Input device and position determining method
First Claim
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1. A method of determining a contact position of an electrostatically chargeable object (22) on a contact plate (12) of an input device (10), the method comprising the process steps:
- measuring, by a measuring circuit (20) of the input device (10), an RC element with a sensing capacitor (Cf) formed by an electrical resistive layer (16) on a contact surface (14) of the contact plate (12) and the electrostatically chargeable object (22), and an ohmic resistance (Rn) between the contact position of the electrostatically chargeable object (22) and each one of at least two electrically conducting contacts (18) when the sensing capacitor (Cf) is fully electrically charged, the measuring comprising;
fully discharging the sensing capacitor (Cf) and the reference capacitor (CS);
fully charging the sensing capacitor (Cf);
equalizing charge between the sensing capacitor (Cf) and the reference capacitor (CS); and
measuring the voltage (US) across the reference capacitor (CS);
measuring, by the measuring circuit (20), the RC element for a charging duration (t) with the sensing capacitor (Cf) and an ohmic resistance (Rn) between the contact position of the electrostatically chargeable object (22) and each one of the electrically conducting contacts (18) when the sensing capacitor (Cf) is partially electrically charged, the measuring of the RC element for a charging duration (t) comprising;
fully discharging the sensing capacitor (Cf) and the reference capacitor (CS);
fully charging the sensing capacitor (Cf);
equalizing charge between the sensing capacitor (Cf) and the reference capacitor (CS); and
measuring the voltage (Us) across the reference capacitor (CS);
determining by a processing unit of the input device (10), the ohmic resistance (Rn) between the contact position of the electrostatically chargeable object (22) and each one of the at least two electrically conducting contacts (18) by measuring the corresponding RC element; and
determining, by the processing unit, coordinates (X, Y) of the contact position of the electrostatically chargeable object (22) by means of the ohmic resistances (Rn) between the contact position of the electrostatically chargeable object (22) and the electrically conducting contacts (18).
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Abstract
An input device (10) has a contact plate (12) having a contact surface (14) and being least partially coated with an electrical resistive layer (16) on a surface opposite the contact surface (14). The electrical resistive layer (16) has at least two electrically conducting contacts (18). A measuring circuit (20) is provided for measuring a sensing capacitor (24) formed by the electrical resistive layer (16) and an electrostatically chargeable object (22) arranged at a contact position on the contact surface (14). Further, a processing unit is provided for determining coordinates (X, Y) of the contact position of the electrostatically chargeable object (22) on the contact surface (14) by means of a determination of the ohmic resistances (Rn) between the contact position of the electrostatically chargeable object (22) and the electrically conducting contacts.
21 Citations
4 Claims
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1. A method of determining a contact position of an electrostatically chargeable object (22) on a contact plate (12) of an input device (10), the method comprising the process steps:
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measuring, by a measuring circuit (20) of the input device (10), an RC element with a sensing capacitor (Cf) formed by an electrical resistive layer (16) on a contact surface (14) of the contact plate (12) and the electrostatically chargeable object (22), and an ohmic resistance (Rn) between the contact position of the electrostatically chargeable object (22) and each one of at least two electrically conducting contacts (18) when the sensing capacitor (Cf) is fully electrically charged, the measuring comprising; fully discharging the sensing capacitor (Cf) and the reference capacitor (CS); fully charging the sensing capacitor (Cf); equalizing charge between the sensing capacitor (Cf) and the reference capacitor (CS); and measuring the voltage (US) across the reference capacitor (CS); measuring, by the measuring circuit (20), the RC element for a charging duration (t) with the sensing capacitor (Cf) and an ohmic resistance (Rn) between the contact position of the electrostatically chargeable object (22) and each one of the electrically conducting contacts (18) when the sensing capacitor (Cf) is partially electrically charged, the measuring of the RC element for a charging duration (t) comprising; fully discharging the sensing capacitor (Cf) and the reference capacitor (CS); fully charging the sensing capacitor (Cf); equalizing charge between the sensing capacitor (Cf) and the reference capacitor (CS); and measuring the voltage (Us) across the reference capacitor (CS); determining by a processing unit of the input device (10), the ohmic resistance (Rn) between the contact position of the electrostatically chargeable object (22) and each one of the at least two electrically conducting contacts (18) by measuring the corresponding RC element; and determining, by the processing unit, coordinates (X, Y) of the contact position of the electrostatically chargeable object (22) by means of the ohmic resistances (Rn) between the contact position of the electrostatically chargeable object (22) and the electrically conducting contacts (18). - View Dependent Claims (2, 3, 4)
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Specification
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Current AssigneeTRW Automotive Electronics & Components GmbH & Co. KG
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Original AssigneeTRW Automotive Electronics & Components GmbH & Co. KG
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InventorsBackes, Ulrich
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Primary Examiner(s)Breene, John
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Assistant Examiner(s)Islam, Mohammad
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Application NumberUS13/448,655Publication NumberTime in Patent Office1,694 DaysField of Search702/47, 702/52, 702/150US Class Current1/1CPC Class CodesG06F 3/0416 Control or interface arrang...G06F 3/0444 using a single conductive e...G06F 3/045 using resistive elements, e...
