Touch sensitive flat panel display
First Claim
Patent Images
1. A touch sensitive liquid crystal display (LCD) system comprising:
- a plurality of LCD elements, each of said elements having a corresponding charge time which changes when an external touch is applied to said element by a user;
means for selectively applying a charge to each of said LCD elements in said plurality;
means for monitoring a voltage across each of said LCD elements in said plurality and for using said voltage to compare said charge time of each of said LCD elements to a reference charge time value; and
means, responsive to said means for monitoring, for determining which, if any, of said LCD elements in said plurality are currently being touched by a user, based on said comparison.
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Abstract
The present invention relates to a touch sensitive LCD flat panel display. The display allows a user to provide input into a computer device by simply touching an LCD display screen with a passive device, such as a finger, stylus, or a ball point pen. The invention includes circuitry which continuously compares the charge times of the liquid crystal elements of the display to a reference value and uses the results of the comparison to determine which elements in the display are currently being touched.
252 Citations
41 Claims
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1. A touch sensitive liquid crystal display (LCD) system comprising:
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a plurality of LCD elements, each of said elements having a corresponding charge time which changes when an external touch is applied to said element by a user; means for selectively applying a charge to each of said LCD elements in said plurality; means for monitoring a voltage across each of said LCD elements in said plurality and for using said voltage to compare said charge time of each of said LCD elements to a reference charge time value; and means, responsive to said means for monitoring, for determining which, if any, of said LCD elements in said plurality are currently being touched by a user, based on said comparison. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A liquid crystal display (LCD) system comprising:
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a plurality of LCD elements, said LCD elements including; a front transparent plate having a first surface and a second surface, said first surface having a front electrode disposed adjacent thereto; a rear transparent plate positioned substantially parallel to, and in fixed relation to, said front transparent plate, said rear transparent plate having a rear electrode disposed adjacent to a first surface thereof, said first surface of said rear transparent plate facing said first surface of said front transparent plate so that said front electrode is substantially opposite said rear electrode; and a layer of liquid crystal material between said first surface of said front transparent plate and said first surface of said rear transparent plate, said layer capable of changing optical properties when a predetermined voltage is applied across said front and rear electrodes; wherein at least one of said LCD elements has a capacitance which chances when a user touches said second surface of said front transparent plate; means for determining whether said second surface of said front transparent plate is being touched by a user based on said chance in capacitance; and means, operatively connected to said front transparent plate, for increasing the change in capacitance of said LCD element when said second surface of said front transparent plate is touched by a user so that said means for determining is more sensitive to the touch of a user. - View Dependent Claims (30, 31, 32, 33)
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34. In an LCD display system having a display screen including a plurality of LCD display elements arranged in rows and columns, said LCD system capable of displaying an image on said display screen by providing predetermined voltages to said LCD elements in said plurality, an apparatus for detecting the touch of a user on said display screen while an image is being displayed, said apparatus comprising:
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means for alternately charging and discharging said display elements in a subgroup of said plurality of display elements; means for comparing a charge time of each of said display elements in said subgroup to a reference charge time value; and means for processing the results of said comparison to determine which, if any, of said display elements in said subgroup are being touched; where in said LCD display elements in said plurality which are not in said subgroup continuously display an image on said display screen. - View Dependent Claims (35, 36, 37, 38, 39, 40)
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41. A method for sensing an external touch on a liquid crystal display (LCD), said method comprising the steps of:
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providing an array of LCD elements, each of said LCD elements having an associated charge time value which changes when an external touch is applied to a surface of said element; selectively applying a charge to each of said LCD elements in said array; comparing a charge time of each of said LCD elements to a reference charge time value; and determining whether one or more of said LCD elements in said array is being touched based on the results of said comparing step.
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Specification