JPH02179950A - Method and device for recording of optical disk - Google Patents

Abstract

PURPOSE:To improve jitter characteristics and to improve recording density by executing recording by using the pulse trains generated by subtracting the specified number of pulses which do not exceed the min. pulse from the pulse trains passed through a gate during the period corresponding to the recording wavelength. CONSTITUTION:The bit clock signal synchronized with an original signal is applied to a clock input terminal of a shift register 10 and an input terminal of an AND circuit 11. This original signal is delayed for a specified period of time by the shift register 10 and is applied as a delay signal to the input terminal of the AND circuit 11. The original signal, bit clock signal and delay signal pass through the AND circuit 11 and are thereby outputted as the recording signal. The recording signal is applied to the driver of a laser. The laser is driven by this driver and the surface of an optical disk is irradiated with the light spot P2 corresponding to the recording signal, by which data recording is executed. The increase of the C/N and the improvement of the recording density are possible in this way and the correct reproduction of the edge part of the recording signal is possible as well.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an optical disk, particularly a recording method and apparatus for a magneto-optical disk.

Conventional Technology There are various ways to record data on magneto-optical disks.
One of them is to apply a weak magnetic field to the recording layer of a magneto-optical disk formed by a perpendicularly magnetized film.
A spot of laser light is irradiated onto the location where data is to be written, raising the temperature of that location to near the Curie point. Thereby, data can be recorded on the magneto-optical disk in the form of a difference in the direction of magnetization at the location irradiated with the laser beam.

Conventionally, a signal representing data to be recorded was directly applied to a laser drive circuit.

Problems to be Solved by the Invention However, when magneto-optical recording is performed by feeding a signal representing data to be recorded (hereinafter referred to as the original signal) directly to a circuit that drives a laser, as shown in Figure 5, thermal conduction is affected. As a result, the C/N ratio deteriorates significantly, making it impossible to increase the recording density. In FIG. 5, P5A indicates a case where the laser power is large, and P5B indicates a case where the laser power is small.

On the other hand, as shown in Figure 6, by narrowing the width of the original signal by a certain period of time to make it smaller, an appropriate light spot P6 is irradiated, compensating for the effects of heat conduction, and recording with a high C/N becomes possible. , the recording density can be increased if the signals have the same period.

However, when the data to be recorded changes and the wavelength of the original signal changes significantly as shown in Figure 7, if the width of the original signal is narrowed and recorded, the position of the optical spot P7 of the laser beam will change relative to the original signal. Since the edges are misaligned, recorded data cannot be reproduced correctly.

For this reason, there has been a demand for an optical disc recording apparatus that can improve the recording density by increasing the C/N and can also correctly reproduce the edge portions of recorded signals.

Means for Solving the Problems The optical disc recording method according to the present invention records a recording signal whose recording wavelength changes according to the recording wavelength of the recording signal.
In an optical disc recording method that converts continuous pulses of a constant waveform and a constant interval into a number of pulses for recording, a constant number of pulses not exceeding a minimum pulse train is converted from a pulse train that has passed through a gate during a period corresponding to the recording wavelength. It is characterized by recording using a pulse train generated by subtraction.

The optical disk recording device according to the present invention includes a delay circuit that delays a recording signal to be recorded on the optical disk for a predetermined period of time, and a logic that performs a logical product of the recording signal, its bit clock signal, and the delayed recording signal delayed by the delay circuit. It is characterized by comprising a product circuit and an optical head that performs recording on an optical disk based on the signal output from the AND circuit.

According to the first invention, a recording signal whose recording wavelength changes is converted into a number of continuous pulses having a constant waveform and constant intervals. Recording is performed using a pulse train generated by subtracting a fixed number of pulses not exceeding the minimum pulse train from the pulse train that passed through the gate during the period corresponding to the recording wavelength.

By minimum pulse train is meant the pulse train produced by being gated by the highest frequency recording signal.

According to the second invention, the recording signal (original signal) is delayed for a certain period of time by the delay circuit. with recording signal.

The bit clock signal and the delayed recording signal are ANDed by an AND circuit, and a laser is driven by the signal output from the AND circuit to record on the optical disk. In this case, the power of the laser beam is adjusted so that the edge of the laser beam spot (bit) matches the width of the recording signal. This makes the bit width of the recording signal almost equal regardless of the wavelength.

Embodiment FIG. 1 shows a characteristic portion of a recording circuit in an optical disk recording apparatus. In addition, each signal flowing through this circuit is shown in FIG.

Referring to these figures, the original signal modulated by the data to be recorded on the optical disk (for example, an EFM modulation signal) is connected to the data terminal of the shift register 1o and the AND circuit 1.
1 input terminal. Also, the bit clock signal of the original signal, which is synchronized with the original signal, is transferred to the shift register l.
It is applied to the clock input terminal of O and the input terminal of AND circuit 11. The original signal given to the shift register IO is.

The signal is delayed for a certain period of time by the shift register IO and is applied to the input terminal of the AND circuit 11 as a delayed signal.

Original signal given to the input terminal of the AND circuit 11.

The bit ψ clock signal and the delayed signal pass through an AND circuit 11 and are output as a recording signal. This recording signal is given to the laser driver. Then, the laser is driven by this driver, and a light spot P2 corresponding to the recording signal is irradiated onto the optical disk to record data. ◎Figure 3 shows another embodiment 0 In this circuit, the shift register IO day line 12 instead of
is applied. In this figure, the same components as those shown in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted.

Referring to FIG. 3, the original signal is applied to the input terminal of the delay line 12 and the input terminal of the AND circuit 11, and the delayed signal output from the delay line 12 is also applied to the input terminal of the AND circuit 11. .

Also, the bit clock signal that is synchronized with the original signal is
It is applied to the input terminal of D circuit II.

The recording signal output from the AND circuit 11 is a logical product of the original signal, the bit clock signal, and the delayed signal, similar to the circuit shown in FIG. 1, and this recording signal drives the laser driver. Data is recorded on the optical disk by a laser in response to a recording signal.

For reference, FIG. 4 shows a time chart when the original signal is ANDed with the bit clock and clock signals, and the laser driver is driven by this signal. FIG. 4 shows a light spot P of laser light generated by a laser driven by an AND signal of an original signal and a bit clock signal,
P is also shown as 4A 4B. One optical spot P4A shows the situation when the intensity of the laser beam is increased, and the other optical spot P4B shows the situation when the intensity of the laser beam is decreased.

In this case, when recording is performed on the optical disc using the optical spot P4A that is generated when the intensity of the laser beam is increased, the C/N improves and high-density recording is possible, but the edges are not reproduced correctly during reproduction, so the data is Unable to read correctly.

In addition, in order to correctly reproduce the edges of the recorded portion, the intensity of the laser beam is lowered, and if recording is performed on the magneto-optical disk using the optical spot P4B generated at this time, the C/N deteriorates, so a high recording density is obtained. I can't. In either case, the conventional problem cannot be solved.

Effect of the invention According to the first invention, jitter characteristics are improved.

It is possible to improve recording density.

According to the second invention, since the laser is driven based on the signal output from the AND circuit that takes the AND of the original signal, the bit clock signal, and the delayed signal of the original signal, the second invention also improves the jitter characteristics. This makes it possible to record data on the optical disc with a high C/N, and to improve the recording density. For example, the 1σ of jitter is significantly improved when recording is performed on a magneto-optical disk using the method shown in FIG. 6 and when recording is performed on a magneto-optical disk using the present invention.

Furthermore, in the present invention, since the shortest wavelength of the eye pattern does not overlap with other wavelengths, it can be seen that the aperture ratio of the eye is low in the conventional apparatus, and is improved by the present invention.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment according to the present invention, and FIG.
The figure shows the signal waveform flowing through each part of the block diagram shown in FIG. 1 and the appearance of a light spot caused by a laser beam. FIG. 3 is a block diagram showing another embodiment. FIG. 4 shows each signal waveform diagram when recording is performed using the original signal and the bit clock signal. Figures 5 to 7 show the signals and light spots used during recording using the conventional method. In Figure 6, recording is performed using a signal with a shorter width than the original signal, and the signal with a shorter width and a laser beam are
In FIG. 7, recording is performed by logical product of the original signal and the signal with a shortened width, and shows the original signal, the signal with the shortened width, and the laser beam, respectively. lO...Shift register. 11...AND circuit. 12...Delay line. P2"P4A"P4B' 5^ 5B"B. P, P...Light spot. Above Figure 3 Figure 2 Figure y!

Claims (2)

[Claims] (1) In an optical disc recording method in which a recording signal whose recording wavelength changes is converted into a number of continuous pulses having a constant waveform and a constant interval according to the recording wavelength of the recording signal and recorded, A method for recording an optical disc, characterized in that recording is performed using a pulse train generated by subtracting a fixed number of pulses not exceeding a minimum pulse train from a pulse train that has passed through a gate during a corresponding period. (2) a delay circuit that delays a recording signal to be recorded on an optical disk for a predetermined period of time; an AND circuit that ANDs the recording signal, its bit clock signal, and the delayed recording signal delayed by the delay circuit; and the logic circuit described above. An optical disc recording device comprising: an optical head that records on an optical disc based on a signal output from an integrated circuit.