Patent ID: 8829843
Filing Date: 2014-09-09
Classification: H02P

Abstract:
1. A drive control circuit of a linear vibration motor, having a stator and a vibrator at least one of which is constituted by an electromagnet, which vibrates the vibrator relative to the stator by supplying a drive current to a coil of the electromagnet, the drive control circuit comprising: a drive signal generating unit configured to generate a drive signal used to alternately deliver a positive current and a negative current to the coil with an nonconducting period inserted between conducting periods; a driver unit configured to generate the drive current in response to the drive signal generated by said drive signal generating unit so as to supply the drive current to the coil; an induced voltage detector configured to detect an induced voltage occurring in the coil during the nonconducting period; and a zero-cross detecting unit configured to detect a zero cross of the induced voltage detected by said induced voltage detector, wherein said drive signal generating unit estimates an eigen frequency of the linear vibration motor based on a detected position of the zero cross thereof, and the frequency of the drive signal is brought close to the estimated eigen frequency, and wherein said drive signal generating unit calculates a difference between an end position of each cycle of the drive signal and a detection position of the zero cross to be associated with the end position and adds the calculated difference to a cycle width of the present drive signal so as to adaptively control the cycle width of the drive signal.