JPS60191481A - Disk device - Google Patents

Abstract

PURPOSE:To improve the reliability to temperature variation and reduce the off- track margin of a disk as compared with a conventional device by providing a correcting means which corrects a head positioning mechanism according to temperature variation. CONSTITUTION:A servo head 6 is positioned at a constant position, so the maximum off-track quantity of a data head 7 at this time is Xa, but a data head 4 coupled with an actuator 8 has an offset -Xa/2 and the off-track quantity is Xa-Xa/2=Xa/2 because the servo head is given an offset -Xa/2 with an offset voltage impressed from a temperature compensating circuit 17. Similarly, the off-track quantity is suppressed in low-temperature operation to Xb-Xb/2= Xb/2. The total off-track quantity in high-temperature and low-temperature operation is ¦Xa/2-Xb/2¦, which is reduced to a half as large as usual. The output offset voltage of the temperature compensating circuit 17 is set equally corresponding to the temperature in a main body case 1, but the offset voltage may be adjusted finely for every data head 7 synchronously with a head switching signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a disk device, particularly to temperature compensation of a head positioning control mechanism.

[Prior art]

Generally, a magnetic disk drive is configured as shown in FIG. In the figure, 1 is a main body case, and the main body case 1 is provided with a spindle 2 that is rotated by a motor (not shown). The spindle 2 has a recording surface consisting of concentric information tracks on both sides, and a disc-shaped magnetic disk 3 having a hole in the center is integrated with the spindle 2 and separated from each other. A magnetic head 4 for recording and reproducing is held on the recording surface of the magnetic disk 3 by a head arm 5. The magnetic head 4 is assigned to a servo head 6 for reading position information recorded on one of the plurality of recording surfaces of the magnetic disk 3, and a data head 7 for reading and writing data on the other recording surface. The head arms 5 each have the same shape, are attached to an actuator 8 as a head positioning mechanism, and are moved together in the radial direction of the magnetic disk 3 by the drive of the actuator 8.
The magnetic head 4 is moved. A signal from the position detector 9 is supplied to the actuator via a position setting circuit 10, a control mode switching circuit 11, and a power amplifier 12. The operation of the disk device with the above configuration will be explained below.

Position information written on one side of the recording surface of the magnetic disk 3 is read out by the servo head 6, and the current position of the magnetic head is detected by the position detector 9. Position setting circuit 1
0 inputs a control signal to the actuator 8 via the control mode switching circuit 11 and the power amplifier 12 to control the actuator 8 so that the displacement between the target position and the current position is always zero. The control mode switching circuit 11 has switching contacts for a position control mode 13 and a speed control mode 14.

As described above, the actuator 8 is driven to move the head arm 5 and all the data heads 7 can be positioned on the target information track.

However, an expansion difference occurs between each of the same-shaped helad arms 5 that move together due to a temperature difference within the main body case 1, and if the expansion difference differs between when recording and reproducing information. It becomes a problem.

Figures 3 and 4 show the servo head 6 due to the above expansion difference.
This is an enlarged view of the positional relationship of Sodo 7 and data. FIG. 3 shows the high-temperature operation, and FIG. 4 shows the low-temperature operation. For example, during high-temperature operation, the temperature difference between the upper and lower parts of the main body case 1 becomes larger than that at normal temperatures, so the data head 7 moves to the maximum in the direction of the spindle 2 with the servo head 6 as a reference, as shown in FIG. Distance Xa off-track. Conversely, during low-temperature operation, the data head 7 off-tracks by a maximum distance xb in the opposite direction to that during high-temperature operation, as shown in FIG. Since the servo head 6 corresponds to the position information on the servo surface, it is always positioned on the target information track on the magnetic disk 3 regardless of the temperature, but the data head 7 changes the maximum distance Xa and xb according to temperature changes.
Off-track will occur. Thus, high temperature.

Xa,l! during low temperature operation! :Xb off-track occurs, but since this conventional device is not equipped with a means to detect and correct this off-track, considering what happens when data is written at a high temperature and read at a low temperature, Unless each information track on the magnetic disk 5 has an off-track margin of width 1Xa-Xb1 or more, this device cannot be expected to function normally. However, the information tracks of the magnetic disk 3 are configured with high density, and the information tracks are becoming increasingly dense in line with recent demands for miniaturization and increased recording capacity of this device. Currently, it is becoming difficult to provide an off-track margin.

As described above, in the conventional device, it is necessary to strictly control the temperature change inside the main body case 1, and a sufficient off-track margin is required to cover the amount of off-track. However, there were drawbacks such as difficulty in increasing the recording capacity and recording capacity.

[Summary of the invention]

The present invention eliminates the above drawbacks by providing a correction means for correcting the head positioning mechanism of a disk device according to temperature changes, and will be described in detail below using embodiments.

[Embodiments of the invention]

FIG. 5 is a block diagram showing an embodiment of the disk device according to the present invention, and the same parts as in FIG. 2 are designated by the same reference numerals. In the figure, 15 is a temperature detector, which is used to detect the ambient temperature of the herad arm 5 inside the main body case 1 by a temperature sensor 16 installed inside the main body case 1. A temperature correction circuit 17 converts the output from the temperature detector 15 into an offset voltage corresponding to the detected temperature, and outputs it as a correction signal to the actuator 8 via the power amplifier 12. The above-mentioned off-track amount Xa of the data head 7 at high temperature and off-track amount xb at low temperature can be confirmed by actual measurement and can be obtained as data with good reproducibility. Therefore, the temperature correction circuit 17 shown in FIG.
2. Also, in an intermediate temperature range, an offset voltage for off-tracking by an arbitrary value is set so as to be generated.

This can be easily configured by using comparators that generate three types of offset voltages. Next, the operation of the apparatus configured as described above will be explained.

First, to explain the high temperature operation of this device, the 6th
As shown in the figure, since the servo head 6 is positioned at a constant 6- position, the data head 7 at this time
The maximum off-track amount is Xa, but the temperature correction circuit 1
-X a / due to the offset voltage applied from 7
Since the servo head 6 is offset by 2, the data head 4 connected to the actuator 8 is also offset by -Xa/2, and the offset amount is X a -X a
/ 2 = X a / 2. Similarly, during low temperature operation, the amount of off-track is suppressed to X b - X b/2 = X b/2. Therefore, the total amount of off-track at high and low temperatures is 1 Xa/2-Xb/2 l, which is half of the conventional amount.

In the above embodiment, the offset voltage output by the temperature correction circuit 17 is uniformly set to correspond to the temperature inside the main body case 1, but the offset voltage is set for each data head 7 in synchronization with the head switching signal. The voltage may be finely adjusted.

In addition, the method of detecting the temperature inside the main body case 1 is the navel arm 5.
However, the same effect as described above can be obtained even if the temperature of the head arm 5 itself or the temperature of the actuator 8 is detected. Further, the offset voltage may be one that changes continuously in response to temperature changes.

〔Effect of the invention〕

As explained above, the disk device according to the present invention is provided with a correction means for correcting the positioning mechanism according to temperature changes, so reliability against temperature changes is improved, and the off-track margin of the disk is reduced compared to the conventional one. Since it is smaller than the device, it is easy to downsize the device and increase the recording capacity.

[Brief explanation of the drawing]

Fig. 1 is a simplified configuration diagram showing an example of a magnetic disk device, Fig. 2 is a block diagram showing an example of a positioning mechanism of the conventional device, and Figs. FIG. 5 is a block diagram showing an embodiment of the apparatus according to the present invention, and FIG. 6 is a simplified diagram showing the off-track amount of the magnetic head of the apparatus according to the present invention. 3...Magnetic disk, 5...Head arm, 6...
- Servo head, 7... Data head, 8... Actuator, 15... Temperature detector, 17... Temperature correction circuit. Note that the same reference numerals are used for the same or corresponding parts in the figures. Agent Masuo Oiwa (and 2 others) 9- Figure 1 Figure 2 111312 8 6/4 Figure 5 Figure 6

Claims (1)

[Claims] Temperature detection means for detecting the ambient temperature of the arm in a disk device comprising disks stacked at predetermined intervals and a head positioning mechanism that drives an arm having a head to position the head on a data track of the disk. and a temperature correction means for outputting a temperature correction signal to the head positioning mechanism based on the output from the temperature detection means.