KR19990074011A - Recording Control Method for High Density Optical Recording Devices - Google Patents

Abstract

A method of recording optimal data via the light output of a laser diode is disclosed. A method of controlling NRZI data recording consisting of 3T to 14T by a combination of a reproduction light output level, a recording light output level, and an erase light output level, further comprising combining at least one reproduction and recording light output level in addition to the optical output levels. In order to control the recording waveform of the NRZI data according to the combined level, the present invention combines six types of optical output control signals to record optimally input NRZI data on a disk to minimize jitter and to improve the reliability and performance of the system. Can improve.

Description

Recording Control Method for High Density Optical Recording Devices

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high density optical recording method, and more particularly to a method of recording optimal NRZI data through the light output of a laser diode.

In the multimedia era, high-capacity recording media are required, and optical recording apparatuses using such high-capacity recording media include MODD (Magnetic Optical Disc Driver) and DVD-RAM (Digital Versatile Disc Random Access Memory) drivers. have.

Such optical recording apparatuses require an optimal system state as the recording density increases and require precision. In general, it is important to minimize such jitter in order to achieve high density recording since the recording capacity increases, the time-axis oscillation (hereinafter referred to as jitter) of the recording pulse with respect to the radial tilt increases. .

Conventionally, a format book as shown in FIG. 1E for input NRZI (Non Return to Zero Inversion) data having a recording mark length of 3T, 5T, 11T, etc., as shown in FIG. Configure and record overwrite pulse in the state specified in. Here, the NRZI data is divided into a mark and a space, and the space period is kept in an erased state at the time of a write command. The recording marks of NRZI data of 3T, 4T, ..., 14T that are different in units of 1L (L: 1 bit length) are multi (with the first pulse, the last pulse and the cooling pulse unchanged. multi) Only the number of pulses is recorded.

That is, the reproduction light output (read power (b) of FIG. 1), the peak light output (also called write light output: (c) of FIG. 1) and the bias power output (aka Also referred to as erase light output: The waveform of the recording pulse shown in FIG. 1E is formed by the combination of FIG. Each output control signal is a high active signal.

According to the 2GB (Giga Byte) DVD-RAM standard, this write pulse waveform consists of the first pulse, the multi pulse chain and the last pulse, and the rising edge of the first pulse of the basic write pulse, also known as the preheat pulse. Is a time point T / 2 delayed from the rising edge of the recording mark, and the rising edge of this first pulse can be shifted back and forth in units of 1 ns (nono second), and the last pulse can also be shifted back and forth in units of 1 ns. By dividing into several short pulses, heat accumulation at the rear end of the recording mark is reduced to prevent deformation of the recording mark. In such a structure of the recording pulse, a recording pulse waveform is produced and used irrespective of the preceding space and the following space of the recording mark.

Therefore, the optimum result does not appear when three types of light output levels having the same write power are used in 3T to 14T when recording by configuring the recording pulse as shown in Fig. 1E. That is, jitter occurs when data having a long recording mark length, in which heat may accumulate at the rear end of the recording mark, is generated according to the input NRZI data. It may be deteriorated, and in a case other than 3T, the center of the recording mark generated on the disc may be in the center or one side may be widened. This is the biggest factor that degrades the performance of the system, there is a problem that becomes difficult to use in the future high-density DVD-RAM.

In order to solve the above problems, it is an object of the present invention to provide a method for optimally recording a plurality of light output levels for input NRZI data.

In order to achieve the above object, in the method of controlling NRZI data recording composed of 3T to 14T by a combination of a reproduction light output level, a recording light output level, and an erase light output level according to the present invention,

At least one reproduction and recording optical output level is further combined with the optical output levels, and the recording waveform of the NRZI data is controlled according to the combined level.

1A to 1E are waveform diagrams showing the configuration of a conventional recording pulse.

Figure 2 is a block diagram showing a laser diode light output control apparatus according to the present invention.

3A to 3H are waveform diagrams of recording pulses generated by the pulse generator shown in FIG.

Hereinafter, with reference to the accompanying drawings, it will be described a preferred embodiment of the laser diode light output control method according to the present invention.

2 is a block diagram showing a laser diode light output control apparatus according to the present invention, and comprises a write pulse generator 210 and a current driver 210, the write pulse generator 210 is a read erase (read erase) ) Pulse generator 212, first pulse generator 214, last pulse generator 216, multi-pulse train generator 218, 3T detection pulse generator 219 and the OR gate 219.

That is, the write pulse generator 210 generates a write pulse for the input NRZI data, and the current driver 220 converts the write pulse generated by the write pulse generator 210 into a current signal to drive the laser diode. Let's do it.

3A to 3H are waveform diagrams of recording pulses generated by the pulse generator shown in FIG. Each waveform is an active high signal.

Next, the operation of the apparatus shown in FIG. 2 will be described with reference to the waveforms of FIGS. 3A to 3H.

Fig. 3A is input NRZI data, which is divided into marks 3T to 14T and spaces. This NRZI data is a modulated signal and nT (T: period of the synchronous clock used in the optical recording device). FIG. 3C is a waveform for controlling the reproduction optical power level during reproduction generated by the lead-ease pulse generator 212, and FIG. 3D shows a multi-pulse strain generator 218 is a waveform for controlling the bottom light output level of the multi-pulse train, and represents the lower end value of the multi-train pulse during recording. 3E is a waveform for controlling the light output level generated by the read-ease pulse generator 212, and is used for data erasing and preheating during recording. 3 (f) shows light output levels of first and last pulses generated by OR of the first pulse generator 214 and the last pulse generator 216 to the OR gate 219. The waveform is for controlling, and the first and last pulse widths are variable. Fig. 3G is a waveform for controlling the 3T recording light output level generated in the 3T detection pulse generator 219, and shows the recording when 3T is the shortest mark. 3H is a waveform for controlling the light output level of the multi-pulse train generated by the multi-pulse strain generator 218, and shows the upper end value of the multi-train pulse during recording. FIG. 3B shows a maximum of six types corresponding to the waveforms of (c), (d), (e), (f), (g) and (h) generated by the recording pulse generator 210 ( The waveforms of c, d, e, f, g, and h are combined by switching and output to the current driver 220, and are the time points at which the period rising from c to e is written. That is, six types of optical outputs, which are a combination of the levels of (c), (d), (e), (f), (g), and (h) of FIG. 3, for optimal recording of the input NRZI data. Use level. For example, the light output level value of (c) of FIG. 3 is 0.2-3 mV, (d) is 0.2-3 mV, (e) is 3-10 mV, (f) is 3-16 mV, (g) Is 3-16 mV, and (h) can be set to 3-16 mV.

In other words, at least one reproduction and recording light output level is further combined with a combination of the existing reproduction light output level, the recording light output level, and the erase light output level, and the recording waveform of the NRZI data is controlled according to the combined level. . In addition, the light output level of the shortest mark 3T and the other marks (4T or more) is distinguished and recorded by the light output level of the multi-pulse train of FIG. The top level of the multi-train and the bottom level of the multi-train can be separately changed by the light output level of FIG. 3H and the light output level of (D).

Referring to the recording waveform shown in (b) of FIG. 3, at least one intermediate preheat pulse includes a preheat pulse f having a first signal level for preheating the optical recording medium and a second signal for recording NRZI data. (h), the second signal level of the intermediate preheat pulse h is set larger than the first signal level of the initial preheat pulse f. In addition, a plurality of intermediate preheat pulses (h) are generated, at least one signal level of the plurality of intermediate preheat pulses (h) is greater than the first signal level, and is previously stored in the optical recording device before the initial heating pulse (f) is applied. It consists of an erase pulse e for canceling the signal. The signal level of the erase pulse e is smaller than the first signal level.

The current driver 220 controls the driving level of the input light output to control the flow of each channel current ((c), (d), (e), (f), (g), (h) of FIG. 3). The current is converted into a current for a control time corresponding to)) and flows through the laser diode to heat the recording medium through continuous on and off operation of the laser diode to record the desired recording waveform.

The recording pulse waveform proposed in the present invention can be used in most high density optical recording devices.

As described above, the present invention combines six types of optical output control signals to record optimally input NRZI data on a disk, thereby minimizing jitter and improving system reliability and performance. In addition, the shortest mark (3T) and other marks can be adjusted separately to prevent deterioration.

Claims (12)

A method of controlling recording of NRZI data consisting of 3T to 14T by a combination of a reproduction light output level, a recording light output level, and an erase light output level, And further combining at least one reproduction and recording optical output level with the optical output levels, and controlling the recording waveform of the NRZI data according to the combined level. The recording control method according to claim 1, wherein the light output level is at most six levels. The method of claim 2, wherein the light output level is Optical output level during reproduction, lower optical output level of multi-train pulse during recording, optical output level for recording data erasing, optical output level of first and last pulse, 3T recording optical output level, upper optical output of multi-train pulse at recording Recording control method characterized in that the level. The recording control method according to claim 1, further comprising an optical output level controlled exclusively for the shortest mark. The recording control method according to claim 1, wherein the recording control is performed by distinguishing the light output level for the shortest mark and the other marks. The recording control method according to claim 1, wherein the light output varies separately the top level of the multi-train. The recording control method according to claim 1, wherein the light output varies separately at a bottom level of the multi train. Generating a preheat pulse having a first signal level for preheating the recording medium, applying the initial preheat pulse to the recording medium, and applying at least one intermediate preheat pulse to the second signal for recording the modulated signal In the method for controlling the signal recording of the optical recording device, And the second signal level of the intermediate preheat pulse is greater than the first signal level of the initial preheat pulse. 9. The recording control method according to claim 8, wherein a plurality of intermediate preheat pulses are generated, and at least one signal level of the plurality of intermediate heat pulses is greater than a first signal level. 9. The recording control method according to claim 8, wherein an erase pulse for erasing a signal previously stored in the optical recording device is generated before the initial heating pulse is applied. 9. The write control method according to claim 8, wherein the signal level of the erase pulse is smaller than the first signal level. 9. The recording control method according to claim 8, wherein the modulated signal is nT (T: period of a synchronous clock used in an optical recording device).