JPH0746984Y2 - Proximity switch - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a proximity switch which can detect the approach of an object to be detected.

[0002]

2. Description of the Related Art FIG. 5 is a circuit diagram showing a schematic configuration of a conventional oscillation type proximity switch, and FIG. 6 is an operation explanatory diagram thereof. In the figure, an integrated circuit (IC) 5 is composed of an oscillator circuit (not shown), a rectifying / smoothing circuit for oscillating voltage, a voltage detecting circuit for detecting the level of the smoothed voltage, and the like. Oscillation coil 2
Are connected in parallel with the capacitor 3 to form a resonance circuit. The sensitivity adjusting resistor 4 is for adjusting the gain of the oscillation circuit of the integrated circuit 5. Further, 6 is an output terminal, 7 and 8 are power terminals, and 1 is a distance between the object to be detected (in this case, a metal body) 1 and the oscillation coil 2. When the metal body 1 approaches the oscillation coil 2, the oscillation voltage V1 across the oscillation coil 2 gradually decreases as the metal body 1 approaches, as shown in FIG. At this time, when the oscillating voltage V1 reaches the voltage detection level V0 of the voltage detecting circuit of the integrated circuit 5, the output terminal 6 outputs a signal indicating the state changed from the off state to the on state, and the metal body 1 is oscillated by the oscillation coil. Approaching 2 and stipulating the distance l1
It is possible to determine that you have entered within.

[0003]

However, in this conventional device, it is not possible to simply determine whether or not the metal body 1, which is an object to be detected, has entered a prescribed distance, and the object to be detected approaches the ON operation area. It has a drawback that it is not possible to determine whether or not it is separated from the off operation region. Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the conventional device, to ensure a simple configuration, and a state before the detected object enters the ON operation region or a state in which the detected object is separated from the ON operation region to the OFF operation region. It is to provide a proximity switch that can be discriminated.

[0004]

In order to achieve the above-mentioned object, the present invention switches from OFF operation to ON operation when an input signal level reaches a predetermined voltage detection level, and an object to be detected approaches. In the proximity switch for detecting that the input signal level or the voltage detection level is constantly and repeatedly level-shifted, and the input signal and the voltage detection level which are constantly and repeatedly level-shifted by the level-shift switching means. Or the input signal is compared with the voltage detection level that has been level-shifted constantly by the level shift switching means, and in an intermediate area between the off-operation area due to the separation of the object to be detected and the on-operation area due to the proximity. The object to be detected is in the on-moving region, which is equipped with detection means that outputs a signal that repeats on / off Possible to determine the state of the ON and OFF signals immediately before away state or off-operation region immediately before the neighboring characterized.

[0005]

In the proximity switch according to the present invention, when the input signal level is constantly level-shifted by the level shift switching means, the repeated level-shifted input signal is compared with the voltage detection level to detect the object to be detected. Outputs a signal that repeats ON / OFF in the intermediate area between the OFF operation area and the ON operation area when approaching when it is separated from the oscillation coil, and the voltage detection level is constantly and repeatedly level-shifted by the level shift switching means. In this case, the voltage detection level that is repeatedly level-shifted is compared with the input signal to detect an intermediate area between the ON operation area and the OFF operation area when the object to be detected is separated from the oscillation coil and the object to be detected. When the object approaches the oscillation coil, it is turned on in the intermediate area between the off operation area and the on operation area.
It can be seen that the detected object exists in the ON operation region and the OFF operation region by outputting a signal that repeats OFF.

[0006]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a circuit configuration diagram showing a schematic configuration of one embodiment of the present invention, and FIG. 2 is an operation explanatory diagram thereof.
In the figure, parts having the same functions as in FIG. 5 are assigned the same reference numerals and explanations thereof are omitted.

In FIG. 1, an oscillator 9 gives its oscillation signal to a transistor 10. The oscillator 9 and the transistor 10 constitute level shift switching means for repeatedly level shifting the input signal level input to the integrated circuit 5. As shown by A in FIG. 2, the transistor 10 is repeatedly turned on and off, and for example, of the gain adjusting resistors 4A and 4B of the oscillation circuit (not shown) of the integrated circuit 5, for example, the resistor 4B is repeatedly short-circuited and opened. I do. Therefore, the oscillation voltage V2 across the oscillation coil 2 is high when the transistor 10 is on and is low when the transistor 10 is off, and this relationship is maintained even when the metal body 1 approaches the oscillation coil 2. . When the oscillation voltage V2 reaches the voltage detection level V0, the output signal B of the output terminal 6 changes from the previously off state to the on state. However, since the oscillation voltage V2 crosses the voltage detection level V0 while the metal body 1 is in the intermediate region l2, the output signal B repeats the on / off operation. Further, when the metal body 1 approaches the oscillation coil 2, the output signal B changes to ON operation, and the proximity region l1
Is displayed.

As described above, while the metal body 1 is in the intermediate region l2, the output signal B which repeats the ON / OFF operation is output through the smoothing circuit (not shown) of the integrated circuit 5 to generate a DC voltage. It can also be taken out as a signal. Next, FIG. 3 is a circuit configuration diagram showing a schematic configuration of another embodiment of the present invention, and FIG. 4 is an operation explanatory diagram thereof. In the figure, parts having the same functions as those in FIG. 1 or 5 are designated by the same reference numerals.

In the figure, the voltage detection circuit 11 incorporated in the integrated circuit 5 has a voltage detection level V0A which is switched in two stages in accordance with the output waveform of the oscillator 9 as the level shift switching means. When the metal body 1 approaches the oscillation coil 2, the oscillation voltage V3 gradually decreases, and when the metal body 1 crosses the voltage detection level V0A, the metal body 1 moves to the intermediate region l2.
The output signal B of the output terminal 6 repeats the ON / OFF operation while it is in the state of. Further, when the metal body 1 approaches the oscillation coil 2, the output signal B changes to ON operation, indicating that it is in the proximity area l1.

[0010]

As described above, according to the present invention,
When the input signal level reaches a predetermined voltage detection level, the proximity switch is switched from the off operation to the on operation to detect that the object to be detected approaches, and either the input signal level or the voltage detection level is detected. Level shift switching means for constantly repeating level shift, and comparison between input signal and voltage detection level constantly repeated level shifting by the level shift switching means, or input and voltage detection level constantly repeated level shifting by the level shift switching means Compare with the signal,
A state immediately before the detected object approaches the ON operation region, including detection means for outputting a signal that repeats ON / OFF in an intermediate region between an OFF operation region due to separation of the detected object and an ON operation region due to proximity. Alternatively, the state immediately before leaving the off operation area is determined by the on / off repeated signal, so that the circuit configuration is simple and the detected object is separated from the oscillation coil without increasing the number of output terminals. The object to be detected is present in the intermediate area between the off operation area and the on operation area due to proximity, or in the intermediate area between the on operation area where the detection object is close to the oscillation coil and the off operation area due to separation. In this case, since it is possible to output a signal that repeatedly turns on and off, it is possible to reliably determine that the detected object is present in the intermediate region. Having.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a schematic configuration of an embodiment of a proximity switch of the present invention.

FIG. 2 is an operation explanatory diagram of FIG.

FIG. 3 is a circuit configuration diagram showing a schematic configuration of another embodiment of the proximity switch of the present invention.

FIG. 4 is an operation explanatory diagram of FIG.

FIG. 5 is a circuit configuration diagram showing a schematic configuration of a conventional proximity switch.

6 is an explanatory diagram of the operation of FIG.

[Explanation of symbols]

 1 Metal Body 2 Oscillation Coil 4A Sensitivity Adjustment Resistor 4B Sensitivity Adjustment Resistor 5 Integrated Circuit 9 Oscillator 10 Transistor V2 Oscillation Voltage V3 Oscillation Voltage V0 Voltage Detection Level VOA Voltage Detection Level 12 Intermediate Area

Claims (1)

[Scope of utility model registration request] 1. A proximity switch for detecting the approach of an object to be detected by switching from an off operation to an on operation when the input signal level reaches a predetermined voltage detection level, wherein the input signal level or the voltage detection is detected. Level shift switching means for constantly and repeatedly level shifting one of the levels, and comparing the input signal and voltage detection level constantly and repeatedly level shifted by the level shift switching means, or constantly and repeatedly level shifting by the level shift switching means. A detection unit is provided, which compares the voltage detection level with an input signal and outputs a signal that repeats on / off in an intermediate region between an off operation region due to separation of the detected object and an on operation region due to proximity. The state immediately before the object approaches the ON operation area, or immediately before the object moves away from the OFF operation area. Proximity switch, characterized in that the state to determine the ON and OFF signals.