JPH03259473A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To reduce the positioning time attended with the changeover of a head by making some data heads whose thermal off-track is similar bringing to one group and avoiding positioning by a data face position error signal when a different data head in the same group is selected. CONSTITUTION:When plural data heads are grouped into some groups, data heads whose thermal off-track is similar are grouped to one group. When a host device designates a new data head 54 and commands a positioning of head whose cylinder number 19 is zero and the head 54 designated newly belongs to a same group as the head 54 selected at present, a storage data face position error signal 24 is outputted as a selection data face position error signal 13. In this case, the head positioning by the data face position error signal is not implemented. Thus, the positioning time attended with the changeover of the head selection is reduced.

Description

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

[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 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;

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 each of the magnetic disk plates 51a, 51b, and 51d and the lower surface of the magnetic disk plate 51c are used as recording surfaces for recording data, and as shown in FIG. is provided with a plurality of concentric data tracks 74, and all data tracks 74 are provided with at least one servo area 75 at the same position for writing servo data. . The upper surface of the magnetic disk plate 51c is used as a servo disk (servo surface) for writing servo surface data. As shown in FIG.
0 is provided with a plurality of concentric servo tracks 71, and all of 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 data is written to the data surface 73 by the data head 54, the host device first specifies which data head should perform the write operation. That is, the head selection circuit 50 selects one data head based on the head selection signal 47 sent from the host device. Write data 60 sent from the host device is converted into a current signal for writing by the write/read drive circuit 57, and written to the magnetic disk plates 51a to 51d by the selected data head 54. On the other hand, data head 5
4, when reading the data written on the data surface by the data head 54 specified by the host device.
The readout drive circuit 5 writes the readout signal read out by
7 and discriminated by a data discrimination circuit 58 and transmitted as read data 59 to a host 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 transmitted to the write/read drive circuit 5.
After being amplified by 7, the data surface servo data 5 is input to the data surface position error signal generation circuit 4 in the position error signal generation circuit 64, where the data surface position error signal 6 is amplified.
5 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. Clock signal 3 is used as a clock signal used in the write/read clock signal and position error signal generation circuit 64.
At the same time, an index signal 61 is generated and output. Furthermore, the amplified servo surface servo data 1 is
The signal is input to the servo surface position error signal generation circuit 2 in the position error signal generation circuit 64, converted into a servo surface position error signal 66, and output. As described above, the position error signal generation circuit 64 is a circuit that generates the data surface position error signal 65 and the servo surface position error signal 66 from the data surface servo data 5 and the servo surface servo data 1, 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 83 of zero cross points of the servo surface position error signal 66
The number of tracks the head has traversed can be determined by 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 the positioning control circuit 69 receives a head positioning command (seek command 68) and the number of cylinders 19 designated via the difference cylinder register 14 from the host device, it outputs a servo surface position error signal 66 during head movement;
The voice coil motor 56 is controlled by the current flowing through the voice coil motor 56 while the head is moving, and the positioning mechanism 55 is driven to send a seek command 68 to the servo head 53.
and position the cylinder at the position specified by the cylinder number 19. 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, the signals shown in this figure are actually written on each servo track on the magnetic disk plate 51c.
The data is written continuously for one round. As shown in this figure,
The servo data signal consists of an ID signal 77, a sync signal 78, an even track position signal 79, and an odd track position signal 80. 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 combination of the placement and omission of the ID signal 77 constitutes an index signal. 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 the servo surface position error signal generation circuit 2 in the position error signal generation circuit 64. Figure 5(a)
When the servo head 53 is located at the position 53(a), position 5B(b), and position 53(C) with respect to the servo track 71, the read signals 82a, 82b, and 82c of the servo data signal are respectively the fifth
The waveform is shown in Figure (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 known from 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 shows the relationship between the data surface 73 and the data track 74. In other words, the third servo area 75 is provided after the index signal 61 (servo area 75
data area 76), data track 7
The center of each servo track 75a coincides 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. be.

Next, the head positioning control operation will be explained.

The positioning control circuit 69 receives a sea command 68 from the host device.
When inputting , the number of cylinders to be moved, 19, is also input at the same time. When the positioning control circuit 69 inputs the seek command 68, the positioning mechanism 5 moves from the number of cylinders to be moved, 19.
5 is determined, and the voice coil motor 56 is driven at the determined initial speed. While the head is moving, a servo surface position error signal 66 is generated from the servo data of the servo disk, and the actual speed of the head movement is checked from the slope of this servo surface position error signal 66 before reaching the specified speed. The voice coil motor 56 is controlled so that 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 it has moved to the specified number of cylinders. Next, the voice coil motor 56 is controlled so that the signal level of the servo surface position error signal 66 becomes zero to position the head. This completes the head positioning operation based on the servo surface data of the servo disk.

Subsequently, a fine adjustment operation for positioning the head 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, servo data in the servo area 75 of the data surface 73 is read out by the data head 54 specified by the host device, but at this time, the index signal 61
By reading from the servo data for a predetermined period of time, only the servo data can be accurately read, and therefore the signal of 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.

In general, when the ambient temperature of a magnetic disk drive changes, differences in thermal expansion coefficients occur in each part of the head positioning mechanism. A so-called thermal off-track phenomenon occurs in which positioning cannot be performed on the data track. To improve this thermal off-track, as explained above, in magnetic disk drives that use both the servo side servo method and the data side servo method, the first step is to move the head from the host device to the specified cylinder. Positioning is controlled using servo data on the servo surface of the servo disk, and then positioning of the data head is finely adjusted using servo data on the servo area of the data surface where data is actually written or data is actually read. This allows the data head to be accurately positioned on the data track where data is 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, when writing or reading data under the control of a host device, different data heads may be selected to perform writing or reading operations at the same cylinder position. Even in such cases, conventional magnetic disk drives always perform head positioning control operations based on servo data read by the newly designated data head every time a new data head is designated by the host device. Therefore, data writing and reading operations cannot be performed continuously immediately after the head selection operation, resulting in a disadvantage that the usage efficiency of the magnetic disk device in the host device is reduced.

[Means to solve the problem]

In the magnetic disk drive of the present invention, several data heads whose mounting positions are close to each other belong to one group, and when switching is performed between data heads in the same group, the data surface position error signal is A seek operation is not performed using the data surface position error signal from the data head before switching, and a seek operation is performed only when switching is performed between data heads belonging to different groups. Therefore, the data head before switching is designated as the data head when reading servo data written on the data surface.

That is, the 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 any 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; a head selection circuit that selects a designated one of the plurality of data heads based on a signal; one servo head provided corresponding to the servo surface; a positioning mechanism for mounting the magnetic disks and positioning them in designated cylinders among a plurality of concentric cylinders provided on the magnetic disk plate; a voice coil motor for driving the movement of the positioning mechanism; and a voice coil motor for driving the movement of the positioning mechanism; a write/read drive circuit that converts incoming write data and sends it to the data head as a current signal for writing, amplifies and outputs a read signal read from the magnetic disk plate by the data head; and the write/read drive circuit. a data discrimination circuit that discriminates the output signal of the circuit and sends it as read data to a host device; and a servo signal amplification circuit that amplifies the servo data signal of the servo surface read by the servo head and outputs it as servo surface servo data. , detects a clock signal included in the servo data signal and sends it to the data discrimination circuit, data surface position error signal generation circuit, and servo surface position error signal generation circuit, and generates and outputs an index signal. a clock generation circuit, a servo surface position error signal generation circuit that receives the clock signal from the clock generation circuit, converts the servo surface servo data into a servo surface position error signal, and outputs the signal; the data surface position at which a data surface position error signal is output by inputting a signal, inputting data surface servo data read out from the servo data written in the servo area of the data surface in the output signal of the write/read drive circuit; an error signal generation circuit; a head address register that inputs a head selection signal from the host device and outputs the current head address as the command signal to the head selection circuit; and a head address register that receives the current head address and the subsequent head selection signal. A classification circuit that determines whether inputs belong to the same group or not, and a classification circuit that determines whether the number of cylinders to be moved to the cylinder position specified by the host device is zero or not through a difference cylinder register. a judgment circuit for making a judgment, an AND circuit for inputting output signals of the classification circuit and the judgment circuit and outputting a selection signal, a storage circuit for storing the data surface position error signal, and a data surface position error signal generation. a selection circuit inputting the output signals of the circuit and the storage circuit and outputting one of them according to the selection signal; and a positioning control circuit that controls the operation of the motor.

〔Example〕

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

FIG. 1 is a block diagram showing one embodiment of the present invention.

In the embodiment shown in FIG. 1, section C of the conventional magnetic disk device shown in FIG. 2 is replaced with section D shown in FIG.

In FIG. 1, the head address register 11 is a register that stores the current head address 12, which is the address of the currently selected data head. Remember. The head selection circuit 5o inputs the current head address 12 and selects the data head designated by the host device from among the plurality of data heads 54. The current head address 12 is also input to the classification circuit 17. The classification circuit 17 determines to which group of the data heads 54 the input current head address 12 belongs. The classification circuit 17 also inputs the address of the next data head based on the next head selection signal 47 sent from the host device, determines which group this data head address belongs to, and distinguishes between the current head address 12 and the next head address. It is determined whether or not the address of the data head belongs to the same group.

Here, the criteria for grouping the data heads 54 will be explained.

As mentioned in the conventional technology section, magnetic disk devices are
When the ambient temperature changes, deviations occur due to differences in the coefficient of thermal expansion of each part of the head positioning mechanism, and even if the servo head is accurately positioned on the servo track, it is difficult to accurately position the data head on the data track. A so-called thermal off-track phenomenon occurs, in which it is impossible to FIG. 7 is a characteristic diagram showing the relationship between the position of the data head and the amount of thermal off-track in such a thermal off-track phenomenon. When dividing a plurality of data heads into several groups, data heads having similar thermal off-track amounts are assigned to one group. In the example of FIG. 7, the data head addresses (0 to 3) are considered to be one group, and the data head addresses (4 to 7) and (
8 to 11> and (12 to 15>) are each made into another group.

The difference cylinder register 14 is a circuit that inputs and stores the number of cylinders to be moved to position the head from a host device. The determination circuit 18 determines the number of cylinders 19 stored in the difference cylinder register 14.
This is a circuit that determines whether or not is zero. When selecting different data heads on the same cylinder, the host device instructs the head positioning operation by setting the number of cylinders 19 to zero. The AND circuit 16 inputs the outputs of the classification circuit 17 and the determination circuit 18, and determines that the address of the next data head designated by the host device currently belongs to the same group as the head address 12, and that the number of cylinders is 19. When it is zero, a selection signal 15 is output.

The data head 54 currently designated by head address 12 is selected, and the read signal read by the selected data head 54 is amplified by the write/read drive circuit 57 . The read signal read by the data head 54 also includes data surface servo data, and the data surface servo data 5 is input to the data surface position error signal generation circuit 4 and converted into a data surface position error signal 65. On the other hand, the read signal read out by the servo head 53 is sent to the servo signal amplification circuit 65.
Servo surface servo data 1 amplified by
is input to the servo surface position error signal generation circuit 2 and converted into a servo surface position error signal 66.

The storage circuit 8 stores the level of the data surface position error signal 65 generated by the data head 54 selected at that time when the servo head 53 is positioned so that the servo surface position error signal 66 becomes zero in the head positioning operation. . The selection circuit 10 selects the data surface position error signal 65 and the stored data surface position error signal 24 stored in the storage circuit 8.
and the selection signal 15 is active (the selection signal 15 becomes active when the current head address 12 and the next data head address belong to the same group and the number of cylinders 19 is zero). When the selection signal 15 is inactive, the stored data surface position error signal 24 is output as the selected data surface position error signal 13, and when the selection signal 15 is inactive, the data surface position error signal 65 is output as the selected data surface position error signal 13. The positioning control circuit 69 inputs the servo surface position error signal 66 and the selected data surface position error signal 13, and controls the operation of the voice coil motor 56 so that the sum of these signals becomes zero. 54 positioning is performed.

Here, if the host device specifies a new data head and instructs a head positioning operation with the number of cylinders 19 being zero,
When the newly specified data head belongs to the same group as the currently selected data head, select the storage data surface position error signal 24 and select the data surface position error signal 1.
Output as 3. At this time, since the sum of the input signals of the six positioning control circuits is the same as that for the currently selected data head, no positioning operation of the data head is performed using the data surface position error signal.

On the other hand, when the newly designated data head belongs to a different group from the currently selected data head, the data surface position error signal of the newly designated data head is output as the selected data surface position error signal 13. Therefore, a data head positioning operation is performed using the data surface position error signal.

〔Effect of the invention〕

As explained above, in the magnetic disk drive of the present invention, several data heads with similar thermal off-track amounts belong to one group, and when different data heads in the same group are selected, the data By not performing the positioning operation based on the surface position error signal, there is an effect that the time required for the positioning operation accompanying switching of head selection can be shortened.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an example of a conventional magnetic disk device, and FIG. 3 is a block diagram showing an example of a conventional magnetic disk device.
The figure is a plan view showing the servo disk of the example in Fig. 2, Fig. 4 <a) and (b) are a plan view and an enlarged development view of section A, and Fig. 5 (a) is a plan view showing the data surface of the example in Fig. 2. ) and (b) are a plan view showing the servo data signal written on the servo track on the servo disk in the example of FIG. 2, and a waveform diagram showing the readout signal, and FIGS. 6(a) and (b) 7 is a plan view showing the servo track of the example of FIG. 2 and a waveform diagram showing the position error signal, and FIG. 7 is a characteristic diagram showing the relationship between the data head address and the thermal off-track amount in the example of FIG. 1. . l... Servo surface servo data, 2...
Servo surface position error signal generation circuit, 3... Clock signal, 419114. Data surface position error signal generation circuit, 5... Data surface position error signal generation circuit, 6...
・Logic product circuit, 8...Memory circuit, 10...
...Selection circuit, 11...Head address register,
12...Current head address, 13...Selection data surface position error signal, 14...Difference cylinder register, 15...Selection signal, 1
6...60. AND circuit, 17...Classification circuit, 18...Judgment circuit, 1...Number of cylinders, 24...Stored data surface position error signal, 4
7...Head selection signal, 50...Head selection circuit, 51a, 51b, 51c, 51d...
... Magnetic disk plate, 52 ... Spindle motor, 53 ... Servo head, 54 ...
Data head, 55...Positioning mechanism, 56.
...Voice coil motor, 57...Write/read drive circuit, 58...Data discrimination circuit,
59...Read data, 60...Write data, 62...Clock generation circuit, 63...
... Servo signal amplification circuit, 64 ... Position error signal generation circuit, 65 ... Data surface position error signal, 66 ... Servo surface position error signal, 67・
...Spindle motor drive circuit, 68...
・Seek command, 69...Positioning control circuit, 7
0...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
...Sync 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 any one of the recording surfaces on both sides serving as a servo surface and the remaining surface as a data surface, and the plurality of data heads are activated by a command signal. a head selection circuit that selects one designated data head among them, one servo head provided corresponding to the servo surface, and a head selection circuit that mounts the data head and the servo head and transfers them to the magnetic disk. A positioning mechanism that positions a designated cylinder among multiple concentric cylinders provided on a plate, a voice coil motor that drives the movement of the positioning mechanism, and a voice coil motor that converts write data sent from a host device. a write/read drive circuit that amplifies and outputs a read signal read from the magnetic disk plate by the data head to the data head as a write current signal; a data discrimination circuit that separately transmits read data to a host device; a servo signal amplification circuit that amplifies the servo data signal of the servo surface read by the servo head and outputs it as servo surface servo data; a clock generation circuit that detects a clock signal contained in the clock signal and sends it to the data discrimination circuit, the data surface position error signal generation circuit, and the servo surface position error signal generation circuit, and also generates and outputs an index signal; the servo surface position error signal generation circuit which inputs the clock signal from the clock generation circuit and converts the servo surface servo data into a servo surface position error signal and outputs the signal; the data surface position error signal generating circuit inputting data surface servo data read out from the servo data written in the servo area of the data surface in the output signal of the read drive circuit and outputting a data surface position error signal; a head address register that receives a head selection signal from the host device and outputs the current head address as the command signal to the head selection circuit;
a classification circuit that inputs the current head address and the subsequent head selection signal and determines whether they belong to the same group; a determination circuit that determines whether the number of cylinders moved to the cylinder position is zero; an AND circuit that inputs the output signals of the classification circuit and the determination circuit and outputs a selection signal; and the data surface position error. a storage circuit that stores signals; a selection circuit that receives the output signals of the data surface position error signal generation circuit and the storage circuit and outputs one of them according to the selection signal; and an output signal of the selection circuit. and a positioning control circuit that controls the operation of the voice coil motor by inputting the servo surface position error signal and the servo surface position error signal.