JPH0521235B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display device in which a liquid crystal display section and a driving circuit are integrated. below,
The case where the display section is a liquid crystal will be explained.

Conventionally, at least one of the substrates holding the liquid crystal material is extended, and an integrated circuit or the like is mounted on the extended part.
Many forms of liquid crystal display devices that are smaller, more reliable, and easier to handle have been disclosed. The present invention provides a liquid crystal display device that solves the problem of having multiple wiring patterns when a plurality of integrated circuits are mounted on an extended portion of a substrate as shown in part A in FIG. 12 of the conventional example. .

When multiple integrated circuits are mounted on a board, it is very important to connect the common power supply, common signals, etc. of the multiple integrated circuits in order to reduce the number of external connection terminals and facilitate the interface. . The problem of such cross wiring is as shown in FIG. 11 of the conventional example.
The necessary cross wiring between the drive elements 1Z is performed on a synthetic resin printed circuit board 2Z that allows easy cross wiring using through holes, and the wiring between this synthetic resin printed circuit board 2Z and the liquid crystal display panel 3Z is performed on an insulating material. Connection depth 4 with a pattern made of conductive material
This problem has been solved with a structure connected by Z.

The disadvantages of this structure are that since the cross wiring is done through through holes, a printed circuit board 2Z that is capable of through holes is required, and a connecting tape 4Z is required, which increases material costs and equipment. The reliability of the connections has increased because there are three connections: between the drive element 1Z and the printed circuit board 2Z, between the printed circuit board 2Z and the connection tape 4Z, and between the connection tape 4Z and the liquid crystal display panel 3Z. There was a point of decline.

In order to eliminate such drawbacks, the present invention integrates the liquid crystal display panel 3Z and the printed circuit board 2Z,
The purpose is to reduce material costs, downsize, and improve connection reliability.Based on the following example,
Explain in detail.

The present invention eliminates the need for the printed circuit board 2Z and the connecting tape 4Z by mounting the driving element 1Z on a glass substrate that integrates the liquid crystal display panel 3Z and the printed circuit board 2Z and performing cross wiring, and the liquid crystal display panel 3Z and the printed circuit board 2Z are not required. The feature is that connection with panel 3Z is also unnecessary.

FIG. 1 shows a first embodiment of the invention. Integrated circuit 1 with at least a built-in LCD driver
A plurality of "a" are registered on the liquid crystal panel 5a. The material of the panel 5a is glass. The liquid crystal panel 5a is composed of at least two substrates, one of which is extended, and the integrated circuit 1a is mounted on the extended portion.
is installed. The liquid crystal panel 5a is composed of a portion 2a on which the integrated circuit 1a is mounted and a display portion 3a. A flexible substrate 6 is used to connect common signals of the plurality of integrated circuits 1a.
a is mounted on the extended portion 2a of the board, solving the problem of cross wiring. At the intersection of the cross wiring, the wiring on the extended portion 2a of the liquid crystal panel and the wiring on the flexible substrate 6a are connected by soldering.

FIG. 2 is an enlarged view of the connection part with the flexible substrate 6a among the extension parts of the liquid crystal panel 5a. A transparent electrode pattern 7a is made of tin, indium, etc. on a glass substrate constituting a liquid crystal panel. A metal such as nickel or tin is formed on the transparent electrode pattern 7a by electroless plating. These metals have good solderability. On the transparent electrode layer 7a, nickel,
A thin metal layer 8a made of tin or the like is formed.

FIG. 3 is an enlarged view of the flexible substrate 6a shown in the first embodiment of the liquid crystal display device of the present invention shown in FIG. The flexible substrate 6a of the present invention is used to solve the problem of cross wiring on the liquid crystal panel 5a. In the flexible substrate 6a, holes are made by drilling, punching, etc. at wiring intersections on the insulating film 9a, and a metal foil 10a such as copper foil is pasted over the holes. Both the insulating film 9a and the copper foil 10a have a thickness of 10 to 70 μm. Insulating film 9a
If the copper foil 10a is too thick, it cannot be used as a solution for cross wiring in the liquid crystal display device of the present invention.

FIG. 4 is a sectional view of the first embodiment of the liquid crystal display device of the present invention. Extension portion 2 of liquid crystal panel 5a
A transparent electrode is formed on a glass substrate, and the above-mentioned thin metal layer with good solder wettability is formed on the transparent electrode. On the other hand, the flexible substrate 6a is stacked on the extended portion 2a of the liquid crystal panel such that the insulating substrate side faces the extended portion 2a of the liquid crystal panel. Next, solder 12
a, the metal thin film 8a of the panel extension portion and the metal foil 10a of the flexible substrate 6a are combined.
There are various methods of soldering. Solder is poured into the hole 11a of the flexible substrate 6a while being heated to solder the copper foil 10a of the flexible substrate 6a and the metal thin film 8a of the extended portion 2a of the panel. This method has the advantage of being simple. Further, a solder layer is formed in advance on at least one of the metal thin film 8a formed on the extended portion 2a of the panel substrate and the metal foil 10a of the flexible substrate 6a by electroless plating or painting, and the two are bonded by thermocompression. There is also a method of joining using solder. This method helps reduce man-hours.

FIG. 5 shows a second embodiment of the liquid crystal display device of the present invention in which a display section and a drive circuit section are integrated. This extends the flexible substrate 6a and uses the wiring on the flexible substrate 6a as it is for connection to the external device 13. This eliminates the need for new connecting parts, making the liquid crystal display device easier to use and helping to reduce costs.

FIG. 6 shows an embodiment in which an oblong hole 11b is formed in a flexible substrate 6b used in the liquid crystal display device of the present invention, and a plurality of wiring lines 10b are passed through the hole 11b. When such a flexible substrate 6b is used, a plurality of intersections in the oval hole 11b can be connected at once, which helps to reduce the number of steps.

FIG. 7 shows the flexible substrate 6 shown in FIG.
This is an example in which cross-wiring is performed using b. By pressing a heated tool 15b such as a soldering iron against the oval hole 11b, the oval part 1 is removed at once.
It connects intersections within 1b.

FIG. 8 shows a flexible substrate 6 similar to FIG. 6.
This is an embodiment in which oval holes 11c and 11d are made in holes 11c and 11d in holes 11c and 11d, and a plurality of wiring lines 10c and 10d are passed through the holes. This is the pattern of the metal thin film 8a on the extension portion 2a of the opposing panel. The flexible substrate and the extended portion of the panel are connected in the same manner as in FIG. 7, but by using the flexible substrate in FIG. 8, the heating tool 15b for connection can be made smaller, which also leads to power savings. Also, various wiring patterns are possible, so
Wiring patterns can be created as needed.

FIG. 9a also shows an oval hole 1 in the flexible substrate 6e.
In this embodiment, a plurality of wires 10e are passed through a plurality of wires 10e with spaces 1e between them, but since the long axis direction of the ellipse is perpendicular to the wires, the heating tool 15b can be further miniaturized, which contributes to miniaturization of the connecting device and power saving. Helpful. Also, Figure 9b
is the pattern of the metal thin film 8a on the panel extension portion 2a facing the flexible substrate 6e. As can be seen from the figure, various patterns can be considered, and patterns can be created according to needs.

FIG. 10 shows an embodiment in which the flexible substrate 6e of FIG. 9 is used to perform cross wiring. Cross wiring at a plurality of locations is performed simultaneously using a plurality of heating tools 15c.

As shown in FIG. 4, in the liquid crystal display device of each embodiment described above using FIGS. 1 to 9, the insulating film 9a side of the flexible substrate 6a faces the extended portion 2a side of the liquid crystal panel. Since the wires are arranged as shown in FIG.
will not cause defects such as shorts or leaks. Further, since the wiring portion 10a of the flexible substrate and the wiring portion 8a of the liquid crystal panel are connected by soldering at the intersection, the reliability of the connection is better than that of a connection using a conductive adhesive. Furthermore, since the connections are made by soldering, the soldering serves both as an electrical connection and a mechanical connection. Therefore, the flexible substrate 6a is connected to the extension part 2 of the liquid crystal panel.
It is not necessary to fix it by any other method other than soldering in order to mechanically connect it to. Also,
The printed circuit board 2Z and connection tape 4Z shown in conventional example FIG. 10 are no longer required, and along with this, the connection between the printed circuit board 2Z and the connection tape 4Z and the connection between the connection tape 4Z and the liquid crystal display panel 3Z are no longer necessary. become. This reduces material costs and connection man-hours,
Product costs can be reduced. Furthermore, by reducing the number of connection points to nearly 1/2 to 1/3, it is possible to improve connection reliability. Furthermore, the characteristics of liquid crystal display devices, which are thinner and more compact, have been further reduced, making them easier to handle. Further, by making the holes 11 in the flexible substrate 6 smaller as shown in FIGS. 8 and 9, the heating tool can be made smaller, which is useful for reducing power consumption. Further, by using a bonding device equipped with a plurality of heating tools as shown in FIG. 10, it is possible to perform cross-wiring at a plurality of locations at the same time, thereby reducing the number of man-hours and costs.

As mentioned above, the liquid crystal display device of the present invention has significantly fewer connection points than the conventional one, so that
Work hours and connection resistance are significantly reduced, and connection reliability is improved. Further, by using a flexible substrate having holes for connection with a common power source and a common signal line, the degree of freedom in mounting increases. Furthermore, by connecting the integrated circuit to an extension of at least one of the substrates, it is possible to reduce the pitch, but if the present invention is used, high definition and
It can also be applied to high-density display elements.

As described above, the liquid crystal display device of the present invention is compact, easy to use, and greatly contributes to the development of industry when liquid crystal displays are applied to various fields.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the liquid crystal display device of the present invention. FIG. 2 is an enlarged view of the liquid crystal panel substrate portion of the liquid crystal display device of the present invention. FIG. 3 shows a flexible substrate used in the liquid crystal display device of the present invention. FIG. 4 is a sectional view of the liquid crystal display device of the present invention shown in FIG. 1. FIG. 5 shows a second embodiment of the liquid crystal display device of the present invention. FIG. 6 shows a second embodiment of a flexible substrate used in the liquid crystal display device of the present invention. FIG. 7 is a mounting process diagram of the flexible board shown in FIG. 6. FIG. 8 shows a third embodiment of the flexible substrate used in the liquid crystal display device of the present invention and a second embodiment of the pattern of the metal thin film on the extended portion of the panel. FIG. 9 shows a fourth embodiment of the flexible substrate used in the liquid crystal display device of the present invention and a third embodiment of the pattern of the metal thin film on the extended portion of the panel. FIG. 10 is a mounting process for the flexible board shown in FIG. 9. FIGS. 11 and 12 are diagrams showing conventional liquid crystal display devices. 1a is an integrated circuit, 2a is an extension of the liquid crystal panel,
3a is a display part of a liquid crystal panel, 5a is a liquid crystal panel,
6a, 6b, 6c, 6d, 6e are flexible substrates, 7a is a transparent electrode pattern, 8a is a metal thin film pattern, 9a is an insulating film, 10a is wiring on the flexible substrate, 11a, 11b, 11c, 1
1d and 11e are holes in the flexible board, 12a is solder, and 15b is a heating tool for soldering.

Claims (1)

[Claims] 1. A liquid crystal substance, a pair of substrates sandwiching the liquid crystal substance, and electrodes formed on the surfaces of the substrates, the integrated circuit and the electrodes being connected by an extension of the substrate, and at least an end of the extension of one of the substrates. a common signal line connected to the integrated circuit disposed on the substrate; a flexible substrate having a wiring pattern formed corresponding to the common signal line and disposed on an extended portion of the one substrate; and the wiring A liquid crystal display device, characterized in that a hole is formed in an insulating portion to expose a part of the pattern, and the exposed wiring pattern and the common signal line are electrically connected.