JPH0312061A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To preclude a head crush by counting the number of times of instantaneous contact between a magnetic head and a recording medium and operating a head-disk assembly protection circuit at the time of exceeding a prescribed number of times of the contact. CONSTITUTION:When a head-disk assembly (HDA) 7 is under the write enable and read enable state by a host control circuit 6, and when an enable signal 10 from a control circuit 5 and a hit signal 11 from an impact detecting element of the HDA 7 are inputted to a head hit detecting circuit 1, a head hit pulse 12 is sent to a head hit counter/data holding circuit 2. The number of times of a head hit is counted by the circuit 2 and sent to a head hit data comparison circuit 3. This data is compared by the circuit 3 with a prescribed value set by the circuit 6 at the time of supplying a power source, and when the data from the circuit 2 becomes larger than the prescribed value, a signal 14 is outputted, and a head crush warning lamp 8 is lit via the control circuit 5, and then after a lapse of a given period of time, the HDA 7 is stopped in its rotation. By this method, the head crush can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device, and particularly to a magnetic disk device equipped with a floating head.

[Conventional technology]

Conventionally, this type of magnetic disk drive has a head disk assembly (hereinafter referred to as HDA) that has an integrated structure of a magnetic head mechanism section and a rotation mechanism section including a storage medium. When the magnetic head in contact with the storage medium rotates at high speed,
It floats very slightly above the surface of the storage medium, allowing data to be read and written in a non-contact manner.

[Problem to be solved by the invention]

In the above-described magnetic disk drive, the dust inside the HDA is 0.3 to 0.0.
There is a drawback that contact damage between the head and the storage medium, which is called head crash, caused by intervening in the gap between the head and the floating head with a separation of 5 μm, is caused.
Another drawback is that this head crash cannot be predicted.

[Means to solve the problem]

The magnetic disk drive of the present invention includes a head hit detection circuit that detects a head hit from the impact when a magnetic head hits a magnetic medium, and a head hit counter/data storage that counts the number of outputs of the head hit detection circuit and holds data on the number of outputs. a head hit data comparison circuit for comparing preset number data with number data held in the hit counter/data holding circuit; and a head hit data comparison circuit for holding the preset number data;
a head crash warning lamp that is lit by a comparison output from the head hit comparison data holding circuit and the head hit data comparison circuit to notify an operator that a head crash may occur due to contact damage between the magnetic disk and the magnetic medium; , and an HDA protection circuit that stops the HDA after a certain period of time has passed after the warning lamp is lit.

With the above configuration, the number of instantaneous contacts between the magnetic head and the storage medium, which is a sign of a head crash, is counted, and when the number of contacts exceeds a preset number, the HDA protection circuit is activated to prevent a head crash from occurring. It can be prevented.

〔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.

Head hit detection circuit 1. Head hit counter/data holding circuit 2. Head hit data comparison circuit 3. Head hit comparison data holding circuit 4. Control circuit 5. Upper control circuit 6. HDA7. Head crash warning lamp8. HD
It is composed of the A protection circuit 9.

FIG. 2 is a partial internal configuration diagram of the HDA 7 shown in FIG. 4, and shows the storage medium 22. A magnetic head 232 rotating shaft 24° drive mechanism section 25 is shown.

FIG. 3 is a detailed configuration diagram of section A in FIG. 2, and shows the magnetic head 23.
It is shown that an impact detection element 26 is attached to detect impact force.

In FIG. 1, when the host control circuit 6 determines that the HDA 7 is in a read/write state, the head hit detection circuit 1 is caused to send an enable signal 10 from the control circuit 5. In the head hit detection circuit l, the enable signal 1
0 is input, and impact detection element 2 of HDA7
When the hit signal 11 is input from 6, it is determined that the hit signal 11 is accurate information, and the head hit counter/
A head hit pulse 12 is sent to the data holding circuit 2. Upon receiving this head hit pulse 12, the hit counter/data holding circuit 2 counts the number of head hits and transfers the data to the head hit data comparison circuit 3,
and sends it to the control circuit 5. On the other hand, head hit comparison data is input to the head hit comparison data holding circuit 4 together with the comparison data holding signal 13 via the control circuit 5 to a point predetermined by the host control circuit 6 when the power is turned on to the magnetic disk drive. The data is sent to the head hit data comparison circuit 3. The head hit data comparison circuit 3 compares the data from the head hit comparison data holding circuit 4 with the data from the head hit counter/data holding circuit 2, and when the data from the head hit counter/data holding circuit 2 becomes larger. , sends a head crush limit signal 14 to the control circuit 5. Upon receiving this signal 14, the control circuit 5 outputs a warning lamp lighting signal 15.
is activated to light up the head crash warning lamp 8 and notify the operator that there is a risk of a head crash. Further, at the same time as the warning lamp lighting signal 15 is activated, the control circuit 5 sends a protection circuit enable signal 20 to the HDA protection circuit 9. HDA
If the protection circuit 9 does not turn off the power within a certain period of time after receiving the protection circuit enable signal 20, it sends a forced stop signal 21 to the HDA 7 to stop the rotation of the HDA 7, thereby preventing a head crash. To prevent.

The above is a normal sequence, but when the power is turned off, the contents of the head hit counter/data holding circuit 2 are erased. Therefore, the power cut-off request signal 19 is transmitted to the upper control circuit 6.
, the host control circuit 6 causes the control circuit 5 to send a head hit counter data read command 17 & head hit counter/data holding circuit 2 to read the count number of the head hit counter/data holding circuit 2. . Then, the host control circuit 6 writes the data to a predetermined area in the HDAT via the HDA interface cable 18, and then turns off the power. Then, when the power is turned on again, the host control circuit 6 reads the data written when the power was turned off via the HDA interface cable 18, and sends the obtained data to the head hit counter/head hit counter via the control circuit 5. It is sent to the head hit counter/data holding circuit 2 together with the data load command 16. In this way, the number of head hits from the time when the HDA7 is assembled is counted, and when a predetermined number of head hits is reached, the operator is notified of the risk of a head crash, and at the same time, even if the operator is not present at all times, the number of head hits is counted. , head crash is prevented by automatically stopping the rotation of the HDA 7.

Note that by sending the head hit counter data read command 17 from the upper control circuit 6 via the control circuit 5, the head hit count can be read out at any time and monitored by the upper control circuit 6. Therefore, if the predetermined number of head hits has not been reached,
Even if a head crash occurs, the head hit count at that time is retained, so the failure occurrence situation can be captured as actual data.

〔Effect of the invention〕

As explained above, the magnetic disk drive of the present invention includes a head hit detection circuit, a head hit counter/data holding circuit, a head hit data comparison circuit, a head hit comparison data holding circuit, a head crash warning lamp, and a head hit counter/data holding circuit.
By having the DA protection circuit, it is possible to prevent failures caused by head crashes that could not be prevented until now, even if the operator is not present all the time. Additionally, since head hits can be measured at all times, the degree of risk of occurrence of a failure can be determined as actual data.

-4-ro a]

[Brief explanation of the drawing]

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. 3 is a detailed internal configuration diagram of a part of the head disk assembly shown in FIG. 2. l...Head hit detection circuit, 2...
Head hit counter/data holding circuit, 3...
・Head hit data comparison circuit, 4... Head hit comparison data holding circuit, 5... Control circuit,
6... Upper control circuit, 7... Head disk assembly (HDA), 8... Head crash warning lamp, 9... HDA protection circuit,
26... Impact detection element.

Claims (1)

[Claims] A head hit detection circuit that detects a head hit from the impact when a magnetic head hits a magnetic medium, and a head hit counter/data holding circuit that counts the number of outputs of this head hit detection circuit and holds data on this number of times, are preset. a head hit data comparison circuit that compares the number of hits data held in the hit counter/data holding circuit with the number data held in the hit counter/data holding circuit; a head hit comparison data holding circuit that holds the preset number data; A head crash warning lamp is lit by the comparison output from the head hit data comparison circuit to notify the operator that a head crash may occur due to contact breakdown between the magnetic head and the magnetic medium, and a certain period after the warning lamp is lit. A magnetic disk device comprising: a head disk assembly protection circuit that stops the head disk assembly over time.