JPH01286182A - Disk device - Google Patents

Abstract

PURPOSE:To offset noises, to reduce the number of coils moved integrally with a head carriage to one, and to accelerate the travel of the head carriage by reducing the weight of a movable part by taking the sum of signals from two coils wound in a reverse direction with each other in the speed detector of a disk device. CONSTITUTION:A mobile element 16 having a magnet 14 is provided in the yoke 12 of a voice coil motor 10 as the driving source of the disk device, and the head carriage 18 is mounted on the mobile element 16 integrally, then, the mobile element 16 and the carriage 18 are moved integrally. A head arm 20 is mounted on the carriage 18, and a recording and reproducing head 26 guided by a pair of guide bars 22 is provided on the arm 20. An encoder 28 is arranged nearly in the center of the carriage 18 in parallel with the bars 22, and the amount of travel of a head 26 is detected corresponding to the travel of the carriage 18. Also, the speed detector 64 is provided at a side opposite to a motor 10 that is the travel center of the head 26, and the coil 242a of a detecting unit 200 is wound in the reverse direction of that of the coil 142a of a detecting unit 100, and the noises are offset by the coils 142a and 242a.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a disk device, in particular, a bed carriage on which a head is mounted is coupled to a mover of a voice coil motor, and the head is moved to a predetermined position on the disk. The present invention relates to a disk device that can be used.

[Prior Art] Currently, 1 mega type disks are the mainstream in disk devices such as magnetic disk devices, which are used in electronic equipment such as computers to record and reproduce information, but 2 mega type, 10 mega type or other types are also used. High-density disks are beginning to be used. In order to perform ultra-high density recording and reproduction of 5 to 10 Mega type, a motor that can be controlled with ultra-precision is required, and linear pulse motors are beginning to be adopted in place of conventional lead screw type DC motors. Manufacturing this linear pulse motor requires considerable precision, which increases the overall cost.
Voice coil motors are used as a drive source for heads because they are inexpensive and fast.

When a voice coil motor (hereinafter abbreviated as VCM) is used as a drive source for the head, the amount of movement of the carriage to which the head is attached and is moved by the VCM is expressed in a linear manner in order to control the relative position between the disk and the head. It is detected using an encoder.

A speed detector is also provided to monitor the movement of the head carriage moved by the VCM, and feeds back a speed signal to the servo circuit to improve control performance.

This speed detector is a voice coil composed of, for example, a coil attached to a moving element, an iron yoke disposed passing through this coil, and a magnet integrated with this iron yoke. Speed is detected by measuring the voltage induced in the coil due to relative movement with the coil.

Recently, the above-mentioned speed detection coil is installed on the opposite side of the head movement center line from the head carriage driving VCM, so that it is not affected by the sagging magnetic flux from the speed detection coil or the head carriage driving VCM. Such consideration has been taken.

[Problems to be Solved by the Invention] In order to further improve detection accuracy in the speed detection coil configured as described above, two speed detection coils are provided, each coil is wound in reverse to each other, and the magnet is By arranging the polarities opposite to each other and taking the sum of the outputs of both coils, a configuration has been adopted that can increase the detection output, cancel out the effects of the head carriage drive VCM and external magnetic fields, and reduce noise. There is.

However, with such a configuration, the weight of the movable part, that is, the head carriage increases, and the power consumption also increases accordingly, which poses a problem in that it is difficult to increase the speed and reduce the power consumption of the head carriage.

The present invention has been made to eliminate the above-mentioned drawbacks.
It is an object of the present invention to provide a disk device that can increase the speed of a head carriage and operate with low power consumption.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a first coil that moves together with the head carriage, which is used in a speed detector that detects the moving speed of the head carriage of a disk device. The second coil is stationary with respect to the head carriage and is wound in the opposite direction to the first coil.

[Function] With the above configuration, noise is canceled out by summing the signals from the two reversely wound coils of the speed detector, and only one speed detection coil is moved together with the head carriage. Therefore, the weight of the movable part can be reduced.

[Example] Hereinafter, the present invention will be described in detail based on the example shown in the drawings.

The disk device shown in FIGS. 1 and 2 has a voice coil motor (VCM) 10 as a drive source, and a VCMIO
A mover 16 having a magnet 14 and a coil 16a is provided within the yoke 12. A head carriage 18 is integrally attached to the mover 16, and when a current is passed through the coil 16a, the mover 16 is moved by interaction with the magnetic field of the magnet 14, and the head carriage 18 is moved together with it. be done. A helad arm 20 is integrally attached to the head carriage 18. The head arm 20 passes through the carriage 18 in the direction of carriage movement, and is guided by a pair of guide bars 22, 22 fixed to the device to seek toward and away from the center of the disk 24, thereby moving the head 26. It can be moved to a predetermined track position.

The head arm 20 is provided with a pair of recording/reproducing heads 26, and as is well known, information is recorded on both sides of the disk, read out, or erased by the heads 26.

Further, an encoder 28 is provided parallel to the guide bar 22, and this encoder 28 is connected to the head carriage 1.
It is inserted into a guiding notch 18a formed in the holder 8 and fixed to the device via an elastic member. encoder 2
8 is formed with slits 28a at equal intervals, and a light receiving element receives light emitted from a light emitting element (not shown) of a photointerrupter disposed in the head carriage 18 through the slit, and the light is emitted from the slit after passing through the slit. By counting the number, it is possible to detect the amount of movement of the mover 16 and the head carriage 18 associated therewith, that is, the amount of movement of the head 26.

In the case of this embodiment, the encoder 28 is disposed approximately at the center of the head carriage 18, near the movement center line M of the head 26 along the head movement direction. A photo interrupter 30 is attached to the head carriage 18 so as to straddle the encoder 28. The photointerrupter 30 is provided with, for example, two sets of light emitting elements and light receiving elements, and detects the slit of the encoder that has passed as the head carriage 18 moves, thereby changing the amount of movement of the head carriage, that is, the head 26. The amount of movement is detected.

Furthermore, a speed detector 64 is provided on the side opposite to the voice coil motor 10 (on the right side in FIGS. 1 and 2) with respect to the center line M of movement of the head 26.

This speed detector 64 includes a detection unit 100 that moves together with the head carriage 18 and a fixed detection unit 200.
It is composed of. The detection unit 100 includes a moving element 142 that is integrally fixed to the head carriage 18, a coil 142a wound around the moving element, and a coil 142a that is arranged through the moving element and partially fixed to the device. It is composed of an iron yoke 144 and a magnet 146 provided on the iron yoke 144.

On the other hand, the detection unit 200 has a structure similar to that of the detection unit 10.
0, but it is fixed to the disk device, and the coil 242a of the detection unit 200 is connected to the coil 142a by winding it in the opposite direction to the coil 142a described above.

Next, control of the disk device having the above configuration will be explained using the circuit diagram shown in FIG.

The destination of the movement of the head 26 is determined by receiving a step command from a host system (not shown), and the movement command is sent from the signal line a to the adder circuit 54 and the power amplifier 50.
VCMIO is driven through. When VCMIO is driven, the movable element 16 and the bed carriage 18 fixed thereto are moved along the guide bar 22 due to the interaction between the current flowing through the coil 16a and the magnet 14.

When the head carriage 18 is moved, the action of the photo interrupter 30 provided integrally with the head carriage and the encoder 28 fixed to the device causes
Information regarding the movement of the carriage is output from the encoder 28 as two signals φA and φB whose phases are shifted by 90 degrees, for example.

The output signal of the encoder 28 is first sent to the differential amplifier 52 in the subsequent stage.
Rough positioning of the head position is performed using the intersection point of both signal waveforms, that is, the point of zero difference, as a reference, and the output of the differential amplifier 52 is inputted as a coarse position signal to the adder circuit 54 at the subsequent stage.

The pseudo sine wave output signal of the encoder 28 is shaped into a square wave by comparators 56 and 58 at the subsequent stage, and then input to a track counter 60 where counting is performed in the forward or reverse direction. It is input to the microcomputer 62 as a current position signal C indicating where on the track it is.

Also, as the rad carriage 18 moves, the mover 1
42 is moved, an induced voltage is generated in the coil 142a due to the interaction between the coil 142a wound around the mover 142 and the magnetic field of the magnet 146 provided on the iron yoke 144.

At this time, another fixed detection unit 200 is provided, and this coil 242a is connected to the movable detection unit 1.
Since the coil 242a is wound in the opposite direction to that of the coil 142a, when there is magnetic noise, the noise detected by the coil 242a has a waveform opposite to that detected by the coil 142a, as shown in FIG. Therefore, by summing both signals, the noise is canceled out. On the other hand, since a voltage proportional to the speed is generated in the coil 142a, the moving speed can be determined by measuring this voltage. Also, the coil 2 of the detection unit 200
The magnet corresponding to 42a can be omitted and configured as a simple yoke.

The speed signal related to the movement of the bed carriage 18 taken out in this way is input to the subsequent amplifier 66.
Further, the signal d inputted to the phase compensation circuit 67 and subjected to phase compensation is inputted to the addition circuit 54 to improve control performance. Further, the signal f from the amplifier 66 is input to the microcomputer 62 for speed control.

Further, a signal related to the moving speed of the bed carriage detected by the speed detector 64 and amplified by the amplifier 66 is inputted to the differentiating circuit 68, converted into an acceleration signal, and compared with a predetermined value in the subsequent comparator 70. When an acceleration exceeding the reference value of this comparator Tough 0 occurs, the output signal e from the comparator is applied to the microcomputer 62 to inhibit writing, for example, and prevent external data from being transmitted. Data destruction due to fI\l is prevented.

Furthermore, the servo information of the track recorded on the floppy disk 24 is detected by the head 26 itself, amplified by the amplifier 72 at the subsequent stage, and inputted to the position error detection circuit f4, where the track following position error signal g is sent to the microcomputer 62.
is input.

In this way, the rough position signal d directly input to the adder circuit 54, the phase-compensated speed signal d, and the microcomputer 62
Accurate movement control of the head carriage 18 and the head 26 that moves together with it is performed according to the current position signal C9 input to the speed signal f, the shock prevention signal e during writing due to speed fluctuations, and the track following servo signal g. , for example, the count value of the target position in the microcomputer 62,
As the encoder 28 moves, the track counter 60
When the count values obtained by
QJ, and when the differential amplifier 52 is "0", that is, the head stops at the track position corresponding to the predetermined slit position. After this, eight lines are entered for tracking control.

What is shown in FIG. 5 is a second embodiment of the present invention, and the overall structure of the disk device is almost the same as that of the first embodiment shown in FIGS. 1 and 2. , the coils of the two detection units 100.300 of the speed detector are arranged in the same magnetic circuit.

That is, the iron yoke 144 and the magnet 146 are used in common, one coil 142b is fixedly arranged, and the other coil 142a is provided so as to be movable integrally with the head carriage 18.

In this case as well, the coils 142a and 142b are wound in opposite directions.

Control of the disk device in this embodiment is almost the same as in the previous embodiment, but since the iron yoke 144 and magnet 146 are common, the space, number of parts, and assembly man-hours can be reduced accordingly. In addition, since the magnetic paths are the same, the noise is induced in the same way, and common noise can be more effectively improved.

The one shown in FIG. 6 is a conventional disk device,
The head carriage 18 is integrally provided with two coils 42a, 42a of VCM wound in opposite directions.

In such a configuration, the weight of the two coils 42a, 42a is applied to the head carriage 18, which prevents the head carriage from increasing speed and reducing power consumption, and furthermore, the mass becomes unbalanced with respect to the center line of movement of the head. Although there are various problems such as a stronger mass inertia force acting on the speed detector side, the device of the present invention does not have such problems.

[Effects of the Invention] As is clear from the above description, according to the present invention, the coil of the speed detector for detecting the speed of the head carriage of a disk device is moved integrally with the head carriage; It consists of a second coil that stands still and is wound in the opposite direction to the first coil, so by summing the output signals of both coils, external noise is canceled out and common mode noise is also reduced. .

In addition, since only one coil is moved together with the head carriage, the weight of the movable part can be reduced, the head carriage can be moved faster, and power consumption can be reduced accordingly.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams showing a first embodiment of the present invention, and FIG. 5 is a perspective view showing a second embodiment of the present invention.
FIG. 6 is a perspective view showing a conventional disk device. 10...Voice coil motor (VCM) 18...Head carriage

Claims (1)

[Claims] 1) In a disk device in which a head carriage carrying a head is coupled to a mover of a voice coil motor and the head is moved to a predetermined position on the disk, voltage induced in the coil as the head carriage moves is A speed detector is provided for detecting the moving speed of the head carriage, and the coils include a first coil that moves together with the head carriage, and a second coil that is stationary with respect to the head carriage and is wound in the opposite direction to the first coil. A disk device comprising a coil. 2) The disk device according to claim 1, wherein the first and second coils are respectively disposed horizontally or vertically with respect to the moving direction of the head carriage.