JPH07107976B2 - Contactless actuated electronic device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device which has an oscillator that can be attenuated by an object from the outside and operates without contact.
Particularly, it relates to a proximity switch.

[0002]

2. Description of the Prior Art In a known proximity switch of the type described above (German Patent No. 2054100), a feedback oscillator is used which can be attenuated externally by the object. Then, in order to process the oscillator signal, a demodulation method in which an AC voltage is rectified and smoothed is conventionally applied.

[0003]

Since the resonant frequency of the aforementioned oscillator is related to the tolerances of the coils and capacitors and other components, the vibration amplitude can change independently of the object in proximity to the oscillator. Further, the demodulation method in which the processing circuit for the oscillator signal is rectified and smoothed is accompanied by a sensitivity loss due to the influence of temperature and other environmental conditions on the above-mentioned components.

Therefore, an object of the present invention is, as a device of the above type, to have a vibration amplitude that is as constant as possible in the non-damped state of an oscillator, and to have almost no influence on external influences such as temperature and humidity or influences of parts. Regardless, it is to provide a high sensitivity, quick response, and low cost.

[0005]

In order to achieve the above-mentioned object, the present invention has a separately excited oscillator which can be attenuated by an object from the outside, and the separately excited oscillator is connected to a frequency regulator for phase adjustment. In a contactless operation type electronic device controlled by a synchronous loop (PLL), the output of the separately excited oscillator is directly input to the reference voltage comparison circuit to output the Schmitt trigger signal, and the Schmitt trigger signal output is input to the shift register. It is characterized by

[0006]

By using the separately excited oscillator as the oscillator, the oscillation vibration only decreases when the object attenuates and does not stop, so that the oscillation amplitude increases immediately when the object is separated, and The noise signal is effectively removed by connecting the output of the excitation oscillator directly to the reference voltage comparison circuit having the Schmitt trigger output and inputting the Schmitt trigger output to the 4-bit shift register having the serial input terminal and the parallel output terminal. You can

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In the figure, an oscillator circuit consisting of a coil 1 and a capacitor 2 is connected on the one hand to a negative potential conductor 3 and on the other hand to an input 4 of a reference voltage comparison circuit 5.
Furthermore, the oscillating circuit is a frequency adjuster 7 (in the present case, for example, the printed matter “Theorie und Anwendung der phase-locked
-loop (the theory and application of phase-locked loop) known as "phase-locked loop" input terminal 6 and capacitor 8 (capacitor that works in concert with the frequency adjustment oscillator circuit consisting of coil 25 and capacitor 26 as a phase measurement capacitor) The reference voltage comparator circuit 5 is connected on one side to the negative potential conductor 3 and to the resistor 9 which provides the reference voltage, whereby the sensitivity can be kept constant. The other resistor 10 is used as a hysteresis resistor.
The reference voltage can also be influenced externally via the conductor 11. As shown in the printed matter, the output 12 of a known reference voltage comparison circuit 5 having a Schmitt trigger output is connected to the input 13 of a retriggerable timing element 14, for example.

The timing element is connected to the negative potential conductor via a capacitor 15 which defines the timing pulse. The output 16 of the retriggerable timed element 14 is an exclusive OR circuit.
18 is connected to one input terminal 17 and an output signal 22 is output from the output terminal 19 through a matching circuit 20 and an amplifier 21.
Is obtained. However, it is also conceivable to use a shift register having a serial input and a parallel output and an AND logic circuit for its output in order to achieve noise suppression. Whether the output signal 22 is positive or negative depends on the connection of the second input 23 of the exclusive OR circuit 18. In the state shown, no signal is applied to the input 23. After opening the program switch 24, the input end 23 through the resistor 25
Is given a signal. The exclusive OR circuit 18 gives a signal to the output terminal 19 only when a signal is given to either the input terminal 17 or the input terminal 23. That is, when the program switch 24 is closed, it produces an output signal when the oscillator is not damped, and when the switch 24 is open, it produces an output signal 22 when the oscillator is damped.

Next, a method of operating the switchgear according to the present invention will be described. As long as the oscillator oscillates without being damped by an external object, each pulse is compared with the reference voltage in the reference voltage comparison circuit 5. As long as they reach a certain voltage value in the undecayed state, these pulses are transmitted to the output side of the reference voltage comparison circuit 5. The retriggerable timing element 14 accepts one transmitted pulse during each half wave. Similarly, these pulses are applied to the shift register. Since the run time of the retriggerable timed element is longer than the period of the oscillator oscillation, a continuous signal is produced at the output 16 during continuous oscillation of the oscillator. This output signal is the exclusive OR circuit 18, the matching circuit 20 and the amplifier as described above.
Processed via 21. To prevent false pulses, the retriggerable timing element 14 responds only after the arrival of a plurality of pulses, for example three pulses.

The output signal 22 opens and closes a thyristor or triac connected to a voltage source to control a load connected in series so that the switchgear according to the invention can be used as a two-wire switchgear. Is also possible. The main components of the switchgear according to the invention can easily be combined in one integrated circuit (IC) to allow a compact and simple construction.

[0011]

As described above, according to the present invention, in the non-contact actuated switchgear, particularly the proximity switch, the conventional self-excited oscillator system is changed,
By using the oscillator as a separately excited type, the oscillation frequency greatly changes due to the tolerance of the inductance of the coil of the resonance circuit and the capacitance of the capacitor, and there is no drawback that the oscillation frequency fluctuates even if the object to be detected does not approach. Not only the management aspect in the manufacturing process,
The advantage is that the operational reliability during field use is greatly improved.

Further, the main part of the circuit portion of the electronic device according to the present invention can be integrated on one semiconductor chip together with the PLL circuit for frequency adjustment, and a great advantage can be obtained in terms of manufacturing cost. . Furthermore, since the oscillation frequency is extremely stabilized by the configuration of the present invention, the oscillation frequency can be selected to be higher by an order of magnitude than that of the conventional one, and the detection sensitivity of the proximity target can be considerably increased as compared with the conventional device. Is possible.

Furthermore, noise is suppressed by inputting the output of the separately excited oscillator directly to the reference voltage comparison circuit to output the Schmitt trigger signal and inputting this Schmitt trigger signal output to the shift register. It is possible to prevent malfunction due to noise.

[Brief description of drawings]

FIG. 1 is a principle circuit diagram of an embodiment of a switchgear according to the present invention.

[Explanation of symbols]

 1 coil 2 capacitor 3 negative potential lead wire 5 reference voltage comparison circuit 7 frequency regulator (PLL) 8 capacitor 9 reference voltage resistance 10 hysteresis resistance 14 time limit element 15 capacitor 18 exclusive OR circuit 20 matching circuit 21 amplifier 22 output signal 24 program switch 25 coils 26 capacitors

Claims (1)

[Claims] 1. A contactless actuated electronic device comprising a separately excited oscillator externally attenuable by an object, the separately excited oscillator being connected to a frequency adjuster for phase locked loop (PLL) control. A contactless operation type electronic device, wherein the output of the separately excited oscillator is directly input to a reference voltage comparison circuit to output a Schmitt trigger signal, and the Schmitt trigger signal output is input to a shift register.