JPH08304852A - Method and device for inspecting liquid crystal display substrate - Google Patents

Abstract

PURPOSE: To shorten an inspection time and to precisely inspect a voltage state of a pixel electrode in the inspection of a liquid crystal display substrate before sealing a liquid crystal in it. CONSTITUTION: A sensor element 2 simultaneously accompanying an optical change according to respective voltage states for plural pixel electrodes 12 is made approach to or abutted on the liquid crystal display substrate 1, and a light source 3 radiating light 6 from a substrate rear surface in the surface direction is provided on the substrate rear surface, and the device is provided with a light detection part 5 making the light passing through the sensor element 2 optically changed by the voltage of the pixel electrode 12 and whose polarization state is changed incident on a polarizing plate 4, and converting the light to a light quantity proportioning to the polarization change amount by the polarizing plate 4, and detecting the light quantity and converting it to an electric signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection of a liquid crystal display substrate, and more particularly to a method and an apparatus for inspecting a defect of the liquid crystal display substrate which occurs before liquid crystal is filled.

[0002]

2. Description of the Related Art Conventionally, as a method and apparatus for inspecting a liquid crystal display substrate before injecting liquid crystal, a method and apparatus for electrically inspecting the operation of a thin film transistor and a pixel electrode of each pixel using a prober have been used.

A conventional inspection apparatus for inspecting a plurality of pixels on a liquid crystal display substrate at the same time is shown in FIG. 4, for example.

Referring to FIG. 4, a module 50 having a thin film transparent electrode 42 on the upper surface of an electro-optical element 41 made of liquid crystal or Pockels crystal and a reflecting plate 43 on the lower surface is provided in a small space on the upper surface of the liquid crystal display substrate 1. Place a gap.

When a voltage (inspected voltage) is applied to the pixel electrode, the optical property of the electro-optical element 41 changes due to the potential difference with the thin film transparent electrode 42.

The liquid crystal display substrate 1 is irradiated with light from a light source 3 arranged in a horizontal direction, reflected by a beam splitter 44 provided on the upper side of the module 50, and irradiated onto the module.

The light incident on the module 50 is reflected by the reflection plate 4
It is reflected by 3 and is emitted from the module 50 toward the beam splitter 44. At that time, the emitted light from the module has its polarization or the amount of light changed in accordance with the change in the optical property of the electro-optical element 41.

The emitted light passes through the beam splitter 44,
Further, by passing through the filter 45, only the specific wavelength centered on red color is input to the photodetection section 5. CCD
The incident light is detected by the photodetector 5 including the above, and is converted into an electric signal to inspect the operation (voltage) state of each pixel.

[0009]

However, in the conventional method and apparatus using the prober, it is necessary to electrically inspect each pixel one by one, so that there is a problem that the inspection takes too long.

Further, the conventional device (see FIG. 4) for optically inspecting a plurality of pixels at the same time detects the light reflected by the reflection plate of the module, and the incident light and the reflected light of the module 50 are the same. Since it is an optical path, a part of the reflected light returns to the light source, and due to the effect of the returned light, the voltage state of the pixel electrode cannot be accurately inspected when the voltage of the pixel electrode is low.

Therefore, an object of the present invention is to solve the above problems and provide a method and apparatus for shortening the inspection time and accurately inspecting the voltage state of the pixel electrode in the inspection of the liquid crystal display substrate before the liquid crystal is sealed. Especially.

[0012]

In order to achieve the above-mentioned object, the present invention provides a liquid crystal display substrate before liquid crystal encapsulation, which has at least a gate wiring, a source wiring, a pixel electrode and a thin film transistor formed on the surface thereof. A sensor device that changes optical characteristics according to the voltage state of the pixel electrode is arranged so as to be separated from or in contact with the surface of the substrate, and light of a predetermined polarization state is incident from the rear surface of the liquid crystal display substrate toward the surface. Then, the light output from the substrate surface is made incident on the sensor device, and the voltage state of the pixel electrode is detected based on the polarization state of the output light from the sensor device. I will provide a.

The present invention also provides a pixel electrode before encapsulating liquid crystal,
On the surface of the liquid crystal display substrate on which the thin film transistor, the gate, and the source wiring are formed, a sensor element accompanied by an optical change according to an applied electric field is arranged so as to be separated from or in contact with the surface. Linearly polarized light is emitted from the back surface of the display substrate toward the front surface (the surface on which the pixel electrode is provided), and the polarization state is changed by passing through the sensor element that is optically changed by the voltage of the pixel electrode. A liquid crystal display characterized in that light is passed through a polarizing plate to be converted into a light quantity proportional to a polarization change quantity, the light quantity is detected and converted into an electric signal, and the voltage state of the pixel electrode is inspected by the electric signal. A method for inspecting a board is provided.

Further, according to the present invention, a prober for supplying an electric signal to a shooting bar of a liquid crystal display substrate to drive each pixel and an electric signal generator are provided, and the liquid crystal display substrate surface is provided with a prober according to a voltage of the pixel electrode. A sensor element with an optical change is arranged, and a light source that emits linearly polarized light from the back surface of the liquid crystal display substrate to a surface direction, and light that has changed polarization in proportion to the voltage intensity of the pixel electrode through the sensor element are provided. A polarizing plate that converts the amount of light proportional to the amount of change in polarization, a photodetector that converts the amount of light from the polarizing plate into an electric signal and outputs the electric signal, and a signal processing of the output electric signal to detect the voltage of the pixel electrode. There is provided a signal processing device for displaying, and an inspection device for a liquid crystal display substrate.

In the liquid crystal display substrate inspecting method of the present invention, preferably, a polarizing plate is provided at the subsequent stage of the sensor device, the polarizing plate outputs a light amount corresponding to a polarization change amount, and the light amount is converted into an electric signal. The voltage state of the pixel electrode is inspected after conversion.

In the liquid crystal display substrate inspection method of the present invention, preferably, the sensor device includes an electro-optic crystal having a Pockels effect.

In the method for inspecting a liquid crystal display substrate according to the present invention, preferably, the sensor device includes a liquid crystal interposed between transparent electrode layers provided on opposite surfaces of the glass substrate. And

In the liquid crystal display substrate inspection method of the present invention, preferably, linearly polarized light is incident from the substrate rear surface of the liquid crystal display substrate toward the surface.

In the liquid crystal display substrate inspection apparatus of the present invention, preferably, the sensor element has an electro-optic crystal having a Pockels effect, and first and second transparent layers provided on both end faces of the electro-optic crystal. A conductive layer, the second transparent conductive layer is divided into a plurality of portions corresponding to the positions corresponding to the pixel electrodes, and has a smaller area than the second transparent conductive layer on the second transparent conductive layer. It is characterized in that it is equipped with a metal electrode.

In the liquid crystal display substrate inspecting apparatus of the present invention, preferably, the sensor elements are provided in a plurality of positions in correspondence with the first glass substrate provided with the first transparent conductive layer and the positions corresponding to the pixel electrodes. A second glass substrate provided with a second transparent conductive layer divided into, and the second glass substrate has an opening at a position corresponding to the pixel electrode, and the opening has the opening The metal electrode is inserted so as to protrude from the end surface of the second glass substrate facing the pixel electrode,
A liquid crystal is enclosed between the first transparent conductive layer and the second glass substrate so as to cover the second transparent electrode.

In the liquid crystal display substrate inspection apparatus of the present invention, preferably, the liquid crystal is a nematic type liquid crystal.

[0022]

According to the present invention, the operation state is detected by irradiating the liquid crystal display substrate from the back surface to the front surface with linearly polarized light and detecting the change in the polarization state through the sensor that changes the polarization state according to the potential of the pixel electrode. Since it is possible to inspect a plurality of light pixels at the same time, the inspection time can be shortened. And according to the present invention,
In the configuration shown in FIG. 4, part of the reflected light returns to the light source, and the problem that the voltage state of the pixel electrode cannot be accurately inspected due to the effect of the returned light when the voltage of the pixel electrode is small is solved. Even if the voltage of the pixel electrode is small, the voltage state of the pixel electrode can be accurately inspected.

Further, according to the present invention, when liquid crystal is used as the sensor element whose optical characteristics change depending on the voltage of the pixel electrode, the sensor element can be manufactured in the same size as the liquid crystal display substrate to be inspected. In addition, the inspection time can be significantly shortened, and an increase in the inspection time of, for example, a large-sized liquid crystal display substrate can be suppressed.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

[0025]

[Embodiment 1] FIG. 1 is a diagram showing the configuration of a liquid crystal display substrate inspection apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the sensor element 2 is brought close to or in contact with the surface of the liquid crystal display substrate 1 before liquid crystal injection. As will be described later in detail, the optical properties of the sensor element 2 change depending on the voltage of the pixel electrode 12 (voltage to be inspected).

The linearly polarized light 6 is output from the light source 3 provided on the back surface side of the liquid crystal display substrate 1, passes through the liquid crystal display substrate 1, and is incident on the sensor element 2.
The polarization state of the light 6 changes as it passes through the sensor element 2.

The light whose polarization state has changed (light which has passed through the sensor element 2) is further converted into a light amount proportional to the amount of change in the polarization state by passing through the polarizing plate 4, and the photodetection section 5
Is incident on.

The photo-detecting section 5 is composed of a photodiode array or CCD in which photodiodes are arranged in a matrix, and outputs, for example, an electrical signal proportional to the amount of incident light.

Since the voltage to be inspected and this electric signal are in a proportional relationship, the voltage state of the pixel electrode 12 can be known from the intensity of the electric signal output from the photodetector 5, and the operation of each pixel can be inspected. it can. During inspection, a voltage is applied from a signal generator to a shooting bar connected to a source line and a gate line (not shown) on the surface of the liquid crystal display substrate 1 via a prober to drive pixels. The shooting bar is cut and removed in a later step of assembling the liquid crystal display panel by enclosing the liquid crystal.

Next, the sensor element 2 will be described in detail. FIG. 2 schematically shows a configuration example (cross-sectional view) of the sensor element 2 in this example.

A first transparent conductive layer 22 which is an ITO film made of indium, tin or oxide is vapor-deposited on the upper surface of the electro-optic crystal 21 such as LiNbO ₃ , KDP or GaAs. The first transparent conductive layer 22 has a wire connected to the end of the sensor element, a terminal is provided at the end of the wire, and the terminal is brought into contact with the GND (ground) portion of the liquid crystal display substrate 1 to electrically bring it to the GND level. ing.

Similarly, a transparent conductive layer is vapor-deposited on the lower surface of the electro-optical crystal 21, and then a second transparent conductive layer 23 which is divided into a plurality of parts is formed by a printing / etching technique. The electrode 24 is formed.

The metal electrode 24 is located at the center of the second transparent conductive layer 23 and has a size smaller than the area of the second transparent conductive layer 23 (for example, an area of about 30 μm × 30 μm □ or less).
It is said. The material of the metal electrode 24 is preferably a material having good adhesion to ITO, such as Cr.

The second transparent conductive layer 23 has the same size as the pixel electrode 12 (for example, 10) at a position where it overlies each pixel electrode 12 of the liquid crystal display substrate 1 to be inspected.
Multiple areas are formed in a matrix with an area of about 0 μm × 300 μm).

When a voltage is applied to the pixel electrode 12, the first
Potential difference occurs between the transparent conductive layer 22 and the pixel electrode 12 of
An electric field is generated in the electro-optic crystal 21 in the vertical direction. The refractive index of the electro-optic crystal 21 changes in proportion to the electric field strength. Then, by passing the light through the electro-optic crystal 21, the polarization state of the light is changed in proportion to the change amount of the refractive index.

[0037]

[Embodiment 2] FIG. 3 shows the structure of a sensor element according to a second embodiment of the present invention.

Referring to FIG. 3, a first glass substrate 31 having a first transparent conductive layer 22 deposited thereon and a second glass substrate 32 having a plurality of holes formed therein are provided with metal electrodes. After embedding 24 and further depositing a transparent conductive layer, it is divided by a printing / etching technique to form a second transparent conductive layer 23 on the metal electrode 24, and the first transparent conductive layer 22 and the second transparent conductive layer 22 facing each other are formed. Liquid crystal 33 is enclosed between the transparent conductive layers 23 (second glass substrate 32).

The size of the holes formed in the second glass substrate 32 is about 30 μmφ or less, and a plurality of holes are formed so as to be located at the center of each pixel electrode 12 of the liquid crystal display substrate 1 to be inspected. To be done.

The metal electrode 24 is projected by about several μm with respect to the surface close to the pixel electrode 12.

The second transparent conductive layer 23 covers the metal electrode 24 so as to overlap with each pixel electrode 12 of the liquid crystal display substrate 1 to be inspected, and has a size similar to that of the pixel electrode 12 (for example, about 100 μm × 300 μm). Area) and a plurality of them are formed in a matrix.

Further, the liquid crystal 33 to be sealed is preferably a nematic liquid crystal. The nematic liquid crystal can detect a low voltage of the pixel electrode 23 because the potential difference at which the optical change starts is lower than that of the polymer-dispersed liquid crystal.

When a voltage is applied to the pixel electrode 12, the first
Potential difference occurs between the transparent conductive layer 22 and the pixel electrode 12 of
The twist phenomenon occurs in the liquid crystal molecules. By passing the light through the liquid crystal 33, the polarization state of the light is changed according to the twist phenomenon.

In the sensor element of the first embodiment, the number of pixels that can be inspected at the same time is limited by the size of the electro-optic crystal 21 (for example, diameter of about 3 inches φ), but in this embodiment, the liquid crystal display to be inspected is limited. Since the sensor element can be manufactured in the same size as the substrate 1, the inspection time can be further shortened as compared with the first embodiment.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited to the above embodiments, and it goes without saying that the invention includes various embodiments according to the principles of the present invention.

[0046]

As described above, according to the present invention,
A plurality of pixels can be inspected at the same time, and the inspection time can be shortened, and the voltage state of the pixel electrode can be accurately inspected even when the voltage of the pixel electrode is small.

Further, according to the present invention, since the liquid crystal is used as the sensor element whose optical characteristics change depending on the voltage of the pixel electrode, the sensor element can be manufactured in the same size as the liquid crystal display substrate to be inspected. Therefore, the inspection time can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method and an apparatus for inspecting a liquid crystal display substrate according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of a sensor element according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a sensor element according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating a conventional method and apparatus for inspecting a liquid crystal display substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display substrate 2 Sensor element 3 Light source 4 Polarizing plate 5 Optical detection part 6 Light 11 Thin film transistor 12 Pixel electrode 21 Electro-optic crystal 22 First transparent conductive layer 23 Second transparent conductive layer 24 Metal electrode 31 First glass substrate 32 second glass substrate 33 liquid crystal 41 electro-optical element 42 thin film transparent electrode 43 reflector 44 beam splitter 45 filter

Claims (10)

[Claims] 1. A sensor for varying optical characteristics according to a voltage state of each pixel electrode on a liquid crystal display substrate before liquid crystal encapsulation, which has at least a gate line, a source line, a pixel electrode and a thin film transistor formed on a surface thereof. The device is arranged so as to be separated from or in contact with the substrate surface, light of a predetermined polarization state is incident from the substrate back surface of the liquid crystal display substrate to the surface direction, and the light output from the substrate surface is applied to the sensor device. A method for inspecting a liquid crystal display substrate, which comprises detecting a voltage state of the pixel electrode based on a polarization state of incident light and output light from the sensor device. 2. A polarizing plate is provided at a subsequent stage of the sensor device, the polarizing plate outputs a light amount corresponding to a polarization change amount, and the light amount is converted into an electric signal to inspect a voltage state of the pixel electrode. The method for inspecting a liquid crystal display substrate according to claim 1, wherein: 3. The method for inspecting a liquid crystal display substrate according to claim 1, wherein the sensor device includes an electro-optic crystal having a Pockels effect. 4. The method for inspecting a liquid crystal display substrate according to claim 1, wherein the sensor device includes a liquid crystal interposed between transparent electrode layers provided on opposite surfaces of the glass substrate. . 5. The method for inspecting a liquid crystal display substrate according to claim 1, wherein linearly polarized light is incident from the back surface of the liquid crystal display substrate toward the front surface. 6. A sensor element accompanied by an optical change according to an applied electric field is formed on a surface of a liquid crystal display substrate on which a pixel electrode before encapsulating liquid crystal, a thin film transistor, a gate and a source wiring are formed. Arranged so as to be separated or in contact with each other, linearly polarized light is radiated from the substrate rear surface of the liquid crystal display substrate toward the surface (the surface on which the pixel electrode is disposed) direction, and the linearly polarized light is optically changed by the voltage of the pixel electrode. The light whose polarization state is changed by passing through the sensor element is passed through the polarizing plate to be converted into a light amount proportional to the polarization change amount, the light amount is detected and converted into an electric signal, and the electric signal causes the pixel electrode A method for inspecting a liquid crystal display substrate, which comprises inspecting a voltage state. 7. A prober for driving each pixel by applying an electric signal to a shooting bar of the liquid crystal display substrate and an electric signal generator, wherein an optical change is made on the surface of the liquid crystal display substrate according to the voltage of the pixel electrode. A light source for arranging the accompanying sensor element and emitting linearly polarized light from the back surface of the liquid crystal display substrate to the front surface direction, and a polarization change amount of light passing through the sensor element and changed in polarization in proportion to the voltage intensity of the pixel electrode. A polarizing plate for converting the amount of light from the polarizing plate into a light amount, a photodetector for converting the amount of light from the polarizing plate into an electric signal and outputting the electric signal, and a signal processing for processing the output electric signal to detect and display the voltage of the pixel electrode. An apparatus for inspecting a liquid crystal display substrate, comprising: 8. The sensor element includes an electro-optic crystal having a Pockels effect, and first and second transparent conductive layers provided on both end surfaces of the electro-optic crystal, wherein the second transparent conductive material is provided. The layer is divided into a plurality of parts corresponding to the positions corresponding to the pixel electrodes, and a metal electrode having an area smaller than that of the second transparent conductive layer is provided on the second transparent conductive layer. 7. The liquid crystal display substrate inspection device according to 7. 9. The sensor element is provided with a first glass substrate provided with a first transparent conductive layer and a second transparent conductive layer divided into a plurality of portions corresponding to positions corresponding to the pixel electrodes. A second glass substrate, wherein the second glass substrate has an opening at a position corresponding to the pixel electrode, and the opening portion has an end surface facing the pixel electrode of the second glass substrate. A metal electrode is inserted so as to protrude into the space, and liquid crystal is sealed between the first transparent conductive layer and the second glass substrate so as to cover the second transparent electrode. The liquid crystal display substrate inspection device according to claim 7. 10. The inspection device for a liquid crystal display substrate according to claim 7, wherein the liquid crystal is a nematic liquid crystal.