JPH0358362A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To prevent trouble due to a head crush by counting the number of head hitting times detected by a detecting circuit and lighting a warning lamp when its value exceeds a preset allowable value. CONSTITUTION:When an enable signal is sent from a control circuit 6 to a head hitting detection circuit 2, the head hitting is detected by the circuit 2 from a signal detected by a vibration detecting element of a head disk assembly (HDA) 1, and the number of this hitting times is counted by a head hitting counter / data holding circuit 8. On the other hand, a data of a preset head hitting allowable number is outputted by a head hitting comparison data holding circuit 4 to a head hitting comparison circuit 5 to be compared with the count number data from the circuit 3, and when the number of head hitting times exceeds the allowable number, a head crush limit signal is sent to the circuit 6. When this signal is received by the circuit 6, a head crush warning lamp 7 is lit, thus preventing the trouble due to the head crush.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk drive, and more particularly to a magnetic disk drive having a function of preventing damage caused by contact between a magnetic head and a magnetic disk.

[Prior Art] A conventional magnetic disk device records and reproduces information by combining a rotating disk (magnetic disk) whose surface is coated with a magnetic material and a magnetic head.

[Problems to be Solved] In the above-described conventional magnetic disk device, when the magnetic disk is operated for a long period of time with the magnetic disk in the same position, dust adheres to the magnetic head. This dust contains small pieces of magnetized metal, which often causes information stored on magnetic disks to be erased.

In the worst case, dust with a thickness of <t4M may get between the magnetic head and the high-speed rotating magnetic disk, causing a fatal accident such as contact failure between the head and disk, a so-called crash. There was. Further, there is no preventive measure until the phenomenon actually occurs, and it is difficult to predict when a head crash will occur.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a magnetic disk device having a function of preventing failures caused by head crashes by detecting head hits, which are a sign of head crashes. shall be.

[Solving the Problems] In order to achieve the above object, a magnetic disk device of the present invention includes a magnetic disk and a magnetic head, and a head disk assembly for detecting the vibration frequency of the magnetic disk;
A head hit detection circuit that detects a head hit based on a signal from the head disk assembly, a head hit counter/data holding circuit that counts and holds the number of head hits, and a head hit prevention circuit that prevents head crashes. a head hit comparison data holding circuit that approximates and holds the allowable number of inputs; a head hit data comparison circuit that compares the data of this head hit comparison data holding circuit with the data of the head hit counter/data holding circuit; The system is equipped with head crash warning means that operates based on the comparison results in the data comparison circuit.

[Example] An example of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a magnetic disk device according to an embodiment of the present invention.

In the drawing (in which l is the head disk assembly (hereinafter referred to as H)
It is called DA. ). As shown in FIGS. 2 and 3, this HDA I includes a magnetic disk 11 that rotates at high speed around a rotating shaft 14, and a drive mechanism that is provided at a position facing the magnetic disk 11 and that moves up and down. 15, and a magnetic head l2 attached to the magnetic head l2. Furthermore, a vibration detection element l3 is attached near the magnetic head l2, which detects the vibration of the magnetic head l2 and sends out the detected vibration as a hit signal 100.

2 is a head hit detection circuit (hereinafter referred to as the detection circuit).
It is. Based on the hit signal 100 inputted from the IDA 1, the detection circuit 2 determines that the moment the magnetic head 12 comes into contact with the magnetic disk 11, it is a head hit.

> is detected, and this detection result is sent to the head hit pulse signal 2.
Send as 00.

Reference numeral 3 denotes a head hit counter/data holding circuit (hereinafter referred to as a counter/data holding circuit), which counts the number of head hits based on the head hit pulse signal 200 from the detection circuit 2. Hold.

Reference numeral 4 denotes a head hit comparison data holding circuit (hereinafter referred to as the comparison data holding circuit), in which data setting the situation in which a head crash occurs, in this case, the permissible number of head hits to prevent a head crash is input. .

Reference numeral 5 denotes a head hit data comparison circuit (hereinafter referred to as a data comparison circuit), which compares the data content of the comparison data holding circuit 4 with the data content of the counter/data holding circuit 3. When the data in the counter/data holding circuit 3 becomes larger than the data in the comparison data holding circuit 4, that is, when the number of head hits exceeds the set permissible number a, there is a risk of a head crash. A head crush limit signal 400 is sent to the control circuit 6.

The control circuit 6 sends an enable signal 600 to the detection circuit 2.
, a head hit counter/data command signal 601 to the counter/data holding circuit 3, and a comparison data holding signal 602 to the comparison data holding circuit 4. Further, when the control circuit 6 receives the head crash limit signal 400 from the data comparison circuit 5, it transmits a warning lamp lighting signal 603 and lights the head crash warning lamp 7.

Also, 8 is an HDA interface cable,
DA 1 and control circuit 6 are connected.

Next, the operation of the magnetic disk device having such a configuration will be explained.

First, when the magnetic disk device is in a write/readable state, the control circuit 6 sends the detection circuit 2 to the detection circuit 2.
In response, an enable signal 600 is sent out. As a result, the detection circuit 2 detects a head hit from the hit signal 100 detected by the HDAl vibration detection element l3, and sends this to the counter/data holding circuit 3 as a head hit pulse signal 200. The counter/data holding circuit 3 receives the head hit counter/data from the control circuit 6.
Based on the data load command signal 601, the head hit pulse signal 200, that is, the number of head hits is counted.

On the other hand, the comparison data holding circuit 4 receives the comparison data holding signal 602 from the control circuit 6 and sends the data contents of a preset allowable number of head hits to the data comparison circuit 5. and data comparison circuit 5
Now, the data from the comparison data holding circuit 4 and the counter/
The data from the data holding circuit 3 is compared. As a result of the comparison, if the risk of a head crash increases, the data comparison circuit 5 sends a head crash limit signal 400 to the control circuit 6. Upon receiving this signal, the control circuit 6 transmits a warning lamp lighting signal 603 to the head crash warning lamp 7, and lights up the head crash warning lamp 7 to visually foresee the danger of a head crash.

The above is a normal sequence, but when the power is turned off, the data content obtained by the counter/data holding circuit 3 is lost. Therefore, in order to avoid this, 1
When the iW disconnection request signal 700 is input to the control circuit 6,
The control circuit 6 reads the head hit count number of the counter/data holding circuit 3 through the data path. and,
The read head hit count number is written into a predetermined area in the HDA 1 via the HDA interface cable 8, and then the power is turned off.

When the power is turned on again at a later date, the data written in the HDAI is read into the control circuit 6 via the HDA interface cable 8, and sent to the counter/data holding circuit 3 along with the head hit counter/data load command signal 601. Ru. This brings the device into a state just before the power is turned off, and it operates in the normal sequence described above.

In this embodiment, a lamp is used as a head crash warning means, or other commonly used warning means may be used.

[Effects of the Invention] As explained above, according to the present invention, there is an effect that failures caused by head crashes can be prevented.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a magnetic disk device according to an embodiment of the present invention, FIG. 2 is a schematic diagram of an HDA which is the main part of this embodiment, and FIG. 3 is an enlarged schematic diagram of part A of FIG. 2. be. 1: HDA (head disk assembly) 2: Head hit detection circuit 3: Head hit counter/data holding circuit 4: Head hit comparison data holding circuit 5. Head hit data comparison circuit

Claims (1)

[Claims] A head disk assembly that includes a magnetic disk and a magnetic head and detects the frequency of the magnetic disk; and a head hit detection circuit that detects a head hit based on a signal from the head disk assembly. , a head hit counter/data holding circuit that counts and holds the number of head hits, a head hit comparison data holding circuit that inputs and holds the allowable number of head hits in advance to prevent head crashes, and this head hit comparison data. A head hit data comparison circuit that compares data in the holding circuit with data in the head hit counter/data holding circuit; and head crash warning means that operates based on the comparison result in the head hit data comparison circuit. magnetic disk device.