JPH09139151A - Membrane switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resistance type membrane switch which has multifunctions and a high density by disposing each resistance element in each contact part formed of a through-hole region perforated in the respective opposed parts of a fixed contact in an insulating spacer and a movable contact. SOLUTION: On a first insulating sheet 7, each fixed contact 2 in a plurality of keys, a resistance element 6 and a first wiring layer 4 are formed by patterning, and each fixed contact 2 is connected to the first wiring layer 4 in the direction of a line through the resistance element 6. Also, on the surface opposite to the first insulating sheet 7 in a second insulating sheet 8, a plurality of movable contacts 3 and a second wiring layer 5 for connecting the movable contacts 3 in the direction of a column are formed by patterning. Further, in an insulating spacer 9 interposed between the first and the second insulating sheets 7, 8, a round through-hole 10 making a contact part is perforated in the respective opposed parts of the fixed contact 2 and the movable contact 3. The insulating spacer 9 is held between the insulating sheets 7, 8 and each resistance element 6 is disposed in each round through-hole 10, thereby being able to obtain a resistance type membrane switch which can be much more miniaturized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance type membrane switch in which a resistance element prevents an electric signal from wrapping around.

[0002]

2. Description of the Related Art A plurality of switches (hereinafter referred to as keys)
In a full keyboard membrane switch (membrane switch for PC) etc. arranged in a matrix, innumerable software is often used, so if multiple keys are pressed at the same time, a false input may occur due to the wraparound of electrical signals. .

The wraparound of the electric signal will be described with reference to the basic circuit diagram of the composite switch (keyboard) shown in FIG.
In the figure (a), 1a, 1b, 1c, 1d, ... Are a plurality of keys arranged in a matrix, and 4a, 4b, ... Are the fixed contacts of the plurality of keys 1a, 1b, 1c, 1d ,. First wirings connected in the row direction (hereinafter, the same reference numerals 4a, 4b, ... Are used when referring to the first wiring layer),
5a, 5b, ... are a plurality of keys 1a, 1b, 1c, 1
Second wiring for connecting the movable contacts in d, ... In the column direction (hereinafter also referred to as a second wiring layer, the same reference numerals 5a, 5
b) is used), and as shown in FIG. 2B, when three keys 1a, 1b, 1c are pressed at the same time, the wirings 4b-5b are connected to each other, as if the key 1
A sneak signal current flows when d is pressed.

FIG. 6 shows a diode type composite switch for preventing such an electric signal from sneaking in. In this composite switch, a plurality of keys 1a, 1
Between the movable contacts of b, 1c, 1d, ... And the second wirings 5a, 5b ,.
5b, 15c, 15d, ... Are connected. Similarly to the above, when the three keys 1a, 1b, 1c are pressed at the same time, the sneak signal current is blocked by the reverse connection of the diode 15a, and between the wirings 4b and 5b, the key 1d that directly connects the keys is pressed. Conduct only by. In the diode type composite switch, the electric signal sneak prevention is completed only by the circuit configuration of FIG. 6, but mounting a plurality of diodes increases the cost.

FIGS. 7 to 9 show a resistance type sheet-shaped composite switch (membrane switch) capable of preventing sneaking of an electric signal at a lower cost than a diode type (Japanese Patent Publication No. 4-47934). Gazette). 7 is a circuit diagram, FIG. 8 is a plan view showing a resistive element pattern, and FIG. 9 is a sectional view of a key portion. As shown in FIG. 7, in this sheet-shaped composite switch, a plurality of keys 1a, 1b, 1c, 1
Resistance elements 16a, 16b, 16c, 16d, ... Are respectively connected between each fixed contact (or movable contact) in d, ... And each first wiring 4a, 4b, ... (Or each second wiring). ing. Then, as above, the three keys 1
When a, 1b and 1c are pressed at the same time, the sneak signal current flows through the electric path in which the three resistance elements 16a, 16b and 16c are connected in series, whereas when only the key 1d is pressed, the electric path is 1 Only the individual resistance elements 16d have resistance.
An external circuit detects the signal level difference due to the difference in the resistance value by hardware or software to prevent the electric signal from wrapping around.

Since the resistance element 16 generally has a high resistance of about 5 to 20 kΩ, a carbon-based material is mainly used, and a pattern is formed by screen printing as shown in FIGS. 8 (a) and 8 (b). There is. In FIGS. 8A and 8B, 2 is a fixed contact, 10 is a contact portion described in FIG. 9 below, and 4 is a first wiring layer. In the case of the zigzag resistance element pattern of FIG. 4A, the size of the entire pattern is 5 ×
The resistance element pattern having a size of about 7 mm is arranged at about 80 to 90 places in the membrane switch having a size of about 300 × 100 mm.

In FIG. 9, 7 is a plurality of fixed contacts 2, a resistance element 16 and a first insulating layer of polyester on which the first wiring layer 4 is patterned, and 8 is a plurality of movable contacts 3.
And a second insulating sheet of polyester in which the second wiring layer is patterned, 9 is the first and second insulating sheets 7 and 8
It is an insulating spacer made of polyester sandwiched in between, and circular through holes 10 are formed in each facing portion of the fixed contact 2 and the movable contact 3. A contact portion of each key is formed by the circular through hole 10 region (hereinafter, the same reference numeral 10 as that of the circular through hole is used when the contact portion is called). Each resistance element 16 is formed on the region of the first insulating sheet 7 other than the contact portion 10.

[0008]

By the way, recently, the number of contacts and the number of wirings of the membrane switch has increased with the increase in the number of functions, and the density of the membrane switch tends to be higher.

However, in the conventional resistance type membrane switch, for example, a resistance element having a size of about 5 × 7 mm is provided on the first insulating sheet area other than the contact portion in the membrane switch having a size of about 300 × 100 mm. 80 to
Since about 90 places were arranged, the ratio of the area occupied by all resistance element patterns to one membrane switch was 1
It is 0 to 20%. For this reason, it is difficult to increase the number of high-density wirings and the number of contacts, and it is difficult to cope with multi-functionality and it is difficult to reduce the size.

The present invention has been made in view of the above,
An object of the present invention is to provide a membrane switch capable of increasing the degree of freedom in design, further increasing the number of high-density wiring and the number of contacts, being able to better cope with multi-functionalization and achieving further miniaturization. And

[0011]

In order to solve the above-mentioned problems, according to the present invention, each fixed contact in a plurality of keys arranged in a matrix and these fixed contacts are connected in either row or column direction. A first insulating sheet on which a plurality of first wiring layers are patterned, a plurality of movable contacts in the plurality of keys and a plurality of second movable contacts connected in the row or column in the other direction. A second insulating sheet in which a wiring layer is patterned, and an insulating spacer which is arranged between the first and second insulating sheets and has a through hole formed in each facing portion of the fixed contact and the movable contact, In a membrane switch in which a resistance element is connected to at least one of the fixed contact and the first wiring layer or between the movable contact and the second wiring layer, each resistance element is formed in the through hole region. Placed inside each contact It made it to the gist. With this configuration, the degree of freedom in design is increased, the high-density wiring and the number of contacts can be further increased, and it is possible to better cope with multi-functionalization and further downsizing.

[0012]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIGS. The membrane switch according to the present embodiment has a circuit configuration substantially similar to that shown in FIG. In addition, in FIG. 1 to FIG.
The same or equivalent members and parts as those in FIG.

In FIG. 1, on the first insulating sheet 7 made of polyester or the like, each fixed contact 2 in a plurality of keys,
The resistance element 6 and the first wiring layer 4 are patterned. Each fixed contact 2 is connected in the row direction to the first wiring layer 4 via a resistance element 6. In addition, the first insulating sheet 7 in the second insulating sheet 8 such as polyester
A plurality of movable contacts 3 and a second wiring layer 5 to which these movable contacts 3 are connected in the column direction are pattern-formed on the surface facing to. Reference numeral 9 denotes an insulating spacer made of polyester or the like sandwiched between the first and second insulating sheets 7 and 8, and circular through holes 10 serving as contact portions are formed at the facing portions of the fixed contact 2 and the movable contact 3. ing.

In this embodiment, (a) and (b) of FIG. 2 are used.
As shown in FIG. 3 and FIG.
2a, and is patterned as shown by 6a and 6b in FIGS. 2 (a) and 2 (b). The resistance element 6 is formed by printing using carbon paste, and its resistance value is defined by such a pattern shape, width, and thickness.

Since each resistance element 6 is arranged in the contact portion 10, it is not necessary to coat the resistance element pattern with resist (insulating ink) or the like. When a resist is coated on the resistive element pattern, the solvent of the resist affects the carbon paste of the resistive element material,
There is a risk that the resistance value will increase and the variation between manufacturing lots will increase. However, in the present embodiment, there is no need to coat the resist as described above, so there is no fear of this.

When the resistance element 6 is arranged in the contact portion 10, the resistance element pattern may be worn away as the key is pressed, but in contrast to this, as shown in FIG.
As shown in FIG. 7, if the key top 11 made of rubber or the like is provided, or if the key top 11 is pushed down via an actuator or the like, only the contact points 2 and 3 are keyed, so that the resistance element pattern can be prevented from being worn. .

As described above, according to the present embodiment,
In the above-mentioned one membrane switch, since the area ratio 10 to 20% occupied by all the resistance element patterns is absorbed in the contact portion 10, the degree of freedom in design is increased, and high-density wiring and contact outside the contact portion 10 are increased. It is possible to further increase the number of points, better support multi-functionality, and further downsize.

[0018]

As described above, according to the present invention,
In the resistance type membrane switch, each resistance element is arranged in each contact part formed by the through hole area opened in each facing part of the fixed contact and the movable contact in the insulating spacer, increasing the degree of freedom in design. Therefore, it is possible to further increase the number of high-density wirings and the number of contacts, and it is possible to better cope with the increase in the number of functions and further reduce the size.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a membrane switch according to the present invention.

FIG. 2 is a plan view showing a pattern example of a resistance element in the above embodiment.

FIG. 3 is a side sectional view of a key portion in the above embodiment.

FIG. 4 is a side sectional view showing a configuration example when a key top is provided in the above embodiment.

FIG. 5 is a diagram showing a basic circuit of a conventional composite switch.

FIG. 6 is a circuit diagram of a conventional diode-type composite switch.

FIG. 7 is a circuit diagram of a conventional resistance type membrane switch.

FIG. 8 is a plan view showing a resistance element pattern in the conventional resistance type membrane switch.

FIG. 9 is a side sectional view of a key portion in the conventional resistance type membrane switch.

[Explanation of symbols]

 1a, 1b, 1c, 1d, ... Key 2 Fixed contact 3 Moving contact 4 First wiring layer 5 Second wiring layer 6 Resistive element 7 First insulating sheet 8 Second insulating sheet 9 Insulating spacer 10 Contact part ( Circular through hole)

Claims (1)

[Claims] 1. A first insulation in which fixed contacts of a plurality of keys arranged in a matrix and a plurality of first wiring layers in which these fixed contacts are connected in one of a row direction and a column direction are patterned. A sheet, a second insulating sheet on which each movable contact in the plurality of keys and a plurality of second wiring layers in which these movable contacts are connected in either row or column in the other direction are patterned, 1. An insulating spacer which is provided between the first and second insulating sheets and has a through hole formed in each of the facing portions of the fixed contact and the movable contact, and the fixed contact and the first wiring layer or the movable contact. A membrane switch in which a resistance element is connected to at least one of the second wiring layers, wherein each resistance element is arranged in each contact portion formed in the through hole region.