JP2004061478A - Electrostatic capacity weight sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic capacity weight sensor which eliminates increase in electrostatic capacity and lowering of sensitivity due to long term heavy weight, be very high sensitivity and low cost. <P>SOLUTION: The sensor is structured by attaching an insulation spacers 4 on both sides of a plate which stainless steel 5 is bonded on a dielectric sheet 6 and pinching it with a capacitor electrode S-3a and a capacitor electrode E-3b. Its surrounding is covered with an insulator 2 and covered again with a shield electrode 1 using APA aluminum resin complex panels 1, 2, 3a and 3b. The surrounding is covered with a shield 8 and again with a cover insulator 7. For the stainless steel 5, a stainless steel plate with a thickness of 0.1 to 0.8 mm is used. For the cover insulator 7, a material expanding and contracting by external pressure is used. For the shield 8, a material easily expanding and contracting by external pressure is used. By this structure, a capacity weight sensor is provided whose capacity between electrodes of capacitor varies sensitively by weight. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a capacitance. The present invention relates to a weight sensor, and more particularly to a capacitance sensor suitable for use in a security alarm or the like that identifies and detects a small animal, a human body, and a vehicle, and that detects a change in capacitance due to weight.
[0002]
[Prior art]
Japanese Patent Application No. 2000-278967 discloses a capacitance sensor that detects a change in weight as a change in capacitance. This is a sensor that is embedded in the ground so that a change in weight can be detected as a change in capacitance. It relates to a weight sensor.
[0003]
[Problems to be solved by the invention]
With the conventional sensor material structure, when the sensor is buried 10 cm or more in the ground and one month or more elapses, the capacitance of the sensor gradually increases, and the durability against long-term heavy weight pressurization such as deterioration of sensitivity There was a problem with sex. In addition, when the burying depth of the sensor is 10 cm or more, the change in the capacitance of the sensor with respect to the weight becomes small, so that the sensitivity of the sensor is insufficient. Further, the capacitance of the sensor was too large, which hindered circuit design. In addition, there is a problem that the sensitivity differs depending on the location where the sensor weight is applied and a problem that the sensitivity varies. In addition, a sensor with good sensitivity was required to reduce the circuit cost. Another problem is that the cost of assembling the capacitor electrode and the insulator constituting the sensor is high.
[0004]
An object of the present invention is to provide a weight sensor for detecting a person suitable for crime prevention or the like by improving the above-mentioned drawbacks of the conventional capacitance sensor.
[0005]
[Means for Solving the Problems]
The capacitance weight sensor is composed of a dielectric sheet 6 (thickness: 0.05 mm to 0.6 mm) laminated with stainless steel 5SUS301 stainless steel (thickness: about 0.1 mm to 0.8 mm), and an insulating spacer 4 attached to both sides of the capacitor. It has a structure sandwiched between the electrodes 3a and 3b. An APA aluminum resin composite panel is used for the capacitor electrodes 3a and 3b, and the shield electrode 1 is provided via an insulator 2 as an integral plate. The periphery of the shield electrode 1 is covered with a shield 8. The periphery of the shield 8 is covered with a cover insulator 7 that can expand and contract by weight.
The spacer 4 is made of an insulator (hard vinyl chloride) having a thickness of 0.5 mm to 2.5 mm and a width of 10 mm to 20 mm at a pitch of about 10 cm. Contact with a certain weight.
The above-mentioned capacitor electrode is desirably an electrode made smaller by separating the aluminum layer of the APA aluminum resin composite panel with a groove.
The shield 8 is desirably made of a flexible material such as an aluminum foil laminated film so that the shield 8 can expand and contract when weight is pressed.
The cover insulator 7 is made of a thermoplastic polyetherester elastomer, an ultra-soft polyester resin, or the like, which can be expanded and contracted in the direction in which the weight is applied.
The capacitance and weight sensor of the present invention has a low cost, a small variation in sensitivity, an ultra-high sensitivity, and no long-term heavy pressure deterioration due to the above-mentioned structure and material.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a capacitance weight sensor according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view of the capacitance weight sensor. The capacitance weight sensor has a structure in which stainless steel 5 is adhered to a dielectric sheet 6, but insulating spacers 4 are attached to both sides thereof and sandwiched between capacitor electrodes S- 3 a and E- 3 b. For the capacitor electrode, use an APA aluminum resin composite panel "a composite plate with a sandwich structure in which low foaming polyethylene is used for the core material and aluminum numbers are laminated on both sides, trade name: Lightnium". Is provided by an integrated plate. The capacitor electrode S-3a and the capacitor electrode E-3b are insulated from the shield electrode using the side of the aluminum layer of the APA aluminum resin composite panel on which the four sides of the aluminum layer have been dropped by 5 mm. Separated to reduce the area of the capacitor electrode. Since the area of the capacitor electrode is reduced, the capacitance of the sensor can be reduced. An extensible shield 8 such as an aluminum foil laminated film is attached around the shield electrode 1. The periphery is covered with a cover insulator 7 that can expand and contract by weight. A polyester film having a thickness of 0.05 mm to 0.6 mm is used for the dielectric sheet 6, a thickness of 0.1 mm to 0.8 mm is used for the stainless steel 5, a thickness of 0.5 mm to 2.5 mm and a width of 10 mm for the spacer 4. 20 mm hard vinyl chloride is used at a pitch of about 10 cm, and the cover insulator 7 is made of an elastic insulating material such as a thermoplastic polyetherester elastomer or an ultra-soft polyester resin. The action of expanding and contracting the distance between the capacitor electrodes due to the weight is performed by the action of a spring between the plywood of the spacer 4, the dielectric sheet 6 and the stainless steel 5. It can be used for long-term heavy weight pressurization without deterioration. When the weight is increased, the capacitor electrode S-3a comes close to the stainless steel 5 and comes into contact with a certain load, and the capacitance between the electrodes changes as if the capacitor electrode S-3a was arranged at the position of the stainless steel 5 and the capacitance suddenly changed. And the sensitivity of the sensor becomes very high. According to the above principle, the capacitance and sensitivity of the sensor can be changed by adjusting the spacer thickness and the pitch interval. As the thickness of the spacer is thinner and the pitch interval of the spacer is wider, the sensitivity increases, but the durability under heavy load becomes weaker. The connection between the sensor signal extraction cable and the electrode of the capacitance weight sensor is such that the shield electrode 1 is connected to the shield side of the cable, and the capacitor electrodes 3a and 3b are connected to the twisted wire inside the shield of the cable.
The above-mentioned weight sensor is mainly used by being buried at a depth of about 10 cm in the ground, but is used under a carpet sheet or on a bed to detect the presence of a person. In addition to this, it can also be used for applications such as detecting pressure on a human hand.
[0013]
【The invention's effect】
It has a structure in which the capacitance changes depending on the weight of a person or the like, and uses a structural material that achieves ultra-high sensitivity, that is, a change rate of the capacitance per unit area of about 10 times, and is durable with respect to the weight. Since it is an electrostatic capacitance weight sensor, it can be used to detect a human body by being buried in the ground at a depth of 10 cm or more, and the sensor circuit cost can be reduced. In addition, this capacitance weight sensor uses an APA aluminum resin composite panel for the capacitor electrode, and its structure is shielded by a conductor through an insulator through an insulator. Has become a significant reduction. In addition, there is an effect of suppressing intrusion of external noise and unnecessary radiation by the action of the shield electrode.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a capacitance weight sensor.
DESCRIPTION OF SYMBOLS 1 Shield electrode 2 Insulator 3a Capacitor electrode S
3b Capacitor electrode E
4 Spacer 5 Stainless steel 6 Dielectric sheet 7 Cover insulator 8 Shield

Claims (6)

A spacer is provided on both sides of a stainless steel plate laminated to a dielectric sheet to form a capacitor electrode sandwiched between two APA aluminum resin composite panels. The periphery of this capacitor electrode is covered with an insulator, and the periphery is further shielded. A capacitive weight sensor characterized in that the structure covered with electrodes is made of an APA aluminum resin composite panel integrated plate, and the outermost periphery is covered with a stretchable insulating material. 2. The capacitance weight sensor according to claim 1, wherein the stainless steel plate and the capacitor electrode via the spacer come into contact with each other when the weight exceeds a certain value. In the invention of claim 1, the dielectric between the spacer and the electrodes of the two APA aluminum resin composite panels is an elastic dielectric sheet having a thickness of about 0.05 mm to 0.6 mm, and the stainless steel plate has a thickness of 0.1 mm. A capacitance weight sensor having a thickness of about 1 mm to 0.8 mm In the invention of claim 1, in the APA aluminum resin composite panel, the electrode on the spacer side is an electrode constituting a capacitor, and the area of the electrode is reduced by separating the aluminum layer by a groove. A capacitance weight sensor used as a shield electrode 2. The capacitance weight sensor according to claim 1, wherein the spacer uses insulators having a thickness of about 0.5 mm to 2.5 mm and a width of 10 mm to 20 mm at a pitch of about 10 cm. The invention according to claim 1, wherein a thermoplastic polyetherester elastomer, an ultra-soft polyester resin, or the like is used as a material capable of extending and contracting in a direction in which a weight covering the outer periphery of the capacitance weight sensor is applied. Capacitance weight sensor

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