JP2003223717A - Optical recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably record the data by setting the optimum amount of recording light in a recording mode in an optical recording and reproducing device which uses an optical recording medium of large modulation of the recording information. <P>SOLUTION: The light source of a laser diode 11 is driven by a laser drive circuit 20 to radiate the light beam of the recording level amount to the record the data and to radiate the light beam of the level amount lower than the above at the positions between the data. A photo detector 13 detects the reflected light beam from the above optical recording medium irradiated as above. A system controller 37 sample-and-holds the signals detected by the above photo detector 13 while the above light source is radiating the light beams of the recording level amount and the lower level amount of light, and controls the recording level amount and the above lower level amount of the light beam. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording apparatus for recording information by irradiating an optical recording medium with a light beam to form pits. In recent years, disk-shaped recording media such as optical disks and magneto-optical disks utilizing optical or magneto-optical signal recording / reproducing methods have been developed and are being supplied to the market. These disc-shaped recording media can be read-only memory (ROM), such as a so-called compact disc (CD), or the user can write data once. Known are write-once-type (write-once) recording media, and recording media on which data can be rewritten (so-called overwrite), such as magneto-optical disks. In an optical disk recording / reproducing apparatus for writing / reading data to / from the write-once type or overwritable optical disk, laser drive is performed while rotating the optical disk at a constant angular velocity or linear velocity by a spindle servo. A focus servo based on a detection output by the photodetector is provided in an optical head including a laser diode that outputs a light beam for recording and reproducing information by being driven by a circuit, and a photodetector that detects reflected light of the light beam irradiated on the optical disk. Data is recorded and reproduced by scanning the recording track of the optical disk with a light beam by applying a servo and tracking servo. Further, in the optical disk recording / reproducing apparatus for recording / reproducing information by scanning a recording track with a light beam as described above, if the beam power of the light beam for scanning the input recording track in the recording mode is too small, the information cannot be reliably obtained. If the beam power of the light beam that scans the recording track in the reproduction mode is too large, there is a possibility that the information recorded on the recording track may be seriously affected. For example, as disclosed in JP-A-53-46633, the intensity of a light beam for recording and reproducing information, that is, the amount of light, is detected, and feedback control of a laser diode drive circuit that outputs the light beam is performed. Then, the so-called APC servo loop for keeping the beam power of the light beam constant is switched according to various operation modes, So that properly switch the word. [0005] In an optical recording / reproducing apparatus for recording / reproducing information on / from an optical recording medium by scanning a recording track with a light beam, the reflected light from the optical recording medium is converted into an optical signal. The head detects and performs focus servo and tracking servo of the light beam based on the detection output. The reflected light from the optical recording medium is a pit formed in the recording tracking of the recording medium. That is, since the information is modulated by the recording information, the servo system may be affected by the pits. In an optical recording / reproducing apparatus, a pit is formed by scanning a recording track on an optical recording medium with a recording light beam emitted from a laser diode pulse-driven in accordance with recording information in a recording mode. The information is recorded. As shown in FIG. 4, a pit P is actually formed after irradiating a recording light beam obtained by pulse-driving a laser diode with a recording pulse corresponding to the recording information. There is a time delay τ of about 300 to 400 ns before starting, and the detection output waveform of the reflected light of the recording light beam applied to the recording track is also modulated with the above time delay. Therefore, in the conventional servo system which operates based on the detection output of the reflected light of the recording light beam, an automatic gain control circuit having a large dynamic range in the servo system is largely dependent on a pattern of pits formed on a recording track, that is, recording information. It was necessary to provide. In particular, the degree of modulation by a recording information signal is 60%, as in a write-once optical disk having a dye-based optical recording medium layer.
In an optical recording / reproducing apparatus using an optical recording medium as high as a compact disk, the effect of a pit pattern formed on a recording track in a recording operation mode on the operation of a servo system becomes a problem. In an optical disc having a pre-groove (guide groove) for tracking servo, the pre-groove is wobbled (oscillated) as in the so-called ATIP (absolute time in pre-groove) format. Japanese Patent Application Laid-Open No. 63-87665 discloses a method of recording auxiliary sub-information, for example, absolute time information, using the wobbling frequency component as a carrier.
However, when the above-mentioned ATIP format is adopted, since the reflected light detected by the optical head at the time of the information recording is modulated with the time delay τ as described above, There is a problem that the absolute time information cannot be reproduced well. Specifically, the level uncertainty caused by reading the recorded pits generates a low-frequency spectrum component, which greatly reduces the C / N of the wobbling frequency component, and reduces the absolute time information. This is because the error rate is extremely deteriorated when reproducing the data. In view of the above, the present invention provides an optical recording / reproducing apparatus using an optical recording medium having a high degree of modulation by a recording information signal in a recording operation mode.
It is an object of the present invention to set an optimum recording light amount so that data can be reliably recorded. According to the present invention, there is provided an optical recording apparatus comprising: a light source for irradiating a light beam for recording information by forming pits on an optical recording medium; Driving means for driving the light source to emit a light beam having a light amount of a recording level and driving the light source to emit a light beam having a light amount of a lower level than the recording level between recording data; Detecting means for detecting the amount of light beam reflected from the optical recording medium of the light beam emitted by the light source; and while the light source irradiates the light beam of the light amount of the recording level, and more than the recording level. Sampling pulse generation for generating a sampling pulse for sampling and holding a signal detected by the detection means while irradiating a light beam of a low level light quantity Generating means, sample and hold means for sampling and holding a signal detected by the detection means in response to the sampling pulse, and a recording level light amount in the light beam based on the detection signal sampled and held by the sample and hold means And control means for controlling the light amount at a level lower than the recording level. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an optical disk 1 formed of a write-once optical recording medium, which is driven to rotate at a constant linear velocity by a spindle motor 2 so that a recording track of the optical disk 1 is The configuration of a recording / reproducing system when the present invention is applied to an optical disk recording / reproducing apparatus that optically records and reproduces digital data in a data format conforming to the CD standard by scanning with light is shown. The optical disc 1 employs a so-called ATIP format, in which a pregroove for tracking servo is wobbled and its wobbling frequency component is modulated so that absolute time information is recorded in advance as auxiliary sub-information. I have. In this optical disk recording / reproducing apparatus, the optical head 10 is driven by a laser driving circuit 20 to emit a laser beam for recording and reproducing digital data, and a laser beam emitted by the laser diode 11. And a photodetector 13 for detecting the reflected light of the laser light emitted from the laser diode 11 from the optical disk 1. By scanning a recording track of the optical disc 1 with a laser beam emitted by the laser diode 11, information is recorded and reproduced on the recording track. The recording system of the optical disk recording / reproducing apparatus is as follows.
And an encoder 23 for converting the digital data D _IN to be recorded is supplied through the input-output interface 22 from an input terminal 21 to the recording data sequence of the data format conforming to the CD standard, the write pulse corresponding to the recording data sequence Is provided to the laser drive circuit 20 and the like. The laser drive circuit 20 drives the laser diode 11 of the optical head 10 with a write pulse corresponding to the recording data sequence by pulse driving. And the above digital data D _IN
The data is recorded on the recording track of the optical disc 1 as the recording data string having a data format conforming to the D standard. The reproducing system of the optical disk recording / reproducing apparatus includes a decoder 32 to which a detection output of the photodetector 13 of the optical head 10 is supplied via a reproducing amplifier circuit 31, and the like. With respect to the detection output of the reflected light from the recording track of the optical disk 1 scanned by the laser light to be reproduced, the reproduction data D _OUT obtained by performing the decoding process corresponding to the encoder 23 of the recording system by the decoder 32 is output. The signal is output from the terminal 40. Further, the control system of the optical disk recording / reproducing apparatus includes a spindle servo circuit 34 to which a detection output from the photodetector 13 of the optical head 10 is supplied via a reproduction amplifier circuit 33. The rotational speed of the optical disk 1 is detected from a wobbling signal of the wobbled pre-groove of the optical disk 1 based on the detection output by the photodetector 13 and the motor drive circuit 3 of the spindle motor 2 is feedback-controlled to detect the rotational speed. 1
Spindle servo control is performed to keep the rotation of the motor at a constant linear velocity. The control system of the optical disk recording / reproducing apparatus includes a head servo circuit 35 to which a detection output from the photodetector 13 of the optical head 10 is supplied via a reproduction amplifier circuit 33. Based on the detection output by the photodetector 13,
Error information such as a focus error and a tracking error of a laser beam applied to the optical disc 1 is detected, and a two-axis actuator (not shown) for driving an objective lens of the optical head 10 is controlled based on the error information. Head servo control such as servo and tracking servo is performed. Further, the control system of the optical disk recording / reproducing apparatus includes an ATIP decoder 36 to which a detection output from the photodetector 13 of the optical head 10 is supplied via the reproduction amplifier circuit 33.
The absolute time information _DATIP is read from the wobbling signal of the optical disk 1 based on the wobbled pre-groove based on the detection output. The absolute time information D _ATIP obtained by the ATIP decoder 36 is supplied to a system controller 37. The system controller 37 has an analog-to-digital conversion function. The detection output of the photodetector 13 of the optical head 10 is supplied to the analog input port from the reproduction amplifier circuit 33 and the optical head 10 Laser diode 11
The detection output of the photodetector 12 for detecting the laser light emitted from the photodetector 12 is supplied via a preamplifier 38. Note that a so-called back monitor photodetector may be used instead of the photodetector 12. The write pulse generating circuit 24
The operations of the laser drive circuit 20 and the like are controlled by the system controller 37 as follows. That is, in the recording operation mode, as shown in FIG. 2, the write pulse generation circuit 24 causes the write pulse generation circuit 24 to generate a write pulse D _WR synchronized with the data clock CK corresponding to the recording data. This is given to the laser drive circuit 20. The write pulse generation circuit 24 performs pulse driving of the laser diode 11 of the optical head 10 by the laser drive circuit 20 in accordance with the write pulse D _WR to generate a recording light beam emitted by the laser diode 11. -die at a predetermined timing t ₁ in time period T _D of the write pulse D _WR after a predetermined time has elapsed τ until the pit P on the optical disk 1 is actually formed first sampling pulse SP ₁
And the recording pit P is recorded on the optical disc 1.
And it outputs the write pulse D minimum pulse interval period T _S predetermined timing t ₂ at the second sampling pulse SP ₂ in the _WR after completion of forming. [0023] Here, in the optical disk recording and reproducing apparatus for optically performing recording and reproducing digital data in a data format compatible with the CD standard, the minimum pulse interval period T _S of the write pulse D _{W R} is 3 channel clocks It is set to correspond to the period. Further, in the write pulse generating circuit 24, the first sampling pulse SP ₁ and the second sampling pulse SP ₂
Can be formed from a data clock CK corresponding to the channel clock and recording data synchronized with the data clock CK. Further, the laser driving circuit 20 is configured to pulsed light quantity L _A recording level laser diode 11 of the optical head 10 in response to the write pulse D _WR, the period between each write pulse D _WR among T ₀ is a high frequency driving the laser diode 11 at a light volume L _B of the playback level. By the pulse driving of the laser diode 11 by the laser driving circuit 20, a recording pit P corresponding to the write pulse D _WR is formed on the optical disc 1 by a recording light beam emitted by the laser diode 11 in a predetermined manner. It is formed with a time delay τ, whereby the recording data is recorded. In this embodiment, the system controller 37 outputs the detection output from each of the photodetectors 12 and 13 of the optical head 10 to a first sampling pulse S formed by the write pulse generation circuit 24.
And sampled at P _1, on the basis of the sampling value, and controls the operation of the laser drive circuit 20, automatically adjusts the light amount L _A of the laser diode 11 recording level of the next of the optical head 10 Control. [0027] That is, during a period in which the laser diode 11 is formed recording pit P is actually on the optical disc 1 by the recording light beam emitted, and the light amount L _A of the laser beam the laser diode 11 is radiated , the difference between the light amount _{L C} of the reflected light by the above optical disc 1 _[L a -L
_C] or the ratio [L _{C /} L _A] is to adjust the light amount L _A of the laser diode 11 recording level of the optical head 10 to a predetermined value, reflected light of the light beam is a predetermined modulation factor in so that the optimum writing light quantity L _a modulated. Further, the system controller 37 includes:
A detection output from the photodetector 13 of the optical head 10 is sampled by a _second sampling pulse SP2 formed by the write pulse generation circuit 24, and a recording pit P is formed on the optical disc 1 based on the sampling value. as the light amount L _D of the reflected light in the predetermined section T _S after completion of a predetermined amount, and controls the operation of the laser drive circuit 20, the laser during T ₀ between each write pulse D _WR diode 11 is performing a so-called APC control to maintain the amount of light L _B of the reproduction level of the light beam emitted in a predetermined light amount. Here, as shown in FIG. 3, for example, the laser drive circuit 20 includes differential transistors 20A and 20A in which the laser diode 11 is connected to one collector.
B, a first variable current source 20C commonly connected to the emitters of the differential transistors 20A and 20B, the laser diode 11, and the differential transistor 20.
A, a second variable current source 20E and the like connected via a choke coil 20D to a connection point with one of the collectors of the pair A and 20B. The system controller 37 controls the current of the first variable current source 20C. by controlling the value, the automatic setting control of the write light intensity L _a is made,
APC control is performed by controlling the current value of the second variable current source 20E. Further, the spindle servo circuit 34,
Head servo circuit 35 and the ATIP decoder 35 incorporates a sampling means for sampling a detection output of the photodetector 13 of the optical head 10 at a second sampling pulse SP ₂ which is formed by the write pulse generating circuit 24, based on the detection output of the photo detector 13 in the period T _S after completion of formation of the recording pits P with respect to the optical disk 1, the above-described spindle servo control operation, a forming processing operation of the head servo control operation and absolute time information D _ATIP performed ing. The detection output obtained by the photodetector 13 of the optical head 10 in the in the interval T _S after completion of formation of the recording pits P with respect to the optical disk 1, detects the reflected light from the non-recorded portion between the recording pits P Therefore, there is no influence of the recording pit P, that is, the influence of the recording data. [0032] Thus, in this embodiment, the photodetector 13 of the optical head 10 during the interval _{T S}
APC control operation by the system controller 37, spindle servo control operation by the spindle servo circuit 34,
The head servo control operation by the head servo circuit 35 and the absolute time information D by the ATIP decoder 35
_{The ATIP} formation processing operation and the like can be reliably performed with high accuracy, and a highly reliable recording operation on the optical disc 1 can be performed. In the optical recording apparatus according to the present invention, while the light source is irradiating the light beam of the light amount of the recording level, and irradiating the light beam of the light amount of the lower level than the recording level. In the meantime, the signal detected by the detecting means for detecting the light amount of the reflected light beam from the optical recording medium is sampled and held by the sample holding means, and the light amount of the recording level in the light beam and the level lower than the recording level Since the light amount is controlled, it is possible to accurately detect the reflected light amount which is reduced by being affected by the pits formed on the optical recording medium according to the recording data, and it is possible to perform highly accurate recording laser power control. The laser power control should be performed with high accuracy while irradiating a light beam with a light amount lower than the recording level after the pit formation. Can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a configuration of a recording / reproducing system of an optical disc recording / reproducing apparatus to which the present invention is applied. FIG. 2 is a time chart for explaining an operation of a recording operation mode in the optical disc recording / reproducing apparatus. FIG. 3 is a circuit diagram showing a configuration example of a laser drive circuit used in the optical disk recording / reproducing apparatus. FIG. 4 is a waveform diagram showing a state of a change in the amount of reflected light from the optical disk when pits are formed on the optical disk with a light beam. [Description of Signs] 1 optical disk, 10 optical head, 11 laser diode, 12, 13 photodetector, 20 laser drive circuit, 24 write pulse generation circuit, 34 spindle servo circuit, 35 head servo circuit, 36 ATI
P decoder, 37 system controller

Claims (1)

Claims: 1. A light source for irradiating a light beam for recording information by forming pits on an optical recording medium, and the light source having a recording level light beam corresponding to recording data. And driving means for driving the light source so as to emit a light beam having a light amount lower than the recording level between the recording data and the recording data. Detecting means for detecting the amount of the reflected light beam from the optical recording medium; and irradiating the light source with the light beam having a light amount lower than the recording level while irradiating the light beam with the recording level light from the light source. Sampling pulse generating means for generating a sampling pulse for sampling and holding a signal detected by the detecting means while Sample-and-hold means for sampling and holding a signal detected by the detection means in response to the detection signal sampled and held by the sample-and-hold means; An optical recording apparatus comprising: a control unit for controlling the amount of light.