JPH04353821A - Liquid crystal display device and its defect correcting method - Google Patents

Abstract

PURPOSE:To realize the liquid crystal display device and correcting method which are improved in the reliability of correction of a bright point picture element and do not have the correction position limited. CONSTITUTION:Once a bright point picture element 5 detected, the bright point picture element 5 of a deflection plate 31 positioned on the incidence side of a liquid crystal panel and the periphery of a surface on the same irradiation path are irradiated with the laser beam from an excimer laser oscillator to perform excimer laser etching, thereby forming a recessed part 18 which has a rough surface 17 on its bottom surface at the irradiated position of the deflection plate 31. Consequently, when this device is applied to a projection device, light passed through the bright point picture element 5 is reduced, so the bright point picture element on a display screen is corrected into a state wherein the bright point picture element is inconspicuous as a defect as compared with peripheral normal picture elements.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a transmissive liquid crystal panel in which a liquid crystal is sealed between a pair of transparent substrates sandwiched between a pair of polarizing plates, and display pixels are arranged in a matrix. The present invention relates to a liquid crystal display device having a light source unit that irradiates illumination light for display from the back side of a transmissive liquid crystal panel, and a defect repair method for repairing bright spot defects occurring in the liquid crystal panel of the liquid crystal display device.

0002

2. Description of the Related Art An example of this type of liquid crystal display device is an active matrix drive type liquid crystal panel used in a projection device. In this liquid crystal panel, TFTs (thin film transistors) are connected to picture element electrodes arranged in a matrix on one of a pair of glass substrates to be bonded together, and each picture element electrode is connected by the switching operation of the TFT. Display operations are performed by selecting and deselecting. Therefore, crosstalk during non-selection, which is a drawback of a simple matrix, does not occur, and a high-quality display can be realized.

By the way, since a TFT has a multilayer structure in which a gate electrode, a source electrode, a drain electrode, etc. are laminated on a glass substrate, there are a process of laminating these metal thin films on a glass substrate, and a process of patterning the metal thin film. is repeated. Therefore, in order to manufacture a perfect TFT without any defects, great effort is required to maintain and control various conditions during the manufacturing process.

[0004] Therefore, in some cases, a defective TFT may be generated in which normal TFT characteristics are not obtained, and if the defect is repairable, it is attempted to repair it using the respective repair technology depending on the content of the defect. . An example of such a TFT defect is that it cannot be repaired on the circuit formation pattern, and when the display is driven, the picture element corresponding to the picture element electrode connected to the TFT becomes a bright spot on the display screen. There is a recognized bright spot defect.

One conventional example of a method for correcting bright spot defects is the method shown in FIGS. 11 and 12. In this method, an opaque light-shielding film 6 is formed near the surface of the glass substrate 2 on the incident side corresponding to the bright spot pixels 5 of the liquid crystal panel 1 (hereinafter, this position is referred to as the bright spot defect correction section 6), and thereby the light source ( A method is used to reduce the light incident on the bright spot picture element 5 from the bright spot picture element 5 (not shown) so as to make the bright spot picture element 5 less noticeable.

Here, in 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 modified location, the incident path of the illumination light from the light source is the same as that of the bright spot picture element 5. The surface position of the glass substrate 2 is selected. More specifically, the surface position of the glass substrate 2 on the path A that passes through the bright spot picture element 5 of the luminous flux that enters the display panel 1 from the light source through the condenser lens 7 and is converged on the projection lens 8 is determined. say. FIG. 12 shows a bright spot picture element 5 and an opaque light-shielding film 6.
This diagram schematically shows that they are on the same route. In addition,
The glass substrate 2 consists of two glass substrates 2 and 3 that are bonded together.
This is a glass substrate located on the incident side of the two substrates, and a liquid crystal serving as a display medium is sealed between the two substrates.

Further, the opaque light-shielding film 6 is specifically formed as follows. That is, UV curable resin (ultraviolet curable resin) ink is applied to the tip of the marking needle with a minute radius (
After transferring it to the corrected area, it is cured by irradiation with ultraviolet rays, thereby adhering it to the surface of the glass substrate 2. The size of this opaque light-shielding film 6 varies slightly depending on the model of the liquid crystal panel, but it is extremely small with a diameter of about 100 to 250 μm and a thickness of about 10 μm.

However, the above correction method is only applicable to liquid crystal panels for projection devices where the optical axis of the bright spot picture element 5 and the correction location are always constant, and the viewing angle is constant like a direct view type. It cannot be applied to anything that is not.

[0009]

However, the above-mentioned correction method has the following drawbacks, and there is a limit to completely eliminating the adverse effects of bright spot defects in liquid crystal display devices.

■The opaque light-shielding film 6 does not have sufficient adhesion to the glass surface, which has a very smooth surface, so if cleaning work such as wiping the surface to remove dust and other stains, the glass substrate 2 will be damaged. It is prone to problems such as peeling off from the surface and damage, and has the drawback of poor reliability.

■ In light-shielding properties, this opaque light-shielding film 6
Since it almost completely blocks transmitted light, when the display screen is a bright video scene, the opaque light-shielding film 6 becomes visible as a black dot, which has the drawback that the correction area is limited to the edge position of the display. be.

The present invention solves the drawbacks of the prior art, and provides a liquid crystal display device and a method for repairing defects in a liquid crystal display device, which improves the reliability of correction and does not limit the repair position. The purpose is to

[0013]

[Means for Solving the Problems] In the liquid crystal display device of the present invention, liquid crystal is sealed between a pair of transparent substrates sandwiched between polarizing plates arranged oppositely, and display pixels are arranged in a matrix. In a liquid crystal display device comprising a transmissive liquid crystal panel and a light source means for emitting illumination light for display from the back side of the transmissive liquid crystal panel, the illumination irradiates the pixel in which a bright spot defect has occurred. A recessed portion is formed near the surface of the deflection plate located on the light irradiation path, and the bottom surface of the recessed portion is formed into a rough surface shape exhibiting light scattering characteristics, thereby achieving the above object. be done.

[0014] Furthermore, the method for correcting defects in a liquid crystal display device of the present invention is such that liquid crystal is sealed between a pair of transparent substrates sandwiched between polarizing plates disposed oppositely, and display pixels are arranged in a matrix. A method for correcting a defect in a liquid crystal display device having a transmissive liquid crystal panel and a light source means for emitting illumination light for display from the back side of the transmissive liquid crystal panel, the method comprises: irradiating the transmissive liquid crystal panel with the illumination light; a step of detecting a bright spot defect occurring in the picture element using , forming a recessed part whose bottom surface has a rough surface shape exhibiting light scattering properties, thereby achieving the above object.

[0015] Preferably, a recessed part is formed having a step-like bottom surface formed by alternately forming shallow parts and deep parts. Further, it is preferable to form the recessed portion by excimer laser etching. Furthermore,
It is also possible to form a concave portion not only on the incident side but also on the deflection plate on the output light side.

[0016]

[Effect] As described above, by forming a recessed part near the surface of the deflection plate located on the irradiation path of display illumination light and roughening the bottom surface, the illumination light passing through this part is diffused. be done. Therefore, on the display screen, the brightness level of the bright spot defect is reduced to a level that makes it less noticeable compared to the surrounding picture elements. As a result, the presence of the bright spot picture element becomes inconspicuous compared to the surrounding normal picture elements. In other words, the bright spot picture element has been corrected.

[0017]

[Embodiment] An embodiment of the present invention will be described below.

FIG. 1 schematically shows a defect correction method according to an embodiment of the present invention, in which an excimer laser oscillator 9
The laser beam 10 emitted from the slit pattern 1
1, is reflected by an ultraviolet reflecting mirror 12, passes through a lens 13, and is set on a mounting table 14.
The light is focused and irradiated onto the bright spot correction unit 16. As indicated by diagonal lines in FIG. 2, the bright spot correction unit 16 is located on the same irradiation path as the bright spot picture element 5 that generates the bright spot with respect to the irradiated light.

Further, the bright spot correction unit 16 of this embodiment is shown in FIG.
A pair of glass substrates 2 and 27 are bonded together as shown in
Of the pair of deflection plates 31, 31 disposed on both outer sides of the LCD panel 1, a position near the surface of the deflection plate 31 on the side where the illumination light 40 from the light source is incident on the liquid crystal panel 1 is selected. The deflection plates 31, 31 are formed of dye-based deflection plates such as iodine-based deflection plates, and the bright spot correction unit 1
6 is on the irradiation path of the illumination light 40 that irradiates the bright spot picture element 5 as described above.

Color filters 24 and black stripes 25 are alternately arranged on the inner surface of the glass substrate 2 on the incident side, that is, on the opposing surface. The color filters 24 are all color filters of the same color (in the illustrated example, R (red) color filters), and the color filters 24 and black stripes 25 are arranged corresponding to picture elements. Further, a counter electrode 26 is provided on the inner surface of the color filter 24 and black stripe 25 arranged in this manner. The counter electrode 26 is arranged to apply a voltage to the twisted nematic liquid crystal layer 30 sealed between the pair of glass substrates 2 and 27. Note that the color filter 24
may be arranged on the outer surface side of the glass substrate 2.

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 picture element electrodes 28 arranged in a matrix and a TF for switching the power supply to the picture element electrodes 28.
A twisted nematic liquid crystal layer 30 twisted by 90 degrees or more is sealed between the glass substrates 2 and 27. In this embodiment, the liquid crystal display 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 filter 2 incorporated in the liquid crystal panel 1
4 have the same color within the same panel as described above, and the three liquid crystal panels 1 are combined to perform a full-color display of the three primary colors.

Further, as the liquid crystal panel 1, either a direct view type or a projection type liquid crystal display device can be used.
As a display method, a TFT drive type, an MIM drive type, a duty drive type, etc., which utilize the twisted alignment effect of the polarizing film 31 and liquid crystal molecules, are widely applicable. Furthermore, in addition to the above structure, a glass substrate with a TFT is provided on the incident side of the illumination light 40,
Bright spot correction unit 1 on the glass substrate side with color filter on the output side
It is good also as a structure which forms 6.

Note that the slit pattern 11 is formed with a pattern in which the outer size of the bright spot correction section 16 is enlarged, and the laser beam 10 is directed to the bright spot correction section by the reduction slit exposure through the slit pattern 11. 16 positions are irradiated with high precision. 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. In addition, the mounting table 14 may be placed in the X-Y position in a horizontal plane, for example.
It is movable in two orthogonal axes directions, and by moving the mounting table 14, the laser beam 10 can be irradiated onto a desired bright spot correction section 16.

In addition, the detection of the bright spot picture elements 5 is carried out by irradiating the liquid crystal panel 1 with illumination light 40 from a light source and projecting the display image of the liquid crystal panel 1 in the driving state onto the display screen in the previous step. This is done by visually checking the projected image.

As shown in FIG. 3, the correction process for the bright spot correction section 16 is performed by irradiating the bright spot correction section with a laser beam 10 from the direction of arrow I1. As a result, the irradiated portion is laser-etched, and a rough surface 17 consisting of minute irregularities is formed on the bottom surface of the etched portion of the deflection plate 31, that is, on the bottom surface of the recess 18. Therefore, from now on, when illumination light 40 is irradiated from the light source to this roughened surface from the direction I2, which is the same as the direction of arrow I1, the illumination light 40 is diffused by the rough surface 17, and then
The light is emitted towards the display screen. Therefore, depending on the degree of the rough surface shape, the amount of direct light reaching the observer from the bright spot picture element 5 on the same path decreases, and the brightness level of the bright spot picture element 5 on the display screen is lower than that of the surroundings. The brightness level is reduced to a level that is no different from the brightness level of the normal picture element 50. As a result, it is no longer recognized as a bright spot picture element. That is, bright spot picture element 5
This means that the bright spot picture element 5 has been corrected due to the dimming effect.

Expressing the above luminance reduction effect as a change in the amount of direct light reaching the observer, it is possible to appropriately control the amount of light after surface roughening within a range of approximately 80% to 10% of the amount before irradiation with laser beam 10. It is. In this embodiment, the light intensity is reduced to approximately 50%±10% of the light intensity before irradiation with the laser beam 10, thereby obtaining a good bright spot defect correction effect. Note that since the deflection plates 31 are arranged on both the incident side and the output side, if it is desired to increase the amount of brightness attenuation described above, the recesses 18 and the rough surfaces 17 may be formed in both the deflection plates 31, 31.

The above-mentioned surface roughening treatment may be performed by laser etching using a CO2 laser, or by engraving using a diamond needle or a cemented carbide needle, but according to excimer laser etching, It has the following advantages over these methods.

First, compared to the touch engraving method, there is an advantage that the roughening process is easier and the roughened surface 17 can be formed with high precision in the uneven shape.

On the other hand, compared to CO2 laser, CO2
Since laser etching is thermal processing, the bright spot correction part 16
This would cause thermal damage to the surrounding area, but excimer laser etching has the advantage of not causing such thermal damage. Therefore, for the above reasons, the correction method of forming the rough surface 17 by excimer laser etching is the most preferable method to implement.

Furthermore, in excimer laser etching, ArF with an oscillation wavelength of 193 nm and ArF with an oscillation wavelength of 24 nm are used as filler gas.
KrF with a wavelength of 8 nm, XeCl with an oscillation wavelength of 308 nm, etc. are used, and the pulse energy of the excimer laser oscillator 9 differs depending on the type of the filled gas, and the surface roughness of the rough surface 18 also differs. The experimental results confirmed that excimer laser etching using KrF as a filler gas is the most preferable repair method.

That is, in order to examine the type of excimer laser gas that is most suitable for roughening the surface by attenuating the light emitted from the bright spot correction section 16, experiments were conducted under the same pulse shot conditions with different types of gas filled. The surface roughness of the rough surface 17 is K
rF was the coarsest, followed by ArF. When the roughened surface 17 made of KrF, which had the highest surface roughness, was observed under a microscope, it was confirmed that the roughened surface 17 had a sand grain shape and that transmission of transmitted illumination was sufficiently suppressed.

Therefore, when we used this KrF to uniformly irradiate a laser beam over the entire area of the bright spot correction unit 16 shown in FIG. It was confirmed that the brightness had been reduced to a low level that was no different from the bright spot level.

FIG. 4 shows a variation of the surface roughening treatment shown in FIG. A roughening process is performed to form the surface 17. Also in this modification, if you want to increase the amount of brightness attenuation, both deflection plates 31, 3
The recess 18a and the rough surface 17 may be formed in the recess 18a and the rough surface 17.

5 and 6 show a second embodiment of the present invention. In this second embodiment, a large number of concave portions 19 (shaded portions in the figure) and convex portions are formed within a minute area of the bright spot correction portion 16. Part 20 (
A correction method is used in which a rough surface 17 is formed on the bottom surface of the recess 19 and the surface of the convex portion 20. The micro area mentioned above differs depending on the model of LCD panel, but the small one is 120 x 100 μm, and the large one is 25 μm.
It is approximately 0×230 μm.

According to the second embodiment, since the surface roughening treatment is performed twice, there is an advantage that the incident light from the light source can be further diffused and attenuated. This second embodiment is convenient for responding to future technological trends in projection devices. In other words, as future technological trends are expected to increase the brightness of metal halide lamps as light sources, it is necessary to further improve the bright spot brightness reduction effect in the roughened surface treatment area to accommodate this. This is because there is.

Note that this correction method is performed by irradiating the bright spot correction section 16 with the laser beam 10 in the following procedure. That is, first, the laser beam 10 is uniformly irradiated over the entire area of the bright spot correction section 16, and then the recess 19 is formed by irradiating the laser beam a second time from above using a mesh-like slit pattern mask. do.

FIGS. 7 and 8 show a third embodiment of the present invention. In this third embodiment, a large number of circular hole-shaped recesses 21 are formed in the bright spot correction section 16 as shown by diagonal lines in FIG. However, a correction method is adopted in which a rough surface 17 is formed on the bottom surface of the recess 21. The correction method of this third embodiment is performed in the same procedure as the second embodiment, and produces the same light reduction effect.

FIG. 9 shows a modification of the surface roughening treatment shown in the third embodiment. In this modification, the recess 21a is formed into a tapered shape, and a rough surface 17 is formed on the bottom surface of the recess 21a. Perform processing.

FIG. 10 shows a fourth embodiment of the present invention. In this fourth embodiment, the irradiation direction of the laser beam 10 is set at a predetermined angle with respect to the bright spot correction unit 16, so that the laser beam 10 is irradiated at a predetermined angle. A correction method is used to form uneven portions 19b and 20b. The fourth embodiment also provides the same effects as the second and third embodiments.

Note that the liquid crystal panel to which the present invention is applied is 3
It is not limited to those used in single-panel projection type liquid crystal display devices, 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 also be implemented in the same way.

[0041]

The present invention has the following advantages over the conventional correction method described above.

■ Light shielding and light attenuation characteristics.

According to the conventional method, since the incident light entering the correction section is completely blocked, the correction section becomes a black spot and the correction area is limited to the edge of the display. Since the correction is performed by diffusing and attenuating the incident light, such black spots do not occur and the correction location is not limited.

■ Reliability of modification.

Since an opaque light-shielding film is not used, it goes without saying that the film does not peel off or fall off during cleaning, and reliability can be improved.

■Correction size and shape.

According to the conventional method, if an opaque light-shielding film is to be bonded stably, the bonding shape is limited to a circular shape, which makes it difficult to deal with square bright spot pixels. According to the present invention, by using a slit pattern, it is possible to deal with the shape of a bright spot pixel, and many types of uneven steps can be formed, so there is an advantage that the degree of dimming can be selected.

[Brief explanation of drawings]

FIG. 1 is a drawing schematically showing a defect repair method using an excimer laser device according to an embodiment of the present invention.

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

FIG. 3 is a drawing showing a rough surface formed by excimer laser etching.

FIG. 4 is a drawing showing a modification of the surface roughening process shown in FIG. 3;

FIG. 5 is a drawing showing a bright spot correction unit according to a second embodiment of the present invention.

FIG. 6 is a sectional view taken along line BB in FIG. 5;

FIG. 7 is a drawing showing a bright spot correction unit according to a third embodiment of the present invention.

FIG. 8 is a sectional view taken along line CC in FIG. 7;

FIG. 9 is a drawing showing a modification of the surface roughening process shown in FIG. 8;

FIG. 10 is a sectional view of a bright spot correction section according to a fourth embodiment of the present invention.

FIG. 11 is a side view showing a conventional method.

FIG. 12 is a drawing corresponding to FIG. 2 in the conventional method.

[Explanation of symbols]

1.LCD panel 2 Glass substrate 5 Bright spot picture elements 9 Excimer laser oscillator 10 Laser beam 11 Slit pattern 14　Placement stand 16 Bright spot correction section 17 Rough surface 18 Recess 19 Recess 27 Output light side glass substrate 30 Twisted nematic liquid crystal 31 Deflection plate 40 Illumination light

Claims (2)

[Claims] 1. A transmissive liquid crystal panel in which a liquid crystal is sealed between a pair of transparent substrates sandwiched between opposing polarizing plates, and display pixels are arranged in a matrix; and the transmissive liquid crystal panel. In a liquid crystal display device having a light source means for irradiating illumination light for display from the rear direction of the polarizing plate located on the irradiation path of the illumination light that irradiates the picture element in which a bright spot defect has occurred, A liquid crystal display device in which a recessed portion is formed near the surface, and the bottom surface of the recessed portion is formed into a rough surface shape exhibiting light scattering characteristics. 2. A transmissive liquid crystal panel in which a liquid crystal is sealed between a pair of transparent substrates sandwiched between opposing polarizing plates, and display pixels are arranged in a matrix; and the transmissive liquid crystal panel. A method for repairing a defect in a liquid crystal display device having a light source means for irradiating illumination light for display from the back side of the display device, wherein the illumination light is irradiated onto the transmissive liquid crystal panel to correct a bright spot defect occurring in the pixel. a step of detecting a rough surface having a bottom surface exhibiting light scattering characteristics near the surface of the deflection plate located on the irradiation path of the illumination light that irradiates the picture element in which the bright spot defect has occurred; A method for correcting a defect in a liquid crystal display device, comprising the step of forming the formed recessed part.