CN117651850A - Wavelength measurement device and wavelength measurement method - Google Patents

Abstract

A wavelength measurement device, comprising: a light-splitting unit (3) that splits light emitted by the LED chip (101) when excited; a light receiving unit (5) having a plurality of pixels (51) for receiving the light split by the light splitting unit (3) for each wavelength; a plurality of readout units (52, 54, 55, 513) that respectively correspond to the plurality of pixels (51) and read out signals from the respective pixels; and an arithmetic unit (6) for calculating the representative wavelength of the LED chip (101) based on the signals read by some of the plurality of reading units.

Description

Wavelength measurement device and wavelength measurement method

Technical Field

The present invention relates to a wavelength measurement device and a wavelength measurement method for measuring a representative wavelength of an LED (light emitting diode (light emitting diode)) chip.

Background

For example, since a backlight LED used in a display such as a television has a color variation, which causes a reduction in image quality such as color unevenness of the display, a color of a haircut is strictly managed. Therefore, conventionally, a so-called combining process has been performed in which wavelengths of the LED chips are measured and classified for each color.

However, for example, as the size of the LED chip becomes smaller as the micro LED chip having one side of 100 μm or smaller, a large number of LED chips need to be measured, and therefore the wavelength measurement time becomes longer, and the time of the merging process (merging time) becomes longer. Therefore, shortening of the wavelength measurement time is demanded from the viewpoint of manufacturing efficiency and cost.

The wavelength measurement of the LED chip is performed as follows: light emitted from the LED chip is split for each wavelength, the split light of each wavelength is received by a plurality of pixels of the light receiving sensor, and a signal from each received pixel is read out. Conventionally, since signals are read out for all the pixels of the wavelength after the light splitting, the time required for reading out the signals is long, and it is difficult to shorten the wavelength measurement time.

Further, patent document 1 discloses a spectrum measuring apparatus including: a CCD (charge coupled device (charge coupled device)) detector including a plurality of light receiving elements arranged in two dimensions; an optical system for splitting the incident light and irradiating the split light to a CCD detector; and a limiting unit configured to limit irradiation of light from the optical system to at least one of a part of rows and a part of columns of each of the plurality of light receiving elements.

According to this spectrum measuring apparatus, since at least one of the number of rows and the number of columns irradiated with light can be reduced, the time required for the acquisition process of the electric charges generated in each light receiving element can be shortened as compared with a configuration in which the irradiation destination of light is not limited.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2018-128326

Disclosure of Invention

Problems to be solved by the invention

However, in the technique described in patent document 1, since no charge is accumulated in the light receiving element whose light irradiation is restricted by the restricting portion, the charge is read out from the light receiving element itself, although the reading out can be completed at high speed. Therefore, even if the technique described in patent document 1 is applied to wavelength measurement of an LED chip, the reduction of the readout time is limited, and thus the reduction of the wavelength measurement time is limited.

Further, there is a problem in that the physical restriction portion for restricting the irradiation of light is required, and thus the constitution is complicated.

The present invention has been made in view of the above-described technical background, and an object of the present invention is to provide a wavelength measurement device and a wavelength measurement method that can shorten the measurement time of the representative wavelength of an LED chip without requiring a physical limiting portion that limits the irradiation of light.

Means for solving the problems

The above object is achieved by the following means.

(1) A wavelength measurement device, comprising:

a light-splitting unit that splits light emitted by the LED chip when excited;

a light receiving unit having a plurality of pixels for receiving the light split by the light splitting unit for each wavelength;

a plurality of readout units, corresponding to the plurality of pixels, for reading out signals from the respective pixels; and

and an operation unit configured to calculate a representative wavelength of the LED chip based on the signals read by a part of the plurality of reading units.

(2) The wavelength measuring device according to the preceding item 1, wherein the part of the readout units forms one readout unit group, and a plurality of readout unit groups exist.

(3) The wavelength measurement device according to the preceding item 1 or 2, wherein the arithmetic unit acquires spectral information of the LED chip based on signals read out by all the readout units, and sets a part of the readout units that read out the signals in the main measurement, based on the acquired spectral information, before the main measurement.

(4) The wavelength measurement device according to the foregoing item 2, the arithmetic unit acquires the spectral information of the LED chip based on the signals read out by all the readout units, and selects the readout unit group that reads out the signals in the main measurement, according to the acquired spectral information, before the main measurement.

(5) The wavelength measurement device according to any one of the preceding claims 1 to 4,

the light receiving unit is an area sensor,

each pixel of one pixel row of the area sensor receives light from a plurality of areas in a light emitting surface of the LED chip, and each pixel of the other pixel row orthogonal to the one pixel row receives light emitted from each area and split for each wavelength.

(6) The wavelength measurement device according to item 5 above, wherein the arithmetic unit averages signals from a plurality of regions in the light emitting surface of the LED chip.

(7) The wavelength measurement device according to the preceding item 5 or 6, wherein the area sensor is moved in a direction orthogonal to the one pixel row to receive light from a two-dimensional area within the light emitting surface of the LED chip.

(8) The wavelength measurement device according to any one of the preceding claims 5 to 7, wherein the LED chip is moved in a direction orthogonal to a column region in a light emitting surface of the LED chip corresponding to the one pixel column, thereby receiving light from a two-dimensional region in the light emitting surface of the LED chip.

(9) The wavelength measurement device according to any one of the preceding claims 1 to 8, wherein the representative wavelength is at least one of a light emission peak wavelength, a center of gravity wavelength, and a center wavelength.

(10) The wavelength measurement device according to any one of the preceding claims 1 to 9, comprising a light source unit that excites the LED chip to emit light.

(11) The wavelength measurement device according to any one of the preceding claims 1 to 10, wherein the light receiving unit and the readout unit are configured by a CMOS sensor.

(12) A method of wavelength measurement, comprising:

a light splitting step of splitting light emitted by the LED chip excited by the light splitting unit;

a light receiving step of receiving the light split by the light splitting step for each wavelength by a plurality of pixels;

a readout step of reading out signals from the respective pixels by a part of readout units among a plurality of readout units which correspond to the pixels and read out the signals; and

and a calculation step of calculating a representative wavelength of the LED chip based on the signal read out by the reading step.

(13) The wavelength measurement method according to the preceding item 12, wherein the part of the readout units forms one readout unit group, and a plurality of readout unit groups exist.

(14) The wavelength measurement method according to the preceding item 12 or 13, wherein in the operation step, before the main measurement, the spectrum information of the LED chip is acquired based on the signals read out by all the reading-out units, and a part of the reading-out units that read out the signals in the main measurement is set according to the acquired spectrum information.

(15) The wavelength measurement method according to the preceding item 13, wherein in the operation step, the spectrum information of the LED chip is acquired based on the signals read out by all the readout units, and the readout unit group that reads out the signals in the main measurement is selected according to the acquired spectrum information, before the main measurement.

(16) The wavelength measurement method according to any one of the preceding claims 12 to 15,

the light receiving unit is an area sensor,

each pixel of one pixel row of the area sensor receives light from a plurality of areas in a light emitting surface of the LED chip, and each pixel of the other pixel row orthogonal to the one pixel row receives light emitted from each area and split for each wavelength.

(17) The wavelength measurement method according to the preceding item 16, wherein in the calculating step, signals from a plurality of regions in a light emitting surface of the LED chip are averaged.

(18) The wavelength measurement method according to the preceding item 16 or 17, wherein the light from the two-dimensional region in the light emitting surface of the LED chip is received by moving the region sensor in a direction orthogonal to the one pixel row.

(19) The wavelength measurement method according to any one of the preceding claims 16 to 18, wherein the LED chip is moved in a direction orthogonal to a column region in a light emitting surface of the LED chip corresponding to the one pixel column, thereby receiving light from a two-dimensional region in the light emitting surface of the LED chip.

(20) The method for measuring a wavelength according to any one of the preceding claims 12 to 19, wherein the representative wavelength is at least one of a light emission peak wavelength, a center of gravity wavelength, and a center wavelength.

(21) The wavelength measurement method according to any one of the preceding claims 12 to 20, wherein the light receiving unit and the readout unit are configured by a CMOS sensor.

Effects of the invention

According to the inventions described in the foregoing items (1) and (12), light emitted by the LED chip excited is split by the splitting unit, and is received by the light receiving unit having a plurality of pixels for each wavelength. The signals of the pixels are read out by a part of the plurality of readout units which correspond to the plurality of pixels and read out the signals from the respective pixels. Based on the read signal, the representative wavelength of the LED chip is calculated by the calculation unit.

In this way, since only signals from a part of pixels are read out by a part of the readout units, signals of all pixels do not need to be read out, and accordingly, the readout time can be shortened, and the wavelength measurement time can be shortened. Further, a physical limiting portion for limiting light reception is not required, and the constitution is not complicated.

In particular, in the present invention, the emission colors of the LED chips are red (R), green (G), and blue (B), and the wavelength ranges required for measuring the representative wavelengths are substantially limited, and it is not necessary to acquire signals of all wavelengths in the visible region. For example, in the case of measuring an R-color LED chip, a signal in the 550 to 700nm region may be obtained. Therefore, there is no problem in reading out the signal from the pixel even if the wavelength region is limited, and the advantage of shortening the wavelength measurement time by shortening the reading-out time can be enjoyed.

Further, the LED chip emits light when excited by excitation light, and therefore, it is necessary to exclude the influence of the excitation light, but by restricting the wavelength region in which measurement data is read out, there is an effect that the influence of the excitation light can be excluded as much as possible.

According to the inventions described in the foregoing items (2) and (13), a part of the readout units form one readout unit group, and there are a plurality of readout unit groups, and therefore, for the LED chips of different colors, signals of wavelength regions respectively defined by the plurality of readout unit groups can be read out.

According to the inventions described in the foregoing items (3) and (14), before the main measurement is performed, the arithmetic unit can acquire the spectral information of the LED chip based on the signals read out by all the readout units, and set a part of the readout units that read out the signals in the main measurement with high accuracy based on the acquired spectral information.

According to the inventions described in the foregoing items (4) and (15), before performing the main measurement, the arithmetic unit can acquire the spectral information of the LED chip based on the signals read out by all the readout units, and select the readout unit group that reads out the signals in the main measurement with high accuracy according to the acquired spectral information.

According to the inventions described in the foregoing items (5) and (16), since each pixel of one pixel row of the area sensor receives light from a plurality of areas in the light emitting surface of the LED chip and each pixel of the other pixel row orthogonal to the one pixel row receives light emitted from each area and split for each wavelength, light from a plurality of areas in the light emitting surface of the LED chip can be split for each wavelength and received by the pixel.

According to the inventions described in the foregoing items (6) and (17), the arithmetic unit averages signals from a plurality of regions in the light emitting surface of the LED chip, so that the setting of the reading unit that reads out the signals can be performed with high accuracy.

According to the inventions described in the foregoing items (7) and (18), by moving the area sensor in the direction orthogonal to one pixel row, light from the two-dimensional area in the light emitting surface of the LED chip can be received.

According to the inventions described in the foregoing items (8) and (19), by moving the LED chip in a direction orthogonal to the column region in the light emitting surface of the LED chip corresponding to one pixel column, light from the two-dimensional region in the light emitting surface of the LED chip can be received.

According to the inventions described in the foregoing items (9) and (20), at least one of the emission peak wavelength, the center of gravity wavelength, and the center wavelength can be obtained as the representative wavelength.

According to the invention described in the foregoing item (10), the LED chip can be excited to emit light by the light source section.

According to the inventions described in the foregoing items (11) and (21), since the light receiving unit and the readout unit are constituted by the CMOS sensor, it is possible to realize readout of signals from a part of pixels by a part of the readout unit by the CMOS sensor.

Drawings

Fig. 1 is a block diagram showing a configuration of a wavelength measurement device according to an embodiment of the present invention.

Fig. 2 is a perspective view showing a specific configuration of a part of the wavelength measurement device of fig. 1.

Fig. 3 is a circuit diagram showing an exemplary configuration of the CMOS sensor.

Fig. 4 is an explanatory diagram of setting of the wavelength readout range.

Fig. 5 is a diagram for explaining a relationship between the pixel sizes of the plurality of LED chips and the light receiving unit on the measurement object.

Fig. 6 is a diagram for explaining a determination example of a wavelength reading range in the main measurement.

Fig. 7 is a diagram for explaining another determination example of the wavelength readout range in the main measurement.

Fig. 8 (a), (B), and (C) are explanatory diagrams of settings of the readout unit group.

Fig. 9 is a schematic diagram of data of wavelength λ having maximum brightness, which is extracted from light received from the surface of the measurement object, from among data of a pixel group of an appropriate region including measurement data of a plurality of LED chips, for example.

Fig. 10 (a) is a diagram showing a state in which measurement data in each pixel is separated into each LED chip, (B) is a diagram for explaining a calculation method of a representative wavelength, and (C) is an enlarged diagram of (B).

Fig. 11 is a spectrum graph plotting an average value of 9 pixels per wavelength for a data region of a plurality of LED chips.

Fig. 12 is a spectral graph plotting the value of one pixel per wavelength for the data region of multiple LED chips.

Fig. 13 is a graph showing an average value of 9 pixels for each wavelength of a data region of 1LED chip, and a fitted curve based on the average value.

Fig. 14 is a diagram for explaining a measurement method for a measurement object having a wide measurement range.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is a block diagram showing a configuration of a wavelength measurement device according to an embodiment of the present invention. In this embodiment, a case will be described in which the object 100 is a wafer on which a plurality of LED chips are formed.

The wavelength measuring device shown in fig. 1 includes a light source 1 for excitation, an objective lens 2 having a variable magnification, a spectroscopic unit 3, an imaging lens 4, a region sensor 5 as a two-dimensional imaging element, a calculation unit 6, and a measurement result display unit 7 constituted by a liquid crystal display device or the like.

The excitation light source 1 irradiates excitation light to a plurality of LED chips on the object 100 to be measured, and excites the plurality of LED chips to emit light.

The spectroscopic unit 3 splits the light from the LED chips passing through the objective lens 2 for each wavelength, and the imaging lens 4 images the light of each wavelength split by the spectroscopic unit 3 on the area sensor 5. In the present embodiment, the wavelength is divided into wavelengths at a wavelength interval of 5 nm.

The area sensor 5 corresponds to a light receiving unit, and includes a plurality of pixels 51 arranged vertically and horizontally as shown in fig. 2. The lateral direction (the space X direction in fig. 2) of the area sensor 5 means the lateral direction of the physical space, and each pixel 51 in the lateral direction corresponds to the area in the lateral direction of the object 100 to be measured. On the other hand, the longitudinal direction of the area sensor 5 (the wavelength Z direction of fig. 2) corresponds to the wavelength of light. That is, each pixel 51 of the pixel row in the space X direction corresponds to a plurality of regions (column regions) 100a in the one-dimensional direction of the object 100, and light emitted from the column region 100a, which is incident on the slit 31 of the spectroscopic unit 3 through the objective lens 2 and wavelength-resolved by the spectroscopic unit 3, is received by each pixel 51 of the pixel row in the wavelength Z direction. Therefore, in order to perform spectroscopic measurement on each region in the two-dimensional direction (plane) of the object 100, it is necessary to perform spectroscopic measurement while moving (scanning) the object 100 in the Z1 direction orthogonal to the column region 100a in the one-dimensional direction. Alternatively, the wavelength measuring device including the area sensor 5 may be moved in the wavelength Z direction orthogonal to the spatial X direction in fig. 2 without moving the object 100, or both the object 100 and the wavelength measuring device may be moved with a speed difference, and it is essential that at least one of the object 100 and the wavelength measuring device is moved relative to the other.

Each time the relative movement is performed, the column regions 100a of the measurement object 100 are switched, the spectral data of a plurality of frames is obtained by setting the spectral data of each column region 100a to the amount of one frame, and is accumulated as a spectral data cube. In the present embodiment, the object 100 (LED chip 101) to be measured is moved, and as shown in fig. 1, a moving device 300 capable of moving the table 200 on which the object 100 to be measured is placed is provided.

The technique of dividing the plane of the measurement object 100 into regions having a size corresponding to the pixels 51 of the area sensor 5, splitting light from each region, receiving the split light by each pixel 51 of the area sensor 5, and repeating the receiving while relatively moving at least one of the measurement object 100 and the wavelength measuring device with respect to the other, thereby obtaining the split data is known as a push-broom method, and is known as a hyperspectral camera, for example.

In the present embodiment, the area sensor 5 includes a plurality of readout units for reading out signals from the respective pixels, and is a sensor capable of specifying a readout range, and for example, a CMOS sensor is used. Hereinafter, the area sensor is also referred to as a CMOS sensor. Fig. 3 schematically shows an exemplary configuration of the CMOS sensor 5.

In the CMOS sensor 5 shown in fig. 3, each pixel 51 includes: a light receiving element 511 constituted by a photodiode or the like, an amplifier 512 that converts the charge accumulated by the light receiving element 511 into a voltage and amplifies it, and a pixel selection switch 513. The pixel selection switch 513 of each pixel 51 is connected to a corresponding one of the plurality of vertical signal lines 52 arranged on each pixel 51 of the column. In addition, the vertical signal line 52 is connected to the horizontal signal line 55 through the CDS circuit 53 and the column selection switch 54.

Accordingly, the light receiving element 511 is connected to the vertical signal line 52 by turning on the pixel selection switch 513 of the pixel 51 for which a signal is desired to be read out, and the vertical signal line 52 is connected to the horizontal signal line 55 by turning on the column selection switch 54, so that a signal concerning the selected pixel 51 can be read out through the vertical signal line 52 and the horizontal signal line 55. That is, the signal reading section of each pixel 51 is formed of a pixel selection switch 513 of each pixel 51, a vertical signal line 52 and a horizontal signal line 55 which are common to a plurality of pixels 51, a column selection switch 54, and the like, and the signal reading section is controlled to read out a signal of an arbitrary pixel 51.

Accordingly, as shown in fig. 4, by setting the readout range W2 from all the readout regions W1 in the wavelength Z direction of the area sensor 5 and setting the readout sections of the plurality of pixels 51 existing within the set readout range W2 as one readout section group, only signals of the wavelength of the specified range W2 within the wavelength split by the spectroscopic section 3 can be read.

The measurement data, which is signals outputted from the plurality of pixels 51 of the area sensor 5, of which the read range is specified, is converted into a digital signal by a current-voltage (IV) conversion circuit and an analog-digital (AD) conversion circuit, which are not shown, as needed, and is sent to the arithmetic unit 6. The calculation unit 6 calculates the representative wavelength for each of the plurality of LED chips on the measurement object by a CPU or the like, using the transmitted measurement data. Details of the calculation method of the representative wavelength will be described later.

The measurement result display unit 7 displays the calculation result of the calculation unit 6. The conversion of the measurement data output from the area sensor 5 into a digital signal may be performed by the arithmetic unit 6.

The arithmetic unit 6 may be a dedicated device or may be a personal computer. The measurement data outputted from the area sensor 5 and processed into a digital signal may be transmitted to the arithmetic unit 6 via a network. In this case, even if the computing unit 6 is located at a place separate from the measurement place, measurement of the representative wavelength of the LED chip can be performed.

Next, a method of measuring the representative wavelength of each LED chip on the wafer as the measurement object 100 by the wavelength measuring apparatus shown in fig. 1 will be described.

Fig. 5 is a diagram for explaining a relationship between the plurality of LED chips 101 on the measurement target 100 and the size of the pixel 51 of the area sensor 5. The horizontal axis of the fine grid in fig. 5 is the spatial X direction, and the vertical axis is the spatial Y direction generated by scanning the LED chip 101 in the wavelength Z direction. The size of one lattice is a measurement area, corresponding to the size of the pixel 51.

The LED chips 101 are displayed in a rectangular shape, and are arranged vertically and horizontally on the measurement object 100. The rectangular region directly serves as a light emitting surface of each LED chip 101.

The arrangement pitch of the LED chips 101, the pitch of the pixels 51 of the area sensor 5, the magnification of the objective lens 2, and the like are set so that data can be acquired for the light emitting surface of one LED chip 101 by a plurality of pixels 51, that is, so that light emitted from a plurality of areas of the light emitting surface of one LED chip 101, which are of a size corresponding to the pixels 51, can be received by the corresponding plurality of pixels 51, respectively. In the present embodiment, the light from the light emitting surface of one LED chip 101 can be divided into 3×3=9 pixels or more to receive light.

Next, before the main measurement is performed, a prediction amount for determining a read range in the wavelength Z direction (in other words, a wavelength region in which the reading is performed) is performed.

First, 1 frame measurement data, which is a signal of 1 line in the X direction in space, is read out from pixels (all pixels in the Z direction of the wavelength in fig. 2 and 4) corresponding to all wavelength ranges (380 to 780 nm). The 1-frame measurement data read out was spectral data (data of luminance at each wavelength) with a wavelength interval of 5 nm.

Next, the wavelength λ0 of the pixel 51 having the maximum luminance is determined from the data of the pixel group including the appropriate partial region of the plurality of LED chips 101. In addition, even if the wavelength of the pixel 51 having the maximum luminance is not the wavelength, the average of the wavelengths of the plurality of pixels 51 having high luminance may be set to λ0. By averaging the wavelengths, the accuracy of the wavelength λ0 becomes high.

The wavelength range in the main measurement (hereinafter, also referred to as the main measurement wavelength range) which is a read range is set to a predetermined range of, for example, ±75nm around the wavelength λ0 determined in this way. As an example, as shown in fig. 6, when the determined wavelength λ0 is 626.0nm, 626.0 ±75nm, that is, 551nm to 701nm is determined as the main measurement wavelength range. The wavelength of + -75 nm may be any value other than that. By determining the main measurement wavelength range, a readout unit group including a part of readout units that perform readout among the readout units of all the pixels 51 of the area sensor 5 is set.

As another method for determining the predicted main measurement wavelength range, a method of selecting from a plurality of main measurement wavelength ranges prepared in advance based on the determined value of the wavelength λ0 can be cited. For example, as shown in fig. 7, when the LED chip 101 is blue, 390 to 540nm (center wavelength: 465 nm) is preset as a main measurement wavelength range WB, when green, 465 to 615nm (center wavelength: 540 nm) is preset as a main measurement wavelength range WG, and when red, 550 to 700nm (center wavelength: 625 nm) is preset as a main measurement wavelength range WR.

And, if the value of the wavelength λ0 is close to 465nm, a main measurement wavelength range WB of 390 to 540nm set for blue is selected, if the value of the wavelength λ0 is close to 540nm, a main measurement wavelength range WG of 465 to 615nm set for green is selected, and if the value of the wavelength λ0 is close to 625nm, a main measurement wavelength range WR of 550 to 700nm set for red is selected. By selecting the main measurement wavelength range, a readout unit group for performing readout of the pixels 51 is set. For example, when the main measurement wavelength range WR is determined, as shown in fig. 8 (a), the readout unit group 50R that reads out the measurement data of the plurality of pixels 51 corresponding to the main measurement wavelength range WR is set, when the main measurement wavelength range WG is determined, as shown in fig. 8 (B), the readout unit group 50G that reads out the measurement data of the plurality of pixels 51 corresponding to the main measurement wavelength range WG is set, and when the main measurement wavelength range WB is determined, as shown in fig. 8 (C), the readout unit group 50B that reads out the measurement data of the plurality of pixels 51 corresponding to the main measurement wavelength range WB is set. In this way, different readout part groups are set from the plurality of readout part groups 50R, 50G, 50B according to the main measurement wavelength range.

In addition, as another other determination method of the main measurement wavelength range, when the emission color of the LED chip 101 is known in advance, the main measurement wavelength ranges WB, WG, WR set in advance for the same blue, green, and red as described above may be selected without performing the prediction. In this case, the readout unit groups 50B, 50G, 50R corresponding to the main measurement wavelength ranges WB, WG, WR among the readout unit groups 50R, 50G, 50B are also set.

In this way, after the main measurement wavelength range is determined and the readout portion group corresponding to the plurality of pixels 51 performing signal readout is set, main measurement is performed as follows.

That is, excitation light is irradiated from the excitation light source 1 onto the measurement object 100 placed on the stage 200, and light emitted from the plurality of LED chips 101 on the measurement object 100 is received by each pixel 51 of the area sensor 5 while the stage 200 is moved by the moving device 300. The light emitted from the LED chip 101 is split by the splitter 3 for each predetermined wavelength, and the split light of each wavelength is received by each pixel 51. The movement of the stage 200 is performed after reading out the main measurement wavelength range for measurement data of 1 frame. When the exposure is completed, the stage 200 may be moved during the reading.

The measurement data is read out from the pixels 51 only in the readout section group set corresponding to the main measurement wavelength range determined by the pre-measurement among all the pixels 51 that receive the light.

The read measurement data is sent to the arithmetic unit 6, and stored in a memory, not shown, in the arithmetic unit 6. Since the measurement is performed while the object 100 on the table 200 is moved by the moving device 300, 1 frame of measurement data is obtained every time the object 100 is moved (every time the object is scanned), and thus, a plurality of frames of measurement data are obtained for the two-dimensional direction, in other words, the planar area of the object 100. In each frame, measurement data is read out only for the pixels 51 corresponding to the readout unit group, and measurement data concerning wavelengths within the main measurement wavelength range among the divided wavelengths is obtained.

Based on the measurement data thus obtained, the calculation unit 6 calculates the representative wavelength of each LED chip 101.

Fig. 9 is a schematic diagram of data having a wavelength λ of maximum brightness, which is obtained by extracting only light of an arbitrary wavelength from light received from the surface of the measurement object 100, for example, data of a pixel group including an appropriate region of measurement data of the plurality of LED chips 101. The black frame 8 shown in fig. 9 indicates a region corresponding to the light emitting surface of one LED chip 101. The area 9 shown in a dense state has a strong luminance, and the luminance becomes weaker as the surrounding area is reached.

Next, the measurement data received by the pixels 51 of the area sensor 5 is separated to each LED chip 10. This separation can be performed, for example, as follows. That is, the wavelength λ having the maximum luminance is obtained from the data of the pixel group of the appropriate region including the measurement data of the plurality of LED chips 101. Next, at the wavelength λ, each pixel 51 may be classified by brightness, and image processing may be performed using a certain brightness level as a threshold value, thereby separating each LED chip 101. Fig. 10 (a) shows a state in which measurement data of each pixel 51 is separated into each LED chip 101. In fig. 10 (a), 9 data areas 10a to 10i indicated by black boxes are separated.

Next, for the measurement data of each of the separated LED chips 101, a pixel of interest to obtain the maximum value of luminance (luminance value) is determined. For example, as shown in fig. 10B, in the measurement data for the data area (for example, the data area 10B) of one LED chip 101, when the maximum value is obtained by the pixel of interest 51a in a certain wavelength, the pixel 51a is determined as the pixel of interest. Here, a certain wavelength is a wavelength used only for finding a separated luminance level or a pixel of interest, and examples thereof include a wavelength having the maximum luminance in data of a pixel group of an appropriate region including measurement data of a plurality of LED chips 101, a wavelength having the maximum luminance in measurement data of a data region of one LED chip, a design wavelength of an LED chip, and the like, as described above.

After the pixel of interest 51a is determined, the value of the pixel of interest 51a and the value of a certain wavelength obtained by 1 or more pixels around the pixel of interest 51a are averaged as spectral data of the wavelength (luminance data at the wavelength). In the example of fig. 10 (B), as shown in the enlargement of fig. 10 (C), the values of 8 pixels 51B to 51i around the pixel of interest 51a and the total 9 pixels 51 of the pixel of interest 51a are averaged.

By averaging the data of the plurality of pixels including the pixel of interest 51a in this way, the effect of reducing the measurement noise can be obtained.

The average pixel is used as the surrounding pixels of the target pixel 51a to accommodate the measurement region of the wavelength of the LED chip 101 in the light emitting surface, and a value having little influence of variation can be obtained with a small amount of data. Specifically, if the values including the surrounding 9 pixels of the pixel of interest 51a representing the maximum luminance are used, the value having the small influence of the deviation can be sufficiently obtained.

Fig. 11 is a spectrum chart showing the average value of 9 pixels at each wavelength for 4 data areas 10b, 10d, 10f, and 10h among the data areas 10a to 10i of the plurality of LED chips 101 shown in fig. 10 (a). On the other hand, fig. 12 is a spectrum chart in which the values of the attention-only pixels 51a obtained for each wavelength are plotted for the same 4 data areas 10b, 10d, 10f, and 10 h. In any graph, the horizontal axis represents wavelength and the vertical axis represents luminance. When comparing the two graphs, it can be seen that the spectral shape of only the value of the attention pixel 51a shown in fig. 12 is aliased.

The luminance values of the pixel of interest 51a and the pixels 51b to 51i around the pixel of interest are averaged for each wavelength, and the representative wavelength is obtained from the average value of each wavelength obtained. Specifically, as shown in fig. 13, a fitting curve is obtained by gaussian fitting or the like based on the average value of the respective wavelengths, and the wavelength of the peak of the fitting curve is set as the representative wavelength. When the wavelength interval is small, the wavelength of the largest average value among the average values of the respective wavelengths may be used as the representative wavelength without fitting.

In this way, the representative wavelength is calculated from the measurement data for all the LED chips 101 of the measurement object 100. The representative wavelength calculated in the present embodiment is the emission peak wavelength, but may be the center of gravity wavelength, the center wavelength, or the like. The barycentric wavelength is a weighted average of wavelengths weighted by the emission spectrum. In other words, the center of gravity wavelength is a value obtained by integrating the product of each wavelength and the intensity of light of that wavelength over the entire emission wavelength, and dividing the value obtained by integrating the intensity of light over the entire emission wavelength. The center wavelength is the average value of the two half-value wavelengths obtained by reducing the maximum amplitude of the peak wavelength by 3 dB.

As described above, in the present embodiment, the main measurement wavelength range in which the signals are read is determined instead of the signals of all the pixels 51 corresponding to the wavelengths in all the ranges after the light splitting, and the signals are read by the reading unit group including the reading units of a part of the pixels 51, which is set in correspondence with the determined main measurement wavelength range. Accordingly, it is not necessary to read out signals of all pixels, and accordingly, the readout time can be shortened, the wavelength measurement time can be shortened, and the combination time can be shortened. Further, since a physical restriction portion for restricting light reception of the pixels 51 which do not perform reading is not required, the constitution does not become complicated.

In particular, the emission colors of the LED chip 101 are red (R), green (G), blue (B), the wavelength ranges required to measure the respective representative wavelengths are approximately defined, and it is not necessary to obtain a signal of all wavelengths in the visible region, so there is no problem even if the signal from the pixel 51 is read out by defining the wavelength region, and an advantage of shortening the wavelength measurement time due to shortening of the readout time can be obtained.

In contrast to the case where the integration time of the CMOS sensor 5 is 1ms and the measurement wavelength range is 400nm, which is a frame rate indicating the number of frames that can be read out in 1 second, which is about 520FPS, the frame rate when the wavelength measurement range is limited to 150nm can be increased to about 920FPS, and the readout time can be shortened.

Further, the LED chip 101 emits light when excited by excitation light, and therefore, it is necessary to exclude the influence of the excitation light, but by restricting the wavelength region in which measurement data is read out, there is an effect that the influence of the excitation light can be excluded as much as possible.

The present application claims priority from japanese patent application publication No. 2021-118071, filed 7/16 in 2021, the disclosure of which forms part of this application directly.

Industrial applicability

The invention can be used for measuring the representative wavelength of the LED chip.

Description of the reference numerals

1 light source for excitation

2 objective lens

3 beam splitter

4 imaging lens

5 area sensor (light receiving unit)

51 pixel

511 light receiving element

512 amplifier

513 pixel selection switch

52 vertical signal line

54 column selection switch

55 horizontal signal line

6 arithmetic unit

7 measurement result display unit

10a to 10i data areas

100 objects to be measured

100a column area

101LED chip (LED chip)

200 watch

300 mobile device

Wavelength ranges for WB, WG, WR primary measurements

50B, 50G, 50R readout sections.

Claims (21)

1. A wavelength measurement device, comprising:

a light-splitting unit that splits light emitted by the LED chip when excited;

a light receiving unit having a plurality of pixels for receiving the light split by the light splitting unit for each wavelength;

a plurality of readout units, corresponding to the plurality of pixels, for reading out signals from the respective pixels; and

and an operation unit configured to calculate a representative wavelength of the LED chip based on the signals read by a part of the plurality of reading units.

2. The wavelength measurement device according to claim 1, wherein,

the part of the read-out units form a read-out unit group, and a plurality of read-out unit groups exist.

3. The wavelength measurement device according to claim 1 or 2, wherein,

the arithmetic unit acquires spectral information of the LED chip based on signals read out by all the readout units before the main measurement, and sets a part of the readout units that read out the signals in the main measurement according to the acquired spectral information.

4. The wavelength measurement device according to claim 2, wherein,

the arithmetic unit acquires spectral information of the LED chips based on signals read out by all the readout units before the main measurement, and selects a readout unit group that reads out signals in the main measurement according to the acquired spectral information.

5. The wavelength measurement device according to any one of claims 1 to 4, wherein,

the light receiving unit is an area sensor,

each pixel of one pixel row of the area sensor receives light from a plurality of areas in a light emitting surface of the LED chip, and each pixel of the other pixel row orthogonal to the one pixel row receives light emitted from each area and split for each wavelength.

6. The wavelength measuring device according to claim 5, wherein,

the arithmetic unit averages signals from a plurality of regions within a light emitting surface of the LED chip.

7. The wavelength measurement device according to claim 5 or 6, wherein,

by moving the area sensor in a direction orthogonal to the one pixel row, light from a two-dimensional area within the light emitting surface of the LED chip is received.

8. The wavelength measurement device according to any one of claims 5 to 7, wherein,

the LED chip is moved in a direction orthogonal to a column region in a light emitting surface of the LED chip corresponding to the one pixel column, and light from a two-dimensional region in the light emitting surface of the LED chip is received.

9. The wavelength measurement device according to any one of claims 1 to 8, wherein,

the representative wavelength is at least one of a light emission peak wavelength, a center of gravity wavelength, and a center wavelength.

10. The wavelength measurement device according to any one of claims 1 to 9, wherein,

the LED chip is provided with a light source part for exciting the LED chip to emit light.

11. The wavelength measurement device according to any one of claims 1 to 10, wherein,

the light receiving unit and the reading unit are formed by CMOS sensors.

12. A method of wavelength measurement, comprising:

a light splitting step of splitting light emitted by the LED chip excited by the light splitting unit;

a light receiving step of receiving the light split by the light splitting step for each wavelength by a plurality of pixels;

a readout step of reading out signals from the respective pixels by a part of readout units among a plurality of readout units which correspond to the pixels and read out the signals; and

and a calculation step of calculating a representative wavelength of the LED chip based on the signal read out by the reading step.

13. The wavelength measurement method according to claim 12, wherein,

the part of the read-out units form a read-out unit group, and a plurality of read-out unit groups exist.

14. The wavelength measurement method according to claim 12 or 13, wherein,

before the main measurement, in the operation step, the spectral information of the LED chip is acquired based on the signals read out by all the readout units, and a part of the readout units that read out the signals in the main measurement is set according to the acquired spectral information.

15. The wavelength measurement method according to claim 13, wherein,

before the main measurement, in the operation step, the spectral information of the LED chips is acquired based on the signals read out by all the readout units, and the readout unit group that reads out the signals in the main measurement is selected according to the acquired spectral information.

16. The wavelength measurement method according to any one of claims 12 to 15, wherein,

the light receiving unit is an area sensor,

each pixel of one pixel row of the area sensor receives light from a plurality of areas in a light emitting surface of the LED chip, and each pixel of the other pixel row orthogonal to the one pixel row receives light emitted from each area and split for each wavelength.

17. The wavelength measurement method according to claim 16, wherein,

in the calculating step, signals from a plurality of regions in the light emitting surface of the LED chip are averaged.

18. The wavelength measurement method according to claim 16 or 17, wherein,

by moving the area sensor in a direction orthogonal to the one pixel row, light from a two-dimensional area within the light emitting surface of the LED chip is received.

19. The wavelength measurement method according to any one of claims 16 to 18, wherein,

the LED chip is moved in a direction orthogonal to a column region in a light emitting surface of the LED chip corresponding to the one pixel column, and light from a two-dimensional region in the light emitting surface of the LED chip is received.

20. The wavelength measurement method according to any one of claims 12 to 19, wherein,

the representative wavelength is at least one of a light emission peak wavelength, a center of gravity wavelength, and a center wavelength.

21. The wavelength measurement method according to any one of claims 12 to 20, wherein,

the light receiving unit and the reading unit are formed by CMOS sensors.