Analog touch screen with coating for inhibiting increased contact resistance
First Claim
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1. An analog touch screen, comprising:
- a top transparent layer disposed over a bottom transparent layer, the top layer comprising a flexible sheet having a layer of a semiconductive ceramic coated on a lower face thereof, and the bottom transparent layer comprising a substrate sheet having a thin layer of a semiconductive ceramic coated on an upper face thereof;
a non-electrically conductive spacer interposed between the top and bottom layers effective for spacing apart the layers of semiconductive ceramic except when the top layer is flexed by an external touch so that electrical contact occurs between the semiconductive layers at a location where the touch occurred;
a noncontinuous, electrically conductive metallic film which in use does not form an appreciable amount of an insulating oxide, the film covering at least one of the layers of semiconductive ceramic so that the film is interposed between the semiconductive layers during electrical contact caused by a touch, the metallic film being of a thickness effective to reduce the effects of repeated operation on contact resistance over many operating cycles of the touch screen without substantially varying the sheet resistance of the underlying semiconductive ceramic layer; and
conductors connected to the transparent layers for applying an electrical current to the semiconductive layers to determine the horizontal and vertical position of the external touch on the top layer.
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Accused Products
Abstract
Analog resistance touch switches and matrix type touch switches have contacts coated with a very thin film, which in use does not form an appreciable amount of an insulating oxide, to inhibit changes in contact resistance and extend operating life.
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Citations
17 Claims
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1. An analog touch screen, comprising:
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a top transparent layer disposed over a bottom transparent layer, the top layer comprising a flexible sheet having a layer of a semiconductive ceramic coated on a lower face thereof, and the bottom transparent layer comprising a substrate sheet having a thin layer of a semiconductive ceramic coated on an upper face thereof; a non-electrically conductive spacer interposed between the top and bottom layers effective for spacing apart the layers of semiconductive ceramic except when the top layer is flexed by an external touch so that electrical contact occurs between the semiconductive layers at a location where the touch occurred; a noncontinuous, electrically conductive metallic film which in use does not form an appreciable amount of an insulating oxide, the film covering at least one of the layers of semiconductive ceramic so that the film is interposed between the semiconductive layers during electrical contact caused by a touch, the metallic film being of a thickness effective to reduce the effects of repeated operation on contact resistance over many operating cycles of the touch screen without substantially varying the sheet resistance of the underlying semiconductive ceramic layer; and conductors connected to the transparent layers for applying an electrical current to the semiconductive layers to determine the horizontal and vertical position of the external touch on the top layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification