JPH03214445A - Magneto-optical recorder - Google Patents

Abstract

PURPOSE:To obtain a regenerative signal having faithfully reproduced the process with time of a recording signal from a recording bit by making the timing and/or irradiating time and irradiating intensity at the irradiating time of a 1st laser for recording a recording signal different from that at the other irradiating time after the recording signal is changed. CONSTITUTION:Laser light irradiating timing is decided for a modulation magnetic field to be generated by a electromagnet 10 by a phase adjusting circuit 14, and the timing is made constant. Then, laser light irradiating time is made constant by a pulse width adjusting circuit 13, and when the recording signal (b) is changed from '0' to '1', the 1st irradiating time is made shorter than the following irradiating time, and longer in the reverse case changing the signal from '1' to '0'. Laser light output intensity is decided by a laser power control circuit 12, and the 1st output intensity when the recording signal is changed from '0' to '1' is made weaker than the following output intensity, and stronger in the reverse case. Thus, a recording signal change with time is faithfully recorded as a length change of a recording bit length.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an overwritable device that performs recording by reversing the applied magnetic field at a single frequency and irradiating pulsed laser light in synchronization with the applied magnetic field. The present invention relates to a magneto-optical recording device.

[Prior Art] Conventionally, as one of the magneto-optical recording devices that enable information to be rewritten by overwriting, a magnetic field applied at a channel clock or a single frequency that is a multiple of the channel clock used to modulate the data to be recorded is resonant. A magneto-optical recording device has been considered that performs recording by modulating a magnetic field using a circuit and emitting pulsed laser light in synchronization with the modulated magnetic field.

FIG. 3 is a diagram showing the configuration of an example of such a conventional device.

In FIG. 3, 1 indicates a magneto-optical disk, and in this example, the magneto-optical disk 1 is constructed by coating a perpendicular magnetization film 3 on a plastic substrate 2, and further coating a protective film 4. It is configured to rotate around a central axis of 0-0°.

Further, 8 indicates an optical head that irradiates the perpendicular magnetization 1]u3 of the magneto-optical disk 1 with a laser beam. This optical head 8 is composed of a semiconductor laser 5, a condensing lens 6, and a condensing lens driving actuator 7 as main components, and has the function of always focusing the laser beam on the perpendicular magnetization film 3, and It is configured to be movable in the radial direction of the magnetic disk 1.

An electromagnet 10 is arranged to face the optical head 8 with respect to the magneto-optical disk 1 and applies a magnetic field to the perpendicular magnetization film 3. This electromagnet 10 is arranged so that the generated magnetic field is maximized at the portion where recording pits are formed. Further, this electromagnet 10 is configured to move in conjunction with the optical head 8. A current is supplied to this electromagnet 10 by a coil 9 connected to a resonant magnetic head driver 11 at a single frequency of the channel clock of the modulation method of the data to be recorded or a multiple thereof. When the magnetic field strength necessary for recording is ±H, the magnetic field is configured to generate a magnetic field of ±H or more as a peak value. The resonant magnetic head driver 11 is configured with a capacitor l7 as a main element, and is driven at a frequency input from an oscillator 16.

Laser light irradiated from the optical head 8 is irradiated in a pulsed manner with respect to a modulated magnetic field generated by an electromagnet 10 by an optical modulation circuit 15 that determines the phase and pulse width at a desired position. The optical modulation circuit 15 includes a phase adjustment circuit 14 that determines the timing of irradiating the modulated magnetic field with laser light;
and a pulse width modulation circuit 13 that determines the time to irradiate the laser beam.

The phase adjustment circuit l4 receives a channel clock output from an oscillator 16 that drives the resonant magnetic head driver 1l,
Driven by a clock of the same frequency synchronized with a single frequency or a frequency that is a multiple thereof, and a recording signal,
The timing of irradiating the generated magnetic field with laser light is determined.

Further, the pulse width adjustment circuit 13 has a function of determining a desired laser beam irradiation time based on the laser beam irradiation timing signal determined by the phase adjustment circuit 14.

In the magneto-optical recording apparatus configured in this manner, consider a case where an NRZ signal is supplied as a recording signal (b) using a modulation method such as 2.7 modulation or EFM modulation, as shown in FIG. 4, for example. At this time, the clock supplied to the phase adjustment circuit 14 is as shown in clock (a). In this example, the frequency is the same as the channel clock. Moreover, the change in the magnetic field applied on the perpendicular magnetization film 3 is the modulation magnetic field (c)
At the highest point of the modulated magnetic field strength, a value sufficiently exceeding the magnetic field strength ±H required for recording is supplied.

When input is given at such timing, the laser beam irradiation timing is such that if the recording signal is ゜'1゛, the laser beam is irradiated at the time when a magnetic field with a magnetic field strength of "+H" is applied, and the recording signal is In the case of "゜゜O", the laser beam will be irradiated at the time when the magnetic field of -H゜゜ is applied.Therefore, the pulsed output of the laser beam will be generated by the modulation magnetic field (c
), it becomes like (d). However, detailed timing such as the time required for the temperature of the perpendicularly magnetized film 3 to rise after laser beam irradiation is not considered here.

When the laser beam is irradiated at such timing, the moving speed of the magneto-optical disk 1 is determined so that the pit shape formed by one laser beam irradiation is sufficiently large with respect to the laser beam irradiation pulse interval. Therefore, the pattern of recorded pits formed is as shown in recording pattern (e). Here, the white and hatched portions of the recording pattern (e) indicate a state in which the perpendicular magnetization film 3 is magnetized in directions corresponding to "1°" and "0°" of the recording signal (b), respectively.

In this way, the magneto-optical recording device of this example selectively irradiates a pulse-modulated laser beam onto a magnetic field modulated at a single frequency, depending on the recording signal. Since the perpendicular magnetization film 3 is magnetized in this direction, new information can be recorded by overwriting regardless of what information is recorded on the perpendicular magnetization film 3 of the magneto-optical disk 1.

[Problems to be Solved by the Invention] However, in the conventional example described above, as shown in FIG. There is a difference in laser irradiation timing with respect to the change in recording signal (b) when changing from ゜゜ to "1゜" and when changing from ゛1゛ to "0". For example, assuming that the modulation of the magnetic field has the same frequency as the channel clock of the code modulation method, and if one period of the channel clock is IT, then the recording signal change when the recording signal (b) changes from "O゛゜" to "1" Based on the laser irradiation timing for , the laser beam irradiation timing will be delayed by 0.5T when the recording signal (b) changes from 1° to 0. Therefore, the recording pattern will be different from the conventional one shown in FIG. In the example, when "1" is recorded, it is recorded 0.5T longer, and when "゜゛0" is recorded, it is recorded 0.5T shorter, and the reproduced signal obtained from that recording pattern (
f) had the disadvantage that it could not faithfully reproduce the recorded signal (b).

[Means and Effects for Solving the Problems] The present invention, as a means for solving the above-mentioned problems, includes applying a magnetic field modulated at a constant period to a magneto-optical recording medium, and transmitting a light beam to a recording signal and the above. In a magneto-optical recording device that performs recording by irradiating in a pulsed manner according to the period of an applied magnetic field, the timing of the first laser beam irradiation for recording the recording signal after the recording signal changes; and/or means for irradiating the irradiation time and/or irradiation intensity differently with respect to other irradiation times after the change, and recording pits generated due to the periodicity of the applied magnetic field when the recording signal changes. The present invention provides a magneto-optical recording device characterized by controlling changes in length.

Further, in the first laser beam irradiation after the recording signal changes to a recording signal corresponding to a longer recording pit length, the irradiation timing is delayed with respect to other irradiation after the change. and/or the irradiation time is shortened and/or the irradiation intensity is decreased, and the recording signal is changed to a recording signal corresponding to a shorter recording pit length. During light irradiation, the method is characterized by having means for advancing the irradiation timing, lengthening the irradiation time, and/or increasing the irradiation intensity with respect to other irradiation times after the change. , attempts to solve the above problem by using a magneto-optical recording device.

According to the present invention, with respect to the first laser beam irradiation after the recording signal transitions, there is provided a means for increasing or retarding the irradiation timing of the laser beam with respect to the modulated magnetic field according to a change in the recording signal, and a means for adjusting the laser beam irradiation time. By providing all, selectively, or only a means for lengthening or shortening the laser beam intensity and a means for increasing or weakening the laser beam intensity, it is possible to eliminate the problem caused by the timing difference between the recording signal and the modulated magnetic field. It is possible to correct the deviation of the recording pattern, and to create a recording pattern that is faithful to the recording signal. Moreover, this makes it possible to obtain a reproduced signal that faithfully reproduces the recorded signal.

[Embodiment] FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. In the figure, 1 indicates a magneto-optical disk, and in this example, the magneto-optical disk 1 is attached to a plastic substrate 2. It is constructed by depositing a perpendicular magnetization film 3 and a protective film 4, and is configured to rotate about a central axis 0-0''.

Further, 8 represents an optical head for irradiating the perpendicular magnetization film 3 of the magneto-optical disk 1 with laser light and raising the temperature of the perpendicular magnetization film 3 at the irradiated area to a temperature near or above the Curie point. .

The optical head 8 is composed of a semiconductor laser 5, a condensing lens 6, and a condensing lens driving actuator 7 as main components, so that the laser beam is always focused on the recording/reproducing position of the perpendicularly magnetized film 3. It has autofocus and autotracking functions and is configured to be movable in the radial direction of the magneto-optical disk 1.

An electromagnet 10 is arranged to face the optical head 8 with respect to the magneto-optical disk 1, and applies a recording magnetic field to the perpendicularly magnetized film 3. This electromagnet 10 is arranged so that the generated magnetic field is maximized at a portion where a recording pit is formed.

Further, this electromagnet 10 is configured to move in conjunction with the optical head 8 for the above-mentioned reason. Also, this electromagnet 1o
In this case, a current is supplied by the coil 9 connected to the resonant magnetic head driver 11 at a single frequency of the channel clock of the modulation method of the data to be recorded or a multiple thereof, and as a result, the current is supplied on the perpendicularly magnetized film 3 at that frequency. It is configured to generate a magnetic field having a peak value equal to or greater than the magnetic field strength ±H required for recording. The resonant magnetic head driver 11 is
The main component is a capacitor 17, and the oscillator 1
It is driven by a signal with a single frequency that is a channel clock manually input from 6 or a multiple thereof.

The irradiation timing, irradiation time, and laser beam intensity of the laser beam irradiated from the optical head 8 with respect to the modulated magnetic field generated by the electromagnet 10 are determined by the optical modulation circuit 15. The optical modulation circuit 15 includes a phase adjustment circuit 14, a pulse width adjustment circuit 13, and a laser (LD) power control circuit 12.

Regarding the first laser beam irradiation after the recording signal transitions, we will explain how to speed up or slow down the laser beam irradiation timing, lengthen or shorten the laser beam irradiation time, and increase the laser beam intensity. An embodiment in which all the means for increasing or weakening are provided will be described.

The phase adjustment circuit 14 determines the laser beam irradiation timing for the modulated magnetic field generated by the electromagnet 10. In this example, when the recording signal changes from "0" to "1" (when the recording signal changes to a recording signal corresponding to a longer recording pit length), the first laser beam irradiation timing for the modulated magnetic field is set as follows. In other words, when the recording signal changes from "1' to "0" (when the recording signal changes to a recording signal corresponding to a shorter recording pit length) than the laser beam irradiation timing that follows, If the timing of laser beam irradiation is delayed by 172 cycles of the conventional modulated magnetic field period due to the periodicity of the modulated magnetic field compared to when the signal changes from "0" to ゜゛1゜゛, the first laser beam irradiation timing for the modulated magnetic field may be changed. It has a function of delaying the next laser beam irradiation timing.The phase adjustment circuit 14 also has a function of keeping the laser beam irradiation timing constant with respect to the modulated magnetic field in other cases.

The pulse width adjustment circuit 13 determines the laser beam irradiation time. In this example, when the recording signal changes from ゛1゜゛, the first laser beam irradiation time is made shorter than the next laser beam irradiation time, and conversely, when the recording signal changes from ゛゛1゜゛ to ゛0゛. ”, that is, compared to the case where the recording signal changes from “゛゜○゜゜” to “1”, due to the periodicity of the modulated magnetic field, the period of the conventional modulated magnetic field is 1/2
It has a function of making the laser beam irradiation time longer than the next laser beam irradiation time when the periodic laser beam irradiation timing is delayed. The pulse width adjustment circuit 13 also has the function of keeping the laser beam irradiation time constant in other cases.

The laser power control circuit 12 determines the laser light output intensity. In this example, the recording signal is “0”.
The first laser light output intensity when changing from "1" to "1" is then "weaker than the laser light output intensity", and conversely, when the recording signal changes from "1" to "o" That is, if the laser beam irradiation timing is delayed by 172 cycles of the conventional modulated magnetic field period due to the periodicity of the modulated magnetic field compared to the case where the recording signal changes from ゛0'' to ゜゛1゜, the laser beam output intensity is changed to It has the function of increasing the intensity of the laser light output that follows. Further, the laser power control circuit 12 has a function of keeping the laser light output intensity constant in other cases.

Figure 2 shows that in the above configuration, the recording signal is as shown in Figure 2(b).
FIG. 3 is a diagram showing a timing chart of each signal and recording pattern when input as shown in FIG.

In FIG. 2, the magnetic field applied to the magneto-optical disk 1 is as shown in (C). In this state, the output of the phase adjustment circuit 14 is as shown in (d). When the recording signal (b) changes from "O" to "1'", the laser irradiation timing (a) is the next one. 《If the output is delayed compared to the laser irradiation timing (2), and conversely the recording signal changes from “1゜゛” to “0”, the first laser irradiation timing (c) after the recording signal change is output earlier than the next laser irradiation timing (2).

After the laser irradiation timing is determined by the phase adjustment circuit 14, it is input to the pulse width adjustment circuit 13, and the laser irradiation time is determined as in the pulse width adjustment circuit output (e). Here, when the recording signal changes from "0°" to "1", the first laser irradiation time is set shorter than the next laser irradiation time, and conversely, the recording signal changes from "1" to "0".
The first laser beam irradiation time when changing to `` is set to be longer than the next laser beam irradiation time.

After setting the laser beam irradiation time, the laser beam intensity is finally determined. Similarly to the laser light irradiation timing and laser light irradiation time, the laser light intensity is changed at the first point after the recording signal changes. In other words, the recording signal is “0”.
The laser light output intensity at the timing (a) when changing from ゛ to ゛1 is set to be weaker than the laser light output intensity at the next < (mouth), and conversely, the recording signal changes from ゜゜1 to 0 The laser light output intensity at the timing (c) of changing to ``is set to be stronger than the laser light output intensity at the next slope.

As a result of the above, the laser light output becomes as shown in (f), and the recorded pit pattern recorded in this state schematically becomes as shown in the recorded pattern (g).

Here, the white and hatched portions of the recording pattern (g) indicate the state in which the perpendicular magnetization film 3 is magnetized in directions corresponding to "1" and "0" of the recording signal, respectively.

The reproduced signal obtained from such a recording pattern (g) is as shown in FIG. 2(h), and is a faithful reproduction of the recording signal (b).

In the above embodiment, all three means are provided for the first laser beam irradiation after the recording signal changes: a means for controlling the laser beam irradiation timing, a means for controlling the laser beam irradiation time, and a means for controlling the laser beam intensity. However, not limited to this, 2
Even if one or more means is selected and operated, the same effect can be obtained depending on the characteristics of the recording medium, that is, the perpendicularly magnetized film.

[Effects of the Invention] As explained above, in a magnetic field modulation magneto-optical recording device that modulates a magnetic field with a single frequency and irradiates laser light in a pulsed manner by selecting it according to a distribution signal, the recording signal changes after the recording signal changes. the first of
Regarding the second laser beam irradiation, a means for changing the laser beam irradiation timing, a means for changing the laser beam irradiation time, and a means for changing the laser beam intensity are provided, and each means is applied to the next laser beam irradiation. By doing so, it is possible to control the change in the recording pit length due to the timing difference between the recording signal and the modulated magnetic field, and it is possible to faithfully record the temporal change in the recording signal as a change in the recording pit length. In other words, there is an effect that a reproduced signal that faithfully reproduces the change over time of the recorded signal can be obtained from the recorded pits.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the magneto-optical recording device of the present invention. FIG. 2 is a timing chart explaining the operation of the magneto-optical recording method of the present invention. FIG. 3 is a configuration diagram of a conventional magneto-optical recording device. FIG. 4 is a timing chart explaining the operation of the conventional magneto-optical recording method. 1: magneto-optical disk, 2: plastic substrate, 3: perpendicular magnetization film, 4: protective film, 5: semiconductor laser, 6: condensing lens, 7: actuator, 8: optical head, 9: coil,
lO2 electromagnet, 1l: resonant magnetic head driver, 12
．． Laser power control circuit, 13: Pulse width adjustment circuit, 14: Phase adjustment circuit, 15: Optical modulation circuit, 16:
Oscillator 17: Capacitor

Claims (2)

[Claims] (1) In a magneto-optical recording device that performs recording by applying a magnetic field modulated at a constant cycle to a magneto-optical recording medium, and irradiating a light beam in a pulsed manner according to a recording signal and the cycle of the applied magnetic field, After the recording signal changes, the timing and/or irradiation time and/or irradiation intensity of the first laser beam irradiation for recording the recording signal are different from those of other irradiation times after the change. What is claimed is: 1. A magneto-optical recording device, comprising: means for irradiating the recording signal in a manner similar to the above, and controlling a change in recording pit length caused by the periodicity of the applied magnetic field when the recording signal changes. (2) At the time of the first laser beam irradiation after the recording signal changes to a recording signal corresponding to a longer recording pit length, the irradiation timing is changed with respect to the other irradiation times after the change. and/or the irradiation time is shortened, and/or the irradiation intensity is decreased, and the recording signal is changed to a recording signal corresponding to a shorter recording pit length. At the time of light irradiation, the irradiation timing is made earlier and/or the irradiation time is made longer than at other irradiation times after the change, and/
2. The magneto-optical recording apparatus according to claim 1, further comprising means for increasing said irradiation intensity.