JP2010145558A - Method and device for inspecting liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and device for accurately detecting defective product by uniformly pressing the whole image display surface of a liquid crystal display device. <P>SOLUTION: In the method and device for inspecting the liquid crystal display device 3, an image displayed on the image display surface 31 of the liquid crystal display device 3 is captured while pressing the image display surface 31 by a pressing part 8 having a plurality of roller 61 installed thereto alternately so that the track of each roller 61 overlaps the track of the other roller 61, and the captured image is compared with a reference image captured before the pressing start to determine the quality of the liquid crystal display device 3. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for accurately detecting a short circuit between opposing substrates of a transmissive liquid crystal display device and a transflective liquid crystal display device, and an inspection device therefor.

In general, a liquid crystal display device is configured by sandwiching a liquid crystal between electrodes of a glass substrate facing each other. A voltage is applied to the liquid crystal as an image display command signal to control the direction of liquid crystal molecules, and from the outside. The image is displayed using the incident light and the color filter.
In such a liquid crystal display device, defective products may occur in the manufacturing process. For example, a metal foreign substance may be mixed between the electrodes of the opposing glass substrate or there may be an etching failure of the electrodes.
When these foreign substances come into contact with both electrodes and are short-circuited, a point that always lights up or a line defect is generated on the liquid crystal display surface. The occurrence of this short circuit is affected by the shape and size of the foreign matter, the deflection of the image display surface, and the like.
Conventionally, in the short-circuit defect inspection process, the defect is detected by pressing the image display surface and narrowing the space between the counter electrodes to make the short circuit obvious.
For example, a liquid crystal display surface is pressed by a horizontally long cylindrical roller for attaching a polarizing plate to detect a short circuit (Patent Document 1), or an inspection pressing tool equipped with a constant load spring is applied with a substantially constant load. An inspection tool (Patent Document 2) that presses the liquid crystal display device is proposed.

JP-A-10-232378 (paragraphs 0015-0016) JP 2003-228297 A (paragraphs 0024-0041)

However, since all of the conventional techniques use a single roller as a pressing tool, a portion that comes into contact when pressed is linear.
Further, since the liquid crystal display device is fixed to the examination table by gripping its four sides, when the image display surface is pressed with a roller, the outer side is less likely to bend than the inner side and is more likely to bend toward the center.
Since the contact surface of the roller is a straight line, a large pressing force is applied to both ends of the roller.
As described above, the conventional pressing tool has a problem that the entire image display surface of the liquid crystal display device cannot be pressed uniformly and the entire display surface cannot be inspected uniformly and accurately.

  The present invention has been made to solve the above-described problem, and an object of the present invention is to provide a method for accurately detecting a defective product by uniformly pressing the entire display surface of a liquid crystal display device and an inspection device therefor. And

An inspection apparatus for a liquid crystal display device according to the present invention comprises:
In an inspection apparatus for detecting a short circuit between electrodes by pressing an image display surface of a liquid crystal display device that sandwiches liquid crystal between electrodes provided on opposing glass substrates,
An inspection table for fixing the liquid crystal display device;
A signal input means for inputting a test drive signal to the electrode terminal of the liquid crystal display device;
A plurality of rollers for pressing the image display surface;
A roller drive control mechanism for moving a plurality of rollers in a staggered manner so that the trajectory of each roller at the time of pressing overlaps the trajectory of other rollers;
A photographing mechanism for photographing an image on the image display surface;
And a pass / fail judgment unit for judging the display quality of the liquid crystal display device from the image.

In an inspection method for detecting a short circuit between electrodes by pressing an image display surface of a liquid crystal display device sandwiching liquid crystal between electrodes provided on opposing glass substrates,
Fixing the liquid crystal display device to the examination table;
Inputting a driving signal for inspection to the electrode terminal of the liquid crystal display device;
Shooting an image on the image display surface while pressing the image display surface with a pressing unit alternately attached to the rollers so that the trajectory of each roller overlaps the trajectory of the other rollers;
And determining whether or not the display quality of the liquid crystal display device is good from the image.

An inspection apparatus for a liquid crystal display device according to the present invention comprises:
An inspection table for fixing the liquid crystal display device;
A signal input means for inputting a test drive signal to the electrode terminal of the liquid crystal display device;
A plurality of rollers for pressing the image display surface;
A roller drive control mechanism that moves a plurality of rollers in a staggered manner so that the trajectory of each roller at the time of pressing overlaps the trajectory of other rollers;
A photographing mechanism for photographing an image on the image display surface;
Since it has a pass / fail judgment unit that judges the display quality of the liquid crystal display device from the image,
The entire image display surface of the liquid crystal display device can be pressed uniformly, and the entire image display surface can be inspected with high accuracy.

In addition, the inspection method of the liquid crystal display device according to the present invention includes:
Fixing the liquid crystal display device to the examination table;
Inputting a driving signal for inspection to the electrode terminal of the liquid crystal display device;
Shooting an image on the image display surface while pressing the image display surface with a pressing unit alternately attached to the rollers so that the trajectory of each roller overlaps the trajectory of the other rollers;
And the step of judging the quality of the display quality of the liquid crystal display device from the image,
The entire image display surface of the liquid crystal display device can be pressed uniformly, and the entire image display surface can be inspected with high accuracy.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an inspection apparatus 1 (hereinafter referred to as inspection apparatus 1) for a liquid crystal display device according to Embodiment 1 of the present invention, and is a view of the entire inspection apparatus 1 viewed from the side.
FIG. 2 is a plan view of the inspection apparatus 1.
FIG. 3 is a cross-sectional view of the liquid crystal display device 3 that is an object to be inspected by the inspection device 1.

Before describing the specific structure of the inspection apparatus 1, an example of a defect of the liquid crystal display device 3 to be detected by the inspection apparatus 1 will be described.
As shown in FIG. 3, in the case of the liquid crystal display device 3 to which a TFT is added, a counter electrode 103 is provided on one glass substrate 102, and a source or gate line 106 and a pixel electrode 107 are provided on the other glass substrate 105. Patterned. A liquid crystal material 104 is filled between these members.
The dust 101 is a substance that causes trouble. For example, delamination generated in the patterning process or dust entering from the outside. If this simultaneously contacts the upper and lower electrodes, the liquid crystal display device 3 will display unexpectedly.

As shown in FIG. 3, even if the dust 101 is not in contact with both electrodes at the same time, it may move in the liquid crystal material 104 and cause a short circuit. The inspection apparatus 1 is for accurately detecting such a potential defective portion.
In order to detect a potential defective portion, the glass substrate 102 may be pressed with a pressing tool. The short circuit is intentionally made obvious. Since the glass substrate is somewhat elastic, it bends downward when pressed from above. Then, the counter electrode 103 also bends and pushes the liquid crystal material 104, contacts the dust 101, and a short circuit occurs. Then, the light of the backlight is transmitted through the portion of the liquid crystal display device 3 so that it can be known that the cause of the defect exists at that location.

Next, an inspection table 4 on which the liquid crystal display device 3 to be inspected is placed is installed on the backlight unit 2 for explaining a schematic configuration of the inspection device 1. The inspection table 4 is connected to a liquid crystal driving device 5, and the liquid crystal driving device 5 is connected to a control computer 30 that controls the entire inspection device 1.
The inspection table 4 includes connectors for transmitting a video signal from the liquid crystal driving device 5 to the liquid crystal display device 3.

The liquid crystal driving device 5 turns on / off the inspection signal of the liquid crystal display device 3 to be inspected according to a command from the control computer 30. This signal is input to the electrode terminal of the liquid crystal display device 3 via the inspection table 4, and the liquid crystal display device 3 is in a driving state.
The backlight unit 2 emits light upward from the lower surface of the liquid crystal display device 3, and observes a situation where this light passes through the liquid crystal display device 3, so that the voltage applied between the electrodes of the liquid crystal display device 3 Thus, it is possible to know whether or not the orientation of the liquid crystal molecules is correctly changed, and the display quality of the liquid crystal display device 3 can be confirmed.
In the present embodiment, the liquid crystal driving device 5 and the liquid crystal display device 3 are connected via the inspection table 4, but a configuration in which they are directly connected without using the inspection table 3 may be used.

A pressing unit 8 including a plurality of rollers 61 that presses the image display surface of the liquid crystal display device 3 is connected to a Z-axis robot 10 that moves it up and down, and the Z-axis robot 10 moves it left and right. The X-axis robot 11 is connected to a Y-axis robot 12 that moves the X-axis robot 11 from the front to the back.
FIG. 4 is a system configuration diagram showing a control system of the inspection apparatus 1.
The X, Y, and Z axis robots are connected to an X axis, Y axis, and Z axis controller 28, respectively, and each axis controller 28 is connected to a control unit 21 of a control computer 30 to constitute a roller drive control mechanism.

Thereby, based on the instruction | command from the control computer 30, the press part 8 can be moved to arbitrary places and can be pressed by arbitrary pressing force. The plurality of CCD cameras 15 take images of the image display surface 31 of the liquid crystal display device 3 on the inspection table 4. Since the CCD camera 15 is also connected to the XYZ axis controllers, the image display surface 31 can be photographed in accordance with the movement of each axis robot.
The photographed image is judged pass / fail by the pass / fail judgment unit 27 of the control computer 30, and at the same time, an inspection log is stored.

Below, the detail of the press part 8 of the inspection apparatus 1 is demonstrated.
FIG. 5 is a side view of the pressing unit 8 in a state where the roller unit 6 that presses the image display surface 31 of the liquid crystal display device 3 is attached to the roller unit support member 7.
FIG. 6 is a front view of the pressing unit 8 (a view of the pressing unit 8 viewed from the Y-axis robot side).
The roller unit 6 that presses the image display surface 31 from the upper surface includes a roller 61, a roller support member 62 that supports the roller 61, a cushion expansion / contraction member 63 attached to the outer periphery of the roller support member 62, and a roller support member 62 and an air cylinder 64 connected to the telescopic member 63. The air cylinder 64 can be expanded and contracted by compressed air, and the amount of expansion and contraction can be controlled in units of individual roller units 6. This role will be described later.

As shown in FIG. 1, the roller units 6 are arranged in two right and left rows when the inspection apparatus 1 is viewed from the side. As shown in FIGS. 2 and 6, the rollers 61 in each row are staggered so that when each roller 61 moves to the left and right, the respective trajectory overlaps the trajectory passed by the roller 61 in the adjacent row. Has been placed.
With this structure, the entire image display surface 31 can be pressed by the rollers 61 only by moving the pressing portion 8 once from the right end to the left end of the image display surface 31.

The pressing unit 8 is moved up and down by the Z-axis robot 10, and the pressing force on the image display surface 31 of the liquid crystal display device 3 can be changed by changing the height of the pressing unit 8. In this case, the pressing force of all the rollers changes.
FIG. 7 is a cross-sectional view of the roller and the image display device when the image display surface is pressed by the roller in the conventional inspection device. Since the position a is the end of the glass substrate and the four sides around the liquid crystal display device are fixed, the vicinity of the end does not bend much. When this is pressed by a long roller, the whole is bent as shown in FIG. 7, and the central portion cannot be pressed.

However, since there are a plurality of rollers 61 according to the present embodiment and the elastic member 63 is further attached, even if the method of bending the image display surface 31 of the liquid crystal display device 3 varies depending on the location at the time of pressing, There is no effect on pressing.
Further, an air cylinder 64 is attached to the roller unit 6, and the height of each roller unit 6 can be controlled by expanding and contracting the cylinder 64.

The fact that the height of the roller unit 6 can be individually controlled means that the pressing force applied to the roller unit 6 can be changed for each unit. When this function is used, the roller 61 that presses the vicinity of the end of the image display surface 31 and the height of the roller 61 that presses near the center are changed stepwise, and all the roller units 6 are attached. By pressing the unit support member 7 with a Z-axis robot, it is possible to correct the force to press all the places on the image display surface 31 as a result.
On the other hand, it is possible to inspect by pressing the place where the vicinity of the four sides is difficult to bend more strongly, and fine pressing conditions can be set.

FIG. 8 is a flowchart showing an outline of the inspection.
The inspection procedure will be described sequentially.
First, as step S1, the liquid crystal display device 3 to be inspected is attached to the inspection table 4, connectors are connected, and the backlight 2 is turned on. During the inspection, the backlight 2 is always on.

  Next, a test signal is input to the liquid crystal display device 3 in step S2. At this time, a signal for displaying black is sent to the image display surface 31.

In step S <b> 3, the CCD camera 15 captures an initial screen before pressing the image display surface 31 in advance.
Usually, there is no pixel to be lit on the image display surface before the start of pressing, so this image is used as a reference image.

In step S <b> 4, the pressing unit 8 starts pressing the image display surface 31 of the liquid crystal display device 3.
The press control of the image display surface 31 is performed by the control computer 30. A command is sent to the X and Y axis robots, the pressing unit 8 is moved from the standby position to the right end of the image display surface 31 of the liquid crystal display device 3, and a command is sent to the Z axis robot to control the pressing force. Then, the pressing unit 8 is moved to the left by the X-axis robot while pressing the pressing unit 8 against the image display surface 31.
As a variation of the pressing method, it is also effective to move the pressing portion 8 after changing the pressing force at the same place. In this case, it is possible to quickly and accurately find a defective portion inside the liquid crystal display device 3 that cannot be manifested with a certain pressure.
Since the individual adjustment of the roller unit 6 using the air cylinder 64 has been described above, it is omitted here.

In step S <b> 5, the image display surface 31 is photographed by the CCD camera 15 in accordance with the pressing of the image display surface 31, and image processing for taking the difference between this image and the reference image is performed by the image processing unit 20 of the control computer 30.
Although the reference image and each image are compared here, a configuration may be used in which images taken before and after are compared. The reason is as follows.
When the image display surface 31 is pressed, ripple-like polarized light is generated around the pressed position.
By comparing two consecutive images, the misjudgment that this deflection can cause can be reduced. This is because polarized light recorded in either image is not a defect.

In step S6, the quality of the liquid crystal display device 3 is determined. If even one bright spot that is a short-circuit defect is found, the inspection is terminated as NG, and if there is no bright spot, the result is OK.
In step S7, it is determined whether or not the processing has been completed for all the image display images 31. If not completed, the process returns to step 3 to repeat the process. If completed, the process proceeds to step S8 and the inspection is terminated.
When the inspection is completed, the control computer 30 releases the pressing of the Z-axis robot, sends a command to the X and Y-axis robots, and returns the pressing unit 8 to the standby position. Then, the power source of the liquid crystal driving device 5 is turned off.

Thus, according to the inspection apparatus and the inspection method for the liquid crystal display device of the present invention, the entire image display surface 31 of the liquid crystal display device 3 can be pressed uniformly, and the entire image display surface 31 can be inspected with high accuracy.
In addition, since the pressing force and the number of pressings of each roller can be adjusted flexibly, it is possible to inspect with high accuracy by changing the pressing force according to the characteristics of the bending method depending on the location of the image display surface 31.
Further, since the entire image display surface 31 can be pressed only by moving the pressing portion 8 from one end to the other end of the image display surface 31, the inspection speed can be shortened.
Furthermore, even if the model of the liquid crystal display device 3 to be inspected changes, it can be dealt with inexpensively and simply by changing the inspection table 4.

  In this embodiment, the liquid crystal display device 3 to be inspected is in a panel state before mounting a drive circuit and a backlight, but even in a module state after mounting each circuit, If an inspection signal is generated from the drive circuit and an image is displayed, the inspection apparatus 1 can be inspected simply by changing the inspection table 4. The control computer 30 can also be connected to the network 32, and can count and manage the quality data of the liquid crystal display device 3 and the like.

It is a side view in Embodiment 1 of the inspection apparatus of the liquid crystal display device of this invention. It is a top view in Embodiment 1 of the inspection apparatus of the liquid crystal display device of this invention. 2 is a cross-sectional view of a liquid crystal display device 3 that is an inspection target in Embodiment 1. FIG. It is a system block diagram which shows the control system in Embodiment 1 of the test | inspection apparatus of the liquid crystal display device of this invention. It is a side view of the press part 8 in Embodiment 1 of the inspection apparatus of the liquid crystal display device of this invention. It is a front view of the press part 8 in Embodiment 1 of the inspection apparatus of the liquid crystal display device of this invention. It is sectional drawing of a roller and an image display apparatus when an image display surface is pressed with a roller in the conventional inspection apparatus. In Embodiment 1 of the liquid crystal display device of this invention, it is a flowchart of the test | inspection using the test | inspection apparatus 1. FIG.

Explanation of symbols

1. Inspection device for liquid crystal display device, 2 backlight unit, 3 liquid crystal display device,
31 Image display surface, 4 inspection table, 5 liquid crystal drive, 6 roller unit,
61 rollers, 62 roller support members, 63 telescopic members, 64 air cylinders,
7 roller unit support member, 8 pressing unit, 10 Z-axis robot, 11 X-axis robot, 12 Y-axis robot, 15 CCD camera, 20 image processing unit, 21 control unit,
27 pass / fail judgment unit, 28 axis controller, 30 control computer,
31 Network.

Claims (11)

In an inspection apparatus for detecting a short circuit between the electrodes by pressing an image display surface of a liquid crystal display device that sandwiches liquid crystal between electrodes provided on opposing glass substrates,
An inspection table for fixing the liquid crystal display device;
Signal input means for inputting a driving signal for inspection to the electrode terminal of the liquid crystal display device;
A plurality of rollers for pressing the image display surface;
A roller drive control mechanism for moving the plurality of rollers in a staggered manner so that the trajectory of each roller at the time of pressing overlaps the trajectory of other rollers;
A photographing mechanism for photographing an image of the image display surface;
An inspection apparatus for a liquid crystal display device, comprising: a quality determination unit that determines a display quality of the liquid crystal display device from the image. The liquid crystal display device inspection according to claim 1, wherein the pass / fail determination unit compares the image captured before the start of pressing the image display surface and each image captured while pressing the image display surface to determine pass / fail. apparatus. 2. The inspection apparatus for a liquid crystal display device according to claim 1, wherein the pass / fail judgment unit judges pass / fail by comparing two consecutive images taken while pressing the image display surface. 4. The inspection apparatus for a liquid crystal display device according to claim 1, wherein the roller drive control mechanism can press the pressure by controlling the pressure stepwise. 5. The inspection apparatus for a liquid crystal display device according to claim 1, wherein the pressing on the image display surface presses the same place a plurality of times. 6. The inspection apparatus for a liquid crystal display device according to claim 1, wherein the roller drive control mechanism can control the pressing force for each roller. In an inspection method for detecting a short circuit between the electrodes by pressing an image display surface of a liquid crystal display device that sandwiches liquid crystal between electrodes provided on opposing glass substrates,
Fixing the liquid crystal display device to an inspection table;
Inputting a driving signal for inspection to an electrode terminal of the liquid crystal display device;
Shooting the image on the image display surface while pressing the image display surface with a plurality of rollers that are alternately attached so that the trajectory of each roller overlaps the trajectory of the other roller;
And a step of judging whether or not the display quality of the liquid crystal display device is good from the image. 8. The liquid crystal according to claim 7, wherein the step of determining whether or not the display quality is good includes a step of comparing an image photographed before pressing the image display surface with each image photographed while pressing. Display device inspection method. 8. The method for inspecting a liquid crystal display device according to claim 7, wherein the step of determining whether the display quality is good includes a step of comparing two consecutive images taken while pressing the image display surface. . 10. The pressing of the image display surface by the roller is performed by changing the pressing force in a stepwise manner a plurality of times at the same point on the image display surface. 2. A method for inspecting a liquid crystal display device according to 1. The liquid crystal display device inspection method according to claim 7, wherein the pressing force is controlled for each roller.

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