Browse Prior Art Database

Fail Safe Capacitive Actuator with Acoustical Noise Reduction

IP.com Disclosure Number: IPCOM000045867D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Bellamy, RL: AUTHOR [+2]

Abstract

As the actuator described in U.S. Patent 4,118,611 restores to its normal up position, it contacts the frame, causing an undesirable noise.

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Fail Safe Capacitive Actuator with Acoustical Noise Reduction

As the actuator described in U.S. Patent 4,118,611 restores to its normal up position, it contacts the frame, causing an undesirable noise.

The improvement adds an integral actuator upstop 10 located near the fulcrum 11 and contacting the frame 13 when the tip 11 of the actuator 14 is near the frame. Upstop 10 has a low velocity as it impacts the frame compared to the tip 12 which has much higher velocity as it is much farther away from the fulcrum 11, resulting in the diminution of the acoustical upstop noise. Further improvement may be obtained when the upstop 10A in Fig. 2 is designed as a bridge, as shown, which permits deflection in the center to cushion the impact of the keybutton notch.

Actuator upstop 10 also serves as a positive engagement surface of the actuator should the buckling spring have failed to buckle for any reason. The keybutton notches 16 will engage the upstop 10 on an actuator that has failed to make, driving the tip 12 downward to contact the pad card, thus permitting the generated signal to be sensed electronically.

As the keybutton 15 reaches its final downstop (by abutment of notch 16 to upstop 10 and the actuator in its down position) and then continued downward pressure is applied by the operator to the top center of the button, the button will cam backwardly to dissipate keybutton-bottoming noise.

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