JPH02208847A - Magneto-optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To dissolve a bit shift from a synchronizing signal on a magneto- optical disk by delaying a recording signal by a prescribed time from the synchronizing signal existing on the magneto-optical recording medium and driving a bias magnetic field impressing means by the delayed signal. CONSTITUTION:A bias magnetic field head 7 is driven by a magnetic field modulating circuit 9, and the magnetic field modulating circuit 9 is driven in synchronization with an information signal delayed by a delay circuit 10 for delaying the information signal to be inputted from a terminal 11. A delay amt. of the delay circuit 10 is corresponding to half time of a recording signal pulse width, and the bias magnetic field head 7 is constituted to be capable of moving in the radial derection of the optical disk 1 by following an optical head 4. Consequently, by delaying the information signal and then driving the magnetic field modulating circuit 9, the bit shift can be prevented form being involved in the whole recording pits. By this method, the bit shift from the synchronizing signal is eliminated, and a good regenerative signal can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magneto-optical recording/reproducing device that is capable of rewriting information on a magneto-optical recording medium by overwriting.

[Prior Art] Conventionally, a method as shown in FIG. 4 has been proposed as a magneto-optical recording/reproducing apparatus that enables information to be rewritten by overwriting.

In FIG. 5, 1 indicates a magneto-optical disk.

In this example, this magneto-optical disk is constructed by depositing a perpendicular magnetization film 3 on a glass substrate 2.

This magneto-optical disk 1 is rotated around the central axis 〇-〇゛.

Further, reference numeral 4 designates an optical head section that irradiates the perpendicularly magnetized film 3 of the magneto-optical disk l with a laser beam. It has a function of always focusing the laser light on the magneto-optical disk 1, and is configured to be movable in the radial direction of the magneto-optical disk 1. Reference numeral 7 denotes an electromagnet that applies a bias magnetic field to the perpendicular magnetization film 3 disposed on the magneto-optical disk 1 so as to face the optical head 4 . This electromagnet 7 is configured to move in the radial direction in conjunction with the optical head 4. The electromagnet 7 is also configured to be supplied with a current whose phase is inverted in accordance with the recording signal by a coil 8 connected to a magnetic field modulation circuit 9.

The magnetic field modulation circuit 9 operates according to the recording signal. For example, when the recording signal changes as shown in FIG. The structure is configured to generate a constant bias magnetic field strength (C) sufficient to make the direction of magnetization of the film 3 upward, and when the recording signal is "0", it is exactly opposite to when the recording signal is "l". It is configured to operate so that the bias magnetic field strength (C) is equal and constant in both directions. At this time, the laser beam from the optical head is emitted continuously in a recording state so that the laser beam intensity (b) is constant, and locally irradiates the perpendicular magnetization film 3 of the magneto-optical disk 1.
The temperature of the perpendicularly magnetized film in this irradiated portion is raised above the Curie point.

In the magneto-optical recording and reproducing apparatus configured as described above, when a recording signal (a) as shown in FIG. 6 is supplied, the laser light intensity (b),
The bias magnetic field strength (c) is as shown in the figure, respectively.
The laser beam intensity (b) is continuous at an intensity Pw sufficient to raise the perpendicular magnetization film 3 above the Curie point, and the bias magnetic field intensity (c) is at an intensity of ±H in synchronization with the recording signal (a). generated. Therefore, the perpendicular magnetization IP23 of the optical disk 1
A recording pattern as schematically shown in FIG. 6(d) is formed. Note that in this case, the blank and diagonally lined recording patterns indicate the states of upward magnetization and downward magnetization, respectively.

In this way, the magneto-optical recording and reproducing apparatus of this example continuously heats the perpendicular magnetization film 3 of the magneto-optical disk 1 above the Curie point with laser light, and magnetizes it in the direction of the magnetic field modulated according to the recording signal. Therefore, regardless of what information is recorded on the perpendicular magnetization film 3 of the magneto-optical disk 1, new information can be recorded by overwriting.

[Problem to be solved by the invention] However, in the above conventional example, as shown in FIG. The time from t to the center of "1" of the recording signal. The bit shift shortens the length by t, and the peak shift lengthens the length by t, resulting in a total bit shift of (tz - tt).

[Means for Solving the Problems] An object of the present invention is to provide a magneto-optical recording and reproducing device that can eliminate bit shifts from a synchronization signal on a magneto-optical disk.

Another object of the present invention is to provide a magneto-optical recording and reproducing apparatus that can eliminate peak shifts and bit shifts.

The above object has a means for condensing light onto a magneto-optical recording medium, and a bias magnetic field applying means for applying a predetermined bias magnetic field corresponding to a recording signal to the condensed part, and magnetically recording. In a magneto-optical recording and reproducing apparatus that records information by forming pits, the apparatus includes a delay means for delaying the recording signal by a predetermined time with respect to a synchronization signal present on the magneto-optical recording medium,
This is achieved by a magneto-optical recording and reproducing apparatus characterized in that the bias magnetic field applying means is driven by the delayed signal.

In addition to the above-mentioned delay means, by providing a bias magnetic field waveform adjustment means that makes the applied bias magnetic field strength weaker in the rear part of the recording bit to be formed than in other areas in the recording pit, the recorded pattern is prevented from being out of alignment. It can prevent peak shift and further increase the practical effect.

[Function] According to the present invention, by delaying the information signal and driving the magnetic field modulation circuit, it is possible to prevent the bit shift of the entire recording bits, eliminate the bit shift from the synchronization signal, and produce a good reproduction signal. can be obtained.

[Example] Hereinafter, the magneto-optical recording and reproducing apparatus and method according to the present invention will be described in detail based on specific examples. Note that in the present invention, a recording/reproducing device is a device that is capable of at least recording and, if necessary, processing of reproduction.

FIG. 1 is a schematic configuration diagram showing the most basic configuration of a magneto-optical recording/reproducing apparatus according to the present invention.

In FIG. 1, l is a magneto-optical disk.

The basic configuration is that a perpendicularly magnetized film 3 is adhered to a glass substrate 2. This magneto-optical disk 1 is configured to rotate around a central axis 0-0''. 4 is an optical head;
The optical head 4 basically consists of a semiconductor laser 5 and a lens 6, and has the function of always focusing the laser beam irradiated from the semiconductor laser 5 on the perpendicularly magnetized film. Further, the optical head 4 also moves in the radial direction of the magneto-optical disk l, which is also a rotating part. Reference numeral 7 denotes a bias magnetic field generating head disposed opposite to the position where the laser beam is focused by the optical head 4, and is an electromagnet consisting of a coil 8. The bias magnetic field head 7 is driven by a magnetic field modulation circuit 9. The magnetic field modulation circuit 9 is driven in synchronization with an information signal delayed from a delay circuit 10 that delays an information signal input from a terminal 11. Here, the delay amount of the delay circuit 10 is a time corresponding to t3 shown in FIG. 5 of the conventional example.

Note that this bias magnetic field head 7 is configured to follow the optical head 4 and move in the radial direction of the optical disk l.

In the above configuration, as shown in FIG. 2, consider a case where a synchronizing signal as shown in FIG. 2(a) is obtained as a signal for the information recording area from the optical disk l when recording information.

A recording signal (b) is generated based on this synchronization signal (a). This recording signal (b) is sent from the terminal 11 to the delay circuit 1.
0, and here it is delayed by the time t3 in FIG. 5, resulting in a delayed signal (c). Further, simultaneously with the synchronization signal, a laser beam is irradiated from the optical head 4, and continues to be irradiated continuously with a laser power pw that raises the temperature of the perpendicularly magnetized film 3 to the Curie point or higher. At this time, the delayed signal (c
) the magnetic field modulation circuit 9 is driven.

At this time, the bias magnetic field head driven by the magnetic field modulation circuit 9 generates a bias magnetic field with a strength of ±H in synchronization with the delay signal (C). Therefore, the perpendicular magnetization film 3 of the optical disk 1 has a recording pattern as schematically shown in FIG. 2(f). Here, the white portion and the hatched portion represent that the perpendicularly magnetized film is magnetized upward and downward, respectively. Therefore, such a recording pattern (f
) is formed, and the reproduced signal is as shown in (g). In this way, the reproduced signal has a bit shift amount of 1.0 from the synchronization signal to the recording bit center position as shown in the conventional example. The waveform has no .

Next, a magneto-optical recording and reproducing apparatus that can eliminate peak shifts and bit shifts will be described with reference to FIG. 4. In this embodiment, as shown in FIG. 3o is provided and the strength of the applied bias magnetic field is changed to be weaker in the rear part of the recording bit to be formed than in other areas within the recording bit, thereby preventing the recording pattern from failing.

In the above configuration, as shown in FIG. 4, when a synchronizing signal (a) is obtained from the optical disk during information recording, a recording signal (b) is generated based on this synchronizing signal (a). This recording signal (b) is input to the delay circuit 10 from the terminal 11, where it is delayed by the time t in FIG. 4, and becomes the delayed signal (c).

When a delay signal as shown in (c) is input, as shown in (e), the bias magnetic field strength is weakened at a time corresponding to the rear part of the bit within the 1-bit region. A bit formed by such laser light intensity (d) and bias magnetic field strength (e) is
) is constant, so the temperature distribution of the perpendicularly magnetized film 3 always has the same pattern in the laser irradiated area and depends on the strength of the applied bias magnetic field. Therefore (a)
When the bias magnetic field strength shown in is given, when the bias magnetic field strength is equal, the width of the formed bit is equal, and when the bias magnetic field strength is weakened, the temperature distribution on the perpendicularly magnetized film 3 becomes higher. Bits will be formed only in the region. Therefore, the recording bit pattern becomes a recording pattern schematically shown in <f), and is no longer an arrow-shaped recording pattern. Here, the perpendicular magnetization film is facing upward in the white part and the shaded part, respectively.
This means that it is magnetized downward. Therefore, the reproduced signal in a state where such a recording pattern (f) is formed is as shown in (g). In this way, the reproduced signal has a good waveform without the peak shift amount t shown in the conventional example, and by providing the delay circuit 10, it is possible to obtain a good waveform from the synchronization signal written on the magneto-optical disk. The bit shift amount t can also be eliminated.

Note that the present invention is not limited to the so-called Curie point writing method in which the irradiated area of the laser beam is raised to the Curie point;
The present invention can be similarly applied to Curie point compensation writing.

In addition, if the recording film is not only a single-layer recording medium but also a multilayer film, the problem arises whether the recording pattern is substantially in the feather-like shape,
It is clear that it is applicable to all.

[Effects of the Invention] As explained above, according to the present invention, by providing a circuit that delays the information signal that drives the bias magnetic field modulation circuit, it is possible to eliminate the bit shift from the synchronization signal on the magneto-optical disk. be.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the magneto-optical recording/reproducing apparatus of the present invention. FIG. 2 is an operational diagram illustrating the operation of the magneto-optical recording and reproducing apparatus shown in FIG. 1. FIG. 3 is a block diagram showing an embodiment of the magneto-optical recording/reproducing apparatus of the present invention. FIG. 4 is an operational diagram illustrating the operation of the magneto-optical recording and reproducing apparatus shown in FIG. 3. FIG. 5 is a block diagram of a conventional magneto-optical recording/reproducing apparatus. FIG. 6 is an operation diagram illustrating the operation of a conventional magneto-optical recording and reproducing apparatus. l: magneto-optical disk, 2 glass substrates, 3: perpendicular magnetization film, 4: optical head, 5: semiconductor laser, 6: lens, 7:
Electromagnet, 8: Coil, 9: Magnetic field modulation circuit, 10: Delay circuit 11: Input terminal, 30: Bias magnetic field waveform adjustment circuit. Figure 1 Agent Patent Attorney Seki Taira Yamashita Figure 1

Claims (3)

[Claims] (1) It has a means for focusing light on a magneto-optical recording medium and a bias magnetic field applying means for applying a predetermined bias magnetic field corresponding to a recording signal to the focused region, and magnetically forms recording pits. A magneto-optical recording/reproducing device for recording information by a magneto-optical recording medium, comprising a delay means for delaying the recording signal by a predetermined time with respect to a synchronization signal present on the magneto-optical recording medium;
A magneto-optical recording and reproducing apparatus characterized in that the bias magnetic field applying means is driven by the delayed signal. (2) The magneto-optical recording device according to claim 1, further comprising a bias magnetic field waveform adjustment means that makes the applied bias magnetic field strength weaker in the rear part of the recording pit to be formed than in other regions within the recording pit. playback device. (3) The magneto-optical recording/reproducing apparatus according to claim 2, wherein the temperature of the light condensing portion reaches a Curie point.