JP2740583B2 - Liquid crystal display device and defect repair method for liquid crystal display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission type liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates sandwiched between a pair of deflection plates, and picture elements for display are arranged in a matrix. The present invention relates to a liquid crystal display device having light source means for irradiating illumination light for display from the rear side of a transmission type liquid crystal panel, and a defect correction method for correcting a bright spot defect occurring 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.

[0005] As a conventional example of a method of correcting the bright spot defect, there is a method shown in FIGS. This method forms an opaque light-shielding film 6 near the surface of the glass substrate 2 on the incident side corresponding to the bright spot picture element 5 of the liquid crystal panel 1 (hereinafter, this position is referred to as a bright spot defect correcting section 6). (Not shown), the light incident on the bright spot picture element 5 is reduced and the bright spot picture element 5 is corrected so as to be inconspicuous.

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. 12 shows a bright dot picture element 5 and an opaque light shielding film 6.
Are on the same path. In addition,
The glass substrate 2 is composed of two glass substrates 2 and 3 to be bonded.
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 sufficient adhesion to a glass surface having a very smooth surface, a cleaning operation such as wiping the surface to remove dirt and other dirt will cause the surface of the glass substrate 2 to lose its surface. There is a drawback in that it is liable to cause defects such as peeling off from the substrate or causing defects, and is inferior in reliability.

The opaque light shielding film 6 has a light shielding characteristic.
Has a drawback that the opaque light-shielding film 6 is visually recognized as a black dot in a bright image scene where the display screen is bright, so that the correction portion is limited to the end position of the display. is there.

The present invention solves such disadvantages of the prior art, and provides a liquid crystal display device and a method of correcting a defect of a liquid crystal display device in which the reliability of correction is improved and the correction position is not limited. The purpose is to do.

[0013]

In the liquid crystal display device of the present invention, a liquid crystal is sealed between a pair of transparent substrates sandwiched between deflecting plates arranged to face each other, and picture elements for display are arranged in a matrix. A liquid crystal display device having a transmission type liquid crystal panel and light source means for irradiating illumination light for display from the back side of the transmission type liquid crystal panel, wherein the illumination for irradiating the picture element in which a bright spot defect occurs. A recessed portion is formed near the surface of at least one of the deflecting plates located on the light irradiation path so as to cover the defective picture element, and the bottom surface of the recessed portion is filled with a sealing gas.
Excimer laser etching using KrF
It is a rough surface shape showing the light scattering properties, the above objects can be achieved.

Further, according to the defect correcting method for a liquid crystal display device of the present invention, liquid crystal is sealed between a pair of transparent substrates sandwiched between deflecting plates arranged to face each other, and picture elements for display are arranged in a matrix. A defect correction method for a liquid crystal display device having a transmission type liquid crystal panel and light source means for irradiating illumination light for display from the back side of the transmission type liquid crystal panel. Detecting a bright spot defect occurring in the picture element, and detecting at least one of the deflection plates located on an irradiation path of the illumination light for irradiating the picture element having the bright spot defect. In the vicinity of the surface , Kr
By an excimer laser etching using F, Recessed recessed to form a processed concave portion so as to cover the defect pixel
Forming the bottom surface of the processed portion into a rough surface shape exhibiting light scattering characteristics, whereby the object is achieved.

[0015] Preferably, a recessed portion having a step-like bottom surface formed by alternately connecting shallow portions and deep portions alternately is formed. Further, it is preferable to form the recessed portion by excimer laser etching. Furthermore,
The recessed portion can be formed not only on the incident side but also on the outgoing light side deflection plate.

[0016]

As described above, a recessed portion is formed near the surface of at least one of the deflecting plates positioned on the irradiation path of the display illumination light so as to cover the defective picture element, and the bottom surface is roughened. Then, only the illumination light passing through this portion is diffused. This roughening treatment is performed by using KrF as the filling gas.
Surface roughness due to excimer laser etching
Has a sufficiently rough surface and the best light scattering characteristics are obtained.
It is. Therefore, on the display screen, the brightness level of the bright spot defect is reduced to a level at which it is not noticeable with respect to surrounding picture elements. As a result, the presence of the bright spot picture element becomes inconspicuous with respect to surrounding normal picture elements. That is,
This means that the bright dot picture element has been corrected. Also, when forming a recessed portion so as to cover a defective picture element near the surface of the deflection plate, when forming a recessed portion in accordance with the shape of the bright spot picture element and roughening the bottom face thereof In this case, only defective picture elements are accurately corrected without affecting normal picture elements. In particular, when applied to the case where the shape of the bright spot picture element is a square, a remarkable effect is obtained. Further, when a concave portion is formed on both the incident side and the exit side of the deflecting plate disposed opposite to each other to cover the defective picture element, and the bottom surface thereof is roughened, the amount of luminance reduction becomes large. Therefore, a further dimming effect can be obtained for the bright spot defect to be corrected, and the bright spot defect is satisfactorily corrected. In this case, the control range of the amount of light reduction is also expanded.

[0017]

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.
Beam 10 emitted from the slit pattern 1
1, after being reflected by the ultraviolet reflecting mirror 12 and passing through the lens 13, the liquid crystal panel 1 set on the mounting table 14.
Are focused and irradiated on the bright spot correction unit 16. 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 as shown in FIG.
A pair of glass substrates 2, 27 bonded as shown in FIG.
Of the pair of deflecting plates 31 arranged on both outer sides of the liquid crystal panel 1, the illuminating light 40 from the light source is selected near the surface of the deflecting plate 31 on the side on which the liquid crystal panel 1 is incident. The deflecting plates 31 are formed of a dye-based deflecting plate such as an iodine-based dye.
Reference numeral 6 is on the irradiation path of the illumination light 40 for irradiating the bright spot picture element 5 as described above.

Color filters 24 and black stripes 25 are alternately arranged on the inner side of the glass substrate 2 on the incident side, that is, on the opposite side. The color filters 24 are all color filters of the same color (R (red) color filter in the illustrated example), and the color filters 24 and the black stripes 25 are arranged corresponding to the picture elements. Further, a counter electrode 26 is provided on the inner surface side of the color filter 24 and the black stripe 25 thus provided. The counter electrode 26 is provided for applying a voltage to the twisted nematic liquid crystal layer 30 sealed between the pair of glass substrates 2 and 27. The color filter 2
4 may be disposed 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 arranged pixel electrodes 28 arranged in a matrix and a TF for switching 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 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 has the same color in the same panel as described above, and the three liquid crystal panels 1 are combined to perform three primary color full-color displays.

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., utilizing the twist alignment effect of the deflection film 31 and liquid crystal molecules, can be widely applied. Further, in addition to the above structure, a glass substrate with a TFT on the incident side of the illumination light 40,
Bright spot correction unit 1 on the glass substrate side with the color filter on the emission side
6 may be formed.

The slit pattern 11 is formed with a pattern in which the outer size of the bright spot correcting section 16 is enlarged, and the laser beam 10 is reduced 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.

In the preceding process, the bright spot picture element 5 is detected by irradiating the liquid crystal panel 1 with illumination light 40 from a light source and projecting a display image of the liquid crystal panel 1 in a driving state on a display screen. The inspection is performed by the inspector visually checking the projected image.

As shown in FIG. 3, the correction processing for the bright point correction unit 16 is performed by irradiating a laser beam 10 from the arrow I ₁ direction luminance point correction unit. As a result, the irradiated portion is laser-etched, and the rough surface 17 made 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 concave portion 18. Thus, thereafter, is irradiated with illumination light 40 from the same I ₂ direction of arrow I ₁ direction from the light source to the surface roughening treatment unit, the illumination light 40 after being diffused by the roughened 17, towards the display screen Is emitted. Therefore, the amount of light that reaches the observer directly from the bright spot picture element 5 on the same path decreases according to the degree of the rough surface shape, and the brightness level of the bright spot picture element 5 becomes lower on the display screen. The luminance level of the normal picture element 50 is reduced to a level that does not differ from the luminance level of the normal picture element 50. As a result, it is not recognized as a bright spot picture element. In other words, the bright spot picture element 5 is corrected by the dimming effect of the bright spot picture element 5.

Expressing the brightness reduction effect as a change in the amount of light directly reaching the observer, the amount of light after the surface roughening can be appropriately controlled within a range of about 80% to 10% before irradiation with the laser beam 10. It is. In the present embodiment, the amount of light before irradiation with the laser beam 10 is reduced to about 50% ± 10% to obtain a favorable effect of correcting a bright spot defect. Since the deflecting plates 31 are arranged on both the incident side and the outgoing side, when it is desired to increase the above-mentioned luminance reduction light amount, the concave portions 18 and the rough surface 17 may be formed in both of the deflecting plates 31, 31.

The above surface roughening treatment may be performed by laser etching using a CO ₂ laser, or may be performed by engraving using a diamond needle or a cemented carbide needle. For example, 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 surrounding bright point correction section 16, such heat according to the excimer laser etching There is an advantage that it does not cause any damage. 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 248 nm are used as sealing gases.
KrF, XeCl having an oscillation wavelength of 308 nm, etc. are used.
Although the pulse energy of the excimer laser oscillator 9 and the surface roughness of the rough surface 18 are different depending on the type of the sealing gas, excimer laser etching using KrF as the sealing gas is based on the following experimental results by the present inventors. It was confirmed that machining was the most preferable correction method.

That is, in order to examine the type of excimer laser gas that is optimal for roughening the surface to reduce the light emitted from the luminescent spot correction unit 16, the experiment was performed under the same pulse shot conditions while changing the type of sealing gas. The surface roughness of the rough surface 17 is K
rF was the coarsest, followed by ArF. Observation with a microscope of the rough surface 17 made of KrF, which was able to achieve the highest surface roughness, 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 correcting section 16 shown in FIG. 2 was uniformly irradiated with a laser beam using this 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.

FIG. 4 shows a modification of the surface roughening process shown in FIG. 3. In this modification, a hemispherical concave portion 18a is formed near the surface of the incident side deflection plate 31, and the bottom surface is roughened. A surface roughening process for forming the surface 17 is performed. Also in this modified example, when it is desired to increase the amount of luminance reduction light, the two deflecting plates 31, 3
1, the recess 18a and the rough surface 17 may be formed.

FIGS. 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 FIG. 5) and convex portions Part 20
(A white frame portion in the figure) and a method of forming a rough surface 17 on the bottom surface of the concave portion 19 and the surface of the convex portion 20 are adopted. Note that the small area varies depending on the type of liquid crystal panel, but a small one is 120 × 100 μm and a large one is 250 × 230.
It is about μm.

According to the second embodiment, since the surface roughening process is performed in a double manner, there is an advantage that the incident light from the light source can be further diffused and reduced. According to the second embodiment, it is convenient for responding to future technological trends of the projection device. That is, it is expected that the luminance of metal halide lamps as light sources will increase as a future technical trend, and in order to cope with this, it is necessary to further improve the dimming effect of the bright spot luminance in the surface roughening processing section. Because there is.

This correction method is performed by irradiating the laser beam 10 to the luminescent spot correction section 16 in the following procedure. That is, first, the entire area of the bright spot correction section 16 is uniformly irradiated with the laser beam 10, and then the second laser beam irradiation is performed from above using a mesh-shaped slit pattern mask to form the concave portion 19. I do.

FIGS. 7 and 8 show a third embodiment of the present invention. In this third embodiment, a number of round hole-shaped concave portions 21 indicated by oblique lines in FIG. Then, a correction method of forming the rough surface 17 on the bottom surface of the concave portion 21 is adopted. The correction method of the third embodiment is performed in the same procedure as in the second embodiment, and has the same dimming effect.

FIG. 9 shows a modification of the surface roughening treatment shown in the third embodiment. In this modification, a concave portion 21a is formed in a tapered shape, and a rough surface 17 is formed on the bottom surface. 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 luminescent spot correction unit 16 so as to be inclined. A method of forming the uneven portions 19b and 20b is adopted. According to the fourth embodiment, the same effects as those of the second and third embodiments can be obtained.

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.

[0041]

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, the incident light incident on the correction portion is completely blocked, so that the correction portion becomes a black point, so that the correction portion is limited to the end of the display. Since the incident light is corrected by being diffused and reduced, such a black spot does not occur, and the corrected portion is not limited. In addition, by forming a recessed portion so as to cover the defective picture element on both the entrance side and the exit side of the deflecting plate disposed opposite to each other, and roughening the bottom surface thereof, the luminance reduction light amount is increased. A further dimming effect can be obtained for the bright spot defect to be corrected. In this case, it is also possible to widen the control range of the amount of light reduction. In addition, this roughening treatment is
Excimer laser etching using KrF
Process, the surface roughness becomes sufficiently rough.
Bright spot defects that provide the best light scattering properties and can be corrected
, A desired dimming effect can be obtained.

Correction reliability.

Since the opaque light-shielding film is not used, the film does not peel off or drop off during cleaning or the like, and the reliability can be improved. Ma
Depressed near the surface of the deflection plate to cover defective pixels
Part is formed, and the bottom surface is roughened.
Positive reliability can be improved. In particular, the surface of the deflector
A recessed part is formed near the surface according to the shape of the bright pixel
The rough surface is applied to the bottom of the
Correctly correct only defective picture elements without affecting
Can be.

Corrected size, corrected shape.

According to the conventional method, if a stable adhesion of the opaque light-shielding film is to be performed, the bonding shape is necessarily limited to a circular shape, so that it is difficult to cope with a square bright spot picture element. According to the present invention, by using a slit pattern, it is possible to cope with the shape of a bright spot picture element and to form various kinds of uneven steps, so that there is an advantage that the dimming degree can be selected.

[Brief description of the drawings]

FIG. 1 is a drawing schematically showing a defect repair method using an excimer laser device according to one 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 for illumination light.

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

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

FIG. 5 is a view 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 of FIG. 5;

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

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

FIG. 9 is a view showing a modification of the surface roughening processing shown in FIG. 8;

FIG. 10 is a sectional view of a luminescent spot correction unit 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 a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2 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 Rough surface 18 Depression 19 Depression 27 Outgoing light side glass substrate 30 Twisted nematic liquid crystal 31 Deflection plate 40 Illumination light

Claims (2)

(57) [Claims] 1. A transmissive liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates sandwiched between opposed polarizing plates, and picture elements for display are arranged in a matrix. A light source means for irradiating illumination light for display from the back side of the liquid crystal display device, wherein at least one of the light sources located on the irradiation path of the illumination light for irradiating the picture element having a bright spot defect A concave portion is formed near the surface of the deflection plate so as to cover the defective picture element, and the bottom surface of the concave portion is formed by using KrF as a filling gas.
Screeching laser etched by a liquid crystal display device which is a rough surface shape showing the light scattering properties. 2. A transmissive liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates sandwiched between opposing deflecting plates and picture elements for display are arranged in a matrix, and the transmissive liquid crystal panel. A light source means for irradiating illumination light for display from the rear side of the liquid crystal display device, wherein the illumination light is applied to the transmissive liquid crystal panel to generate a bright spot defect in the picture element. An excimer laser using KrF as a filling gas in the vicinity of at least one surface of the deflecting plate located on the irradiation path of the illumination light for irradiating the picture element having the bright spot defect.
By the etching process , a recessed portion is formed so as to cover the defective picture element, and the bottom surface of the recessed portion is subjected to light scattering characteristics.
A method of correcting a defect in a liquid crystal display device, the method comprising: