Drive control circuit for linear vibration motor
View Patent ↗In a drive control circuit of a linear vibration motor, a differential amplifier circuit includes an operational amplifier in which an P-channel type transistor is used as a transistor that receives an input voltage, and the differential amplifier circuit detects an induced voltage occurring in a coil. Before the H-bridge circuit is controlled to a high impedance state, a drive signal generating unit turns on a first transistor and a second transistor, and delivers a regenerative current through the coil, the first transistor, the second transistor and the power supply potential.
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;
an H-bridge circuit configured to generate a drive current according to the drive signal generated by said drive signal generating unit so as to supply the drive current to the coil; and
a differential amplifier circuit configured to detect an induced voltage occurring in the coil wherein said differential amplifier circuit includes an operational amplifier in which an P-channel type transistor is used as a transistor that receives an input voltage,
said H-bridge circuit including:
a first P-channel type transistor connected between one end of the coil and a power supply potential;
a first N-channel type transistor connected between the one end of the coil and a ground potential;
a second P-channel type transistor connected between the other end of the coil and the power supply potential; and
a second N-channel type transistor connected between the other end of the coil and the ground potential,
wherein before said H-bridge circuit is controlled to a high impedance state, said drive signal generating unit turns on the first P-channel type transistor and the second P-channel type transistor, turns off the first N-channel type transistor and the second N-channel type transistor, and delivers a regenerative current through the coil, the first P-channel type transistor, the second P-channel type transistor and the power supply potential.
2. A drive control circuit of a linear vibration motor according to claim 1 , 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, and supplies said drive signal of the opposite phase to said H-bridge circuit,
said drive signal of the opposite phase including a high impedance period during which said H-bridge circuit is controlled to a high impedance state.
3. A drive control circuit of a linear vibration motor according to claim 2 , further comprising a hysteresis comparator configured to compare the induced voltage detected by said differential amplifier circuit with a reference voltage used to detect a zero cross of the induced voltage,
wherein said hysteresis 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 hysteresis comparator during the consecutive high-impedance periods, said drive signal generating unit determines that the linear vibration motor has come to a stop.
4. 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;
an H-bridge circuit configured to generate a drive current according to the drive signal generated by said drive signal generating unit so as to supply the drive current to the coil; and
a differential amplifier circuit configured to detect an induced voltage occurring in the coil wherein said differential amplifier circuit includes an operational amplifier in which an N-channel type transistor is used as a transistor that receives an input voltage,
said H-bridge circuit including:
a first P-channel type transistor connected between one end of the coil and a power supply potential;
a first N-channel type transistor connected between the one end of the coil and a ground potential;
a second P-channel type transistor connected between the other end of the coil and the power supply potential; and
a second N-channel type transistor connected between the other end of the coil and the ground potential,
wherein before said H-bridge circuit is controlled to a high impedance state, said drive signal generating unit turns on the first N-channel type transistor and the second N-channel type transistor, turns off the first P-channel type transistor and the second P-channel type transistor, and delivers a regenerative current through the coil, the first N-channel type transistor, the second N-channel type transistor and the ground potential.
5. A drive control circuit of a linear vibration motor according to claim 4 , 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, and supplies said drive signal of opposite phase to said H-bridge circuit,
said drive signal of the opposite phase including a high impedance period during which said H-bridge circuit is controlled to a high impedance state.
6. A drive control circuit of a linear vibration motor according to claim 5 , further comprising a hysteresis comparator configured to compare the induced voltage detected by said differential amplifier circuit with a reference voltage used to detect a zero cross of the induced voltage,
wherein said hysteresis 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 hysteresis comparator during the consecutive high-impedance periods, said drive signal generating unit determines that the linear vibration motor has come to a stop.