JPH02281467A - Spindle motor driving circuit for magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent trouble due to attraction from occurring between a magnetic head and a magnetic disk by actuating a spindle motor by raising a motor diving voltage gradually by utilizing the temperature-resistance characteristic of a resistance body. CONSTITUTION:A thermistor 120 connected in series between the emitters of motor driving switching elements 11-13 and a motor driving power source has a high resistance value at low temperature when the motor 60 is at a stop, but varies to a low resistance value by self-heating with the starting current at the start of the motor 60. When the spindle motor 60 is actuated, a voltage applied to the spindle motor wiring can be raised gradually from a low voltage because of the characteristic of the thermistor 120. Then a motor control circuit 100 turns on a soft/normal switching element 53 a certain time later to apply a rated voltage to the spindle motor winding, thereby starting normal operation. Consequently, the trouble due to attraction is prevented from occurring between the magnetic head and magnetic disk when the spindle motor 60 is actuated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device, and particularly to a contact start/stop device.
The present invention relates to a spindle motor drive circuit for a magnetic disk device of type p).

[Conventional technology]

Conventionally, the motor drive circuit of this type of magnetic disk device is
As shown in FIG. 2, motor drive switching elements 11 to 13 and 2 are connected to each drive winding of the spindle motor 60.
1 to 23, and the motor control circuit 5o receives the motor start signal 1.
When is input, the output signals from the rotational position detection elements 61 to 63 of the spindle motor 60 are used to turn on the motor drive switching elements 11 to 13 and 21 to 23 one by one to apply a rotating magnetic field to the motor 60. Control so that it occurs. The starting characteristic of the motor was a steep rising characteristic as shown by the broken line in FIG. 3(1). In addition,
A reference clock generation circuit 52 is connected to the motor control circuit 50 .

[Problems to be Solved by the Invention] In the spindle motor drive circuit of the conventional magnetic disk device described above, when the spindle motor is started at the time of starting up the device, the motor drive power supply is connected to the drive winding of the spindle motor by the motor drive switching element. When starting the device, the spindle motor starts with maximum torque.

However, in magnetic disk drives using the contact start/stop method, when the device is started or stopped, the magnetic head and the magnetic disk are in contact via a lubricant coated on the surface of the magnetic disk, making it particularly difficult for the device to be idle for long periods of time. Under these conditions, a phenomenon in which the magnetic head is attracted to the surface of the magnetic disk tends to occur. Under the above conditions, a large frictional force is exerted on the contact surface between the magnetic head and the magnetic disk, so the conventional starting method of starting the spindle motor at maximum torque may cause adhesion and peeling, especially on the magnetic head and magnetic disk surface. Both magnetic heads and
This has the disadvantage that it can cause considerable damage to both surfaces of the magnetic disk, and in the worst case, it is likely to cause serious failures such as head crashes that can lead to data destruction.

SUMMARY OF THE INVENTION An object of the present invention is to provide a spindle motor drive circuit for a magnetic disk device that eliminates the problem that occurs between a magnetic head and a magnetic disk due to adhesion when the spindle motor is started.

[Means for Solving the Problems] A spindle motor drive circuit for a magnetic disk drive according to the present invention includes a resistor having a negative temperature coefficient between a motor drive switching element and a motor drive power supply, and a resistor having a negative temperature coefficient. The motor control circuit has a soft/normal switching switching element connected to both ends of the resistor in parallel, and the motor control circuit starts the spindle motor after a certain period of time has passed after the motor start signal is input, or when the spindle motor rotates for a certain period of time. The feature is that after reaching the number, the switching element for soft/normal switching is turned on.

[Function] Since the temperature of the resistor is low when the spindle motor is at rest, it has a high resistance value. When the motor starts, the resistance of the resistor changes to a low resistance value due to self-heating caused by the starting current. Therefore, when starting the spindle motor, the voltage applied to the spindle motor winding gradually increases from a low voltage, and after a certain period of time or when the spindle motor reaches a certain rotation speed, the soft/normal switching switching element is turned on, the rated voltage is applied to the spindle motor winding, and the spindle motor enters normal operation.

In this way, since the spindle motor starts up slowly when the motor is started, problems occurring between the magnetic head and the magnetic disk due to attraction are eliminated.

〔Example〕

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

FIG. 1 is a block diagram of a spindle motor drive circuit showing one embodiment of the present invention.

Each winding of the spindle motor 60 is connected to the collector of each set of motor drive switching elements 11 to 13 and 21 to 23, and the winding drive current supply side switching element 1
Emitters 1 to 13 are connected in parallel to the thermistor 120 and both ends of the thermistor 120, and are connected to the motor drive power source via a soft/normal switching switching element 53 to short-circuit both ends of the thermistor 120 under preset conditions. It is connected. Note that other parts of the spindle motor drive circuit of this embodiment are not much different from conventional circuits, so detailed explanations will be omitted.

Next, the operation of this circuit will be explained with reference to FIG.

When starting the spindle motor 60 for restarting the magnetic disk device after it has stopped for a long time, the motor control circuit 1
00 uses the output signals from the rotor rotation position detection elements 61 to 63 of the spindle motor 60 when the motor start signal 1 is input, and switches the motor drive switching element 11.
~13 degrees 21 to 23 are turned on one by one to control the motor 6o to generate a rotating magnetic field.

The thermistor 120 connected in series between the emitters of the motor drive switching elements 11 to 13 and the motor drive power supply has a high resistance value because the temperature is low when the motor is at rest, and the resistance value is high due to the starting current when the motor is started. Changes to a low resistance value due to self-heating. Due to the characteristics of the thermistor described above, when starting the spindle motor 6o, the voltage applied to the spindle motor winding can be gradually increased from a low voltage, and the motor control circuit 100, as shown in FIG. 3(2), Soft start end signal 1 after a certain period of time T has elapsed
10 to a high level, and the soft/normal switching switching element 53 is turned on. As a result, the rated voltage is applied to the spindle motor windings, resulting in normal operation. That is, in contrast to the conventional motor start-up characteristic shown by the broken line in FIG. 3(1), this circuit can provide a gradual start-up characteristic when the motor is started, as shown by the solid line in FIG. 3(1).

〔Effect of the invention〕

As explained above, the present invention starts the spindle motor by gradually increasing the motor drive voltage using the temperature-resistance characteristics of the resistor.In other words, the torque at the time of starting the motor is sufficiently By starting with a low pressure, the magnetic head can fly smoothly even if there is an adhesion phenomenon that tends to occur in contact start/stop type magnetic disk drives, and the magnetic head and magnetic disk can be easily floated due to adsorption. This has the effect of solving the problems that occur and providing a highly reliable magnetic disk device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a spindle motor drive circuit showing an embodiment of the present invention, FIG. 2 is a block diagram of a conventional spindle motor drive circuit, and FIG. 3 is a block diagram of a spindle motor drive circuit shown in FIGS. 1 and 2. 2 is a characteristic diagram showing the starting characteristics of the motor of the circuit and the timings of the motor start signal 1 and the soft start end signal 110. FIG. l...Motor start signal, 11
~13.21~23... Motor drive switching element, 50, 100... Motor control circuit, 52...
......Reference clock generation circuit, 53...
......Soft/normal switching switching element, 60... Spindle motor, 61
~63...Rotational position detection element, NO...
...Soft start end signal, 120...
...Thermistor.

Claims (1)

[Claims] 1. In a spindle motor drive circuit for a contact start/stop type magnetic disk device, a resistor having a negative temperature coefficient is provided between a motor drive switching element and a motor drive power source; The motor control circuit has a switching element for soft/normal switching connected to both ends of the resistor in parallel to the resistor, and the motor control circuit starts the spindle motor after a certain period of time has passed after the motor start signal is input, or when the spindle motor is started. A spindle motor drive circuit for a magnetic disk device, characterized in that a switching element for switching between soft and normal is turned on after the rotation speed reaches a certain number of rotations.