JPH03265820A - Liquid crystal display and production thereof - Google Patents

Abstract

PURPOSE:To allow the easy correction of the void to be detected after the production of a liquid crystal panel by roughening the surface of the substrate in the void part of the liquid crystal panel thereby making this surface opaque. CONSTITUTION:A back light 20 is projected from the side of a glass substrate 11 and an image is displayed on the liquid crystal panel 10 to clarify the position of the void. A stainless steel mask having the aperture pattern of the same size as the size of one picture element of the panel 10 is brought into tight contact with the glass substrate 12. The void part 30 and the aperture pattern of the mask are registered at this time. Alumina or carborundum powder is then sprayed by a sandblasting method using gaseous nitrogen onto the mask surface to roughen the glass surface facing the opening pattern of the mask. The light of the back light 20 is, therefore, the refracted and scattered in the roughened surface part and the brightness appearing to the eyes is decreased by >=(1 to 2) digits. The void detected after the production is easily corrected in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure for correcting white defects in a liquid crystal panel and a manufacturing method thereof.

[Conventional technology]

As countermeasures against defects in liquid crystal panels for liquid crystal displays, various methods are known, such as pasting defects that occur during the manufacturing process, or using redundant methods to make process defects invisible or difficult to see as images on the display. There is.

On the other hand, there are correction methods for defects detected after manufacturing, such as trimming the electrode wiring in the defective area.

A similar product is a photomask, and one of its repair devices is a device that uses focused ion beam illumination to sputter white defect areas on the substrate surface to make them opaque. Regarding this device, Nikkei Microdevice July 1985 (
It was introduced in the newsletter of issue 241 of the first issue.

[Problem to be solved by the invention]

2. Countermeasures against defects in the manufacturing process in the prior art cannot deal with defects detected after manufacturing.

Laser 1 - Rimming, which is used to correct defects detected after manufacturing, requires setting the trimming position on the pattern in the liquid crystal panel in advance, and there are constraints on the pixel design, and there are also restrictions on the trimming position on the substrate. Because the layers are limited,
It cannot be applied to all layers on the substrate. Furthermore, the cutting after trimming may be included in the liquid crystal panel, which may cause deterioration of the reliability of the liquid crystal panel.

Although the focused ion beam repair method for photomasks can also be applied to repair liquid crystal panels, it requires expensive equipment equipped with an evacuation system and is not practical. This is because the correction of the mask requires one to two orders of magnitude finer processing than the correction of the liquid crystal panel.

An object of the present invention is to provide a method for extremely easily correcting defects detected after manufacturing a liquid crystal panel.

[Means to solve the problem]

1] White defect detected by assembling a liquid crystal panel and displaying an image (a defect where an area that should originally be displayed as black is displayed as white or the color passed through a color filter) is a defect that is detected by assembling a liquid crystal panel and displaying an image in order to make a distant relative of the target of 2.1. The surface of the substrate is roughened in the area where this occurs. This surface roughening can be done in a size equivalent to the pixel size (for example, 100 μm opening), and does not require finer refinement like in the case of photomask modification, so irradiation with a laser beam in the air or sandblasting is used. be able to.

[Effect]

In a liquid crystal display, a white defect in normally black mode is very noticeable and unsightly, even if it is a point defect and occupies a small proportion of the entire display area. This looks like a shining star in the night sky, and is unacceptable as a display product. However, by roughening the substrate surface in this white defect area, the light to the backlight 1 is refracted and scattered at the rough surface area, reducing the visible luminance by one to two orders of magnitude or more, making it unsightly. can be prevented.

〔Example〕

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

FIG. 1 shows a schematic diagram of a liquid crystal display of the present invention. 1
0 is a liquid crystal panel, which consists of two glass substrates 11 and 12, a liquid crystal 13, and a drive circuit 14. Although not shown in the drawing, the glass substrate includes a liquid crystal element using a thin film transistor, a transparent electrode, an alignment film, and a polarizing film.

Glass beads or glass fibers are attached for adjusting the distance between the color filter and the glass substrate. Reference numeral 20 denotes a backlight, which is comprised of two U-shaped fluorescent lamps 21 and a reflector plate 22. Up to this point, it is the same as a normal liquid crystal display.

In the figure, the x mark 30 in [liquid crystal]-3 indicates a defective portion.

This shows the location where a white defect was detected by the lighting test. Surface portion 3 of the glass substrate corresponding to the defective portion 30
By roughening the surface of the backlight 1, the light from the backlight 1 is refracted and scattered, and the light 33 projected to the outside can be made extremely weak.

The surface roughening of the defective portion of the glass substrate was carried out as follows. Light is emitted from the backlight l-20 from the back surface of the liquid crystal panel 10 (the side on the glass substrate 1 in the drawing). Next, an image is displayed on the liquid crystal panel 10 to clarify the location of the defect. A stainless steel mask with an open pattern of the same size as the ↑ pixel of the liquid crystal panel is brought into close contact with the glass substrate]2. At this time, the defective portion 31 and the opening pattern of the stainless steel mask are made to coincide. This alignment 1- has a size that can be viewed with the naked eye. Next, 4000 mesh of alumina or carporundum powder is blown onto the mask surface using a sandblasting method with nitrogen gas at 5 atmospheres, so that the glass surface facing the lobe pattern between the masks can be roughened. After this, a coloring agent such as ink may be impregnated into the roughened portion. Because the surface is roughened, the adhesion force of the colorant is much greater than that on a smooth surface, resulting in a long life. The depth of the surface roughening is preferably three times or more the defect size in order to increase the scattering of transmitted light.

Another method for roughening the surface is the laser beam 11 irradiation method. , the surface of the glass substrate is roughened by focusing a XeCQ excimer laser to the size of a defective pixel and irradiating the panel. 20 beams with an energy density of 0.3 J/-
By focusing on the 0 μm aperture and irradiating 3 pulses, the glass surface can be heated to about 4. A rough surface with a depth of 0 μm can be formed. In the case of laser beam 13 irradiation, it is necessary to use a mask. The coloring agent is then applied in the same manner as described above.

Assemble the liquid crystal display by installing backlights I to 20 in their normal positions.

Incidentally, the light transmittance of the defective portion could be reduced to 17 to 4% by roughening the surface. This level of reduction makes defects less noticeable, while
It is also possible to identify the N time (when displaying an image). The light transmittance when the colorant is attached is 6 to 1%, which is suitable for cases where the backlight is strong at about 10'12 ux or more.

Although the description above focuses on correction of white defects, it is also possible to perform the above correction on black defects. Moreover, the location where light is scattered due to roughening of the surface or the like may be any part of the optical path from the light source to the eye.

〔Effect of the invention〕

According to the present invention, defects in a liquid crystal panel, particularly white defects, can be easily corrected, which is effective in reducing the cost of liquid crystal displays.

[Brief explanation of drawings]

FIG. 1 shows a schematic diagram of a liquid crystal display of the present invention. 0 part. ・LCD panel, 0 defective part, surface

Claims (1)

[Scope of Claims] 1. A liquid crystal display characterized in that the substrate surface of the white defect portion of the liquid crystal panel is roughened to make it opaque. 2. A method for manufacturing a liquid crystal display, which comprises roughening the substrate surface of the white defect portion of the liquid crystal panel to make it opaque. 3. The method of manufacturing a liquid crystal display according to claim 2, wherein the roughening of the substrate surface is performed by laser beam irradiation or sandblasting. 4. The liquid crystal display according to claim 1, wherein the liquid crystal panel is in a normally black mode, and the white defects are dots.