JPH0652343B2 - Liquid crystal display - Google Patents

Description

The present invention relates to a liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device in which a liquid crystal panel and a circuit board on which a drive circuit is mounted are integrated.

Such a liquid crystal display device is used for a clock display and an alpha-numeric (hereinafter abbreviated as αN) display for displaying numbers and characters. The present invention provides a liquid crystal display device which uses a film-shaped electrode connector to connect a liquid crystal panel and a circuit board, and which has good reliability and assemblability.

(Prior Art) Conventionally, conductive rubber has been generally used to connect a liquid crystal panel and a circuit board.

(Problems to be Solved by the Invention) However, in the above-described conventional technique, it is difficult to align the conductive rubber. Further, for electrical connection, the conductive rubber must be pressed with a constant force, which makes it difficult to adjust the force. Also, the presser foot is likely to be uneven. Further, there is a defect that the circuit board is easily bent by the force of crushing the conductive rubber, which may impair reliability.

Therefore, an object of the present invention is to provide a liquid crystal display device which is easy to assemble. Another object of the present invention is to provide a highly reliable liquid crystal display device.

(Means for Solving the Problem) A liquid crystal display device of the present invention is a liquid crystal panel, a circuit board on which a drive element for driving the liquid crystal panel is disposed, and a holding frame for fixing the liquid crystal panel to the circuit board. In the liquid crystal display device having, the liquid crystal panel and the circuit board are electrically connected using a film electrode connector based on a plastic film, between the liquid crystal panel and the circuit board, The first connection portion between the film-shaped electrode connector and the liquid crystal panel is pressed on one side, and the second connection portion between the film-shaped electrode connector and the circuit board is pressed on the other side. An elastic body having an end portion corresponding to at least one of the first and second connection portions and the film-shaped electrode connector bonded by an adhesive member is arranged.

As the film-like electrode connector, for example, Japanese Patent Laid-Open No.
There is a connector disclosed in Japanese Patent No. 5-60987,
The present invention utilizes such a connector to construct a liquid crystal display device having excellent assemblability and reliability.

(Examples) Hereinafter, a liquid crystal display device of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a first embodiment of the liquid crystal display device of the present invention. The liquid crystal panel 1 is connected to the circuit board 3 by the holding frame 2.
, And a simple signal is input to the terminals on the circuit board 3 from the outside to display on the liquid crystal panel 1 (for example, “EPSON”).

FIG. 2 shows a sectional view of the liquid crystal display device according to the first embodiment of the present invention shown in FIG. 1, and FIG. 3 shows an exploded view.

The liquid crystal panel 1 shown in FIGS. 2 and 3 is composed of at least two substrates made of a glass plate or a plastic film, and a liquid crystal material sandwiched between the substrates. When the liquid crystal panel 1 is a twisted nematic type (hereinafter abbreviated as TN type), the upper and lower polarizing plates and the reflection plate are fixed to the substrate by a silicon-based or acrylic-based adhesive or adhesive. When the liquid crystal panel 1 is a white-tailored guest-host type (hereinafter abbreviated as GH type), a UV filter is attached to the upper surface of the liquid crystal panel 1, and a reflector is attached to the lower surface.

At least a driving element 4 such as an IC for driving and displaying the liquid crystal panel 1 is mounted on the circuit board 3. As the circuit board 3, a glass epoxy board, a paper epoxy board, a paper phenol board, a CC4 board (manufactured by Hitachi Chemical) or the like is used. The glass epoxy substrate has high reliability, high heat resistance, low heat shrinkage, and good environmental resistance. A paper epoxy board, a paper phenol board, or a CC4 board is easy to cost. In particular, the CC4 substrate has a simple manufacturing process and a low cost. The circuit board 3 needs to have a certain hardness, and an extremely soft material such as a flexible board is generally unsuitable. However, since the liquid crystal panel 1 and the circuit board 3 are connected by thermocompression bonding of the film-shaped electrode connector 5, compared with the case where the conventional conductive rubber is used, the circuit board 3
The hardness of is good. On the circuit board 3, a metal pattern on the circuit board 3 is exposed at a connection portion of the film electrode connector 5 (hereinafter, abbreviated as a board connector portion). The metal pattern is generally copper foil, and preferably has a thickness of 3 to 20 μm or less. The ordinary copper foil has a thickness of 39 μm, but the thickness of the copper foil of the board connector portion 31 of the circuit board 3 used in the liquid crystal display device of the present invention is in the range of 3 to 20 μm. . Nickel plating or solder plating, or gold plating or gold flash on the copper foil pattern,
A thin metal layer having a thickness of 0.1 to 3 μm may be formed by electroless gold plating, silver plating, silver flanche, or electroless silver plating.

The thickness of the metal pattern of the board connector portion 31 is such that, when such a thin metal layer is formed, the thickness including the thin metal layer is within a range of 3 to 20 μm. By forming the thin metal layer on the metal pattern such as copper foil, the electrical connection between the film-shaped electrode connector 5 and the circuit board 3 is improved, and the rust prevention of the metal pattern improves the reliability of the electrical connection. The electrical resistance of the connecting portion is reduced, and when driving the liquid crystal panel, there is no sagging of the drive waveform due to the time constant of CR, so that the drive display characteristics are improved. This advantage is particularly great when a thin metal layer is formed in a silver foil shape. Particularly, in the field where reliability is required, gold plating by electrolysis is performed, and when the terminal for electroplating cannot be taken out, electroless gold plating or gold flash is preferable.

An external terminal 32 for electrically connecting to the outside is provided at the end of the circuit board 3. This may have a connector attached. Mounting holes 30 formed by through holes are provided at four ends of the circuit board 3 so that the liquid crystal display device can be easily attached to an external device. Through hole 20 in the presser frame 2
Is provided. The liquid crystal display device of the present invention includes a bolt,
It is used by attaching it to an external device through a through hole 20 and a mounting hole 30 with a nut, a screw or the like.

The film-shaped electrode connector 5 electrically connects the circuit board 3 and the liquid crystal panel 1. The film-shaped electrode connector 5 has a conductive portion and an insulating portion formed on a polyester film having a thickness of, for example, 10 to 50 μm, and at least the insulating portion is composed of a hot-melt type adhesive, and the liquid crystal panel 1 and the circuit board 3 are provided. The electrical and mechanical connection is made by thermocompression bonding of and. The conductive pattern portion is printed with a predetermined pattern by mixing conductive powder such as silver powder, graphite powder or carbon black into an epoxy-based, rubber-based or thermoplastic-based adhesive and screen-printing it. It Something like this:
For example, spot weld sealer 1 made by Cemedine KK
There is a conductive adhesive E202 manufactured by 63M or Epotek. An insulating hot-melt type adhesive is formed by screen printing between the conductive pattern portions. Examples of such an adhesive include "6" manufactured by Cemedine KK.
There is 500 ". In addition, the conductive adhesive forming the conductive pattern is a hot-melt type adhesive such as "6500" made by Cemedine KK, in which conductive powder such as silver powder, graphite or carbon black is mixed to obtain hot-melt property and conductivity. May be combined. In addition, an insulating adhesive or paint having no hot-melt property may be applied or screen-printed on portions other than the terminal portion of the film-like electrode connector 5. This adhesive may be an epoxy-based or thermoplastic-based adhesive or paint, such as "1565" or "181" manufactured by Cemedine KK. Such conductive adhesives, hot melt type adhesives, insulating adhesives or coatings, and other examples of the film-like electrode connector are described in detail in JP-A-55-60987.
The film-shaped electrode connector 5 disclosed in JP-A-55-60987 is a product name "heat seal" (Nippon Graphite K
(Made by K). The film electrode connector is electrically and mechanically connected to a liquid crystal panel or a circuit board by heating and pressure bonding. As the thermocompression bonding condition, for example, a pressure of 5 kg / cm ^{2 and} a temperature of 180 ° C. for about 10 seconds are sufficient.

The elastic body 6 includes sponge rubber, natural rubber, urethane foam,
The film is an elastic body made of silicon rubber or the like, and is formed in such a size that the liquid crystal panel 1 is compressed when it is fixed to the circuit board 3 by the holding frame 2, and the repulsive force generated thereby is used to form the film. The connector for pressing the electrode connector 5, the liquid crystal panel 1, and the circuit board 3 is pressed. In addition to this, the elastic body 6 also has a function of a support for holding the liquid crystal panel 1 at a predetermined position. The conductive pattern portion of the terminal connecting portion of the film-like electrode connector 5 is mechanically coupled to the adherend of the liquid crystal panel 1 or the circuit board 3 by the hot-melt type insulating adhesive formed outside the conductive pattern portion. In the case where the conductive body comes into contact with the conductive terminal portion of the adherend due to the force and the electric conduction is obtained, the elastic body 6 presses the terminal portion, so that the elastic body 6 is bonded by the hot-melt type adhesive. Since the force by the presser works, the reliability of the connection is improved both mechanically and electrically.

A double-sided adhesive member 61 may be formed on one surface or two surfaces of the elastic body 6. The double-sided adhesive member 61 may be a commercially available double-sided tape. Further, this is one in which an acrylic, rubber or thermoplastic adhesive is formed on the surface of the elastic body 6 by spraying, brushing, screen printing or the like. This includes, for example, Cemedine KK "8
There is 400 ".

The presser frame 2 is a thin metal plate with a thickness of 0.1 to 1.2 mm.
It is a degree. Material is iron, copper, bronze, brass, stainless steel,
There are aluminum plates, etc. The thin metal plate used for the presser frame 2 has a constant thickness, and is a distributed metal material, for example, a rolled steel plate. The iron material is the cheapest available. When an iron material is used, plating with nickel, chromium, etc. provides a rustproof effect. Further, the use of a stainless steel plate has advantages such as strong resistance to rust, easy processing, and toughness. The holding frame 2 is formed by bending one metal plate into a predetermined shape by pressing or the like and bending it.

Next, a method of assembling the liquid crystal display device of the present invention using such parts will be described.

First, the film-shaped electrode connector 5 is thermocompression-bonded to the liquid crystal panel 1 by hot pressing. Next, the other terminal of the film electrode connector 5 is connected to the circuit board 3 by hot pressing. Next, the elastic body 6 is placed below the terminals of the liquid crystal panel 1. Next, the holding frame 2 is set from above the liquid crystal panel 1 so that the feet 23 enter the holes 33 of the circuit board 3.
Next, the foot 23 of the holding frame 2 protruding from the back surface of the hole 33 of the circuit board is twisted, and the holding frame 2 and the liquid crystal panel 1 are attached to the circuit board 3.
To fix.

When the press frame 2 and the circuit board 3 are provided with the through holes 20 and the mounting holes 30 for assembling, the workability is improved and the liquid crystal panel 1 is properly aligned, so that the liquid crystal display has a beautiful appearance. The device is assembled. This is because when the press frame 2 is fixed to the circuit board 3, the through hole 20 of the press frame 2 is used.
And the elongated holes (hereinafter,
(Referred to as a pin), and the relative positions of the circuit board 3 and the holding frame 2 are aligned by the pin. Through hole 20, mounting hole 3
The positions of 0 and pins are such that the outer periphery of the liquid crystal panel 1 is in contact with the through hole 20, the mounting hole 30, and the outer periphery of the pin. Next, the liquid crystal panel 1 is provided with the outer periphery of the through hole 20,
It is moved so as to come into contact with the outer circumference of the pin inserted into the mounting hole 30. Next, the foot 23 of the holding frame 2 is twisted to fix the liquid crystal panel 1 and the holding frame 2 to the circuit board 3.

FIG. 4 shows an example of the film electrode connector 5 used in the liquid crystal display device of the present invention. FIG. 4 (a) is a plan view,
FIG. 4 (b) is a sectional view. Reference numeral 51 is a base film made of a material such as polyester, polyethylene or cellulose acetate. The conductive member 5 is formed on the base film 51.
There are a conductive pattern portion where 2 is arranged and an insulating portion where a hot melt type insulating adhesive 53 is arranged, and an insulating member 54 is arranged outside the terminal portion. Insulating member 54
Uses a thermosetting epoxy-based adhesive or rubber-based adhesive that does not have hot-melt properties. By arranging the insulating member 54 in this manner, the film-shaped electrode connector 5 becomes tough, and is less likely to tear, break, or break, and does not come into contact with the metal holding frame 2 or the like to cause a short circuit. And so on.

FIG. 6 shows a second embodiment of the liquid crystal display device of the present invention. It has substantially the same configuration as the first embodiment described with reference to FIGS. 1 to 5. To clarify the differences,
A cross-sectional view is shown.

The difference from the first embodiment is that the above-mentioned adhesive member 61 is formed on both surfaces of the elastic body 6 (the surface on the liquid crystal panel 1 side and the surface on the circuit board 3 side).
Is provided.

This has the following effects.

(1) The back surface side of the film-shaped electrode connector 5 connected to the terminal portion of the liquid crystal panel 1 is made of the elastic body 6 by the adhesive member 61.
Since the back surface side of the film-shaped electrode connector 5 which is bonded to the terminal portion of the circuit board 3 is bonded to the elastic body 6 by the adhesive member 61, the liquid crystal panel 1 and the circuit board 3
And are integrated and fixed more securely, and deviations are less likely to occur.

FIG. 7 shows a third embodiment of the present invention, and only a sectional view is shown like the second embodiment (FIG. 6). The difference from the first embodiment shown in FIGS. 1 to 5 is that the adhesive member 61 is arranged on the surface of the elastic body 6 on the circuit board 3 side, as is clear from the drawings. .

This has the following effects.

(1) It is easy to position the liquid crystal panel 1 with respect to the circuit board 3 by adhering the elastic body 6 to the back surface side of the film-shaped electrode connector 5 connected to the circuit board 3 with the adhesive member 61 in advance. become.

(Effects of the Invention) As described above, the present invention has the following effects.

(1) Since the elastic body presses the connection between the film electrode connector and the liquid crystal panel and the connection between the circuit board and the film electrode connector, the reliability of the connection is improved both electrically and mechanically. Particularly, since the end portion of the elastic body corresponding to at least one of the first and second connection portions is bonded to the film electrode connector by the adhesive member, the elastic body is not displaced. Therefore, the connecting portion can be reliably pressed down.

(2) Further, since the end portion of the elastic body is adhered to the film-like electrode connector, for example, when the elastic body is adhered on the circuit board side, the positioning at the time of assembling the liquid crystal panel becomes easy and the assemblability is improved. An improvement is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of a liquid crystal display device of the present invention. FIG. 2 is a cross-sectional view of essential parts of the liquid crystal display device shown in FIG. FIG. 3 is an exploded view of the liquid crystal display device shown in FIG. FIG. 4 is a diagram showing an example of a film-shaped electrode connector. FIG. 5 is a view showing another example of the film electrode connector. FIG. 6 is a diagram showing a second embodiment of the liquid crystal display device of the present invention. FIG. 7 is a diagram showing a third embodiment of the liquid crystal display device of the present invention. 1 ... Liquid crystal panel 2 ... Holding frame 3 ... Circuit board 4 ... Drive element 5 ... Film-shaped electrode connector 6 ... Elastic body 61 ... Adhesive member

Front page continued (72) Inventor Shimada Yone Toshihiro, Shiojiri-shi, Nagano 80, Hirookahara Shinden Shinshu Seiki Co., Ltd. (56) Reference JP-A-54-79061 (JP, A) (JP, U)

Claims (1)

[Claims] 1. A liquid crystal display device comprising a liquid crystal panel, a circuit board on which a drive element for driving the liquid crystal panel is arranged, and a holding frame for fixing the liquid crystal panel to the circuit board. The liquid crystal panel and the circuit board are electrically connected using a film-like electrode connector based on a plastic film, and the film-like electrode connector and the liquid crystal are provided on one side between the liquid crystal panel and the circuit board. Connection of at least one of the first and second connection parts, pressing the first connection part with the panel and pressing the second connection part with the film electrode connector and the circuit board on the other side. A liquid crystal display device, in which an elastic body having an end portion corresponding to the portion is adhered to the film-shaped electrode connector with an adhesive member is arranged.