JP3257287B2 - Optical disk recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recording apparatus for generating a write pulse based on a mark length of data and emitting a laser beam in accordance with the pulse output to record an information signal on a disk-shaped recording medium. Related to the device.

[0002]

BACKGROUND OF THE INVENTION Generally, the optical disc recording, the input data series is a series of bit information of "1" and "0", changing the minimum inversion interval T _min and a maximum inversion interval T _{m ax} of the input data sequence Thus, it is converted into a code symbol sequence more suitable for an optical disk. Then, as a format for recording this code symbol sequence on an optical disc,
There are inter-mark recording and mark length recording.

[0003] Among them, mark length recording is performed based on a code of a symbol sequence, for example, NRZI (Non Return to Zero I).
A waveform sequence is generated by modulation, and the light emission of the laser diode LD is controlled by changing the pulse width and the light emission level in accordance with the data length of the waveform sequence, thereby performing recording compensation in thermal recording. For example, the recording compensation by comb-pulse, as shown in FIG. 5, the diameter by the first pulse P _S of the pulse width t _a to record a round shortest mark M _S called 0.8μm dots for subsequent temperature retention It had stretched the mark length by the pulse P _H.

Here, the distance between the marks in the disk in the linear direction is defined as the mark length, and the distance in the radial direction of the disk is defined as the mark width. Then, the shortest mark M _S would mark length and mark width are equal.

[0005] In FIG. 5, the shortest mark M _S is 2 times the period T of the channel clock CLOCK, that is, the mark length of the distance 0.8μm at 2T min. In addition, the shortest mark M
Immediately after _S is formed, two temperature holding pulses are supplied, so that a mark having a mark length of 1.2 μm with a distance of 4T is formed. Further, as the temperature holding pulses immediately shortest mark M _S is formed is six supply,
A mark having a mark length of 2.4 μm is formed in 8T. Here, the mark width is constant at 0.8 μm in each case.

[0006]

By the way, the development of super-resolution technology using magnetism, etc., has made it possible to reproduce finer signals, and it has become necessary to record at the shortest mark length with a smaller mark width than the long mark signal. Was. However, as described above, the conventional comb-type pulse can cope only with recording with the same mark width.
Ratio) and a decrease in C / N. Also, when the mark width of the other mark was adjusted to the mark width of the shortest mark length, the C / N was reduced. Further, when trying to increase the C / N of a long mark, the short mark becomes longer and the edge shift amount increases. For this reason, in long marks, C
/ N deteriorated and edge jitter increased.

The present invention has been made in view of the above circumstances, and provides an optical disk recording apparatus capable of realizing a reduction in duty, a reduction in edge shift amount, an improvement in C / N for long marks, and a reduction in edge jitter. With the goal.

[0008]

An optical disk recording apparatus according to the present invention generates a write pulse having a leading pulse based on a mark length of data, and drives a light emitting means according to the write pulse. In an optical disc recording apparatus for emitting a laser beam and recording an information signal on a disc-shaped recording medium with a mark width of at least a predetermined mark width, a mark length detecting means for detecting a mark length of the data, and the mark length detecting means In the case where the mark length detected by the above is longer than the predetermined mark width and the case where the mark length is shorter than the predetermined mark width, at least the pulse width of the first pulse is changed to generate a write pulse. Pulse generation means, and when the mark length detected by the mark length detection means is longer than a predetermined mark width, A correction amount generating means for generating a light emission change amount for changing a light emission level of the head pulse as a correction value, and a generation output of the correction amount generation means when the arc length is shorter than the predetermined mark width. The above object is achieved by providing an automatic output control means for outputting a drive voltage that is automatically output controlled in response thereto, and a driving means for driving the light emitting means from the output of the write pulse generation means and the automatic output control means. .

When the mark length detected by the mark length detection means is longer than the predetermined mark width, the write pulse generation means determines the width of the first pulse and determines the number of temperature holding pulses. Determine and generate a write pulse.

[0010]

[0011]

[0012]

The write pulse generating means is provided for determining whether the mark length detected by the mark length detecting means is longer than a predetermined mark width, or when the mark length is shorter than the predetermined mark width.
At least the write pulse is generated by changing the pulse width of the first pulse. The correction amount generation unit is configured to emit light for changing the emission level of the first pulse when the mark length detected by the mark length detection unit is longer than a predetermined mark width and when the mark length is shorter than the predetermined mark width. The amount of change is generated as a correction value. The automatic output control means outputs a drive voltage that has been automatically output controlled according to the generated output of the correction amount generating means. The driving means drives the light emitting means from the outputs of the write pulse generating means and the automatic output control means, emits a laser beam, and records an information signal on the disk-shaped recording medium.

[0013]

[0014]

Therefore, the optical disk recording apparatus according to the present invention can realize a reduction in the change in operation duty ratio, a reduction in the amount of edge shift, an improvement in C / N for long marks, and a reduction in edge jitter.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical disk recording apparatus according to the present invention will be described below with reference to the drawings. This embodiment is an optical disc recording apparatus which irradiates a laser beam from a laser diode LD onto a disc having a diameter of, for example, 130 mm to record a mark length in accordance with the data length of a waveform train by thermal recording. In particular, this optical disk recording apparatus records an information signal on an optical disk with a mark width equal to or smaller than a predetermined mark width, as described later.

The optical disk recording apparatus of this embodiment, a timing adjustment circuit 1 adjusts the timing of the recording data D _0, the mark length detection circuit 2 for detecting the mark length of the recording data D _0, the mark length detection circuit 2 Detection result ta,
The comb pulse generator 3 generates a comb pulse from the tb, tc, the channel clock CLOCK, and the timing-adjusted recording data D ₀ ′, and the detection results ta, tb, tc of the mark length detector 2. A drive correction amount generating circuit 4 for outputting the change amount of the light emission level of the comb-type leading pulse as a correction value;
In the timing adjusting circuit 5 to adjust the timing of the generated signal, and supplies the driving voltage V _D which is an auto power control via the driver 7 and the drive circuit 9 to the laser diode LD auto power control (hereinafter, referred to as APC. A) a circuit 6, an amplifier 8 for supplying mutually complementary balanced outputs from the pulse output of the comb-type pulse generation circuit 3 to a drive circuit 9, and a drive circuit 9 for driving a laser diode LD. Recording data D ₀ is supplied to the mark length detection circuit 2, multiple of the period of the channel clock CLOCK as shown in (A) in FIG. 2, for example 2T, 3T or above the 4T~8T
Is detected. The detection results ta, tb, and tc signals (shown in FIG. 2B) are supplied to the comb pulse generation circuit 3 and the drive correction amount generation circuit 4, respectively.

The comb-type pulse generation circuit 3 determines the width of the comb-type head pulse and the number of temperature maintaining pulses, and generates necessary write pulses. In particular, the comb-type pulse generation circuit 3 changes the pulse width of the leading pulse depending on whether the mark length is longer than the predetermined mark width or when the mark length is shorter than the predetermined mark width. .
For example, the predetermined mark width is 0.8 μm as shown in FIG.

The timing adjustment circuit 1 delays the recording data by the time required for the mark length detection circuit 2 to determine the mark length, thereby processing the mark length detection circuit 2 and the comb pulse generation circuit 3 Adjust the timing of

The drive correction amount generation circuit 4 similarly generates the change amount of the light emission level of the comb-type head pulse as the correction value Vofs, and generates, for example, the light emission level Lc as shown in FIG. If the reference level is used as the reference level, as a negative correction, Lc-La is generated when the head pulse width is ta, Lc-Lb when the head pulse width is tb, and 0 when the head pulse width is tc. That is, the drive correction amount generation circuit 4 changes the light emission level of the first pulse depending on whether the mark length is longer than the predetermined mark width or when the mark length is shorter than the predetermined mark width. .

The timing adjustment circuit 5 adjusts the timing deviation generated in the mark length detection circuit 2 and the drive correction amount generation circuit 4 in the same manner as the timing adjustment circuit 1. Therefore, the timing of the pulse output of the comb pulse generating circuit 3 and the timing of the drive output of the APC circuit can be matched.

The APC circuit 6, as shown in FIG. 3, a laser diode emitting monitor the buffer amplifier 10 to which the voltage V _M is supplied, a comparator for comparing the data and the reference voltage value V _ref from the buffer amplifier 10 11, a low-pass filter (hereinafter referred to as LPF) 12 that limits the comparison output of the comparator 11, and a filter output from the LPF 12 based on the hold signal H.
It comprises a sample / hold (S / H in the figure) circuit 13 to be held, and an operational amplifier 14 to which the output from the S / H circuit 13 and the output V _ofs ′ from the timing adjustment circuit 5 are input. Have been.

First, the APC circuit 6 includes the buffer amplifier 1
The comparator 11 compares the laser diode emission monitor voltage via 0 with the reference voltage value _Vref . This comparator 11
Is subjected to band limitation by the LPF 12, and then sampled / held by the hold signal H from the mark length detection circuit 2. FIG. 4 shows the comparison output of the comparator 11 before holding (broken line) and after holding (solid line).
After the sample hold, the increase / decrease of the drive amount due to the mark length is canceled, and the APC process is performed. At this time, the hold signal H is output when the data is 2T or 3T, as shown in FIG. The hold output and the drive correction amount V _ofst whose timing has been adjusted by the timing adjustment circuit 5 are subtracted by the operational amplifier 14 to become the drive voltage V _D which is the final drive output as shown in FIG. This final drive output is supplied to the laser diode drive circuit 9 via the driver 7.

The laser diode drive circuit 9 is composed of a transistor Tr ₁ and the transistor Tr ₂ and the transistor Tr ₃ Prefecture. Positive output of the balanced output from the amplifier 8 to the base of the transistor Tr ₁ is supplied, the collector is connected to the cathode of the laser diode LD, an emitter connected directly connected to the emitter of the transistor Tr ₂ to the collector of the transistor Tr ₃ Have been. The collector of the transistor Tr ₂ is grounded via a load resistor R ₁ ,
The base inverting output of the amplifier 8 is supplied, the emitter is connected directly to the emitter of the transistor Tr ₁ as described above is connected to the collector of the transistor Tr _3. The base of tr ₃ final drive output from the APC circuit 6 is supplied via the driver 7, and the emitter is connected to V _EE through a resistor R _11.

The transistor Tr ₁ of the laser diode drive circuit 9 is turned on when the transistor Tr ₂ is off. At this time, the final drive output supplied to the base of the transistor Tr ₃ is a laser diode LD.
And emits a laser beam.

As described above, the optical disk recording apparatus of the present embodiment can reduce the change in duty, reduce the amount of edge shift, improve the C / N for long marks, and reduce the edge jitter.

The optical disc recording apparatus according to the present invention
The present invention is not limited to the above-described embodiment. For example, recording may be performed on another disk having a different diameter. Further, in order to realize higher-density recording, a laser generation element that emits laser light of a short wavelength, for example, a harmonic generation element such as a second harmonic generation element may be used.

[0028]

The optical disk recording apparatus according to the present invention provides a write pulse when the mark length detected by the mark length detecting means is longer than a predetermined mark width and when the mark length is shorter than the predetermined mark width. The generating means changes the pulse width of at least the first pulse to generate a write pulse, and the correction amount generating means generates a light emission change amount for changing the light emission level of the first pulse as a correction value. Then, the automatic output control means outputs a drive voltage that is automatically output controlled in accordance with the generated output of the correction amount generating means, and the driving means drives the light emitting means from the output of the write pulse generating means and the automatic output control means. Since the laser beam is emitted and the information signal is recorded on the disc-shaped recording medium, it is possible to reduce the change in the duty ratio, reduce the amount of edge shift, improve the C / N for long marks, and reduce the edge jitter.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram of an optical disc recording apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart for explaining the operation of the optical disc recording device shown in FIG.

FIG. 3 is a specific circuit diagram of an APC circuit of the optical disc recording device of the embodiment.

4 is a timing chart for explaining an operation of the APC circuit shown in FIG.

FIG. 5 is a diagram for explaining the operation of a conventional optical disk recording device.

[Explanation of symbols]

 2 Mark length detection circuit 3 Comb type pulse generation circuit 4 Drive correction amount generation circuit 6 Auto power control circuit 9 Laser diode drive circuit

Claims (2)

(57) [Claims] 1. A writing pulse having a leading pulse is generated based on a mark length of data, and a light emitting unit is driven in accordance with the writing pulse to emit a laser beam. An optical disk recording apparatus for recording an information signal with a mark width equal to or less than the mark width of: a mark length detecting means for detecting a mark length of the data; and the mark length detected by the mark length detecting means is a predetermined mark width. In the case where the length is longer than the above, and in the case where the mark length is shorter than the predetermined mark width, at least the write pulse generating means for generating the write pulse by changing the pulse width of the leading pulse is detected by the mark length detecting means. When the mark length is longer than a predetermined mark width, and when the mark length is shorter than the predetermined mark width, Correction amount generation means for generating a light emission change amount for changing the light emission level of the first pulse as a correction value, and automatic output control for outputting a drive voltage which is automatically output controlled in accordance with the generation output of the correction amount generation means An optical disk recording apparatus, comprising: a driving unit that drives the light emitting unit from an output of the writing pulse generating unit and the output of the automatic output control unit. 2. The writing pulse generating means, when the mark length detected by the mark length detecting means is longer than the predetermined mark width, determines a width of a head pulse and determines the number of temperature holding pulses. 2. The optical disk recording apparatus according to claim 1, wherein the write pulse is determined and generated.