Elastomeric key switch actuator

• US 5,389,757 A
• Filed: 03/16/1994
• Issued: 02/14/1995
• Est. Priority Date: 06/15/1993
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Souliere, Ernest G.
• Primary Examiner(s): CUSICK, ERNEST
• Application Number:
  US08/210,099
• Time in Patent Office: 335 Days
• Field of Search: 200/517, 200/513, 200/521, 200/345, 200/406, 200/402
• US Class Current: 200/345
• CPC Class Codes: H01H 13/705 characterised by construction, mounting or arrangement of operating parts, e.g. push-buttons or keys
• CPC Class Codes: H01H 2215/00 Tactile feedback
• CPC Class Codes: H01H 2215/006 Only mechanical function
• CPC Class Codes: H01H 2215/016 Collapsing to second stable position
• CPC Class Codes: H01H 2227/022 Collapsable dome
• CPC Class Codes: H01H 2235/008 Rubber spring

Abstract

A key switch and resilient actuator assembly that includes an electrical switching region and a hollow open ended actuator cover of elastomeric material overlaying the switching region with the open end of the actuator cover in surrounding relationship with the switching region. The actuator cover includes a first wall portion shaped to provide substantially linear resistive force during compression displacement of the cover toward the switching region and to provide substantially linear restoring force during expansion displacement of the actuator cover away from the switching region. The actuator cover further includes a second wall portion shaped to undergo buckling toward the switching region at a predetermined compression displacement and to undergo unbuckling away from the switching region at a predetermined expansion displacement that is smaller in total displacement than the predetermined compression displacement. The actuator cover also includes an interior portion positioned and sized to move into the switching region at the buckling of the second wall portion and to move out of the switching region at the unbuckling of the second wall portion.

Claims

1. A key switch and actuator assembly comprising:

An electrical switching region; and

A hollow arched actuator made of elastomeric material and having an open end, the actuator overlaying the electrical switching region and having its open end in surrounding relationship therewith, the actuator including a first wall portion shaped to provide substantially linear resistive force during compression displacement of the actuator toward the switching region and to provide substantially linear restoring force during expansion displacement of the actuator away from the switching region, the actuator further including a second wall portion located below the first wall portion shaped to undergo buckling toward the switching region at a predetermined compression displacement and to undergo unbuckling away from the switching region at a predetermined expansion displacement that is smaller in total displacement than the predetermined compression displacement, the actuator also including an interior portion positioned and sized to move into the switching region at the buckling of the second wall portion and to move out of the switching region at the unbuckling of the second wall portion.

2. A resilient key switch assembly comprising:

An electrical switch including two annular shaped normally open contacts of the same diameter; and

A hollow closed topped dome shaped cover made of elastically resilient material, the cover having and open bottom end situated opposite the closed top, the cover overlaying the electrical switch with its open bottom end in surrounding relationship with the contacts of the switch, the cover including a first linear wall portion shaped to undergo a rolling action during compression displacement of the cover toward the contacts and to undergo an unrolling action during expansion displacement of the cover away from the contacts, the cover further including a second tactile wall located closer to the open bottom end than the linear wall portion, the tactile wall portion being shaped to undergo a buckling action toward the switch at a predetermined compression displacement and to undergo an unbuckling action away from the contacts at a predetermined expansion displacement that is smaller in total displacement than the predetermined compression displacement, the cover also including an annular shaped foot having substantially the same diameter as the contacts and in aligned relationship with them ,the foot being positioned within the cover to close the contacts at the buckling action of the second portion and to open the contacts at the unbuckling action of the second portion.

3. The resilient key switch assembly of claim 2 where the electrical switch comprises two annular shaped contacts and the interior portion of the dome shaped cover is annular shaped.

4. The resilient key switch assembly of claim 2 further including a bumper encircling the annular shaped foot.