JP2821122B2 - Magneto-optical disk device and magneto-optical recording method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disc apparatus, and more particularly, to an overwritable magneto-optical disc capable of simultaneously performing overwriting and error checking immediately after recording with one laser light source. Related to the device. [Prior Art] Conventionally, as an overwritable magneto-optical disc apparatus, IEE Transaction on Magnetics, MAG 20, Volume 5, Volume 1
013 (1984) (IEEE Iransaction on Magnetics MAG)
-20 Volume 5 p.1013 (1983)), a method using two optical spots,
As described in JP-A-107121, JP-A-59-215008, and JP-B-60-48806, a method of modulating a magnetic field applied to a recording film in accordance with information to be recorded can be used. The present invention particularly relates to a magneto-optical disk device based on the latter magnetic field modulation method. [Problems to be Solved by the Invention] In order to improve the data processing speed of a magneto-optical disk, a function of processing an error check within one rotation of the disk is required in addition to an overwrite function. In the conventional overwritable magneto-optical disk device, no consideration has been given to the error checking function. DRAW (Direct Rea) that performs an error check immediately after recording
To realize the (d. After Write) function, a method is known in which two light spots are arranged on the same information track, one of which is a recording spot and the other is a reproduction spot.
However, conventionally, recording was performed by modulating a laser beam in accordance with recording information. Therefore, when the above-mentioned two light spots were formed by one laser light source, the reproduction spot for error checking was also intensity-modulated during recording. Will be done. For this reason, overwriting and DR with one laser light source
Realizing AW at the same time was considered difficult. [Means for Solving the Problems] An object of the present invention is to solve the above problems and to provide a magneto-optical disk device capable of simultaneously realizing overwriting and DRAW with one laser light source. The above object is to divide the light from the laser light source into a plurality of light beams by a diffraction grating and to focus on a disc to form a plurality of light spots. Alternatively, this can be achieved by using a magnetic field modulation recording method in which an intensity-modulated magnetic field is applied to a recording film. [Operation] In the case of the magnetic field modulation recording method, it is not necessary to modulate the laser beam in accordance with the recording information, so that the light intensity of the error check reproduction spot is constant even during recording. The fact that information erasing / recording / error checking on a magneto-optical disk can be processed within one rotation of the disk with only one laser light source can be realized only by using a light beam splitting by a diffraction grating and a magnetic field modulation recording system. This is a new effect. Since there is one laser light source, a small and inexpensive device can be realized. Furthermore, in order to arrange a plurality of light spots on the same information track, only the rotation adjustment of the diffraction grating is required, and there is an effect that the adjustment of the apparatus becomes extremely easy. Embodiment An embodiment of the present invention will be described below with reference to FIG. Referring to FIG. 1, reference numeral 1 denotes a magneto-optical disk which is a rotating record carrier. For example, light emitted from a light source composed of the semiconductor laser 2 is converted by a collimating lens 3 into a parallel light beam, and further by a beam shaping optical system 4 into a light beam having a circular intensity distribution. Next, the light is split into a plurality of light beams (three light beams of the 0th order and ± 1st order in this embodiment) by the diffraction grating 5 and is incident on the aperture lens 7 via the beam splitter 6. Lens 7
The light beam focused on the disk substrate 103 enters the disk 1 from the disk substrate 103 side, and forms a small spot having a diameter of about 1 μm on the recording film 101. The aperture lens 7 is arranged so that the focus is always on the recording film following the vertical vibration of the disk 1, and the spot is always on the desired track following the eccentricity of the information recording track on the disk. 8 attached. The reflected light from the disc 1 is reflected by a beam splitter 6 through a stop lens 7 and guided to a signal detection optical system 9 for detecting a magneto-optical signal and a light spot control signal such as a focus shift or a track shift. FIG. 2 shows the light spots on the recording film and the intensity of each light spot during recording / reproduction. Here, a case where three light spots are formed by the diffraction grating will be described. Supotsuto SP ₂ The central zero order, SP ₁ and SP ₃ is ± 1-order diffracted light. If the direction of rotation of the disk is taken as shown in the figure, the light spot S
It passes through in the order of P ₃ , SP ₂ , and SP ₁ . Therefore, SP
₃ is the preceding playback spot, SP ₂ is the recording / erasing spot,
SP ₁ can be assigned as the playback spot for the check. The light intensity ratio of each spot is set so that the reproducing spot has the reproducing power and the recording / erasing spot has the recording power during recording. This can be arbitrarily determined by changing the structure of the diffraction grating 5. For example, playback power 1m
In the case of W and a recording power of 7 mW, the light intensity ratio may be set to 1: 7. FIG. 3 also shows the light emission power of the laser light source at the time of reproduction and at the time of recording, respectively. During playback, set the laser to low power _Pr.
To emit light. At this time, SP ₂ becomes the playback power,
(A) reproduction of a magneto-optical signal, (b) reproduction of a signal in which address information and the like are formed in advance in the form of uneven pits, (c) detection of a defocus signal, and (d) detection of a track deviation signal. Do. SP _1, SP ₃ is not used for power is low. Then the time of recording, to emit laser 2 at a high power P _w.
In this case, SP ₂ acts as an optical Supotsuto for recording / erasing i.e. overwriting. When a high-power laser beam is irradiated, the temperature of the recording film 101 increases, and the magnetization and coercive force decrease. At this time, when a magnetic field whose polarity is inverted by the magnetic head 10 according to the recording information is applied, the magnetization is fixed in the direction of the applied magnetic field in the process of cooling the recording film 101. Since the previous information is erased when the temperature of the recording film 101 rises, it is possible to simultaneously erase old information and record new information, that is, overwrite. Recording time SP ₂ also focus error signal detection, track shift signal detection is also performed. On the other hand, at this time, SP ₁ and SP ₃ have the reproduction power, so that SP ₃ precedes SP ₂ to reproduce the above-mentioned address information and the like, and SP ₁ reproduces the magneto-optical signal and performs an error check immediately after recording. . As described above, the reproduction system of the magneto-optical signal is switched between recording and reproduction. FIG. 3A shows this switching circuit. This is provided in the signal detection circuit 12. The switching of each signal detection circuit is performed by a switching switch 120. Switching is performed between recording and erasing, and a signal from the controller 15 is used for the timing. Address information or the like is recorded in the form of a magneto-optical signal, and when it is necessary to reproduce the information at the time of recording is required prior Supotsuto SP _3. For disk where address information or the like is formed in the form of land and groove pit, it is possible to reproduce the signal in SP _2. Or may not SP ₃ is when it is not necessary to reproduce the address information or the like in particular prior. In this case, the diffraction grating is set so that the intensity distribution of the light spot is as shown in FIG. Further, the switching circuit may have the configuration shown in FIG. 3 (b), for example. The switching of the magneto-optical signal detection circuit at the time of recording / erasing has been described above. However, the light spot for detecting the focus error signal and the track error signal may be switched at the time of recording / erasing. Table 1 shows an example of switching light spots for detecting a focus shift signal and a track shift signal. The switching circuit conforms to FIG. 3 and is omitted. Next, the signal detection optical system 9 will be described. In this embodiment, a differential detection optical system using a λ / 2 plate 901 and a polarizing beam splitter 903 is shown for detecting a magneto-optical signal. The defocus signal is detected at a position equidistant before and after the focal point of the lens 902 by the photo detector 9.
04,905 are arranged to obtain a defocus signal from a change in the size of the light spot on the photodetector. The detection of the track shift signal uses a so-called diffracted light differential system. FIG. 5 is a block diagram of a signal obtained from each photodetector. As the signal detection optical system, not only the above system but also various types can be considered. FIG. 6 shows a second embodiment of the present invention, in which the collimating lens 3 and the convex lens 902 are omitted. In this case, the shapes of the detectors 904 and 905 are the same as in the first embodiment. With this configuration, the device can be made smaller. [Effects of the Invention] According to the present invention, it is possible to realize a magneto-optical disk device capable of processing both overwriting and DRAW within one rotation of the disk with a single laser light source, so that a compact, inexpensive and high-performance optical disk can be realized. A magnetic disk device is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a first embodiment of the present invention, and FIG.
FIG. 6 is a diagram showing an intensity distribution of a light spot in the embodiment of FIG.
4 is a diagram showing a detection signal switching circuit, FIG. 4 is a diagram showing a modification of FIG. 2, FIG. 5 is a diagram showing a signal detection optical system in the first embodiment, and FIG. FIG. 7 is a diagram showing a second embodiment. DESCRIPTION OF SYMBOLS 1 ... Disk, 2 ... Semiconductor laser, 3 ... Collimator lens, 5 ... Diffraction grating, 6 ... Beam splitter, 7 ... Focusing lens, 9 ... Signal reproduction optical system, 10 ... Magnetic head, 11 ...
Semiconductor laser drive circuit, 12 ... signal detection circuit, 13 ... actuator drive circuit, 14 ... magnetic head drive circuit, 15 ... controller.

   ────────────────────────────────────────────────── ─── Continuation of front page       (56) References JP-A-62-34333 (JP, A)                 JP-A-62-92247 (JP, A)                 JP-A-63-157340 (JP, A)

Claims (1)

(57) [Claims] Magnetic field applying means for applying a magnetic field modulated in accordance with recording information to a recording medium; a single light source for continuously irradiating the recording medium with laser light;
The same diffraction grating as described above, wherein one of the two or more light beams is used as a first light spot for recording, and the other is used as a second light spot for reproduction, A magneto-optical disc device having an optical system for converging on a track. 2. 2. The magneto-optical disk drive according to claim 1, wherein a direction in which the first and second light spots are arranged coincides with a direction in which the track extends. 3. In a magneto-optical recording method in which a magnetic field modulated according to recording information is applied to a recording medium and information is recorded by continuously irradiating the recording medium with laser light, a laser light from a single light source is diffracted. And divides the light into higher-order and lower-order diffracted light, forms a first light spot from the lower-order diffracted light, forms a second light spot from the higher-order diffracted light, The first and second light spots are converged on the same track of the recording medium, and when information is recorded, the information is recorded with the first light spot and the information recorded with the second light spot is reproduced. Magneto-optical recording method. 4. In a magneto-optical recording method in which a magnetic field modulated according to recording information is applied to a recording medium and information is recorded by continuously irradiating the recording medium with laser light, a laser light from a single light source is diffracted. And divides the light into higher-order and lower-order diffracted light, forms a first light spot from the lower-order diffracted light, forms a second light spot from the higher-order diffracted light, The first and second light spots are converged on the same track of the recording medium, and at the time of recording information, the information recorded by the first light spot and the information recorded by the second light spot are reproduced to reproduce the information. Sometimes the first
A magneto-optical recording method, wherein reproduction is performed with a light spot.