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Keyboard and Wiping Contact Assembly

IP.com Disclosure Number: IPCOM000073430D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 47K

Publishing Venue

IBM

Related People

Johnson, DO: AUTHOR

Abstract

This keyboard centers about an elastic diaphragm switch (EDS) assembly having positive wiping contact operation. The EDS portion of the assembly has a rigid baseplate 10 with semi-spherical depressions 12 beneath each contact location. One layer 14 of flexible insulating material, such as MYLAR* (R), is superimposed on the baseplate 10. There is a coating 16 of conductive material, gold or copper for example, on the upper side of this layer 14. Above this is a spacer 18 having circular apertures immediately above the depressions 12. Another layer 20 of flexible material with a coating 22 of conductive material on the underside forms the top sealing member of the EDS assembly.

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Keyboard and Wiping Contact Assembly

This keyboard centers about an elastic diaphragm switch (EDS) assembly having positive wiping contact operation. The EDS portion of the assembly has a rigid baseplate 10 with semi-spherical depressions 12 beneath each contact location. One layer 14 of flexible insulating material, such as MYLAR* (R), is superimposed on the baseplate 10. There is a coating 16 of conductive material, gold or copper for example, on the upper side of this layer 14. Above this is a spacer 18 having circular apertures immediately above the depressions 12. Another layer 20 of flexible material with a coating 22 of conductive material on the underside forms the top sealing member of the EDS assembly.

The key portion of the assembly comprises a number of keybuttons 30 molded into a flexible grid of cross-bars 32 which lie on the sealing layer 20 above and between the depressions 12. Protuberances 42 on the buttons 30 limit key travel as desired. A nib 44 on the lower surface of each button 30 is effective to force layers 20 and 18 into the depressions 12, as shown with respect to the keybutton 30'.

The conductive coatings 16 and 22 have generally circular apertures, as shown on the inset, with complementary contact tongues centrally located and extending into the circular area. Normally the contact areas are concentrically located one above the other. When a keybutton is depressed, however, the deformation of the layer 14 and 20 with attendant deformat...