OBJECT DETECTOR BASED ON CAPACITANCE

• Main Authors: MURAKAMI YUICHI, OTA NOBUYUKI, IEDA SEIICHI, TSURUTA MANABU, YOSHIDA AKEMASA
• Format: Patent
• Language: English
• Published: 20.02.1998
• Edition: 6
• Subjects: DETECTING MASSES OR OBJECTS; GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PHYSICS; TESTING

PROBLEM TO BE SOLVED: To enhance the detection reliability of an obstacle by preventing erroneous operation due to adhesion of water or mud. SOLUTION: The object detector comprises an electrode unit 10 including a first electrode 10a, a second electrode 10b and a grounded third electrode 10c, a switching circuit Csw for switching between the second electrode 10b and the ground selectively, an oscillation circuit 3, a resonance/coupling circuit 2 inserted between the oscillation circuit 3 and the second electrode 10b, and a CPU 1 setting a zero-point correction mode for grounding the first electrode 10a through the switching circuit Csw and a detection mode for connecting the first electrode 10a with the second electrode 10b. In the zero-point correction mode, the CPU 1 regulates the capacity of the circuit 2 such that the oscillation output voltage VL will be equal to a first set value Vx. Subsequently, a switching is made to the detection mode and the capacity of the circuit 2 is altered to a value larger by an amount corresponding to the increase of capacity due to adhesion of water or mud and approach to an obstacle is detected by monitoring the oscillation output voltage VL.