KR20010009422A - Record signal generating method and apparatus for optical record/player - Google Patents

Abstract

PURPOSE: An apparatus for generating a recording signal of an optical recording/playing back device is provided to form multi-pulse by using a single channel. CONSTITUTION: A reference signal generator(402) outputs a reference signal to a signal overlay unit(405). An encoder(401) outputs a recording pulse and an ALPC(Auto Laser Power Control) control pulse to an ALPC control unit(404). The recording pulse is a control pulse for generating multi-pulse by turning on/off LD(Laser Diode) power up to recording power. A power generator(403) outputs variable LD power level overlaid with a write clock to the signal overlay unit. The signal overlay unit outputs multi-pulse to an LD driver(406) by overlaying the recording pulse with the write clock according the power level of the power generator. A V-I amplifier of the LD driver runs an LD in an optical pickup device(102) by converting the LD driving voltage into current. Therefore, the recording pulse of the encoder is recorded on an optical disk(101).

Description

Record signal generating method and apparatus for optical record / player

The present invention relates to a system for recording and reproducing data on an optical disc, and more particularly to a method and apparatus for generating an optimal recording signal for recording data on a disc.

In general, for rewritable discs, the recording medium is usually formed of a phase change material. Therefore, the light focused at the optical head is converted to heat, and this heat changes the state of the phase change recording medium so that the reflection amount is changed, thereby forming marks on the phase change type disk to record the pits. Here, forming a mark by a predetermined length on the disk is called a 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-related portion of a general optical disc recording / reproducing apparatus, and FIG. 2 is a detailed block diagram of FIG. 1, in which a signal for recording on the disc 101, that is, a recording pulse, is input to the encoder 103. When the encoder 103 converts the recording pulse into a 16-bit digital signal, the encoder 103 processes the upper 8 bits and the lower 8 bits (this is called a symbol) in units of frames.

The 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) or EFM + modulation for converting 8-bit symbol data to 14 bits. Do it. 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. 3 (a) 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'. In other words, if '1' is met, the current state is reversed.

On the other hand, the power generating unit 104 generates the power of the laser diode (LD) for the data to be recorded and converted to analog and then the LD driver (Auto laser power control (ALPC) control unit 105) 106) 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 is recorded on the optical disc 101. At this time, the LD light output is remarkably changed according to the temperature. As the temperature increases, the recording power drops and the recording power increases as the temperature decreases. ALPC) feedback to the feedback unit 107. The ALPC feedback unit 107 outputs the ± power level to the ALPC control unit 105 according to the feedback LD power and adds it to the recording power generated by the power generation unit 104 to increase the LD output power during recording / reproducing. Keep it constant.

At this time, when data is recorded by a single NRZI modulated pulse, the shape of the pit is formed like a tear drop due to the thermal characteristic of the disk itself, or the formation of the mark is distorted due to the latent heat characteristic of the disk. That is, the tip of the currently recorded mark influences the length of the mark under the influence of the latent heat generated to form the mark just recorded, and also affects the length of the end of the recording mark according to the length of the current recording mark. Gives.

Therefore, a multi-pulse modulation scheme is sometimes used to prevent the diffusion of heat and to form the shape of the pit into a smooth oval shape. That is, as shown in FIG. 3 (b), multi-pulse modulation is performed in which a single pulse is divided into several pulses and scanned on a disk by turning on / off several times in one single NRZI modulated pulse.

As such, since a single pulse is divided into several pulses and scanned on the disk, heat accumulation in the section where the signal pit is located is prevented, thereby forming the shape of the pit in a smooth oval shape.

In this case, in the case of a normal rewritable disc, the LD power uses three levels. As shown in FIG. In order.

That is, in the case of multi-pulse, the encoder 103 outputs the write pulse, erase pulse, and read pulse to the LD driver 106. In addition, the power generating unit 104 generates each power, for example, a recording power, an erase power, and a read power, and outputs the generated power to the ALPC control unit 105, and the ALPC control unit 105 outputs a control pulse output from the encoder 103. The write power, erase power, and read power fed back by the (control pulse) are added to the LD driver 106 and output.

In the case of the multi-pulse, the LD driver 106 is enabled by a write pulse, an erase pulse, and a read pulse output from the encoder 103 as shown in FIG. 2 to convert a voltage corresponding to each pulse into a current. Two VI amplifiers 106-1 to 106-3 and driving currents outputted through the VI amplifiers 106-1 to 106-3 to add to the adder 106-4 for driving the LD in the optical pickup 102. It is composed.

That is, the first VI amplifier 106-1 converts the recording power output from the ALPC controller 105 into current by turning on / off as shown in FIG. 106-2) is turned on / off by an erase pulse as shown in FIG. 3 (d) to convert the erase power output from the ALPC controller 105 into a current, and the third VI amplifier 106-3 reads By the pulse as shown in Fig. 3 (e) is turned on / off and the read power output from the ALPC control unit 105 is converted into a current.

When the adder 106-4 adds the currents output from the first to third VI amplifiers 106-1 to 106-3 to drive the LD in the optical pickup 102, the multi-pulse modulated signal becomes an optical disk. Recorded at 101.

However, in order to implement the multi-pulse as described above, as shown in FIG. 2, a voltage level of three levels and a switch control signal of three lines are required. In other words, switching channels are required for the desired power level to implement the multi-pulse. In addition, there is a problem of deterioration in recording characteristics due to noise characteristics such as glitches in the generation of the LD driving current due to the interference of the time for switching the three levels of voltages in each V-I amplifier.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a method and apparatus for generating a recording signal of an optical recorder for implementing a multi-pulse using a single channel.

1 is a block diagram illustrating a configuration of a recording signal generating apparatus in a conventional optical recording / reproducing player

2 is a detailed block diagram of FIG. 1 in a multi-pulse implementation

3A to 3E are timing charts for recording mark formation in FIG.

4 is a block diagram showing the configuration of a recording signal generating apparatus in the optical recording / playback apparatus according to the present invention;

5 (a) to (d) is a timing diagram showing a process of implementing a multi-pulse in a single channel according to the present invention

Explanation of symbols for main parts of the drawings

101: optical disk 102: optical pickup

401: encoder 402: reference signal generator

403: power generation unit 404: ALPC control unit

405: signal overlap 406: LD driver

107: ALPC feedback

According to an aspect of the present invention, there is provided a method of generating a recording signal of an optical recorder according to the present invention, the method comprising: generating a reference signal having a predetermined period, and superimposing a desired power level on the reference signal to generate a laser diode during a recording period. It characterized in that it comprises a step of driving.

The reference signal of the step is characterized in that the write clock.

An apparatus for generating a recording signal of an optical recorder according to the present invention includes an encoder for generating a recording pulse according to data to be recorded, a reference signal generator for generating a reference signal having a predetermined period, and a desired power level for recording. A single channel which is enabled by the power generating unit, a signal superimposing unit generating a multi-pulse by superimposing the write pulse and the reference signal at a power level of the power generating unit, and an output of the signal superimposing unit; It characterized in that it comprises a LD drive unit.

The encoder is characterized by generating a single pulse with a write pulse for one pit length.

The present invention superimposes a desired voltage level on a reference signal having a certain period, for example, a write clock, and the pit generation section is LD to multi-pulse, and the erase section is to an erase level by the write pulse control generated by the encoder. By constantly driving LD at the read level in the reproduction section, switching noise is removed to improve recording characteristics.

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.

4 is a block diagram illustrating an optical disk recording apparatus according to the present invention. The reference signal generator 402 and the signal overlap unit 405 are further provided in FIG. The LD driver 406 is composed of a single channel, that is, a single V-I amplifier.

The reference signal generator 402 generates a reference signal having a predetermined period and outputs the signal to the signal overlapping unit 405 as shown in FIG. 5 (c). In order to absorb the variable factors such as eccentricity, etc., a write clock generated by applying a phase locked loop (PLL) to a periodic signal generated along a track, such as a wobble clock, or a fixed clock Use

The encoder 401 outputs a write pulse as shown in FIG. 5 (b) to the signal superimposing unit 405 to turn on / off the VI amplifier of the LD driver 406, and the control pulse for controlling the ALPC is Output to the ALPC control unit 404. In this case, the write pulse is a control pulse that generates a multi-pulse by turning on and off the actual LD power to the write power. Here, the encoder 401 outputs the NRZI form indicating the pit length to be actually recorded as shown in FIG. 5A to the signal overlapping unit 405 instead of the recording pulse as shown in FIG. 5B. You may.

Meanwhile, the power generator 403 sets the power level of the LD to overlap the write clock and outputs the power level to the signal overlapping unit 405. The power level may vary.

The signal overlapping unit 405 overlaps the write pulse output from the encoder 401 and the write clock of the reference signal generator 402 at a power level output from the power generation unit 403, that is, a voltage level. As a result, a multi-pulse as shown in FIG. 5D is generated and output to the LD driver 406. That is, during the recording pulse on period for generating the recording pit, multi pulses are generated by synchronizing the read clock swinging the read power level and the write power level by the set level, and the other periods are at the erase power level and the reproduction period. Generates a pulse train at the read power level.

The V-I amplifier of the LD driver 406 converts an LD driving voltage corresponding to a multi-pulse input as shown in FIG. 5D into an LD driving current to drive the LD in the optical pickup 102. Therefore, the recording pulse output from the encoder 401 is recorded on the optical disc 101.

As described above, the present invention uses only one V-I amplifier, that is, a single channel in the LD driver 406, even though the recording is performed using multi-pulse.

At this time, the ALPC controller 404 adds the power level generated by the power generator 403, that is, the LD driving voltage and the feedback voltage output from the ALPC feedback unit 107, and outputs the result to the signal overlapping unit 405. The signal superimposing section 405 also superimposes this signal and outputs the signals to the LD driving section 406 so that the LD maintains the reproduction, erasure and recording power at the set power.

Therefore, optimal recording is performed even in a high density disc such as a DVD-RAM.

On the other hand, the present invention by processing the cycle of the clock generated by the reference signal generator 402 through the division, etc., it is possible to easily generate a multi-frequency or a low-frequency multi-pulse more than the current without noise.

As described above, according to the method and apparatus for generating a recording signal of an optical recorder according to the present invention, by superimposing a desired voltage level on a reference clock having a predetermined period and using it as an LD driving signal during a recording period, a multi-pulse is provided through a single channel. Since no switching noise occurs, optimal recording is performed, which reduces jitter in the reproduction signal. In addition, the voltage level and the switch control signal corresponding to the number of power levels are also unnecessary.

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)

A method of generating a recording signal of an optical recorder which generates a recording pulse according to data to be recorded and applies a recording power level therefrom to drive a laser diode. Generating a reference signal having a predetermined period; And driving a laser diode during a recording period by superimposing a desired power level on the reference signal. The method of claim 1, wherein the reference signal of the step A recording signal generation method for an optical recorder characterized in that it is a write clock. The method of claim 1, And generating a high frequency multi-pulse by changing the period of the reference signal in the step and superimposing a desired power level. The method of claim 1, And generating a low-frequency multi-pulse by varying the period of the reference signal in the step and superimposing a desired power level. A recording signal generating apparatus of an optical recorder for driving a laser diode to form a mark on an optical disk, An encoder for generating a recording pulse according to the data to be recorded, A reference signal generator for generating a reference signal having a predetermined period; A power generator for generating a desired power level for recording; A signal overlapping unit generating a multi-pulse by superimposing the recording pulse and the reference signal at a power level of the power generating unit; And an LD driver of a single channel enabled by the output of the signal overlapping unit to drive the laser diode. The method of claim 5, wherein the encoder And a single pulse generated by a recording pulse for one pit length. The method of claim 5, And the reference signal generator is configured to output a reference signal by applying a PLL to a write clock.