JPH0269620A - Weight detecting member - Google Patents

Abstract

PURPOSE:To detect an electrostatic capacity without receiving any influence from a stray capacity produced between electric wires or between earths by shielding a detection electrode with electrodes for earth. CONSTITUTION:When a weight G is applied to a weight detecting member 10, distances d1 and d2 between a detection electrode 10a and electrodes for earth 10d and 10e become shorter, since urethane members 10b and 10c are compressed. As a result, the time constant of a detecting member 10 changes and a capacity detecting section 3 detects the change and outputs an electrostatic capacity detecting signal to a heater controlling section 4. Therefore, only the change in the electrostatic capacity produced by the weight G can be detected without receiving any external influence, since the detection electrode 10a is shielded by the electrodes 10d and 10e.

Description

DETAILED DESCRIPTION OF THE INVENTION (Objective of the Invention) (Industrial Field of Application) The present invention relates to a le! detection member used in a device for detecting the absence of a load fi by a change in capacitance.

(Prior art) Conventional Im detection members are made of urethane or the like as disclosed in Japanese Patent Application Laid-Open No. 15448/1982 and Japanese Patent Application No. 8928/1983 filed by our company as human body detection means such as electric carpets. A structure has been proposed in which electrodes are bonded to both sides of a dielectric elastic member to detect changes in capacitance of the dielectric elastic member.

Now, in the schematic circuit of the carpet shown in FIG. 2, in an example using the lff1 detection member of the prior art described in ttJ, electrodes ia and ib are adhered to both surfaces, respectively, to constitute the weight detection member 1.

One electrode 1a of this lff1 detection member 1 is grounded,
The other electric current iib is connected to the pulse generator 2. It is connected to the capacitance detection section 3 and the power supply Vcc. Furthermore - this capacitance detection section 3
is configured to output a detection signal to the heater control section 4.

In the above configuration, in normal operation, the weight detection member 1 is repeatedly charged with a constant time constant by the l-1,1 output pulse from the pulse generator 2. The capacitance detection section 3 that detects this detects that no weight, such as a human body, is applied to the weight detection member 1, that is, that there is no change in capacitance, and sends this capacitance detection signal to the heater control section. It is output to 4.

For example, if an additional IG such as a human body is added,
C is compressed. That is, the dimension d between the respective electrodes 18 to 1b becomes smaller.

First, if the area of each electrode 1a, 1b is S, and the dielectric constant of urethane is ε, the capacitance C generated by these is expressed as C-ε(S/d), so fd is small → capacitance The IC becomes large, and the timing of charging and discharging changes. This is the capacitance detection section 3
is detected, and a detection signal of the capacitance change is output to the heater control section 4. Then, the evening control unit 4 controls the heater based on the detection signal.

(Problems to be Solved by the Invention) However, with the weight detection member 1 having the above-described configuration, a stray capacitance C1 is generated between, for example, the electric wire 5 that is wired indoors and the electrode 1b.

In addition, even if a human touches another grounded object, the floating capacity 11C
2 occurs. Stray capacitance C1, C caused by this capacitance
2 is larger than the capacitance C of the weight detection member 1, this stray capacitance ICI, C2 is detected as noise by the capacitance detection unit 3.
is input. For this reason, a malfunction has occurred in which the heater control section 4 is caused to malfunction.

That is, 1) with the heavy ffi detection member having the configuration described above, it was not possible to accurately detect a change in capacitance due to a load.

Therefore, an object of the present invention is to provide a highly reliable weight detection member that is not affected by stray capacitance generated between electric wires or between the ground and is capable of accurate electrostatic passenger detection. 1.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a detection electrode for detecting capacitance, a dielectric elastic member that covers this electrode from both upper and lower directions, and further comprises: It shall consist of a grounding electrode that covers from above and below.

(Function) With this configuration, the detection 7rX electrode is shielded by the grounding electrode, so it is not affected by stray capacitance generated between wires or the like.

(Example) An example using the II detection member of the present invention will be described below with reference to FIG. Note that the same reference numerals will be used for the same parts.

First, reference numeral 10 denotes a weight detection member, and the structure of this weight detection member 10 has a planar detection electrode 10a in the center, and this detection electrode 10a is covered from both sides with two urethane sheets 10b and 10c, which are dielectric elastic members. It's thick. Furthermore, these two urethane sheets 10b.

A first electrode 10, which is a grounding electrode, covers 10C.
d and the second electrode 10e are inoculated.

The first electrode 10d and the second electrode 10e of this weight detection member 10 are grounded, and the detection electrode 10a is grounded.

It is connected to the pulse generator 2, the capacitance detection section 3, and the power supply VCC. Further, the capacitance detection section 3 is configured to output an electrostatic guest detection signal to the heater control section 4.

Next, the operation of the above structure will be explained.

In normal operation, the medium quantity detection member 10 is activated at a constant period (time period vi) by the H and L output pulses from the pulse generator 2.
> is repeatedly charging and discharging. The capacity detection unit 3 detects the state of charge based on this time constant, and if there is no change in the state of charge (time constant), the load of the human body, etc.
If it is not added to 0, 1 is disconnected, and this detection signal is output to the heater control section 4.

Here, when a load G is applied to the Ifjt detection member 10, the urethane 10b, 10C is compressed, and the dimension d 1 between the detection electrode 10a, the first electrode 10d, and the second electrode 10e
, d1 becomes smaller. With a lever, the detection electrode and the first. The area of the second Ti pole is S, urethane 1Q
b, the dielectric constant of 10C is ε, and if we consider that the capacitors are equivalently connected in parallel, the capacitance C1 is expressed as C1=28(S/'d1), and if jd 1 is small → capacitance C1 large," the time constant of the weight detection member 10 changes, and the capacitance detection section 3 detects this and outputs a capacitance detection signal to the control section 4.

During this operation, the electric wire 5, etc. and the first and second
, 10e, etc. are generated between the first and second electrodes 1c3, but since they are grounded,
The potentials of 0d and 1Qe are constant at the ground potential. Therefore, changes in capacitance due to external stray capacitance do not occur. However, no noise is input to the capacitance detection section 3. Furthermore, the detection unit 1410a detects these first and second electrodes 1
Since it is shielded by 0d and iQe, the capacitance detection unit 3 can detect only the change in capacitance due to the weight G without being influenced by the outside.

Therefore, this weight detection member can perform accurate capacitance detection without being affected by external forces (effects due to stray capacitance) from electric wires or grounding parts.

Also, compared to conventional weight detection components, the structure is easier to change (
It also has manufacturing advantages, such as being able to be manufactured in a single process and can be immediately integrated into products that use conventional weight sensing members.

It should be noted that the present invention is not limited to the embodiments described in "11", and can be used as a switching unit for automatic doors, etc., and can also be used as a switching unit for automatic doors, etc. Also, the present invention can be used as a switching unit for automatic doors, etc. It is also possible to use a configuration in which the detection electrode is wrapped around and covered.Furthermore, the dielectric elastic member is not limited to urethane, but rubber or the like may also be used, and it may be deformed as appropriate within the scope of the purpose to hide the actual state. be.

〔Effect of the invention〕

As described in detail above, according to the present invention, accurate changes in capacitance can be detected without being affected by externally generated stray capacitance, etc., resulting in highly reliable detection. ffl
! The detection member is provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic circuit diagram of an electric carbera i/e incorporating the ff1l detection member of the present invention, and FIG. 2 is a schematic circuit diagram of a conventional weight detection member/v/e electric carpet. In the drawing, 108 is a detection electrode, 10b, 10Ciu urethane (dielectric elastic member), and 10C1, 10e are a first electrode and a second electrode (grounding electrode).

Claims (1)

[Claims] A weight detection member comprising: a detection electrode for detecting capacitance; a dielectric elastic member that covers this electrode from both upper and lower directions; and a grounding electrode that further covers this dielectric elastic member from above and below.