or more photoelectric conversion elements that constitute a light receiving surface of the pixel and generate electric charges by photoelectrically converting received light; a floating diffusion region connected to the one or more photoelectric conversion elements and converting the electric charges into voltages corresponding to the amounts of the electric charges; and a storage capacitor connected to the floating diffusion region and capable of accumulating the electric charges overflowing from the one or more photoelectric conversion elements, wherein each of the plurality of first pixels is configured to include two or more photoelectric conversion elements, each of the two or more photoelectric conversion elements is connected to the floating diffusion region, and the electric charges accumulated in the two or more photoelectric conversion elements are compared with each other to generate a phase difference data signal, and two or more second pixels among the plurality of second pixels together form a second pixel group, and the second pixel group is configured to generate a phase difference data signal by comparing the electric charges accumulated in each of the second pixels constituting the second pixel group.

Description

Solid-state imaging device and camera equipment

Technical Field

The present invention relates to a solid-state imaging device and a camera apparatus provided with the solid-state imaging device.

Background

In recent years, in camera devices such as digital cameras, as a technique for realizing an input dynamic range in which a sustainable accumulation capacity exceeds an allowable range in photodiodes (photoelectric conversion elements) provided in pixels, a high dynamic range imaging (High Dynamic Range Imaging, HDR imaging) technique is known. For example, in patent document 1, there is disclosed an "overflow charge accumulation capacitance" HDR imaging technique that can hold a charge far exceeding the upper limit of the accumulation capacitance that can be held by a photodiode in a pixel by accumulating the charge overflowing from the photodiode into an additional holding capacity provided in the pixel.

In addition, in recent camera apparatuses, demand for high-speed and high-precision auto focusing has increased. As such an autofocus technique, particularly in a relatively small camera device such as a non-return camera or a smart phone, a photographing-plane phase difference autofocus technique is often employed. In this imaging image plane phase difference autofocus, the light receiving surface of a pixel under one microlens is divided into two parts, signals from an object passing through different optical paths are read out, and the spatial phase difference of the object image is processed to calculate a defocus amount. In this way, in the imaging plane phase difference autofocus, since the defocus amount can be calculated by one phase calculation, there is an advantage that high-speed autofocus can be performed compared to the contrast detection autofocus that has been conventionally employed.

Comparing the two types of imaging plane phase difference auto focusing modes, in the dual-pixel mode, all pixels can contribute to the creation of phase difference information and the output of an image signal, while in the occlusion mode, only occluded pixels contributing to the creation of phase difference information contribute to the output of an image signal, only non-occluded pixels contribute to the output of an image signal. Therefore, typically, the dual pixel system is more accurate in auto focus than the occlusion system, and is more excellent than the SN ratio of a captured image, particularly when capturing a low-luminance subject.

On the other hand, in the two-pixel system, when a high-luminance object is imaged, electric charges are generated in one of the two photodiodes disposed in one pixel beyond the upper limit of the retainable capacitance, and the electric charges overflowing from the photodiode may flow into the other photodiode. In the pixel where such overflow occurs, the two photodiodes no longer provide correct phase difference information, and may become a main cause of lowering the autofocus accuracy.

There has also been an attempt to apply such a two-pixel type photographing plane phase difference autofocus technique to a pixel employing a spillover charge accumulating capacitive HDR imaging technique as in patent document 1.

As an example of such an attempt, first, a two-pixel system in which two photodiodes are arranged in one pixel, and a system in which additional holding capacities corresponding to the photodiodes are respectively arranged are considered. However, if a plurality of additional storage capacitors are arranged in the pixel in this way, the pixel becomes large in size, and it is not practical to use the above-described relatively small camera device such as a non-inverted camera and a smart phone.

As a method of combining these technologies while suppressing an increase in size of a pixel, patent document 2 discloses a pixel having an overflow holding capacitance that can hold charges overflowing from two photodiodes (photoelectric conversion sections) that are commonly provided in the two photodiodes. In this pixel, the potential barrier between two photodiodes is set relatively large, so that the charge designed to overflow from one photodiode preferentially flows into the overflow holding capacitance instead of the other photodiode. The electric charge thus flowing into the overflow holding capacitance and being held is added to one of the two photodiodes holding a larger electric charge when the phase difference signal is generated. Thus, in the pixel of patent document 2, even when charges are generated beyond the upper limit of the capacitance that can be held by one of the two photodiodes in the pixel, accurate phase difference information can be provided. Therefore, according to the pixel of patent document 2, a high dynamic range can be achieved, and auto-focusing can be performed with sufficiently high accuracy even for a high-luminance subject to some extent.

However, in the pixel of patent document 2, although it is possible to cope with a case where only one of the two photodiodes overflows, when a high-luminance object where both photodiodes overflow is photographed, electric charges flow from both photodiodes into one overflow holding capacitance. Therefore, there is a problem that the phase information of the charges held in the overflow holding capacitance is lost, and as a result, the correct phase difference information cannot be provided.

Prior art literature

Patent literature

Patent document 1: U.S. patent application publication No. 2017/0099423

Patent document 2: JP 2020-57894A.

Disclosure of Invention

Problems to be solved by the invention

Accordingly, the present invention solves the problem of providing a solid-state imaging device that can realize a high dynamic range and also provide highly accurate phase difference information for a higher-luminance object, and a camera device provided with the solid-state imaging device.

Solution for solving the problem

In the solid-state imaging device according to the present invention,

comprises a plurality of first pixels and a plurality of second pixels different from the plurality of first pixels,

each of the plurality of first pixels and the plurality of second pixels includes:

One or more photoelectric conversion elements that constitute a light receiving surface of the pixel and generate electric charges by photoelectrically converting received light;

a floating diffusion region connected to the one or more photoelectric conversion elements and converting the electric charges into voltages corresponding to the amounts of the electric charges; and

a holding capacitor connected to the floating diffusion region and capable of accumulating the electric charges overflowing from the one or more photoelectric conversion elements,

each of the plurality of first pixels is configured to include two or more photoelectric conversion elements, each of the two or more photoelectric conversion elements is connected to the floating diffusion region, and the charges accumulated in the two or more photoelectric conversion elements are compared with each other to generate a phase difference data signal,

more than two second pixels among the plurality of second pixels together constitute a second pixel group,

the second pixel group is configured to generate a phase difference data signal by comparing the charges accumulated in each of the second pixels constituting the second pixel group.

In the solid-state imaging device, for example, in each of the two or more pixels constituting the second pixel group, a portion of the light receiving surface of the pixel is blocked so as to prevent light from being received at the portion of the light receiving surface.

Alternatively, in the solid-state imaging device, a separate on-chip lens (OCL) is provided in each of the plurality of first pixels,

an independent one on-chip lens (OCL) is provided in each of the second pixel groups, and the two or more pixels constituting the second pixel groups share the one on-chip lens (OCL).

In the solid-state imaging device, in each of the plurality of first pixels,

the potential barrier between the two or more photoelectric conversion elements is lower than the potential barrier between the photoelectric conversion elements and the holding capacitance.

In this case, preferably, in each of the plurality of the above-described second pixels,

when the total number of charges accumulated in the one or more photoelectric conversion elements is equal to or less than a predetermined saturation charge amount, a phase difference data signal is generated based on the total number of charges accumulated in the one or more photoelectric conversion elements,

when the total number of charges accumulated in the one or more photoelectric conversion elements is larger than a predetermined saturation charge amount, a phase difference data signal is generated based on the total number of charges accumulated in the one or more photoelectric conversion elements and the total number of charges accumulated in the storage capacitor.

Alternatively, in the solid-state imaging device, in each of the plurality of first pixels,

the potential barrier between the two or more photoelectric conversion elements may be higher than the potential barrier between the photoelectric conversion elements and the storage capacitor.

In this case, preferably, in each of the plurality of second pixels described above,

when the charges accumulated in the one or more photoelectric conversion elements are equal to or less than a predetermined saturation charge amount, a phase difference data signal is generated based on the total number of charges accumulated in the one or more photoelectric conversion elements,

when the charge accumulated in any one of the one or more photoelectric conversion elements is greater than a predetermined saturation charge amount, a phase difference data signal is generated based on the total number of the charges accumulated in the one or more photoelectric conversion elements and the charges accumulated in the holding capacitance.

In addition, the solid-state imaging device includes, for each of the plurality of first pixels,

it is determined whether or not the electric charges held by each of the two or more photoelectric conversion elements reach a threshold value indicating that overflow occurs in the photoelectric conversion element, and if the threshold value is not reached, a phase difference data signal generated based on the electric charges generated in the two or more photoelectric conversion elements is output to the first pixel, and if at least one of the electric charges reaches the threshold value, a phase difference data signal generated based on the electric charges generated in the second pixel group determined by the solid-state imaging device may be output.

The camera device of the present invention is configured to,

the solid-state imaging device includes the solid-state imaging device, and a control device configured to control the solid-state imaging device.

The camera device is configured to determine, for example, based on a signal from the control device, whether or not the solid-state imaging device outputs a phase difference data signal for each pixel based on the electric charges generated in the two or more photoelectric conversion elements included in the first pixel, and/or whether or not to output a phase difference data signal for each pixel based on the electric charges generated in the two or more second pixel groups.

The camera device may be a mobile terminal, for example.

Drawings

Fig. 1 is a diagram showing a configuration of a solid-state imaging device according to a first embodiment.

Fig. 2 is a diagram showing an example of arrangement of pixels arranged in the pixel array section, and a plurality of specific examples of the second pixels are shown in one diagram.

Fig. 3 is a sectional view showing the structure of the first pixel.

Fig. 4 is a sectional view showing the structure of the second pixel.

Fig. 5 is an equivalent circuit diagram of a pixel included in the solid-state imaging device.

Fig. 6 is a diagram showing the potential barriers between the photoelectric conversion element and the holding capacitance in each pixel of the first embodiment.

Fig. 7 is a timing chart of the above-described pixel.

Fig. 8 is a flowchart showing a first output example of the phase difference data signal.

Fig. 9 is a flowchart showing a second output example of the phase difference data signal.

Fig. 10 is a flowchart showing a third output example of the phase difference data signal.

Fig. 11 is a flowchart showing in detail step 1002 of the third output example in the first embodiment.

Fig. 12 is a diagram showing the potential barriers of the photoelectric conversion element and the holding capacitance in each pixel of the second embodiment.

Fig. 13 is a flowchart showing in detail step 1002 of the third output example in the second embodiment.

Fig. 14 is a diagram showing a configuration of a solid-state imaging device according to another embodiment.

Fig. 15 is a sectional view showing the structure of a solid-state imaging device according to another embodiment.

Detailed Description

The solid-state imaging device of the present invention comprises:

a plurality of first pixels, and a plurality of second pixels different from the plurality of first pixels,

a floating diffusion region connected to the one or more photoelectric conversion elements and converting the electric charges into voltages corresponding to the amounts of the electric charges;

A floating holding capacitor connected to the floating diffusion region and capable of accumulating the electric charges overflowed from the one or more photoelectric conversion elements,

each of the plurality of first pixels is configured to include two or more photoelectric conversion elements, each of the two or more photoelectric conversion elements is connected to the floating diffusion region, and phase difference data signals can be generated by comparing the charges accumulated in the two or more photoelectric conversion elements,

According to this configuration, by appropriately using both the method of generating charges in the plurality of photoelectric conversion elements based on the first pixels provided in the solid-state imaging device and the method of generating charges in the second pixel group provided in the solid-state imaging device, it is possible to generate a highly accurate phase difference data signal for both the high-luminance subject and the low-luminance subject.

For example, when the object has high luminance and exceeds the charge of the storage capacitor that can be held by the photoelectric conversion element included in the pixel, as in the double pixel system described above, in the system based on the charges generated in the plurality of photoelectric conversion elements, since the charges overflow from the photoelectric conversion element, there is a possibility that an accurate phase difference data signal cannot be generated. On the other hand, in the manner of comparing the electric charges generated in the plurality of pixel groups of the second pixel group, if the electric charges generated in each of the plurality of pixels is equal to or less than the total number of the amounts that can be accumulated by the photoelectric conversion element and the additional holding capacitance, by comparing the electric charges held in the respective pixels of the plurality of pixel groups, an accurate phase difference data signal can be provided.

Further, since the charges overflowing from the photoelectric conversion element are held in the additional holding capacitance, a photographic image with a high dynamic range can be generated by reading out these charges.

Alternatively, if the subject is low in luminance, the charges generated in the photoelectric conversion elements included in the pixels do not exceed the storage capacitance that can be held, and no charge overflow occurs, it is possible to provide a phase difference data signal that is based on the phase difference data signals generated in all the photoelectric conversion elements in the first pixel and that is based on a two (or three, four, or the like) pixel system with higher accuracy.

In the solid-state imaging device, in each of the plurality of first pixels,

According to this configuration, when a charge exceeding a storable storage capacity is generated in one of the two or more photoelectric conversion elements included in the first pixel, the charge overflowing from the photoelectric conversion element does not flow into the additional storage capacity, but flows preferentially into the other photoelectric conversion elements included in the pixel. Typically, since the noise of the electric charge held by the photoelectric conversion element tends to be smaller than that of the electric charge held by the additional holding capacitance, the SN ratio of the obtained photographic image can be made high.

According to this configuration, when the total number of charges accumulated in the photoelectric conversion element of the second pixel is equal to or less than a predetermined saturation charge amount (for example, when it is assumed that charges overflowing from the photoelectric conversion element do not flow into the additional holding capacitance), the phase difference data signal is generated without considering the additional holding capacitance, and therefore, the phase difference data signal with higher accuracy can be generated without being affected by noise caused by the holding capacitance.

According to this configuration, when a charge exceeding a storable storage capacitance is generated in one of the two or more photoelectric conversion elements included in the first pixel, the charge overflowing from the photoelectric conversion element preferentially flows into the additional storage capacitance. In this case, even if a charge overflow occurs in the photoelectric conversion element of the pixel, the charge held by the additional holding capacitance can be regarded as the overflow charge generated by the photoelectric conversion element as long as there is one overflow photoelectric conversion element. Therefore, even for a relatively high-luminance object, a highly reliable phase difference data signal can be generated by the first pixel.

According to this configuration, when the charges accumulated in the photoelectric conversion elements of the second pixels are equal to or less than a predetermined saturation charge amount (for example, when it is assumed that the charges overflowing from the photoelectric conversion elements do not flow into the additional holding capacitance), the phase difference data signal is generated without taking the additional holding capacitance into consideration, and therefore, the phase difference data signal with higher accuracy can be generated without being affected by noise caused by the holding capacitance.

In addition, the solid-state imaging device may be configured such that, for each of the plurality of first pixels,

judging whether or not the electric charges held by each of the two or more photoelectric conversion elements reach a threshold value indicating that overflow occurs in the photoelectric conversion element, outputting, in the first pixel, a phase difference data signal generated based on the electric charges generated in the two or more photoelectric conversion elements if the threshold value is not reached, and outputting, in the case where at least one of the two or more photoelectric conversion elements reaches the threshold value, a phase difference data signal generated based on the electric charges generated in the second pixel group determined by the solid-state imaging device.

According to this configuration, the solid-state imaging device can appropriately determine which of the two phase difference data signal generation methods is used for each pixel by determining whether or not the phase difference information is held without being destroyed (for example, whether or not the electric charge generated in a certain photoelectric conversion element overflows and does not flow into another photoelectric conversion element), and can output a more accurate phase difference data signal.

In this case, when it is determined that the phase difference information is destroyed in a certain first pixel and an accurate phase difference data signal cannot be generated by comparing the charges generated in the plurality of photoelectric conversion elements of the first pixel, the solid-state image device selects, for example, the charge information of a nearby second pixel from the charge information of a plurality of pixels currently read into the line memory, and regards the phase difference data signal generated based on the charge information of the nearby second pixel as the phase difference data signal generated by the first pixel.

The camera device of the present invention is configured to,

According to this configuration, the camera device can generate a highly accurate phase difference data signal for both a high-luminance subject and a low-luminance subject by appropriately using both a method of comparing charges generated in two or more photoelectric conversion elements included in a first pixel included in a solid-state imaging device and a method of comparing charges generated in a second pixel group included in the solid-state imaging device.

According to this configuration, in the solid-state imaging device, the camera apparatus can be controlled from outside the solid-state imaging device by the control device of the camera apparatus: the phase difference data signal is output using a manner of comparing charges generated in two or more photoelectric conversion elements of the first pixel or using a manner of comparing charges generated in the second pixel group (or using both manners simultaneously).

The camera device may be a mobile terminal such as a smart phone, a mobile phone, a tablet computer, a mobile information terminal (PDA), etc.

< first embodiment >, first embodiment

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

[ structural example of solid-state imaging device ]

The solid-state imaging device according to the present embodiment is incorporated in a camera device such as a smart phone or a digital camera, and includes a CMOS image sensor.

Specifically, as shown in fig. 1, the solid-state imaging device 1 includes a pixel array section 2, a vertical driving section 3, a plurality of column signal processing sections 4, a horizontal driving section 5, a control section 6, and a signal processing section 7. The solid-state imaging device 1 further includes a memory 8 that can store the signals and the like processed by the signal processing unit 7. In the solid-state imaging device 1 according to the present embodiment, a CMOS image sensor is constituted by at least the pixel array section 2, the vertical driving section 3, the plurality of column signal processing sections 4, the horizontal driving section 5, and the control section 6.

At least, the pixel array section 2, the vertical driving section 3, the column signal processing section 4, the horizontal driving section 5, the control section 6, and the signal processing section 7 are arranged on the same semiconductor substrate or on a plurality of semiconductor substrates electrically connected. The signal processing section 7 and the memory 8 may be arranged on a semiconductor substrate on which the pixel array section 2, the vertical driving section 3, the column signal processing section 4, the horizontal driving section 5, and the control section 6 are arranged, or may be arranged on different substrates. That is, the arrangement positions of the signal processing unit 7 and the memory 8 are not limited.

The pixel array section 2 has a plurality of pixels 10 two-dimensionally arranged in a matrix. Each of the plurality of pixels 10 constitutes a light receiving surface of the pixel 10, and has two photoelectric conversion elements 11R and 11L, and the photoelectric conversion elements 11R and 11L can photoelectrically convert input light (incident light), accumulate signal charges (charges) in an amount corresponding to the amount of the input light, and output the accumulated signal charges.

The plurality of pixels 10 are constituted by a plurality of first pixels 10A whose light receiving surface is not blocked by the opaque film and a plurality of second pixels 10B whose light receiving surface is partially blocked by the opaque film, but the arrangement state of the first and second pixels 10A, 10B and the light receiving surface are not shown in fig. 1. Details of the specific constitution of each pixel 10 including their arrangement state or light shielding state of the light receiving surface will be described later.

In addition to the first pixel 10A and the second pixel 10B, the pixel array section 2 may include a dummy unit pixel having no photoelectric conversion element structure, or a pixel that blocks light input from the outside by blocking the light receiving surface.

The pixel array section 2 has a plurality of row signal lines 21 arranged in each row and extending in the row direction, and a plurality of column signal lines 22 arranged in each column and extending in the column direction, with respect to the matrix-like pixel arrangement. Each of the above-described plurality of row signal lines 21 is connected to the vertical driving section 3, and each of the plurality of column signal lines 22 is connected to the corresponding column signal processing section 4.

The vertical driving section 3 is constituted by a shift register, for example, and selects a predetermined row signal line 21, thereby supplying a pulse (signal) for driving the pixels 10 to the selected row signal line 21, and driving the pixels 10 in units of rows. In detail, the vertical driving section 3 sequentially selects the pixels 10 of the scanning pixel array section 2 in the vertical direction in units of rows, and supplies pixel signals based on signal charges generated in the photoelectric conversion elements 11 of the pixels 10 according to the input light amounts to the column signal processing section 4 through the column signal lines 22.

The plurality of column signal processing units 4 are arranged for each column of the pixels 10, and perform signal processing such as noise reduction for each pixel column on pixel signals output from the pixels 10 in one row. The column signal processing units 4 of the present embodiment perform signal processing such as correlated double sampling (Correlated Double Sampling:cds) for removing fixed pattern noise inherent to pixels, and a/D (Analog/Digital) conversion.

The horizontal driving section 5 is configured by, for example, a shift register, sequentially outputs horizontal scanning pulses, sequentially selects each of the plurality of column signal processing sections 4, and sequentially outputs pixel signals subjected to signal processing by the respective column signal processing sections 4 to the signal processing section 7.

The control unit 6 controls the operation of each unit of the solid-state imaging device 1. Specifically, the control section 6 receives an input clock signal and data for instructing an operation mode or the like, and outputs data such as internal information of the solid-state imaging device 1. Specifically, the control unit 6 generates a clock signal or a control signal as a reference for the operations of the vertical driving unit 3, the column signal processing unit 4, the horizontal driving unit 5, and the like based on the vertical synchronization signal, the horizontal synchronization signal, and the master clock signal, and outputs the generated clock signal or control signal to the vertical driving unit 3, the column signal processing unit 4, the horizontal driving unit 5, and the like.

The signal processing unit 7 performs various signal processing such as arithmetic processing on the pixel signals output from the respective column signal processing units 4. The signal processing unit 7 of the present embodiment is a DSP (Digital Signal Processor; digital signal processor).

The specific arrangement position of the signal processing unit 7 is not limited. In the solid-state imaging device 1 according to the present embodiment, the signal processing unit 7 is disposed at a position different from that of the CMOS image sensor, but the entire configuration of the signal processing unit 7 may be disposed (mounted) on the CMOS image sensor, or a part of the signal processing unit 7 may be configured to be disposed on the CMOS image sensor.

The memory 8 is a line memory, a frame memory, a FIFO, or the like, and can store pixel signals and the like output from the respective column signal processing units 4. The specific configuration of the memory 8 will be described later.

[ arrangement example of pixels in pixel array section ]

Next, a specific arrangement example of pixels arranged in a matrix in the pixel array section 2 will be described with reference to fig. 2.

As shown in fig. 2, a plurality of pixels 10 are two-dimensionally arranged in a matrix in the pixel array section 2. In the example shown in fig. 2, 4 rows by 9 columns of pixels 10 are arranged. Further, two photoelectric conversion elements 11R and 11L are provided for each pixel 10.

As shown in fig. 2, the plurality of pixels 10 are configured to include a plurality of first pixels 10A whose light receiving surfaces are not blocked by the opaque film 60 and a plurality of second pixels 10B whose light receiving surfaces are partially blocked by the opaque film 60. In the example shown in fig. 2, in the case where the pixel in the mth row and n-th column is represented as a pixel (m, n), the pixels arranged in (1, 1), (1, 5), (1, 9), (3, 1), (3, 5), (3, 9), (5, 5), and (5, 9) are the second pixels 10B whose light receiving surfaces are partially blocked by the opaque film 60, and the remaining pixels are the first pixels 10A.

The first pixel 10A generates a photographing data signal based on the signal charges accumulated in the pixel, and, in the case where the signal charges generated in the two photoelectric conversion elements 11R, 11L included in the pixel do not overflow, can generate a phase difference data signal that receives light by comparing the amounts of the signal charges generated in the two photoelectric conversion elements 11R, 11L.

On the other hand, when the second pixel 10B is configured such that the signal charges generated in the photoelectric conversion elements 11R and 11L of the first pixel 10A overflow and the phase difference data signal cannot be generated from the first pixel 10A, the phase difference data signal for receiving light can be generated by comparing the charges accumulated in each of the second pixels 10B constituting two or more second pixel 10B groups corresponding to each other.

In the present embodiment, the two or more pixels corresponding to each other constituting the second pixel 10B group are two or more pixels in which the phases of light which can be received and which can be received are complementary to each other, the phases of light which can be received and which can be received are not shielded in one second pixel 10B. In the example shown in fig. 2, when the row direction of fig. 2 is left and right and the column direction is up and down, the combination of the pixels (1, 1) and (3, 1) in which the upper half and the lower half of the pixel are respectively shielded, the combination of the pixels (1, 5) and (1, 9) in which the right half and the left half of the pixel are respectively shielded, the combination of the pixels (3, 9) and (5, 9) in which the right half and the left half of the same pixel are respectively shielded, and the combination of the pixels (3, 5) and (5, 5) in which the upper right half and the lower left half of the pixel are respectively shielded belong to two pixels corresponding to each other.

In fig. 2, for convenience, the upper half and the lower half, the right half and the left half, the upper right half and the lower left half of the pixels are shown as combinations of pixels that are respectively shielded, but the combination of the second pixels 10B need not be arranged in the pixel array section 2, but a plurality of specific examples are shown in one drawing. For example, the second pixels 10B disposed in the pixel array section 2 may be pixels whose right half or left half is shielded.

Here, in order to sufficiently accurately obtain the accuracy of the phase difference data signals generated by the second pixel 10B group, two or more pixels corresponding to each other constituting the second pixel 10B group are preferably arranged in a row and a column that are close to each other to some extent. Not limited to the following, but for example, these pixels may be designed to: in the two-dimensional arrangement of the pixel array section 2, neither the rows nor the columns are spaced apart from each other by 20 pixels or more.

The second pixel 10B is generally not conducive to generation of a photographing data signal unlike the first pixel 10A, and therefore, the photographing data signal at the position where the second pixel 10B is disposed may need to be complemented by the photographing data signal from the nearby first pixel 10A. At this time, if the second pixels 10B are disposed at positions too close to each other, the replenishment of the photographing data signal may be hindered. Therefore, the present invention is not limited to the following, but two or more pixels corresponding to each other constituting the second pixel 10B group may be designed, for example: in the two-dimensional arrangement of the pixel array section 2, rows and columns are each spaced apart by 1 pixel or more.

The ratio of the number of first pixels to the number of second pixels constituting the pixels 10 arranged in the pixel array section 2 is not particularly limited, but in order to obtain a good image data signal based on the signal charges accumulated in the first pixels 10A, a sufficiently accurate phase difference data signal may be obtained by the second pixels in a high-luminance state in which the signal charges overflow from at least one of the two photoelectric conversion elements 11R, 11L included in the first pixels 10A, for example, the number of first pixels: number of second pixels = 4:1 to 64:1, preferably 6:1 to 32:1, more preferably 8:1 to 24:1, for example, may be 12:1.

[ construction of pixels ]

Next, a specific configuration of the pixels 10 arranged in a matrix in the pixel array section 2 will be described with reference to fig. 3 to 5.

First, a schematic structure of the first pixel 10A in which the light receiving surface is not blocked by the opaque film will be described with reference to fig. 3.

As shown in fig. 3, the first pixel 10A includes: a semiconductor region 20 that constitutes a light receiving surface and includes two photoelectric conversion elements 11R and 11L that generate signal charges by photoelectrically converting received light; and an independent one on-chip lens 30 provided on the semiconductor region 20 so as to cover the two photoelectric conversion elements 11R, 11L.

With this configuration, light (for example, L1 and L2 shown in fig. 3) incident on the first pixel 10A is refracted by the on-chip lens 30, and is incident on one of the two photoelectric conversion elements 11R and 11L through different optical paths, respectively. That is, since which of the two photoelectric conversion elements 11R, 11L receives light is determined according to the phase of the light incident on the first pixel 10A, a phase difference occurs in the light received by the two photoelectric conversion elements 11R, 11L. Therefore, the phase difference data signal can be generated by comparing the amounts of light received by the two photoelectric conversion elements 11R, 11L, that is, by comparing the amounts of signal charges generated by photoelectric conversion of the light, with respect to the first pixel 10A.

In the present embodiment, the first pixel 10A further includes a color filter 40 and a transparent film 50 between the semiconductor region 20 and the on-chip lens 30. The color filter 40 selects, for example, R (red), G (green), or B (blue) for each pixel so that each pixel is arranged as desired (for example, bayer arrangement) in the planar arrangement of the pixel array section 2 shown in fig. 2. The color filter 40 and the transparent film 50 are not necessarily required, and may be omitted.

Next, a schematic structure of the second pixel 10B having the light receiving surface blocked by the opaque film portion will be described with reference to fig. 4.

The second pixel 10B includes a semiconductor region 20 including two photoelectric conversion elements 11R and 11L, an on-chip lens 30, a color filter 40, and a transparent film 50, similarly to the first pixel a. On the other hand, the second pixel 10B is different from the first pixel 10A in that the light receiving surface is partially shielded (blocked) by the opaque film 60.

With this configuration, in the second pixel 10B, the light of the phase shielded by the opaque film 60 cannot be received, and only the light of the specified phase which is not shielded can be received. Therefore, in the second pixels 10B, like the first pixels 10A, each pixel cannot independently generate the phase difference data signal, but in the combination of the second pixels 10B in the adjacent rows and columns in which the phases of the received light are complementary, the phase difference data signal can be generated by comparing the amounts of the light received by each second pixel 10B, that is, by comparing the amounts of signal charges generated by photoelectric conversion of the light.

Specifically, the explanation will be made based on the example shown in fig. 4, in which, as an example of the second pixel 10B, the second pixel 10 b_r that is shielded from light by the opaque film 60 is shown on the left side of fig. 3 (in the above example, the photoelectric conversion element 11L), and the second pixel 10 b_l that is shielded from light by the opaque film 60 is shown on the right side of fig. 4 (in the above example, the photoelectric conversion element 11R). The second pixel 10 b_r does not receive the light of the left phase, which is shielded, but receives the light of the right phase, and the second pixel 10 b_l does not receive the light of the right phase, which is shielded, but receives the light of the left phase. Therefore, the second pixel 10 b_r receiving only light of the right phase and the second pixel 10 b_l receiving only light of the left phase are in a complementary relationship with each other, and by comparing the amounts of light received by these pixels, a phase difference data signal can be generated.

In addition, although one of the photoelectric conversion elements 11R, 11L of the second pixels 10 b_r, 10 b_l shown in fig. 4 is completely shielded by the opaque film 60, the second pixels 10B may be partially shielded by the photoelectric conversion elements 11R, 11L as in some of the second pixels 10B shown in fig. 2. For example, as the second pixels 10B arranged in (1, 1) and (3, 1) of the pixel array section 2 shown in fig. 2, a combination of the second pixels 10B in a complementary relationship with each other may be constituted by pixels in which the upper half portions of the photoelectric conversion elements 11R and 11L constituting the light receiving surface are shielded, and pixels in which the lower half portions thereof are shielded.

In the present embodiment, the second pixel 10B includes two photoelectric conversion elements similarly to the first pixel 10A, but the photoelectric conversion element included in the second pixel 10B may be one.

Next, a circuit configuration included in the semiconductor region 20 common to the first pixel 10A and the second pixel 10B constituting the pixel 10 will be described with reference to fig. 5.

In the circuit configuration shown in fig. 5, the pixel 10 includes: two photoelectric conversion elements 11R, 11L that generate signal charges by photoelectric conversion according to input light; a floating diffusion region 12 that converts signal charges generated by the photoelectric conversion elements 11R, 11L into a voltage signal (voltage) corresponding to the amount of the signal charges; and a holding capacitance (overflow holding capacitance) 13 that is connected to the floating diffusion region 12 and is capable of accumulating signal charges overflowed from the photoelectric conversion elements 11R, 11L. The photoelectric conversion elements 11R and 11L of the present embodiment are photodiodes, for example.

The pixel 10 includes: transfer transistors (first switching transistors) 14R, 14L that connect the photoelectric conversion elements 11R, 11L and the floating diffusion region 12, respectively; a holding switching transistor (second switching transistor) 15 that connects the floating diffusion region 12 and the holding capacitance 13; a reset transistor (third switching transistor) 16 that connects the holding capacitance 13 and the reset power supply (reset potential) VDD1; an amplifying transistor 17 that amplifies the voltage signal of the floating diffusion region 12; and a selection transistor 18 that connects the amplifying transistor 17 and the column signal line 22.

For a plurality of pixels 10 arranged in a matrix, a plurality of row signal lines 21 are wired for each pixel row. Various driving signals Φtx_l, Φtx_r, Φs, Φres, Φsel are supplied from the vertical driving section 3 to the pixels 10 via the row signal lines 21. The driving signals phi TX_L, phi TX_R, phi S, phi RES, phi SEL are the pulses.

The floating diffusion region 12 performs charge-voltage conversion of the signal charges generated by the photoelectric conversion elements 11R, 11L into a voltage signal and outputs it. The floating diffusion region 12 of the present embodiment is also connected to the reset power supply VDD1 via the hold switch transistor 15 and the reset transistor 16 in this order.

The holding capacitance 13 is a capacitor, and as described above, is connected to the floating diffusion region 12 via the holding switching transistor 15, and is also connected to the reset power supply VDD1 via the reset transistor 16.

The drive signal phitx_l is applied to the gate electrode of the transfer transistor 14L. The drive signal Φtx_l is outputted from the vertical drive section 3 based on a signal (instruction) from the control section 6. When the drive signal Φtx_l becomes Hi (i.e., when the transfer transistor 14L is turned on), the transfer gate of the transfer transistor 14L becomes on, and the signal charge accumulated in the photoelectric conversion element 11 is transferred to the floating diffusion 12 via the transfer transistor 14. Further, when the drive signal Φtx_l becomes Low, the transfer transistor 14L is turned off.

Similarly, a drive signal Φtx_r is applied to the gate electrode of the transfer transistor 14R. The drive signal Φtx_r is outputted from the vertical drive section 3 based on a signal (instruction) from the control section 6. When the drive signal Φtx_r becomes Hi (i.e., when the transfer transistor 14R is turned on), the transfer gate of the transfer transistor 14R becomes on, and the signal charge accumulated in the photoelectric conversion element 11R is transferred to the floating diffusion 12 via the transfer transistor 14R. Further, when the drive signal Φtx_r becomes Low, the transfer transistor 14R is turned off.

The drive signal os is applied to the gate electrode of the holding switching transistor 15. The driving signal Φs is outputted from the vertical driving section 3 based on a signal from the control section 6. When the drive signal Φs becomes Hi (i.e., the holding switching transistor 15 is turned on), the holding gate of the holding switching transistor 15 becomes an on state, and the signal charge can move from the floating diffusion region 12 to the holding capacitance 13. Further, when the drive signal Φs becomes Low, the holding switching transistor 15 is turned off.

The drive signal Φres is applied to the gate electrode of the reset transistor 16. The drive signal Φres is outputted from the vertical drive section 3 based on a signal from the control section 6. When the drive signal Φres becomes Hi (i.e., the reset transistor 16 is turned on), the reset gate of the reset transistor 16 becomes on, and the potential of the floating diffusion 12 and the holding capacitance 13 or the potential of the holding capacitance 13 is reset to the level (reset level) of the reset power supply (reset potential) VDD1 according to the drive signal Φs applied to the gate electrode of the holding switching transistor 15. Further, when the drive signal Φres becomes Low, the reset transistor 16 is turned off.

In the amplifying transistor 17, the gate electrode is connected to the floating diffusion region 12, and the drain electrode is connected to the power supply VDD2. The amplifying transistor 17 is an input portion of a readout circuit (so-called source follower circuit SF) that reads out the voltage of the floating diffusion region 12 as a pixel signal. That is, the amplifying transistor 17 is configured by connecting a source electrode to the column signal line 22 via the selection transistor 18, thereby configuring a constant current source and a source follower circuit SF connected to one end of the column signal line 22.

The selection transistor 18 is connected to the source electrode of the amplification transistor 17 and the column signal line 22. A drive signal Φsel is applied to the gate electrode of the selection transistor 18. The drive signal Φsel is outputted from the vertical drive section 3 based on a signal from the control section 6. When the drive signal Φsel becomes Hi (i.e., the selection transistor 18 is turned on), the selection gate of the selection transistor 18 becomes on, and the pixel 10 becomes selected. Thereby, the pixel signal output from the amplifying transistor 17 is output to the column signal line 22 via the selecting transistor 18. Further, when the drive signal Φsel becomes Low, the selection transistor 18 is turned off.

Finally, the relationship between the potential barriers between the two photoelectric conversion elements 11R and 11L and the storage capacitor 13 in the pixel 10 will be described with reference to fig. 6.

As shown in fig. 6, in the pixel 10 of the present embodiment, the potential barrier between the two photoelectric conversion elements 11R and 11L is lower than the potential barrier between the two photoelectric conversion elements 11R and 11L and the storage capacitor 13. In the circuit configuration shown in fig. 5, the potential barrier between the two photoelectric conversion elements 11R, 11L is set by adjusting the holding gates of the transfer transistors 14R, 14L, and the potential barrier between the two photoelectric conversion elements 11R, 11L and the holding capacitor 13 is set by adjusting the holding gate of the holding switching transistor 15.

Therefore, in the pixel 10 of the present embodiment, when signal charges exceeding the storable storage capacitance are generated in one of the photoelectric conversion elements 11R, 11L (for example, the photoelectric conversion element 11L) at the time when the transfer transistors 14R, 14L and the holding switching transistor 15 are turned off, the signal charges overflowing from the one photoelectric conversion element 11R, 11L first exceed the potential barrier between the lower photoelectric conversion elements 11R, 11L (the holding gates of the transfer transistors 14R, 14L), preferentially flow into the other photoelectric conversion element 11R, 11L (for example, the photoelectric conversion element 11R) and are accumulated. When the signal charges accumulated in both the photoelectric conversion elements 11R and 11L reach the limit of the accumulation capacitance that can be held, the signal charges overflowing from the photoelectric conversion elements 11R and 11L exceed the potential barrier between the higher photoelectric conversion elements 11R and 11L and the holding capacitance 13 (the holding gate of the holding switching transistor 15), flow into the holding capacitance 13, and are accumulated.

Typically, the noise of the charges held in the photoelectric conversion elements 11R, 11L tends to be lower than the noise of the signal charges held in the holding capacitance 13. Therefore, as in the present embodiment, the signal charges generated in the photoelectric conversion elements 11R and 11L are accumulated as much as possible in the photoelectric conversion elements 11R and 11L instead of the pixel 10 of the storage capacitor 13, and thus the effect of relatively high SN ratio of the output image data signal can be achieved.

Further, in the first pixel 10A, in the case where the signal charge overflowing from one of the photoelectric conversion elements 11R, 11L flows into the other photoelectric conversion element 11R, 11L, the information of the light of the phase received in each of the photoelectric conversion elements 11R, 11L overflows or mixes, and therefore the signal charge held in the photoelectric conversion element 11R, 11L does not contribute to generating a correct phase difference data signal. Therefore, in the present embodiment, when signal charge overflows in a certain first pixel 10A, the first pixel 10A can output a reliable imaging data signal by a driving method described later, but cannot output a reliable phase difference data signal. In this case, the signal generated by the second pixel 10B can be used as a reliable phase difference data signal.

[ example of driving pixels of solid-state imaging device ]

The driving timing of the pixel 10 configured as described above will be described with reference to fig. 7. Further, fig. 7 shows a drive signal (pulse of a control signal) of the pixel 10, and accordingly an output voltage (pixel signal) appearing on the column signal line 22, vout representing the output voltage.

First, at time t01, in a state where the selection transistor 18 is turned off, the transfer transistors 14R and 14L, the holding switching transistor 15, and the reset transistor 16 are turned on, and the floating diffusion 12 and the holding capacitor 13 become reset levels.

In this way, the transfer transistor 14 is turned off in a state in which the floating diffusion region 12 is connected to the reset power supply VDD1, whereby the photoelectric conversion elements 11R, 11L become a floating state, and accumulation of signal charges generated by input of light starts in the photoelectric conversion elements 11R, 11L, respectively.

Almost at the same time (in detail, with a slight delay) when the transfer transistors 14R, 14L are turned off, the holding switch transistor 15, the reset transistor 16 are turned off, respectively, whereby the floating diffusion region 12 and the holding capacitance 13 also become a floating state.

Here, when the signal charge overflows (overflows) from at least one of the photoelectric conversion elements 11R, 11L, the holding capacitance 13, which becomes a floating state, and the photoelectric conversion elements 11R, 11L, which have not overflowed yet, can hold (accumulate) the overflowed signal charge. In detail, as described above with respect to fig. 6, the signal charges overflowed from one of the photoelectric conversion elements 11R, 11L are first held (accumulated) in the other photoelectric conversion element 11R, 11L. After that, after the signal charge held in any one of the photoelectric conversion elements 11R, 11L reaches the limit of the accumulation capacitance that can be held, the overflowed signal charge flows into the holding capacitance 13 to be held.

In this way, in a state where the transfer transistors 14R and 14L, the holding switching transistor 15, and the reset transistor 16 are turned off, after the transfer transistors 14R and 14L are turned off, the pixel signal of the pixel 10 is read from the time T02 after the predetermined accumulation period Δt elapses.

Specifically, when the control unit 6 (in detail, the vertical driving unit 3 which receives an instruction from the control unit 6) turns on the selection transistor 18 by changing the driving signal Φsel to Hi from the state where the switching transistors 14R, 14L, 15, 16, and 18 of the pixel 10 are turned off, the pixel 10 is connected to the column signal line 22.

Next, at time t03, the potential of the floating diffusion region 12 (floating diffusion region reference potential) is read out from the source follower circuit SF, and is stored in the memory 8 as a first signal (pixel signal) after a/D conversion.

In the solid-state imaging device 1 of the present embodiment, the column signal processing unit 4 stores the first signal in the memory 8 in the a/D converted state (i.e., in the state converted into the digital signal), but the present invention is not limited to this configuration. The subsequent processes may also be performed while the pixel signal (the voltage of the floating diffusion region 12) read out from the source follower circuit SF is kept as an analog signal. The same applies to the pixel signals (second to fifth signals) read out from the source follower circuit SF at the subsequent time points.

Next, at time T04, control unit 6 turns on transfer transistor 14R by changing drive signal Φtx_r to Hi, transfers signal charges accumulated in photoelectric conversion element 11R during accumulation period Δt to floating diffusion 12, and turns off transfer transistor 14 by changing drive signal Φtx_r to Low.

This signal is read out from the source follower circuit SF at time t05, and is stored in the memory 8 as a second signal (pixel signal) after a/D conversion.

Next, at time T06, control unit 6 turns on transfer transistors 14R and 14L by turning on both drive signals Φtx_r and Φtx_l, transfers signal charges accumulated in photoelectric conversion elements 11R and 11L during accumulation period Δt to floating diffusion 12, and turns off transfer transistor 14 by turning on drive signals Φtx_r and Φtx_l.

This signal is read out from the source follower circuit SF at time t07, and is stored in the memory 8 as a third signal (pixel signal) after a/D conversion.

Next, at time t08, control unit 6 turns on holding switching transistor 15 by turning on driving signal Φs, thereby turning on floating diffusion region 12 and holding capacitor 13, and then turns on and off transfer transistor 14 by turning on driving signals Φtx_r and Φtx_l again. The voltage of the floating diffusion region 12 at this time is read out from the source follower circuit SF at t09, and is stored in the memory 8 as a fourth signal (pixel signal) after a/D conversion.

Finally, at time t10, the control unit 6 turns on the reset transistor 16 by changing the drive signal Φres to Hi, thereby connecting the floating diffusion region 12 and the holding capacitor 13 to the reset power supply (reset potential) VDD1, and initializing (resetting) all the signal charges of the floating diffusion region 12 and the holding capacitor 13. The voltages (reset levels) of the floating diffusion region 12 and the holding capacitor 13 after the initialization are read out from the source follower circuit SF at t11, and are stored in the memory 8 as a fifth signal (pixel signal) after a/D conversion.

By processing the first to fifth signals obtained in the driving of the above pixel 10, it is possible to restore the signal based on the signal charges held in the photoelectric conversion elements 11R and 11L and the holding capacitance 13. Specifically, the first signal is subtracted from the second signal, thereby restoring a signal (signal R) in which the electric charge held in the photoelectric conversion element 11R after correction is obtained based on the reset noise and the deviation of the DC level. Similarly, the first signal is subtracted from the third signal, thereby restoring a signal (signal r+l) based on the total amount of charges held in the photoelectric conversion elements 11R and 11L after the reset noise and the deviation of the DC level are corrected. Further, by subtracting the second signal from the third signal, a signal (signal L) of the total amount of charges held in the photoelectric conversion element 11L after correction based on the reset noise and the deviation of the DC level is recovered. Then, by subtracting the signal 05 from the signal 04, the signals (signals r+l+c) of the photoelectric conversion elements 11R and 11L and the signal charges held in the holding capacitance 13, which have been corrected based on the deviation of the DC level, are restored.

Here, when the pixel 10 is the first pixel 10A, the signal charges generated by the light incident on the photoelectric conversion elements 11R and 11L during the accumulation period Δt do not exceed the capacitance that the photoelectric conversion elements 11R and 11L can hold, and when no overflow from the photoelectric conversion elements 11R and 11L occurs, the signal r+l recovered by the above processing can be used as a correct captured data signal.

Also in this case, the information output from the photoelectric conversion elements 11R, 11L holds information about the phases of the lights respectively incident thereon, and therefore, the signal R and the signal L recovered by the above-described processing can be used as reliable phase signals by comparing them, whereby a correct phase difference data signal can be generated.

In the first pixel 10A, when the signal charges generated by light incident on the photoelectric conversion elements 11R and 11L during the accumulation period Δt exceed the capacitance that one of the photoelectric conversion elements 11R and 11L can hold, and the signal charges overflow from one of the photoelectric conversion elements 11R and 11L to the other, the signal r+l recovered by the above-described processing can be used as a correct imaging data signal.

However, in this case, since the signal charges overflow from one to the other of the photoelectric conversion elements 11R, 11L, the signal R and the signal L do not have a meaning as a phase signal. Therefore, the signal R and the signal L cannot be used as the phase difference data signals to be generated reliably.

In the first pixel 10A, when the signal charges generated by the light incident on the photoelectric conversion elements 11R and 11L during the accumulation period Δt exceed the capacitance that can be held by one of the photoelectric conversion elements 11R and 11L, and the signal charges overflow from the photoelectric conversion elements 11R and 11L to the holding capacitance 13, the signal r+l recovered by the above-described processing is different from the above-described 2 cases in that the signal quantity processed by the photoelectric conversion elements 11R and 11L is exceeded, and therefore, it does not have a meaning as a captured data signal. In this case, if a signal from the holding capacitance 13 is used, the above-described signal r+l+c can be used as a correct shooting data signal.

In this case, the signals R and L also have no meaning as phase signals, and therefore cannot be used to generate reliable phase difference data signals.

In addition, in the case where the pixel 10 is the second pixel 10B, the second pixel 10B generally does not produce a useful photographing data signal. In the combination of the second pixels 10B in which the phases of the received light are complementary, the signal r+l (in the case where no overflow from the photoelectric conversion elements 11R, 11L to the holding capacitance 13 occurs) or the signal r+l+c (in the case where overflow from the photoelectric conversion elements 11R, 11L to the holding capacitance 13 occurs) of each of the second pixels 10B restored by the above-described processing can be used as a phase signal for generating a reliable phase difference data signal in the second pixel 10B group.

[ output example of phase difference data Signal from solid-State imaging device ]

As described above, the solid-state imaging device 1 according to the present embodiment includes two units, i.e., a unit that generates a phase difference data signal from the first pixel 10A and a unit that generates a phase difference data signal from the second pixel 10B. These units can be appropriately selected according to the brightness or exposure time of a shooting scene using the solid-state imaging device 1. For example, in the case where the photographing scene is low in luminance or the exposure time (accumulation period Δt) is short, it is difficult for the photoelectric conversion elements 11R, 11L to overflow, and therefore it is considered that the phase difference data signal generated in the first pixel 10A that generates photographing data can be effectively utilized. On the other hand, when the imaging scene has a high luminance or a long exposure time (accumulation period Δt), it is considered that the photoelectric conversion elements 11R and 11L are likely to overflow, and it is difficult to generate a reliable phase difference data signal in the first pixel 10A, and it is preferable to replace the phase difference data signal generated in the second pixel 10B. An example of outputting the phase difference data signal in the pixel array section 2 of the solid-state imaging device 1 according to the present embodiment will be described below.

Fig. 8 is a flowchart showing a first output example of the phase difference data signal from the solid-state imaging device. As shown in fig. 8, the first output example includes the following steps 801 to 803.

First, in step 801, signal data generated in a plurality of pixels 10 (i.e., first pixels 10A and second pixels 10B) included in a fixed range of the pixel array section 2 is accumulated in the memory 8 by a method or the like shown in the driving example of the pixels 10. The memory 8 is, for example, a line memory that accumulates signal data of pixels 10 arranged on one or more lines as a reading object, among a plurality of pixels 10 arranged in two dimensions in a matrix in the pixel array section 2.

Next, in step 802, in the pixels 10 related to the signal data accumulated on the memory 8 (i.e., referenceable on the memory 8), the following processing is performed on the signal data concerning the first pixels 10A, thereby outputting a phase difference data signal from each of the first pixels 10A.

Specifically, each of the first pixels 10A that can be referred to on the memory 8 outputs two signals, that is, a phase difference data signal (hereinafter, also referred to as a first phase difference data signal) generated based on the signal charges accumulated in the photoelectric conversion elements 11R, 11L of the first pixel 10A and a phase difference data signal (hereinafter, also referred to as a second phase difference data signal) generated based on the signal charges accumulated in the second pixel 10B group that can be referred to on the memory 8.

The second group of pixels 10B to be referred to for generating the second phase difference data signal output by the phase difference information of the first pixel 10A as an object is preferably a second group of pixels 10B located in the vicinity of the first pixel 10A as an object, and the average distance of each of the first pixels 10A as an object and the second pixels 10B constituting the second group of pixels 10B is more preferably the shortest group among all the second groups of pixels 10B that can be referred to on the memory 8.

Thereafter, in step 803, if there are more pixels 10 in the pixel array section 2 that have not been read in the memory 8, the signal data accumulated in the memory 8 is updated, and the above steps 801 to 802 are repeated until all the pixels 10 included in the pixel array section 2 are read.

In the case of the first output example described above, it is possible to determine which phase difference data signal is flexibly used for the first phase difference data signal and the second phase difference data signal output from the first pixel 10A of the pixel array section 2 by the control device or the like of the camera apparatus that receives the output signals. Alternatively, two phase difference data signals may be flexibly used according to the output destination.

Fig. 9 is a flowchart showing a second output example of the phase difference data signal from the solid-state imaging device. As shown in fig. 9, the second output example includes the following steps 901 to 903.

First, in step 901, as in the first output example, signal data generated in a plurality of pixels 10 included in a fixed range of the pixel array section 2 is accumulated in the memory 8.

Next, in step 902, each of the first pixels 10A that can be referred to on the memory 8 selects whether to output the first phase difference data signal or the second phase difference data signal based on an instruction from the outside of the solid-state imaging device 1. The instruction from the outside is executed by, for example, a control device or the like provided in the camera device in which the solid-state imaging device 1 is mounted.

For example, in a case where it is determined that the camera apparatus does not use the holding capacitance 13 of the pixel 10, that is, in a case where the HDR mode is not employed, the control device of the camera apparatus may instruct to output the first phase difference data signal as the phase difference information of the first pixel 10A of the object. On the other hand, in the case where it is determined that the camera apparatus uses the holding capacitance 13 of the pixel 10, that is, in the case of adopting the HDR mode, the control device of the camera apparatus may instruct to output the second phase difference data signal as the phase difference information of the first pixel 10A of the object.

In this case, regarding whether or not the holding capacitance 13 is used for the pixels 10 in the pixel array section 2, in most cases, the same mode is adopted based on the setting of the control means of the camera apparatus. However, it is not always necessary that all the pixels 10 in the pixel array section 2 have the same pattern, and an instruction to use the storage capacitor 13 may be transmitted to the first pixel 10A disposed in a part of the pixel array section 2 and an instruction to not use the storage capacitor 13 may be transmitted to the remaining part. For example, among all the pixels 10 provided with the camera device, the pixels 10 near the center which are sensitive to light may be given different instructions according to the arrangement positions of the pixels 10, without using the storage capacitor 13, and the pixels 10 near the periphery which are difficult to receive light may be given different instructions by using the storage capacitor 13.

Then, in step 903, if there are more pixels 10 in the pixel array section 2 that are not read in the memory 8, the signal data accumulated in the memory 8 is updated, and the above steps 901 to 902 are repeated until all the pixels 10 included in the pixel array section 2 are read.

In the case of the second output example described above, the amount of the signal to be output can be reduced as compared with the first output example, and therefore, the burden of signal processing in a control device or the like of the camera device that receives the signal to be output can be reduced.

Fig. 10 is a flowchart showing a second output example of the phase difference data signal from the solid-state imaging device. As shown in fig. 10, the second output example includes the following steps 1001 to 1003.

First, in step 1001, as in the first output example, signal data generated in a plurality of pixels 10 included in a fixed range of the pixel array section 2 is accumulated in the memory 8.

Next, in step 1002, each of the first pixels 10A that can be referred to on the memory 8 selects whether to output the first phase difference data signal or the second phase difference data signal based on the judgment of the solid-state imaging device 1 itself. The above selection is performed by the signal processing section 7 based on various signals of the first pixel 10A as an object, for example.

The processing for each first pixel 10A in step 1002 described above is shown in detail by fig. 11. In step 1101, the signal processing unit 7 determines whether or not each of the signals R and L based on the signal charges accumulated in the photoelectric conversion elements 11R, 11L reaches a threshold value indicating that overflow occurs in the photoelectric conversion elements 11R, 11L for the first pixel 10A to be subjected. If the signals R and L do not reach the threshold value, the phase difference information of the first pixel 10A to which the first phase difference data signal is to be applied is output in step 1102. When at least one of the signals R and L reaches the threshold, the photoelectric conversion elements 11R and 11L overflow, and a reliable phase difference data signal cannot be obtained from the signals R and L, so that in step 1103, the phase difference information of the first pixel 10A to which the second phase difference data signal is targeted is output. Thereafter, in step 1104, steps 1101 to 1103 are repeated until all the first pixels 10A that can be referred to on the memory 8 output the phase difference data signal.

In the case of using the first phase difference data signal as the phase difference information of the first pixel 10A, a phase difference data signal generated by comparing the signal R and the signal L in the first pixel 10A is output.

In the case where the second phase difference data signal is used as the phase difference information of the first pixel 10A, it is determined whether or not an overflow from the photoelectric conversion elements 11R and 11L to the holding capacitor 13 occurs in each pixel constituting the second pixel 10B group, and preferably, when the overflow does not occur, the signal r+l of the second pixel 10B is used as the phase signal for generating the phase difference data signal in the group, and when the overflow occurs, the signal r+l+c of the second pixel 10B is used as the phase signal. For example, it is possible to determine whether or not overflow from the photoelectric conversion elements 11R and 11L to the storage capacitor 13 is generated by determining whether or not a threshold value indicating that overflow is generated in both the photoelectric conversion elements 11R and 11L is reached.

In addition, in the case where no overflow from the photoelectric conversion elements 11R, 11L to the holding capacitance 13 occurs, the signal charge held in the holding capacitance 13 is theoretically zero. Therefore, even in such a case, the second pixel 10A is considered to generate the signal r+l+c instead of the signal r+l as the phase signal. However, in reality, the signal r+l+c contains signal noise caused by the holding capacitance 13. Therefore, in the case where no overflow occurs in the holding capacitor 13, it is preferable to use the signal r+l instead of the signal r+l+c in order to increase the SN ratio of the phase signal as described above.

In addition, in the case where the second phase difference data signal is output as the phase difference information of the first pixel 10A, it is preferable that a device (for example, a camera device) that receives the output phase difference data signal performs appropriate complementary processing on the output phase difference data signal to perform processing equivalent to that of the phase difference data signal generated based on the signal charges accumulated in the photoelectric conversion elements 11R, 11L of the other first pixel 10A.

Thereafter, in step 1003, if there are more pixels 10 in the pixel array section 2 that are not read in the memory 8, the signal data accumulated in the memory 8 is updated, and the above steps 1001 to 1002 are repeated until all the pixels 10 included in the pixel array section 2 are read.

In the case of the third output example described above, since the phase difference data signal output by the determination of the solid-state imaging device 1 itself is selected based on whether or not overflow occurs in the photoelectric conversion elements 11R and 11L of the first pixel 10A, as compared with the second output example, a more reliable phase difference signal can be output from the solid-state imaging device 1.

The phase difference data signals output from the pixels 10 as described above can be used for, for example, automatic focusing in a camera device or the like provided with the solid-state imaging device 1. The phase difference data signal can be used for various purposes such as depth estimation (depth mapping), in addition to autofocus.

< second embodiment >

Next, a second embodiment will be described.

[ constitution of solid-state imaging device ]

The solid-state imaging device 1 according to the second embodiment of the present invention is the same as that of the first embodiment except that the relationship between the potential barriers between the two photoelectric conversion elements 11R and 11L in the pixel 10 and the potential barriers between the two photoelectric conversion elements 11R and 11L and the holding capacitance 13 is different. In the following, in the present embodiment, the same reference numerals as in the first embodiment are used to describe the constituent elements of the solid-state imaging device.

Fig. 12 shows a relationship between a potential barrier between two photoelectric conversion elements 11R, 11L and a potential barrier between the two photoelectric conversion elements 11R, 11L and a holding capacitance 13 in a pixel 10 of the solid-state imaging device 1 of the second embodiment. As shown in fig. 12, in the pixel 10 of the present embodiment, the potential barrier between the two photoelectric conversion elements 11R and 11L is higher than the potential barrier between the two photoelectric conversion elements 11R and 11L and the holding capacitance 13. Therefore, in the pixel 10 of the present embodiment, when signal charges exceeding the storable storage capacitance are generated in one of the photoelectric conversion elements 11R and 11L (for example, the photoelectric conversion element 11L) at the time when the transfer transistors 14R and 14L and the holding switching transistor 15 are turned off, the signal charges overflowing from the one photoelectric conversion element 11R and 11L first exceed the potential barrier between the lower photoelectric conversion element 11R and 11L and the holding capacitance 13, and preferentially flow into the holding capacitance 13 and are accumulated.

In the present embodiment, even in the case where only one of the photoelectric conversion elements 11R, 11L (for example, the photoelectric conversion element 11L) overflows, if the other (for example, the photoelectric conversion element 11R) does not overflow, the generation source capable of holding the signal charge accumulated in the holding capacitance 13 is the above-described one of the photoelectric conversion elements 11R, 11L (for example, the photoelectric conversion element 11L), that is, the signal charge accumulated in the holding capacitance 13 has phase information. Therefore, in this case, if the total number of signal charges accumulated in the one photoelectric conversion element 11R, 11L (for example, the photoelectric conversion element 11L) that generates overflow and the signal charges accumulated in the holding capacitance 13 are compared with the signal charges accumulated in the other photoelectric conversion element 11R, 11L (for example, the photoelectric conversion element 11R) that does not generate overflow, a reliable phase difference data signal can be generated. Therefore, according to the present embodiment, in a shooting scene where the luminance of the signal charge generated in the photoelectric conversion elements 11R and 11L overflows or the exposure time is long, an effect of generating a phase difference data signal with higher reliability than that of the first embodiment can be achieved.

[ example of driving pixels of solid-state imaging device ]

The driving time point of the pixel 10 of the present embodiment may be the same as that of the first embodiment. As in the first embodiment, the signals R, r+l, L, and r+l+c can be restored by processing the first to fifth signals obtained in the driving of the pixels 10. In the present embodiment, the signal r+c can be recovered by subtracting the signal R from the signal r+l+c, and the signal l+c can be recovered by subtracting the signal R from the signal r+l+c.

Here, in the first pixel 10A, when no overflow occurs from the photoelectric conversion elements 11R and 11L during the accumulation period Δt, the signal r+l can be used as a correct imaging data signal, and the signal R and the signal L can be used as reliable phase signals that can generate correct phase difference data signals by comparing them, as in the first embodiment.

On the other hand, in the first pixel 10A, when overflow occurs from at least one of the photoelectric conversion elements 11R, 11L during the accumulation period Δt, unlike the first embodiment, the signal r+l exceeds the signal amount that can be handled by the photoelectric conversion elements 11R, 11L, and therefore, it does not have a meaning as a captured data signal. In this case, the signal r+l+c can be used as a correct shooting data signal.

In this case, the signals R and L have no meaning as phase signals, and therefore cannot be used to generate reliable phase difference data signals. However, if an overflow occurs in only one of the photoelectric conversion elements 11R and 11L, a correct phase difference data signal can be generated by comparing a signal obtained by adding the signal C to a signal corresponding to the photoelectric conversion element 11R and 11L in the signal R, L, which has generated an overflow, and a signal corresponding to the photoelectric conversion element 11R and 11L, which has not generated an overflow. For example, when the signal charge generated in the photoelectric conversion element 11L overflows, and when the signal charge does not overflow in the photoelectric conversion element 11R, the signal R and the signal l+c are compared, a correct phase difference data signal can be generated.

In addition, when overflow occurs in both the photoelectric conversion elements 11R and 11L, the signal charges accumulated in the holding capacitance 13 overflow from both the photoelectric conversion elements 11R and 11L and the signal charges flowing out are mixed. Therefore, in such a case, the signal charge accumulated in the holding capacitance 13 cannot be used as a phase signal.

In the second pixel 10B that does not generate the photographing data signal, the signal r+l may be used as a phase signal for generating a reliable phase difference data signal in the second pixel 10B group in the case where no overflow is generated in any of the photoelectric conversion elements 11R, 11L, and the signal r+l+c may be used as a phase signal for generating a reliable phase difference data signal in the second pixel 10B group in the case where overflow is generated.

The phase difference data signal may be output from the pixel array section 2 of the solid-state imaging device 1 of the second embodiment in the same manner as the first embodiment except for the details of step 1002 of the third output example shown below. The processing for each first pixel 10A in step 1002 in the above-described second embodiment is shown in detail by fig. 13.

In step 1301, the signal processing section 7 determines whether or not each of the signals R and L based on the signal charges accumulated in the photoelectric conversion elements 11R, 11L reaches a threshold value indicating that overflow occurs in the photoelectric conversion elements 11R, 11L for the first pixel 10A that is the object.

If neither of the signals R and L reaches the threshold, a first phase difference data signal generated by comparing the signal R and the signal L in the first pixel 10A is output in step 1302.

On the other hand, when one of the signals R and L reaches the threshold value, that is, when an overflow occurs in one of the photoelectric conversion elements 11R and 11L, in step 1303, a phase difference data signal (also referred to as a first phase difference signal to which an overflow capacitance is added) generated by comparing a signal obtained by adding the signal C to a signal corresponding to the photoelectric conversion element 11R and 11L in which an overflow occurs in the signal R, L in the first pixel 10A and a signal corresponding to the photoelectric conversion element 11R and 11L in which an overflow does not occur is output.

When both the signals R and L reach the threshold value, the signal charges overflowing from both the photoelectric conversion elements 11R and 11L flow into the holding capacitor 13, and the signal C based on the holding capacitor 13 does not have phase information, so that the second phase difference data signal is output as the phase difference information of the first pixel 10A to be subjected to step 1304. The above 1304 can be performed in the same manner as in step 1103 of the first embodiment.

Thereafter, in step 1305, steps 1301 to 1304 are repeated until all the first pixels 10A which can be referred to on the memory 8 output phase difference data signals.

The solid-state imaging device according to the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications are possible within the scope of the present invention. For example, the configuration of one embodiment may be added to the configuration of another embodiment, and a part of the configuration of one embodiment may be replaced with the configuration of another embodiment. Further, a part of the constitution of an embodiment may be deleted.

Specifically, in the first and second embodiments described above, as the second pixels 10B constituting the combination of two or more second pixels 10B configured to be able to generate the phase difference data signal of the received light, a pixel group in which the light receiving surface of the pixel is partially shielded by the opaque film 60 may be used, but the second pixels in the present invention are not limited to this.

For example, as in the examples shown in fig. 14 and 15, a combination of two or more second pixels 10B 'sharing one on-chip lens 30' may be employed as the second pixel group. In the above example, in the pixel array section 2', two second pixels 10B' are adjacent to each other to form a group, and one on-chip lens 30 'is independently provided in each of the second pixel 10B' groups. In the above example, the signal charges generated by the second pixels 10B' can be processed in the same manner as in the first and second embodiments described above, and the phase difference data signal can be output.

In the first and second embodiments described above, the pixel 10 includes two photoelectric conversion elements 11R and 11L, but the number of photoelectric conversion elements included in the pixel 10 is not limited to two, and may be three or more. Further, the pixels including two or more photoelectric conversion elements 11R and 11L are only the first pixels 10A, and the second pixels 10B may include only one photoelectric conversion element.

The terms of directions such as "up", "down", "left" and "right" in the above-described embodiments are not limited to the directions of the embodiments of the present invention, unless otherwise specified.

While the present invention has been described in detail and with reference to the drawings, those skilled in the art will recognize that changes and/or modifications of the above-described embodiments can be made easily. Accordingly, unless a change or modification by a person skilled in the art deviates from the level of the claims described in the claims, the change or modification is to be construed as being included in the scope of the claims.

Reference numerals illustrate:

1 … solid-state imaging device, 2 … pixel array section, 21 … row signal line, 22 … column signal line, 3 … vertical drive section, 4 … column signal processing section, 5 … horizontal drive section, 6 … control section, 7 … signal processing section, 8 … memory (storage section), 10A, 10B … pixels, 11R, 11L … photoelectric conversion element, 12 … floating diffusion region, 13 … holding capacitance, 14R, 14L … transfer transistor (first switching transistor), 15 … holding switching transistor, first holding switching transistor (second switching transistor), 16 … reset transistor (third switching transistor), 17 … amplifying transistor, 18 … selection transistor, 20 … semiconductor region, 30 … upper lens, 40 … color filter, 50 TX … transparent film, 60 … opaque film, SF … source follower circuit, VDD1 … reset power (reset), 2 … power supply, RES, phi S, VDD phi S, SEL, and Tx phi S, R phi S, and phi S, respectively

Claims

A solid-state imaging device is characterized in that,

comprises a plurality of first pixels and a plurality of second pixels different from the plurality of first pixels,

each of the plurality of first pixels and the plurality of second pixels includes:

one or more photoelectric conversion elements that constitute a light receiving surface of the pixel and generate electric charges by photoelectrically converting received light;

a floating diffusion region connected to the one or more photoelectric conversion elements, the floating diffusion region converting the electric charge into a voltage corresponding to an amount of the electric charge; and

a holding capacitance that is connected to the floating diffusion region and is capable of accumulating the electric charges overflowing from the one or more photoelectric conversion elements,

each of the plurality of first pixels is configured to include two or more photoelectric conversion elements each connected to the floating diffusion region, and phase difference data signals can be generated by comparing the charges accumulated in the two or more photoelectric conversion elements,

more than two second pixels among the plurality of second pixels together constitute a second pixel group,

the second pixel group is configured to be able to generate a phase difference data signal by comparing the electric charges accumulated in each of the second pixels constituting the second pixel group, respectively.
The solid-state imaging device according to claim 1, wherein,

in each of the two or more pixels constituting the second pixel group, a portion of the light receiving surface of the pixel is blocked to prevent light from being received at the portion of the light receiving surface.
The solid-state imaging device according to claim 1, wherein,

a separate one of the on-chip lenses is provided in each of the plurality of first pixels,

an independent one on-chip lens is provided in each of the second pixel groups, and the two or more pixels constituting the second pixel group share the one on-chip lens.
The solid-state imaging device according to any one of claims 1 to 3, wherein,

in each of the plurality of first pixels, a potential barrier between the two or more photoelectric conversion elements is lower than a potential barrier between the photoelectric conversion elements and the holding capacitance.
The solid-state imaging device according to claim 4, wherein,

in each of the plurality of second pixels,

when the total number of charges accumulated in the one or more photoelectric conversion elements is equal to or less than a predetermined saturation charge amount, a phase difference data signal is generated based on the total number of charges accumulated in the one or more photoelectric conversion elements,

When the total number of charges accumulated in the one or more photoelectric conversion elements is larger than a predetermined saturation charge amount, a phase difference data signal is generated based on the total number of charges accumulated in the one or more photoelectric conversion elements and the total number of charges accumulated in the holding capacitance.
The solid-state imaging device according to any one of claims 1 to 5, wherein,

in each of the plurality of first pixels,

the potential barrier between the two or more photoelectric conversion elements is higher than the potential barrier between the photoelectric conversion elements and the holding capacitance.
The solid-state imaging device according to claim 6, wherein,

in each of the plurality of second pixels,

when all of the charges accumulated in the one or more photoelectric conversion elements are equal to or less than a predetermined saturation charge amount, a phase difference data signal is generated based on the total number of charges accumulated in the one or more photoelectric conversion elements,

when the charge accumulated in any one of the one or more photoelectric conversion elements is greater than a predetermined saturation charge amount, a phase difference data signal is generated based on the total number of the charges accumulated in the one or more photoelectric conversion elements and the charges accumulated in the holding capacitance.
The solid-state imaging device according to any one of claims 1 to 7, wherein,

the solid-state imaging device, for each of the plurality of first pixels,

judging whether or not the electric charges held by each of the two or more photoelectric conversion elements reach a threshold value indicating that overflow occurs in the photoelectric conversion element, outputting, in the first pixel, a phase difference data signal generated based on the electric charges generated in the two or more photoelectric conversion elements if the threshold value is not reached, and outputting, in the case where at least one of the two or more photoelectric conversion elements reaches the threshold value, a phase difference data signal generated based on the electric charges generated in the second pixel group determined by the solid-state imaging device.
A camera apparatus, characterized by comprising:

the solid-state imaging device according to any one of claims 1 to 8

A control device configured to control the solid-state imaging device.
The camera device of claim 9, wherein,

based on a signal from the control device, it is determined whether the solid-state imaging device outputs a phase difference data signal for each pixel based on the electric charges generated in the two or more photoelectric conversion elements provided in the first pixel, and/or whether the solid-state imaging device outputs a phase difference data signal for each pixel based on the electric charges generated in the two or more second pixel groups.
The solid-state imaging device according to claim 9 or 10, wherein,

the camera device is a mobile terminal.