JPH06333288A - Magnetic recorder - Google Patents

Abstract

PURPOSE:To improve recording density with simple constitution by switching the polarity of modulation magnetic field so that a displacement amount of a magnetic recording medium at the time of switching polarity becomes a spacial linear density limit or below of a light beam irradiation means in the state of continuously irradiating a light beam. CONSTITUTION:A magnetic recording medium 2 is continuously irradiated with a light beam by a laser driving circuit 5, a laser diode 6, a collimate lens 7, a polarizing beam splitter 8 and an objective lens 9 constituting a light beam irradiation means. The polarity of the modulation magnetic field is switched by a magnetic field modulation head 13 and a magnetic field head driving circuit 17 constituting a revision magnetic field impression means so that the displacement amount (x) of the recording medium 2 corresponding to the period (t) when the modulation magnetic field falls from first magnetic flux density +< to second magnetic field flux -< and the period (t) when the modulation magnetic field rises from the second magnetic flux density -< to the first magnetic flux density becomes the spacial linear density limit or below of the optical irradiation means. Thus, a timing control circuit required for intermittently irradiating the optical beam is eliminated, and the whole constitution is simplified, and the deterioration in the S/N of reproduced signal is prevented.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problem to be Solved by the Invention Means for Solving the Problem (FIGS. 1 to 3) Action (FIGS. 1 to 3) Example (1) Configuration of Example (FIG. 1 to FIG. 1) (FIG. 3) (2) Effect of the embodiment (3) Other embodiment Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording apparatus, and is suitable for application to a magneto-optical disk apparatus for recording desired data by applying, for example, a thermomagnetic recording method.

[0003]

2. Description of the Related Art Conventionally, in a magneto-optical disk device of this type, desired data can be recorded by applying a thermomagnetic recording method. That is, in this type of magneto-optical disk device, the magneto-optical disk is intermittently irradiated with a light beam, and the pulse emission recording method is applied to sequentially locally heat the magneto-optical disk.

In this state, in the magneto-optical disk device, a modulating magnetic field is applied to the irradiation position of this light beam so as to penetrate the magneto-optical disk. At this time, in the magneto-optical disk device, the polarity of the modulation magnetic field is switched according to the logic level of the data to be recorded, and thereby the desired data is thermomagnetically recorded.

At this time, in the magneto-optical disk device,
By applying a modulation magnetic field so as to penetrate the magneto-optical disk, a vertically magnetized region (that is, consisting of pits) can be formed at the irradiation position in this light beam, and by this switching the polarity of the modulation magnetic field The data can be sequentially recorded.

[0006]

By the way, the magneto-optical disk device of this type is characterized in that the conditions of thermo-magnetic recording are changed depending on the ambient temperature and the peripheral speed of the magneto-optical disk. Moreover, it is necessary to finely control the timing of switching the polarity of the modulation magnetic field. Therefore, the conventional magneto-optical disk device is provided with a timing control circuit corresponding to a delay circuit, and controls the timing control circuit to control the irradiation period of the light beam and the timing of switching the polarity of the modulation magnetic field with respect to the light beam. It was done like this. Therefore, in the conventional magneto-optical disk device, there is a problem that the structure becomes complicated accordingly.

Further, the control of the irradiation period and the timing control of the modulation magnetic field require high speed and high accuracy as the recording density of the magneto-optical disk is increased,
The conventional magneto-optical disk device has a problem that the recording density cannot be easily improved.

In practice, in this timing control circuit, when the polarity of the modulating magnetic field is switched at a cycle of 20 to 50 [nsec], it is necessary to switch the delay time with a resolution of about 0.2 [nsec]. There is a feature that the configuration is complicated even by itself.

The present invention has been made in consideration of the above points, and an object of the present invention is to propose a magnetic recording apparatus which has a simple structure and can easily improve the recording density as compared with the conventional one.

[0010]

In order to solve such a problem, according to the present invention, in a magnetic recording apparatus 1 for irradiating a magnetic beam on a magnetic recording medium 2 to thermomagnetically record desired recording data D2, Light beam irradiation means 5, 6, 7, 8, 9 for irradiating the magnetic recording medium 2 and modulation magnetic field application means 13 for applying a modulation magnetic field φ whose polarity is switched according to the recording data D2 to the irradiation position of the light beam. , 17, the light beam irradiation means 5, 6, 7, 8, 9 continuously irradiate the light beam, and the modulation magnetic field φ changes the SN of the reproduction signal RF.
A first magnetic field having a ratio of saturation equal to or higher than a first magnetic flux density + ψ,
The modulation magnetic field applying means 13 and 17 are formed by switching the polarity between a second magnetic field having a polarity opposite to that of the first magnetic field and having a SN ratio of the reproduced signal saturated and having a second magnetic flux density of −ψ or less. A magnetic recording medium corresponding to a period t during which the modulating magnetic field falls from the first magnetic flux density + ψ to the second magnetic flux density −ψ and a period t during which the modulating magnetic field rises from the second magnetic flux density −ψ to the first magnetic flux density + ψ. The displacement amount x of 2 is the light beam irradiation means 5, 6,
The polarity of the modulation magnetic field φ is switched so that the spatial linear density limit of 7, 8 or 9 is not more than the limit.

[0011]

[Operation] The light beam is continuously emitted, and the modulation magnetic field ψ is changed to the first
Of the magnetic recording medium 2 corresponding to the period t from which the magnetic flux density + ψ falls to the second magnetic flux density −ψ and the period t where the modulation magnetic field rises from the second magnetic flux density −ψ to the first magnetic flux density + ψ.
By changing the polarity of the modulation magnetic field φ so that the displacement amount x of the light beam irradiation means 5, 6, 7, 8, 9 is equal to or less than the spatial linear density limit, deterioration of the SN ratio can be effectively avoided. The reproduction signal RF can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) Configuration of the Embodiment In FIG. 1, reference numeral 1 denotes a magneto-optical disk device as a whole, which thermomagnetically records desired data on the magneto-optical disk 2.

That is, the magneto-optical disk 2 is fixed to the rotary shaft of the spindle motor 4 by the hub 3, and the spindle motor 4 is driven by the hub 3 to rotate at a constant angular velocity. In this state, the magneto-optical disk device 1
The laser drive circuit 5 drives the laser diode 6 to continuously emit a light beam from the laser diode 6 at the time of recording, while at the time of reproduction, the light amount is reduced to continuously emit the light beam. To eject.

The magneto-optical disk device 1 converts this light beam into parallel rays by the collimator lens 7, transmits the deflected beam splitter 8 and guides it to the objective lens 9, and the objective lens 9 directs it to the magneto-optical disk 2. Focus the light beam. Further, the magneto-optical disk device 1 includes a magneto-optical disk 2
The reflected light obtained from the above is received by the objective lens 9 and guided to the deflected beam splitter 8, and the reflected light of the deflected beam splitter 8 is condensed by the condenser lens 10 on the photodiode 11.

As a result, the magneto-optical disk device 1 detects the reproduction signal RF by utilizing the Kerr effect at the time of reproduction on the basis of this reflected light, and at the same time, at the time of recording / reproduction, the focus error signal and the tracking error signal. The objective lens 9 can be moved vertically and horizontally based on the focus error signal and the tracking error signal to perform focus control and tracking control.

Further, the magneto-optical disk device 1 is
The magnetic field modulation head 13 is driven so that a modulation magnetic field can be applied to the irradiation position of this light beam, whereby the technique of thermomagnetic recording can be applied to record desired data. That is, the magneto-optical disk device 1 responds to a control command output from the host computer, and controls the entire operation by the recording control circuit 14 of the micro computer configuration, whereby the modulation circuit 15, at the time of recording,
The magnetic field head drive circuit 17 is activated.

The modulation circuit 15 inputs, together with the data clock DCK, the recording data D1 synchronized with the data clock DCK from the host computer in the form of binary serial data, and codes the recording data to record the recording data. Convert to D2. The clock generation circuit 18 is configured to divide a reference signal generated by driving the crystal unit X to generate a predetermined clock CK. In the magneto-optical disk device 1, the clock CK is used as a reference. It is designed to work.

As a result, the magnetic field head drive circuit 17 causes the magnetic field modulation head 1 to correspond to the logical level of the recording data D2.
3 is driven, thereby forming a modulation magnetic field whose polarity changes according to the output signal of the modulation circuit 15. As a result, in the magneto-optical disk device 1, the polarity of the modulation magnetic field is switched in the state where the light beam is continuously irradiated, and thereby the recording data D2 is thermomagnetically recorded on the magneto-optical disk 2.

Thus, in the magneto-optical disk device 1, since the light beam is continuously irradiated, the timing control circuit necessary for intermittently irradiating the light beam can be omitted, and the entire structure is simplified accordingly. can do.

By the way, when the desired data is thermomagnetically recorded by continuously irradiating the light beam in this manner, the SN of the reproduction signal may be deteriorated. That is, as shown in FIG. 3, in order to prevent deterioration of the SN ratio in thermomagnetic recording and prevent deterioration of the bit error rate, at the time of reproduction, the magnetic flux density at which the SN ratio of the reproduced signal saturates + ψ or more. It is necessary to raise the modulation magnetic field φ and further lower the modulation magnetic field φ to the magnetic flux density −ψ or less (FIG. 2 (A)).

On the other hand, when the magnetic field modulation head 13 composed of an inductance element is driven to switch the polarity of the modulation magnetic field, it is difficult to rapidly switch the modulation magnetic field φ. In this case, the modulation magnetic field φ has a magnetic flux density of + ψ and −
When the period T held during ψ becomes longer, an unsaturated region α corresponding to this period T is formed in the magneto-optical disk 2 (FIG. 2 (B)), and in the magneto-optical disk device 1, this unsaturated region α is formed. The SN ratio of the reproduced signal deteriorates in the unsaturated region α,
Eventually, the SN ratio of the entire reproduction signal RF deteriorates.

However, this period T is shortened and this period T
If the displacement x of the magneto-optical disk 2 (that is, the displacement of the period T defined by the peripheral velocity of the light beam irradiation position) x corresponding to the above is kept below the spatial linear density limit of the optical system, the light beam is intermittently It is possible to obtain almost the same reproduction result as in the case of irradiating (FIG. 2 (C)). That is, in this type of magneto-optical disk device 1, the light beam can be converged only to about 1.4 [μm] due to the resolution of the optical system, and therefore the polarity changes at intervals of 0.5 [μm] or less in the reproducing system. With respect to the perpendicularly magnetized region, the switching of the polarities cannot be detected.

As a result, if the displacement amount x of the magneto-optical disk 2 corresponding to this period T is kept below the spatial linear density limit of the optical system, that is, 0.5 [μm], the reproduction signal RF
It is possible to effectively avoid the deterioration of the SN ratio. Therefore, in the magneto-optical disk device 1, desired recording data can be recorded by increasing the recording density accordingly.

Incidentally, according to the experimental results, when the displacement amount x of the magneto-optical disk corresponding to the unsaturated region α is plotted on the horizontal axis in FIG. 3, when the light beam is intermittently irradiated as in the conventional case. It can be confirmed that there is no difference in the signal level of the reproduction signal when the displacement amount x becomes 0.5 [μm] or less in CT when the light beam is continuously irradiated as compared with PT.

For this reason, in this embodiment, the magnetic field modulation head 13 is formed of a flying type magnetic head, which allows the magnetic field modulation head 13 to be arranged close to the magneto-optical disk 2 and to apply a necessary modulation magnetic field with a small magnetic force. It is done like this. Further, the magnetic field modulation head 13 is selected to have a small inductance (0.5 [μH] in this embodiment), whereby the polarity of the modulation magnetic field can be switched in a short time by following the change in the logic level of the recording data D2. It is done like this.

On the other hand, in the reproduction system, the reproduction signal RF output from the photodiode 11 is amplified by the amplifier circuit 1.
After being amplified by 9, the signal is input to the signal processing circuit 20. The signal processing circuit 20 converts the reproduction signal RF into a digital value by a built-in analog digital conversion circuit with the reproduction signal RF as a reference, and then obtains a comparison result with a predetermined reference value to sequentially input the signals. The reproduced signal RF is reproduced.

As a result, the magneto-optical disk device 1 demodulates the recording data, and the demodulation circuit 21 converts the demodulated recording data into the original format, contrary to the modulation circuit 15. As a result, the magneto-optical disc device 1 outputs the demodulated reproduction data D3 to the host computer together with the reproduction clock DCK1 in response to the request from the host computer.

(2) Effects of the Embodiments According to the above structure, the length of the unsaturated region on the magneto-optical disk becomes the spatial linear density limit of 0.5 [μm] in the state where the light beam is continuously irradiated. By switching the polarity of the modulation magnetic field so that the distance becomes the following short distance and thermomagnetically recording the recording data with this modulation magnetic field, it is possible to effectively avoid the deterioration of the SN ratio even if the timing control circuit is omitted. With a simple structure, the recording density can be improved more easily than in the past.

(3) Other Embodiments In the above-described embodiments, the case where the magneto-optical disk is driven under the condition of constant angular velocity has been described, but the present invention is not limited to this, and the optical condition under constant linear velocity is used. It can also be applied when driving a magnetic disk.

Further, in the above-mentioned embodiments, the case where the present invention is applied to the magneto-optical disk device has been described.
The present invention is not limited to this, and can be widely applied to a case where desired data is recorded on various magnetic recording media by applying a thermomagnetic recording method.

[0032]

As described above, according to the present invention, the displacement amount of the magnetic recording medium at the time of polarity switching becomes less than the spatial linear density limit of the light beam irradiation means in the state where the light beam is continuously irradiated. As described above, by switching the polarity of the modulation magnetic field, the S
It is possible to obtain a reproduction signal while effectively avoiding the deterioration of the N ratio, and thereby obtain a magneto-optical disk device that can improve the recording density with a simple configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing a magneto-optical disk device according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram for explaining the operation.

FIG. 3 is a characteristic curve diagram showing the experimental results.

[Explanation of symbols]

1 ... Magneto-optical disk device, 2 ... Magneto-optical disk, 6
...... Laser diode, 13 ...... Magnetic field modulation head, 1
5 ... Modulation circuit, 17 ... Magnetic field head drive circuit, 20 ...
... signal processing circuit, 21 ... demodulation circuit.

Claims (1)

[Claims] 1. A magnetic recording apparatus for irradiating a magnetic beam onto a magnetic recording medium to thermo-magnetically record desired recording data, and a light beam irradiating means for irradiating the magnetic beam onto the magnetic recording medium; Modulation light field applying means for applying a modulation magnetic field whose polarity is switched according to the recorded data to the irradiation position, and the light beam irradiation means continuously irradiates the light beam, and the modulation magnetic field is a reproduction signal. The first magnetic flux density equal to or higher than the first magnetic flux density at which the SN ratio of
And a second magnetic field having a polarity opposite to that of the first magnetic field and having a second magnetic flux density equal to or less than the second magnetic flux density at which the SN ratio of the reproduction signal is saturated, and the modulation magnetic field applying unit is formed. Is the magnetic recording corresponding to a period during which the modulating magnetic field falls from the first magnetic flux density to the second magnetic flux density and a period during which the modulating magnetic field rises from the second magnetic flux density to the first magnetic flux density. A magnetic recording apparatus, wherein the polarity of the modulating magnetic field is switched so that the displacement amount of the medium becomes equal to or less than the spatial linear density limit of the light beam irradiating means.