JPH10160628A - Image quality inspection device for lcd panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily detect polarization dependency defect, for improved defect detection rate. SOLUTION: On a panel stage 1 comprising a back light 4 and the first polarizing plate 5, an LCD panel 20 which is to be inspected is mounted. Driven by a probe unit 2, the LCD panel 20 displays an image. The second polarizing plate 6 is assigned above the LCD panel 20. The second polarizing panel 6 is rotated with a pulse motor 9, with polarization direction to the first polarizing plate 5 variable. With a CCD camera 3 assigned above the second polarizing plate 6, the image picked up by the CCD camera 3 is outputted to an image process/analysis process part 7, and image quality of the LCD panel is evaluated there.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image quality inspection apparatus for an LCD panel, which images a display state of an LCD panel with a camera and inspects the image quality of the LCD panel based on the image captured by the camera.

[0002]

2. Description of the Related Art FIG. 5 is a schematic block diagram of a conventional LCD panel image quality inspection apparatus. As shown in FIG. 5, the inspection target is a TN type LCD panel 120, which is mounted on the panel stage 101. Panel stage 101
Has a backlight 104 and a first polarizer 105, and illumination light from the backlight 104 emits light from the first polarizer 1.
The LCD panel 120 is illuminated through the LCD panel 120 through the LCD panel 105.

[0003] LCD mounted on panel stage 101
A probe unit 102 is electrically connected to the panel 120 by a probe needle 102a.
The LCD panel 120 is driven according to the inspection conditions of
An image is displayed on the D panel 120. Further, above the LCD panel 120, a second polarizing plate 106 is arranged. The second polarizing plate 106 is arranged so that the polarization direction is orthogonal to the first polarizing plate 105. This allows
When no voltage is applied to the LCD panel 120, the light of the backlight 104 passes through the second polarizer 106, and the LCD panel 120 is set to “white display”. When a voltage is applied, the light of the backlight 104 is transmitted to the second polarizer 10.
6 and the LCD panel 120 becomes "black display".

Then, the light transmitted through the second polarizing plate 106 is
The display image on the LCD panel 120 is captured by the CCD 103 camera, and the captured image is processed by the image processing / analysis processing unit 107.
The image processing and analysis are performed to evaluate the image quality of the LCD panel 120.

[0005]

However, LCDs
The panel has a defect that is easily seen by changing the polarization angle. In particular, protrusions and foreign substances are typical examples. Such a polarization-dependent defect, that is, a polarization-dependent defect, could not be detected by a conventional image quality inspection apparatus.

Accordingly, an object of the present invention is to provide an image quality inspection apparatus for an LCD panel which can easily detect a polarization-dependent defect and improve the defect detection rate.

[0007]

In order to achieve the above object, an image quality inspection apparatus for an LCD panel according to the present invention comprises a first polarizing plate and a second polarizing plate opposed to each other with an LCD panel interposed therebetween. An image is displayed on the LCD panel in a state where illumination light is emitted from the side of the polarizing plate, and the image quality of the LCD panel is evaluated based on a display image of the LCD panel taken by a camera from the side of the second polarizing plate. In the image quality inspection apparatus for an LCD panel, the second polarizing plate is variably provided with a polarization direction with respect to the first polarizing plate.

In this image quality inspection apparatus, first, a general image quality is inspected by making the polarization direction of the second polarizing plate perpendicular to the first polarizing plate. Next, the orientation of the second polarizing plate is changed, and a polarization-dependent defect is detected.

In the image quality inspection apparatus for an LCD panel according to the present invention, a first polarizing plate and a second polarizing plate are disposed opposite to each other with the LCD panel interposed therebetween, and illumination light is emitted from the first polarizing plate side. In the state, an image is displayed on the LCD panel, and the L image captured by the camera from the second polarizing plate side is displayed.
In an image quality inspection apparatus for an LCD panel that evaluates the image quality of the LCD panel based on a display image of a CD panel, a plurality of the second polarizing plates can be moved to positions facing the first polarizing plate, respectively. A plurality of second polarizing plates provided in different polarization directions with respect to the first polarizing plate;
Is characterized in that one of the polarizing plates has a polarization direction orthogonal to the first polarizing plate.

In this image quality inspection apparatus, first, a plurality of second
Among the polarizing plates, those having a polarizing direction orthogonal to the first polarizing plate are opposed to the first polarizing plate, and the general image quality is inspected. Next, among the remaining second polarizers, the second polarizer having the orientation in which the polarization-dependent defect is most visible is placed on the first polarizer.
And a polarization-dependent defect is detected.

In this case, the plurality of second polarizers may be an LCD.
It may be mounted between a panel and a camera on a rotating plate that is rotated in a plane parallel to the plane of the LCD panel, or may be mounted between the LCD panel and the camera and parallel to the plane of the LCD panel. It may be attached to a stage that is reciprocated linearly in the plane.

[0012]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of an embodiment of an image quality inspection apparatus for an LCD panel according to the present invention.

As shown in FIG. 1, a TN type LCD panel 20 to be inspected is mounted on a panel stage 1 having a backlight 4 and a first polarizing plate 5 as in the prior art. In addition, the probe unit 2 is electrically connected to the LCD panel 20 mounted on the panel stage 1 by the probe needle 2a.
The point that the CD panel 20 is driven and an image is displayed on the LCD panel 20 is the same as in the related art.

Above the LCD panel 20, the second polarizing plate 6 is arranged. The second polarizing plate 6 has a disk shape as shown in FIG. 2, and a gear 10 is integrally provided on the outer periphery thereof. The gear 10 meshes with a pinion 11 fixed to the output shaft of the pulse motor 9, and by rotating the pulse motor 9, the second polarizing plate 6 is rotated in the circumferential direction. That is, the second polarizing plate 6 is variably provided in the polarization direction with respect to the first polarizing plate 5.

Referring again to FIG. 1, above the second polarizing plate 6, an LCD panel 20 that has passed through the second polarizing plate 6 is provided.
A CCD camera 3 for picking up a display image is arranged. The image picked up by the CCD camera 3 is output to an image processing / analysis processing section 7, where predetermined image processing and analysis processing for image quality inspection are performed, and the image quality of the LCD panel 20 is evaluated. When inspecting for a polarization-dependent defect, the image processing / analysis processing unit 7 rotates the second polarizing plate 6 by an arbitrary angle by the pulse motor 9 via the drive circuit 8.

The second polarizing plate 6 is usually arranged with the polarization direction orthogonal to the first polarizing plate 5. Thereby, when no voltage is applied to the display element of the LCD panel 20, the illumination light from the backlight 4 is transmitted and the LCD panel 20 becomes "white display", and when the voltage is applied, the illumination light from the backlight 4 is generated. It is cut off and "black display" is displayed. In this state, a general image quality inspection of the LCD panel 20 is performed based on the image captured from the CCD camera 3. Next, the polarization-dependent defect is rotated so that the orientation of the second polarizing plate 6 is the direction in which the defect can be most easily seen. Sexual defects are detected.

Regarding the rotation angle of the second polarizing plate 6, C
The image from the CD camera 3 may be output to a monitor (not shown) and set by an operator while watching the monitor image, or the second polarizer 6 may be intermittently rotated at a preset angle unit. Alternatively, the presence or absence of a polarization-dependent defect at each angle may be detected.

As described above, the polarization direction of the second polarizing plate 6 with respect to the first polarizing plate 5 is variably provided, so that a polarization-dependent defect that cannot be detected by a normal inspection can be reliably achieved. Can be detected, and the defect detection efficiency is greatly improved.

FIG. 3 is a schematic perspective view of a main part of another embodiment of the image quality inspection apparatus for an LCD panel of the present invention.

In this embodiment, the LCD panel 20 and the CC
Rotating plate 1 having a plurality of circular openings to which a second polarizing plate 6a is detachably attached between the rotating plate 1 and the D camera 3
2 is arranged. The rotation plate 12 is rotated in a plane parallel to the plane of the LCD panel 20 by the rotation of the pulse motor 9 transmitted through the belt 13. By rotating the rotating plate 12 by the pulse motor 9, each second polarizing plate 6a
Are sequentially moved to a position between the CCD camera 3 and the LCD panel 20, that is, a position facing the first polarizing plate 5. Each of the second polarizers 6 is attached to the rotating plate so that the polarization directions with respect to the first polarizers 5 when located between the CCD camera 3 and the LCD panel 20 are different from each other. However, one of them is attached so that the polarization direction with respect to the first polarizing plate 5 is orthogonal, and the second polarizing plate 6a is usually positioned between the CCD camera 3 and the LCD panel 20. doing.

As described above, the plurality of second polarizers 6a arranged so that the polarization directions with respect to the first polarizer 5 are different from each other are provided so as to be movable to a position facing the first polarizer 5. After performing the normal image quality inspection, the rotating plate 12
Is rotated to switch the second polarizing plate 6a, and the polarization-dependent defect can be reliably detected. In addition, since each second polarizing plate 6a is detachably attached to the circular opening of the rotating plate 12, the direction of the second polarizing plate 6a can be adjusted, and the polarization direction with respect to the first polarizing plate 5 can be freely changed. Can be set.

In the example shown in FIG. 3, an example is shown in which the second polarizer 6a is switched using the rotation of the rotary plate 12.
As shown in FIG. 4, the second polarizer 6 is
b may be switched. In FIG. 4, L
Provided between the CD panel 20 and the CCD camera 3 so as to be able to reciprocate linearly in a plane parallel to the plane of the LCD panel 20 by an appropriate drive means for converting a rotational movement of a pulse motor (not shown) into a linear movement. Stage 14 is arranged. The stage 14 is provided with a plurality of circular openings along the moving direction, and each opening has a second polarizing plate 6b.
Is detachably attached. Each second polarizing plate 6b
Have different polarization directions with respect to the first polarizing plate 5, and one of them has a perpendicular polarization direction. Thus, after the normal image quality inspection, the stage 14 is moved to switch the second polarizing plate 6b, and the polarization-dependent defect can be reliably detected.

[0024]

As described above, according to the present invention, the polarizing direction of the second polarizing plate with respect to the first polarizing plate is variably provided, or a plurality of second polarizing plates having different polarizing directions with respect to the first polarizing plate are provided. By using the polarizing plate described above, it is possible to detect a polarization-dependent defect that could not be detected conventionally, and it is possible to greatly improve the defect detection efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an image quality inspection apparatus for an LCD panel of the present invention.

FIG. 2 is a schematic perspective view of a second polarizing plate and a driving mechanism of the image quality inspection device for an LCD panel shown in FIG. 1;

FIG. 3 is a schematic perspective view of a main part of another embodiment of the image quality inspection apparatus for an LCD panel of the present invention.

FIG. 4 is a schematic perspective view of a main part of still another embodiment of the image quality inspection apparatus for an LCD panel of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional LCD panel image quality inspection apparatus.

[Explanation of symbols]

 Reference Signs List 1 panel stage 2 probe unit 2a probe needle 3 CCD camera 4 backlight 5 first polarizer 6, 6a, 6b second polarizer 7 image processing / analysis processing unit 8 drive circuit 9 pulse motor 10 gear 11 pinion 12 rotation Plate 13 Belt 14 Stage

Claims (4)

[Claims] 1. A first polarizing plate and a second polarizing plate are opposed to each other with an LCD panel therebetween, and an image is displayed on the LCD panel in a state where illumination light is emitted from the first polarizing plate side. An image quality inspection apparatus for an LCD panel for evaluating image quality of the LCD panel based on a display image of the LCD panel captured by a camera from a side of the second polarizing plate, wherein the second polarizing plate includes the first polarizing plate. An image quality inspection apparatus for an LCD panel, wherein a polarization direction with respect to a plate is variably provided. 2. A first polarizing plate and a second polarizing plate are disposed opposite to each other with an LCD panel therebetween, and an image is displayed on the LCD panel in a state where illumination light is emitted from the first polarizing plate side. An image quality inspection apparatus for an LCD panel that evaluates the image quality of the LCD panel based on a display image of the LCD panel captured by a camera from the second polarizing plate side, wherein a plurality of the second polarizing plates are each The first polarizing plate is movably provided at a position facing the first polarizing plate and has a different polarization direction with respect to the first polarizing plate, and one of the plurality of second polarizing plates is provided with the first polarized light. An image quality inspection apparatus for an LCD panel, characterized in that the polarization directions with respect to the plate are orthogonal. 3. The liquid crystal display according to claim 1, wherein the plurality of second polarizers are arranged on the LCD.
3. The image quality inspection apparatus for an LCD panel according to claim 2, wherein the apparatus is mounted between a panel and the camera and attached to a rotating plate that is rotated in a plane parallel to a plane of the LCD panel. 4. The liquid crystal display according to claim 1, wherein the plurality of second polarizers are arranged on the LCD.
The image quality inspection apparatus for an LCD panel according to claim 2, wherein the apparatus is mounted on a stage that is disposed between the panel and the camera and that is reciprocated linearly in a plane parallel to a plane of the LCD panel.