JP2000250060A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reuse normal parts and to reduce cost by separating both parts without damaging after connecting a liquid crystal display element and an external driving circuit with a wiring substrate. SOLUTION: A flexible wiring board 13 to connect a liquid crystal display element 11 and an external driving circuit 12 is constructed with two parts consisting of a liquid crystal side wiring board 17, to which joints 17b, 18b are soldered, and a driving side wiring board 18. In the case the liquid crystal display element 11 and the external driving circuit 12 are separated, reuse of normal parts is feasible without damaging both the liquid crystal display element 11 and the external driving circuit 12 by heating and separating the joints 17b, 18b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device in which an external drive circuit is mounted on a liquid crystal display element using a wiring board.

[0002]

2. Description of the Related Art Recently, in an active matrix type liquid crystal display device, polysilicon (PS) is used as a driving element.
Those using a polysilicon TFT having a semiconductor layer composed of i) are often used. This polysilicon has an intermediate property between amorphous silicon (a-Si) and single-crystal silicon, has a high mobility of 10 to 200 cm2 / Vs, and is formed on a glass substrate on which a liquid crystal display element is formed. Can be configured at the same time.

Therefore, a liquid crystal display element having a pixel portion using a polysilicon TFT as a switching element and a signal drive circuit as a shift register for transferring data to the switching element in the pixel portion is formed on the same glass substrate. On the other hand, a control IC is mounted on a circuit board separate from the glass substrate.
And an external drive circuit equipped with a data input IC, a common voltage generation circuit, a gradation compensation circuit, a power supply circuit, and the like. From this external drive circuit, data signals can be input to the signal drive circuit via bus lines. Accordingly, a liquid crystal display device that simplifies an external drive circuit has been developed.

In order to mount an external drive circuit on a glass substrate of such a liquid crystal display element, conventionally, connection pads formed on the glass substrate and the external drive circuit and connection pads on the flexible wiring board side are conventionally used. , Anisotropic conductive film (hereinafter abbreviated as ACF) or solder. Then, after the liquid crystal display element and the external drive circuit are connected by a flexible wiring board, an image output failure caused by either the liquid crystal display element or the external drive circuit at the time of shipping inspection in the manufacturing process of the liquid crystal display device. In the event that a liquid crystal display element and an external drive circuit are separated by heating and peeling off the connected flexible wiring substrate, the production cost can be reduced by reusing any normal part. I was

[0005]

However, as described above, after the liquid crystal display element and the external drive circuit are connected by a flexible wiring board using ACF or solder, the liquid crystal display element or the external drive circuit is reused for reuse. If the flexible wiring board is to be peeled off from the drive circuit by heating, there is a risk that the glass substrate and the connection pads formed on the external drive circuit may be damaged at the time of peeling. Cannot be sufficiently removed, and the residue remains on the connection pad, causing a problem of poor connection at the time of reuse. Furthermore, not only the connection pads are damaged, but also the peeling operation by heating has an adverse effect on the mounted components on the external drive circuit, for example, causing the peeling of the connecting portion of the control IC or damaging the circuit board itself and connecting. There is also a danger that the pad may be peeled off, and even though the component is a normal component, it cannot be effectively reused, thereby preventing a reduction in manufacturing cost.

Therefore, the present invention makes it possible to easily and satisfactorily separate the liquid crystal display element and the external drive circuit without damaging the liquid crystal display element and the external drive circuit even after connecting the liquid crystal display element and the external circuit board by the flexible wiring board. It is another object of the present invention to provide a liquid crystal display device capable of reducing manufacturing costs by effectively reusing normal components.

[0007]

According to the present invention, as a means for solving the above-mentioned problems, a plurality of liquid crystal cells arranged in a matrix inside a liquid crystal cell in which a liquid crystal layer is sandwiched between insulating substrates arranged in parallel with each other. A liquid crystal pixel and a signal line to which the liquid crystal pixel is commonly connected for each column; a signal line driving circuit formed on one of the insulating substrates to supply a display signal to the signal line; and a control signal to the signal line driving circuit. An external drive circuit board on which an external drive circuit for supplying the external drive circuit is mounted; and a flexible wiring board for connecting the signal line drive circuit and the external drive circuit board. It is constituted by a plurality of wiring boards which are connected to each other in a peelable manner by members.

According to the present invention having such a structure, the flexible wiring board is peeled off, and the liquid crystal cell and the external drive circuit board can be separated well without damaging them. It is intended to be reusable and to reduce manufacturing costs.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in FIGS. Reference numeral 10 denotes an active matrix type liquid crystal display device, and a liquid crystal display element 11
And an external drive circuit 12 connected by a flexible wiring board 13 which is a connection means. The display region of the glass substrate 11a of the liquid crystal display element 11 has an n-type polysilicon TFT
An image display section 14 having a pixel electrode (not shown) having a driving element (not shown) as a driving element is formed, and a glass substrate 11 is formed.
In the frame area a, a p-type polysilicon TFT (not shown)
Is formed as a driving element.
The external drive circuit 12 includes components such as a control IC (not shown), an IC for inputting data signals to the signal drive circuit 16, a common voltage generation circuit, a gradation compensation circuit, and a power supply circuit, which are not shown, mounted on a circuit board 12a. ing.

The flexible wiring board 13 is made of a glass substrate 11a.
Alternatively, the liquid crystal side wiring board 17 which is made of an insulating resin such as polyimide or polyester having a higher thermal conductivity than the circuit board 12a and is connected to the liquid crystal display element 11;
2 connected to the drive-side wiring board 18. The liquid crystal-side wiring substrate 17 has a single-sided wiring structure, and its connection end 17 a with the liquid crystal display element 11 is connected to the glass substrate 1.
ACF is connected to connection pads (not shown) having a narrow pitch of 100 to 200 μm formed in 1a. The wiring pitch of the liquid crystal side wiring board 17 is
The connection end 17a is limited to 100 to 200 μm so as to match the connection pad on the glass substrate 11a, whereas the junction 17b is expanded to 300 to 400 μm because the limitation in the width direction is relatively loose. ing.

On the other hand, the drive-side wiring board 18 has a double-sided wiring structure, and a connection end 18a with the external drive circuit 12 is 0.9 m long.
soldering with a grid-shaped electrode with a narrow pitch of m
The relay part 18b arranges the wiring pads 21.

The liquid crystal side wiring board 17 of the flexible wiring board 13
The drive side wiring board 18 is joined by soldering the relay portions 17b and 18b. That is, a comb-shaped lead 20 having a pitch of 300 to 400 μm is formed so as to protrude from the relay portion 17 b of the liquid crystal side wiring board 17, while a wiring pad 21 having a pitch of 300 to 400 μm is provided on the relay portion 18 b of the driving side wiring board 18. The comb-like leads 20 and the wiring pads 21 are aligned with alignment marks (not shown) provided on both the liquid crystal side wiring board 17 and the driving side wiring board 18 and then joined by soldering.

Next, the liquid crystal display element 11 and the external drive circuit 1
2 is connected by the flexible wiring board 13. First, after the process of mounting a chip such as a control IC on the external drive circuit 12 is completed, the external drive circuit 12 and the drive-side wiring board 1 are mounted.
8 and ACF connection, and this is handled as an integral part.
As a result, the flexible wiring board 13 is first connected to an external drive circuit on which a number of components such as various ICs are mounted, and the operation after the connection can be checked beforehand, and defective components can be removed more quickly. Thereafter, the drive side wiring board 18 and the liquid crystal side wiring board 17 are connected by soldering, and the liquid crystal side wiring board 17 and the liquid crystal display element 11 are connected by ACF to form a liquid crystal display device.

Then, a defect is found at the time of the image output inspection, and the cause thereof is caused by the liquid crystal display element 11 or the external driving device 12.
If it is determined that the liquid crystal display element 11 is separated from the external driving device 12 by heating and separating the soldering of the comb-shaped lead 20 and the wiring pad 21 in order to reuse a normal component. I do. Next, the comb-shaped leads 20 or the wiring pads 21 of the wiring boards 17 and 18 on the component side to be reused
Of the liquid crystal side wiring board 17
Alternatively, the drive-side wiring board 18 is repaired.

With this configuration, even if an image output failure occurs during the shipping inspection of the liquid crystal display device. The liquid crystal display element 11 and the external drive circuit 12 can be easily separated by heating and separating the relay portions 17b and 18b of the flexible wiring board 13. In addition, since the relay portions 17b and 18b are provided apart from the connection pads of the liquid crystal display element 11 or the external drive circuit 12 and have good thermal conductivity of the flexible wiring board 13, the relay portions 17b and 18b are heated. At the time of separation, there is no risk of damaging both the liquid crystal display element 11 and the external drive circuit 12 due to heat, so that each can be reused and cost can be reduced. Further, after the separation, the flexible wiring board 13 can be easily repaired only by preliminary soldering the relay portions 17b and 18b on the normal side of the liquid crystal display element 11 or the external drive circuit 12.

The present invention is not limited to the above embodiment,
The wiring structure of the connection means can be changed as long as the purpose is not changed. If single-sided wiring is used, the cost of parts can be reduced as compared with the case of using double-sided wiring in which the entire length is expensive. Also, if the connection means is formed in another shape according to the arrangement of the external drive circuit corresponding to the shape and structure of the liquid crystal display device, the external drive circuit can be shared even for liquid crystal display devices having different external shapes, and the common development can be achieved. It is also possible to reduce costs by mass production or mass production.

Further, the shape and method of joining the connection means are also arbitrary. For example, in the above-described embodiment, the connection between the external drive circuit and the drive side wiring board is performed by laying out components on the external drive circuit and mounting the components. It is optional according to the method, and is formed by a pad row having a pitch of about 300 to 400 μm.
A CF connection may be used. Also, as in another modification shown in FIG. 3, the wiring pads 26, 2 are attached to the wiring ends of both the relay portions 23a, 24a of the liquid crystal side wiring substrate 23 and the driving side wiring substrate 24.
7 may be provided for ACF connection. When the ACF-connected relay portions 23a and 24a are separated by heating for component reuse, the ACF residue remaining on the wiring pads 26 and 27 of the component to be reused is removed and the liquid crystal side is removed. The wiring board 23 or the driving-side wiring board 24 will be repaired.

Further, the connection procedure between the connection means and the liquid crystal display element and the external drive circuit is optional, and the liquid crystal side wiring board, the driving side wiring board and the liquid crystal display element in the above-described embodiment can be used.
Although the order of connection with the external drive circuit is not limited, as in the embodiment, if the external drive circuit and the drive side wiring board are connected first and the operation check is performed first, a large number of components such as various ICs can be provided. By mounting, an external drive circuit that is likely to cause a defect can be removed before connection to the liquid crystal display element, and the chance of a repair process for reusing components can be reduced.

[0019]

As described above, according to the present invention, when a defect is caused by either the liquid crystal display element or the external drive circuit after mounting the external drive circuit on the liquid crystal display element, both are damaged. Since the two parts can be easily separated and repaired without giving the parts, the normal parts can be reused, and the cost can be reduced by effectively using the parts.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a schematic explanatory view showing a relay section of the flexible wiring board according to the embodiment of the present invention.

FIG. 3 is a schematic explanatory view showing a relay portion between a liquid crystal side wiring board and a driving side wiring board according to another modification of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display device 11 ... Liquid crystal display element 11a ... Glass substrate 12 ... External drive circuit 12a ... Circuit board 13 ... Flexible wiring board 14 ... Image display part 16 ... Signal drive circuit 17 ... Liquid crystal side wiring board 18 ... Drive side Wiring board 20: Comb-like lead 21: Wiring pad

Claims (3)

[Claims] 1. A liquid crystal cell comprising a liquid crystal layer sandwiched between insulating substrates arranged in parallel with each other, a plurality of liquid crystal pixels arranged in a matrix, and a signal line to which the liquid crystal pixels are commonly connected for each column. A signal line drive circuit formed on one of the insulating substrates and supplying a display signal to the signal line; an external drive circuit board mounted with an external drive circuit for supplying a control signal to the signal line drive circuit; A flexible wiring board for connecting the signal line driving circuit and the external driving circuit board, wherein the flexible wiring board is composed of a plurality of wiring boards connected to each other by a conductive member so as to be peelable from each other. A liquid crystal display device characterized by the above-mentioned. 2. The liquid crystal display device according to claim 1, wherein the conductive member is a solder layer. 3. The liquid crystal display device according to claim 1, wherein the conductive member is an anisotropic conductive film.