JP2001067980A - Membrane switch and on-load detector using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a degree of freedom in arrangement of contact portions and provide a compact form as a whole. SOLUTION: An upper side conductive pattern 5 has a first land formed of a high-resistance spiral pattern spirally extending from the center to the outside and a lower side conductive pattern 6 has a second land formed of a spiral pattern similar to that of the first land. As the area of contact of the first land with the second land 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 continuously by detecting the resistance value for the contact portion 7, permitting electrical correction.

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. 8 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. 9, one contact part group 110 is configured by combining a plurality of contact parts 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 contact portion is formed as a conductive pattern on one of the flexible sheets, a first land formed by a helical pattern of resistors extending helically outward from a center thereof, and a first land corresponding to the first land. A second land that is formed as a conductive pattern on the flexible sheet side and is in contact with the first land at the time of switch-on, and according to a contact area between the first land and the second land at the time of switch-on. The resistance value of the contact portion changes.

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, since the first land forming the contact portion is formed by the spiral pattern made of the resistor, the contact area between the first land and the second land is changed according to the on-load. As the resistance gradually increases from the center, the resistance value of the entire contact portion decreases correspondingly, and it becomes possible to detect the on-load by the change in the resistance value. 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 stable because only the paste of the resistor is used for the first land. I have. Further, since the ON load can be continuously measured with one contact portion, the size of the switch itself does not increase. Also, electrical correction is easy.

Preferably, the second land has a spiral pattern compatible with the spiral pattern of the first land in order to increase the resistance change due to, for example, an on-load. Further, the first lands are made of, for example, a pair of spiral patterns which are insulated from each other and arranged adjacent to each other,
The second land may be an isolated pattern that short-circuits a pair of spiral patterns of the first land.

[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. 2 (a) shows the upper conductive pattern 5, and FIG. 2 (b) shows the lower conductive pattern 6, respectively. As shown in FIG. 2A, the upper conductive pattern 5 includes a first land 11 formed of a spiral pattern extending spirally from the center to the outside, and a first land 11 connected to the outer periphery of the first land 11. It is composed of one lead 12. The lower conductive pattern 6 has a second land 13 formed in the same pattern as the first land 11 and a second land 13 connected to the outer periphery of the second land 13 as shown in FIG. And two leads 14. The first land 11 and the second land 13 are formed of a carbon paste prepared to have a high resistance, for example, a resistance of 100 to 100 KΩ / cm ^{2 with} a thickness of 10 μm. The first lead 12 and the second lead 14 connected thereto are formed by superposing a silver paste on the carbon paste described above so as to have a lower resistance value than the first land 11 and the second land 13. It is.

When the membrane switch 1 has such a configuration, when the on-load is small, only the center portions of the first land 11 and the second land 13 are in contact with each other. The first land 1
The distance between the high resistance regions of the first and second lands 13 becomes longer.
Therefore, as shown in FIG. 3A, the resistance value R1 shows a large value. On the other hand, when the on-load increases and the contact area between the first land 11 and the second land 13 increases,
Since the distance from the lead 12 to the second lead 14 between the first land 11 and the second land 13 in the high-resistance region becomes shorter, the resistance value R2 becomes small 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. The first lead 12 of the conductive pattern 5 of the membrane switch 1
For example, it is connected to a power supply (+ V), and the second lead 14 is led to the current detector 21. The current detector 21 detects the resistance value of each contact 7 by detecting each of the current values flowing through the plurality of contacts 7. Thereby, the on-load at each contact portion 7 can be detected.

In the above embodiment, the second land 13 has a high resistance spiral pattern similarly to the first land 11 in order to obtain a large resistance change due to the on-load. However, as shown in FIG. The second land 31 may be a circular solid pattern. In addition, the second lands 13 and 31
It may be formed of carbon paste or silver paste.

FIG. 6 is a view showing conductive patterns 5 and 6 according to still another embodiment of the present invention. In this embodiment, the first land 41 is constituted by a pair of spiral patterns 42 and 43 coaxially and spirally extending outward from the center, which are insulated and separated from each other. The first lead 44 and the second lead 45 are connected. Further, the second land 46 is an isolated pattern that conforms to the spiral patterns 42 and 43 of the first land 41 but is joined at its outer periphery.

Also in this embodiment, the first land 41 is formed by a high resistance pattern, and the second land 46 is formed by a high resistance pattern or a low resistance pattern. According to this embodiment, in addition to the above-described on-load detection function, since the second land 46 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. Further, as shown by a dotted line in FIG. 6, there is an advantage that the disconnection self-diagnosis resistor 47 can be easily attached. In this embodiment, a circular solid pattern 51 as shown in FIG. 7 can be used as the second land.

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.

[0019]

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 a conductive pattern 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 partially cutaway perspective view showing a conventional membrane switch.

FIG. 9 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, 10
4, 105... Conductive pattern, 7, 107, 111 to 11
3 contact point, 8, 106 opening, 11, 41 first land, 12, 44 first lead, 13, 31, 46, 5
1 ... second land, 14, 45 ... second lead.

Continuation of the front page (72) Inventor Toshio Ochiai 1440 Mutsuzaki, Sakura-shi, Chiba F-term in Fujikura Sakura Works (reference) 5G006 AA01 AA07 FB14 FB36 FB37

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 in the membrane switch, and when a load in the thickness direction of the flexible sheet is applied to the contact portion, the opposing conductive pattern contacts at the opening position. Are formed as a conductive pattern on one of the flexible sheets, and formed by a spiral pattern of resistors extending spirally outward from the center of the first land, and the other land corresponding to the first land is formed. A second land which is formed as a conductive pattern on the conductive sheet side and comes into contact with the first land at the time of switch-on, and the first land at the time of switch-on; Serial membrane switch, wherein the resistance value of the contact portion is changed in accordance with the contact area between the second land. 2. The membrane switch according to claim 1, wherein the second land is formed of a spiral pattern that matches a spiral pattern of the first land. 3. The first land includes a pair of spiral patterns that are insulated from each other and are adjacently arranged. The second land is an isolated pattern that short-circuits the pair of spiral patterns of the first land. 2. The membrane switch according to claim 1, wherein: 4. The membrane switch according to claim 1, further comprising: a resistance value detecting unit configured to detect a resistance value of the contact part of the membrane switch as an on-load applied to the contact part. An on-load detection device, comprising: