JPH01103318A - Proximity switch device - Google Patents

Abstract

PURPOSE:To select the length of a signal transmission line optionally by providing a couple of oscillation electrode plates acting like an antenna outputting an oscillated signal from an oscillation circuit. CONSTITUTION:The oscillated output of a prescribed frequency is radiated from an oscillation circuit 5 through a couple of the oscillation electrodes 2, 3 and the electric force of lines are generated around the electrode plates. The electric line of forces at the outside of the electrode plate 3 and a detection electrode plate 1 located at the outside are changed in response to the change in the dielectric constant due to access of a human body. Thus, the electric field strength between the electrodes 1, 3 is changed, an induced voltage is generated in a detection coil 6 and extracted through an amplifier circuit 7. In this case, since the electrode plates 2, 3 act only like the antenna for the circuit 5, the length of the signal transmission line connecting a detection section comprising the electrode plates 1-3 and a control section comprising other circuits is adjusted optionally.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is mainly used as a start switch for detecting the approach of an object such as a human body without contact and controlling the operation of an automatic opening/closing door or a security device. The present invention relates to a proximity switch device used.

<Prior Art> As a proximity switch device used as a starting switch for controlling the opening/closing of such an automatic opening/closing door, a rubber cloak is used, which is made by covering the entirety of two metal plates facing each other with a predetermined gap with waterproof rubber. Switches have been commonly used in the past. This rubber cape switch detects an approaching human body by contact between two metal plates when a human body is placed on it.Since it uses a contact type to detect the human body, for example, if a person steps on it with a high heel or a stubby foot. It has the drawbacks of being prone to breakdowns and damage to its waterproof function and having a short lifespan, and is not aesthetically pleasing because it is laid exposed in the vicinity of automatic opening/closing doors.

Therefore, as a proximity switch device that eliminates these drawbacks, two sensing plates made of metal plates are buried underground in the mat near the automatic opening/closing door, and these sensing plates are used as constants in the oscillation circuit. When a human body approaches the buried sensing plate, the oscillation frequency of the oscillation circuit changes due to stray capacitance and resistance loss between the human body and the sensing plate. Since the output level changes according to the change in Q, a non-contact detection method has been devised in which this change is extracted to the outside and operates a switch section, thereby controlling the opening/closing of an automatic opening/closing door.

<Problems to be Solved by the Invention> However, even in the non-contact detection type proximity switch device, due to the fact that two sensing plates made of metal plates are used as constants in the oscillation circuit, the following problems occur. There are various problems such as: In other words, since the oscillating part uses the sensing plate as a constant in the oscillation circuit, it is preferable to install the oscillating part near the sensing plate.If the oscillating part is buried underground together with the sensing plate, the impedance of the sensing plate Due to this, it is generally used by placing it inside a sensing plate within the same electric field.

The reason for doing this is that when the oscillator is separated from the sensing plate,
This is because, due to impedance, another electric field is generated in the feeder line connecting the two, making it impossible to use the sensing plate as a constant in the oscillation circuit.

However, using a structure in which the oscillation section is housed within the sensing plate causes great practical inconvenience. That is, in the case of inspection and repair due to a malfunction in the oscillating section, it is necessary to remove the entire sensing plate, and in particular, removing the floor such as tiles is a large-scale construction work. Additionally, if a maintenance hole is provided in advance, the above problem can be resolved, but providing such a hole in front of an automatically opening/closing door poses problems in terms of aesthetic appearance and smooth passage. .

Furthermore, since the sensing plate and the oscillating section are integrally constructed, there are problems in manufacturing and reliability of the device.

<Purpose of the Invention> The present invention has been made in view of the above-mentioned conventional technical problems, and it is possible to install a detection section consisting of a buried electrode plate and a control section consisting of an oscillation section, a switch section, etc. at an arbitrary distance. It is an object of the present invention to provide a proximity switch device that does not generate unnecessary radio waves in a signal transmission line such as a cable connecting the two devices even when the two devices are connected.

Means for Solving the Problems> The present invention constitutes technical means for solving the problems as follows. That is, an oscillation circuit configured from a crystal resonator or the like and outputting a predetermined frequency signal, a pair of oscillation electrode plates buried close to each other and functioning as antennas for outputting the oscillation signal of the oscillation circuit, and one of the oscillation circuits. A detection electrode plate buried close to the oscillation electrode plate and connected to the other oscillation electrode plate, and a certain level of electric field strength between this detection electrode plate and the other oscillation electrode plate. The present invention is characterized by comprising a detection circuit that detects the above changes.

Effects> With the above configuration, the oscillation signal of the oscillation circuit is radiated out through the pair of oscillation electrode plates, so that electric lines of force are generated around each of the three electrode plates. When a human body approaches the detection area where each electrode plate is buried,
The lines of electric force do not change because the permittivity of each gap between the three electrode plates does not change appreciably, but the permittivity of each outer portion of the detection electrode plate located on the outside and the other oscillation electrode plate changes, the lines of electric force change, and a voltage is induced between the sensing electrode plate and the other oscillation electrode plate, which are connected to each other, due to the change in electric field strength, and this induced voltage exceeds a certain value. When this occurs, the detection circuit detects this and activates the switch section.

In this proximity switch device, unlike existing devices, each electrode plate is not one of the components of the oscillation circuit, and the pair of oscillation electrode plates act as mere electrodes that output the oscillation signal of the oscillation circuit. Since the oscillation frequency and output level are determined by the oscillation circuit itself, even if each electrode plate is installed separately from the oscillation circuit and detection circuit, another electric field will be generated in the signal transmission line such as the cable connecting between them. does not occur.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

The figure is a block configuration diagram showing an embodiment of the present invention, and the detection area, for example, when used as a starting switch for an automatic opening/closing door, the sensing part buried in a location near the automatic opening/closing door has a single detection electrode. Plate 1 and a pair of oscillation electrode plates 2.
3 are stacked with a spacer member 4 having a high dielectric constant such as a foamed urethane material interposed therebetween, and a detection electrode plate 1 and a ground side oscillation electrode plate 3 located on both outer sides.
are connected to each other. As each of the electrode plates 1 to 3, in addition to a simple metal plate, those having a wire-like shape, a grid-like shape, and a shelf-like shape can be used.

The oscillation circuit 5 is configured using a crystal resonator and the like as components and outputs a constant oscillation frequency signal, and outputs the oscillation signal through a pair of oscillation electrode plates 2.3. That is, both oscillation electrode plates 2 and 3 function as mere antennas of the oscillation circuit 5, rather than as one of the constituent members of the oscillation circuit 5.

The amplifier circuit 7 amplifies the electric field strength, that is, the induced voltage, between the detection electrode plate 7 and the ground-side oscillation electrode plate 3. The detection coil 6, which is one of the components of the amplifier circuit 7, The primary side coil part is inserted and connected between the detection electrode plate 1 and the earth side oscillation electrode plate 3, and the secondary side coil part is connected to the amplifier circuit 7.

The detection circuit 8 compares the output of the amplifier circuit 7 with a predetermined set level and outputs a signal when the output exceeds the set level. The output circuit 9 includes a switch section for controlling the opening and closing of an automatic opening/closing door, and a relay coil of the switch section is energized by the output of the detection circuit 8.

Next, to explain the operation of the embodiment, the oscillation output of a constant frequency from the oscillation circuit 5 is transmitted to the pair of oscillation electrode plates 2.
3, each electrode plate 1-3
Electric lines of force are generated around the . When a human body approaches the detection area where each of the electrode plates 1 to 3 is embedded, the lines of electric force in the gaps between each of the electrode plates 1 to 3 have a dielectric constant due to the presence of the spacer member 4 having a high dielectric constant. Corresponding to the fact that there is almost no change, there is no change, but the lines of electric force on the outside of the detection electrode 1 and the ground-side oscillation electrode plate 3, which are located on both outsides, change due to the change in dielectric constant due to the approach of the human body. Change in response to change. Therefore, the electric field strength between the picture electrode plates 1 and 3 changes, and an induced voltage is generated in the primary coil section of the detection coil 6, and is amplified and taken out from the secondary coil section, and is amplified and extracted from the amplification circuit 7. is further amplified. When a human body approaches each electrode plate 1 to 3, the output level of the amplifier circuit 7 becomes higher than the set level of the detection circuit 8, and a signal is output from the detection circuit 8 to energize the relay coil of the output circuit 9, automatically The door can be opened.

This proximity switch device differs from existing devices that use an electrode plate as one of the components of the oscillation circuit to detect deviations in oscillation frequency and changes in intensity due to the proximity of a human body. Plate 2.3 is the oscillation circuit 5
Since each electrode plate 1 only functions as an antenna,
The length of the signal transmission line that connects the detection section consisting of 3 to 3 and the control section consisting of other oscillation circuits 5, detection circuits 8, etc. can be made arbitrary. Therefore, the control section can be installed at any location according to the site conditions where the proximity switch device is installed, and the wiring location of the signal transmission line can also be arbitrarily selected.

It should be noted that the present invention is not limited to the above description and illustrated examples, and may include various modified embodiments without departing from the scope of the claims. For example, in the above embodiment, the case where the switch is used as a starting switch for an automatically opening/closing door has been described, but it can also be used as a switch for detecting a human body or a moving object in crime prevention or safety equipment. Further, the spacer members 4 interposed between the electrode plates 1 to 3 are not limited to those made of foamed urethane-based materials, and other high dielectric constant members may also be used. Furthermore, each electrode plate 1 may be a space.
~3 do not necessarily need to be arranged in parallel.

<Effects of the Invention> Since the present invention is configured and operates as described above, according to the proximity switch device of the present invention, the pair of oscillation electrode plates is not a fixed component of the oscillation circuit (it functions as a mere antenna). Therefore, the length of the signal transmission line that connects the detection section consisting of each electrode plate and the control section consisting of an oscillation circuit, detection circuit, etc. is no longer affected, and the installation location of the control section 1 and the wiring of the signal transmission line are no longer affected. can be selected arbitrarily, making it easy to handle inspections and repairs.

Furthermore, since the oscillation frequency and output level are determined only by the oscillation circuit, stable operation is achieved without malfunctions. Furthermore, the detection sensitivity can be adjusted by adjusting only the detection sensitivity of the detection circuit itself or the sensitivity of the detection side, such as the amplification degree of the amplifier circuit in the preceding stage, without considering oscillation tuning. becomes easier.

[Brief explanation of the drawing]

The figure is a block diagram of an embodiment of the present invention. 1...Detection electrode plate 2... One oscillation electrode plate 3...Other oscillation electrode plate 5...Oscillation circuit 8...Detection circuit

Claims (1)

[Claims] (1) An oscillation circuit composed of a crystal resonator or the like and outputting a predetermined frequency signal, a pair of oscillation electrode plates buried close to each other and functioning as antennas for outputting the oscillation signal of the oscillation circuit, and one of the oscillation circuits. A detection electrode plate buried close to the oscillation electrode plate and connected to the other oscillation electrode plate, and a certain level of electric field strength between this detection electrode plate and the other oscillation electrode plate. A proximity switch device comprising a detection circuit that detects the above change.