JPH09257641A - Method and device for inspecting display surface of liquid crystal panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a method of the device for inspecting a display surface, which can positively detect the poor display and the defective display in the inspection of the display surface of a liquid crystal panel. SOLUTION: At the upper part of a light irradiation means 10 constituted of a white fluorescent lamp and the like, a first polarizing plate 11 is arranged and constituted so that the plate can be rotated with an optical axis as the center. At the upper part of the first polarizing plate 11, a liquid crystal panel 12 is arranged and constituted so that the specified driving voltage is applied from an AC power supply 13. At the upper part of the liquid crystal panel 12, a second polarizing plate 14 is arranged and constituted so that the plate can be rotated with the optical axis as the center. At the upper part of the second polarizing plate 14, a light condensing means 15 is arranged. The light condensing means 15 is constituted of, e.g. a microscope, a CCD(charge-coupled device) camera and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for inspecting a display surface of a liquid crystal panel, and more particularly to observing the liquid crystal panel through the polarizing plate before attaching the polarizing plate to the liquid crystal panel to thereby display the defective display surface. A method and apparatus for discovering.

[0002]

2. Description of the Related Art Conventionally, in the manufacturing process of a liquid crystal panel, a liquid crystal cell is constructed by enclosing a liquid crystal between two panel substrates.
Polarizing plates are attached to both sides of the liquid crystal cell. In this manufacturing process, a defect of the liquid crystal cell itself may be found in advance by observing the display surface of the liquid crystal cell through the polarizing plate before adhering the polarizing plate, and repair work may be performed.

To observe the display surface, two polarizing plates set in the same polarization axis direction as the polarizing plates to be attached are arranged on both sides of the liquid crystal cell, and a backlight is applied to the display surface to observe the display surface with a microscope. , A CCD camera or the like. The observation is performed both when a voltage is applied to the liquid crystal cell and when it is not applied.

This display surface inspection step is carried out so that defects and defects which cannot be found only by the liquid crystal cell can be easily found when observed through the polarizing plate, and also through the same polarizing plate as the final finished product. It is also meaningful to confirm the state of the display surface.

Display defects or display defects observed in the display surface inspection step are, as shown in FIG. 2, a linear defect A caused by a short circuit in the wiring, a linear defect B caused by a disconnection, a foreign substance mixed in or active. These are point defects C caused by defective blocking, stain defects D caused by residual cleaning marks, and coloring unevenness E caused by changes in the liquid crystal cell gap.

[0006]

By the way, in the above-mentioned display surface inspection step, display defects and display defects can be found in advance by actually observing the display surface through a polarizing plate, and these can be corrected. Further, there is an advantage that wasteful execution of the subsequent steps can be avoided. However, in the display surface inspection process, there is no choice but to observe with a constant incident direction of light and at a constant visual angle. Therefore, observation with different incident directions of light and observation with different visual angles should be performed sufficiently. Therefore, display defects and display defects are often overlooked, and there is a problem that the defect removal rate by the display surface inspection is low. Therefore, particularly subtle defects are often overlooked and often discovered only after the product is completed. When manufacturing a high-quality liquid crystal panel, production efficiency is reduced, and it is difficult to reduce the manufacturing cost. There is a problem.

Therefore, the present invention solves the above-mentioned problems, and an object thereof is to provide a display surface inspection method or apparatus capable of surely finding a display defect or a display defect in the display surface inspection of a liquid crystal panel as compared with the prior art. It is to be realized.

[0008]

Means for Solving the Problems The means taken by the present invention to solve the above-mentioned problems are obtained by observing a display surface of the liquid crystal panel through a polarizing plate on the liquid crystal panel before the polarizing plate attaching step. In a method for inspecting a display surface of a liquid crystal panel to be inspected, the direction of the polarization axis of the polarizing plate in the polarizing plate attaching step is a reference direction with respect to the plane alignment direction of the liquid crystal panel, and the reference is the reference direction with the polarizing plate as the reference direction. While observing the state, the display surface is observed while rotating the polarizing plate about the optical axis.

According to this means, by rotating the polarizing plate, it becomes possible to easily find a display defect and a display defect that cannot be found or are difficult to find with a normal arrangement of the polarizing plate. Can be reduced.

Here, it is preferable that the display surface is observed at one or more rotation angles of the polarizing plate in which it is easy to find a defective portion, and the observation is performed at the rotation angle. According to this means, the inspection can be performed quickly and efficiently by observing at the rotation angle.

In this case, it is also desirable to set the rotation angle in advance for each of a plurality of failure modes. According to this means, it is possible to perform the inspection in a state in which it is easy to observe depending on the defect mode, so that it is possible to improve the detection rate of the display defect or the display defect.

Next, on the liquid crystal panel before the step of attaching the polarizing plate,
A liquid crystal panel display surface inspection device for inspecting by observing the display surface of the liquid crystal panel through a polarizing plate is provided with a polarizing plate holding portion that holds the polarizing plate rotatably about an optical axis. Is.

Here, it is preferable to provide a polarizing plate drive unit for rotating the polarizing plate held by the polarizing plate holding unit to a desired rotation angle position.

Further, it is desirable that the polarizing plate is attached to a light collecting portion for observing the display surface. In this case, the device can be simplified and downsized by attaching it to the light collecting part, and the polarizing plate itself can be made small by arranging it in the vicinity of the light collecting part.

Further, it is desirable to provide a heating means for heating the liquid crystal panel. In this case, it becomes easy to observe the liquid crystal panel after heating, and it becomes possible to observe the display surface while keeping the liquid crystal panel at a predetermined temperature. Here, as the heating means, it is desirable to bring a heater formed of a transparent conductive material into contact with the liquid crystal panel surface.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of a method and apparatus for inspecting a display surface of a liquid crystal panel according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram showing an outline of an embodiment of a method and apparatus for inspecting a display surface of a liquid crystal panel according to the present invention. The light irradiation means 10 is, for example, a white fluorescent lamp used as a backlight of a liquid crystal panel. A first polarizing plate 11 is arranged above the light irradiation means 10 and is configured to be rotatable around the optical axis. A liquid crystal panel 12 is arranged above the first polarizing plate 11, and a predetermined drive voltage is applied to the liquid crystal panel 12 from an AC power supply 13.

A second polarizing plate 1 is provided above the liquid crystal panel 12.
4 is arranged so as to be rotatable around the optical axis. A condensing unit 15 is arranged above the second polarizing plate 14, and the condensing unit 15 is composed of, for example, a microscope, a CCD (charge coupled device) camera, or the like.

In the liquid crystal panel 12, a rubbing treatment is preliminarily performed in a predetermined direction on the panel substrate itself or an alignment film deposited on the inner surface of the panel substrate, and the rubbing treatment causes the liquid crystal molecules to be aligned in the alignment direction 12a shown by an arrow in the figure. Is oriented. With respect to this alignment direction 12a, in the reference state in which the completed liquid crystal panel is arranged in the same state as the polarizing plates attached to the upper and lower sides, the polarization axis 11a of the first polarizing plate 11 and the second polarizing plate The 14 polarization axes 14a are oriented in directions orthogonal to each other.

When the display surface shown in FIG. 1 is inspected in the reference state, the incident direction of light and the observation direction are always constant, and therefore, even if the observation is carried out very carefully, as shown in FIG. It is not possible to completely find all the linear defects A and B, the dot defect C, the stain defect D, and the coloring defect E.

However, from the above standard state, the first polarizing plate 1
When the first and second polarizing plates 14 are rotated about the optical axis, a display defect or display defect that cannot be found in the reference state may be clearly visible. Therefore,
The upper and lower polarizing plates 11 and 1 with the reference state as the reference position.
By rotating 4, the display rate of display defects and display defects can be increased, and the defect rate of finished products can be reduced.

In this case, the optimum values of the rotation angles of the first polarizing plate 11 and the second polarizing plate 14 when observing the display surface are:
It depends on the types of defects and defects shown in FIG. 2 and the degree of defects and defects. Therefore, one or a plurality of rotation angles that are most observable can be obtained in advance for each of the defects or defects A to E, and the rotation angles can be sequentially set and observed. Most of these rotation angles are subtly different depending on the degree of defects and the cell thickness of the liquid crystal cell, and therefore it is preferable to set them with a certain width.

A predetermined AC drive signal is usually applied to the liquid crystal panel 12 from an AC power source 13 to observe each pixel on the display surface in a lighting state. In the lighting state, short circuit, disconnection, defect of active element, etc. are observed. Further, even when the drive signal is not applied, dust contamination, gap defect, stain defect, etc. can be observed.

FIG. 3 is a schematic block diagram showing an example of a display surface inspection apparatus for a liquid crystal panel according to the present invention. This device includes an illumination side device 20 and a liquid crystal panel 12 with respect to the illumination side device 20.
And a light-collecting-side device 30 facing each other.

The illumination side device 20 has an illumination housing portion 22 in which a white fluorescent lamp 21 is housed, a lid frame portion 23 rotatably attached to the illumination housing portion 22, and an outer periphery of the lid frame portion 23. A drive belt 24 that engages and transmits rotation from an electric motor (not shown) and a polarizing plate 25 fixed inside the lid frame portion 23 are provided.

In the condensing side device 30, a supporting plate 31 held horizontally, a condensing lens body 32 attached to the supporting plate 31, and a tube rotatably attached to the condensing lens body 32. A frame portion 33 and a drive belt 34 that engages with the outer periphery of the cylindrical frame portion 33 and transmits rotation from an electric motor (not shown).
And a polarizing plate 35 fixed inside the cylindrical frame 33.

The drive belts 24 and 34 provided on the illumination side device 20 and the light collection side device 30, respectively, rotate the polarizing plates 25 and 35 to a desired angular position by the driving force of the electric motor. The rotation amount of the electric motor and the operation and stop of the electric motor can be operated by a control switch (not shown).

Although the display surface of the liquid crystal panel 12 can be observed by directly looking into the condenser lens body 32 of the condenser side device 30, a CCD camera, a photographic device or the like is provided above the condenser lens body 32. It can also be attached to take video images and photographs.

According to this device, since the polarizing plates 25 and 35 are attached to the illuminating side device 20 and the condensing side device 30, respectively, the device structure becomes simple and compact, and
In particular, the polarizing plate 35 of the condensing side device 30 can be formed small.

FIG. 4 shows the structure of a display surface inspection apparatus having a configuration different from that of the display surface inspection apparatus shown in FIG. 4, the same parts as those shown in FIG. 3 are designated by the same reference numerals, and the description thereof will be omitted.

In this display surface inspection apparatus, a glass transparent substrate 36 fixed to the overhanging support frame 22a of the illumination accommodating portion 22 is arranged on the upper surface of the illumination side device 20, and the ITO (ITO ( A heater pattern 37 made of indium tin oxide is formed. LCD panel 12
Are placed on the heater pattern 37.

By energizing the heater pattern 37, the liquid crystal panel 12 can be heated, and the occurrence of display defects or display defects due to heating can be observed. The heating temperature of the liquid crystal panel 12 is 30 to 60 ° C.

Conventionally, the liquid crystal panel 12 was placed on another hot plate, heated to a predetermined temperature, and then set in a display surface inspection apparatus equipped with a polarizing plate. In this embodiment, since the heat treatment can be performed just by setting it in the apparatus, the display state after heating can be easily inspected and the display surface can be observed while the liquid crystal panel 12 is kept at a predetermined temperature. it can.

[0034]

As described above, according to the present invention, the following effects can be obtained.

According to the first aspect, by rotating the polarizing plate, it becomes possible to easily find a display defect and a display defect that cannot be found or difficult to find in the normal arrangement of the polarizing plate. The rate can be reduced.

According to the first aspect and the third to fifth aspects, the inspection can be performed quickly and efficiently by observing at the rotation angle.

According to the second aspect, since the inspection can be performed in a state in which it is easy to observe depending on the failure mode, it is possible to improve the detection rate of the display failure or the display failure.

According to the sixth aspect, the device can be simplified and downsized by attaching it to the light collecting part, and the polarizing plate itself can be made small by disposing it near the light collecting part.

According to the seventh aspect, it becomes easy to observe the liquid crystal panel after heating and it becomes possible to observe the display surface while keeping the liquid crystal panel at a predetermined temperature.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a schematic configuration of an embodiment of a display surface inspection method and apparatus for a liquid crystal panel according to the present invention.

FIG. 2 is an explanatory diagram showing a display defect and a display defect of a liquid crystal panel.

FIG. 3 is a vertical cross-sectional view showing a configuration example of an embodiment of a display surface inspection device for a liquid crystal panel according to the present invention.

FIG. 4 is a vertical cross-sectional view showing another configuration example of the embodiment of the display surface inspection device for a liquid crystal panel according to the present invention.

[Explanation of symbols]

 10 Light Irradiating Means 11 First Polarizing Plate 12 Liquid Crystal Panel 13 AC Power Supply 14 Second Polarizing Plate 15 Condensing Means 37 Heater Pattern

Claims (7)

[Claims] 1. A method for inspecting a display surface of a liquid crystal panel, which comprises inspecting a display surface of the liquid crystal panel through a polarizing plate on the liquid crystal panel before the step of attaching the polarizing plate, wherein a plane alignment direction of the liquid crystal panel On the other hand, while observing a reference state in which the polarization axis direction of the polarizing plate in the polarizing plate attaching step is the reference direction and the polarizing plate is in the reference direction, while rotating the polarizing plate about the optical axis, A method for inspecting a display surface of a liquid crystal panel, which comprises observing the display surface. 2. The liquid crystal according to claim 1, wherein the observation of the display surface is performed at one or more rotation angles of the polarizing plate in which it is easy to find a defective portion in advance, and the rotation angle is used. Panel display surface inspection method. 3. The display surface inspection method for a liquid crystal panel according to claim 2, wherein the rotation angle is preset for each of a plurality of failure modes. 4. A display surface inspection device for a liquid crystal panel, which comprises inspecting a display surface of the liquid crystal panel through a polarizing plate on the liquid crystal panel before the step of attaching the polarizing plate, wherein the polarizing plate has an optical axis. An apparatus for inspecting a display surface of a liquid crystal panel, which is provided with a polarizing plate holding portion which holds a polarizing plate as a center. 5. The display surface of a liquid crystal panel according to claim 4, further comprising a polarizing plate driving unit that rotationally drives the polarizing plate held by the polarizing plate holding unit to a desired rotation angle position. Inspection device. 6. The display surface inspection device for a liquid crystal panel according to claim 4 or 5, wherein the polarizing plate is attached to a condensing section for observing the display surface. 7. The display surface inspection device for a liquid crystal panel according to claim 4, further comprising heating means for heating the liquid crystal panel.