- Patent JPS5534529

Document Type and Number:

Japanese Patent JPS5534529

Kind Code:

B2

Abstract:

1383132 Electronic touch switches MAGIC DOT Inc 23 Feb 1973 [17 March 1972] 9065/73 Heading G1N In a capacitor plate electronic touch switch, the switching circuit is substantially isolated from earth ground so that the entire switching circuit and plate oscillates at power frequency with respect to ground. This oscillating voltage across the body capacity provides an input signal when the plate is touched. As shown, Fig.1, a two-stage switching amplifier 12, 30 is inter-connected by an integrator circuit 48, 50 and energized through a transformer and rectifier 62, 78. The circuit earths 26 are isolated from earth ground 70 and the transformer connections "poled" so that the touch-plate will be 180 degrees out-of-phase with any voltage induced in the touching body. Alternatively a power frequency signal may be injected into the D.C. supply to the switching circuit through a resistor (150), Fig.5 (not shown) with a mains supply, or (102), Fig.3 (not shown) with a battery supply, or a resistive potential divider may be used instead of a transformer, Fig.4 (not shown) with the lower arm (124) acting as an "isolating" resistor. Detailed Additions, Fig.5 (not shown). A large resistor (1 megohm, 152) connected to earth ground is stated to improve noise immunity, and an H.F. by-pass capacitor (158) is recommended in the amplifier circuit. A Zener diode (not shown) connected across the integrator capacitor 50 allows the circuit to be used on various supply voltages.