JPH02308460A - Magneto-optical recorder - 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 more specifically, it proposes a magneto-optical recording device that can override (overwrite) a magneto-optical disk.

[Conventional technology]

When recording data on a magneto-optical disk, a laser beam is projected onto the data recording position of the perpendicularly magnetized film, and a magnetic field related to the data is applied. When the temperature of the perpendicularly magnetized film at the position where the laser beam is projected rises and reaches the Curie point or above, the perpendicularly magnetized film is magnetized in the direction of the applied magnetic field, and data is recorded on the magneto-optical disk. be done.

FIG. 4 is a block diagram showing the main parts of a conventional magneto-optical recording device that allows data to be rewritten by overriding in such a magneto-optical recording method.

The magneto-optical disk 1 is constructed by coating a perpendicularly magnetized film 3 on a transparent substrate 2, and the magneto-optical disk 1 rotates around a central axis 0.

An optical head section 4 including a semiconductor laser 5 and a lens 6 is disposed on one side of the magneto-optical disk 1 . Laser light LB emitted from this semiconductor laser 5 passes through a lens 6 and is projected onto the perpendicularly magnetized film 3 .

Further, the optical head section 4 can move in the radial direction of the magneto-optical disk 1 while maintaining a predetermined distance from the magneto-optical disk 1.

An electromagnet 7 for applying a magnetic field is provided on the other side of the magneto-optical disk l, and this electromagnet 7
It faces the optical head section 4 via a. Further, this electromagnet 7 can be moved in conjunction with the optical head section 4.

Furthermore, a magnetic field modulation circuit 8 is provided for magnetic field modulation,
Its input side is connected to the recording signal input terminal 9, and its output side is connected to the coil 7a of the electromagnet 7.

Next, the operation of this magneto-optical recording device will be explained with reference to FIG. 5, which shows the waveforms and recording patterns of various signals. Figure 5 (A
) When a recording signal as shown in FIG. 5(B) is input to the magnetic field modulation circuit 8, the electromagnet 7 generates a magnetic field as shown in FIG.
It is applied to the perpendicular magnetization film 3 of the magneto-optical disk 1. in this case,
As shown in FIG. 5(C), the perpendicular magnetization film 3 is irradiated with a laser beam B with a constant light intensity that raises the temperature of the perpendicular magnetization film 3 to more than one Curie point, so that the magneto-optical disk l In the recording trunk of the perpendicularly magnetized film 3, recording patterns 104, 108, . . . IOE as shown in FIG. Note that the (+) and (-) signs in the recording pattern represent upward and downward magnetization, respectively.

In this way, the above-mentioned magneto-optical recording device continuously heats a minute portion on the perpendicular magnetization film 3 of the magneto-optical disk 1 to more than one Curie point using the laser beam L8, and moves this heated minute portion to the Curie point. When the area is near the Curie point, the area near the Curie point is magnetized in the direction of the magnetic field modulated in accordance with the recording signal. Then, when the temperature drops, the magnetization is maintained and data is recorded in units of an area smaller than the area of the heated minute part. In this way, even if data is already recorded on the magneto-optical disk 1, new data can be recorded by overwriting.

[Problem to be solved by the invention]

The above-mentioned conventional overridable magneto-optical recording device projects a laser beam LB having a constant optical intensity onto a magneto-optical disk 1, and applies a modulated magnetic field in accordance with a recording signal to the projection position, thereby recording a magneto-optical disk. Override data to 1. The magnetic field applied to the magneto-optical disk 1 is
As shown in Figure 5 (B), from the maximum negative value -H (or maximum positive value +H) to the maximum positive value +H (or maximum negative value -H)
It takes a magnetic field reversal time t1 for the change to occur. Therefore, the magnetic field reversal time is 1. The magnetic field strength gradually increases (or decreases) within the range. A recording pattern 10A is formed on the perpendicular magnetization film 3 as shown in FIG. 5(D).

10B... Before and after each pattern forming the IOE, there is a magnetized region where the magnetic field strength is ambiguous, the so-called noise-up region 11^
.

11B...IIF, which may cause an error during data reproduction. Also, magnetic field reversal time 1. Due to the existence of , there is a problem that the inversion period cannot be increased and high-density recording cannot be performed.

In view of this problem, the present invention eliminates errors during reproduction due to magnetized regions (noise-up regions) where the magnetic field strength is ambiguous.
The purpose of the present invention is to provide a magneto-optical recording device that can record data at high density.

[Means to solve the problem]

The magneto-optical recording device according to the present invention has a single frequency, a pulsed first laser beam of a predetermined intensity, and a predetermined intensity that is emitted only during a data recording period at a time point with a phase difference of 180 degrees with respect to the laser beam. A configuration in which pulsed second laser beams are projected onto the magneto-optical disk, respectively, and an alternating magnetic field of the same frequency that is generated after a predetermined time delay from the time when the first pulsed laser beam is emitted is applied to the magneto-optical disk. Make it.

[Effect]

The first laser beam emitting means emits a pulsed laser beam having a single frequency. The second laser beam emitting means responds to the pulsed laser beam emitted by the first laser beam emitting means.
A pulsed laser beam is emitted only during the period of recording data at a point in time when the phase differs by 0 degrees. The magnetic field applying means generates an alternating magnetic field having the same frequency after a predetermined time delay from the laser beam emitted by the first laser beam emitting means.

As a result, new data is recorded following erasure of recorded data, and a data recording area with ambiguous magnetic field strength does not occur. Furthermore, since erasing and recording are performed almost simultaneously, no sequence is required for erasing.

〔Example〕

The present invention will be described in detail below with reference to drawings showing embodiments thereof.

FIG. 1 is a block diagram showing the main parts of a magneto-optical disk device according to the present invention. A semiconductor laser array 20 is provided on one side of the magneto-optical disk 1, and the first... Laser light LB emitted by the second semiconductor lasers 20a and 20b
,, LBb are both projected onto the magneto-optical disk 1 through the lens 21 and the objective lens 22, and
A focused point is obtained on the perpendicularly magnetized film 3. And laser beam LB.

The laser beam LB is slightly displaced from the laser beam LBb in the moving direction of the magneto-optical disk 1 indicated by the arrow at the laser beam projection position of the magneto-optical disk 1.

The laser beam LBb is used for data recording, and the laser beam LBb is used for erasing data. An electromagnet 7 is disposed on the other side of the magneto-optical disk 1, facing the projection position of the laser beams LB, LB, projected onto the magneto-optical disk.

A coil 7a of this electromagnet 7 is connected to the output side of an electromagnet drive circuit 23 via a coupling capacitor C.

The clock CL input to the clock input terminal 24 is input to the first pulse generation circuit 25, the second pulse generation circuit 26, and the delay circuit 27. The first pulse generation circuit 25 generates a pulse train in synchronization with the falling edge of the clock CK. Further, the second pulse generation circuit 26 generates a pulse train in synchronization with the rising edge of the clock CK. The delay circuit 27 outputs the input clock CK after delaying the time until the temperature of the magneto-optical disk 1 is raised to one Curie point by the laser beam. This delay time varies depending on the disc medium and recording conditions.

The output of the first pulse generation circuit 25 is input to an AND circuit 28 to which the recording signal SR is input. AND circuit 28
The output of is input to the first semiconductor laser drive circuit 29,
The semiconductor laser drive circuit 29 generates a laser drive pulse P having a narrow pulse width in relation to the output of the AND circuit 28 .

The pulse is input to the semiconductor laser 20a. The output of the second pulse generation circuit 26 is input to the second semiconductor laser drive circuit 30.
0 outputs a laser drive pulse P2 having a narrow pulse width in relation to the output of the pulse generation circuit 26, and this pulse is input to the semiconductor laser 20b. The output of the delay circuit 27 is input to an oscillation circuit 31. In synchronization with the input clock CK, the oscillation circuit 31 outputs a single-frequency sine wave signal SS, which has a negative maximum value at the rising edge and a positive maximum value at the falling edge, and inputs it to the electromagnet drive circuit 23. . The output of the electromagnet drive circuit 23 is applied to the coil 7a of the electromagnet 7 via a coupling capacitor C.

Next, the operation of the magneto-optical recording apparatus constructed as described above will be explained with reference to FIG. 2 showing waveforms and recording patterns of each part thereof.

The clock C shown in FIG. 2(A) is connected to the clock input terminal 24.
When Ko is input, the pulse generation circuit 25 outputs the clock C.
Output a pulse in synchronization with the falling edge of K, and send it to A.
Input to ND circuit 28. The pulse generation circuit 26 generates a pulse in synchronization with the rising edge of the clock CK and inputs it to the semiconductor laser drive circuit 30. Thereby, the semiconductor laser drive circuit 30 outputs a laser drive pulse P2, inputs the pulse to the semiconductor laser 20b, and the semiconductor laser 20b emits a laser beam LBb synchronized with the clock CK as shown in FIG. 2 ([1)]. will be output.

On the other hand, the delay circuit 27 receives the clock CK after a predetermined time delay.
The oscillation circuit 31 outputs the clock CK and inputs the clock CK.
outputs a sine wave signal SS synchronized with the clock CK. The sine wave signal SS is input to the electromagnet drive circuit 23, and the output excites the electromagnet 7, so that the electromagnet 7 applies an alternating magnetic field H shown in FIG. 2(C) to the magneto-optical disk 1. As a result, each time the alternating magnetic field H exceeds the required negative value -H, the laser beam LBb is projected, and the recorded data on the magneto-optical disk (2) is reliably erased each time.

In addition, as mentioned above, the alternating magnetic field H is generated by the delay circuit 27.
Therefore, during the period when the sine wave signal is delayed by the clock CK and the temperature of the magneto-optical disk L, which rises with a delay in the timing of laser beam LB and irradiation, exceeds the Curie point, the alternating magnetic field H has a negative required value. =H or higher, and the recorded data can be reliably erased.

Here, when the recording signal S is input to the AND circuit 28, the AND circuit 28 outputs an output when the recording signal SR and the pulse train from the pulse generation circuit 25 are input, and the semiconductor laser drive circuit 29 Enter.

Thereby, the semiconductor laser drive circuit 29 is synchronized with the fall of the clock IJ, outputs a pulse at a timing 16 with a phase difference of 180 degrees from the output of the semiconductor laser drive circuit 30, and inputs it to the semiconductor laser 20a. Then, the semiconductor laser 20a emits a laser beam LB shown in FIG. 2(E) and projects it onto the magneto-optical disk 1. As a result, the laser beam LB is emitted each time the alternating magnetic field H exceeds the positive required value +H during the period when the recording signal S is "1", and data is recorded each time. In this case, as in erasing, the alternating magnetic field lags behind the laser light pulse, so
The laser beam LB causes the alternating magnetic field H to exceed the required positive value +H during the period when the temperature of the magneto-optical disk exceeds the Curie point, thereby ensuring data recording.

In this method, during the period when the temperature of the magneto-optical disk exceeds the Curie point, the alternating magnetic field H exceeds a required positive or negative value, and recording or erasing is performed.

Therefore, the recording pattern does not have a noise-up area where the magnetic field strength is ambiguous as shown in FIG. 2(F), and the data erasing area (-) and the data recording area (+) are clearly distinguished.

Therefore, when reproducing data recorded in this way, the data erase area (-) and data recording area (
+), the level of the reproduced signal shown in FIG. 2(G) will not change suddenly and an error will not occur.

Note that if the oscillation frequency of the oscillation circuit 31 is increased, the result shown in Fig. 2 (
The interval between the data recording area (+) and the data erasing area (-) of the recording pattern shown in F) can be shortened, making high-density recording possible. In this embodiment, the data is put into the recording state with a positive required value of the alternating magnetic field H, but the data may be put into the recording state with a negative required value, and the data can be put into the erased state with a positive required value.

FIG. 3 is a block diagram showing the main parts of a magneto-optical recording device according to another embodiment of the present invention. This magneto-optical recording device uses two semiconductor lasers 4 without using a semiconductor laser array 20.
0.41 is used. Semiconductor laser 4 for data recording
0 is arranged so that the direction of emission of the laser beam LB that it emits is perpendicular to the moving direction of the magneto-optical disk l. Further, a dichroic mirror 42 is disposed at an intermediate position where the lens 21 and the objective lens 22 face each other. The dichroic mirror is configured to transmit light having a semiconductor laser wavelength for recording and reflect light having a semiconductor laser wavelength for erasing. The semiconductor laser 41 for data erasing has a different oscillation wavelength from the semiconductor laser 40 for data recording, and is arranged so that the emission direction of the laser beam LBb that it emits is parallel to the moving direction of the magneto-optical disk 1. The laser beam LBb passes through a lens 43 and is projected onto a dichroic mirror 42. The laser beam LBb reflected by the dichroic mirror 42 is projected onto the magneto-optical disk 1. By using the dichroic mirror in this way, the light utilization efficiency can be increased. The rest of the structure is the same as the magneto-optical recording device shown in FIG.

Even in this case, the laser beam LB emitted by the semiconductor laser 40 is moved slightly in the direction of movement of the magneto-optical disk l at the laser beam projection position of the magneto-optical disk 1 than the laser beam LB of the semiconductor laser 41. It can be placed in a displaced state. It can be operated in the same manner as the magneto-optical recording device shown in FIG. 1, and the same effects can be obtained.

In this embodiment, a magneto-optical recording device has been described, but it goes without saying that the present invention can also be applied to a magneto-optical recording/reproducing device.

〔Effect of the invention〕

As described in detail above, the present invention applies an alternating magnetic field of a single frequency to a magneto-optical disk so that the alternating magnetic field becomes negative (or positive).
A light beam for erasing data is emitted so that the temperature of the magneto-optical disk exceeds the Curie point when the temperature exceeds the required value, and during the period when the recording signal exists, the alternating magnetic field remains at the required value of positive (or negative). Since the light beam for data recording is emitted so that the temperature of the magneto-optical disk exceeds the Curie point when the value exceeds the required value of the alternating magnetic field, the data is erased or recorded and the recorded pattern is A noise-up region where the magnetic field strength is ambiguous does not occur. Further, since data is erased by a light beam emitted at a constant period and recorded immediately after, no data remains unerased, as in the case of erasing by continuous irradiation.

Furthermore, since recording is performed immediately after erasing, there is no need for a sequence for erasing, and the data transfer rate can be increased.

Therefore, according to the present invention, it is possible to provide an excellent overridable magneto-optical recording device that does not cause errors during data reproduction and can record data at high density. Furthermore, since the magnetic field applied to the magneto-optical disk may be an alternating magnetic field with a single frequency, there are other effects such as the electromagnet drive circuit being able to be constructed with a simple circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the main parts of a magneto-optical recording device according to the present invention, FIG. 2 is an explanatory diagram showing waveforms and recording patterns of each part, and FIG. FIG. 4 is a block diagram showing the main parts of a conventional magneto-optical recording apparatus, and FIG. 5 is an explanatory diagram showing waveforms and recording patterns of each part. 1... Magneto-optical disk 7... Electromagnet 20a, 2
0b... Semiconductor laser 25, 26... Pulse generation circuit 27... Delay circuit 28... AND
Circuit 29.30... Semiconductor laser drive circuit 31...
- Oscillation circuit In the figures, the same reference numerals indicate the same or equivalent parts. Agent Masuo Oiwa 2nd condolence illustration 4

Claims (1)

[Claims] (1) A magneto-optical recording device for recording data on a magneto-optical disk, comprising: a first laser beam emitting means for irradiating a magneto-optical disk with a pulsed laser beam having a single frequency and a predetermined intensity; a second laser beam emitting means for irradiating a magneto-optical disk with a pulsed laser beam of a predetermined intensity only during a data recording period at a point in time when the phase differs by 180 degrees from the laser beam; and the first laser beam emitting means. 1. A magneto-optical recording device comprising: magnetic field applying means for generating an alternating magnetic field at the same frequency after a predetermined time delay from the timing at which the pulsed laser beam is emitted.