JPH09258267A - Liquid crystal display device and defect correction method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device on in which a bright spot is inconspicuously corrected eve after the assembly of the device completed, and to provide a defect correction method therefor. SOLUTION: A mask 12 corresponding to a light spot pixel 10 is provided on a driving substrate 3 side. A short-wavelength laser beam A of, for example <=400nm is generated by a laser oscillator and is radiated through the mask 12. Since the beam A has an absorbing wavelength against an ITO film of the pixel 10, only the ITO film of the pixel 10 is efficiently destructed. Thus, the bright spot of a normally black system liquid crystal display device is converted into a demerit defect and the defect correction is efficiently conducted for the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a defect repairing method thereof, and more particularly, it is preferable to convert a bright spot defect formed in a liquid crystal display device into a demerit defect by a short wavelength laser beam. The present invention relates to a liquid crystal display device ensuring display quality and a defect repairing method thereof.

[0002]

2. Description of the Related Art Liquid crystal display devices are characterized by a flat structure and low power consumption, and are being put to practical use and becoming widespread in liquid crystal application equipment represented by video cameras equipped with a liquid crystal monitor, televisions and the like. FIG. 4 is a diagram showing the basic structure of the liquid crystal display device according to the present invention. The liquid crystal display device 1 in the figure is roughly composed of a counter substrate 2 and a drive substrate 3. On the counter substrate 2, a color filter CF (in the case of a color liquid crystal panel), a black matrix BM, and a transparent electrode 2A serving as a pixel electrode are formed of an ITO (Indium-Tin Oxide) film or the like. The drive substrate 3 has a thin film transistor (hereinafter, simply referred to as “TF”) for controlling each image.
T)) and the transparent electrode 3A are formed. A liquid crystal display device having such a structure is called an active matrix type. The liquid crystal display device which is the object of the present invention is not limited to this structure and is merely an example.

The two glass substrates are arranged to face each other with a predetermined gap therebetween, and are joined by a seal material 5 with a spacer 4 sandwiched therebetween. That is, in the liquid crystal display device 1, after maintaining the cell gap by the spacer 4, the liquid crystal injection hole is secured and the periphery is adhered by the sealing material 5. In a relatively small liquid crystal display device, the cell gap may be maintained only by the sealing material 5 without sandwiching the spacer 4.
Then, liquid crystal is injected from an injection hole (not shown) to form a liquid crystal layer 6, and two polarizing plates (not shown) are integrally laminated on both surfaces of these glass substrates to complete the liquid crystal display device 1. To be done.

To briefly explain the operation of the liquid crystal display device 1 having such a configuration, the counter substrate 2 and the drive substrate 3 described above are used.
The alignment film (not shown) formed on the substrate is subjected to rubbing treatment by a predetermined means, and the liquid crystal layer 6 is twisted by 90 degrees and aligned by the action of the rubbing. The liquid crystal layer 6 has optical rotatory power, and when no voltage is applied, the light emitted by the backlight (not shown) propagates along the liquid crystal molecule axis in the liquid crystal cell, and the plane of polarization rotates 90 degrees. Two polarizing plates are arranged in parallel along this optical rotation direction (normally black method), and the incident light is not transmitted as it is and black display is performed. When a voltage equal to or higher than the threshold value is applied to the liquid crystal 6, light is transmitted through the liquid crystal cell to develop a color according to the color filter CF formed on the counter substrate 2.

By the way, in such a liquid crystal display device, when a TFT is broken or a voltage application line is short-circuited, a so-called bright spot defect in which light always passes through the polarizing plate occurs. That is, the bright spot defect is a defect that allows light to pass through even in the mode of blocking light. For example, in the case of the normally black method, black display is performed when the voltage is off, so that the TFT is destroyed and it becomes inoperative. In this state, light is transmitted as it is, and a bright spot defect occurs. When such a bright spot defect occurs, the image quality is significantly deteriorated. In particular, bright spot defects that leak light are conspicuous, so that the degree of image quality deterioration is remarkable, and there are several bright spot defects in the liquid crystal display device, and the entire panel becomes defective, resulting in a decrease in production efficiency.

However, such a liquid crystal display device can inspect a defective portion only after the liquid crystal cell is completed. Further, in order to deal with such a defect, a defect repairing method of irradiating a bright spot defect with a laser beam to damage a TFT, a polarizing plate, or the like and blocking light is also proposed. There is a problem that the liquid crystal or the like is damaged, and the reliability of defect correction cannot be ensured.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to avoid damage to the conventional liquid crystal display device and the liquid crystal display device in the defect correction thereof, and to provide the liquid crystal display device. It is an object of the present invention to provide a liquid crystal display device capable of easily correcting defects even after completion of, and a defect repairing method thereof.

[0008]

In order to solve the above-mentioned problems of the present invention, the following means have been taken. That is, the defect repairing method for a liquid crystal display device of the present invention includes a transparent electrode arranged in a matrix on the substrate, a drive substrate having a means for driving the transparent electrode in a normally black method, and a counter substrate. In the defect repairing method for a liquid crystal display device comprising
A step of masking the transparent electrode on which the bright point defect is formed, a step of irradiating a short wavelength laser beam of, for example, 400 nm or less through this masking, and a transparent electrode on which the bright point defect is formed by the short wavelength laser beam. And a step including a step of destroying.

According to the liquid crystal display device and the defect repairing method thereof of the present invention, the liquid crystal display device, which has a bright spot defect after the assembly of the liquid crystal display device and deteriorates the display quality, has a shortness of, for example, 400 nm or less. Irradiation with a wavelength laser beam was performed to convert the bright spot defect into a demerit defect. That is, an ITO film is generally used as a transparent electrode in a liquid crystal display device. The transmittance characteristic of this material is such that it is transparent in the visible light region but exhibits absorption in the short wavelength region of 400 nm or less. So 400
By irradiating a bright spot defect portion of a normally black type liquid crystal display device with a short wavelength laser beam of nm or less,
Only the ITO film that applies an electric field to the liquid crystal can be destroyed. As a result, the electric field is not applied to the bright spot defect portion of the normally black type liquid crystal display device, and the bright spot defect can be converted into the demerit defect. In addition, according to the defect repairing method for a liquid crystal display device of the present invention, a short wavelength laser beam is irradiated with 40
Since the laser beam of 0 nm or less is used, the bright spot defect portion can be corrected inconspicuously without damaging the driving substrate, the liquid crystal, or the like.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings.

First, the sectional structure of the liquid crystal display device of the present invention will be described with reference to FIG. FIG. 1 is a schematic sectional view showing the basic structure of a liquid crystal display device of the present invention. The same parts as those of the conventional liquid crystal display device will be denoted by the same reference numerals.

The liquid crystal display device of the present invention in FIG. 1 is constructed by sandwiching a liquid crystal layer 6 between a counter substrate 2 and a drive substrate 3. In the liquid crystal display device of the present invention, bright spot pixels 10 may occur together with normal pixels 11. When the bright spot pixel 10 is generated, a defect is corrected by a method described later, and the bright spot pixel is converted into a deduction pixel to make it inconspicuous.

As described above, the bright spot pixel is converted into the demerit pixel by the method for correcting defects of the liquid crystal display device of the present invention, so that it is possible to remedy a defect in which the entire liquid crystal cell is defective due to the bright spot pixel in the past. Can be However, before the completion of the liquid crystal display device, since the location of the bright spot pixel cannot be known, it cannot be changed to the demerit pixel. In the present invention, this bright spot defect is discriminated after the liquid crystal display device is completed, and the spot is irradiated with a short wavelength laser beam of, for example, 400 nm or less that the ITO film of the transparent electrode has absorption characteristics. Destroy the ITO film. This allows
In a normally black type liquid crystal display device, a bright spot defect can be converted into a demerit defect. The liquid crystal display device of the present invention thus completed is operated as described above.

Next, the principle of the liquid crystal display device and its defect repairing method of the present invention will be described by exemplifying the light transmission characteristics of the ITO film actually used for the transparent electrodes of the liquid crystal display device in FIG. FIG. 2 shows ITO used in the liquid crystal display device of the present invention.
It is a waveform diagram which shows the spectrum characteristic of a film | membrane and a laser wavelength.

As is apparent from FIG. 2, the ITO film actually used as the transparent electrode of the liquid crystal display device at present is transparent in the visible light region but shows absorption in the short wavelength region of 400 nm or less. There is. Therefore, by applying an extremely strong light such as a laser beam with respect to this absorption wavelength, only the ITO film can be efficiently destroyed. That is, the liquid crystal and materials other than the transparent electrode in the driving substrate are not affected because they transmit shorter wavelengths than the ITO film, and the ITO film alone can be destroyed efficiently.

Further, the liquid crystal display device of the present invention and the defect repairing method thereof will be described with reference to FIG. 3A and 3B are process diagrams showing a liquid crystal display device and a defect repairing method therefor according to the present invention. FIG. 3A is a sectional view showing a defect repairing process, and FIG. 3B is a sectional view showing a defect repairing process.

The defect repairing method for a liquid crystal display device according to the present invention comprises:
As shown in FIG. 3A, a mask 12 corresponding to the bright spot pixel 10 is provided on the drive substrate 3 side of the liquid crystal display device, and a semiconductor laser oscillation via an excimer laser and a wavelength conversion element via the mask 12. For example, from a machine (not shown)
A short wavelength laser beam A having a wavelength of 00 nm or less is oscillated and irradiated. The short wavelength laser beam A of the laser oscillator is set in advance so as to obtain an optimum intensity. Since this short wavelength laser beam has an absorption wavelength with respect to the ITO film of the bright spot pixel 10, only the ITO film of the bright spot pixel 10 can be efficiently destroyed (see FIG. 3B). In addition,
In the defect repairing method for a liquid crystal display device according to the present invention, the drive substrate 3 is used.
Although the short-wavelength laser beam A is irradiated from the side, it goes without saying that irradiation may be performed from the counter substrate 2 side.

In a normally black type liquid crystal display device, an electric field is applied from the transparent electrode to the liquid crystal to display a white color. Therefore, if the transparent electrode to which the electric field is applied is broken, the electric field is not applied to the black color. Will be displayed. As a result, the bright spot defect can be converted into the demerit defect and the defect of the liquid crystal display device can be efficiently corrected. Alternatively, the short-wavelength laser beam A may be directly applied to the bright spot pixel 10 without applying the mask 12 after detecting a defective pixel by applying a drive signal to the transparent electrode, for example.

The present invention is not limited to the above embodiment,
Various embodiments can be adopted. Although the active matrix type liquid crystal display device has been illustrated in the present embodiment, it can be applied to other liquid crystal display devices such as a simple matrix type liquid crystal display device and a ferroelectric type liquid crystal display device. The method and structure are not limited. Further, it goes without saying that the present invention can be developed into various forms within the scope of its technical idea.

[0020]

As described above, according to the liquid crystal display device and the defect repairing method of the present invention, the normally black method causes a bright spot defect after the completion of the assembly of the liquid crystal display device and deteriorates the display quality. Since the liquid crystal display device of No. 1 is irradiated with a short wavelength laser or the like to convert the bright spot defect into a demerit defect, the bright spot defect can be easily and inconspicuously corrected even after the liquid crystal display device is assembled. Is possible and useful.

Further, in the defect repairing method of the liquid crystal display device of the present invention, since the defect repairing is performed by irradiating the short wavelength laser having the absorption wavelength of the ITO film which is the pixel electrode, the driving substrate or the liquid crystal itself is damaged. It is possible to correct the defect without giving.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a basic configuration of a liquid crystal display device of the present invention.

FIG. 2 is a waveform diagram showing spectrum characteristics of an ITO film and a laser wavelength used in the liquid crystal display device of the present invention.

3A and 3B are process diagrams showing a liquid crystal display device and a defect repairing method therefor according to the present invention. FIG. 3A is a sectional view showing a defect being repaired, and FIG. 3B is a sectional view showing a condition after the defect is repaired. .

FIG. 4 is a schematic sectional view showing a basic configuration of a liquid crystal display device according to the present invention.

[Explanation of symbols]

1 ... Liquid crystal display device, 2 ... Counter substrate, 3 ... Drive substrate, 4 ...
Spacer, 5 ... Sealing material, 6 ... Liquid crystal layer, 10 ... Bright pixel, 11 ... Normal pixel, 12 ... Mask

Claims (4)

[Claims] 1. A defect of a liquid crystal display device comprising a transparent electrode arranged in a matrix on a substrate, a driving substrate having a driving means for driving the transparent electrode by a normally black method, and a counter substrate. In the correction method, a step of masking the transparent electrode having a bright spot defect formed thereon, a step of irradiating a short wavelength laser beam through the masking, and a transparent electrode having a bright spot defect formed by the short wavelength laser beam. A method of repairing defects in a liquid crystal display device, the method including a step of destroying. 2. The short wavelength laser beam is, in particular, 400
A laser beam having a wavelength of nm or less.
A method for correcting a defect in a liquid crystal display device according to item 1. 3. The defect repairing method for a liquid crystal display device according to claim 1, wherein the destruction step is performed by directly irradiating the transparent electrode having the bright spot defect without using the masking. . 4. A liquid crystal display device, wherein a defect is repaired by the defect repairing method for a liquid crystal display device according to claim 1.