JPH01229475A - Magnetic recording device - Google Patents

Abstract

PURPOSE:To reduce power consumption and at the same time to improve vibration proofness by comparing the drop of the output level of a signal read out of a magnetic head with a reference voltage level to detect a track shift of a magnetic head due to vibration and compensating the holding current of a stepper motor only when a position shift is generated. CONSTITUTION:In a normal working state, the output e1 of an envelope detecting circuit 4 is larger than the reference voltage e0. At the same time, the output S1 of a comparator 5 is kept at '0' and the holding current is dropped for a stepper motor driver circuit 7. Then the output of an AGC incorporating amplifier 2 drops when the head position shifts with addition of external vibration while an amplification factor is kept to secure a fixed level of the output of the amplifier 2. When the output e1 drops less than the voltage e0, the output of the comparator 5 is equal to '1' and the circuit 7 has the full output of its holding current to reset the head position.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a magnetic recording device, and in particular to a magnetic recording device that electrically prevents a magnetic head from falling out of track due to external vibration or the like in a low power consumption magnetic recording device. 9 Related to Apparatus [Prior Art] If the magnetic head drive mechanism of this type of magnetic recording device is mechanically reversible, the magnetic head drive step remains intact even after completing the seek and starting the data read/write operation. A hold current must continue to flow through the sober motor in order to maintain its stopped position. However, in the case of conventional low power consumption type magnetic recording devices, the hold current is reduced to "O" or about 1/2 of the seek current in order to reduce power consumption.

[Problem to be solved by the invention]

In the above-mentioned conventional low power consumption type magnetic recording device, priority is given to low power consumption, so the hold torque of the stepper motor is reduced, and the effect of preventing magnetic tracks from falling off due to external vibrations is insufficient. Ta.

[Means to solve the problem]

The magnetic recording device of the present invention includes an amplifier including an AGC circuit that amplifies the output of a magnetic head to obtain a fixed level output, and a monostable multi-channel amplifier that operates the AGC circuit of the amplifier for a fixed period of time after receiving an index signal. a vibrator circuit; an envelope detection circuit for detecting the output of the amplifier; a comparator for comparing the output of the envelope detection circuit with a reference voltage; The stepper motor driver circuit increases the hold current when the voltage is lower than the voltage.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
FIG. 4 is a diagram showing the temporal relationship of voltage waveforms at various parts in the figure when the positional relationship between the magnetic head and the track is normal and when there is an abnormality where a deviation has occurred.

The amplifier 2 includes an AGC circuit, amplifies the output of the magnetic head 1, and outputs it to the envelope detection circuit 4 at the next stage. Also, amplifier 2
is a function in which the AGC operates in response to the output of the monostable multivibrator 3, which generates pulses for a certain period of time in response to the index signal S1 of the spindle motor, and thereafter keeps the amplification factor constant by turning off the AGC circuit. has. The envelope detection circuit 4 is a kind of AM detection circuit, and when the output e1 of the envelope detection circuit 4 is higher than the reference voltage e,), the output S1 of the comparator 5 is "0", and the magnetic head 1 is on track. Due to the deviation, the output el becomes the reference voltage e. If the voltage drops further, the output Sl of the comparator 5 becomes "1".

OR circuit 6 is high power signal S. , or the output S of the comparator 5, or both are "1", it outputs "1", and when the output of the OR circuit 6 is "1", the stepper motor driver circuit 7 uses the hold current as the full output. , "When the value is 0°, the hold current is reduced.

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

As shown in Fig. 2(a), when the index signal SI is input, the output of the monostable multivibrator 3 remains "1" for a certain period of time.
During this time, the AGC of the amplifier 2 operates to maintain a constant amplifier output regardless of the magnitude of the output of the head 1. When the output of the monostable multivibrator 3 becomes "0", the AGC stops operating, and the amplifier 2 maintains the amplification factor that makes the amplifier output constant. During normal operation, the output el of the envelope detection circuit 4 is greater than the reference voltage e□, the output Sl of the comparator 5 remains "0", and the stepper motor driver circuit 7 lowers the hold current.

Next, the abnormal case shown in FIG. 2(b) will be explained. When maintaining the amplification factor that makes the amplifier output constant,
If external vibrations are applied and the head position shifts, the amplifier 2
When the output e1 falls below the reference voltage e,), the output of the comparator 5 becomes "1", the stepper motor driver circuit 7 makes the hold current the full output, and the head position is restored.

〔Effect of the invention〕

As explained above, the present invention detects the track deviation of the magnetic head due to vibration etc. by comparing the drop in the output level of the signal read from the magnetic head with the reference voltage, and only when the position deviation occurs, the stepper Since the magnetic head is pulled back by supplementing the hold current of the motor, there is no need to keep the hold current flowing all the time, which has the effect of suppressing the power consumption of the device and improving vibration resistance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a track separation prevention circuit for a magnetic head of a magnetic recording device according to an embodiment of the present invention, and FIG. 2 is a diagram showing the temporal relationship of voltage waveforms at various parts in FIG. (a
) is a diagram when the positional relationship between the magnetic head and the track is normal, and FIG. 2(b) is a diagram when the positional relationship between the magnetic head and the track is abnormal. DESCRIPTION OF SYMBOLS 1... Magnetic head, 2... Amplifier, 3... Monostable multivibrator, 4... Envelope detection circuit, 5...
・Comparator, 6...OR circuit, 7...Stepper motor driver circuit.

Claims (1)

[Claims] an amplifier including an AGC circuit that amplifies the output of a magnetic head to obtain a constant level output; a monostable multivibrator circuit that operates the AGC circuit of the amplifier for a constant time after receiving an index signal; and an output of the amplifier. an envelope detection circuit that detects the voltage, a comparator that compares the output of the envelope detection circuit with a reference voltage, and increases a hold current when the output of the envelope detection circuit is lower than the reference voltage in response to the output of the comparator. A magnetic recording device comprising a stepper motor driver circuit.