JP3433603B2 - Display device defect repair method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for correcting a pixel defect in an active matrix type display device in which pixels composed of switching elements and pixel electrodes are formed in a matrix.

[0002]

2. Description of the Related Art An example of a conventional active matrix type display device will be briefly described with reference to FIG. This display device has a structure in which a pair of substrates 71 and 72 made of glass or the like are arranged so as to face each other, and an electro-optical substance made of a liquid crystal 73 or the like is sealed in a gap therebetween. Lower board (driving board)
Signal lines 74 and gate lines 75 arranged in a matrix, and thin film transistors 76 and pixel electrodes 77 arranged at the intersections thereof are formed on 71. The thin film transistor 76 is line-sequentially selected by the gate line 75 and functions as a switching element for writing the image signal supplied from the signal line 74 into the corresponding pixel electrode 77.
On the other hand, a counter electrode 78 and a color filter 79 are formed on the inner surface of the upper substrate (counter substrate) 72. The color filter 79 is R (red) corresponding to each pixel electrode 77,
It is divided into G (green) and B (blue) segments. Two active matrix display devices having such a configuration are provided.
A desired full-color image display can be obtained by sandwiching it between the polarizing plates 80 and 81 and allowing white light to enter.

In recent years, the resolution of active matrix type display devices has been remarkably increased, and the number of pixels is on the order of 10 ⁶ . Therefore, it is extremely difficult to manufacture a defect-free display device with high yield. Therefore,
Conventionally, a defect correction technique for correcting defective pixels to create a non-defective display device has been proposed. As a conventional countermeasure against pixel defects, a redundant configuration has been proposed in which a switching element formed of two thin film transistors connected in series to one pixel is provided. There are two types of pixel defects: bright spot defects (white spot defects) and dark spot defects (black spot defects). The bright spot defect pixels that are noticeable in all black display have the greatest adverse effect on the image quality. Therefore, as shown in US Pat. No. 5,142,386, for example, the color filter or the liquid crystal corresponding to the white spot defective pixel is directly irradiated with a laser or the like and heated to make the bright spot defective pixel opaque. Have been taken to make it inconspicuous.

[0004]

However, a redundant configuration in which two thin film transistors connected in series are used as switching elements is not an advantageous method because it complicates the pixel structure. Further, in the method of directly irradiating a color filter or liquid crystal with a laser or the like for heating, if the energy of the laser is not accurately controlled, the adjacent normal pixels are also heated, which conversely increases defects. In addition, even if the irradiation energy can be controlled accurately, it may not be possible to properly create a defect depending on the material and physical properties of the color filter or the liquid crystal, and unevenness may occur, rather degrading the image quality. In addition, this method also damages the display device itself, and thus has a problem that reliability is deteriorated. The present invention is to solve the above problems, and an object thereof is to provide a defect correction method that can easily make a bright spot defective pixel a dark dot without degrading the image quality without directly damaging the display device. is there.

[0005]

A display device which is a target of a defect repairing method according to the present invention is a panel provided with a pair of substrates bonded to each other with a predetermined gap and an electro-optical material held in the gap. Have a structure. Pixel electrodes arranged in a matrix and switching elements for driving the pixel electrodes are formed on one substrate side, and on the other substrate, the counter electrodes facing the pixel electrodes through the electro-optical material and forming the pixels and the individual electrodes are formed. Microlenses corresponding to the pixels are formed. In such a display device, the defect repairing method of the present invention selectively irradiates a microlens corresponding to a defective pixel having a white defect with an energy beam, and disables the microlens so that the defective pixel becomes a normal pixel. It is characterized by making a black spot relatively. Specifically, the microlenses are rendered ineffective by intensively irradiating them with an energy beam to physically destroy, deform, or make them opaque. Alternatively, the microlens contains a photosensitive material which is sensitive to invisible light and blackens, and the microlens is blackened by selectively irradiating the energy beam of invisible light to blacken the photosensitive material. The lens may be disabled. Furthermore, a voltage is applied between the counter electrode and each pixel electrode to display a normal pixel as a black dot and a defective pixel as a white dot, and the energy of non-visible light from the one substrate (driving substrate) side. The beam is radiated over the entire surface, and only the microlenses corresponding to the pixels displayed as white dots are selectively exposed to disable them.

According to the present invention, in an active matrix type display device having a microlens corresponding to each pixel on a one-to-one basis, only the microlens corresponding to a pixel having a white dot defect is destroyed or destroyed by an energy beam such as a laser. Transform it. Alternatively, the microlens containing the photosensitive material is selectively exposed from the back surface side with a laser beam other than visible light. As a result, the microlens corresponding to the white point defect is halftoned, and the white point defect can be turned into a black point.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic partial cross-sectional view showing an embodiment of a display device defect correcting method according to the present invention. (A) shows the state before the defect correction, and (B) shows the state after the defect correction. As shown in the figure, the display device which is the target of the defect repairing method according to the present invention is an active matrix type, and includes a pair of drive substrate 1 and counter substrate 2 bonded via a predetermined gap, and a liquid crystal held in this gap. And a panel structure including an electro-optic material such as 3.
Pixel electrodes 4 arranged in a matrix and switching elements 5 for driving the pixel electrodes 4 are formed on one drive substrate 1 side. The switching element 5 is, for example, a thin film transistor formed on a quartz base material or a glass base material 6. A counter electrode 7 and a microlens 8 are formed on the other counter substrate 2 side. The counter electrode 7 and the pixel electrode 4 face each other via the liquid crystal 3 and form a pixel. In the figure, individual pixels are separated by dotted lines for easy understanding.
The microlens 8 is provided corresponding to each pixel, and converges the incident light and concentrates it in the opening of the pixel to improve the light utilization efficiency. The counter substrate 2 has a laminated structure in which an upper glass base material 9 and a lower glass base material 10 are bonded with an adhesive 11. The above-mentioned microlens 8 is formed on the upper glass substrate 9 by, for example, an etching method. The lower glass substrate 10 is provided with color filters R, G, B corresponding to each pixel. These color filters R, G and B are used as the flattening film 12
The counter electrode 7 described above is entirely formed on it. The intermediate adhesive 11 that joins the upper glass substrate 9 and the lower glass substrate 10 to each other is transparent, and a material whose refractive index is substantially the same as that of the upper and lower glass substrates is selected, and the boundary surface Prevents reflection.

Now, suppose that the central pixel has a white spot defect. In this case, as shown in (B), the energy beam 15 is selectively irradiated to the mylo lens 8 corresponding to the defective pixel having the white spot defect, and the micro lens 8 is disabled to make the defective pixel a normal pixel. On the other hand, it becomes a black dot relatively. That is, the energy beam 15 is intensively applied to physically destroy, deform or make the microlens 8 ineffective.
As a result, the condensing function of the microlens 8 is lost, so that the amount of incident light in the central pixel is smaller than that in the adjacent pixel. Therefore, the defective pixel at the center relatively to the adjacent normal pixel becomes a black dot. Originally, a pixel that was a white spot defect becomes a black spot, so that it becomes inconspicuous and can be handled as a good product as the panel itself. An energy beam 15 such as a YAG laser is focused on the microlens 8 corresponding to the defective pixel, and only this microlens 8 is destroyed or deformed. If this happens,
Light incident from either the counter substrate 2 side or the drive substrate 1 side is scattered or diffused by the deformed microlens 8,
The pixel density is absorbed and halftoned. Since the energy beam 15 is almost absorbed by the microlens 8, the liquid crystal 3 is not damaged at all. As a specific irradiation condition of the energy beam, for example, the wavelength 53
The beam spot output from the 2 nm YAG laser is
Through an aperture such as squeezing the size of ^{3 × 3μm 2 ~5 × 5μm 2} . Maximum energy 10 mj, beam duration 4
Energy irradiation is performed under the condition of nsec. At this time, the irradiation energy is adjusted by an attenuator in the range of 2.0 to 4.0 mj, and the microlens 8 having a diameter of 30 μm is
By irradiating one to several shots, the microlens for one pixel can be effectively destroyed.

FIG. 2 is a sectional view showing a second embodiment of the display device defect correcting method according to the present invention. (A) shows the state before the defect correction, and (B) shows the state after the defect correction. Basically, it is the same as that of the first embodiment shown in FIG. 1, and corresponding parts are designated by corresponding reference numerals to facilitate understanding. The difference is that the micro lens 8
That is, a contains a photosensitive material which is sensitive to invisible light and blackens. The microlenses 8a are selectively disabled by blackening the photosensitive material by selectively irradiating the energy beam of invisible light. For example, when ultraviolet rays are used as the energy beam of invisible light, a silver salt compound can be used as the photosensitive material. This silver salt compound is used, for example, in an emulsion of a white film, and is sensitive to only wavelengths in the ultraviolet light region.

As shown in (B), when a defect is repaired, first, a black level signal voltage is applied between the counter electrode 7 and each pixel electrode 4 via the switching element 5, and the right and left normal pixels are subjected to black dots. While displaying, the defective pixel at the center is displayed as a white dot. That is, in this example, the active matrix type display device is in the normally white mode. When a black level signal voltage is applied, normal pixels are displayed in black while
The defective pixel remains in white display and is in a light transmitting state. In this state, the energy beam 15a of invisible light is entirely radiated from the drive substrate 1 side, and only the microlenses 8a corresponding to the pixels displayed as white dots are selectively exposed to inactivate. That is, by irradiating ultraviolet light from the side of the drive substrate 1 instead of the backlight in the all black display, only the microlens 8a on the defective pixel is exposed and halftoned. Such a method can significantly reduce the time required for defect correction. Also, by adjusting the intensity of ultraviolet light, it is possible to freely control the degree of blackening of defective pixels. The defective pixel may be specified in advance by inspection, and the energy beam may be made spot-like from the counter substrate 2 side to selectively and intensively irradiate the microlens corresponding to the defective pixel to disable it. .

FIG. 3 is a schematic sectional view showing another structure of an active matrix type display device which is a target of the defect repairing method according to the present invention. The difference from the display device shown in FIGS. 1 and 2 is that the positions of the microlens and the color filter are vertically inverted. With such a structure, the irradiation efficiency is improved when the energy beam is irradiated from the drive substrate 1 side to selectively disable the microlens. That is, it is possible to directly irradiate the microlens with the energy beam from the drive substrate 1 side without passing through the color filter. Hereinafter, a specific structure of the display device will be described in detail for reference. This color display device includes a counter substrate 2 facing the light source side and receiving incident light, a drive substrate 1 bonded to the counter substrate 2 through a predetermined gap and emitting emitted light, a liquid crystal 3 held in the gap, and the like. And a flat panel structure including an electro-optic material. Innumerable pixels arranged in a matrix are integrated and formed on the inner surface of the drive substrate 1, and the incident light is electro-optically modulated and converted into the emitted light. Each pixel is composed of a pixel electrode 4 made of a transparent conductive film and a switching element 5 made of a thin film transistor for driving the pixel electrode 4.

On the other hand, on the side of the counter substrate 2, a microlens 8 for condensing incident light into individual pixels and RGB pixels for the individual pixels are provided.
Color filters (R, G, B) for coloring the three primary colors are integrated and formed. The color filter is formed on the outer surface side of the counter substrate 2, and the microlens 8 is formed on the inner surface side of the counter substrate 2. The incident light first passes through a color filter arranged on the outer surface side of the counter substrate 2. After passing through the color filter, the incident light is condensed by the microlens 8 and illuminates the pixel. The pixel electro-optically modulates the incident light,
The emitted light is emitted to display a desired color image. A counter electrode 7 made of a transparent conductive film is formed on the inner surface side of the counter substrate 2, and in reality, each pixel is formed by the counter electrode 7 and the liquid crystal 3 held between the pixel electrode 4. It is formed. The voltage applied between the counter electrode 7 and the pixel electrode 4 changes the transmittance of the liquid crystal 3, and desired electro-optical modulation is performed. Further, a black mask 20 is patterned on the inner surface side of the counter substrate 2 so as to frame the periphery of each pixel. The black mask 20 defines the opening of each pixel.

Here, a method of forming the microlens 8 will be described. In this example, the etching method is adopted, and after the surface of the glass base material 21 is covered with a resist, discrete minute openings are provided. Using this resist as a mask, the glass substrate 21 is isotropically etched with hydrofluoric acid or the like. Since the etching proceeds isotropically around the minute opening,
Concave surfaces are etched within the individual openings. The concave surface is filled with a transparent material such as epoxy resin to form the microlens 8. At this time, at the same time, the transparent material contains a photosensitive material. As described above, this light-sensitive material is sensitive to invisible light such as ultraviolet light and blackens. Since the refractive index of the glass base material 21 is different from that of the transparent epoxy resin, the microlens 8 can be formed.
By appropriately setting the refractive index and the radius of curvature of the concave surface, the microlens 8 having a desired focal length can be obtained. A glass sheet 22 having a predetermined thickness is attached to the glass base material 21 in order to adjust the focal length to the pixel. The counter electrode 7 and the black mask 20 described above are formed on the surface of the glass sheet 22. The black mask 20 does not necessarily have to be provided on the counter substrate 2 side, and may be patterned on the drive substrate 1 side in some cases.

Finally, with reference to FIG. 4, a method of forming the microlens shown in FIG. 1 will be described for reference. First, in step (A), the photosensitive resin 30 is applied on the glass substrate 9 to a predetermined thickness. This photosensitive resin 30 is transparent and its refractive index is different from that of the glass base material 9. Next step (B)
Then, the photosensitive resin 30 is exposed and developed through a predetermined mask, and processed into individual separated columnar patterns. Finally, in step (C), heat treatment is performed and so-called reflow is performed to convert the photosensitive resin that has been patterned into a cylindrical shape into the shape of the microlens 8. As a result, the microlenses 8 corresponding to individual pixels are integrated and formed on the surface of the glass base material 9.

[0015]

As described above, according to the present invention, a microlens corresponding to a defective pixel having a white spot defect is selectively irradiated with an energy beam, and the microlens is disabled to make the defective pixel defective. Are black dots relative to normal pixels. According to this, there is no deterioration of image quality and damage to the panel due to the defect correction which has been a problem in the conventional method. Moreover, if the microlenses containing the photosensitive material are collectively exposed from the back surface through the white spot pixels, the time required for the correction of the white spot pixels can be significantly shortened, and the throughput of the repair work is dramatically improved. As described above, according to the present invention, a defective pixel can be quickly repaired without affecting the image quality and reliability of the active matrix display device.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a first embodiment of a display device defect correcting method according to the present invention.

FIG. 2 is a schematic partial cross-sectional view showing a second embodiment of a display device defect correcting method according to the present invention.

FIG. 3 is a schematic partial cross-sectional view showing another example of an active matrix type display device to which the defect repairing method according to the present invention is applied.

FIG. 4 is a process chart showing an example of a method for forming a microlens provided in an active matrix display device.

FIG. 5 is a schematic perspective view showing an example of a conventional active matrix display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Driving substrate, 2 ... Counter substrate, 3 ... Liquid crystal, 4 ... Pixel electrode, 5 ... Switching element, 7 ... Counter electrode, 8 ... Microlens, 15 ... Energy beam

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02F 1/1335 G02F 1/13 101 G02F 1/1362 G02F 1/1343 G09F 9/00-9/46

Claims (4)

(57) [Claims] 1. A panel structure comprising a pair of substrates bonded at a predetermined interval and an electro-optical material held in the gap, and one substrate side having pixel electrodes arranged in a matrix. A switching element that drives this is formed, and on the other substrate side, a counter electrode that faces the pixel electrode via an electro-optical material and forms a pixel, and a microlens corresponding to each pixel is formed. A defect correction method, wherein a microlens corresponding to a defective pixel having a white dot defect is selectively irradiated with an energy beam, and the microlens is disabled to make the defective pixel a black dot relative to a normal pixel. A method for correcting a defect in a display device, which comprises: 2. The defect of the display device according to claim 1, wherein the microlenses are rendered ineffective by intensively irradiating the energy beams to physically destroy, deform or make the microlenses ineffective. How to fix. 3. The microlens contains a photosensitive material that is sensitive to invisible light and blackens, and selectively irradiates an energy beam of invisible light to blacken the photosensitive material. 2. The method for correcting a defect in a display device according to claim 1, wherein the microlens is disabled. 4. An energy beam of invisible light is applied from one of the substrates while a voltage is applied between the counter electrode and each pixel electrode to display a normal pixel as a black dot and a defective pixel as a white dot. 4. The defect repairing method for a display device according to claim 3, wherein the entire surface is illuminated and only the microlens corresponding to the pixels displayed as white dots is selectively exposed to make it ineffective.