JPS59215008A - Optical magnetic disc device - Google Patents

Abstract

PURPOSE:To obtain an optical magnetic disc device which makes the best of the optical modulating system and the magnetic field modulating system in one device by recording many high speed data by the optical modulation system and recording a few data such as management information or the like by the magnetic field modulation system. CONSTITUTION:The image of an optical beam irradiated from a semiconductor laser 1 is formed on an optomagnetic recording medium 6 through a collimator lens 3, a mirror 4 and an objective lens 5. In recording information at high speed, the optical modulation system is adopted, a recording signal is given through a signal line L1, a semiconductor laser 1 is driven in response to the recording signal by means of a laser driver 2 so as to modulate the optical beam. Then the temperature of a part on which the optical beam is irradiated rises, the magnetization is inverted and the signal is recorded. In recording data at comparatively low speed, the mode is changed over into the magnetic field modulating system, optical beams of a prescribed level are generated continuously from the laser 1 by means of the laser driver 2 and a current changed in forward/reverse direction in response to the recording signal is given to a coil 10 via a coil driver 11 from a signal line L2, then an alternating magnetic field is generated and the information is recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a magneto-optical disk device that records and reproduces information signals using magneto-optic effects.

In conventional magneto-optical disk drives, information signals are generally recorded by applying a magnetic field and a light beam to a magnetic thin film such as Gd'TbFe or Hcd-CO to change the direction of magnetization. When a linearly polarized laser beam is irradiated onto a magnetic thin film and reflected or transmitted, the recording signal is recorded by utilizing the magnetic Kerr effect or Faraday effect, which causes the vibration plane of the linearly polarized light to rotate according to the direction of magnetization. Reading out. The rotation of light reflected from the surface of a medium is called the magnetic Kerr effect, and the rotation of transmitted light is called the Faraday effect.

In particular, magneto-optical disk devices have an extremely large capacity, can be loaded and played back at high speed, and are compatible with VTRs.
It has many advantages, such as the ability to erase and rewrite data just like magnetic disks.

It is expected to be used as a recording device for image information.

As described above, there are conventionally known methods for writing recording signals (data) in magneto-optical disk devices. First, the first recording method is 1. There is a method of recording information by irradiating a disk surface made of a magnetic thin film with a laser beam modulated according to a recording signal. In this case.

Generally, by applying an unmodulated magnetic field to the disk surface simultaneously with laser beam irradiation, the magnetization sensitivity of the disk is increased, making it possible to record with a relatively weak laser beam. However, even without applying such a magnetic field, recording is possible if the laser beam is strong12
Of course. below.

This seventh recording method is called a light modulation method.

The first recording method is to irradiate an unmodulated light beam onto a disk surface made of a thin magnetic film.

At the same time, there is a method of applying a magnetic field modulated according to the recording signal. By making the magnetic field applied at this time so weak that it cannot record with its own magnetic field strength, information can be accurately recorded only in the area irradiated with the light beam. In addition, the magnetic field is 1. It is generated by passing a current corresponding to a recording signal through a coil disposed near the recording section. Hereinafter, this No. 1 recording method will be referred to as a magnetic field modulation method.

Conventional magneto-optical disk devices have used one of the above-mentioned recording methods.

Comparing the above-mentioned recording methods, the optical modulation method is more suitable for extremely high-speed and high-density recording.

In the magnetic field modulation method, it is necessary to apply a high-speed recording signal to the coil, but since the coil has a predetermined inductance, it is difficult to apply a high-speed signal. however.

The optical modulation method has the following drawbacks when changing the recorded data of a portion recorded in one device.

In other words, with the optical modulation method, it is not possible to directly write new data to the previously recorded area.

It is necessary to erase the recorded portion once and then write new data. Therefore, changing data requires one process of erasing and rewriting.

On the other hand, there is an advantage that new data can be directly written to a portion recorded using the magnetic field modulation method without going through an erasing process.

In this way, when using a magneto-optical disk device for large-capacity image data files, etc., it is necessary to perform high-speed, high-density recording and reproducing, so conventional magnetic field modulation methods are inappropriate, and optical It is suitable to use a modulation method. However, when performing such recording and playback, it is important to know what kind of image information is recorded in which area on the disk, or which area on the X disk is currently being used. It is also necessary to record so-called management information, such as information on whether or not the data is being stored, on the same disk using a single magneto-optical disk device.

However, since such management information often needs to be updated, it is necessary to rewrite it from time to time as necessary. There is a problem with inappropriateness.

Purpose: 1. The purpose of the present invention is to eliminate the above-mentioned drawbacks, and to
An object of the present invention is to provide a magneto-optical disk device that takes advantage of the advantages of both methods by recording a large amount of data at high speed using an optical modulation method and recording a small amount of data such as management information using a magnetic field modulation method in one device.

In order to achieve such an object, the present invention comprises: a light beam modulator that modulates a laser beam according to a recording signal; a magnetic field generator that generates a magnetic field at a position irradiated with the light beam; The present invention provides a magneto-optical disk device having a magnetic field modulating means for modulating the magnetic field.

Example The present invention will be described in detail below with reference to one drawing.

FIG. 7 shows an example of the configuration of a magneto-optical disk device of the present invention, in which a semiconductor laser 1.2 that emits a laser beam is a laser driver that drives a semiconductor laser l, and the laser driver is driven by one signal. The laser beam is modulated in response to a recording signal provided through line L/. 3 is a collimator lens that converts the laser beam emitted from the semiconductor laser into a bundle of parallel rays, and 4 is a reflective mirror that changes the optical path of the laser beam.

This is an objective lens that focuses the strs laser beam into a spot.

6 K'S disk-shaped magneto-optical recording medium (magneto-optical disk)
, and its recording surface is Gd=TbFe or I/Cd
C.

A laser beam spot focused by an objective lens S is irradiated with the laser beam spot. This is a drive motor that drives the magneto-optical recording medium 6 at a predetermined rotational speed. The half mirror 19, which is interposed between the reflecting mirror and the collimator lens 3 and splits the reflected light of the laser beam reflected on the magneto-optical recording medium 6, receives the above-mentioned reflected light that has passed through the half mirror t. This focus detection optical system 9 includes, for example, a condenser lens, a wavelength plate (polarizing plate), and a light receiving element (photoelectric conversion element) such as a CCD.

Furthermore, lθ is a magnetic field generation coil that applies a magnetic field to the irradiation position of the light beam on the magneto-optical recording medium core, ii is a coil dryer that drives this magnetic field generation coil 10, and 1 signal 11L:1 is sent to the coil driver //. The magnetic field of the coil 10 is modulated according to the recording signal supplied through the coil 10.

Next, to explain the operation, the light beam emitted from the semiconductor laser I, the collimator lens 3. Through the mirror + and the objective lens 5, a diameter of approximately −
The image is formed into a spot on the order of μm. Magneto-optical recording medium 6
Some of the light reflected by the surface.

The light is guided to the focus detection optical system t by the half mirror g, and an error signal of the distance between the objective lens S and the magneto-optical recording medium 6 is obtained by receiving the light from the optical system 9, and the objective lens 5 is moved in the vertical direction according to this error signal.・ Move to accurately form a spot on the magneto-optical recording medium 6.

Near the objective lens S &C, a magnetic field generating coil IO is provided as shown in the figure, and on the other hand, the magneto-optical recording medium A is rotated by, for example, l.theta.(7r, p, m).Furthermore, a semiconductor Laser/, optical system 3.'l,!,
g, 9, coil /θ, etc. are housed in a housing (not shown), and are movable integrally in the radial direction of the magneto-optical recording medium core as a recording/reproducing head. Recording data can be written to any location in the memory.

With the above configuration, when recording information at a high speed, an optical modulation method is adopted to provide a recording signal through the signal line L/, and the laser driver λ drives the semiconductor laser/ in accordance with the recording signal, thereby producing light. Modulate the beam. At this time, coil 1 OKk'! A constant DC current may be passed from the coil driver l/ to generate a magnetic field in the opposite direction to the direction in which the magneto-optical recording medium 6 is magnetized in advance, and if the light beam is strong, the coil driver l/ is energized. You don't have to.

As a result, the temperature of the portion hit by the light beam locally increases, the magnetization is reversed, and a double signal is recorded.

When erasing the recorded signal on the magneto-optical recording medium 6 recorded in this way, a DC current of the opposite polarity to that described above is applied to the coil driver coil in the same direction as the previously magnetized direction, that is, opposite to the recording pit. The recorded signal is erased by generating a directional magnetic field by the coil IO and simultaneously irradiating a constant light beam. In this way, in order to perform recording using the optical modulation method and rewrite the recorded part (recorded bits) with -f, it is necessary to erase the recorded signal in advance. When recording data (for example, the above-mentioned management information, etc.), the switching means (not shown) switches to the magnetic field modulation method, and the laser driver continuously generates a light beam of a certain level from the laser l.
At the same time, a recording signal is given to the coil driver /l through the signal line L, and a current that changes in the forward and reverse directions with respect to the recording signal is passed from the coil driver l to the coil lθ, thereby producing an alternating magnetic field according to the recording signal. occurs. Due to this.

The direction of magnetization of the portion hit by the light beam is reversed in accordance with the recording signal, and information is recorded. When recording using this magnetic field modulation method, it is possible to record regardless of whether or not there is already recorded data in the recording area, and there is no need to erase the recorded information.

In this way, in this example, one device can both record main information such as one image information at high speed, and rewrite auxiliary information such as management information, which may be performed at low speed, without erasing it. This is very convenient in practice. In actual use, it is preferable to record the data to be recorded at high speed and rewrite the management information at low speed accordingly.

It should be noted that when reading out the recorded information, it can be done by a single information reading means like the conventional one described above, and a reading means is provided independently for each of the two methods mentioned above. There's no need. However, it goes without saying that the demodulation of the modulated signal must be performed in accordance with the modulation method used for each recording method.

Furthermore, it is effective to divide and predetermine areas of the portion to be recorded by one recording method on the recording medium 6 according to each recording method in this example. In this case, it is preferable to allocate the inner central part of the recording medium to the magnetic field modulation method, and the outer vicinity of the recording medium B to the optical modulation method f.

In other words, what are the limits to the recording speed of optical modulation methods?

It is limited by the size of recording pits on the recording medium 6. In other words, it is necessary to ensure that the recording pits formed according to the recording signal are recorded within the range where they are formed independently. Therefore, when the recording medium 6 is rotating at a constant rotational speed, the linear velocity outside the rtX is high, making high-speed recording possible. On the other hand, with the magnetic field modulation method, the coil
The recording speed is limited by the inductance. In other words.

This is because it is difficult to change the current flowing through the coil IO at a high speed due to the inductance of the coil lθ, which limits the recording speed. Therefore, the upper limit of the recording speed remains almost the same whether it is at the inner center of the recording medium or at the outer periphery.

Therefore, by setting the portion to be recorded using the magnetic field modulation method inside the recording medium, more data can be recorded on one recording medium.
Even when changing the rotation speed of the motor 7 depending on the area to be recorded, by setting the recording area in sections as described above, the variable range of the rotation speed of the motor 7 can be made smaller. There are some advantages to doing so.

Effects As explained above, according to the present invention, with one device,
This provides the effect of realizing both high-speed recording of information and recording that allows data to be easily rewritten.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of the configuration of a magneto-optical disk device of the present invention. l...Semiconductor laser. Co...Laser driver. 3... Collimator lens. Da... reflective mirror. j...Objective lens. 6... Magneto-optical recording medium. 7...Motor. g...Half mirror. De Paf Orcus detection optical system. 10...Coil, l/...Coil driver. L/, L, 2...Signal line. Patent applicant Canon Co., Ltd.

Claims (1)

[Scope of Claims] /) A magneto-optical recording medium, a light source that generates a light beam, an optical system that irradiates the light beam emitted from the light source onto the magneto-optical recording medium, and a first a light beam modulating means for modulating the magnetic field according to the recording signal; a magnetic field generating means for generating a magnetic field at the irradiation position of the light beam; a magnetic field modulating means for modulating the magnetic field according to the recording signal; A magneto-optical disk device comprising: a signal supply switching means for switching and supplying a signal to either the light beam modulation means or the magnetic field modulation means. f) In the apparatus according to claim 1 [. When recording the recording signal on the magneto-optical recording medium, the front light distribution beam is kept constant at the center of rotation of the magneto-optical recording medium, the magnetic field is modulated according to the recording signal, and the magnetic field is modulated in accordance with the recording signal. A magneto-optical disk device comprising: control means for controlling the magnetic field to be constant in the rotational periphery sr, and for controlling the light beam to be modulated in accordance with the recording signal.