JPH02214049A - Magneto-optical recorder - Google Patents

Abstract

PURPOSE:To dissolve the deterioration of a recording medium and a regenerative signal in quality due to generated heat by impressing a magnetic field for recording and erasing information using a permanent magnet and erasing the information with a light beam to be emitted in a pulse pattern. CONSTITUTION:The magnetic field for recording and erasing information is impressed by using the permanent magnet for impressing a fixed magnetic field in order to impress the magnetic field in the direction of recording a magneto-optical recording medium 109. Thus, since the permanent magnet 116 is used for a magnetic field impressing means for recording and erasing information to carry out the erasing of information by emitting the light beam in a pulse state from a laser diode 102 and the recording of information after modulation with a lower frequency than the pulse-like light beam emitted at the time of erasing, no heat is generated to obtain the impressing magnetic field, and hence the deterioration of the recording medium 109 and the regenerative signal in quality can be dissolved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a magneto-optical recording device that obtains information using a reflected light beam from a magneto-optical recording medium.

[Prior Art] Conventionally, as a magneto-optical recording device that obtains information using a light beam from a magneto-optical recording medium, there is a reflection type method (hereinafter referred to as a "car type") that utilizes the Kerr effect.

FIG. 2 is a schematic diagram of the main parts of a single-type magneto-optical recording device. A laser beam emitted from a laser diode 202 is bounced up, its optical path is bent by a prism 210, and the beam is focused onto a magneto-optical recording medium 209 by an objective lens 203. The reflected light from the magneto-optical recording medium 209 passes through the objective lens 203. The beam enters the beam splitter 212. Here, it is divided into servo beam and signal beam. The servo beam enters the beam splitter 215 and enters the track servo error detection photodiode 207 and the focus error detection photodiode 208. Note that the track servo uses the push-pull method, and the focus servo uses the astigmatism method. On the other hand, the signal beam enters the λ/2 plate 214, the plane of polarization is rotated by 45 degrees, enters the photodiodes 205 and 206, and the signal is detected from the operation of the output. When recording information, a current is applied to the applied magnetic field coil 216 while applying a magnetic field and a laser beam is irradiated to erase the area to be recorded.Then, the current in the coil is reversed to change the direction of the magnetic field to the recording direction, and then the information is erased. Record the recorded area.

[Problems to be Solved by the Invention] However, the above-mentioned conventional technology generates heat because it is necessary to flow a large current through the coil to obtain the applied magnetic field necessary for recording and erasing information. The heat generated increases the disk temperature, which adversely affects the quality of reproduced signals and the life of the magneto-optical recording medium. Furthermore, there is a problem that the range of application of the device is narrowed due to the increased power consumption.

In addition, as a method of adding an override function, it is possible to combine the so-called magnetic field modulation method in which the direction of the magnetic field generated by the coil is changed according to the data, but this method causes heat generation and power consumption due to the large current flowing through the coil. Because the magnetic field is large, the direction of the magnetic field cannot be changed at high speed, which limits the data transfer speed. Also, Jpn, Appl, Phys.

Vol, 26.5upp1.26-4, p149(19
87) and the Institute of Electronics, Information and Communication Engineers Research Report MR-61, some magnetic field applying means have a floating head structure similar to the head of a fixed magnetic disk, but information can be recorded only on one side of the disk. The per unit capacity does not increase. Furthermore, since the flying height of the flying head is several micrometers, there is a problem with reliability.

The present invention has been made to solve these problems, and its purpose is to provide a single-type magneto-optical recording device that can be overridden and which does not cause deterioration in signal quality due to temperature rise of reproduced signals. There is a particular thing.

[Means for Solving the Problems] The magneto-optical recording device of the present invention includes a light beam generating means, a means for modulating the light beam, an optical means for focusing the light beam on a magneto-optical recording medium, and a magneto-optical recording medium. Tracking and focusing means for causing a light spot to follow an information recording column on the optical recording medium, and means for detecting the reflected beam light from the magneto-optical recording medium to detect information stored on the magneto-optical recording medium. , a magneto-optical recording device comprising means for detecting servo signals for tracking and focusing, and magnetic field generating means for recording and erasing information, wherein the magnetic field generating means is a permanent magnet, and the direction of the magnetic field is It is arranged so that the direction is the same during erasing as in the information recording area, and the information is erased by emitting the light beam in a pulsed manner, and the information is modulated at a lower frequency than the pulsed emission of the light beam during erasing. It is characterized by recording.

[Function] According to the above configuration of the present invention, since the magnetic field for recording and erasing information is applied using a permanent magnet, there is no problem of heat generation. This eliminates the deterioration of the reproduced signal due to the rise in , and enables high-speed override.

[Example] The present invention will be described in detail below using examples.

FIG. 1 is a schematic diagram showing the configuration of a magneto-optical recording device according to an embodiment of the present invention. A laser beam emitted from a laser diode 102 is deflected by a lifting prism 110, and an optical path is bent by an objective lens 103, and the beam is focused onto a magnetic recording medium 109.

The reflected light from the magneto-optical recording medium 109 is reflected by the objective lens 103.
, passes through beam splitter 111 and beam splitter 1
12. Here, it is divided into a servo beam and a signal beam. The signal beam enters the λ/2 plate 114, the plane of polarization rotates 45 degrees, and enters the photodiodes 105 and 106.
A signal is detected from the actuation of its output.

The magnetic field applying permanent magnet 107 is fixed so as to apply a magnetic field in the recording direction.The structure of the disk used in this embodiment is shown in FIG. On a 5.25-inch diameter polycarbonate disk substrate 301 with continuous grooves, a SiN underprotective protective film 30,200 angstroms thick, a magneto-optical recording film with a compensation composition of TbFe 303,300 angstroms long, an A1 reflective film 304,500 angstroms thick, S
A protective film of 305.600 angstroms was formed on the iN by sputtering, and then laminated with a polycarbonate substrate 307 without grooves using an ultraviolet curable resin 306.
It was initialized and used with a DC magnetic field of kOe.

First, to confirm recording and erasing, apply a magnetic field of 100
Signals were recorded and erased at 0e (recording direction), a rotational speed of 90 rpm, a laser modulation frequency of IMHz, a recording laser power of 6 mW, and a reproduction laser power of 1 mW. For the laser intensity during modulation, 1 in the recording information corresponds to the recording power level, and 0 corresponds to the reproduction level (hereinafter, when modulating the laser, use these 2
When the reproduced signal was measured using a spectrum analyzer, it was found to be 55 dB. In this state, the repetition frequency is 5M without changing the magnetic field direction and rotation speed.
When irradiated with laser at Hz, pulse width of 20 nsec, and laser power of 8 mW, it was in an erased state. When measured using a spectrum analyzer, the same spectrum as at the time of disk initialization was observed, confirming the erased state. Next, the laser oscillation frequency IMHz was set to 1.5MHz.
When recording and reproducing with a laser power of 6 mW, a CN ratio of 55 dB was obtained, and when the erase oscillation was irradiated and reproduced, an erased state was obtained.

The IMHz signal was then recorded and the 1.5MHz signal was overridden. At that time, as shown in Fig. 4, a laser was modulated so that a recording pulse of 1.5 MHz with a pulse width of 333 ns and a pulse height of 6 mW and an erase pulse of 5 MHz with a pulse width of 20 ns and a pulse height of 8 mW came between the recording pulses. The beam was irradiated. When the reproduced signal was measured with a spectrum analyzer, the noise level of the IMHz component peaked at 1.5MHz, and the CN ratio was 55dB.
Met. The override is now confirmed.

Next, we investigated the deterioration of the reproduced signal. The method is I MHz and 1
．． After repeating 5MHz recording a predetermined number of times, 1MHz
The CN ratio at 1.5 MHz and the CN ratio at 1.5 MHz were measured. The results are shown in Table 1.

In Table 1, drive A shows the case where the magneto-optical recording device according to the embodiment of the present invention is used, and drive B uses the conventional magneto-optical recording device (Fig. 2), and the direction of the applied magnetic field is applied every erasing recording. 1 MHz recording and 1.5 MHz recording were repeated alternately by changing the recording speed, and the laser power was 8 mW during recording.
7mW during erasing, 1mW playback level, applied magnetic field 1000e during recording and 2000e during erasing, other conditions were the same as drive A. 0 "-" in the table indicates that no carriers were observed within the measurable range. As can be seen from Table 1, no deterioration in the quality of the reproduced signal or deterioration of the medium was observed in the magneto-optical recording apparatus according to the present invention. On the other hand, in drive B, a decrease in erasing performance was observed due to the CN ratio and deterioration of the medium, which was thought to be due to an increase in the temperature of the medium.

The above experiment was also conducted using a combination of writing frequencies of 2 MHz and 3 MHz, and a combination of 3-MHz and 4 MHz. No deterioration of the reproduced signal or medium was observed in the magneto-optical recording device (drive A) of the present invention. However, in the conventional method (drive B), deterioration was observed as in the 1 MHz and 1.5 MHz examples.

[Effects of the Invention] As described above, according to the present invention, by using a permanent magnet as the magnetic field applying means and continuously irradiating short pulses when erasing data, the magnetic field applying means becomes a permanent magnet, so that heat generation is reduced. This has the effect that no deterioration of the medium or quality of the reproduced signal occurs.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of a reflection type magneto-optical recording device in an embodiment of the present invention. FIG. 2 is a diagram schematically showing the main parts of a conventional reflection type magneto-optical recording device. FIG. 3 is a diagram showing the disk structure used in this example. FIG. 4 is a diagram showing the laser oscillation state when overriding the 1.5 MHz signal in this embodiment. 101.202 ... Laser modulator 102.202
・ ・ Laser diode 103.203 ・ ・
Objective lens 104.204 ... Actuator 105.20
5.106.206 ... Photodiode 107.207 ... Photodiode for focus error detection 108.208 ... Photodiode for track error detection 109.209 ... Magneto-optical recording medium 110.21
0... Flip-up prism 111.211.112
．． 212... Beam splitter 113.213... Polarizing beam splitter 114
．． 214... λ/2 plate 115.215... Beam splitter 116 ・
... Permanent magnet for magnetic field application 216 ... Coil for magnetic field application 301 ... Polycarbonate substrate 302 ...
SiN lower protective film 303... Magneto-optical recording film SiN upper protective film Transparent film with high thermal conductivity Ultraviolet curable resin Polycarbonate substrate without grooves and above Applicant Seiko Epson Corporation Representative Patent Attorney Masayoshi Kamikushi (Case 1) Figure 2 Figure 3

Claims (1)

[Scope of Claims] A light beam generating means, a means for modulating the light beam, an optical means for focusing the light beam onto a magneto-optical recording medium, and a convergence point of the light beam is an information recording column on the optical recording medium. tracking and focusing means for following the magneto-optical recording medium; means for detecting the reflected beam light from the magneto-optical recording medium to detect information stored in the magneto-optical recording medium; and means for detecting servo signals for tracking and focusing. , a magneto-optical recording device comprising a magnetic field generating means for recording and erasing information, wherein the magnetic field generating means is a permanent magnet, and the direction of the magnetic field is the same at the time of information recording and erasing. erase information by emitting the light beam in a pulsed manner;
A magneto-optical recording device characterized by recording information by modulating a light beam at a lower frequency than the pulsed emission of a light beam during erasing.