JPH0373449A - Magnetic field modulation type magneto-optical disk device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of collision at the time of loading/ejecting a disk cartridge by providing the disk device with a mechanism capable of vertically moving a magnetic head at the time of loading the cartridge to the device. CONSTITUTION:Since the magnetic head 5 for modulating a magnetic field supplies a sufficiently large magnetic field to a recording film, the head 5 floats the surface of a magneto-optical disk 3 with a gap >= 10mu. In order to attain the replaceability of the disk 3, the disk 3 stored in a cartridge 17 is loaded/ ejected to/from the device. The disk device is provided with the mechanism for preventing the accurence of collision by moving an optical head 2 to the outermost periphery and vertically moving the magnetic head 5 at the time of loading/ejecting the disk 3 into/from the device. Consequently, the magnetic head 5 can be prevented from colliding with the disk cartridge 17 at the time of loading/ejecting the cartridge 17.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an overwritable magnetic field modulation type magneto-optical disk device having a magnetic head. The present invention relates to a magnetic field modulation type magneto-optical disk device having a mechanism for lowering the magnetic head to prevent collision between the magnetic head and the disk cartridge.

[Conventional technology]

In conventional rewritable optical modulation type magneto-optical disk drives, a wj of 2 to 3 mm above the disk faces the optical head in order to apply a bias magnetic field when recording/erasing information.
Electromagnets or permanent magnets are arranged with gaps, but since these electromagnets are fixed on the cartridge loader, the cartridge can be taken in and out without hitting the disk cartridge at all times when loading the disk cartridge.

However, in an overridable magnetic field modulation type magneto-optical disk device, the magnetic head for magnetic field modulation flies above the disk with a gap of only 10 μm or less opposite the optical head during normal use.

When the disk is stopped, it comes into contact with the disk, so if the disk cartridge is inserted or removed in this state, there is a problem in that the magnetic head will be destroyed. A magnetic field modulation type magneto-optical disk device is described in, for example, Japanese Patent Laid-Open No. 63-217548.

[Problem to be solved by the invention]

In a magnetic field modulation type magneto-optical disk device in which a magnetic head is disposed opposite an optical head, a new problem has arisen: ε, in which the magnetic head is moved vertically to prevent collisions when a disk cartridge is inserted or removed. An object of the present invention is to provide a magnetic field modulation type magneto-optical disk device having the above-mentioned vertical movement mechanism for the magnetic head.

Means for Solving the CRS Problem] In order to achieve the second object, the present invention utilizes a temperature-dependent shape changeable element such as a shape memory alloy in the holding portion of the magnetic head as the vertical movement mechanism. do.

[Effect]

Shape memory alloy is used for the holding part including the magnetic head spring,
A Peltier element is used as the temperature control element. The shape memory alloy has two memory states, one with the magnetic head up and one with the magnetic head down, and is heated with a Peltier element so that it is in the up state when loading the cartridge and in the down state in the steady state when recording and reproducing information. do. By controlling the temperature using the Peltier element in this way, it is possible to easily realize vertical movement of the magnetic head.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1st
The figure shows the configuration of a magnetic field modulation type magneto-optical disk device according to the present invention. A spindle motor 4 for rotating a magneto-optical disk 3 at a constant speed is mounted on a linear actuator (not shown). A magnetic head 5 is arranged in the optical head 2 facing a magneto-optical disk 3. In the optical head 2, the light emitted from the semiconductor laser 6, which is a light source for recording and reproduction, is reflected.
The light is condensed by the i-lens 7, becomes parallel light, passes through the polarizing prism 8 and the galvano mirror 9, and enters the aperture lens 10, forming a spot of about 1 micron on the magneto-optical disk 3. The magneto-optical disk 3 has a recording film of a rare earth-transition metal formed by vapor deposition or sputtering on a glass substrate of about 1 mm, and a layer on the recording film to protect the recording film from contact with the magnetic head 5. A protective film with a thickness of about 10 microns is formed on the surface.

When recording information, the semiconductor laser 6 is oscillated with a high output power of about 10 mW on the magneto-optical disk 3 to raise the recording film to around the Curie temperature, leaving it in a state where there is almost no magnetization. The information signal sent from the signal processing circuit 11 is guided to the magnetic head 5 through the magnetic head opening circuit 12, and when the direction of the current is switched in accordance with the information signal, upward and downward magnetic domains are recorded on the recording film. will be done. On the other hand, information is reproduced using the Kerr effect, that is, when the magneto-optical disk 5
The light reflected from the magneto-optical disk 5 contains a Kerr-rotated component in which the polarization plane is slightly rotated depending on the direction of magnetization, such as upward or downward magnetization, with respect to the normal 11A polarization plane of the light incident on the magneto-optical disk 5. Aperture lens 10 again. After passing through the galvanometer mirror 9, the optical path is separated by the polarizing prism 8, and the optical detection XJ! The light enters the I device 13. The photodetector 13 uses a servo optical system (not shown) such as an automatic focus detection system and a track deviation detection system, and an information signal optical system (not shown) that detects address information and magneto-optical signals. A signal or an information signal is detected and guided to the security processing circuit 11. As described above, information is recorded and reproduced.

In the above-described magnetic field modulation recording, the magnetic head 5 that performs magnetic field modulation supplies a sufficient magnetic field to the recording film.
It is necessary to float above the magneto-optical disk 3 with a gap of 10 microns or less.

Furthermore, in order to realize the interchangeability of optical disks, which is a feature of optical disk devices, disks are stored in cartridges and taken in and out of the device. Therefore, if an optical disk is inserted into or removed from the apparatus with the magnetic head 5 lowered, a problem arises in that the magnetic heads are destroyed by collision with each other. To prevent this,
A mechanism is provided for moving the optical head 2 to the outermost periphery and moving the magnetic head 5 up and down to prevent collisions when the optical disk 3 is taken in and out of the apparatus.

In FIG. 2, a first embodiment will be described in which a shape memory alloy is used in the holding portion of the magnetic head to realize a mechanism for moving the magnetic head up and down. Nigaml shape memory alloy is used for an arm 52 that supports a gimbal spring 51 having a magnetic head 5 at its tip. Shape memory alloys are made of Ti-N3 alloys and have the characteristic of remembering their shape with respect to temperature. Figure 6 shows an example of the amount of displacement with respect to temperature of a shape memory alloy (Bulletin of the Japan Institute of Metals Vol. 24, No. 1 (1985), p.
3).

In this case, the maximum displacement occurs when the temperature reaches 50°C or higher after heating, and conversely, it returns to its original shape when it cools down to 30°C. In this example, a two-way shape memory alloy is used, as shown in FIG. 2, in which the magnetic head 5 is in a lowered state when heated, and the magnetic head 5 is raised in a cooled state. Of course, two-way shape memory alloys with opposite properties may also be used. A Peltier element 53 is installed in the optical head 2 for heating and cooling the shape memory alloy, and it can accurately heat and cool the shape memory alloy regardless of the internal temperature of the device.
A temperature sensor 54 is installed for cooling. The Veritier drive amount g55 is driven by the magnetic head vertical movement command from the control circuit 14 to heat the Peltier element 53.
Along with cooling, the detection signal from the temperature sensor 54 is moved around the Peltier residence! 355 to control the applied temperature of the shape memory alloy to a constant value.

With reference to FIG. 3, a second embodiment will be described in which a shape memory alloy is used in the holding portion of the magnetic head to realize a moving mechanism for moving the magnetic head up and down. In the first embodiment, a plate-shaped shape memory alloy is used, but in the second embodiment, a coil-shaped shape memory alloy is used. A gimbal 51 having a magnetic head 5 at its tip
is attached to a gimbal support rod 56, and a bias coil 58 made of a normal spring material is attached to support the gimbal and to move it up and down. A bias coil 58 and a coiled shape memory combination coil 59 disposed in the helad arm 5 are connected for two-way operation, and a Peltier element 53 disposed in contact with the shape memory alloy coil 59. As explained in FIG. 2, the magnetic head can be moved in the vertical direction by heating and cooling. In this case, at low temperatures, the shape memory alloy coil 59 moves upward against the force of the bias coil 58, which causes the magnetic head 5 to move downward, and when heated above the transformation temperature, the bias coil 58 is struck. As described above, the magnetic head 5 can be moved vertically as desired by controlling the temperature of the shape memory alloy.

The above sequence flowchart will be explained with reference to the overall configuration of FIG. 1, which shows the sequence flowchart when loading/unloading a disk cartridge in FIGS. 4 and 5. First, when the device is powered on, the control circuit 1
The rear actuator (not shown) is activated by commands from 4.
The optical head 2 is positioned at the outermost periphery by driving the optical head 2 (FIG. 4(a)). An outguard detector 15 (for example, a transmission type photodetector) is placed at the outermost periphery of the optical head 2. The optical head 2 is stopped and fixed at this position. Furthermore, whether or not the magnetic head 5 is in the upwardly moved position is detected using a magnetic head position detection detector 16 (e.g., a reflective photodetector) disposed below a gimbal spring 51 to which the magnetic head 5 is attached. Check the output (4th @ (b)). If the magnetic head remains lowered, the control circuit 14 causes the Peltier element drive circuit 5 to
The magnetic head 5 is moved upward by operating the Peltier element 53 through the magnetic head 5 and heating or cooling it. The same effect can be obtained even if the order of moving the optical head toward the outer periphery and moving the magnetic head upward is reversed. This is the initial operation, and the disk cartridge can be loaded.

Next, the disk cartridge is loaded.The cartridge loader (not shown) for loading the cartridge 17 and moving it up and down remains moved upward, and in this state, the cartridge 17 is loaded from the right side in the drawing. , When the cartridge is inserted to the dotted line position, the cartridge N sensor 18 (for example,
The mechanical switch) detects the loading of the cartridge (
No. 4 (C)). Then, the cartridge loader moves downward and transfers the cartridge 17 to the spindle motor/LL.
(Fig. 4(d)). Whether or not the cartridge 17 has been properly set is determined by the cartridge SET sensor 19 (for example, a mechanical switch) (FIG. 4(e)). After the cartridge 17 is set correctly,
The magnetic head 5 moves upward by operating the Peltier element 53 and heating or cooling it (FIG. 4(f)).
), whether the magnetic head 5 is in the normally lowered state is determined by the output of the magnetic head position detection detector 1G placed below the gimbal spring 51 (FIG. 4(g)), as described above. ), the position where the magnetic head contacts on the magneto-optical disk 3 is determined by the contact start/stop (
(CSS) Considering the operation, an area other than the outermost recording area of the magneto-optical disk 3 is best. In addition, this C8S region is a protective film containing a filler such as alumina for the purpose of removing dust adhering to the magnetic head 5. After the magnetic head 5 is lowered normally, the control circuit 14 is
The spindle motor 4 is rotated by the command (Fig. 4 (h)).
, is the spindle motor 4 correct as determined from the time interval of rotation pulses from the spindle motor? : [When the rotation is reached (
In FIG. 4(i)), the linear actuator is activated to the inner circumference by a command from the control circuit 14, and the optical head 2 is positioned and fixed at the innermost circumference (No. 41''i](j)). Whether it is positioned at the innermost circumference is determined based on the output of the in-guard detector 20 (for example, a transmission type photodetector) placed at the innermost circumference of the optical head 2 (FIG. 4(k)). ,
After that, the semiconductor laser 6 that is the light source is turned on (Fig. 4 (1)), and the autofocus (A, F) servo is turned on (Fig. 4 (m)
)), track following (TR) servo ON (Fig. 4 (n)
)) starts signal reproduction, reads the address information pre-recorded in the form of irregularities on the magneto-optical disk 5, and successfully recognizes the TD (Fig. 4 (0)).
, the device enters the READY state in which information can be recorded and reproduced.

Next, the operation when ejecting the cartridge 17 will be explained using FIG. 5. When the eject switch (EJECTSW) 21 for ejecting the cartridge 17 is pressed, the TR servo is first turned off (Fig. 5(a)).
, the AF servo turns OFF (FIG. 5(b)), and the semiconductor laser 6 turns OFF (FIG. 5(e)).Then, the optical head 2 is activated by the linear actuator according to a command from the control circuit 14 in order to eject the cartridge. is actively moved to the outer periphery to position and fix the optical head 2 at the outermost periphery (No. 5@(d)).

As described above, whether the optical head 2 is positioned at the outermost circumference is determined based on the output of the outguard detection 115. The optical head 2 is positioned at the outermost circumference, and the magnetic head
After being positioned in the 8S area, the spindle motor 4 is stopped by a command from the control circuit 14 (FIG. 5(e)).The spindle motor 4 is stopped from the interval I\lff when the rotation pulse from the spindle motor 4 is received. Judgment (Figure 5 (
f)) After the spindle motor 4 has stopped, the control circuit 14 drives the Peltier element 5 through the Peltier element drive circuit 55.
3 to move the magnetic head 5 upward by heating or cooling it (FIG. 5(g)). Whether or not the magnetic head 5 has moved upward can be determined by the magnetic head position detector 16 disposed below the gimbal spring as described above.
(Fig. 5 (h)). After the magnetic head 5 moves upward, the cartridge loader is rotated to lift the cartridge 17 upward and eject the cartridge 17 to the right in the drawing (Fig. 5 (h)). Figure (i)), Cartridge 1
It is determined whether or not the disk cartridge 7 has been exhausted by the output of the cartridge N sensor 18 attached to the left side of the cartridge loader. This state is also a state in which the disk cartridge can be locked.

〔Effect of the invention〕

As explained above, in a magnetic field modulation type magneto-optical disk device, the present invention has a shape memory mechanism that moves the magnetic head up and down so that the magnetic head placed opposite to the optical head does not collide when inserting and removing a disk cartridge. This is realized using an alloy and a Peltier element as a temperature control element. By doing so, the magnetic head can operate stably without colliding when the disk cartridge is inserted or removed.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of a first embodiment of a vertical movement mechanism using a shape memory alloy according to the present invention, and FIG. 3 is a diagram showing a shape memory alloy according to the present invention. An explanatory diagram of the second embodiment of the vertical movement mechanism using
FIG. 5 is a sequence flowchart when discharging a disk cartridge according to the present invention, and FIG. 6 is a diagram showing the characteristics of the shape memory alloy. Explanation of symbols 2... Optical head, 3... Magneto-optical disk, 4...
Spindle motor, 5...Magnetic head, 11...Signal processing circuit, 12...Magnetic head active circuit, 14...
Control circuit, 15... Outguard detector, 16...
Detection 1i for magnetic head position detection, 17...Cartridge, 18...Cartridge IN sensor, 19...Cartridge SET sensor, 20...In guard detector, 21...Inject switch, 51...・Gimbal spring, 52... Arm, 53... Peltier element,
54... Temperature sensor, 55... Peltier drive circuit,
56...Gimbal support rod. 57...Head arm, 58...Bias m1-1
'/L/, 59...Shape memory alloy coil. Figure 1 fj+42 Figure m6 Figure Figure Figure

Claims (1)

[Claims] 1. An overwritable magnetic field modulation type magneto-optical disk device having a magnetic head and an optical head, which has a mechanism capable of moving the magnetic field up and down when a disk cartridge is loaded into the device. A magnetic field modulation magneto-optical disk device characterized by the following. 2. The magnetic field modulation type magneto-optical disk device according to claim 1, wherein a shape memory alloy is used for the holding portion of the magnetic head as the mechanism capable of moving the magnetic head up and down. 3. The magnetic field modulation type magneto-optical disk device according to claim 2, wherein a Peltier element is used as the temperature applying element to the holding portion of the magnetic head.