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Reduction of Downstop Noise on a Membrane Keyboard

IP.com Disclosure Number: IPCOM000044289D
Original Publication Date: 1984-Dec-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 84K

Publishing Venue

IBM

Related People

Murphy, RD: AUTHOR [+2]

Abstract

The noise produced from a key button downstopping against a frame when the key button is depressed is reduced through having a stem of each key button engage a pivot plate, which pivots to close a membrane switch, before the key button engages the frame. This also improves switch make bounce while not affecting switch break bounce. A key button 1 (Fig. 1) has the length of its stem 2 such that the stem 2 has its bottom 3 engage a pivot plate 4, which rests on a membrane switch assembly 5 and supports one end of a spring 6 urging the key button 1 upwardly, with the key button 1 spaced from top surface 7 of a frame 8.

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Reduction of Downstop Noise on a Membrane Keyboard

The noise produced from a key button downstopping against a frame when the key button is depressed is reduced through having a stem of each key button engage a pivot plate, which pivots to close a membrane switch, before the key button engages the frame. This also improves switch make bounce while not affecting switch break bounce. A key button 1 (Fig. 1) has the length of its stem 2 such that the stem 2 has its bottom 3 engage a pivot plate 4, which rests on a membrane switch assembly 5 and supports one end of a spring 6 urging the key button 1 upwardly, with the key button 1 spaced from top surface 7 of a frame 8. This avoids the noise previously produced by the key button 1 engaging the top surface 7 of the frame 8, although a smaller noise is produced by the bottom 3 of the stem 2 of the key button 1 engaging the pivot plate 4. In Fig. 2, the pivot plate 4 has a raised projecting portion 9 for engaging a stem 10 of the key button 1. The stem 10 is the standard length of the key button 1 rather than the extended length of the stem 2 of Fig. 1. The raised projecting portion 9 (Fig. 2) of the pivot plate 4 engages bottom 11 of the stem 10 of the key button 1 before the key button 1 engages the top surface 7 of the frame 8. Even if the spring 6 fails to buckle before the stem 10 of the key button 1 engages the pivot plate 4 because of the earlier engagement between the key button 1 and the pivot plate 4, the swit...