JP2005182878A - Magnetic disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic disk device capable of saving a magnetic head due to an emergency situation when power fails. <P>SOLUTION: The magnetic disk device is provided with: a 1st driving circuit 2 for supplying a driving current to a 1st motor 1 for driving the magnetic disk to rotate; a 2nd driving circuit 4 for supplying a driving current to a 2nd motor 3 for controlling the magnetic head position; a power source change-over circuit 6 for changing over the power source to the 2nd motor 3; and a power source change-over switch means 15 controlled by the power supply source change-over circuit 6. In the connection terminal where the maximum voltage is induced among two or more motor coils in the 1st motor 1 at the time of cutting off the current to the 1st and 2nd driving circuits 2 and 4, the current to be supplied to the 2nd motor 2 is made constant by fixing the induced voltage, the remaining current is supplied as the brake current to halt the 1st motor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a magnetic disk device including a drive circuit that rotationally drives a magnetic disk and a drive circuit that controls the position of a magnetic head.

  In magnetic disk devices, when the power supply circuit is shut down due to an accident such as a human malfunction or a power failure, a technology to urgently retract the magnetic head has been used to protect the data stored in the magnetic disk. Yes. In such an emergency, since the power supply from the power supply source cannot be expected, various ideas have been made.

  Hereinafter, an example of a conventional emergency evacuation circuit for a magnetic head will be described with reference to the drawings.

  FIG. 4 is a block diagram for explaining a conventional magnetic disk apparatus.

  In FIG. 4, 1 is a spindle motor for rotating the magnetic disk, 1-1 to 1-3 are motor coils in the spindle motor 1, 2 is a spindle motor drive circuit, and 3 is a voice coil for driving the magnetic head. Motor, 4 is a drive circuit for voice coil motor, 5 is a power supply monitoring circuit for monitoring the state of the power supply source, and 6 is a supply for switching the power supply to the second motor by transmitting a retract command signal in an emergency. A power supply switching circuit, 15a and 15b are supply power supply switching means for performing a switching operation in conjunction with the save command signal, and 7 is a rectifier circuit for rectifying the terminal voltages of the motor coils 1-1 to 1-3.

  In the magnetic disk apparatus having the above-described configuration, when the magnetic disk apparatus performs a normal operation, the power supply selector switches 15a and 15b are set to the state of the contact a, and the voice coil motor drive circuit 4 is connected to the voice coil motor 3. A drive current is applied to perform position control for setting the magnetic head at a predetermined position on the magnetic disk. On the other hand, the spindle coil motor drive circuit 2 outputs three-phase drive signals to the connection terminals 10, 11 and 12 of the spindle motor 1, and the drive signals are sent to the motor coils 1-1, 1-2 and 1-3, respectively. Given. Each drive signal is a signal having an electrical angle of 120 °, and the drive signals are sequentially given to the spindle motor 1, and the spindle motor 1 controls the rotation of the magnetic disk. The input terminals of the rectifier circuit 7 are connected to the connection terminals 10, 11, 12 of the spindle motor 1, but the b contacts of the power supply changeover switch means 15a, 15b connected to the output terminals thereof are in an open state. For this reason, the rectifier circuit 7 does not become a load of the drive circuit 2.

  The power supply monitoring circuit 5 monitors the state of the power supply voltage Vcc, and when the power supply voltage supplied from a power supply source (a circuit that rectifies the commercial power supply voltage and outputs a DC voltage) is a normal value, the emergency evacuation is performed. Without sending a command signal, the power supply selector switches 15a and 15b are always set to the a contact state. Should the power supply voltage Vcc supplied to the drive circuit 2, the drive circuit 4 and the power supply switching circuit 6 be interrupted by a power failure or the like, an emergency evacuation command signal is output from the power supply monitoring circuit 5, and the power supply switching circuit 6 switches the power supply changeover switch means 15a, 15b to the b-contact side and cuts off the drive current supplied from the drive circuit 2 to the spindle motor 1. At this time, the rotation speed of the spindle motor 1 gradually decreases due to the influence of the inertial force, and each of the motor coils 1-1 to 1-3 has a sinusoidal waveform while the spindle motor 1 continues to rotate. A three-phase back electromotive force is generated. The rectifier circuit 7 rectifies the three-phase voltage generated and outputs the rectified output to the rectifier circuit output terminal 18. Then, the rectified output is supplied to the voice coil motor 3 through the supply voltage changeover switch means 15a and 15b, and the emergency retraction operation of the magnetic head is performed.

  FIG. 3 is a diagram showing the characteristics of a conventional magnetic disk device, where (a) is the power supply voltage, (b) is the maximum counter electromotive voltage, (c) is the current supplied to the second motor when the power is shut off, e) shows the voltage of the second motor connection terminal 16.

  In the conventional example of FIG. 5, since the relay 19 for two circuits must be used to switch the connection circuit of the voice coil motor 3, it becomes necessary to use a large relay having a large allowable current value. As a result, the relay 19 having a specification in which the DC resistance of the relay coil 19-1 is small and the driving current is large is used, and the capacity value of the capacitor 21 needs to be increased in order to secure the current.

  The mechanical switching operation cannot avoid the wear of the contacts of the changeover switch, has a problem in reliability, and the use of a large relay or capacitor is disadvantageous in cost.

  An object of the present invention is to solve the problems of the prior art and provide a magnetic disk device capable of urgently retracting a magnetic head at the time of a power failure without using an electrolytic capacitor for storing a power supply voltage for the time of the power failure. is there.

  In order to achieve the above object, a magnetic disk apparatus according to the present invention is driven by a first drive circuit that applies a drive current to a first motor that rotationally drives the magnetic disk, and a second motor that controls the position of the magnetic head. A second drive circuit for supplying a current, and driving the second motor to retract the magnetic head to protect the magnetic head when the power is shut off, and supplying a brake current to the first motor. The magnetic disk is controlled to stop rotating.

  The magnetic disk apparatus of the present invention also includes a first drive circuit that applies a drive current to a first motor that rotationally drives the magnetic disk, and a second that applies a drive current to a second motor that controls the position of the magnetic head. Connected to a plurality of motor coils of the first motor, a power supply switching circuit for switching the power supply to the second motor, a power supply changeover switch means controlled by the power supply switching circuit First to third input terminals and an output terminal connected to the power supply changeover switch means, and when the supply to the first drive circuit and the second drive circuit is cut off, the first The induced voltage is fixed at the input terminal, which is the maximum among the induced voltages generated in the plurality of motor coils of the motor, the current supplied to the second motor is constant, and the remaining current is set to the first Be one and supplying a braking current to stop over data, it is possible to retract the magnetic head in a short time and less power when the power is cut off.

  According to the magnetic disk device of the present invention, even if the power supply circuit is interrupted due to a power failure or an unexpected accident, the maximum voltage of a plurality of phases generated by the first motor is output and the maximum voltage is kept constant. Since the remaining energy can be supplied as a current for stopping the first motor, the magnetic head can be retracted at an early stage and the spindle motor can be stopped.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram for explaining an embodiment of a magnetic disk apparatus of the present invention.

  In FIG. 1, 1 is a spindle motor for rotating the magnetic disk, 1-1, 1-2, 1-3 are motor coils in the spindle motor 1, 2 is a spindle motor drive circuit, and 3 is a magnetic head. Voice coil motor to be driven, 4 is a drive circuit for the voice coil motor, 5 is a power supply monitoring circuit, 6 is a power supply switching circuit, 10, 11 and 12 are motor coils 1-1 to 1-3 of each phase of the spindle motor 1. Is connected to the input terminal of the power supply switching circuit 6, 13 is a control terminal of the power supply switching circuit 6, 14 is an output terminal of the power supply switching circuit 6, and 7 is used to supply power for driving the voice coil motor during emergency evacuation. The rectifier circuit 15 including the six diodes 7a to 7f includes a voice coil motor drive circuit 4 that is connected to the voice coil motor drive circuit 4 based on the emergency evacuation command given from the power supply switching circuit 6. Separately from Rumota 3, a changeover switch which connects the rectifier circuit 7 to the voice coil motor 3.

  Here, the first motor is specifically the spindle motor 1, which has motor coils 1-1 to 1-3, and is supplied from the spindle motor drive circuit 2 which is the first drive circuit. It rotates according to the drive current, and rotates a magnetic disk (not shown).

  The first drive circuit 2 has three, three, and ten-phase output ends of 10, 11 and 12, and each motor coil 1 of the first motor 1 receives drive currents having different electrical angles by 120 ° from the respective output ends. -1 to 1-3.

  Specifically, the second motor 3 is a linear motor such as the voice coil motor 3 and has a winding 3-1 from the voice coil motor drive circuit 4 as the second drive circuit. The position of the magnetic head is controlled according to the drive current. The second drive circuit 4 applies a DC drive current to both ends of the winding 3-1 of the second motor 3.

  The above configuration is the same as in the prior art, and the normal operation in which the power supply Vcc is applied to the first and second drive circuits 2 and 4 operates in the same manner as in the conventional example.

  Further, a power supply monitoring circuit 5 and a power supply switching circuit 6 are provided. The power supply monitoring circuit 5 is coupled to a power supply line for supplying a power supply voltage Vcc to the first and second drive circuits 2 and 4. A control signal that operates when the voltage Vcc is cut off is generated, and the control signal is output to the control terminal 13. When a positive power supply voltage is used, a low level output signal is enabled, and when a negative power supply voltage is used, a high level output signal is enabled. More specifically, if a potential level equivalent to the ground potential or a current flowing toward the ground potential is used as an output signal, the power supply monitoring circuit 5 that cannot expect supply of a power supply voltage when operating is used as an emergency evacuation control signal. Can be output stably.

  Next, the power supply switching circuit 6 has a control terminal 13, first, second and third input terminals 10, 11, 12 and a first output terminal 14, and includes first to third inputs. Terminals 10 to 12 are individually connected to the plurality of motor coils 1-1 to 1-3 in the first motor 1, further connected to the power supply switching circuit 6, and the control terminal 13 is connected to the power supply monitoring circuit 5. A control signal that operates when the power supply voltage Vcc of the first and second drive circuits 2 and 4 is cut off is input from the output terminal of the power supply monitoring circuit 5.

  The first output terminal 14 is connected to a changeover switch, and each switch element 15a, 15b of the changeover switch 15 is switched to the position of the contact a, and when the power supply voltage Vcc is cut off, the switch is switched to the position of the contact b.

  The magnetic disk device of this embodiment configured as described above operates as follows.

  In a normal operation in which the power supply voltage Vcc is applied to the power supply terminals of the first and second drive circuits 2 and 4, the first drive circuit 2 is connected to the motor coils 1-1 and 1-2 of the first motor 1. , 1-3 is given a three-phase drive current having an electrical angle of 120 °, the first motor 1 is rotated by a rotating magnetic field generated by the drive current, and the magnetic disk is driven to rotate. Then, the second drive circuit 4 gives a drive current to both ends of the winding 3-1 of the second motor 3 and performs control to set the magnetic head at a predetermined position. At this time, since the power supply monitoring circuit 5 does not give a control signal to the control terminal 13 of the supply power supply switching circuit 6, each switch element 15a, 15b of the changeover switch 15 is in the position of the contact a and the voice coil motor drive circuit 4 Driven by.

  The operation for urgently retracting the magnetic head when the power supply voltage Vcc is interrupted will be described below.

  When the power supply voltage Vcc applied to the power supply terminals of the first and second drive circuits 2 and 4 is cut off, the output current of the first drive circuit 2 and the output current of the second drive circuit 4 are cut off. Then, the rotation of the first motor 1 tries to stop. However, the first motor 1 that has been rotating until then continues to rotate for a while with the force of inertia, and during that period, an electromotive force is generated at the terminal feeling of the motor coils 1-1, 1-2, and 1-3. To do. This electromotive force is a sinusoidal AC signal having an electrical angle of 120 ° for each phase of 10, 11, and 12, and as the time passes, the reference potential of the AC signal and the power supply voltage VCC are cut off and near the ground potential. However, when the potential drops to a certain potential, the internal impedance of the first drive circuit 2 becomes higher, gradually approaching the ground potential from there, and finally becomes the ground potential.

  On the other hand, the power supply monitor 5 outputs a control signal that becomes active when the power supply voltage Vcc falls below about half of the normal voltage, and supplies the control signal to the control terminal 13 to the power supply switching circuit 6. As the control signal, it is convenient to make it active at a low level (ground potential) in order to operate under an operating condition in which the power supply voltage Vcc is not supplied.

  Considering the ground potential as a reference, the potentials of the wirings U, V, and W coupled between the first drive circuit 2 and the first motor 1 rise and fall within the power supply voltage range over time. However, the potential of one of the wirings is the highest and the potential of the other two wirings is lower than that.

  For example, if the potential of the wiring U is higher during the period of 0 ° to 120 ° in electrical angle, the potential of the wiring V is the highest during the next 120 ° (120 ° to 240 °) period, and the next 120 °. In the period of (240 ° to 360 °), the potential of the wiring W is the highest, and then the potential of the wiring U becomes the highest again.

  The induced voltage generated in the plurality of motor coils of the first motor 1 is rectified by the rectifier circuit 7 and supplied to the winding 3-1 as emergency evacuation power, and a current IL flows through the winding 3-1. At this time, the winding 3-1 has a resistance component RL, and the diode voltage Vf is generated by the rectifying elements 7a, 7c, 7e, so that the output terminals 10, 11, 12 of the first motor 1 are used. Is fixed at a voltage determined by IL × RL + Vf.

  The induced voltage is supplied to the second motor 3 through the rectifier circuit 7 to urgently retreat the magnetic head and suppress the generated energy, whereby the first motor 1 can be stopped early.

  FIG. 2 is a characteristic diagram of the magnetic disk device of this embodiment, where (a) is the power supply voltage, (b) is the maximum counter electromotive voltage, and (c) is the current supplied to the second motor when the power is shut off. A current obtained by adding a brake current for stopping the first motor, (d) indicates a voltage of the second motor connection terminal 16.

  The present invention is applied to a magnetic disk device, and is particularly effective when applied to a magnetic disk device having a function of urgently retracting a magnetic head when the power is shut down due to an unexpected accident such as a power failure.

1 is a block diagram showing a configuration of a magnetic disk device according to an embodiment of the present invention. Characteristic diagram of magnetic disk device of this embodiment Characteristics of conventional magnetic disk drive Block diagram showing the configuration of a conventional magnetic disk device Block diagram showing a configuration that is a problem of a conventional magnetic disk device

Explanation of symbols

1 First motor (spindle motor)
2 First drive circuit (for spindle motor)
3 Second motor (voice coil motor)
4 Second drive circuit (for voice coil motor)
DESCRIPTION OF SYMBOLS 5 Power supply monitoring circuit 6 Supply power supply switching circuit 7 Rectifier circuit 7a-7f Rectifier element 8, 9 2nd motor current adjustment resistance 10, 11, 12 1st motor connection terminal 13, 14 Control terminal 15 switch of power supply switching circuit Switches 15a, 15b Supply power changeover switch means 16, 17 Second motor connection terminal 18 Rectifier circuit output terminal 19 Relay 19-1 Relay coil 20 Backflow prevention diode 21 Capacitance 22, 24 Relay coil drive transistor 23 Limit resistor 25 Relay coil drive circuit

Claims (3)

  A first driving circuit for supplying a driving current to a first motor for rotationally driving the magnetic disk; and a second driving circuit for supplying a driving current to a second motor for controlling the position of the magnetic head. In order to protect the magnetic head, the second motor is driven to retract the magnetic head, and a brake current is supplied to the first motor to control rotation of the magnetic disk. Magnetic disk unit.   A first driving circuit for supplying a driving current to a first motor for rotationally driving the magnetic disk; a second driving circuit for supplying a driving current to a second motor for controlling the position of the magnetic head; and the second motor. A power supply switching circuit for switching power supply to the power supply, a power supply switching switch means controlled by the power supply switching circuit, and first to third input terminals connected to a plurality of motor coils of the first motor And an output terminal connected to the supply power changeover switch means, and is generated in a plurality of motor coils of the first motor when supply to the first drive circuit and the second drive circuit is cut off. The induced voltage is fixed at the input terminal, which is the largest of the induced voltages, the current supplied to the second motor is constant, and the remaining current is used as a brake current for stopping the first motor. Magnetic disk apparatus, characterized by.   3. The magnetic disk apparatus according to claim 1, wherein a coil is used as a load for the first motor and the second motor.

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