KR100617231B1 - Apparatus for controlling optical output of optical record/player - Google Patents

Abstract

An optical output control apparatus of an optical recorder for maintaining a constant recording and reproduction characteristic in a non-continuous recording mode disc in which recording and reproduction are alternately performed by a recording command. In particular, a reproduction area and a recording area including a header area are provided. By storing the sample value in advance and holding the section with the sample value at the time of switching, the erase power can always be maintained at a constant level in the recording area and the read power in the reproduction area including the header area. However, even if the disk reflectance changes due to temperature characteristics, each power can be restored to its original state, thereby preventing deterioration of recording and playback characteristics.

Sample, hold, ALPC

Description

Apparatus for controlling optical output of optical record / player

1 is a block diagram of a configuration related to recording in a typical optical disc record player;

2A to 2C are timing diagrams for implementing three levels of write strategy in FIG.

3 is a graph showing the relationship between the output power and the current of the laser diode according to the temperature change

4 shows the arrangement of a header preformatted at the start of each sector in a typical rewritable disc.

5A to 5D are timing diagrams showing a recording process in a non-continuous recording mode disc.

6 is a block diagram showing the configuration of an optical output control apparatus of the optical recorder according to the present invention.

(A) to (e) is an operation waveform diagram of each part of FIG.

Explanation of symbols for main parts of the drawings

100: optical disk 102: optical pickup

200: encoder 300: playback sample & hold

301: playback switching unit 302: playback noise removing unit                 

303403: Differential Amplifier 400: Record Sample & Hold

401: recording switching unit 402: recording noise removing unit

500: control unit 501: ADC

502: Micom 503: DAC

600: amplifier

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to light output control of an optical recorder, and more particularly, to an optical output control apparatus of an optical recorder to maintain a constant output of a laser diode (LD) regardless of recording / reproducing.

Generally, in the case of an optical recording medium, for example a rewritable optical disc, the recording medium is usually formed of a phase change material. Therefore, the light focused at the optical head is converted into heat, and this heat changes the state of the phase change recording medium so that the reflection amount is changed, thereby forming a mark on the phase change type disk to record the pits. Here, forming a mark by a predetermined length on the disk is referred to as write strategy.

At this time, the laser light is incident on the opposite side of the reflective surface with a pit. Therefore, the pit appears as a projection when viewed from the laser incident side.

The pit has a width of 0.4 to 0.6 mu m, the length of one pit and the interval between the pit and the pit in 9 steps from 3T to 11T for a compact disc (CD) and 12T to 14T for a digital multifunction disc (DVD). Are divided into stages. Here, T means the length of one clock pulse, 3T means three clock pulses, and 11T corresponds to the length of 11 clock pulses.

In the pit group of the track wound in a spiral, there is a specific pit array at a certain interval, and the pit array that exists regularly has a synchronization signal, and the block from the synchronization signal to the next synchronization signal is called a frame. do. In this case, one frame includes a plurality of symbol data.

FIG. 1 is a block diagram illustrating a recording in a general optical disc recorder. When a signal for recording on the disc 101 is input to the encoder 103, the encoder 103 converts the record signal into a 16-bit digital signal. The process of converting and dividing the upper 8 bits and the lower 8 bits (this is called a symbol) into frame units is performed.

Then, an 14-bit code value corresponding to 8-bit symbol data is read from a code table of a memory (not shown) to perform EFM (Eight to Fourteen Modulation) modulation for converting 8-bit symbol data to 14 bits. That is, code tables for EFM or EFM + are mapped in memory.

The EFM or EFM + modulated data has a non-return-to zero, inverted modulation as shown in FIG. 2A by adding a margin bit (eg, 3 bits) to remove the DC component after modulation. After that, it is input to the LD driver 106. The NRZI modulation is a modulation rule for inverting data in a signal of '1'. That is, if only '1' is met, the current state is reversed.

On the other hand, the write power generation unit 104 generates the power of the laser diode LD for the data to be recorded, converts it to analog, and outputs the power to the LD driver 106 through the write level adder 105. Here, the recording power differs depending on the disc state depending on the length of the mark to be formed.

When the NRZI modulated data is input from the encoder 103, the LD driver 106 modulates the power of the laser diode LD to power at the time of recording, that is, converts the LD drive voltage into an LD drive current, thereby optical pickup. The LD of 102 is driven. Thus, the NRZI modulated signal forms a pit as shown in FIG. In other words, data is recorded on the optical disc 101.

In this case, when data is recorded by a single NRZI modulated pulse, the shape of the pit is formed as a tear drop due to the thermal characteristics of the disk itself, or the formation of the mark is distorted due to the latent heat characteristic of the disk, thereby preventing the diffusion of such heat and the shape of the pit. Multi-pulse modulation is also used to form a smooth oval. This is to perform multipulse modulation in which a single pulse is divided into several pulses and scanned on a disk by turning on / off several times in a single NRZI modulated pulse as shown in FIG.

In addition, the light strategy implemented by the multi-pulse is usually in the form of 2 levels, 3 levels, 4 levels. In the case of a rewritable disc, the power of each level is usually the strongest in the write power, followed by erase power, read power, and cooling power. The levels of the read power and the cooling power may be the same or different.

On the other hand, the LD light output changes remarkably with temperature. As shown in FIG. 3, the recording power mW decreases as the temperature increases, and the recording power mW rises as the temperature decreases. Therefore, in order to keep the recording power mW constant, the LD driver 106 must supply more current (mA) to the LD as the temperature increases, and supply less current (mW) as the temperature decreases.

To this end, the optical pickup 102 feeds back a portion of the LD power to the front monitoring PD of the auto laser power control (ALPC) feedback unit 107. The ALPC feedback unit 107 outputs the ± power level according to the LD power detected by the monitoring PD (MPD) to the recording level adder 105 to add to the recording power generated by the recording power generation unit 104. The LD output power is kept constant during recording / playback. Here, the ALPC feedback unit 107 may be provided in the optical pickup 102.

As such, when the LD output power is controlled by instantaneous feedback, this is called ALPC.

Therefore, if the above-described ALPC is performed, no big problem occurs in the disk of the continuous recording mode. Here, the continuous recording mode is an example of a disc such as a DVD-R or a DVD-RW, in which recording power continues to be input until recording of one file is completed. In other words, only recording is performed by a recording command. In this case, it is necessary to follow with only a certain response characteristic at an initial stage.

However, there may be a problem in the discontinuous recording mode in which the header section exists, such as a DVD-RAM. That is, in the case of the discontinuous recording mode, recording and reproduction are alternately performed by the recording command.

For example, in the case of a DVD-RAM, a signal track having a structure of lands and grooves is provided to enable tracking control even on a blank disc in which no information signal is recorded, and to increase recording density. For this purpose, information signals are recorded in tracks of lands and grooves, respectively. At this time, since there is no information on the first disk, disk control and recording are impossible. For this purpose, disc tracks are created in lands and grooves, and information is recorded along the tracks. Information for random access and rotation control is recorded separately on the disc, so that tracking control can be performed on a blank disc in which no information signal is recorded. To do it.

The control information may be recorded by pre-formatting the header area at each sector at the start of the sector. At this time, the header area preformatted at the start position of each sector is composed of four header fields (header 1 field and header 4 field) again in the case of DVD-RAM. Here, the header 1,2 field and the header 3,4 field are alternately arranged from the track center. FIG. 4 is an example of the structure of the header field for the first sector in one track. That is, the phases of the header 1,2 fields are inversely opposite to the header 3,4 fields, and the phases of the tracking error signals detected in the header 1,2 fields and the header 3,4 fields are opposite to each other.                         

Therefore, recording and reproduction must be performed alternately by a recording command. That is, in the recording command as shown in Fig. 5A, sector areas other than the header area and the header area, that is, recordable areas (hereinafter, referred to as recording areas), alternately exist as shown in Fig. 5B. Therefore, when a recording command is input, reproduction is performed in the header area to detect control information, and recording is performed in the area except the header area, that is, the recording area, using the control information.

At this time, the erasure level must be kept constant in the recording area, and the read level must be kept constant in the header area. In other words, if the erasure level is not properly formed, distortion may occur in the recording pit due to the latent heat characteristic.

For this purpose, a sample & hold circuit is used. As a conventional example, a charge / discharge circuit is used as the sample & hold circuit.

If the LD output fed back from the optical pickup 102 to the ALPC feedback unit 107 when the response characteristic is good is the same as in FIG. 5C, the read level is sampled in the header area as shown in FIG. 5D. & Hold, and in the recording area, the erasure level is sampled & hold as shown in Fig. 5E.

At this time, in the holding period, the response characteristic should be slow to lower the band, and the response characteristic should be fast at the moment of switching. That is, in the disc of the discontinuous recording mode, since the header area exists, the read / write section is required to be switched at a very fast time during data recording. For this reason, the switching response characteristic should be fast in the discontinuous write mode.

Therefore, in the disc of the non-continuous recording mode, the response characteristics should be fast and slow when recording data. It is difficult to implement this in the same circuit. In other words, the cost increases and the circuit becomes complicated. In addition, since the conventional sample & hold circuit is an analog circuit, the holding level is changed in the reproduction and recording sections as shown in FIGS. 5 (d) and 5 (e). In other words, the sample & hold circuit samples the immediately preceding value and then holds the value. The fast switching causes the rocking of the sample section and the holding section, causing the header to be distorted, which can result in poor RF reproduction.

Therefore, when the response characteristic is slow at the switching moment, the header region may not be properly reproduced and distortion may occur when the header region is reproduced.

If the header area is not reproduced correctly, the physical identification number (PID) cannot be recovered correctly, resulting in deterioration of recording characteristics.

The present invention has been made to solve the above problems, and an object of the present invention is to store the hold level in advance, and then hold the corresponding section with the hold level stored immediately at the switching moment, thereby keeping the hold level constant in the corresponding section. An optical output control apparatus of an optical recorder is provided.

The optical output control apparatus of the optical recorder according to the present invention for achieving the above object, includes a laser diode (LD) drive for performing the recording and reproduction, the recording and reproduction are alternately performed by a recording command In the optical output control apparatus for maintaining the recording and reproducing characteristic on a disc, a reproducing area including a recording area and a header area while generating a recording pulse according to the data to be recorded when the recording command is input and outputting the recording pulse to the LD driver. An encoder that generates a lead-on pulse that separates a signal and a light sample & hold (S / H) pulse that separates a pit formation period and a blank period from the recording area, and amplifies the feedback part of the optical output of the laser diode A sample value and a holding value by an optical output feedback unit for outputting a sample value and a read-on pulse output from the encoder Are alternately selected to output to the LD driver, and a sample and hold are alternately selected by the write S / H pulse output from the encoder to output and output to the LD driver. And the feedback sample and hold section and the recording sample & hold section are fed back the sample values by the read-on pulse and the write S / H pulse. It characterized in that it comprises a control unit for providing each holding value to.

The control unit maintains a sample value fed back from the reproducing sample & hold unit during recording by turning on / off of the read-on pulse, and outputs the holding value to the reproducing sample & hold unit during reproduction. It is characterized in that the sample value fed back from the recording sample & hold part is maintained when the pit is formed by the on / off of the H pulse, and is output as the holding value to the recording sample & hold part after the pit formation is completed.

The LD driver is configured to hold the read power with a holding value output through the reproducing sample & hold unit in the reproducing area, and to hold the erase power with a holding value output through the recording sample & hold part in the blank period of the recording area. It is characterized by.

Other objects, features and advantages of the present invention will become apparent from the following detailed description of embodiments taken in conjunction with the accompanying drawings.

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

Fig. 5 is a block diagram of the optical output control apparatus of the optical recorder according to the present invention, which includes an optical disk 101 having a prepitted header area, and an optical pickup for recording and reproducing information on the optical disk 101. (102), RF and servo error generation unit 108 for generating RF and servo error signals from the electrical signal output from the optical pickup 102, and receives the control signal from the RF and servo error generation unit 108 An encoder 200 for generating and outputting a write pulse switching signal, read on pulses, write sample & hold pulses (write S / H) pulses, and regeneration to be switched by the read on pulses to sample & hold the read power. A sample & hold unit 300, a write sample & hold unit 300 that is switched by the write S / H pulse to sample & hold erasure power, and the read on pulse, the write S / H pulse, and the regeneration And recording samples & hold sections (300,400) The control unit 500 is configured to determine each hold level in the header / recording area by using the fed-back signal, and then output them to the reproduction and record samples & hold units 300 and 400, respectively.

Here, the LD driver 102-1 may be configured in the optical pickup 102, or may be configured separately from the optical pickup 102, and it is assumed that the LD driver 102-1 is configured in the optical pickup 102.

In addition, 102-2 is a current-voltage (IV) converter which converts the output current of MPD (Monitering PD), which detects when a part of the LD output is fed back from the optical pickup 102 to a voltage, 600 denotes the above This amplifier amplifies the voltage output from the IV converter 102-2 to a predetermined level.

In the multi-pulse recording method using the LD driving voltage of three levels, the encoder 200 outputs a write pulse, an erase pulse, and a read pulse to the LD driver 102-1, and the power generation unit 700 each. Power, for example, write power, erase power, and read power, are generated and output to the LD driver 102-1.

In addition, the reproduction sample & hold unit 300, the recording sample & hold unit 400, and the control unit 500 correspond to an ALPC unit.

Here, the regeneration sample & hold unit 300 is switched by a read-on pulse provided by the encoder 200 to reproduce a sample level output from the amplifier 600 or a hold level output from the control unit 500. LD driving unit 102 by differentially amplifying the output of the switching unit 301, the reproduction noise removing unit 302 for removing noise of the signal output through the reproduction switching unit 301, and the reproduction noise removing unit 302 And a differential amplifier 303 for outputting to -1). Here, the output of the reproduction noise removing unit 302 is output to the differential amplifier 303 and fed back to the control unit 500 so that the control unit 500 can determine the hold level.

The recording sample & hold unit 400 is switched by a write S / H pulse provided by the encoder 200 to output a sample level output from the amplifier 600 or a hold level output from the controller 500. The LD driver may perform differential amplification on a write switch 401, a write noise remover 402 for removing noise of a signal output through the write switch 401, and an output of the write noise remover 402. And a differential amplifier 403 for outputting to 102-1. Similarly, the output of the recording noise removing unit 402 is output to the differential amplifier 403 and fed back to the control unit 500 so that the control unit 500 can determine the hold level. Here, the differential amplifiers 303 and 403 receive a reference voltage from the controller 500, and the outputs of the differential amplifiers 303 and 403 are output to the LD driver 102-1.

In addition, the control unit 500 receives an output of the reproduction noise removing unit 302 and the recording noise removing unit 402 and digitizes the analog / digital converter (ADC) 501 and the encoder ( The microcomputer 502 determines the hold level in the header area and the recording area by using the read-on pulse, the write S / H pulse, and the output of the ADC 501. The DAC 503 is configured to analogize the output hold level to be output to the reproduction switching unit 301 and the recording switching unit 401, respectively, and to the LD driving unit 102-1.

In this case, the reproduction sample & hold unit 300 and the recording sample & hold unit 400 are separated in order to cope with high speed during R / W switching.

According to the present invention configured as described above, when a recording command is input by a user, the encoder 200 generates a recording pulse switching signal as shown in FIG. 7A and outputs it to the LD driver 102-1 of the optical pickup 102. . Also, a read-on pulse and a light S / H pulse are generated for the ALPC, and output to the regeneration switching unit 301 of the regeneration sample & hold unit 300 and the microcomputer 502 of the control unit 500, and the write S / H pulse. The H pulse is generated and output to the write switching unit 401 of the record sample & hold unit 400 and the microcomputer 502 of the control unit 500.

Here, the read-on pulse is a signal for distinguishing the header area from the recording area as shown in (b) of FIG. 7, and a low active state indicating that the low state is the header area is taken as an example. That is, the read on pulse is an actual R / W pulse.

In addition, if the NRZI waveform is equal to (c) of FIG. 7 in one sector section, the write S / H pulse is generated in synchronization with the NRZI waveform as shown in (e) of FIG. 7.

FIG. 7D shows a case of recording using multipulse.

That is, the read power is continuously sampled in the period where the read on pulse is high, for example, in the recording area, and the read power is held at the sampled value in the period when the read on pulse is low, for example, in the header area.

In addition, the erasure power is continuously sampled in a section in which the light S / H pulse is high, for example, the section in which the actual pit is formed, and in the section in which the light S / H pulse is low, for example, in the blank section, the eraser power is sampled. Hold.

To this end, the LD output voltage fed back through the IV converter 102-2 in the optical pickup 102 is amplified by the amplifier 600 and then regenerated by the regenerative switching unit 301 of the regenerated sample & hold unit 300. It is provided to the write switching unit 401 of the write sample & hold unit 400. In addition, the controller 500 converts the voltage fed back from the reproduction noise removing unit 302 of the reproduction sample & hold unit 300 and the recording noise removal unit 402 of the recording sample & hold unit 400 to the ADC 501. ) Is input and digitized.

At this time, the microcomputer 502 determines the hold level in the recording area and the header area by the read-on pulse and the write S / H pulse.

If the read-on pulse is high, the micom 502 is a real recording area, and thus the microcomputer 502 is fed back from the regeneration noise removing unit 302 to continuously sample the digitized voltage of the ADC 501 while holding the read power level of the regeneration area. Determine.

At this time, the regeneration switching unit 301 is switched by a read-on pulse. If the read-on pulse is high, the signal output from the amplifier 600 is output to the regeneration noise removing unit 302, and if the read-on pulse is low, The signal output from the control unit 500 is output to the reproduction noise removing unit 302. That is, in the header area, the signal output from the amplifier 600 is at the sample level, and the signal output from the controller 500 is at the hold level.

Therefore, assuming that the read-on pulse is low, a sample level is output through the regeneration switching unit 301, and the sample level is output to the differential amplifier 303 after the noise is removed from the regeneration noise removing unit 302. At the same time, it is fed back to the ADC 501 of the controller 500.

At this time, the microcomputer 502 takes an average while accumulating sample levels for a predetermined period to determine a hold level of the header area, and when the read-on pulse changes to low, sets the average value to the hold level to the DAC 503. The DAC 503 analogizes it and outputs it to the reproduction switching unit 301. At this time, the regeneration switching unit 301 is switched by the read-on pulse and outputs the hold level output from the DAC 503 to the regeneration noise removing unit 302. Therefore, in the header area, that is, the reproduction area, the read power is held at the hold level so that the holding level does not change.

Here, the average value is one embodiment, and the instantaneous value of the signal fed back in the high period of the read-on pulse may be determined as the hold level.

On the other hand, the microcomputer 502 determines the hold level of the recording area while continuously sampling the digitized voltage fed back from the recording noise removing unit 402 when the write S / H pulse is high.

That is, the recording area is divided into a pit forming section and a blank section. In the pit forming section, the erase power is sampled, the hold level is determined using the sampled value, and the erase section is held at the hold level in the blank section. do. Write S / H pulses are used for this purpose.

In this case, the write switching unit 401 is switched by a write S / H pulse. If the write S / H pulse is high, that is, in a pit formation period, the write switching unit 401 is switched by the amplifier 600. If the output signal is output to the recording noise removing unit 402, and the write S / H pulse is low, that is, in the blank period, the recording switching unit 401 selects the signal output from the control unit 500 to reduce the recording noise. Output to reject 402.

Therefore, assuming that the write S / H pulse is high, the sample level is output through the write switching unit 401, and the sample level is the differential amplifier 403 after the noise is removed from the write noise removing unit 402. At the same time as the feedback to the ADC 501 of the control unit 500.                     

In this case, the microcomputer 502 takes an average while accumulating sample levels for a predetermined period to determine the hold level of the recording area. If the write S / H pulse turns low, the microcomputer 502 sets the average value to the hold level and sets the DAC 503. ), And the DAC 503 analogizes it to the write switching unit 401. In this case, the write switching unit 401 is switched by the write S / H pulse to output the hold level output from the DAC 503 to the write noise removing unit 402. Therefore, in the recording area, since the eraser power is held at the holding level, the holding level does not change.

Similarly, the average value is one embodiment, and the instantaneous value of the signal fed back in the high period of the write S / H pulse may be determined as the hold level.

Thus, by storing the sample value in the reproduction area and the recording area including the header area in advance, and holding the corresponding section with the sample value at the time of switching, the erasure level is optimally maintained in the recording area. Lead power can be maintained optimally.

As described above, according to the optical output control apparatus of the optical recorder according to the present invention, the erasure power is always maintained at a constant level in the recording area and the read power in the reproducing area including the header area. Deterioration of recording characteristics can be prevented. In particular, in the case of the disc in the non-continuous recording mode, even if the disc reflectance is changed by the long time recording or the temperature characteristic, each power can be restored to the original state so that no header distortion occurs. Therefore, since the physical identification number (PID) of each sector can be recovered accurately, deterioration of recording and reproduction characteristics can be prevented.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the embodiments, but should be defined by the claims.

Claims (7)

An optical output control apparatus comprising a laser diode (LD) driver for performing recording and reproducing, and for maintaining a constant recording and reproducing characteristic in a disk in which recording and reproduction are alternately performed by a recording command, When a write command is input, a write pulse according to the data to be recorded is generated and output to the LD driver, and a lead-on pulse that separates a recording area and a reproduction area, and a light sample that separates a pit formation period and a blank period from the recording area. An encoder for generating a hold (S / H) pulse; An optical output feedback unit for receiving and amplifying a part of the optical output of the laser diode and outputting the amplified sample value; A reproduction sample & hold unit which alternately selects a sample value and a holding value by the read-on pulse output from the encoder and outputs the sample value and the holding value to the LD driver; A recording sample & hold unit which alternately selects a sample value and a holding value by the write S / H pulses output from the encoder and outputs the sample value and the holding value to the LD driver; And Receive feedback of the sample values from the reproduction sample & hold unit and the recording sample & hold unit by the read-on pulse and the write S / H pulse, and then hold each of the reproduction sample & hold unit and the recording sample & hold unit during recording and playback. And a control unit for providing a value. The method of claim 1, And the reproduction area is a header area. The method of claim 1, wherein the reproduced sample & hold unit A reproducing switching unit which is switched by a lead-on pulse to selectively output a sample value in the recording area and a holding value in the reproducing area; And a reproduction noise removing unit which removes noise of the signal output through the reproduction switching unit and outputs the LD drive unit to feed back to the control unit. The recording sample & hold unit according to claim 1, wherein the recording sample & hold unit A write switching unit which is switched by a write S / H pulse to selectively output a sample value in a pit formation section and a holding value in a blank section; And a recording noise removing unit which removes noise of the signal output through the recording switching unit and outputs the LD driving unit to feed back to the control unit. The method of claim 1, wherein the control unit A sample value fed back from the reproducing sample & hold part is maintained during recording by turning on / off of the read on pulse, and is output as a holding value to the reproducing sample & hold part during reproducing. When the pit is formed by on / off, the sample value fed back from the recording sample & hold part is maintained, and when the pit is formed, the output value is output to the recording sample & hold part as a holding value. controller. 6. The apparatus of claim 5, wherein the holding value is an average value of sample values of a predetermined section. The method of claim 1, wherein the LD drive unit The read area holds the read power with a holding value output through the reproducing sample & hold section, and the erase power is held with a holding value output through the recording sample & hold section in a blank section of the recording area. Optical output control device of optical recorder.

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