1. Field of the Invention
The present invention relates to a circuit for processing a pseudo-oscillatory signal generated by an oscillating circuit, more particularly for an inductive proximity detector or similar apparatus.
2. Description of the Prior Art
A resonating circuit proximity detector is described in the French patent application FR 86 13359 filed on 19th Sept. 1986. The resonating circuit includes a capacitor in parallel with a coil which can be influenced by an object to be detected and it is connected to a power supply through a controllable switch which is driven by control pulses generated by a processing circuit.
Depending on the state of the control pulses, the switch is closed or open and the resonating circuit is charged by a power supply or is respectively discharged with variable damping depending on the object detected.
The processing circuit includes a comparator and a logic circuit. The comparator compares the relaxation voltage of the resonating circuit with a threshold so as to generate measurement pulses representative of the presence and of the distance of an electrically conducting object; the measurement pulses are transmitted to the logic circuit which delivers a measurement signal to a user circuit having a digital input and controls the closure and opening cycles of the static switch.
The proximity detector described has the advantage of allowing even very close objects to be detected while facilitating direct digital processing of the analog proximity information.
It seems desirable to construct the processing circuit of such a proximity detector--or of any other similar apparatus using an influenceable resonating circuit--in the form of an integrated circuit adapted to MOS technology and to reduce the consumption of this circuit.
In addition, in such a circuit, it would be advantageous to minimize or suppress the adjustments and to provide self compensation of the temperature and voltage supply drifts.
The purpose of the invention is to respond to these requirements in a processing circuit of the above described type.