Proximity detector

Abstract

Abstract PURPOSE: To improve detection precision by placing a loop circuit across the secondary winding of an oscillation transformer in a state close to resonance by providing a feedback phase and amplitude adjusting circuit between one terminal of the primary winding and the collector of a transistor. CONSTITUTION: At the stage of adjustment, the loop circuit consisting of secondary winding L 2 of oscillation transformer T, and capacitors C 1 and C 2 is placed in a state close to resonance and feedback phase and amplitude adjusting circuit N 1 is used to adjust properly feedback to the oscillating circuit consisting of transistor Q 1 , transformer T, etc., so that oscillation of amplitude h 1 will be caused between collector B of Q 1 and earth terminal E at time (t). As a person approaches a parallel plate detector, the oscillation amplitude decreases without reference to whether the capacity of the detector changes much or a little and the phase shifts through circuit N 1 . This change is amplified by transistor QL connected via detecting/amplifying circuit N 2 and output from self-compensating circuit N 3 . Consequently, the detection precision can be improved while malfunction is eliminated. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Takeo Ueda

Bibliographic Details