JPH02111993A - liquid crystal display device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to the structure of a liquid crystal display device.

[Conventional technology]

A conventional liquid crystal display device is shown in FIG.

In a liquid crystal display device using COF (chip on flexible tape), one side of a flexible tape 11 mounted with a liquid crystal driver IC 10 that generates a liquid crystal drive signal according to a display pattern is pressed onto a liquid crystal panel 12 to establish continuity. .

Timing signals to the liquid crystal driver ICl0, display data signals, reference voltages for generating liquid crystal drive voltages, etc.
Since there are many things in common between the multiple driver ICs 10, the power supply board (hereinafter referred to as the bus board 9) placed across the series of driver ICs 10 has -
It is supplied in bulk. Therefore, there is always a bus board 9 corresponding to each of the three sides of the liquid crystal panel 12 in position.

By the way, for the purpose of ease of handling, improvement of characteristics, etc.
In addition to the circuits described above, a liquid crystal display device requires interface circuits such as a reference voltage generation circuit using a dividing resistor and an alternating current signal generation circuit, but in conventional liquid crystal display devices, these interface circuits are installed on the bus board 9. It was installed.

[Problem to be solved by the invention]

However, in conventional liquid crystal display devices, for the reasons stated above, the interface circuit has to correspond to the three sides of the liquid crystal panel 12, so the degree of freedom in position is low and tall mounting components are mounted. In order to do this, there was a problem in that the external size of the liquid crystal display device had to be increased.

In addition, the position of the interface circuit is determined regardless of the connection position between the connected device and the liquid crystal display device, so long wiring must be used between the connected device and the interface circuit, and the noise margin is sufficient. I couldn't get it.

Furthermore, with the advancement of liquid crystal technology, interface circuits are being improved day by day, as shown in many other patent applications, but in conventional liquid crystal display devices, the liquid crystal display device is completed as a module. Another problem is that it is extremely difficult to replace the interface circuit for improvement.

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and its purpose is to provide a sufficient noise margin without increasing the external size of a liquid crystal display device, and to easily replace the interface circuit. An object of the present invention is to provide such a liquid crystal display device.

[Means to solve the problem]

In order to solve the above problems, the liquid crystal display device of the present invention is a liquid crystal display device in which a liquid crystal drive circuit is connected to a liquid crystal panel using a COF, and an interface circuit between the liquid crystal drive circuit and a connected device is mounted. The present invention is characterized in that a substrate is disposed on the back side of the liquid crystal display device.

[Effect]

As mentioned above, since the interface circuit is placed on a separate board and placed on the back of the liquid crystal display device, the degree of freedom in the position of the interface circuit is improved, and as a result, the dimensions of the liquid crystal display device and the wiring position with the connected device can be changed. The degree of freedom has improved. Additionally, it has become easier to replace the interface circuit.

〔Example〕

The structure and features of the liquid crystal display device according to the present invention will be explained below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of an embodiment of a liquid crystal display device according to the present invention, and FIGS. 2(a) to 2(c) are views showing the liquid crystal display device of the embodiment.

Reference numeral 1 denotes a board on which an interface circuit is mounted (hereinafter referred to as interface board 1), which has an L-shape, and has a connector 7 mounted on its end. Insulating sheet 2 for insulating the interface board 1 from the external casing
is made of Bakelite (Xmi5i) VSS-11T20
0), and is fixed to the lamp house 3 together with the interface board 1 with self-tapping screws 4. The fixing position is a dead space that inevitably occurs when the lamp house 3 and the case 5 are mated, and does not affect the external shape of the liquid crystal display device.The lamp house 3 has a stepped part for fixing the interface board 1. A is provided,
Furthermore, by providing a hole for fixing the self-tapping screw 4 in this step, the self-tapping screw 4 is prevented from protruding into the inner surface of the lamp house 3, and the screwing direction of the self-tapping screw 4 is perpendicular to the back surface of the liquid crystal display device. This improves ease of assembly.

The area of interface board 1 is 25mm x 200mm
It is large enough to accommodate an interface circuit, and it is also possible to mount tall electronic components up to 10 mm in height by making effective use of dead space.

Furthermore, if the interface circuit becomes complicated, for example, the interface board 1 may be 290 m long in the long side direction.
It can be extended up to m, and if necessary, it is also possible to utilize the dead space on the opposite side.

Connection with connected devices is via a tape electric wire 6 connected to the interface board 1. By placing the interface board l on the back side of the liquid crystal display device 1 on the side of the connected device, as shown in FIG. Connectable devices can be connected. Therefore, the possibility of malfunction due to radiation noise and noise of the liquid crystal display device itself can be minimized.

The connection between the interface board 1 and the inside of the liquid crystal display device is from a connector 7 to a bus board 9 via a tape electric wire 8. Since the interface board 1 is fixed parallel to the bus board 9 by self-tapping screws 4,
In order to prevent twisting between the connector 7 and the tape wire 8 and to minimize the length of the tape wire 8, case
The side surface is cut out along the path of the tape electric wire 8, and as a result, the length of the tape electric wire 8 is suppressed to 40 mm. The number of cores of the tape electric wire 8 is 20, but since the interface board l is arranged parallel to the back surface of the liquid crystal display device and the outer shape of the board is L-shaped,
By extending the L-shaped portion B, the number of cores can be increased as necessary.

〔Effect of the invention〕

According to the present invention, the area of the interface board, the number of wire connections, and the height of the mounted components can be secured sufficiently without increasing the external size of the liquid crystal display device, and the wire connection with the connected device can be kept to the shortest distance. Therefore, a sufficient noise margin can be secured.

Furthermore, since the interface circuit is designed to be detachable as a single interface board, it is easy to replace the interface circuit for improvement or the like.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a liquid crystal display device showing one embodiment of the present invention. FIGS. 21(a) to 21(c) are diagrams showing a liquid crystal display device of the present invention. FIGS. 3(a) and 3(b) are diagrams showing the positional relationship between the liquid crystal display device of the present invention and connected devices. FIG. 4 is an exploded perspective view of a conventional liquid crystal display device. 1... Interface board 2... Insulating sheet 3... Lamp house 4... Self-tapping screw 5... Case 6... Tape wire 7... Connector 8... Tape wire 9... Bus board IO...Liquid crystal driver IC 11...Flexible tape 12...Liquid crystal panel 13...Liquid crystal display device 14 implementing the present invention...Connected devices and above Applicant Agent for Seiko Epson Corporation Patent Attorney Kisanbe Meiki and 1 other person Figure 1 Figure Figure

Claims (1)

[Claims] A liquid crystal display device in which a liquid crystal drive circuit is connected to a liquid crystal panel using a COF, characterized in that a substrate carrying an interface circuit between the liquid crystal drive circuit and connected devices is disposed on the back side of the liquid crystal display device. LCD display device.