JPH06131944A - Membrane switch - Google Patents

Abstract

PURPOSE:To improve productivity by allowing a signal sending/receiving connector to ensure and facilitate the connection between two membrane sheets of mono-tailed membrane switch for a keyboard. CONSTITUTION:A membrane switch is provided with the second sheet formed with electrodes connected in the Y direction and arranged with leads connected to electrode lines in a blank space as a connecting area and the first sheet formed with electrodes connected in the X direction and leads starting from the positions corresponding to the leads of the second sheet 31 in the connecting area together with a junction to a connector, the electrodes are faced to each other via an insulating sheet 23 having electrode holes and a connecting area hole and the thickness of about 100mum, and the second and first leads are excited by an anisotropic conducting adhesive 24 in the connecting area. The connecting area 22b' of the second sheet 31 is protruded to the electrode forming face side by the difference between the thickness of the insulating sheet 23 and the film thickness of the anisotropic conducting adhesive 24 when it is dried.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a membrane switch used for a thin keyboard for inputting information, and more particularly to a so-called "1" in which only one signal transmitting / receiving connector is connected to the membrane switch. The present invention relates to a membrane switch that ensures and facilitates connection between two membrane sheets in a "tailed membrane switch" to improve productivity.

[0002]

2. Description of the Related Art FIG. 3 is a diagram schematically illustrating a membrane switch as a technical background, FIG. 4 is a diagram illustrating a conventional membrane switch, and FIG. 5 is a diagram illustrating a problem.

The membrane switch 1 located inside the keyboard casing (not shown in FIG. 3) has, for example, a thickness of 100 μm.
A polyester resin sheet of about m has a diameter of 5 mm at each position corresponding to each key top placement position of the keyboard housing on one side.
Of the first membrane sheet (hereinafter simply referred to as the first sheet) 11 in which the circular electrodes 11a of the same position are connected to each other in the X direction in the drawing correspond to the respective electrode 11a arrangement positions on one surface of the same resin sheet. A second membrane sheet (hereinafter simply referred to as a second sheet) 12 in which circular electrodes 12a, which are the same as the above electrodes, are formed in patterns at a position connected to each other in the Y direction in the drawing, and each of the electrodes corresponding to each electrode. The insulating sheet 13 is made of the same material and has circular holes 13a of approximately the same size as the respective electrodes.

The above-mentioned membrane sheets 11 and 12 are
Each electrode alignment direction, that is, X in the first sheet 11
In the second sheet 12, the information input / output connectors 14 _-1 , 14 _-2 connected to the respective electrode rows can be attached to one side edge in the Y direction.

Therefore, the first and second sheets 11 and 12 are bonded and integrated through the insulating sheet 13 so that the circular electrodes 11a and 12a face each other correspondingly, whereby the membrane switch 1 shown in FIG. It is designed to be composed.

Reference numeral 15 shown by a broken line is a panel for holding and fixing the membrane switch 1 in a plane, and 16 is an insulating plate for insulating the membrane switch 1 from the panel 15. In such a membrane switch 1, by depressing or releasing a key top mounted on a keyboard casing (not shown), the electrode 11a on the first sheet 11 and the second sheet 12 corresponding to the operation key top are placed. Since the connection with the electrode 12a is made or the connection is released, the cable 14 _-1 ', 14 which connects the ON-OFF signal for each keytop via each connector 14 _-1 , 14 _-2 to each connector It can be delivered to the control unit via _-2 ', and can function as a membrane switch.

In particular, the thickness of the insulating sheet 13 in this case
Approx. 100 μm is a reliable ON-OFF signal for a long time.
It is set from the standpoint of ensuring the operation and tactile feel. Only
However, in the above-mentioned membrane switch 1, they are arranged orthogonally.
2 connectors 14 _-1,14_-2Because you are using
It takes assembly man-hours and parts cost to configure it as a card
It may not be possible to meet the customer's request for price reduction
Space must be provided for each connector
Therefore, it cannot meet the demand for miniaturization as a keyboard.
Sometimes.

FIG. 4 shows a conventional example as a membrane switch that has been put into practical use in order to meet such customer requirements. However, in order to make it easier to understand in the figure, only the membrane switch portion in FIG. 3 is extracted. The same target members and parts as those in FIG. 3 are denoted by the same symbols.

In the figure, (4-1) shows the configuration and (4-2) shows the assembly process as a switch in stages.
(4-2) is a cross section of (4-1) taken along arrows a to a '.

The membrane switch 2 in (4-1) of FIG.
A first sheet on which a circular electrode 21a having a diameter of about 5 mm is formed in a pattern on one surface of a polyester resin sheet having a thickness of 100 μm at each predetermined position described in FIG.
21 and a second sheet 22 in which circular electrodes 22a similar to the above are pattern-formed at respective positions corresponding to the electrodes 21a on one surface of the same resin sheet, and the same material as in FIG. It is composed of an insulating sheet 23.

In the second sheet 22 in this case, a plurality of leads 22b (two in the figure) connected to the respective electrode rows are collected in a blank portion (outer area in the figure) of each circular electrode 22a arrangement area. It is formed as an open connection area 22b '.

Further, in this case, the first sheet 21 is started at a position where each lead 22b can be connected to an area corresponding to each connection area 22b 'of the second sheet 22 in the marginal area of each circular electrode 21a. lead 21b that is routed to the end side for mounting the connector 14 _-1 described in FIG 3 is formed as a.

Further, like the insulating sheet 13 shown in FIG.
In this case, in the insulating sheet 23 in which a is formed, holes 23a having substantially the same size as the connection area 22b 'are formed at respective positions corresponding to the connection area 22b' of the second sheet 22.

Therefore, when the first sheet 21 and the second sheet 22 are bonded and integrated with each other via the insulating sheet 23, the leads 21b of the first and second sheets 21, 22 are formed in the area of the hole 23a of the insulating sheet 23. The ends of 22b face each other.

Therefore, after the insulating sheet 23 is positioned and adhered and fixed to the electrode forming surface side of the first sheet 21, the
In the area of each hole 23a of the insulating sheet 23 where the tip area of the lead 21b of the sheet 21 is exposed, a viscous anisotropic conductive adhesive 24
(Product name: DOTITE FH-889 "Fujikura Kasei Co., Ltd.") is applied by a normal screen printing technique to a thickness such that the film thickness when dried is 20 to 30 μm. )
The state becomes as shown in.

In this case, the anisotropic conductive adhesive 24 is
When the electrodes are brought into contact with both surfaces in a dried state and thermocompression-bonded at a predetermined temperature and pressure, the conductive property between the electrodes can be obtained only in a region where the electrodes face each other.

Then, the anisotropic conductive adhesive 24 is dried and
After making the thickness of 20 to 30 μm, the second sheet 22 is positioned, adhered and fixed to be integrated, and then the hole 23 of the insulating sheet 23 is formed.
When the connection area 22b 'of the second sheet 22 corresponding to a is thermocompression-bonded as shown in (2), an amount corresponding to the difference between the thickness of the insulating sheet 23 and the thickness of the anisotropic conductive adhesive 24 is applied. 2 sheets 22
The lead 21b of the first sheet 21 and the lead 22b of the second sheet 22 can be electrically connected to each other in the state (3) in which the connection area 22b 'of FIG.

This means that the leads 22b connected to the respective electrodes of the second sheet 22 are routed around the connector _14-1 mounting edge of the first sheet 21. Therefore, the connector 25 having more connection terminals than the connector 14 _-1 described in FIG.
Is attached to the first sheet 21 as indicated by a broken line B, so that the one-tailed membrane switch 2 capable of transmitting and receiving all signals by one connector can be constructed.

Since the membrane switch 2 does not need to be provided with two orthogonal connectors, it has a merit that it can be constructed at a lower cost than the conventional one and that the size of the keyboard can be reduced.

[0020]

However, in the membrane switch in this case, the thickness of the insulating sheet 23 (about 100 μm)
And the thickness (20 to 30 μm) of the anisotropic conductive adhesive 24 causes a recess in the connection area 22b ′ of the second sheet 22, that is, the electrode conduction area.

FIG. 5 is an enlarged view of this electrode conduction region.
Here, (a) shows the state during and immediately after the thermocompression bonding, (b) illustrates the state after the thermocompression bonding, and (c) illustrates the state after left for a long time. It is a thing.

That is, in (a), the lead 21b of the first sheet 21 and the lead 22b of the second sheet 22 are completely connected to each other through the anisotropic conductive adhesive 24. After the release, when the restoring property of the second sheet 22 exceeds the adhesive force of the anisotropic conductive adhesive material 24, the adhesion between the leads 21b, 22b and the anisotropic conductive adhesive material 24 becomes (b). As shown in (c), it gradually weakens, and after being left for a long time, as shown in (c), the adhesiveness in the region is lost, and the connection characteristics between the leads 21b and 22b may be deteriorated or conduction may be lost.

Therefore, in the conventional membrane switch, the second sheet is partially deformed to establish electrical connection with the first sheet, so that stable electrical connection between the two cannot be secured for a long period of time. There was a problem that there was something.

[0024]

SUMMARY OF THE INVENTION The above-mentioned problem is that electrodes corresponding to a plurality of key tops arranged in a line on a keyboard housing are formed in a pattern on one surface of a resin sheet in the Y direction and are connected to the respective electrode rows. A second membrane sheet in which leads are patterned as connection areas aligned in the margin of the electrode arrangement area, electrodes connected to the X direction located corresponding to the electrodes on one surface of the resin sheet, and the connection area in the connection area. The first membrane sheet, in which the leads starting from the position corresponding to the leads of the second membrane sheet are both patterned including the connecting portion to the connector, and the first membrane sheet is provided at the positions corresponding to the respective electrodes. A hole having substantially the same size as the electrode is formed, and a hole having substantially the same size as the connection area is formed at a position corresponding to the connection area of the second membrane sheet. Through 100μm approximately insulation sheet is second in also the connection region so as to face each of the above electrodes
And the first lead is adhered and fixed so as to be electrically conductive with an anisotropic conductive adhesive, and the connection area of the second membrane sheet is the thickness of the insulating sheet and the anisotropic conductive adhesive. This is achieved by a membrane switch that is provided with means capable of projecting or displacing toward the electrode formation surface side by an amount equal to the difference with the dry film thickness of the adhesive material.

[0025]

When the connection area of the second sheet is formed in a shape that facilitates connection to the first sheet, the resilience of the second sheet in the connection area can be eliminated or reduced so that stable conduction is achieved. It can be maintained and secured for a long time.

Therefore, in the present invention, the connection area of the second sheet is preliminarily deformed or formed so as to be easily deformed to form the membrane switch. Therefore, the adhesive strength as the anisotropic conductive adhesive can be secured for a long period of time, and a membrane switch that can maintain stable conduction characteristics can be realized.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining an example of the structure of a membrane switch according to the present invention. Like FIG. 4, (1-1) shows the structure and (1-2) shows the assembly process as a switch. 4 is a cross section taken along the same arrows a to a '.

FIG. 2 is a diagram showing another configuration example.
Note that, since all of the examples are the case of the membrane switch having the same configuration as that in FIG. 4, the same target members and parts as those in FIG. 4 are denoted by the same reference numerals and the duplicate description will be omitted. .

The membrane switch 3 in (1-1) of FIG.
It is composed of the first sheet 21 described in FIG. 4, the second sheet 31 made of the same resin sheet, and the insulating sheet 23 of FIG.

In particular, the second sheet 31 in this case is
Only the connection area 22b 'of the second sheet 22 described in FIG. 4 is formed in the embossed molding area 31a projecting to the electrode forming surface side as shown in the extracted sectional view (a).

The amount of protrusion δ of the embossed molding region 31a is determined by the thickness of the insulating sheet 23 and the anisotropic conductive adhesive described with reference to FIG.
It corresponds to the difference from the thickness of 24 (80 to 70 μm in the case of the figure).

Then, as in the case of FIG. 4, the first sheet 21
After the insulating sheet 23 is positioned and adhered and fixed to the electrode forming surface side of the above, the above-mentioned viscous anisotropic conductive adhesive 24 is applied to the area of each hole 23a of the insulating sheet 23 as described in FIG. If the second sheet 31 is placed on top of it, (1-
It can be in the state shown in (1) of 2).

Next, the anisotropic conductive adhesive material 24 is dried to have the above-mentioned thickness, that is, 20 to 30 μm, and then the second sheet 31 is positioned and adhered and fixed, so that the embossed molding area 31a of the second sheet 31 is formed. By thermocompression bonding to the first sheet side
As shown in (2), the leads 21b of the first sheet 21 and the leads 22b of the second sheet 31 can be electrically connected to each other via the anisotropic conductive adhesive 24 as in FIG.

In the membrane switch 3, when the second sheet 31 is adhered to the first sheet 21 via the insulating sheet 23, the embossed molding area 31a of the second sheet 31 is anisotropic on the leads 21b of the first sheet 21. Since the conductive adhesive 24 is brought into contact with the conductive conductive adhesive 24, stable connection can be maintained without deterioration in connection characteristics between the two even after they are electrically connected by thermocompression bonding.

2 (2-1) showing another configuration example, the membrane switch 4 includes a first sheet 21 of FIG. 4, a second sheet 41 made of the same resin sheet, and an insulating sheet 23 of FIG. It consists of

In particular, in this case, the second sheet 41 has only the connection area 22b 'of the second sheet 22 described in FIG. 4, and the tips of the leads 22b are U-shaped as shown in the enlarged view (b). The slit 41a is formed on the tongue piece 41b.

Therefore, the tongue piece 41b can be easily displaced in the thickness direction by pressing the free end thereof. Therefore, as in the case of FIG. 4, after the insulating sheet 23 is positioned and adhered and fixed to the electrode forming surface side of the first sheet 21, the above-mentioned viscous anisotropy is applied to the area of each hole 23a of the insulating sheet 23. When the conductive adhesive 24 is applied as described with reference to FIG. 4 and the second sheet 41 is arranged on the conductive adhesive 24, the state shown in (1) of (2-2) can be obtained.

Next, the anisotropic conductive adhesive material 24 is dried to the above thickness, and then the second sheet 41 is positioned and adhesively fixed, and the tongue piece 41b of the second sheet 41 is attached to the first sheet side. As shown in (2), the leads 21b of the first sheet 21 and the leads 22b of the second sheet 41 are electrically connected to each other through the anisotropic conductive adhesive material 24 as in FIG. You can

In this membrane switch 4, the lead 22b located on the tongue piece 41b of the second sheet 41 has the insulating sheet 23.
Through the anisotropic conductive adhesive 24 located in the hole 23a of the
Since it is electrically connected to the leads 21b of the sheet 21, the connection characteristics between the two are not deteriorated even after being left for a long time, and stable connection can be maintained as in the case of FIG.

[0040]

As described above, according to the present invention, the connection between the two membrane sheets in the one-tailed membrane switch in which only one signal transmitting / receiving connector connected to the membrane switch is constituted is ensured and facilitated. It is possible to provide a membrane switch with improved productivity.

In the description of the present invention, the case where the lead in the connecting area of each membrane sheet is composed of two is taken as an example, but the number is changed in consideration of the size and position of each margin area. It is clear that the same effect can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a configuration example of a membrane switch according to the present invention.

FIG. 2 is a diagram showing another configuration example.

FIG. 3 is a diagram schematically illustrating a membrane switch as a technical background.

FIG. 4 is a diagram illustrating a conventional membrane switch.

FIG. 5 is a diagram illustrating a problem.

[Explanation of symbols]

 21 First membrane sheet 21b, 22b Lead 22,31,41 Second membrane sheet 22b 'Connection area 23 Insulation sheet 23a Hole 24 Anisotropic conductive adhesive 31a Embossing molding (area) 41a U-shaped slit 41b Tongue piece

Claims (3)

[Claims] 1. An electrode corresponding to a plurality of key tops arranged in alignment on a keyboard casing is patterned on one surface of a resin sheet in the Y direction, and leads connected to each of the electrode rows have margins in the electrode arrangement area. A second membrane sheet that is patterned as a connection area aligned with the area,
The electrode connected to the X direction on one side of the resin sheet and connected to the X direction, and the lead starting from the position corresponding to the lead of the second membrane sheet in the connection area together include the connection portion to the connector. The first membrane sheet having a pattern is formed, and holes having substantially the same size as the respective electrodes are formed at positions corresponding to the respective electrodes, and at positions corresponding to the connection area of the second membrane sheet. 100 μm thickness with holes of approximately the same size as the connection area
A membrane switch in which the above-mentioned electrodes are faced to each other through an insulating sheet of a certain degree and the second and first leads are electrically connected by an anisotropic conductive adhesive in the above-mentioned connection area. The connection area (22b ′) of the second membrane sheet (31)
Is provided with a means capable of protruding or displacing toward the electrode formation surface by an amount equal to the difference between the thickness of the insulating sheet (23) and the film thickness of the anisotropic conductive adhesive (24) when dried. Membrane switch featuring. 2. The second membrane sheet connection area (22b ′) according to claim 1, wherein the projection to the electrode formation surface side is the connection area (2b).
Membrane switch characterized by being embossed (31a) in 2b '). 3. Means capable of displacing the second membrane sheet connection region (22b ′) to the electrode formation surface side according to claim 1,
A membrane switch comprising a tongue piece (41b) formed by a U-shaped slit (41a) surrounding the tip of each lead in the connection area (22b ') in a U-shape.