Multiple detent membrane switch

• US 5,824,978 A
• Filed: 06/26/1997
• Issued: 10/20/1998
• Est. Priority Date: 06/26/1997
• Status: Expired due to Fees

• Current Assignee: Lear Automotive Dearborn, Incorporated (Lear Corporation)
• Original Assignee: UT Automotive, Inc.
• Inventors: Karasik, Boris G., Karasik, Vladimir G.
• Primary Examiner(s): Friedhofer, Michael A.
• Application Number:
  US08/882,844
• Time in Patent Office: 481 Days
• Field of Search: 200/1 B, 200/5 A, 200/512, 200/513, 200/517, 400/472, 400/490
• US Class Current: 200/18
• CPC Class Codes: H01H 13/64 wherein the switch has more than two electrically distinguishable positions, e.g. multi-position push-button switches
• CPC Class Codes: H01H 13/702 with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
• CPC Class Codes: H01H 2215/004 Collapsible dome or bubble
• CPC Class Codes: H01H 2225/018 Consecutive operations

Abstract

An improved membrane switch includes multiple detents. A pair of electric circuits are completed by the membrane switch. The switch includes the pair of open electric circuits, three flexing areas, and two membrane contacts. Normally the flexing areas bias the membrane contacts out of contact with the electric circuits. When a first actuation force is applied to the membrane, the intermediate flexing area flexes allowing the first circuit to be complete by the first membrane contacts. When a second actuation force is applied to the membrane, the center and outer flexing areas flex allowing the second circuit to be completed by the second membrane contacts. The inventive membrane switch provides the operator with a clear indication and a detent feel for each of the two circuits.

Claims

1. A membrane switch comprising:

a membrane having a center, intermediate, and outer flexing areas and first and second membrane contacts, said membrane positioned adjacent first and second circuit contacts associated with each of said first and second membrane contacts; and

said center, intermediate and outer flexing areas normally biasing said first and second membrane contacts out of contact with said first and second circuit contacts, and a first actuation force on said membrane flexing said intermediate flexing area and causing said first membrane contact to contact said first circuit contact, and a second actuation force flexing said center and outer flexing areas and causing said second membrane contact to contact said second circuit contact.

2. The membrane switch of claim 1, wherein said second actuation force is a normal force on the center of said membrane.

3. The membrane switch of claim 1, wherein said second membrane contact is positioned radially outwardly of said first membrane contact.

4. The membrane switch of claim 3, wherein said intermediate flexing area is radially between said first and second membrane contacts.

5. The membrane switch of claim 1, wherein a button is formed on said membrane in a generally center location, said button providing an operator with a location to apply said first and second actuation forces.

6. The membrane switch of claim 5, wherein said first membrane contact is aligned with a center of said button.

7. The membrane switch of claim 1, wherein said first and second circuit contacts are mounted on a printed circuit board.

8. The membrane switch of claim 1, wherein said membrane further includes

an upper actuation surface;

and

a coaxial, lower actuation surface circumscribing said upper actuation surface below said upper actuation surface, said intermediate flexing area extending between said upper actuation surface and said lower actuation surface, such that said first actuation force acts on said upper actuation surface and said second actuation force acts on said lower actuation surface.

9. A membrane switch comprising:

a printed circuit board including

a first open circuit mounted thereon, said first open circuit including a pair of spaced first circuit contacts; and

a second open circuit mounted thereon, said second open circuit including a pair of spaced second circuit contacts;

a membrane including

an upper actuation surface;

a coaxial, lower actuation surface circumscribing said upper actuation surface below said upper actuation surface;

center, intermediate, and outer flexing areas, said intermediate flexing area extending between said upper actuation surface and said lower actuation surface, said center flexing area is radially inward of said intermediate flexing area, and said outer flexing area extending radially outward from said lower actuation surface; and

first and second membrane contacts, said first membrane contact being coupled to the upper actuation surface via said center flexing area, said second membrane contact being coupled to said lower actuation surface, said membrane positioned upon said printed circuit board such that said first and second membrane contacts are aligned to complete said first and second circuits, said center, intermediate and outer flexing areas normally biasing said first and second membrane contacts out of contact with said first and second circuit contacts; and

a button is formed on said membrane adjacent said upper actuation surface, said button providing an operator with a location to apply first and second actuation forces, such that upon exerting said first actuation force on said button, said button transfers said first actuation force to said upper actuation surface flexing said intermediate flexing area and causing said first membrane contact to contact said first circuit contact closing said first circuit, and such that upon exerting said second actuation force on said button, said button transfers said second actuation force to said lower actuation surface flexing said center and outer flexing areas and causing said second membrane contact to contact said second circuit contact closing said second circuit.

10. A method of switching comprising the steps of:

providing a switch having a membrane having radially spaced center, intermediate, and outer flexing areas and a first and second membrane contacts, said membrane switch being positioned adjacent first and second circuit contacts for each of said first and second membrane contacts;

providing a first actuation force on said membrane flexing said intermediate flexing area and causing said first membrane contact to contact said first circuit contact; and

providing a second actuation force on said membrane flexing said center and outer flexing areas and causing said second membrane contact to contact said second circuit contact, and exerting a substantially normal force on said first membrane contact.