Touch panel
First Claim
1. A touch panel device for determining the touch location at which a touch sensing surface of the device is touched comprising:
- signal generator means for producing an alternating-current voltage output;
transformer means having a primary winding means connected to the signal generator output so as to be driven by the signal generator means, the transformer means also having a secondary winding means with first and second secondary winding outputs and a center tap, the secondary winding means providing a panel scanning signal as the primary winding means is driven by the signal generator output;
switching means for selectively coupling the secondary winding means to the touch sensing surface so as to selectively apply the panel scanning signal to the touch sensing surface and generate touch current signals at the center tap upon touching of the panel; and
panel output signal processing means having a first input coupled to the center tap of the transformer means for receiving the touch current signals, the panel output signal processing means comprising means for determining the touch location from the touch current signals.
1 Assignment
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Accused Products
Abstract
A touch panel has panel scanning signals selectively applied to the four sides of a touch sensing surface of the panel so as to establish alternating current voltage gradients in desired directions across the touch sensing surface. When the panel is touched, touch currents result and are utilized by a touch location circuit in determining the location of touch. The impedance touch current resulting from a user'"'"'s touch may also be determined and used. The touch panel circuit automatically compensates for changes in impedance touch current, such as results when users touch the panel with ungloved and gloved fingers.
305 Citations
27 Claims
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1. A touch panel device for determining the touch location at which a touch sensing surface of the device is touched comprising:
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signal generator means for producing an alternating-current voltage output; transformer means having a primary winding means connected to the signal generator output so as to be driven by the signal generator means, the transformer means also having a secondary winding means with first and second secondary winding outputs and a center tap, the secondary winding means providing a panel scanning signal as the primary winding means is driven by the signal generator output; switching means for selectively coupling the secondary winding means to the touch sensing surface so as to selectively apply the panel scanning signal to the touch sensing surface and generate touch current signals at the center tap upon touching of the panel; and panel output signal processing means having a first input coupled to the center tap of the transformer means for receiving the touch current signals, the panel output signal processing means comprising means for determining the touch location from the touch current signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A touch panel device for determining the touch location at which a touch sensing surface of the device is touched comprising:
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signal generator means for producing an alternating-current voltage signal output; panel scanning signal applying means for applying panel scanning signals to the touch sensing surface, the panel scanning signal applying means having an input coupled to the signal generator output, the panel scanning signal applying means having first and second alternating-current voltage scanning outputs which are driven by the signal generator output and which are one hundred and eighty degrees out of phase from one another; switching means for selectively coupling the first and second panel scanning outputs to the touch sensing surface so as to selectively apply the panel scanning signals to the touch sensing surface and generate touch current signals upon touching of the panel, the switching means comprising means for selectively coupling one of the panel scanning outputs to a first side of the touch sensing surface and the other of the panel scanning outputs to a second side of the touch sensing surface, the second side being located across the touch sensing surface in a first direction from the first side, so as to establish a voltage gradient across the touch sensing surface in the first direction from the first to the second sides and so as to provide a first touch current signal output from the touch sensing surface, the switching means comprising means for selectively coupling one of the panel scanning outputs to a third side of the touch sensing surface and the other of the panel scanning outputs to a fourth side of the touch sensing surface, the fourth side being located across the touch sensing surface in a second direction from the first side, so as to establish a voltage gradient across the touch sensing surface in the second direction from the third to the fourth sides and so as to provide a second touch current signal output from the touch sensing surface when the touch sensing surface is touched, the switching means also comprising means for selectively and simultaneously coupling one of the panel scanning outputs to the first, second, third and fourth sides of the touch sensing surface so as to provide an impedance touch current signal output from the touch sensing surface when the touch sensing surface is touched; and panel output signal processing means having a first input for receiving the first, second and impedance touch current signals, the panel output signal processing means comprising means for determining the touch location from the first, second and impedance touch current signals. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A method of determining the touch location at which a touch sensing surface is touched comprising:
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simultaneously applying an alternating current voltage signal to each of the sides of the touch sensing surface and generating an impedance touch current signal when the touch sensing surface is touched; applying an alternating current voltage signal to the touch sensing surface to establish an alternating current voltage gradient across the touch sensing surface in a first direction from a first to a second side of the touch sensing surface and generating a first touch current signal when the touch sensing surface is touched; applying an alternating current voltage signal to the touch sensing surface to establishing an alternating current voltage gradient across the touch sensing surface in a second direction from a third to a fourth side of the touch sensing surface and generating a second touch current signal when the touch sensing surface is touched; and determining the touch location from the impedance, first and second touch current signals. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. A method of determining the touch location at which a touch sensing surface is touched comprising:
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establishing an alternating current voltage gradient across the touch sensing surface in a first direction from a first side to a second side of the touch sensing surface and generating a first touch current signal when the touch sensing surface is touched; establishing an alternating current voltage gradient across the touch sensing surface in a second direction opposite to the first direction from the second side to the first side of the touch sensing surface and generating a second touch current signal when the touch sensing surface is touched; establishing an alternating current voltage gradient across the touch sensing surface in a third direction from a third side to a fourth side of the touch sensing surface and generating a third touch current signal when the touch sensing surface is touched; establishing an alternating current voltage gradient across the touch sensing surface in a fourth direction opposite to the third direction from the fourth side to the third side of the touch sensing surface and generating a fourth touch current signal relative to ground potential when the touch sensing surface is touched; and determining the touch location from the first, second, third and fourth touch current signals.
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Specification