Inspection method, inspection device, and program

Abstract

To provide an inspection method or the like capable of performing autofocusing with high focusing accuracy and at high speed without requiring dedicated hardware.SOLUTION: The inspection method includes: acquisition step (S12) of acquiring a one-dimensional brightness profile by subjecting an inspection image in a pixel area of a display panel photographed by a photographing device to image processing for compressing the brightness of the inspection image into one-dimensional brightness; generation step (S13) of generating a frequency spectrum intensity profile by Fourier-transforming the one-dimensional brightness profile; calculation step (S14) of calculating the magnification of the photographing device from one or more peak positions in the frequency spectrum intensity profile on the basis of the periodic structure of pixels shown in the pixel area; and estimation step (S15) of estimating a current focus position, which is the focus position of the photographing device in the inspection image, from the calculated magnification and magnification information indicating a relationship between a focus position and magnification of the photographing device.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present disclosure relates to an inspection method, an inspection apparatus, and a program. [Background technology]

[0002] In the production process of display panels, various inspections are carried out to maintain product quality, and image inspection accounts for a large portion of these.

[0003] In recent years, image inspection requires high-quality images not only to improve the accuracy of judgment by an operator but also to improve the accuracy of judgment by automatic inspection.

[0004] In order to perform image inspection with high-quality images, inspection devices generally employ high-quality imaging elements or optical systems, etc. In addition, to obtain high-quality images, an autofocus mechanism related to the focus accuracy of the image is also important, and an autofocus mechanism such as a contrast detection AF is used in inspection devices (for example, Patent Document 1).

[0005] Contrast detection AF is a method that searches for the contrast peak of an image while changing the focus position. In other words, contrast detection AF does not require dedicated AF hardware, and performs autofocus processing using the image itself. For this reason, contrast detection AF has the advantage of high focusing accuracy. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 3316684 Summary of the Invention [Problem to be solved by the invention]

[0007] However, while the contrast detection AF used in Patent Document 1 has the advantage of high focusing accuracy, it has the disadvantage of slow operating speed because it is not clear whether the out-of-focus camera position is in the + or - direction from the in-focus position. Since takt time is an important element for inspection equipment, using contrast detection AF in inspection equipment has a major weakness.

[0008] In addition to contrast detection AF, laser AF is also known as an autofocus mechanism. Laser AF has the advantage of being fast in operation because it is a method of irradiating a panel with laser light and directly measuring the distance to the panel surface. However, laser AF has the disadvantage that it requires dedicated AF hardware, and high-precision AF hardware is expensive. Furthermore, when laser AF is used in an inspection device, the distance between the laser detector and the display panel surface is measured, which creates problems such as the need for calibration to convert the measured distance into the distance between the optical system used to adjust the focus position and the display panel surface.

[0009] The present disclosure has been made in consideration of the above-mentioned circumstances, and aims to provide an inspection method and the like that can perform processing for high-speed autofocusing without requiring dedicated hardware. [Means for solving the problem]

[0010] In order to achieve the above-mentioned object, an inspection method according to one embodiment of the present disclosure is a display panel inspection method performed by a computer, and includes: an acquisition step of acquiring a one-dimensional luminance profile by performing image processing to compress the luminance of an inspection image of a pixel region of the display panel captured by an imaging device into a one-dimensional luminance whose axis is a vertical direction of an arrangement direction of a plurality of sub-pixels that constitute one pixel in a plurality of pixels, each of which is composed of a plurality of sub-pixels; a generation step of generating a frequency spectrum intensity profile by performing Fourier transform processing on the one-dimensional luminance profile; a calculation step of calculating the imaging magnification of the imaging device from one or more peak positions included in the frequency spectrum intensity profile based on the fact that the plurality of pixels are formed in a periodic structure in the pixel region; and an estimation step of estimating a current focus position, which is the focus position of the imaging device in the inspection image, from magnification information indicating the relationship between the focus position and the imaging magnification in the imaging device and the calculated imaging magnification.

[0011] In this way, the current focus position of the photographing device 20 in the test image can be estimated only by calculation processing without requiring dedicated hardware. In addition, due to the performance of recent computers equipped with processors, etc., it is possible to quickly perform one-dimensional luminance compression and Fourier transform processing of the test image photographed by the photographing device 20.

[0012] Therefore, according to the inspection method of this aspect, it is possible to perform the process for autofocusing at high speed without requiring dedicated hardware.

[0013] In addition, in the calculation step, a peak position of a fundamental frequency among the one or more peak positions may be estimated to be a peak position corresponding to a one-pixel unit structure of the pixel area shown in the test image, and the shooting magnification of the shooting device may be calculated from the peak position of the fundamental frequency.

[0014] Also, for example, in the generating step, the frequency spectrum intensity profile may be generated by performing a Fourier transform process twice on the one-dimensional luminance profile.

[0015] Furthermore, for example, the magnification information may be information indicating a relationship between the multiple focus positions and the imaging magnification, the value of the fundamental frequency obtained by Fourier transform processing of a one-dimensional luminance profile of an image of a pixel area of ​​a display panel captured by the imaging device at each of the multiple focus positions of the imaging device.

[0016] Also, for example, the method may further include an adjustment step of calculating an amount of movement of the image capturing device required for focusing from the estimated current focus position and the magnification information, and adjusting a position of the image capturing device using the amount of movement.

[0017] In addition, in order to achieve the above-mentioned object, an inspection device according to one embodiment of the present disclosure is an inspection device for a display panel, and includes an acquisition unit that acquires a one-dimensional luminance profile by performing image processing to compress the luminance of an inspection image of a pixel region of the display panel captured by an imaging device into a one-dimensional luminance whose axis is a vertical direction of an arrangement direction of a plurality of sub-pixels that constitute one pixel in a plurality of pixels, each of which is composed of a plurality of sub-pixels; a generation unit that generates a frequency spectrum intensity profile by performing Fourier transform processing on the one-dimensional luminance profile; a calculation unit that calculates the imaging magnification of the imaging device from one or more peak positions included in the frequency spectrum intensity profile based on the fact that the plurality of pixels are formed in a periodic structure in the pixel region; and an estimation unit that estimates a current focus position, which is the focus position of the imaging device in the inspection image, from magnification information indicating the relationship between the focus position and the imaging magnification in the imaging device and the calculated imaging magnification.

[0018] In addition, in order to achieve the above-mentioned object, a program according to one embodiment of the present disclosure is a program for causing a computer to execute an inspection method for a display panel, and causes the computer to execute the following steps: an acquisition step of acquiring a one-dimensional luminance profile by performing image processing to compress the luminance of an inspection image of a pixel region of the display panel captured by an imaging device into a one-dimensional luminance whose axis is a vertical direction of an arrangement direction of a plurality of sub-pixels that constitute one pixel in a plurality of pixels, each of which is composed of a plurality of sub-pixels; a generation step of generating a frequency spectrum intensity profile by performing Fourier transform processing on the one-dimensional luminance profile; a calculation step of calculating the imaging magnification of the imaging device from one or more peak positions included in the frequency spectrum intensity profile based on the fact that the plurality of pixels are formed in a periodic structure in the pixel region; and an estimation step of estimating a current focus position, which is the focus position of the imaging device in the inspection image, from magnification information indicating the relationship between the focus position and the imaging magnification in the imaging device and the calculated imaging magnification.

[0019] Furthermore, these general or specific aspects may be realized by an apparatus, a method, an integrated circuit, a computer program, or a recording medium such as a computer-readable CD-ROM, or may be realized by any combination of a system, a method, an integrated circuit, a computer program, and a recording medium. Effect of the Invention

[0020] The present disclosure makes it possible to provide an inspection method that can perform autofocusing with high focusing accuracy and at high speed without requiring dedicated hardware. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of an inspection system including an inspection device according to an embodiment. [Diagram 2] FIG. 2 is a diagram showing an example of a hardware configuration of a computer that realizes the functions of the inspection device according to the embodiment by software. [Diagram 3] FIG. 3 is a block diagram illustrating an example of a functional configuration of an inspection device according to an embodiment. [Figure 4] FIG. 4 is an example of an inspection image of a pixel region of a display panel according to an embodiment. [Diagram 5] FIG. 5 is a diagram showing a one-dimensional luminance profile when the luminance of the inspection image shown in FIG. 4 is compressed on the X-axis. [Figure 6] FIG. 6 is a diagram showing a one-dimensional luminance profile when the luminance of the inspection image shown in FIG. 4 is compressed on the Y axis. [Figure 7A] FIG. 7A is another example of an inspection image of a pixel region of a display panel according to an embodiment. [Figure 7B] FIG. 7B is a diagram showing a one-dimensional luminance profile when the luminance of the test image shown in FIG. 7A is compressed along the Y axis. [Figure 8] FIG. 8 is a diagram for explaining an example of a one-dimensional luminance profile subjected to fast Fourier transform processing by the generating unit according to the embodiment. [Figure 9] FIG. 9 is a diagram showing a frequency spectrum intensity profile when the fast Fourier transform process is performed twice on the one-dimensional luminance profile of FIG. [Figure 10] FIG. 10 is a diagram for explaining another example of a one-dimensional luminance profile subjected to fast Fourier transform processing by the generating unit according to the embodiment. [Figure 11] FIG. 11 is a diagram showing a frequency spectrum intensity profile when the fast Fourier transform process is performed twice on the one-dimensional luminance profile of FIG. 7B. [Figure 12] FIG. 12 is a diagram showing an example of magnification information in the case where the value of the fundamental frequency according to the embodiment is set as the imaging magnification. [Figure 13] FIG. 13 is a flowchart showing the operation of the inspection device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, the embodiments of the present disclosure will be described in detail with reference to the drawings. Note that each of the embodiments described below shows a specific example of the present disclosure. The numerical values, shapes, materials, standards, components, the arrangement and connection forms of the components, steps, and the order of steps shown in the following embodiments are merely examples and are not intended to limit the present disclosure. In addition, among the components in the following embodiments, components that are not described in the independent claims of the present disclosure are described as optional components. In addition, each figure is not necessarily a strict illustration. In each figure, substantially the same configuration is given the same symbol, and duplicated explanations may be omitted or simplified.

[0023] (Embodiment) The inspection device and the like according to this embodiment will be described below.

[0024] [1. Inspection system] The inspection device 10 according to the present embodiment will be described below with reference to the drawings.

[0025] FIG. 1 is a diagram showing a schematic configuration of an inspection system including an inspection device 10 according to the present embodiment.

[0026] The inspection system shown in FIG. 1 includes an inspection device 10, an imaging device 20, a stage 21, and a stage driving unit 22.

[0027] The inspection device 10 is a device for performing image inspection using an inspection image obtained by capturing a pixel region of a display panel 30. Here, the display panel 30 is a liquid crystal display panel, an organic EL display panel, or the like, and may be a rigid panel or a flexible panel. A plurality of pixels are arranged in a matrix in the pixel region of the display panel 30. Each of the plurality of pixels is composed of a plurality of sub-pixels, such as RGB sub-pixels.

[0028] The photographing device 20 is configured with an optical system that focuses the lens by a full group extension method or the like, and photographs the pixel area of ​​the display panel 30. In an optical system such as a full group extension method, there is a strong correlation between the focus position and the photographing magnification. The photographing device 20 may be configured with an optical system that focuses the lens by an inner focus or the like, and photograph the pixel area of ​​the display panel 30. There is also a strong correlation between the focus position and the photographing magnification in an optical system such as an inner focus. The photographing magnification is the ratio between the size of the image reflected on the photographing surface and the actual size of the subject. In addition, the photographing device 20 is kept at a substantially constant distance from the display panel 30 as shown in FIG. 1, and the focus position is adjusted by moving as shown in (a) to (c) of FIG. 1. In FIG. 1, (b) of FIG. 1 shows an example where the focus position is correct, i.e., the in-focus position, and (a) and (c) of FIG. 1 show an example where the focus position is correct, i.e., the in-focus position, and (a) and (c) of FIG. 1 show an example where the focus position is out of focus.

[0029] The photographing device 20 captures an inspection image of the display panel 30 by photographing a pixel region of the display panel 30. The photographing device 20 can adjust the focus position of the optical system of the photographing device 20 by moving to a position such as (a), (b) or (c) shown in Fig. 1. The photographing device 20 is controlled by the inspection device 10, but may be controlled by another computer.

[0030] The stage 21 holds a display panel 30 .

[0031] The stage driving unit 22 is composed of a ball screw, a guide rail, and a motor, and moves the stage 21 relatively to the imaging device 20. The stage driving unit 22 is controlled by the inspection device 10, but may be controlled by another computer.

[0032] [1-1. Hardware configuration of inspection device 10] Before describing the functional configuration of the inspection device 10 according to the present embodiment, an example of the hardware configuration of the inspection device 10 according to the present embodiment will be described with reference to FIG.

[0033] FIG. 2 is a diagram showing an example of a hardware configuration of a computer 1000 that realizes the functions of the inspection device 10 according to the present embodiment by software.

[0034] 2, the computer 1000 is a computer including an input device 1001, an output device 1002, a CPU 1003, an internal storage 1004, a RAM 1005, a GPU 1006, a reading device 1007, a transmission / reception device 1008, and a bus 1009. The input device 1001, the output device 1002, the CPU 1003, the internal storage 1004, the RAM 1005, the reading device 1007, and the transmission / reception device 1008 are connected by the bus 1009.

[0035] The input device 1001 is a user interface device such as an input button, a touch pad, a touch panel display, etc., and accepts user operations. The input device 1001 may be configured to accept voice operations and remote operations using a remote control or the like in addition to accepting touch operations by the user.

[0036] The output device 1002 is used in combination with the input device 1001, and is configured with a touch pad or a touch panel display, etc., to notify the user of information that should be made known to the user.

[0037] The built-in storage 1004 is a flash memory or the like. The built-in storage 1004 may store in advance at least one of a program for implementing the functions of the inspection device 10 and an application using the functional configuration of the inspection device 10. The built-in storage 1004 may store a procedure for performing image processing, which will be described later, a formula for Fourier Transformation (FFT) processing, a formula for Fast Fourier Transformation (FFT) processing, a procedure including a program, a calculation procedure for the imaging magnification of the imaging device 20, a procedure for estimating the current focus position of the imaging device 20, magnification information of the imaging device 20, and the like.

[0038] The RAM 1005 is a random access memory, and is used to store data and the like when a program or application is executed.

[0039] The GPU 1006 is a graphics processing unit that copies programs, applications, and data stored in the internal storage 1004 to a dedicated RAM built into the GPU, and performs image processing according to the instructions contained in the programs and applications.

[0040] The reading device 1007 reads information from a recording medium such as a USB (Universal Serial Bus) memory. The reading device 1007 reads the above-mentioned programs and applications from a recording medium on which the programs and applications are recorded, and stores the programs and applications in the built-in storage 1004.

[0041] The transmitting / receiving device 1008 is a communication circuit for performing wireless or wired communication. The transmitting / receiving device 1008 may communicate with, for example, a server device connected to a network, download the above-mentioned programs and applications from the server device, and store them in the built-in storage 1004.

[0042] The CPU 1003 is a central processing unit that copies programs and applications stored in the internal storage 1004 to the RAM 1005, and sequentially reads out instructions included in the programs and applications from the RAM 1005 and executes them.

[0043] [1-2. Functional configuration of inspection device 10] Next, the functional configuration of the inspection device 10 according to the present embodiment will be described with reference to FIG.

[0044] FIG. 3 is a block diagram showing an example of a functional configuration of the inspection device 10 according to the present embodiment.

[0045] 3, the inspection device 10 includes an acquisition unit 101, a generation unit 102, a calculation unit 103, an estimation unit 104, and a focus adjustment unit 105. Note that the focus adjustment unit 105 is not essential to the inspection device 10, and may be provided externally.

[0046] [1-2-1. Acquisition part 101] The acquisition unit 101 acquires an inspection image of a pixel region of the display panel 30 captured by the imaging device 20. The acquisition unit 101 acquires a one-dimensional luminance profile by performing image processing to compress the luminance of the acquired inspection image into a one-dimensional luminance with an axis perpendicular to the arrangement direction of a plurality of sub-pixels constituting one pixel in a plurality of pixels. Each of the plurality of pixels is composed of a plurality of sub-pixels. The acquisition unit 101 can realize the image processing function and acquisition function by having a processor execute a control program stored in a memory in a computer that realizes the function of the inspection device 10.

[0047] FIG. 4 is an example of a test image of a pixel region of the display panel 30 according to the present embodiment. In FIG. 4, an example of a test image in focus is shown as a test image 61. In the pixel region shown in the test image 61, one pixel, which is a constituent unit of a screen displayed by the display panel 30, and a plurality of sub-pixels, which are monochromatic dots of, for example, RGB, obtained by further dividing the pixel, are shown. That is, the test image 61 in FIG. 4 shows the pixel region of the display panel 30, which is composed of a plurality of pixels in which the sub-pixels, which are monochromatic dots of, for example, RGB, function as one pixel. In the example shown in FIG. 4, a pixel composed of a vertically elongated rectangular sub-pixel, in which the width of the B (Blue) sub-pixel is wider than the widths of the R (Red) and G (Green) sub-pixels, is arranged in a matrix. That is, in the pixel region shown in the test image 61 shown in FIG. 4, a plurality of pixels are formed in a periodic structure. In the following, the direction in which the sub-pixels constituting one pixel are aligned, i.e., the direction in which the sub-pixels constituting one pixel are aligned in a plurality of pixels each composed of a plurality of sub-pixels, is referred to as the X-axis, and the direction perpendicular to the direction in which the sub-pixels constituting one pixel are aligned is referred to as the Y-axis.

[0048] FIG. 5 is a diagram showing a one-dimensional luminance profile 62 when the luminance of the inspection image 61 shown in FIG. 4 is compressed on the X axis. FIG. 6 is a diagram showing a one-dimensional luminance profile 63 when the luminance of the inspection image 61 shown in FIG. 4 is compressed on the Y axis. In FIG. 5 and FIG. 6, the vertical axis is luminance, more precisely, the sum of luminance. In FIG. 5, the horizontal axis is the X coordinate, i.e., the pixel position on the X axis, and in FIG. 6, the horizontal axis is the Y coordinate, i.e., the pixel position on the Y axis. Compression on the X axis means that, at each pixel position on the X axis, the sum of luminance of all pixels along the Y axis of the pixel position is calculated. Similarly, compression on the Y axis means that, at each pixel position on the Y axis, the sum of luminance of all pixels along the X axis of the pixel position is calculated.

[0049] In this embodiment, the acquiring unit 101 acquires, for example, a test image 61 shown in Fig. 4 as a test image of a pixel region of the display panel 30 captured by the imaging device 20. The acquiring unit 101 also performs image processing to compress the luminance of the acquired test image 61 into one-dimensional luminance on the Y axis, thereby acquiring, for example, a one-dimensional luminance profile 63 shown in Fig. 6.

[0050] Here, the reason why the luminance of the inspection image 61 is compressed along the Y axis instead of along the X axis will be explained using a one-dimensional luminance profile 62 shown in FIG. 5 and a one-dimensional luminance profile 63 shown in FIG.

[0051] In the one-dimensional luminance profile 62 shown in FIG. 5, the luminance is compressed in the X-axis, that is, in the arrangement direction of the sub-pixels constituting one pixel. Although the arrangement in one pixel unit is periodic, the arrangement of the sub-pixels in one pixel unit (that is, the arrangement of the sub-pixels along the X-axis) is not symmetrical, so the shape of the one-dimensional luminance profile 62 shown in FIG. 5 is complex. On the other hand, the one-dimensional luminance profile 63 shown in FIG. 6 compresses the luminance in the Y-axis, that is, in the direction perpendicular to the arrangement direction of the sub-pixels constituting one pixel. Since the arrangement in one pixel unit along the Y-axis is the same pattern, the shape of the one-dimensional luminance profile 63 shown in FIG. 6 is simple. That is, in order to know what kind of shape (waveform) is formed by the composition of the Fourier transform processing (fast Fourier transform processing) in the generating unit 102 described later, it is better for the shape of the one-dimensional luminance profile to be simple. Note that when the cell pitch is equal, that is, when the widths of the R, G, and B sub-pixels are equal, the luminance may be compressed in the X-axis or the Y-axis.

[0052] In this manner, the acquiring unit 101 can acquire a one-dimensional luminance profile from the test image of the pixel region of the display panel 30 captured by the imaging device 20.

[0053] For comparison, a case where an out-of-focus test image is acquired will also be described.

[0054] Fig. 7A is another example of a test image of a pixel region of display panel 30 according to the present embodiment. Fig. 7B is a diagram showing a one-dimensional luminance profile 66 obtained by compressing the luminance of test image 65 shown in Fig. 7A along the Y axis.

[0055] That is, the acquiring unit 101 acquires, for example, an out-of-focus test image 65 shown in Fig. 7A as a test image of a pixel region of the display panel 30 captured by the imaging device 20. Then, the acquiring unit 101 performs image processing to compress the luminance of the acquired test image 65 into one-dimensional luminance on the Y axis, thereby acquiring, for example, a one-dimensional luminance profile 66 shown in Fig. 7B. It can be seen that the shape of the one-dimensional luminance profile 66 shown in Fig. 7B is different from the shape of the one-dimensional luminance profile 63 shown in Fig. 6.

[0056] [1-2-2. Generation unit 102] The generating unit 102 generates a frequency spectrum intensity profile by performing Fourier transform processing on the one-dimensional luminance profile. The generating unit 102 can realize the Fourier transform processing and generation function by causing a processor to execute a control program stored in a memory in a computer that realizes the functions of the inspection device 10.

[0057] In the following, a case where fast Fourier transform processing is used will be described as an example, but the present invention is not limited to this, and any algorithm may be used as long as it is a Fourier transform processing.

[0058] Furthermore, the generation unit 102 is not limited to performing a single fast Fourier transform on the one-dimensional luminance profile acquired by the acquisition unit 101, but may perform two fast Fourier transforms on the one-dimensional luminance profile acquired by the acquisition unit 101. More specifically, the generation unit 102 may perform two fast Fourier transforms on the one-dimensional luminance profile acquired by the acquisition unit 101 to generate a frequency spectrum intensity profile. Here, the generation unit 102 may perform a further multiple fast Fourier transforms to generate a frequency spectrum intensity profile.

[0059] Fig. 8 is a diagram for explaining an example of a one-dimensional luminance profile that has been subjected to a fast Fourier transform process by the generating unit 102 according to the present embodiment. Fig. 8(a) shows the one-dimensional luminance profile 63 of Fig. 6, and Fig. 8(b) shows a frequency spectrum intensity profile 63a in the case where a fast Fourier transform process is performed once on the one-dimensional luminance profile 63 of Fig. 8(a). Fig. 9 is a diagram showing a frequency spectrum intensity profile 63b in the case where a fast Fourier transform process is performed twice on the one-dimensional luminance profile 63 of Fig. 6.

[0060] In this embodiment, the generating unit 102 performs fast Fourier transform processing once or twice on the one-dimensional luminance profile 63 shown in FIG. 8(a), for example.

[0061] For example, by performing a fast Fourier transform once while regarding the shape of the one-dimensional intensity profile 63 shown in (a) of Fig. 8 as a waveform, a frequency spectrum intensity profile 63a shown in (b) of Fig. 8 is generated. Also, by performing a fast Fourier transform twice while regarding the shape of the one-dimensional intensity profile 63 shown in (a) of Fig. 8 as a waveform, a frequency spectrum intensity profile 63b shown in Fig. 9 is generated.

[0062] Here, a case where the fast Fourier transform process is performed once or twice on the one-dimensional intensity profile 66 of the out-of-focus test image 65 will also be described.

[0063] Fig. 10 is a diagram for explaining another example of a one-dimensional luminance profile subjected to a fast Fourier transform process by the generating unit 102 according to the present embodiment. Fig. 10(a) shows the one-dimensional luminance profile 66 of Fig. 7B, and Fig. 10(b) shows a frequency spectrum intensity profile 66a in the case where a fast Fourier transform process is performed once on the one-dimensional luminance profile 66 of Fig. 10(a). Fig. 11 is a diagram showing a frequency spectrum intensity profile 66b in the case where a fast Fourier transform process is performed twice on the one-dimensional luminance profile 66 of Fig. 7B.

[0064] For example, a frequency spectrum intensity profile 66a shown in Fig. 10(b) is generated by performing a fast Fourier transform once while regarding the shape of a one-dimensional intensity profile 66 shown in Fig. 10(a) as a waveform. Also, a frequency spectrum intensity profile 66b shown in Fig. 11 is generated by performing a fast Fourier transform twice while regarding the shape of a one-dimensional intensity profile 63 shown in Fig. 8(a) as a waveform.

[0065] In comparison with the frequency spectrum intensity profile 63a shown in FIG. 8(b), it is clear that there are no waves in the power spectrum of high frequency components in the frequency spectrum intensity profile 66a shown in FIG. 10(b).

[0066] In this way, the generating unit 102 can generate a frequency spectrum intensity profile by treating the shape of the one-dimensional luminance profile of the test image as a waveform and performing fast Fourier transform processing. From the generated frequency spectrum intensity profile, the frequency components and their amplitudes contained in the waveform of the one-dimensional luminance profile of the test image can be determined.

[0067] [1-2-3. Calculation unit 103] The calculation unit 103 calculates the shooting magnification of the image capturing device 20 from one or more peak positions included in the frequency spectrum intensity profile based on the fact that a plurality of pixels are formed in a periodic structure in the pixel region of the display panel 30. More specifically, the calculation unit 103 calculates the shooting magnification of the image capturing device 20 from the peak position of the fundamental frequency by estimating that the peak position of the fundamental frequency among the one or more peak positions corresponds to the structure of one pixel unit of the pixel region shown in the inspection image. Note that the calculation function of the calculation unit 103 can be realized, for example, by a processor executing a control program stored in a memory in a computer that realizes the function of the inspection device 10.

[0068] In this embodiment, the calculation unit 103 calculates the imaging magnification of the imaging device 20 from the frequency and magnitude of the power spectrum of the waves included in the frequency spectrum intensity profile generated by the generation unit 102 and the structural properties of the pixel area of ​​the display panel 30. The imaging magnification is the ratio between the size of the image reflected on the imaging surface and the actual size of the subject. That is, in this embodiment, the imaging magnification is the ratio between the size of the pixels in the pixel area reflected in the test image captured by the imaging device 20 and the size of the pixels in the actual pixel area of ​​the display panel 30.

[0069] More specifically, since the wave indicated by the dotted circle a has the lowest frequency component among one or more waves included in the frequency spectrum intensity profile 63a in (b) of FIG. 8, for example, the calculation unit 103 estimates the frequency of the wave indicated by the dotted circle a to be the fundamental frequency.

[0070] Here, as shown in (a) of FIG. 8, the one-dimensional luminance profile 63 is composed of 1000 data (1000 pixels). As shown in (b) of FIG. 8, the fundamental frequency wave of the frequency spectrum intensity profile 63a, that is, the wave indicated by the dotted circle a, has a numerical value of 7 at the peak position. The calculation unit 103 can calculate 1000 / 7=143, so it is estimated that the wave indicated by the dotted circle a corresponds to the wave of 143 data periods in the one-dimensional luminance profile 63 shown in (a) of FIG. 8. In addition, a pixel region having a periodic structure in which eight pixels are arranged is shown in the Y-axis direction of the inspection image 61 shown in FIG. 4, and eight waves indicated by the dotted circle a are shown in the one-dimensional luminance profile 63 shown in (a) of FIG. From these, it can be seen that the wave indicated by the dotted circle a corresponds to one pixel unit. Therefore, it can be seen that the fundamental frequency wave indicated by the dotted circle a in the frequency spectrum intensity profile 63a corresponds to one pixel unit.

[0071] Similarly, for example, it is estimated that the wave indicated by the dotted circle b in the frequency spectrum intensity profile 63a in (b) of FIG. 8 is the wave indicated by the dotted circle b in the one-dimensional luminance profile 63 shown in (a) of FIG. 8. More specifically, as shown in (a) of FIG. 8, the one-dimensional luminance profile 63 is composed of 1000 data (data of 100 pixels). As shown in (b) of FIG. 8, the numerical value of the peak position of the wave indicated by the dotted circle b in the frequency spectrum intensity profile 63a is 14. Since the calculation unit 103 can calculate 1000 / 14=71, it is estimated that the wave of the 71 data period in the one-dimensional luminance profile 63 shown in (a) of FIG. 8 is the wave indicated by the dotted circle b. Note that the wave indicated by the dotted circle b in (a) of FIG. 8 corresponds to the two-humped wave included in the wave indicated by the dotted circle a. Moreover, in the frequency spectrum intensity profile 63a in FIG. 8(b), the frequency of the peak position of the wave indicated by the dotted circle b is twice the fundamental frequency.

[0072] In the same manner, the calculation unit 103 estimates that the wave indicated by the dotted circle c in the frequency spectrum intensity profile 63a in (b) of Fig. 8 is the wave indicated by the dotted circle c in the one-dimensional brightness profile 63 shown in (a) of Fig. 8. The wave indicated by the dotted circle c in (a) of Fig. 8 corresponds to three thorny waves included in the wave indicated by the dotted circle c. The frequency of the peak position of the wave indicated by the dotted circle c in the frequency spectrum intensity profile 63a in (b) of Fig. 8 is three times the fundamental frequency.

[0073] In this way, the calculation unit 103 can calculate the fundamental frequency from the peak positions of one or more waves included in the frequency spectrum intensity profile, and can calculate the data period in units of one pixel from the structural properties that indicate the periodic structure of the pixels in the pixel region of the display panel 30. As a result, the calculation unit 103 can calculate the size of the pixels in the pixel region shown in the test image captured by the imaging device 20, and can therefore calculate the imaging magnification using the size of the pixels in the pixel region of the actual display panel 30.

[0074] In this embodiment, the calculation unit 103 may calculate, as the imaging magnification, the value of the peak position of the fundamental frequency obtained by performing fast Fourier transform processing on the one-dimensional luminance profile once or twice.

[0075] More specifically, the calculation unit 103 may calculate, as the imaging magnification, the value 7 of the fundamental frequency of the frequency spectrum intensity profile 63a in Fig. 8(b) obtained by performing a fast Fourier transform on the one-dimensional luminance profile once. The calculation unit 103 may also calculate, as the imaging magnification, the value of the fundamental frequency of the frequency spectrum intensity profile 63b in Fig. 9 obtained by performing a fast Fourier transform on the one-dimensional luminance profile twice. In the frequency spectrum intensity profile 63b in Fig. 9, the wave indicated by the dotted circle d is the wave having the lowest frequency component, and the frequency of the peak position of the wave indicated by the dotted circle d is the fundamental frequency.

[0076] The frequency spectrum intensity profile 63a of the in-focus inspection image 61 has been described above, but the same can be said about the frequency spectrum intensity profile 66a of the out-of-focus inspection image 65, so will be described below.

[0077] The calculation unit 103 can estimate that the frequency of the wave indicated by the dotted circle a is the fundamental frequency, since, for example, among the one or more waves included in the frequency spectrum intensity profile 66a in FIG. 10(b), the wave indicated by the dotted circle a is the wave having the lowest frequency component.

[0078] More specifically, as shown in FIG. 10(a), the one-dimensional luminance profile 66 is composed of 1000 data (100 pixel data). As shown in FIG. 10(b), the value of the peak position of the fundamental frequency wave indicated by the dotted circle a in the frequency spectrum intensity profile 66a is 7. The calculation unit 103 can calculate 1000 / 7=143, so it can be estimated that the wave of the 143 data period in the one-dimensional luminance profile 66 shown in FIG. 10(a) is the wave indicated by the dotted circle a. It can be seen that the wave indicated by the dotted circle a in FIG. 10(a) is a wave corresponding to one pixel unit. This shows that the fundamental frequency wave indicated by the dotted circle a in the frequency spectrum intensity profile 66a is a wave corresponding to one pixel unit.

[0079] Similarly, for example, the wave indicated by the dotted circle b in the frequency spectrum intensity profile 66a in (b) of FIG. 10 is estimated to be the wave indicated by the dotted circle b in the one-dimensional luminance profile 66 shown in (a) of FIG. 10. More specifically, as shown in (a) of FIG. 10, the one-dimensional luminance profile 66 is composed of 1000 data (data of 100 pixels). As shown in (b) of FIG. 10, the numerical value of the peak position of the wave indicated by the dotted circle b in the frequency spectrum intensity profile 66a is 14. Since the calculation unit 103 can calculate 1000 / 14=71, it can be estimated that the wave of the 71 data period in the one-dimensional luminance profile 66 shown in (a) of FIG. 10 corresponds to the wave indicated by the dotted circle b. Note that the wave indicated by the dotted circle b in (a) of FIG. 10 corresponds to the two-humped wave included in the wave indicated by the dotted circle a. Moreover, in the frequency spectrum intensity profile 66a in FIG. 10(b), the frequency of the peak position of the wave indicated by the dotted circle b is twice the fundamental frequency.

[0080] In this way, with regard to the fundamental frequency, the frequency spectrum intensity profile 66a of the out-of-focus inspection image 65 can be handled in the same manner as the frequency spectrum intensity profile 63a of the in-focus inspection image 61. In other words, the calculation unit 103 can calculate the shooting magnification from the frequency spectrum intensity profile 66a of the out-of-focus inspection image 65.

[0081] Similarly, the calculation unit 103 may calculate, as the imaging magnification, the value 7 of the fundamental frequency of the frequency spectrum intensity profile 66a in Fig. 10(b) obtained by performing a fast Fourier transform on the one-dimensional luminance profile once. The calculation unit 103 may calculate, as the imaging magnification, the value of the fundamental frequency of the frequency spectrum intensity profile 66b in Fig. 11 obtained by performing a fast Fourier transform on the one-dimensional luminance profile twice. In the frequency spectrum intensity profile 66b in Fig. 11, the wave indicated by the dotted circle d is the wave with the lowest frequency component, so that the frequency of the peak position of the wave indicated by the dotted circle d is the fundamental frequency.

[0082] [1-2-4. Estimation section 104] The estimation unit 104 estimates a current focus position, which is the focus position of the photographing device 20 in the inspection image, from the magnification information indicating the relationship between the focus position and the photographing magnification in the photographing device 20 and the photographing magnification calculated by the calculation unit 103. Note that the estimation unit 104 can realize the estimation function by, for example, having a processor execute a control program stored in a memory in a computer that realizes the function of the inspection device 10.

[0083] In an optical system such as a full group extension type that the photographing device 20 according to this embodiment has, the focal position and the photographing magnification are one to one. This magnification information showing the relationship between the focal position and the photographing magnification in the photographing device 20 can be obtained in advance. Also, even if the photographing device 20 according to this embodiment has an optical system such as an inner focus, there is a strong correlation between the focal position and the photographing magnification in the optical system such as the inner focus. Therefore, the magnification information showing the relationship between the focal position and the photographing magnification in the photographing device 20 can be obtained in advance.

[0084] Therefore, the estimation unit 104 can estimate the current focus position of the photographing device 20 in the test image from the photographing magnification calculated by the calculation unit 103 by referring to the magnification information.

[0085] As described above, in the present embodiment, the shooting magnification may be the fundamental frequency value obtained by fast Fourier transform processing of the one-dimensional luminance profile of the image of the pixel region of the display panel 30 shot by the shooting device 20. In this case, the magnification information of the shooting device 20 may be information indicating the relationship between the fundamental frequency value (shooting magnification) obtained by fast Fourier transform processing of the one-dimensional luminance profile at each of the multiple focus positions of the shooting device 20 and the multiple focus positions.

[0086] Fig. 12 is a diagram showing an example of magnification information when the value of the fundamental frequency according to the present embodiment is used as the shooting magnification. The FFT values ​​shown in Fig. 12 are fundamental frequency values ​​obtained by performing fast Fourier transform processing twice on a one-dimensional luminance profile.

[0087] In FIG. 12, the relationship between the FFT value and the focus position obtained from the image of the pixel region of the display panel 30 captured at a plurality of focus positions of the imaging device 20 is shown as magnification information 70. The magnification information 70 shown in FIG. 12 was created as follows. First, the focus position of the imaging device 20 was shifted in increments of 10 μm in the range of −500 μm to 500 μm to capture 100 focus-shifted images of the pixel region of the display panel 30. Next, the 100 focus-shifted images obtained were compressed on the Y axis into a one-dimensional luminance profile, and a fast Fourier transform process was performed twice to calculate the FFT value, which is the value of the fundamental frequency for the 100 focus-shifted images. Then, the relationship between the 100 different focus positions and the FFT value was linearly approximated to obtain an approximate straight line. In this manner, the magnification information 70 shown in FIG. 12 was created.

[0088] The estimation unit 104 can estimate the current focus position of the imaging device 20 from the FFT value, which is the imaging magnification calculated by the calculation unit 103, based on the magnification information 70 shown in Fig. 12. Furthermore, by using the magnification information 70 shown in Fig. 12, it is possible to calculate the distance from the current focus position to the focus position of 0 μm, which is the in-focus position.

[0089] In the example shown in Fig. 12, the value of the fundamental frequency obtained by performing the fast Fourier transform process twice on the one-dimensional luminance profile is described as the FFT value, but this is not limited thereto. The value of the fundamental frequency obtained by performing the fast Fourier transform process once on the one-dimensional luminance profile may be the FFT value. Even in this case, it is possible to create magnification information similar to the magnification information 70 shown in Fig. 12, so that the estimation unit 104 can estimate the current focus position of the imaging device 20 from the FFT value, which is the imaging magnification calculated by the calculation unit 103, based on the magnification information created in a similar manner.

[0090] [1-2-5. Focus adjustment unit 105] The focus adjustment unit 105 calculates the amount of movement of the photographing device 20 required for focusing from the current focus position estimated by the estimation unit 104 and the magnification information, and adjusts the position of the photographing device 20 using the calculated amount of movement. Note that the focus adjustment unit 105 can realize the above adjustment function by having a processor execute a control program stored in a memory in a computer that realizes the function of the inspection device 10.

[0091] In the present embodiment, as described above, the value of the fundamental frequency obtained by performing fast Fourier transform processing on the one-dimensional luminance profile of the image of the pixel region of the display panel 30 photographed by the photographing device 20 may be used as the photographing magnification. In this case, the magnification information may be information indicating the relationship between the fundamental frequency value (FFT value) obtained by performing fast Fourier transform processing on the one-dimensional luminance profile at each of the multiple focus positions of the photographing device 20 and the multiple focus positions. An example of this magnification information is the magnification information 70 in FIG. 12 described above. The focus adjustment unit 105 can calculate the distance from the current focus position to the focus position of 0 μm, which is the in-focus position, by using the magnification information as shown in FIG. 12 or the approximation line included in the magnification information as shown in FIG. 12. Therefore, the focus adjustment unit 105 can calculate the amount of movement of the photographing device 20 required for focusing from the magnification information and the current focus position estimated by the estimation unit 104 as shown in FIG. 12, and can adjust the position of the photographing device 20 using the calculated amount of movement.

[0092] In this manner, the inspection device 10 can adjust the focus of the photographing device 20, and therefore can obtain a focused, high-quality inspection image.

[0093] [1-3. Operation of the inspection device 10] An example of the operation of the inspection device 10 configured as above will be described below.

[0094] FIG. 13 is a flowchart showing the operation of the inspection device 10 according to the present embodiment.

[0095] First, the inspection device 10 acquires a test image of a pixel region of the display panel 30 (S11). More specifically, the acquisition unit 101 acquires the test image of the pixel region of the display panel 30 captured by the imaging device 20. For example, the acquisition unit 101 acquires a test image of the pixel region of the display panel 30, such as the test image 61 shown in Fig. 4 or the test image 65 shown in Fig. 7A.

[0096] Next, the inspection device 10 performs image processing on the inspection image acquired in step S11 to compress the one-dimensional luminance along the Y axis, thereby acquiring a one-dimensional luminance profile (S12). More specifically, the acquisition unit 101 acquires a one-dimensional luminance profile obtained by performing image processing on the luminance of the acquired inspection image to compress the luminance into one-dimensional luminance with the axis (Y axis) being the vertical direction of the arrangement direction of a plurality of sub-pixels constituting one pixel in a plurality of pixels each composed of a plurality of sub-pixels. For example, the acquisition unit 101 acquires a one-dimensional luminance profile in which the luminance of the inspection image is compressed along the Y axis, such as the one-dimensional luminance profile 63 shown in FIG. 6 or the one-dimensional luminance profile 66 shown in FIG. 7B.

[0097] Next, the inspection device 10 generates a frequency spectrum intensity profile by performing a fast Fourier transform process on the one-dimensional luminance profile acquired in step S12 (S13). More specifically, the generation unit 102 generates a frequency spectrum intensity profile by performing a fast Fourier transform process on the one-dimensional luminance profile acquired in step S12 once or twice.

[0098] For example, the calculation unit 103 performs a fast Fourier transform on the one-dimensional luminance profile once to generate a frequency spectrum intensity profile such as the frequency spectrum intensity profile 63a shown in (b) of Fig. 8 or the frequency spectrum intensity profile 66a shown in (b) of Fig. 10. Note that the calculation unit 103 may perform a fast Fourier transform on the one-dimensional luminance profile twice to generate a frequency spectrum intensity profile such as the frequency spectrum intensity profile 63b shown in Fig. 9 or the frequency spectrum intensity profile 66b shown in Fig. 11.

[0099] Next, the inspection device 10 calculates the shooting magnification of the imaging device 20 from the peak positions of one or more waves included in the frequency spectrum intensity profile generated in step S13 (S14). More specifically, the calculation unit 103 calculates the shooting magnification of the imaging device 20 from the frequency and power spectrum magnitude of the waves included in the frequency spectrum intensity profile generated by the generation unit 102 and the structural properties of the pixel area of ​​the display panel 30. The calculation unit 103 estimates that the peak position of the fundamental frequency among the one or more peak positions corresponds to the structure of one pixel unit of the pixel area shown in the inspection image, and calculates the shooting magnification of the imaging device 20 from the peak position of the fundamental frequency. For example, the calculation unit 103 calculates the fundamental frequency from the peak positions of one or more waves included in the frequency spectrum intensity profile 63a in (b) of FIG. 8 or the frequency spectrum intensity profile 66a in (b) of FIG. 10, and calculates the shooting magnification using the calculated fundamental frequency.

[0100] Next, the inspection device 10 estimates the current focus position of the imaging device 20 that captured the inspection image from the magnification information of the imaging device 20 (S15). More specifically, the estimation unit 104 estimates the current focus position, which is the focus position of the imaging device 20 in the inspection image, from the magnification information indicating the relationship between the focus position and the imaging magnification in the imaging device 20 and the calculated imaging magnification. The imaging magnification may be a value of a fundamental frequency obtained by performing a fast Fourier transform process once or twice on a one-dimensional luminance profile of an image of a pixel region of the display panel 30 that has been captured. In this case, the current focus position can be estimated from the calculated imaging magnification by using the information indicating the relationship between the value of the fundamental frequency (imaging magnification) obtained by performing a fast Fourier transform process once or twice and a plurality of focus positions as the magnification information of the imaging device 20.

[0101] [1-4. Effects, etc.] The inspection device 10 etc. according to the present embodiment performs image processing to compress the luminance of the test image of the pixel region of the display panel 30 captured by the image capture device 20 into one-dimensional luminance with the axis perpendicular to the arrangement direction of the sub-pixels constituting one pixel in the pixels each composed of sub-pixels. A frequency spectrum intensity profile is generated by performing Fourier transform processing on the one-dimensional luminance profile acquired by performing such image processing. This Fourier transform is performed at least once, but may be performed twice. Furthermore, the inspection device 10 etc. according to the present embodiment calculates the imaging magnification of the image capture device 20 from one or more peak positions included in the frequency spectrum intensity profile, based on the fact that the pixel region has a periodic structure of multiple pixels. Then, the current focus position of the image capture device 20 in the test image is estimated from the calculated imaging magnification and magnification information indicating the relationship between the focus position and the imaging magnification in the image capture device 20.

[0102] In this way, the inspection device 10 etc. according to the present embodiment performs one-dimensional luminance compression and Fourier transform processing on the inspection image captured by the imaging device 20. Then, using the frequency spectrum intensity profile obtained by the Fourier transform processing, the current focus position of the imaging device 20 in the inspection image is estimated. There is a strong correlation between the focus position and the imaging magnification in the optical system such as a lens of the imaging device 20, and also, by utilizing the property that a periodic structure is formed in the pixel region of the display panel 30, the current focus position is estimated from the frequency spectrum intensity profile.

[0103] In other words, the inspection device 10 etc. according to this embodiment can estimate the current focus position of the photographing device 20 in the inspection image only by calculation processing without requiring dedicated hardware. Also, due to the performance of recent computers equipped with processors etc., the inspection device 10 etc. according to this embodiment can quickly perform one-dimensional luminance compression and Fourier transform processing of the inspection image photographed by the photographing device 20.

[0104] Therefore, the inspection device 10 according to the present embodiment and the like can perform the process for autofocusing at high speed without requiring dedicated hardware.

[0105] Here, the inspection device 10 according to the present embodiment estimates that the peak position of the fundamental frequency among one or more peak positions included in the frequency spectrum intensity profile is the peak position corresponding to the structure of one pixel unit in the pixel area shown in the inspection image, and calculates the imaging magnification of the imaging device 20 from the estimated peak position of the fundamental frequency.

[0106] As a result, even if the test image captured by the imaging device 20 is out of focus, the current focus position can be estimated from the frequency spectrum intensity profile, and the imaging magnification can be calculated.

[0107] Fig. 14 is a diagram showing a frequency spectrum intensity distribution at the focus position of the test image of the pixel region of the display panel 30 according to the present embodiment. Fig. 14(a) shows an example of an out-of-focus position with a focus position of -3 (μm), Fig. 14(b) shows an example of an in-focus position with a focus position of 0 (μm), and Fig. 14(c) shows an example of an out-of-focus position with a focus position of +3 (μm). The positions of the imaging device 20 in Fig. 14(a) to (c) are, for example, the positions of the imaging device 20 in Fig. 1(a) to (c).

[0108] As can be seen by comparing (a) to (c) of FIG. 14, when the image is in focus, there is a waveform of a high spatial frequency component included in the dotted circle indicated by h. In addition, the waveforms excluding the high spatial frequency components are also different in the frequency spectrum intensity distributions shown in (a) to (c) of FIG. 14. That is, even in the case of an inspection image obtained by photographing the pixel region of the same display panel 30, the frequency spectrum intensity distribution obtained by the Fourier transform process differs depending on the focus position, so that the degree of out-of-focus can be seen. Therefore, in this embodiment, the fact that the frequency spectrum intensity distribution obtained by the Fourier transform process differs, that there is a strong correlation between the focus position and the photographing magnification in the optical system of the photographing device 20, and that a periodic structure is formed in the pixel region of the display panel 30 is utilized. That is, the current focus position can be estimated from the peak position of the fundamental frequency included in the wavenumber spectrum intensity profile by utilizing the structural properties of the photographing device 20 and the properties of the optical system.

[0109] Furthermore, the inspection device 10 etc. according to the present embodiment may generate a frequency spectrum intensity profile by performing two Fourier transforms on a one-dimensional luminance profile obtained by one-dimensionally compressing the luminance of the inspection image captured by the imaging device 20. This makes it easy to estimate the fundamental frequency from the frequency spectrum intensity profile.

[0110] Moreover, the magnification information does not have to be obtained from the optical properties of the image capturing device 20. More specifically, the magnification information may be information indicating the relationship between the multiple focus positions and a fundamental frequency value obtained by Fourier transform processing of a one-dimensional luminance profile of an image of a pixel region of the display panel 30 captured at each of multiple focus positions of the image capturing device 20. Here, the fundamental frequency value is defined as the image capturing magnification.

[0111] This makes it possible to directly estimate the current focus position using the magnification information from the fundamental frequency of the frequency spectrum intensity profile generated by performing Fourier transform processing once or twice, thereby enabling the current focus position to be estimated quickly.

[0112] In addition, the inspection device 10 etc. according to this embodiment may further calculate the amount of movement of the photographing device 20 required for focusing from the estimated current focus position and magnification information, and adjust the position of the photographing device 20 using the calculated amount of movement.

[0113] In this way, the current focus position and the amount of movement of the photographing device 20 required for focusing can be obtained simply by calculation using the magnification information and the test image, so that high-speed autofocus processing can be performed without the need for dedicated hardware.

[0114] In other words, the inspection device 10 according to the present embodiment and the like can perform autofocusing with high focusing accuracy and at high speed without requiring dedicated hardware.

[0115] In other words, the inspection device 10 etc. according to this embodiment does not require dedicated AF hardware, and can perform high-speed processing for autofocus (AF) using the inspection image itself captured by the imaging device 20. This makes it possible to realize high-speed AF processing that has the advantages of high focusing accuracy and no need for calibration, without requiring dedicated AF hardware.

[0116] Although the inspection device and inspection method according to the present disclosure have been described above based on the embodiments and modifications, the present disclosure is not limited to these embodiments and modifications. As long as they do not deviate from the gist of the present disclosure, various modifications conceived by a person skilled in the art to the embodiments and modifications, and other forms constructed by combining some of the components in the embodiments and modifications are also included within the scope of the present disclosure.

[0117] The following forms may also be included within the scope of one or more aspects of the present disclosure.

[0118] (1) Some of the components constituting the above-mentioned inspection device may be a computer system composed of a microprocessor, ROM, RAM, GPU, hard disk unit, display unit, keyboard, mouse, etc. A computer program is stored in the RAM or hard disk unit. The microprocessor achieves its function by operating according to the computer program. Here, the computer program is composed of a combination of multiple instruction codes that indicate commands for a computer to achieve a predetermined function.

[0119] (2) Some of the components constituting the above-mentioned inspection device may be composed of one system LSI (Large Scale Integration). The system LSI is an ultra-multifunctional LSI manufactured by integrating multiple components on one chip, and specifically, is a computer system including a microprocessor, ROM, RAM, GPU, etc. A computer program is stored in the RAM. The system LSI achieves its functions by the microprocessor or the GPU operating in accordance with the computer program.

[0120] (3) Some of the components constituting the above-mentioned inspection device may be composed of an IC card or a standalone module that can be attached to each device. The IC card or the module is a computer system composed of a microprocessor, ROM, RAM, GPU, etc. The IC card or the module may include the above-mentioned ultra-multifunction LSI. The microprocessor or the GPU operates according to a computer program, causing the IC card or the module to achieve its functions. The IC card or the module may be tamper-resistant.

[0121] (4) Furthermore, some of the components constituting the above-mentioned inspection device may be the computer program or the digital signal recorded on a computer-readable recording medium, such as a flexible disk, a hard disk, a CD-ROM, an MO, a DVD, a DVD-ROM, a DVD-RAM, a BD (Blu-ray (registered trademark) Disc), a semiconductor memory, etc. Also, the components may be the digital signals recorded on these recording media.

[0122] In addition, some of the components constituting the above-mentioned determination device may transmit the computer program or the digital signal via a telecommunications line, a wireless or wired communication line, a network such as the Internet, data broadcasting, etc.

[0123] (5) The present disclosure may be embodied as any of the methods described above, a computer program for implementing these methods by a computer, or a digital signal comprising the computer program.

[0124] (6) The present disclosure may also be directed to a computer system having a microprocessor, a GPU, and a memory, the memory storing the above-mentioned computer program, and the microprocessor or the GPU operating in accordance with the computer program.

[0125] (7) The program or the digital signal may also be implemented by another independent computer system by recording it on the recording medium and transferring it, or by transferring the program or the digital signal via the network, etc.

[0126] (8) In addition, some of the components constituting the above-mentioned inspection device may be performed on a cloud or server device.

[0127] (9) The above-described embodiments and modifications may be combined with each other. [Industrial Applicability]

[0128] The present disclosure can be used for an inspection method, inspection device, program, etc. that can perform autofocusing at low cost, with high focusing accuracy, and at high speed when capturing an inspection image in an inspection process that uses an inspection image of a pixel region of a display panel. [Explanation of symbols]

[0129] 10 Inspection equipment 20 Imaging Equipment 21 Stage 22 Stage drive unit 30 Display Panel 61, 65 Inspection images 62, 63, 66 One-dimensional brightness profile 63a, 63b, 66a, 66b Frequency spectrum intensity profile 101 Acquisition Department 102 Generation part 103 Calculation section 104 Estimation part 105 Focus adjustment section 1000 Computers 1001 Input Device 1002 Output device 1003 CPU 1004 Internal Storage 1005 RAM 1006 GPU 1007 Reading device 1008 Transmitting and receiving device 1009 Bus

Claims

1. A method for inspecting a display panel performed by a computer, comprising the steps of: an acquiring step of acquiring a one-dimensional luminance profile by performing image processing for compressing the luminance of the test image of the pixel region of the display panel captured by the image capturing device into a one-dimensional luminance with an axis perpendicular to an arrangement direction of a plurality of sub-pixels constituting one pixel in a plurality of pixels each composed of a plurality of sub-pixels; a generating step of generating a frequency spectrum intensity profile by performing a Fourier transform process on the one-dimensional luminance profile; a calculation step of calculating an imaging magnification of the imaging device from one or more peak positions included in the frequency spectrum intensity profile based on the fact that the plurality of pixels are formed in a periodic structure in the pixel region; and estimating a current focus position, which is the focus position of the photographing device in the test image, from magnification information indicating a relationship between a focus position and a photographing magnification in the photographing device and the calculated photographing magnification. Testing method.

2. In the calculation step, calculating an imaging magnification of the imaging device from the peak position of the fundamental frequency by estimating that a peak position of a fundamental frequency among the one or more peak positions corresponds to a one-pixel unit structure of the pixel area shown in the test image; The inspection method according to claim 1 .

3. In the generating step, a frequency spectrum intensity profile is generated by performing a Fourier transform process twice on the one-dimensional luminance profile. The inspection method according to claim 2.

4. The magnification information is information indicating a relationship between the plurality of focus positions of the image capturing device and a fundamental frequency value obtained by Fourier transform processing of a one-dimensional luminance profile of an image of a pixel region of a display panel captured by the image capturing device at each of the plurality of focus positions of the image capturing device, the fundamental frequency value being taken as an image capturing magnification. The inspection method according to claim 2.

5. moreover, a step of calculating a movement amount of the photographing device required for focusing based on the estimated current focus position and the magnification information, and adjusting a position of the photographing device using the movement amount; The inspection method according to any one of claims 1 to 4.

6. A display panel inspection apparatus, comprising: an acquisition unit that acquires a one-dimensional luminance profile by performing image processing to compress the luminance of a test image of a pixel region of the display panel captured by an image capture device into a one-dimensional luminance whose axis is a vertical direction to an arrangement direction of a plurality of sub-pixels that constitute one pixel in a plurality of pixels, each of which is composed of a plurality of sub-pixels; a generation unit that generates a frequency spectrum intensity profile by performing a Fourier transform process on the one-dimensional luminance profile; a calculation unit that calculates an imaging magnification of the imaging device from one or more peak positions included in the frequency spectrum intensity profile, based on the fact that the plurality of pixels are formed in a periodic structure in the pixel region; an estimation unit that estimates a current focus position, which is a focus position of the photographing device in the test image, from magnification information indicating a relationship between a focus position and a photographing magnification in the photographing device and the calculated photographing magnification, Inspection equipment.

7. A program for causing a computer to execute a display panel inspection method, an acquiring step of acquiring a one-dimensional luminance profile by performing image processing for compressing the luminance of the test image of the pixel region of the display panel captured by the image capturing device into a one-dimensional luminance with an axis perpendicular to an arrangement direction of a plurality of sub-pixels constituting one pixel in a plurality of pixels each composed of a plurality of sub-pixels; a generating step of generating a frequency spectrum intensity profile by performing a Fourier transform process on the one-dimensional luminance profile; a calculation step of calculating an imaging magnification of the imaging device from one or more peak positions included in the frequency spectrum intensity profile based on the fact that the plurality of pixels are formed in a periodic structure in the pixel region; and estimating a current focus position, which is the focus position of the photographing device in the test image, from magnification information indicating a relationship between a focus position and a photographing magnification in the photographing device and the calculated photographing magnification. program.

Images