KR0124618B1 - Recording density decision method of optical disk - Google Patents

Abstract

A method for determining a recording density of an optical magnetic disk is disclosed. First, it is determined whether the focusing remains or not. In case that the focusing remains, the value of the cross talk is changed to RF analog signal, and the amplitude of the analog signal is detected. And then, the maximum and the minimum values of the magnitude of the analog signal are calculated. The calculated value is compared to a reference value to determine the recording density.

Description

Determination Method of Recording Density of Magneto-optical Disk

1A is an explanatory diagram showing a beam irradiated onto a track of a high density disk.

(B) of FIG. 1 is a waveform diagram of a harmonic analog signal to (a).

2A is an explanatory diagram showing a beam irradiated onto a track of a low density disk.

(B) of FIG. 2 is a waveform diagram of an analog signal of harmonics in (a).

3 is a schematic block diagram of the present invention.

4 is an embodiment of the present invention.

5 is a schematic flowchart for carrying out the invention.

The present invention relates to a method for determining the recording density of a magneto-optical disk, and more particularly, to a method for determining the recording density of a magneto-optical disk for determining the recording density of the disk by driving a focusing servo mechanism to detect the track pitch of the disk.

Until now, commercialization of discs with significantly different recording densities has not been commercialized.In the area of the same disc, where the recording linear speed of compact discs is 1.2 to 1.4m / s, the discs play differently if the linear speeds are different. The density is different, but the difference is not large.

However, if a compact disc with high recording density is commercialized, the player can distinguish between a low density diskette and a high density diskette so that a high density magneto-optical disk can be used for a playback device using a compact disc with a low recording density. It is a matter of course that the playback system must be switched at the same time as the recording density.

On the other hand, in order to change the recording density, the length of the unit pit recorded on the disc track is reduced or the track pitch between the track and the track is reduced. Usually, the length of the pit (3T ~ 11T) and By simultaneously reducing the track pitch, the recording density is increased. In such a case, the reproducing apparatus that has discriminated between the low density disk and the high density disk must process the operation of the digital signal processor in accordance with the recording density of the disk.

Conventionally, in order to determine the recording density of the disc, a method of placing an ID (Identification Data) code indicating the recording density of the disc has been proposed, but in this case, the ID (Identification Data) code is read to read the disc. Since it is necessary to determine the type, there is a constraint that the ID loss of the disc and the format of the ID of the disk must be the same.

Accordingly, the present invention has been made to solve the above problems, the rotation servo for rotating the disk motor during the recording or playback command, the focusing servo for focusing the reflective surface of the disk, and the laser beam irradiated to the disk surface The laser output servo to read the information of the disk is driven, but the tracking servo is not driven. As the disk motor rotates, the main laser beam has a few (1 ~ 2) tracks due to the disk eccentricity or the disk motor shaft. It is an object of the present invention to provide a recording density determination method of a magneto-optical disk for determining the recording density of a disc to be reproduced by using the amount of crosstalk detected by causing the pit face and the mirror face to be depressed.

In order to achieve the above object, the present invention provides a method for determining whether focusing is maintained correctly as a disk rotates, and a cross generated when the laser beam traverses a small number of disc tracks as the focus is maintained. Torque (Crose Talk) phenomenon (leakage of signal current on the mirror surface close to the fit surface) Converting reflected light into an analog signal of harmonics (RF) to detect an envelope, and detecting the envelope according to the cross talk phenomenon. Detecting a maximum value and a minimum value and outputting a ratio of the minimum value to the maximum value, and comparing the ratio of the minimum value to the maximum value with a reference value to obtain a high signal (for a high density disc) and a low signal (for a low density disc). It can be configured as a step to output.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

(A) of FIG. 1 is an explanatory view of picking focusing a high-density disk having a narrow track pitch with a beam of diameter D, and (b) of FIG. 1 is a disc according to the pickup focusing of (a) of FIG. A beam having a diameter D is a waveform diagram that detects an analog signal of harmonics (RF) that is detected after being irradiated to the pit surface and the mirror surface of the track while moving the track of the track. The maximum value (Vp) and minimum value (Vb) of the analog signal of the harmonic RF detected while passing through a plurality of vi) and mirror surfaces are shown. Points a, b and c in FIG. 1 (a) correspond to points a ', b' and c 'in FIG.

(A) of FIG. 2 is an explanatory view of pickt focusing a low-density disc having a wide track pitch with a beam of diameter D ', and (b) of FIG. 2 (b) shows the fit of the track according to the pickt focusing of (a). It is a waveform diagram that detects the analog signal of the harmonics (RF) of the beam detected after being irradiated to the pit surface and the mirror surface of the track while crossing a small number (1 to 2) between the surface and the mirror surface. D ') shows the maximum value vp' and minimum value vb 'of the electrical waveform detected as the beam of D') passes through a plurality of pit and mirror surfaces of the disc.

Therefore, as shown in (b) and (b) of FIG. 1, the signal of the waveform is largely detected when the beam crosses the pit surface, and the waveform is crossed when the mirror surface is crossed. Since the signal of D is small and the calculation ratio of the maximum value and the minimum value of each waveform is different, it is possible to determine the density of the disk by detecting and comparing the right angle cases.

Accordingly, an optimum playback state can be maintained by switching signal equalization characteristics, servo loop characteristics, and digital signal processing corresponding to the density of the disc.

3 is a schematic block diagram of the present invention, in which a laser beam reflected from a compact disc is incident to the photodiode 36 and then outputted to be converted into an analog signal of harmonics (RF), Detection means 32 for detecting an envelope of harmonics RF converted by the signal conversion means 31 and a minimum value of the maximum value of the analog signal of harmonics RF detected by the detection means 32. Is composed of recording density determination means 33 for comparing the ratio of the signal to the reference value, and harmonics (RF) output from the signal conversion means (31) when the focusing servo mechanism (Focusing Servo Mechanism) and the rotation servo mechanism of the disk motor is driven. The amplitude of the analog signal is determined by the detection means 32, and the ratio of the minimum value to the maximum value of the analog signal of the harmonics RF output from the detection means 32 is determined by the recording density determination means. The low density disc reproducing apparatus 34 and the high density disc reproducing apparatus 35 are respectively driven in accordance with the recording density of the disc to be reproduced in comparison with the standard value.

4 is a diagram for determining a recording density of a disc by detecting a ratio of a minimum value to a maximum value of an analog signal of harmonics (RF) of FIG. 3. The analog signal is DC-coupled by the capacitor 41 and half-wave rectified by the diode 43 via the buffer 42 and then applied to the maximum value detecting end 44 and the minimum value detecting end 45, respectively.

The maximum value detection stage 44 outputs the maximum value of the analog signal, and the minimum value detection stage 45 detects only the minimum value of the analog signal and is input to the divider 46, respectively.

The divider 46 calculates the maximum value Vp and the minimum value Vb inputted from the maximum value detection stage 44 and the minimum value detection stage 45 to determine the ratio of the minimum value Vb to the maximum value Vp ( Vp / Vb) is input to the non-inverting stage (+) of the comparator 47, which is a recording density determination means.

Therefore, the signal (Vp / Vb) input from the divider 46 to the non-inverting terminal (+) of the comparator 47 is compared with the reference voltage V-bias input to the inverting terminal (-). Since it is output in the state of the level, the high density disk and the low density disk can be distinguished according to the level state.

That is, the output value of the comparator 47 is accepted by a microcomputer (not shown) or an analog switch (not shown), so that the system can be used for signal equalization, servo loop, Digital signal processing and the like were switched to maintain the optimal playback state.

On the other hand, at the time of reproduction, a focusing movable part (not shown) for precisely irradiating a laser beam onto the disc when the disc vibrates or changes in the formation of the track, and the pit plane on which the data irradiated on the disc can always follow. The tracking movable part (not shown) has a respective servo mechanism so that the laser beam is always correctly irradiated to the pit surface on the disk to continuously read the data on the disk.

In this embodiment, the division ratio, which is the size ratio of the minimum value to the maximum value, is output using the divider 46, but an adder or a subtractor may be used as the calculation means.

5 is a schematic flowchart for carrying out the present invention, which operates a focusing directional actuator and a focusing servoblock to precisely irradiate a beam onto a disc (step 500).

Then, it is determined whether the focusing operation is maintained (step 510), and when maintaining the focusing operation, the spindle motor is rotated (step 520).

Then, the main beam crosses a plurality of tracks as shown in FIGS. 1 and 2 due to the disc eccentricity, and the analog signal of the harmonics RF is input to the recording density determination means 33 of FIG. When a high level signal is outputted (step 530), the high density reproducing apparatus 34 is activated (step 540), and a low level signal is output. In this case, the low-density playback device 35 is activated (step 550) so that the playback system is selected according to the density of the current disc.

As described above, according to the present invention, in a system capable of simultaneously reproducing a high-density disc and a low-density disc, an analog signal of harmonics (RF) is generated while the beam traverses the track while maintaining only the focusing servo while rotating the spindle motor without using a special ID code. The recording density of the disc can be easily determined by using the amount of crosstalk (detected amount of signal current leaked between adjacent signal lines) outputted by the high-density and low-density discs. There is a feature that can activate the system.

Claims (4)

Determining whether focusing is maintained correctly as the disk rotates, and harmonics (Crose Talk) values generated as the laser beam traverses a small number of disc tracks as the focus is maintained. Detecting an envelope by converting the signal into an analog signal, calculating and outputting the minimum and maximum values of the envelope, and comparing the calculated value with a reference value to verify a recording density. Method for determining recording density of magneto-optical disks. 2. The method of claim 1, wherein the calculated value of the maximum and minimum values of the detected envelope is a subtracted value. 2. The method of claim 1, wherein the calculated value of the maximum and minimum values of the detected envelope is a division value. The method of claim 1, wherein the calculated value of the maximum and minimum values of the detected envelope is an addition value.