Low current switching apparatus having detent structure providing tactile feedback

• Main Authors: ZUERCHER, JOSEPH CHARLES, WILLIAMS, CONSTANCE LANEAR, TARANOWSKI, MICHAEL G, LEWIS, EDWARD GEORGE
• Format: Patent
• Language: English; French; German
• Published: 04.09.1991
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SWITCHES; ELECTRICITY; EMERGENCY PROTECTIVE DEVICES; RELAYS; SELECTORS

Pivotal movement of a switch actuator (16) drives a finger (16c,16d) projecting from the actuator against a convexly bowed leaf spring (40), depressing an intermediate portion of the leaf spring to an unstable concave condition. The leaf spring resists the actuator movement, initially with an increasing force but changing to a decreasing force at a predictable point (B) in actuator movement to provide tactile feedback at an operator (22) affixed to the actuator. The leaf spring is a flat beam. The spring force and point of changeover can be readily and predictably varied during manufacture by selecting springs (40) having different widths, thicknesses or other variable parameters. A modular block (38) holds the spring in the bowed condition and is positioned relative to the actuator finger by a support plate (36). The actuator finger drives the spring against a conductive rubber block (34a,34b), compressing the block against spaced conductors (28d,28e) on a printed circuit (28) to complete the circuit. A plurality of such switches are made in a common package by layering a printed circuit (28), insulator sheet (30), conductive rubber sheet (34) with raised bosses (34a,34b,34c), detent support plate (36) and a plurality of detent blocks (38) with bowed springs (40), between a base (26) and a cover (4). Back lit illumination is provided by a light pipe (42) trapped against the cover as an additional layer. A microprocessor board (52), connected to the internal printed circuit (28), is attached to the switch housing (2) exteriorly of the base (26).