JPH10170962A - Liquid crystal display device and defect correction method for the device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the correction section to become a black spot and to reduce the sense of incongruity with respect to the surrounding pixels by diffusing, reducing and correcting the light beams, which are made incident on a spot correction section. SOLUTION: When a spot correction section 16 is irradiated with laser beams 10 in the direction indicated by an arrow 'I', the section 16 is laser-etched and a rough surface 17 having fine raggedness is formed on the etching bottom surface of a glass substrate 2, i.e., the bottom surface of a recessed part 18. Thus, if the roughened section is irradiated with the light beams from a light source, irradiating light beams (illuminating light beams) 40 are diffused by the surface 17 and the luminance level of the spot pixels located on the same path is reduced to the level having no difference with respect to the luminance level of the surrounding normal pixels on the display screen. Thus, the levels of gradation of the spot pixels and the surrounding pixels are made similar on the display screen and the color of the surrounding pixels is blurred with respect to the spot pixels by the infiltrated light beams from the surrounding pixels. Thus, the correction is made for the spot pixels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates and picture elements for display are arranged in a matrix, and a display is performed from the back of the transmissive liquid crystal panel. The present invention relates to a liquid crystal display device having light source means for irradiating illumination light for use in a liquid crystal display, and a defect correction method for correcting a bright spot defect generated in a liquid crystal panel of the liquid crystal display device.

[0002]

2. Description of the Related Art As an example of this type of liquid crystal display device, there is an active matrix drive type liquid crystal panel used for a projection device. In this liquid crystal panel, a TFT (thin film transistor) is connected to pixel electrodes arranged in a matrix on one of a pair of glass substrates to be bonded, and the switching operation of the TFT causes each pixel electrode to be connected. The display operation is performed by selecting or not selecting.
For this reason, a high-quality display can be realized without generating crosstalk at the time of non-selection which is a disadvantage of the simple matrix.

Since a TFT has a multilayer structure in which a gate electrode, a source electrode, a drain electrode and the like are laminated on a glass substrate, a step of laminating these metal thin films on a glass substrate and a step of patterning the metal thin film Is repeatedly performed. Therefore, in order to manufacture a complete TFT without any defect, a great effort is required to maintain and control various conditions in the manufacturing process.

[0004] Therefore, in some cases, defective TFTs for which normal TFT characteristics are not obtained may occur. If a defect can be repaired, it is repaired using each repair technique according to the content of the defect. . As an example of such a defect of the TFT, a pixel corresponding to a pixel electrode connected to the TFT becomes a luminescent spot on the display screen when the display cannot be repaired and the display is driven. There are perceived bright spot defects.

FIGS. 7 and 8 show an example of a conventional method of correcting the bright spot defect. The method shown in FIGS. 7 and 8 is based on the method of opaque light shielding on the surface of the glass substrate 2 corresponding to the bright spot picture element 5 of the display panel 1. A method of forming a film 6 and reducing the light incident on the bright spot picture element 5 from a light source (not shown) to correct the bright spot picture element inconspicuously is adopted.

Here, the portion corresponding to the bright spot picture element 5 on the glass substrate 2 on which the opaque light-shielding film 6 is formed, that is, the correction location, is the same as the bright spot picture element 5 and the incident path of the illumination light from the light source. The surface position of the glass substrate 2 is selected. More specifically, the surface position of the glass substrate 2 on the path A passing through the bright spot picture element 5 in the light flux that is incident on the display panel 1 from the light source through the condenser lens 7 and converged on the projection lens 8 is determined. Say. FIG. 8 schematically shows that the bright spot picture element 5 and the opaque light shielding film 6 are on the same path. The glass substrate 2 is a glass substrate located on the incident side of the two glass substrates 2 and 3 to be bonded, and a liquid crystal as a display medium is sealed between the two substrates.

The opaque light-shielding film 6 is specifically formed as follows. That is, the UV curable resin (ultraviolet curable resin) ink is applied to the fine tip R of the marking needle.
After being adhered to the location (R) and transferred to the above-mentioned repaired location, it is cured by irradiating it with ultraviolet light, thereby bonding to the surface of the glass substrate 2. The opaque light-shielding film 6
Although the size slightly varies depending on the type of liquid crystal panel, it is very small with a diameter of about 100 to 250 μm and a thickness of about 10 μm.

However, the above-described correction method is applied only to a bright spot picture element 5 and a liquid crystal panel for a projection apparatus in which the optical axis of the correction point is always constant. It cannot be applied to those that are not.

[0009]

However, the above-described repair method has the following drawbacks, and therefore, there is a limit in completely eliminating the adverse effect of a bright spot defect in a liquid crystal display device.

Since the opaque light-shielding film 6 does not have a sufficient adhesive force to a glass surface having a very smooth surface, if a cleaning operation such as wiping the surface is performed to remove dirt such as dust,
There is a drawback that the glass substrate 2 is liable to be peeled off from the surface of the glass substrate 2 or to be damaged, and is inferior in reliability.

In the light-shielding characteristic, the opaque light-shielding film 6 almost completely blocks transmitted light, so that when the display screen is a bright video scene, the opaque light-shielding film 6 is visually recognized as a black dot. Has the disadvantage that it is limited to the end positions of the display.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, and it is an object of the present invention to provide a liquid crystal display device in which the reliability of repair is improved and the repair position is not limited, and a method of repairing the defect. Aim.

Another object of the present invention is to provide a liquid crystal display device capable of further improving the dimming effect of illumination light passing through a bright spot picture element and correcting the bright spot picture element with respect to surrounding normal picture elements inconspicuously. And a method for repairing the defect.

[0014]

A liquid crystal display device according to the present invention comprises a transmissive liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates and picture elements for display are arranged in a matrix. A light source means for irradiating illumination light for display from the rear side of the panel, wherein a transparent substrate positioned on the irradiation path of the illumination light for irradiating the picture element having a bright spot defect The surface has a recessed portion narrowed toward the bottom surface side, and the side surface and the bottom surface of the recessed portion are formed into a rough surface shape exhibiting light scattering characteristics, thereby achieving the above object. Is done.

[0015] Preferably, the side surface is formed in a saw-toothed rough surface, and the bottom surface is formed in a mesh-shaped rough surface.

Further, according to the defect correcting method for a liquid crystal display device of the present invention, there is provided a transmissive liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates and picture elements for display are arranged in a matrix. A light source means for irradiating illumination light for display from the rear side of the panel, wherein the illuminating light is applied to the transmissive liquid crystal panel and the bright spots generated in the picture elements are illuminated. A step of detecting a defect, and a recess process narrowing toward a bottom surface near a surface of a transparent substrate located on an irradiation path of the illumination light for irradiating the picture element in which the bright spot defect has occurred. Forming a light scattering region by roughening the side and bottom surfaces of the recessed portion, thereby achieving the above object.

Preferably, a roughening process is performed to form a saw-toothed rough surface on the side surface and form a mesh-like rough surface on the bottom surface.

Preferably, the recessed portion is formed by laser etching using an excimer laser beam, and the surface is roughened.

The operation of the present invention will be described below.

As described above, the recessed portion narrowed toward the bottom surface is formed on the surface of the transparent substrate corresponding to the bright spot picture element, and the light scattering characteristics are provided on the side and bottom surfaces of the recessed portion. When the roughening process shown is performed, the illumination light incident on this portion is diffused in the peripheral direction, so that the illumination light transmitted through the bright spot picture element and formed on the display screen can be reduced. Such a dimming effect is also exhibited when a square-hole-shaped recessed portion is formed near the surface of the transparent substrate and a rough surface is formed on the bottom surface of the recessed portion. Since the scattering surface per light beam of the same light can be made larger than the latter, the light scattering effect that can diffuse the illumination light in the peripheral direction can be improved accordingly. Therefore, according to the former, the dimming effect can be further improved.

As described above, when the illumination light passing through the bright spot picture element is reduced, the luminance level of the bright spot defect is reduced to a level at which it becomes less noticeable with respect to the surrounding picture elements. In addition, since the illumination light is diffused, a part of the illumination light passes through a peripheral pixel adjacent to the pixel having the bright spot defect. Further, when the diffused light passes through the liquid crystal layer, the diffused light is slightly scattered by the liquid crystal layer. Therefore, on the display screen, the density of the picture element having a bright spot defect and the density of the surrounding picture elements become similar to each other, and at the same time, the surrounding picture elements are so-called “ It will be in a "smeared" state. As a result, the presence of the bright spot picture element becomes inconspicuous with respect to surrounding normal picture elements.
That is, the bright spot picture element is corrected.

[0022]

An embodiment of the present invention will be described below. FIG. 1 schematically shows a defect correcting method according to an embodiment of the present invention. A laser beam 10 emitted from an excimer laser oscillator 9 passes through a slit pattern 11 and is reflected by an ultraviolet reflecting mirror 12. , Mounting table 1 via lens 13
The light is condensed and radiated to the bright spot correction unit 16 of the liquid crystal panel 1 set on the liquid crystal panel 4. As shown by oblique lines in FIG. 2, the bright spot correction unit 16 is on the same irradiation path as the bright spot picture element 5 that generates a bright spot with respect to the irradiation light. In addition, the bright spot correction unit 16 of the present embodiment is configured such that the surface of the glass substrate 2 on the side where the illumination light 40 from the light source is incident on the liquid crystal panel 1 among the pair of glass substrates bonded as shown in FIG. Selected near. A color filter 2 is provided on the inner surface of the glass substrate 2 on the incident side.
4 and a black stripe 25 are arranged corresponding to the picture elements, and a counter electrode 26 for applying a voltage to the liquid crystal is provided.

On the other hand, on the inner surface of the glass substrate 27 on the side from which the illumination light 40 is emitted, there are arranged pixel electrodes 28 arranged in a matrix and a TF for switching the power supply to the pixel electrodes 28.
T29 is formed, and a twisted nematic liquid crystal layer 30 twisted and oriented 90 degrees or more is sealed between the two glass substrates 2 and 27. In this embodiment, a liquid crystal panel 1 used in a three-panel projection type liquid crystal display device is exemplified as the liquid crystal panel 1. In this case, the color filters 24 incorporated in the liquid crystal panel 1 have the same color in the panel, and the three liquid crystal panels 1 are combined to perform three primary color full-color displays. Also,
The color filter 24 may be provided outside the glass substrate 2. The incident direction of the laser beam 10 coincides with the incident direction of the illumination light 40 on the liquid crystal panel 1.

The slit pattern 11 is formed with a pattern having a shape in which the outer size of the bright spot correcting section 16 is enlarged, and the laser beam 10 is emitted by the reduced slit exposure through the slit pattern 11. Irradiation is accurately performed at 16 positions. In addition, if such a slit pattern 11 is used, there is an advantage that the rough surface 17 described below can be formed with various uneven steps.
The mounting table 14 is, for example, in a horizontal plane, XY.
The laser beam 10 can be irradiated to a desired bright spot correction unit 16 by moving the mounting table 14 in two orthogonal directions.

The bright spot picture element 5 is detected by irradiating the liquid crystal panel 1 with illumination light from a light source in a previous process, and projecting a display image of the liquid crystal panel 1 in a driving state on a display screen.
This projection image is visually recognized by an inspector.

In the direction indicated by arrow I in FIG.
When the laser beam 10 is irradiated on the laser beam 6, the irradiated portion is laser-etched, and a rough surface 17 having minute unevenness is formed on the bottom surface of the etched portion of the glass substrate 2, that is, on the bottom surface of the concave portion 18. Therefore, when light is emitted from the light source to the surface roughening processing unit, the irradiation light (illumination light) is diffused by the rough surface 17 and the luminance level of the bright spot picture element 5 on the same path is displayed on the display screen. In this case, the brightness level is reduced to a level that is not different from the luminance level of the surrounding normal picture elements 50. In addition, since the irradiated light is diffused and the diffused light is slightly scattered by the liquid crystal layer 30, a part of the illuminating light passes through the surrounding picture element 50 adjacent to the bright spot picture element 5. Then, a component which returns to the bright spot picture element 5 again occurs. Therefore, on the display screen, the gray level of the bright picture element 5 and the gray level of the surrounding picture elements 50 are approximated, and the color of the surrounding picture elements 50 due to the intrusion of light from the surrounding picture elements 50. Becomes “smeared” with respect to the bright spot picture element 5. Therefore, for the above-mentioned reason, it is not recognized as the bright spot picture element 5. That is, the bright spot picture element is corrected.

When the above-mentioned luminance reduction effect is expressed by the amount of light,
Light intensity after roughening is 80% to 1 before irradiation with laser beam 10.
It can be appropriately controlled within a range of about 0%. In this embodiment, 50% ± 10% of the light amount before the laser beam 10 irradiation.
% To obtain an excellent effect of correcting bright spot defects.

The above surface roughening treatment may be performed by laser etching using a CO2 laser, or by engraving using a diamond needle or a needle made of cemented carbide. There are the following advantages over these methods.

First, as compared with the tactile engraving method, there is an advantage that the rough surface processing is facilitated and the rough surface 17 with high accuracy of the uneven shape can be formed.

On the other hand, when compared with CO ₂ lasers, since CO ₂ laser etching is thermal processing, but will give thermal damage to the glass surrounding the bright point correction section 16, thus according to the excimer laser etching There is an advantage that no significant thermal damage is caused. Therefore, for the above reasons, the repairing method for forming the rough surface 17 by excimer laser etching is the most preferable in implementing the method.

In the excimer laser etching, ArF having an oscillation wavelength of 193 nm and an oscillation wavelength of 24
KrF having a wavelength of 8 nm, XeCl having an oscillation wavelength of 308 nm, or the like is used. The pulse energy of the excimer laser oscillator 9 and the surface roughness of the rough surface 18 differ depending on the type of the sealing gas. From the experimental results, it was confirmed that excimer laser etching using KrF as the sealing gas is the most preferable correction method.

That is, in order to examine the optimal excimer laser gas type for roughening the surface to diffuse the light incident on the bright spot correction unit 16, the type of the sealing gas was changed and the experiment was performed under the same pulse shot conditions. 17 has a surface roughness of KrF
Was the coarsest, followed by ArF. On the other hand, when XeCl was used as the sealing gas, the surface roughening process could not be performed because the laser beam 10 transmitted through the glass surface. Then, the rough surface 17 by KrF, whose surface roughness was the most roughened, was obtained.
By observing the sample with a microscope, it was confirmed that the rough surface 17 had a sand-like shape and transmission of transmitted illumination was sufficiently suppressed.

Therefore, when the entire area of the bright spot correction section 16 shown in FIG. 2 was uniformly irradiated with a laser beam using the KrF to confirm the bright spot disappearing effect, the brightness level of the bright spot was the same as that of the normal picture element. It was confirmed that the light was dimmed to a low level not different from the bright spot level.

By the way, as a future technical trend of this type of projection device, it is expected that a metal halide lamp, which is a light source, will have a higher brightness. It is necessary to further improve the dimming effect, and there is a limit in the above-described roughening treatment.

Therefore, in the present invention, as shown in FIGS. 4 and 5, a concave portion 18A in the shape of a quadrangular pyramid narrowing toward the bottom is formed on the surface portion of the glass substrate 2 corresponding to the bright spot picture element 5, That is, it is formed in the bright spot correcting portion 16 and the concave portion 18
The rough surfaces 17A and 17B are formed on the bottom surface and the side surface (inclined surface) of A, respectively, so that the illumination light transmitted through the bright spot picture element 5 is further reduced. Such recess 18A, rough surface 1
7A and 17B are formed as follows by etching using an excimer laser.

First, after setting the reduction ratio of the laser beam 10 to be reduced and exposed through the slit pattern 11 and the energy density of the laser beam 10 to appropriate values, the excimer laser oscillator 9 applies the laser beam 10 to the luminescent spot correcting section 16. To thereby form the concave portion 18A. Next, as shown in FIG. 6, a mesh-shaped slit pattern mask 60 having round holes 61 formed therein is inserted into the slit pattern 11, and in this state, the laser beam 10 is irradiated with the concave portions 18.
A is irradiated. As a result, a sawtooth-shaped rough surface 17B is formed on the side surface of the recess 18A, and at the same time, a mesh-shaped rough surface 17A is formed on the bottom surface.

When the concave portion 18A is formed and the rough surfaces 17A and 17B are formed, the scattering surface of the illumination light incident on the bright spot correcting portion 16 per the same light flux is changed to the concave portion 18 and the rough surface shown in FIG. 17, the light scattering effect can be improved by that amount, which can diffuse the illumination light in the peripheral direction. Therefore, the dimming effect can be improved.

As the specifications of the concave portion 18A, it is preferable that the vertical and horizontal dimensions of the outermost surface are 250 μm × 250, the inclination angle is 5 to 20 degrees, and the depth is 200 μm or more. By the way, it was confirmed that the dimming effect can be set to about 80% or more according to the concave portion 18A having such specifications. On the other hand, the dimming effect in the case of the concave portion 18 in FIG. 3 was about 50%. Therefore, according to the concave portion 18a and the rough surfaces 17A and 17B, it is possible to cope with future technical trends of the projection device.

The liquid crystal panel to which the present invention is applied is 3
The present invention is not limited to the one used for the single panel type projection type liquid crystal display device, and is a direct-view type liquid crystal panel in which three primary color filters of R (red), G (green), and B (blue) are alternately arranged. Can be similarly implemented. It has been confirmed that even if the picture elements adjacent to the bright picture element have different colors, the effect of eliminating the bright picture element using the color bleeding phenomenon can be sufficiently obtained.

[0040]

According to the present invention described above, there are the following advantages over the above-mentioned conventional correction method.

Light shielding and dimming characteristics. According to the conventional method, since the incident light incident on the correction unit is completely shielded, the correction part is limited to the end of the display because the correction unit becomes a black point, whereas according to the present invention,
Since the incident light is corrected by diffusion dimming, it is possible to prevent the correction portion from becoming a black spot, and, as a matter of course, the surrounding picture elements become “smeared” with respect to the bright spot picture elements.
It can reduce the sense of incongruity with surrounding picture elements visually.

Further, if the recessed portion is formed in the shape described in claims 1 to 5, the dimming effect can be further improved, so that it is possible to cope with future technical trends of the projection apparatus.

Correction reliability. Since the opaque light-shielding film is not used, it is natural that the film does not peel off or drop off during cleaning or the like, and the reliability can be improved.

Corrected size, corrected shape. According to the conventional method, if a stable bonding of the opaque light-shielding film is performed, the bonding shape is inevitably limited to a circular shape, which makes it difficult to deal with a square bright spot picture element. In the etching process using the excimer laser beam described in 6, the shape of the bright spot picture element can be easily handled by using a slit pattern. Furthermore, since various types of concave shapes and rough surface shapes can be formed, there is an advantage that the dimming degree can be selected. In addition, there is an advantage that processing accuracy can be improved particularly by etching using an excimer laser.

[Brief description of the drawings]

FIG. 1 is a drawing schematically showing a defect repair method using an excimer laser device.

FIG. 2 is a drawing showing that a bright spot picture element and a bright spot correction unit are on the same irradiation path for illumination light.

FIG. 3 is a sectional view showing a liquid crystal panel having a rough surface formed by excimer laser etching.

FIG. 4 is a partially enlarged cross-sectional view showing a liquid crystal panel having a concave portion and a rough surface capable of further improving the dimming effect.

FIG. 5 is a view in the direction of arrow A in FIG. 4;

FIG. 6 is a view showing a slit pattern mask used for excimer laser etching.

FIG. 7 is a side view showing a conventional method.

FIG. 8 is a drawing similar to FIG. 2 in a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2 Incident side glass substrate 5 Bright spot picture element 9 Excimer laser oscillator 10 Laser beam 11 Slit pattern 14 Mounting table 16 Bright spot correction part 17, 17A, 17B Rough surface 18, 18A Depression 30 Liquid crystal layer 40 Illumination light 50 Surrounding normal picture elements

Claims (5)

[Claims] 1. A transmissive liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates and picture elements for display are arranged in a matrix, and illumination light for display is illuminated from the back of the transmissive liquid crystal panel. A liquid crystal display device having a light source means that emits a bright spot defect. A liquid crystal display device in which a recessed portion is formed, and a side surface and a bottom surface of the recessed portion are formed in a rough surface shape exhibiting light scattering characteristics. 2. The liquid crystal display device according to claim 2, wherein the side surface is formed in a saw-toothed rough surface, and the bottom surface is formed in a mesh-shaped rough surface. 3. A transmissive liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates and picture elements for display are arranged in a matrix, and illumination light for display is illuminated from the back of the transmissive liquid crystal panel. A defect correcting method for a liquid crystal display device having a light source means for detecting a bright spot defect occurring in the picture element by irradiating the illumination light to the transmissive liquid crystal panel; Forming a recessed portion narrowing toward the bottom side on the surface of the transparent substrate positioned on the irradiation path of the illumination light for irradiating the generated picture element; and a side surface of the recessed portion. And forming a light scattering region by roughening the bottom surface. 4. The defect correcting method for a liquid crystal display device according to claim 3, wherein a roughening process for forming a saw-toothed rough surface on the side surface and forming a mesh-like rough surface on the bottom surface is performed. 5. The defect correcting method for a liquid crystal display device according to claim 3, wherein the recessed portion is formed by laser etching using an excimer laser beam, and the surface is roughened.