JPH04264525A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent the disconnection of the transparent electrode of a liquid crystal display section. CONSTITUTION:The tip part of an upper substrate 21 constituted of the polymer film of the liquid crystal display section 20 and the tip part of the TAB substrate 28 of a driving circuit section 26 are adhered via the transparent electrode 25 and an output signal line 29, in the liquid crystal display device by which the liquid crystal display 20 and the driving circuit section 26 are electrically connected, the vicinity of the part adhered to the upper substrate 21 of the TAB substrate 28 is bent in advance before the upper substrate 21 and the TAB substrate 28 are adhered and this device is constituted of an adhering section 28b by which the TAB substrate 28 is adhered to an LSI supporting section 28a supporting an LSI chip 27 and the upper substrate 21 and an inclined section 28c by which the LSI supporting section 28a and the sticking section 28b are linked.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a liquid crystal display device.
In particular, the present invention relates to a liquid crystal display device in which a polymer film is used as a substrate of a liquid crystal display part and a drive circuit part is constructed by tape automated bonding.

0002

2. Description of the Related Art Generally, liquid crystal display devices in which a polymer film is used as a substrate of a liquid crystal display portion are widely used in office automation equipment, measuring equipment, and the like. As such a conventional liquid crystal display device, tape automated bonding (Tape Automated Bonding) is used.
nding (hereinafter referred to as TAB), the drive circuit section is configured by, for example, as shown in FIGS. 12 to 14. Note that FIG. 12 is a cross-sectional view after the liquid crystal display section and the drive circuit section are bonded together, and FIGS. 13 and 14 are a cross-sectional view and a perspective view of the drive circuit section before bonding, respectively.

[0003] In FIGS. 12 to 14, reference numeral 1 denotes a drive circuit section composed of TAB;
It consists of a B board 2, an LSI chip 3, an output signal line 4, and a control signal line 5. An insulating coverlay film 6 is printed on the parts other than the connection terminals of the output signal line 4 and the control signal line 5 to prevent short circuits of the signal lines. On the other hand, 7 is a liquid crystal display section, and the liquid crystal display section 7 includes an upper substrate 8, a lower substrate 9, and a transparent electrode (ITO: Indium Tin Oxide).
10, polarizing plates 11 and 12, and a liquid crystal layer (not shown). A heat seal connector 13 is sandwiched between the ends of the TAB board 2 and the end of the upper board 8, on which the connection terminals of the output signal line 4 and the transparent electrode 10 are arranged, respectively.
The drive circuit section 1 and the liquid crystal display section 7 are electrically connected by pressing and thermocompression bonding the upper substrate 8.

0004

However, such conventional liquid crystal display devices have a problem in that the transparent electrodes are easily disconnected for the reasons described below. That is, the conventional one has a structure in which the TAB substrate 2 and the upper substrate 8 are pressed and bonded by thermocompression, and the thickness of the upper substrate 8 is 0.1 mm, and the thickness of the TAB substrate 2 is also about 0.1 mm.
Since they are approximately 1 mm, when thermocompression bonding is performed, the vicinity of the bonded portion of both substrates deforms as shown in FIG. 12. As a result,
The corner of the end of the lower substrate 9 may damage the transparent electrode 10, which is several hundred angstroms thick, on the upper substrate 8.
The transparent electrode 10 becomes easily disconnected. Note that there is a liquid crystal display device described in Japanese Utility Model Application Publication No. 14425/1983 that prevents distortion of the electrode lead-out portion of the upper substrate, but this device uses a PCB as the substrate for the drive circuit portion. It cannot be applied to those using TAB. Specifically, the method described in the publication forms a housing part for the reflective plate of the liquid crystal display panel on the top surface of the circuit board, connects the electrode extraction part of the top board of the liquid crystal display panel to the circuit board, and bends the top board. It is possible to mount the device without any stress, prevent disconnection of the transparent electrode during connection and subsequent stress, and improve yield and reliability. It is not possible.

[0005] Accordingly, an object of the present invention is to prevent disconnection of the transparent electrode by bending the third substrate of the drive circuit section in the vicinity of the bonded portion before bonding.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides first and second substrates made of polymer films sandwiching a liquid crystal layer, and a voltage applied to the liquid crystal layer that is wired on the first and second substrates. a liquid crystal display section having a transparent electrode to which voltage is applied, an LSI chip formed by tape automated bonding and outputting a driving voltage to the liquid crystal display section, a third substrate supporting the LSI chip, and wiring on the third substrate. L
a drive circuit section having an output signal line of an SI chip, the second substrate is arranged so as to be sandwiched between the first substrate and the third substrate, and an end portion of the first substrate and an end portion of the third substrate are provided. In the liquid crystal display device in which the third substrate is bonded to the first substrate through a transparent electrode and an output signal line, and the liquid crystal display section and the drive circuit section are electrically connected, the third substrate is bonded to the first substrate. 1. The third substrate is bent in advance before being bonded, and the third substrate is connected to the LSI support part that supports the LSI chip and the first
It is characterized by comprising an adhesive part that is adhered to the substrate, and an inclined part that connects the LSI support part and the adhesive part, and also covers and insulates the signal output line on the third substrate. A coverlay film may be provided, and the coverlay film may cover and insulate only the signal output line on the LSI support portion, and further, before the third substrate is bent, a predetermined portion corresponding to the slope portion may be A portion may be removed, and furthermore, the inclined portion of the third substrate and the vicinity of the inclined portion may be covered with an insulating adhesive.

[0007]

[Operation] In the present invention, the portion of the third substrate near the portion to be bonded to the first substrate is bent in advance before bonding the first and third substrates, so that the end portion of the first substrate is not bent. 1 board and 3rd board
The edges of the substrate are glued. Therefore, the transparent electrode on the first substrate is prevented from coming into contact with the second substrate, and the transparent electrode is prevented from being damaged.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on the drawings. 1 to 4 are diagrams showing a first embodiment of a liquid crystal display device according to the present invention. 1 to 4, 20 is a liquid crystal display section, and the liquid crystal display section 20 is composed of an upper substrate 21, a lower substrate 22, polarizing plates 23, 24, transparent electrodes 25, and a liquid crystal layer (not shown). The upper substrate 21 and the lower substrate 22 have a thickness of 0.
．． It consists of a 1mm polymer film with a liquid crystal layer sandwiched between them. The transparent electrode 25 is a transparent electrode that is wired on the upper substrate 21 and the lower substrate 22 and applies a voltage to the liquid crystal layer. The transparent electrode 25 is wired on the upper substrate 21 protruding from the lower substrate 22 at the connection terminal portion, and is connected to the polarizing plates 23 and 24.
The thickness is 0.3 mm.

On the other hand, reference numeral 26 denotes a drive circuit section formed by tape automated bonding.
It consists of The LSI chip 27 has a control signal line 30
A predetermined driving voltage is supplied to the transparent electrode 25 through the output signal line 29 in accordance with a control signal inputted through the output signal line 29. T.A.
The B board 28 supports the LSI chip 27, and the output signal line 29 and control signal line 30 are wired on the TAB board 28. The lower substrate 22 is arranged to be sandwiched between the upper substrate 21 and the TAB substrate 28, and the ends of the upper substrate 21 and the TAB substrate 28 are adhered via the transparent electrode 25 and the output signal line 29, and the liquid crystal The display section 20 and the drive circuit section 26 are electrically connected. Specifically, a heat seal connector 32 for thermocompression (anisolm manufactured by Hitachi Chemical) is sandwiched between the edge of the upper substrate 21 and the edge of the TAB substrate 28, and both substrates are connected to the heat seal connector 32.
It is bonded by thermocompression.

Here, the drive circuit section 26 is pressed by a press mold 36 shown in FIG.
The TAB substrate 28 is bent in advance before bonding the B substrate 28, and as shown in FIG.
I support part 28a, adhesive part 28b adhered to the upper substrate 21
, an inclined portion 28c connecting an LSI support portion 28a and an adhesive portion 28b. The height h in FIG. 2 when the TAB board 28 is bent is the thickness of the lower board 22 of 0.1 m.
m, the thickness of the polarizing plate 24 of 0.3 mm, and the thickness of the adhesive 33 made of double-sided tape or the like for attaching the drive circuit section 26 to the liquid crystal display section 20 of 0.1 mm, which is 0.5 m.
The thickness is set to 0.6 mm, which is slightly thicker than m. The control signal line 30 is connected to the bus line board 35 by solder 34, and the coverlay film 31 is formed by printing and covers and insulates the signal output line 29 and control signal line 30 on the TAB board 28. There is.

Next, a procedure for assembling the liquid crystal display device will be explained. First, heat seal connector 3 is attached to drive circuit section 30.
2 and press mold 3 shown in FIG.
6 to bend the ends of the TAB substrate 28 as shown in FIG. Next, the control signal line 30 of the drive circuit section 26 is connected to the bus line board 35 with solder 34,
After aligning the connection terminals of the output signal line 29 and the connection terminals of the transparent electrode 25, the upper substrate 21 and the TAB substrate 28 are bonded by thermocompression using the thermal head 37 as shown in FIG.
3, attach the drive circuit section 26 to the liquid crystal display section 20,
Assembly of the liquid crystal display device is completed.

As mentioned above, in this embodiment, the TAB substrate 2
Since the vicinity of the adhesive part 28b of No. 8 is bent in advance before bonding,
When the upper substrate 21 and the TAB substrate 28 are bonded by thermocompression, the upper substrate 2
1 is prevented from being bent, and the transparent electrode 25 is prevented from being damaged by the edge of the lower substrate 22. Therefore, disconnection of the transparent electrode 25 can be reliably prevented during and after bonding the upper substrate 21 and the TAB substrate 28, and the reliability of the device can be improved.

FIGS. 5 and 6 are diagrams showing a second embodiment of a liquid crystal display device according to the present invention. In addition, in FIGS. 5 and 6,
The same members as those of the first embodiment shown in FIGS. 1 to 4 are given the same reference numerals, and their explanations are omitted, and the same applies to the following embodiments. 5 and 6, the coverlay film 41 is the LSI support portion 28a of the TAB board 28.
Only the upper signal output line 29 and the control signal line 30 are covered and insulated. With this configuration, in addition to the effects of the first embodiment described above, the ends of the TAB substrate 28 can be easily bent, and the shape shown in FIG. 6 can be easily maintained.

FIGS. 7 to 10 are diagrams showing a third embodiment of a liquid crystal display device according to the present invention. In FIGS. 7 to 10,
Before the TAB substrate 28 is bent, a predetermined portion of the TAB substrate 28 corresponding to the inclined portion 28c is removed. In detail, as shown in FIGS. 9 and 10, for example, TAB
When removing the control signal line connection hole 28d of the board 28, only the hole 28e portion of the inclined portion 28c where the output signal line 29 is wired is removed. With this configuration, in addition to the effects of the first and second embodiments described above, it is possible to easily bend the TAB board 28 and maintain the shape of the bent TAB board 28 without increasing the number of man-hours. It can be made easier. Although not shown, an insulating film may be applied to the output signal lines 29 to prevent short circuits between the output signal lines 29 when the inclined portion 28c is removed.

FIG. 11 shows a fourth example of the liquid crystal display device according to the present invention.
It is a figure showing an example. In FIG. 11, TAB substrate 2
The inclined portion 28c of No. 8 and the vicinity of the inclined portion 28c are covered with an insulating adhesive 51 and fixed. With this configuration, in addition to the effects of the third embodiment described above, the insulation between the output signal lines 29 can be increased, and by reliably maintaining the bent shape of the TAB board 28, the upper board The shapes of the substrate 21 and the lower substrate 22 can be maintained. Furthermore, the drive circuit section 26 can be reliably held in the liquid crystal display section 20. Therefore, reliability can be further improved.

[0016]

According to the present invention, the vicinity of the portion of the third substrate to be bonded to the first substrate is bent in advance before bonding the first and third substrates, so that the end portion of the first substrate is bent. Therefore, the transparent electrode on the first substrate can be prevented from
It is possible to prevent the transparent electrode from coming into contact with the substrate, and it is possible to prevent the transparent electrode from being damaged. Therefore, disconnection of the transparent electrode can be prevented and reliability can be improved.

Furthermore, if a coverlay film is provided to cover and insulate the signal output line on the third substrate, and the cover film covers and insulates only the signal output line on the LSI support part, 3. The board can be easily bent,
The bent shape of the third substrate can be easily maintained. Furthermore, if the predetermined portion corresponding to the slope portion is removed before the third substrate is bent, the third substrate can be made even easier to bend and maintain its shape. Furthermore, when the inclined portion of the third substrate and the vicinity of the inclined portion are covered with an insulating adhesive, it is possible to improve the insulation of the output signal line and to firmly fix the third substrate. , and reliability can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of essential parts of a first embodiment of a liquid crystal display device according to the present invention.

FIG. 2 is a cross-sectional view of the drive circuit section in FIG. 1.

FIG. 3 is a schematic cross-sectional view of a press die for molding the drive circuit section in FIG. 1;

FIG. 4 is a diagram illustrating a method of thermocompression bonding between the upper substrate and the TAB substrate in FIG. 1;

FIG. 5 is a sectional view of a main part of a second embodiment of a liquid crystal display device according to the present invention.

FIG. 6 is a cross-sectional view of the drive circuit section in FIG. 5.

FIG. 7 is a sectional view of a main part of a third embodiment of a liquid crystal display device according to the present invention.

FIG. 8 is a cross-sectional view of the drive circuit section in FIG. 7.

9 is a sectional view of the drive circuit section in FIG. 7 before bending.

FIG. 10 is a perspective view of the drive circuit section in FIG. 7 before bending.

FIG. 11 is a sectional view of a main part of a fourth embodiment of a liquid crystal display device according to the present invention.

FIG. 12 is a sectional view of a main part of a conventional liquid crystal display device.

FIG. 13 is a cross-sectional view of the drive circuit section in FIG. 12.

FIG. 14 is a perspective view of the drive circuit section in FIG. 12.

[Explanation of symbols]

20 Liquid crystal display section 21 Upper board (first board) 22 Lower board (second board) 25 Transparent electrode 26 Drive circuit section 27 LSI chip 28 TAB board (third board) 28a LSI support part 28b Adhesive part 28c Slope part 29 Output signal line 31 Coverlay film 51 Insulating adhesive

Claims (4)

[Claims] 1. A liquid crystal display section comprising first and second substrates made of polymer films sandwiching a liquid crystal layer, and transparent electrodes that are wired on the first and second substrates and apply voltage to the liquid crystal layer;
The LSI chip and LS are formed by tape automated bonding and output driving voltage to the liquid crystal display section.
a drive circuit section having a third substrate supporting an I chip and an output signal line of the LSI chip wired on the third substrate;
The second substrate is arranged so as to be sandwiched between the first substrate and the third substrate, an end of the first substrate and an end of the third substrate are bonded via a transparent electrode and an output signal line, and a liquid crystal display is provided. In a liquid crystal display device in which a display portion and a drive circuit portion are electrically connected, a portion of the third substrate near a portion to be bonded to the first substrate is bent in advance before bonding the first and third substrates; A liquid crystal display device characterized in that three substrates are comprised of an LSI support part that supports an LSI chip, an adhesive part that is adhered to the first substrate, and an inclined part that connects the LSI support part and the adhesive part. 2. A coverlay film is provided to cover and insulate the signal output line on the third substrate, and the coverlay film covers and insulates only the signal output line on the LSI support part. The liquid crystal display device according to claim 1. 3. The liquid crystal display device according to claim 1, wherein a predetermined portion corresponding to the inclined portion is removed before the third substrate is bent. 4. The liquid crystal according to claim 1, wherein the inclined portion of the third substrate and the vicinity of the inclined portion are coated with an insulating adhesive. Display device.