JPS59198569A - Track position correcting device - Google Patents

Abstract

PURPOSE:To suppress minimizingly the position shift of a head due to thermal expansion by providing an expanding/contracting mechanism having an electrostriction element or a magnetostriction element to at least one of a head support member and a torque transmission mechanism, applying an electric signal to the said element and correcting the head position. CONSTITUTION:The expanding/contracting mechanism having the electrostriction element or the magnetostriction element to at least one of notches 8, 9 formed on the way of the actuator arm 3 and the head arm 5 is provided. In the figure, 11 is a U-shaped elastic body whose both ends are inserted to the notch 8 and the electrostriction elements 10, 10' are clipped between them. When an electric field is applied to the electrostriction elements 10, 10', a strain is produced, and this strain is expanded and delivered to the actuator arm 3. The correcting control of track shift is as follows: Assuming that the head position at high/low temperatures is shifted by delta, when a signal is written and read while providing in advance a displacement larger than the delta by the expanding/contracting mechanism, the track shift of the head is corrected by applying a voltage to the expanding/contracting mechanism so that the signal output of the average value of its envelope is maximized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a track position correction device used in magnetic disk devices such as floppy disk devices, or optical disk devices that optically record and reproduce video and audio. .

Conventional Structure and Problems Therein FIG. 1 shows a conventional head position 2 page setting device for a magnetic disk device. In Fig. 1, ■ is a stepping motor, 2 is a capstan attached to the output shaft of the stepping motor 1, 3 is an actuator arm whose one end is fixed to the shaft 4, and the other end of this actuator arm 3. An arcuate surface is formed. The actuator arm 3 and capstan 2 are connected by a steel belt (not shown). That is, the band-shaped steel belt is wound around the outer peripheral surface of the capster 2, and both ends are fixed to the ends of the arcuate surface of the actuator arm 3.

56-i is a head arm having one end fixed to the shaft 4; a head spring 6 is fixed to the other end of the head arm 5; a head 7 is supported on the head spring 6;

In FIG. 1, when the stepping motor 1 operates,
The capstan 2 rotates, and the rotation of the capstan 2 is transmitted to the actuator arm 3 via the steel belt, and the actuator arm 3 rotates. When the Akcheny farm 3 rotates, the shaft 4 also rotates, the head arm 5 fixed to the shaft 4 also rotates, and the position of the head 7 changes.

The head positioning accuracy of this type of magnetic disk drive is several microns.
In the conventional example shown in FIG. 1, the length of each component changes due to thermal expansion, which has the disadvantage that the head position changes due to temperature changes. In other words, when writing to a magnetic medium at a low temperature and reading a signal from the magnetic medium at a high temperature, the length of each component changes, so the position of the head differs during writing and reading, and the signal S /
This resulted in poor N and errors. This phenomenon is especially noticeable when the recording density of a magnetic medium increases in the radial direction.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks, and aims to minimize head position deviation due to thermal expansion.

Structure of the Invention In order to achieve the above object, the present invention provides a support member,
At least one of the rotational force transmission mechanisms is provided with an expansion mechanism having an electrostrictive element or a magnetostrictive element, and the steering position is corrected by applying an electric signal to the electrostrictive element or the magnetostrictive element.

DESCRIPTION OF THE EMBODIMENT FIG. 2 shows an embodiment of the present invention. In FIG. 2, the same parts as in FIG. 1 are given the same numbers. 8
．． 9 is a notch formed in the middle of the actuator arm 3 and head arm 5, respectively, and this notch 8.9
An expansion/contraction mechanism having an electrostrictive element or a magnetostrictive element is provided in the expansion/contraction mechanism.

FIG. 3 shows an embodiment in which the notch 8 of the actuator arm 3 is provided with an electrostrictive element 10, 10'.

In Fig. 3, 11 is a U whose both ends are inserted into the notch 8.
An electrostrictive element 10, 10' is held between the U-shaped elastic bodies 11.

12 is an electrode provided between the electrostrictive elements 10 and 10'. When an electric field is applied to the electrostrictive element 10 , 10 ′, strain occurs, and this strain is magnified and transmitted to the actuator arm 3 . 13.13' is a lead wire.

FIG. 4 shows another embodiment of the invention. In FIG. 4, 14 is a magnetostrictive element whose end is fixed to the edge of the opening of the notch 8, 15 is a coil wound around the magnetostrictive element 14, and 1
6.16' is a lead wire, and when a current flows through the coil 15 through the lead wire 16.16', a magnetic field is applied to the magnetostrictive element 14, causing distortion, and this distortion is applied to the actuator arm 3.
can be conveyed to.

In Figures 3 and 4, the electrostrictive elements 10 and 10 are shown, respectively.
', a telescoping mechanism consisting of the magnetostrictive element 14 is provided in the notch 8 of the actuator arm 3, but a similar telescoping mechanism may also be provided in the notch 9 of the head arm 5. It may be provided on one side.

FIG. 5 shows the operation of an embodiment in which the head arm 5 is provided with a telescoping mechanism. In the state shown by the solid line in FIG.
When a current is passed through the lead wire 4, distortion occurs, one side of the head arm 5 stretches, the rad arm 5 bends as shown by the dashed line, and the head position changes. Note that the electrostrictive elements J0, 10' and the magnetostrictive element 14 expand and contract in only one direction υ due to voltage or magnetic field, and the expansion and contraction direction of the expansion and contraction mechanism in the above embodiments is only the expansion direction or only the contraction direction. .

Next, a method of controlling the correction of the torso angle deviation in the embodiment using the above-mentioned expansion and contraction mechanism will be explained.

Figure 6 shows the relationship between the misalignment between the write head position and the read head position and the head output.If the head misalignment is large, the head output will decrease, and if the misalignment occurs by approximately the track width, the head output will decrease. The head output becomes almost zero. Normally, when a signal is written on a magnetic medium at a certain temperature and read out at a different temperature, thermal expansion of the head drive mechanism causes 9) curvature deviation and a decrease in head output. If the track deviation is very large, the head output will be greatly reduced and errors will occur. In particular, when the track density is increased, the head output is significantly reduced even if a slight track deviation occurs.

As shown in Fig. 7, if the head position deviates by δ at high and low temperatures, when writing or reading signals while applying a displacement larger than δ in advance with the expansion mechanism, the signal output or its envelope will be By applying voltage to the expansion/contraction mechanism so that the average value is maximized, head tracking deviation can be corrected.

Figure 7 shows that at low temperatures the signal is written with a shift of a (a) δ), at high temperature it is written with a shift of b (b) a - δ), and when reading, the head is moved from bottom to top in Figure 7. This shows that it is best to keep the output at maximum while moving closer.

Conventionally, the trunk density has been increased by using a linear actuator and controlling the track with a servo track, but according to this embodiment, by using a stepping motor and a simple telescoping mechanism, the density of the track can be increased. It is something that can be achieved.

Effects of the Invention The present invention has the above-mentioned configuration, and the present invention has the advantage that track deviation can be corrected with a simple configuration and that track density can be increased.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a conventional track positioning device, FIG. 2 is a perspective view of a track position correction device according to an embodiment of the present invention, FIG. 3 is a top view of the main parts of the device, and FIG. 4 is a top view of essential parts of another embodiment of the present invention, FIG. 5 is a top view of another embodiment, FIG. 6 is a diagram showing the relationship between head positional deviation and head output, and FIG. FIG. 3 is a diagram showing the head position at high temperature. 1...Stepping motor, 2-...Capstan, 3
・Actuator arm, 4...axis, 5...head arm, 6 head spring, 7...head, 8.9...notch, 10.10'...electrostrictive element, 11...elastic body,
12 Electrode, 13.13'... Lead wire, 14... Magnetostrictive element, 15... Coil, 16.16'... Lead wire. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Crane Figure θ Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A rotational drive mechanism, a rotational force transmission mechanism that transmits the rotational force generated by the rotational drive mechanism to the head support member to change the head position, and an electrostrictive element or a magnetostrictive element. 1. A track position correction device comprising: an expansion/contraction mechanism provided on at least one side, and corrects a heel position by expansion/contraction operations of the electrostrictive element or the magnetostrictive element.