Capacitance switch

Claim 2

A membrane capacitance switch comprising: a substrate sheet, a flexible sheet extending over said substrate sheet, a conductive contact carried by one of said substrate sheet and said flexible sheet, a capacitance spacing element carried by the other of said substrate sheet and said flexible sheet and located alongside and spaced from said conductive contact, said capacitance spacing element comprising an inner insulating layer and outer conductive portions, whereby said flexible sheet may be flexed to vary the spacing of said conductive contact and said capacitance spacing element.

Claim 3

The membrane capacitance switch of claim 1 in which are provided a plurality of conductive contacts and in which an integral capacitance spacing element extends over said plurality.

Claim 4

The membrane capacitance switch of claim 1 in which said capacitance spacing element comprises a layer of plastic and said outer conductive portions comprise layers of metal.

Claim 5

The membrane capacitance switch of claim 3 in which said plastic is polyester.

Claim 6

The membrane capacitance switch of claim 4 in which said metal is sputtered aluminum.

Claim 7

The membrane capacitance switch of claim 1 in which said capacitance spacing element is carried by said substrate.

Claim 8

The membrane capacitance switch of claim 6 in which said capacitance spacing element is secured with respect to said substrate by means of a layer of adhesive.

Claim 9

The membrane capacitance switch of claim 7 in which a spacer lies between said flexible sheet and said substrate and in which said capacitance spacing element is bent around said spacer at an end thereof.

Claim 10

The membrane capacitance switch of claim 8 in which said capacitance spacing element is adhered to said spacer on the. side of said spacer away from said substrate.

Claim 11

The membrane capacitance switch of claim 8 in which said flexible sheet carries a contact pad engaging said capacitance spacing element on its face away from said substrate.

Claim 12

ll. The membrane capacitance switch of claim 1 comprising a plurality of said capacitance spacing elements, each thereof extending over a plurality of conductive contacts.

Claim 13

The membrane capacitance switch of claim 8 in which a conductive element extends along said bent portion and to a second conductive contact carried by one of said substrate sheet and said flexible sheet.

Claim 14

The switch of claim 1 in which said inner insulating layer and said outer conductive portions are integral.

Claim 15

A capacitance-type switch in which an electrically integral capacitance spacing layer extends through a plurality of switch zones, and is separately movable in a switching direction at each of said switch zones.

Claim 16

A capacitance-type switch in which an electrically integral capacitance spacing layer extends through a plurality of switch zones, and is separately movable in a switching direction at each of said switch zones.

Claim 17

A capacitance switch comprising: a substrata sheet, a flexible sheet extending over said substrate sheet, a conductive contact carried by one of said substrate sheet and said flexible sheet, a capacitance spacing element carried by the other of said substrate sheet and said flexible sheet and located alongside and spaced from said conductive contact, said capacitance spacing element comprising an inner insulating layer and outer conductive portions, whereby said flexible sheet may be flexed to vary the spacing of said conductive contact and said capacitance spacing element, in which a spacer lies between said flexible sheet and said substrate and in which said capacitance spacing element is bent around said spacer in a fold portion at an end thereof, said spacer being centrally spaced from said fold portion.

Claim 18

A capacitance switch comprising: a substrata sheet, a flexible sheet extending over said substrate sheet, a conductive contact carried by one of said substrate sheet and said flexible sheet, a capacitance spacing element carried by the other of said substrate sheet and said flexible sheet and located alongside and spaced from said conductive contact, said capacitance spacing element comprising an inner insulating layer and outer conductive portions, whereby said flexible sheet may be flexed to vary the spacing of said conductive contact and said capacitance spacing element, in which a spacer lies between said flexible sheet and said substrate and in which said capacitance spacing element is bent around said spacer in a fold portion at an end thereof, said spacer being centrally spaced from said fold portion.

Claim 19

The switch of claim 15 in which said spacer comprises adhesive material.

Claim 20

The switch of claim 16 in which said spacer is . centrally semi-circularly relieved adjacent said fold portion.

Claim 21

The switch of claim 17 in which the transverse edges of the end of said spacer including said relieved portion of said spacer engages said fold portion.

Claim 22

The capacitance switch of claim 1 or claim 14 which has one capacitance value in an activated condition and a different capacitance value in a deactivated condition, the circuitry comprising a source supplying a first clock node and a second clock node with two-state electrical pulses 180° out of phase, first and second switch connection nodes for connecting a switching element in said capacitance switch to said circuitry, a buffer having an input connected to'said first switch connection node, and providing an output signal depending upon the condition at said buffer input relative to a threshold value, means connected between said clock nodes and said switch connection nodes for responding to the capacitance associated with one condition of said switch by maintaining said buffer input at a condition relative to said threshold value of said buffer and for responding to a capacitance associated with another condition of said switch by permitting the condition at said buffer input to vary sufficiently to cause the output of said buffer to vary with said two-state pulses, and a frequency detector connected to said buffer, to determine which condition said capacitance switch is in.

Claim 23

The circuitry of claim 19 wherein said means connected between said clock nodes and switch connection nodes comprises a first high impedance path between said first clock node and said first switch connection node, a-second high impedance path between said second clock node and said second switch connection node, a first unidirectional, low impedance path between said first clock node and said first switch connection node, and a. second unidirectional, low impedance path between said second clock node and said second switch connection node, one said low impedance path permitting current flow to its respective switch connection node and the other said low impedance path permitting current flow away from the other said switch connection node.

Claim 24

The circuitry of claim 20 wherein said frequency detector comprises a resistor connected at one end to an output of said buffer and at the other end to a gate input, a detecting capacitor, and means for draining said capacitor when the output signal of said buffer is low.

Claim 25

The circuitry of claim 21 wherein said high impedance paths are resistors and said unidirectional low impedance paths are diodes.

Claim 26

The circuitry of claim 21 or 22 wherein said means for draining is a diode connected to said buffer output.

Claim 27

The circuitry of claim 19 wherein said switch contains a row with a plurality of switching elements, each having a conductive pad electrically common with pads of the other switches and a pad having its own conductor isolated from conductors for other switching elements, and said circuit contains a first switch connection, buffer, means connected between clock nodes and switch connection nodes, and frequency detector for each said switching element in said row.

Claim 28

The circuitry of claim 24 wherein said switch includes a plurality of rows of said switching elements resulting in an X by Y matrix of switching elements, and said circuit contains a second said switch connection, a buffer, means connected between clock nodes and switch connection-nodes, and a frequency detector for each said row.

Claim 29

A capacitance switch comprising a substrate, a first conductive contact carried by said substrate, a flexible sheet extending over said substrate, a second conductive contact carried by said flexible sheet and aligned with and ordinarily spaced from said first contact, a capacitance spacing element carried by one of said substrate and said flexible sheet, located other than directly under or above said contacts, said capacitance spacing element comprising an inner insulating layer and outer conductive portions, one said conductive portion being electrically connected to one said contact, and first means for connection of the other said contact and the other said conductive portion to external circuitry, whereby said flexible sheet may be flexed to vary the spacing between said contacts to increase the capacitance of said switch.

Claim 30

A capacitance switch comprising a substrate, a first conductive contact carried by said substrate, a flexible sheet extending over said substrate, a second conductive contact carried by said flexible sheet and aligned with and ordinarily spaced from said first contact, a capacitance spacing element carried by one of said substrate and said flexible sheet, located other than directly under or above said contacts, said capacitance spacing element comprising an inner insulating layer and outer conductive portions, one said conductive portion being electrically connected to one said contact, and first means for connection of the other said contact and the other said conductive portion to external circuitry, whereby said flexible sheet may be flexed to vary the spacing between said contacts to increase the capacitance of said switch.

Claim 31

The switch of claim 26 further comprising a third contact carried by the other of said substrate and said flexible sheet that said capacitance spacing element is carried by, said third contact being electrically connected to second means for connection to external circuitry and being aligned with and ordinarily spaced from said conductive portion not electrically connected to said first means for connection to external circuitry, whereby said flexible sheet may be flexed to vary the 1 spacing between said third contact and said capacitance spacing element.

Claim 32

The switch of claim 27 further comprising a fourth contact carried, connected, and positioned similarly to said third contact and spaced from said third contact.

Claim 33

The switch of claim 28 further comprising a plurality of said capacitance spacing elements and fifth contacts associated with said plurality of capacitance spacing elements, some of said fifth contacts being aligned with and ordinarily spaced from conductive portions of said plurality of capacitance spacing elements, some of said fifth contacts being aligned in ordinarily spaced pairs and being remotely located from but electrically connected to their associated capacitance spacing elements.

Claim 34

The switch of claim 29 wherein said contacts are arranged in positions corresponding to positions of typewriter keys, said capacitance elements being aligned with rows of said typewriter key positions.

Claim 35

The switch of claim 30 wherein sixth contacts are provided and arranged in pairs in positions corresponding to positions of numerical computation keys,.said sixth contacts being located remotely on said switch from said contacts having positions corresponding to said positions of typewriter keys, one said contact of each said pair being electrically connected to a conductive p or- tion of a capacitance spacing element aligned with a corresponding typewriter row.

Claim 36

The switch of claim 26 wherein an end of said capacitance spacing element is folded over in the direction away from the sheet that carries it, and said other said conductive portion is in electrical communication with a conductor carried by the sheet that said spacing element is not carried by, whereby all conductors comprising electrical connections to external circuitry can be carried by a single sheet.

Claim 37

The switch of claim 32 wherein another end of said capacitance spacing element is folded over in the direction toward the sheet that carries it, and said one conductive portion is in electrical communication with a conductor carried by the sheet and electrically connected to said one contact.