Wavelength measuring device and wavelength measuring method

Abstract

The present invention comprises a light-splitting means (3) that splits light emitted from an excited LED chip (101), a light-receiving means (5) that has a plurality of pixels (51) that receive each wavelength of the light split by the light-splitting means (3), a plurality of readout means (52), (54), (55), (513) that correspond to each of the plurality of pixels (51) and read out signals from each of the pixels, and a computation means (6) that computes a representative wavelength for the LED chip (101) on the basis of the signals read out by a portion of the readout means from among the plurality of readout means.

Description

Technical Field

[0001] This invention relates to a wavelength measuring apparatus and a wavelength measuring method for measuring the representative wavelength of an LED (light emitting diode) chip.

Background Art

[0002] For example, since the color variation of LEDs used for backlights in displays such as televisions causes image quality degradation such as color unevenness in the display, the emission color is strictly controlled. For this reason, a process called binning, in which the wavelength of each LED chip is measured and classified by color, has been conventionally performed.

[0003] However, when the size of an LED chip becomes small, such as a micro LED chip with a side length of 100 μm or less, a huge number of LED chips need to be measured. As a result, the wavelength measurement time becomes long, and ultimately the time of the binning process (binning time) becomes long. Therefore, shortening the wavelength measurement time is required in terms of manufacturing efficiency and cost.

[0004] The wavelength measurement of an LED chip is performed by spectroscopically separating the light emitted from the LED chip for each wavelength, receiving the light of each spectroscopically separated wavelength with a plurality of pixels of a light receiving sensor, and reading out signals from each received pixel. Conventionally, since signals have been read out for all pixels of all spectroscopically separated wavelengths, the time required for reading out the signals becomes long, and it is difficult to shorten the wavelength measurement time.

[0005] Patent Document 1 discloses an optical spectrum measuring apparatus including a CCD (Charge Coupled Device) detector including a plurality of two-dimensionally arranged light receiving elements, an optical system that spectroscopically separates incident light and irradiates the CCD detector, and a limiting unit that limits the irradiation of light from the optical system to at least one of a part of each row and a part of each column of the plurality of light receiving elements.

[0006] According to this optical spectrum measurement device, it is possible to reduce at least one of the number of rows and columns to which light is irradiated. Therefore, compared to a configuration that does not restrict the direction of light irradiation, it is possible to shorten the time required to acquire the charge generated at each photodetector. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2018-128326 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, in the technology described in Patent Document 1, since no charge is accumulated in the photodetector whose light irradiation is restricted by the limiting unit, although it is possible to discard the data at high speed, the charge itself is still read out from these photodetectors. For this reason, even if the technology described in Patent Document 1 is applied to the wavelength measurement of LED chips, there is a limit to how much the readout time can be shortened, and therefore there is a limit to how much the wavelength measurement time can be shortened.

[0009] Furthermore, the need for a physical limiting mechanism to restrict light irradiation added to the complexity of the design.

[0010] This invention has been made in view of the above technical background, and aims to provide a wavelength measuring device and a wavelength measuring method that do not require a physical limiting part to restrict light irradiation and can shorten the measurement time for the representative wavelength of an LED chip. [Means for solving the problem]

[0011] The above objectives will be achieved by the following means: (1) A spectroscopic means for spectrally analyzing the light emitted when an LED chip is excited, A light-receiving means having a plurality of pixels that receive light spectrally separated by the spectral means for each wavelength, Multiple reading means corresponding to each of the aforementioned multiple pixels, which can read signals from each pixel and select whether or not to read the signals, A calculation means that calculates the representative wavelength of the LED chip based on the signal read out by the reading means selected from the plurality of reading means to read out the signal, Equipped with 、 The light receiving means is an area sensor, Each pixel in one pixel row of the area sensor receives light from multiple regions within the light-emitting surface of the LED chip, and each pixel in the other pixel row, which is orthogonal to the first pixel row, receives light emitted and spectrally separated from each region, wavelength by wavelength. Wavelength measurement device. (2) The wavelength measuring apparatus described in paragraph 1 above, wherein the reading means selected to read out a signal forms one group of reading means, and there are multiple groups of reading means. (3) The wavelength measuring device according to paragraph 1 or 2 above, wherein the calculation means acquires spectral information of the LED chip based on the signals read out by all the reading means prior to the measurement, and sets up a reading means for reading signals in the measurement from the acquired spectral information. (4) The wavelength measuring apparatus according to paragraph 2 above, wherein the calculation means acquires spectral information of the LED chip based on the signals read out by all the reading means prior to the measurement, and selects a group of reading means to read out signals in the measurement from the acquired spectral information. (5) The calculation means averages the signals from multiple regions within the light-emitting surface of the LED chip. 1 Wavelength measuring device as described above. ( 6 )By moving the area sensor in a direction orthogonal to one of the pixel rows, the light from a two-dimensional region within the light-emitting surface of the LED chip is received. 1 Wavelength measuring device as described above. ( 7 )By moving the LED chip in a direction orthogonal to the column region on the light-emitting surface of the LED chip corresponding to one of the pixel rows, the LED chip receives light from a two-dimensional region on the light-emitting surface. 1 Wavelength measuring device as described above. ( 8 ) The wavelength measuring device according to paragraph 1, wherein the representative wavelength is at least one of the emission peak wavelength, centroid wavelength, or center wavelength. (9 The wavelength measurement device according to the preceding paragraph 1, comprising a light source unit for exciting the LED chip to emit light. ( 10 ) The light receiving means and the reading means are the wavelength measurement device according to the preceding paragraph 1, which are constituted by a CMOS sensor. ( 11 ) A spectral splitting step of splitting the light emitted by exciting the LED chip by a spectral splitting means; A light receiving step of receiving the light split by the spectral splitting step by a light receiving means having a plurality of pixels for each wavelength; A reading step of reading the signal by the reading means selected to read the signal among a plurality of reading means that correspond to each of the plurality of pixels and are capable of selecting pixels for reading signals from each pixel; An arithmetic step of calculating a representative wavelength of the LED chip based on the signal read by the reading step; including 、 The light receiving means is an area sensor, Each pixel in one pixel row of the area sensor receives light from multiple regions within the light-emitting surface of the LED chip, and each pixel in the other pixel row, which is orthogonal to the first pixel row, receives light emitted and spectrally separated from each region, wavelength by wavelength. A wavelength measurement method. ( 12 ) The reading means selected to read the signal forms one group of reading means, and there are a plurality of groups of reading means in the preceding paragraph 11 The wavelength measurement method described. ( 13 ) In the arithmetic step, prior to this measurement, spectral information of the LED chip is acquired based on the signals read by all the reading means, and from the acquired spectral information, the reading means for reading the signal in this measurement is set in the preceding paragraph 11 or 12 The wavelength measurement method described. ( 14 ) In the arithmetic step, prior to this measurement, spectral information of the LED chip is acquired based on the signals read by all the reading means, and from the acquired spectral information, a group of reading means for reading the signal in this measurement is selected in the preceding paragraph 12 The wavelength measurement method described. ( 15) In the calculation step, the signal from multiple regions within the light-emitting surface of the LED chip is averaged. 11 Wavelength measurement method as described above. ( 16 )By moving the area sensor in a direction orthogonal to one of the pixel rows, the light from a two-dimensional region within the light-emitting surface of the LED chip is received. 11 Wavelength measurement method as described above. ( 17 )By moving the LED chip in a direction orthogonal to the column region on the light-emitting surface of the LED chip corresponding to one of the pixel rows, the LED chip receives light from a two-dimensional region on the light-emitting surface. 11 Wavelength measurement method as described above. ( 18 The aforementioned representative wavelength is at least one of the emission peak wavelength, centroid wavelength, or center wavelength. 11 Wavelength measurement method as described above. ( 19 The light receiving means and reading means are configured by a CMOS sensor. 11 Wavelength measurement method as described above. [Effects of the Invention]

[0012] The preceding paragraph (1) and ( 11 According to the invention described above, the light emitted when an LED chip is excited is spectrally separated by a spectral means and received at each wavelength by a light receiving means having a plurality of pixels. Of the plurality of reading means corresponding to each of the plurality of pixels, which can read the signal from each pixel and select whether or not to read the signal, the signal of the pixel is read out by the reading means selected to read the signal. Then, based on the readout signal, the representative wavelength of the LED chip is calculated by a calculation means.

[0013] Thus, The selected readout is the one that reads the signal. Because this method reads out signals from only some pixels, it is not necessary to read out signals from all pixels, thereby shortening the readout time and thus the wavelength measurement time. Moreover, there is no need for a physical limiting mechanism to restrict light reception, and the configuration does not become complicated.

[0014] In particular, in this invention, the LED chip emits red (R), green (G), and blue (B) light, and the wavelength range required to measure the representative wavelength of each is generally limited, making it unnecessary to acquire signals across all wavelengths in the visible range. For example, when measuring an R-colored LED chip, it is sufficient to acquire signals in the 550-700nm range. Therefore, there is no problem in reading out signals from pixels while limiting the wavelength range, and the advantage of shortening wavelength measurement time due to reduced readout time can be enjoyed.

[0015] Furthermore, since LED chips are excited and emit light by excitation light, it is necessary to eliminate the influence of the excitation light. However, by limiting the wavelength range from which the measurement data is read out, it is possible to eliminate the influence of the excitation light as much as possible. Furthermore, each pixel in one pixel row of the area sensor receives light from multiple regions within the light-emitting surface of the LED chip, and each pixel in the other pixel row, which is orthogonal to the first pixel row, receives the light emitted and spectrally separated from each region for each wavelength. This allows light from multiple regions within the light-emitting surface of the LED chip to be spectrally separated for each wavelength and received by the pixels.

[0016] The preceding paragraph (2) and ( 12 According to the invention described above, the reading means selected to read out a signal form one reading means group, and since there are multiple reading means groups, signals in limited wavelength ranges can be read out by multiple reading means groups for LED chips of different colors.

[0017] The preceding paragraph (3) and ( 13 According to the invention described above, prior to the measurement, the calculation means can acquire spectral information of the LED chip based on the signals read by all the reading means, and from the acquired spectral information, it can accurately set the reading means that will read the signals in the measurement.

[0018] The preceding paragraph (4) and ( 14 According to the invention described above, prior to the measurement, the calculation means can acquire spectral information of the LED chip based on the signals read by all the reading means, and from the acquired spectral information, it can accurately select the group of reading means from which to read the signals in the measurement.

[0020] Previous item ( 5 ) and ( 15 According to the invention described above, the calculation means averages the signals from multiple regions within the light-emitting surface of the LED chip, so that the settings of the reading means for reading out the signals can be made with high accuracy.

[0021] Previous item ( 6 ) and ( 16 According to the invention described above, by moving the area sensor in a direction orthogonal to one of the pixel rows, light from a two-dimensional region within the light-emitting surface of the LED chip can be received.

[0022] Previous item ( 7 ) and ( 17 According to the invention described above, by moving the LED chip in a direction orthogonal to the column region on the light-emitting surface of the LED chip corresponding to one of the pixel columns, it is possible to receive light from a two-dimensional region on the light-emitting surface of the LED chip.

[0023] Previous item ( 8 ) and ( 18 According to the invention described in ( ), at least one of the emission peak wavelength, centroid wavelength, and center wavelength can be determined as a representative wavelength.

[0024] Previous item ( 9 According to the invention described above, the LED chip can be excited by the light source to emit light.

[0025] Previous item ( 10 ) and ( 19 According to the invention described above, the light receiving means and the reading means are composed of a CMOS sensor, and this CMOS sensor makes it possible to read signals from some pixels by some reading means. [Brief explanation of the drawing]

[0026] [Figure 1]This is a block diagram showing the configuration of a wavelength measuring device according to one embodiment of the present invention. [Figure 2] Figure 1 is a perspective view showing a specific configuration of part of the wavelength measuring device. [Figure 3] This is a circuit diagram showing an example configuration of a CMOS sensor. [Figure 4] This is an explanatory diagram regarding the setting of the wavelength readout range. [Figure 5] This diagram illustrates the relationship between the size of multiple LED chips on the object being measured and the size of the pixels in the light-receiving means. [Figure 6] This figure illustrates an example of determining the wavelength readout range in this measurement. [Figure 7] This figure illustrates another example of determining the wavelength readout range in this measurement. [Figure 8] (A), (B), and (C) are explanatory diagrams regarding the settings of the reading unit group. [Figure 9] This diagram schematically shows the data for the wavelength λ with the greatest brightness, extracted from the light received from the surface of the object being measured, within a suitable region of pixel data that includes measurement data for multiple LED chips, for example, light of an arbitrary wavelength. [Figure 10] (A) is a diagram showing the measurement data for each pixel separated for each LED chip, (B) is a diagram to explain the method for calculating the representative wavelength, and (C) is a magnified view of (B). [Figure 11] This is a spectral graph plotting the average values ​​of nine pixels for each wavelength in the data area of ​​multiple LED chips. [Figure 12] This is a spectral graph plotting the values ​​of a single pixel for each wavelength across the data regions of multiple LED chips. [Figure 13] This graph shows the average value calculated for each wavelength of nine pixels within the data area of ​​a single LED chip, along with the corresponding fitting curve. [Figure 14] This diagram illustrates a measurement method for objects with a wide measurement range. [Modes for carrying out the invention]

[0027] Hereinafter, embodiments of this invention will be described based on the drawings.

[0028] Figure 1 is a block diagram showing the configuration of a wavelength measuring device according to one embodiment of the present invention. In this embodiment, the case in which the object to be measured 100 is a wafer on which a plurality of LED chips are formed will be described.

[0029] The wavelength measuring device shown in Figure 1 comprises an excitation light source 1, an objective lens 2 with adjustable magnification, a spectroscopic unit 3, an imaging lens 4, an area sensor 5 which is a two-dimensional image sensor, a calculation unit 6, and a measurement result display unit 7 which is composed of a liquid crystal display device or the like.

[0030] The excitation light source 1 irradiates multiple LED chips on the object to be measured 100 with excitation light, exciting the multiple LED chips and causing them to emit light.

[0031] The spectral unit 3 separates the light from each LED chip that has passed through the objective lens 2 into wavelengths, and the imaging lens 4 images the light of each wavelength separated by the spectral unit 3 onto the area sensor 5. In this embodiment, the light is separated into wavelengths with a wavelength pitch of 5 nm.

[0032] The area sensor 5 corresponds to a light-receiving means and is equipped with multiple pixels 51 arranged vertically and horizontally as shown in Figure 2. The horizontal direction of the area sensor 5 (spatial X direction in Figure 2) refers to the horizontal direction of physical space, and each pixel 51 in the horizontal direction corresponds to a horizontal region of the object to be measured 100. On the other hand, the vertical direction of the area sensor 5 (wavelength Z direction in Figure 2) corresponds to the wavelength of light. In other words, each pixel 51 in the pixel row in the spatial X direction corresponds to multiple one-dimensional regions (row regions) 100a of the object to be measured 100. Light emitted from the row regions 100a passes through the objective lens 2 and enters the slit 31 of the spectrometer 3, and the light that is wavelength-decomposed by the spectrometer 3 is received by each pixel 51 in the pixel row in the wavelength Z direction. Therefore, in order to perform spectroscopic measurements on each region in the two-dimensional direction (plane) of the object to be measured 100, it is necessary to move (scan) the object to be measured 100 in the Z1 direction, which is orthogonal to the one-dimensional row regions 100a. Alternatively, instead of moving the object to be measured 100, the wavelength measuring device including the area sensor 5 may be moved in the wavelength Z direction perpendicular to the spatial X direction in Figure 2, or both the object to be measured 100 and the wavelength measuring device may be moved with a speed difference. In short, at least one of the object to be measured 100 and the wavelength measuring device should be moved relative to the other.

[0033] Each time the object 100 is moved relative to the measurement target, the column region 100a of the measurement target 100 switches, and spectral data for each column region 100a is obtained as one frame, resulting in multiple frames of spectral data which are accumulated as spectral data cubes. In this embodiment, the measurement target 100 (LED chip 101) is moved, and as shown in Figure 1, a moving device 300 is provided that can move the table 200 on which the measurement target 100 is placed.

[0034] Furthermore, the technique of obtaining spectral data by dividing the plane of the object to be measured 100 into regions corresponding to the size of each pixel 51 of the area sensor 5, spectrally analyzing the light from each region and receiving it with each pixel 51 of the area sensor 5, and repeating this while moving at least one of the object to be measured 100 and the wavelength measuring device relative to the other, is called the pushbloom method and is known, for example, in hyperspectral cameras.

[0035] In this embodiment, the area sensor 5 is a sensor that has multiple readout units that read signals from each pixel and can specify a readout range, and a CMOS sensor is used, for example. Hereinafter, the area sensor will also be referred to as the CMOS sensor. A schematic example of the configuration of the CMOS sensor 5 is shown in Figure 3.

[0036] In the CMOS sensor 5 shown in Figure 3, each pixel 51 is equipped with a light-receiving element 511 made of a photodiode or the like, an amplifier 512 that converts and amplifies the charge accumulated by the light-receiving element 511 into a voltage, and a pixel selection switch 513. The pixel selection switch 513 of each pixel 51 is connected to the corresponding vertical signal line 52 among a plurality of vertical signal lines 52 arranged for each pixel 51 in a vertical column. The vertical signal lines 52 are connected to horizontal signal lines 55 via a CDS circuit 53 and a column selection switch 54.

[0037] Therefore, by turning on the pixel selection switch 513 of the pixel 51 whose signal is to be read, connecting the photodetector 511 and the vertical signal line 52, and then turning on the column selection switch 54 to connect the vertical signal line 52 to the horizontal signal line 55, the signal of the selected pixel 51 can be read via the vertical signal line 52 and the horizontal signal line 55. In other words, a signal readout section for each pixel 51 is formed by the pixel selection switch 513 of each pixel 51, the vertical signal line 52 and horizontal signal line 55 common to multiple pixels 51, and the column selection switch 54, etc., and by controlling the signal readout section, the signal of any pixel 51 can be read.

[0038] Therefore, as shown in Figure 4, a reading range W2 is set from the entire reading area W1 in the wavelength Z direction of the area sensor 5, and the reading units of multiple pixels 51 located within the set reading range W2 are set as a single reading unit group. This makes it possible to read out only the signals for wavelengths within the specified range W2 from the wavelengths spectrally analyzed by the spectral unit 3.

[0039] The measurement data, which consists of signals output from multiple pixels 51 of the area sensor 5 with a specified reading range, is converted into digital signals as needed through a current-to-voltage (IV) conversion circuit and an analog-to-digital (AD) conversion circuit (not shown), and sent to the arithmetic unit 6. The arithmetic unit 6 uses the received measurement data to calculate the representative wavelength for each of the multiple LED chips on the object being measured using a CPU or the like. Details of the method for calculating the representative wavelength will be described later.

[0040] The measurement result display unit 7 displays the calculation results from the calculation unit 6. Note that the conversion of the measurement data output from the area sensor 5 into a digital signal may also be performed by the calculation unit 6.

[0041] The calculation unit 6 may be a dedicated device or it may be composed of a personal computer. Furthermore, the measurement data output from the area sensor 5 and processed into a digital signal may be sent to the calculation unit 6 via a network. In this case, the representative wavelength of the LED chip can be measured even if the calculation unit 6 is located far from the measurement site.

[0042] Next, we will explain how to measure the representative wavelength of each LED chip on the wafer, which is the object to be measured, using the wavelength measuring device shown in Figure 1.

[0043] Figure 5 illustrates the relationship between the size of multiple LED chips 101 on the object 100 to be measured and the size of the pixels 51 of the area sensor 5. In Figure 5, the horizontal axis of the fine grid represents the spatial X direction, and the vertical axis represents the spatial Y direction, which is created by scanning the LED chips 101 in the wavelength Z direction. The size of one grid corresponds to the measurement area and the size of the pixels 51.

[0044] The LED chips 101 are displayed as rectangles and are arranged vertically and horizontally on the object 100 to be measured. The rectangular area itself becomes the light-emitting surface of each LED chip 101.

[0045] The arrangement of the LED chips 101, the pixel pitch of the area sensor 5, and the magnification of the objective lens 2 are set so that data can be acquired by multiple pixels 51 for the light-emitting surface of a single LED chip 101. In other words, light emitted from multiple areas of the light-emitting surface of a single LED chip 101, each corresponding to a pixel 51, can be received by the corresponding multiple pixels 51. In this embodiment, the light from the light-emitting surface of a single LED chip 101 is divided and received by 3 x 3 = 9 or more pixels.

[0046] Next, before performing the main measurement, a preliminary measurement is performed to determine the readout range in the wavelength Z direction, or in other words, the wavelength region to be readout.

[0047] First, one line of signal in the spatial X direction, i.e., one frame of measurement data, is read from the pixels corresponding to the entire wavelength range (380-780 nm) (all pixels in the wavelength Z direction in Figures 2 and 4). The read-out measurement data for one frame consists of spectral data (brightness data at each wavelength) with a wavelength pitch of 5 nm.

[0048] Next, the wavelength λ0 of the pixel 51 with the highest brightness is determined from the data of a suitable group of pixels in a region encompassing multiple LED chips 101. Alternatively, λ0 may be the average of the wavelengths of multiple pixels 51 with the highest brightness, rather than the wavelength of the pixel 51 with the highest brightness. Averaging the wavelengths improves the accuracy of the wavelength λ0.

[0049] Centered around the determined wavelength λ0, a predetermined range, for example, ±75 nm, is set as the readout range, or wavelength range for the actual measurement (hereinafter also referred to as the actual measurement wavelength range). As an example, as shown in Figure 6, if the determined wavelength λ0 is 626.0 nm, the actual measurement wavelength range is set to 626.0 ± 75 nm, which is 551 nm to 701 nm. Note that ±75 nm may be any other value. By determining the actual measurement wavelength range, a group of readout units consisting of some of the readout units that perform readings from all the readout units of the area sensor 5 is set.

[0050] Another method for determining the main measurement wavelength range through pre-measurement is to select from several pre-prepared main measurement wavelength ranges based on the determined wavelength λ0 value. For example, as shown in Figure 7, if the LED chip 101 is blue, the main measurement wavelength range WB is pre-set to 390-540nm (center wavelength: 465nm); if it is green, the main measurement wavelength range WG is pre-set to 465-615nm (center wavelength: 540nm); and if it is red, the main measurement wavelength range WR is pre-set to 550-700nm (center wavelength: 625nm).

[0051] Then, if the wavelength λ0 is close to 465 nm, the main measurement wavelength range WB of 390-540 nm set for blue is selected; if the wavelength λ0 is close to 540 nm, the main measurement wavelength range WG of 465-615 nm set for green is selected; and if the wavelength λ0 is close to 625 nm, the main measurement wavelength range WR of 550-700 nm set for red is selected. The selection of the main measurement wavelength range sets the readout group that reads out the pixels 51. For example, if the main measurement wavelength range WR is determined, as shown in Figure 8(A), the readout group 50R that reads out the measurement data of multiple pixels 51 corresponding to the main measurement wavelength range WR is set; if the main measurement wavelength range WG is determined, as shown in Figure 8(B), the readout group 50G that reads out the measurement data of multiple pixels 51 corresponding to the main measurement wavelength range WG is set; and if the main measurement wavelength range WB is determined, as shown in Figure 8(C), the readout group 50B that reads out the measurement data of multiple pixels 51 corresponding to the main measurement wavelength range WB is set. In this way, a different readout group is selected from among the multiple readout groups 50R, 50G, and 50B, depending on the measurement wavelength range.

[0052] Furthermore, as yet another method for determining the measurement wavelength range, if the emission color of the LED chip 101 is known in advance, the measurement wavelength ranges WB, WG, and WR, which are pre-set for blue, green, and red respectively, may be selected without performing a pre-measurement. In this case as well, among the readout groups 50R, 50G, and 50B, readout groups 50B, 50G, and 50R corresponding to the measurement wavelength ranges WB, WG, and WR will be set.

[0053] Thus, after determining the wavelength range for the measurement and setting up a group of readout units corresponding to multiple pixels 51 that will read out the signal, the measurement is performed as follows.

[0054] Specifically, the object to be measured 100, placed on the table 200, is irradiated with excitation light from the excitation light source 1. The table 200 is moved by the moving device 300, and the light emitted from multiple LED chips 101 on the object to be measured 100 is received by each pixel 51 of the area sensor 5. The light emitted from the LED chips 101 is spectrally separated into predetermined wavelengths by the spectral unit 3, and the light of each spectrally separated wavelength is received by each pixel 51. The movement of the table 200 is performed after reading out the measurement wavelength range for one frame of measurement data. If exposure is complete, the table 200 may be moved during the reading process, etc.

[0055] Of all the pixels 51 that receive light, measurement data is read out from the pixels 51 only in the readout section group that is set to correspond to the main measurement wavelength range determined in the pre-measurement.

[0056] The read measurement data is sent to the calculation unit 6 and stored in a memory (not shown) within the calculation unit 6. The measurement is performed by moving the object to be measured 100 on the table 200 using the moving device 300. Since one frame of measurement data is obtained with each movement (each scan), multiple frames of measurement data are obtained for the two-dimensional direction of the object to be measured 100, or in other words, for a planar region. Furthermore, in each frame, measurement data is read only for the pixels 51 corresponding to the reading unit group, and measurement data is obtained for wavelengths within the measurement wavelength range among the spectrally separated wavelengths.

[0057] Based on the measurement data obtained in this way, the calculation unit 6 calculates the representative wavelength of each LED chip 101.

[0058] Figure 9 schematically shows the data for the wavelength λ with the greatest brightness, extracted from the data of a suitable region of pixel group that includes light of an arbitrary wavelength, such as measurement data from multiple LED chips 101, from the light received from the surface of the object 100 being measured. The black frame 8 in Figure 9 indicates the region corresponding to the light-emitting surface of one LED chip 101. Furthermore, the darkly shown region 9 indicates high brightness, and the brightness decreases towards the periphery.

[0059] Next, the measurement data received by each pixel 51 of the area sensor 5 is separated for each LED chip 10. This separation can be done, for example, as follows: From the data of a group of pixels in an appropriate region that includes the measurement data of multiple LED chips 101, the wavelength λ with the maximum brightness is determined. Next, each pixel 51 is divided into levels based on brightness at wavelength λ, and by performing image processing with a certain brightness level as a threshold, the data can be separated for each LED chip 101. Figure 10(A) shows the state after the measurement data from each pixel 51 has been separated for each LED chip 101. In Figure 10(A), the data is separated into nine data regions 10a to 10i, indicated by black frames.

[0060] Next, for each separated LED chip 101, the pixel of interest that yielded the maximum brightness (luminance value) is identified. For example, as shown in Figure 10(B), if the maximum value at a certain wavelength is obtained at the pixel of interest 51a in the measurement data of a data area (e.g., data area 10b) for one LED chip 101, then this pixel 51a is identified as the pixel of interest. Here, the certain wavelength is a wavelength used solely to find the separated brightness level or the pixel of interest. For example, as mentioned above, it could be the wavelength with the maximum brightness among the data of a group of pixels in an appropriate region encompassing the measurement data of multiple LED chips 101, or the wavelength with the maximum brightness among the measurement data of a data area for one LED chip, or the design wavelength of the LED chip, etc.

[0061] After identifying the pixel of interest 51a, the value of the pixel of interest 51a and the values ​​of one or more pixels surrounding the pixel of interest 51a at a certain wavelength are averaged to obtain spectral data (brightness data at that wavelength). In the example in Figure 10(B), as shown in an enlarged view in Figure 10(C), the values ​​of a total of nine pixels 51, including the eight pixels 51b to 51i surrounding the pixel of interest 51a and the pixel of interest 51a, are averaged.

[0062] By averaging the data from multiple pixels, including the pixel of interest 51a, in this way, the effect of reducing measurement noise can be obtained.

[0063] Furthermore, the reason for averaging the pixels surrounding the pixel of interest 51a is to keep the wavelength measurement area of ​​the LED chip 101 within the light-emitting surface, allowing for the acquisition of values ​​with less influence from variability using a relatively small number of data points. Specifically, by using the values ​​of the nine surrounding pixels, including the pixel of interest 51a which showed the maximum brightness, it is possible to obtain values ​​with sufficiently little influence from variability.

[0064] Figure 11 is a spectral graph plotting the average values ​​of nine pixels for each wavelength in four data regions 10b, 10d, 10f, and 10h of the data regions 10a to 10i of the multiple LED chips 101 shown in Figure 10(A). On the other hand, Figure 12 is a spectral graph plotting only the values ​​of the pixel of interest 51a, obtained for each wavelength in the same four data regions 10b, 10d, 10f, and 10h. In both graphs, the horizontal axis represents wavelength and the vertical axis represents brightness. Comparing the two graphs, it can be seen that the spectral shape is distorted in Figure 12, which shows only the values ​​of the pixel of interest 51a.

[0065] The brightness values ​​of the target pixel 51a and its surrounding pixels 51b to 51i are averaged for each wavelength, and the representative wavelength is determined from the average value obtained for each wavelength. Specifically, as shown in Figure 13, a fitting curve is obtained using Gaussian fitting or the like based on the average value for each wavelength, and the wavelength of the peak value of the fitting curve is taken as the representative wavelength. In cases where the wavelength pitch is small, the wavelength of the largest average value among the average values ​​for each wavelength may be taken as the representative wavelength without fitting.

[0066] In this way, a representative wavelength is calculated from the measurement data for all LED chips 101 of the object to be measured 100. The representative wavelength calculated in this embodiment is the emission peak wavelength, but it may also be the centroid wavelength or center wavelength. The centroid wavelength is a weighted average of wavelengths weighted by the emission spectrum. In other words, the centroid wavelength is the value obtained by dividing the value obtained by integrating the product of each wavelength and the light intensity of that wavelength over the entire emission wavelength range by the value obtained by integrating the light intensity over the entire emission wavelength range. The center wavelength is the average of two half-maximum wavelengths that are 3 dB lower than the maximum amplitude on both sides of the peak wavelength.

[0067] As described above, in this embodiment, instead of reading the signals from all pixels 51 corresponding to the entire spectrally analyzed wavelength range, the measurement wavelength range for reading is determined, and the signals are read out by a group of reading units consisting of reading units for some pixels 51 that are set to correspond to the determined measurement wavelength range. Therefore, it is not necessary to read out the signals from all pixels, which shortens the reading time, the wavelength measurement time, and consequently the binning time. Moreover, since there is no need for a physical limiting unit to restrict the reception of light from pixels 51 that are not being read, the configuration does not become complicated.

[0068] In particular, the LED chip 101 emits red (R), green (G), and blue (B) light, and the wavelength range required to measure the representative wavelength of each is generally limited. Since it is not necessary to acquire signals at all wavelengths in the visible range, there is no problem in reading out the signal from the pixel 51 by limiting the wavelength range, and the advantage of shortening the wavelength measurement time due to the shortened readout time can be enjoyed.

[0069] Incidentally, when the integration time of the CMOS sensor 5 is set to 1 ms and the measurement wavelength range is 400 nm, which covers the entire visible spectrum, the frame rate, which indicates the number of frames that can be read out per second, is approximately 520 FPS. However, when the wavelength measurement range is limited to 150 nm, the frame rate can be increased to approximately 920 FPS, thus shortening the readout time.

[0070] Furthermore, since the LED chip 101 is excited and emits light by excitation light, it is necessary to eliminate the influence of the excitation light. However, by limiting the wavelength range from which the measurement data is read out, it is possible to eliminate the influence of the excitation light as much as possible.

[0071] This application is accompanied by a priority claim from Japanese Patent Application No. 2021-118071, filed on 16 July 2021, and the disclosures thereof constitute a part of this application. [Industrial applicability]

[0072] This invention can be used to measure the characteristic wavelength of an LED chip. [Explanation of symbols]

[0073] 1. Light source for excitation 2. Objective lens 3 Spectroscopic section 4. Imaging lens 5. Area sensor (light receiving means) 51 pixels 511 Photodetector 512 Amplifier 513 Pixel Selection Switch 52 Vertical signal lines 54 Column Selection Switch 55 Horizontal signal line 6 Arithmetic section 7 Measurement result display section 10a~10i Data Area 100 Objects to be measured 100a column area 101 LED chips (LED chips) 200 tables 300 Mobile devices WB, WG, WR Wavelength range in this measurement 50B, 50G, 50R Readout Unit Group

Claims

1. A spectral means for spectrally analyzing the light emitted when an LED chip is excited, A light-receiving means having a plurality of pixels that receive light spectrally separated by the spectral means for each wavelength, Multiple reading means corresponding to each of the aforementioned multiple pixels, which can read signals from each pixel and select whether or not to read the signals, A calculation means that calculates the representative wavelength of the LED chip based on the signal read out by the reading means selected from the plurality of reading means to read out the signal, Equipped with, The light receiving means is an area sensor, A wavelength measuring device in which each pixel of one pixel row of the area sensor receives light from multiple regions within the light-emitting surface of an LED chip, and each pixel of the other pixel row orthogonal to the first pixel row receives light emitted and spectrally separated from each region at each wavelength.

2. The wavelength measuring apparatus according to claim 1, wherein the reading means selected to read out a signal forms one group of reading means, and there are multiple groups of reading means.

3. The wavelength measuring apparatus according to claim 1 or 2, wherein the calculation means acquires spectral information of the LED chip based on the signals read out by all the reading means prior to the measurement, and sets up a reading means for reading signals in the measurement from the acquired spectral information.

4. The wavelength measuring apparatus according to claim 2, wherein the calculation means acquires spectral information of the LED chip based on the signals read out by all the reading means prior to the measurement, and selects a group of reading means to read signals in the measurement from the acquired spectral information.

5. The wavelength measuring device according to claim 1, wherein the calculation means averages signals from multiple regions within the light-emitting surface of the LED chip.

6. The wavelength measuring device according to claim 1, wherein the area sensor is moved in a direction orthogonal to one of the aforementioned pixel rows, thereby receiving light from a two-dimensional region within the light-emitting surface of the LED chip.

7. The wavelength measuring device according to claim 1, wherein the LED chip is moved in a direction orthogonal to the row region on the light-emitting surface of the LED chip corresponding to one of the aforementioned pixel rows, thereby receiving light from a two-dimensional region on the light-emitting surface of the LED chip.

8. The wavelength measuring device according to claim 1, wherein the representative wavelength is at least one of the emission peak wavelength, centroid wavelength, and center wavelength.

9. The wavelength measuring device according to claim 1, further comprising a light source unit that excites the LED chip to emit light.

10. The wavelength measuring device according to claim 1, wherein the light receiving means and the reading means are configured by a CMOS sensor.

11. A spectral step in which the light emitted when an LED chip is excited is spectrally separated using a spectral means, A light receiving step in which the light spectrally separated by the above spectral step is received by a light receiving means having a plurality of pixels for each wavelength, A reading step in which, among a plurality of reading means corresponding to each of the plurality of pixels, which read signals from each pixel and can select the pixel from which to read signals, the reading means selected to read the signals reads the signals. A calculation step is performed to calculate the representative wavelength of the LED chip based on the signal read out in the above reading step, Includes, The light receiving means is an area sensor, A wavelength measurement method comprising: each pixel of one pixel row of the area sensor receiving light from multiple regions within the light-emitting surface of an LED chip; and each pixel of the other pixel row orthogonal to the first pixel row receiving light emitted and spectrally separated from each region, wavelength by wavelength.

12. The wavelength measurement method according to claim 11, wherein the reading means selected to read out a signal forms one group of reading means, and there are multiple groups of reading means.

13. The wavelength measurement method according to claim 11 or 12, wherein, in the calculation step, prior to the measurement, spectral information of the LED chip is acquired based on the signals read by all reading means, and a reading means for reading signals in the measurement is set from the acquired spectral information.

14. The wavelength measurement method according to claim 12, wherein, in the calculation step, spectral information of the LED chip is acquired based on the signals read by all reading means prior to the measurement, and a group of reading means for reading signals in the measurement is selected from the acquired spectral information.

15. The wavelength measurement method according to claim 11, wherein the calculation step averages the signals from multiple regions within the light-emitting surface of the LED chip.

16. The wavelength measurement method according to claim 11, wherein the area sensor is moved in a direction orthogonal to one of the pixel rows, thereby receiving light from a two-dimensional region within the light-emitting surface of the LED chip.

17. The wavelength measurement method according to claim 11, wherein the LED chip is moved in a direction orthogonal to the row region on the light-emitting surface of the LED chip corresponding to one of the aforementioned pixel rows, thereby receiving light from a two-dimensional region on the light-emitting surface of the LED chip.

18. The wavelength measurement method according to claim 11, wherein the representative wavelength is at least one of the emission peak wavelength, centroid wavelength, and center wavelength.

19. The wavelength measurement method according to claim 11, wherein the light receiving means and the reading means are configured by a CMOS sensor.

Images