SENSING CIRCUIT DISCHARGE CONTROL METHOD AND DEVICE FOR TOUCH PANEL
First Claim
1. A sensing circuit discharge control method, the sensing circuit comprising a sensing electrode and a discharging unit, the sensing electrode having a capacitance when no touch event occurs, while the capacitance increasing when a touch event occurs, the discharging unit having a first current source and a second current source, said method comprising:
- providing a clock having a clock period;
setting a current level for the first current source;
setting a value P, a discharging duration of the first current source being defined as P times the clock period;
charging the sensing electrode;
discharging the sensing electrode by the first current source with the set current level and discharging duration;
discharging the sensing electrode by the second current source until discharge of the sensing electrode is completed;
determining whether the discharge of the sensing electrode is completed within a predetermined duration; and
adjusting the value P to adjust the discharging duration of the first current source if it is determined that the discharge of the sensing electrode is failed to be completed within the predetermined duration.
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Accused Products
Abstract
A sensing circuit discharge control method and device for a touch panel are disclosed. A discharging duration of a current source in the sensing circuit of the touch panel is fine tuned in a digital control manner, so as to control the discharging amount of the sensing circuit without frequently adjusting the discharging current of the current source. By using the present invention, discharging time difference between a condition in which a touch event occurs and a condition in which no touch event occurs for each sensing circuit can approach the same.
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Citations
17 Claims
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1. A sensing circuit discharge control method, the sensing circuit comprising a sensing electrode and a discharging unit, the sensing electrode having a capacitance when no touch event occurs, while the capacitance increasing when a touch event occurs, the discharging unit having a first current source and a second current source, said method comprising:
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providing a clock having a clock period; setting a current level for the first current source; setting a value P, a discharging duration of the first current source being defined as P times the clock period; charging the sensing electrode; discharging the sensing electrode by the first current source with the set current level and discharging duration; discharging the sensing electrode by the second current source until discharge of the sensing electrode is completed; determining whether the discharge of the sensing electrode is completed within a predetermined duration; and adjusting the value P to adjust the discharging duration of the first current source if it is determined that the discharge of the sensing electrode is failed to be completed within the predetermined duration. - View Dependent Claims (2, 3, 4, 5)
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6. A sensing circuit discharge control device, the sensing circuit comprising a sensing electrode and a discharging unit, the sensing electrode having a capacitance when no touch event occurs, while the capacitance increasing when a touch event occurs, the discharging unit further having a first current source and a second current source for discharging the sensing electrode in turn after the sensing electrode has been charged, and a discharging current level of the first current source is much greater than that of the second current source, said device comprising:
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an edge detector for detecting when discharge of the sensing electrode is completed; a main controller for setting a value P to set a discharging duration of the first current source, which is P times a clock period, instructing the sensing electrode to be charged, instructing the first current source to discharge the sensing electrode with a set current level and the set discharging duration, instructing the second current source to discharge the sensing electrode until a discharge of the sensing electrode is completed and determining if the discharge of the sensing electrode is completed within a predetermine duration according to an output of the edge detector; and a duration controller for adjusting the discharging duration of the first current source by adjusting the value P if the main controller determines that the discharge of the sensing electrode has failed to be completed within the predetermined duration. - View Dependent Claims (7, 8, 9, 10)
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11. A touch panel comprising:
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a plurality of sensing circuits, each sensing circuit comprising; a sensing electrode having a capacitance when no touch event occurs, the capacitance increasing when a touch event occurs; and a discharging unit having a first current source and a second current source for discharging the sensing electrode in turn after the sensing electrode is charged, a current level of the first current source being much greater than that of the second current source; and a sensing circuit discharge control device comprising; an edge detector for detecting when discharge of the sensing electrode is completed; a main controller for setting a value P to set a discharging duration of the first current source, which is P times a clock period, instructing the sensing electrode to be charged, instructing the first current source to discharge the sensing electrode with a set current level and the set discharging duration, instructing the second current source to discharge the sensing electrode until discharge of the sensing electrode is completed and determining if the discharge of the sensing electrode is completed within a predetermine duration according to an output of the edge detector; and a duration controller for adjusting the discharging duration of the first current source by adjusting the value P if the main controller determines that the discharge of the sensing electrode is failed to be completed within the predetermined duration. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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Specification