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公开(公告)号：DE69920448D1
公开(公告)日：2004-10-28
申请号：DE69920448
申请日：1999-05-21
Applicant: QUALCOMM INC
Abstract: A method and circuit for processing switch closures in a passive network (100) having switches (S1 ... Sn). The passive network (100) generates an output voltage in response to a switch closure. The circuit comprises a comparison circuit (206), coupled to the passive network, for comparing the output voltage to a reference voltage. A decoder (212), coupled to the comparison circuit, decodes the switch closure if the output voltage is within a predetermined range, and does not decode said switch closure if the output voltage is not within the predetermined range. The circuit differentiates between input ranges in a passive network keypad which allows the proper processing of meaningful key presses, while ignoring inadvertent or superfluous key presses, thereby conserving power and processor time.
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公开(公告)号：DE69923343T2
公开(公告)日：2006-05-04
申请号：DE69923343
申请日：1999-11-12
Applicant: QUALCOMM INC
Inventor： CLAXTON D
Abstract: A method and apparatus for calibrating a resistive ladder switching matrix coupled to a keypad in a portable electronic device having a housing with a cover that may be positioned in an open state or a closed state. A first contact of a calibration element is coupled to a reference voltage and a second contact of the calibration element is coupled to ground by moving the cover from the open state to the closed state. When the first contact of the calibration element is coupled to the reference voltage and the second contact of the calibration element is coupled to ground, a calibration resistance across the calibration element is determined. The calibration resistance may correspond to an input impedance of the resistive ladder switching matrix when no buttons associated with the keypad are depressed. Signals from the resistive ladder switching network are calibrated when the cover is in the closed state in accordance with the calibration resistance.
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公开(公告)号：DE69920448T2
公开(公告)日：2005-09-22
申请号：DE69920448
申请日：1999-05-21
Applicant: QUALCOMM INC
Abstract: A method and circuit for processing switch closures in a passive network (100) having switches (S1 ... Sn). The passive network (100) generates an output voltage in response to a switch closure. The circuit comprises a comparison circuit (206), coupled to the passive network, for comparing the output voltage to a reference voltage. A decoder (212), coupled to the comparison circuit, decodes the switch closure if the output voltage is within a predetermined range, and does not decode said switch closure if the output voltage is not within the predetermined range. The circuit differentiates between input ranges in a passive network keypad which allows the proper processing of meaningful key presses, while ignoring inadvertent or superfluous key presses, thereby conserving power and processor time.
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公开(公告)号：DE69923343D1
公开(公告)日：2005-02-24
申请号：DE69923343
申请日：1999-11-12
Applicant: QUALCOMM INC
Inventor： CLAXTON D
Abstract: A method and apparatus for calibrating a resistive ladder switching matrix coupled to a keypad in a portable electronic device having a housing with a cover that may be positioned in an open state or a closed state. A first contact of a calibration element is coupled to a reference voltage and a second contact of the calibration element is coupled to ground by moving the cover from the open state to the closed state. When the first contact of the calibration element is coupled to the reference voltage and the second contact of the calibration element is coupled to ground, a calibration resistance across the calibration element is determined. The calibration resistance may correspond to an input impedance of the resistive ladder switching matrix when no buttons associated with the keypad are depressed. Signals from the resistive ladder switching network are calibrated when the cover is in the closed state in accordance with the calibration resistance.
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