Coordinate input device and display device with the same
First Claim
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1. A capacitance detection device of a capacitance system, comprising:
- a first capacitor including a coordinate electrode for detecting a capacitance;
a power source for supplying electric charges to be charged in the first capacitor;
an electric charge storage capacitor in which charges to be charged therein changes according to the electric charges charged in the first capacitor;
the electric charge storage capacitor includes a first electrode which connects with the coordinate electrode and a second electrode which is opposed to the first electrode;
a first switch and a second switch for changing a reference potential of the second electrode of the electric charge storage capacitor; and
a second capacitor including the coordinate electrode and a conductor which touches the capacitance detection device;
wherein the first switch electrically connects between the second electrode of the electric charge storage capacitor and a first reference voltage;
wherein the second switch electrically connects between the second electrode of the electric charge storage capacitor and a second reference voltage;
further comprising an amplifier for detecting electric charges which are transferred from the coordinate electrode via a third switch,wherein the third switch directly connects between the coordinate electrode and the amplifier in order to transfer the electric charges,wherein the capacitance detection device is configured so that when the second reference voltage is applied to the second electrode of the electric charge storage capacitor a noise voltage of the coordinate electrode is reduced,wherein the reference potential of the electric charge storage capacitor is changed in a period of measuring the capacitance due to turning on of the first and second switch alternately,wherein the second switch is turned ON corresponding to a term comprising a start time and an end time in which the electric charges are transferred via the third switch, andwherein the third switch is configured to be turned ON at the same start time as the second switch during the term.
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Abstract
A capacitance detection device of a capacitance system includes: a capacitance sensor electrode for detecting a capacitance; a power source for supplying charges to be charged in the capacitance sensor electrode; an electric charge storage capacitor in which an amount of charges to be charged therein changes according to the electric charges charged in the capacitance sensor electrode; and a switch for changing a reference potential of the electric charge storage capacitor. The reference potential of the electric charge storage capacitor is changed in a period of measuring the capacitance.
15 Citations
12 Claims
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1. A capacitance detection device of a capacitance system, comprising:
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a first capacitor including a coordinate electrode for detecting a capacitance; a power source for supplying electric charges to be charged in the first capacitor; an electric charge storage capacitor in which charges to be charged therein changes according to the electric charges charged in the first capacitor; the electric charge storage capacitor includes a first electrode which connects with the coordinate electrode and a second electrode which is opposed to the first electrode; a first switch and a second switch for changing a reference potential of the second electrode of the electric charge storage capacitor; and a second capacitor including the coordinate electrode and a conductor which touches the capacitance detection device; wherein the first switch electrically connects between the second electrode of the electric charge storage capacitor and a first reference voltage; wherein the second switch electrically connects between the second electrode of the electric charge storage capacitor and a second reference voltage; further comprising an amplifier for detecting electric charges which are transferred from the coordinate electrode via a third switch, wherein the third switch directly connects between the coordinate electrode and the amplifier in order to transfer the electric charges, wherein the capacitance detection device is configured so that when the second reference voltage is applied to the second electrode of the electric charge storage capacitor a noise voltage of the coordinate electrode is reduced, wherein the reference potential of the electric charge storage capacitor is changed in a period of measuring the capacitance due to turning on of the first and second switch alternately, wherein the second switch is turned ON corresponding to a term comprising a start time and an end time in which the electric charges are transferred via the third switch, and wherein the third switch is configured to be turned ON at the same start time as the second switch during the term. - View Dependent Claims (2, 3, 4)
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5. An input coordinate detecting device of a capacitance system, comprising:
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a first capacitor including a coordinate electrode for detecting a capacitance; a power source for supplying electric charges to be charged in the first capacitor; an electric charge storage capacitor in which charges to be charged therein changes according to the electric charges charged in the first capacitor; the electric charge storage capacitor including a first electrode which connects with the coordinate electrode and a second electrode which is opposed to the first electrode; and a first and second switch for changing a reference potential of the second electrode of the electric charge storage capacitor, wherein the first switch electrically connects between the second electrode and a first reference voltage, wherein the second switch electrically connects between the second electrode and a second reference voltage, further comprising an amplifier for detecting electric charges which are transferred from the coordinate electrode via a third switch, wherein the third switch directly connects between the coordinate electrode and the amplifier in order to transfer the electric charges, wherein the coordinate detecting device is configured so that when the second reference voltage is applied to the second electrode of the electric charge storage capacitor a noise voltage of the coordinate electrode is reduced, wherein the reference potential of the electric charge storage capacitor is changed in a period of measuring the capacitance due to turning on of the first and second switch alternately, wherein the second switch is turned ON corresponding to a term comprising a start time and an end time in which the electric charges are transferred via the third switch, and wherein the third switch is configured to be turned ON at the same start time as the second switch during the term. - View Dependent Claims (6, 7, 8)
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9. A display device comprising:
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an LCD panel and a touch sensor panel, wherein the touch sensor panel includes a first transparent electrode facing the LCD panel, wherein the LCD panel includes a second transparent electrode facing the touch sensor panel, and wherein a capacitance is formed between the first and second transparent electrodes, wherein the touch panel sensor includes a capacitance detection device for detecting an input coordinate comprising; a first capacitor including a coordinate electrode for detecting a capacitance; a power source for supplying electric charges to be charged in the first capacitor; an electric charge storage capacitor in which charges to be charged therein changes according to the electric charges charged in the first capacitor; the electric charge storage capacitor including a first electrode which connects with the coordinate electrode and a second electrode which is opposed to the first electrode; and a first and second switch for changing a reference potential of the second electrode of the electric charge storage capacitor, wherein the first switch electrically connects between the second electrode and a first reference voltage, wherein the second switch electrically connects between the second electrode and a second reference voltage, further comprising an amplifier for detecting electric charges which are transferred from the coordinate electrode via a third switch, wherein the third switch directly connects between the coordinate electrode and the amplifier in order to transfer the electric charges, wherein the display device is configured so that when the second reference voltage is applied to the second electrode of the electric charge storage capacitor a noise voltage of the coordinate electrode is reduced, wherein the reference potential of the electric charge storage capacitor is changed in a period of measuring the capacitance due to turning on the first and second switch alternately, wherein the second switch is turned ON corresponding to a term comprising a start time and an end time in which the electric charges are transferred via the third switch, and wherein the third switch is configured to be turned ON at the same start time as the second switch during the term. - View Dependent Claims (10, 11, 12)
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Specification
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Current AssigneePanasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
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Original AssigneeJapan Display Incorporated, Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
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InventorsMamba, Norio, Nagata, Koji, Hayakawa, Koji, Anno, Kouichi, Kumagai, Toshiyuki, Furuhashi, Tsutomu, Kajiwara, Hisayoshi
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Primary Examiner(s)HARRIS, DOROTHY H
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Application NumberUS12/573,955Publication NumberTime in Patent Office2,478 DaysField of Search345173-174, 324/678, 324/686, 178/18.06US Class Current1/1CPC Class CodesG06F 1/3262 Power saving in digitizer o...G06F 3/0412 Digitisers structurally int...G06F 3/0418 for error correction or com...G06F 3/0446 using a grid-like structure...
