Patent application number | Description | Published |
20080218107 | Motor Drive Unit and Electric Apparatus Having a Motor - A motor drive unit capable of detecting the position of a stationary rotor of any type of sensorless motor, determining a proper startup logic for the rotor, and starting up the motor in a stable condition. To do this, multiple stator coils of the sensorless motor are supplied with rotor-position detecting drive voltages that are adapted to vary the middle point voltage of the multiple stator coils but do not rotate the motor. The middle point voltage of the stator coils is compared with a detection reference voltage. When the result of the comparison matches one of predetermined detection logic patterns, a proper startup logic is generated in accordance with the position of the rotor specified by the matching detection logic pattern to start up the motor. Otherwise, the detection reference voltage is changed in level, and a new rotor-position detecting signal is generated to repeat the procedure for detecting the rotor position. | 09-11-2008 |
20080252238 | MOTOR DRIVE CIRCUIT - A pulse generation unit generates a PWM signal whose duty ratio changes according to a target torque of a motor. A back electromotive detection circuit compares a back electromotive voltage generated at a coil of the motor with a middle point voltage of the coil, and outputs a back electromotive detection signal that becomes high level at a timing of the zero crossing point. A phase adjustment unit compares phases of the back electromotive detection signal and a reference signal that becomes a predetermined level at a predetermined timing, and adjusts the duty ratio of the PWM signal by feedback so that the phase error becomes a minimum. A frequency adjustment unit adjusts the frequency of the PWM signal such that the frequency of the PWM signal becomes integral multiples of the frequency of the back electromotive detection signal. | 10-16-2008 |
20100177626 | MOTOR DRIVE CIRCUIT, METHOD, AND DISC DEVICE USING THE SAME - A back electromotive force detection circuit detects a zero-crossing point by comparing a back electromotive force Vu which occurs in at least one coil of a motor with a center tap voltage at a common node of the coils, and outputs a back electromotive force detection signal. A switching control circuit controls the switching states of multiple switching circuits based upon the back electromotive force detection signal, thereby adjusting the current flowing through the coils of the motor. A window generating circuit outputs a window signal at a predetermined level during a period obtained by multiplying the cycle of the back electromotive force detection signal by a predetermined coefficient before the detection of the zero-crossing point. The switching control circuit stops the switching operation of the switching circuit during a period in which the window signal is maintained at the predetermined level, thereby setting the state to the high impedance state that corresponds to a non-driving period. | 07-15-2010 |
20110090775 | MOTOR DRIVING CIRCUIT - An SPM driver drives a spindle motor. A VCM driver drives a VCM. A DC/DC converter (switching regulator) receives a power supply voltage from an external circuit, and generates a stabilized voltage. Linear regulators each receive a power supply voltage from an external circuit, and each generates a stabilized voltage. A shock detection circuit detects vibration of a device mounting the driving circuit. A power monitoring circuit monitors the power supply voltage, and generates a power-on reset signal which is switched to a predetermined level whenever the power supply voltage is cut off. An ADC converts the back electromotive voltage that occurs at the VCM into a digital signal. A serial interface receives data from an external host processor, which is used to control the driving circuit. Cutoff circuits are arranged between the capacitors, which are to be charged using the induced current that occurs at the SPM, and the power supply terminal. When the power supply voltage is cut off, each cutoff circuit disconnects the corresponding capacitor from the power supply terminal. | 04-21-2011 |
20130258515 | MOTOR DRIVE DEVICE, MAGNETIC DISK STORAGE DEVICE, AND ELECTRONIC APPLIANCE - A motor drive device has a driver circuit generating an output current for a motor and a control circuit controlling the drive circuit. The control circuit, when switching the driver circuit from a PWM-driving state to a linear-driving state, controls the timing of the switching such that the path of the output current does not change between before and after the switching, and in addition, in the middle of the switching, switches the driver circuit to a high-output-impedance state momentarily. | 10-03-2013 |
20140300987 | MOTOR DRIVE DEVICE, MAGNETIC DISK STORAGE DEVICE, AND ELECTRONIC DEVICE - A motor drive device has a spindle motor driver adapted to drive a spindle motor. the spindle motor driver includes lower side NMOSFETs, one for each phase, which connect and disconnect terminals, one for each phase, of the spindle motor to and from a ground terminal; a controller adapted to generate a switch control signal and a brake control signal; lower side pre-drivers, one for each phase, connected between an application terminal of an internal power supply voltage and the ground terminal and adapted to generate lower side gate signals, one for each phase, in accordance with the switch control signal to output the lower side gate signals to the lower side NMOSFETs, one for each phase; and a brake unit adapted to pull up to the internal power supply voltage all the lower side gate signals, one for each phase, in accordance with the brake control signal. | 10-09-2014 |
20140300992 | MOTOR DRIVE DEVICE, MAGNETIC DISK STORAGE DEVICE, AND ELECTRONIC DEVICE - A motor drive device has a spindle motor driver adapted to receive electric power from a power supply line to drive a spindle motor; an isolation switch adapted to connect and disconnect an application terminal of a power supply voltage to and from the power supply line, and a current monitor adapted to monitor a first current flowing into the isolation switch. The current monitor includes a mirror switch arranged to connect a first terminal of the mirror switch to the application terminal of the power supply voltage and adapted to be turned on and off by the same control signal as the isolation switch; a bias generator adapted to bias a second terminal of the mirror switch to the same voltage as the power supply line; a resistor which converts a second current flowing into the mirror switch into a first voltage; and a current limit signal generator adapted to compare at least one of the first voltage, a second voltage obtained by level-shifting the first voltage, and a third voltage obtained by dividing the first voltage with a predetermined threshold voltage to generate a current limit signal. | 10-09-2014 |
20140300993 | MOTOR DRIVE DEVICE, MAGNETIC DISK STORAGE DEVICE, AND ELECTRONIC APPLIANCE - A motor drive device has a motor driver adapted to receive a first power supply voltage to drive a motor; an internal regulator adapted to generate from an input voltage an internal power supply voltage; and a power supply switcher adapted to receive both the first power supply voltage and a second power supply voltage lower than the first power supply voltage to output, as the input voltage, the second power supply voltage when the second power supply voltage is normal and to output, as the input voltage, the first power supply voltage when the second power supply voltage is abnormal. | 10-09-2014 |