JPH0515257U - Membrane switch - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a membrane switch that maintains mechanical strength at all times and can be easily broken only when necessary. [Structure] A wiring pattern 6a made of copper foil and a dummy pattern 14 are provided over almost the entire area of an ultrathin base film 7, and a band-shaped cutting line 15 without the dummy pattern 14 is formed. [Effect] The mechanical strength of the base film 7 having a low breaking strength is reinforced by the dummy pattern 14, but when an external force acts on the base film 7, the base film 7 is weakened.
Are easily broken along the cutting line 15.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a membrane switch, and more particularly to a membrane switch suitable for a steering wheel of a vehicle equipped with an airbag device.

[0002]

[Prior Art]

 The airbag device is intended to mitigate an occupant's frontward collision by inflating and deploying an airbag stored in a steering wheel at the time of a vehicle collision. By the way, in recent years, even a vehicle equipped with such an airbag device has been proposed in which various input switches for a car phone, an audio system, etc. are attached to the center pad of the steering wheel.

Conventionally, a general switch device of this type stores a plurality of push switches together with an airbag inside a steering wheel, and a key top group corresponding to these push switches is arranged on a center pad. When the occupant selects and pushes in each key top, the push switch corresponding to that key top is operated to switch between on and off.

[0004]

[Problems to be solved by the device]

 However, in the above-mentioned conventional technique, when the airbag is inflated and deployed, the push switch group and the key top group arranged in front of the airbag are scattered by the airbag that inflates toward the occupant, which is a safety issue. I had a problem with.

The present invention has been made in view of the circumstances of the prior art as described above, and an object thereof is to provide a membrane switch that always maintains mechanical strength and can be easily broken only when necessary. Especially.

[0006]

Means for Solving the Problems In order to achieve the above object, the present invention comprises a pair of base films having patterned electrodes, which are laminated via a spacer so that the electrodes face each other. In the membrane switch, a plurality of dummy patterns made of metal foil are formed on the base film, and a band-shaped cutting line is formed between the dummy patterns.

[0007]

[Action]

 Even if a base film having a low breaking strength, for example, an ultrathin film is used, the base film is reinforced by a dummy pattern made of metal foil provided over almost the entire area, so the mechanical strength is secured. To be done. On the other hand, for example, when the stress from the airbag acts on the base film when the airbag is inflated and deployed, the base film is easily broken along the cutting line where the dummy pattern does not exist, and the airbag passes through the broken base film. Be deployed outside.

[0008]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. 1 is a front view of a steering wheel to which a membrane switch according to an embodiment of the present invention is applied, FIG. 2 is a sectional view of the membrane switch of FIG. 1, and FIG. 3 is a lower base film provided in the membrane switch of FIG. FIG.

In FIG. 1, reference numeral 1 denotes a steering wheel, and a center portion 3 is provided in the center of the steering wheel 1 via spokes 2. The center part 3 has a concave shape with an open upper end, and accommodates a membrane switch, a folded air bag, and its detonator, which will be described later, inside. A center pad 4 is attached to the open end of the center portion 3, and a membrane switch is exposed from a plurality of openings 5 formed in the center pad 4.

As shown in FIG. 2, the membrane switch includes a lower base film 7 having a lower electrode 6, a spacer film 9 having a through hole 8, an upper base film 11 having an upper electrode 10, and a bulge. A display film 13 having a portion 12 is formed, and these films are laminated in order from the bottom and integrated by an adhesive tape or the like (not shown). The lower electrode 6 and the upper electrode 10 face each other in the through hole 8 with a predetermined gap therebetween, and the bulging portion 12 is located above these electrodes 6 and 10 and extends from the opening 5 of the center pad 4. Exposed. Therefore, when the operator (occupant) pushes in the bulging portion 12, the pressing force bends the upper base film 11 downward so that the electrodes 6 and 10 come into contact with each other and the switch is switched from off to on. When the pressing force applied to the bulging portion 12 is removed, the upper base film 11 and the display film 13 return to the state shown in FIG. 2 and the electrodes 6 and 10 are separated from each other, so that the switch is switched from on to off.

The lower base film 7 is made of an ultrathin PET (polyethylene terephthalate) film having a thickness of 75 μm, for example, and is made of a material which is easily broken by itself. As shown in FIG. 3, the lower electrode 6 and its surrounding pattern 6a are provided on the upper surface of the lower base film 7 in an arbitrary shape, and a dummy pattern 14 which does not participate in the switching of the switch is formed in almost the entire remaining area. It is provided. Both of the routing pattern 6a and the dummy pattern 14 are made of metal foil, for example, copper foil, and are patterned by a known etching technique, but the dummy pattern 14 does not exist at any position of the lower base film 7. A cutting line 15 (shown by a broken line in FIG. 3) is formed. Therefore, in the lower base film 7, the mechanical strength of the cutting line 15 traversed only by the routing pattern 6a is inferior, but the mechanical strength in almost all other regions is the same as that of the routing pattern 6a (including the lower electrode 6). It is raised by the dummy pattern 14.

Although not shown, the upper base film 11 is also configured in exactly the same manner as the lower base film 7, that is, a dummy pattern is formed on the lower surface of the upper base film 11 leaving a strip-shaped cutting line. The spacer film 9 and the display film 13 are provided over the entire area, and both are formed of a material having low breaking strength. The cutting lines 15 of the base films 7 and 11 are arranged so as to overlap each other when seen in a plan view.

In the above embodiment, when the occupant presses the bulging portion 12 exposed from the opening 5 of the center pad 4 with a finger or the like, both electrodes 6 and 10 come into contact with each other due to this pressing force, and the switch Switches from off to on. When the pressing force is removed, the electrodes 6 and 10 are separated from each other, and the switch is switched from on to off. Under such a normal use condition, the mechanical strengths of the lower base film 7 and the upper base film 11 are respectively increased by the dummy patterns 14, so that the breakage of both the base films 7 and 11 and the wiring pattern is prevented. There is.

On the other hand, when an airbag (not shown) stored in the steering wheel 1 is inflated and deployed during a vehicle collision, the inflating force of the airbag causes the films 7, 9, 11, 13 of the membrane switch to have both bases. Since the airbag 7 is easily broken along the cutting line 15 of the films 7, 11, the airbag passes through the broken portion and pushes the center pad 4 away to be smoothly inflated and deployed in the occupant direction. In this case, since the membrane switch is formed by laminating a plurality of films, there is no risk of the occupant being injured by the broken membrane switch.

In the above-mentioned one embodiment, the case where the ultra-thin PET film is used as the both base films 7 and 11 has been described. However, a material having a lower breaking strength than PET, for example, a polyethylene film is used as the normal thickness. It is also possible to use. Further, the spacer film 9 and the display film 13 may be made of a material having a normal breaking strength, and a notch such as a half cut may be formed at a portion corresponding to the cutting line 15 of both base films 7 and 11.

[0016]

[Effect of the device]

 As described above, according to the present invention, it is possible to provide a membrane switch that maintains mechanical strength at all times and can be easily cut only when necessary, and therefore a vehicle equipped with an air bag device. Even if it is attached to the steering wheel, the safety can be ensured without hindering the inflation and deployment of the airbag.

[Brief description of drawings]

FIG. 1 is a front view of a steering wheel to which a membrane switch of the present invention is applied.

2 is a cross-sectional view of the membrane switch of FIG.

FIG. 3 is a plan view of a lower base film included in the membrane switch of FIG.

[Explanation of symbols]

 1 Steering Wheel 4 Center Pad 5 Opening 6 Lower Electrode 7 Lower Base Film 8 Through Hole 9 Spacer Film 10 Upper Electrode 11 Upper Base Film 12 Swelling Part 13 Display Film 14 Dummy Pattern 15 Cutting Line

Claims (1)

[Scope of utility model registration request] 1. A membrane switch in which a pair of base films having electrodes formed by patterning are laminated via a spacer so that the respective electrodes face each other, and a plurality of dummy patterns made of metal foil are formed on the base film. A membrane switch characterized in that a band-shaped cutting line is formed between these dummy patterns while being formed.