LCD panel inspection apparatus and inspection method

Abstract

The objective is to improve the reliability of LCD panel inspection. [Solution] The inspection device 10 comprises a stand 28 for setting the liquid crystal panel 30 to be inspected, a plurality of local linear actuators 24 arranged in a direction perpendicular to the screen of the liquid crystal panel set on the stand and distributed along the periphery of the liquid crystal panel, a whole linear actuator 25 arranged in a direction parallel to the screen of the liquid crystal panel and provided on the side of the liquid crystal panel, a plurality of cameras 21-24 for capturing images of the display screen of the liquid crystal panel, and a determination unit 11 for determining whether or not there are defects in the liquid crystal panel based on a series of images captured by the cameras.

Description

Technical Field

[0001] The present disclosure relates to an inspection apparatus and an inspection method for a liquid crystal panel.

Background Art

[0002] There are the following problems in the inspection of liquid crystal panels. Fine defects (such as dot chipping, bright dots, and unevenness) are difficult to see and may be overlooked by the human eye. Visual inspection depends on the concentration of the inspector, so mistakes are likely to occur due to fatigue and reduced attention, and variation in evaluation among inspectors also becomes a problem.

[0003] Furthermore, defects may be hidden. A structure in which an IC chip directly mounted on a flexible film is pressure-bonded and connected to a liquid crystal glass substrate is advantageous for thinning and narrow bordering, and is thus adopted in many liquid crystal panels (COF (Chip On Film)). The IC chip is an important component responsible for the electronic circuit for driving the liquid crystal panel, and converts video signals (digital data) sent from the outside (such as smartphones, TVs, and personal computers) into necessary voltage signals, and also has a function of controlling the display timing of millions of pixels.

[0004] If there is a connection failure in the COF, vertical or horizontal line-like noise (stripe noise) appears on the screen. The stripe noise due to the connection failure of the COF does not manifest in a static state, and may appear only when physical pressure is applied from a specific direction from the outside, so it is difficult to detect and the reliability of inspection is low.

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object is to improve the reliability of inspection of a liquid crystal panel.

Means for Solving the Problems

[0006] An inspection apparatus for a liquid crystal panel according to an embodiment of the present invention includes a stand for setting the liquid crystal panel to be inspected, and is arranged in a direction perpendicular to the stroke direction of the screen of the liquid crystal panel set on the stand, and is distributed along the peripheral edge of the liquid crystal panel. To vibrate and press the periphery of the LCD panel from the front Multiple first actuators are arranged in a direction parallel to the stroke direction of the LCD panel screen set on the frame, and are provided on the side of the LCD panel. to vibrate and press the side of the LCD panel from the side. The system comprises a second actuator, multiple cameras for capturing images of the liquid crystal panel's display screen, and a determination unit for determining whether or not there are defects in the liquid crystal panel based on a series of images captured by the cameras. [Brief explanation of the drawing]

[0007] [Figure 1] A diagram showing the configuration of a liquid crystal panel inspection apparatus according to an embodiment of the present invention. [Figure 2] Figure 1 is a perspective view from the front right showing the two linear actuator systems and three cameras along with their mounts. [Figure 3] Figure 1 is a perspective view from the front left showing the two linear actuator systems and three cameras along with their mounts. [Figure 4] Figure 2 is a perspective view showing the LCD panel to be inspected mounted on the stand. [Figure 5] A flowchart illustrating the inspection procedure for a liquid crystal panel according to an embodiment of the present invention. [Figure 6] Figure 5 shows an example of a test chart displayed on the liquid crystal panel in step S17. [Figure 7] This diagram shows the inspection operation when the liquid crystal panel is 2D type in this embodiment. [Figure 8] This diagram shows the inspection operation when the liquid crystal panel is 3D in this embodiment. [Figure 9] Figure 5 shows an example of the inspection result display screen in process S24. [Modes for carrying out the invention]

[0008] Embodiments of the present invention will be described below with reference to the drawings. The liquid crystal panel inspection apparatus according to this embodiment inspects for defects in the liquid crystal panel. Examples of inspection items here include dead pixels, backlight abnormalities, and the presence or absence of stripe noise caused by poor COF (Chip On Film) connection.

[0009] As shown in Figure 1, the inspection device 1 has a processor 11. The processor 11 is connected via a data / control bus 19 to a storage device 14 such as RAM (Random Access Memory) 12, ROM (Read Only Memory) 13, HDD (Hard Disk Drive) or SSD (Solid State Drive), an input device 15 such as a keyboard or mouse, a display 16, and a video controller 18. The liquid crystal panel 30 to be inspected is connected to the video controller 18 via a connector 26. The video controller 18 supplies a video signal to the liquid crystal panel 30 to uniformly display, for example, gray as a halftone as a test chart, across the entire screen of the liquid crystal panel 30.

[0010] Furthermore, the processor 11 is connected via an interface (I / F) 17 to a plurality of cameras 21-23 (in this case, 3), a plurality of local linear actuators (first actuators) 24 (in this case, 16), and a global linear actuator (second actuator) 25, each via drivers not shown. Camera 21 faces the center of the front of the liquid crystal panel 30 and is referred to as the front camera. Camera 22 is a left-front camera positioned diagonally to the left front of the liquid crystal panel 30, facing the center of the liquid crystal panel 30. Camera 23 is a right-front camera positioned diagonally to the right front of the liquid crystal panel 30, facing the center of the liquid crystal panel 30.

[0011] Furthermore, while the local linear actuator 24 and the overall linear actuator 25 illustrate a method of converting the rotational motion of an electric motor into linear motion, the system is not limited to this. It may also be a method of directly outputting the linear motion of a linear motor to the liquid crystal panel 30, or a method of directly outputting the rotational motion of an electric motor, or even pneumatic, hydraulic, or other energy sources.

[0012] As shown in Figures 2, 3, and 4, the stand 28 of the inspection device 1 has a frame structure into which a liquid crystal panel 30 of a specified size to be inspected is inserted from above. The frame structure is assembled so that the entire surface of the liquid crystal panel 30 is exposed while holding down its back surface. Furthermore, the frame structure is assembled so that the portion of the frame facing the contact portion (pusher) of the 16 local linear actuators 24, which are distributed along the periphery of the liquid crystal panel 30, is exposed and holds down with the minimum amount necessary to prevent it from tipping forward.

[0013] The localized linear actuators 24 are supported on the frame 28 such that their stroke direction is perpendicular to the screen of the liquid crystal panel 30 set on the frame 28, and 16 actuators are distributed along the periphery of the liquid crystal panel 30, with four actuators on each side. The pushers of the 16 localized linear actuators 24 press vertically from the front at different local locations on the periphery of the liquid crystal panel 30. The COF on which the driver IC is mounted is connected to the liquid crystal glass substrate (TFT substrate) at multiple locations on the periphery of the liquid crystal panel 30. The number and location of these connection points between the COF and the liquid crystal glass substrate vary depending on the product specifications, but they generally correspond to the pressing locations of all 16 localized linear actuators 24, or 4, 6, 8, etc. For the inspection, the user can arbitrarily set in advance, depending on the number and location of connection points, all 16 local linear actuators 24, or a combination of several local linear actuators 24 that will actually be driven from among them.

[0014] The overall linear actuator 25 is supported on the frame 28 such that its stroke direction is parallel to the screen of the liquid crystal panel 30 set on the frame 28, and it is positioned on the side of the liquid crystal panel 30. The pusher of the overall linear actuator 25 presses the liquid crystal panel 30 from the side. The overall linear actuator 25 has a larger output characteristic than the local linear actuator 24. A dispersion plate 27 is interposed between the pusher of the overall linear actuator 25 and the side of the liquid crystal panel 30. The dispersion plate 27 distributes the pressing force of the overall linear actuator 25 across the entire side of the liquid crystal panel 30. As a result, the entire liquid crystal panel 30 is pressed from the side.

[0015] Figure 5 shows the procedure for the inspection operation by the inspection device 1. In Figure 5, the dashed lines indicate the work process performed by the inspection worker. The inspection worker mounts the LCD panel 30 to be inspected onto the stand 28, and connects the video controller 18 via the connector 26 (S11).

[0016] In step S12, the inspector selects via the input device 15 whether the liquid crystal panel 30 to be inspected is a two-dimensional (2D) type that displays images in a flat plane, or a three-dimensional (3D) type that allows for naked-eye stereoscopic viewing by displaying images at different angles to the left and right eyes, eliminating the need for glasses or a headset. The inspector also sets, via the input device 15, all or some combinations of local linear actuators 24 that will actually be driven for inspection as inspection conditions, according to the number and location of connection points between the COF and the liquid crystal glass substrate in the specifications of the liquid crystal panel 30 to be inspected.

[0017] For the purposes of this explanation, we will assume that four of the 16 local linear actuators 24—two local linear actuators 24(R1) and 24(R3) located on the right side, and two local linear actuators 24(D1) and 24(D3) located on the lower side—are actually set to be driven for testing purposes.

[0018] The processor 11 waits for an operation (press) of an inspection switch (not shown) by an inspection operator (S13). When the inspection switch is turned on by the inspection operator (S13; Yes), a test chart video signal is supplied from the video controller 18 to the liquid crystal panel 30 according to the control of the processor 11, and accordingly, the test chart 32 is displayed on the liquid crystal panel 30 as illustrated in FIG. 6 (S14).

[0019] When the liquid crystal panel 30 selected in step S12 is of the 2D type (step S15, Yes (2D type)), the front camera 21 among the cameras 21 - 23 is selectively activated by the control of the processor 11, and imaging from the front is started (S16). When it is of the 3D type (step S15, No (3D type)), all of the cameras 21 - 23 are activated by the control of the processor 11, and imaging from three directions is started (S17).

[0020] FIG. 7 shows the inspection operation when the liquid crystal panel 30 is of the 2D type, and FIG. 8 shows the inspection operation when the liquid crystal panel 30 is of the 3D type. As shown in FIG. 7, by the processor 11, from the video imaged by the front camera 21, the video portion imaged in a predetermined period after the test chart is displayed and before the vibration and pressing operations by the linear actuators 24 and 25 are started is extracted. For each of a series of images constituting the video portion, a reference image without dot missing is differentiated, and the presence or absence of dot missing is determined based on each of these plurality of differentiated images (S18). By the processor 11, if a differentiated value corresponding to dot missing remains in at least one of the plurality of differentiated images, it is determined that dot missing has occurred in the liquid crystal panel 30. If no differentiated value corresponding to dot missing remains in all of the plurality of differentiated images, it is determined that no dot missing has occurred in the liquid crystal panel 30.

[0021] Furthermore, in step S18, the processor 11 individually calculates the brightness for all pixels or for a predetermined local area within each of the series of images constituting the video portion captured during the predetermined period, checks against a predetermined reference brightness range, and determines that there is a brightness abnormality, i.e., a backlight abnormality, if there is one or a predetermined number or more pixels or local areas outside the reference brightness range, and determines that there is no brightness normal, i.e., no backlight abnormality, if there are no pixels or local areas outside the reference brightness range, or if the number is less than the predetermined number.

[0022] When the LCD panel 30 is a 3D type, as shown in Figure 8, the processor 11 uses the image portion extracted from the images captured by the front camera 21, the left front camera 22, and the right front camera 23 to determine whether there are any dead pixels or backlight abnormalities, as described above.

[0023] Next, under the control of the processor 11, the four local linear actuators 24(R1), 24(R3), 24(D1), and 24(D3) specified in step S12 vibrate continuously for a predetermined time, followed by a pressing operation that continues for a predetermined time (S19). Consequently, the peripheral edge of the liquid crystal panel 30 vibrates and is also partially pressed.

[0024] During the period in which vibration and pressing continue, the captured image portion is extracted, and a detection process is performed on each of the series of images constituting the captured image portion to check for the presence or absence of vertical and horizontal stripe noise (vertical and horizontal striped noise) (S20). When the liquid crystal panel 30 is a 2D type, as shown in Figure 7, the detection process for the presence or absence of vertical and horizontal stripe noise is performed using the image portion extracted from the image captured by the front camera 21. When the liquid crystal panel 30 is a 3D type, as shown in Figure 8, the detection process for the presence or absence of vertical and horizontal stripe noise is performed using the image portions extracted from the images captured by the front camera 21, the left front camera 22, and the right front camera 23, respectively.

[0025] Next, under the control of the processor 11, the overall linear actuator 25 vibrates for a predetermined time, followed by a pressing operation that continues for a predetermined time (S21). Consequently, the liquid crystal panel 30 vibrates as a whole and is also pressed from the sides as a whole. During the period in which the vibration and pressing continue, a detection process for the presence or absence of vertical and horizontal stripe noise is performed, similar to step S20 (S22).

[0026] The display of the test chart by the liquid crystal panel 30 and the imaging by cameras 21-23 are stopped (step S23). In the next step S24, the processor 11 creates a display screen of the judgment results and displays it on the display 16. As shown in Figure 9, the judgment results for the presence or absence of vertical lines (vertical stripe noise), horizontal lines (horizontal stripe noise), scratches (dead pixels), and brightness abnormalities (backlight abnormalities) are all combined on one screen along with the overall judgment result. It is also possible to display in more detail where the vertical / horizontal lines appear.

[0027] According to this embodiment, the reliability of inspection of liquid crystal panels can be improved. Specifically, the connection point between the COF on which the driver IC is mounted and the liquid crystal glass substrate (TFT substrate) at the peripheral edge of the liquid crystal panel 30 is vibrated and pressed locally by the local linear actuator 24 and overall by the overall linear actuator 25, so that COF connection failures can be detected with high reliability. Furthermore, since vibration and pressing are applied from the front by the local linear actuator 24 and from the side by the overall linear actuator 25, and vibration and pressing from two directions are applied in a time-division manner, COF connection failures can be detected with high accuracy.

[0028] It should be noted that the embodiments are not limited to those described above, and various modifications can be made during implementation without departing from the gist of the invention. Furthermore, each embodiment may be combined as appropriate, and in that case, the combined effects can be obtained. Moreover, the embodiments described above include various inventions, and various inventions can be extracted by selecting combinations from the multiple constituent elements disclosed. For example, if the problem can be solved and effects obtained even if some constituent elements are deleted from all the constituent elements shown in the embodiment, then the configuration with these deleted constituent elements can be extracted as an invention. [Explanation of Symbols]

[0029] 1...Inspection device, 11...Processor, 12...RAM, 13...ROM, 14...Storage device, 15...Input device, 16...Display, 17...Interface (I / F), 18...Video controller, 19...Data / control bus, 21...Front camera, 22...Left front camera, 23...Right front camera, 24...Local linear actuator, 25...Overall linear actuator.

Claims

1. A stand for setting the LCD panel to be inspected, A plurality of first actuators are provided, arranged in a direction perpendicular to the stroke direction of the screen of the liquid crystal panel set on the aforementioned frame, distributed along the periphery of the liquid crystal panel, and vibrate and press the periphery of the liquid crystal panel from the front. A second actuator is positioned on the side of the liquid crystal panel, with the stroke direction parallel to the screen of the liquid crystal panel set on the aforementioned frame, and is provided to vibrate and press the side of the liquid crystal panel from the side. Multiple cameras for capturing images of the display screen of the aforementioned liquid crystal panel, An inspection apparatus comprising: a determination unit that determines whether or not there are defects in the liquid crystal panel based on a series of images captured by the camera.

2. The inspection apparatus according to claim 1, wherein the plurality of first actuators operate in combination according to user instructions.

3. The inspection apparatus according to claim 1, further comprising a display unit for displaying a predetermined test chart on the liquid crystal panel.

4. The first actuator and the second actuator operate in a time-division manner. The inspection apparatus according to claim 1, wherein the determination unit determines the presence or absence of stripe noise in the liquid crystal panel by separately using a series of images captured by the camera during the operation of the first actuator and a series of images captured by the camera during the operation of the second actuator.

5. The inspection apparatus according to claim 4, wherein the determination unit determines whether or not there are dead pixels in the liquid crystal panel and whether or not there are backlight abnormalities based on a series of images captured by the camera before the operation of the first and second actuators.

6. The inspection apparatus according to claim 1, wherein the plurality of cameras include a front camera positioned in front of the liquid crystal panel, a right front camera positioned diagonally to the right front of the liquid crystal panel and facing the center of the liquid crystal panel, and a left front camera positioned diagonally to the left front of the liquid crystal panel and facing the center of the liquid crystal panel.

7. The inspection apparatus according to claim 6, wherein the determination unit determines whether the liquid crystal panel has defects based on a series of images captured by the front camera when the liquid crystal panel is a 2D liquid crystal panel that performs two-dimensional display, and determines whether the liquid crystal panel has defects based on a series of images captured by the front camera, a series of images captured by the right front camera, and a series of images captured by the left front camera when the liquid crystal panel is a 3D liquid crystal panel that supports stereoscopic viewing.

8. The inspection apparatus according to claim 1, further comprising a dispersion plate for distributing the pressing force of the second actuator across the entire side surface of the liquid crystal panel.

9. A process of displaying a predetermined test chart on the LCD panel to be inspected, The steps include: starting to take images of the display screen of the liquid crystal panel using a camera, The process involves, after the camera starts imaging, driving a plurality of first actuators to vibrate and press the peripheral edge of the liquid crystal panel from the front, A step of determining whether or not there is stripe noise in the liquid crystal panel based on a series of images captured by the camera during the operation of the first actuator, The process involves, after the operation of the first actuator, driving a second actuator to vibrate and press the side of the liquid crystal panel from the side, An inspection method comprising the step of determining whether or not there is stripe noise in the liquid crystal panel based on a series of images captured by the camera during the operation of the second actuator.

Images