JP2006201814A - In-plane-switching liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an in-plane-switching liquid crystal display device which has a large opening part 50 and is high-quality by improving shielding effect for a leakage electric field from a signal line 3 and reducing the light-shielding area. <P>SOLUTION: The in-plane-switching liquid crystal display device is provided with a TFT array substrate 20, comprising a scanning line, the signal line 3, a pixel formed by intersection of the scanning line and the signal line 3, a thin-film transistor disposed on the pixel, a drive electrode 5 connected to the thin-film transistor, a counter electrode 6, disposed opposite to the drive electrode and common wiring which connects the counter electrode 6 to a counter electrode of another pixel; a counter substrate 30 disposed so as to face the TFT array substrate; and a liquid crystal 11, which is enclosed between the TFT array substrate 20 and the counter substrate 30 and is driven by an electric field parallel to the substrate surface which is generated by the drive electrode 5 and the counter electrode 6, wherein on the TFT array substrate 20, the drive electrode 5 and the counter electrode 6 are formed on a layer, close to the liquid crystal 11 different from the layer on which the signal line 3 is formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an in-plane switching type (hereinafter referred to as IPS type) liquid crystal display device that drives a liquid crystal by generating a parallel electric field with respect to an array substrate, and more specifically from a signal line. The present invention relates to a structure of a high-brightness liquid crystal display device in which an aperture ratio is increased by reducing the influence of a leakage electric field and reducing a light shielding region.

In an active matrix liquid crystal display device, an in-plane switching method (that is, an IPS method) in which the direction of an electric field applied to the liquid crystal is parallel to the array substrate is mainly used as a method for obtaining a wide viewing angle. (For example, see JP-A-8-254712). When this method is adopted, it has been clarified that there is almost no change in contrast and inversion of gradation level when the viewing angle direction is changed (for example, M. Oh-e, et al., AsiaDisplay, 95, pp. 57
7-580).

  FIG. 18 schematically shows the structure of one pixel of a conventional IPS liquid crystal display device. FIG. 18 (a) is a plan view thereof, and FIG. 18 (b) is a cross-sectional view of FIG. It is sectional drawing in A '. FIG. 19 is an equivalent circuit of one pixel constituting the pixel electrode of the IPS liquid crystal display device, and FIG. 20 is a circuit configuration diagram illustrating a circuit of the IPS liquid crystal display device. In FIG. 18, 1 is a glass substrate, 2 is a scanning line, 3 is a signal line, 4 is a thin film transistor (TFT), 5 is a drive electrode, 6 is a counter electrode, 7 is a storage capacitor forming electrode, 8 is a common wiring, 9 Are a gate insulating film, 10 is a protective film, 11 is a liquid crystal, 12 is a black matrix (BM), 14 is a contact hole, 15 is a source electrode, and 16 is a drain electrode. Reference numeral 20 denotes an array substrate (comprised of a glass substrate 1, a signal line 3, a drive electrode 5, a counter electrode 6 and the like), 30 denotes a counter substrate disposed facing the array substrate 20, and 40 denotes a signal line 3. A slit 50, which is a gap between the counter electrode 6 and the counter electrode 6, is an opening. 19 and 20, the same reference numerals as those in FIG. 18 denote the same or equivalent elements as those in FIG. 18.

The schematic configuration and operation of a conventional IPS liquid crystal display device will be described with reference to FIGS. In FIG. 20, the scanning line 2 connected to the scanning line driving circuit and the signal line 3 connected to the signal line driving circuit intersect at almost right angles, so that a plurality of grids surrounded by the scanning line 2 and the signal line 3 are obtained. Shaped pixels. A thin film transistor (TFT Thin-Film-Transistor) is provided at each intersection of the scanning line and the signal line forming the lattice-like pixel.

  FIG. 19 shows this state by an equivalent circuit. The thin film transistor (TFT) 4 is a semiconductor element having three electrodes, a gate electrode, a source electrode 15, and a drain electrode 16. The gate electrode is connected to the scanning line 2 extending from the scanning line driving circuit, and the source electrode 15 is driven by a signal line. Connected to the signal line 3 connected to the circuit. The remaining drain electrode 16 is connected to the drive electrode 5 and drives the liquid crystal by an electric field generated between the counter electrode 6. Reference numeral 13 denotes a storage capacitor that holds electric charges between the drive electrode 5 and the counter electrode 6. Next, the structure of one pixel will be described with reference to FIGS. 18 (a) and 18 (b). A pixel formed by intersecting the scanning line 2 and the signal line 3 is provided with a driving electrode 5 and a counter electrode 6 for driving the liquid crystal layer, and a thin film transistor (TFT) 4. The thin film transistor (TFT) 4 has three electrodes, and the scanning line 2 connected to the scanning line driving circuit shown in FIG. 20 is connected to the gate electrode of the thin film transistor (TFT) 4 and the scanning line driving circuit outputs it. A scanning signal to be applied is applied to the gate electrode of the thin film transistor (TFT) 4.

  The signal line 3 connected to the signal line driving circuit is connected to the source electrode 15 of the thin film transistor 4 (TFT) and transmits a video signal output from the signal line driving circuit. The drain electrode 16 of the thin film transistor (TFT) 4 is connected to the drive electrode 5 through the contact hole 14 as shown in FIG. In the same pixel, the counter electrode 6 is provided so as to face and mesh with the drive electrode 5. The counter electrode 6 is connected to the common wiring 8. The common wiring 8 connects the counter electrode 6 provided in each pixel on the TFT array substrate 20.

  Next, the structure of the pixel cross section will be described with reference to FIG. Reference numeral 1 denotes a glass substrate, on which a drive electrode 5 and a counter electrode 6 are formed. The same layer as the drive electrode 5 and the counter electrode 6 is not shown in FIG. 18B. The scanning line 2 and the common wiring 8 are also formed. Next, the gate insulating film 9 is laminated, and the signal line 3 is formed on the gate insulating film 9. Although not shown in FIG. 18B, the storage capacitor forming electrode 7 is also formed in the same layer as the signal line 3. A protective film 10 is further laminated on the signal line 3 to form a TFT array substrate 20. The TFT array substrate 20 and the counter substrate 30 are overlapped, and the liquid crystal 11 is sealed between the TFT array substrate 20 and the counter substrate 30 to manufacture an IPS liquid crystal display device.

  Since the IPS type liquid crystal display device is a method of generating an electric field along the surface of the TFT array substrate 20 between the drive electrode 5 and the counter electrode 6 provided on the TFT array substrate 20 and driving the liquid crystal, Reference numeral 30 denotes an electrodeless substrate having no electrode. The counter substrate 30 is provided with a black matrix (BM) 12 that is a light shielding film. Although not shown, the backlight provided on the lower side of the TFT array substrate in FIG. The light leaking from the slit 40 is shielded.

  A region surrounded by a broken line 50 indicates an opening per pixel, and plays a role of a window through which light having a backlight as a light source is transmitted. However, the light from the backlight is blocked by the drive electrode 5, the counter electrode 6, the black matrix 12, and the like, and as a result, the image quality of the liquid crystal display is greatly affected. Therefore, it is a problem to reduce the ratio of the area of the drive electrode 5, the counter electrode 6, the black matrix 12, and the like occupying the area of the opening 50.

  The configuration of the pixel of the conventional IPS liquid crystal display device has been described with reference to FIGS. Next, the operation of the IPS liquid crystal display device will be described. A thin film transistor (TFT) 4 provided in each pixel and having a gate electrode connected to the scanning line 2, a source electrode 15 connected to the signal line 3, and a drain electrode 16 connected to the drive electrode 5 is a semiconductor switching element. Is controlled. When a scanning signal is applied to the gate electrode of the thin film transistor (TFT) 4 from the scanning line driving circuit via the scanning line 2, all the thin film transistors (TFT) 4 in the row are switched on.

  When the gate electrode is switched on, the video signal transmitted from the signal line drive circuit flows to the drain electrode 16 via the source electrode 15 and is written to the drive electrode 5 connected to the drain electrode 16. The charge written to the drive electrode 5 is held between the counter electrode 6 and the current charge is held until the gate electrode is turned on again and a new video signal charge is written. In other words, the drive electrode 5 and the counter electrode 6 function as a kind of capacitor in that charges are written while the gate electrode is turned on, and the written charges are stored as they are when the gate electrode is turned off. Plays. The storage capacitor 13 shown in FIG. 19 increases the storage power of the capacitor. The storage capacitor 13 is formed by stacking the storage capacitor forming electrode 7 and the common wiring 8 with the gate insulating film 9 interposed therebetween. .

  By the way, in the conventional IPS type liquid crystal display device shown in FIG. 18, between the signal line 3 provided at the side edge of one pixel and the counter electrode 6 formed in parallel with the signal line 3. An electric field is generated due to the potential difference between the signal line 3 and the counter electrode 6. FIG. 21 shows an electric field generated between a signal line 3 and a counter electrode 6 of a conventional IPS liquid crystal display device having a TFT array substrate in which a drive electrode 5 and a counter electrode 6 are formed below the signal line 3. FIG. 6 is a diagram showing the influence of the electric field on the electric field generated between the drive electrode 5 and the counter electrode 6, and is obtained by simulating the change in potential generated between the drive electrode 5 and the counter electrode 6. FIG. 21 shows the calculation of the potential at the upper or lower portion of the window when a white window is displayed in a halftone with a relative transmittance of 50%.

  The drive electrode 5 is formed between the two counter electrodes 6 and it is desirable for the liquid crystal to be driven accurately that the potential distribution is symmetrical about the drive electrode 5. Referring to FIG. 21, the potential distribution in the region near the signal line 3 of the opening 50 is strongly influenced by the leakage electric field from the electric field generated between the signal line 3 and the counter electrode 6, and the potential distribution is You can see that it is asymmetric. This electric field is generated along the surface of the glass substrate 1 and causes problems such as crosstalk. For example, when a white window is displayed in a black display as shown in FIG. 22, a display problem called “vertical crosstalk” occurs in which the luminance at the top and bottom of the window changes with respect to the other black display. To do.

  Hereinafter, an example of a normally black mode (a mode in which black is displayed when no voltage is applied) will be described with reference to FIG. When the window pattern as shown in FIG. 22 is displayed, the signal line 3 of the pixel in the window portion and the upper and lower portions of the window in the screen is opposed to the opposite electrode 6 during the selection period of the black display portion. 6 is applied, and a voltage necessary for white display is applied during the selection period of the white display portion.

  It is considered that a voltage having a value obtained by averaging the absolute value of the potential difference between the electrodes is effectively applied to the liquid crystal 11. Therefore, for example, when the black display selection period and the white display selection period are the same, an effective potential equal to that in the halftone display is applied between these signal lines 3 and the counter electrode 6. At this time, the liquid crystal on the slit 40 between the signal line 3 and the counter electrode 6 becomes a transmission mode by an electric field in a direction horizontal to the glass substrate 1 generated between the signal line 3 and the counter electrode 6. Furthermore, the electric field generated by the potential difference between the signal line 3 and the counter electrode 6 also affects the electric field between the drive electrode 5 and the counter electrode 6, and changes the liquid crystal in the black display portion to the transmission mode. As a result, crosstalk occurs.

  In order to prevent the occurrence of such vertical crosstalk, leakage light transmitted through the slit 40 between the signal line 3 and the counter electrode 6 is transmitted by a black matrix 12 (hereinafter abbreviated as BM) formed on the counter substrate 30. While shielding the light, the drive electrode 5 and the counter electrode 6 are separated from the counter electrode 6 and the signal line 3 at the end on the opening 50 side, and an electric field generated between the signal line 3 and the counter electrode 6 is generated. It is necessary to prevent interference with the electric field between them. However, when the drive electrode 5 and the counter electrode 6 are separated from the signal line 3 and the width of the counter electrode 6 adjacent to the signal line 3 is increased, the aperture ratio of the opening 50, that is, surrounded by a broken line in FIG. The ratio of the area obtained by subtracting the area of the drive electrode 5 and the counter electrode 6 from the area of the opening 50 to the area of the opening 50 is reduced, and the image quality is deteriorated. Therefore, in order to develop a high-quality liquid crystal display device, it is a problem to shield the electric field generated between the signal line 3 and the counter electrode 6 adjacent to the signal line 3 without reducing the aperture ratio. It was.

  Further, as apparent from FIG. 18B, the surface of the protective film 10 which is the upper layer film of the array substrate 20 has a step, and the distance (gap) from the counter substrate 30 is not constant. Therefore, uneven brightness tends to occur, causing deterioration in image quality. Furthermore, because it has a stepped part, not only defects due to cracks in the array substrate occur during manufacturing, but also the wiring on the array substrate may break at the stepped part, improving the product yield rate and reliability There was a problem in doing.

  In addition, light having a backlight as a light source is transmitted as leakage light from the slit 40, and the image quality is deteriorated. A black matrix 12 is provided on the counter substrate 30 in order to shield this leakage light. However, an error may occur when the TFT array substrate 20 and the counter substrate 30 are overlapped, and the black matrix 12 is formed large with a slight margin in consideration of this error. However, when the black matrix 12 is enlarged to enhance the light shielding effect, there is a problem that the aperture ratio decreases.

  The present invention was made to solve the above problems, and in an IPS liquid crystal display device using an electric field in a direction parallel to a glass substrate, the shielding effect against a leakage electric field from a signal line is enhanced. A first object is to provide a high-quality liquid crystal display device having a wide opening (that is, having a high aperture ratio) by reducing the light shielding area. A second object of the present invention is to provide a high-quality liquid crystal display device that improves the yield rate by suppressing the occurrence of defects such as cracks in the array substrate and disconnection of wiring, thereby reducing the production cost. It is.

  The IPS type liquid crystal display device according to the present invention is provided in a scanning line for transmitting a scanning signal, a signal line for transmitting a video signal, a lattice pixel in which the scanning line and the signal line intersect, and the pixel. A thin film transistor that is connected to the scanning line and the signal line and performs switching of a video signal based on the scanning signal, a driving electrode connected to the thin film transistor, a counter electrode disposed opposite to the driving electrode, and the counter electrode TFT array substrate having a common wiring for mutually connecting the counter electrode of the other pixel and the other pixel, a counter substrate provided to face the TFT array substrate, and between the TFT array substrate and the counter substrate And the driving electrode and the counter electrode are driven by generating an electric field parallel to the substrate surface, and the TFT array substrate includes the driving electrode and The layer formed countercurrent electrode of the signal line and is formed in a layer closer to a different liquid crystal.

  The IPS liquid crystal display device according to the present invention includes a drive electrode that is connected to the thin film transistor and generates an electric field parallel to the surface of the TFT array substrate to drive the liquid crystal layer, and a counter electrode connected to the common wiring. Further, at least the counter electrode includes a TFT array substrate formed in a layer closer to the liquid crystal different from the layer in which the signal line is formed.

  The IPS liquid crystal display device according to the present invention includes a TFT array substrate having a counter electrode formed so as to cover part or all of the signal lines.

  The IPS liquid crystal display device according to the present invention further includes a TFT array substrate having at least a counter electrode provided in a layer different from the scan line and having the counter electrode formed so as to cover a part or all of the scan line. Is.

  The IPS-type liquid crystal display device according to the present invention includes a TFT array substrate in which common lines and scanning lines are provided in the same layer, and signal lines are provided in a layer closer to the counter substrate than the common lines and scanning lines. It is a thing.

  The IPS liquid crystal display device according to the present invention has a TFT array substrate in which the surface of the protective film is formed in a substantially flat shape.

  In addition, the IPS liquid crystal display device according to the present invention includes light shielding means formed so as to overlap the signal line and the counter electrode.

  The IPS liquid crystal display device according to the present invention includes a thin film transistor that switches a video signal based on a scanning signal, and a charge that is connected to the thin film transistor and is written when the thin film transistor is turned on. A TFT array substrate is provided, in which a drive electrode that stores electricity while is off and a storage capacity increasing electrode that reinforces the power stored in the drive electrode are formed so as to overlap each other in different layers.

  According to the in-plane switching type liquid crystal display device according to the present invention, since the drive electrode and the counter electrode are formed in a layer close to the liquid crystal different from the signal line, the drive electrode and the counter electrode are formed in a layer close to the liquid crystal. The liquid crystal can be driven efficiently. Accordingly, it is possible to widen the distance between the drive electrode and the counter electrode, and the aperture ratio is improved.

  Further, according to the in-plane switching type liquid crystal display device of the present invention, at least the counter electrode is formed in a layer close to the liquid crystal different from the layer in which the signal line is formed, among the drive electrode and the counter electrode. The influence of the electric field generated by the potential difference between the line and the counter electrode can also be suppressed.

  According to the in-plane switching type liquid crystal display device of the present invention, since the counter electrode is formed so as to cover part or all of the signal line, the electric field generated by the potential difference between the signal line and the counter electrode is It is possible to suppress the occurrence of display problems that affect the electric field generated between the drive electrode and the counter electrode and deteriorate the image quality. Therefore, liquid crystal display with high image quality is possible, and leakage light between the signal line using the backlight as the light source and the counter electrode can be surely shielded, so that the black matrix can be eliminated and the aperture ratio is improved. The

  According to the in-plane switching type liquid crystal display device of the present invention, at least the counter electrode is provided in a layer different from the scanning line and is formed so as to cover a part or all of the scanning line. It can be used to connect to the counter electrode of another pixel, and the width of the counter electrode can be increased without reducing the area of the opening. Therefore, the resistance of the counter electrode can be lowered and the load on the wiring can be reduced. In addition, since the potential is supplied from the counter electrode on the scanning line even if the common wiring is disconnected, the occurrence of defects on the display can be suppressed and the reliability can be improved.

  Further, according to the in-plane switching type liquid crystal display device according to the present invention, the common wiring and the scanning line are provided in the same layer, and the signal line is provided in a layer closer to the counter substrate than the common wiring and the scanning line. Defects that occur in the stepped portion can be suppressed.

  Further, according to the in-plane switching type liquid crystal display device according to the present invention, since the surface in contact with the TFT array substrate and the liquid crystal is provided with the protective film formed in a substantially flat shape, the surface of the array substrate over the entire display screen is provided. The gap between the opposing substrate and the liquid crystal display device can be configured with high accuracy and uniformity, and the rubbing treatment required for the alignment of the liquid crystal can be uniformly applied to reduce the alignment disturbance. Can be realized. In addition, the defect occurrence rate due to cracks or the like in the step portion of the protective film is reduced, and the yield is improved.

  According to the in-plane switching type liquid crystal display device of the present invention, since the TFT array substrate having the light shielding means formed so as to overlap the signal line and the counter electrode is provided, the light leaking through the slit is shielded. This makes it possible to eliminate the black matrix provided on the counter substrate. Also, when determining the size of the light shielding means, it is not necessary to consider the overlay error when overlaying the TFT array substrate and the counter substrate, so the size of the light shielding means should be minimized. And the aperture ratio was improved.

  In addition, according to the in-plane switching type liquid crystal display device of the present invention, since the TFT array substrate is formed so that the thin film transistor, the drive electrode, and the storage capacity increasing electrode are overlapped with different layers, The area of the electrode for forming the capacitor can be reduced, and the opening of the pixel can be widened accordingly, and a liquid crystal display device with high luminance can be realized.

Embodiment 1 FIG.
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the figure, the same reference numerals as in the prior art represent the same or equivalent ones as in the prior art. 1 is a cross-sectional view schematically showing the structure of one pixel of an IPS liquid crystal display device according to Embodiment 1 of the present invention, and FIG. 2 is a plan view thereof. 1 shows a cross-sectional view taken along the line AA shown in FIG. In the figure, 1 is a glass substrate, 2 is a scanning line, 3 is a signal line, 4 is a thin film transistor (TFT), 5 is a drive electrode, 6 is a counter electrode, 7 is a storage capacitor forming electrode, 8 is a common wiring, A gate insulating film, 10 is a protective film, 11 is a liquid crystal, 12 is a black matrix (BM), 14 is a contact hole, 15 is a source electrode of the transistor, and 16 is a drain electrode of the transistor. Reference numeral 20 denotes an array substrate (consisting of a glass substrate 1, a signal line 3, a drive electrode 5, a counter electrode 6, etc.), 30 denotes a counter substrate serving as a display screen disposed facing the array substrate 20, and 40 Is a slit which is a gap between the signal line 3 and the counter electrode 6, and 50 is an opening of the pixel. 3 shows an IPS liquid crystal display device in which a channel protective film type thin film transistor 21 which is a kind of thin film transistor 4 (TFT) is provided as the thin film transistor 4 (TFT) used in the IPS liquid crystal display device shown in FIG. FIG. 3A is a plan view, and FIG. 3B is a cross-sectional view.

  Next, the structure of the pixel of the IPS liquid crystal display device will be described with reference to FIGS. In the figure, reference numeral 1 denotes a glass substrate, and a scanning line 2 is formed on the glass substrate 1. A gate insulating film 9 is laminated so as to cover the scanning line 2, and the signal line 3 is provided on the gate insulating film 9. A protective film 10 is laminated on the signal line 3, and a drive electrode 5 and a counter electrode 6 are provided on the protective film 10. The TFT array substrate 20 has a structure as described above. The substrate 30 provided so as to face the TFT array substrate 20 is a counter substrate that holds the liquid crystal 11 between the TFT array substrate 20 and the substrate 30. The IPS liquid crystal display device according to the present invention generates an electric field along the surface of the TFT array substrate, and drives the liquid crystal 11 by controlling the direction of the electric field.

  FIG. 2 is a plan view of the IPS liquid crystal display device shown in FIG. In FIG. 2, 2 is a scanning line, 3 is a signal line, and a region surrounded by the scanning line 2 and the signal line 3 is one pixel. Reference numeral 4 denotes a thin film transistor (TFT) provided at the intersection of the scanning line 2 and the signal line 3. Of the three electrodes of the thin film transistor 4, the gate electrode is connected to the scanning line 2 and the source electrode 15 is connected to the signal line 3. ing. Of the three electrodes of the thin film transistor 4, the drain electrode 16 is connected to the drive electrode 5 through the contact hole 14 in the upper layer through the protective film 10 (not shown). The counter electrode 6 is provided so as to be engaged with the drive electrode 5, and the counter electrode 6 is formed in the same layer as the common wiring 8 and connected to each other. Although not shown, the common wiring 8 connects the counter electrode 6 of another adjacent pixel. The drive electrode 5, the counter electrode 6, and the common wiring 8 are simultaneously formed in a layer above the signal line 3.

  Reference numeral 7 denotes a storage capacitor for holding the potential of the drive electrode 5, which is formed by laminating the counter electrode 6 and the drain electrode 16 vertically. Reference numeral 40 denotes a slit between the signal line 3 and the counter electrode 6, and the black matrix 12 provided on the counter substrate 30 shown in FIG. 1 blocks light leaking through the slit 40 using a backlight as a light source. Is. Reference numeral 50 denotes an opening. If the area of the opening is increased, a high-quality liquid crystal display can be obtained. Note that the IPS liquid crystal display device holds the charge written to the drive electrode 5 connected to the drain electrode 16 of the thin film transistor 4 between the drive electrode 5 provided on the TFT array substrate 20 and the counter electrode 6. Since the liquid crystal 11 is driven by generating an electric field along the surface of the glass substrate 1, the counter substrate 30 is an electrodeless substrate without electrodes. Hereinafter, an example of the process flow of the TFT array substrate constituting the pixel of the IPS liquid crystal display device according to the first embodiment will be described.

4, 5, and 6 are diagrams showing a process flow of the TFT array substrate. 4 to 6 are diagrams showing the TFT array substrate, and the diagram on the right side is a diagram showing a terminal portion for mounting the scanning line 2 on the scanning line driving circuit. In FIG. 4, in step 1, the scanning line 2 is formed on a glass substrate 1 as a simple substance such as Cr, Al, Mo, Ta, Cu, Al—Cu, Al—Si—Cu, Ti, W, or an alloy thereof, or Transparent materials such as ITO (Indium Tin Oxide)
Alternatively, a structure in which these layers are stacked is formed with a thickness of about 50 nm to 800 nm. This scanning line 2 also functions as a gate electrode of the thin film transistor 4. As an etching method when forming the scanning line 2, taper etching having a trapezoidal cross section is shown in FIG. 4 as an example, but an etching method having a rectangular cross section may be used.

In step 2, the gate insulating film 9, amorphous silicon, and amorphous silicon doped with impurities such as phosphorus are continuously deposited so as to cover the scanning line 2, and then the amorphous silicon is patterned to form the thin film transistor 4 in a channel etch type. is there. The gate insulating film 9 is made of a transparent insulating film such as silicon nitride or silicon oxide, an oxide film of a gate electrode material (that is, a material of the scanning line 2), or a laminated film thereof, and the thickness is about 200 nm to 600 nm. Is appropriate. Further, microcrystalline silicon doped with impurities such as phosphorus may be used instead of amorphous silicon doped with impurities such as phosphorus.

In step 3, the signal line 3 is formed simultaneously with the source electrode 15 and the drain electrode 16 of the thin film transistor 4. The signal line 3 also functions as the source electrode 15. This signal line 3 is made of Cr, Al, Mo, Ta, Cu, Al—Cu, Al—Si—Cu, Ti, W alone, an alloy containing these as a main component, a transparent material such as ITO, or the like. It is formed with a laminated structure. In step 4, the protective film 10 is formed of a transparent insulating film such as silicon nitride or silicon oxide, and a part of the protective film on the drain electrode 16 of the thin film transistor 4 is used to electrically connect the drive electrode 5 and the drain electrode 16. Is removed to form a contact hole 14. At the same time, the gate insulating film 9 and the protective film 10 are removed from the terminal portion of the scanning line 2 and the protective film 10 is removed from the terminal portion of the signal line 3 so that the external circuit can be electrically connected to the scanning line 2 and the signal line 3. To do.

In step 5, the drive electrode 5 and the counter electrode 6 are made of Cr, Al, Mo, Ta, Cu, Al—Cu, Al—Si—Cu, Ti as electrodes for forming an electric field in the horizontal direction with respect to the substrate surface. , W alone, an alloy thereof, a transparent material such as ITO, a structure in which these are laminated, or a laminated structure including these. The drive electrode 5 is connected to the drain electrode 16 through the contact hole 14. The counter electrode 6 is connected to the common wiring 8. The counter electrode 6 overlaps with the drain electrode 16 through the protective film 10 to form a storage capacitor 7 for holding the potential of the drive electrode. Through the above five steps, the TFT array substrate 20 having the driving electrode 5 and the counter electrode 6 above the signal line 3 (that is, on the counter substrate 30 side) and applying a horizontal electric field to the substrate surface is performed five times. In this photolithography process, a channel etch type thin film transistor can be used.

In the process flow of the TFT array substrate described above, the terminals are formed using the same metal layer as the scanning lines 2, but the terminals may be formed using ITO. ITO may be formed in the same layer as the scanning line or signal line 3 or common wiring 8. Further, although the signal wiring is straight etched, it is desirable to perform taper etching. In addition, when the signal line is formed with a structure in which Al is laminated on Cr, if Al is patterned and then Cr is patterned, overetching will be applied to Cr, resulting in a wrinkle structure, which may cause breakage. In order to prevent this, if the Al is etched again after the Cr patterning and the Al is receded from the end face of the Cr, it is possible to prevent the formation of the eaves structure. For the etching of Al, taper etching may be used. This method uses signal lines such as Cr, Al, Mo, Ta, Cu, Al-Cu, Al-Si-Cu, Ti, W
The present invention can be applied to a case where a single layer, an alloy containing these as a main component, or a laminated structure of two or more different metals from a transparent material such as ITO.

  In FIG. 4, the drive electrode 5 and the counter electrode 6 are formed in the same layer. However, as shown in FIG. 5, the drive electrode 5 is formed simultaneously with the signal line 3, and then the protective film 10 is formed using silicon nitride or the like. The counter electrode 6 may be formed after the formation. In this case, the drive electrode 5 and the counter electrode 6 are formed in separate layers. Further, instead of the thin film transistor 4 (TFT) used in the TFT array substrate shown in FIG. 4, a channel protective film type transistor 21 which is a kind of the thin film transistor 4 may be used. FIG. 6 is a diagram showing a process flow of the TFT array substrate formed using the channel protective film type transistor 21.

  The TFT array substrate shown in FIG. 6 constitutes the pixel of the IPS type liquid crystal display device shown in FIG. 3, and has more layers than the TFT array substrate shown in FIG. This is because, after the scanning line 2 is formed, a gate insulating film 9, amorphous silicon, and a channel protective film are continuously deposited so as to cover the scanning line 2, and then a channel protective film 21 is formed, and the channel protective film 21 is used as a mask. Impurities such as P are ion-implanted into amorphous silicon to form an n layer to form a channel protective film transistor (step 2 in FIG. 6).

  The characteristic structure of the TFT array substrate 20 of the IPS-type liquid crystal display device according to the first embodiment is that the drive electrode 5 and the counter electrode 6 are above the signal line 3 on the array substrate 20 (that is, on the counter substrate 30 side). It is arranged in. With this arrangement, the formation of the contact hole 14 and the step of removing the protective film 10 from the terminal portion of the signal line 3 and the step of removing the insulating film 9 and the protective film 10 from the terminal portion of the scanning line 2 are performed at once. I can do it. Therefore, the number of masks can be reduced by one and the manufacturing cost can be reduced.

  Further, since the drive electrode 5 and the counter electrode 6 are formed in a layer on the counter substrate 30 side with the signal line 3 being different from the layer, the opening shown in FIG. 2 can be estimated as will be described later in Embodiment 5. It has been found that the influence of the electric field generated by the potential difference between the counter electrode 6 provided adjacent to the signal line 3 at the end of the part 50 and the signal line 3 can be reduced. Therefore, the counter electrode at the end of the opening 50 can be brought close to the signal line 3, and the area of the opening 50 can be increased.

  In FIG. 1, since the drive electrode 5 and the counter electrode 6 are in direct contact with the liquid crystal sandwiched between the TFT array substrate 20 and the counter substrate 30, the liquid crystal can be driven efficiently. The interval between the counter electrodes 6 can be widened. Therefore, the effect that the aperture ratio is further improved can be obtained.

Embodiment 2. FIG.
FIG. 7 schematically shows the structure of the pixel electrode of the liquid crystal display device according to Embodiment 2 of the present invention. FIG. 7A is a plan view thereof, and FIG. 7B is FIG. ) Is a cross-sectional view taken along the line AA, and FIG. 8 is a diagram showing a process flow of the array substrate. In the figure, 1 is a glass substrate, 2 is a scanning line, 3 is a signal line, 4 is a thin film transistor (TFT), 5 is a drive electrode, 6 is a counter electrode, 7 is a storage capacitor forming electrode, 8 is a common wiring, A gate insulating film, 10 is a protective film, 11 is a liquid crystal, 12 is a black matrix, 14 is a contact hole, 15 is a source electrode of the transistor, 16 is a drain electrode of the transistor, and 18 is a through hole. Reference numeral 20 denotes an array substrate (consisting of a glass substrate 1, a signal line 3, a drive electrode 5, a counter electrode 6, etc.), 30 denotes a counter substrate serving as a display screen disposed facing the array substrate 20, and 40 Is a slit which is a gap between the signal line 3 and the counter electrode 6, and 50 is an opening of the pixel.

  In the first embodiment, the common wiring 8 is formed in the same layer as the counter electrode 6. However, in the second embodiment, as shown in FIG. 8, the common wiring 8 is formed on the same layer as the scanning line 2, that is, on the glass substrate 1. A common wiring 8 is formed. The source electrode 15 is connected to the signal line 3, the signal line 3 is formed on the scanning line 2 and the common wiring 8 through the gate insulating film 9, and further the drive electrode 5 through the protective film 10. A counter electrode 6 is formed. The drive electrode 5 is connected to the drain electrode 16 through the contact hole 14, and the counter electrode 6 is connected to the common wiring 8 through the through hole 18. As for the thin film transistor (TFT) 4, a channel protective film type thin film transistor may be used.

  In the IPS liquid crystal display device according to the second embodiment, the drive electrode 5 and the counter electrode 6 are formed in a layer close to the liquid crystal different from the signal line 3 as in the first embodiment, so that the liquid crystal is driven more efficiently. Therefore, the aperture ratio can be improved by increasing the distance between the drive electrode 5 and the counter electrode 6. Further, since the common wiring 8 and the scanning line 2 are formed in the same layer, the common wiring 8 is formed on the flat glass substrate 1 together with the scanning line 2, and the common wiring 8 is disconnected at the step portion. Can be suppressed, and the occurrence of defect rate can be reduced. Therefore, the reliability of the product is also improved. In the first embodiment, the counter electrode 6 cannot be thinned because the resistance of the common wiring 8 is lowered. However, in the second embodiment, the counter electrode 6 can be thinned. By reducing the thickness of the counter electrode 6, variations in electrode spacing are reduced, and a liquid crystal display device with less luminance unevenness over the entire screen can be realized.

Embodiment 3 FIG.
FIG. 9 schematically shows the structure of one pixel of the liquid crystal display device according to Embodiment 3 of the present invention. FIG. 9A is a plan view thereof, and FIG. 9B is FIG. ) Is a cross-sectional view taken along the line AA ′, and FIG. 10 is a process flow of the array substrate. In the figure, 1 is a glass substrate, 2 is a scanning line, 3 is a signal line, 4 is a thin film transistor (TFT), 5 is a drive electrode, 6 is a counter electrode, 7 is a storage capacitor forming electrode, 8 is a common wiring, A gate insulating film, 10 is a protective film, 11 is a liquid crystal, 12 is a black matrix, 14 is a contact hole, 15 is a source electrode of the transistor, and 16 is a drain electrode of the transistor. Reference numeral 20 denotes an array substrate (consisting of a glass substrate 1, a signal line 3, a drive electrode 5, a counter electrode 6, etc.), 30 denotes a counter substrate serving as a display screen disposed facing the array substrate 20, and 40 Is a slit that is a gap between the signal line 3 and the counter electrode 6, and 50 is an opening of the pixel.

  When the TFT array substrate 20 was formed, the protective film 10 was formed of a transparent insulating film such as silicon nitride or silicon oxide, and the surface of the protective film 10 had a step. However, in Embodiment 3, the protective film 10 is formed using a material such as an acrylic-melamine system or an acrylic-epoxy system having a function of flattening the surface of the layer to be formed, so that FIG. 10), as shown in FIG. 10, the surface level difference of the protective film 10 is eliminated and the surface is flattened.

  In the IPS-type liquid crystal display device according to the third embodiment, the surface of the protective film 10 is flattened so that the distance (gap) between the surface of the array substrate and the counter substrate 30 is accurately and uniformly over the entire display screen. This makes it possible to manufacture a liquid crystal display device with less luminance unevenness over the entire screen. In addition, the defect occurrence rate due to cracks or the like in the step portion of the protective film 10 is reduced, and the yield is improved. In addition, a high-quality liquid crystal display device can be realized with uniform rubbing treatment necessary for liquid crystal alignment and less alignment disorder.

  Similarly to the first embodiment, since the drive electrode 5 and the counter electrode 6 are provided in a layer closer to the liquid crystal than the layer in which the signal line 3 is formed, the liquid crystal can be driven efficiently. Since the interval between the counter electrodes 6 can be widened, there is an effect that the aperture ratio is also improved.

Embodiment 4 FIG.
FIG. 11 schematically shows the structure of one pixel of the IPS liquid crystal display device according to the fourth exemplary embodiment of the present invention. FIG. 11 (a) is a plan view thereof, and FIG. 11 (b) is FIG. It is sectional drawing in AA 'of (a). In the figure, 1 is a glass substrate, 2 is a scanning line, 3 is a signal line, 4 is a thin film transistor (TFT), 5 is a drive electrode, 6 is a counter electrode, 7 is a storage capacitor forming electrode, 8 is a common wiring, A gate insulating film, 10 is a protective film, 11 is a liquid crystal, 14 is a contact hole, 15 is a source electrode of the thin film transistor (TFT) 4, and 16 is a drain electrode of the thin film transistor (TFT). Reference numeral 20 denotes an array substrate (consisting of a glass substrate 1, a signal line 3, a drive electrode 5, a counter electrode 6 and the like), 30 denotes a counter substrate serving as a display screen disposed facing the array substrate 20, 60 Is a light-shielding film provided on the glass substrate 1.

  In the pixel structure of the liquid crystal display device according to the first to third embodiments, the fourth embodiment blocks light leaked from the slit 40 (see FIG. 18A) between the signal line 3 and the counter electrode 6. The light shielding film 60 to be formed is formed on the glass substrate 1. The structure of the liquid crystal display device according to the fourth embodiment will be described below with reference to FIGS. 11 (a) and 11 (b).

  In FIG. 11B, a light shielding film 60 is formed on the glass substrate 1. Although not shown in FIG. 11B, the scanning line 2 is also formed in the same layer as the light shielding film 60. The scanning line 2 also functions as a gate electrode of a thin film transistor (TFT) 4. A gate insulating film 9 is laminated on the scanning line 2 and the light shielding film 60. The signal line 3 is formed on the gate insulating film 9 at a position overlapping the light shielding film 60. A thin film transistor (TFT) 4 is also formed on the gate insulating film 9. The thin film transistor (TFT) 4 may be either a channel etch type TFT or a channel protective film type TFT. The source electrode 15 and the drain electrode 16 of the thin film transistor (TFT) 4 are also formed in the same layer as the signal line 3, and the protective film 10 is further laminated. Subsequently, a contact hole 14 is formed in the protective film 10, and the drive electrode 5 provided on the protective film 10 and the drain electrode of the thin film transistor (TFT) 4 provided on the gate insulating film 9 are connected via the contact hole 14. Connect.

  Similar to the drive electrode 5, the counter electrode 6 is also formed on the protective film 10. The counter electrode 6 is provided so as to overlap with the light shielding film 60 through the drain electrode 16 and the protective film 10 to form a storage capacitor 7 that holds the potential of the drive electrode 5. The counter electrode 6 is connected to a common wiring 8 provided on the same layer. Broken lines are shown at both ends of the pixel in FIG. This broken line indicates the position of the light shielding film 60 provided on the glass substrate 1 shown in FIG. 11B in FIG. As shown by the broken line, the opposing electrodes 6 at both ends are formed so as to overlap the light shielding film 60, thereby covering the slit 40 (see FIG. 18A) between the signal line 3 and the opposing electrode 6. I understand.

  In the fourth embodiment, the drive electrode 5 and the counter electrode 6 are formed on the protective film 10, but the drive electrode 5 and the signal line 3 are simultaneously formed on the gate insulating film 9, and a protective film is formed using silicon nitride or the like. After the formation, the counter electrode 6 may be formed. In this case, the drive electrode 5 and the counter electrode 6 are formed in separate layers. In the fourth embodiment, since the light shielding film 60 is formed on the glass substrate 1, light leakage from the slit 40 (not shown) between the signal line 3 and the counter electrode 6 does not occur. Thus, the width of the black matrix (BM) 12 can be narrowed, or the light shielding in the direction of the signal line 3 does not have to be performed by the BM 12. Therefore, the black matrix 12 can be omitted, and a large opening can be obtained.

  The liquid crystal display device is manufactured by stacking and combining a TFT array substrate and a counter substrate with a color filter, enclosing the liquid crystal 11 between these substrates, and connecting a drive circuit. However, an overlay error may occur in the process of superimposing the TFT array substrate and the counter substrate, and the black matrix reduces the overlay error so that light leaked from the slit 40 of the TFT array substrate 20 can be reliably blocked. In consideration of this, it was necessary to take a large light-shielding area (see FIG. 18A). Therefore, by providing the light-shielding film 60 on the TFT array substrate 20, it is possible to reliably shield light transmission portions such as slits, and there is no need to consider the overlay error between the TFT array substrate and the counter substrate. Therefore, the black matrix 12 can be gathered to the minimum necessary size, and the opening can be enlarged.

  Further, in the IPS liquid crystal display device according to the fourth embodiment, similarly to the IPS liquid crystal display device according to the first embodiment, the drive electrode 5 and the counter electrode 6 are provided in a layer close to the liquid crystal. Can be driven and the interval between the electrodes can be widened, so that the aperture ratio can be improved.

Embodiment 5 FIG.
FIG. 12 schematically shows the structure of one pixel of the IPS liquid crystal display device according to the fifth embodiment. FIG. 12 (a) is a plan view thereof, and FIG. 12 (b) is a diagram of FIG. 12 (a). It is sectional drawing in AA '. In the figure, 1 is a glass substrate, 2 is a scanning line, 3 is a signal line, 4 is a thin film transistor (TFT), 5 is a drive electrode, 6 is a counter electrode, 7 is a storage capacitor forming electrode, 8 is a common wiring, A gate insulating film, 10 is a protective film, 11 is a liquid crystal, 12 is a black matrix, 14 is a contact hole, 15 is a source electrode of the transistor, and 16 is a drain electrode of the transistor. Reference numeral 20 denotes an array substrate (comprised of a glass substrate 1, a signal line 3, a drive electrode 5, a counter electrode 6 and the like), and 30 denotes a counter substrate serving as a display screen disposed facing the array substrate 20. .

  In the fifth embodiment, similarly to the first embodiment, the drive electrode 5 and the counter electrode 6 are formed in an upper layer than the signal line 3, and the counter electrode 6 is formed so as to cover the signal line 3. 3 is configured to be less affected by the leakage electric field from 3 and to prevent leakage light from the slit 40 between the signal line 3 and the counter electrode 6 (see FIG. 18A). is there. FIG. 13 shows a result of simulating a change in potential generated between the drive electrode 5 formed so as to cover the signal line 3 and the counter electrode 6 formed in the same layer as the drive electrode 5. FIG. FIG. 13 shows the calculated potential at the upper or lower portion of the window when a white window is displayed in a halftone with a relative transmittance of 50%.

  FIG. 21 showing the potential distribution in the TFT array substrate of the conventional IPS type liquid crystal display device having the drive electrode 5 and the counter electrode 6 below the signal line 3 is compared with FIG. Since the electric field generated by the potential difference with the counter electrode 6 is shielded by the counter electrode 6 disposed at the upper part so as to cover the signal line 3, the region near the signal line 3 in the opening 50 and the signal line 3 It can be seen that the potential distribution in the remote region is almost symmetrical.

  As described above, in the TFT array substrate 20 of the IPS liquid crystal display device according to the fifth embodiment, the driving electrode 5 and the counter electrode 6 are provided in an upper layer than the signal line 3 and the counter electrode 6 is covered so as to cover the signal line 3. Since the influence of the electric field generated between the signal line 3 and the counter electrode 6 on the electric field generated between the drive electrode 5 and the counter electrode 6 can be greatly reduced, the end of the opening 50 can be reduced. The counter electrode 6 can be made closer to the signal line 3 and the total area of the opening 50 can be increased.

  Further, since the counter electrode 6 is formed so as to cover the signal line 3, the leakage light can be reliably shielded and the black matrix 12 can be eliminated. Therefore, since the area of the opening 50 can be increased, a high-brightness liquid crystal display device can be provided, and the process of providing the black matrix 12 can be reduced, so that productivity is improved and cost is reduced. Liquid crystal display devices can now be manufactured. Further, as in the first embodiment, since the drive electrode 5 and the counter electrode 6 are formed in a layer close to the liquid crystal, the liquid crystal can be driven efficiently, the distance between the electrodes can be increased, and the aperture ratio is also improved. The

Embodiment 6 FIG.
FIG. 14 schematically shows the structure of one pixel of the IPS liquid crystal display device according to the sixth embodiment. FIG. 14 (a) is a plan view, and FIG. 14 (b) is FIG. 14 (a). It is sectional drawing in AA. The pixel configuration of the IPS liquid crystal display device according to the sixth embodiment shown in FIG. 14 is basically the same as the pixel configuration of the IPS liquid crystal display device according to the fifth embodiment shown in FIG. Therefore, explanation is omitted. Although the case where the counter electrode 6 having a structure that completely covers the signal line 3 is provided in the fifth embodiment, the counter electrode 6 of the pixel of the IPS liquid crystal display device according to the sixth embodiment shown in FIG. Alternatively, the counter electrode 6 having a structure covering a part of the signal line 3 may be used.

  According to the sixth embodiment, since the counter electrode 6 is formed so as to cover a part of the signal line 3, the electric field generated by the potential difference between the signal line 3 and the counter electrode 6 is generated by the drive electrode 5 and the counter electrode 6. Since the influence on the electric field between the signal line 3 and the counter electrode 6 can be reduced and the leakage light transmitted through the slit 40 can be blocked, the width of the black matrix 12 is reduced. Alternatively, the black matrix 12 can be eliminated, and a high-brightness liquid crystal display device with a wide opening can be realized. Further, by eliminating the black matrix 12, the process of providing the black matrix 12 can be reduced, so that the productivity is improved. It can also be seen that the area where the signal line 3 and the counter electrode 6 overlap is reduced, so that the occurrence of short-circuit defects between the signal line 3 and the counter electrode 6 is reduced. Furthermore, since the area where the signal line 3 and the counter electrode 6 overlap is reduced, the capacitance between the signal line 3 and the counter electrode 6 can be reduced, the wiring load is reduced, and driving is facilitated.

Embodiment 7 FIG.
FIG. 15 schematically shows the structure of one pixel of the IPS liquid crystal display device according to the seventh embodiment. FIG. 12 (a) is a plan view, and FIG. 12 (b) is FIG. 12 (a). It is sectional drawing in AA '. The configuration of the pixel of the IPS liquid crystal display device according to the seventh embodiment shown in FIG. 15 is the same as the configuration of the pixel of the IPS liquid crystal display device according to the fifth embodiment shown in FIG. Omitted. In the pixel structure of the liquid crystal display device according to the sixth embodiment, for example, as shown in FIG. 14, the seventh embodiment is formed by enlarging the counter electrode 6 over the scanning line 2, and using the counter electrode 6, The counter electrode 6 of another pixel adjacent to this pixel is connected.

  By using such a structure, the width of the counter electrode 6 is increased, the resistance of the counter electrode 6 is reduced, and the load is reduced, so that driving is facilitated. Further, even if the common wiring 8 is disconnected, the potential is supplied from the counter electrode 6 on the scanning line 2, so that there is no display defect. Therefore, the reliability of the product is improved. Note that the structure of the counter electrode 6 according to the seventh embodiment can be applied not only to the seventh embodiment but also to other embodiments, and it goes without saying that the same effect can be obtained.

Embodiment 8 FIG.
FIG. 16 schematically shows a cross-sectional structure of the storage capacitor portion in one pixel of the liquid crystal display device according to the eighth embodiment of the present invention. In the figure, 17 is an electrode for increasing the storage capacity formed on the glass substrate 1, and 16 is a drain electrode of a thin film transistor (TFT). As shown in the figure, the liquid crystal display device according to the eighth embodiment is held. The capacitor portion is formed by laminating the electrode 17 for increasing the storage capacitor on the layer separate from the drain electrode 16 of the thin film transistor (TFT) via the gate insulating film 9 (for example, the layer of the scanning line 2). Yes. As described above, by forming the electrode of the storage capacitor portion in a laminated structure, the area of the electrode for forming the storage capacitor can be reduced, and as a result, the opening 50 (not shown) of the pixel is formed. Can be wide.

Embodiment 9 FIG.
FIG. 17 is a diagram illustrating a process flow of the TFT array substrate according to the ninth embodiment. In FIG. 17, 1 is a glass substrate, 2 is a scanning line, 3 is a signal line, 4 is a thin film transistor (TFT), 5 is a drive electrode, 6 is a counter electrode, 8 is a common wiring, 9 is a gate insulating film, and 10 is a protective film. 14 is a contact hole, 15 is a source electrode of the transistor, 16 is a drain electrode of the transistor, and 19 is a second protective film. The array substrate 20 includes a glass substrate 1, a signal line 3, a drive electrode 5, a counter electrode 6, and the like.

  In the ninth embodiment, a second protective film 19 is formed on the TFT array substrate shown in FIGS. Therefore, the structure of one pixel of the liquid crystal display device according to the ninth embodiment is the same as that of the first embodiment. A method for manufacturing the liquid crystal display device according to the ninth embodiment will be described below. The process flow of the TFT array substrate in the ninth embodiment is the same as that in the first embodiment up to the step of forming the counter electrode 6. The ninth embodiment is characterized in that the second protective film 19 is formed on the upper layer of the counter electrode 6.

  By forming the second protective film 19 between the drive electrode 5 and the counter electrode 6, a short circuit between the drive electrode 5 and the counter electrode 6 due to foreign matter can be prevented, and the yield is improved. Further, since the level difference between the drive electrode 5 and the counter electrode 6 can be flattened, a high-quality liquid crystal display device can be realized in which the rubbing treatment necessary for the alignment of the liquid crystal is uniformly performed and the alignment is not disturbed.

It is sectional drawing which shows the structure of one pixel of the in-plane switching type liquid crystal display device concerning Embodiment 1 of this invention. It is a top view which shows the structure of one pixel of the in-plane switching type liquid crystal display device concerning Embodiment 1 of this invention. It is the top view and sectional drawing which show the structure of one pixel of the in-plane switching type liquid crystal display device concerning Embodiment 1 of this invention. It is a figure which shows the process flow of the TFT array substrate of the in-plane switching type liquid crystal display device concerning Embodiment 1 of this invention. It is a figure which shows the process flow of the TFT array substrate of the in-plane switching type liquid crystal display device concerning Embodiment 1 of this invention. It is a figure which shows the process flow of the TFT array substrate of the in-plane switching type liquid crystal display device concerning Embodiment 1 of this invention. It is the top view and sectional drawing which show the structure of one pixel of the in-plane switching type liquid crystal display device concerning Embodiment 2 of this invention. It is a figure which shows the process flow of the TFT array substrate of the in-plane switching type liquid crystal display device concerning Embodiment 2 of this invention. It is the top view and sectional drawing which show the structure of one pixel of the in-plane switching type liquid crystal display device concerning Embodiment 3 of this invention. It is sectional drawing which shows the process flow of the TFT array substrate of the in-plane switching type liquid crystal display device concerning Embodiment 3 of this invention. It is the top view and sectional drawing which show the structure of one pixel of the in-plane switching type liquid crystal display device concerning Embodiment 4 of this invention. It is the top view and sectional drawing which show the structure of one pixel of the in-plane switching type liquid crystal display device concerning Embodiment 5 of this invention. It is a figure which shows electric potential distribution when a drive electrode and a counter electrode exist in a layer above a signal line. It is the top view and sectional drawing which show the structure of one pixel of the in-plane switching type liquid crystal display device concerning Embodiment 6 of this invention. It is the top view and sectional drawing which show the structure of one pixel of the in-plane switching type liquid crystal display device concerning Embodiment 7 of this invention. It is sectional drawing which shows the structure of one pixel of the in-plane switching type liquid crystal display device concerning Embodiment 8 of this invention. It is a figure which shows the process flow of the TFT array substrate of the in-plane switching type liquid crystal display device concerning Embodiment 9 of this invention. It is the top view and sectional drawing which show the structure of one pixel of the conventional in-plane switching type liquid crystal display device. It is a figure which shows the equivalent circuit of 1 pixel of the conventional in-plane switching type liquid crystal display device. It is a block diagram which shows the structure of the conventional in-plane switching type liquid crystal display device. It is a figure which shows potential distribution when a drive electrode and a counter electrode are in a lower layer from a signal line. It is a figure which shows crosstalk.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Scan line 3 Signal line 4 Thin-film transistor (TFT) 5 Drive electrode 6 Counter electrode 7 Electrode for retention capacity formation 8 Common wiring 9 Gate insulating film 10 Protective film 11 Liquid crystal 12 Black matrix (BM)
13 Holding Capacitance 14 Contact Hole 15 Source Electrode 16 Drain Electrode
17 Electrode for increasing retention capacity 18 Through hole 19 Second protective film 20 Array substrate 21 Channel protective film 30 Counter substrate 40 Slit 50 Opening 60 Light shielding film

Claims (8)

A scanning line for transmitting a scanning signal, a signal line for transmitting a video signal, a grid-like pixel formed by intersecting the scanning line and the signal line, provided in the pixel and connected to the scanning line and the signal line; A thin film transistor that performs switching of a video signal based on a scanning signal, a drive electrode connected to the thin film transistor, a counter electrode disposed to face the drive electrode, and the counter electrode and a counter electrode of another pixel are mutually connected A TFT array substrate having a common wiring to be connected, a counter substrate provided so as to face the TFT array substrate, and sealed between the TFT array substrate and the counter substrate, and the drive electrode and the counter electrode are In an in-plane switching liquid crystal display device including a liquid crystal that is driven by generating an electric field parallel to the substrate surface, the TFT array substrate includes the driving electrode. Plane switching type liquid crystal display device characterized in that it is formed in a layer closer to the different liquid crystal and a counter electrode layer formed of the signal lines and. The TFT array substrate is provided with a drive electrode that generates an electric field parallel to the surface of the TFT array substrate to drive the liquid crystal and a counter electrode, and at least the counter electrode is a layer in which the signal line is formed. The in-plane switching type liquid crystal display device according to claim 1, wherein the in-plane switching type liquid crystal display device is formed in a layer close to a liquid crystal different from the above. 3. The in-plane switching type liquid crystal display device according to claim 2, wherein the TFT array substrate has a counter electrode formed so as to cover part or all of the signal lines. 4. The in-plane switching according to claim 3, wherein the TFT array substrate has at least a counter electrode provided in a layer different from the scanning line and has a counter electrode formed so as to cover a part or all of the scanning line. Type liquid crystal display device. 2. The in-plane TFT according to claim 1, wherein the TFT array substrate is provided with a common wiring and a scanning line in the same layer, and a signal line is provided in a layer closer to the counter substrate than the common wiring and the scanning line. Switching type liquid crystal display device. 2. The in-plane switching type liquid crystal display device according to claim 1, wherein the TFT array substrate is provided with a protective film having a substantially flat shape on a surface where the TFT array substrate and the liquid crystal are in contact with each other. 2. The in-plane switching type liquid crystal display device according to claim 1, wherein the TFT array substrate has light shielding means formed so as to overlap the signal line and the counter electrode. The TFT array substrate includes a thin film transistor that performs switching of a video signal based on a scanning signal, a drive electrode that stores a charge written when the thin film transistor is turned on while the thin film transistor is turned off, and a drive electrode 2. The in-plane switching type liquid crystal display device according to claim 1, wherein the storage capacitor increasing electrode for reinforcing the stored power is formed so as to overlap with different layers.

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