CN115326359A - Method for inspecting display device - Google Patents

Abstract

The invention aims to provide a method for inspecting a display device, which can judge whether a defective pixel exists or not by vision even under the condition of high-definition pixels. The method for inspecting a display device includes a step of alternately displaying a 1 st test pattern image and a 2 nd test pattern image on an entire surface of a display portion at a constant period to inspect whether or not a defective pixel exists, wherein the 1 st test pattern image is periodically arranged with a 1 st unit region displayed at a 1 st grayscale value and a 2 nd unit region adjacent to the 1 st unit region and displayed at a 2 nd grayscale value different from the 1 st grayscale value, the 2 nd test pattern image displays the 1 st unit region at the 2 nd grayscale value and the 2 nd unit region at the 1 st grayscale value, and the 1 st unit region and the 2 nd unit region are 1 pixel respectively.

Description

Method for inspecting display device

Technical Field

One embodiment of the present invention relates to a method for inspecting a display device. And more particularly, to a method of inspecting a display device including a step of inspecting a defective pixel.

Background

As a method for inspecting a display device, a method for determining gamma characteristics by visual observation is disclosed (see patent document 1). This check is performed as follows: in the display unit, a gradation region having a gradation pattern of an inspection color in one direction and a dither (inspection pattern) region having a region of the inspection color and black are arranged adjacently, and the luminance of the gradation region and the luminance of the dither region are compared by visual observation at the same position in one direction.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2016-161612.

Disclosure of Invention

Problems to be solved by the invention

The defective pixel includes a dead (black dot) defect and a bright dot defect. Specifically, the defective pixel defect includes a defect that is not lit regardless of the video signal or has a significantly low gray scale with respect to the gray scale of the video signal, and the bright pixel defect includes a defect that is lit regardless of the video signal or has a significantly high gray scale with respect to the gray scale of the video signal. The visual lighting inspection is performed by lighting the entire display unit and visually judging the presence or absence of the defective pixel as described above by an inspector. However, if the size of the pixel is reduced by high definition, the size of the defect is also reduced, and it is difficult to discriminate the defective pixel. For example, the dead pixel defect is buried by light of peripheral pixels surrounding the dead pixel defect, and it is difficult to visually detect the dead pixel defect. For this reason, it is difficult to visually check the presence or absence of a defective pixel by displaying only a test pattern, and the precision of the pixel is highly refined, which causes a problem of deterioration or variation in the precision of identifying the defective pixel.

In view of the above problems, an object of one embodiment of the present invention is to provide an inspection method capable of visually judging the presence or absence of a defective pixel even when the pixel has high definition.

Means for solving the problems

A method for inspecting a display device according to an embodiment of the present invention includes a step of alternately displaying a 1 st test pattern image and a 2 nd test pattern image over an entire surface of a display portion at a constant period to inspect whether or not defective pixels exist, wherein the 1 st test pattern image includes a 1 st unit region displayed at a 1 st gray scale value and a 2 nd unit region adjacent to the 1 st unit region and displayed at a 2 nd gray scale value different from the 1 st gray scale value, the 2 nd test pattern image displays the 1 st unit region at the 2 nd gray scale value and the 2 nd unit region at the 1 st gray scale value, and the 1 st unit region and the 2 nd unit region are each 1 pixel.

According to the present invention, even when the pixels have high definition, the presence or absence of defective pixels can be visually discriminated.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a display device according to an embodiment of the present invention.

Fig. 2 is a diagram showing a state of a pixel when the 1 st test pattern image used in the inspection method of the display device according to the embodiment of the present invention is displayed.

Fig. 3 is a diagram showing a state of a pixel when a 2 nd test pattern image used in the inspection method of the display device according to the embodiment of the present invention is displayed.

Fig. 4A shows a method of displaying a test pattern image in the method of inspecting a display device according to the embodiment of the present invention.

Fig. 4B shows a method for displaying a test pattern image in the inspection method for a display device according to the embodiment of the present invention.

Fig. 5 is a diagram showing a display state when a defective pixel is included in the 1 st test pattern image according to the embodiment of the present invention.

Fig. 6 is a diagram showing a state of a pixel when a 1 st test pattern image used in the inspection method of the display device according to the embodiment of the present invention is displayed.

Fig. 7 is a diagram showing a state of a pixel when a 2 nd test pattern image used in the inspection method of the display device according to the embodiment of the present invention is displayed.

Fig. 8 is a diagram showing a state of a pixel when the 1 st test pattern image used in the inspection method for a display device according to the embodiment of the present invention is displayed.

Fig. 9 is a diagram showing a state of a pixel when a 2 nd test pattern image used in the inspection method of the display device according to the embodiment of the present invention is displayed.

Fig. 10 shows an inspection system for a display device according to an embodiment of the present invention.

Description of the reference numerals

100: display device, 102: display panel, 104: display unit, 106: scanning line driver circuit, 108: driver IC,110: terminal portion, 112: flexible circuit board, 150: inspection system, 152: control circuit, 154: test pattern image generation circuit, 156: display device drive circuit, 158: a camera, 160: image processing circuit, 162: storage device, 164: input unit, 166: output unit, PX: pixel, SPX: sub-pixel, 201A: 1 st test pattern image, 202A: 2 nd test pattern image.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. However, the present invention can be implemented in various different forms, and is not limited to the description of the embodiments illustrated below. The drawings are for clarity of explanation, and therefore, the width, thickness, shape, and the like of each part may be schematically shown as compared with the actual embodiment. In the present specification and the drawings, the same reference numerals are given to the same elements as those described above with respect to the already-shown drawings (or reference numerals such as a and B are given to the elements after the numerals), and detailed description thereof may be omitted as appropriate. Further, the characters "1 st" and "2 nd" are used for distinguishing the elements from each other, and do not have the same meaning unless otherwise specified.

[ 1 st embodiment ]

The details of a method for inspecting a defective pixel of a display device according to an embodiment of the present invention will be described with reference to the drawings.

Fig. 1 shows a schematic configuration of a display device 100. The display device 100 includes a display panel 102 and a driver IC108 that outputs a video signal to the display panel 102. The display panel 102 includes a display section 104 composed of a plurality of pixels PX. The plurality of pixels PX are arranged in the display unit 104 in a predetermined arrangement pattern. The driver IC108 is mounted to the flexible circuit board 112. The flexible circuit board 112 is connected to the terminal portion 110 of the display panel 102.

Scanning signal lines and data signal lines, not shown, are disposed in the display portion 104. The display panel 102 may include a scan line driver circuit 106. The scanning line driving circuit 106 is connected to scanning signal lines. The scanning signal line drive circuit 106 outputs a scanning signal. In addition, the driver IC108 is connected to a data signal line. The driver IC108 outputs an image signal. The plurality of pixels PX arranged in the display unit 104 are selected by a scanning signal, and a video signal is sequentially input from a data signal line.

The display portion 104 may be configured to include a liquid crystal display element as a display element, for example. The display portion 104 may include, for example, an organic electroluminescent element as a display element. Further, the display unit 104 may include, for example, a micro LED or a mini LED as a display element. The display portion 104 may have a so-called In-cell type structure In which a capacitive touch sensor is integrated, for example. The display unit 104 incorporates a capacitive touch sensor, and includes, for example, a part of the display element and a part of the touch sensor, such as an electrode and a wiring. The display unit 104 may have a so-called On-cell type structure in which a capacitive touch sensor is mounted, for example.

Fig. 1 is an enlarged view of a region D in the display unit 104 shown in the insertion diagram. The pixel PX includes a plurality of sub-pixels SPX. The insertion diagram of fig. 1 shows an example in which the pixel PX includes a sub-pixel SPXR, a sub-pixel SPXG, and a sub-pixel SPXB. These multiple sub-pixels correspond to each color, e.g., sub-pixel SPXR corresponds to red, sub-pixel SPXG corresponds to green, and sub-pixel SPXB corresponds to blue. The pixel PX controls the gray levels of the 3 primary colors based on the R (red), G (green), and B (blue) of the sub-pixels, and represents the color of 1 dot which is an element of the color image. The display unit 104 displays 1 image by the plurality of pixels PX whose colors are expressed in this manner. In this case, if a certain pixel is defective and color representation cannot be performed accurately, a part of the image is missing, and the missing part may be visually recognized.

Such defects degrade the quality of the displayed image, and therefore, the display device is inspected in a factory before shipment. The defect inspection of the pixels is performed by lighting inspection. That is, the entire surface of the display unit 104 is lit, and whether or not there is a defect in a pixel and whether or not the number of defects is within a reference range are checked. The inspection of the defective pixel is performed, for example, by the visual observation of an inspector. The visual inspection depends on the skill of the inspector, and if the inspection is performed carefully, the productivity is lowered. Further, as the high definition of pixels progresses, there is a problem that it is difficult to identify defective pixels as described above.

In the present embodiment, in the lighting inspection of the display device 100, the display method of the test pattern image displayed on the display unit 104 is studied and designed, whereby the visibility of the defective pixel can be improved and the defective pixel can be easily recognized. The details thereof will be described below.

Fig. 2 shows a partially enlarged view of the display unit 104, showing a state of the pixel PX when the 1 st test pattern image 201A is displayed. The display unit 104 shown in fig. 2 shows a mode in which a plurality of pixels PXjk are arranged in the X-axis direction and the Y-axis direction. Further, the X-axis direction and the Y-axis direction are directions shown in fig. 2 for convenience. Specifically, the pixel PXjk represents a mode in which the pixel PX11 (PX 21), the pixel PX12 (PX 22), the pixel PX13 (PX 23), the pixel PX14 (PX 24), the pixel PX15 (PX 25), and the pixel PX16 (PX 26) are arranged in the X-axis direction, and the pixel PX11, the pixel PX21, the pixel PX31, the pixel PX41, the pixel PX51, the pixel PX61, the pixel PX71, and the pixel PX81 are arranged in the Y-axis direction.

As explained with reference to fig. 1, each pixel PXjk includes subpixels SPXR, SPXG, SPXB. In fig. 2, for each pixel PXjk, the subpixel SPXR, subpixel SPXG, and subpixel SPXB in a bright state (also referred to as lit or emitted light) displayed in grayscale in the 1 st test pattern image 201A are hatched, and the subpixel SPXR, subpixel SPXG, and subpixel SPXB in a dark state (also referred to as unlit or not emitted light) are indicated in black.

As shown in fig. 2, the 1 st test pattern image 201A includes a 1 st unit area displayed at a 1 st grayscale value and a 2 nd unit area displayed at a 2 nd grayscale value. The 1 st and 2 nd gray scale values have different gray scale values. For example, the 1 st gray scale value is 80-100% gray scale, and the 2 nd gray scale value is 0-20% gray scale. The 1 st unit area is adjacent to the 2 nd unit area. The 1 st test pattern image 201A is alternately arranged with the 1 st unit area and the 2 nd unit area in this adjacent relationship.

In the present embodiment, the 1 st unit region and the 2 nd unit region are formed of 1 pixel. The 1 st pixel corresponding to the 1 st unit area is displayed with the 1 st gray scale value to be in a bright state, and the 1 st pixel corresponding to the 2 nd unit area is displayed with the 2 nd gray scale value to be in a dark state. Therefore, the 1 st test pattern image 201A has a periodic pattern in which pixels in a bright state and pixels in a dark state are arranged every 1 st pixel. In other words, the 1 st test pattern image 201A has a pattern in which pixels in a bright state and pixels in a dark state are alternately arranged for every 1 pixel to form a block check (also referred to as a checkered pattern). Specifically, the pixels PX11, PX13, PX15, PX22, PX24, and PX26 are pixels that are in a bright state by gray-scale display (80 to 100% gray scale), and the pixels PX12, PX14, PX16, PX21, PX23, and PX25 are pixels that are in a dark state (0 to 20% gray scale).

In this example, each pixel PXjk displays the subpixel SPXR, subpixel SPXG, and subpixel SPXB at the 1 st grayscale value (bright state) or the 2 nd grayscale value (dark state). When the white display is set to 100% gray scale and the black display is set to 0% gray scale, the 1 st gray scale value (bright state) is in the range of 80-100% gray scale and the 2 nd gray scale value (dark state) is in the range of 0-20% gray scale. For example, when the gray levels of red (R), green (G), and blue (B) are 256 gray levels, the 1 st gray level value of the subpixel SPXR corresponding to red (R), the subpixel SPXG corresponding to green (G), and the subpixel SPXB corresponding to blue (B) is 204 to 255, and the 2 nd gray level value is 0 to 51. When the subpixel SPXR, subpixel SPXG, and subpixel SPXB are displayed at 100% gray scale (lit) as the 1 st gray scale value, the pixel PXjk is displayed in white, and when displayed at 0% gray scale (lit) as the 2 nd gray scale value, the pixel PXjk is displayed in black.

In fig. 2, in the case where a pixel in a bright state is displayed at a 100% gray level and a pixel in a dark state is displayed at a 0% gray level, white dots and black dots are alternately displayed in 1 pixel unit. In addition, in the case where the pixels in the bright state are displayed at the 80% gray scale and the pixels in the dark state are displayed at the 20% gray scale, the bright gray dots and the dark gray dots are alternately displayed in 1 pixel unit.

Fig. 3 shows the 2 nd test pattern image 202A. The 2 nd test pattern image 202A has an inverted pattern of the 1 st test pattern image 201A. That is, the pixels PX11, PX13, PX15, PX22, PX24, and PX26 are pixels in a dark state, and the pixels PX12, PX14, PX16, pixel PX21, pixel PX23, and pixel PX25 are pixels in a bright state.

Fig. 2 and 3 show a partial state of the display unit 104, but the 1 st test pattern image 201A and the 2 nd test pattern image 202A having such a periodic pattern are displayed on the entire display unit 104.

Since the bright state and the dark state (the lit state and the unlit state) are reversed for each 1 pixel (1 dot) in the 1 st test pattern image 201A shown in fig. 2 and the 2 nd test pattern image 202A shown in fig. 3, the observer looks monotonous gray displayed when looking down at the entire display unit 104. In the 1 st test pattern image 201A and the 2 nd test pattern image 202A, the proportions of the pixels in the bright state, the pixels, and the dark state are substantially the same. Therefore, the 1 st test pattern image 201A and the 2 nd test pattern image 202A are displayed in gray of the same gray scale in the entire plan view. Therefore, even if only the 1 st test pattern image 201A or only the 2 nd test pattern image 202A is displayed, defective pixels (dead or bright defects) are buried in the gray display and are difficult to be visually recognized.

In contrast, the inspection method of the display device 100 according to the embodiment of the present invention improves the visibility of defective pixels by alternately displaying the 1 st test pattern image 201A and the 2 nd test pattern image 202A. Fig. 4A shows a method of displaying a test pattern image when the lighting inspection of the display device 100 is performed. As shown in fig. 4A, the 1 st test pattern image 201A and the 2 nd test pattern image 202A are alternately displayed on the display portion 104 at a constant period T.

The frame frequency of the display device 100 is, for example, 60Hz or 120Hz. With respect to such a frame frequency, the period T in which the 1 st test pattern image 201A and the 2 nd test pattern image 202A are alternately displayed has a period longer than the period of 1 frame. Specifically, the period T is preferably 0.1 to 1 second, for example, 0.2 to 0.8 second. By displaying the 1 st test pattern image 201A and the 2 nd test pattern image 202A at such a period T, defective pixels are emphasized, and visibility is improved.

Fig. 5 is a diagram illustrating the reason why the defective pixel is emphasized. Fig. 5 shows a display state of the 1 st test pattern image 201A. In the display state of the 1 st test pattern image 201A, when attention is focused on the pixel PX22, the pixel PX24, the pixel PX42, and the pixel PX44, these pixels are pixels in a bright state, and the pixel PX23, the pixel PX32, the pixel PX34, and the pixel PX43 are pixels in a dark state. Here, the pixel PX33 is originally a pixel to be in a bright state, but is a defective pixel and therefore is a pixel that is not lit (is not in a bright state). In fig. 5, although SPXR, SPXG, and SPXB contained in PX33 are all in the dark state, only 1 or 2 of SPXR, SPXG, and SPXB are in the dark state and are also in the same defect state. When the 2 nd test pattern image 202A is displayed, the above-described bright state and dark state are reversed, and the same pattern as the display pattern shown in fig. 3 is displayed. Since the pixel PX33 is in a dark state, the 2 nd test pattern image 202A is not a defective pixel.

In fig. 5, when attention is paid to the periphery of the pixel PX33 which is a defective pixel, the pixels PX23, PX32, PX34, and PX43 are pixels in a dark state. Since the defective pixel PX33 is also a pixel in a dark state in appearance, the area of the 1 st test pattern image 201A where the periphery of the defective pixel PX33 deviates from the original light and dark periodic pattern, and the pixels PX23, PX32, PX33, PX34, and PX43 become clusters of pixels in a dark state and are displayed in black is locally increased. As a result, the black dots are highlighted on the entire display unit 104.

Then, the 1 st test pattern image 201A in which the black dots are emphasized and the normal 2 nd test pattern image 202A are alternately displayed in the period T, and thereby the black dots are displayed so as to blink on the display unit 104. That is, according to the inspection method shown in the present embodiment, the 1 st test pattern image 201A and the 2 nd test pattern image 202A are alternately displayed at the period T, so that the portion of the defective pixel becomes a black dot, and the black dot can be displayed so as to blink. Since the observer can visually recognize a dynamic state such as flickering of a black dot in an image displayed in gray, the observer can easily determine a defective pixel.

According to the inspection method of the present embodiment, since a defective pixel can be displayed in a moving image state, the attention of the observer can be called and the defective pixel can be easily found, as compared with the case where the defective pixel is inspected in a still image state displayed in full white, full black, or intermediate gradation. In other words, in the inspection method of the present embodiment, since a portion including a defective pixel in a display portion that appears monotonous flickers and is displayed in a highlighted manner, a stimulus can be given to the viewer's vision, and a place where a defective pixel exists can be easily found. The inspection method of the display device according to the present embodiment is effective when the pixels are highly refined, and can easily find defective pixels even when the fineness of the pixels is 300ppi or more, for example.

In the present embodiment, the case where the defective pixel is described as an example, but the bright point defective pixel can be highlighted by the same principle, and the bright point defective pixel can be easily found.

Although fig. 2 and 3 show examples in which the pixels PX are arranged in stripes, the inspection method according to the present embodiment is not limited to stripe arrangements, and can be applied to various pixel arrangements such as Bayer (Bayer) arrangements, penTile arrangements, and Diamond-PenTile arrangements. The pixel PX may include not only the sub-pixels corresponding to red (R), green (G), and blue (B), but also the sub-pixel corresponding to white (W) and the sub-pixel corresponding to yellow (Y).

[ 2 nd embodiment ]

The present embodiment shows a different mode of the test pattern image from the 1 st test pattern image 201A and the 2 nd test pattern image 202A shown in embodiment 1. In the following description, the differences from embodiment 1 will be mainly described.

Fig. 6 shows a 1 st test pattern image 201B according to this embodiment. In the 1 st test pattern image 201B, the pixels PX11, PX13, PX15, PX22, PX24, and PX26 are pixels that are displayed in a gray-scale (80 to 100% gray-scale) and become a bright state, and the pixels PX12, PX14, PX16, PX21, PX23, and PX25 are pixels that are displayed in a dark state (0 to 20% gray-scale). Here, the 1 st test pattern image 201B is different from the 1 st embodiment in the following respects: the bright-state pixel performs gray-scale display not for all of the sub-pixels SPXR, SPXG, and SPXB but for one sub-pixel.

Fig. 7 shows a 2 nd test pattern image 202B according to the present embodiment. The 2 nd test pattern image 202B represents an inverted pattern of the 1 st test pattern image 201B. In the 2 nd test pattern image 202B, the pixel PX11, the pixel PX13, the pixel PX15, the pixel PX22, the pixel PX24, and the pixel PX26 are pixels in a dark state, and the pixel PX12, the pixel PX14, the pixel PX16, the pixel PX21, the pixel PX23, and the pixel PX25 are pixels in a bright state.

As an example, fig. 6 and 7 show a case where the subpixel SPXR corresponding to red is displayed in gray scale. The gray scale display of the pixel PXjk is not limited to the subpixel SPXR corresponding to red, and may be a subpixel SPXG corresponding to green or a subpixel SPXB corresponding to blue.

In the 1 st test pattern image 201B and the 2 nd test pattern image 202B, by sequentially changing the subpixels for gray scale display, it is possible to check whether or not there is a defect in each of the subpixels corresponding to red (R), green (G), and blue (B). For example, the lighting inspection of the subpixel SPXR corresponding to red (R) may be performed for a certain time (a time sufficiently longer than the period T) by the 1 st test pattern image 201B and the 2 nd test pattern image 202B, the lighting inspection of the subpixel SPXG corresponding to green (G) may be performed for the next certain time, and the lighting inspection of the subpixel SPXB corresponding to blue (B) may be performed for the next certain time.

The 1 st test pattern image 201B and the 2 nd test pattern image 202B are alternately displayed with a period T while the inspection is performed. With such a display method, defective pixels that become defective dots and bright dots can be easily detected as in embodiment 1. Further, according to the present embodiment, the defective pixel can be inspected in units of the sub-pixel SPX. That is, while embodiment 1 is suitable for detecting defective pixels in pixel units, in the present embodiment, defective pixels can be detected in units of sub-pixels.

The inspection method described in this embodiment can be implemented in appropriate combination with the inspection method described in embodiment 1. That is, the inspection can be performed by combining the 1 st inspection period in which the 1 st test pattern image 201A and the 2 nd test pattern image 202B are alternately displayed with the period T and the 2 nd inspection period in which the 1 st test pattern image 201B and the 2 nd test pattern image 202B are alternately displayed with the period T. By such a combination, inspection can be performed in both pixel units and sub-pixel units, and missing detection of defective pixels can be avoided.

[ embodiment 3 ]

In embodiment 2, pixels in a dark state (0 to 20%) in which black display is substantially performed may be replaced with gray display (more than 20% gray scale and less than 80% gray scale). That is, in the 1 st test pattern image 201B shown in fig. 6, the pixel PX11, the pixel PX13, the pixel PX15, the pixel PX22, the pixel PX24, and the pixel PX26 may be pixels in a bright state for gray-scale display (80 to 100% gray scale), and the pixel PX12, the pixel PX14, the pixel PX16, the pixel PX21, the pixel PX23, and the pixel PX25 may be pixels for gray-scale display (more than 20% gray scale and less than 80% gray scale). The same applies to the 2 nd test pattern image 202B shown in fig. 7.

By replacing the pixel for performing black display with the pixel for performing gray display in this way, the detection accuracy of the defective pixel can be improved as in embodiment 2. Further, it is possible to suppress the flicker of the display section 104 when switching between the 1 st test pattern image 201B and the 2 nd test pattern image 202B. Further, by replacing the pixel for performing black display with the pixel for performing gray display, the pixel having the defective dead pixel can be made conspicuous, and missing detection of the defective pixel can be avoided.

[ 4 th embodiment ]

In embodiment 2, the pixel PXjk for gray-scale display (80 to 100% gray scale) is not for gray-scale display of all the subpixels SPXR, SPXG, and SPXB but for gray-scale display of one subpixel, but at least 2 subpixels may be gray-scale displayed instead. For example, yellow may be displayed by performing gray scale display on the sub-pixel SPXR corresponding to red (R) and the sub-pixel SPXG corresponding to green (G), cyan may be displayed by performing gray scale display on the sub-pixel SPXG corresponding to green (G) and the sub-pixel SPXB corresponding to blue (B), and magenta may be displayed by performing gray scale display on the sub-pixel SPXR corresponding to red (R) and the sub-pixel SPXB corresponding to blue (B). In this embodiment, a pixel for performing black display can be replaced with a pixel for performing gray display.

In this way, by displaying an intermediate color instead of the 3 primary colors of red (R), green (G), and blue (B), the detection accuracy of defective pixels can be improved similarly to embodiment 2.

[ 5 th embodiment ]

The 1 st test pattern image 201A and the 2 nd test pattern image 202A shown in embodiment 1 show other modes different from the test pattern image. In the following description, the differences from embodiment 1 will be mainly described.

Fig. 8 shows a 1 st test pattern image 201C according to the present embodiment. The 1 st unit area and the 2 nd unit area of the 1 st test pattern image 201C are composed of 2 pixels. In the example shown in fig. 8, the 1 st unit region is constituted by the pixel PX11 and the pixel PX21, and the 2 nd unit region is constituted by the pixel PX12 and the pixel PX 22.

Specifically, the 1 st test pattern image 201C is a pixel in a bright state where the pixel PX11, the pixel PX21, the pixel PX13, the pixel PX23, the pixel PX15, and the pixel PX25 are displayed in gray scale (80 to 100% gray scale), and the pixel PX12, the pixel PX22, the pixel PX14, the pixel PX24, the pixel PX16, and the pixel PX26 are in a dark state (0 to 20% gray scale). In addition, in the row from the pixel PX31 and the pixel PX41, the pixel PX31 and the pixel PX41 are pixels in a dark state (0 to 20% gray scale), and the pixel PX32 and the pixel PX42 are pixels in a bright state for gray scale display (80 to 100% gray scale), and display a gray scale pattern inverted from the above 2 row. As described above, the present embodiment is different from embodiment 1 in that a unit region is defined by a set of 2 lines, and a light and dark gray scale pattern is displayed.

Fig. 9 shows a 2 nd test pattern image 202C according to the present embodiment. The 2 nd test pattern image 202C represents the reverse pattern of the 1 st test pattern image 201C. In the 2 nd test pattern image 202B, the 1 st test pattern image 201C is a pixel in which the pixel PX11, the pixel PX21, the pixel PX13, the pixel PX23, the pixel PX15, and the pixel PX25 are in a dark state (0 to 20% gray scale), and the pixel PX12, the pixel PX22, the pixel PX14, the pixel PX24, the pixel PX16, and the pixel PX26 are in a bright state in which gray scale display (80 to 100% gray scale) is performed. In the row from the pixel PX31 and the pixel PX41, the pixel PX31 and the pixel PX41 are pixels in a bright state for gray-scale display (80 to 100% gray scale), and the pixel PX32 and the pixel PX42 are pixels in a dark state, and a gray-scale pattern inverted from the above 2 rows is displayed.

In this way, by forming a test pattern in which a block inspection (or a checkered pattern) is formed by a set of 2 lines, it is possible to similarly inspect a defective pixel. When the display unit 104 has a small size of 1 pixel due to high definition, it is difficult to visually recognize a defective pixel in a unit of 1 dot (1 pixel), but as shown in this embodiment, a test pattern image by block inspection (also referred to as a checkered pattern) is formed using a plurality of lines, whereby a defective pixel can be easily found.

In the present embodiment, as in embodiment 1, the 1 st test pattern image 201C and the 2 nd test pattern image 202C are alternately displayed at a predetermined period T, whereby defective pixels can be emphasized and visibility can be improved.

Fig. 8 and 9 show test pattern images based on block inspection (also referred to as checkering) in a set of 2 lines, but the present invention is not limited to this example, and test pattern images based on block inspection (also referred to as checkering) may be generated in a set of more lines (e.g., 3 lines, 4 lines). Further, instead of the row direction, a test pattern image by block inspection (also referred to as a checkerboard pattern) may be generated by grouping a plurality of rows. Further, a test pattern image based on the block check pattern (also referred to as a checkered pattern) may be formed by grouping n rows and m columns.

The 1 st test pattern image 201C and the 2 nd test pattern image 202C in a group of a plurality of rows (or a plurality of columns) in the present embodiment can be implemented in appropriate combination with the embodiments 2 to 4.

[ 6 th embodiment ]

In the present embodiment, another example of a driving method when a test pattern image is displayed in a lighting test of the display device 100 is shown, which is different from the driving method shown in embodiment 1.

Fig. 4B shows a method of displaying a test pattern image when the lighting inspection of the display device 100 according to the present embodiment is performed. As shown in fig. 4B, the display period of the 3 rd test pattern image is inserted after the display period of the 1 st test pattern image and before the display period of the 2 nd test pattern image. Although not shown in fig. 4B, the 3 rd test pattern image may be inserted after the display period of the 2 nd test pattern image and before the display period of the 1 st test pattern image. The images shown in embodiments 1 to 5 are applied to the 1 st test pattern image and the 2 nd test pattern image.

In the 3 rd test pattern image, all the pixels PXjk of the display portion 104 are displayed at a gray scale value intermediate between the gray scale of the bright state (80 to 100% gray scale) and the gray scale of the dark state (0 to 20% gray scale). The 3 rd test pattern image is preferably a raster image having a gray scale of 60 to 80%. As shown in fig. 4B, by inserting a gray-displayed raster image between the 1 st test pattern image and the 2 nd test pattern image of the block inspection (also referred to as checkering) pattern displaying 1 pixel, it is possible to suppress flicker on the screen and improve visibility of defective pixels.

[ 7 th embodiment ]

This embodiment mode shows an example of a configuration of an inspection system to which the inspection method of a display device according to one embodiment of the present invention is applied.

Fig. 10 shows an inspection system 150 of a display device according to the present embodiment. Inspection system 150 includes control circuitry 152, test pattern image generation circuitry 154, display device drive circuitry 156, camera 158, image processing circuitry 160, storage device 162, input 164, and output 166. The control circuit 152 controls the operations of the respective sections based on a predetermined program. The program is stored in the storage device 162 and is read into the control circuit 152 when the inspection system 150 is started. Data for generating a test pattern image is also stored in the storage device 162. The output unit 166 is configured by a display panel or the like, and displays an operation screen for operating the inspection system. The input section 164 is constituted by a keyboard, a pointing device, a touch panel, and the like, and is used for checking the operation of the system 150.

By the control of the control circuit 152, the test pattern image generation circuit 154 generates the 2 nd test pattern image and the 2 nd test pattern image shown in embodiments 1 to 6, and outputs them to the display device drive circuit 156. The display device 100 is driven by the display device driving circuit 156, and a test pattern image is displayed on the display section 104.

The camera 158 captures a test pattern image displayed on the display section 104, and outputs its captured data to the image processing circuit 160. The image processing circuit 160 analyzes the image data captured by the camera 158 to determine the presence or absence of a defective pixel. For example, if there is a portion where an inspection pattern having a shape different from that of another region is generated in a blinking state in the captured data, it is determined that a defect exists in the portion. The image display device driving circuit 156 outputs information about the defective pixel to the control circuit 152. The information on the defective pixel may include information (bitmap data) on the total number of defective pixels, the number of adjacent defective pixels, and the position of the defective pixel. The control circuit 152 causes the output section 166 to display information about the defective pixel.

As described above, according to the inspection system 150 of the present embodiment, the lighting inspection is performed by using the test pattern images and the display method thereof shown in embodiments 1 to 6, and thus the defective pixel inspection with high accuracy can be performed.

Claims (10)

1. An inspection method of a display device, characterized in that:

the method includes the steps of alternately displaying a 1 st test pattern image and a 2 nd test pattern image over the entire display portion at a constant period, and inspecting whether or not defective pixels exist, wherein the 1 st test pattern image is periodically provided with a 1 st unit region displayed at a 1 st gray scale value and a 2 nd unit region adjacent to the 1 st unit region and displayed at a 2 nd gray scale value different from the 1 st gray scale value, the 2 nd test pattern image displays the 1 st unit region at the 2 nd gray scale value and the 2 nd unit region at the 1 st gray scale value,

the 1 st unit region and the 2 nd unit region are 1 pixel, respectively.

2. The inspection method of a display device according to claim 1, characterized in that:

the certain period is in the range of 0.2 to 0.8 seconds.

3. The inspection method of a display device according to claim 1, wherein:

the 1 st unit region and the 2 nd unit region are respectively configured by a plurality of pixels adjacent to each other.

4. The inspection method of a display device according to claim 1, wherein:

the 1 st gray scale value is a gray scale value representing white, and the 2 nd gray scale value is a gray scale value representing black.

5. The inspection method of a display device according to claim 1, wherein:

the 1 st gray scale value is a gray scale value representing any one color of red, green and blue, and the 2 nd gray scale value is a gray scale value representing black or gray having a gray scale lower than the 1 st gray scale value.

6. The inspection method of a display device according to claim 1, wherein:

the 1 st gray scale value is a gray scale value indicating an intermediate color of any two colors of red, green, and blue, and the 2 nd gray scale value is a gray scale value indicating black or gray having a gray scale lower than the 1 st gray scale value.

7. The inspection method of a display device according to claim 4, characterized in that:

the 1 st gray scale value has a gray scale of 80-100%, and the 2 nd gray scale value has a gray scale of 0-20%.

8. The inspection method of a display device according to claim 1, characterized in that:

a display of a 3 rd test pattern image in which all pixels have a gray scale value intermediate between the 1 st gray scale value and the 2 nd gray scale value is inserted between the 1 st test pattern image and the 2 nd test pattern image.

9. The inspection method of a display device according to claim 8, wherein:

the 3 rd test pattern image is a grating image having a gray scale of 60 to 80%.

10. The inspection method of a display device according to claim 1, characterized in that:

the pixel density of the display part is more than 300 ppi.

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