Display device having unpatterned touch detection
First Claim
1. In a touch-responsive display device having a faceplate, the improvement comprisingA. at least a first electrode disposed on the faceplate at a known relative location along at least a first direction,B. an electrically-conductive coating on said faceplate connected in circuit with said coating and extending continuously therefrom along at least said first direction, said coating presenting to said first electrode an electrical impedance responsive to the relative location along said first direction of a capacitive touch of the faceplate, andC. measuring means for applying an impedance-measuring signal of selected character to said electrode, and for responding to the response of said electrical impedance of said faceplate coating to said measuring signal for identifying the location along said first direction relative to said electrode of a capacitive touch of the faceplate.
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Accused Products
Abstract
A display device locates a touch anywhere on a conductive display faceplate by measuring plural electrical impedances of the faceplate conductive coating. The impedances are at electrodes located on different edges of the faceplate. A touch locating circuit determines the location of a touch using known pulsed signals and, in another embodiment, using a tuned measuring signal.
189 Citations
22 Claims
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1. In a touch-responsive display device having a faceplate, the improvement comprising
A. at least a first electrode disposed on the faceplate at a known relative location along at least a first direction, B. an electrically-conductive coating on said faceplate connected in circuit with said coating and extending continuously therefrom along at least said first direction, said coating presenting to said first electrode an electrical impedance responsive to the relative location along said first direction of a capacitive touch of the faceplate, and C. measuring means for applying an impedance-measuring signal of selected character to said electrode, and for responding to the response of said electrical impedance of said faceplate coating to said measuring signal for identifying the location along said first direction relative to said electrode of a capacitive touch of the faceplate.
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17. In a touch-responsive display device having a faceplate, the improvement comprising
A. an unpatterned electrically-conductive coating on said faceplate, B. at least first and second conductive electrodes connected with the faceplate coating and disposed at known different locations thereon, each electrode having presented thereto by said faceplate coating an electrical impedance responsive to the relative distance therefrom of a capacitive touch of the faceplate, and C. means for identifying the spacing of a capacitive touch of the faceplate coating relative to said electrodes, said spacing-identifying means including (i) means for applying an impedance-measuring. signal of selected character to each said electrode, (ii) means responsive to the response of the electrical impedance of the faceplate coating at each electrode to said measuring signal, and (iii) means for comparing to a reference condition the response of said coating impedance at each said electrode to said measuring signal.
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18. A method for locating a capacitive touch to a display-device faceplate, said method comprising the steps of
A. providing at least one electrode at a known relative location on the faceplate, B. providing an electrically-conductive coating on the faceplate connected with said electrode and extending therefrom continuously along at least a first direction, said coating presenting to said electrode an electrical impedance responsive to the relative location along said first direction of a capacitive touch of the faceplate, C. providing a reference measure of said electrical impedance presented to said electrode in response to an electrical signal applied thereto in the absence of any touch, D. providing a further measure of said electrical impedance presented to said electrode in response to an electrical signal applied thereto when a touch is present, and E. identifying the location of said touch along said first direction relative to said one electrode in response to a comparison of said reference and further measures.
Specification