Electronic pressure-sensitive device for detecting the magnitude of load as electrical resistance

Abstract

Disclosed is an electronic pressure-sensitive device which has a long service life and which is capable of detecting with high accuracy loads of various magnitudes including values in proximity to zero. In the electronic pressure-sensitive device, first and second resistive element layers 2b and 6b are formed on the outermost surfaces of first and second contact portions 2 and 6, and the first and second resistive element layers 2b and 6b are constantly maintained in an electrical contact state, the force bringing the first and second resistive element layers 2b and 6b into press contact with each other being detected as the electrical resistance between the first and second contact portions 2 and 6.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to an electronic pressure-sensitive device for detecting the magnitude of a load as electrical resistance and, in particular, to an electronic pressure-sensitive device capable of detecting the magnitude of a load ranging from a small load to a large load.[0003] 2. Description of the Related Art[0004] For example, as shown in FIG. 7, in a conventional electronic pressure-sensitive device used in a seat sensor or the like detecting whether a person is sitting on a seat, a first contact portion 52 formed on a flexible first insulating substrate 51 and consisting of a conductive material is opposed to a second contact portion 56 formed on a flexible second insulating substrate 55 and consisting of a conductive material through the intermediation a gap, the width of the gap being maintained by a spacer 54 provided between the first and second insulating substrates.[0005] When a load is applied to the first and second i...

AI Technical Summary

Benefits of technology

[0013] Further, since there is no need to maintain a gap between the contact portions, there is no need to provide a maintaining member for maintaining a gap, and there is no deterioration in performance due to deformation of the maintaining member. Further, since there is no gap between the contact portions, the amount of deformation (deflection amount) due to the load is small, so that there is little burden on the substrates, thereby providing a long service life.

[0040] In this electronic pressure-sensitive device, power supply from the outside to the contact portions and the resistance value output between the first and second contact points (power output in accordance with the resistance value) are effected by using the wiring pattern, so that there is no need to separately connect a lead wire or the like to the resistive elements, so that the construction is simple, and it is possible to make the electrical connection between the contact portions and the exterior more reliable.

Problems solved by technology

However, in the conventional electronic pressure-sensitive device, which is turned ON when a load of a magnitude not less than a threshold value is applied, it is difficult to detect a small load applied to the electronic pressure-sensitive device or variation in the load.

In a motor-vehicle-mounted seat sensor using this conventional electronic pressure-sensitive device, it is difficult to detect the magnitude of a load, so that it is impossible to sense the physique of the person sitting on the seat, to operate the air bag in conformity with the physique of the person sitting on the seat, some other device is necessary.

Further, in the case of a motor-vehicle-mounted sensor, a load can be continuously applied at high temperature, so that it is necessary to use an expensive material such as polyethylene terephthalate, which has a superior heat resistance, for the first and second insulating substrates 51 and 55, which are continuously deflected by the load (baggage), resulting in a high cost.

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