Membrane switch element with coated spacer layer

Claim 1

In a membrane switch element of the open-contact type adapted for combination with a keyboard having keys with a contact at their inboard end, the switch element including first and second conductive circuits spaced from one another, the improvement comprising: (1) a flexible plastic film substrate having a circuit panel carrying the first conductive circuit and a tail extending from the panel, the first conductive circuit including (i) a plurality of conductive contacts each having a first contact section and a second contact section electrically separated from each other, and (ii) a plurality of first conductive tracks extending along the circuit panel of the substrate and across the tail to the end thereof, each first contact section being connected to a first conductive track; (2) a first dielectric coating printed over the circuit panel of the film substrate in liquid form and cured to a solid coating in a pattern defining (i) a first uncoated zone surrounding each contact of the first conductive circuit, (ii) a second uncoated zone associated with each first uncoated zone, and (iii) a coated zone over the balance of the first conductive circuit; (3) a second conductive circuit on the surface of the first dielectric coating opposite from the film substrate and including a plurality of second conductive tracks extending across the dielectric coating and along the tail of the film substrate to the end thereof, each second contact section of the contacts of the first conductive circuit being electrically interconnected to a second conductive track within a second uncoated zone defined by the first dielectric coating; and (4) a second dielectric coating printed over the first dielectric coating in liquid form and cured to a solid coating in a pattern covering the second conductive circuit on the first dielectric coating and having uncoated zones in registry with the first uncoated zones.

Claim 5

A method for the manufacture of an open-contact membrane switch element comprising the steps of: (1) providing a flexible plastic film substrate having a circuit panel and a tail extending from an edge of the panel; (2) printing a first conductive circuit on the film substrate including (i) a plurality of conductive contacts each having a first contact section and a second contact section electrically separated from each other, and (ii) a plurality of first conductive tracks extending along the circuit panel of the substrate and across the tail to the end thereof, each first contact section being connected to a first conductive track; (3) printing a first dielectric coating over the circuit panel in a pattern defining (i) a first uncoated zone surrounding each contact of the first conductive circuit, (ii) a second uncoated zone associated with each first uncoated zone, and (iii) a coated zone covering the balance of the first conductive circuit, and thereafter curing the first dielectric coating to a solid coating; (4) printing a second conductive circuit on the first dielectric coating that includes a plurality of second conductive tracks extending across the first dielectric coating and along the tail of the film substrate to the end thereof and with each second contact section of the contacts of the first conductive circuit being electrically interconnected to a second conductive track within a second uncoated zone defined by the first dielectric coating; and (5) printing a second dielectric coating over the first dielectric coating in a pattern covering the second conductive circuit and the second uncoated zones and having uncoated zones in registry with the first uncoated zones.

Claim 6

A method for the manufacture of an open-contact membrane switch element comprising the steps of: (1) providing a flexible plastic film substrate having a circuit panel and a tail extending from an edge of the panel; (2) printing a first conductive circuit on the film substrate including (i) a plurality of conductive contacts each having a first contact section and a second contact section electrically separated from each other, and (ii) a plurality of first conductive tracks extending along the circuit panel of the substrate and across the tail to the end thereof, each first contact section being connected to a first conductive track; (3) printing a first dielectric coating over the circuit panel in a pattern defining (i) a first uncoated zone surrounding each contact of the first conductive circuit, (ii) a second uncoated zone associated with each first uncoated zone, and (iii) a coated zone covering the balance of the first conductive circuit, and thereafter curing the first dielectric coating to a solid coating; (4) printing a second conductive circuit on the first dielectric coating that includes a plurality of second conductive tracks extending across the first dielectric coating and along the tail of the film substrate to the end thereof and with each second contact section of the contacts of the first conductive circuit being electrically interconnected to a second conductive track within a second uncoated zone defined by the first dielectric coating; and (5) printing a second dielectric coating over the first dielectric coating in a pattern covering the second conductive circuit and the second uncoated zones and having uncoated zones in registry with the first uncoated zones.