JP2712563B2 - Recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called magneto-optical recording system in which a magnetic medium is irradiated with light energy to cause a local temperature rise and simultaneously record a signal by applying a magnetic field. In particular, the present invention relates to a method for enabling overwriting (overlap recording) and recording using a plurality of light beams.

FIG. 4 is a schematic view showing a conventional technique. 4, reference numeral 51 denotes a magneto-optical disk, 52 denotes a recording film, 53 denotes an objective lens, 54 denotes a laser beam, 55 denotes a magnetic circuit, 56 denotes a coil, and 57 denotes a magnetic flux generated when a current is applied to the coil 56. Is shown. In the recording / reproducing apparatus configured as described above, a signal of a single frequency is applied to the magnetic circuit 56, a modulator of the light beam 54 synchronized with the signal is provided, and an information signal for modulating the magnetic field and the light beam is transmitted to the magnetic circuit 56. As shown in FIG. 5, by synchronizing, an information signal having a wide band is recorded on the magnetic medium 52 (Japanese Patent Application No. 63-2051).
Four).

Problems to be Solved by the Invention It is necessary to increase the relative speed between the optical disk and the optical head in order to record and reproduce information signals on the optical disk at a high speed. However, in general, increasing the relative speed increases the laser output for recording. There was a limit to what we had to do.

The present invention is for recording and reproducing information signals at high speed without increasing the relative speed, and provides a recording device capable of tracking a plurality of laser beams on a plurality of tracks of an optical disk and having an overwrite function. It is intended to do so.

Means for Solving the Problems The present invention solves the above problems, by scanning the track with a plurality of light beams while modulating the magnetic field with a predetermined signal, by a signal synchronized with the predetermined signal,
The light beam is modulated to record an information signal on a predetermined track.

Operation According to the above configuration, by combining a single magnetic field modulator and a plurality of light beams, information signals can be recorded on a plurality of tracks at the same time, and can be configured to have an overwrite function. is there.

Embodiment Hereinafter, a recording apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 3. FIG.

 FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, 1 is a magneto-optical disk, 2 is a semiconductor laser, and has two outgoing beams (2a, 2b). Reference numeral 3 denotes a collimator lens, 4 denotes a beam splitter, and 5 denotes an image rotating prism using, for example, a Dove prism. 6 is a rotating device for rotating the prism 5, 7 is an objective lens,
Magneto-optical disk 1 by tracking actuator 8
In the radial direction of. The objective lens 7 is also movable in the focus direction, but is not shown here. Reference numeral 9 denotes a lens for enlarging the light reflected from the magneto-optical disk 1 and projecting the light having passed through the polarizing beam splitter 10 to photodetectors 11 and 12.

Reference numerals 13 and 14 denote amplifiers for separately converting the two outputs of the two-divided photodetectors (11a and 11b) into voltages. Reference numerals 15 and 16 denote amplifiers for separately converting the two outputs of the two-divided photodetectors (12a, 12b) into voltages.

17 is an adder for adding the outputs of the amplifiers 14 and 15, and 18 is an adder for adding the outputs of the amplifiers 13 and 16. Here, the laser beam 2a is incident on the same track of the magneto-optical disk 1, and
The reflected laser beam is guided to photodetectors 12a and 13a.
Similarly, the laser beam 2b is guided to the photo detectors 12b and 13b.
As a result, an output signal of the pre-pit reproduced by the laser beam 2b is obtained at the output of the adder 17, and an information signal of the pre-pit reproduced by the laser beam 2a is obtained at the output of the adder 18. A magneto-optical reproduction signal reproduced by the laser beam 2b is obtained in the differential amplifier 19, and a magneto-optical reproduction signal reproduced by the laser beam 2a is obtained in the output of the differential amplifier 20.

Reference numeral 21 denotes a magnetic head.
This is for applying a magnetic field to the position of the beam spot formed on the recording film. The laser beams 2a and 2b form beam spots 76 and 77 on tracks A and B shown in FIG. 3, respectively. Track A has wobble pits 70A, 71A, 73A and 74B for tracking, and track B has the same structure. 70B, 71B, 73
B, 74B. Clock pits for recording synchronization clocks are indicated by 72A, 75A, 72B, and 75B, respectively, and recording areas are provided between 72A and 73A and between 72B and 73B, respectively. In order to track the beam spot on the track of the magneto-optical disk described above, a tracking error is detected by the beam spot 76, the tracking actuator 8 is controlled, and the image rotating prism 5 is similarly controlled by the beam spot 77. 30,33 is the laser beam 2a,
2b is a tracking error signal detector, 31 and 34 are equalizers, and 32 and 35 are drive amplifiers for controlling the tracking actuator 8 and the rotation actuator 6.

30a is a reproduction signal of the clock pit of the track A, and 30b is a reproduction signal of the clock pit of the track B. 36 is a reference clock generator and laser beams 2a and 2
Set the recording start timing of b. 37 is an information signal input, 38 is a clock separator, writes an information signal in a buffer memory 39, reads out the information signal with a 36d clock supplied from a controller 36, and sends it to an S / P (serial / parallel signal converter) 40. input. Reference numerals 41 and 46 denote encoders that perform an encoding operation in synchronization with the magnetic field modulation clock signal output from the controller 36.

Reference numerals 42 and 47 denote buffer memories which are transferred to modulators 44 and 49 by a 36d clock signal and input. Modulators 44 and 49 have R /
W (recording / reproducing) 45,50 switching signal switches between recording operation and reproducing operation. Modulators 44 and 49 modulate the two output beams of the two lasers. An amplifier 51 supplies a modulation signal to the magnetic head 21.

 Next, the operation will be described.

First, the operation of writing the information signal 37 to the magneto-optical disk 1 is performed by the S / P 40 of writing the information signal 37 to the buffer memory 39.
, And a modulation signal is supplied to the laser beam and the magnetic head 21 as shown in the timing chart of FIG. The outputs of the encoders 41 and 46 are input to the buffer memories 42 and 47, and the buffer memories 42 and 47 output the clock signal (Ck) 36d.
The start and stop pulses 36b and 36c of the optical modulation via the Ck 36d and the gates 43 and 48 control the transfer timing. By doing so, the information signal can be recorded in the recording area on the track of the magneto-optical disk shown in FIG. 3 at an accurate position with respect to the clock pits indicated by 72A, 72B, 75A and 75B. it can. Controller 36
Creates a timing pulse for this purpose.
The two laser beams 2a and 2b of the two lasers are converted into parallel light by a collimator lens 3, passed through a beam splitter 4, an image rotating prism 5, and an objective lens 7 to an magneto-optical disk 1.
A beam spot on the track. The objective lens 7 is displaced in the radial direction of the magneto-optical disk 1 by the tracking actuator 8. The rotation actuator 6
When the image rotation prism 5 rotates, the angle between the line segment connecting the laser beams and the track of the magneto-optical disk 1 of the two laser beams 2a and 2b changes, so that both the tracking actuator 8 and the rotation actuator 6 operate. By doing so, the two laser beams 2a and 2b can be tracked on adjacent tracks on the magneto-optical disk 1. For this reason, the tracking error signal detector 30 detects the tracking error signal using the reproduction signals of the wobble pits 70a and 71a shown in FIG. That is, since the wobble pit is configured to be offset from the center of the track by a fixed distance, for example, the wobble pit
The difference between the reproduction amplitude of 70a and the reproduction amplitude of the wobble pit 71a is a tracking error signal. Drive amplifier 32 optimizes the response characteristics of tracking servo by equalizer 31
Then, the tracking actuator 8 is displaced to cause the laser beam 2a to track the track A in FIG. Similarly, the tracking error signal of the laser beam 2b is detected by the tracking error signal detector 33, and the equalizer 3
4. The rotation actuator 6 is controlled via the drive amplifier 35. During recording, the laser beam modulators 44 and 49 are controlled to make the laser beam power unmodulated only in the wobble pit reproducing section, and the tracking error signal detectors 30 and 3 are set by setting the laser beam power to a constant value.
3 can keep the output level constant. This makes it possible to keep the gain of the tracking servo constant without using any additional circuit.

Next, the operation at the time of reproducing the information signal will be described. The recording domain formed as a change in the magnetization on the track of the magneto-optical disk is reflected by the beam spot 76 for scanning the recording domain by the polarization beam splitter 10 for the S wave and the P wave.
The light is separated into waves and projected on the photodetectors 13a and 12a. Then, a reproduced signal is obtained at the output of the differential amplifier 20 via the amplifiers 14 and 15. Similarly, a reproduced signal reproduced by the beam spot 77 is obtained at the output of the differential amplifier 19. These reproduced signals are decoded and transferred to a controller (not shown).

FIG. 2 is a waveform diagram for explaining the recording operation of the block diagram shown in FIG. In FIG. 2, reference numeral 2-1 denotes outputs of the encoders 41 and 46. In FIG. 2, the same operation waveforms are shown for the laser beams 2a and 2b for simplicity, but they are not the same in actual operation because the outputs of the encoders 41 and 46 are different. 2-1 is the output of the encoders 41 and 46, 2-2 is the clock 36d, 2-3 is the intensity of the magnetic field of the magnetic head 21, 2-4 is the laser output light 2a, 2b, and 2-5 is the laser 2a, 2b. The temperature of the laser beam spots 76 and 77 on the recording film is shown, and 2-6 shows the recording domain formed as a result.

As described above, the amplitude modulation of the two laser beams can be performed in synchronization with the magnetic field of the magnetic head 21.
Overwriting becomes possible. Further, the magnetic head for generating a magnetic field can be provided with a slider so as to slide a predetermined height (for example, about 10 μm) from the recording film of the magneto-optical disk 1, so that the power for modulating the magnetic field is reduced. It is possible. In the method of the present invention, it is necessary to control so that the phase of the magnetic field and the modulation phase of the laser power always have a constant difference. However, the monitor light of the laser is detected, the phase is compared with the detected output of the magnetic field, and the buffer memory 42, Four
The phase of the clock input to 7 can also be controlled.
As the magnetic field detection output, the current of the magnetic head may be detected, or a separate detector may be provided. In order to control the phase of the clock, the clock signal input to the gates 43 and 48 may be passed through a phase modulator, and the phase modulator may be modulated with a phase error signal obtained by comparing the phases.

The S / P (serial / parallel converter) 40 can be divided into encoders 41 and 46 one bit at a time.
It is convenient to convert by dividing the time axis every 12 bytes.

As described above, according to the recording apparatus of the present invention, two tracks,
Two-beam overwriting can be realized with a single magnetic field modulator, and the transfer speed can be increased with a simple configuration.
Further, there is a feature that the band of the magnetic field modulator is not widened unlike the conventional magnetic modulation method. According to the method of the present invention, when the magnetic field changes from the S pole to the N pole or from the N pole to the S pole, the temperature of the recording film of the magneto-optical disk always exceeds the Curie point. It has a number of features, such as being able to accurately control the time interval between recorded domains in which the change in magnetization is highly accurate.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a timing chart showing the operation of the block diagram of FIG.
FIG. 3 is a schematic diagram showing a configuration of a track of a magneto-optical disk, FIG. 4 is a schematic diagram of a conventional configuration example, and FIG. 5 is a timing chart showing the operation of FIG. 1 ... Magneto-optical disk, 2 ... 2-beam laser, 5 ...
Image rotating prism, 6 ... Rotating actuator, 10 ... Polarizing beam splitter, 11,12 ... Photodetector, 21 ... Magnetic head, 30,31,32, ... Tracking servo system, 33,34,3
5 ... Image rotation control system, 40 ... Serial / parallel converter, 41,46, ... Encoder, 44,49 ... Modulator.

Claims (3)

(57) [Claims] A magnetic head for applying a change in a magnetic field on the magnetic medium; means for applying a current to the magnetic head for generating a magnetic field on the magnetic medium; Means for irradiating a plurality of light spots having a large tangential diameter on the plurality of tracks on the magnetic medium by tracking them, and wherein the plurality of light spots are within a predetermined intensity range of the magnetic field. A recording apparatus comprising: means for positioning; and means for modulating the light spot in accordance with an input information signal, wherein the information signal is recorded on the magnetic medium as a change in magnetization direction. 2. The apparatus according to claim 1, wherein the timing at which the magnitude of the magnetic field takes the maximum value and the timing at which the local temperature of the magnetic medium caused by the modulated light spot takes the maximum value are substantially synchronized. The recording device according to claim 1. 3. The recording apparatus according to claim 1, wherein a position of one of the plurality of light spots with respect to the track is detected to constitute a tracking servo.