JPH06162888A - Noncontact type switch - Google Patents

Abstract

PURPOSE:To provide a noncontact type switch with which error operation due to the change of ambient environment and noise except intentional operation is prevented. CONSTITUTION:A sensing part A is provided with a plurality of detecting elements 1a, 1b consisting of a pair of electrodes. One detecting element 1a is a main detecting element which is an operation object and another detecting element 1b is installed in the surrounding of the detecting element 1a. A detecting circuit 2 generates a detection signal from a comparator 26 when the electrostatic capacity between electrodes decreases as a human being comes closer to each detecting element 1a, 1b. A signal processing part 21 generates an output signal when a detection signal is generated only in the detecting element 1a. Also, the signal processing part 21 does not generate the output signal when detection signal corresponding to either one of detecting elements 1a, 1b is generated within a prescribed time after a detection signal corresponding to the other detecting element 1a or 1b is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-contact type switch which generates an output signal by a non-contact operation by detecting a change in electrostatic capacitance due to the approach of a human body.

[0002]

2. Description of the Related Art Conventionally, as a non-contact type switch of this type utilizing a change in capacitance, as shown in FIG. 7, the inner electrode 11 and the outer periphery of the inner electrode 11 are surrounded over the entire circumference. A sheet-like detection element 1 in which the outer electrode 12 and the outer electrode 12 are arranged on substantially the same plane is proposed (PCT).
/ AU86 / 00043). That is, the detection element 1 constitutes a sensing unit that detects the presence or absence of an operation. The inner electrode 11 and the outer electrode 12 are insulator bases 1.
3 is laminated or embedded. As shown in FIG. 8, the inner electrode 11 is connected to the base of the transistor Q for detection,
A rectangular wave pulse voltage is applied to the outer electrode 12 as a drive signal drv.
Is applied as. That is, when the drive signal drv is applied to the outer conductor 12, the inner conductor 11 detects a current corresponding to the rising and falling of the drive signal drv.

When there is no object around the sensing element 1, electric charges are distributed only between the inner electrode 11 and the outer electrode 12 as shown in FIG. 9 (a). On the other hand, FIG.
As shown in (b), when an object having a large earth-to-ground capacitance such as a human body approaches the sensing element 1, a capacitor is formed between the outer electrode 12 and the object. Since this capacitor functions as a bypass capacitor to the ground, the capacitance between the inner electrode 11 and the outer electrode 12 will be smaller than when there is no object, and when the drive signal drv rises and falls. The current flowing through the base of the transistor Q at that time decreases. Therefore, the signal to be judged sen, which is the collector output of the transistor Q, depends on the existence of an object as shown in FIGS.
The peak value changes as shown in.

The signal to be judged sen is input to the detection circuit.
The detection circuit stores the reference value obtained based on the peak value of the signal to be judged sen when the power is turned on (that is, the peak value of the detected current), and stores the peak value and the reference value of the signal to be judged sen thereafter. Compare sequentially. That is, the signal to be judged sen is taken out at a constant cycle and compared with the reference value. Also,
In the detection circuit, when the peak value of the signal to be judged sen becomes smaller than the reference value, the detection signal is generated assuming that the object approaches. The load can be turned on / off by controlling switch elements such as relays using this detection signal.

As described above, this type of non-contact type switch can turn the output on and off in a non-contact manner, so that it can be embedded in an insulating material and used as a wall switch. It can also be used by embedding it in housing equipment or water supply equipment. In particular, in a water supply facility, the detection element 1 can be embedded in the facility to prevent water from entering the energized portion, which is advantageous over other switches when used as a switch in a water supply facility. .

[0006]

By the way, since the non-contact type switch having the above-mentioned structure detects the change of the electrostatic capacity in a non-contact manner, it has the same level as that of the human body due to the influence of radiation noise or getting wet with water. There is a problem that a malfunction occurs when the capacitance changes. For example, if it is used in a bathroom, there is a high possibility that a malfunction will occur when it gets wet with water that has overflowed when taking a bath or when using a shower. Also,
Since the presence or absence of the operation is detected in a non-contact manner, even if there is no intention to operate, it may be judged that the operation is performed only by a part of the human body approaching, and a malfunction may occur.

The present invention is intended to solve the above problems, and it is possible to prevent malfunctions due to the presence of radiation noise, changes in the surrounding environment such as getting wet with water, and noises other than conscious operation. It is intended to provide an expression switch.

[0008]

According to the present invention, in order to achieve the above object, a sensing section having a sensing element in which a pair of electrodes are arranged close to each other on a substantially same plane, and both electrodes when a human body approaches In a non-contact switch equipped with a detection circuit that outputs a detection signal when the capacitance between them decreases below a reference value, multiple sensing elements are arranged around the main sensing element to form a sensing unit, The circuit is a detection unit that generates a detection signal for each detection element, and an output signal when a detection signal corresponding to another detection element is generated within a predetermined time after the detection signal corresponding to any one detection element is generated. And a determination unit that generates an output signal when only the detection signal corresponding to the main detection element is generated.

Further, the reference value for the main detection element may be set higher than the reference values for the other detection elements.

[0010]

According to the above construction, in addition to the main detection element in the sensing portion, a plurality of detection elements arranged around the main detection element are provided, and a detection signal is generated for each detection element and one detection element is provided. No output signal is generated when a detection signal corresponding to another detection element is generated within a certain time after the detection signal corresponding to an element is generated, and output when only a detection signal corresponding to the main detection element is generated. Since the signal is generated, if there is radiation noise or the environment changes such that the sensing part gets wet with water, or if the person approaches the sensing part without being aware of it In case of occurrence, the output signal is prevented from being generated by outputting the detection signal corresponding to multiple detection elements. Rukoto but they can. Also, when a person intentionally operates the main sensing element,
Since it is considered that a detection signal corresponding to another detection element is not generated, an output signal can be generated, and a conscious operation and an unintentional erroneous operation can be discriminated. As a result, the probability of malfunction is reduced.

Further, when the reference value for the main detection element is set higher than the reference values for the other detection elements, the space area where the detection signal is generated for the main detection element is the space where the detection signal is generated for the other detection element. It is possible to widen the area, and as a result, it is possible to improve the operability by expanding the spatial area in which the detection signal is generated only for the main detection element.

[0012]

EXAMPLE In this example, as shown in FIG. 2, nine sensing elements 1a and 1b are arranged in a matrix in a sensing section A, and the central sensing element 1a is the main sensing element to be operated. Other sensing element 1b
Is a detection element used to prevent malfunction. The structure of each sensing element 1a, 1b is similar to that described in the prior art, and as shown in FIG. 3, an inner electrode 11 and an outer electrode 12 are provided on a base 13 made of an insulating material. The outer electrode 12 is arranged so as to surround the circumference of the electrode 11, and the display lamp 14 embedded in the base 13 is exposed so as to face the center of the inner electrode 11.

Each sensing element 1a, 1b is connected to a sensing circuit 2. As shown in FIG. 1, the detection circuit 2 includes a signal processing unit 21 including a microcomputer that applies a drive signal drv to the outer electrode 12. Drive signal
drv is a rectangular wave pulse signal having a period of 20 msec. The bases of the transistors Q are connected to the inner electrodes 11 of the detection elements 1a and 1b, respectively, and the judgment signal sen is output from the collector of the transistor Q. The judgment signal sen output from each transistor Q is supplied to the multiplexer 22. It is designed to be sequentially taken in through. The signal to be judged sen fetched through the multiplexer 22 is input to the DC component removing circuit 23 to remove the DC component, and then amplified by the amplifier circuit 24. The signal to be judged sen is a signal of a differential waveform generated in response to rising and falling of the drive signal drv, so the output of the amplifier circuit 24 is input to the peak hold circuit 25 and the peak value of the differential waveform is detected. It The signal processing unit 21 stores a reference value set based on the peak value of the signal to be judged sen when the power is turned on, and this reference value is input to the comparator 26 through the digital-analog converter 27. The comparator 26 compares the peak value of the signal to be judged sen, which is the output of the peak hold circuit 25, with the reference value, which is the output of the digital-analog converter 27, and the peak value of the signal to be judged sen is smaller than the reference value. Then, a detection signal is generated and input to the signal processing unit 21.

In the signal processing unit 21, the multiplexer 22
Which sensing element 1a, 1 depends on the selection signal sel to
It is possible to know whether a detection signal has been generated for b.
Here, even when the detection signal is generated for the main detection element 1a, while the selection signal sel to the multiplexer 22 makes one cycle, another detection element 1b is generated.
When the detection signal is generated, the signal processing unit 2
No output signal is generated from 1. When the detection signal is generated for the main detection element 1a and the detection signal is not generated for the other detection elements 1b while the selection signal sel makes one cycle, the signal processing unit 21 generates an output signal. Further, the signal processing unit 21 does not generate an output signal under conditions other than the above. Therefore, the multiplexer 22, the peak hold circuit 25, the comparator 26, and the like form a detection unit, and the signal processing unit 21 forms a determination unit.

For example, when the sensing section A gets wet with water, it is considered that detection signals are generated for the plurality of detection elements 1a and 1b, and also when there is radiation noise, the detection signals for the plurality of detection elements 1a and 1b are generated. It is thought that it will occur, and moreover the person unconsciously senses
Since it is considered that the detection signals are generated for the plurality of detection elements 1a and 1b even when the output signal approaches, the output signal is not generated in these cases. On the other hand, when a finger or the like is intentionally brought close to the main detection element 1a, no detection signal is generated for the other detection elements 1b, so that an output signal can be generated, and only in this case, the operation as a switch is possible. It will be possible.

When the sensing section A of the non-contact type switch having the above-mentioned structure is used as an operating section for controlling a jet-type water flow device (Jacuzzi (trademark)), FIG.
It may be buried in the edge of the bathtub 3, as shown in FIG. here,
Although the sensing unit A is arranged on the back surface side of the bathtub 3, it goes without saying that it may be arranged on the front surface side of the bathtub 3. Further, when used as a wall switch, as shown in FIG. 5, a sensing section A having detection elements 1b for preventing malfunction is arranged on both sides of the main sensing element 1a, and the sensing element 1a is provided on the surface of the sensing section A. Only the cover 4 having the window 4a exposing only one may be attached.

(Embodiment 2) In the first embodiment, the reference value to be compared with the peak value of the signal to be judged sen is made equal for each of the sensing elements 1a and 1b.
As shown in FIG. 2, two-step reference values THa and THb are set, the higher reference value THa is used for the main detection element 1a, and the lower reference value THb is used for the other detection elements 1b. I am trying to use it. Reference value T
By setting Ha and THb in this way, it is possible to set the range in which the detection signal is generated for the main detection element 1a that is the operation target to be wider than the range in which the detection signal is generated for the other detection elements 1b. Only in the element 1a, the space region where the detection signal is generated can be widened, and the operability is improved. Other configurations are similar to those of the first embodiment.

[0018]

As described above, according to the present invention, in addition to the main sensing element in the sensing section, a plurality of sensing elements arranged around the main sensing element are provided to generate a sensing signal for each sensing element. , When a detection signal corresponding to one detection element is generated and a detection signal corresponding to another detection element is generated within a fixed time, no output signal is generated, only a detection signal corresponding to the main detection element is generated. Since an output signal is generated when the sensing part is exposed to radiation noise or the surrounding environment changes such that the sensing part gets wet with water, or when the person approaches the sensing part without being aware of it. If noise occurs, the output signal is generated by outputting the detection signal corresponding to multiple detection elements. It has the advantage that it is possible to prevent the that. Further, when a person intentionally operates the main sensing element, it is considered that the detection signal corresponding to the other sensing element does not occur, so that the output signal can be generated, and the conscious operation and the unconscious operation can be performed. It is possible to identify the erroneous operation of. As a result, there is an advantage that the probability of occurrence of malfunction is reduced.

If the reference value for the main detection element is set higher than the reference values for the other detection elements, the space area where the detection signal is generated for the main detection element is the space where the detection signal is generated for the other detection element. It is possible to widen the area than the area, and as a result, it is possible to improve the operability by expanding the spatial area in which the detection signal is generated only for the main detection element.

[Brief description of drawings]

FIG. 1 is a block circuit diagram showing a first embodiment.

FIG. 2 is a front view showing a configuration example of a sensing unit used in the first embodiment.

FIG. 3 shows a sensing element used in Example 1,
(A) is a plan view and (b) is a sectional view.

FIG. 4 is a schematic configuration diagram showing a usage example of the first embodiment.

FIG. 5 is an exploded perspective view showing another configuration example of the sensing unit used in the first embodiment.

FIG. 6 is an operation explanatory diagram of the second embodiment.

FIG. 7 is a plan view of a conventional detection element.

FIG. 8 is a circuit diagram of a main part of a conventional example.

FIG. 9 is a diagram illustrating the principle of a conventional example.

FIG. 10 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

 1 Detecting Element 1a Detecting Element 1b Detecting Element 2 Detecting Circuit 21 Signal Processing Section 22 Multiplexer 23 DC Component Removing Circuit 24 Amplifying Circuit 25 Peak Hold Circuit 26 Comparator 27 Digital-Analog Converter A Sensing Section

Claims (2)

[Claims] 1. A sensing unit including a sensing element in which a pair of electrodes are arranged close to each other on a substantially same plane, and a sensing signal is output when the capacitance between the two electrodes decreases below a reference value due to the approach of a human body. In the non-contact switch equipped with a detection circuit, a plurality of detection elements are arranged around the main detection element to form a sensing unit, and the detection circuit includes a detection unit that generates a detection signal for each detection element. , When the detection signal corresponding to another detection element is generated within a predetermined time from the generation of the detection signal corresponding to any one of the detection elements, an output signal is not generated,
A non-contact type switch, comprising: a determination unit that generates an output signal when only a detection signal corresponding to a main detection element is generated. 2. The non-contact switch according to claim 1, wherein the reference value for the main detection element is set higher than the reference values for the other detection elements.