JPH02273352A - Recording device and method for optical disk - Google Patents

Abstract

PURPOSE:To make C/N excellent, to improve recording density and jitter characteristic and to make the shape of a recording bit optimum by dividing the recording surface of an optical disk to a part which is heated in a specified time and a part which is kept at a constant temperature and outputting a recording signal. CONSTITUTION:A heating signal from a 1st signal output means O1 is controlled by a control means 1 so as to be outputted after the recording temperature of the optical disk becomes a temperature equal to or below a Curie point. The recording surface of the optical disk is heated to be at the temperature equal to or above the Curie point in the specified time with the heating signal (a1) outputted from the means O1. Thereafter, a heat keeping a signal (b1) is outputted from a 2nd signal output means O2 and the recording surface is kept at the constant temperature equal to or above the Curie point. Data is recording on the optical disk based on the heating signal and the heat keeping signal outputted from the 1st and the 2nd signal output means. The recording density is improved by making recording power high in the part of the signal (a1).

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a recording device and a recording method for optical discs, particularly magneto-optical discs and write-once optical discs.

BACKGROUND OF THE INVENTION Conventional techniques for recording data on optical disks include optical modulation recording and magnetic field modulation recording. In optical modulation recording, a weak magnetic field is applied to the recording layer of an optical disk formed by a perpendicularly magnetized film, and a spot of laser light is irradiated onto the area where data is to be written, raising the temperature of that area to near the Curie point. This records data on the optical disk in the form of a difference in the direction of magnetization at the location irradiated with the laser beam. In conventional optical modulation recording, a signal representing data to be recorded is directly applied to a laser drive circuit.

In magnetic field modulation recording, an optical disk is irradiated with a laser, the recording surface of the optical disk is raised to a temperature above the Curie point at which writing is possible, and the magnetization is reversed by changing the external magnetic field to record data. In conventional magnetic field modulation recording, recording is performed by keeping the laser drive signal constant and maintaining the temperature of the optical disk surface above the Curie point.

Problems to be Solved by the Invention In optical modulation recording, a signal representing data to be recorded (
Data is recorded by feeding the original signal (hereinafter referred to as the original signal) directly to the circuit that drives the laser.

When the C'N is good, the jitter characteristics deteriorate, and when the jitter characteristics are good, the C/N deteriorates. That is, as shown in FIG. 12, if the power of the original signal is reduced (indicated by the symbol S), the temperature of the optical disc 2A is raised to the temperature indicated by the symbol T1°, and the optical spot P is irradiated to record, the jitter characteristics will be reduced. 2A Good results, but C/N deteriorates. In addition, the C/N is good when the original signal's noise is sharpened (indicated by the symbol S), the temperature of the optical disc 1.2B is raised to the temperature indicated by the symbol T1°, and the optical spot P12B is irradiated for recording. However, the Jeddah characteristics deteriorate.

For this reason, there has been a desire for an optical disk recording device that can improve the recording density by increasing the C/N and also has good jitter characteristics.

The recording process using magnetic field modulation recording is shown in FIG. In FIG. 13, it is assumed that the recording optical spot 1-P13 moves from left to right on the track where the mark bit PM is formed, as indicated by the arrow. code t
, the magnetic field is reversed and the center of spot P13 is at this sign t. If the position corresponds to , the temperature on the rear side (left side in the drawing) of spot P13 will become higher due to heat conduction.
Coordinate X along the contour lines of the temperature distribution. A domain wall is formed at the position shown. Next, at the position indicated by the symbol t1, the magnetic field is reversed again, and along the temperature distribution at this time, the coordinate position x1
A new domain wall with a reversed magnetic field is formed. The shape of the recording pit recorded in this way is a feather-like shape that follows the shape of the contour line of the temperature distribution.

During reproduction, a reproduction signal rises when a reproduction light spot passes the edge of a recording pit, so that in a recording medium with poor thermal conductivity, the contour lines of the temperature distribution draw a large arc. For this reason, the recording pits have long feather-shaped tails, and the rise of the reproduced signal becomes slow, making it difficult to perform high-density recording.

Means for Solving the Problems The optical disc recording device according to the first invention includes a first signal output that outputs a heating signal having power to raise the temperature of the recording surface of the optical disc to a temperature equal to or higher than the Curie point within a predetermined time. means, which is output immediately after the output of the heating signal output from the first signal output means, has a power relatively lower than that of the heating signal, and is capable of controlling the temperature of the recording surface of the optical disk by Curie. a second signal output means for outputting a heat retention signal for keeping the temperature at or above a temperature of control means for controlling the delay until the temperature of the recording surface of the optical disk drops to a temperature below the Curie point after the end of outputting the signal; It is characterized in that data is recorded on the optical disc based on the signal output from the second signal output means.

The second invention is to maintain the recording surface of the optical disk at a temperature above the Curie point by irradiating the optical disk with a laser, and to reverse the magnetization of the recording surface of the optical disk by applying a change in the magnetic field from the outside, thereby transferring data to the optical disk. In the recording method for optical discs, a signal that has passed through a gate circuit that allows only signals with a predetermined pulse width to pass is used as a laser drive signal, and this laser drive signal drives a laser drive circuit to irradiate the optical disc with laser. The recording surface of the optical disk is maintained at a temperature above the Curie point and data is recorded thereon.

The third invention is to maintain the recording surface of the optical disk at a temperature above the Curie point by irradiating the optical disk with a laser, and to reverse the magnetization of the recording surface of the optical disk by applying a change in the magnetic field from the outside, thereby transferring data to the optical disk. In a method for recording an optical disc, the laser drive signal is turned off for a predetermined time after the rise and fall of a signal containing data to be recorded, and the laser drive signal is turned on for times other than the predetermined time to record the optical disc. It is characterized by keeping the surface at a temperature above the Curie point and recording one piece of data.

The fourth invention is to maintain the recording surface of the optical disk at a temperature above the Curie point by irradiating the optical disk with a laser, and to reverse the magnetization of the recording surface of the optical disk by applying a change in the magnetic field from the outside, thereby transferring data to the optical disk. Immediately after the rise of a signal containing data, a first pulse signal having the power to raise the temperature of the recording surface of the optical disc to a temperature equal to or higher than the Curie point within a predetermined time; The recording surface of the optical disk is heated by a second pulse signal that is output after the output of the pulse signal, has a relatively lower power than the power of the first pulse signal, and maintains the recording surface of the optical disk at a temperature equal to or higher than the Curie point. It is characterized in that it is maintained at a temperature above the Curie point and data is recorded.

According to the first aspect of the invention, the heating signal of the first signal output means is controlled by the control means so as to be output after the temperature of the recording surface of the optical disk becomes equal to or lower than the Curie point.

Then, the temperature of the recording surface of the optical disk rises to the Curie point or higher within a predetermined time by the heating signal output from the first signal output means. After that, a warming signal is outputted from the signal output means of node 2, and the recording surface of the optical disk is maintained at a constant temperature above the Curie point. Data is recorded on the optical disk based on the heating signal and the warming signal output from the first and second signal means.

According to the second invention, a laser driver is driven by a signal that has passed through a gate circuit that allows only a signal with a predetermined pulse width to pass, and the optical disc is irradiated with the laser to heat the recording surface of the optical disc to a temperature above the Curie point. Data is recorded while being held.

According to the third invention, the laser drive signal is turned off for a predetermined period of time after the rise and fall of the data signal. It is turned on except for a predetermined time when it is forcibly turned off, and by turning on the laser drive signal, the recording surface of the optical disk is maintained at a temperature equal to or higher than the Curie point.

According to the fourth invention, the first pulse signal causes the recording surface of the optical disc to rise in temperature to a temperature equal to or higher than the Curie point within a predetermined time. Then, the recording surface of the optical disk is maintained at a temperature equal to or higher than the Curie point by a second pulse signal having a power relatively lower than the pulse width of the first pulse signal.

Embodiments First, the first invention will be explained. The first invention is an optical modulation recording method in which the external magnetic field is kept constant and the laser output is varied.

FIG. 1 shows an embodiment of an optical disc recording device according to the first invention, and is a block diagram showing extracted characteristic parts of the optical disc recording device. FIG. 2 is a time chart showing signal waveforms flowing through each part of the block diagram shown in FIG.

In FIG. 2, the clock signal is omitted from illustration.

The original signal is sent to the input terminal of shift register 1 and the first AN
It is applied to the input terminal of the D circuit 11. shift register 1
A clock signal for timing the output is applied to the clock input terminal, and a signal delayed by a predetermined time is output in synchronization with this clock signal. The delayed signals are output from output terminals 01 and 02 of shift register 1, respectively. From output terminal 0, time T with respect to the original signal
A signal is output with a delay of n1 (corresponding to the time of the n1 clock), and an exclusive OR circuit (hereinafter referred to as an EX-OR circuit)10. It is applied to the input terminals of the first AND circuit 11 and the second AND circuit 12, respectively. In addition, a signal delayed by time TI11 (corresponding to m1 clock time) with respect to the original signal is output from output terminal 0°, and EX-O
It is applied to the input terminal of the R circuit 10. EX-OR circuit 1
The delayed signal exclusive-ORed with 0 is the second A
It is applied to the input terminal of the ND circuit 12.

The first AND circuit 11 performs the logical product of one original signal and the delayed signal output from the output terminal 01 of the shift register 1, and outputs the result. The output signal of the AND circuit 11 is applied to the negative input terminal of the next stage operational amplifier 13 via a resistor R1.

This output signal corresponds to the laser irradiation time of the optical disc.

The delay signal output from the output terminal 0□ of the shift register 1 by the second AND circuit 12 and the EX-OR circuit 10
The logical AND with the signal output from is taken and output.

Similarly to the output signal of the AND circuit 11, the output signal of the AND circuit 12 is also connected to the operational amplifier 13 via the resistor R2.
is applied to the negative input terminal of .

The operational amplifier 13 has a feedback loop via a resistor R3.
The loop is connected to the negative input terminal. The positive input terminal is grounded. This operational amplifier 13 performs an addition operation using the resistance ratio of the resistor R1 and the resistor R2 as a coefficient. The output signal of the operational amplifier 13 is applied to the negative input terminal of the next stage operational amplifier 14 via a resistor R4. This operational amplifier 14 also has a fitback loop via resistor R5, which connects the output terminal and the negative input terminal. Further, the positive input terminal is grounded.

The output signal from the output terminal of the operational amplifier 14 is the recording signal. The recorded signals are shown in the bottom row and third row of Figure 2.
As shown in the upper part of the figure, the portion a1 corresponds to the heating signal with relatively large laser power for a predetermined time after the signal rises.
and a portion b1 corresponding to the warming signal having a laser power smaller than the laser power of the portion at corresponding to the heating signal. As shown in FIG. 3, the heating signal portion a1 of the recording signal causes the recording surface of the optical disk to rise in temperature to the Curie point or higher within a predetermined time.

Thereafter, the recording surface of the optical disk is maintained at a constant temperature by a portion b1 of the recording signal corresponding to the heat retention signal. When the output of the recording signal is finished, the temperature of the recording surface of the optical disk decreases to below the Curie point. Recording pits recorded on the recording surface of the optical disc using such recording signals are indicated by P3 in the lower part of FIG.

Next, the second invention will be explained. The second invention is a magnetic field modulation recording method in which data is recorded by irradiating the recording surface of an optical disk with a laser to raise the temperature above the Curie point and changing the external magnetic field.

FIG. 4 shows characteristic parts of a block diagram showing an embodiment of the second invention, and FIG. The shape of the pit and the waveform of the reproduced signal are shown, respectively. In FIG. 5, illustration of the clock signal is omitted.

A clock signal synchronized with a recording signal corresponding to a changing state of the external magnetic field is applied to a clock input terminal of a frequency divider 21, and the frequency is divided by a predetermined frequency division ratio. The frequency-divided signal is applied to an amplifier 22, which performs amplification optimization and outputs it as a laser drive signal.

The output laser drive signal is a pulse signal having a frequency division ratio set by the frequency divider 21, and the laser driver is driven by this laser drive signal. As a result, the recording surface of the optical disk is irradiated with a laser beam, and the recording surface is maintained at a temperature equal to or higher than the Curie point. When the external magnetic field changes as a recording signal while the temperature is maintained at a temperature higher than the Curie point, the magnetization is reversed and recording pits P are formed on the recording surface of the optical disk.
5 is formed and data is recorded. During reproduction, when the beam spot for reproduction passes through one edge of the recording pit P5, the reproduction signal rises steeply, and when it passes the other edge, the reproduction signal falls.

Next, the third invention will be explained. The third invention also uses a magnetic field modulation method like the second invention.

FIG. 6 shows characteristic parts of a block diagram showing an embodiment of the third invention, and FIG. 7 shows the signal waveforms of the recording signal and the laser drive signal, and the recording pattern on the recording surface of the optical disc. has been done. In FIG. 7, illustration of the clock signal and original signal is omitted.

An original signal containing data to be recorded on the optical disk is applied to the input terminal of the shift register 31, and a clock signal synchronized with the original signal is applied to the shift register 31.
is given to the clock input terminal of The shift register 31 has a first output terminal 01 and a second output terminal 02, and the first output terminal 01 outputs the original signal 02.
A signal delayed by the clock is output and sent to EX-OR circuit 3.
is applied to one input terminal of 2. Also, the delayed signal output from the first output terminal is used as a recording signal by the magnetic head (
(path shown). A signal delayed by m2 clocks from the original signal is output from the second output terminal, and EX-OR
It is applied to the other input terminal of circuit 32.

The EX-OR circuit 32 takes the exclusive OR of the delayed signals output from the output terminals 01 and 02 and outputs the
The signal is applied to the OT circuit 33. The signal inverted by the NOT circuit 33 is given to the laser driver as a laser drive signal to maintain the recording surface of the optical disk at a temperature above the Curie point.

The laser drive signal uses two delayed signals, EXOR
By being generated by the circuit 32 and the NOT circuit 33,
It is turned off for a certain period of time immediately after the rise of the recording signal and for a certain period of time immediately after the fall of the recording signal. While the laser drive signal is turned off, the recording surface of the optical disk is not irradiated with a laser and heat is radiated from the optical disk, so that the optical disk is cooled. The off period is Ω2 clocks determined by the shift register 31 and m
It depends on the amount of delay of 2 clocks.

The recording surface of the optical disk is maintained at a temperature above the Curie point based on the laser drive signal, and when a recording signal is applied to the magnetic head, the magnetic field changes and the recording surface is magnetized in the area where the recording signal was applied to the magnetic head. is reversed. Data is thereby recorded. In FIG. 7, only the portion of the magnetic field that is reversed is shown as a recording pit.

FIG. 8 is a block diagram showing another embodiment.

In the block diagram shown in FIG. 8, the original signal is directly applied to the magnetic head (path shown) as a recording signal.

The original signal is applied to the input terminals of the first one-shot multivibrator 35 and the NOT circuit 34, respectively.

The original signal applied to the NOT circuit 34 is inverted and applied to the second one-shot multivibrator 36.

The output signal of the first one-shot multivibrator 35 and the output signal of the second one-shot multivibrator 3B are respectively applied to input terminals of an AND circuit 37. The AND circuit 37 performs a logical product and outputs the result, so that it can be obtained as a laser drive signal.

Next, the third invention will be explained. The third invention is also based on a magnetic field modulation recording method.

The characteristic parts of the block diagram showing the embodiment of the third invention in FIG. 9 are the time chart 1 shown in FIG. The temperature state of the recording surface of the two-optical disk and the state of the recording pits are shown in each signal waveform of the laser drive signal.

The original signal is given to the input terminal of the shift register 41, and the clock signal is given to the clock input terminal of the shift register 41, respectively. To the shift register 41, signals delayed from the original signal by ρ clock, Ω2 clock and 1g3 clock are outputted from three output terminals O, O and 03, respectively. In other words, the first delayed signal delayed by Ω1 clocks from the original signal is output from the inner terminal 01, the second delayed signal delayed by Ω2 clocks from the original signal is output from the output terminal O, and the second delayed signal delayed from the original signal by Ω2 clocks is output from the output terminal 03. , l!
A third delayed signal delayed by three clocks is output.

The first delayed signal and the second delayed signal are connected to one EX-O
It is applied to the input terminal of the R circuit 42, the exclusive OR is taken, and the result is applied to the NOT circuit 45 at the next stage. The inverted output signal from the NOT circuit 45 is applied to one input terminal of an AND circuit 47.

The second delayed signal and the third delayed signal are connected to the other EX-O
It is applied to the input terminal of the R circuit 43, exclusive ORed, and output. The output signal of the EX-OR circuit 48 is given to an OR circuit 46 at the next stage. The OR circuit 46 has N
An inverted clock signal is also provided by the OT circuit 44. The signal logically summed by the OR circuit 46 is given to an AND circuit 47. A 1 laser drive signal can be obtained by logically multiplying the output signal of the NOT circuit 45 and the output signal of the OR circuit 46, which are applied to the AND circuit 47. The driver is driven by this laser drive signal, and the recording surface of the optical disk is maintained at a temperature above the Curie point. The recording signal is a delayed signal output from the second output terminal 02 of the shift register 41, and this recording signal is applied to a magnetic head (path shown) to record data.

Referring to FIG. 11, the laser drive signal is a heating signal portion a2 for raising the temperature of the recording surface of the optical disk to a temperature higher than the Curie point in a short period of time, and a heating signal portion a2 for maintaining the recording surface of the optical disk at a temperature higher than the Curie point. It can be divided into a heat retention signal part b2 for heating and a cooling signal part C2 for releasing heat.

The heating signal portion a2 rises in synchronization with the rise or fall of the recording signal. After the heating signal part a2 is output, the keeping-warm signal part b2 is output, and there is a cooling signal part C2 between the time when the output of the keeping-warm signal part b ends and the heating signal part a2.

When the laser driver is driven by a laser drive signal and a recording signal is applied to the magnetic head when the recording surface of the optical disk is at a temperature higher than the Curie point, the magnetization of the corresponding position on the track is reversed and the recording pit P1□ is data is recorded.

Effects of the Invention According to the first invention, in the optical modulation recording method, the recording signal is output in two parts: a signal part that heats the recording surface of the optical disc within a predetermined time, and a signal part that keeps the recording surface at a constant temperature. By increasing the power, it is possible to improve the C/N and improve the recording density. Furthermore, since the heat retention signal is specifically output, the recording range does not increase due to residual heat, and recording with good jitter characteristics can be performed. Furthermore, since the output of the recording signal is controlled until the recording surface of the optical disk becomes below the Curie point, the optimum shape of the recording pit can be achieved.

According to the second invention, in the magnetic modulation recording method, the laser drive signal is not output continuously but as a pulse signal with a fixed interval, so it is necessary to accumulate heat generated in the optical disk by thermal conduction. can be kept to a minimum. Therefore, the shape of the recording pit, which is arrow-shaped, can be optimized, and the rise of the reproduced signal becomes steep, allowing high-density recording.

According to the third invention, in the magnetic modulation recording method, the laser drive signal is turned off for a certain period of time immediately after the rise and fall of the recording signal, so that the recording surface of the optical disk is cooled while the laser drive signal is turned off.

As a result, the accumulation of heat on the optical disk can be suppressed, the shape of the recording pits can be optimized, and the reproduced signal exhibits a steep rise, making it possible to perform high-density recording.

According to the fourth invention, in the magnetic modulation method, the laser drive signal includes a heating signal portion that rapidly increases the temperature of the recording surface of the optical disk, a heat retention signal portion that maintains the temperature of the recording surface of the optical disk, and a cooling signal portion that cools the recording surface of the optical disk. Since it includes a signal portion, it is possible to suppress the accumulation of heat on the optical disc. For this reason, the shape of the recording domain is optimized,
The reproduced signal exhibits a steep rise, making it possible to perform high-density recording.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the first invention, FIG. 2 is a time chart showing signal waveforms flowing through the circuit shown in FIG. 1, and FIG. 3 is a recording signal obtained by the circuit shown in FIG. 1. FIG. 3 is a diagram showing the temperature rise on the recording surface and the appearance of recording pits when recording is performed. Fig. 4 is a block diagram showing an embodiment of the second invention, and Fig. 5 shows a laser drive signal, a recording signal, a temperature state of the recording surface of the optical disk, a shape of a recording pit, and reproduction obtained by the circuit shown in Fig. 4. It is a figure which shows each signal. FIG. 6 is a block diagram showing an embodiment of the third invention, and FIG. 7 is a diagram showing the waveforms and recording pits of the recording signal and laser drive signal obtained by the circuit shown in FIG. 6. FIG. 8 is a block diagram showing another embodiment. FIG. 9 is a block diagram showing an embodiment of the fourth invention;
The figure shows a time chart 1 showing the signal waveforms flowing through each part of the block diagram shown in Fig. 9, and Fig. 11 shows the recording number, laser drive signal, and temperature of the recording surface of the optical disk obtained from the circuit shown in Fig. 9. It shows the state and shape of the recording pit. FIG. 12 is a diagram showing the temperature rise on the recording surface and the appearance of recording pits when recording is performed using the conventional optical modulation recording method. FIG. 13 is a diagram showing the recording process when recording is performed by conventional magnetic field modulation recording. 1, 31.41...Shift register. 10, 32.42.43...EX-OR circuit. 11, 12.37.47...AND circuit. 13, 14...Operational amplifier 21...Frequency divider. 22...Amplifier. 33, 34.44.45...NOT circuit 35, 36.
...One-shot multi-bye break. 46...OR circuit. R-Rs...resistance. ■ That's all

Claims (4)

[Claims] (1) a first signal output means for outputting a heating signal having power to raise the temperature of the recording surface of the optical disk to a temperature equal to or higher than the Curie point within a predetermined time; a heating signal output from the first signal output means; A second heating signal is output immediately after the heating signal finishes outputting, and has relatively lower power than this heating signal, and outputs a heating signal that keeps the temperature of the recording surface of the optical disk at a temperature higher than the Curie point. The heating signal outputted from the signal outputting means and the first signal outputting means is outputted after the heating signal outputted from the second signal outputting means finishes outputting, and the temperature of the recording surface of the optical disc is set. control means for controlling the delay until the temperature drops below the Curie point; An optical disc recording device that performs recording. (2) The recording surface of the optical disk is maintained at a temperature above the Curie point by irradiating the optical disk with a laser, and the magnetization of the recording surface of the optical disk is reversed by applying a change in the magnetic field from the outside to record data on the optical disk. In an optical disc recording method, a signal that has passed through a gate circuit that allows only signals with a predetermined pulse width to pass through is used as a laser drive signal, and this laser drive signal drives a laser drive circuit to irradiate the optical disc with a laser to record the optical disc. An optical disc recording method characterized by recording data while maintaining the surface at a temperature above the Curie point. (3) The recording surface of the optical disk is maintained at a temperature above the Curie point by irradiating the optical disk with a laser, and the magnetization of the recording surface of the optical disk is reversed by applying a change in the magnetic field from the outside to record data on the optical disk. In an optical disc recording method, the laser drive signal is turned off for a predetermined period of time after the rise and fall of a signal containing data to be recorded, and the laser drive signal is turned on for times other than this predetermined time to cure the recording surface of the optical disc. A method for recording an optical disc, which is characterized by recording data while maintaining the temperature at a temperature higher than the temperature of the disc. (4) The recording surface of the optical disk is maintained at a temperature above the Curie point by irradiating the optical disk with a laser, and the magnetization of the recording surface of the optical disk is reversed by applying a change in the magnetic field from the outside to record data on the optical disk. In an optical disc recording method, a first pulse signal having power to raise the temperature of the recording surface of the optical disc to a temperature equal to or higher than the Curie point within a predetermined time immediately after the rise of a signal containing data; A second pulse signal is output after the output, has a power relatively lower than the power of the first pulse signal, and maintains the recording surface of the optical disk at a temperature above the Curie point, so that the recording surface of the optical disk is heated to the Curie point. A method for recording an optical disc, which is characterized by maintaining the temperature at a temperature above and recording data.