JPH056603Y2 - - 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 feeding of the head carriage, which is transferred along the magnetic disk, was carried out by a motor, etc., and was carried out by a piezoelectric actuator with fine servo feeding control.
Publication No. 36010, Special Publication No. 10384 of 1986, Special Publication No. 10384, Special Publication No. 10384
Some of these are shown in 1960 Publication No. 10385 and 1986 Special Publication No. 10386. 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 to ensure that the magnetic head is at the desired track position, and to prevent fluctuations such as head touch. It is an object of the present invention to provide a magnetic disk head drive device that is free from danger.

[Summary of the idea]

The above object of this invention is to provide a head carriage which carries a magnetic head and is 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. The screw shaft is rotated by the screw shaft, the screw engaging portion of the head carriage engages with the screw shaft, and the head cartridge is rotated in one direction in order to bring the screw engaging portion into contact with the threaded portion of the screw shaft. a piezoelectric actuator using a laminated piezoelectric element installed at one end of the screw shaft and capable of moving the screw shaft in its axial direction by changing dimensions in response to a servo signal; a pressure spring installed at the other end of the screw shaft to bias the screw shaft toward the piezoelectric actuator; The magnetic disk head drive device is capable of fine-feeding, and at least during playback, coarse feed of the head carriage is performed by the motor, and fine-feeding of the head carriage is performed by driving the piezoelectric actuator based on a servo signal. can be achieved.

[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, and 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 pin (screw engaging portion) 11 engages with the wall surface of the threaded portion 5a of the screw shaft 5, and the rotation of the screw shaft 5 moves the magnetic disk (not shown) along the radial direction. It is becoming more and more common.

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

Further, as shown in FIGS. 2a and 2b, one end 5b of the screw shaft 5 is movable in the thrust direction into a bearing holder 20 that is fitted and held in a hole in the support plate 2. Thrust bearing 2
1, and this thrust bearing 2
Inside the bearing holder 20 on the outside of the bearing holder 1, a laminated piezoelectric ceramic (actuator) 22 whose dimensions change in the thrust direction by applying a voltage is provided.

On the other hand, the other end 5c of the screw shaft 5 is held by a thrust bearing 24 movable in the thrust direction in a bearing holder 23 that is fitted and held inside the hole of the support plate 1. A pressure spring 25 is provided between the bearing holder 23 and the thrust bearing 24 to bias the thrust bearing 24 in the thrust direction.

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).

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

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. The discriminated vertical synchronization signal Vsync is sent to the peak hold circuit 34 as a reset signal every rotation of the disk.

On the other hand, the detection signal 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, so that both the signals V1 and V2 are
When V2≧V1, turn on analog switch 37,
It is designed to turn off when V2<V1. 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, when the minute magnetic head 10 passes the proper position and V2<V1, the analog switch 3
7 is turned off to stop the servo drive of the magnetic head 10.

Therefore, the drive of the magnetic head 10 is stopped when the signal V2 has slightly passed its peak, in other words, when 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 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 22 is connected to the connection point of these three, 37, 38, and 39 via a buffer amplifier 40. The other end of the piezoelectric ceramic 22 is grounded.

The switch 38 is turned OFF by the final driving pulse from the driving 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, at this point the magnetic head 10 is 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 2
2 is also driven and begins to be displaced in one direction (in the direction of increasing displacement in this embodiment), thereby displacing the magnetic head 10 as will be described later.

Thereafter, the piezoelectric ceramic 22 is driven (the amount of displacement is increased) until the signals V1 and V2 become V2<V1, and at the point when V2<V1, the analog switch 37 is turned off and the piezoelectric ceramic 22
is maintained in this state.

When 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 22 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 for the servo drive as described above, that is, the servo is performed by always displacing the piezoelectric ceramic 22 in one direction, is that the influence of hysteresis of the reciprocating displacement of the piezoelectric ceramic 22 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 22 when the servo operation starts, the laminated piezoelectric ceramic 22
Since its dimensions change from the state shown in Figure a and the thrust bearing 21 in the bearing holder 20 is moved in the direction of pushing out, the screw shaft 5, together with the thrust bearing 24 in contact with the other end 5c, is attached to the pressing spring 25. Move in the thrust direction against the force.

This movement of the screw shaft 5 moves the head carriage 9 and the magnetic head 10 above it.
is positioned in the height direction, so when the screw shaft 5 moves to the state shown by the broken line as shown in FIG. The pin 11, which is pressed against one wall of the threaded portion 5a, is restricted from moving in the height direction as described above, so it moves in the direction against the biasing force of the springs 12, 12. As a result, the head carriage 9 and the magnetic head 10 above it are moved in the direction of the desired position on the desired track, that is, in the direction of the arrow in FIG.
The magnetic head 10 is moved in a direction in which the difference of 12.5 μm becomes smaller, and the magnetic head 10 is moved by a small amount until the aforementioned signals V1 and V2 become 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.

In addition, in the video floppy disk drive device for an electronic still camera 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.
2 is also advantageous in that it is small in size and consumes little power.

Further, in the embodiment described above, a laminated piezoelectric ceramic was used as a member for moving the screw shaft 5 against the urging force of the pressing spring 25, but it is of course possible to use an electric actuator other than the laminated piezoelectric ceramic. Furthermore, it is also possible to install the pressure spring 25 on the piezoelectric ceramic 22 side, and it goes without saying that all various modifications within the scope of the spirit of the present invention are included in the scope of the registered claims. .

[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 displaces the screw shaft in the direction of movement of the head carriage, thereby moving the head carriage and the magnetic head above it by a small amount, making it possible to perform head touch, etc. The magnetic head can be reliably stopped at a desired position without being moved, and the reproduction characteristics can be improved with a relatively simple configuration, so it has great practical value.

[Brief explanation of the drawing]

The drawings show an embodiment of this invention, and FIG. 1 is a plan view of the head carriage feeding mechanism, and FIGS. 2a and b.
3 is a diagram showing both ends of the screw shaft, 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. Schematic diagram shown,
FIG. 5 is a timing chart based on FIG. 4. 1, 2... Support plate, 3, 4... Guide shaft, 5... Screw shaft, 5a... Threaded portion, 5b, 5c... End portion, 6... Stepping motor, 7, 8... Gear , 9... Head carriage, 10... Magnetic head, 11... Pin (screw engaging part), 12... Spring, 20, 23... Bearing holder, 21, 24... Thrust bearing, 22
...Laminated piezoelectric ceramic, 25...Press spring, 3
0...Preamplifier, 31...FM demodulation/synchronization signal separation circuit, 32...detection circuit, 33...integrator circuit, 34...peak hold circuit, 35...comparison circuit, 36...constant current source, 37... ...Analog switch, 38...Switch, 39...Capacitor.

Claims (1)

[Scope of Claim for Utility Model Registration] A head carriage equipped 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 that is rotated by the screw shaft; a screw engaging portion of the head carriage that engages with the screw shaft; and a screw engaging portion of the head carriage that is rotated in one direction in order to bring the screw engaging portion into contact with a threaded portion of the screw shaft. a piezoelectric actuator using a laminated piezoelectric element installed at one end of the screw shaft and capable of moving the screw shaft in its axial direction by changing dimensions in response to a servo signal; a pressure spring installed at the other end of the screw shaft to bias the screw shaft in the direction of the piezoelectric actuator, and by moving the screw shaft in the axial direction, the head carriage is moved in its transport direction A head of a magnetic disk, characterized in that, at least during playback, coarse feeding of the head carriage is performed by the motor, and minute feeding of the head carriage is performed by driving the piezoelectric actuator based on a servo signal. Drive device.