JP2007212610A - Liquid crystal display device, liquid crystal display panel, and method for manufacturing liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which occurrence of a malfunction and breakage of a control circuit of the liquid crystal display device is suppressed in an electrostatic breakdown test. <P>SOLUTION: The liquid crystal display device is equipped with: a first substrate 10; pixel electrodes formed on the first substrate 10; a second substrate 20 placed opposite to the first substrate 10; a common electrode 22 formed on a surface of the second substrate 20 facing the first substrate 10; a liquid crystal 40 placed between the first substrate 10 and the second substrate 20; the control circuit 31 to control voltages respectively applied to the pixel electrodes and the common electrode 22; and a conductor pattern 21 for grounding formed on the surface of the second substrate 20 facing the first substrate 10 and connected to a ground arranged on the outside of the liquid crystal display device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, a liquid crystal display panel, and a method for manufacturing a liquid crystal display device. In particular, the present invention relates to a liquid crystal display device, a liquid crystal display panel, and a method for manufacturing the liquid crystal display device that can prevent malfunction and destruction of a control circuit of the liquid crystal display device during an electrostatic breakdown test.

  FIG. 6A is a plan view for explaining a configuration of a conventional liquid crystal display device, and FIG. 6B is a cross-sectional view taken along line AA ′ of the liquid crystal display panel 100 included in the liquid crystal display device. The liquid crystal display device includes a liquid crystal display panel 100 and an FPC (flexible printed wiring board) 102. The FPC 102 connects the liquid crystal display panel 100 to an external system (not shown).

  The liquid crystal display panel 100 has a structure in which a liquid crystal 140 is sealed between a substrate 110 and a counter substrate 120. The substrate 110 is provided with a pixel electrode (not shown), a transistor (not shown), a source wiring (not shown), a gate wiring (not shown), and a common wiring 111. A common electrode 122 is provided. The common electrode 122 is connected to the common wiring 111 through a conductive spacer 142 disposed between the substrate 110 and the counter substrate 120, and a reference potential is applied from the common wiring 111. Although not shown, an alignment film is provided between each of the substrate 110 and the counter substrate 120 and the liquid crystal.

  The common wiring 111 is connected to the driver IC 131 mounted on the substrate 110 via the wiring 111a. The driver IC 131 is connected to an external system ground by a wiring 132 provided in the FPC 102.

One of reliability tests for liquid crystal display devices is an electrostatic breakdown test. In the electrostatic breakdown test, static electricity of the order of 10 kV is applied to the surface of the counter substrate 120 exposed to the outside using a static electricity applying gun 150 (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-223827 (fourth paragraph)

  In the electrostatic breakdown test, when static electricity is applied to the surface of the counter substrate that is exposed to the outside, charges on the opposite side of the counter substrate are charged with reverse polarity. In some cases, it flows into the counter substrate via a control circuit (for example, a driver IC). In this case, the reference potential of the control circuit may fluctuate and the control circuit may malfunction. In the worst case, the control circuit may be destroyed.

  The present invention has been made in consideration of the above-described circumstances, and an object of the present invention is to provide a liquid crystal display device and a liquid crystal device capable of suppressing the malfunction and destruction of the control circuit of the liquid crystal display device during the electrostatic breakdown test. An object of the present invention is to provide a display panel and a method for manufacturing a liquid crystal display device.

In order to solve the above problems, a liquid crystal display device according to the present invention provides:
A first substrate;
A pixel electrode formed on the first substrate;
A second substrate disposed opposite the first substrate;
A common electrode formed on a surface of the second substrate facing the first substrate;
A liquid crystal positioned between the first substrate and the second substrate;
A control circuit for controlling a voltage applied to each of the pixel electrode and the common electrode;
A grounding conductor pattern formed on a surface of the second substrate facing the first substrate and connected to a ground provided outside the liquid crystal display device.

  According to this liquid crystal display device, since the grounding conductor pattern is provided on the second substrate, the second substrate can be applied even if static electricity is applied to the surface of the second substrate exposed to the outside. The charge of the opposite polarity charged on the surface on the opposite side directly flows into the grounding conductor pattern from the ground. Therefore, it is possible to suppress the inflowing charge from passing through the control circuit, thereby suppressing the malfunction of the reference potential of the control circuit and the destruction of the control circuit.

  When the transistor is formed on the first substrate and is controlled by the control circuit and functions as a switch of the pixel electrode, the grounding conductor pattern is partially located above the transistor. Is preferred. In this way, it is possible to increase the area of the grounding conductor pattern and efficiently flow charges of reverse polarity without reducing the aperture ratio of the liquid crystal display device.

  In the case where a plurality of the common electrodes are arranged in a matrix on the second substrate, the grounding conductor pattern is located in the same layer as the common electrodes, and between the plurality of common electrodes. The space may be provided in a stripe shape or a lattice shape. In this way, the common electrode and the grounding conductor pattern can be formed in the same process.

  The grounding conductor pattern may be formed in a layer different from the common electrode. In this case, the grounding conductor pattern may be formed of a transparent conductor, and a part thereof may be positioned above the pixel electrode.

  It is preferable to include a first ground wiring that connects the control circuit to the ground, and a second ground wiring that connects the grounding conductor pattern to the ground. In this case, it is preferable that the resistance of the first ground wiring is higher than that of the second ground wiring.

A liquid crystal display panel according to the present invention includes a first substrate,
A pixel electrode formed on the first substrate;
A second substrate disposed opposite the first substrate;
A common electrode formed on a surface of the second substrate facing the first substrate;
A liquid crystal positioned between the first substrate and the second substrate;
A grounding conductor pattern formed on a surface of the second substrate facing the first substrate and connected to a ground provided outside the liquid crystal display device.

The method of manufacturing a liquid crystal display device according to the present invention includes forming a pixel electrode, a transistor functioning as a switch of the pixel electrode, and a common wiring on a first substrate;
Forming a conductive film on the second substrate;
Forming a common electrode and a grounding conductor pattern on the second substrate by selectively removing the conductive film;
A step of placing the common electrode and the grounding conductor pattern on the second substrate opposite to the first substrate and disposing a liquid crystal between the two substrates.

Another method of manufacturing a liquid crystal display device according to the present invention includes forming a pixel electrode, a transistor functioning as a switch of the pixel electrode, and a common wiring on a first substrate;
Forming a grounding conductor pattern on the second substrate;
Forming an insulating film on the grounding conductor pattern;
Forming a common electrode on the insulating film;
A step of placing the common electrode and the grounding conductor pattern on the second substrate opposite to the first substrate and disposing a liquid crystal between the two substrates.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1A is a plan view for explaining the configuration of the liquid crystal display device according to the first embodiment of the present invention, and FIG. 1B is a cross-sectional view. The liquid crystal display device includes a liquid crystal display panel 1 and an FPC (flexible printed wiring board) 2 that connects the liquid crystal display panel 1 to a system (not shown).

  The liquid crystal display panel 1 has a structure in which the liquid crystal 40 is sealed between the substrate 10 and the counter substrate 20 using a sealing material 40a. A common wiring 11 is provided on the substrate 10, and a common electrode 22 and a grounding conductor pattern 21 are provided on the opposite substrate 20 on the surface on which the liquid crystal 40 is sealed. The common electrode 22 is connected to the common wiring 11 via a conductive spacer 42 disposed between the substrate 10 and the counter substrate 20, and a reference potential is applied from the common wiring 11. The grounding conductor pattern 21 is insulated from the common electrode 22, and is connected to the wiring 10a provided on the substrate 10 through the conductive pattern 40b provided on the sealing material 40a. The wiring 10a is directly connected to the ground of the system described above via the wiring 2a provided in the FPC 2. The wirings 10a and 2a are routed so that the distance from the system ground to the grounding conductor pattern 21 is the shortest. Note that an alignment film (not shown) is provided between the substrate 10 and the counter substrate 20 and the liquid crystal, and a polarizing plate (not shown) and a surface exposed to the outside of the substrate 10 are provided. A reflecting plate (not shown) is provided in this order, and a polarizing plate (not shown) is provided on the surface of the counter substrate 20 exposed to the outside.

  The common wiring 11 is connected to a driver IC 31 that is COG-mounted on the substrate 10 via a wiring 11 a provided on the substrate 10. The driver IC 31 is connected to the system ground by a wiring 32 provided in the FPC 2. The wiring 32 preferably has a higher resistance than the wiring 2a. Such a configuration is realized, for example, by including the resistor 32a, but the resistor 32a may not be provided in some cases.

  When the electrostatic breakdown test is performed on the liquid crystal display panel 1, 10 kV level static electricity is applied to the surface of the counter substrate 20 exposed to the outside using the static electricity applying gun 50. At this time, the opposite surface of the counter substrate 20 is charged with a charge having a reverse polarity to the applied static electricity, and this reverse polarity charge is transferred from the system ground to the grounding conductor pattern via the wirings 2a and 10a. 21. Accordingly, the inflowing charge is prevented from passing through the driver IC 31, the malfunction of the reference potential of the driver IC 31 is fluctuated, and the driver IC 31 is prevented from being destroyed. This effect becomes significant when the resistance of the wiring 32 is made higher than the resistance of the wiring 2a.

  FIG. 2A is a diagram for explaining a configuration of a circuit provided on the substrate 10. A common wiring 11, a source wiring 12 and a gate wiring 13 are provided on the substrate 10. The common wiring 11 and the gate wiring 13 are provided in parallel to each other, and the source wiring 12 is provided in a direction orthogonal to the common wiring 11.

  A region surrounded by the common wiring 11, the source wiring 12, and the gate wiring 13 is a pixel, but a plurality of pixels are arranged in a matrix. Each pixel is provided with a pixel electrode 15 and a transistor 14. The transistor 14 is a switching element that connects the pixel electrode 15 and the source line 12, and the gate electrode is connected to the gate line 13.

  FIG. 2B is a diagram for explaining the configuration of a circuit provided on the counter substrate 20. The common electrode 22 of the counter substrate 20 is disposed at a position facing the pixel electrode 15. The grounding conductor pattern 21 has an electrode portion 21a located above the transistor 14 and a wiring portion 21b that connects the electrode portion 21a to the wiring 2a. The wiring portion 21 b is routed between the spaces between the common electrodes 22, that is, above the source wiring 12 or above the gate wiring 13 and the common wiring 11. By providing the electrode portion 21a above the transistor 14, charges can be efficiently moved without reducing the aperture ratio of the pixel.

  Each drawing in FIG. 3 shows a pattern example of the grounding conductor pattern 21. In these drawings, only the wiring portion 21b of the grounding conductor pattern 21 is shown, and the illustration of the electrode portion 21a is omitted.

In the example shown in FIG. 3A, the wiring portion 21 b is a strip-like wiring 211 that extends in the vertical direction in the drawing, and is a square-shaped wiring 211 that is wired along the edge of the counter substrate 20. They are connected to each other.
In the example shown in FIG. 3B, the wiring portion 21b is formed by connecting a plurality of wirings 213 extending in the horizontal direction in the figure with a square-shaped wiring 211.
In the example shown in FIG. 3C, the wiring portion 21b is a wiring in which wirings 214 are provided inside a square-shaped wiring 211 in a grid pattern.

  In each of the patterns shown in FIGS. 3A and 3B, the wiring 211 is connected to the wiring 10a shown in FIG. 1 at each of the four corners 21c, thereby reducing the impedance. Note that the connection point between the wiring 212 and the wiring 10a is not limited to the corner portion 21c, and can be set at any other location.

  Next, a manufacturing method of the liquid crystal display device according to the present embodiment will be described. First, the common wiring 11, the source wiring 12, the gate wiring 13, the transistor 14, and the ground wiring 10 a are formed on the substrate 10. The ground wiring 10 a is formed in the same process as any of the common wiring 11, the source wiring 12, and the gate wiring 13.

  Further, a transparent conductive film (for example, an ITO film) is formed on one surface of the counter substrate 20. Next, a photoresist film is applied on the transparent conductive film, and the photoresist film is exposed and developed. Thereby, a resist pattern is formed on the transparent conductive film. Next, the transparent conductive film is etched using this resist pattern as a mask. As a result, the transparent conductive film is selectively removed, and the grounding conductor pattern 21 and the common electrode 22 are formed.

  Next, the surface of the counter substrate 20 on which the grounding conductor pattern 21 and the common electrode 22 are formed is opposed to the substrate 10, and the liquid crystal is sealed between the substrate 10 and the counter substrate 20 using the sealing material 40 a. Since the conductive material 40b is provided in advance in the sealing material 40a, the wiring 10a and the grounding conductor pattern 21 are connected by this process.

Further, a conductive spacer 42 is disposed between the substrate 10 and the counter substrate 20 to connect the common electrode 22 to the common wiring 11.
Thereafter, the driver IC 31 is mounted on the substrate 10 and the FPC 2 is further attached.

  As described above, according to the first embodiment of the present invention, since the grounding conductor pattern 21 is provided on the counter substrate 20, even if static electricity of 10 kV level is applied to the surface of the counter substrate 20 exposed to the outside, The reverse polarity charge on the opposite surface of the counter substrate 20 flows directly from the system ground via the grounding conductor pattern 21 and the wiring 2a. Therefore, it is possible to suppress the inflowing charge from passing through the driver IC 31, thereby suppressing the malfunction of the reference potential of the driver IC 31 and the destruction of the driver IC 31.

  Further, since the grounding conductor pattern 21 is formed in the same process as the common electrode 22, the number of manufacturing processes does not increase. Therefore, even if the grounding conductor pattern 21 is provided, the manufacturing cost does not increase. Further, since the grounding conductor pattern 21 is formed on the surface of the counter substrate 20 that is not exposed to the outside, it is not damaged when the liquid crystal display device is handled.

  Further, since the grounding conductor pattern 21 is configured to sandwich the common electrode, the grounding conductor pattern 21 also functions as a shield that protects the common electrode 22 from electromagnetic waves and the like.

  FIG. 4 is a cross-sectional view for explaining the configuration of the liquid crystal display device according to the second embodiment of the present invention, and corresponds to FIG. 1B in the first embodiment. This embodiment has the same configuration as that of the first embodiment except that the grounding conductor pattern 21 and the common electrode 22 are formed as separate layers. Specifically, a grounding conductor pattern 21, an insulating film 23, and a common electrode 22 are laminated on the counter substrate 20 in this order. Hereinafter, the same components as those of the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

Each drawing of FIG. 5 is a diagram showing a pattern shape of the grounding conductor pattern 21 in the present embodiment. In the example shown in FIG. 5A, the grounding conductor pattern 21 is formed of a transparent conductor (for example, ITO), and is formed on the entire surface of the counter substrate 20. For this reason, charges of opposite polarity are easily charged on the opposite surface of the counter substrate 20.
In the example shown in FIG. 5B, the grounding conductor pattern 21 is the same pattern as in the first embodiment, and does not overlap the pixel electrode. For this reason, it is not necessary to form the grounding conductor pattern 21 with a transparent conductor.

  The manufacturing method of the liquid crystal display device according to the present embodiment is the same as the manufacturing method according to the first embodiment except for the method of forming the grounding conductor pattern 21 and the common electrode 22. Hereinafter, the description is omitted except for the method of forming the grounding conductor pattern 21 and the common electrode 22.

  The grounding conductor pattern 21 and the common electrode 22 are formed as follows. First, a conductive film is formed on the counter substrate 20. When the grounding conductor pattern 21 is the pattern shown in FIG. 5A, this conductive film becomes the grounding conductor pattern 21. When the grounding conductor pattern 21 is shown in FIG. 5B, a photoresist film is formed on the conductive film, and the photoresist film is exposed and developed. Thereby, a resist pattern is formed on the conductive film. Next, the conductive film is etched using this resist pattern as a mask. As a result, the conductive film is selectively removed to form the grounding conductor pattern 21. Thereafter, the resist pattern is removed.

  Next, an insulating film (for example, a silicon oxide film) is formed on the entire surface including the grounding conductor pattern 21. Next, a transparent conductive film (for example, an ITO film) is formed on the insulating film. Next, a photoresist film is applied on the transparent conductive film, and the photoresist film is exposed and developed. Thereby, a resist pattern is formed on the transparent conductive film. Next, the transparent conductive film is etched using this resist pattern as a mask. Thereby, the transparent conductive film is selectively removed, and the common electrode 22 is formed.

  As described above, also in the second embodiment, the same effect as that in the first embodiment can be obtained.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

(A) is a top view for demonstrating the structure of the liquid crystal display device which concerns on the 1st Embodiment of this invention, (B) is sectional drawing. (A) is a figure for demonstrating the structure of the circuit provided in the board | substrate 10, (B) is a figure for demonstrating the structure of the circuit provided in the opposing board | substrate 20. FIG. Each figure is a diagram showing a pattern shape of a grounding conductor pattern 21 in the first embodiment. Sectional drawing for demonstrating the structure of the liquid crystal display device which concerns on 2nd Embodiment. Each figure is a view showing a pattern shape of a grounding conductor pattern 21 in the second embodiment. (A) is a top view for demonstrating the structure of the conventional liquid crystal display device, (B) is sectional drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,100 ... Liquid crystal display panel, 2,102 ... FPC, 2a, 10a, 11a, 32, 111a, 132, 211-214 ... Wiring 10, 110 ... Substrate, 11, 111 ... Common wiring, 12 ... Source wiring, DESCRIPTION OF SYMBOLS 13 ... Gate wiring, 14 ... Transistor, 15 ... Pixel electrode, 20, 120 ... Opposite substrate, 21 ... Grounding conductor pattern, 21a ... Electrode part, 21b ... Wiring part, 22, 122 ... Common electrode, 23 ... Insulating film, 31, 131 ... Driver IC, 32a ... Resistance, 40, 140 ... Liquid crystal, 40a ... Sealing material, 40b ... Conductive pattern, 42, 142 ... Conductive spacer, 50, 150 ... Electrostatic application gun

Claims (10)

A liquid crystal display device,
A first substrate;
A pixel electrode formed on the first substrate;
A second substrate disposed opposite the first substrate;
A common electrode formed on a surface of the second substrate facing the first substrate;
A liquid crystal positioned between the first substrate and the second substrate;
A control circuit for controlling a voltage applied to each of the pixel electrode and the common electrode;
A grounding conductor pattern formed on a surface of the second substrate facing the first substrate and connected to a ground provided outside the liquid crystal display device;
A liquid crystal display device comprising: A transistor formed on the first substrate and controlled by the control circuit and functioning as a switch for the pixel electrode;
The liquid crystal display device according to claim 1, wherein a part of the grounding conductor pattern is located above the transistor. A plurality of the common electrodes are arranged in a matrix on the second substrate,
The grounding conductor pattern is located in the same layer as the common electrode, and is provided in a stripe shape or a lattice shape in a space between the plurality of common electrodes. Liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the grounding conductor pattern is formed in a layer different from the common electrode.   The liquid crystal display device according to claim 4, wherein the grounding conductor pattern is formed of a transparent conductor, and a part thereof is positioned above the pixel electrode. A first ground wiring connecting the control circuit to the ground;
A second ground wiring connecting the grounding conductor pattern to the ground;
The liquid crystal display device according to claim 1, comprising:   The liquid crystal display device according to claim 6, wherein the first ground wiring has a higher resistance than the second ground wiring. A first substrate;
A pixel electrode formed on the first substrate;
A second substrate disposed opposite the first substrate;
A common electrode formed on a surface of the second substrate facing the first substrate;
A liquid crystal positioned between the first substrate and the second substrate;
A grounding conductor pattern formed on a surface of the second substrate facing the first substrate and connected to a ground provided outside the liquid crystal display device;
A liquid crystal display panel comprising: Forming a pixel electrode, a transistor functioning as a switch of the pixel electrode, and a common wiring on a first substrate;
Forming a conductive film on the second substrate;
Forming a common electrode and a grounding conductor pattern on the second substrate by selectively removing the conductive film;
A step of placing the common electrode and the grounding conductor pattern on the second substrate facing the first substrate and disposing a liquid crystal between the two substrates;
A method of manufacturing a liquid crystal display device comprising: Forming a pixel electrode, a transistor functioning as a switch of the pixel electrode, and a common wiring on a first substrate;
Forming a grounding conductor pattern on the second substrate;
Forming an insulating film on the grounding conductor pattern;
Forming a common electrode on the insulating film;
A step of placing the common electrode and the grounding conductor pattern on the second substrate facing the first substrate and disposing a liquid crystal between the two substrates;
A method of manufacturing a liquid crystal display device comprising:

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