JPH05182220A - Optical disk recorder - Google Patents

Abstract

PURPOSE:To stably obtain the information of a guide groove without interference between write processing and read processing. CONSTITUTION:Writing data supplied through an input terminal 10 is supplied to an LD driving circuit 11 and an LD 121 in an optical pickup part 12 is emitted. The LD driving circuit 11 drives so as to supply a non-zero-level not heat- transforming a recording medium even when the writing data is a zero-level. A sample hold circuit 19 in a servo signal generating circuit part 18 samples a signal detecting a return light beam reflected by an optical disk 13 by a PD 127 and further supplied the signal to an objective lens driving circuit 21 through a phase compensation circuit 20. The objective lens driving circuit controls the operation of the actuator 124 in the optical pickup part 12.

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 suitable for use in an optical disk recording apparatus for recording information along a guide groove of a recording medium for recording by optical modulation.

[0002]

2. Description of the Related Art Recording media for recording by optical modulation are classified into a write once read many (WORM) type, a rewritable type and a read only type. These recording media record information by forming concave and convex pits on the recording media by turning on / off the laser light according to "1" or "0" of the supplied digital signal. In particular, each write-once type optical disk is made of a material such as SbSe or BiTe, and the erasable rewritable type magneto-optical disk is TbFe.
Information is recorded by utilizing alloying of materials such as Co and phase change of crystal-amorphous.

An optical disk device for recording and / or reproducing on / from the recording medium has a servo control such as a tracking servo or a focus servo for recording / reproducing on / from the recording medium by accessing information recorded at high density at high speed. Need to do. In order to perform the servo control efficiently, the recording medium has various types such as interrupting a groove which is a guide groove and introducing a mirror portion in the section, or adding wobble pits arranged in a staggered manner with respect to a track center. Information is recorded using the method. In addition, since the recording medium is accessed at high speed, the absolute time (Absolute Time)
In Pregroove: hereinafter abbreviated as ATIP), information recording is performed and pregrooves are formed in advance to improve the information recording density or to simplify the optical disc device.

By configuring the recording medium in this manner, the operation of the optical disk device is stable and reliable.

FIG. 3 shows a part of the pre-groove 31 spirally formed from the innermost peripheral side to the outermost peripheral side while wobbling. A disk 30 as a recording medium shown in FIG. 3 has a U groove or a V groove formed in the pre-groove 31, and pits are formed in the pre-groove 31 or in an area between the pre-grooves so as to be orthogonal to the reading direction. The information such as the above ATIP is recorded in advance by performing FM modulation at a frequency of 20.05 kHz in the direction.

In order to read the information recorded in the pre-groove 31, for example, a tracking error signal output through a push-pull type detector by the return light reflected from the recording medium by irradiating a laser beam is used. Then, the optical disk device is servo-controlled.

[0007]

By the way, an optical disc apparatus is used for a recording medium which forms pits for recording information by utilizing the above-mentioned physical changes such as phase change and alloy.
When a write command is supplied as shown in FIGS. 2A and 2B, laser light is not output according to the level of the data to be written, which is either "1" or "0". That is, since the laser beam is not emitted except during recording, it is very difficult to detect the ATIP information written in advance and perform servo control.

In the case of irradiating the laser only when forming the pits, the return light from the recording medium with respect to the light amount of the irradiating laser light receives a physical change of the recording medium as noise, for example, thermal characteristics of the recording medium and writing output. If it is not appropriate, the state of the returning light may change due to teardrop-shaped pits (see FIG. 2C) and the like, and reproducibility may be poor. This poor reproducibility is due to the fact that the error occurrence rate during data recording depends on the laser output. Therefore, a servo error signal such as a tracking error signal included in the return light cannot be stably read from the recording medium, and recording is performed in an unstable servo control state during recording.

When the recorded recording medium is reproduced without sufficient servo control at the time of recording, the optical disk reproducing apparatus is directly affected by the reproduced signal output, and the reproduced signal is not reproduced. Causes an increase in error rate and instability in detection of information such as the tracking error signal, resulting in deterioration of reproducibility during reproduction. As described above, in the optical disc recording apparatus, it is very difficult to stably read the information written in the pre-groove during recording.

In view of the above situation, the present invention can completely separate the pre-groove information written in the pre-groove from the recording information at the time of recording, stably read the pre-groove information, and perform servo control. It is intended to provide an optical disk recording device.

[0011]

An optical disk recording apparatus according to the present invention is an optical disk recording apparatus for recording information along a guide groove of a recording medium, the optical quantity being equal to or more than a threshold value of a light quantity for forming a recording mark pattern on the recording medium. Light source output driving means for adjusting the output level of the light source that emits a high light quantity level and a non-zero low light quantity level lower than the threshold value to the recording medium according to the data, and the emitted light according to the output from the light source output driving means. Of the recording medium, the optical detecting means detecting the return light reflected by the guide groove, and the servo control signal generating means of the optical head based on the low light level detected by the optical detecting means. As a result, the above-mentioned problems are solved.

[0012]

The optical disk recording apparatus according to the present invention controls the emitted light quantity according to the data with a high light quantity level above the threshold value of the light quantity for forming the recording mark pattern on the recording medium and a non-zero low light quantity level lower than the threshold value. , The pre-groove information in the non-writing period obtained by the returning light is sample-held to be a continuous signal, demodulated and servo-controlled.

[0013]

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.

FIG. 1 shows a schematic block circuit relating to a servo control system of an optical disk recording apparatus according to the present invention. The optical disk recording device is an optical disk recording device for recording information along a guide groove of a recording medium, wherein a high light amount level equal to or higher than a threshold value of a light amount for forming a recording mark pattern on the recording medium and a non-zero low value. A laser driving circuit 11 which is a light source output driving means for adjusting an output level of a light source for emitting a light amount level to a recording medium according to data, and guidance of emitted light according to an output from the laser driving circuit 11 on the recording medium. An optical pickup unit 12 which is a light detecting means for detecting the return light reflected by the groove,
On the basis of the low light amount level detected from the optical pickup section 12, a servo control signal generating circuit section 18 which is a servo control signal generating means of the optical head is used.

The optical pickup section 12 includes a laser emitting element 121, a collimator lens 122, a beam split 123, an actuator 124, an objective lens 125,
It is composed of a condenser lens 126 and a photodetector 127.
The servo control signal generation circuit section 18 is composed of a sample hold circuit 19 and a phase compensation circuit 20.

The recording operation will be described with reference to the output waveform chart shown in FIG. 2 along the schematic block circuit shown in FIG.

As described above, when the recorded recording medium is reproduced without sufficient servo control at the time of recording, the optical disk reproducing apparatus outputs the reproduction signal which is directly affected by the recording. .. The reproduction signal causes an increase in error rate during recording and instability in detection of information such as the tracking error signal, resulting in deterioration in reproducibility during reproduction.

For this reason, it is necessary that recording on the optical disk 13 be sufficiently performed stably through servo control such as tracking. However, when the recording medium is recorded, if the laser output as a recording signal exceeds a recording level threshold for forming pits as a recording mark pattern, the characteristics of the recording medium can be changed and recording can be performed. As described above, the servo control cannot be performed sufficiently.

Further, when a non-zero level laser which does not exceed the recording level threshold is irradiated, the characteristics of the recording medium are kept stable and the return light from the recording medium is normally written in advance in the recording medium. Pregroove information can be read. Focusing on this point, it is possible to avoid the interference of both information and to perform stable servo control by completely separating the required information, for example, the pregroove and the recording information, which maintain the characteristics of this recording medium. become.

The optical disk recording apparatus inputs write data when a write command is supplied through the input terminal 10 as a control signal for completely separating the pregroove information and the record information. The write data is supplied to the delay circuit 17 and also the laser (LD) drive circuit 11
Is being supplied to. The laser drive circuit 11 supplies a laser drive control signal to the laser light emitting element 121 in the optical pickup section 12 according to the level of the write data.

The laser driving circuit 11 performs a laser driving operation for irradiating a laser having a laser output level lower than a laser irradiation threshold required for writing information during a period in which information is not written on a recording medium such as the optical disk 13. ing. The laser driving operation in the laser driving circuit 11 is performed according to the signal level of the write data externally supplied as shown in FIG.
When the level shown in (d) is "1", the laser drive control signal is output so as to perform recording on the optical disk 13. When the level of the write data is "0", the optical disk 13 is output.
A laser drive control signal is output so as to supply a laser output level of a non-zero level lower than the laser irradiation threshold necessary for writing information. When the write data is supplied in this manner, the write data supplies the laser drive control signal at a level lower than the threshold value that causes the recording layer of the recording medium to change even if the level is "0". .. As will be described later, this laser drive control signal is used as laser light for reproducing the pregroove information.

The laser light emitting element 121 outputs a laser according to the level of the supplied laser drive control signal. The laser emitted from the laser light emitting element 121 becomes a parallel light flux through the collimator lens 122 and reaches the objective lens 125 through the beam splitter 123 and a ¼ wavelength plate (not shown). This parallel light flux is narrowed down by the objective lens 123, and a minute spot is narrowed down on the surface of the optical disc 13. The minute spots form the pits shown in FIG. 2E on the recording layer of the optical disc 13.

FIG. 2 (f) shows the reflected light reflected from the surface of the optical disk 13 of the irradiated laser. As described above, the optical disc 13 is irradiated with a laser light amount equal to or more than a recording threshold value for writing certain recording information, but has a thermal characteristic for causing a physical state change of the recording layer, and thus, for example, about 200 ns. Pits are formed with a delay (see FIG. 2E). The return light from the optical disk 13 shown in FIG. 2 (f) has an amount of laser light that forms pits, which are recording mark patterns, on the recording medium substantially in synchronization with the rising from the laser drive circuit 11 shown in FIG. 2 (d). Although irradiated, the pits are not formed due to the thermal characteristics of the recording medium. For this reason, the amount of return light from the surface of the recording medium increases, and the level of the return light reaches the maximum value for about 200 ns. Recording is performed while the output level is maintained at or above the threshold value of the laser light amount required for recording, while the level of the returning light sharply decreases in accordance with the formation of pits thereafter.

When the level of the write data becomes "0", the output level of the laser drive circuit 11 outputs the laser at a level lower than the recording threshold so as to stop writing. The output of the laser drive control signal from the laser drive circuit 11 indicates the stop level of the laser irradiation, but as described above, it has a high heat capacity due to the thermal characteristics of the recording medium, so that pits are still formed. Therefore, as shown in FIG. 2C and FIG. 2E, pits and shifts (about 20%) formed with respect to the laser drive control signal are formed.
0-300 ns) will occur.

The return light reflected from the pit forming surface is a non-zero value while the output level of the emitted laser light is above the recording threshold level and the supply of the laser light is stopped and is lower than the recording threshold level. The laser light of is emitted. By the way, the amount of return light during this shift period is the minimum amount of return light due to the fact that the pit formation is still performed and the non-zero low and narrow laser light is emitted. Therefore, the reproduction of the pre-groove information needs to be performed in the section P from the end of the formation of the shifted pits shown in FIG. 2 (f) to the supply of the level "1" of the next write data. As described above, in the write command mode, the period other than the write data level "1", that is, the write data level "0"
During this period, the laser drive circuit 11 controls so that a laser beam lower than the recording threshold level and non-zero is output to the optical disc 13.

In the section P, the reflection of the laser on the surface of the optical disk 13 includes, for example, absolute address (ATIP) information pre-written in the pre-groove in the return light. The return light in the section P returns to the same optical path as that of the incident light and is supplied from the objective lens 125 to the beam splitter 123 via the quarter wavelength plate. Beam splitter 123
Reflects the polarized light by the beam splitter 123 and supplies it to the condenser lens 126. The condenser lens 126 converts the separated light flux into an electric signal by converting the movement of the spot moving on the photodetector 127 by a photodetector (2D-PD) 127 for detecting a tracking error signal into the amplifier 1.
4 and 15 respectively. The amplifier 15 amplifies the supplied signal and outputs it as an RF signal from the output terminal 16. Further, the amplifier 14 amplifies the supplied signal and supplies it as a servo error signal to the sample hold circuit 19 in the servo control signal generation circuit section 18.

In the sample hold circuit 19, the write data has a deviation between the laser drive control signal and the pit formation section as described above in the delay circuit 17,
In order to mask this shift time, sampling and holding are started via a delay circuit 17, for example, at the rising edge of the write data delayed by a predetermined time. In this way, the pre-groove information is taken into the sample hold circuit 19. At this time, the sampling pulse shown in FIG. 2G may be the entire section P, but since it is not necessary to use the entire area, it is only necessary to open the window for a short time as shown. This will be described later
This is also due to the fact that ATIP (absolute time information) has a frequency of 22.05 kHz and is slower than pit formation.

The sample hold circuit 19 supplies the phase-compensated servo control signal to the objective lens drive circuit 21 via the phase compensation circuit 20. Actuator 12
Reference numeral 4 moves the position of the objective lens 125 based on this servo control signal to perform servo control.

The output signal of the sample hold circuit 19 is output via the output terminal 22. This output signal is a pulse train modulated by ATIP (absolute time code) as one of the pregroove information. Although not shown, this output signal is demodulated into a data bit of an ATIP code by the pulse train in a demodulation circuit in the subsequent stage. The demodulation circuit supplies it to a system controller (not shown) corresponding to the servo control unit of the optical disk recording apparatus and is used, for example, for servo of the spindle motor or control of the scanning position of the optical head.

The laser light output for irradiation is controlled according to the level of the write data supplied in the above-described configuration, and the information of the pre-groove during the non-write period obtained by the return light is sampled and held, for example, as described above. It is possible to completely separate the pregroove information written in the pregroove and the recording information. The optical disc recording apparatus can perform servo control such as tracking error at the time of recording by a signal that stably reads out the information of the separated pre-groove. Further, by taking the delay amount into consideration when sampling and holding, for example, a servo error signal such as a tracking error signal can be continuously demodulated and servo-controlled.

Since the information previously written in the guide groove is not modulated by light, ideal guide groove information can be obtained from the same state as the unrecorded state.

Although the present embodiment has been described with respect to a general optical disk recording apparatus, particularly in the system of the write-once compact disk recording apparatus, in the write command mode, the light supplied with the write data in the OFF state is DC. Noise is reduced by using a switched on / off signal instead of (DC) light.

[0033]

As is apparent from the above description, according to the optical disc recording apparatus of the present invention, in the optical disc recording apparatus for recording information along the guide groove of the recording medium, the recording mark pattern is formed on the recording medium. From the light source output driving means, a light source output driving means for adjusting the output level of the light source for emitting a high light quantity level equal to or higher than the threshold of the light quantity to be formed and a low light quantity level of non-zero while being lower than the threshold value to the recording medium according to the data, A light detecting means for detecting the return light reflected by the guide groove in the recording medium of the emitted light according to the output of
By having a servo control signal generating means for the optical head based on the low light amount level detected by the light detecting means, the writing processing of the recording signal and the reading processing of the guide groove information are completely separated. By doing so, it is possible to prevent mutual interference of both processes. Further, the optical disk recording apparatus can perform servo control such as tracking error at the time of recording by a signal which stably reads out the information of the separated pre-groove.

Since the information previously written in the guide groove is not modulated by light, ideal guide groove information can be obtained from the same state as the unrecorded state.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic block configuration in an embodiment of an optical disc recording apparatus according to the present invention.

FIG. 2 is a diagram for explaining the operation of the block configuration shown in FIG.

FIG. 3 is a schematic diagram showing a part of a wobbling pre-groove on a recording medium.

[Explanation of symbols]

Input terminal 11 Laser driving circuit 12 Optical pickup unit 13 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Optical disk 14, 15 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Amplifier 16 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Output terminal 18 ・ ・ ・ ・・ ・ ・ ・ ・ ・ ・ ・ Servo control signal generation circuit 19 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Sample and hold circuit 20 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Phase compensation circuit 21・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Objective lens drive circuit

Claims (1)

[Claims] 1. An optical disc recording apparatus for recording information along a guide groove of a recording medium, wherein a high light amount level equal to or higher than a threshold value of a light amount forming a recording mark pattern on the recording medium and a non-zero low light amount lower than the threshold value. The light source output driving means for adjusting the output level of the light source for emitting the level to the recording medium according to the data, and the return light reflected by the guide groove in the recording medium of the emitted light according to the output from the light source output driving means. An optical disk recording apparatus comprising: a light detecting means for detecting; and a servo control signal generating means for at least an optical head based on the low light amount level detected by the light detecting means.