JPS6028068B2 - magnetic disk drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a drive device for rotationally driving a magnetic disk used as storage means for various signals.

(2) Magnetic disks are commonly used for recording and reproducing data signals, etc., but it is difficult to rotate multiple magnetic disks at the same time and record signals on multiple recording tracks formed in the same circular shape on their surfaces. At the same time, signals were also reproduced from these recording tracks, and the configuration shown in FIG. 1 was generally adopted as a subsidiary.

That is, the magnetic disks la to lm are stacked in the same D shape and connected to the spindle 2, and a belt 4 is stretched between the pulley fixed to the spindle 2 and the pulley of the induction conductor 3. While the spindle 2 is rotationally driven by the induction motor 3, the magnetic heads 5a to 5n facing the respective surfaces of the magnetic disks la to lm are moved by the arms 6a to 6.
m, and these arms 6a to 6m are supported by rollers 7
The magnetic disks la to lm are fixed to a carriage 8 that moves freely in the radial direction. , as the magnetic heads 5a to 5n move linearly forward and backward, they move to and face desired recording tracks on the magnetic disks la to lm.

However, in order to obtain a predetermined rotational driving force, the transfer motor 3 requires a certain amount of dimensions in the direction of its diameter, which makes it difficult to make it smaller and lighter. It is unsuitable for use as a direct drive driven by
Since the driving part protrudes greatly from 2, the overall size becomes large, and at the same time, by using the belt 4, vibration and dust are generated due to the rotation of the belt 4, reducing reliability as a complete counterfeit. This resulted in the following drawbacks.

Therefore, as a countermeasure, it is possible to adopt a DC brushless motor instead of a synchronous motor.This type of motor has a stator winding formed in a flat plate shape, so it is easy to downsize, and it is also a direct drive. It is also easy to do so, and by adopting a DC brushless motor, the entire device can be made into a 4-shape and highly reliable.

However, to drive a DC brushless conductor, a pole signal that controls the polarity switching of the magnetic poles according to rotation is essential. This has to be installed separately, which complicates the structure of the motor and poses an obstacle to lower prices.Furthermore, when using a commercial power source, a frequency converter is added depending on the power frequency. This may lead to later drawbacks that may result in the need to do so.

The present invention has the object of eliminating the above-mentioned drawbacks of the conventional art at once, and provides a magnetic disk device configured to be capable of extracting a clock signal from a magnetic disk on which a clock signal synchronized with the rotational state is recorded in advance. When a DC brushless motor is used to drive the spindle of a magnetic disk, the drive control circuit controls the rotation of the DC brushless motor based on a clock signal taken from the magnetic disk, which simplifies the configuration. The object of the present invention is to provide a magnetic disk drive shaft which can perform highly stable rotational drive and which can provide high reliability as a magnetic disk device.

The details of the present invention will be explained below with reference to FIG. 2 and subsequent figures showing embodiments.

FIG. 2 shows the configuration of a magnetic disk device, including magnetic disks la to lm, spindle 2, and magnetic heads 5a to 5.
The mutual relationships among the arms 6a-6m, carriage 8, coil 9, etc. are the same as in FIG. 1, but the permanent magnet 10 shown in FIG. 1 is omitted, and the magnetic disks la-l are omitted.
The upper surfaces of the magnetic disk lm are used for recording and reproducing data signals, etc., whereas the lower surface of the magnetic disk lm is used for recording positioning signals for the recording tracks of the magnetic heads 5a to 5n-1 to the recording tracks. A magnetic head 5n as a servo head is provided to take out this positioning signal, and the output of the magnetic head 5n is directly given to the position control circuit 21.

Note that the positioning signal recorded on the lower surface of the magnetic disk lm is recorded in the recording tracks corresponding to the recording tracks provided on the upper surface of the magnetic disks la to lm-1 and lm, and It contains information for generating a clock signal synchronized with rotational conditions such as angle and rotational speed, and the generated clock signal is applied to the position control circuit 21 via the magnetic head 5n.

In accordance with an external control signal SC, the position control circuit 21 receives information storing the current recording track number, and
After comparing the information with the recording track number specified by the control signal SC, the direction and amount of movement of the carriage 8 is determined, and a current corresponding to the direction of movement is applied to the coil 9, thereby moving the carriage 8 in a predetermined direction. Along with letting
Based on the output of the magnetic head 5n, it is determined how many recording tracks have been skipped, and when the magnetic head 5n reaches the recording track with the designated number, the current is applied to the coil 9 based on the output of the head 5n. The magnetic heads 5a to 5n are stopped on the recording track of the designated number.

On the other hand, a DC brushless electric motor (
Hereinafter, a rotor 2 to which a permanent magnet 23 of an electric motor 22 is fixed
4 is locked, and a flat stator winding 26 fixed on the yoke 25 is provided opposite to this, and the stator winding 26
The rotor 24 rotates by switching and controlling the excitation current supplied to the rotor 24 by the drive control circuit 27, and thereby the magnetic disks la to lm are directly driven and rotate together with the rotor 24.

FIG. 3 shows a block diagram of the drive control circuit 27, in which the clock signal from the magnetic disk lm is taken out by the magnetic head 5n, and then converted into a pulse waveform by the waveform shaping circuit WF. After the frequency is divided by the frequency divider DV, this frequency divided output is given to the distribution circuit DIS using a shift register or the like via the selection circuit SEL, which generates a three-phase control pulse with a frequency based on the frequency divided output. The three-phase output frequency of the voltage-controlled inverter VCI is determined by the following, and this is used as a switching-controlled excitation current to drive the electric motor 22.

However, since the clock signal from the magnetic disk lm cannot be obtained at startup, the distribution circuit DI
It is necessary to drive S, and a pulse generator PG that generates a pulse signal for self-starting is provided, and the pulse signal from the pulse generator PG is distributed to the distribution circuit via the selection circuit SEL, which initially selects the ■ side. It is given to DIS.

Therefore, the output of the pulse generator PG causes the electric motor 2 to
2 is started, but a reference signal a for determining the circuit speed is given from the outside, and a clock signal and reference signal a whose frequency is determined according to the rotational speed of the magnetic disk lm are supplied.
The electric motor 22 controls the voltage control inverter VCI based on the difference between the two and changes the power of each phase in the output of the inverter VCI so that the rotation speed corresponds to the level of the reference signal a. is controlled.

That is, the output of the waveform shaping circuit WF is given to a frequency/voltage converter (hereinafter referred to as FVC) F/V using an integrating circuit,
The tortoise pressure corresponding to the frequency of the clock signal is applied to the negative input of the differential amplifier DA, and the reference signal a is applied to the positive input of the amplifier DA, and in this step, the difference output between the two is obtained. Moreover, after this is amplified by amplifier A, the output power of voltage control inverter VCI is controlled by the output thereof.

In this example, one waveform in each phase output of the voltage controlled inverter VCI is composed of a plurality of pulses, and the output power is controlled by changing the pulse width of each pulse according to the output of the amplifier A.

However, the operation of a voltage controlled inverter is not limited to this, and by adding a voltage or current control circuit to the DC wire input side,
The same applies if this circuit is controlled by the output of amplifier A and the voltage or current of each phase output is changed.
Therefore, the rotational speed of the electric motor 22 changes depending on the output power of the voltage-controlled inverter VCI, and the rotational speed becomes constant when the differential output of the differential amplifier DA becomes zero.

In addition, a selection circuit SEL using a relay or gate circuit, etc.
After the motor 22 is started, the clock signal 0 frequency reaches a predetermined frequency and then switches to the ■ side, and the divided output of the frequency divider DV is given to the distribution circuit DIS. Control is provided by the output of comparator CPR.

That is, the comparator CPR compares the output of FVC・F/V with a reference voltage corresponding to a predetermined frequency, and when the frequency of the clock signal reaches a predetermined frequency and the two match, the output of FVC・F/V A comparison output is generated by the output voltage from /V, thereby switching the selection circuit SEL to the ■ side.

Note that the number of poles of the electric motor 22 is P, the number of phases of its drive power source is G, the frequency of the clock signal is expressed as the number of clock signals K/rev during one revolution of the magnetic disk lm, and the frequency divider DV, When the circumferential ratio is 1/N, the following function may be selected.

P○N=K In addition, the phase of the power source that drives the electric motor 22 and the phase of the mechanical rotation angle of the electric motor 22 are approximately 90
It is preferable to set the phase difference to 0 and set the assumed brush angle to 0. Therefore, the pulse generator PG is equipped with a selection circuit S.
In addition to the main output to the EL, a creation power C is provided which has a phase difference of 9 pins from the main output.The AND gate of this sub-output C and the output of the comparator CPR is obtained by an AND gate G. The frequency divided wave DV, is controlled by the output of the frequency divider DV, to start the frequency dividing operation, and the phase of the frequency divided output obtained from the frequency divider DV, is regulated.

Therefore, at first, the electric motor 22 is started based on the output of the pulse generator PG, and when a predetermined rotation speed is reached, the rotation speed is determined according to the reference signal a, and the rotational drive of the magnetic disks la to lm is stably performed. It is done.

FIG. 4 is a block diagram showing a control system in the case of further stabilizing the rotational speed, and the drive control circuit 2 of FIG.
7, an automatic phase control circuit 28 is added.

That is, the reference oscillator OSC with a stable oscillation frequency
After generating a reference frequency, the output obtained by dividing the clock signal b obtained from the waveform shaping circuit WF of the drive control circuit by a frequency divider DV2 with a frequency division ratio of 1/M and the output of the reference oscillator OSC are divided in phase. Comparison is performed by a comparator PCP, and the comparison output is passed through a loop filter FL such as a low frequency wave generator and then given to the drive control circuit 27 as a reference signal a, and the rotation speed of the motor 22 is determined by the output frequency of the reference oscillator OSC. is determined, a highly accurate and highly stable rotational speed can be obtained.

Therefore, the clock signal for forming a pole signal can be obtained from the magnetic disk lm as a servo disk without providing a Hall element or a photoelectric conversion element for detecting the rotational state to the electric motor 22. It is possible to easily realize a compact and highly reliable magnetic disk device. In addition, the magnetic disk lm as a servo disk may not be placed at the bottom but may be placed in any order, or the magnetic disks la to lm-1 for data recording may be provided with a specific clock signal without a servo disk. The same effect can be achieved even if a recording track is determined and a magnetic head facing the recording track is provided exclusively for the servo head.

Further, the configuration of the drive control circuit 27 can be arbitrarily selected depending on the conditions, and the configuration of the automatic phase control circuit 28 can be selected from the frequency divider DV2.
Various modifications can be made, such as the possibility of omitting it in some cases.

As is clear from the above explanation, according to the present invention, the rotational state detection element essential to a DC brushless motor is no longer necessary, and a direct drive magnetic disk device can be easily realized, downsized, and the motor section can be housed in a sealed case. Since it is possible to cover with
In addition to completely preventing the intrusion of moisture, internal vibrations and dust generation are also eliminated, and damage to magnetic disks and magnetic heads caused by dust and moisture is completely prevented, and the motor starts. Since the operating conditions are stabilized and the reliability and stability are high, the recording and reproducing conditions of data signals are improved, and great effects can be obtained in magnetic disk devices for various uses.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional example, Fig. 2 and subsequent figures show embodiments of the present invention, Fig. 2 is a block diagram, Fig. 3 is a block diagram of a drive control circuit, and Fig. 4 is a block diagram of an automatic phase control circuit. FIG. 3 is a block diagram of an added control system. lm...Magnetic disk, 2...Spindle, 5n...Magnetic head, 22...
Electric motor (DC brushless motor), 24... Rotor, 25... Yoke, 26... Stator winding, 27... Drive control circuit, 28. ...Automatic phase control circuit, PG...Pulse generator, 06
C: Reference oscillator, PCP: Phase comparator. Figure 1 Figure 3 Figure 4 Figure N Ship

Claims (1)

[Scope of Claims] 1. In a magnetic disk device configured to be capable of extracting a clock signal from a magnetic disk on which a clock signal synchronized with the rotational state has been recorded in advance, a DC brushless drive that drives a spindle of the magnetic disk is provided. an electric motor, a frequency divider that divides the frequency of the clock signal taken out from the magnetic disk, a frequency/voltage converter that converts the clock signal into a voltage according to the frequency, and an output of the converter and a predetermined frequency. a comparator that compares a corresponding reference voltage and produces a comparison output when the two match;
A pulse generator that generates a main pulse signal for self-starting and a sub-pulse signal having a phase difference of 90 degrees from the main pulse signal, and initially selects the main pulse signal from the pulse generator and outputs the comparison output. a selection circuit that selects the output reliability of the frequency divider according to the frequency divider; a voltage inverter whose output frequency is controlled by the output of the selection circuit and drives the DC brushless motor; A magnetic disk drive device comprising: an AND gate that performs a logical product of a pulse signal and an output of the comparator to generate an output that regulates the phase of the frequency-divided output of the frequency divider. 2. A magnetic disk device configured to be capable of extracting a clock signal from a magnetic disk on which a clock signal synchronized with the rotational state has been recorded in advance, comprising: a DC brushless motor that drives a spindle of the magnetic disk; A frequency/voltage converter converts the clock signal extracted from the clock signal into a voltage corresponding to the frequency of the clock signal, and the output of the converter is compared with a reference voltage corresponding to a predetermined frequency, and a comparison output is obtained when the two match. a comparator that generates a signal, a pulse generator that generates a pulse signal for self-starting, and a selection that initially selects the pulse signal from the pulse generator and selects the output signal of the frequency divider in accordance with the comparison output. an automatic phase control circuit that compares the phases of the clock signal and the output of the reference oscillator and sends out a reference signal; and a differential amplifier that determines the difference between the reference signal and the output of the frequency/voltage converter; A magnetic disk drive device, wherein the output power is controlled by the differential output of the differential amplifier, the output frequency is controlled by the output of the selection circuit, and a voltage control inverter is provided for driving the DC brushless motor. .