Tactile touch switch panel

• US 4,127,752 A
• Filed: 10/13/1977
• Issued: 11/28/1978
• Est. Priority Date: 10/13/1977
• Status: Expired due to Term

• Current Assignee: Sheldahl, Inc.
• Original Assignee: Sheldahl, Inc.
• Inventors: Lowthorp, Blaine G.
• Primary Examiner(s): Scott, James R.
• Application Number:
  US05/841,931
• Time in Patent Office: 411 Days
• Field of Search: 200/1 R, 200/5 R, 200/5 A, 200/86 R, 200/67 DB, 200/159 R, 200/159 B, 200/275, 200/302, 200/308, 200/340
• US Class Current: 200/5.00A
• 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 2209/08 with memory properties
• CPC Class Codes: H01H 2215/008 Part of substrate or membrane
• CPC Class Codes: H01H 2217/01 Off centre actuation
• CPC Class Codes: H01H 2227/002 Layer thickness
• CPC Class Codes: H01H 2227/022 Collapsable dome
• CPC Class Codes: H01H 2231/05 Card, e.g. credit card
• CPC Class Codes: H01H 2237/008 Plunger guided by flexible arms

Abstract

A touch panel diaphragm-type switch array providing improved tactile feedback. A rigid substrate having a printed circuit conductor pattern thereon, with the pattern defining a plurality of switch locations, each including first and second separate electrical contacts is provided and superimposed thereover is a spacer having apertures in registration with the electrical contact pairs. Sandwiched between the substrate and the spacer is a thin layer of a suitable plastic material which is deformed in the areas defined by the apertures in the spacer to define dome-shaped projections surrounded by an annular ring. A bridging conductor is disposed on the underside of the dome-shaped projections. "Spider" members are supported by the side walls of the apertures and are disposed between the outer side of the dome-shaped projections and a flexible plastic cover layer which is affixed to the top side of the spacer layer. The cover layer is imprinted with indicia to visually define the switch positions. Depression of the cover layer with a finger acts through the spider to invert the dome to thereby bring the bridging conductor into electrical engagement with the first and second switching contacts on the substrate. A positive feel is imparted to the finger as the dome inverts and the electrical contact is established.

Claims

1. A tactile feedback electrical switch assembly for intermittently altering the electrical condition of normally spaced apart conductors and comprising:

(a) base pad means for receiving and retaining said electrical switching assembly thereon;

(b) a first insulative film having means insulatively mounting a plurality of spaced apart electrical switching conductors upon said base pad means with mutally adjacent conductors of said electrical switching conductor forming a pair of switch contacts;

(c) a tactile layer having a plurality of dome-shaped projections formed therein with said layer being arranged for mounting upon said base pad means in superimposed relationship with said first insulative film, and with each of said dome-shaped projections being in substantial registration with one discrete pair of switch contacts on said first insulative film and with an electrical conductor bridging contact area on the inner surface of said tactile layer within said dome and in substantial registration with said contacts; and

(d) said dome-shaped projection comprising a generally parabolic disc with a raised center portion and an annular ring projecting upwardly and outwardly from the edge of said parabolic disc, said annular ring joining said parabolic disc along a generally circular transition line, said transition line normally being located at the apex of an angle which is generally acute from the upper surface of said dome-shaped projection and wherein the upper surface of said parabolic disc extends above that of said annular ring, the arrangement being such that upon depression of said parabolic disc, said annular ring functions as a hinge for accommodating inversion of said parabolic disc and resultant contact between said bridging contact and said switch contacts.

2. The tactile feedback electrical switch assembly as in claim 1 and further including:

(a) a spacer layer of a predetermined thickness and having a plurality of apertures formed therethrough, said spacer layer being disposed on said first insulative film on said base pad, each of said apertures being in registration with individual ones of said bridging contact areas and each containing one of said plurality of dome-shaped projections.

3. The device as in claim 2 and further including:

(a) a second flexible insulative film having indicia marked thereon in a predetermined orientation defining a plurality of switch positions, said second film being affixed to the upper surface of said spacer layer with said switch positions being in registration with corresponding apertures in said spacer layer.

4. The device as in claim 3 and further including:

(a) a plurality of rigid members each having radially extending flexible projections, said rigid members being individually disposed between the outer top surfaces of said parabolic discs and the inner surface of said second flexible insulative film, said radially extending flexible projections supportively engaging the side walls of said apertures formed in said spacer layer, to provide tactile feedback to the finger of an operator depressing said second flexible insulative film in the area of said switch positions.

5. Apparatus as in claim 4 wherein said radially extending flexible projections comprise:

(a) thin, flexible strips extending outwardly and downwardly from said rigid members, adjacent ones of said strips being substantially at right angles to one another.

6. Apparatus as in claim 4 wherein said radially extending flexible projections comprise:

(a) a plurality of concentric circles of material surrounding said rigid member; and

(b) a plurality of thin, flexible strips of the same material extending radially from said rigid member joining said concentric circles to one another and to said rigid member.

7. Apparatus as in claim 1 wherein said tactile layer comprises a third insulating film having a conductive coating on at least a portion of said inner surface of said third insulating film within said dome.