JPH03189943A - magneto-optical recording device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magneto-optical recording device, and particularly to a magneto-optical recording medium, in which an alternating magnetic field is applied as a recording bias magnetic field, and a light beam corresponding to a recording signal is applied to a magneto-optical recording medium. The present invention relates to a magneto-optical recording device that records information on a magneto-optical recording medium by modulating and irradiating a beam in synchronization with an alternating magnetic field.

[Conventional technology]

Conventionally, an alternating current magnetic field is applied to a magneto-optical recording medium as a recording bias magnetic field, and a light beam corresponding to a recording signal is modulated and irradiated in synchronization with the alternating magnetic field. The one shown in FIG. 3 has been proposed as a magneto-optical recording device in which information can be rewritten by overwriting.

In FIG. 3, 1 indicates a magneto-optical disk, and 2 indicates a magnetic film. This magneto-optical disk 1 is rotatably driven by a motor 3.

The magneto-optical disk 1 is irradiated with light by the optical pickup 4, and information is recorded or reproduced (2). The optical pickup 4 has a built-in semiconductor laser 5 as a light source. The light emitted from this semiconductor laser 5 is
The light passes through the collimator lens 6 and the beam splitter 7a, and is focused onto the magneto-optical disk 1 by the objective lens 8. On the other hand, the light reflected by the magneto-optical disk 1 passes through the objective lens 8 again and is separated from the incident light by the beam splitter 7&.
After the light is further split into two by the beam splitter 7b.

One of the lights is received by the optical sensor 10a via the sensor lens 9a. Then, based on the output of this optical sensor 10a, A
A focus error signal and a tracking error signal are detected by the T-AF circuit 11.

These error signals are input to the actuator 12,
Auto tracking and auto focusing are performed by driving the objective lens 8.

The other light is further split into two by a beam splitter 7c, and each light is sent to a sensor lens 9b.

The light is received by the optical sensors 10b and 10c via the light beam 9c.

A reproduced signal is obtained by summing the signals from the optical sensor 10b and the optical sensor 10c. optical pickup 4
In this method, the magnetic film 2 of the magneto-optical disk 1 is locally irradiated with laser light of a constant intensity emitted in a pulsed manner by a semiconductor laser 5, and the temperature of the magnetic film 2 in this irradiated portion is raised above the Curie point. It is configured to

Reference numeral 13 denotes an electromagnet for applying a magnetic field to the magnetic film 2 of the magneto-optical disk 1. In this example, this electromagnet 13 is interlocked with the optical pickup 4 across the magneto-optical disk 1 to apply a magnetic field in the radial direction of the magneto-optical disk. It is configured so that it can be moved.

Further, 14 indicates a reference oscillator, and the laser light emitted from the semiconductor laser 5 is modulated by the recording signal produced by the recording signal modulator 15 in synchronization with the reference signal of a constant frequency produced by the reference oscillator 14. be done. The laser light emitted from the semiconductor laser 5 passes through a collimator lens 6 and a beam splinter 7a, and is focused onto the magneto-optical disk 1 by an objective lens 8. At the same time, the electromagnet 13 is driven by the drive circuit 16 at a constant frequency generated by the reference oscillator 4, and an alternating current magnetic field synchronized with (the modulation signal of) the laser beam is applied onto the magneto-optical disk 1 to record data. will be carried out. Note that reference numeral 17 is a cap and a cap for matching the resonance frequency of the electromagnet 13 with the reference frequency.

In the magneto-optical recording device configured in this manner.

For example, when a recording signal as shown in FIG. 4 (Al) is input to the recording signal modulator 15, the recording signal as shown in FIG. As shown in the figure (0), the laser beam is applied to the magneto-optical disk 1.
When irradiated in a pulsed manner, bits 4a + 4b + 4c, etc., as schematically shown in Fig. 4, are formed.Actually, when recording on a magneto-optical disk with groups, The bits are straightened in groups as shown in Figure 4 (i
Bits 4 a', 4 b'+ 48'+ as shown in
"' is formed.

According to such a magneto-optical recording device, it is possible to record new information by overwriting the information irrespective of the information previously written on the magneto-optical disk 1.

(5) [Problem to be solved by the invention] However, the above-mentioned magneto-optical recording device is
When trying to record a 3T pattern recording signal with a high level "1" of 3T and a low level "0°" of 3T as shown in Figure (A), the AC magnetic field shown in Figure 4(B) The laser beams are synchronously turned on as shown in FIG. 4 fc1. In this case, the laser beam is turned on when the alternating current magnetic field reaches its maximum positive value during the period when the recording signal is at a high level of "1", and during the period when the signal level of the recording signal is at the low level "'0". , the laser beam is turned on when the alternating current magnetic field reaches its minimum negative value. Then, Figure 4 (C
As shown in I, when the recording signal changes from high level "]P to low level "O"', the time interval (T1) at which the laser lights up is longer υ, and the recording signal changes from low level 1 to low level "O"'.
When changing from 0'' to high level 1, the time interval (T2) between laser lighting becomes shorter, so 1 and O
The length of the bits will be different. Therefore, the reproduced signal is
Even though the recorded signal is a 3T pattern, it is not shown in Fig. 4 (
As shown in Fl (6), high level "1" is 3.5 T, low level "0"
is 2.5T for the duty of the recording signal.

There was an inconvenience that the duty of the reproduced signal was shifted.

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, it is an object of the present invention to provide a magneto-optical recording device that can form bits such that the duty of a reproduced signal does not deviate from the recorded signal and can perform good overwriting. shall be.

[Means to solve the problem]

The magneto-optical recording device of the present invention has the following features for the magneto-optical recording medium:
In a magneto-optical recording device that records information on a magneto-optical recording medium by applying an alternating current magnetic field as a recording bias magnetic field and modulating and irradiating a light beam corresponding to a recording signal in synchronization with the alternating current magnetic field, the above-mentioned alternating current It is characterized by having means for applying an offset magnetic field of constant strength in a predetermined direction of the magnetic field.

[Effect]

In the present invention, an offset magnetic field is generated in the alternating current magnetic field in a direction in which the recording bit pattern is shorter than the signal length of the actual recording signal, and the recording bit z? A large magnetic field is applied in the direction where the turns become shorter.

By applying a small magnetic field in the direction in which the recording bit pattern becomes longer, the total energy of the magnetic field strength and laser power on the magneto-optical recording medium becomes larger in the direction in which the recording bit pattern becomes shorter. In addition, the length of the recording bit pattern and the length of the recording signal pattern are set to be equal to each other, so that the length of the recording bit pattern becomes smaller as the length increases.

This is an attempt to correct the duty shift with respect to the reproduced signal.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram showing an embodiment of the magneto-optical recording device of the present invention.

FIGS. 2A to 2C are explanatory diagrams of the recording operation of the magneto-optical recording device.

Note that in FIGS. 1 and 2, parts corresponding to those in FIGS. 3 and 4 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In this embodiment, by arranging a permanent magnet 18 near the objective lens 8 of the optical pickup 4 as shown in FIG. so that it can be added in the direction of

In the magneto-optical recording device of this embodiment configured in this way, a high level "1" signal 3 T as shown in FIG. 2(A) is used.
When a 3T/'' turn recording signal with low level ``0'' of 3T is supplied, the permanent magnet 18 is applied to an alternating current magnetic field in a direction that shortens the length of the recording bit, as shown in Figure 2 (Bl).
By applying an offset (bias magnetic field ΔHc), the strength of the magnetic field during the high level "1" period of the recording signal is reduced, and the strength of the magnetic field during the low level "O" period is increased. As shown in FIG. 2 (0), the size of the recording bit formed on the magneto-optical disk 1 is
The period of low level “0” when the length of the recording bit becomes short (
9) A thick line is placed in between, and it is made smaller during the 1' period when the length of the recording bit becomes longer. Note that when recording bits are recorded on the magneto-optical disk 1 with a group, the second Both sides of the recorded bit as shown in FIG. 9 are corrected by the group, resulting in a good quality recorded bit as shown in FIG. 2 (]11m.

Therefore, the length of the recording bits recorded on the magneto-optical disk corresponds to the recording signal, and the reproduced signal also has a length shown in Figure 2 (
As shown in the square, the duty does not deviate from the recording signal.

〔Effect of the invention〕

As explained above, according to the present invention, magneto-optical recording is performed by applying an alternating magnetic field as a recording bias magnetic field and modulating and irradiating a light beam corresponding to a recording signal in synchronization with the alternating magnetic field. In a magneto-optical recording device that records information on a medium.

By applying an offset magnetic field by means of applying an offset magnetic field in a predetermined direction of an alternating magnetic field for a bias magnetic field, and making a pattern of 1" and "0" in which the length of the recording bit becomes shorter in that direction (10 ) Since the lengths of the recording bit corresponding to 11'' and the recording pit corresponding to @0'' can be adjusted, the duty of the reproduced signal can be made equal to the recording signal.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the magneto-optical recording device of the present invention. FIG. 2 is an explanatory diagram of the recording operation of the magneto-optical recording device. FIG. 3 is a schematic configuration diagram showing a conventional magneto-optical recording device. I is an explanatory diagram of the recording operation of the conventional magneto-optical recording device. 1... Magneto-optical disk, 2... Magnetic film %3... Motor, 4... Optical pickup, 5... Semiconductor laser, 6...Collimator lens-7a e 7 b #
7 e...Beam sinter, 8...Objective lens-
9a + 9 b + 9 c...Sensor lens, 1
0s1.10b, 10C... optical sensor. 11...AT-AF circuit, 12...actuator. 13... Electromagnet, 13B... Coil, 14... Reference oscillation circuit, 15... Recording signal modulator, 16... Drive circuit. 17... Cano e Shita%] 8... Permanent magnet.

Claims (1)

[Claims] (1) By applying an alternating current magnetic field as a recording bias magnetic field to the magneto-optical recording medium and modulating and irradiating a light beam corresponding to the recording signal in synchronization with the alternating magnetic field, information is transmitted to the magneto-optical recording medium. What is claimed is: 1. A magneto-optical recording device for recording, comprising means for applying an offset magnetic field of constant strength in a predetermined direction of the alternating current magnetic field.