KR19980079018A - Laser Output Control of Digital Video Disc Recorder - Google Patents

Abstract

The present invention relates to a laser output control apparatus for a digital video disc recorder, comprising: a recording waveform generation unit (10) for generating a recording waveform signal in accordance with input data and generating a reference level signal according thereto; A laser diode driver 20 for driving the laser diode 30 according to the recording waveform signal; An amplifier 80 which amplifies the optical signal output from the laser diode 30 with a predetermined amplification gain and outputs the same to the disk D; A light detector 50 for detecting the amount of light of the optical signal reflected from the disk D; An error detection unit 60 for comparing the light amount signal detected by the light detection unit 50 with the reference signal provided from the recording waveform generation unit 10 and detecting the error signal; A compensator (70) for providing a compensation signal according to the error signal detected by the error signal detector (60) to the amplifier (80) to adjust the amplification gain to compensate for the laser output; A comparator 100 for comparing the light amount signal detected by the light detector 50 with a preset reference signal and generating a logic signal according to the light amount signal greater than the reference signal; A control unit 110 generating a control signal according to the logic signal if provided; When the control signal is provided from the control unit 110 is switched to provide a power supply (Vcc) to the amplifier 80 to turn off the amplifier 80 by switching the switching unit 90 to block the output light of the laser diode (30) Included and configured.

Description

Laser Output Control of Digital Video Disc Recorder

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital video disc recorder, and more particularly, to a digital video disc recorder capable of protecting a laser diode and a disc when a relatively large laser is output due to a difference in the amount of reflected light on a disc and a control error in laser output power. It relates to a laser output control device of the.

With the development of audio and video media, optical disc systems have been developed for recording and reproducing video and audio data on semi-permanent optical discs.

Such an optical disc system reproduces an image and / or an audio recorded on an optical disc and outputs it through a screen and / or a speaker, and has a higher signal-to-noise ratio than conventional image and / or audio reproducing apparatus, resulting in better image quality and / or Or it can reproduce the signal with sound quality, it does not generate noise due to irregular reproduction and modulation, very low distortion, no ghost and random access, so it is rapidly developed and widely distributed. There is a trend.

In addition, the optical disc used for such functions as the playback and recording in the optical disc system is a play-only type in which the user can only play information such as a CD, CD-ROM, and a video disc, depending on the function and purpose of recording. Thereafter, the recorded information can be divided into an additional recording type which can be read many times but cannot be erased and rewritten, and an erased rewrite type that can repeatedly record, erase and reproduce the information.

Play-only type CD is already replacing the existing LP record board in the sound industry, CD-ROM which is a medium that can be searched when necessary by recording a large amount of information that needs to be widely spread such as encyclopedia, and recently in Korea Video discs and the like, which are rapidly expanding, have already been put into practical use and are in the dissemination stage. Additional recordable optical discs can be used for hospitals and large documents that need to store information such as X-rays, NMR-CTs, ultrasound tomography, and patient care cards. It is used for necessary public offices and mineral veins such as mines and oil fields.

The erasing rewritable optical disc has a magneto-optical type and a phase change type. The phase change type is recorded using a crystalline / amorphous reversible change in the process of heating and cooling the micro part of the medium using a laser. I am using a method to read it.

In general, recording of a magneto-optical optical disk causes the coercive force of the heated micro part to be reduced when the magnetic thin film unidirectionally oriented to the thin film surface is momentarily heated to near the Curie temperature by a laser focused light pulse. At this time, only the laser irradiation part heated by the weak magnetic field applied in the direction opposite to the medium magnetization direction is reversed. When the laser pulse is turned off and cooled to room temperature, only this part remains as a stable inverse magnetic domain bit and information is recorded.

The erasing is performed by heating the portion where the information is recorded by the laser beam, and then applying the direction of the external magnetic field at the time of cooling as opposed to at the time of recording to have the original magnetization direction.

On the other hand, reading of the recorded information is performed by using a laser light and a polarizer which are weaker than at the time of recording. When the linearly polarized light is reflected from the surface of the vertically magnetized material, the polarization direction is left with respect to the polarization direction of the incident light when the linearly polarized light is reflected from the surface of the perpendicular magnetized material Use the magneto-optical Kerr effect which rotates to the right and the right, respectively. That is, the polarization direction of the reflected light is rotated counterclockwise when the magnetization direction of the material is downward, and clockwise when it is upward, so that the reflected light passes through the two reflected beams with the analyzer set in advance in a direction that hardly passes the reflected polarization in the unrecorded portion. Then, the reflected light of the unrecorded part has a weak light quantity, and the reflected light of the recorded part passes through the analyzer and is converted into a strong signal of light, which is converted into a digital signal '0' and '1' by using a light detecting element. Will be read.

As described above, a system for recording, erasing, and reproducing the erase rewritable optical disc is commonly referred to as a digital video disk recorder (DVDR).

On the other hand, in a recordable optical disc, a pregroove is formed in a spiral shape in advance, and a land portion is formed between the pregroove and the pregroove, and data can be recorded in the pregroove and the land portion. In the pregroove or land portion, a sync code or absolute address is pre-recorded in the form of a wobble or pit. A recordable area except for an area where the sync code or absolute address is pre-recorded is called a program area. do.

When the digital video disc recorder described above executes a recording function for recording data input from the outside onto a recordable optical disc, a laser diode that outputs light to the disc must be appropriately driven in accordance with the input data. In other words, when the recording function is executed, data must be recorded in the form of pits or the like on the disk surface unlike reproduction, and therefore, stronger laser light must be output on the disk during reproduction.

1 is a schematic block diagram illustrating a laser output control apparatus when executing a conventional recording function. The recording waveform generating unit 10, the laser diode (LD) driving unit 20, the LD 30, the amplifying unit 40, An optical detector 50, an error detector 60, and a compensator 70 are provided.

The operation of the laser output control device when executing the conventional recording function configured as described above will be briefly described.

When the recording function is executed and the recording data to be recorded from the outside is input, the recording waveform generating unit 10 generates a recording waveform signal according to the input recording data, and provides the recording waveform signal to the LD driver 20, and also generates the recording waveform signal. Outputs a reference level signal according to the error detection unit 60.

Then, the LD driver 30 provides a drive signal according to the recording waveform provided from the recording waveform generator 10 to the LD 30, and accordingly, the LD 30 outputs a laser light signal of a predetermined level. The laser light is not immediately incident on the disk D, but is amplified to a predetermined level in the amplifier 40 and at a level at which data can be written to the disk yarn.

At the same time, the light detector 50 detects the amount of light reflected at the same time as recording the data on the disk D and provides it to the error detector 60, and the error detector 60 is the recording waveform generator 10. The reference level signal provided from the signal is compared with the light amount signal provided from the light detector 50, and an error signal corresponding to the difference is detected and provided to the compensator 70.

Then, the compensator 70 provides a compensation signal for compensating the error signal provided from the error detector 60 to the amplifier 40 to adjust the amplification gain of the amplifier 40 so as to increase the output power of the laser light or Adjust it weakly.

However, the conventional laser output control device as described above simply detects the error signal according to the light quantity signal detected by the light detector 50 and controls the laser output to compensate for the error signal, thereby detecting the light reflected from the disk. When an error occurs, since a laser of higher power is output to the disk when the recording function is executed, there is a problem that the laser diode and the disk may be damaged.

Accordingly, the present invention has been devised to solve such a problem in the related art, and an object of the present invention is to prevent damage to the laser diode and the disk by more appropriately controlling the output of the laser light when the recording function is executed in the digital video disc recorder. The present invention provides a laser output control device of a digital video disc recorder.

According to a preferred embodiment of the present invention for achieving this object, a digital video disc for preventing damage to a laser diode and a disc outputting laser light due to excessive laser output light when performing a recording function in a digital video disc recorder An apparatus for controlling a laser output, comprising: a recording waveform generation section for generating a recording waveform signal in accordance with data input for recording on the disk, and for generating a reference level signal in accordance with the recording waveform, and from the recording waveform generation section; A laser diode driver for driving the laser diode according to the recording waveform signal, an amplifier for amplifying the optical signal output from the laser diode with a predetermined amplification gain, and outputting the optical signal to the disc; Of the reflected light signal An optical detector for detecting the amount of light, an error detector for comparing the light amount signal detected by the optical detector with a reference signal provided from the recording waveform generator, and detecting the error signal, and an error signal detected by the error detector. A compensator for compensating the laser output by adjusting the amplification gain by providing a compensation signal to the amplifying unit, and comparing the light quantity signal detected by the light detector with a preset reference signal. A comparator for generating a logic signal, a controller for generating a control signal according to the logic signal provided from the comparator, and one input terminal connected to the compensator, and a predetermined power supplied to the other input terminal. Has two input stages, the output stage of which is connected to the amplifying unit and is provided from the controller. When a signal is provided in the switching unit it includes switching to block the output light of the laser diode by the amplifying unit off by providing the power supply portion and the amplifier configuration.

1 is a schematic block diagram showing a laser output control apparatus of a conventional digital video disc recorder.

2 is a block diagram showing a laser output control apparatus of a digital video disc recorder according to a preferred embodiment of the present invention.

<Description of the code | symbol about the principal part of drawing>

10: recording waveform generating unit 20: LD drive unit

30: LD40 :, 80: amplification part

50: light detector 60: error detector

70: compensator 90: switching unit

100: comparison unit 110: control unit

D: Disk Q: Transistor

R: Resistance Vcc: Power

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

2 is a block diagram showing a laser output control apparatus of a digital video disc recorder according to a preferred embodiment of the present invention.

As shown in FIG. 2, the present invention includes a recording waveform generator 10, an LD driver 20, an LD 30, an amplifier 80, an optical detector 50, an error detector 60, and a compensator ( 70), a switching unit 90, a comparator 100, and a controller 110.

The recording waveform generating unit 10 generates a recording waveform signal in accordance with data input from the outside for recording on the disk D, and provides the recording waveform signal to the LD driver 20, and provides a reference level signal according to the recording waveform signal. Occurs in the error detection unit 60.

Then, the LD driver 20 drives the LD 30 according to the recording waveform signal provided from the recording waveform generator 10 so that the LD 30 amplifies the optical signal having a predetermined level according to the recording waveform signal. To print). Accordingly, the amplification unit 80 amplifies the optical signal output from the laser diode 30 to a predetermined amplification gain, that is, the amplification gain set according to the compensation signal provided from the compensator 70 and outputs it to the disk D. The amplifier 80 is composed of resistors R1 and R2 and npn type transistor Q.

In addition, the light detector 50 detects the amount of light of the optical signal output from the amplifier 80 and reflected from the disk D, and provides the light detector 50 to the error detector 60 and the comparator 100.

Accordingly, the error detector 60 compares the light quantity signal detected by the light detector 50 with the reference signal provided from the recording waveform generator 10 to detect the error signal and provides it to the compensator 70.

The compensator 70 compensates the laser output by adjusting the amplification gain by providing a compensation signal according to the error signal detected by the error detector 60 to the amplification unit 80, and the compensation signal of the compensator is the amplification unit 80. The amplification degree of the transistor Q is determined by inputting to the base terminal of the transistor Q which constitutes.

On the other hand, the comparator 100 compares the light quantity signal detected by the light detector 50 with a preset reference signal, and when the light quantity signal is larger than the reference signal, that is, an error signal is generated in the reflected light so that the laser power is a disk or LD The controller 100 generates a logic signal, for example, a 'high' or a 'low' signal, which is large enough to damage the 30.

In addition, when the logic signal is provided from the comparator 100, the controller 110 generates a switching control signal according to the switching unit 90.

On the other hand, the switching unit 90 has one input terminal connected to the compensator 70 and the other input terminal having two input terminals to which a predetermined power supply Vcc, that is, 5V power supply, is supplied. 80 is provided. In general, the compensation signal of the compensator 70 is provided to the amplifier 80, and when a switching control signal is provided from the controller 110, the transistor Q is configured to switch to the amplifier 80. 5V power is supplied to the base terminal of the amplifier to turn off the amplifier 80 to block the output light of the laser diode 30 to prevent the disk and the LD 30 from being damaged.

As described above, the present invention has an effect of protecting the disk and the laser diode by blocking the error if the output of the laser light becomes large enough to damage the disk or the laser diode.

Claims (2)

In the laser output control apparatus of the digital video disc for preventing the damage of the laser diode 30 and the disc D outputting the laser light due to the excess of the laser output light when the recording function is executed in the digital video disc recorder, A recording waveform generation section (10) for generating a recording waveform signal in accordance with data input for recording on said disk (D), and generating a reference level signal in accordance with the recording waveform; A laser diode driver 20 for driving the laser diode according to a recording waveform signal provided from the recording waveform generator 10; An amplifying unit (80) for amplifying the optical signal output from the laser diode (30) with a predetermined amplification gain and outputting it to the disk; A light detector (50) for detecting the amount of light of the optical signal output from the amplifier (80) and reflected from the disk (D); An error detection unit (60) for comparing the light amount signal detected by the light detection unit (50) with a reference signal provided from the recording waveform generation unit (10) and detecting the error signal; A compensator (70) for providing a compensation signal according to the error signal detected by the error detector (60) to the amplifier (80) to adjust the amplification gain to compensate for the laser output; A comparison unit (100) for comparing the light amount signal detected by the light detector (50) with a preset reference signal and generating a logic signal according to the light amount signal when the light amount signal is larger than the reference signal; A control unit 110 for generating a control signal according to the logic signal from the comparison unit 100; One input terminal is connected to the compensator and the other input terminal has two input terminals to which predetermined power is supplied. The output terminal is connected to the amplifying unit 80 to switch when a control signal is provided from the control unit 110. And a switching unit 90 to block the output light of the laser diode 30 by providing the power to the amplifying unit 80 to turn off the amplifying unit 80. Device. The apparatus of claim 1, wherein the amplifying unit (80) comprises npn transistors.