JPH076487A - Magnetic disk device and vibration detecting method - Google Patents

Abstract

PURPOSE:To detect a vibration and an impact exerted upon a device during the time of writing-in data without using expensive parts such as piezoelectric elements. etc. CONSTITUTION:When a head selecting circuit 2-1 selects a head 1-1 and data are being written-in on a magnetic disk which is not shown in a Fig., a head selecting circuit 2-2 selects a head 1-3 as a read-out head and data read-out from the head 1-3 are inputted to a peak detecting circuit 10 via a pre-amplifier 7, an AGC amplifier 8 and a full-wave rectifier circuit 9. The peak detecting circuit 10 holds peaks of inputted signals with time constants tau1, tau2 and outputs the signals to comparators 11, 12. When the change of data read-out by the head 1-3 is larger than a reference value, comparators detects this to output to a microprocessor 15 as the signal of the vibration and the impact via an OR circuit 13 and an AND circuit 14. The microprocessor 15 stops the writing operation of the head 1-1 when the vibration and impact detection signal is inputted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device, and more particularly to a vibration detecting method for detecting vibration or shock applied during data reading / writing.

[0002]

2. Description of the Related Art Conventionally, a sector servo for detecting a burst data written in advance for each sector of a plurality of concentric cylinders of a magnetic disk by a head and positioning the head at the center of a target cylinder. In the magnetic disk device of the method, since burst data is not continuous when vibration or shock is applied during the data read / write operation for the target sector,
The servo system of the head could not detect that the vibration or shock was applied when reading / writing the data. For this reason, even if the head servo system shifts the position of the head due to vibration or impact, it cannot be detected and the data is read / written as it is. Therefore, a read error occurs when reading the data. In addition, there is a problem that the data is erroneously written to the adjacent cylinder at the time of writing the data.

Therefore, conventionally, piezoelectric elements are installed at a plurality of locations in a magnetic disk device, and a circuit for detecting the vibration or shock by the piezoelectric elements is provided. This circuit vibrates during reading / writing of data to / from a magnetic disk. When a shock or shock is detected, control is performed to suspend the reading / writing of data. However, a plurality of piezoelectric elements that detect vibrations and shocks applied to the magnetic disk device in this manner (usually at least 3 in order to detect vibrations and shocks in the X, Y, and Z axis directions).
Since one or more piezoelectric elements are relatively expensive), if a vibration shock detection circuit using such piezoelectric elements is provided, there is a disadvantage that the device becomes expensive, Since it is necessary to secure a place for mounting the element, there is a drawback that it goes against the downsizing of the device.

[0004]

In the conventional magnetic disk device using the sector servo system, when vibration or shock is applied to the device during the data read / write operation on the magnetic disk, the head servo system detects this. Therefore, even if the head deviates from the center of the target cylinder, the data read / write operation continues as it is, so a data read error occurs during read, and data is written to the adjacent cylinder during write. There was a problem of writing. Therefore, a circuit for detecting the vibration or shock using a piezoelectric element is provided, and if the circuit detects the vibration or shock during the reading / writing of data, control for temporarily suspending the data reading / writing operation may be performed. However, since the piezoelectric element is expensive, the device becomes expensive,
Space is needed to attach the piezoelectric element,
There is a drawback that it is difficult to downsize the device.

Therefore, the present invention eliminates the above-mentioned drawbacks and reliably detects vibrations and impacts applied to the device during data writing without using expensive parts such as piezoelectric elements, so that data is erroneously transmitted to adjacent cylinders. It is an object of the present invention to provide a magnetic disk device and a vibration detection method capable of preventing writing and improving the reliability of the device.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a magnetic disk device having a plurality of read / write heads for reading and writing data on a magnetic disk, the head being different from the head used for reading and writing data. A head selecting unit for selecting, a comparing unit for comparing a change in data read from the head selected by the head selecting unit with a reference value, and a change in the data read by the comparing unit has a reference value. The device will vibrate if exceeded,
When it is determined that a shock is applied and a vibration detection signal is output, and the vibration is detected by this detection means,
And a control means for stopping writing or reading of data by the head.

[0007]

In the magnetic disk drive of the present invention, the head selecting means selects a head different from the head used for reading and writing data. The comparing means compares the change in the data read from the head selected by the head selecting means with a reference value. The detection means determines that vibration or impact has been applied to the device when the change in the data read by the comparison means exceeds a reference value, and outputs a vibration detection signal. The control means stops the writing or reading of data by the head when the vibration is detected by the detecting means. This makes it possible to detect vibrations and impacts applied to the device without using an expensive piezoelectric element, and to make the device inexpensive and compact.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a magnetic disk device of the present invention. 1-1 to 1-3 are heads for reading / writing data to / from a magnetic disk (not shown), 2-1 is a head selection circuit for selecting the data reading / writing head, and 2-2 is for detecting vibration and shock. Head select circuit for selecting a head for reading the data, 3 is a preamplifier with a constant gain for amplifying the read data, 4 is an automatic gain control (AGC) amplifier for making the level of the read data constant, and 5 is a peak of the read data Pulse peak detector, which outputs a pulse
6 is a decoding circuit for demodulating read data, 7 is a pre-amplifier with a constant gain that amplifies vibration and shock detection read data, and 8 is an automatic gain control (AGC) amplifier that keeps the level of vibration and shock detection read data constant , 9 is a full-wave rectifier circuit for full-wave rectifying the input data, 10 is a peak detection circuit for detecting the peak of the read data subjected to full-wave rectification with time constants τ1 and τ2, and 11 is a peak detection circuit 10 A comparator for detecting the upper limit value of the peak voltage of the constant τ1, 12 is a comparator for detecting the lower limit value of the peak voltage of the time constant τ2 detected by the peak detection circuit 10, and 13
Is an OR circuit that takes the logical sum of the comparison results of the comparators 11 and 12, 14 is the output of the OR circuit 13, and the servo gate signal SG
AND circuit which takes the logical product of the inversion signal of the above, the data write signal WG, and the inhibition signal INH, and 15 are heads 1-1 and 1-2.
The output signal S from the AND circuit 14 is a microprocessor that controls the position of the
I is input to the interrupt terminal INT. Reference numeral 16 is a data write circuit that supplies a write signal to the head selection circuit 2-1, C1 and C2 are time constants τ1 of the peak detection circuit 10,
External capacitors that determine τ2, R1, R2 and R
3 and R4 are voltage dividing resistors. However, the head 1-1 has a head number 0, the head 1-2 (not shown) has a head number 1,
The head 1-3 is head number 3, and a plurality of heads are mounted in addition to this, but the illustration is omitted.

Next, the operation of this embodiment will be described. During the data read operation, the head selection circuit 2-1 selects, for example, the head 1-1 as the read head. At the same time, the head 1-1 is positioned at the center of a target cylinder on a magnetic disk (not shown) by a servo system (not shown). Thereafter, the head 1-1 reads data from the target sector on the target cylinder. This read data is amplified by the preamplifier 3 and then its level is made constant by the AGC amplifier 4, and then its peak is detected by the pulse peak detector 5 and input to the decoding circuit 6. Decoding circuit 6
Demodulates the peak of the input read signal and outputs it. On the other hand, at the time of writing, write data is supplied from the data write circuit 16 to the head 1-2 selected by the head selection circuit 2-1 and written in the target sector on the target cylinder of the magnetic disk.

By the way, the head selecting circuit 2-2 selects the head having the relationship shown in FIG. 3 with respect to the head selected by the head selecting circuit 2-1 at the time of reading / writing data. The data reproduced by this head is output to the preamplifier 7. In FIG. 3, when the head selection circuit 2-1 selects the head 1-1 with the head number 0,
The head selection circuit 2-2 selects the head 1-3 having the head number 2. A signal HS indicating the selection relation of the heads at this time
0 and HS1 are 0 and 0. The data read by the heads 1-3 are amplified by the preamplifier 7 and then AG
After the level is made constant by the C amplifier 8 as shown in FIG. 2 (A), it is full-wave rectified by the full-wave rectifier circuit 9 as shown in FIG. 2 (D) and input to the peak detection circuit 10. . The peak detection circuit 10 uses the externally attached capacitors C1 and C2 to hold the input peak voltage at 2
Kinds of time constants τ1 and τ2 are set.

The time constant τ1 is set to a relatively short time constant so that it can follow small peak fluctuations. The time constant τ2 is a relatively long time constant and is set so as not to follow a small peak fluctuation. FIG. 2 in which the time constant of τ1 of the peak detection circuit 10 is held.
The peak detection voltage as shown in (E) is input to the non-inverting input terminal of the comparator 11 and the inverting input terminal of the comparator 12. On the other hand, the peak detection voltage held at the time constant τ2 of the peak detection circuit 10 as shown in FIG. 2 (F) is divided by the voltage dividing resistors R1 and R2, and then the comparison circuit 1
1 is input to the inverting input terminal, and the voltage dividing resistor R3,
The voltage is divided by R4 and input to the non-inverting input terminal of the comparison circuit 12. The peak holding voltage of the time constant τ2 becomes the reference voltage (upper limit value, lower limit value) of the comparators 11 and 12 by the voltage dividing resistors R1 and R2 and the voltage dividing resistors R3 and R4 described above. Therefore, when the peak voltage held by the time constant τ1 becomes higher than the upper limit value with respect to the reference voltage generated by the voltage dividing resistors R1 and R2, the comparator 11 outputs a high level signal as shown in FIG. Is output to the AND circuit 14 via the OR circuit 13. When the peak voltage held at the time constant τ1 becomes lower than the lower limit value with respect to the reference voltage generated by the voltage dividing resistors R3 and R4, the comparator 12 sends a high level signal to the AND circuit 14 via the OR circuit 13. Output.

When vibration and impact are applied to the magnetic disk device from the outside in the radial direction of the magnetic disk (not shown) during the above-mentioned operation, both the head 1-1 and the head 1-2 have a radius of the magnetic disk. It moves in the direction, and it deviates from the center of the target track. At this time, the output of the read data of the head 1-3 selected by the head selection circuit 2-2 fluctuates, and the output temporarily lowers as shown in (a) of FIG. This decrease in the output of the read data appears in the peak voltage held by the time constant τ1 of the peak detection circuit 10 as shown by B in FIG. 2 (E), and this peak voltage temporarily decreases. However, the peak voltage held by the time constant τ2 of the peak detection circuit 10 is unlikely to be affected by the decrease in the output of the read data, so that the reference voltage input to the comparators 11 and 12 is substantially constant.

As described above, when the output signal level of the head 1-3 temporarily drops due to vibration or shock, the comparator 1
2 detects this at C in FIG. 2 (G) and outputs a high level vibration detection signal. This vibration detection signal is output to the AND circuit 14 through the OR circuit 13. When the AND circuit 14 is not in the servo gate, is writing data, and is not prohibiting the vibration and impact detection operation,
Since the SG inversion signal shown in (B) and the WG and INH signals shown in FIG. 2 (C) are all at a high level, they are open and the vibration detection signal is output from the comparator 12, After passing through the circuit 14 as shown in FIG.
It is input to the interrupt terminal INT of the microprocessor 15.

When the vibration detection signal is input to the interrupt terminal INT, the microprocessor 15 stops the output of the write data supplied from the data write circuit 16 to the head selection circuit 2-1 and the head 2- The data write operation by 1 is temporarily stopped. However, at the time of reading data, since it can be processed as a read error, the vibration detection operation by the head 1-3 is not performed.

When the magnetic disk device is vibrated or shocked, the output of the read signal from the head 1-3 may increase. In this case, the peak held by the time constant τ1 of the peak detection circuit 10 is generated. Since the voltage temporarily rises, the output voltage of the comparison circuit 11 is inverted to the high level,
It is detected that vibration or shock is applied to the magnetic disk device. The vibration detection signal output by the comparison circuit 11 is also input to the interrupt terminal INT of the microprocessor 15 through the OR circuit 13 and the AND circuit 14, and the same write operation stop control as described above is performed.

According to this embodiment, the head selection circuit 2-1
The write head is selected by the head select circuit 2- while writing data to the magnetic disk (not shown).
2 selects a head other than the above, reads data from the magnetic disk by this head, and when the comparison circuit 11 or 12 detects a change of the read data that is greater than or equal to a reference value, writes the data by the write head. Can be suspended to prevent accidental writing of data to adjacent cylinders of the target track,
As a result, the reliability of the device can be improved. or,
Since it is not necessary to use an expensive piezoelectric element, the device can be constructed at a low cost, and the device can be downsized because a space for mounting the piezoelectric element is not required. However, circuits such as the preamplifier 7 to the AND circuit 14 are required to detect vibrations and shocks, but since these are integrated into ICs, they do not increase the cost of the device so much, and Since the space for mounting the device is hardly taken, the above effect can be obtained. In this example, the vibration detection operation by the head different from the read head is not performed at the time of reading the data, but if this is performed and the vibration or shock is applied to the device, the data is not read. It is also possible to perform control to suspend.

FIG. 4 is a block diagram showing another embodiment of the present invention. In this example, the circuit that amplifies the read data by the head selected by the head selection circuit 2-1 and keeps the level constant is also used as the circuit that processes the data read by the head selected by the head selection circuit 2-2. . Therefore, when the head selected by the head selection circuit 2-1 is reading data from the magnetic disk (not shown), all the switches SW1 to SW4 are switched to the terminal a side, and the read data is the preamplifier 3 and AGC.
The pulse peak detector 5 is input via the amplifier 4. However, while the head selected by the head selection circuit 2-1 is in the writing period, the switch S
All of W1 to SW4 are switched to the terminal b side, and the read data read by the head selected by the head selection circuit 2-2 is input to the full-wave rectifier circuit 9 via the preamplifier 3 and the AGC amplifier 4, Vibration and impact on the device are detected by the same operation as that of the embodiment, and the same effect as that of the previous embodiment can be obtained. In particular, in this example, the circuit that amplifies the read signal for vibration / shock detection to make the level constant is also used, so that the circuit configuration is simplified as compared with the previous example,
Further, the device can be made inexpensive and compact.

[0018]

As described above, according to the magnetic disk device and the vibration detecting method of the present invention, it is possible to reliably detect the vibration and the shock applied to the device during the data writing without using expensive parts such as piezoelectric elements. Thus, it is possible to prevent the data from being erroneously written in the adjacent cylinder, and it is possible to improve the reliability of the device.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a magnetic disk device of the present invention.

FIG. 2 is a time chart of various signals generated by the device of FIG.

FIG. 3 is a diagram for explaining an example of the relationship of heads selected by the two head selection circuits shown in FIG.

FIG. 4 is a block diagram showing another embodiment of the present invention.

[Explanation of symbols]

1-1 to 1-3 ... Heads 2-1 and 2-2
... Head selection circuit 3, 7 ... Preamplifier 4, 8 ... AGC
Amplifier 5 ... Pulse peak detector 6 ... Decoding circuit 9 ... Full wave rectification circuit 10 ... Peak detection circuit 11, 12 ... Comparator 13 ... OR circuit 14 ... AND circuit 15 ... Microprocessor 16 ... Data writing circuit C1, C2 ... Capacitor R1 to R4 ... Dividing resistance

Claims (3)

[Claims] 1. In a magnetic disk device having a plurality of read / write heads for reading and writing data on a magnetic disk, head selecting means for selecting a head different from the head used for reading and writing data, Comparing means for comparing a change in the data read from the head selected by the head selecting means with a reference value; and vibration of the apparatus when the change in the read data by the comparing means exceeds the reference value. And a detection unit that outputs a vibration detection signal when it is determined that a shock is applied, and a control unit that stops writing or reading of data by the head when the vibration is detected by the detection unit. Porcelain disk device. 2. The comparison means holds the peak voltage of the data read from the head selected by the head selection means with two types of time constants, and the peak voltage held with a long time constant is used as a reference signal. 2. The magnetic disk device according to claim 1, wherein the peak voltage held with a short time constant is compared with this reference signal. 3. A vibration detecting method for detecting vibration and shock applied to a magnetic disk device having a plurality of read / write heads for reading and writing data on a magnetic disk, the method being used for reading and writing data. A vibration detection method that selects a head other than the one that is being used and detects when a change in the data read from this head exceeds a reference value as if a vibration or impact had been applied to the device.