JPH03295048A - Magneto-optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To enable the overwrite by modulating the direction of a magnetic field to be generated by a magnetic head having an optical height detector for detecting the height from a magneto-optical disk and a height control mechanism for keeping the height constant. CONSTITUTION:The magneto-optical disk 1 is formed with a single layer of a magneto-optical recording film on its upper surface. An optical head 2 is equipped with a laser beam source, a signal detecting system for reproducing a data out of the reflected light and a servo optical system for tracking and focusing. A frame 3 is combined with the magnetic head 4, a leaf spring 5, a piezoelectric element 6 and the optical height detector 7, disposed on the side opposite to the optical head 2, and is accessed in the vertical direction to a track by a linear motor, etc. Thus, by functioning of the optical height detector 7 and the piezoelectric element 6, the distance between the magnetic head 4 and the optical disk 1 can be lengthened as apart from each other by approximately 0.1-0.2mm irrespective of wobbling of the disk, and hence the overwrite in a magnetic field modulation system can be carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording/reproducing device that allows overwriting.

[Background Art] In recent years, digital audio discs, read-only optical discs called optical video discs, and write-once optical discs used for electronic files, etc. have been put into practical use and are rapidly becoming popular in homes and offices. Furthermore, rewritable optical discs have recently been put into practical use and have begun to be used as external memory for computers and memory for multimedia. This uses the magneto-optical effect, and details can be found at ro pl.
It is described in usEJ magazine, November 1988 issue, pages 82-89.

The disk used in this device is housed in a cartridge and is removable from the device. The disc is two discs glued together, each side 297MB (512B/5e
In case of ctor, track pitch 1.6 μm) both sides 59
It has a storage capacity of 4MB. Data transfer rate 7.4
Mbps, average seek time 95m5. The device dimensions are 146W x 82.8H x 203. 2D (mm)
, cartridge dimensions are 135X153X11 (mm
). The height of the device is 82.8 mm and is a so-called "full hide" device.

[Problems to be Solved by the Invention] However, the above-mentioned conventional technology has the following problems.

The first problem is that it takes time to rewrite data because overwriting is not possible. This is because data is erased in the first rotation and new data is recorded in the second rotation, so two rotations are always required to rewrite data. Floppy disk drive (FDD) Hard disk drive (HDD)
Since it is possible to overwrite data, data can be rewritten in just one rotation. As a result, when I actually use it, I feel that it is slower when rewriting data compared to an HDD.

The second problem is that it cannot be built into a small personal computer. In recent years, small personal computers called laptop computers have been put into practical use. This display is made of a foldable liquid crystal or plasma display, and can be carried with one hand, and is expected to become widely popular in the future. In the conventional example mentioned above,
It is impossible to install it on a laptop computer.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems and provide a magneto-optical disk drive device that allows overwriting and can be built into a small personal computer.

[Means for Solving the Problems] The magneto-optical recording and reproducing device of the present invention irradiates a focused laser spot onto a single-plate magneto-optical disk having a magneto-optical recording film, and directs an optical head across the magneto-optical disk. A magnetic head with an optical height detector that detects the height from the magneto-optical disk and a height control mechanism that keeps the height constant is placed at a position facing the magneto-optical disk, and the direction of the magnetic field generated by the magnetic head is It is characterized by overwriting by modulating it.

Further, the optical height detector is composed of one light source and two photodetectors placed at different distances from the light source.

[Example] An example of the present invention is shown in FIG. Reference numeral 1 denotes a magneto-optical disk, in which a single-layer magneto-optical recording film is formed on one side (corresponding to the top surface in the figure) of a disk substrate. Of course, the magneto-optical recording film is sandwiched with a protective film to prevent oxidation, and is further coated with a resin. Reference numeral 2 denotes an optical head, which includes a laser light source, a signal detection optical system for reproducing data from reflected light, and a servo optical system for tracking and force shifting. 3 is a frame, each part (4
, 5, 6, 7). The whole connected by the frame 3 is accessed in the track vertical direction by a linear motor or stepper motor. 4
is a magnetic head. 5 supports the magnetic head 4 with a leaf spring.

A piezoelectric element 6 is bonded onto the plate spring 5.

By applying an electric field to the electrodes on both sides of the piezoelectric element, the leaf spring warps vertically, and the height of the magnetic head 4 relative to the magneto-optical disk 1 changes. This height is always kept constant in combination with the function of the height detector 7 (see FIG. 2) constituted by the light emitting diode 8 and photodiodes A and B (9, 10).

FIG. 2 is a structural diagram of the light emitting diode 8 and its surroundings as viewed from the spindle motor shaft. 9.10 are photodiodes AS B, which are placed at different distances from the light emitting diode 8. θ1 is the radiation angle from the light emitting diode of the light ray that leaves the light emitting diode 8 and enters the photodiode A, θ2 is the radiation angle of the light ray that enters the photodiode, and θ1 and 02 have different values. d indicates the distance between the magneto-optical disk 1 and the light emitting diode 8 (or the magnetic helad 4).

FIG. 3 is a radiation angle dependence diagram of the light output of a light emitting diode. As the radiation angle (θ) increases, the optical output decreases.

Further, the dependence of the optical output on the radiation angle is small at locations where the radiation angle is large and at locations where the radiation angle is small.

FIGS. 4(a), (b), and (c) are diagrams explaining the principle of the height detector. (a), (b), and (C) are cases where the magneto-optical disk 1 is too close to the light emitting diode 8, when it is at the target height, and when it is too far away. Radiation angle θ1, θ
2 becomes smaller in the order of (a), (b), and (C). When the radiation angle is large and small, photodiode A,
Since the pressure of H does not differ significantly, dividing the output of photodiode A by the output of photodiode B (using the divider circuit 11) results in a value close to 1. However, when the radiation angle is an intermediate value, the divided value becomes small. That is, the output of the divider circuit takes a minimum value at a specific height, as shown in FIG. Therefore, if the level L is determined using a comparator and the piezoelectric element 6 is driven so that the output ratio is always below the level L, the height from the disk can be kept constant with the error Δ. Normally, a magneto-optical disk has a surface runout of about ±100 μm, but this can be sufficiently tracked by the present invention.

As the magnetic helad 4, MnZn ferrite, NiZn
A spiral thin film coil type formed by photolithography on a high magnetic permeability material such as ferrite, or a spiral thin film coil type formed by forming the high magnetic permeability material into an axially symmetrical mountain shape and winding a conductor wire inside it. A bulkhead type is used, which has a coil made by embedding it in it. The magnetic field modulation frequency is several 100 k
Hz to several MHz. The height between the surface of the magneto-optical disk 1 and the magnetic head 4 is maintained at 0.1 to 0.2 mm.

Therefore, since the disc is not affected by dirt and dust on the disc surface, it is possible to attach and detach the disc.

There are mainly two specific methods for overwriting. One method is to switch the magnetic field while continuously irradiating the medium with laser power that can heat the medium to near the Curie point. Others are
Laser power is irradiated in pulses, and after a certain delay time (
This is a method of switching the magnetic field (the time it takes for the medium to heat up) and the magnetic field.

FIG. 6 is a structural diagram of a magneto-optical disk used in the present invention. Reference numeral 12 denotes a transparent substrate, on the surface of which guide grooves and pre-pits are formed. 13, the protective film 14 is a magneto-optical recording film;
15 is a reflective film, and 16 is a resin protective film. As the magneto-optical recording film, a rare earth transition metal-based film is often used, and a film having a composition that combines Gd, Td, Dy, Nd, etc. with Fe, Co, etc. is used. The magnetic field during recording is 1
000e to 2000e is sufficient.

The magneto-optical disk has a diameter of 86 mm and a thickness of 1. 2-1,
It is 4mm. This is housed in a 90x94x6mm cartridge. Compared to conventional cartridges,
Since the size is significantly reduced, it is also possible to reduce the size of the drive device. The dimensions of the drive device are 101.6Wx146Dx4
It's 1H.

It is also possible to install it in a buttotsubu personal computer.

[Effects of the Invention] As described above, according to the present invention, the distance between the magnetic head and the magneto-optical disk can be maintained at zero regardless of the surface runout of the disk due to the functions of the optical height detector and the piezoelectric element. 1~0
．． Since they can be separated by about 2 mm, overwriting using the magnetic field modulation method becomes possible. As a result, the speed at which data is rewritten becomes faster, making it possible to realize a high-speed external storage device.

Furthermore, by using a single disk with a diameter of 86 mm and a cartridge with a thickness of 6 mm, the dimensions of the drive device can be significantly reduced, making it possible to install it in a laptop computer.

The present invention is not limited to the above embodiments, and can be modified in many ways. For example, if it is not necessary to install it in a laptop computer, it is of course possible to apply the present invention to a disk having a diameter of 86 mm or more. Or, patent application 1986-3
An electromagnetic drive mechanism such as that shown in No. 16712 may be used to move the magnetic head up and down.

[Brief explanation of drawings]

FIG. 1 is a basic configuration diagram of an embodiment of the present invention. FIG. 2 is a structural diagram of the optical height detector of the present invention. FIG. 3 is a radiation angle dependence diagram of the light output of a light emitting diode. FIG. 4(a) is a diagram explaining the principle of the optical height detector when the magneto-optical disk is too close to the light emitting diode. FIG. 4(b) is a diagram illustrating the principle of the optical height detector when the magneto-optical disk is at the target height with respect to the light emitting diode. FIG. 4(C) is a diagram explaining the principle of the optical height detector when the magneto-optical disk is too far from the light emitting diode. FIG. 5 is a characteristic diagram showing the relationship between the distance to the disk and the division circuit. FIG. 6 is a structural diagram of a magneto-optical disk used in the present invention. 1... Magneto-optical disk 2... Optical head 3... Frame 4... Magnetic head 5... Leaf spring 6... Piezoelectric element 7... Height detector 8... Light emitting diode 9...Photodiode A 9'-...Light ray exits the light emitting diode and enters the photodiode A10...Photodiode B 10'...Leaves the light emitting diode and enters the photodiode B
Light rays incident on 11...Division circuit 12...Transparent substrate 13...Protective film 14...Magneto-optical recording film 15...Reflective film 16...Resin protective film or more

Claims (2)

[Claims] (1) A focused laser spot is irradiated onto a single-plate magneto-optical disk having a magneto-optical recording film, and the height from the magneto-optical disk is detected at a position facing the optical head across the magneto-optical disk. A magnetic head having an optical height detector and a height control mechanism that keeps the height constant is arranged, and overwriting is performed by modulating the direction of the magnetic field generated by the magnetic head. Magneto-optical recording and reproducing device. (2) The optical height detector according to claim 1, wherein the optical height detector is constituted by one light source and two photodetectors placed at different distances from the light source. Magnetic recording and reproducing device.