KR0153902B1 - Laser power modulation circuit for data recordable disc - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser power modulating circuit for a recordable optical disc, which modulates and outputs laser power based on an information recording / erasing signal and an information reproducing signal having different levels with respect to an optical disc capable of repeating recording / reproducing of information. In a laser power modulation circuit of an optical disc, a first duty converter 40 for receiving a clock signal synchronized with information to be recorded on the optical disc to generate a signal having a first duty ratio, and a clock synchronized with the information to be recorded. A second duty converter 42 generating a signal having a second duty ratio based on the signal, and switching in response to the information to be recorded, the signal having the first duty ratio and the signal having the second duty ratio; A switch having a first duty ratio selectively outputted by the switching action of the first switch unit 44 and a signal having the second duty ratio A level setting section 46 for setting the recording / erasing level of the information on the basis of the recording control signal of the information, and a reproducing level setting section 48 for setting the information reproducing level for reproducing the information recorded on the optical disc; An adder 50 for adding and processing the recording / erasing level of the information set by the level setting section 46 and the reproducing level of the information set by the reproducing level setting section 48, and a laser driver having a level added by the adder 50; And a second switching unit 52 for switching and controlling the application of the signal to 54, wherein the signal of the first duty ratio generated by the first duty converter 40 is converted to the second duty converter 42. The duty ratio is set to have a duty ratio that is greater than the signal of the second duty ratio generated by so that the first duty ratio is applied to the recording of the information while the second duty ratio is applied to the erasing of the information.

Description

Laser Power Modulation Circuit for Recordable Optical Discs

1A and 1B are circuit diagrams and waveform diagrams illustrating a laser power modulation circuit for a recordable optical disc according to a conventional example.

2 shows a laser power modulation circuit for a recordable optical disc according to a preferred embodiment of the present invention.

FIG. 3 is a view showing waveforms generated in the main part of the laser power modulation circuit for a recordable optical disc according to the preferred embodiment of the present invention shown in FIG.

* Explanation of symbols for main parts of the drawings

11: recording level setting unit 13: erasing level setting unit

15: first switching element 17: reproduction level setting section

19: second switching element 21: third switching element

23: laser drive unit 25: comparator

29 transistor 31 laser diode

40,42: first and second duty converter 44,50: first and second switch

46: level setting section 48: playback level setting section

50: adder 54: laser drive unit

The present invention relates to a laser power control circuit for an optical disc capable of recording / reproducing information, and more particularly, to modulation of laser power applied when recording / reproducing information on a phase-converting disc capable of repeating recording / reproducing of information. The present invention relates to a laser power modulation circuit for a recordable optical disc which modulates a duty ratio of a signal in two stages so that an appropriate information recording condition can be selected and stable information can be recorded.

At present, an optical disc capable of repeatedly recording and reproducing data by a user has been proposed, and a phase conversion disc to which a phase change method based on recording information is applied to an information recording surface has been proposed. The principle of data recording for optical discs that can be repeatedly played back and recorded is to apply a laser power of approximately tens of mW to irradiate light onto the optical disc surface to raise the temperature of the optical spot portion above the recording temperature, In this state, the position of the optical spot is moved by the rotation of the optical disk, whereby the portion irradiated with the optical spot is quenched to be in an amorphous state, and when erased, light is applied to the optical disk surface by applying a laser power of about 10 mW. Irradiated to allow the temperature of the light spot portion to rise to the erasing temperature, whereby the optical spot is rotated by the rotation of the optical disk. By ensuring that the mobile is located immediately before the light spot on the irradiated portion is slowly cooled, and to amorphous state, the recording / erasing of the information executed by such action.

Then, the reproduction principle applies a laser power of approximately 0.6 mW lower than the laser power applied at the time of recording the information to irradiate the light on the optical disk surface, and receives the difference in reflectance according to the state (crystalline, amorphous) of the material on the disk. Playback is performed by recognizing and signaling the element.

Therefore, in order to record information on an optical disk capable of recording such information and to reproduce the recorded information, laser power set to different levels must be applied. FIG. 1 modulates laser power for such a phase-converted optical disk. An example of the configuration of a laser power modulation circuit for an optical disc for enabling recording / erasing and reproduction of information is shown.

That is, according to the laser power modulation circuit for an optical disc according to the conventional example shown in FIG. 1, a recording level setting unit for setting a recording level of information when information is recorded on the information recording surface of the optical disc by a phase conversion method. (11) and an erasing level setting section 13 for setting an erasing level of information in the case of recording information by the recording level provided by the recording level setting section 11, and the data structure of the information to be recorded. Is applied between the recording level applied by the recording level setting section 11 and the erasing level set by the erasing level setting section 13 to switch the EFM-modulated recording signal. One switching element 15 is configured.

In addition, the laser power modulation circuit for an optical disc shown in FIG. 1 is switched by a reproduction level setting unit 17 for setting a reproduction level for reproducing information recorded on the optical disc, and by the first switching element 15. FIG. The output recording / erasing level and the reproduction level output from the reproduction level setting section 17 are set by a signal (REC; information recording mode designation signal) designating a processing mode (information recording mode or reproduction mode) for the corresponding optical disc. The switching control outputs the output of the recording / erasing level switched by the first switching element 15 when the information recording mode designation signal REC is input, while the reproduction level is reproduced when the information on the optical disc is reproduced. The second switching element 19 switched to the reproduction level set by the setting unit 17, for turning on / off the laser light in the laser light source for recording / reproducing information on the optical disk. In a state where the third switching element 21 and the third switching element 21 which are switched to the second switching element 19 side by the control signal RS ON / OFF are connected to the second switching element 19 side. And a laser driver 23 for driving a laser light source with a laser power corresponding to a recording / erasing level of information applied through the first switching element 15 or a reproduction level set by the reproduction level setting unit 17. It is configured by.

In addition, the laser driver 23 has an inverting input terminal (-) connected to the third switching element 21 via a resistor 24 and a resistor 26 and a corresponding laser driver 23 at the non-inverting input terminal (+). A PNP type transistor having a diode (27) for monitoring the laser light driven and radiated therein, the reference potential of which is set, and a base connected to the output side of the comparator (25) via a resistor (28). (29), the power supply potential Vcc is connected to the emitter side of the transistor 29 via a resistor 20, and the laser diode 31 as a laser light source is connected to the collector side.

According to the laser power modulation circuit of a recordable optical disc according to the related art, the control signal REC is set to, for example, a low level when the information on the optical disc is reproduced, so that the second switching element 19 reproduces. It is switched to the level setting section 17, so that the regeneration level set by the regeneration level setting section 17 is transmitted to the laser driver 23 via the second switching element 19 and the third switching element 21. Is approved. Therefore, in the laser driver 23, the regeneration level applied via the resistor 24 is applied to the inverting input terminal (-) of the comparator 25 so that the output of the comparator 25 is set to a low level, and the low level When the resistor 28 is applied to the base of the transistor 29, the transistor 29 is turned on to radiate the laser diode 31 by the power supply Vcc to reproduce the information recorded on the optical disk. Will run.

On the other hand, when recording / erasing information in the disc recording / reproducing system which handles the optical disc while the power is turned on (t1 time point in FIG. 1 (b)) for recording or reproducing the information on the optical disc. The EFM modulated recording signal is applied to the first switching element 15, and a control signal REC for controlling information recording is applied at a high level to the second switching element 19 to control radiation of laser power. Laser ON / OFF (RS ON / OFF; t2 time point in FIG. 1 (b)) is applied, and accordingly, the information recording level set in the recording level setting section 11 (a in FIG. ) And the information erasing level lower than the information recording level set by the erasing level setting section 13 (see (b) of FIG. 15 is switched in response to the EFM write signal applied to the second switching element 19 and the third switch. It is applied to the laser driver 23 via the sub-element 21, so that the laser driver 23 is adapted to the output of the comparator 25 based on the detection signal from the photodiode 27 for laser light monitoring. The transistor 29 is switched so that the laser diode 31 is operated so that laser light of a level for erasing / writing information is emitted, and the EFM modulated recording signal on the information recording surface of the optical disc by such laser light. A pit corresponding to the pit is formed to record information.

By the way, according to the laser power modulation circuit for the optical disc shown in FIG. 1, three levels of level setting (see waveform in (b) of FIG. 1 (b)) are performed when recording / reproducing information on the optical disc. Further, the pits formed on the information recording surface of the optical disc by such three levels of levels are recorded in a nonuniform pattern as a whole as shown in (c) of FIG. 1 (b), so that the error information can be read when the information is reproduced. There is concern that it will be caused.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when information is recorded on an optical disc capable of repetitive recording / reproducing of information, a pulse signal having a duty ratio variable with respect to the information recording / erasing level is generated to record information. It is an object of the present invention to provide a laser power modulation circuit for a recordable optical disc which allows / erasing to be performed by a pulse signal having a single step.

In order to achieve the above object, according to a preferred embodiment of the present invention, the information recording / erasing signal having different levels and the laser power based on the information reproduction signal are modulated and output for an optical disc capable of repeatedly recording / reproducing information. A laser power modulation circuit for an optical disc, comprising: first duty conversion means for receiving a clock signal synchronized with information to be recorded on the optical disc to generate a signal having a first duty ratio, and a clock signal synchronized with the information to be recorded. Second duty converting means for generating a signal having a second duty ratio based on the switching, and switching in response to the information to be written to switch the signal having the first duty ratio and the signal having the second duty ratio in a switching manner; For the first switching means, the signal having a first duty ratio and the signal having the second duty ratio that is selectively output by the switching action of the first switch means Level setting means for setting a recording / erasing level of information on the basis of a recording control signal of information, reproducing level setting means for setting an information reproduction level for reproducing information recorded on the optical disc, and the information set in the level setting means. An addition means for adding and processing the recording / erasing level and the reproduction level of the information set in the reproduction level setting means, and a recording comprising a second switching means for switching control of the application to the laser drive means of the level added by the addition means. There is provided a laser power modulation circuit for an optical disc.

Preferably, the signal of the first duty ratio generated by the first duty conversion means has a duty ratio that is larger than the signal of the second duty ratio generated by the second duty conversion means, and the first duty ratio is a record of information. While the second duty ratio is applied to erasing information.

According to the laser power modulator circuit for a recordable optical disc according to the present invention configured as described above, when information is recorded on an optical disc capable of repeating recording / reproducing of information, it has different duty ratios in the information recording section and the erasing section. As the pulse ratio is generated and applied to the information recording / erasing, only a signal of two levels of information recording / erasing level is generated, thus simplifying the configuration of the laser power modulation circuit for recording / erasing the entire information and recording the information. Pits can also be formed in a normal pattern.

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

2 is a diagram showing a laser power modulation circuit for a recordable optical disc according to a preferred embodiment of the present invention.

In the figure, reference numeral 40 denotes a first duty converter which generates a signal having a first duty ratio by receiving a clock signal CK synchronized with information to be recorded on an optical disc capable of repeating recording / reproducing of information. The signal having the first duty ratio is set to the information recording level applied to the recording section of the information on the optical disk.

Further, 42 is a second duty converter which generates a signal having a second duty ratio based on the clock signal CK synchronized with the information to be recorded on the optical disc, which is generated by the second duty converter 42. The second duty ratio signal is generated with a duty ratio smaller than the first duty ratio of the signal generated by the first duty converter 40 and is set to an information erasing level applied to the erasing section of the information.

44 is a signal having a first duty ratio generated in the first duty converter 40 by switching in response to information DATA to be recorded on the optical disc, and is generated in the second duty converter 42. A first switching device for switching a signal having a second duty ratio is shown.

Reference numeral 46 denotes recording of information on the basis of the recording control signal REC of the information on the signal having the first duty ratio and the signal having the second duty ratio selected and output by the switching action of the first switching means 44. Indicates a level setting section for setting the erasing level, and 48 indicates a reproduction level setting section 48 for setting the information reproduction level for reproduction of the information recorded on the optical disc.

50 denotes an adder for adding and processing the recording / erasing level of the information set in the level setting section 46 and the reproduction level of the information set in the reproduction level setting section 48, and 52 denotes an adder. A second switching element that performs a switching action for applying a level to the laser driver 54, wherein the laser driver 54 has a configuration similar or identical to that of the laser driver 23 described in FIG. The second switching element 52 is switched by a laser ON / OFF signal RS ON / OFF provided from a control means (not shown).

Next, the operation of the laser power modulation circuit for a recordable optical disc according to the present invention configured as described above will be described with reference to the waveform diagram shown in FIG.

First, in the case of reproduction of information on an optical disc, a laser ON / OFF signal (RS / ON / OFF) is applied from the control means for radiation of the laser light by the laser driver 54 for reproducing the information (Fig. 3 t11). Period), the second switching element 52 is switched from the ground potential to the adder 50 side, and in this state, the regeneration level set by the regeneration level setting unit 48 is added to the adder 52 and the second switching device. As the device 50 is applied to the laser driver 54, the laser driver 54 generates a laser of information regeneration level power similarly to the operation of the laser driver 23 described with reference to FIG. Light is generated and irradiated to the optical disc.

On the other hand, when recording / erasing information on the optical disk, the first switching element 44 is provided to the first switching element 44 while a laser ON / OFF signal RS ON / OFF is applied to the second switching element 52. The EFM modulated recording signal DATA shown in FIG. 3 (a) is applied, and the information recording control signal REC is applied to the level setting section 46, and the first and second duty converters 40 are applied. When the clock signal CK (Fig. 3 (b)) synchronized with the write signal DATA is applied to the signal 42, the first duty converter 40 uses a third signal based on the clock signal CK. While the signal having the first duty ratio of the waveform shown in FIG. (C) is generated, in the second duty converter 42, the first duty converter 40 shown in FIG. A signal of the second duty ratio shown in FIG. 3D having a duty ratio smaller than the first duty ratio of the generated signal is generated.

The signals of the first and second duty ratios generated by the first and second duty converters 40 and 42 are controlled by the EFM modulated recording signal DATA of the waveform shown in FIG. Is applied to the level setting section 46 by switching to the first setting device 44, and the level setting section 46 responds to the write control signal REC of the information. The signal of the first duty ratio and the signal of the second duty ratio, which are output in a switchable manner, are combined to correspond to the recording signal DATA having different duty ratios shown in FIG. The set level is output.

The recording / erasing level of the information generated by the level setting section 46 is added to the playback level of the playback level setting section 48 via the adder 50 and then switched by the second switching section 52. Is applied to the laser driver 54, and accordingly, in the t12 and t14 periods of FIG. 3, the laser light is radiated with power at a level at which information is recorded on the optical disc, while the t13 period of the third FIG. Is applied so that the laser light is radiated at a power of a level at which information on the optical disc is erased.

Therefore, according to the laser power modulation circuit for a recordable optical disc according to the present invention, the duty ratio for the modulation signal of the laser power applied when recording information on the optical disc capable of repeating recording / reproducing of the information is modulated in two stages. Therefore, it is possible to select an appropriate recording condition of the information, and the information recording pit is formed in a balanced pattern, thereby making it possible to record stable information.

Claims (2)

An optical power laser power modulation circuit for modulating and outputting an information recording / erasing signal having different levels and a laser power based on the information reproducing signal for an optical disk capable of repeating recording / reproducing of information, the information to be recorded on the optical disk. A first duty conversion means (40) for receiving a clock signal synchronized with and generating a signal having a first duty ratio, and generating a signal having a second duty ratio based on a clock signal synchronized with the information to be recorded. A second duty conversion means (42), the first switching means (44) for switching in response to the information to be recorded to switch output the signal having the first duty ratio and the signal having the second duty ratio, Recording / erasing of information based on a recording control signal of information on the signal having the first duty ratio and the signal having the second duty ratio selectively outputted by the switching action of the first switching means 44 Level setting means (46) for setting the information, reproduction level setting means (48) for setting the information reproduction level for reproduction of the information recorded on the optical disc, and recording / erasing level of the information set in the level setting means (46); Second switching means for switching and controlling the application to the addition means 50 for adding and processing the reproduction level of the information set by the reproduction level setting means, and the laser driving means 54 at the level added by the addition means 50 ( 52. A laser power modulation circuit for a recordable optical disc, characterized in that it comprises a. According to claim 1, wherein the signal of the first duty ratio generated by the first duty conversion means 40 has a duty ratio greater than the signal of the second duty ratio generated by the second duty conversion means 42, Wherein the first duty ratio is applied to the recording of information while the second duty ratio is applied to the erasing of the information.