Browse Prior Art Database

Acoustic Membrane Construction

IP.com Disclosure Number: IPCOM000035889D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Bruner, DA: AUTHOR [+2]

Abstract

In one typical construction of a buckling-spring membrane keyboard, a rubber blanket is placed over the membrane to dampen the noise level of the pivot plate assembly when actuated. The rubber blanket covers the entire upper membrane and is a relatively expensive component item.

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Acoustic Membrane Construction

In one typical construction of a buckling-spring membrane keyboard, a rubber blanket is placed over the membrane to dampen the noise level of the pivot plate assembly when actuated. The rubber blanket covers the entire upper membrane and is a relatively expensive component item.

An improved construction for mounting and damping the pivot plate is provided. As shown in Fig. 1 which is a sectional view through the membrane keyboard, the membrane keyboard includes a three-layer stack of membranes 10, 12 and 14 which conventionally can be formed of polyethylene terephthalate films such as MYLAR* or other suitable material. The center layer 12 has openings formed therein at the various key locations, as shown at 16. Conductive ink contact pads 18 and 20 are provided by screening the conductive ink on the opposed surfaces of the sheets 10 and 14. The sheet 14 flexes when a key stroke is made bringing the contact pads 18 and 20 into contact with each other, defining a key stroke.

(Image Omitted)

For acoustical damping, a damping material such as screenable UV curable silicone rubber, or an expanding PVC plastisol, or other suitable material is screened onto the top of the sheet 14 at each key location. At each location a specific pattern is screened which can be either a series of discrete pads 22, 24 and 26, as shown in Fig. 2, which is a top view of the sheet 14 or a single pattern 28, as shown in Fig. 3, which is also a top view of anot...