Browse Prior Art Database

Torsion Spring Actuator for a Key Switch

IP.com Disclosure Number: IPCOM000083961D
Original Publication Date: 1975-Aug-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 3 page(s) / 57K

Publishing Venue

IBM

Related People

Harris, RH: AUTHOR

Abstract

Fig. 1 illustrates a pictorial view of a molded one-piece key button actuator assembly made of suitable plastic, for actuating dome-type snap switches or other switches such as elastic diaphragm switches or mechanical contact points. The actuator is designed so that it will close a switch requiring 160 grams of nominal vertical force to be actuated and requires 0.01" of displacement. Once a switch has closed, a force of less than 160 grams is required to keep the switch closed.

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Torsion Spring Actuator for a Key Switch

Fig. 1 illustrates a pictorial view of a molded one-piece key button actuator assembly made of suitable plastic, for actuating dome-type snap switches or other switches such as elastic diaphragm switches or mechanical contact points. The actuator is designed so that it will close a switch requiring 160 grams of nominal vertical force to be actuated and requires 0.01" of displacement. Once a switch has closed, a force of less than 160 grams is required to keep the switch closed.

The actuator shown in Fig. 1 consists of a plastic key button 1 with an integral actuator spring which comprises two key button support bars 2, two integrally molded torsion bars 3, and a switch actuator lever or bar 4. The ends of the torsion bars 3 are formed into pivots 5 for mounting in a suitable bearing block, not shown. An upward direction stop member 6 is formed on a part of key button 1, or alternatively as a projection from one of the key support levers 2.

A surface of the actuator lever 4 cooperates with the underside of key button 1, in the event that key button 1 is pushed far enough to twist torsion bars 3 sufficiently, to allow contact to occur between the top surface of actuator lever 4 and the underside of key button 1.

A heel 7 of actuator lever 4 is shown in Fig. 1. This is the raised or increased thickness portion of actuator lever 4 which, when key button 1 has been depressed far enough limits the amount of vertical bending in the torsion bars 3 by coming into contact with the frame member, not shown in Fig. 1.

Upon assembly, the torsion bars 3 are slightly twisted by the switch actuator lever 4 which is in contact with, for example, a flexible dome switch contact. The underside of the actuator lever 4, as shown in Fig. 2, has a small protrusion 9 which is in contact with a snap dome type metal switch element 10.

A slight preload force or deflection of the top of the done switch 10 is indicated by the arrow labeled F(SW). This force tends to push up against protrusion 9 and to apply stress through actuator lever 4 which, in turn, through torsion of the torsion...