DRIVE CONTROL CIRCUIT FOR LINEAR VIBRATION MOTOR

• US 20110279069A1
• Filed: 05/13/2011
• Published: 11/17/2011
• Est. Priority Date: 05/13/2010
• Status: Active Grant

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: ON Semiconductor Trading, Ltd (ON Semiconductor Corporation)
• Inventors: MURATA, Tsutomu
• Granted Patent: US 8,736,202 B2
• Time in Patent Office: Days
• US Class Current: 318/128
• CPC Class Codes: H02P 13/10 by moving core, coil winding, or shield, e.g. by induction regulator
• CPC Class Codes: H02P 25/06 Linear motors

Abstract

In a drive control circuit of a linear vibration motor, the drive signal generating unit generates a drive signal whose phase is opposite to that of the drive signal generated during the motor running, after the running of the linear vibration motor has terminated; this drive signal of opposite phase includes a high impedance period during which the driver unit is controlled to a high impedance state. An induced voltage detector detects an induced voltage occurring in the coil. A comparator has a function as a hysteresis comparator in which the output level does not vary in a predetermined dead band, and the comparator outputs a high-level signal or a low-level signal during the high impedance period. When an in-phase signal is consecutively outputted from the comparator during the consecutive high-impedance periods, the drive signal generating unit determines that the linear vibration motor has come to a stop.

Claims

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;

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; and

a comparator configured to compare the induced voltage detected by said induced voltage detector with a reference voltage used to detect a zero cross of the induced voltage,

wherein after a running of the linear vibration motor has terminated, said drive signal generating unit generates a drive signal whose phase is opposite to that of the drive signal generated during the vibration motor running, said drive signal of the opposite phase including a high impedance period during which said driver unit is controlled to a high impedance state,

wherein said induced voltage detector detects the induced voltage occurring in the coil during the high impedance period, and

wherein said comparator has a function as a hysteresis comparator in which an output level does not vary in a predetermined dead band, and said comparator outputs a high-level signal or a low-level signal during the high impedance period, and

wherein when an in-phase signal is consecutively outputted from said comparator during the consecutive high-impedance periods, said drive signal generating unit determines that the linear vibration motor has come to a stop.

2. A drive control circuit of a linear vibration motor according to claim 1, wherein during the linear vibration motor running, said drive signal generating unit generates a drive signal used to alternately deliver the positive current and the negative current to the coil with a nonconducting period inserted between conducting periods,

wherein said induced voltage detector detects the induced voltage occurring in the coil during the nonconducting period,

wherein said comparator detects a zero cross of the induced voltage detected by said induced voltage detector,

wherein during the linear vibration motor running, said drive signal generating unit has said comparator function as a non-hysteresis comparator having no dead band or has the dead band become narrower than that after the running of the linear vibration motor has terminated, and

wherein an eigen frequency of the linear vibration motor is estimated 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.

3. A drive control circuit of a linear vibration motor according to claim 1, wherein said drive signal generating unit adjusts the width of the dead band.

4. A drive control circuit of a linear vibration motor according to claim 2, wherein said drive signal generating unit adjusts the width of the dead band.

5. 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;

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; and

a comparator, configured to compare the induced voltage detected by said induced voltage detector with a reference voltage used to detect a zero cross of the induced voltage,

wherein after a running of the linear vibration motor has terminated, said drive signal generating unit generates a drive signal whose phase is opposite to that of the drive signal generated during the vibration motor running, said drive signal of the opposite phase including a high impedance period during which said driver unit is controlled to a high impedance state,

wherein said induced voltage detector detects the induced voltage occurring in the coil during the high impedance period, and

wherein said comparator has a function as a hysteresis comparator in which an output level does not vary in a predetermined dead band, and said comparator outputs a high-level signal or a low-level signal during the high impedance period, and

wherein when an in-phase signal is consecutively outputted from said comparator during a high-impedance period and the drive signal immediately before the high impedance period, said drive signal generating unit determines that the linear vibration motor has come to a stop.