US4634818A — Switches and keyboards

Claim 1

Independent Claim 275 words

A keypad consisting of a combined cover and membrane (15) of resiliently deformable material and a substrate (10) bearing open-circuit conductors (12, 13) against which substrate (10) of the combined cover and membrane (15) is positioned with otherwise unsupported integral touch pads (14) disposed in an array and each raised from the surrounding membrane (15) by an angled wall (30) arranged so that finger pressure on any touch pad (14) depresses it until a conductive surface (29) on the underside of the touch pad (14) contacts the substrate (10) and makes the circuit between the conductors (12, 13), characterized in that: (a) each touch pad (14) and the surrounding membrane (15) are relatively thick and the wall (30) is relatively thin, and the thickness and angle of the wall are such that each touch pad (14) can be depressed without deflecting the surrounding membrane (15); (b) the length of each wall (30) between the membrane and the associated touch pad is relatively small in comparison with the width of the associated touch pad (14) and each wall (30) is arranged to give way through an over-center position to give a tactile sensation; and (c) each conductive surface (29) occupies most of the width of the associated touch pad (14), the conductive surface (20) being convex with a radius of curvature selected in relation to the length and angle of the wall (30) and the touch pad (14) size (φB) and travel so that the conductive surface (29) makes face to face contact with the substrate (10) over the full range of angles to which the touch pad (14) tilts when the finger pressure is asymmetric.

Claim 2

Dependent Claim 275 words

A keypad consisting of a combined cover and membrane (15) of resiliently deformable material and a substrate (10) bearing open-circuit conductors (12, 13) against which substrate (10) of the combined cover and membrane (15) is positioned with otherwise unsupported integral touch pads (14) disposed in an array and each raised from the surrounding membrane (15) by an angled wall (30) arranged so that finger pressure on any touch pad (14) depresses it until a conductive surface (29) on the underside of the touch pad (14) contacts the substrate (10) and makes the circuit between the conductors (12, 13), characterized in that: (a) each touch pad (14) and the surrounding membrane (15) are relatively thick and the wall (30) is relatively thin, and the thickness and angle of the wall are such that each touch pad (14) can be depressed without deflecting the surrounding membrane (15); (b) the length of each wall (30) between the membrane and the associated touch pad is relatively small in comparison with the width of the associated touch pad (14) and each wall (30) is arranged to give way through an over-center position to give a tactile sensation; and (c) each conductive surface (29) occupies most of the width of the associated touch pad (14), the conductive surface (20) being convex with a radius of curvature selected in relation to the length and angle of the wall (30) and the touch pad (14) size (φB) and travel so that the conductive surface (29) makes face to face contact with the substrate (10) over the full range of angles to which the touch pad (14) tilts when the finger pressure is asymmetric.

Claim 3

Dependent Claim 108 words

A keypad according to claim 1, wherein the ratio of the width of the wall (30) to the width (φB) of the touch pad (14) is about 0.1, ratio of the width of the conductive surface (29) to the width (φB) of the touch pad (14) is about 0.8, the radius of curvature of the convex conductive surface (29) is about 2.6 φC wherein φC is the width between the locations where opposed parts of wall (30) join the membrane (15) and the conductive surface (29) is a moulded-in disc of elastomer that is a harder material than the material of the membrane (15) and touch pads (14).

Claim 4

Dependent Claim 52 words

A keypad according to any preceding claim, wherein the membrane (15) is moulded slightly under the size of the substrate (10) and has a peripheral lip (16) into which edges of the substrate (10) locate to maintain the membrane (15) in position against the substrate (10) and to tension the membrane (15).

Claim 5

Dependent Claim 28 words

A keypad according to claim 3, wherein retaining studs (20, 21) project from the underside of the membrane (15) and located in through holes in the substrate (10).

Claim 6

Dependent Claim 30 words

A keypad according to claim 1 or 2, wherein the substrate (10) is a printed circuit board formed with an array of interdigitated contact fingers under each touch pad (14).

Claim 7

Dependent Claim 24 words

A keypad according to claim 1 or 2, wherein the visible face of each touch pad (14) is individually colored or marked for identification.

Claim 8

Dependent Claim 16 words

A keypad according to claim 1 or 2, wherein the membrane (15) is of transluscent material.

Claim 9

Dependent Claim 238 words

A two component keypad consisting of a combined cover and membrane (15) of resiliently deformable material and a substrate (10) bearing open-circuit conductors (12, 13) against which substrate (10) of the combined cover and membrane (15) is positioned with otherwise unsupported integral touch pads (14) disposed in an array and each raised from the surrounding membrane (15) by an angled wall (30) arranged so that finger pressure on any touch pad (14) depresses it to contact the substrate (10) and makes the circuit between the conductors (12, 13), characterized in that: (a) each touch pad (14) and the surrounding membrane (15) are relatively thick and the wall (30) is relatively thin and the thickness and angle of the wall are such that each touch pad (14) can be depressed without deflecting the surrounding membrane (15); (b) the length of each wall (30) between the membrane and the associated touch pad is relatively small in comparison with the width of the associated touch pad (14); (c) the gap between the substrate (10) and the undersurface (29) of the touch pad is no greater than the thickness of the surrounding membrane (15); and (d) the dimensions and angle of each wall (30) relative to the touch pad (14) and the membrane (15) are such that irrespective of the angle to which the touch pad (14) tilts the wall (30) gives way through an over-center position to give a tactile sensation.

Claim 10

Dependent Claim 238 words

A two component keypad consisting of a combined cover and membrane (15) of resiliently deformable material and a substrate (10) bearing open-circuit conductors (12, 13) against which substrate (10) of the combined cover and membrane (15) is positioned with otherwise unsupported integral touch pads (14) disposed in an array and each raised from the surrounding membrane (15) by an angled wall (30) arranged so that finger pressure on any touch pad (14) depresses it to contact the substrate (10) and makes the circuit between the conductors (12, 13), characterized in that: (a) each touch pad (14) and the surrounding membrane (15) are relatively thick and the wall (30) is relatively thin and the thickness and angle of the wall are such that each touch pad (14) can be depressed without deflecting the surrounding membrane (15); (b) the length of each wall (30) between the membrane and the associated touch pad is relatively small in comparison with the width of the associated touch pad (14); (c) the gap between the substrate (10) and the undersurface (29) of the touch pad is no greater than the thickness of the surrounding membrane (15); and (d) the dimensions and angle of each wall (30) relative to the touch pad (14) and the membrane (15) are such that irrespective of the angle to which the touch pad (14) tilts the wall (30) gives way through an over-center position to give a tactile sensation.

Claim 11

Dependent Claim 108 words

A keypad consisting of a circuit-bearing substrate and a membrane of resiliently deformable material having a plurality of raised dome keys moulded therein each defined by a dome wall and a touch pad at the top of the wall, the gap between the substrate and a conductive undersurface of each integral touch pad being no greater than the thickness of the membrane, and the thickness and angle of each dome wall relative to the touch pad and the membrane being such that irrespective of the angle to which the touch pad tilts the wall gives way to give a change in tactile sensation immediately before contact is made.

Claim 12

Dependent Claim 108 words

A keypad consisting of a circuit-bearing substrate and a membrane of resiliently deformable material having a plurality of raised dome keys moulded therein each defined by a dome wall and a touch pad at the top of the wall, the gap between the substrate and a conductive undersurface of each integral touch pad being no greater than the thickness of the membrane, and the thickness and angle of each dome wall relative to the touch pad and the membrane being such that irrespective of the angle to which the touch pad tilts the wall gives way to give a change in tactile sensation immediately before contact is made.

Claim 13

Dependent Claim 39 words

A keypad as claimed in claim 9, wherein the membrane and touch pad are of substantially the same thickness and the conductive undersurface is convex and disposed no higher than the line of the top surface of the membrane.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1990-01-05	1990-07-07	1991-01-06	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1994-01-05	1994-07-07	1995-01-06	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1998-01-05	1998-07-07	1999-01-06	$7700.00	Window Closed / Lapsed

Switches and keyboards

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