JPH0413792Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention relates to a magnetic disk head drive device, and in particular, to a magnetic disk head drive device that can improve the positioning accuracy of the magnetic head in a 2-inch magnetic disk used in an electronic still camera. This invention relates to a disk head drive device.

[Prior art and its problems]

For hard disks, optical disks, etc.
In general, tracking servo technology is used to perform tracking of the detection head, and recently this technology is also being adopted in magnetic disks with high TPI. However, in most of the above cases, a voice coil type actuator capable of fine feeding is used, but since voice coil type actuators are relatively expensive, small magnetic disk drives are required to reduce the price. It is difficult to apply to devices.

On the other hand, in consideration of the above points, a method was developed in which the main feed of the head carriage transferred along the magnetic disk was performed by a motor, etc., and the fine servo feed control was performed by a piezoelectric actuator. Some of these are disclosed in Japanese Patent Publication No. 36010, Japanese Patent Publication No. 10384 of 1988, Japanese Patent Publication No. 10385 of 1988, and Japanese Patent Publication No. 10386 of 1988. The devices shown in these documents are aimed at lowering the price while performing tracking servo, but all of these earlier applications are designed to move the head assembly relative to the head carriage.
There is a problem in that as the two move relative to each other, there is a concern that the so-called head touch may fluctuate or deteriorate. In other words, the magnetic head is generally fixed in position with precision adjustment to the head carriage, and if the two are moved relative to each other, there is a concern that the magnetic head will tilt and the azimuth angle will fluctuate. be. Furthermore, since a relatively high voltage of several hundred volts is applied to the piezoelectric actuator in the vicinity of the head, there is a concern that the electric field may have an adverse effect.

[Purpose of invention]

Therefore, this invention makes it possible to fine-tune the stop position of the head carriage at least during playback using a tracking servo using a piezoelectric actuator, thereby ensuring that the magnetic head is at the desired track position, and at the same time eliminating the risk of fluctuations in head touch, etc. An object of the present invention is to provide a magnetic disk head drive device that is free from errors.

[Summary of the idea]

The above-mentioned objects of this invention include: a head carriage loaded with a magnetic head and transported along the radial direction of a magnetic disk; a guide shaft for guiding the head carriage; and a motor installed substantially parallel to the guide shaft. a screw shaft to be rotated, a screw engaging portion of the head carriage having an engaging pin provided on the head carriage to engage with the screw shaft, and a screw engaging pin of the screw engaging portion. a spring that urges the head carriage in one direction to bring it into contact with the wall surface of the threaded portion of the shaft;
an electric actuator disposed between the head carriage and the engagement pin to move the engagement pin a predetermined distance with respect to the head carriage, and the operation of the electric actuator causes the head carriage to be slightly moved in the direction of movement thereof; This is generally achieved by a magnetic disk head drive device in which, at least during playback, coarse feed of the head carriage is performed by the motor, and minute feed of the head carriage is performed by driving the electric actuator based on a servo signal. be done.

[Example of idea]

Embodiments of this invention shown in the drawings will be described below.

In FIG. 1, 1 and 2 are support plates provided in parallel at a predetermined interval, 3 and 4 are the support plates 1,
a guide shaft installed parallel to each other between the two;
A screw shaft 5 is rotatably supported between the support plates 1 and 2, and the rotation of the stepping motor 6 is transmitted through gears 7 and 8.

Reference numeral 9 denotes a head carriage, on the surface of which is fixed a magnetic head 10 that is accurately positioned and adjusted, and is guided and guided by the guide shafts 3 and 4.
At the same time, the engagement pin 11 of the screw engagement portion is engaged with the threaded portion 5a of the screw shaft 5.
The magnetic disk 5 engages with the wall surface of the magnetic disk 5, and is transported along the radial direction of a magnetic disk (not shown) by the rotation of the screw shaft 5.

Incidentally, reference numerals 12 and 12 are springs for pressing the engagement pin 11 of the head carriage 9 against one of the walls of the threaded portion 5a.

Further, FIGS. 2a, b, and c show a portion of the head carriage 9, on which the magnetic head 10 is fixed as described above.

A screw engaging part SC that engages with the screw shaft 5 is provided at the lower part of the head carriage 9. A laminated piezoelectric ceramic 20 whose dimension in the height direction changes by applying a voltage is vertically disposed on the lower surface of the head carriage 9, and a pin holder 21 is fixed to the lower surface of this laminated piezoelectric ceramic 20. An engagement pin 11 that engages with the threaded portion 5a of the screw shaft 5 is located in the notch 22 on the lower surface of the pin holder 21, and the rear end of the engagement pin 11 is located at both ends of the engagement pin 11. The spring plate 24 is pressed and held in the notch 22 by a spring plate 24 which is fixed with a screw 23.

Therefore, first, by moving the head carriage 9 in the vertical direction in FIG.
When recording on a magnetic disk (not shown) by, for example, the stepping motor 6
By inputting a drive signal of 8 pulses times the number of tracks to be recorded from a control circuit (not shown), the head carriage 9 and the magnetic head 10 above it move at a track pitch of 100 μm to perform recording (writing).

When reproducing (reading) the contents of each recorded track, a drive signal of (number of tracks x 8 pulses) - 1 pulse is input from the control circuit to the stepping motor 6.

By inputting this number of pulses, the head carriage 9 is moved via the stepping motor 6, and the magnetic head 10 is moved to the desired track position by 12.5 μm.
(This value is a theoretical value and actually varies)
It is located in the front, and the tracking servo is activated after this.

FIG. 4 shows a control circuit for this tracking servo. In the figure, reference numeral 10 denotes the magnetic head, and the reproduced output of the magnetic head 10 is supplied to an FM demodulation/synchronization signal separation circuit 31 and a detection circuit 32 via a preamplifier 30.

The output of the FM demodulation/synchronization signal separation circuit 31 is sent to a known video reproduction circuit at a later stage (not shown) to reproduce a desired image, and the FM demodulation/synchronization signal separation circuit 31 The discriminated vertical synchronizing signal V _syoc is sent to the peak hold circuit 34 as a reset signal every rotation of the disk.

On the other hand, the detection output of the detection circuit 32 is input to the peak hold circuit 34 via the integration circuit 33, and the signal V2 is supplied to one input terminal of the comparison circuit 35. Further, the peak hold circuit 34 supplies the (peak) signal V1 held every rotation of the disk to the other input terminal of the comparison circuit 35.

The output of the comparison circuit 35 controls an analog switch 37 whose one end is connected to a constant current source 36, and the output of the comparison circuit 35 controls the analog switch 37, which has one end connected to a constant current source 36, and outputs both signals V1 and V2.
When V2<V1, analog switch 37 is
It is designed to be turned off. That is, as will be described later, after the magnetic head 10 reaches the proper position on the target track and the signal V1 shows the highest value, the very small amount of the magnetic head 10 passes the proper position and V2<V.
When it becomes 1, turn off analog switch 37.
Then, the servo drive of the magnetic head 10 is stopped.

Therefore, the drive of the magnetic head 10 is stopped when the signal V2 has slightly passed its peak, in other words, the magnetic head 10 has slightly passed the true proper value on the target track. According to the standard of Tsupii disk, the off-track is ±14μm.
and the magnetic head 10 has a track width of 60μ.
Since the magnetic head 10 is stopped on the target track on the target track at most a few micrometers away from the true proper value on the track, in practice (apparently) the magnetic head 10 is stopped at the proper position. I can do it.

A switch 38 and a capacitor 39 are connected in parallel between the other end of the analog switch 37 and the ground, and the piezoelectric ceramic 20 is connected to the connection point between these three switches 37, 38, and 39 via a buffer amplifier 40. The other end of the piezoelectric ceramic 20 is grounded.

The switch 38 is turned OFF by the final drive pulse from the drive circuit of the stepping motor 6 [the above-mentioned {(number of tracks x 8) - 1}th pulse], and is turned off based on a new track search command. It is designed to be turned on by the first drive pulse to the stepping motor 6.

When the switch 38 is turned off at the above timing, the magnetic head 10 is at this point approximately 12.5 μm before the calculated appropriate position on the target track.
Naturally, the relationship between the signals V1 and V2 is V2>V1, so the analog switch 37 is ON and the switch 38 is OFF, so the capacitor 39 starts charging and the piezoelectric ceramic 20 is also driven. , the magnetic head 10 is displaced in one direction (in the embodiment, in the direction of increasing displacement), and the magnetic head 10 is displaced as described later.

Then, after this, the signals V1 and V2 become V2<V1
The piezoelectric ceramic 20 is driven (the amount of displacement is increased) until V2<V1, the analog switch 37 is turned off, and the piezoelectric ceramic 20 is maintained in this state.

When the image reproduction of the desired track is completed and a new track search command is input, the first drive pulse to the stepping motor 6 based on this command activates the switch 38 as described above.
When turned on, the capacitor 39 is discharged and the piezoelectric ceramic 20 is returned to a reference displacement state (for example, displacement 0).For the above-mentioned operation, please refer to the timing chart shown in FIG.

The reason why the servo drive as described above, that is, the servo is performed by always displacing the piezoelectric ceramic 20 in one direction, is that the influence of hysteresis of the reciprocating displacement of the piezoelectric ceramic 20 can be ignored, and the control circuit has an extremely simple configuration. This is because of this.

When the tracking servo operates as described above, the mechanism operates as follows. That is, since a voltage is applied to the laminated piezoelectric ceramic 20 when the servo operation starts, the laminated piezoelectric ceramic 20
The dimensions change in the vertical direction shown in Figures b and c, that is, in a direction substantially perpendicular to the moving direction of the head carriage 9 and the magnetic head 10 above it, and the engaging pin 11 is moved downward in the figure.

When the engagement pin 11 moves to the state shown by the broken line against the urging force of the springs 12, 12 as shown in FIG. Because of the positioning, the head carriage 9 and the magnetic head 10 above it move in the axial direction of the screw shaft 5 by the amount shown in FIG. As a result, the magnetic head 10 moves in the direction of the proper position on the desired track (that is, in the direction of the arrow in FIG. 1, in which the difference of 12.5 μm becomes smaller), and the above-mentioned signal V1, The magnetic head 10 is moved by a small amount until V2 becomes V2<V1.

In this way, the magnetic head 10 is servo-fed without changing its relative position with respect to the head carriage 9, so the touch between the magnetic head 10 and the disk does not change and a good head touch that has been adjusted as desired is maintained. Regeneration will take place.

6a and 6b show another embodiment of this invention, in which one side of the head carriage 9 on the moving direction side has the magnetic head 10 fixed to its upper part. A pin holder 21 is provided on the side surface via a laminated piezoelectric ceramic 20, and an engagement pin 11 that engages with the threaded portion 5a of the screw shaft 5 is provided in a notch 22 on the lower surface of this pin holder 21. The rear end of both ends of the engagement pin 11 is connected to the pin holder 21.
The spring plate 24 is pressed and held in the notch 22 by a spring plate 24 which is fixed with a screw 23.

Even in the case of this structure, the head carriage 9 and the magnetic head 10 above it are slightly moved when a voltage is applied to the laminated piezoelectric ceramic 20 by the servo tracking circuit, as described above. In the case of the embodiment, the threaded portion 5a of the screw shaft 5 and the engagement pin 11
The head carriage 9 moves in the direction of the proper position on the desired track, that is, in the direction of the arrow in FIG. Signal V
1. Magnetic head 10 until V2 becomes V2<V1
A small amount of feeding will be performed.

In addition, in the video floppy disk drive device for electronic still cameras in this embodiment, the head carriage 9 is extremely small and lightweight, and the screw shaft 5 is also lightweight, so the piezoelectric ceramic 2 is used.
0 is also convenient because it is small and consumes little power.

Furthermore, although laminated piezoelectric ceramic is used in the above embodiment, it is of course possible to use an electric actuator other than laminated piezoelectric ceramic.

[Effect of idea]

By configuring this idea as described above,
During playback, after stopping the head carriage slightly before the desired track position, the tracking servo moves the engagement pin that engages with the screw shaft relative to the head carriage, thereby moving the head carriage and the magnetic head above it by a small amount. Therefore, the magnetic head can be reliably stopped at a desired position without changing the head touch, etc., and good reproduction characteristics can be obtained with a relatively simple configuration, which has great practical value.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention; FIG. 1 is a plan view of the head carriage feeding mechanism, FIG. 2 a is a plan view of the main part, FIG. 2 b is a front view, and FIG. Fig. 3 is a schematic explanatory diagram showing the state of engagement between the threaded portion of the screw shaft and the pin, and Fig. 4 is an embodiment of the control circuit for the tracking servo. 5 is a timing chart based on FIG. 4, FIG. 6 a and b show other embodiments, and FIG. 6 a is a plan view.
FIG. 6b is a view taken along line B--B in FIG. 6a. DESCRIPTION OF SYMBOLS 1, 2... Support plate, 3, 4... Guide shaft, 5... Screw shaft, 5a... Threaded portion, 6... Stepping motor, 7, 8... Gear, 9... Head carriage, 10... ...magnetic head, 11...engaging pin, 12...spring, 20...
Laminated piezoelectric ceramic, 21...Pin holder, 2
2...notch, 23...screw, 24...spring plate,
30... Preamplifier, 31... FM demodulation/synchronization signal separation circuit, 32... Detection circuit, 33... Integrating circuit, 34... Peak hold circuit, 35... Comparison circuit, 36... Constant current source, 37... ...Analog switch, 38...Switch, 39...Capacitor,
SC...screw engagement part.

Claims (1)

[Claims for Utility Model Registration] (1) A head carriage loaded with a magnetic head and transported along the radial direction of a magnetic disk, a guide shaft for guiding the head carriage, and a head carriage installed substantially parallel to the guide shaft. a screw shaft rotated by a motor; a screw engaging portion of the head carriage having an engaging pin provided on the head carriage and engaging with the screw shaft;
a spring that biases the head carriage in one direction in order to bring the engagement pin of the screw engagement portion into contact with the wall surface of the threaded portion of the screw shaft; an electric actuator that moves the engagement pin a predetermined distance with respect to the head carriage, the operation of the electric actuator allows the head carriage to be slightly fed in the transport direction, and the motor is used to coarsely feed the head carriage at least during playback. . A head drive device for a magnetic disk, characterized in that minute feeding of the head carriage is performed by driving the electric actuator based on a servo signal. (2) The head drive device for a magnetic disk according to claim 1, wherein the electric actuator is displaceable in a direction substantially perpendicular to the axis of the screw shaft when the electric actuator is operated. (3) The head drive device for a magnetic disk according to claim 1, wherein the electric actuator is displaceable in the direction of movement of the head carriage when activated.