Title: Mode tracking transducer driver for non-linear transducer
Application Number: 97197666 Application Date: 1997.08.20
Publication Number: 1230320 Publication Date: 1999.09.29
Approval Pub. Date: 2003.09.03 Granted Pub. Date: 2003.09.03
International Classifi-cation: G08B5/22;H04Q1/00;H04R25/00
Applicant(s) Name: Motorola Inc. Address:
Inventor(s) Name: James Gregory Mittel;John M. Mckee;Darrell Curtis
Attorney & Agent: zhang wei
Abstract:
    A mode tracking transducer driver (100) for a non-linear electromagnetic transducer (102) includes a voltage controlled oscillator (104) coupled within a phase lock loop to a transducer driver (106) and a mode detector (112, 108). The voltage controlled oscillator (104) generates a variable frequency output signal, and is responsive to a frequency control signal for controlling the frequency of the output signal. The transducer driver (106) generates a transducer drive signal (502) which is coupled to the non-linear electromagnetic transducer (102) to generate a tactile alert. The mode detector (112, 108) detects a mode change between at least the first operating mode and the second operating mode of the non-linear electromagnetic transducer (102), and in response thereto generates the frequency control signal (118) which establishes a quasi-resonant frequency (204) at which the tactile energy delivered by the non-linear electromagnetic transducer (102) is maximized.
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