JP2880186B2 - Liquid crystal display - Google Patents

Description

Description: 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 thin film transistor or the like and having a flat shield case.

[Conventional technology]

An active matrix type liquid crystal display device has a non-linear element (switching element) provided for each of a plurality of pixel electrodes arranged in a matrix. Since the liquid crystal in each pixel is theoretically always driven (duty ratio 1.0), the active method has better contrast than the so-called simple matrix method that employs the time-division driving method. It is not a technology. A typical switching element is a thin film transistor (TFT).

For example, an active matrix color liquid crystal display device including a thin film transistor and a pixel electrode as one component of a pixel includes a liquid crystal display panel (LCD) in which a plurality of pixels are arranged in a matrix. Each pixel of the liquid crystal display panel is arranged in a drive wiring, that is, in an intersection area between two adjacent scanning signal lines and two adjacent video signal lines. The scanning signal lines extend in the horizontal direction and are arranged in a plurality in the vertical direction. On the other hand, a plurality of video signal lines extend in the vertical direction intersecting with the scanning signal lines, and are arranged in a plurality in the horizontal direction.

The liquid crystal display panel includes a lower substrate in which a thin film transistor, a transparent pixel electrode, an alignment film, and the like are sequentially provided on a lower (based on liquid crystal) transparent glass substrate, a color filter, a common transparent pixel electrode on an upper transparent glass substrate, It is composed of an upper substrate on which alignment films and the like are sequentially provided, a liquid crystal sealed between the alignment films of both substrates, and a sealing member for the liquid crystal provided on a peripheral portion of the panel. The transparent pixel electrode and the thin film transistor are provided for each pixel. One of a source electrode and a drain electrode of the thin film transistor is connected to the transparent pixel electrode, the other electrode is connected to a video signal line, and the gate electrode is connected to a scanning signal line.

2. Description of the Related Art A conventional flat type liquid crystal display device mainly includes a thin upper and lower two shield cases, a thin film transistor array, a liquid crystal display panel attached to a window opened in the shield case, and a semiconductor integrated circuit for driving the liquid crystal display panel. TA with chip (hereinafter referred to as drive IC) mounted
B (tape automated bonding) and TAB
And a printed circuit board (PCB) on which is mounted. The input terminals of the drive wiring provided on the periphery of the liquid crystal display panel (on the lower glass substrate larger in size than the upper glass substrate) and the output outer leads of the TAB are connected to the anisotropic conductive film (perpendicular to the plane). Are electrically connected by a film having a property that current flows but does not flow horizontally. Further, the input-side outer lead of the TAB is electrically and mechanically connected to a terminal of the PCB which is connected to signal transmitting means outside the liquid crystal display device by soldering. Further, electrodes (bonding pads) of the drive IC are bonded to inner leads of the TAB.

Each component such as a liquid crystal display panel and a TAB and a PCB on which a drive IC is mounted are built in a shield case, and the two shield cases are combined and fixed. Further, each shield case is provided with a window for a liquid crystal display panel, and the liquid crystal display panel is fitted in the window so that the liquid crystal display screen can be seen from the window.

Note that an active matrix liquid crystal display device using a TFT is, for example, "12.5 type active matrix color liquid crystal display employing a redundant configuration", Nikkei Electronics, pp. 193-210, December 15, 1986, Nikkei McGraw-Hill, Inc. Issued, known in.

[Problems to be solved by the invention]

Conventional liquid crystal display devices use TABs that do not have sufficient thermal reliability, so the TAB leads often break during heat cycle testing and use, and the manufacturing costs are high due to the large number of steps. There is.

Also, so-called COG (chip-on-glass) mounting, in which a drive IC is mounted directly on a glass substrate without using TAB, has been proposed. However, conventionally, the driving I
In order to connect C, PCB, and FPC, the wiring pattern formed on the glass substrate is plated with Au, etc., which requires a lot of man-hours, and the soldering process raises the temperature to 200 ° C or more, so the wiring pattern peels off. There is a problem that it is easy.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device that can improve reliability, reduce manufacturing cost, and reduce the number of steps and simplify the manufacturing process without using TAB.

[Means for solving the problem]

In order to solve the above problems, a liquid crystal display device according to the present invention includes an upper glass substrate, a lower glass substrate having a portion that is overlapped with the upper glass substrate and has a portion protruding from the upper glass substrate, the upper glass substrate and the lower glass. A liquid crystal display panel comprising liquid crystal sealed and sealed between substrates, a drive IC for driving the liquid crystal display panel, a plurality of drive wirings for supplying an output voltage of the drive IC to the liquid crystal display panel, A plurality of input wirings connected to the input terminals of the drive IC are provided in a portion of the lower glass substrate protruding from the upper glass substrate, and an FPC is formed using an anisotropic conductive film for the input wirings on the lower glass substrate. Connected, bending the FPC to the back surface of the lower glass substrate, and providing an upper case for housing a portion provided with the drive IC on the lower glass substrate,
A portion connected to the input wiring of the FPC is pressed by the upper case via a spacer, and a lower case coupled to the upper case is provided on a back surface of the lower glass substrate,
A portion of the FPC bent toward the rear surface of the lower glass substrate is pressed by the lower case with an insulating sheet interposed.

[Action]

In the liquid crystal display device of the present invention, since the drive IC is mounted directly on the glass substrate and the TAB is not used, there is no possibility that the lead of the TAB is cut, and the reliability can be improved. Also, since anisotropic conductive film is used without using TAB and soldering,
No peeling of the wiring pattern occurs, the number of steps can be reduced, and the manufacturing process can be simplified.

Other objects and features of the present invention will become apparent from the following description with reference to the drawings.

〔Example〕

FIG. 2 is a sectional view of a liquid crystal display section of an active matrix type color liquid crystal display device according to an embodiment of the present invention.
The figure is an equivalent circuit diagram of the liquid crystal display unit.

<< Overall Structure of Panel Section >> As shown in FIG. 2, the liquid crystal display panel has a thin film transistor TF on a lower transparent glass substrate SUB1 based on the liquid crystal layer LC.
T and a transparent pixel electrode ITO1, a thin film transistor TFT protective film PSV1, a first substrate sequentially provided with a lower alignment film ORI1 for setting the orientation of liquid crystal molecules, and a black matrix BM and a color filter FIL on an upper transparent glass substrate SUB2. , A second substrate on which a protective film PSV2 of a color filter FIL, a common transparent pixel electrode ITO2, and an upper alignment film ORI2 are sequentially provided;
Liquid crystal LC sealed between B1 and SUB2 alignment films ORI1 and ORI2
And a sealing material (sealing member) SL provided around the two substrates and sealing the liquid crystal LC between the two substrates. The thickness of the lower transparent glass substrate SUB1 is, for example, 1.1 m
m.

The center part in FIG. 3 shows a cross section of one pixel portion,
The left side shows a cross section of a left edge portion of the transparent glass substrates SUB1 and SUB2 where the external lead-out wiring exists. The right side shows a cross section of a portion on the right edge portion of the transparent glass substrates SUB1 and SUB2 where no external lead-out wiring exists.

In the method for manufacturing a liquid crystal display panel, the first substrate;
The second substrate and the second substrate are separately formed, and a predetermined distance is provided by interposing a spacer material (not shown) between the two substrates so that the alignment films ORI1 and ORI2 of the two substrates face each other. It is assembled by overlapping, sealing the liquid crystal LC between both substrates, and sealing with a sealing material SL provided around both substrates. A backlight BL is arranged on the lower transparent glass substrate SUB1 side.

The sealing material SL shown on each of the left and right sides of FIG.
The transparent glass substrates SUB1 and SU are configured to seal the liquid crystal LC, excluding the liquid crystal filling port (not shown).
It is provided along the entire periphery of the edge of B2 and is made of, for example, epoxy resin.

The common transparent electrode ITO2 on the upper transparent glass substrate SUB2 side is, at least in one place, by a silver paste material SIL,
It is connected to the external lead-out wiring provided on the lower transparent glass substrate SUB1 side. This external wiring is connected to the transparent pixel electrode layer
It is formed of ITO1.

The alignment films ORI1 and ORI2, the transparent pixel electrode ITO1, and the common transparent electrode ITO2 are provided inside the sealing material SL. Polarizing plate PO
L is lower transparent glass substrate SUB1, upper transparent glass substrate SUB
2 are provided on the outer surface of each.

The transparent pixel electrode ITO1 and the thin film transistor TFT are provided for each pixel.

<< Thin Film Transistor TFT >> The thin film transistor TFT of each pixel has 3
It is divided into two (plurality), and is constituted by thin film transistors (divided thin film transistors) TFT1, TFT2 and TFT3.
Each of the thin film transistors TFT1 to TFT3 has substantially the same dimensions (the same channel length and width).
Each of the divided thin film transistors TFT1 to TFT3 mainly includes a gate electrode GT, a gate insulating film GI, an i-type (intrinsic,
intrinsic, not doped with conductivity determining impurities)
An i-type semiconductor layer AS made of an amorphous silicon (Si) semiconductor,
It is composed of a pair of source electrode SD1 and drain electrode SD2. It should be understood that the source / drain is originally determined by the bias polarity between them, and the polarity is inverted during the operation in the circuit of the liquid crystal display device, so that the source / drain is switched during the operation. However, also in the following description, for convenience, one is fixed as a source and the other is fixed as a drain. The thin film transistor TFT has a source electrode SD1 connected to the transparent pixel electrode ITO1, and a drain electrode SD2 connected to the video signal line D1.
L, and the gate electrode GT is connected to the scanning signal line GL.

《Light shielding film BM》 Thin film transistor TF from the upper transparent glass substrate SUB2 side
In order to shield light from T1 to T3, the scanning signal line G on the substrate SUB2 is used.
A black matrix BM made of a chrome layer or the like is provided in a portion corresponding to L, the video signal line DL, and the thin film transistor TFT. Thereby, the contour of each pixel is made clear by the light shielding film BM, and the contrast is improved. In other words, the light shielding film BM
Has two functions of shading the semiconductor layer AS and a black matrix.

It should be noted that the backlight can be attached to the SUB2 side and the SUB1 can be the observation side (externally exposed side).

<< Common Electrode ITO2 >> The common transparent electrode ITO2 is arranged to face the transparent pixel electrode ITO1 provided for each pixel on the lower transparent glass substrate SUB1 side, and is configured to be common to a plurality of pixel electrodes ITO. ing. A common voltage is applied to the common transparent electrode ITO2.

<< Equivalent Circuit of Entire Display Panel >> FIG. 3 shows an equivalent circuit of this liquid crystal display device. A plurality of pixels of the liquid crystal display section are arranged in the same column direction as the direction in which the scanning signal lines Y1, Y2, ... extend, and the pixel columns XiG, XiB, Xi
+ 1R,... Color filter FI
L is formed in a dot shape for each pixel at a position facing the pixel and is dyed separately. iG, Xi + 1G,... are video signal lines DL connected to pixels on which the green filter G is formed. XiB, Xi + 1B,... Are video signal lines DL connected to the pixels on which the blue filters B are formed. Xi + 1R, Xi +
Are video signal lines DL connected to pixels on which the red filter R is formed. These video signal lines DL are selected by video signal drive circuits provided above and below the liquid crystal display panel. Yi is a scanning signal line GL for selecting the pixel column X1 shown in FIG. Similarly, each of Yi + 1, Yi + 2,... Is a scanning signal line for selecting each of the pixel columns X2, X3,.
GL. These scanning signal lines GL are connected to a vertical scanning circuit provided on the left side of the liquid crystal display panel. On the right side of the liquid crystal display panel, a power supply circuit and a circuit for converting CRT information from the host (upper processing unit) into information for the TFT liquid crystal display panel are provided.

FIG. 1A is an exploded perspective view of a liquid crystal display device according to one embodiment of the present invention, and FIG. 1B is a liquid crystal display panel, a wiring pattern, an FPC, a driving IC, and the like. FIG. 1C is a partial enlarged perspective view of a liquid crystal display panel, an FPC, and the like.

1 is an upper shield case, 2 is a holding spacer made of rubber or the like, 3 is a convex portion formed integrally with the upper shield case 1, 4 is a liquid crystal display panel, 5 is an upper transparent glass substrate, and 6 is a lower transparent. It is a glass substrate. An upper transparent glass substrate 5 is overlaid on the lower transparent glass substrate 6, and a liquid crystal (not shown) is sealed and sealed between the two substrates. The size of the lower transparent glass substrate 6 is larger than that of the upper transparent glass substrate 5, and the outer peripheral portions of the four sides of the upper transparent glass substrate 5 become drive wiring regions of the liquid crystal display panel 4. 7 is drive I
C and 8 are drive wiring patterns formed on the lower transparent glass substrate 6, 9 is an input wiring pattern of the drive IC 7, 10a and 10
b, 10c, 10d are FPCs provided around the four sides of the lower transparent glass substrate 6, 11 is a controller for changing a video signal into a TFT drive signal, 12 is a capacitor, a resistor,
13 is a chip part such as a passive element, 13 is a connector part into which a connector for sending data from a personal computer or the like is inserted, 14 is a connector part.
Is an adhesive tape for attaching the FPCs 10a to 10d to the lower transparent glass substrate 6, 15 is a lower shield case, 16 is a swaging hole formed in the lower shield case 15 for inserting the caulking projection 3, and 17 is a shield. The case ground, 18 is the insulating vinyl sheet, and 19 is the FPC ground. In FIG. 1 (B), reference numeral 20 denotes a wiring pattern for connecting FPCs 10a to 10d, and in FIG. 1 (C), reference numeral 21 denotes FPCs 10a to 10d.
An anisotropic conductive film provided between 10d and the wiring patterns 9 and 20 of the lower transparent glass substrate 6, a bonding wire 22 for connecting the driving IC 7 and the wiring patterns 8 and 9;
Protects the bonding wire 22 connected to the drive IC 7,
A mold resin for fixing, 24 is an IC adhesive for bonding the drive IC 7 to the lower transparent glass substrate 6, 25 is a caulking portion of the caulking convex portion 3, and 26 is an upper transparent glass substrate 5 and a lower transparent glass substrate. 6 is a polarizing plate provided on the outer surface. Although not shown, a diffusion plate for diffusing backlight light can also be attached to the lower shield case 15 with an adhesive or the like.

Next, a method for mounting the liquid crystal display device will be described. First, as shown in FIGS. 1A and 1B, the driving IC 7 is
It is positioned and bonded on the lower transparent glass substrate 6 using the bonding adhesive 24, and is bonded to the wiring patterns 8 and 9 by bonding wires 22. The bonding side of the wiring patterns 8 and 9 was made of Al / Cr or Al having good connectivity.
Next, in order to ensure the reliability, as shown in FIG. 1C, the drive IC 7, the bonding wires 22, and the bonding portion are coated with resin (mold resin 23).
Complete 7 COG implementations. At the time of wire bonding, the number of wires is about 2000 for 10 VDT (10-inch visual display terminal), so parallel bonding was adopted to shorten the process.

Next, the FPCs 10a to 10d on which the controller 11 and the chip component 12 are mounted in advance are positioned on the wiring pattern 9 and connected using the anisotropic conductive film 21. At this time, FPC10a ~ 10d
The FPC connection wiring pattern 20 connecting the FPC and the FPCs is also connected by the anisotropic conductive film 21 at the same time. Wiring pattern 9, 20
In consideration of the current margin of the anisotropic conductive film, the bonding area was designed to be as large as possible. The material of the wiring patterns 9 and 20 at the connection portion with the FPCs 10a to 10d was ITO (Nesa film) / Cr.

Next, as shown in FIG. 1 (C), the FPCs 10a to 10d are adhered to the back surface of the lower transparent glass substrate 6 using an adhesive tape 14, and an assembly as shown in FIG. 1 (B) is completed. . The polarizing plate 26 is usually attached at the time of assembling the liquid crystal display panel itself. However, since the polarizing plate 26 may be damaged by heating when the mold resin 23 is cured, the polarizing plate 26 shown in FIG. After the three-dimensional object is completed, it is better to paste it.

Next, the assembly shown in FIG. 1B is housed in the shield cases 1 and 15, and the shield cases 1 and 15 are assembled. The shield cases 1 and 15 are caulked and fixed by the caulking projections 3 and the caulking holes 16 as shown in the caulking portion 25 in FIG. 1 (C). At this time, the upper shield case 1
A spacer 2 made of rubber or the like is interposed between the FPCs 10a to 10d and the wiring patterns 9 and 20 of the lower transparent glass substrate 6 by interposing a spacer 2 made of rubber or the like between the assembly and the assembly shown in FIG. Since the connection portion of the conductive film 21 is strongly pressed by the upper shield case 1 and the spacer 2, the reliability of the connection portion is improved. The ground 17 of the shield case shown in FIG. 1A is connected to the ground 19 of the FPC by soldering. Further, in order to ensure insulation of the drive wiring portion, an insulating vinyl sheet 18 is interposed between the lower shield case 15 and the assembly of FIG. 1 (B).

FIG. 4 is a partial plan view of a lower transparent glass substrate of the liquid crystal display panel. In this embodiment, dummy terminals 27 are provided on one side (or both sides) of the input wiring pattern 9 to the driving IC 7 and the wiring pattern 20 for connection between the FPCs 10a to 10d in order to increase the adhesive strength of the FPCs 10a to 10d to the lower transparent glass substrate 6. Are provided. The dummy terminal 27 is not normally used. That is,
The display circuit is a terminal that is electrically disconnected, and is an electrically floating (floating) terminal.

In the liquid crystal display device of the present embodiment, since the drive IC 7 is mounted on the lower transparent glass substrate 6 and the TAB is not used, there is no fear of cutting the lead of the TAB, and the reliability can be improved. Also,
Since no TAB is used, man-hours can be reduced and manufacturing costs can be reduced. In addition, since the wiring patterns 9, 20 and the FPCs 10a to 10d are connected to each other by using the anisotropic conductive film 21 having a low connection time and a short heating time without using TAB, the wiring patterns do not peel off, The number of steps can be reduced, the manufacturing process can be simplified, and the manufacturing cost can be reduced. The FPCs 10a to 10d are connected to each other by connecting the FPC to the connection wiring pattern 20 formed on the lower transparent glass substrate 6 via the anisotropic conductive film 21. Is unnecessary,
Man-hours and manufacturing costs can be reduced. Furthermore, anisotropic conductive film
The size of the wiring pattern at the location connected by 21 can be increased because the space in the wiring forming area is large, and the current capacity can be sufficiently satisfied. Therefore, in this embodiment, a lightweight, small, and inexpensive liquid crystal display device can be provided.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it is needless to say that various changes can be made without departing from the scope of the present invention. For example, in the above embodiment, the FPCs 10a to 10d are connected to each other by using the FPC connection wiring pattern 20 provided on the lower transparent glass substrate 6, but the lower transparent glass substrate 6 has the FPC connection wiring FPC 10a ~ 1 without pattern 20
The 0d may be partially overlapped, and connection terminals may be provided at the overlapping portions to connect.

〔The invention's effect〕

As described above, according to the liquid crystal display device of the present invention, since the drive IC is directly mounted on the glass substrate and the TAB is not used, there is no possibility that the lead of the TAB is cut, and the reliability can be improved. Also, since the anisotropic conductive film is used without using TAB and soldering, the wiring pattern does not peel off, the number of steps can be reduced, and the manufacturing process can be simplified.
Manufacturing costs can be reduced.

[Brief description of the drawings]

FIG. 1A is an exploded perspective view of a liquid crystal display device according to one embodiment of the present invention, and FIG. 1B is a liquid crystal display panel, a wiring pattern, an FPC, a driving IC, and the like. Partially enlarged view,
Fig. 1 (C) shows a liquid crystal display panel near the controller, FP
FIG. 2 is a sectional view of a liquid crystal display of an active matrix type color liquid crystal display device according to an embodiment of the present invention, FIG. 3 is an equivalent circuit diagram of the liquid crystal display, and FIG. FIG. 3 is a partial plan view of a lower transparent glass substrate of the liquid crystal display panel. DESCRIPTION OF SYMBOLS 1 ... Upper shield case 2 ... Holder spacer 3 ... Caulking convex part 4 ... Liquid crystal display panel 5 ... Upper transparent glass substrate 6 ... Lower transparent glass substrate 7 ... Drive IC 8 ... Drive wiring pattern 9 ... Input wiring pattern of drive IC 10a, 10b, 10c, 10d… FPC 11… Controller 12… Chip parts 13… Connector part 14… Adhesive tape 15… Bottom shield case 16… Crimping hole 17… Shield case ground 18… Insulation vinyl sheet 19… FPC ground 20: Wiring pattern for connection between FPCs 21: Anisotropic conductive film 22: Bonding wire 23: Mold resin 24: Adhesive for IC 25: Caulking part 26: Polarizing plate 27: Dummy terminal

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G02F 1/1345

Claims (1)

(57) [Claims] An upper glass substrate, a lower glass substrate having a portion that is overlapped with the upper glass substrate and protrudes from the upper glass substrate, and a liquid crystal sealed and sealed between the upper glass substrate and the lower glass substrate. A liquid crystal display panel, a driving IC for driving the liquid crystal display panel, a plurality of driving wires for supplying an output voltage of the driving IC to the liquid crystal display panel, and a plurality of inputs connected to input terminals of the driving IC. Wiring is provided on a portion of the lower glass substrate protruding from the upper glass substrate, and an FPC is connected to the input wiring on the lower glass substrate using an anisotropic conductive film, and the FPC is connected to the back surface of the lower glass substrate. And an upper case for accommodating a portion of the lower glass substrate on which the drive IC is provided is provided, and a portion of the FPC connected to the input wiring is connected to the upper case via a spacer. A lower case coupled to the upper case is provided on the back surface of the lower glass substrate, and a portion of the FPC bent to the back surface of the lower glass substrate is pressed by the lower case with an insulating sheet interposed. A liquid crystal display device characterized by the above-mentioned.