JPS62170935A - Production of active matrix liquid crystal display device - Google Patents

Abstract

PURPOSE:To discriminate the quality of a substrate prior to orientation processing by opposing a picture element electrode on the substrate to an electrode on a transparent bottom plate of a testing case with a prescribed interval and impressing a voltage between both the electrodes to detect a defective part of the substrate. CONSTITUTION:Air in an air-tightly kept case 10 is exhausted to remove air bubbles left in liquid crystal between the transparent bottom plate 2 and the matrix substrate 12. After checking the removal of air bubbles, the whole or a specific part between the picture element electrode 13 and the opposite electrode 3 on the matrix substrate 12 is selected and the voltage is impressed to the selected part to change the optical transmittivity of the liquid crystal 11. Parallel light beams are irradiated from the outside of the bottom plate 2 and observed by naked eyes or through a microscope, the difference of the optical transmittivity of picture elements corresponding to the validity/invalidity of a non-linear element or the validity/invalidity of a connecting wiring is detected and the picture elements with abnormal transmittivity in the whole surface of a specific part of the matrix substrate are counted up to decide the validity/ invalidity of the substrate. Thus, the quality of the substrate can be decided prior to the processing process.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

In the present invention, transparent matrix substrates on which pixel electrodes and row electrodes or column electrodes are formed face each other, and a liquid crystal display pixel is provided between both pixel electrodes. The present invention relates to a method of manufacturing an active matrix liquid crystal display device in which a nonlinear element is connected between the display devices.

[Prior art and its problems]

FIG. 2 shows an equivalent circuit of an active matrix liquid crystal display device. Liquid crystal display pixels 24 are each connected between a scanning line 21 and a signal line 22 via a nonlinear element 23. In liquid crystal display devices for portable televisions and computer terminals, the number of pixels 24 is tens to hundreds of thousands, and in order to obtain a clear screen that is easy to see, the number of defective pixels must be 0.01% or less. is required. Most of the defective pixels are caused by defects in nonlinear elements, and conventionally, the following three methods have been used alone or in combination to detect defective pixels. 1. After assembling the liquid crystal panel, operate it to detect defective pixels. 2. A monitor matrix equivalent to the matrix section is built in advance in an unnecessary part of the active matrix board, and the electrical characteristics of the nonlinear elements in 1. are measured and the defective rate is regarded as the overall defective rate. 3. The electrical characteristics of a part of the matrix are measured and the defective rate is considered as the overall defective rate. Method 1 has the advantage of being able to reliably identify defective pixels, but requires pretreatment steps such as coating a J-retaining layer on a substrate for liquid crystal, applying an alignment layer to liquid crystal, and alignment treatment before assembling the panel. However, if a defective panel is produced, such a pretreatment process becomes completely useless, so it is dangerous to adopt only this method unless a high yield is expected. In method 2, the area of unnecessary parts of the board is small and the number of monitor elements/total number of elements has to be much smaller than 1, so only those with extremely low defect rates can be identified, making it difficult to provide assistance to method 1. It can only be used as Method 3 can be effective by appropriately selecting the number of pixels to be tested, but the drawbacks are that it takes time to measure the minute current itself and that there is a risk of damaging the panel because the probe is brought into contact with the pixels. have.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an active matrix liquid crystal display device that can determine the quality of a matrix substrate before alignment treatment using a relatively simple method with few of the above-mentioned drawbacks. .

[Key points of the invention]

In the present invention, without performing permanent assembly as in method 1 described above, the matrix substrate to be inspected is previously removably held and the pixel electrodes on the substrate are fixed to the electrodes on the transparent bottom plate of the inspection container. After filling the space between both electrodes with liquid crystal for inspection, a voltage is applied between both electrodes, and a defective part of the board is detected from an abnormal change in the light transmittance of the liquid crystal. The above object is achieved by making it possible to use only a display device in a display device.

[Embodiments of the invention]

FIG. 3 shows an inspection apparatus according to an embodiment of the present invention, which is divided into two parts. One of them is a container part 10, which includes a frame 1 and a glass plate 2 airtightly attached to the center part as a bottom plate.
Consisting of A counter electrode 3 made of a transparent conductive film is attached to the inner surface of the glass plate 2 at a position facing the matrix of the substrate to be inspected. This film is formed all over the surface of the glass plate 2, or in the form of parallel stripes parallel or perpendicular to the scanning electrodes of the matrix substrate to be inspected and having the width of the pixel electrodes. The surface of the transparent conductive film 3 may be subjected to alignment treatment for liquid crystal so that optical inspection as described below can be easily performed. The counter electrode 3, which may be attached to the outer surface of the container, can be electrically connected outside the container by a lead wire. A spacing piece 4 is attached to the inner surface of the bottom plate 2 to maintain a constant distance between the bottom plate and the matrix substrate to be inspected. The frame 2 is provided with a liquid crystal injection hole 5 at the bottom and an air supply/exhaust hole 6 at the top for making the inside of the inspection device lower than atmospheric pressure. The other part is the lid part 2o, which is made up of a lid frame 7 that is airtightly combined with the container part 1o at a predetermined position, and a glass plate 8 that is hermetically fitted as a lid plate into the center of the lid frame 7. A presser spring 9 is provided inside the lid frame 7. In order to facilitate the combination of the container part 10 and the lid part 20, the container frame 1 and the lid frame 7 are
The lid frame 7 may be connected with a hinge, or the lid frame 7 may be movable along a rail. FIG. 1 shows the state at the time of inspection, and parts common to those in FIG. 3 are given the same reference numerals. First, with the lid 20 open, liquid crystal 11 is injected through the liquid crystal injection hole 5 to fill the counter electrode 3 to the height of the spacing piece 4.Next, the matrix substrate 12 to be inspected is placed on the matrix electrode 13 such as a pixel electrode. Place it on top of the spacing piece 4 with the liquid crystal side facing the liquid crystal.As a result, the liquid crystal 11
is 0, which almost fills the space between the bottom plate 2 and the matrix substrate 12.
Next, the container part 1O is closed by the lid part 20, and the substrate 12 is fixed between it and the spacer piece 4 by the pressing spring 9. The airtight interior space of the container is evacuated from the supply/exhaust hole 6 using a vacuum pump, and air bubbles remaining in the liquid crystal between the bottom plate 2 and the substrate 2 are removed. In order to completely remove air bubbles, it is effective to repeatedly leak and exhaust the air inside the container after injecting the liquid crystal. After confirming that the bubbles have been removed, a voltage is applied to the entire matrix substrate 12 or to a specific portion between the pixel electrode 13 and the counter electrode 3, thereby changing the light transmittance of the liquid crystal 11. By irradiating parallel light from the outside of the bottom plate 2 and observing it with the naked eye or with a 1 m microscope, differences in light transmittance of pixels corresponding to the quality of the nonlinear element or the quality of the connection wiring can be detected. Count the abnormal transmittance pixels in the area to judge whether the substrate is good or bad. After the 0 judgment is completed, air is introduced into the container, the lid is opened, and the matrix substrate is taken out. Good matrix substrates are cleaned by cleaning the attached liquid crystal. It is removed and transferred to the next process. The inspection device is now ready to accept the next substrate to be inspected. FIG. 4 shows a simpler testing device used in another embodiment.
The substrate to be inspected 12 also serves as a lid plate. The substrate 12 is held by a substrate support 14 equipped with a vacuum chuck 15, and a matrix electrode 13 faces the electrode 3 on the bottom plate 2 via the liquid crystal 11. In order to ensure close contact between the substrate 12 and the spacing piece 4, the substrate support 14 is preferably soft and highly elastic, like rubber. The purpose of such inspection methods is to determine the functionality of nonlinear elements or to detect short circuits or disconnections in connection wiring between electrodes, and sufficient contrast and brightness as images are not necessarily required. The type of liquid crystal 11 does not matter, but a dynamic scattering effect can be achieved by using a liquid crystal with negative dielectric anisotropy. When applied, it is preferable that the method according to the present invention does not require the effect of initial alignment of liquid crystals and is characterized in that the inspection is performed before the alignment treatment of the substrate.

【Effect of the invention】

According to the present invention, the quality of the matrix substrate of the active matrix liquid crystal display device 1, for example, the quality of the nonlinear element, is placed on the counter electrode of the inspection device via the liquid crystal for inspection, and between the pixel electrode on the substrate and the counter electrode. By applying a voltage to and observing changes in liquid crystal light transmittance, the determination can be made before the pretreatment process for assembling the matrix substrate. In other words, it is possible to save costs for alignment treatment and other pre-processing steps that would be expended on defective substrates. Another advantage of the present invention is that the optical inspection according to the present invention can be performed without contact, and is faster than microcurrent measurement. It is inversely proportional to the defective rate and requires a lot of time when the defective rate is low, whereas in the inspection method according to the present invention, the measurement time does not depend on the number of pixels to be measured, that is, in the case of electrical measurement of a matrix substrate. , in order to guarantee a good product rate of 0.01%, lo
When measuring 5,000 points out of 10,000 elements, the defect rate must be 0, and the measurement time required about 1 hour. However, according to the inspection method according to the present invention, all approximately 100,000 pixels could be measured, and the measurement time could be kept within one minute.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a matrix substrate during inspection in an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of an active matrix liquid crystal display device, and FIG. 3 is a cutaway of the inspection device used in the embodiment of FIG. 1. The perspective view and FIG. 4 are cross-sectional views at the time of inspection of the matrix substrate in different embodiments of the present invention. l: container frame, 2: bottom plate, 3: counter electrode, 4: spacing piece, 7
: M frame, 8: Transparent lid plate, 9: Pressing spring, 11: Liquid crystal,
12: Matrix base exclusive, 13: Matrix electrode, 14
: Substrate support, 15: Vacuum chuck.

Claims (1)

[Claims] 1) Transparent matrix substrates with pixel electrodes and row or column electrodes formed on one side face each other, liquid crystal display pixels are provided between both pixel electrodes, and between the pixel electrodes on one substrate and the row or column electrodes. When manufacturing a device to which nonlinear elements are connected, the matrix substrate before assembly is removably held and the pixel electrodes on the substrate are opposed to the electrodes on the transparent bottom plate of the test container with a predetermined distance maintained. An active matrix liquid crystal display device characterized in that a voltage is applied between both electrodes after the space between both electrodes is filled with liquid crystal for inspection, and a defective part of a matrix substrate is detected from an abnormality in the change in light transmittance of the liquid crystal. manufacturing method.