Motor drive circuit with short startup time

A motor drive circuit comprising:

• a switching circuit which includes a plurality of transistors connected to a coil of a motor that is to be driven, and adjusts power supplied to the coil by making the transistors perform a switching operation;
• at least one comparator which detects a position of a rotor of the motor and generates an FG (Frequency Generation) signal in accordance with the detected position;
• a pre-driver which drives the switching circuit based on, at least, the FG signal;
• and
• a selector which switches drive mode of the motor drive circuit based on a control signal inputted from outside;
• wherein
• the selector selects a first mode or a second mode when the control signal is a DC signal, and selects a third mode when the control signal is a pulse signal, and wherein
• (i) in the first mode, after commencing starting of the motor, a duty ratio of the pulse signal is set to 100% and, after that, the duty ratio is switched to a predetermined value in accordance with rotational frequency of the motor,
• (ii) in the second mode, the duty ratio of the pulse signal continues to be set to 100%;
• and
• (iii) in the third mode, the duty ratio and frequency of the pulse signal are set, based on a control signal of a pulse form inputted from outside.

A method of driving a motor, the method comprising:

• converting a Hall signal indicating position information of a rotor of the motor that is to be driven, into a rectangular signal;
• selecting, among transistors that constitute a H-bridge circuit connected to a coil of the motor, based on the rectangular signal, either group of two groups of transistor pairs disposed in opposing corners, to be driven;
• generating a pulse signal in a mode selected among three different modes;
• and
• driving the selected transistor pair based on the pulse signal;
• wherein
• the step of generating the pulse signal,
• in a first mode, after commencing starting of the motor, sets a duty ratio of the pulse signal to 100%, and after that, sets the duty ratio to a predetermined value in accordance with rotational frequency of the motor,
• in a second mode, continues to set the duty ratio to 100%, and
• in a third mode, sets the duty ratio and frequency of the pulse signal, based on a control signal of a pulse form, which is inputted from outside.

A method of driving a motor, the method comprising:

• detecting a position of a rotor of the motor that is to be driven, and generating an FG (Frequency Generation) signal in accordance with the detected position;
• adjusting power supplied to a coil of the motor, by controlling ON and OFF states of a plurality of transistors connected to the coil of the motor that is to be driven, based on, at least the FG signal;
• and
• switching drive mode based on a control signal inputted from outside;
• wherein
• a first mode or a second mode is selected when the control signal is a DC signal, and a third mode is selected when the control signal is a pulse signal, and wherein
• (iv) in the first mode, after commencing starting of the motor, a duty ratio of the pulse signal is set to 100% and, after that, the duty ratio is switched to a predetermined value in accordance with rotational frequency of the motor,
• (v) in the second mode, the duty ratio of the pulse signal continues to be set to 100%;
• and
• (vi) in the third mode, the duty ratio and frequency of the pulse signal are set, based on a control signal of a pulse form inputted from outside.

A drive circuit of a vibration motor, the circuit comprising:

• a H-bridge circuit connected to a coil of the vibration motor that is to be driven;
• a comparator which receives a Hall signal indicating position information of a rotor of the vibration motor, and converts the signal into a rectangular signal;
• a pulse modulator which generates a pulse-modulated pulse signal specifying energization time of the coil of the vibration motor;
• and
• a pre-driver which drives the H-bridge circuit based on the pulse signal and the rectangular signal;
• wherein
• the pulse modulator is configured to enable switching between
• a first mode in which, after commencing starting of the motor, a duty ratio of the pulse signal is set to 100% and, after that, the duty ratio is switched to a predetermined value in accordance with rotational frequency of the motor;
• a second mode in which the duty ratio of the pulse signal continues to be set to 100%;
• and
• a third mode in which the duty ratio and frequency of the pulse signal are set, based on a control signal of a pulse form inputted from outside.

An electronic device comprising:

• a communication unit which communicates with a base station;
• and
• a motor unit;
• wherein when a messages arrives from the base station, the communication unit prescribes rotation of the vibration motor, to the motor unit, and wherein the motor unit comprises:
• a vibration motor;
• a Hall element which outputs a Hall signal indicating position information of a rotor of the vibration motor;
• and
• the drive circuit which drives the vibration motor based on the Hall signal,
• and wherein the drive circuit comprises
• a vibration motor;
• a Hall element which outputs a Hall signal indicating position information of a rotor of the vibration motor;
• and
• a drive circuit configured to drive the vibration motor, the drive circuit comprising:
• a H-bridge circuit connected to a coil of the vibration motor that is to be driven;
• a comparator which receives a Hall signal indicating position information of a rotor of the vibration motor, and converts the signal into a rectangular signal;
• a pulse modulator which generates a pulse-modulated pulse signal specifying energization time of the coil of the vibration motor;
• and
• a pre-driver which drives the H-bridge circuit based on the pulse signal and the rectangular signal;
• wherein
• after commencing start-up of the vibration motor, the pulse modulator sets a duty ratio of the pulse signal to 100%, and after that, switches the duty ratio to a predetermined value in accordance with rotational frequency of the vibration motor.