KR100510419B1 - Raster defect correction method for liquid crystal display device and raster defect correction device for the same - Google Patents

Abstract

The present invention provides a raster defect correction method capable of effectively and at high speed erasing the alignment characteristics of an alignment layer when correcting raster defects in a liquid crystal display. By scanning the alignment layer with a laser beam in which the longitudinal direction of the beam shape is orthogonal to the groove direction of the alignment layer, the regularity of the grooves of the alignment layer is broken. When the groove direction of one of the alignment layers is formed at 45 ° and the other groove direction is formed at 135 °, the beam shape and the beam energy are controlled in accordance with the scanning progress of the raster beam. Further, the laser beam is irradiated to the alignment layer through the liquid crystal layer from both sides of the color filter side and the array substrate side (TFT side) opposite thereto.

Description

Raster defect correction method for liquid crystal display and raster defect correction apparatus for same {RASTER DEFECT CORRECTION METHOD FOR LIQUID CRYSTAL DISPLAY DEVICE AND RASTER DEFECT CORRECTION DEVICE FOR THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raster defect correction method and a raster defect correction apparatus for correcting raster defects of a liquid crystal display.

The active matrix liquid crystal display device includes a first glass substrate, a second glass substrate, a liquid crystal sandwiched between the first and second glass substrates, an alignment layer formed on one surface (the surface facing the liquid crystal) of each glass substrate, and the other It has a polarizing plate arranged on the surface side. The first glass substrate is called an array substrate, and signal lines and scanning lines are formed in a matrix shape on the surface of the first glass substrate facing the liquid crystal, where TFTs (thin film transistors) and pixels for charging and discharging charges are provided. An electrode is provided at each intersection of the signal line and the scanning line. The second glass substrate is called a color filter (hereinafter referred to as CF), and a protective coating as well as a transparent conductive film is formed on the surface of the second glass substrate facing the liquid crystal. This transparent conductive film is a common electrode of the liquid crystal display device and covers the entire surface of the second glass substrate.

The alignment layer formed on each of the first and second glass substrates is in direct contact with the liquid crystal of the liquid crystal display device in order to twist the liquid crystal by 90 degrees, and is a thin transparent film. In general, a polyimide resin is used as the material of the alignment layer, and the alignment layer has fine V-shaped grooves (alignment grooves) formed in parallel on the entire surface thereof. The alignment layers of the first and second glass substrates are laid out to be in a state intersecting at 90 degrees. More specifically, the V-shaped groove formed on one alignment layer and the V-shaped groove formed on the other alignment layer intersect at 90 degrees. The 90 ° crossing means that one alignment layer may be 45 ° and the other alignment layer may be 135 °, and a general active matrix liquid crystal display forms this angle.

When a voltage is applied to the liquid crystal between the array substrate and the CF, the liquid crystal is oriented perpendicular to the substrate. Therefore, the white light from the backlight is completely blocked by the polarizing plates disposed at the top and bottom of the liquid crystal display device, and as a result, the display is completely black. On the other hand, if no voltage is applied to the liquid crystal between the array substrate and the CF, the liquid crystal is oriented along the V-shaped groove on each alignment layer. Thus, the polarization of the white light from the backlight is twisted 90 degrees by the liquid crystal to pass through the polarizer. Further, as this polarized light passes through CF, all three colors of RGB are generated, and as a result, the liquid crystal display becomes a completely white display. In practice, vertical and horizontal synchronizing signals are constantly sent from the external signal generator to the TFT to display various patterns on the liquid crystal display.

Active matrix liquid crystal displays are prone to defects in the manufacturing process. It is known that when the TFT causes an operation failure or when the pixel electrode or alignment layer is not normally formed, the pixel no longer blocks the transmitted light and this portion appears as a raster defect (bright spot defect). As a method for correcting such a raster defect, there is a method disclosed in Japanese Patent Laid-Open No. 5-210111. According to this method, the gate electrode and the drain electrode of the TFT are connected by a laser beam, and a DC voltage is constantly applied to the display electrode (pixel electrode) of the defective pixel. Thus, the transmitted light of the pixel is reduced and the defect is weakened. However, ions in the liquid crystal are concentrated on one electrode of the repair portion due to the DC voltage applied to the pixel electrode, so that the lifetime of the liquid crystal display device is shortened.

On the other hand, there is a method of correcting raster defects without applying a DC voltage to the pixel electrode of the defective portion. According to this method, the alignment layer of the liquid crystal display device is irradiated with a laser beam to partially erase the liquid crystal layer pixel by pixel or to erase the V-shaped groove on the alignment layer. Thus, the transmitted light of the defective pixel is reduced and the defect is weakened. Techniques for erasing an alignment layer or erasing V-shaped grooves thereon are disclosed in Japanese Patent Laid-Open Nos. 8-15660 and 8-201813. Furthermore, techniques for generating bubbles in the liquid crystal once in order to safely erase the alignment layer are disclosed in Japanese Patent Laid-Open Nos. 9-90304 and 2000-56283.

However, according to the methods disclosed in Japanese Patent Laid-Open Nos. 8-15660 and 8-201813, since the alignment layer is treated with a laser beam with a spot smaller than the pixel, the processing time is long, and the trajectory of the laser beam scan is new. Raster defects are not satisfactorily corrected.

SUMMARY OF THE INVENTION An object of the present invention is to provide a raster defect correction method and a raster defect correction apparatus capable of erasing the alignment characteristics of an alignment layer of a liquid crystal display device effectively and at high speed.

According to a first aspect of the present invention, there is provided a raster defect correction method for correcting raster defects by canceling the alignment of the grooves of the alignment layer in contact with the liquid crystal layer of the liquid crystal display device. The grooves of the alignment layer are erased by scanning the alignment layer with a laser beam whose longitudinal direction is orthogonal to the groove direction of the alignment layer.

According to a second aspect of the present invention, there is provided a raster defect correction method for correcting raster defects by canceling the alignment of the grooves of the alignment layer in contact with the liquid crystal layer of the liquid crystal display device. By scanning the alignment layer with a first laser beam orthogonal to the groove direction of the alignment layer on the color filter side of the liquid crystal display device, the groove of the alignment layer is erased, and the beam-shaped length direction passes through the liquid crystal layer. The groove of the alignment layer is erased by scanning the alignment layer with a second laser beam orthogonal to the groove direction of the alignment layer on the glass substrate side opposite to the color filter.

According to a third aspect of the present invention, there is provided a raster defect correction apparatus for correcting raster defects by canceling the alignment of the grooves of the alignment layer in contact with the liquid crystal layer of the liquid crystal display device, wherein the longitudinal direction of the beam shape is aligned. Beam shape control means for generating a laser beam orthogonal to the groove direction of the layer; And means for scanning the alignment layer with the laser beam.

According to a fourth aspect of the present invention, there is provided a raster defect correction apparatus for correcting raster defects by canceling the alignment of the grooves of the first and second alignment layers in contact with the liquid crystal layer of the liquid crystal display device, wherein the apparatus has a beam shape. Beam shape control means for generating a first laser beam having a longitudinal direction of orthogonal to the groove direction of the first alignment layer and a second laser beam having a longitudinal direction of the beam shape perpendicular to the groove direction of the second alignment layer; And means for scanning the first alignment layer with the first laser beam and scanning the second alignment layer with the second laser beam.

The grooves of the alignment layer can be erased by scanning the alignment layer with a laser beam whose longitudinal direction of the beam shape is orthogonal to the groove direction of the alignment layer so as to effectively destroy the regularity of the grooves of the alignment layer.

The longitudinal direction of the beam shape forms a laser beam orthogonal to the groove direction of one of the alignment layers in contact with the liquid crystal layer of the liquid crystal display device, and the groove of one of the alignment layers is formed by scanning the one alignment layer with the laser beam. Erase. Further, a laser beam perpendicular to the groove direction of the other alignment layer whose beam shape is in the longitudinal direction is formed, and the groove of the other alignment layer is erased by scanning the other alignment layer with the laser beam.

When the groove direction of the one alignment layer is formed at 45 ° and the groove direction of the other alignment layer is formed at 135 °, the size of the length direction of each laser beam is controlled in accordance with the scanning progress of the laser beam. Thereby, it is possible to effectively destroy the regularity of the groove of the alignment layer.

In addition, the energy of each laser beam is also controlled when the size is controlled as the scan progresses. Thereby, it is possible to effectively destroy the regularity of the grooves of the alignment layer while preventing thermal influence on other liquid crystal cells.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a view showing the configuration of a raster defect correction apparatus according to a first embodiment of the present invention. In Fig. 1, the Q switch pulse laser oscillator 2 emits a Q switch pulse laser based on an instruction from the controller 1, which is input to an expander 3. The expander 3 enlarges and collimates the incident laser beam. The laser output from the expander 3 is input to an attenuator 4 to adjust the beam intensity. The laser output from the attenuator 4 enters the optical slit (optical aperture) 5. The optical slit 5 forms the beam shape of the incident laser longitudinally or laterally. The laser beam passing through the optical slit 5 enters the liquid crystal panel 8 through the relay lens 6 and the objective lens 7, and the alignment layer in the panel 8 is irradiated with the laser beam. The optical slit can form the beam in various shapes, and can be composed of a variable rectangular slit capable of controlling the size of the XY direction and a mechanism for enabling rotation, for example.

The top surface of the liquid crystal panel 8 may be a color filter or an array substrate. The liquid crystal panel 8 is mounted on the stage 9, which is moved by the control of the controller 1. Therefore, if a raster defect (bright spot defect) is found in any pixel of the liquid crystal panel 8, it is possible to set this raster defect point as a correction point and scan the beam in any direction on the liquid crystal panel 8. . The polarizing plate 10 and the backlight 11 are disposed below the liquid crystal panel 8.

On the other hand, the beam which passed the beam splitter 12 and the polarizing plate 13 is image | photographed by the camera 14, and this image data is sent to the image processing apparatus 15 and the monitor 22. As shown in FIG. The image processing apparatus 15 processes the image from the camera 14 to automatically detect the raster defect, i.e., the point requiring raster defect correction, and notify the controller 1. It is also possible for the operator to control the controller 1 by detecting the point where the raster defect correction is needed from the monitor screen.

In Fig. 1, polarizers 10 and 13 intersecting each other at 90 ° are arranged on the upper and lower surfaces of the liquid crystal panel 8, but it is sufficient that they are located between the backlight 11 and the camera 14 and always in the liquid crystal cell. There is no need to be adjacent. By using the camera 14 to observe in real time the situation of the lowering of the light transmittance of the defective pixel and the raster defect correction, or performing image processing by the image processing apparatus 15 to determine whether the raster defect correction is good. It is possible. When the liquid crystal panel 8 has a polarizing plate, the polarizing plates 10 and 13 are unnecessary.

FIG. 2 is a view for explaining the relationship between the laser scanning when the upper surface of the liquid crystal panel 8 is a color filter and the V-shaped groove direction (90 °) of the alignment layer formed on the color filter. In Fig. 2, the V-shaped groove is formed in the vertical direction. That is, the V-shaped groove direction is 90 degrees. As shown in Fig. 2, the laser beam in which the longitudinal direction of the beam shape is orthogonal to the V-shaped groove direction of the alignment layer is the lateral beam B1. The alignment layer is scanned in the vertical direction with the laser beam B1. In FIG. 2, the length in the longitudinal direction of the laser beam B1 is equal to the horizontal width of the pixel.

3 is a view for explaining the relationship between the laser beam scanning when the upper surface of the liquid crystal panel 8 is an array substrate and the V-shaped groove direction (0 °) of the alignment layer formed on the array substrate. In Fig. 3, the V-shaped groove is formed in the horizontal direction. That is, the V-shaped groove direction is 0 degrees. As shown in Fig. 3, the laser beam whose longitudinal direction of the beam shape is orthogonal to the V-shaped groove direction of the alignment layer is the longitudinal beam B2. The alignment layer is scanned in the horizontal direction with the laser beam B2. In Fig. 3, the size of the laser beam B2 in the longitudinal direction is equal to the vertical width of the pixel.

Thus, according to the first embodiment of the present invention, the shape of the laser beam from the oscillator 2 is formed to have a length along the pixel, and the longitudinal direction of the beam shape is orthogonal to the V-shaped groove direction of the alignment layer. By scanning the alignment layer in the V-shaped groove direction with this laser beam, it is possible to effectively and quickly erase the regularity of the V-shaped groove of the alignment layer.

2 and 3, the TFTs of the pixels (defective pixels) on which raster defects occur are turned on. By correcting the raster defect toward the original black display, the monitor 22 immediately determines, via the camera 14, whether or not the light transmittance of the defective pixel is deteriorated, or the image processing apparatus 15 is corrected. It is intended to make it easier to extract the points that should be. Furthermore, in Figs. 2 and 3, the TFTs of the eight pixels surrounding the defective pixels are turned off to simultaneously prove that abnormalities (failures) due to raster defect correction are not occurring in the RGB display colors.

2 and 3, the V-shaped groove direction is 90 ° or 0 °, but the V-shaped groove direction may be 135 ° or 45 °.

4 is a view for explaining the relationship between the laser beam scanning when the upper surface of the liquid crystal panel 8 is a color filter and the V-shaped groove direction 135 ° of the alignment layer formed on the color filter. As shown in Fig. 4, the laser beam whose longitudinal direction of the beam shape is orthogonal to the V-shaped groove direction of the alignment layer is the beam B3 in the inclined direction. The alignment layer is scanned in the V-shaped groove direction shown in FIG. 4 with the laser beam B3. In this case, the length of the laser beam B3 varies depending on the scan position, which is set to become longer as the scan position advances to P1, P2, P3, .... The length of the laser beam B3 is changed by causing the controller 1 (see FIG. 1) to control the optical slit 5 (see FIG. 1).

FIG. 5 is a diagram for explaining the relationship between the laser beam scanning when the upper surface of the liquid crystal panel 8 is an array substrate and the V-shaped groove direction (45 °) of the alignment layer formed on the array substrate. As shown in Fig. 5, the laser beam whose longitudinal direction of the beam shape is orthogonal to the V-shaped groove direction of the alignment layer is the beam B4 in the inclined direction. The alignment layer is scanned in this V-shaped groove direction shown in Fig. 5 with this laser beam B4. As with the laser beam B3, the length of the laser beam B4 changes depending on the scan position, which is set to become longer as the scan position progresses.

4 and 5, the alignment layer is scanned in the V-shaped groove direction. However, it is also possible to make the scanning direction perpendicular or horizontal to the pixel (in the direction of the sides constituting the pixel). FIG. 6 shows an example in which the scanning direction of the beam B4 shown in FIG. 5 is perpendicular or horizontal to the pixel. The scan direction shown in FIGS. 2 to 6 is implemented by controlling the movement of the stage 9 with the controller 1.

In fact, in many liquid crystal display devices, the alignment grooves of the alignment layer are formed at 45 degrees or 135 degrees, so in this case, the scanning direction of the laser beam for erasing the alignment grooves is 135 degrees or 45 degrees (see FIGS. 4 and 5). ). In addition, the length in the longitudinal direction of the inclined laser beam in which the alignment layer of the longitudinal pixels (100 μm in width x 300 μm in length) or the transverse pixels (300 μm in length × 100 μm in length) is scanned is enlarged according to the scanning position. Or to contract. It is preferable to scan the alignment layer while controlling the pulse energy of the laser beam in accordance with the change in the length of the laser beam. More specifically, the energy becomes smaller as the length of the laser beam becomes longer, and the energy becomes larger as it becomes shorter. This is to reduce the thermal effect on the liquid crystal panel due to the irradiation of the laser beam because the energy for the long beam is larger than for the shorter beam. This pulse energy is corrected by taking into account thermal effects, for example by a linear function, and more strictly by a cubic function.

According to the first embodiment of the present invention, the alignment layer is sequentially irradiated with pulse lasers sequentially fired by the Q switch pulse laser oscillator 2. Here, it is also possible to scan the alignment layer by superimposing with a pulse laser which is sequentially fired by the oscillator 2. That is, it is also possible to scan the alignment layer so that the area of the alignment layer irradiated with the pulse laser fired by the oscillator 2 partially overlaps with the area fired by the oscillator 2 and then irradiated with the pulse laser. Under normal circumstances, irradiating the alignment layer with the laser beam to cancel the alignment of the alignment grooves of the alignment layer, the traces of the laser beam remain and provide a new orientation to the alignment layer, weakening the effect of raster defect correction. However, according to the first embodiment of the present invention, the trajectory of the laser beam becomes orthogonal to the V-shaped groove direction of the alignment layer so that the alignment of the alignment layer can be more effectively erased.

7 is a view showing the configuration of the raster defect correction apparatus according to the second embodiment of the present invention, wherein the same parts as in FIG. 1 are denoted by the same reference numerals. As shown in FIG. 7, this raster defect correction apparatus erases the V-shaped groove of the alignment layer from both sides (color filter side and TFT side (array substrate side)) of the liquid crystal panel 8. Therefore, it is possible to further deteriorate the light transmittance of the defective pixel as compared with the first embodiment of the present invention.

In FIG. 7, the laser beam from the attenuator 4 is separated by the beam splitter 16 and then provided to the optical slit 5 and the optical slit 18 through a mirror 17. The laser beam from the optical slit 5 enters the liquid crystal panel 8 through the beam splitter 12, the relay lens 6 and the objective lens 7, and the upper alignment layer of the liquid crystal panel 8 is this laser. Irradiated with a beam. On the other hand, the laser beam from the optical slit 18 enters the liquid crystal panel 8 through the mirror 19, the relay lens 20, and the objective lens 21, and the lower alignment layer of the liquid crystal panel 8 is the same. It is irradiated with a laser beam.

Here, the V-shaped grooves of the upper alignment layer and the V-shaped grooves of the lower alignment layer are orthogonal to each other, and the shapes of the laser beams formed by the optical slits 5 and 8 are also orthogonal to each other. More specifically, one of these beams is beam B1 shown in FIG. 2 and the other is beam B2 shown in FIG. 3, or one of these beams is beam B3 shown in FIG. 4 and the other is beam B4 shown in FIG. 5.

When the V-shaped groove direction of the alignment layer on the color filter and the V-shaped groove direction of the alignment layer on the array substrate are 135 ° and 45 °, respectively, the laser beams formed by the optical slits 5 and 18 are shown in FIGS. 4 and 5. The beams B3 and B4 shown in Fig. 2 and the length in the longitudinal direction of the beams B3 and B4 are controlled according to the scanning position. The scanning directions of the beams B3 and B4 are the directions shown in FIGS. 4 and 5 or the directions shown in FIG. 6.

According to the present invention, the shape of the laser beam is formed into a shape having a length along the pixel, and the laser beam also has the length V of the alignment layer irradiated with the laser beam to scan the alignment layer with the laser beam. It is formed to be orthogonal to the female groove direction. Therefore, it is possible to quickly and effectively destroy the regularity of the V-shaped grooves of the alignment layer, and moreover, it is possible to make raster defect correction of the liquid crystal display device more effective than the conventional raster defect correction method.

Further, according to the present invention, the laser beam is irradiated to the alignment layer through the liquid crystal layer from both sides of the color filter side and the array substrate side (TFT side) opposite thereto. Therefore, raster defect correction can be made more effective.

Further, according to the present invention, when the groove direction of one of the alignment layers is 45 ° and the other groove direction is 135 °, the shape of the laser beam is controlled in accordance with the scanning progress of the laser beam. It is thereby possible to correct raster defects at high speed.

Furthermore, according to the present invention, the energy of the laser beam is also controlled when the shape of the laser beam is controlled in accordance with the scanning progress of the laser beam. Thereby, it is possible to correct raster defects at high speed while preventing thermal influences on other liquid crystal cells.

Further, according to the present invention, the alignment layers are scanned by overlapping them with sequentially emitted laser beams. Thus, the orientation of the alignment layer can be canceled more effectively.

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows the structure of the raster defect correction apparatus which concerns on 1st Embodiment of this invention.

FIG. 2 is a view for explaining the relationship between the V-shaped groove direction (90 °) of the alignment layer formed on the color filter and the scanning laser beam when the upper surface of the liquid crystal panel 8 is a color filter;

3 is a view for explaining the relationship between the V-shaped groove direction (0 °) of the alignment layer formed on the array substrate and the scanning laser beam when the upper surface of the liquid crystal panel 8 is an array substrate.

4 is a view for explaining the relationship between the V-shaped groove direction (135 °) of the alignment layer formed on the color filter and the scanning laser beam when the upper surface of the liquid crystal panel 8 is a color filter;

Fig. 5 is a diagram for explaining the relationship between the V-shaped groove direction (45 °) of the alignment layer formed on the array substrate and the scanning laser beam when the upper surface of the liquid crystal panel 8 is an array substrate.

FIG. 6 shows an example in which the scanning direction of the laser beam B4 shown in FIG. 5 is perpendicular or horizontal to the pixel;

7 is a diagram showing the configuration of a raster defect correction apparatus according to a second embodiment of the present invention.

※ Explanation of code about main part of drawing ※

1: controller

2: Q switch pulse laser

3: expander

4: attenuator

5: optical slit

6: relay lens

7: objective lens

8: liquid crystal panel

9: stage

10: polarizer

11: back light

12: beam splitter

13: polarizer

14: camera

15: image processing apparatus

Claims (12)

A raster defect correction method of correcting raster defects by canceling the alignment of the grooves of the alignment layer in contact with the liquid crystal layer of the liquid crystal display device, By scanning the alignment layer with a laser beam in which the longitudinal direction of the beam shape is orthogonal to the groove direction of the alignment layer, the groove of the alignment layer is erased, When the groove direction of the alignment layer is formed at 45 ° or 135 °, the beam shape of the laser beam is controlled according to the progress of the scanning, and the energy of the laser beam is controlled according to the progress of the scanning. Raster defect correction method characterized in that. A raster defect correction method for correcting raster defects by canceling the alignment of the grooves of the alignment layer in contact with the liquid crystal layer of the liquid crystal display device, By scanning the alignment layer with the first laser beam orthogonal to the groove direction of the alignment layer on the color filter side of the liquid crystal display device, the groove of the alignment layer is erased, The groove of the alignment layer is erased by scanning the alignment layer with a second laser beam orthogonal to the groove direction of the alignment layer on the glass substrate side facing the color filter through the liquid crystal layer, When the groove direction of one of the alignment layers in contact with the liquid crystal layer is formed at 45 ° and the other groove direction is formed at 135 °, the shape of each beam of the first and second laser beams is controlled as the scanning progresses. And controlling the energy of the first and second laser beams as the scanning proceeds. delete delete delete The method according to claim 1 or 2, And scanning the alignment layer with the laser beam sequentially emitted by superimposing the laser beams. The method according to claim 1 or 2, And the scanning direction of the laser beam is a groove direction of the alignment layer. The method according to claim 1 or 2, And the scanning direction of the laser beam is one side direction of a pixel of the liquid crystal display device when the groove direction of the alignment layer is formed to be 45 degrees or 135 degrees. A raster defect correction apparatus for correcting raster defects by canceling the alignment of the grooves of the alignment layer in contact with the liquid crystal layer of the liquid crystal display device, Beam shape control means for generating a laser beam in which the longitudinal direction of the beam shape is orthogonal to the groove direction of the alignment layer; And Means for scanning the alignment layer with the laser beam, The beam shape control means, when the groove direction of the alignment layer is formed to 45 ° or 135 °, the size of the longitudinal direction of the beam shape in accordance with the progress of the scanning of the laser beam, and the energy of the laser beam And control means for controlling the laser beam, and controlling the energy of the laser beam as the scanning of the laser beam proceeds. delete delete A raster defect correction apparatus for correcting raster defects by canceling the alignment of the grooves of the first and second alignment layers in contact with the liquid crystal layer of the liquid crystal display device, Beam shape control means for generating a first laser beam in which the longitudinal direction of the beam shape is orthogonal to the groove direction of the first alignment layer and a second laser beam in which the longitudinal direction of the beam shape is orthogonal to the groove direction of the second alignment layer ; And Means for scanning the first alignment layer with the first laser beam and scanning the second alignment layer with the second laser beam, The beam shape control means is adapted to proceed with scanning of the laser beam when the groove direction of one of the first alignment layer and the second alignment layer is formed at 45 ° and the other groove direction is formed at 135 °. Accordingly, control means for controlling each beam shape of the first laser beam and the second laser beam, and also controlling the energy of the first and second laser beams, is provided for the first and second laser beams. And controlling the energy of the first and second laser beams as the scanning proceeds.