JPH04167242A - Method and apparatus for recording optomagnetic recording medium - Google Patents

Abstract

PURPOSE:To enhance a C/N ratio and a jitter characteristic by a method wherein, only when a magnetic-head driving current is at a prescribed value or higher, a laser driving current is supplied to a laser and the recording face of an optomagnetic recording medium is irradiated with a laser beam which is output from the laser. CONSTITUTION:A magnetic-head driving current which is changed to a positive current and a negative current according to a data to be recorded on an optomagnetic recording medium 60 is generated. A magnetic-head driving current is supplied to a magnetic head 40 which exerts a magnetic field on the recording face of the recording medium 60. Only when the magnetic-head driving current is at a prescribed value or higher, a laser driving current is supplied to a laser; the recording face of the optomagnetic recording medium 60 is irradiated with a laser beam which is output from the laser. Thereby, a C/N ratio and a jitter characteristic can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a method and apparatus for recording desired data on a magneto-optical recording medium.

Conventional technology Recording on a magneto-optical disk utilizes the fact that when the recording surface of the magneto-optical disk is irradiated with a predetermined laser beam, the portion of the magneto-optical disk that is irradiated with the laser beam is magnetized by an external magnetic field. The data is represented by

Recording methods for magneto-optical disks include optical modulation recording methods and magnetic field modulation recording methods.

The optical modulation recording method is a method in which a constant magnetic field is always applied to a magneto-optical disk, and a laser beam is irradiated onto the recording surface of the magneto-optical disk in accordance with data to be recorded on the magneto-optical disk. In this method, in order to re-record on recorded pits, it is necessary to erase the recorded pits and then write a new one, and there is a drawback that override is not possible.

The magnetic field modulation recording method is a method in which a magneto-optical disk is always irradiated with a constant laser beam, and a magnetic field is applied to the magneto-optical disk in accordance with the data to be recorded on the magneto-optical disk.

In this method, unlike the optical modulation recording method, overriding is possible. In the case of the magnetic field modulation recording method, it is necessary to reverse the magnetic field depending on the data to be recorded on the magneto-optical disk, but this reversal can be achieved by changing the drive current of the magnetic head that generates the magnetic field to positive or negative.

Problems to be Solved by the Invention However, when recording data on a magneto-optical disk using the magnetic field modulation recording method, the magnetic head drive current is affected by the coil included in the magnetic head, so the magnetic head drive current changes as shown in Figure 4. It is not possible to change the value suddenly from positive to negative, and a transient state occurs. When the magnetic head drive current is below a predetermined value, the magnetic field applied to the magneto-optical disk is not sufficient. For this reason, an unstable recording area as shown by hatching is formed on the recording surface of the magneto-optical disk, and the existence of this area causes deterioration of the CN ratio and jitter characteristics.

An object of the present invention is to improve the CN ratio and jitter characteristics.

Means for Solving the Problems This invention records desired data by applying a magnetic field corresponding to the data to the recording surface of a magneto-optical recording medium, which becomes heated to a temperature above the Curie point by being irradiated with a laser beam. In a recording method for a magneto-optical recording medium, a magnetic head drive current that changes between positive and negative depending on the data to be recorded on the magneto-optical recording medium is generated, and the magnetic head is driven to apply a magnetic field to the recording surface of the magneto-optical recording medium. In addition to supplying a head drive current, a laser drive current is supplied to the laser only when the magnetic head drive current exceeds a predetermined value, and the laser light output from the laser is directed onto the recording surface of the magneto-optical recording medium. It is characterized by irradiation.

Preferably, the laser drive current is output from the time when the generated magnetic head drive current becomes equal to or greater than a predetermined value until a predetermined time before the time when the generated magnetic head drive current becomes equal to or less than the predetermined value again.

A recording device for a magneto-optical recording medium according to the present invention includes a magnetic head drive means for creating and outputting a magnetic head drive current that changes between positive and negative depending on data to be recorded on the magneto-optical recording medium, and an output from the magnetic head drive means. a magnetic head that inputs a magnetic head drive current to be inputted and applies a magnetic field with a polarity corresponding to the input magnetic head drive current to a recording surface of a magneto-optical recording medium; A laser drive means that outputs a laser drive current only when the value exceeds a value, and a laser drive current output from the laser drive means are input, and the recording surface of the magneto-optical recording medium is adjusted according to the input laser drive current. The present invention is characterized in that it includes a laser beam irradiation means that increases the temperature to a temperature equal to or higher than the Curie point and irradiates the recording surface of the magneto-optical recording medium with a laser beam.

Preferably, the laser driving means outputs the laser driving current from the time when the magnetic head driving current becomes equal to or higher than a predetermined value until a predetermined time before the time when the magnetic head drive current becomes equal to or less than the predetermined value again.

According to the present invention, a magnetic head drive current that changes in positive or negative depending on the data to be recorded on the magneto-optical recording medium is output. A magnetic field with a polarity corresponding to the magnetic head drive current is applied to the magneto-optical recording medium. Further, the laser drive current is output only when the magnetic head drive current exceeds a predetermined value. Laser light is irradiated onto the magneto-optical recording medium according to the laser drive current. Therefore, the laser beam is irradiated onto the magneto-optical recording medium only when the external magnetic field of the recording surface of the magneto-optical recording medium on which data is to be recorded is equal to or higher than a predetermined value, and data is recorded on the magneto-optical recording medium.

Embodiment FIG. 1 is a block diagram showing part of the electrical configuration of a magneto-optical disk recording apparatus. A detailed block diagram of the logic circuit included in this magneto-optical disk recording device is shown in FIG. Further, FIG. 3 is a time chart of signals flowing through each circuit in FIGS. 1 and 2.

Original recording signals and clock pulses corresponding to data to be recorded on the magneto-optical disk 60 are input to the logic circuit IO. The clock pulses preferably have a frequency that is an integer multiple of the bit clock pulses synchronized with the original recording signal.

For example, with four times the frequency, the frequency is 17.2872 M
Hz clock pulses are preferred. Clock pulses can also be created by PLL circuit 55. Drive signals for the magnetic head drive circuit 21 and the pulse current drive circuit 31 are created by the logic circuit IO and are applied to the respective circuits 21 and 31.

The logic circuit IO will be explained with reference to FIG.

The logic circuit IO includes first to fourth AND circuits 11 to 14,
It is composed of an OR circuit 15 and a shift register 18. The original recording signal is input to the data input terminal of the shift register 18, and the clock pulse is input to the clock input terminal of the shift register 18. Also, the clock pulse is the first AND circuit 1! and third AND circuit 13
Reverse each and enter.

4 each delayed by a predetermined time according to the clock pulse.
Two delayed signals are output from shift register 18.

These delayed signals are referred to as first, second, third, and fourth delayed signals, respectively. The first delayed signal is input to the first AND circuit 11 and the second AND circuit 12 without being inverted, but is inverted and input to the third AND circuit 13 and the fourth AND circuit 14, respectively. The second delay signal is given to the magnetic head drive circuit 21. The third delayed signal is the second A
The signals are inverted and input to the fourth AND circuit 14 without being inverted to the ND circuit 12, respectively. The fourth delayed signal is the first A
The ND circuit 11 and the fourth AND circuit 14 are connected to the second AND circuit 12 and the third AND circuit 13 without being inverted.
Highlight and input each. These first to fourth A
The outputs of the ND circuits 11 to 14 are provided to an OR circuit 15. The output of the OR circuit 15 is given to the pulse current drive circuit 31 as the output of the logic circuit IO.

Referring again to FIG. 1, the second delay signal output from the logic circuit 10 is applied to the magnetic head drive circuit 21, so that the magnetic head 22 is output from the magnetic head drive circuit 21.
drive current is output. The polarity of this drive current is reversed according to the second delay signal.

As shown in FIG. 3, the magnetic head drive current is
Due to the influence of the inductance of the coil included in 2, a transient state occurs as indicated by the symbol A. For this reason, the magnetic field applied to the magneto-optical disk 6o is also in a transient state. Then, when a predetermined time has elapsed from the rise or fall of the second delayed signal, the drive current becomes a predetermined value or more, as indicated by symbol B, and the magnetic field becomes sufficiently large.

The output current of the pulse current drive circuit 31 is applied to an adder circuit 32 and then input to a laser diode 41 included in an optical head 40. Since the output current of the pulse current drive circuit 31 corresponds to the output of the OR circuit 15 shown in FIG. 2, it is output only when the drive current of the magnetic head 22 is equal to or higher than a predetermined value. In addition, in order to prevent the recording pit from expanding due to heat conduction, a time point (T
11 to T13), the output of the drive current of the laser diode 41 ends. Therefore, laser light is emitted from the laser diode 41 only when the magnetic head drive current exceeds a predetermined value. This laser light is irradiated onto the magneto-optical disk 60 via the condenser lens 42. Since data is recorded only when the magnetic field applied to the magneto-optical disk 60 is equal to or higher than a predetermined value, formation of an unstable recording area on the magneto-optical disk 60 is prevented.

The recording device includes a monitoring photodiode 43, and the amount of light emitted from the laser diode 41 is monitored. The output current of the monitor photodiode 43 is I-V
The signal is input to the conversion amplifier circuit 51, converted into a voltage value, and then applied to the negative input terminal of the differential amplifier circuit 53. A reference voltage from the reference voltage generation circuit 52 is applied to the positive input terminal of the differential amplifier circuit 53. The voltage amplified by the differential amplifier circuit 53 is sent to the adder circuit 32 via the bias current drive circuit 54.
given to. Monitor photodiode 43.1-V
The conversion amplifier circuit 5I, the differential amplifier circuit 53, and the bias current drive circuit 54 form a feedback loop, and the light emitted from the laser diode 41 is corrected, so that a constant laser light is always output from the laser diode 41. .

Effects of the Invention According to the present invention, a laser is driven from the time when the drive current of a magnetic head for applying a magnetic field to a magneto-optical recording medium reaches a predetermined value or more, and the recording surface of the magneto-optical recording medium is Heat the temperature to above the Curie point. Then, the driving of the laser is stopped by a predetermined time period after the end of recording and the drive current of the magnetic head decreases below a predetermined value. As a result, when the magnetic field applied from the magnetic head becomes less than a predetermined value, the temperature of the recording surface drops below the Curie point, thereby preventing the formation of an unstable recording area.

Since it is possible to prevent unstable regions from being formed on the magneto-optical recording medium as in the prior art, it is possible to improve the CN ratio and jitter characteristics. Furthermore, by adjusting the laser beam irradiation time, it is possible to prevent the recording pit from expanding due to the influence of heat conduction.

The recording method according to the present invention also allows overriding, unlike the optical modulation recording method.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and is a block diagram showing part of the electrical configuration of a magneto-optical recording device. FIG. 2 is a block diagram of a logic circuit included in the magneto-optical recording device of FIG. 1. FIG. 3 is a time chart of signals flowing through each circuit of FIGS. 1 and 2. FIG. Figure 4 shows the time and time of signals flowing in a conventional magneto-optical recording device.
It is a chart, and record pits are also shown. IO...Logic circuit. 21...Magnetic head drive circuit (magnetic head drive means). 22...Magnetic head. 31... Pulse current drive circuit (laser drive means). 40... Optical head. 41... Laser diode (laser light irradiation means). 60... Magneto-optical disk. Patent applicant: NEC Home Electronics Co., Ltd.

Claims (4)

[Claims] (1) In a recording method for a magneto-optical recording medium in which desired data is recorded by applying a magnetic field according to the data to the recording surface of the magneto-optical recording medium, which reaches a temperature above the Curie point when irradiated with laser light. , generating a magnetic head drive current that changes between positive and negative depending on the data to be recorded on the magneto-optical recording medium, and supplying the magnetic head drive current to the magnetic head that applies a magnetic field to the recording surface of the magneto-optical recording medium; A magneto-optical recording medium, in which a laser drive current is supplied to a laser only when the magnetic head drive current exceeds a predetermined value, and a recording surface of the magneto-optical recording medium is irradiated with laser light output from the laser. Recording method. (2) The magneto-optical recording according to claim (1), wherein the laser drive current is output from the time when the generated magnetic head drive current becomes equal to or higher than a predetermined value until a predetermined time before the time when the generated magnetic head drive current becomes equal to or less than the predetermined value again. How the media is recorded. (3) A magnetic head drive means that creates and outputs a magnetic head drive current that changes in positive or negative depending on the data to be recorded on the magneto-optical recording medium, which inputs the magnetic head drive current output from the magnetic head drive means. , a magnetic head that applies a magnetic field with a polarity corresponding to the input magnetic head drive current to the recording surface of the magneto-optical recording medium; A laser driving means that outputs a driving current, and a laser that inputs the laser driving current output from the laser driving means and raises the recording surface of the magneto-optical recording medium to a temperature equal to or higher than the Curie point in accordance with the inputted laser driving current. A recording device for a magneto-optical recording medium, comprising: laser light irradiation means for irradiating light onto a recording surface of the magneto-optical recording medium. (4) Claim (3) wherein the laser driving means outputs the laser driving current from the time when the magnetic head driving current becomes equal to or higher than a predetermined value until a predetermined time before the time when the magnetic head drive current becomes equal to or less than the predetermined value again. A magneto-optical recording medium recording device according to.