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 Art

[0002] In the production process of display panels, various inspections are performed to maintain product quality, and image inspection occupies a large weight among them.

[0003] In recent years' image inspections, in addition to improving the judgment accuracy by operators, high-quality images have been demanded to improve the judgment accuracy by automatic inspection.

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

[0005] The contrast detection type AF is a method of searching for the contrast peak of an image while changing the focus position. That is, in the contrast detection type AF, dedicated hardware for AF is not required, and autofocus processing is performed using the image itself. Therefore, the contrast detection type AF has the advantage of high focus accuracy.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, while the contrast-detection type AF used in Patent Document 1 has the advantage of high focusing accuracy, it has the disadvantage of slow operation speed because it is not possible to determine whether the direction of the out-of-focus camera position is positive or negative from the in-focus position. Since cycle time is a crucial factor for inspection equipment, using contrast-detection type AF in inspection equipment is a major drawback.

[0008] In addition to contrast-detection autofocus (AF), laser autofocus (AF) is also known as an autofocus mechanism. Laser AF has the advantage of fast operation speed because it directly measures the distance to the panel surface by irradiating the panel with laser light. However, laser AF has the disadvantage of requiring dedicated AF hardware, and high-precision AF hardware is expensive. Furthermore, when using laser AF in inspection equipment, the distance between the laser detector and the display panel surface is measured, which presents problems such as the need for calibration to convert this measurement to the distance between the optical system used to adjust the focus position and the display panel surface.

[0009] This disclosure is made in view of the circumstances described above, and aims to provide an inspection method that does not require dedicated hardware and can perform processing to autofocus at high speed. [Means for solving the problem]

[0010] To achieve the above objective, an inspection method according to one embodiment of the present disclosure is a computer-based inspection method for a display panel, comprising: an acquisition step of obtaining a one-dimensional luminance profile by applying 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 with the axis perpendicular to the direction of arrangement of the multiple subpixels constituting one pixel in a plurality of pixels each composed of a plurality of subpixels; a generation step of generating a frequency spectral intensity profile by performing a Fourier transform 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 spectral intensity profile, based on the fact that the plurality of pixels in the pixel region are formed in a periodic structure; and an estimation step of estimating the current focal position, which is the focal position of the imaging device in the inspection image, from magnification information indicating the relationship between the focal position and the imaging magnification of the imaging device and the calculated imaging magnification.

[0011] In this way, the current focus position of the imaging device 20 in the inspection image can be estimated solely through computational processing, without the need for dedicated hardware. Furthermore, thanks to the performance of modern computers equipped with processors, the inspection image captured by the imaging device 20 can be compressed to one dimension in terms of brightness and then subjected to Fourier transform processing at high speed.

[0012] Therefore, according to the inspection method of this embodiment, processing for high-speed autofocus can be performed without requiring dedicated hardware.

[0013] Furthermore, in the calculation step, the imaging magnification of the imaging device may be calculated 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 a single pixel in the pixel region shown in the inspection image.

[0014] Alternatively, for example, in the generation step, a frequency spectral intensity profile may be generated by performing a Fourier transform on the one-dimensional luminance profile twice.

[0015] Furthermore, for example, the magnification information may also be information indicating the relationship between the multiple focal positions and the fundamental frequency value obtained by performing a Fourier transform on the one-dimensional luminance profile of the pixel area image of the display panel captured by the imaging device at each of the multiple focal positions of the imaging device, when this value is used as the imaging magnification.

[0016] Furthermore, for example, the process may include an adjustment step in which the amount of movement of the imaging device required for focusing is calculated from the estimated current focus position and the magnification information, and the position of the imaging device is adjusted using the amount of movement.

[0017] Furthermore, in order to achieve the above objective, an inspection apparatus according to one embodiment of the present disclosure is an inspection apparatus for a display panel, comprising: an acquisition unit that acquires a one-dimensional brightness profile by performing image processing to compress the brightness of an inspection image of a pixel region of the display panel captured by an imaging device into a one-dimensional brightness with the axis perpendicular to the direction of arrangement of the multiple subpixels constituting one pixel in a plurality of pixels each composed of a plurality of subpixels; a generation unit that generates a frequency spectral intensity profile by performing a Fourier transform on the one-dimensional brightness profile; a calculation unit that calculates the imaging magnification of the imaging device from one or more peak positions included in the frequency spectral intensity profile based on the fact that the plurality of pixels in the pixel region are formed in a periodic structure; and an estimation unit that estimates the current focal position, which is the focal position of the imaging device in the inspection image, from magnification information indicating the relationship between the focal position and the imaging magnification of the imaging device and the calculated imaging magnification.

[0018] Furthermore, in order to achieve the above objective, a program according to one embodiment of the present disclosure is a program for causing a computer to execute a method for inspecting a display panel, and causes the computer to execute the following: an acquisition step of obtaining a one-dimensional brightness profile by performing image processing to compress the brightness of an inspection image of a pixel area of ​​the display panel captured by a shooting device into a one-dimensional brightness with the axis perpendicular to the direction of arrangement of the multiple subpixels that constitute one pixel in a plurality of pixels each composed of a plurality of subpixels; a generation step of generating a frequency spectral intensity profile by performing a Fourier transform on the one-dimensional brightness profile; a calculation step of calculating the shooting magnification of the shooting device from one or more peak positions included in the frequency spectral intensity profile based on the fact that the plurality of pixels in the pixel area are formed in a periodic structure; and an estimation step of estimating the current focal position, which is the focal position of the shooting device in the inspection image, from magnification information showing the relationship between the focal position and the shooting magnification of the shooting device and the calculated shooting magnification.

[0019] These general or specific embodiments may be implemented as devices, methods, integrated circuits, computer programs, or recording media such as computer-readable CD-ROMs, or as any combination of systems, methods, integrated circuits, computer programs, and recording media. [Effects of the Invention]

[0020] This disclosure provides an inspection method that does not require dedicated hardware and can autofocus with high focusing accuracy and high speed. [Brief explanation of the drawing]

[0021] [Figure 1] Figure 1 is a diagram showing the schematic configuration of an inspection system including an inspection device according to an embodiment. [Figure 2] Figure 2 shows an example of a computer hardware configuration that implements the functions of the inspection device according to the embodiment using software. [Figure 3] FIG. 3 is a block diagram showing an example of the functional configuration of the inspection apparatus according to the embodiment. [Figure 4] FIG. 4 is an example of an inspection image of a pixel region of the display panel according to the embodiment. [Figure 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 the display panel according to the embodiment. [Figure 7B] FIG. 7B is a diagram showing a one-dimensional luminance profile when the luminance of the inspection image shown in FIG. 7A is compressed on the Y-axis. [Figure 8] FIG. 8 is a diagram for explaining an example of a one-dimensional luminance profile that has been subjected to fast Fourier transform processing by the generation unit according to the embodiment. [Figure 9] FIG. 9 is a diagram showing a frequency spectrum intensity profile when fast Fourier transform processing is performed twice on the one-dimensional luminance profile of FIG. 6. [Figure 10] FIG. 10 is a diagram for explaining another example of a one-dimensional luminance profile that has been subjected to fast Fourier transform processing by the generation unit according to the embodiment. [Figure 11] FIG. 11 is a diagram showing a frequency spectrum intensity profile when fast Fourier transform processing 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 when the value of the fundamental frequency according to the embodiment is used as the magnification. [Figure 13] FIG. 13 is a flowchart showing the operation of the inspection apparatus according to the embodiment.

Embodiments for Carrying Out the Invention

[0022] The embodiments of this disclosure will be described in detail below with reference to the drawings. Each embodiment described below is a specific example of this disclosure. The numerical values, shapes, materials, standards, components, arrangement and connection configurations of components, steps, and the order of steps shown in the following embodiments are examples only and are not intended to limit this disclosure. Furthermore, components in the following embodiments that are not described in the independent claims of this disclosure will be described as optional components. Also, the figures are not necessarily strictly accurate. In each figure, substantially identical components are denoted by the same reference numerals, and redundant explanations may be omitted or simplified.

[0023] (Embodiment) The following describes the inspection apparatus and other related devices according to this embodiment.

[0024] [1. Inspection System] The inspection device 10 according to this embodiment will be described below with reference to the figures.

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

[0026] The inspection system shown in Figure 1 comprises an inspection device 10, an imaging device 20, a stage 21, and a stage drive unit 22.

[0027] The inspection device 10 is a device for performing image inspection using inspection images captured from the pixel area of ​​a display panel 30. Here, the display panel 30 is a liquid crystal display panel, an organic EL display panel, etc., and may be a rigid panel or a flexible panel. Multiple pixels are arranged in a matrix in the pixel area of ​​the display panel 30. Each of the multiple pixels is composed of multiple subpixels, such as RGB subpixels.

[0028] The imaging device 20 is composed of an optical system that focuses the lens using a full-group extension method, and captures the pixel area of ​​the display panel 30. In optical systems such as the full-group extension method, there is a strong correlation between the focus position and the magnification. Alternatively, the imaging device 20 may be composed of an optical system that focuses the lens using an inner focus method, and capture the pixel area of ​​the display panel 30. Even in optical systems such as inner focus, there is a strong correlation between the focus position and the magnification. The magnification is the ratio of the size of the image projected on the imaging surface to the actual size of the subject. Furthermore, as shown in Figure 1, the distance between the imaging device 20 and the display panel 30 is kept approximately constant, and the focus position is adjusted by moving the device as shown in Figures 1(a) to (c). In Figure 1, Figure 1(b) shows an example of the in-focus position, while Figures 1(a) and (c) show examples of out-of-focus positions.

[0029] The imaging device 20 acquires an inspection image of the display panel 30 by capturing the pixel area of ​​the display panel 30. The imaging device 20 can adjust the focus position of its optical system by moving to positions such as (a), (b), or (c) shown in Figure 1. The imaging device 20 is controlled by the inspection device 10, but may also be controlled by another computer.

[0030] Stage 21 holds the display panel 30.

[0031] The stage drive unit 22 consists of a ball screw, guide rails, and a motor, and moves the stage 21 relative to the imaging device 20. The stage drive unit 22 is controlled by the inspection device 10, but it may also 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 this embodiment, an example of the hardware configuration of the inspection device 10 according to this embodiment will be explained using Figure 2.

[0033] Figure 2 shows an example of the hardware configuration of a computer 1000 that implements the functions of the inspection device 10 according to this embodiment using software.

[0034] As shown in Figure 2, computer 1000 is a computer equipped with an input device 1001, an output device 1002, a CPU 1003, internal storage 1004, RAM 1005, a GPU 1006, a reader 1007, a transceiver 1008, and a bus 1009. The input device 1001, output device 1002, CPU 1003, internal storage 1004, RAM 1005, reader 1007, and transceiver 1008 are connected by the bus 1009.

[0035] The input device 1001 is a user interface device such as an input button, touchpad, or touch panel display, and accepts user input. In addition to accepting user touch input, the input device 1001 may also be configured to accept voice input or remote control input.

[0036] The output device 1002 also serves as the input device 1001 and consists of a touchpad or touch panel display, which notifies the user of information that needs to be known.

[0037] The internal storage 1004 is flash memory or the like. The internal storage 1004 may also pre-store at least one of the following: a program for realizing the functions of the inspection device 10, and an application that utilizes the functional configuration of the inspection device 10. Furthermore, the internal storage 1004 may store procedures for image processing described later, mathematical formulas for Fourier transform (FFT) processing, mathematical formulas for fast Fourier transform (FFT) processing, procedures including programs, procedures for calculating the magnification of the imaging device 20, procedures for estimating the current focus position of the imaging device 20, and magnification information of the imaging device 20.

[0038] RAM1005 is Random Access Memory, used to store data during the execution of a program or application.

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

[0040] The reader 1007 reads information from a recording medium such as a USB (Universal Serial Bus) memory. The reader 1007 reads the program or application from the recording medium on which the program or application is recorded and stores it in the built-in storage 1004.

[0041] The transceiver 1008 is a communication circuit for wireless or wired communication. The transceiver 1008 may, for example, communicate with a server device connected to a network and download programs and applications like the ones described above from the server device and store them in the internal 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 then sequentially reads and executes the instructions contained in those programs and applications from the RAM 1005.

[0043] [1-2. Functional configuration of inspection device 10] Next, the functional configurations of the inspection device 10 according to this embodiment will be explained using Figure 3.

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

[0045] As shown in Figure 3, the inspection device 10 comprises 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 for 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 the pixel area 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 that compresses the luminance of the acquired inspection image into a one-dimensional luminance with the axis perpendicular to the direction of the arrangement of multiple subpixels that constitute one pixel in multiple pixels. Each of the above multiple pixels is composed of multiple subpixels. Furthermore, the acquisition unit 101 can realize the above image processing function and acquisition function by having the processor execute a control program stored in memory in the computer that realizes the functions of the inspection device 10.

[0047] Figure 4 is an example of an inspection image of the pixel area of ​​the display panel 30 according to this embodiment. In Figure 4, an example of a focused inspection image is shown as inspection image 61. The pixel area shown in inspection image 61 shows multiple pixels, which are the constituent units of the screen displayed by the display panel 30, and subpixels, which are monochromatic dots such as RGB, obtained by further dividing that single pixel. In other words, inspection image 61 in Figure 4 shows a pixel area of ​​the display panel 30 composed of multiple pixels, where monochromatic subpixels such as RGB function together as a single pixel. In the example shown in Figure 4, one pixel is formed by a matrix of vertically elongated rectangular subpixels, each with a width of B (Blue) subpixel wider than the widths of R (Red) and G (Green) subpixels. That is, the pixel area shown in inspection image 61 in Figure 4 is formed by multiple pixels in a periodic structure. In the following, the direction in which multiple subpixels make up a single pixel, that is, the direction in which multiple subpixels make up a single pixel in a group of pixels each composed of multiple subpixels, will be referred to as the X-axis. The direction perpendicular to the direction in which multiple subpixels make up a single pixel will be referred to as the Y-axis.

[0048] Figure 5 shows the one-dimensional luminance profile 62 obtained when the luminance of the inspection image 61 shown in Figure 4 is compressed along the X-axis. Figure 6 shows the one-dimensional luminance profile 63 obtained when the luminance of the inspection image 61 shown in Figure 4 is compressed along the Y-axis. In Figures 5 and 6, the vertical axis represents luminance, or more precisely, the sum of luminances. In Figure 5, the horizontal axis represents the X-coordinate, i.e., the pixel position on the X-axis, and in Figure 6, the horizontal axis represents the Y-coordinate, i.e., the pixel position on the Y-axis. Compression along the X-axis means calculating the sum of the luminances of all pixels along the Y-axis at each pixel position on the X-axis. Similarly, compression along the Y-axis means calculating the sum of the luminances of all pixels along the X-axis at each pixel position on the Y-axis.

[0049] In this embodiment, the acquisition unit 101 acquires an inspection image 61, for example, shown in Figure 4, as an inspection image of the pixel area of ​​the display panel 30 captured by the imaging device 20. The acquisition unit 101 also performs image processing on the acquired inspection image 61 to compress the brightness to one dimension along the Y axis, thereby acquiring a one-dimensional brightness profile 63, for example, shown in Figure 6.

[0050] Here, the reason for compressing the brightness of the inspection image 61 on the Y axis rather than the X axis will be explained using the one-dimensional brightness profile 62 shown in Figure 5 and the one-dimensional brightness profile 63 shown in Figure 6.

[0051] The one-dimensional luminance profile 62 shown in Figure 5 compresses luminance along the X-axis, that is, in the direction of the arrangement of multiple subpixels constituting one pixel. Although the arrangement on a per-pixel basis is periodic, the arrangement of multiple subpixels within a per-pixel unit (i.e., the arrangement of subpixels along the X-axis) is not symmetrical, resulting in a complex shape for the one-dimensional luminance profile 62 shown in Figure 5. On the other hand, the one-dimensional luminance profile 63 shown in Figure 6 compresses luminance along the Y-axis, that is, in the direction perpendicular to the direction of the arrangement of multiple subpixels constituting one pixel. Since the arrangement on a per-pixel basis along the Y-axis follows the same pattern, the one-dimensional luminance profile 63 shown in Figure 6 has a simple shape. In other words, a simpler shape for the one-dimensional luminance profile is preferable in order to perform a Fourier transform (Fast Fourier Transform) in the generation unit 102 described later and determine what kind of waveform the shape (waveform) of the one-dimensional luminance profile is made up of. Note that when the cell pitch is equally spaced, that is, when the widths of the R, G, and B subpixels are equal, the luminance can be compressed along either the X-axis or the Y-axis.

[0052] In this way, the acquisition unit 101 can acquire a one-dimensional luminance profile from the inspection image of the pixel area of ​​the display panel 30 captured by the imaging device 20.

[0053] For comparison, we will also explain the case where a blurry, or out-of-focus, inspection image is obtained.

[0054] Figure 7A is another example of an inspection image of the pixel area of ​​the display panel 30 according to this embodiment. Figure 7B shows a one-dimensional luminance profile 66 obtained when the luminance of the inspection image 65 shown in Figure 7A is compressed along the Y axis.

[0055] In other words, the acquisition unit 101 acquires, for example, a blurry inspection image 65 as shown in Figure 7A, as an inspection image of the pixel area of ​​the display panel 30 captured by the imaging device 20. Then, the acquisition unit 101 performs image processing to compress the brightness of the acquired inspection image 65 to one-dimensional brightness on the Y axis, thereby acquiring, for example, a one-dimensional brightness profile 66 as shown in Figure 7B. It can be seen that the shape of the one-dimensional brightness profile 66 shown in Figure 7B is different from the shape of the one-dimensional brightness profile 63 shown in Figure 6.

[0056] [1-2-2. Generation unit 102] The generation unit 102 generates a frequency spectral intensity profile by performing a Fourier transform on a one-dimensional luminance profile. The generation unit 102 can perform the Fourier transform processing and generation functions by having a processor execute a control program stored in memory of the computer that implements the functions of the inspection device 10.

[0057] In the following explanation, we will use the Fast Fourier Transform (FFT) as an example, but any algorithm for performing the Fourier Transform will work.

[0058] Furthermore, the generation unit 102 may perform a Fast Fourier Transform (FFT) on the one-dimensional luminance profile acquired by the acquisition unit 101 not only once, but twice. More specifically, the generation unit 102 may generate a frequency spectrum intensity profile by performing a Fast Fourier Transform (FFT) on the one-dimensional luminance profile acquired by the acquisition unit 101 twice. Here, the frequency spectrum intensity profile may be generated by performing a Fast Fourier Transform (FFT) multiple times.

[0059] Figure 8 is a diagram illustrating an example of a one-dimensional luminance profile processed by the generation unit 102 according to this embodiment. Figure 8(a) shows the one-dimensional luminance profile 63 of Figure 6, and Figure 8(b) shows the frequency spectral intensity profile 63a when the one-dimensional luminance profile 63 of Figure 8(a) is subjected to one Fast Fourier Transform. Figure 9 is a diagram showing the frequency spectral intensity profile 63b when the one-dimensional luminance profile 63 of Figure 6 is subjected to two Fast Fourier Transforms.

[0060] In this embodiment, the generation unit 102 performs a Fast Fourier Transform (FFT) once or twice on the one-dimensional luminance profile 63 shown in Figure 8(a), for example.

[0061] For example, by treating the shape of the one-dimensional luminance profile 63 shown in Figure 8(a) as a waveform and performing a Fast Fourier Transform (FCR) once, the frequency spectral intensity profile 63a shown in Figure 8(b) is generated. Alternatively, by treating the shape of the one-dimensional luminance profile 63 shown in Figure 8(a) as a waveform and performing a FCR twice, the frequency spectral intensity profile 63b shown in Figure 9 is generated.

[0062] Here, we will also explain the case where the Fast Fourier Transform process is performed once or twice on the one-dimensional luminance profile 66 of the out-of-focus inspection image 65.

[0063] Figure 10 is a diagram illustrating another example of a one-dimensional luminance profile processed by the generation unit 102 according to this embodiment. Figure 10(a) shows the one-dimensional luminance profile 66 of Figure 7B, and Figure 10(b) shows the frequency spectral intensity profile 66a when the one-dimensional luminance profile 66 of Figure 10(a) is subjected to one Fast Fourier Transform. Figure 11 is a diagram showing the frequency spectral intensity profile 66b when the one-dimensional luminance profile 66 of Figure 7B is subjected to two Fast Fourier Transforms.

[0064] For example, by treating the shape of the one-dimensional luminance profile 66 shown in Figure 10(a) as a waveform and performing a Fast Fourier Transform (FCR) once, the frequency spectral intensity profile 66a shown in Figure 10(b) is generated. Also, for example, by treating the shape of the one-dimensional luminance profile 63 shown in Figure 8(a) as a waveform and performing a FCR twice, the frequency spectral intensity profile 66b shown in Figure 11 is generated.

[0065] In the frequency spectral intensity profile 66a shown in Figure 10(b), it can be seen that there are no waves in the power spectrum of the high-frequency components, compared to the frequency spectral intensity profile 63a shown in Figure 8(b).

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

[0067] [1-2-3. Calculation Unit 103] The calculation unit 103 calculates the imaging magnification of the imaging device 20 from one or more peak positions included in the frequency spectral intensity profile, based on the fact that multiple pixels are formed in a periodic structure in the pixel area of ​​the display panel 30. More specifically, the calculation unit 103 calculates the imaging magnification of the imaging 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 a single pixel in the pixel area that is captured in the inspection image. Note that the calculation function of the calculation unit 103 can be realized, for example, in a computer that implements the functions of the inspection device 10, by having the processor execute a control program stored in memory.

[0068] In this embodiment, the calculation unit 103 calculates the imaging 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 imaging magnification is the ratio of the size of the image projected on the imaging surface to the actual size of the subject. In other words, in this embodiment, the imaging magnification is the ratio of the size of the pixels in the pixel area projected in the inspection image captured by the imaging device 20 to the size of the pixels in the actual pixel area of ​​the display panel 30.

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

[0070] Here, as shown in Figure 8(a), the one-dimensional luminance profile 63 is composed of 1000 data points (1000 pixels). As shown in Figure 8(b), the numerical value of the peak position of the fundamental frequency wave in the frequency spectral intensity profile 63a, i.e., the wave indicated by the dotted circle a, is 7. The calculation unit 103 can calculate 1000 / 7 = 143, so it can be estimated that in the one-dimensional luminance profile 63 shown in Figure 8(a), the wave with a period of 143 data points corresponds to the wave indicated by the dotted circle a. In addition, the inspection image 61 shown in Figure 4 shows a pixel region with a periodic structure in the Y-axis direction, where eight pixels are lined up, and in the one-dimensional luminance profile 63 shown in Figure 8(a), eight waves are shown indicated by the dotted circle a. From these, it can be seen that the wave indicated by the dotted circle a corresponds to a wave for each pixel. Therefore, it can be seen that the fundamental frequency wave indicated by the dotted circle a in the frequency spectral intensity profile 63a corresponds to a wave for each pixel.

[0071] Similarly, for example, the wave indicated by the dotted circle b in the frequency spectral intensity profile 63a of Figure 8(b) is estimated to be the same wave indicated by the dotted circle b in the one-dimensional luminance profile 63 shown in Figure 8(a). More specifically, as shown in Figure 8(a), the one-dimensional luminance profile 63 consists of 1000 data points (100 pixel data points). As shown in Figure 8(b), the numerical value of the peak position of the wave indicated by the dotted circle b in the frequency spectral intensity profile 63a is 14. The calculation unit 103 can calculate 1000 / 14=71, so it is estimated that the wave with a period of 71 data points in the one-dimensional luminance profile 63 shown in Figure 8(a) corresponds to the wave indicated by the dotted circle b. Note that the wave indicated by the dotted circle b in Figure 8(a) corresponds to the wave with two bumps included in the wave indicated by the dotted circle a. Furthermore, in the frequency spectral intensity profile 63a of Figure 8(b), the frequency of the wave peak indicated by the dotted circle b is twice the fundamental frequency.

[0072] Similarly, the calculation unit 103 estimates, for example, that the wave indicated by the dotted circle c in the frequency spectral intensity profile 63a of Figure 8(b) is the same wave indicated by the dotted circle c in the one-dimensional luminance profile 63 shown in Figure 8(a). Note that the wave indicated by the dotted circle c in Figure 8(a) corresponds to the three spikes contained in the wave indicated by the dotted circle c. Also, the frequency at the peak position of the wave indicated by the dotted circle c in the frequency spectral intensity profile 63a of Figure 8(b) 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 spectral intensity profile, and can calculate the data period for each pixel from the structural properties that show 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 that appears in the inspection image captured by the imaging device 20, and can calculate the imaging magnification using the actual pixel size in the pixel region of the display panel 30.

[0074] In this embodiment, the calculation unit 103 may calculate the peak position value of the fundamental frequency obtained by performing one or two Fast Fourier Transform processes on the one-dimensional luminance profile as the imaging magnification.

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

[0076] The above describes the frequency spectral intensity profile 63a of the in-focus inspection image 61, but the same can be said for the frequency spectral intensity profile 66a of the out-of-focus inspection image 65, which will be explained below.

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

[0078] More specifically, as shown in Figure 10(a), the one-dimensional luminance profile 66 consists of 1000 data points (100 pixel data points). As shown in Figure 10(b), in the frequency spectral intensity profile 66a, the numerical value of the peak position of the fundamental frequency wave indicated by the dotted circle a is 7. The calculation unit 103 can calculate 1000 / 7 = 143, so it can be estimated that in the one-dimensional luminance profile 66 shown in Figure 10(a), the wave with a period of 143 data points corresponds to the wave indicated by the dotted circle a. It can also be seen that the wave indicated by the dotted circle a in Figure 10(a) corresponds to a single pixel. Thus, it can be seen that the fundamental frequency wave indicated by the dotted circle a in the frequency spectral intensity profile 66a corresponds to a single pixel.

[0079] Similarly, for example, the wave indicated by the dotted circle b in the frequency spectral intensity profile 66a of Figure 10(b) is estimated to be the same wave indicated by the dotted circle b in the one-dimensional luminance profile 66 shown in Figure 10(a). More specifically, as shown in Figure 10(a), the one-dimensional luminance profile 66 consists of 1000 data points (100 pixel data points). As shown in Figure 10(b), the numerical value of the peak position of the wave indicated by the dotted circle b in the frequency spectral intensity profile 66a is 14. The calculation unit 103 can calculate 1000 / 14=71, so it can be estimated that the wave with a period of 71 data points in the one-dimensional luminance profile 66 shown in Figure 10(a) corresponds to the wave indicated by the dotted circle b. Note that the wave indicated by the dotted circle b in Figure 10(a) corresponds to the wave with two bumps included in the wave indicated by the dotted circle a. Furthermore, in the frequency spectral intensity profile 66a of Figure 10(b), the frequency of the peak position of the wave indicated by the dotted circle b is twice the fundamental frequency.

[0080] Thus, with respect to the fundamental frequency, the frequency spectral intensity profile 66a of the out-of-focus inspection image 65 can be treated in the same way as the frequency spectral 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 spectral intensity profile 66a of the out-of-focus inspection image 65.

[0081] Similarly, the calculation unit 103 may calculate the fundamental frequency value 7 of the frequency spectrum intensity profile 66a in Figure 10(b), obtained by performing a fast Fourier transform on the one-dimensional luminance profile once, as the imaging magnification. Alternatively, the calculation unit 103 may calculate the fundamental frequency value of the frequency spectrum intensity profile 66b in Figure 11, obtained by performing a fast Fourier transform on the one-dimensional luminance profile twice, as the imaging magnification. In the frequency spectrum intensity profile 66b in Figure 11, the wave indicated by the dotted circle d is the wave with the lowest frequency component, so the frequency at 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 the current focus position, which is the focus position of the imaging device 20 in the inspection image, from magnification information showing the relationship between the focus position and the magnification in the imaging device 20, and the magnification calculated by the calculation unit 103. The estimation unit 104 can be implemented in a computer that implements the functions of the inspection device 10, for example, by having a processor execute a control program stored in memory.

[0083] In the optical system of the imaging device 20 according to this embodiment, such as a full-group extension type, the focal position and the magnification are one-to-one. This magnification information, which shows the relationship between the focal position and the magnification in the imaging device 20, can be acquired in advance. Furthermore, even if the imaging 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 magnification in such an optical system. For this reason, the magnification information showing the relationship between the focal position and the magnification in the imaging device 20 can be acquired in advance.

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

[0085] As described above, in this embodiment, the fundamental frequency value obtained by performing a Fast Fourier Transform on the one-dimensional luminance profile of the pixel area image of the display panel 30 captured by the imaging device 20 may be used as the imaging magnification. In this case, the fundamental frequency value (imaging magnification) obtained by performing a Fast Fourier Transform on the one-dimensional luminance profile at each of the multiple focus positions of the imaging device 20, and information showing the relationship between the multiple focus positions, can be used as the magnification information of the imaging device 20.

[0086] Figure 12 shows an example of magnification information when the fundamental frequency value according to this embodiment is used as the imaging magnification. The FFT value shown in Figure 12 is the fundamental frequency value obtained by performing a Fast Fourier Transform process twice on a one-dimensional luminance profile.

[0087] Figure 12 shows the relationship between the FFT values ​​obtained from images of the pixel region of the display panel 30 captured at multiple focal positions of the imaging device 20 and the focal position, as magnification information 70. The magnification information 70 shown in Figure 12 was created as follows: First, 100 focus-shifted images were obtained by shifting the focal position of the imaging device 20 in 10 μm increments within the range of -500 μm to 500 μm and capturing the pixel region of the display panel 30. Next, the FFT values, which are the fundamental frequency values ​​for the 100 focus-shifted images, were calculated by performing two Fast Fourier Transforms on the one-dimensional luminance profiles obtained by compressing the 100 acquired focus-shifted images along the Y axis. Then, the relationship between 100 different focal positions and the FFT values ​​was approximated by a straight line to obtain an approximate straight line. In this way, the magnification information 70 shown in Figure 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 Figure 12. Furthermore, by using the magnification information 70 shown in Figure 12, the distance from the current focus position to the 0 μm focus position, which is the in-focus position, can be calculated.

[0089] In the example shown in Figure 12, the fundamental frequency value obtained by performing a Fast Fourier Transform (FFT) process twice on a one-dimensional luminance profile was described as the FFT value, but this is not the only option. The fundamental frequency value obtained by performing a Fast Fourier Transform (FFT) process once on a one-dimensional luminance profile may also be used as the FFT value. In this case as well, magnification information similar to the magnification information 70 shown in Figure 12 can be created, and 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 similarly created magnification information.

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

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

[0092] In this way, the inspection device 10 can focus the image of the imaging device 20, thereby obtaining a high-quality, in-focus inspection image.

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

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

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

[0096] Next, the inspection device 10 obtains a one-dimensional luminance profile (S12) by performing image processing on the inspection image acquired in step S11 to compress it to one-dimensional luminance along the Y axis. More specifically, the acquisition unit 101 obtains a one-dimensional luminance profile obtained by performing image processing on the luminance of the acquired inspection image to compress it to one-dimensional luminance with the axis (Y axis) being the vertical direction of the arrangement of the multiple subpixels that constitute one pixel in a plurality of pixels each composed of multiple subpixels. For example, the acquisition unit 101 obtains a one-dimensional luminance profile obtained by compressing the luminance of the inspection image along the Y axis, such as the one-dimensional luminance profile 63 shown in Figure 6 or the one-dimensional luminance profile 66 shown in Figure 7B.

[0097] Next, the inspection device 10 generates a frequency spectral intensity profile by performing a Fast Fourier Transform on the one-dimensional luminance profile acquired in step S12 (S13). More specifically, the generation unit 102 generates a frequency spectral intensity profile by performing a Fast Fourier Transform 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 spectral intensity profile such as the frequency spectral intensity profile 63a shown in Figure 8(b) or the frequency spectral intensity profile 66a shown in Figure 10(b). Alternatively, the calculation unit 103 may perform a Fast Fourier Transform on the one-dimensional luminance profile twice to generate a frequency spectral intensity profile such as the frequency spectral intensity profile 63b shown in Figure 9 or the frequency spectral intensity profile 66b shown in Figure 11.

[0099] Next, the inspection device 10 calculates the imaging 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 imaging magnification of the imaging device 20 from the frequency and power spectrum magnitudes 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 a single pixel in the pixel area that appears in the inspection image, and calculates the imaging 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 Figure 8(b) or the frequency spectrum intensity profile 66a in Figure 10(b), and uses the calculated fundamental frequency to calculate the imaging magnification.

[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 showing the relationship between the focus position and the imaging magnification of the imaging device 20, and the calculated imaging magnification. Alternatively, the imaging magnification may be the value of the fundamental frequency obtained by performing one or two Fast Fourier Transforms on the one-dimensional luminance profile of the image of the pixel area of ​​the captured display panel 30. In this case, by using the value of the fundamental frequency obtained by performing one or two Fast Fourier Transforms (imaging magnification) and information showing the relationship between multiple focus positions as the magnification information of the imaging device 20, the current focus position can be estimated from the calculated imaging magnification.

[0101] [1-4. Effects, etc.] The inspection apparatus 10, etc. according to this embodiment, performs image processing to compress the brightness of the inspection image of the pixel area of ​​the display panel 30 captured by the imaging device 20 into a one-dimensional brightness axis with the vertical direction of the arrangement of multiple subpixels constituting one pixel in a plurality of pixels each composed of multiple subpixels. A frequency spectral intensity profile is generated by performing a Fourier transform on the one-dimensional brightness profile obtained by such image processing. This Fourier transform is performed at least once, but may be performed twice. Furthermore, the inspection apparatus 10, etc. according to this embodiment calculates the shooting magnification of the imaging device 20 from one or more peak positions included in the frequency spectral intensity profile, based on the fact that multiple pixels are formed in a periodic structure in the pixel area. Then, the current focal position of the imaging device 20 in the inspection image is estimated from magnification information showing the relationship between the focal position and the shooting magnification of the imaging device 20 and the calculated shooting magnification.

[0102] As described above, the inspection apparatus 10, etc., according to this embodiment compresses the inspection image captured by the imaging device 20 into one dimension in terms of brightness and then performs a Fourier transform. Then, using the frequency spectral intensity profile obtained by the Fourier transform, the current focal position of the imaging device 20 in the inspection image is estimated. There is a strong correlation between the focal position and the magnification of the optical system, such as the lens, of the imaging device 20, and the property that a periodic structure is formed in the pixel area of ​​the display panel 30 is utilized to estimate the current focal position from the frequency spectral intensity profile.

[0103] In other words, the inspection device 10, etc. according to this embodiment can estimate the current focus position of the imaging device 20 in the inspection image solely through computational processing, without requiring dedicated hardware. Furthermore, due to the performance of computers equipped with modern processors, etc., the inspection device 10, etc. according to this embodiment can perform high-speed Fourier transform processing of the inspection image captured by the imaging device 20 by compressing its brightness to one dimension.

[0104] Therefore, the inspection device 10, etc., according to this embodiment does not require dedicated hardware and can perform processing to autofocus at high speed.

[0105] In this embodiment, the inspection device 10 estimates that the peak position of the fundamental frequency among the one or more peak positions included in the frequency spectral intensity profile corresponds to the peak position of a single pixel in the pixel region visible in the inspection image. Then, the imaging magnification of the imaging device 20 is calculated from the estimated fundamental frequency peak position.

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

[0109] Furthermore, the inspection apparatus 10, etc., according to this embodiment may generate a frequency spectrum intensity profile by performing a Fourier transform twice on a one-dimensional luminance profile obtained by compressing the inspection image captured by the imaging device 20 to one dimension. This makes it easier to estimate the fundamental frequency from the frequency spectrum intensity profile.

[0110] Furthermore, the magnification information does not necessarily have to be obtained from the optical properties of the imaging device 20. More specifically, the magnification information may be information showing the relationship between the fundamental frequency value obtained by Fourier transforming the one-dimensional luminance profile of the pixel area image of the display panel 30 captured at each of the multiple focal positions of the imaging device 20, and the multiple focal positions. Here, the fundamental frequency value is defined as the imaging magnification.

[0111] This allows for high-speed estimation of the current focus position by directly estimating the current focus position using magnification information from the fundamental frequency of the frequency spectrum intensity profile generated by one or two Fourier transform operations.

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

[0113] Thus, the current focus position and the amount of movement of the imaging device 20 required for focusing can be obtained solely through calculations using magnification information and inspection images. Therefore, dedicated hardware is not required, and high-speed autofocus processing can be performed.

[0114] In other words, the inspection device 10, etc., according to this embodiment does not require dedicated hardware and can autofocus with high focusing accuracy and high speed.

[0115] In other words, the inspection device 10, etc., according to this embodiment does not require dedicated AF hardware and can perform autofocus (AF) processing at high speed using the inspection image itself captured by the imaging device 20. This makes it possible to achieve high-speed AF processing that does not require dedicated AF hardware, has high focus accuracy, and does not require calibration.

[0116] The inspection apparatus and inspection method relating to this disclosure have been described above based on embodiments and modifications, but this disclosure is not limited to these embodiments and modifications. Within the scope of this disclosure, various modifications conceivable by those skilled in the art, as well as other forms constructed by combining some of the components of the embodiments and modifications, are also included, as long as they do not deviate from the spirit of this disclosure.

[0117] Furthermore, the following forms may also be included within the scope of one or more aspects of this disclosure.

[0118] (1) Some of the components constituting the above-described inspection apparatus may be a computer system consisting 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 in accordance with the computer program. Here, the computer program is composed of a combination of multiple instruction codes that indicate commands to the computer in order to achieve a predetermined function.

[0119] (2) Some of the components constituting the above-described inspection apparatus may be made up of a single system LSI (Large Scale Integration). The system LSI is a multi-functional LSI manufactured by integrating multiple components onto a single chip, and specifically, it is a computer system that includes a microprocessor, ROM, RAM, GPU, etc. The RAM stores a computer program. The system LSI achieves its function by operating the microprocessor or the GPU in accordance with the computer program.

[0120] (3) Some of the components constituting the above inspection apparatus may consist of detachable IC cards or standalone modules attached to each apparatus. The IC card or module is a computer system consisting of a microprocessor, ROM, RAM, GPU, etc. The IC card or module may include the above-mentioned multi-functional LSI. The IC card or module achieves its function by operating the microprocessor or GPU according to a computer program. The IC card or module may be tamper-resistant.

[0121] (4) Furthermore, some of the components constituting the above-described inspection apparatus may be the computer program or the digital signal recorded on a recording medium that can be read by a computer, such as a flexible disk, hard disk, CD-ROM, MO, DVD, DVD-ROM, DVD-RAM, BD (Blu-ray® Disc), semiconductor memory, etc. Alternatively, the digital signal may be recorded on one of these recording media.

[0122] Furthermore, some of the components constituting the above-described determination device may transmit the computer program or the digital signal via telecommunications lines, wireless or wired communication lines, networks such as the Internet, data broadcasting, etc.

[0123] (5) The disclosure may also be the methods described above. Alternatively, it may be a computer program that implements these methods using a computer, or a digital signal consisting of the computer program.

[0124] (6) The Disclosure also relates to a computer system comprising a microprocessor, a GPU, and memory, wherein the memory stores the computer program, and the microprocessor or the GPU operates in accordance with the computer program.

[0125] (7) Alternatively, the program or the digital signal may be carried out 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 or the like.

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

[0127] (9) The above embodiments and the above modifications may be combined. [Industrial applicability]

[0128] This disclosure can be used in inspection methods, inspection apparatus, and programs that enable low-cost, high-focus accuracy, and high-speed autofocus when capturing inspection images in an inspection process that uses inspection images of the pixel area of ​​a display panel. [Explanation of Symbols]

[0129] 10 Inspection equipment 20 Imaging device 21 stages 22 Stage drive unit 30 Display Panels 61, 65 Examination images 62, 63, 66 1D luminance profiles 63a, 63b, 66a, 66b Frequency Spectral Intensity Profiles 101 Acquisition Department 102 Generation part 103 Calculation Unit 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 Reader 1008 Transceiver 1009 Bus

Claims

1. A computer-based method for inspecting display panels, The acquisition step involves obtaining a one-dimensional luminance profile by performing image processing to compress the luminance of the inspection image of the pixel area of ​​the display panel captured by the imaging device into a one-dimensional luminance with the axis perpendicular to the direction of arrangement of the multiple subpixels that constitute one pixel in a plurality of pixels each composed of multiple subpixels, and A generation step of generating a frequency spectral intensity profile by performing a Fourier transform on the aforementioned one-dimensional luminance profile, A calculation step in which, based on the fact that the plurality of pixels in the pixel region are formed in a periodic structure, the imaging magnification of the imaging device is calculated from one or more peak positions included in the frequency spectral intensity profile, The method includes magnification information showing the relationship between the focal position and the magnification in the imaging device, and an estimation step of estimating the current focal position, which is the focal position of the imaging device in the inspection image, from the calculated magnification. Testing method.

2. In the calculation step described above, By estimating that the peak position of the fundamental frequency among the one or more peak positions corresponds to the structure of a single pixel in the pixel region shown in the inspection image, the imaging magnification of the imaging device is calculated from the peak position of the fundamental frequency. The inspection method according to claim 1.

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

4. The magnification information is information that shows the relationship between the multiple focal positions and the fundamental frequency value obtained by performing a Fourier transform on the one-dimensional luminance profile of the pixel area image of the display panel captured by the imaging device at each of the multiple focal positions of the imaging device, when this value is defined as the imaging magnification. The inspection method according to claim 2.

5. moreover, The process includes an adjustment step of calculating the amount of movement of the imaging device required for focusing from the estimated current focus position and the magnification information, and adjusting the position of the imaging device using the amount of movement. The inspection method according to any one of claims 1 to 4.

6. A display panel inspection device, An acquisition unit obtains a one-dimensional brightness profile by performing image processing that compresses the brightness of the inspection image of the pixel area of ​​the display panel captured by the imaging device into a one-dimensional brightness with the axis perpendicular to the direction in which the multiple subpixels constituting one pixel are arranged in a plurality of pixels each composed of a plurality of subpixels, A generation unit that generates a frequency spectral intensity profile by performing a Fourier transform on the aforementioned one-dimensional luminance profile, Based on the fact that the plurality of pixels in the pixel region are formed in a periodic structure, a calculation unit calculates the imaging magnification of the imaging device from one or more peak positions included in the frequency spectral intensity profile, The system includes magnification information indicating the relationship between the focal position and the magnification in the imaging device, and an estimation unit that estimates the current focal position, which is the focal position of the imaging device in the inspection image, from the calculated magnification. Inspection device.

7. A program that causes a computer to perform a test method for display panels, The acquisition step involves obtaining a one-dimensional luminance profile by performing image processing to compress the luminance of the inspection image of the pixel area of ​​the display panel captured by the imaging device into a one-dimensional luminance with the axis perpendicular to the direction of arrangement of the multiple subpixels that constitute one pixel in a plurality of pixels each composed of multiple subpixels, and A generation step of generating a frequency spectral intensity profile by performing a Fourier transform on the aforementioned one-dimensional luminance profile, A calculation step in which, based on the fact that the plurality of pixels in the pixel region are formed in a periodic structure, the imaging magnification of the imaging device is calculated from one or more peak positions included in the frequency spectral intensity profile, The computer is instructed to perform the following steps: an estimation step of estimating the current focal position, which is the focal position of the imaging device in the inspection image, from magnification information showing the relationship between the focal position and the magnification in the imaging device, and the calculated magnification. program.

Images