JP2002196311A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a peripheral frame part smaller in size by dispensing with insulating spacers which are to be arranged between a metal cover frame and a counter electrode in a liquid crystal display device. SOLUTION: In a liquid crystal display device having constitution in which a liquid crystal layer is held between a matrix array substrate 2 and a counter substrate 3, the counter electrode 7 formed on the whole surface of the counter substrate 3 and a metal cover frame 6 which is arranged at its outer periphery are made to be at the same potential. As a result, even when the counter electrode 7 and the metal cover frame 6 are short-circuited, since an excessive current is not made to flow through an external PCB(printed circuit board) which is not shown in the figure, insulating spacers 8 can be unnecessitated and the peripheral frame part is made smaller in size by this portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to an active matrix type liquid crystal display device using a matrix array substrate.

[0002]

2. Description of the Related Art In recent years, flat panel displays represented by liquid crystal display devices have been developed with a view to miniaturization, light weight, and low power consumption. In this type of liquid crystal display device, a pixel electrode is formed on a surface on a matrix array substrate side, and a counter electrode is formed on a surface on a counter substrate side, and a liquid crystal layer sandwiched between the substrates is formed by the pixel electrode and the counter electrode. Various displays are obtained by modulating with a potential difference between.

[0005] Of the two electrodes opposed to each other with the liquid crystal layer interposed therebetween, the potential is supplied to the opposite electrode by laying out the opposite electrode potential wiring on the matrix array substrate and electrically connecting to the opposite substrate via a conductive pad or the like. It is realized by conducting.

FIG. 5 is a partial cross-sectional view of the liquid crystal display device, particularly showing a cross-sectional configuration of an outer peripheral portion. Counter electrode 7
Are formed up to the outer peripheral portion of the opposing substrate 3, and conductive pads 28 drawn out from the not-shown opposing electrode potential wiring are formed in the peripheral portion of the matrix array substrate 2. A silver paste 31 is formed between the end of the opposing electrode 7 and the conductive pad 28, and the matrix array substrate 2 and the opposing substrate 3
Are bonded together via the seal member 32, so that a potential is supplied to the counter electrode 7 from the counter electrode potential wiring through the silver paste 31. Further, a metal cover frame 6 for protecting the substrate is provided outside the bonded matrix array substrate 2 and counter substrate 3 as shown in FIG. For example, 0
V (or ground potential) is supplied from the outside.
FIG. 7 is a waveform diagram of a signal potential applied to each of the above-described electrodes when driving the liquid crystal. For example, the counter potential of the counter electrode is 5
When a potential (video signal) of 1 to 9 V is applied to V and the pixel electrode, a voltage having an amplitude of 8 V is applied to the liquid crystal layer.

[0005]

As shown in FIG. 5,
Since a metal cover frame 6 having a potential different from that of the counter electrode 7 is provided outside the matrix array substrate 2 and the counter substrate 3, if the counter electrode 7 of the counter substrate 3 and the metal cover frame 6 are short-circuited, conductive An excessive current may flow from the pad 28 to the external PCB (printed circuit board) (not shown) through the counter electrode potential wiring, and the external PCB may be damaged. Therefore, in order to prevent such a short circuit,
As shown in FIG. 5, an insulating spacer 8 is arranged between the counter electrode 7 on the counter substrate 3 and the metal cover frame 6.

In recent years, with the miniaturization of liquid crystal display devices, it has been required to reduce the peripheral frame portion while maintaining the screen size. However, as shown in FIG. 5, since the insulating spacer 8 is disposed between the counter electrode 7 on the counter substrate 3 and the metal cover frame 6 to prevent a short circuit, the peripheral frame portion is made even smaller. It was difficult to do.

An object of the present invention is to provide a liquid crystal display device in which a peripheral frame portion can be reduced by eliminating the need for an insulating spacer.

[0008]

According to a first aspect of the present invention, there is provided a first electrode substrate on which a plurality of pixel electrodes are regularly arranged in a display area; A second electrode substrate on which an opposing electrode facing the electrode is formed on the entire surface, wherein the first electrode substrate and the second electrode substrate are formed at predetermined intervals by a sealing member formed on a peripheral portion of the display area. In a liquid crystal display device in which a liquid crystal layer is sandwiched between two substrates, a metal cover frame having the same potential as the potential of the counter electrode is provided outside the first electrode substrate and the second electrode substrate. It is characterized by being installed.

According to a second aspect of the present invention, in the first aspect, a 0 V potential or a ground potential is applied to the counter electrode and the metal cover frame, and a 0 V potential or a ground potential of the counter electrode is applied to the pixel electrode. And a signal of a positive polarity and a signal of a negative polarity are supplied.

[0010] According to the above configuration, by setting the opposite electrode and the metal cover frame to the same potential, even if the opposite electrode and the metal cover frame are short-circuited, an excessive current does not flow to the external PCB, and short-circuiting is prevented. It is possible to eliminate the need for an insulating spacer.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a liquid crystal display according to the present invention is applied to an active matrix type liquid crystal display will be described below.

The liquid crystal display device according to the present embodiment is roughly composed of two electrode substrates as shown in FIG. 3 and FIG. FIG. 3 is a schematic perspective view showing a configuration of a matrix array substrate, and FIG. 4 is a schematic perspective view showing a configuration of a counter substrate. The liquid crystal display device according to the present embodiment is an active matrix type liquid crystal display device, and includes a matrix array substrate 2 shown in FIG. 3, a counter substrate 3 shown in FIG. With no liquid crystal layer.

The matrix array substrate 2 has a plurality of signal lines 12 arranged in parallel on a transparent insulating substrate 4, and a plurality of scanning lines 14 arranged in parallel so as to intersect at right angles. Each signal line 12 and scanning line 14 are electrically insulated by an insulating film (not shown).

A signal line driving circuit 13 for applying a video signal to the signal line 12 is electrically connected to one end of the signal line 12, and a scanning signal is applied to the scanning line 14 at one end of the scanning line 14. Is electrically connected to the scanning line driving circuit 15.

At each intersection of the signal line 12 and the scanning line 14, T
An FT (thin film transistor) 16 and pixel electrodes 17 are arranged in a matrix to form the display area 11. T
The gate of the FT 16 is connected to the corresponding scanning line 14, the drain is connected to the corresponding signal line 12, and the source is connected to the pixel electrode 17. The pixel electrode 17 is formed of, for example, a transparent electrode such as an ITO film and a reflective electrode such as an Al alloy or an Ag alloy.

At the periphery of the display area 11 on the insulating substrate 4, a conductive pad 28 for applying a potential to the counter electrode 7 and a counter electrode potential wiring 27 are provided. The counter electrode potential wiring 27 is formed in the same step as the step in which the signal line 12 and the scanning line 14 are formed. Further, a predetermined counter potential is supplied to the counter electrode potential wiring 27 from the outside through a connection pad 33 from an external PCB (not shown).

On the other hand, a counter electrode 7 for applying a potential to the liquid crystal layer is formed on a transparent insulating substrate 5 on the counter substrate 3 as shown in FIG. Since the opposing electrode 7 is formed uniformly on the entire surface of the opposing substrate 3, the inside of this region is all at the same potential.

A seal member 32 is applied and formed on the periphery of the matrix array substrate 2, and an opposing substrate 3 is bonded so as to sandwich a liquid crystal layer (not shown). The counter potential applied to the counter electrode 7 is supplied from the external PCB to the connection pad 3
The voltage is applied to the counter electrode potential wiring 27 on the matrix array substrate 2 via 3 and is sent to the conductive pad 28. By applying the silver paste 31 on the conductive pad 28, the conductive pad 2 is
8 and the counter electrode 7 are electrically connected, and a counter potential is applied to the counter electrode 7.

FIG. 2 is a waveform diagram of the signal potential applied to each of the above-mentioned electrodes when driving the liquid crystal. Here, 0 V (or a ground potential) is applied as the opposing potential of the opposing electrode 7, and a voltage from −4 V to +4 V, for example, is applied to the pixel electrode 17. According to this, since a voltage having an amplitude of 8 V can be applied to the liquid crystal layer as a video signal as in the case of FIG. 7, equivalent liquid crystal display can be performed.

FIG. 1 is a partial sectional view of the liquid crystal display device according to the present embodiment, and particularly shows a sectional configuration of an outer peripheral portion. The configurations of the electrodes and the substrate in FIG. 1 are the same as those in FIG. 5, and therefore the description is omitted, and the same parts as those in FIG. Metal cover frame 6 of the present embodiment
Is supplied with the same 0 V potential (or ground potential) as the counter electrode 7 as shown in FIG. As described above, when the opposite electrode 7 and the metal cover frame 6 on the opposite substrate 3 are set to the same potential, an excessive current flows to the external PCB (not shown) even if the opposite electrode 7 and the metal cover frame 6 are short-circuited. Therefore, the insulating spacer 8 for preventing short circuit as shown in FIG. 5 becomes unnecessary. Accordingly, the size of the outer periphery of the substrate conventionally required for the insulating spacer 8 can be reduced by the dimension A,
The peripheral frame portion can be further reduced as compared with the conventional example shown in FIG.

In the above embodiment, the case where the present invention is applied to an active matrix type liquid crystal display device has been described. However, the present invention can be applied to a general flat display device in which a light modulation layer is sandwiched between substrates. it can.

[0022]

As described above, according to the present invention,
Since an insulating spacer for preventing a short circuit between the counter electrode and the metal cover frame can be eliminated, a peripheral frame portion of the liquid crystal display device can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a liquid crystal display device according to an embodiment.

FIG. 2 is a waveform diagram of a signal potential applied to each electrode when driving a liquid crystal according to the embodiment.

FIG. 3 is a schematic perspective view showing a configuration of a matrix array substrate.

FIG. 4 is a schematic perspective view showing a configuration of a counter substrate.

FIG. 5 is a partial cross-sectional view of a conventional liquid crystal display device.

FIG. 6 is an external perspective view of a liquid crystal display device.

FIG. 7 is a waveform diagram of a signal potential applied to each electrode when driving a liquid crystal in a conventional example.

[Explanation of symbols]

2: matrix array substrate, 3: counter substrate, 4, 5: insulating substrate, 7: counter electrode, 12: signal line, 13: signal line driving circuit, 14: scanning line, 15: scanning line driving circuit, 16:
TFT, 27: counter electrode potential wiring, 28: conductive pad,
31: silver paste, 32: sealing member, 33: connection pad

Claims (2)

[Claims] 1. A first electrode substrate in which a plurality of pixel electrodes are regularly arranged in a display area, and a second electrode substrate in which a counter electrode facing the plurality of pixel electrodes is formed on the entire surface. A liquid crystal display device comprising: a first electrode substrate and a second electrode substrate that are bonded at a predetermined interval by a seal member formed in a peripheral portion of the display area; and a liquid crystal layer is sandwiched between the two substrates. And a metal cover frame having the same potential as the potential of the counter electrode is provided outside the first electrode substrate and the second electrode substrate. 2. A 0 V potential or a ground potential is applied to the counter electrode and the metal cover frame, and a positive and negative signal with respect to the 0 V potential or the ground potential of the counter electrode is supplied to the pixel electrode. The liquid crystal display device according to claim 1, wherein: