JPH03259477A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce the time required for head positioning by implementing a data face servo operation only when a temperature change in a magnetic disk device is larger than a reference value. CONSTITUTION:An arithmetic circuit 2 receives an output of a temperature detector 1 at a prescribed time interval, calculates the difference with a precedingly inputted temperature at each input and outputs a temperature difference signal 3. A comparator circuit 4 compares the temperature difference signal 3 with a reference value and outputs a data face servo operating command signal 5 when the signal 3 is a prescribed value or over. A positioning control circuit 6 receives a servo face positioning error signal 66 and a data face position error signal 65 and uses the error signal 66 when an object cylinder is positioned by the head positioning operation and the data face servo operation by the error signal 65 is not executed till the command signal 5 from the comparator circuit 4 is received. Thus, only when the temperature change in the device is larger than the reference value, the data face servo operation is implemented. Then the time required for the head positioning is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device that employs a magnetic head positioning method that uses both a servo surface servo method and a data surface servo method among magnetic disk devices.

[Conventional technology]

Among conventional magnetic disk drives that use a track-following magnetic head positioning system, we are particularly concerned with magnetic disk drives that use a magnetic head positioning system that combines a servo surface servo system and a data surface servo system. This will be explained with reference to FIGS. 2 to 6.

Fig. 2 is a block diagram showing an example of a conventional magnetic/magnetic disk device, Fig. 3 is a plan view showing the servo disk of the example shown in Fig. 2, and Figs. 4 (a) and (b) are A plan view showing the data surface of the example and an enlarged developed view of part A; FIGS. 5(a) and (b) are planes showing the servo data signals written on the servo tracks on the servo disk of the example in FIG. FIGS. 6(a) and 6(b) are a plan view showing the servo track of the example of FIG. 2 and a waveform chart showing the position error signal.

In FIG. 2, magnetic disk plates 51a, 51b, 51c, and 51d are driven by a spindle motor 52 to rotate. The rotation of the spindle motor 52 is controlled by a spindle motor drive circuit 67 to maintain a constant rotation speed. magnetic disk plate 51
The upper and lower surfaces of the magnetic disk plates 51a, 51b, and 51d and the lower surface of the magnetic disk plate 51c are used as data surfaces for recording data.As shown in FIG. , a plurality of concentric data tracks 74 are provided, and all data tracks 74 are provided with a servo area 75 in which servo data is written at the same position. In addition, the magnetic disk plate 5
The upper surface of 1c is used as a servo disk (servo surface) for writing servo data on the servo surface.
As shown in the figure, the servo disk 70 is provided with a plurality of concentric servo tracks 71, and all the servo tracks 71 are provided with an index signal area 72 at the same position. Each data surface includes a plurality of data heads 54 for writing data on the data surface and reading data written on the data surface, and one servo head 53 for reading servo data of the servo disk. and servo surfaces, but these heads are mounted on one positioning mechanism 55, and all the heads are integrated into a cylinder on a predetermined position on the magnetic disk plates 51a to 51d. (data track). The positioning mechanism 55 is driven in its positioning operation by a voice coil motor 56.

When writing data to the data surface 73 using the data head 54, the write data 6 sent from the host device
0 is converted into a current signal for writing by the write/read drive circuit 7, and written to the magnetic disk plates 51a to 51d by the data head 54. On the other hand, when reading data written on the data surface by the data head 54, the read signal read by the data head 54 is amplified by the write/read drive circuit 57, discriminated by the data discrimination circuit 58, and output as read data 59. Send to higher-level device. At this time, the read signal read out by the data head 54 also includes a signal resulting from reading out the servo data written in the servo area 75 on the data surface.

Therefore, this servo data read signal is amplified by the write/read drive circuit 57 and then input to the position error signal generation circuit 64, where it is converted into a data surface position error signal 65 and output.

On the other hand, the servo surface servo data signal read by the servo head 53 is amplified by the servo signal amplification circuit 63, and then the clock signal contained therein is used by the clock generation circuit 62 in the data discrimination circuit 58. The index signal 61 is sent out as a write/read clock signal and a clock signal used in the position error signal generation circuit 64, and also generates and outputs an index signal 61. Further, the amplified servo surface servo data signal is inputted to a position error signal generation circuit 64 to generate a servo surface position error signal 66.
is converted and output. The position error signal generation circuit 64 is
As described above, this circuit generates the data surface position error signal 65 and the servo surface position error signal 66 from the servo surface servo data signal and the data surface servo data signal, respectively. As shown in FIGS. 5 and 6, the servo surface position error signal 66 is a reference signal for head positioning control, and the number of zero-crossing points 83 of the servo surface position error signal 66 determines the track traversed by the head. You can know the number of Further, the moving speed of the head can be determined from the slope of the servo surface position error signal 66, and the distance to the target track can also be determined from the magnitude of the signal level. On the other hand, the distance from the target data track to the data head 54 can be known from the signal level of the data surface position error signal 65.

When a head positioning command (seek command 68) is input from the host device, the positioning control circuit 69 inputs the number of cylinders up to the cylinder specified by the seek command 68, the servo surface position error signal 66 during head movement, and the head position error signal 66. The voice coil motor 56 is controlled by the current flowing through the voice coil motor 56 during the movement of the servo head 53, and the positioning mechanism 55 is driven to position the servo head 53 at the cylinder position designated by the seek command 68. Furthermore, after positioning the head at the target cylinder position, the positioning control circuit 69 controls the voice coil motor 56 based on the data surface position error signal 65 to drive the positioning mechanism 55, thereby fine-tuning the positioning of the data head 54. control.

5 and 6 regarding the servo data signal written on the servo track on the servo disk and the servo surface position error signal 66 generated from the servo data signal.
This will be explained with reference to the figures. The same applies to the servo data signal of the servo area on the data surface and the data surface position error signal generated from the servo data signal.

Although FIG. 5 shows a part of the servo data signal written on the servo track 71, in the actual servo track, the signal shown in this figure is continuously written on the servo track for one revolution of the magnetic disk plate 51c. It is written. As shown in this figure, the servo data signals include an ID signal 77, a sync signal 78, an even track position signal 79, and an odd track position signal 8.
It consists of 0. The even track position signal 79 and the odd track position signal 80 are two types of position signals having different phases. The sync signal 78 is supplied to the clock generation circuit 6
2 is used as a reference signal for generating a clock signal. Also, the ID signal 77 is the normal sync signal 7.
However, there are places where the ID signal 77 is missing, such as an ID signal missing place 81 shown in FIG.

The servo data signal in the index signal area 72 of the servo track 71 includes this ID signal missing location 81.
are provided at several locations, and the index signal is determined by a combination of the placement and omission of the ID signal 77. The clock generation circuit 62 detects the presence or absence of the ID signal 77 of the servo data signal, thereby detecting a combination of placement and omission of the ID signal 77, and generates the index signal 61. Even track position signal 79 of servo data signal
The odd track position signal 80 is converted into a servo surface position error signal 66 in a position error signal generation circuit 64. In FIG. 5(a), the rad 53 is at position 53(a) and position 53 with respect to the servo track 71 to the servo.
(b) and read signals 82a, 82b, and 82c of servo data signals when located at position 53(c)
have the waveforms shown in FIG. 5(b).

On the other hand, the servo surface position error signal 66 is a signal proportional to the difference in read signal level between the even track position signal 79 and the odd track position signal 80. As shown in FIG. 6(a), when the servo head 53 moves in the direction of arrow B on the servo track 71, the servo surface position error signal 66 is
The waveform is shown in FIG. 6(b). As shown in the figure, a zero-crossing point 83 of the servo surface position error signal 66 occurs when the servo head 53 is located at the boundary between two adjacent servo tracks. During head movement, the number of servo tracks (cylinders) traversed by the servo head 53 can be determined by the number of zero cross points 83. Furthermore, since the slope of the servo surface position error signal 66 is proportional to the moving speed of the servo head 53, it is used to detect the moving speed of the head. Furthermore, the servo surface position error signal 6
The signal level 6 indicates the distance from the boundary of adjacent servo tracks, that is, the zero cross point 83 to the servo head 53.

FIG. 4 also shows the relationship between data surface 73 and data track 74. FIG. That is, the servo area 75 is provided after the index signal 61 (servo area 7
5 are data areas 76), and the center of the data track 74 is arranged to coincide with the boundary between two adjacent servo tracks 75a. This is because the positioning of the servo head 53 and data head 54 is controlled so that the servo surface position error signal 66 is at zero level, that is, the servo head 53 is positioned at the boundary between two adjacent servo tracks 71. It is.

Next, the head positioning control operation will be explained.

The positioning control circuit 69 receives a seek command 68 from the host device.
When entering , also enter the number of cylinders to be moved. When the positioning control circuit 69 inputs the seek command 68, it determines the initial speed of movement of the positioning mechanism 55 from the number of cylinders to be moved, and drives the voice coil motor 56 at the determined initial speed. While the head is in motion, a servo surface position error signal 66 is generated from the servo surface servo data of the servo disk, and the actual speed of the head movement is calculated from the slope of this servo surface position error signal 66 by 1i! The voice coil motor 56 is controlled to reach the specified speed. Further, the number of cylinders crossed by the head is determined from the number of zero cross points 83 of the servo surface position error signal 66 of the servo surface servo data. This confirms that the head has moved up to the designated number of cylinders, and then controls the voice coil motor 56 to position the head so that the signal level of the servo surface position error signal 66 becomes zero. This completes the head positioning operation based on the servo surface data of the servo disk.

Next, a fine adjustment operation for head positioning is performed using servo data in the servo area 75 of the data surface 73 where data is written or read. This fine adjustment operation for head positioning is called a data surface servo operation. In the data surface servo operation, the data head 54 reads out the servo data in the servo area 75 of the data surface 73. At this time, it is possible to accurately read only the servo data by reading out the index signal 61 for a predetermined time. I can do it,
Therefore, the signal on the data track 74 on the data surface will not be read out by mistake. A data surface position error signal 65 is generated from the servo data read from the servo area 75, and the voice coil motor is controlled in six positioning control circuits so that the signal level of the data surface position error signal 65 from the servo area 75 becomes zero level. 56.

As explained above, in a magnetic disk drive that uses both the servo surface servo method and the data surface servo method, in order to move the head from the host device to the designated cylinder, the positioning is first performed using the servo surface servo data of the servo disk. Then, the positioning of the data head is finely adjusted by the servo data of the servo area of the data surface where data is actually written or data is actually read.

This improves so-called thermal off-track, which occurs when the positioning mechanism shifts when the ambient temperature of the magnetic disk drive changes, making it impossible to accurately position the data head on the data track even if the servo head is positioned accurately. The data head can be accurately positioned on the data track to be written or read.

[Problem to be solved by the invention]

Conventional magnetic disk drives that use both the servo surface servo method and the data surface servo method described above finely adjust the positioning of the data head using servo data written on the data surface. There is.

However, in order to move the head to the cylinder specified by the host device, first a positioning operation is performed using servo data on the servo surface of the servo disk, and then the servo data on the data surface to be actually written or read is used. Because the data surface servo operation is performed to finely adjust the positioning of the data head based on the servo data of the area, and because it is necessary to perform the data surface servo operation every time a data head is selected, the time required for the head positioning operation, i.e. The disadvantage is that the seek time becomes longer.

[Means to solve the problem]

A magnetic disk device of the present invention includes a plurality of magnetic disk plates, a spindle motor that rotates the magnetic disk plates, and a spindle motor drive circuit that controls the rotation of the spindle motor so that the rotation speed is constant. a plurality of data heads provided corresponding to the data surface, with an arbitrary one surface of the recording surfaces on both sides of the plurality of magnetic disk plates as a servo surface and the remaining surface as a data surface; and a plurality of data heads provided corresponding to the data surface; One servo head provided corresponding to the data head and the servo head are mounted and positioned in a designated cylinder among a plurality of concentric cylinders provided on the magnetic disk plate. A positioning mechanism, a voice coil motor that drives the movement of the positioning mechanism, converts a write signal sent from a host device, sends it to the write head as a current signal for writing, and sends it from the magnetic disk plate by the data head. a write/read drive circuit that amplifies and outputs the readout signal read out; a data discrimination circuit that discriminates the output signal of the write/readout drive circuit and transmits it as a readout signal to a host device; and a servo surface servo read out by the servo head. a servo signal amplification circuit that amplifies and outputs a data signal; a clock signal included in the output signal of the servo signal amplification circuit is detected and sent to the data discrimination circuit and the position error signal generation circuit; a clock generation circuit that generates and outputs an index signal; and a clock generation circuit that receives the clock signal from the clock generation circuit, converts the signal from the servo signal amplification circuit into a servo surface position error signal, and outputs the signal, and drives the write/read drive. the position error signal generation circuit which inputs a signal read out servo data written in the servo area of the data surface in the output signal of the circuit and outputs a data surface position error signal; and a seek command and the position of the servo surface. a positioning control section that inputs an error signal and the data surface position error signal to drive the voice coil motor; calculation means for detecting the temperature of the magnetic disk drive by detecting a signal and calculating the difference from the previously detected temperature; and comparison means for determining the temperature difference obtained by the calculation means by comparing it with a reference value. and a positioning control circuit that drives the voice coil motor so that the level of the data surface position error signal becomes zero level when the temperature difference obtained by the comparison means is larger than a predetermined temperature difference. There is.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the main parts of an embodiment of the present invention.

In the embodiment shown in FIG. 1, the positioning control circuit 69 of the conventional magnetic disk device (see FIG. 2) shown in FIG. 2 is replaced with the positioning control section 9 shown in FIG.

In FIG. 1, a temperature detector l is used to detect the temperature of a magnetic disk device. The arithmetic circuit 2 receives the output of the temperature detector 1 at regular time intervals, calculates the difference from the previously input temperature each time it is input, and outputs a temperature difference signal 3. Comparison circuit 4 compares temperature difference signal 3 with a reference value, and outputs data surface servo operation instruction signal 5 when the temperature difference signal 3 is equal to or greater than a predetermined value.

The positioning control circuit 6 receives a servo surface position error signal 66 and a data surface position error signal 65 similarly to the conventional positioning control circuit 69, and detects the servo surface position error when positioning to a target cylinder in head positioning operation. Although the signal 66 is used, the data surface servo operation based on the data surface position error signal 65 is not executed until the data surface servo operation instruction signal 5 from the comparator circuit 4 is input. In this way, the data surface servo operation is performed only when the temperature change of the magnetic disk device becomes larger than the reference value. IT and operations other than those described above are the same as those of the conventional magnetic disk device described above.

〔Effect of the invention〕

As explained above, the magnetic disk drive of the present invention reduces the time required for the head positioning operation by performing the data surface servo operation only when the temperature change of the magnetic disk drive becomes larger than a reference value. This has the effect of being able to shorten the time.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main parts of an embodiment of the present invention;
Fig. 2 is a block diagram showing an example of a conventional magnetic disk device, Fig. 3 is a plan view showing a servo disk of the example of Fig. 2, and Figs. 4 (a) and (b) are of the example of Fig. 2. 5(a) and 5(b) are a plan view showing the data surface and an enlarged developed view of part A; FIGS. Waveform diagrams showing the readout signal, FIGS. 6(a) and (
b) is a plan view showing the servo track of the example of FIG. 2 and a waveform diagram showing a position error signal; 1... Temperature detector, 2... Arithmetic circuit,
3... Temperature difference signal, 4... Comparison circuit,
5...Data surface servo operation instruction signal, 6...
...Positioning control circuit, 9...Positioning control section, 51a, 51b, 51c, 51d...Magnetic disk plate, 52...Spindle motor 5
3...Servo head, 54...Pig head, 55...Positioning mechanism, 56...
・Voice coil motor, 57...Write/read drive circuit, 58...Data discrimination circuit, 59...
...Read data, 60...Write data, 61...Index signal, 62...
・Clock generation circuit, 63...Servo signal amplification circuit, 64...Position error signal generation circuit, 65...
...Position error signal, 66...Sabot surface position error signal, 67...Spindle motor drive circuit, 68
... Seek command, 69 ... Positioning control circuit, 70 ... Servo disk, 71 ...
... Servo track, 72 ... Index signal area, 73 ... Data surface, 74 ...
...Data track, 75...Servo area,
76...Data area, 77...ID
Signal, 78...Sink signal, 79...
Even track position signal, 80...Odd track position signal, 81...ID signal missing location, 82...
...Read signal, 83...Zero cross point.

Claims (1)

[Claims] A plurality of magnetic disk plates, a spindle motor for rotating the magnetic disk plates, a spindle motor drive circuit for controlling the rotation of the spindle motor so that the rotation speed is constant, and a spindle motor driving circuit for controlling the rotation of the plurality of magnetic disk plates. A plurality of data heads are provided corresponding to the data surface, with one arbitrary surface of the recording surfaces on both sides being a servo surface and the remaining surface being a data surface, and one data head provided corresponding to the servo surface.
a positioning mechanism that mounts the data head and the servo head and positions them in a designated cylinder among a plurality of concentric cylinders provided on the magnetic disk plate, and the positioning mechanism a voice coil motor that drives the motion of the magnetic disk, and a voice coil motor that converts write data sent from a host device and sends it to the data head as a write current signal, and amplifies the read signal read from the magnetic disk board by the data head. a write/read drive circuit for outputting the servo data, a data discrimination circuit for discriminating the output signal of the write/read drive circuit and transmitting it as read data to a host device, and amplifying the signal of the servo surface servo data read by the servo head. a servo signal amplification circuit that outputs a servo signal amplification circuit, and detects a clock signal included in the output signal of the servo signal amplification circuit and sends it to the data discrimination circuit and position error signal generation circuit, and generates an index signal. a clock generation circuit that inputs the clock signal from the clock generation circuit, converts the signal from the servo signal amplification circuit into a servo surface position error signal, and outputs the servo surface position error signal; The position error signal generation circuit inputs a signal read out servo data written in the servo area of the data surface and outputs a data surface position error signal, and a seek command, the servo surface position error signal, and the data surface. a positioning control unit that inputs a position error signal and drives the voice coil motor,
The positioning control unit detects the temperature of the magnetic disk device by detecting a temperature detector and an output signal from the temperature detector at regular time intervals, and calculates a difference between the previously detected temperature. means for determining the temperature difference obtained by the calculation means by comparing it with a reference value; and a comparison means for determining the temperature difference obtained by the calculation means; and a positioning control circuit that drives the voice coil motor so that the level of the voice coil motor becomes zero level.