JPS61184744A - Photomagnetic recording device - Google Patents

Abstract

PURPOSE:To attain a rewrite recording job at a high speed by producing the record information signal synchronized with an AC magnetic field and the delayed record information signal and irradiating the light beam while the magnetic fields corresponding to those two types of record information signals are produced for recording of information. CONSTITUTION:The laser beams produced from two semiconductor lasers 1 and 2 form two beam spots P1' and P2' of light beams P1 and P1 on a disk 9. An optical head 10 is moved in the radius direction of the disk 9 for recording of plural tracks. An LC oscillation circuit 12 is formed by a bias magnetic field coil 11 on the rear side of the disk 9 and has oscillations in a cycle T. This ocsillation output M is converted into a magnetized signal (m) by a shaping circuit 13. The input information signal S is converted into the record information signal S1 through synchronization secured by a sampling circuit 14 with the signal (m) defined as a basic clock for recording. The signal S1 is delayedby l/v through a delay circuit 15 for production of the record information signal S2, where the linear speed is set at (v) under the beam and the distance between both beams is set at (l) respectively. Then modulation circuits 16 and 17 produce modulation signals L1 and L2 from those record information signals and the signal (m).

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording device, and more specifically, to recording an information signal on a recording medium using a light beam and reproducing the recorded signal. , relates to an erasable optical information recording device.

[Prior art]

The above-mentioned optical information recording apparatus is generally referred to as a magneto-optical disk apparatus, in which a disk in which a thin film of ferromagnetic material is formed on a non-magnetic material is used as a recording medium.

The magnetic film on the recording medium is magnetized in advance with its orientation aligned in the perpendicular direction.

When recording information, an external magnetic field is applied, and the magnetic film is irradiated with an original beam modulated according to the information from a recording section consisting of a Rade light source, an imaging lens, etc. The portion irradiated with the original beam is heated by the light energy, and when the temperature reaches the Curie point temperature (approximately 160° C.), the magnetization direction becomes disordered.

Next, as the recording medium moves, the position of the light beam moves to the Ya part, the temperature decreases, and the magnetization direction is reversed from the surroundings by external magnetic flux and magnetized again.

In this way, information is recorded on the magnetic film as a reversal of magnetization, forming a signal train.

On the other hand, during reading, the original beam oscillated from a semiconductor radar or the like in the reproducing section and polarized by a polarizer is irradiated onto the signal train formed on the four magnetic films, and the irradiated part is magnetized by the magnetic Kerr effect. It is reflected as light that is optically rotated according to the direction. This reflected light is separated from the incident light by a beam smitter or the like in the reproducing section, guided through an analyzer to a light receiving element, and information is reproduced by detecting the magnetization direction from the polarization direction.

The great advantage of this magneto-optical disk is that it is capable of recording, reproducing, and re-recording, and unnecessary information can be erased.

[Problem that the invention seeks to solve]

In such a magneto-optical disk device, in order to rewrite information that has already been recorded, the recording area must first be erased, in other words, the magnetization must be aligned in the first uniform direction, and then, New information had to be recorded in this area.

For this reason, unlike conventional magnetic %f disks, overwriting cannot be performed, and there is a drawback that erasing time is required and high-level rewriting is not possible.

A method to solve this problem is to scan the medium with an unmodulated original beam, apply an external magnetic field modulated by an information signal to the area irradiated with this light beam, and magnetize the recording medium in the direction of the applied external magnetic field. There is a way to record information by doing this.

However, with this method, it is necessary to modulate the magnetic field with an information signal, and in order to modulate this magnetic field at high speed, it is necessary to drive the magnetic field modulation coil with a high-output amplifier, or use a magnetic field modulation coil or yoke. A way to get close to the medium is required. However, it is not practical to use a high-output amplifier, and placing the coil or its yoke close to the recording medium does not take advantage of the magneto-optical disk's ability to record and play without touching the edge. There was a drawback.

[Means for solving problems]

According to the present invention, in order to solve the problems of the prior art as described above, in an apparatus that records information by scanning a recording medium at a speed V with an original beam modulated by a digital signal, the irradiation area of the light beam is means for applying an alternating magnetic field with a period T to , and the light beam is separated from the preceding light beam P and the light beam V by an interval t=n, where n is an odd number, and is separated from the following light beam P2. It has a means for generating a recorded information signal S synchronized with the alternating current magnetic field and a recorded information signal 52ft delayed by 7 times. A light beam characterized in that the light beam P is irradiated while a magnetic field corresponding to the recording information signal S2 is generated, and the light beam P2 is caught while a magnetic field corresponding to the recording information signal S2 is generated to record information. A magnetic recording device is provided.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described based on the drawings.

FIG. 1 is a schematic block diagram showing a magneto-optical recording device of the present invention. The radar light generated from the two semiconductor radars 1 and 2 is converted into parallel light by a collimator lens 3, passes through a beam sinter 4, and is collimated by an objective lens 50 into a disk-shaped recording medium 9 (hereinafter simply referred to as disk 9). 2 on top of
Two beams of light PP
Tie. Di 1' 2 Reflected from Suff 9, the nine parts pass through objective lens 5 again,
It is reflected by the multilayer film on the diagonal of the beam splitter 4, is focused by the focusing lens 6, and reaches the light beams 7 and 8. Signals of focus deviation and tracking deviation are obtained by the optical sensors 7 and 8 using a known method, and autofocus or autotracking is performed by driving the 50 objective lenses 7 and 8 with an air actuator or the like. I do.

These optical elements are integrated into an optical head 10 (g
By moving the optical head 10 in the radial direction of the disk 90, recording is performed on the 11 m) rack on the disk 9. In the region irradiated with the original beam, there is a bias magnetic field coil 11 on the back side of the disk 9, which is a coil that constitutes an LC oscillation circuit 12. The LC oscillation circuit 12 oscillates with a period T, and the oscillation output M is converted by the shaping circuit 13 into a magnetization reversal signal m of a digital signal.

Here, let S be the manual information signal to be recorded on the disk 9. The input information signal S is synchronized by the sampling circuit 14 using the magnetization reversal signal m as the basic clock for recording, and is converted into the recording information signal S. Also, the linear velocity under the beam due to 90 rotations of the disk is V, and the interval between the two beams is t.
Then, the recording information signal S2 is generated by delaying the signal S by l/v in the delay circuit 15. The modulation circuit 16 converts the recording information signal S and the magnetization reversal signal m into the radar-1 modulation signal L, and the modulation circuit 17 generates the recording information signal S.
A modulation signal L2 of radar-2 is generated from the magnetization reversal signal m.

,;g2 Figure is a schematic diagram showing the positions of two beam spots P' and Pd on the disk 9, which are placed with a distance between them on the spot indicated by the broken line. It is assumed that the truck travels under the beam from left to right in the direction of the arrow, and beam spot P' precedes P2'. In addition, Fig. 2 (a
) and (b) will be explained later.

Next, the information recording method of the present invention will be explained using the time chart of each signal shown in FIG.

The output M of the LC oscillator circuit 12 is adjusted to indicate the direction of the magnetic field generated on the disk 9 by the coil 11; when positive, the magnetic field on the disk is directed upward, and when negative, the magnetic field is directed downward. This output M is converted by a shaping circuit 15 into a magnetization reversal signal m that is reversed when the magnetic field in the positive and negative directions reaches its maximum.

In order to synchronize the human power information signal S with the magnetic field generated by the LC oscillation circuit, the human power information signal S is turned into a magnetization reversal signal m)
The recording information signal Sl is generated by tenbling at the falling edge of the signal.

If the interval between the two beams is set to t = i (as shown in Fig. 2 (a)), the recording information signal S is delayed by the time it takes for one point on the disk to move (T = -), and the ratio of recording information is Signal 52fI: Create. Modulation signal L (hereinafter simply referred to as radar signal L) that lights up radar 1 only while the magnetization reversal signal m and recording information signal S are dispersed.
, generates a modulation signal L2 (hereinafter simply referred to as radar signal L2) that turns on radar 2 only while the magnetization reversal signal m and recording information signal S2 match.

By irradiating the disk 9 with radar light while selecting the bias magnetic field using the two radar beams created in this manner, information can be rewritten without having to be erased in advance.

Here, the recording information signal S1 is generated by the radar signals S and S2 generated as described above and the magnetization reversal signal m.
is recorded on the disc 9 without erasing the previous information.

The magnetic field reversal signal m repeats reversal at a constant period regardless of the radar signal L2, so the radar
The direction of magnetization when the signals L and L2 are in the ON state is recorded on the disk as is. That is, the magnetization reversal signal m
The information signal recorded on the disk by the radar signal □ is U (solid line), and similarly the magnetization reversal signal m
An information signal U2 (solid line) is generated from the radar signal L2. Beam spots P' and P2' report the distance 1@KL on the disk 9. Since the signal U is delayed by ■ compared to the information signal U, the signal sequence actually recorded on the disk 9 is the U signal. U
2' (an information signal obtained by advancing U2 by - on the time axis of the time chart) becomes a composite signal U3. The combined signal U3 becomes the same signal sequence as the recorded information signal S.

Regarding the size of the beam spots P/ and p2/, it is clear from Fig. 2 (ω) that when the light beam is effective and the pre-recording diameter is reached, the information can be recorded within the track without being skipped. You can increase the amount of information available.

Furthermore, in the actual leprosy example, the direction M of the magnetic field on the disk and the magnetization reversal signal m are out of phase by 90°, but this deviation is made smaller if the heat capacity of the recording medium is small.

The present invention is not limited to the embodiments described above, and can be modified in places.

For example, although n = 1 was explained in the above embodiment, if n is a positive odd number, the two beams can be rewritten without skipping information, and there is no necessity to limit n = 1. FIG. 2(b) shows the arrangement of the beam subsystems P/ and p2/ when n = 3 and 9, and S2 and L2 at this time are added to FIG. 3 as S23 and L23, respectively.

Furthermore, in the embodiment described above, the signal S2 was created by delaying the recording information signal S by the amount of . By inverting the signal L and delaying it by -, a similar no-day signal L2 can be generated.

〔Effect of the invention〕

As described above, according to the optical information recording device of the present invention, by irradiating the beam light while selecting the bias magnetic field 'f: two light beams, it is possible to perform high-speed erasing without the need for prior erasing. A rewritten record has become the Roe group.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing an optical information recording device of the present invention. FIG. 2 is a schematic diagram showing the arrangement of light beams on a disk of the optical information recording apparatus of the present invention, and FIG. 3 is a time chart showing the relationship between each signal. 1.2: Semiconductor radar 1 4: Beam sinter, 7, 8 two-wavelength sensor, 9: Magneto-optical disk, 11: Bias magnetic field coil.

Claims (2)

[Claims] (1) An apparatus for recording information by scanning a recording medium at a speed v with a light beam modulated by a digital signal, comprising means for applying an alternating current magnetic field with a period T to an area irradiated with the light beam, The light beam is spaced l=n(vT) from the preceding light beam P_1 and from the light beam P_1 by an odd number n.
The recording medium comprises a recording information signal S_1 synchronized with the alternating magnetic field and a recording information signal S_2 delayed by l/v. While a magnetic field corresponding to the recording information signal S_1 is generated in the upper recording area, the light beam P
A magneto-optical recording device characterized in that a magneto-optical recording device records information by emitting a light beam P_2 while a magnetic field corresponding to a recording information signal S_2 is generated. (2) The diameter of the spots of the light beams P_1 and P_2 is vT
2. The magneto-optical recording device according to claim 1, wherein the magneto-optical recording device is equal to /2.