JP2005173499A - Liquid crystal display and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display in which a display defect can be corrected so as to obtain higher display quality than a liquid crystal display corrected by a conventional defect correcting method, and to provide a method for manufacturing the display (defect correcting method). <P>SOLUTION: The liquid crystal display comprises: an active matrix substrate 50 on which pixel electrodes 6 and TFTs 5 connected to the pixel electrodes 6 are arranged in a matrix; a counter substrate opposing to the active matrix substrate 50; and a liquid crystal layer held between the substrates; wherein a pixel is defined corresponding to each pixel electrode 6. A conductive layer 14 is disposed on the active matrix substrate 50 and functions as a defect correcting means to electrically connect the pixel electrode 6 of each pixel to the TFT 5 in the next pixel adjacent in one direction to the pixel electrode 6 so that when a pixel is a defective pixel, the defective pixel can be corrected. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device and a manufacturing method thereof, and more particularly, to a defect correcting method for defective pixels.

  An active matrix liquid crystal display device has a switching element such as a thin film transistor (hereinafter abbreviated as TFT) for each pixel, which is the minimum unit of an image, and can individually light each pixel. For example, it is widely used as a display for personal computers and wall-mounted televisions.

  A general liquid crystal display device includes an active matrix substrate in which a plurality of pixel electrodes are arranged in a matrix, a counter substrate having a common electrode, and a liquid crystal layer sandwiched between the two substrates.

  FIG. 7 is a schematic plan view of an active matrix substrate 30 of a general liquid crystal display device, and FIG. 8 is an equivalent circuit diagram of the liquid crystal display device.

  In this active matrix substrate 30, a plurality of gate lines 1 and a plurality of source lines 2 are arranged on an insulating substrate so as to be orthogonal to each other, and a TFT 5 is provided at each intersection of the gate line 1 and the source line 2. The capacitor lines 4 are provided between the gate lines 1 in parallel with the gate lines 1. Further, the pixel electrode 6 is provided in a region surrounded by the pair of gate lines 1 and source lines 2 corresponding to each TFT 5.

  The TFT 5 includes a gate electrode 1a that is a protruding portion of the gate line 1, a source electrode 2a that is a protruding portion of the source line 2, and a drain electrode 3 provided so as to face the source electrode 2a.

  The drain electrode 3 is connected to the pixel electrode 6 through a contact hole 6a, and a portion overlapping the capacitor line 4 is a capacitor electrode. The capacitor electrode constitutes an auxiliary capacitor together with the capacitor line 4 via the insulating film.

  In this liquid crystal display device, when an image is displayed, a gate signal is sent from a predetermined gate line 1, the TFT 5 connected to the gate line 1 is turned on, and at the same time, a source signal is sent from the source line 2. By writing a predetermined charge to the pixel electrode 6 through the source electrode 2a and the drain electrode 3, a potential difference is generated between the pixel electrode 6 and the common electrode 11, and the liquid crystal capacitor 70a and the auxiliary capacitor made of the liquid crystal layer 70 are generated. A predetermined voltage is applied to 20. Then, by changing the alignment state of the liquid crystal molecules constituting the liquid crystal layer 70 by the applied voltage, the transmittance of light incident from the outside is adjusted, and an image is displayed.

  By the way, in a liquid crystal display device having such a configuration, in recent years, in order to improve the aperture ratio of a pixel, a low resistance material is used for a gate line, a source line, and a capacitor line, and the line width is reduced. There is a strong tendency to improve TFT characteristics and improve TFT size by improving film quality. If such gate lines, source lines, capacitor lines, and TFTs are miniaturized, disconnection and short-circuiting of each wiring, TFT characteristic defects, etc. may occur due to dust, film forming conditions, etc. in the manufacturing process of the liquid crystal display device. Becomes higher. A liquid crystal display device including such a problem is detected as, for example, a dot-like or linear defect in a lighting inspection. Normally, a liquid crystal display device allows a certain number of point-like defects, but if the number of defects increases, the liquid crystal display device becomes defective.

  Thus, techniques for correcting such point defects have been proposed in the past and have been put into practical use in the production of liquid crystal display devices.

  For example, in Patent Document 1, a repair region is provided in an overlapping portion of a pixel electrode and a source line in advance in an active matrix substrate that constitutes a liquid crystal display device, and when any of the pixels is a defective pixel, A correction technique is disclosed in which the repair region corresponding to the defective pixel is irradiated with laser to short-circuit the pixel electrode and the source line, and the pixel electrode is directly driven by the source signal from the source line without passing through the TFT. Thereby, a defective pixel can be changed from a bright spot to a black spot.

Further, as shown in the schematic plan view of FIG. 9 and the equivalent circuit diagram of FIG. 10, when the TFT short-circuit defect 21 exists in the TFT 5 and the pixel is a defective pixel, the TFT 5 corresponding to the defective pixel The drain electrode 3 is cut by irradiating the drain electrode cutting portion 22 of the drain electrode 3 with laser, and the contact hole 26 is formed by irradiating the overlapping portion of the pixel electrode 6 and the capacitor line 4 with laser. There is also known a correction technique in which the pixel electrode 6 and the capacitor line 4 are short-circuited, and the pixel electrode 6 is directly driven by a capacitor signal from the capacitor line 4 without using the TFT 5.
Japanese Patent Laid-Open No. 11-305260

  However, in the correction of defective pixels in such a conventional liquid crystal display device, by performing laser irradiation, the bright spot defects are simply turned into black spots, and black spots always exist on the screen display.

  Moreover, today, when a liquid crystal display device is used for a large-sized television or the like, and a defect-free liquid crystal display device is required, such a defect correction method for blackening a bright spot is a defect, although the bright spot defect becomes inconspicuous. This is not an appropriate method because the pixel can always be viewed as a black spot.

  The present invention has been made in view of such a point, and the object of the present invention is to correct defective pixels so that the display quality is higher than that of a liquid crystal display device corrected by a conventional defect correction method. Another object of the present invention is to provide a liquid crystal display device and a method for manufacturing the same (defect correcting method).

  The liquid crystal display device of the present invention includes an active matrix substrate in which pixel electrodes and switching elements connected to the pixel electrodes are arranged in a matrix, a counter substrate facing the active matrix substrate, and a space between the two substrates. A liquid crystal layer sandwiched between, and a pixel is defined corresponding to each pixel electrode, wherein any one of the pixels is a defective pixel on the active matrix substrate In order to correct the defective pixel, there is provided defect correcting means for enabling electrical connection between a pixel electrode of each pixel and a switching element of an adjacent pixel adjacent in any direction. To do.

  According to the above configuration, since the defect correcting means is provided, when correcting the defective pixel, the pixel electrode of the defective pixel and the switching element of the adjacent pixel adjacent in either direction are electrically connected. The pixel defect can be corrected by connecting and causing the defect correcting means to function. Here, the defective pixel is displayed in the same manner as the adjacent pixel because the pixel electrode is driven by the switching element of the adjacent pixel by causing the defect correcting means to function. Therefore, the corrected pixel is not always a black dot display as in the conventional correction technique, but is close to a normal pixel display. Thereby, the defective pixel can be corrected so that the display quality is higher than that of the liquid crystal display device corrected by the conventional defect correcting method.

  In the liquid crystal display device of the present invention, the defect correcting means is provided so as to overlap a switching element of a pair of adjacent pixels via an insulating film, and a contact hole is formed in the insulating film so that both switching elements are provided. The pixel electrode of one pixel may be configured by a conductive layer that can be electrically connected to the switching element of the other pixel by being electrically connected.

  According to the above configuration, when correcting a defective pixel, laser irradiation or the like is performed on the overlapping portion between the switching element of the adjacent pixel and the conductive layer via the switching element of the defective pixel and the conductive layer. A contact hole can be formed in the overlapping insulating film so that the pixel electrode of the defective pixel can be electrically connected to the switching element of the adjacent pixel. Therefore, the defective pixel is displayed in the same manner as the adjacent pixel because the pixel electrode is driven by the switching element of the adjacent pixel. The corrected pixel is not always displayed as a black dot as in the conventional correction technique, but is close to a normal pixel display. Thereby, the defective pixel can be corrected so that the display quality is higher than that of the liquid crystal display device corrected by the conventional defect correcting method.

  In the liquid crystal display device of the present invention, the active matrix substrate or the counter substrate is provided with a color filter layer provided with a colored layer of a predetermined color corresponding to each pixel, and the defect correcting means A pair of adjacent pixels whose defects are corrected by the above may be provided with colored layers of the same color.

  According to the above configuration, the pair of adjacent pixels whose defects are corrected by the defect correcting means are provided with the same colored layer, and the pixel electrodes corresponding to the defective pixels are switched between adjacent pixels. Since it is driven by the element, the display of the defective pixel is exactly the same as the display of the adjacent pixel. Thereby, the defective pixel can be corrected so that the display quality is higher than that of the liquid crystal display device corrected by the conventional defect correcting method.

  Specifically, the color filter layer is generally provided with red, green, and blue colored layers corresponding to each pixel. For example, the color filter layer includes a defective pixel and an adjacent pixel that is adjacent via a defect correcting unit. When the green and red colored layers are provided, the defective pixel is a bright spot when the entire screen is displayed in red, and the pixel corresponding to the display defect is a black dot when the entire screen is displayed in green. Further, when the entire screen is displayed in blue, the pixel corresponding to the display defect is normal. Therefore, if the colored layers corresponding to a pair of adjacent pixels whose defects are corrected by the defect correcting means are not the same color, the defective pixels will be black spot defects or bright spot defects.

  However, as described above, if the colored layers corresponding to a pair of adjacent pixels whose defects are corrected by the defect correcting means are the same color layers, the pair of pixels always display the same color. The defective pixel is displayed close to a normal pixel.

  The liquid crystal display device of the present invention is formed on the active matrix substrate so as to extend in a direction crossing the adjacent direction corresponding to a pair of adjacent pixels whose defects are corrected by the defect correcting means. A pair of capacitance lines may be provided, and the pair of capacitance lines may be electrically connected.

  According to the above configuration, since the pair of capacitor lines are electrically connected, even if one of the pair of capacitor lines is disconnected, the other capacitor line can be used as the redundant wiring. For this reason, it is possible to cause the auxiliary capacitance belonging to one disconnected capacitance line to function normally. As a result, the liquid crystal display device of the present invention can suppress a decrease in applied voltage because the auxiliary capacitor functions normally even if one of the pair of capacitor lines is disconnected. The display quality is higher than that of the liquid crystal display device modified by the method.

  The liquid crystal display device of the present invention is formed on the active matrix substrate so as to extend in a direction crossing the extending direction of the capacitance line corresponding to a pair of adjacent pixels whose defects are corrected by the defect correcting means. The source line is provided in the same layer as the switching element, and the source line and at least one switching element of the pair of pixels are arranged on the capacitor line with an interval in the extending direction of the capacitor line. It may be.

  According to the above configuration, the source line is provided in the same layer as the switching element, and the source line and at least one switching element of a pair of adjacent pixels whose defects are corrected by the defect correcting means are on the capacitance line. Since the capacitor lines are arranged at intervals in the extending direction, the source line and the switching element may be short-circuited on the capacitor line.

  When a short-circuit defect occurs between the source line and the switching element, when correcting the defective pixel due to the short-circuit defect, when the laser irradiation is performed on the part of the short-circuit defect between the source line and the switching element, the source In the liquid crystal display device of the present invention, there is a pair of capacitor lines, and the pair of capacitor lines are electrically connected. Therefore, even if one of the pair of capacitor lines is disconnected, the other capacitor line can be used as the redundant wiring. For this reason, it is possible to cause the auxiliary capacitance belonging to one disconnected capacitance line to function normally. As a result, the liquid crystal display device of the present invention suppresses a decrease in applied voltage because the auxiliary capacitor functions normally even when one of the pair of capacitor lines is disconnected when correcting a defective pixel. Therefore, the display quality is higher than that of the liquid crystal display device corrected by the conventional defect correcting method.

  The liquid crystal display device of the present invention includes an active matrix substrate in which pixel electrodes and switching elements connected to the pixel electrodes are arranged in a matrix, a counter substrate facing the active matrix substrate, and a space between the two substrates. A liquid crystal layer sandwiched between, and a pixel is defined corresponding to each pixel electrode, wherein any one of the pixels is a defective pixel, and the pixel electrode The defect is corrected by being electrically connected to a switching element of an adjacent pixel adjacent in the direction.

  According to the above configuration, since the pixel electrode of the defective pixel is electrically connected to the switching element of the adjacent pixel adjacent in either direction and the defect is corrected, the pixel electrode of the defective pixel is the adjacent pixel. It is driven by the switching element and is displayed in the same manner as the adjacent pixel. Therefore, the corrected pixel is not always a black dot display as in the conventional correction technique, but is close to a normal pixel display. Thereby, the display quality becomes higher than that of the liquid crystal display device corrected by the conventional defect correcting method.

  In the liquid crystal display device of the present invention, a pair of capacitors are formed on the active matrix substrate so as to extend in a direction crossing the adjacent direction corresponding to the pixels and adjacent pixels, and are electrically connected to each other. And a source line formed so as to extend in a direction intersecting with the direction in which the capacitor line extends is provided in the same layer as the switching element, and the source line, the pixel, and the adjacent pixel At least one of the switching elements is disposed on the capacitor line with an interval in the extending direction of the capacitor line, and any one of the pixels is caused by a short circuit between the source line and the switching element on the capacitor line. A defective pixel, the corresponding capacitance line is cut, and the electrical connection between the source line and the switching element is released to correct the defect. Good.

  According to the above configuration, the capacitor line corresponding to the defective pixel due to the short circuit between the source line and the switching element is cut, and the electrical connection between the source line and the switching element is released to correct the defect. As a result, of the pair of capacitor lines, the uncut capacitor line becomes a redundant wiring of the cut capacitor line, and the auxiliary capacitor belonging to the cut capacitor line functions normally. Therefore, the corrected pixel does not always display a black dot as in the conventional correction technique, but is close to a normal pixel display, and an effect of suppressing a decrease in applied voltage due to the auxiliary capacitor is maintained. Therefore, the display quality is higher than that of the liquid crystal display device corrected by the conventional defect correcting method.

  The manufacturing method of the present invention includes an active matrix substrate in which pixel electrodes and switching elements connected to the pixel electrodes are arranged in a matrix, a counter substrate facing the active matrix substrate, and a gap between the two substrates. And a defective pixel detection step for detecting the presence of a defective pixel, wherein the pixel is defined in correspondence with each pixel electrode. A defect correction step of correcting a defect by electrically connecting the pixel electrode of the defective pixel detected in the step to a switching element of an adjacent pixel adjacent in any direction.

  According to the above method, the defective pixel detected in the defective pixel detection step is corrected by electrically connecting the pixel electrode to the switching element of the adjacent pixel in the defect correction step. For this reason, the defective pixel is displayed in the same manner as its neighboring pixels, so that it is not always a black dot display as in the conventional correction technique, but is close to a normal pixel display. Thereby, the manufacturing method of the present invention can correct the defect of the liquid crystal display device having the defective pixel so that the display quality is higher than that of the liquid crystal display device corrected by the conventional defect correction method.

  Since the liquid crystal display device of the present invention is provided with defect correcting means, when correcting the defective pixel, the pixel electrode of the defective pixel and the switching element of the adjacent pixel adjacent in either direction are electrically connected. A pixel defect can be corrected by connecting to and causing the defect correcting means to function. For this reason, the defective pixel is displayed in the same manner as its neighboring pixels, so that it is not always a black dot display as in the conventional correction technique, but is close to a normal pixel display. Thereby, the defective pixel can be corrected so that the display quality is higher than that of the liquid crystal display device corrected by the conventional defect correcting method.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, a liquid crystal display device using TFTs as switching elements will be described as an example. However, the present invention is not limited to the following embodiment, and may have other configurations.

  The liquid crystal display device according to the embodiment of the present invention will be described below.

  FIG. 1 is a schematic plan view of an active matrix substrate 50 constituting the liquid crystal display device of the present invention. FIG. 2 is a schematic cross-sectional view of the liquid crystal display device 100 taken along the line AA ′ in FIG. 3 is an equivalent circuit diagram thereof. 1 and the cross-sectional schematic diagram of FIG. 2 show two pixels adjacent to each other.

  The liquid crystal display device 100 includes an active matrix substrate 50, a counter substrate 60 provided so as to face the active matrix substrate 50, and a liquid crystal layer 70 provided so as to be sandwiched between both the substrates 50 and 60. Yes.

  In the active matrix substrate 50, a plurality of gate lines 1 and a plurality of source lines 2 are disposed on the insulating substrate 10 so as to be orthogonal to each other, and at each intersection of the gate lines 1 and the source lines 2, Between the gate lines 1, the TFT 5 is provided with a pair of capacitance lines 4 in parallel with the gate lines 1. Further, the pair of capacitance lines 4 are connected to each other via a capacitance line connection portion 4 a provided on the source line 2. A pixel electrode 6 is provided in a display area corresponding to each TFT 5 and surrounded by the gate line 1, the capacitor line 4, and the pair of source lines 2.

  The active matrix substrate 50 has a multi-layered structure in which the gate insulating film 8 and the interlayer insulating film 9 are sequentially stacked on the insulating substrate 10.

  Between the insulating substrate 10 and the gate insulating film 8, a gate line 1, a gate electrode 1a, a capacitor line 4 and a conductive layer 14 are provided.

  A semiconductor layer 15 constituting the TFT 5 is provided between the gate insulating film 8 and the interlayer insulating film 9. A source line 2 and a gate line from the source line 2 corresponding to each TFT 5 are provided above the semiconductor layer 15. A source electrode 2a protruding in the extending direction of 1 and a drain electrode 3 facing the source electrode 2a are provided.

  A pixel electrode 6 connected to the drain electrode 3 through a contact hole 6 a is provided on the interlayer insulating film 9, and an alignment film 7 is provided on the pixel electrode 6.

  The drain electrode 3 extends to a region where the capacitor line 4 is disposed, and a portion facing the capacitor line 4 serves as an auxiliary capacitor electrode. The auxiliary capacitance electrode constitutes an auxiliary capacitance 20 together with the capacitance line 4 via the gate insulating film 8.

  The conductive layer 14 functions as a defect correcting means, and is located between adjacent pixels and between a pair of adjacent capacitor lines 4. The conductive layer 14 is connected to the drain electrode 3 of both pixels via the gate insulating film 8. It has an overlapping part.

  The counter substrate 60 has a multilayer stacked structure in which the color filter layer 13, the overcoat layer 12, the common electrode 11, and the alignment film 7 'are stacked in this order on the insulating substrate 10'.

  The color filter layer 13 is provided with a colored layer 13a of one color of red, green and blue corresponding to each pixel, and a black matrix 13b is provided as a light shielding film between the colored layers 13a. . In the pixels adjacent to each other via the conductive layer 14, the colored layer 13a of the same color is disposed.

  The liquid crystal layer 70 is made of a nematic liquid crystal material having electro-optical characteristics.

  In the liquid crystal display device 100, one pixel is formed for each pixel electrode 6. When a gate signal is sent from the gate line 1 and the TFT 5 is turned on in each pixel, the liquid crystal display device 100 starts from the source line 2. A source signal is sent and a predetermined charge is written into the pixel electrode 6 via the source electrode 2 a and the drain electrode 3, and a potential difference is generated between the pixel electrode 6 and the common electrode 11. A predetermined voltage is applied to the liquid crystal capacitor 70 a and the auxiliary capacitor 20. In the liquid crystal display device 100, an image is displayed by adjusting the transmittance of light incident from the outside by utilizing the change in the alignment state of the liquid crystal molecules according to the magnitude of the applied voltage.

  Next, a manufacturing method of the liquid crystal display device according to the embodiment of the present invention will be described.

<Active matrix substrate manufacturing process>
First, a metal film made of Al (thickness of about 200 nm (may be a metal film made of Ti, Cr, Cu, Ta, etc.)) is formed on the entire substrate on the insulating substrate 10 such as a glass substrate by a sputtering method. Then, the gate line 1, the gate electrode 1 a, the capacitor line 4, and the conductive layer 14 are formed by pattern formation by a photolithography technique (hereinafter referred to as “PEP technique”).

  Next, a silicon nitride film (thickness of about 400 nm) or the like is formed on the entire substrate on the gate line 1, the gate electrode 1 a, the capacitor line 4, and the conductive layer 14 by a CVD (Chemical Vapor Deposition) method. Form.

  Next, an intrinsic amorphous silicon film (thickness of about 150 nm) and a phosphorus-doped n + amorphous silicon film (thickness of about 50 nm) are continuously formed by CVD on the entire substrate on the gate insulating film 8. Thereafter, an island pattern is formed on the gate electrode 1a by the PEP technique to form a semiconductor layer 15 composed of an intrinsic amorphous silicon layer and an n + amorphous silicon layer.

  Next, a metal film made of Al (about 200 nm thick (may be a metal film made of Ti, Cr, Cu, Ta, etc.)) is formed on the entire substrate on the gate insulating film 8 on which the semiconductor layer 15 is formed. A film is formed by a sputtering method, and then a pattern is formed by a PEP technique to form a source line 2, a source electrode 2a, and a drain electrode 3.

  Next, the channel portion is formed by etching away the n + amorphous silicon layer of the semiconductor layer 15 using the source electrode 2a and the drain electrode 3 as a mask.

  Next, a silicon nitride film (thickness of about 300 nm) or the like is formed on the entire substrate on the source electrode 2a and the drain electrode 3 by using the CVD method, and the protective insulating film 9 is formed.

  Next, a portion corresponding to the drain electrode 3 of the protective insulating film 9 is removed by etching to form a contact hole 6a.

  Next, a transparent conductive film (thickness of about 10 nm) made of an ITO (Indium Tin Oxide) film is formed on the entire substrate on the protective insulating film 9 by a sputtering method, and then a pattern is formed by a PEP technique to form a pixel electrode. 6 is formed.

  Next, a polyimide resin is applied to the entire substrate on the pixel electrode 6 with a thickness of about 100 nm to form the alignment film 7.

  The active matrix substrate 50 can be manufactured as described above.

  In the above-described manufacturing method of the active matrix substrate 50, the method of forming the semiconductor layer 15 from an amorphous silicon film is exemplified. However, the semiconductor layer 15 may be formed from a polysilicon film, and further, an amorphous silicon film and The polysilicon film may be subjected to laser annealing to improve crystallinity.

<Opposite substrate manufacturing process>
First, after forming a chromium thin film on the insulating substrate 10 ', a black matrix 13b is formed by pattern formation by the PEP technique.

  Next, a color filter layer 9 is formed by patterning any one of red, green and blue colored layers between the black matrices.

  Next, an acrylic resin is applied to the entire substrate on the color filter layer 6 to form the overcoat layer 12.

  Next, an ITO film is formed on the entire substrate on the overcoat layer 12 to form the common electrode 11.

  Next, a polyimide resin is applied to the entire substrate on the common electrode 11 to form an alignment film 7 ′.

  As described above, the counter substrate 60 can be manufactured.

<Liquid crystal display device manufacturing process>
First, a seal material made of a thermosetting epoxy resin or the like is applied to one of the active matrix substrate 50 and the counter substrate 60 by screen printing in a frame-like pattern lacking a liquid crystal inlet portion, and a liquid crystal layer is applied to the other substrate. A spherical spacer made of resin or silica having a diameter corresponding to the thickness of is dispersed.

  Next, the active matrix substrate 50 and the counter substrate 60 are bonded together, the sealing material is cured, and empty cells are formed.

  Next, a liquid crystal material is injected between the active matrix substrate 50 and the counter substrate 60 of the empty cell by a decompression method to form a liquid crystal layer 70. Thereafter, a UV curable resin is applied to the liquid crystal injection port, the UV curable resin is cured by UV irradiation, and the injection port is sealed.

  As described above, the liquid crystal display device 100 of the present invention can be manufactured.

  In general, in the liquid crystal display device 100, the pixel electrode 6 is driven by the TFT 5, and as long as the TFT 5 operates normally, the pixel operates normally and no display problem occurs. However, if the TFT 5 becomes abnormal or a leak current is generated between the source line 2 and the pixel electrode 6 or the like, the corresponding pixel appears as a defective pixel in the inspection process, which causes a display problem.

  Next, a defect correction method (manufacturing method) in the liquid crystal display device 100 of the present invention will be described.

<< Method for correcting defective pixels caused by defective switching elements >>
FIG. 4 is a schematic plan view of an active matrix substrate 50a constituting a liquid crystal display device in which defective pixels are corrected, and the upper left part of FIG. 6 is an equivalent circuit diagram corresponding thereto.

  The active matrix substrate 50a includes an abnormal TFT 5a having a TFT short-circuit defect 21 in which the source electrode 2a and the drain electrode 3a are short-circuited.

<Defective pixel detection process (inspection process)>
For example, a gate inspection signal having a bias voltage of −10 V, a period of 16.7 msec, a pulse voltage of +15 V with a pulse width of 50 μsec is input to the gate line 1 to turn on all the TFTs 5. Further, a source inspection signal having a potential of ± 2 V whose polarity is inverted every 16.7 msec is inputted to the source line 2, and a charge corresponding to ± 2 V is applied to the pixel electrode 6 through the source electrode 2 a and the drain electrode 3 of each TFT 5. Write. At the same time, a common electrode inspection signal having a direct current potential of −1 V is input to the common electrode 11. As a result, a voltage is applied to the liquid crystal capacitor 70a configured between the pixel electrode 6 and the common electrode 11, and the pixel configured by the pixel electrode 6 is turned on, and a normally white mode (white voltage when no voltage is applied). Display) changes from white display to black display.

  At this time, the pixel having the abnormal TFT 5a cannot write a predetermined charge to the pixel electrode 6 and is not lit (bright spot).

  Thereby, the position of the pixel having the abnormal TFT 5a can be specified.

<Defect correction process>
(Drain electrode cutting process)
The drain electrode cutting portion 22 of the drain electrode 3a corresponding to the defective pixel detected in the defective pixel detection step is irradiated with laser light, the metal of the drain electrode cutting portion 22 is scattered, and the pixel electrode 6 and the abnormal TFT 5a are cut. The electrical connection between the pixel electrode 6 and the abnormal TFT 5a is released.

(Drain electrode connection process)
Laser light is irradiated to the overlapping portion of the drain electrode 3a and the drain electrode 3b of the adjacent pixel and the conductive layer. As a result, the gate insulating film 8 between the drain electrodes 3a and 3b and the conductive layer 14 is broken at the overlapping portion, and the metal forming the drain electrodes 3a and 3b is melted and contacted with the overlapping portion. A hole 23 is formed. As a result, the drain electrodes 3a and 3b and the conductive layer 14 become conductive and short-circuited, and the conductive layer 14 functions as a defect correcting means.

  Here, laser light irradiation will be described. The following description is a representative example and is not limited thereto.

~ Laser beam ~
An example of the laser beam is a YAG laser with a wavelength of 1064 nm. After confirming the laser intensity with a laser power measuring device, the laser beam is adjusted to an appropriate intensity with a filter or the like.

~ Alignment of irradiation position ~
On the monitor, a laser irradiation area is preset for the wiring pattern, the irradiation area is aligned with each pattern, and the laser beam adjusted as described above is irradiated.

  There are two types of irradiation methods. One is to set the irradiation size for the wiring pattern in advance, align the position, and then irradiate the melt and cutting simultaneously. The other is cutting. In this method, only a small area is set and irradiation is performed while moving the cutting part.

  As described above, in the liquid crystal display device, a defective pixel caused by the abnormal TFT 5a can be corrected.

  In the liquid crystal display device in which the above steps are completed, a contact hole 23 is formed in an overlapping portion between the drain electrode 3a of the pixel having the abnormal TFT 5a and the drain electrode 3b of the adjacent pixel and the conductive layer 14, and both the drain electrodes 3a and 3b. Are electrically connected through the conductive layer 14 to correct the defect. Therefore, the pixel electrode 6 of the pixel having the abnormal TFT 5 a is driven by the TFT 5 b of the adjacent pixel through the contact hole 23 and the conductive layer 14. Further, since the colored layers corresponding to a pair of pixels adjacent to each other through the conductive layer 14 have the same color, the corrected defective pixel has the same display as that of the adjacent pixel, and the conventional correction is made. It is not always a black dot display as in the technology, but close to normal pixel display. Thereby, the liquid crystal display device in which the defective pixel of the present invention is corrected becomes a display device having higher display quality than the liquid crystal display device corrected by the conventional defect correction method. As a result, the pixel that has been corrected as described above is not functioning normally, but is visually difficult to distinguish as a defective pixel.

<< Method for correcting defective pixel caused by source-drain short circuit >>
A defect correcting method in a liquid crystal display device having a defective pixel due to a source / drain short circuit in addition to the defective pixel due to the above switching element failure will be described below.

  FIG. 5 is a schematic plan view of an active matrix substrate 50b constituting a liquid crystal display device in which defective pixels are corrected, and the lower right portion of FIG. 6 is an equivalent circuit diagram corresponding thereto.

  This active matrix substrate 50b includes an abnormal TFT 5a having a TFT short-circuit defect portion 21 in which the source electrode 2a and the drain electrode 3a are short-circuited, and a source-drain short-circuit defect portion in which the source line 2 and the drain electrode 3b are short-circuited on the capacitance line 4. 24. Note that the source / drain short-circuit defect portion 24 exists in another pixel adjacent to the pixel having the TFT short-circuit defect portion 21 or in another pixel not adjacent to the pixel having the TFT short-circuit defect portion 21 even in the pixel having the TFT short-circuit defect portion 21. Also good.

<Defective pixel detection process (inspection process)>
As described in the defective pixel detection step (inspection step) of the method for correcting a defective pixel caused by the switching element defect, a voltage is applied to the liquid crystal capacitor 70a formed between the pixel electrode 6 and the common electrode 11. Then, the pixel is turned on to change from white display to black display.

  At this time, in a pixel having the source / drain short-circuit defect portion 24, a predetermined charge cannot be written to the pixel electrode 6, and the pixel is not lit (bright spot).

  Thereby, the position of the pixel having the source / drain short-circuit defect 24 can be specified.

  Of the defective pixels, the defective pixels caused by the abnormal TFT 5a can be corrected by executing as described in the correction method for the defective defective switching element, while the defective pixels 24 are caused by the source / drain short-circuit defective portion 24. The defective pixel to be corrected is corrected by executing the following steps.

<Defect correction process>
(Source drain short cut process)
The capacitive line cutting unit 25 that simultaneously cuts the source / drain short-circuit defective part 24 and the capacitive line 4 corresponding to the defective pixel detected in the defective pixel detection step is irradiated with laser light, and the metal of the cutting part 25 is scattered, so that the capacitive line 4, the source line 2 and the drain electrode 3 b are disconnected, and the electrical connection between the source line 2 and the drain electrode 3 b is released.

  As described above, a defective pixel caused by a short circuit between the source line 2 and the drain electrode 3b of the liquid crystal display device can be corrected.

  In the liquid crystal display device in which the above process is completed, the capacitor line 4 corresponding to the defective pixel due to the short circuit between the source line 2 and the drain electrode 3b is cut, and the electric current between the source line 2 and the drain electrode 3b is cut. The connection has been broken and the defect has been corrected. One of the pair of capacitor lines 4 is disconnected, but the other capacitor line 4 is the redundant wiring, so that the auxiliary capacitor belonging to the one disconnected capacitor line 4 functions normally. Will do. Therefore, the corrected pixel does not always display a black dot as in the conventional correction technique, but is close to a normal pixel display, and an effect of suppressing a decrease in applied voltage due to the auxiliary capacitor is maintained. Therefore, the display quality is higher than that of the liquid crystal display device corrected by the conventional defect correcting method.

  As described above, the liquid crystal display device of the present invention is not a black dot display as in the prior art, even if a defective pixel is corrected, but is close to a normal pixel display. This is useful for a liquid crystal display device for use in a television or the like.

It is a plane schematic diagram of the active matrix substrate 50 which comprises the liquid crystal display device which concerns on embodiment of this invention. 1 is a schematic cross-sectional view of a liquid crystal display device 100 according to an embodiment of the present invention. 1 is an equivalent circuit diagram of a liquid crystal display device according to an embodiment of the present invention. It is a plane schematic diagram of the active matrix substrate 50a which shows the manufacturing method of the liquid crystal display device which concerns on embodiment of this invention. It is a plane schematic diagram of the active matrix substrate 50b which shows the manufacturing method of the liquid crystal display device which concerns on embodiment of this invention. It is an equivalent circuit diagram which shows the manufacturing method of the liquid crystal display device which concerns on embodiment of this invention. It is a plane schematic diagram of the active matrix substrate 30 which comprises the conventional liquid crystal display device. It is an equivalent circuit diagram of a conventional liquid crystal display device. It is a plane schematic diagram of the active matrix substrate 30a which shows the defect correction method of the conventional liquid crystal display device. It is the equivalent circuit schematic of the liquid crystal display device which shows the defect correction method of the conventional liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gate line 1a Gate electrode 2 Source line 2a Source electrode 3, 3a, 3b Drain electrode 4 Capacitance line 4a Capacitance line connection part 5, 5a, 5b TFT
6 Pixel electrodes 6a, 23, 26 Contact holes 7, 7 'Alignment film 8 Gate insulating film 9 Interlayer insulating film 10, 10' Insulating substrate 11 Common electrode 12 Overcoat layer 13 Color filter layer 13a Colored layer 13b Black matrix 14 Conductive layer 15 Semiconductor layer 20 Auxiliary capacitor 21 TFT short-circuit defect portion 22 Drain electrode cut portion 24, 27 Source drain short-circuit defect portion 25 Capacitance line cut portion 28 Source line cut portion 30, 30a, 30b, 50, 50a, 50b Active matrix substrate 60 Opposing Substrate 70 Liquid crystal layer 70a Liquid crystal capacity 100 Liquid crystal display device

Claims (8)

An active matrix substrate in which pixel electrodes and switching elements connected to the pixel electrodes are arranged in a matrix, a counter substrate facing the active matrix substrate, a liquid crystal layer sandwiched between the two substrates, A liquid crystal display device in which a pixel is defined corresponding to each pixel electrode,
The active matrix substrate includes a pixel electrode of each pixel and a switching element of an adjacent pixel adjacent to either direction so that the defective pixel can be corrected when any of the pixels is a defective pixel. A liquid crystal display device comprising defect correcting means for enabling electrical connection. The liquid crystal display device according to claim 1,
The defect correcting means is provided so as to overlap a switching element of a pair of adjacent pixels via an insulating film, and by forming a contact hole in the insulating film and electrically connecting both switching elements, A liquid crystal display device comprising a conductive layer that allows a pixel electrode of one pixel to be electrically connected to a switching element of the other pixel. The liquid crystal display device according to claim 1,
The active matrix substrate or the counter substrate is provided with a color filter layer provided with a colored layer of a predetermined color corresponding to each pixel,
A liquid crystal display device, wherein a pair of adjacent pixels whose defects are corrected by the defect correcting means are provided with colored layers of the same color. The liquid crystal display device according to claim 1,
The active matrix substrate is provided with a pair of capacitance lines formed corresponding to a pair of adjacent pixels whose defects are corrected by the defect correcting means so as to extend in a direction intersecting with the adjacent directions. A liquid crystal display device, wherein the pair of capacitance lines are electrically connected. The liquid crystal display device according to claim 4,
A source line formed on the active matrix substrate so as to extend in a direction intersecting with a direction in which the capacitor line extends corresponding to a pair of adjacent pixels whose defects are corrected by the defect correcting means is provided on the switching element. A liquid crystal, wherein the source line and at least one switching element of the pair of pixels are arranged on the capacitor line at an interval in a direction in which the capacitor line extends. Display device. An active matrix substrate in which pixel electrodes and switching elements connected to the pixel electrodes are arranged in a matrix, a counter substrate facing the active matrix substrate, a liquid crystal layer sandwiched between the two substrates, A liquid crystal display device in which a pixel is defined corresponding to each pixel electrode,
Any one of the above-mentioned pixels is a defective pixel, and the pixel electrode is electrically connected to a switching element of an adjacent pixel adjacent in any direction to correct the defect. . The liquid crystal display device according to claim 6,
In the active matrix substrate,
Corresponding to the pixel and the adjacent pixel, a pair of capacitor lines formed so as to extend in a direction intersecting with the adjacent direction and electrically connected to each other are provided, and a direction in which the capacitor lines extend Source lines formed to extend in the intersecting direction are provided in the same layer as the switching element,
The source line and the switching element of at least one of the pixel and the adjacent pixel are arranged on the capacitor line at an interval in a direction in which the capacitor line extends;
One of the pixels is a defective pixel caused by a short circuit between the source line and the switching element on the capacitor line, and the corresponding capacitor line is cut off, so that the source line and the switching element are not connected. The liquid crystal display device is characterized in that the electrical connection is canceled and the defect is corrected. An active matrix substrate in which pixel electrodes and switching elements connected to the pixel electrodes are arranged in a matrix, a counter substrate facing the active matrix substrate, a liquid crystal layer sandwiched between the two substrates, A manufacturing method of a liquid crystal display device in which pixels are defined corresponding to each pixel electrode,
A defective pixel detection step for detecting the presence of the defective pixel;
A defect correction step of correcting a defect by electrically connecting a pixel electrode of the defective pixel detected in the defective pixel detection step to a switching element of an adjacent pixel adjacent in either direction;
A method for manufacturing a liquid crystal display device, comprising:

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