JP2001067981A - Membrane switch and on-load detector using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the degree of freedom in arrangement of contact portions and provide a compact form as a whole. SOLUTION: An opening 8 is in a gourd-shaped pattern, gradually narrower as closer to one side. Upper and lower conductive patterns 5, 6 are in a high- resistance linear pattern extending from the center along the side where the opening 8 is gradually narrower. A contact are between the conductive patterns 5, 6 is changed with the size of an on-load, a resistance value for a contact portion 7 is changed, accordingly. Therefore, the on-load of the contact portion 7 can be detected by detecting the resistance value for the contact portion 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane switch which is turned on when a conductive pattern formed on an opposing surface of a polymerized flexible sheet comes into contact with a hole formed in an insulating spacer. More particularly, the present invention relates to a membrane switch having an on-load measuring function suitable for detecting a seating state by being installed in a seat of an automobile or an aircraft, and an on-load detecting device using the same.

[0002]

2. Description of the Related Art Conventionally, this kind of membrane switch has been applied not only to various information devices and home electric appliances, but also to seat sensors of automobiles and the like. FIG. 9 is a diagram illustrating a configuration of a general membrane switch. The membrane switch is configured by stacking a pair of flexible sheets 101 and 102 via an insulating spacer 103. Conductive patterns 104 and 105 are formed on the opposing surfaces of the flexible sheets 101 and 102, respectively. Insulation spacer 103
An opening 106 is formed at a predetermined position, and the conductive patterns 104 and 105 above and below the opening 106 are
07 is formed. The flexible sheet 101,
When a load in the thickness direction of 102 is applied, the conductive patterns 104 and 105 come into contact with each other through the opening 106, and the presence or absence of seating can be determined by detecting the current flowing through this contact. Here, the load applied to the contact portion when the contact portion 107 is turned on by the load in the thickness direction of the membrane switch is referred to as “on load”.

[0003] As a membrane switch capable of detecting the on-load, for example, a seating sensor for determining the weight of a seated person is known (Japanese Patent Laid-Open No. 10-2).
No. 14537). In this membrane switch, as shown in FIG. 10, one contact portion group 110 is configured by combining a plurality of contact portions 111, 112, and 113 having different hole diameters of the openings of the insulating spacer.

[0004] Separately, a paste-like semiconductor layer in which conductive particles are dispersed is formed between a pair of conductive patterns, and the resistance of the semiconductor layer is changed by the pressing force applied between the conductive patterns. Pressure-sensitive switches, and pressure-sensitive switches in which the resistance value changes by forming irregularities of a predetermined roughness on the surface of the conductive pattern and expanding the contact area between the two conductive patterns by pressing force are known. .

[0005]

However, among the above-mentioned conventional membrane switches, the former one is composed of a plurality of contact portions 1 having a group of contact portions 110 having different opening hole diameters.
11, 112, and 113, the switch itself tends to be large, and each of the contact portions 111 to 1
There is a problem that it is difficult to set the place where 13 is arranged.
Further, the pressure-sensitive switch in which the semiconductor layer is interposed has a problem that the material cost is high and the printability is poor. Further, in a pressure-sensitive switch in which irregularities having a predetermined roughness are formed on the surface of the conductive pattern and the contact area is increased by the pressing force to change the resistance value, the irregularities are crushed with use, and the time-dependent switch is used. There is a problem that large deterioration is large.

The present invention has been made in view of the above points, and provides a membrane switch capable of detecting an on-load which is small, inexpensive and of stable quality, and an on-load detecting device using the same. Aim.

[0007]

A membrane switch according to the present invention is formed by stacking a pair of flexible sheets via an insulating spacer, and a conductive pattern is formed on each of the opposing surfaces of the pair of flexible sheets. Is formed, and an opening for forming a contact portion is formed at a predetermined position of the insulating spacer. When a load in the thickness direction of the flexible sheet is applied to the contact portion at the contact portion, the opening faces the opening at the opening position. In the membrane switch where the conductive pattern contacts,
The opening has a shape whose width gradually decreases in a predetermined direction, and at least one of the conductive patterns on the flexible sheet side includes a pattern formed by a resistor extending along the predetermined direction. When the switch is turned on, the resistance value of the contact portion changes according to the contact area of the conductive pattern facing the opening portion.

Further, the on-load detecting device according to the present invention comprises:
The membrane switch is provided with a resistance value detecting means for detecting a resistance value of the contact portion of the membrane switch as an ON load applied to the contact portion.

According to the present invention, the opening forming the contact portion is formed so as to gradually decrease in width in a predetermined direction, and one of the conductive patterns extends along the direction in which the width of the opening decreases. Since the pattern is formed by the resistors, the contact areas of the upper and lower conductive patterns gradually increase from the center thereof in accordance with the on-load, and the resistance value of the entire contact portion decreases correspondingly. The change in the resistance value makes it possible to detect the on-load. According to the present invention, there is no need to form irregularities on the surface of the paste-like semiconductor layer or the conductive pattern, and the cost is low and the quality is low because only the paste of the resistor is used for the conductive pattern located at the opening. Is also stable. Further, since the ON load can be continuously measured with one contact portion, the size of the switch itself does not increase.

The conductive patterns facing each other at the position of the opening may be patterns compatible with each other. Also, the conductive pattern on one flexible sheet side may be a pair of patterns that are insulated from each other and adjacently arranged, and the conductive pattern on the other flexible sheet side may be an isolated pattern that short-circuits the pair of patterns. You may do it.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing a part of a membrane switch according to one embodiment of the present invention. The membrane switch 1 is configured by polymerizing a pair of flexible sheets 2 and 3 made of an insulating resin film such as a PET film via an insulating spacer 4. On the opposing surfaces of the flexible sheets 2 and 3, conductive patterns 5 and 6 made of carbon paste or the like are formed by a method such as screen printing.
An opening 8 is formed at a position corresponding to the contact portion 7 of the insulating spacer 4, and through this opening 8, the upper and lower conductive patterns 5 and 6 come into contact when a load is applied.

FIG. 2A shows the upper conductive pattern 5, and FIG. 2B shows the lower conductive pattern 6 and the opening 8, respectively. As shown in FIG. 4B, the opening 8 is formed of a uri-shaped pattern whose width gradually decreases in a specific direction, in this example, toward the left side in the figure, and the upper conductive pattern 5 is formed as shown in FIG. As shown in a), the pattern extends linearly from the center of the largest diameter portion along the leftward protruding direction. Also, the lower conductive pattern 6
Also, as shown in FIG. 3B, the upper conductive pattern 5 is formed in the same pattern. The portions 5a and 6a of the conductive patterns 5 and 6 facing the openings 8 are formed of a carbon paste having a high resistance, for example, a thickness of 10 μm and a resistivity of 100 to 100 KΩ / cm ² . The portions 5b and 6b following these are formed by superposing a silver paste on the carbon paste described above so as to have a lower resistance value than the high resistance portions 5a and 6.

When the membrane switch 1 has such a configuration, when the on-load is small, the conductive patterns 5 and
6 is in contact with only the tip portion of the low-resistance portions 5b, 6
The distance between the non-contact high-resistance portions 5a and 6a between b increases. Therefore, as shown in FIG. 3A, the resistance value R1 of the contact portion 7 shows a large value. On the other hand, when the ON load increases and the contact area of the high-resistance portions 5a, 6a increases, the non-contact high-resistance portions 5a, 6a between the low-resistance portions 5b, 6b.
Is shorter, the resistance value R2 of the contact portion 7 becomes smaller as shown in FIG. Therefore, the on-load can be detected by detecting this resistance value.

FIG. 4 is a circuit diagram showing a configuration of an on-load detecting device using the membrane switch 1. As shown in FIG. Lead 9 connected to conductive pattern 5 of membrane switch 1
a is connected to, for example, a power supply (+ V) and the conductive pattern 6
Is connected to the current detector 10. The current detector 10 detects the resistance value of each contact 7 by detecting the value of the current flowing through each of the plurality of contacts 7. Thereby, the on-load at each contact portion 7 can be detected.

In the above embodiment, the conductive patterns 5,
Although the high resistance portions 5a and 6a of FIG.
As shown in FIG. 5, when the high-resistance portion 11 is formed into a waveform pattern, the effective distance of the high-resistance portion 11 can be increased, so that more accurate on-load measurement can be performed. As the shape of the opening, as described above, in addition to the uri-shaped pattern in which the width is linearly reduced, as shown in FIG.
The opening 12 may be a uri-shaped pattern that is narrowed in a curved shape cut inward.

FIG. 7 is a view showing conductive patterns 21 and 22 according to still another embodiment of the present invention. In this embodiment, as shown in FIG. 2A, the upper conductive pattern 21 is composed of divided patterns 23 and 24 separated to the left and right in the figure, and the corresponding lower conductive pattern 22 is formed as shown in FIG. As shown in (b), an isolated pattern 25 that short-circuits the divided patterns 23 and 24 is provided. The conductive patterns 21 and 22
An annular portion 23a arranged to surround the contact portion 7,
24a, 25a and the annular portions 23a, 24a, 25
and a straight line portion 23b, 24b, 25b extending inward from a. In the upper conductive pattern 21,
Lead portions 23c and 24c connected to the annular portions 23a and 24a, respectively, are formed. Annular portion 23a,
A low resistance portion is formed by 24a and lead portions 23c and 24c. Further, as shown in FIG.
Has a rhombic pattern, and linear portions 23b, 24b, 25b are arranged to extend in the four corner directions, and the linear portions 23b, 24b, 25b form a high resistance portion. The isolated pattern 25 may be a high resistance member or a low resistance member.

Also in this embodiment, the straight portions 23b, 24b
The resistance value of the contact portion 7 changes in accordance with the contact area between the contact portion 7 and the straight portion 25b, so that the on-load can be measured. According to this embodiment, since the conductive pattern 21 is an isolated pattern, there is an advantage that only one connector processing with the wiring pattern is required and the connector processing becomes easy. There is also an advantage that disconnection self-diagnosis resistance can be easily provided. In this embodiment, a simple circular solid pattern 28 is used as the conductive pattern 27 as shown in FIG. 3C instead of the isolated pattern corresponding to the one conductive pattern 21 shown in FIG. You can also.

In addition to the combination of the annular pattern and the straight line shown in the above-described embodiment, as shown in FIG.
Are arranged side by side in parallel, and both are short-circuited, for example, in the solid pattern 28 as shown in FIG. 7 (c) or the straight portions corresponding to the linear patterns 31a and 31b, as shown in FIG. 8 (c). As shown in FIG. 8B, the conductive pattern 35 is formed by providing a flat rhombus-shaped opening 32 and separating and linearly arranging the linear patterns 33 and 34 along the longitudinal direction thereof. Then, the two patterns are converted to, for example, the solid pattern and the linear patterns 33 and 34 shown in FIG.
May be short-circuited by a rectangular pattern 42 as shown in FIG.

The membrane switch 1 described above can be widely used, for example, as a seating sensor capable of detecting the weight of an automobile, as well as switches for various information processing devices and home electric appliances.

[0020]

As described above, according to the present invention, 1
Since the on-load can be detected in a state where the first and second lands arranged in the two openings are in contact with each other, each contact portion group of the switch can be made compact.
The degree of freedom in arranging the contact portions can be increased, and the cost can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing a part of a conductive pattern of the switch.

FIG. 3 is an equivalent circuit diagram of the switch.

FIG. 4 is a circuit diagram of an on-load detecting device using the switch.

FIG. 5 is a plan view showing a membrane switch conductive pattern according to another embodiment of the present invention.

FIG. 6 is a plan view showing an opening of a membrane switch according to still another embodiment of the present invention.

FIG. 7 is a plan view showing a conductive pattern of a membrane switch according to still another embodiment of the present invention.

FIG. 8 is a plan view showing a conductive pattern of a membrane switch according to still another embodiment of the present invention.

FIG. 9 is a partially cutaway perspective view showing a conventional membrane switch.

FIG. 10 is a plan view of a conventional membrane switch including a plurality of contact portions having different on-loads.

[Explanation of symbols]

1: membrane switch, 2, 3, 101, 102: flexible sheet, 4, 103: insulating spacer, 5, 6, 2
1, 22, 27, 31, 35, 104, 105 ... conductive patterns, 7, 107, 111 to 113 ... contact portions, 8, 1
2, 26, 32, 106 ... openings.

Continuation of the front page (72) Inventor Toshio Ochiai 1440 Mutsuzaki, Sakura-shi, Chiba F-term in Fujikura Sakura Works (reference) 5G006 AA01 AZ01 FB14 FB29 FB31 FB35 FD02

Claims (4)

[Claims] 1. A pair of flexible sheets are formed by superimposing them via an insulating spacer, a conductive pattern is formed on each of the opposing surfaces of the pair of flexible sheets, and a predetermined position of the insulating spacer is provided. An opening for forming a contact portion is formed at the contact portion, and when a load in the thickness direction of the flexible sheet is applied to the contact portion, a conductive pattern opposed at the opening position contacts the membrane switch; Has a shape that gradually narrows in a predetermined direction, and at least one of the conductive patterns on the flexible sheet side is formed of a pattern of resistors extending along the predetermined direction, A membrane switch characterized in that the resistance value of the contact portion sometimes changes according to the contact area of the conductive pattern facing the opening portion. 2. The membrane switch according to claim 1, wherein the conductive patterns facing each other at the position of the opening are formed of patterns compatible with each other. 3. The conductive pattern on the one flexible sheet side is composed of a pair of patterns that are insulated from each other and are arranged adjacent to each other, and the conductive pattern on the other flexible sheet side is an isolated pattern that short-circuits the pair of patterns. The membrane switch according to claim 1, wherein the membrane switch has a target pattern. 4. The membrane switch according to claim 1, further comprising: a resistance value detecting unit configured to detect a resistance value of the contact portion of the membrane switch as an on-load applied to the contact portion. An on-load detection device, comprising: