CN111885320A - Image sensor, automatic exposure method thereof and electronic equipment - Google Patents
Image sensor, automatic exposure method thereof and electronic equipment Download PDFInfo
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- CN111885320A CN111885320A CN202010773418.1A CN202010773418A CN111885320A CN 111885320 A CN111885320 A CN 111885320A CN 202010773418 A CN202010773418 A CN 202010773418A CN 111885320 A CN111885320 A CN 111885320A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/50—Control of the SSIS exposure
- H04N25/57—Control of the dynamic range
- H04N25/58—Control of the dynamic range involving two or more exposures
- H04N25/587—Control of the dynamic range involving two or more exposures acquired sequentially, e.g. using the combination of odd and even image fields
- H04N25/589—Control of the dynamic range involving two or more exposures acquired sequentially, e.g. using the combination of odd and even image fields with different integration times, e.g. short and long exposures
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
- H04N25/50—Control of the SSIS exposure
- H04N25/57—Control of the dynamic range
- H04N25/58—Control of the dynamic range involving two or more exposures
- H04N25/581—Control of the dynamic range involving two or more exposures acquired simultaneously
- H04N25/583—Control of the dynamic range involving two or more exposures acquired simultaneously with different integration times
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Abstract
The embodiment of the application provides an image sensor, an automatic exposure method thereof and electronic equipment, wherein the image sensor comprises a pixel array and a control circuit, the pixel array comprises at least one first pixel and at least one second pixel, and under the application scene of the same illumination intensity, a first light incoming amount sensed by the first pixel is lower than a second light incoming amount sensed by the second pixel; the control circuit is used for generating a first exposure control signal according to the first light incoming quantity and adjusting the first exposure time of the at least one first pixel according to the first exposure control signal; generating a second exposure control signal according to the second light incoming amount, and adjusting a second exposure time of the at least one second pixel according to the second exposure control signal; the first exposure time is different from the second exposure time.
Description
Technical Field
The embodiment of the application relates to the field of image processing, in particular to an image sensor, an automatic exposure method thereof and electronic equipment.
Background
Because the photosensitive effect of the image sensor is closely related to the illumination intensity of the application scene where the image sensor is located, in recent years, in order to meet the shooting requirements of application scenes with different illumination intensities, the image sensor of the electronic equipment realizes a better image effect by setting an automatic exposure strategy. Referring to fig. 1a, a typical image sensor pixel array includes: and the color pixels are composed of red pixels, green pixels and blue pixels. Referring to fig. 1b, the exposure strategy is to determine an exposure control signal according to the amount of light entering the color pixel, i.e., if the gray-scale value of the pixel sensed by the color pixel does not reach the target value, the exposure control signal extends the exposure time of the color pixel until the amount of light entering the color pixel reaches the target value, and the exposure of the gray-scale value of the output pixel is finished.
Referring to fig. 2a and 2b, the image sensor is suitable for use in low illumination intensity, and since the pixel array includes a white pixel, and the amount of light entering sensed by the white pixel is greater than that of the color pixels, the white pixel and the color pixels both use the same exposure control signal to control the exposure time, which may cause overexposure of the white pixel, and affect the image effect obtained by the image sensor.
Disclosure of Invention
In view of the above, an object of the present invention is to provide an image sensor, an automatic exposure method thereof and an electronic device, which overcome all or part of the above-mentioned disadvantages.
In a first aspect, an embodiment of the present application provides an image sensor, including a pixel array and a control circuit, where the pixel array includes at least one first pixel and at least one second pixel, and a first incident light amount sensed by the first pixel is lower than a second incident light amount sensed by the second pixel under the same illumination intensity; the control circuit is used for generating a first exposure control signal according to the first light incoming quantity and adjusting the first exposure time of the at least one first pixel according to the first exposure control signal; generating a second exposure control signal according to the second light incoming amount, and adjusting a second exposure time of the at least one second pixel according to the second exposure control signal; the first exposure time is different from the second exposure time.
In a second aspect, an embodiment of the present application provides an automatic exposure control method for an image sensor, where the method includes: at least one first pixel senses a first light entering amount, at least one second pixel senses a second light entering amount, and under the same illumination intensity, the first light entering amount sensed by the first pixel is lower than the second light entering amount sensed by the second pixel; generating a first exposure control signal according to the first light inlet quantity, and adjusting the first exposure time of the at least one first pixel according to the first exposure control signal; generating a second exposure control signal according to the second light incoming amount, and adjusting a second exposure time of the at least one second pixel according to the second exposure control signal; the first exposure time is different from the second exposure time.
In a third aspect, an embodiment of the present application provides a data processing system, including: the image sensor described above.
In the embodiment of the application, because the first pixel and the second pixel sense different light entering amounts under the same illumination intensity, the control circuit respectively controls the exposure time of the first pixel and the exposure time of the second pixel by using the first exposure control signal and the second exposure control signal, and the second pixel with higher light entering amount obtains the second exposure time different from the first exposure time, so that the second pixel sensing higher light entering amount is prevented from being over exposed. According to the embodiment of the application, the exposure time control of the first pixel and the second pixel sensing different light incoming quantities can be realized according to the illumination intensity of an application scene, the poor image quality caused by overexposure of the second pixel is avoided, and the better automatic exposure effect is realized.
Drawings
Some specific embodiments of the present application will be described in detail hereinafter by way of illustration and not limitation with reference to the accompanying drawings. The same reference numbers in the drawings identify the same or similar elements or components. Those skilled in the art will appreciate that the drawings are not necessarily drawn to scale. In the drawings:
FIG. 1a is a schematic diagram of a pixel array of a related art image sensor;
FIG. 1b is a flow chart illustrating automatic exposure control of the pixel array of FIG. 1 a;
FIG. 2a is a schematic diagram of another related art image sensor pixel array;
FIG. 2b is a schematic diagram of the light incident amount of each pixel in FIG. 2 a;
fig. 3 is a schematic diagram of an image sensor according to an embodiment of the present disclosure;
fig. 4 is a schematic diagram of a pixel array in an image sensor according to an embodiment of the present disclosure;
FIGS. 5 a-5 c are schematic diagrams of an image sensor with color pixels and white pixels according to an embodiment of the present application;
fig. 6 is a schematic diagram of a control circuit in another image sensor according to an embodiment of the present disclosure;
fig. 7 is a schematic diagram of a control circuit in another image sensor according to an embodiment of the present disclosure;
fig. 8a is a schematic diagram of a pixel array in an image sensor in an application scenario with high illumination intensity according to an embodiment of the present application;
fig. 8b is a schematic diagram of a pixel array in an image sensor in an application scenario with low illumination intensity according to an embodiment of the present disclosure;
fig. 9 is a schematic diagram of an exposure control circuit of a pixel array in an image sensor according to an embodiment of the present disclosure;
FIG. 10a is a diagram illustrating a first voltage timing control signal;
FIG. 10b is a diagram illustrating a second voltage timing control signal;
fig. 11 is a flowchart of an automatic exposure method for an image sensor according to an embodiment of the present disclosure;
fig. 12 is a flowchart of an implementation of step S2 in an automatic exposure method for an image sensor according to an embodiment of the present application;
fig. 13 is a flowchart of an implementation of step S3 in another automatic exposure method for an image sensor according to an embodiment of the present application.
Detailed Description
In the embodiment of the application, because the first pixel and the second pixel sense different light entering amounts under the same illumination intensity, the control circuit respectively controls the exposure time of the first pixel and the exposure time of the second pixel by using the first exposure control signal and the second exposure control signal, and the second pixel with higher light entering amount obtains the second exposure time different from the first exposure time, so that the second pixel sensing higher light entering amount is prevented from being over exposed. According to the embodiment of the application, the exposure time control of the first pixel and the second pixel sensing different light incoming quantities can be realized according to the illumination intensity of an application scene, the poor image quality caused by overexposure of the second pixel is avoided, and the better automatic exposure effect is realized.
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application.
Fig. 3 is a schematic diagram of an image sensor according to an embodiment of the present disclosure. As shown in fig. 3, the image sensor includes a pixel array 31 and a control circuit 32, the pixel array includes at least one first pixel and at least one second pixel, and a first incident light amount sensed by the first pixel is lower than a second incident light amount sensed by the second pixel under the same illumination intensity. The control circuit is used for generating a first exposure control signal according to the first light incoming quantity and adjusting the first exposure time of at least one first pixel according to the first exposure control signal; generating a second exposure control signal according to the second light incoming quantity, and adjusting the second exposure time of at least one second pixel according to the second exposure control signal; the first exposure time is different from the second exposure time.
The image sensor in the embodiment of the application is suitable for a CCD image sensor or a CMOS image sensor.
The image sensor in the embodiment of the application can be included in the portable electronic device. The portable electronic device includes: notebook computers, cell phones, tablets, digital cameras, video cameras, wearable devices, and the like.
The pixel array 31 includes: color pixels, white pixels, phase detection pixels. The color pixel includes: red pixels, green pixels, and blue pixels. Each pixel in the pixel array includes a plurality of photodiodes, and other photoelectric conversion elements may be adopted instead of the photodiodes.
Illustratively, referring to fig. 4, a pixel 41 in the pixel array may include two photodiodes L and S operating independently of each other, L representing a photodiode that can generate a long-exposure image signal and S representing a photodiode that can generate a short-exposure image signal.
Under the same illumination intensity, the first pixel and the second pixel sense different light entering amounts, so that the control circuit respectively controls the exposure time of the first pixel and the second pixel by adopting the first exposure control signal and the second exposure control signal, and the second pixel with higher light entering amount obtains the second exposure time different from the first exposure time, thereby avoiding the second pixel sensing higher light entering amount from being over exposed. According to the embodiment of the application, the exposure time control of the first pixel and the second pixel sensing different light incoming quantities can be realized according to the illumination intensity of an application scene, the poor image quality caused by overexposure of the second pixel is avoided, and the better automatic exposure effect is realized.
Specifically, the first pixel is a color pixel, and the second pixel is a white pixel or a phase detection pixel.
The color pixel includes: red pixels, blue pixels, green pixels. The micro-lenses and the color filters are usually disposed above the color pixels. A white filter or no filter is disposed over the white pixels.
Under the same illumination intensity, the first incident light quantity sensed by the color pixel is lower than the second incident light quantity sensed by the white pixel or the phase detection pixel due to the color filter or the coating film of the color pixel. Since the first light-entering amount is lower than the second light-entering amount, if the exposure time of the color pixel and the white pixel or the phase detection pixel is controlled by the same exposure control signal, the white pixel or the phase detection pixel having a larger light-entering amount is overexposed. In order to avoid overexposure of the white pixel or the phase detection pixel, in the embodiment of the application, different control units are adopted for the color pixel and the white pixel or the phase detection pixel to generate different exposure control signals, so as to control the exposure time of the color pixel and the exposure time of the white pixel or the phase detection pixel respectively.
For example, an image sensor having color pixels and white pixels to which the embodiments of the present application are applicable is shown in fig. 5a to 5 c.
In a specific embodiment of the present application, referring to fig. 6, the control circuit 32 includes:
a first control unit 321 for generating a first gray scale value according to the sensed first light incoming amount; if the first gray value is smaller than the first reference value, the first exposure control signal prolongs the first exposure time to increase the first gray value to the first reference value; when the first gray value is equal to the first reference value, the first exposure control signal ends exposure; when the first gray value is larger than the first reference value, the first exposure control signal shortens the first exposure time to reduce the first gray value to the first reference value.
Specifically, the embodiment of the present application performs a photoelectric conversion and an analog-to-digital conversion on the first incident light amount sensed by the color pixel, and generates a digitized first gray scale value. The longer the exposure time, the larger the first incident light amount sensed by the color pixel, and the larger the first gray scale value. And comparing the digitized first gray value with a first reference value, wherein when the first gray value is smaller than the first reference value, the color pixel cannot sense enough first incident light quantity, and the first exposure time is prolonged to increase the first gray value to the first reference value. When the first gray value is equal to the first reference value, it indicates that the color pixel senses a sufficient first incident light amount, and the first exposure control signal ends the exposure. When the first gray value is greater than the first reference value, it indicates that the color pixel senses an excessive first incident light amount, which may cause overexposure, and the first exposure time is shortened to reduce the first gray value to the first reference value.
According to the embodiment of the application, the first control unit independently senses the first light incoming amount to generate the first gray scale value, and the first exposure time of the color pixel can be adjusted independently according to the comparison between the first light incoming amount sensed by the color pixel and the first reference value, so that the independent control of the first exposure time of the color pixel is realized.
Specifically, in yet another specific implementation of the present application, the first gray scale value is: and selecting at least one of the gray value of the brightness channel, the gray value of the red pixel channel, the gray value of the green pixel channel and the gray value of the blue pixel channel according to the illumination intensity.
Specifically, the luminance channel gray value is obtained by performing accumulation calculation with a certain coefficient according to the red pixel channel gray value, the green pixel channel gray value, and the blue pixel channel gray value, and the specific calculation manner is an existing luminance channel gray value calculation manner selected by a person skilled in the art as needed, which is not described herein again.
According to the method, at least one of the gray value of the brightness channel, the gray value of the red pixel channel, the gray value of the green pixel channel and the gray value of the blue pixel channel is selected as a first gray value according to the illumination intensity.
For example, if the application scene of the illumination intensity is a green strong illumination application scene, the luminance channel grayscale value and the green pixel channel grayscale value are taken as the first grayscale values to be compared with the respective first reference values respectively. When both are smaller than the respective first reference values, the first exposure control signal extends the first exposure time. When one of the two is larger than the first reference value, the first exposure control signal shortens the first exposure time. When one of the two is equal to the first reference value, the exposure is ended. Therefore, in the application scene of the green strong illumination, the gray value of the brightness channel and the gray value of the green pixel channel are used as the first gray values to be compared with the respective first reference values respectively, so that the phenomenon that when the gray value of the red pixel channel or the gray value of the blue pixel channel is used as the first gray value to be compared with the respective first reference values, the green pixel is overexposed due to the fact that the incident light quantity of the green light sensed by the green pixel is too large is avoided. Therefore, in the embodiment of the present application, at least one of the grayscale values of the luminance channel, the grayscale value of the red pixel channel, the grayscale value of the green pixel channel, and the grayscale value of the blue pixel channel is selected as the first grayscale value according to the application scenes with different illumination intensities.
For example, if the application scene of the illumination intensity is an application scene of uniform illumination, the luminance channel gray value is used as the first gray value to compare with the first reference value. When the gray value of the brightness channel is smaller than the first reference value, the first exposure control signal prolongs the first exposure time. When the gray value of the brightness channel is larger than the first reference value, the first exposure control signal shortens the first exposure time. And when the gray value of the brightness channel is equal to the first reference value, ending the exposure. Therefore, the luminance channel gray value is directly adopted as the first gray value in the application scene with uniform illumination, and overexposure of the red pixel, the blue pixel and the green pixel is avoided. Therefore, in the embodiment of the present application, at least one of the grayscale values of the luminance channel, the grayscale value of the red pixel channel, the grayscale value of the green pixel channel, and the grayscale value of the blue pixel channel is selected as the first grayscale value according to the application scenes with different illumination intensities.
Specifically, the first reference value is a preset fixed value, and is set by a person skilled in the art according to experience.
In yet another specific implementation of the present application, referring to fig. 7, the control circuit 32 includes:
a second control unit 322 for generating a second gray scale value according to the sensed second amount of incoming light; when the second gray value is smaller than the second reference value, the second exposure control signal is made to prolong the second exposure time so as to increase the second gray value to the second reference value; when the second gray value is equal to the second reference value, the second exposure control signal ends the exposure; when the second gray scale value is greater than the second reference value, the second exposure control signal shortens the second exposure time to reduce the second gray scale value to the second reference value.
Specifically, the embodiment of the present application performs photoelectric conversion and analog-to-digital conversion on the second incident light amount sensed by the white pixel or the phase detection pixel, and generates a digitized second gray scale value. The longer the exposure time, the larger the second incident light amount sensed by the white pixel or the phase detection pixel, and the larger the second gray scale value. And comparing the digitized second gray scale value with a second reference value, and when the second gray scale value is smaller than the second reference value, indicating that the white pixel or the phase detection pixel cannot sense enough second incident light quantity, and prolonging the second exposure time to increase the second gray scale value to the second reference value. When the second gray value is equal to the second reference value, it indicates that the color pixel senses a sufficient second incident light amount, and the second exposure control signal ends the exposure. When the second gray scale value is greater than the second reference value, it indicates that the color pixel senses an excessive second incident light amount, which may cause overexposure, and the second exposure time is shortened to reduce the second gray scale value to the second reference value. .
In the embodiment of the application, the second control unit individually senses the second incident light quantity to generate the second gray scale value, and the second exposure time of the white pixel or the phase detection pixel can be adjusted by comparing the second incident light quantity sensed by the white pixel or the phase detection pixel with the second reference value, so that the second exposure time of the white pixel or the phase detection pixel can be individually controlled.
The second gray scale value is: a white pixel channel gray scale value or a phase detection pixel channel gray scale value.
Specifically, the second reference value is a preset fixed value, and is set by a person skilled in the art according to experience.
According to the embodiment of the application, the second exposure time of the white pixel or the phase detection pixel is controlled by generating the second exposure control signal by the second control unit different from the color pixel, so that the second exposure time of the white pixel or the phase detection pixel can be adjusted more flexibly according to the light inlet amount of the white pixel or the phase detection pixel. The embodiment of the application avoids the overexposure condition of the white pixel or the phase detection pixel caused by exposing the white pixel or the phase detection pixel by adopting the exposure time of the color pixel, and improves the image effect sensed by the image sensor.
For example, referring to fig. 8a, in an application scenario with high illumination intensity, the exposure of the white pixel is controlled to have a short second exposure time by the photodiode S generating a short-exposure image signal, i.e. the second exposure control signal of the white pixel. Referring to fig. 8b, in the application scenario of low light intensity, the exposure of the white pixel uses the photodiode L generating the long-exposure image signal, i.e. the second exposure control signal of the white pixel controls the second exposure time to be long.
In yet another specific implementation of the present application, the first exposure control signal is a first voltage timing control signal.
In yet another specific implementation of the present application, the second exposure control signal is a second voltage timing control signal.
Since each pixel in the pixel array includes a plurality of photodiodes, other photoelectric conversion elements may be adopted instead of the photodiodes. The voltage time sequence control signal is used as the exposure control signal, so that the exposure time of the photodiode of the pixel can be controlled.
Illustratively, referring to fig. 9, the photodiode PD of the pixel has its exposure time controlled by an exposure control circuit 901. The first exposure control signal is the first voltage timing control signal shown in fig. 10a, and the second exposure control signal is the second voltage timing control signal shown in fig. 10 b. The first voltage timing control signal or the second voltage timing control signal controls the first exposure time T1 or the second exposure time T2 of the photodiode PD of the pixel by controlling the RST voltage and other element voltages in the exposure control circuit 801.
The exposure control circuit 901 is a 4T circuit commonly used for controlling the exposure time of the photodiode PD of the pixel, and therefore, the embodiment of the present application will not be described again.
Corresponding to the above-mentioned photoelectric sensor, the present application also provides an automatic exposure method for an image sensor, referring to fig. 11, the method includes:
s1, the first pixel senses a first light entering amount, the second pixel senses a second light entering amount, and the first light entering amount is lower than the second light entering amount under the same illumination intensity.
S2, generating a first exposure control signal according to the first light-entering amount, and adjusting a first exposure time of at least one first pixel according to the first exposure control signal.
And S3, generating a second exposure control signal according to the second light incoming quantity, and adjusting a second exposure time of at least one second pixel according to the second exposure control signal, wherein the first exposure time is different from the second exposure time.
Under the same illumination intensity, the first pixel and the second pixel sense different light entering amounts, so that the control circuit respectively controls the exposure time of the first pixel and the second pixel by adopting the first exposure control signal and the second exposure control signal, and the second pixel with higher light entering amount obtains the second exposure time different from the first exposure time, thereby avoiding the second pixel sensing higher light entering amount from being over exposed. According to the embodiment of the application, the exposure time control of the first pixel and the second pixel sensing different light incoming quantities can be realized according to the illumination intensity of an application scene, the poor image quality caused by overexposure of the second pixel is avoided, and the better automatic exposure effect is realized.
Specifically, the first pixel is a color pixel, and the second pixel is a white pixel or a phase detection pixel.
The color pixel includes: red pixels, blue pixels, green pixels. The micro-lenses and the color filters are usually disposed above the color pixels. A white filter or no filter is disposed over the white pixels.
Under the same illumination intensity, the first incident light quantity sensed by the color pixel is lower than the second incident light quantity sensed by the white pixel or the phase detection pixel due to the color filter or the coating film of the color pixel. Since the first light-entering amount is lower than the second light-entering amount, if the exposure time of the color pixel and the white pixel or the phase detection pixel is controlled by the same exposure control signal, the white pixel or the phase detection pixel having a larger light-entering amount is overexposed. In order to avoid overexposure of the white pixel or the phase detection pixel, in the embodiment of the application, different control units are adopted for the color pixel and the white pixel or the phase detection pixel to generate different exposure control signals, so as to control the exposure time of the color pixel and the exposure time of the white pixel or the phase detection pixel respectively.
In one embodiment of the present application, referring to fig. 12, step S2 includes:
and S21, generating a first gray scale value according to the sensed first light incoming amount.
S22, when the first gray value is smaller than the first reference value, the first exposure control signal extends the first exposure time to increase the first gray value to the first reference value.
S23, the first exposure control signal ends the exposure when the first gray value is equal to the first reference value.
S24, when the first gray value is greater than the first reference value, the first exposure control signal shortens the first exposure time to decrease the first gray value.
Specifically, the embodiment of the present application performs a photoelectric conversion and an analog-to-digital conversion on the first incident light amount sensed by the color pixel, and generates a digitized first gray scale value. The longer the exposure time, the larger the first incident light amount sensed by the color pixel, and the larger the first gray scale value. Thereby comparing the digitized first gray value with the first reference value. When the first gray value is smaller than the first reference value, it indicates that the color pixel fails to sense the sufficient first incident light amount, and the first exposure time is extended to increase the first gray value to the first reference value. When the first gray value is equal to the first reference value, it indicates that the color pixel senses a sufficient first incident light amount, and the first exposure control signal ends the exposure. When the first gray value is greater than the first reference value, it indicates that the color pixel senses an excessive first incident light amount, which may cause overexposure, and the first exposure time is shortened to reduce the first gray value to the first reference value.
According to the embodiment of the application, the first control unit independently senses the first light incoming amount to generate the first gray scale value, and the first exposure time of the color pixel can be adjusted independently according to the comparison between the first light incoming amount sensed by the color pixel and the first reference value, so that the independent control of the first exposure time of the color pixel is realized.
In yet another specific implementation of the present application, the first gray scale value is: and selecting at least one of the gray value of the brightness channel, the gray value of the red pixel channel, the gray value of the green pixel channel and the gray value of the blue pixel channel according to the illumination intensity.
Specifically, the luminance channel gray value is obtained by performing accumulation calculation with a certain coefficient according to the red pixel channel gray value, the green pixel channel gray value, and the blue pixel channel gray value, and the specific calculation manner is an existing luminance channel gray value calculation manner selected by a person skilled in the art as needed, which is not described herein again.
According to the method, at least one of the gray value of the brightness channel, the gray value of the red pixel channel, the gray value of the green pixel channel and the gray value of the blue pixel channel is selected as a first gray value according to the illumination intensity.
For example, if the application scene of the illumination intensity is a green strong illumination application scene, the luminance channel grayscale value and the green pixel channel grayscale value are taken as the first grayscale values to be compared with the respective first reference values respectively. When both are smaller than the respective first reference values, the first exposure control signal extends the first exposure time. When one of the two is larger than the first reference value, the first exposure control signal shortens the first exposure time. When one of the two is equal to the first reference value, the exposure is ended. Therefore, in the application scene of the green strong illumination, the gray value of the brightness channel and the gray value of the green pixel channel are used as the first gray values to be compared with the respective first reference values respectively, so that the phenomenon that when the gray value of the red pixel channel or the gray value of the blue pixel channel is used as the first gray value to be compared with the respective first reference values, the green pixel is overexposed due to the fact that the incident light quantity of the green light sensed by the green pixel is too large is avoided. Therefore, in the embodiment of the present application, at least one of the grayscale values of the luminance channel, the grayscale value of the red pixel channel, the grayscale value of the green pixel channel, and the grayscale value of the blue pixel channel is selected as the first grayscale value according to the application scenes with different illumination intensities.
For example, if the application scene of the illumination intensity is an application scene of uniform illumination, the luminance channel gray value is used as the first gray value to compare with the first reference value. When the gray value of the brightness channel is smaller than the first reference value, the first exposure control signal prolongs the first exposure time. When the gray value of the brightness channel is larger than the first reference value, the first exposure control signal shortens the first exposure time. And when the gray value of the brightness channel is equal to the first reference value, ending the exposure. Therefore, the luminance channel gray value is directly adopted as the first gray value in the application scene with uniform illumination, and overexposure of the red pixel, the blue pixel and the green pixel is avoided. Therefore, in the embodiment of the present application, at least one of the grayscale values of the luminance channel, the grayscale value of the red pixel channel, the grayscale value of the green pixel channel, and the grayscale value of the blue pixel channel is selected as the first grayscale value according to the application scenes with different illumination intensities.
Specifically, the first reference value is a preset fixed value, and is set by a person skilled in the art according to experience.
In yet another specific implementation of the present application, referring to fig. 13, step S3 includes:
s31, generating a second gray scale value according to the sensed second light incoming amount;
s32, when the second gray scale value is smaller than the second reference value, the second exposure control signal is extended by the second exposure time to increase the second gray scale value to the second reference value.
And S33, the second exposure control signal ends the exposure when the second gray scale value is equal to the second reference value.
S34, when the second gray scale value is greater than or equal to the second reference value, the second exposure control signal shortens the second exposure time to decrease the second gray scale value to the second reference value.
Specifically, the embodiment of the present application performs photoelectric conversion and analog-to-digital conversion on the second incident light amount sensed by the white pixel or the phase detection pixel, and generates a digitized second gray scale value. The longer the exposure time, the larger the second incident light amount sensed by the white pixel or the phase detection pixel, and the larger the second gray scale value. And comparing the digitized second gray scale value with a second reference value, and when the second gray scale value is smaller than the second reference value, indicating that the white pixel or the phase detection pixel cannot sense enough second incident light quantity, and prolonging the second exposure time to increase the second gray scale value to the second reference value. When the second gray value is equal to the second reference value, it indicates that the color pixel senses a sufficient second incident light amount, and the second exposure control signal ends the exposure. When the second gray scale value is greater than the second reference value, it indicates that the color pixel senses an excessive second incident light amount, which may cause overexposure, and the second exposure time is shortened to reduce the second gray scale value to the second reference value.
In the embodiment of the application, the second control unit individually senses the second incident light quantity to generate the second gray scale value, and the second exposure time of the white pixel or the phase detection pixel can be adjusted by comparing the second incident light quantity sensed by the white pixel or the phase detection pixel with the second reference value, so that the second exposure time of the white pixel or the phase detection pixel can be individually controlled.
The second gray scale value is: a white pixel channel gray scale value or a phase detection pixel channel gray scale value.
Specifically, the second reference value is a preset fixed value, and is set by a person skilled in the art according to experience.
According to the embodiment of the application, the second exposure time of the white pixel or the phase detection pixel is controlled by generating the second exposure control signal by the second control unit different from the color pixel, so that the second exposure time of the white pixel or the phase detection pixel can be adjusted more flexibly according to the light inlet amount of the white pixel or the phase detection pixel. The embodiment of the application avoids the overexposure condition of the white pixel or the phase detection pixel caused by exposing the white pixel or the phase detection pixel by adopting the exposure time of the color pixel, and improves the image effect sensed by the image sensor.
For example, referring to fig. 8a, in an application scenario with high illumination intensity, the exposure of the white pixel is controlled to have a short second exposure time by the photodiode S generating a short-exposure image signal, i.e. the second exposure control signal of the white pixel. Referring to fig. 8b, in the application scenario of low light intensity, the exposure of the white pixel uses the photodiode L generating the long-exposure image signal, i.e. the second exposure control signal of the white pixel controls the second exposure time to be long.
In yet another specific implementation of the present application, the first exposure control signal is a first voltage timing control signal.
In yet another specific implementation of the present application, the second exposure control signal is a second voltage timing control signal.
Since each pixel in the pixel array includes a plurality of photodiodes, other photoelectric conversion elements may be adopted instead of the photodiodes. The voltage time sequence control signal is used as the exposure control signal, so that the exposure time of the photodiode of the pixel can be controlled.
Illustratively, referring to fig. 11, the photodiode PD of a pixel has its exposure time controlled by an exposure control circuit 901. The first exposure control signal is the first voltage timing control signal shown in fig. 10a, and the second exposure control signal is the second voltage timing control signal shown in fig. 10 b. The first voltage timing control signal or the second voltage timing control signal controls the first exposure time T1 or the second exposure time T2 of the photodiode PD of the pixel by controlling the RST voltage and other element voltages in the exposure control circuit 901.
The exposure control circuit 601 is a 4T circuit generally used for controlling the exposure time of the photodiode PD of the pixel, and is not described in detail in the embodiment of the present application.
Corresponding above-mentioned photoelectric sensor, this application still provides an electronic equipment, and electronic equipment includes: the image sensor of any of the above embodiments.
It should be understood that the specific examples in the embodiments of the present application are for the purpose of promoting a better understanding of the embodiments of the present application and are not intended to limit the scope of the embodiments of the present application.
It is to be understood that the terminology used in the embodiments of the present application and the appended claims is for the purpose of describing particular embodiments only and is not intended to be limiting of the embodiments of the present application. For example, as used in the examples of this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in this application, it should be understood that the disclosed system, apparatus, and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, a division of a unit is merely a logical division, and an actual implementation may have another division, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
Units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (13)
1. An image sensor includes a pixel array and a control circuit,
the pixel array comprises at least one first pixel and at least one second pixel, and under the same illumination intensity, a first light incoming amount sensed by the first pixel is lower than a second light incoming amount sensed by the second pixel;
the control circuit is used for generating a first exposure control signal according to the first light incoming quantity and adjusting the first exposure time of the at least one first pixel according to the first exposure control signal; generating a second exposure control signal according to the second light incoming amount, and adjusting a second exposure time of the at least one second pixel according to the second exposure control signal; the first exposure time is different from the second exposure time.
2. The image sensor according to claim 2, wherein the first pixel is a color pixel, and the second pixel is a white pixel or a phase detection pixel.
3. The image sensor of claim 2, wherein the control circuit comprises:
a first control unit for generating a first gray scale value according to the sensed first light entering amount; when the first gray value is smaller than a first reference value, the first exposure control signal prolongs the first exposure time to increase the first gray value to the first reference value; when the first gray value is equal to the first reference value, the first exposure control signal ends exposure; when the first gray value is greater than the first reference value, the first exposure control signal shortens the first exposure time to reduce the first gray value to the first reference value.
4. The image sensor of claim 3, wherein the first gray scale value is: and selecting at least one of a brightness channel gray value, a red pixel channel gray value, a green pixel channel gray value and a blue pixel channel gray value according to the illumination intensity.
5. The image sensor of any of claims 2-4, wherein the control circuit comprises:
a second control unit for generating a second gray scale value according to the sensed second light input amount; when the second gray value is smaller than a second reference value, the second exposure control signal is enabled to prolong the second exposure time so as to increase the second gray value to the second reference value; the second exposure control signal ends exposure when the second gray value is equal to the second reference value; when the second gray value is greater than the second reference value, the second exposure control signal shortens the second exposure time to decrease the second gray value to the second reference value.
6. The image sensor of claim 5, wherein the second gray scale value is: a white pixel channel gray scale value or a phase detection pixel channel gray scale value.
7. An automatic exposure control method of an image sensor, the method comprising:
at least one first pixel senses a first light entering amount, at least one second pixel senses a second light entering amount, and under the same illumination intensity, the first light entering amount sensed by the first pixel is lower than the second light entering amount sensed by the second pixel;
generating a first exposure control signal according to the first light inlet quantity, and adjusting the first exposure time of the at least one first pixel according to the first exposure control signal;
generating a second exposure control signal according to the second light incoming amount, and adjusting a second exposure time of the at least one second pixel according to the second exposure control signal; the first exposure time is different from the second exposure time.
8. The automatic exposure control method according to claim 7, wherein the first pixel is a color pixel, and the second pixel is a white pixel or a phase detection pixel.
9. The automatic exposure control method according to claim 8, wherein the generating a first exposure control signal according to the first light input amount and adjusting a first exposure time of the at least one first pixel according to the first exposure control signal comprises:
generating a first gray value according to the sensed first light incoming amount;
when the first gray value is smaller than a first reference value, the first exposure control signal prolongs the first exposure time to increase the first gray value to the first reference value;
when the first gray value is equal to the first reference value, the first exposure control signal ends exposure;
when the first gray value is greater than the first reference value, the first exposure control signal shortens the first exposure time to reduce the first gray value to the first reference value.
10. The automatic exposure control method according to claim 9, wherein the first gradation value is: and selecting at least one of a brightness channel gray value, a red pixel channel gray value, a green pixel channel gray value and a blue pixel channel gray value according to the illumination intensity.
11. The automatic exposure control method according to any one of claims 8 to 10, wherein the generating a second exposure control signal according to the second light input amount and adjusting a second exposure time of the at least one second pixel according to the second exposure control signal comprises:
generating a second gray scale value according to the sensed second light incoming amount;
when the second gray value is smaller than a second reference value, the second exposure control signal is enabled to prolong the second exposure time so as to increase the second gray value to the second reference value;
the second exposure control signal ends exposure when the second gray value is equal to the second reference value;
when the second gray value is greater than or equal to a second reference value, the second exposure control signal shortens the second exposure time to decrease the second gray value to the second reference value.
12. The automatic exposure control method according to claim 11, wherein the second gray scale value is: a white pixel channel gray scale value or a phase detection pixel channel gray scale value.
13. An electronic device, characterized in that the electronic device comprises: the image sensor of any one of claims 1-6.
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