JP2007172694A - Recording power control method for optical disk drive, and optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk drive capable of correctly recording information by correctly setting the bottom level of a laser light source and suppressing the fluctuation of light emitting power caused by the heat of laser beams. <P>SOLUTION: In the optical disk drive in which an optical disk is irradiated with laser beams by a light emitting strength patten composed of a multipulse part which comprises a peak level having high light emitting strength and a bottom level having a low light emitting strength level and an erasing part which is intermediate between the peak level and the bottom level and erases recorded information to record and reproduce information, the average current iAVE of the multipulse part and current iBS of the erasing part during recording are controlled as iAVE = iBS to thereby reduce a change in the temperature of LDs (laser diode) of the multipulse part and the erasing part. By making bottom power not more than 0mW, the bottom current iBT is determined to be a threshold current iTH or less, thereby suppressing the fluctuation of power caused by the temperature of the LDs during recording. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording power control method for an optical disc apparatus that records and reproduces information on an optical disc using an optical pickup, and an optical disc apparatus.

  2. Description of the Related Art An optical disc device is a device that records and reproduces information on an optical disc such as a CD (Compact Disc) -ROM (Read Only Memory), a CD-R (Recordable) / RW (ReWritable), a DVD (Digital Versatile Disc), and the like. It has been put into practical use, and is being actively developed for application in various fields, higher performance, and higher speed. Particularly recently, along with the rapid market expansion of personal computers, the penetration rate of built-in optical disk devices in personal computers has increased.

  Here, the configuration of the optical disc apparatus will be described with reference to FIG. FIG. 6 is a block diagram of the pickup control unit of the optical disc apparatus.

  In FIG. 6, the pickup module 2 moves a spindle motor 3 for rotating the optical disc 1, an optical pickup 4 for reading an information signal of the optical disc 1, and a carriage 5 on which the optical pickup 4 is mounted in the radial direction of the optical disc 1. And a feed unit 6 for causing the The feed unit 6 includes a feed motor 7, a gear (not shown), a screw shaft (not shown), and the like, and the carriage 5 moves between the inner periphery and the outer periphery of the optical disk 1 by rotating the feed motor 7. It is configured.

  The analog signal processing unit 8 generates a focus error signal and a tracking error signal based on a signal output from an optical sensor (not shown) in the optical pickup 4 in the carriage 5 provided in the pickup module 2. To the servo processing unit 9.

  The focus error signal is a signal indicating a deviation in the focal direction between the light beam spot emitted from an objective lens (not shown) provided in the optical pickup 4 and the recording surface of the optical disc 1. The tracking error signal is a signal indicating a deviation in the optical disc radial direction between the light spot and the information track of the optical disc 1.

  The analog signal processing unit 8 extracts a low frequency component of the tracking error signal to generate a lens position signal indicating the relative positional relationship between the objective lens and the carriage 5 and drives the motor via the servo processing unit 9. To the unit 10.

  The servo processing unit 9 includes an ON / OFF circuit, an arithmetic circuit, a filter circuit, an amplifier circuit, and the like. The servo processing unit 9 performs focus / tracking control of the objective lens so that the light beam spot follows the information track of the optical disc 1, and further a tracking error signal. Feed control is performed so that the objective lens maintains a substantially neutral position using the low-frequency component.

  The digital signal processing unit 11 includes a data slicer, a data PLL circuit, a jitter measurement circuit, an error correction unit, a modulation / demodulation unit, a buffer memory, a laser control unit, and the like, and is effective for the host (HOST in the figure) side. It is transferred as data.

  During the recording operation, the digital signal processing unit 11 modulates data sent from the host, and the laser control unit sends a predetermined light source such as a laser diode (not shown) in the optical pickup 4 via the laser driving unit 12. Current is supplied, the light source is caused to emit light in a pulse shape, for example, and recording is performed on the information track of the optical disc 1. The controller 13 controls the entire servo unit configured as described above.

  An example of a method for controlling the recording power in an optical disc apparatus is described in Patent Document 1.

  In laser light emission recording in an optical disc apparatus, if light emission cannot be performed with a desired power, there is a concern that the recording / reproducing performance is deteriorated. Further, there is a case where the power fluctuates due to the temperature fluctuation of the laser diode, which causes a problem of deteriorating the recording / reproducing performance.

  A recording light emission waveform for forming a pit in the case of a medium that records and reproduces information such as CD-RW, DVD-RW, and + RW will be described. FIG. 7 is an explanatory diagram showing the recording light emission waveform. As shown in FIG. 7, the recording light emission waveform forming the pit has a peak power level where the light emission intensity is maximum, a bottom power level where the light emission intensity is minimum, and an erase power level which is an intermediate value thereof. An erase portion and a multi-pulse portion are formed by the light emission waveform shown in FIG. This recording light emission waveform is a waveform in which pits are formed by repeating rapid heating and rapid cooling on the medium by repeating the light beam with high power and low power. That is, it is formed of an erase portion for erasing recorded information, and a multi-pulse portion composed of a peak level with a higher emission intensity level and a bottom level with a lower emission intensity level.

  FIG. 8 shows a pattern of a current flowing through the laser light source in order to realize this recording light emission waveform. The current that flows to obtain the emission intensity at the bottom power level is the bottom current (iBT), and the emission current at the erase power level is obtained by adding the erase current (iER) to the bottom current (iBT). Will be washed away. Further, in order to obtain the light emission intensity at the peak power level, a peak current (iPK) added is supplied.

FIG. 9 shows the configuration of the D / A converter used to generate these currents. The D / A converter for generating the bottom current (iBT) is the reproduction DAC 26 and the threshold DAC 27, and the D / A converter for generating the erase current (iER) is the erase DAC 25, and generates the peak current (iPK). The D / A converter for doing this is the peak DAC 24. When the bottom-level emission intensity is obtained by the current generated by these D / A converters, only the bottom current (iBT) is caused to flow through the laser light source, and when the erase-level emission intensity is obtained, the bottom current (iBT) is When the current combined with the erase current (iER) is sent to the laser light source to obtain the light emission intensity at the peak level, the current combined with the bottom current (iBT), the erase current (iER), and the peak current (iPK) Sent to a light source.
JP 2000-30276 A

  In an RW type optical disk drive that performs recording using such a recording light emission waveform, particularly when the average current of the multi-pulse part is larger than the current of the erase part (for example, a medium compatible with high-speed recording), a laser diode (LD ) Changes between the multi-pulse part and the erase part, and the relationship between the light emission power and the current (IL characteristic) fluctuates. Due to this influence, the desired recording light emission power cannot be obtained and the light emission waveform is distorted. Sometimes.

  The average current of the multi-pulse part is determined by the peak current (iPK), the multi-pulse duty ratio and the level of the bottom current (iBT). At low speed, the peak power level is about twice the erase power level, and the average current of the multi-pulse part is the same level as the erase part. However, in high-speed media, the peak power level is 2 of the erase power level. Sometimes more than double the power is required.

  FIG. 10 is a diagram showing fluctuations in the light emission waveform caused by the peak power level and the erase power level. As shown in FIG. 10, when the average current of the multi-pulse part becomes larger than the current at the erase power level, the temperature of the LD in the multi-pulse part becomes higher than the temperature of the LD in the erase part. In addition, when the average current increases in the multi-pulse part, the IL characteristic of the LD fluctuates due to temperature change. Since the peak power level and the erase power level are determined based on values measured in advance, it is not possible to follow the temperature fluctuation during the LD emission. For this reason, distortion occurs in the peak power level when the mark is formed, and the erase power level fluctuates when the space is formed. This fluctuation adversely affects the recording characteristics, and information recording is not performed accurately. Due to the influence of the LD temperature change, it is difficult to maintain the light emission intensity level appropriately in the multi-pulse part and the erase part.

  An object of the present invention is to provide a recording power control method for an optical disc apparatus and an optical disc apparatus capable of accurately recording information by appropriately setting a light emission intensity level of a laser light source.

  The present invention has been made to solve the above-described problems, and includes a peak power level at which the emission intensity is maximum, a bottom power level at which the emission intensity is minimum, and an erase power level that is an intermediate value thereof. In an optical disc recording power control method and an optical disc apparatus for recording and reproducing information by irradiating an optical disc with a laser beam with a light emission intensity pattern as described above, the main feature is to make the average current of the multi-pulse part equal to the current of the erase part To do.

  The optical disc recording power control method and optical disc apparatus according to the present invention make it possible to suppress fluctuations in recording light emission power due to temperature changes in the LD by making the average current of the multi-pulse part equal to the current of the erase part. It is possible to suppress the temperature change between the part and the multi-pulse part, thereby generating a desired recording light emission pulse and maintaining the recording characteristics in a good state.

  An object of the present invention is to provide an optical disc apparatus capable of accurately recording information by appropriately setting a light emission intensity level of a laser light source, and a peak power level with a maximum light emission intensity and a light emission intensity. In an optical disc apparatus that records and reproduces information by irradiating an optical disc with laser light with a light emission intensity pattern consisting of a minimum bottom power level and an erase power level that is an intermediate value between them, the average current of the multi-pulse part is erased. It was realized by making it equal to the current of the part.

  A first invention made to solve the above-described problems is a multi-pulse unit configured to have a peak power level having a maximum light emission intensity and a bottom power level having a minimum light emission intensity for recording on an optical disc. Recording and reproduction of information by irradiating an optical disc with a laser beam with a light emission intensity pattern comprising an erase portion composed of an erase power level for erasing recorded information between the peak power level and the bottom power level In the recording power control method of the optical disc apparatus, the current is controlled so that the average current of the multi-pulse part becomes equal to the current of the erase part. The average current of the multi-pulse part is the current of the erase part. By controlling the currents to be equal, the light emission parameters of the multi-pulse part and erase part due to temperature fluctuations of the LD It is possible to suppress distortion of the change and the recording light emission waveform of the over, the stable recording power light emission, it is possible to maintain the recording characteristics in a good condition.

  A second invention made to solve the above problems is a recording power control method for an optical disk apparatus according to the first invention, wherein the bottom current during recording on the optical disk is a light emission pattern in which the bottom current is 0 mW level which is equal to or less than a threshold current. As a result, the temperature rise of the LD can be suppressed, and the current consumption of the drive can also be reduced.

  According to a third aspect of the present invention for solving the above-described problems, in the control for reducing the bottom current to the 0 mW level that is equal to or lower than the threshold value according to the second aspect, the threshold current is driven when the current is driven from the 0 mW level to the peak power level. In the following, correction is made in consideration of fluctuations in the peak power level caused by delays in the rise and fall times of the current, and fluctuations in the average power of the multipulse part are suppressed, and the peak of the emission power is maximum. Light can be emitted at a desired power level.

  A fourth invention made to solve the above problems is a recording power control method for an optical disc apparatus according to the second invention, wherein the bottom current is made as small as possible in an LD that is not affected by the distortion of the light emission power due to temperature. Thus, it is possible to suppress the heat generation of the LD.

  A fifth invention made to solve the above-described problem is a multi-pulse unit configured to have a peak power level having a maximum light emission intensity and a bottom power level having a minimum light emission intensity for recording on an optical disc. In an optical disc apparatus that records and reproduces information by irradiating an optical disc with laser light with a light emission intensity pattern comprising an erase portion composed of an erase power level intermediate between the peak power level and the bottom power level, the average of the multi-pulse portion A means for controlling the current so that the current becomes equal to the current of the erase portion, and the temperature fluctuation of the LD is controlled by controlling the current so that the average current of the multi-pulse portion becomes equal to the current of the erase portion. Fluctuations in the emission power of the multi-pulse part and erase part and distortion of the recorded light emission waveform due to the The recording power light emission, it is possible to maintain the recording characteristics in a good condition.

  A sixth invention made to solve the above-mentioned problems is a light emission intensity pattern in which, in the fifth invention, the bottom current during recording on the optical disc is set to a 0 mW level equal to or lower than a threshold current, thereby producing an LD. It becomes possible to suppress the heat generation.

  The seventh invention made to solve the above-mentioned problems is the control of reducing the bottom current to 0 mW level below the threshold current of the sixth invention, when driving the current from 0 mW level to the peak power level. A means to correct the pulse width of the multi-pulse part in consideration of fluctuations in the peak power level caused by the rise and fall times of the current below the threshold current, suppressing fluctuations in the average power of the multi-pulse part Thus, the peak power level with the maximum light emission power can be emitted with a desired power.

  Hereinafter, a method for adjusting a light emission intensity level of an optical disc device and an optical disc device according to an embodiment of the present invention will be described in detail.

  The pickup control unit of the optical disc apparatus to which the present invention is applied is the same as that shown in the block diagram shown in FIG. 6 described in the background section.

  In FIG. 6, the pickup module 2 moves a spindle motor 3 for rotating the optical disc 1, an optical pickup 4 for reading an information signal of the optical disc 1, and a carriage 5 on which the optical pickup 4 is mounted in the radial direction of the optical disc 1. It is comprised by the feed part 6 for making it do. The feed unit 6 includes a feed motor 7, a gear (not shown), a screw shaft (not shown), and the like, and the carriage 5 moves between the inner periphery and the outer periphery of the optical disk 1 by rotating the feed motor 7. It is configured.

  The analog signal processing unit 8 generates a focus error signal and a tracking error signal based on a signal output from an optical sensor (not shown) in the optical pickup 4 in the carriage 5 provided in the pickup module 2. To the servo processing unit 9. In addition, the analog signal processing unit 8 extracts a low frequency component of the tracking error signal, thereby generating a lens position signal indicating a relative positional relationship between the objective lens and the carriage 5 and outputs the lens position signal to the motor driving unit 10. The analog signal processing unit 8 includes a sample and hold circuit 21 shown in FIG.

  The servo processing unit 9 includes an ON / OFF circuit, an arithmetic circuit, a filter circuit, an amplifier circuit, and the like. The servo processing unit 9 performs focus / tracking control of the objective lens so that the light beam spot follows the information track of the optical disc 1, and further a tracking error signal. Feed control is performed so that the objective lens maintains a substantially neutral position using the low-frequency component.

  The digital signal processing unit 11 includes a data slicer, a data PLL circuit, a jitter measurement circuit, an error correction unit, a modulation / demodulation unit, a buffer memory, a laser control unit, and the like, and is effective for the host (HOST in the figure) side. Data is transferred. The digital signal processing unit 11 includes a power control unit 22 shown in FIG.

  FIG. 1 is a block diagram for realizing a light emission current adjusting method according to an embodiment of the present invention. In FIG. 1, a laser unit 20 emits laser light to an optical disk 1, and a front light signal that is waveform information of a light emission intensity pattern of the laser unit 20 is sent to a sample hold circuit (S / H circuit) 21. It is done. The sample and hold circuit (S / H circuit) 21 detects the erase power and the average power and inputs them to the power control unit 22. Further, the power control unit 22 sends a sample hold (S / H) timing signal to the sample hold circuit (S / H circuit) 21 to set the sample timing of the sample hold circuit (S / H circuit) 21.

  Based on the input erase power and average power, the power control unit 22 determines set values of peak current, erase current, and bottom current that fluctuate with temperature rise due to recording, and the set values are sent to the laser driver 23, respectively. The

  The configuration of the laser driver 23 is the same as that of the conventional technique shown in FIG.

  In FIG. 9, the laser driver 23 includes a peak DAC 24 that generates a peak current, an erase DAC 25 that generates an erase current, a reproduction DAC 26 that generates a reproduction current, and a threshold DAC 27 that generates a threshold current. The current obtained by adding the reproduction current and the threshold current is the bottom current.

  At the time of recording operation, as shown in FIG. 6, the data sent from the host is modulated by the digital signal processing unit 11, and the LD (not shown) in the optical pickup 4 is transmitted by the laser control unit via the laser driving unit 12. A predetermined current is supplied to a light source such as), and the light source is caused to emit light in a pulse shape, for example, and recording is performed on an information track of the optical disc 1. The laser driver 12 includes a laser driver 23 shown in FIG.

  FIG. 2 is a flowchart for controlling the bottom current according to the embodiment of the present invention. FIG. 3 is a waveform diagram showing the relationship (IL characteristic) between the light emission intensity level and the light emission current according to the embodiment of the present invention. FIG. 4 is a diagram showing the setting of the average current of the multi-pulse part and the current of the erase part according to the embodiment of the present invention.

  The recording power control method will be described with reference to FIGS.

  In FIG. 3, the horizontal axis represents the current flowing through the laser light source, and the vertical axis represents the emission intensity of the laser light source. Here, the relationship of the light emission intensity with respect to the drive current of the LD is referred to as an IL characteristic. In the recording light emission waveform, the bottom current iBT is required to obtain the bottom power level Pbt having the minimum light emission intensity. Further, in order to obtain the erase power level Per whose light emission intensity is an intermediate level, a current obtained by adding the erase current iER to the bottom current iBT is required. Further, in order to obtain the peak power level Ppk having the maximum light emission intensity, the peak current iPK added to the bottom current iBT and the erase current iER is required. Here, the bottom current iBT required at the bottom power level Pbt where the light emission intensity is minimum is the threshold current iTH which is a current of the portion where the light emission intensity is 0 mW in the IL characteristic, and the bottom when the LD starts to emit light. It consists of a reproduction current iRD that is a current until the emission intensity of the power level Pbt is obtained.

  In high-speed recording, the light emission intensity at the peak power level may be larger than the light emission intensity at the erase power level, the average current in the multipulse part exceeds the average current in the erase part, and the temperature of the multipulse part and erase part The difference will increase. In this case, as shown in FIG. 10 described above, the temperature of the LD rises during light emission of the multi-pulse part, the LD characteristic of the LD fluctuates, and the power decreases. In the erase part, the LD temperature raised in the multi-pulse part returns to the original value, so that the IL characteristic also returns to the initial value and fluctuates to a desired light emission power. Further, since the light emission intensity at the peak power level is larger than that in the erase portion, the difference between the average current in the multipulse portion and the average current in the erase portion becomes large. As a result, when shifting from the erase power emission period to the multi-pulse emission period, the IL characteristic of the erase emission period, which is constant, changes due to the change of the IL characteristic of the LD in the multi-pulse emission period. The light emission level is lowered toward the end of the pulse, and the waveform is distorted. Therefore, it is necessary to reduce the difference in average current between the multi-pulse part and the erase part. In order to make this average current equal, it is possible to keep the peak power level appropriate by appropriately controlling the average current by changing the bottom current of the multi-pulse part.

  In FIG. 4, the first pulse shown in (i) is called a top pulse, the second and subsequent pulses shown in (ii) are called multi-pulses, and the pulse that outputs the final bottom power level shown in (iii) is shown. This is called a cooling pulse. In the present embodiment, the pulse widths of these pulses can be set to arbitrary widths by the power control unit 22 of FIG.

  Here, as an example, a description will be given of a light emission intensity pattern with a recording mark length of 6 [T], a top pulse width of Ttop [T], a multipulse width of Tmp [T], and a cooling pulse width of Tcl [T]. Further, in FIG. 4, iPK is a peak current, iER is an erase current, and iBT is a bottom current. IAVE indicated by a broken line in FIG. 4 indicates an average current of the multi-pulse part. The average current iAVE in the multi-pulse part is obtained by (Equation 1).

iAVE = [(Ttop + 3 × Tmp) × (iPK + iER + iBT) + {3 × (1−Tmp) + Tcl} × iBT] / (Ttop + Tcl + 3) (Equation 1)
The erase portion current iBS is obtained by adding the erase current iER and the bottom current iBT. Therefore, by making the multipulse part average current iAVE equal to the erase part current iBS, distortion of the recording light emission waveform due to temperature can be suppressed.

  As a method for adjusting the average current iAVE of the multi-pulse part without changing the peak power level, in this embodiment, the bottom power level of the multi-pulse part is set to be lower and the bottom current is reset as iBT11. To control the average current iAVE of the multi-pulse part.

  A method for setting the bottom current iBT11 will be described with reference to FIG.

  FIG. 2 is a flowchart for controlling the bottom current. In step 101, the average current iAVE of the multi-pulse part and the current iBS of the erase part are calculated. Next, the magnitude comparison between the average current iAVE of the multi-pulse part calculated in step 102 and the current iBS of the erase part is performed. In steps 103 and 104, conditional branching is performed according to the magnitude relationship between the average current iAVE in the multi-pulse part and the current iBS in the erase part. When iAVE is larger than the current iBS of the erase portion, iAVE-iBS is calculated as shown in step 105, and an average current difference ΔiBT is calculated. If iAVE is smaller than the current iBS of the erase portion, iBS-iAVE is calculated as shown in step 106, and an average current difference ΔiBT is calculated. Based on the average current difference ΔiBT calculated in this way, if iAVE is larger than the current iBS of the erase portion, iBT + ΔiBT shown in step 107 is calculated, and the obtained bottom current iBT11 is calculated. When iAVE is smaller than the current iBS of the erase portion, iBT−ΔiBT shown in step 108 is calculated, and a desired bottom current iBT11 is calculated.

  The bottom current iBT11 thus determined is set to a bottom DAC that is a D / A converter for generating a bottom current, and when ΔiBT is smaller than the current iER of the erase portion, the bottom current fluctuated from the current bottom current iBT. The iBT 11 obtained by subtracting ΔiBT is set to the reproduction DAC 26 and the threshold DAC 27 that are D / A converters for generating a bottom current. In this way, the average current iAVE of the multi-pulse part is controlled to be equal to the current iBS of the erase part. By carrying out the above control, the average current of the LDs in the multi-pulse part and erase part can be kept constant, temperature fluctuations can be suppressed, and a stable recording light emission pulse can be maintained.

  In the above control, a recording power control method for setting the bottom power of the multi-pulse part to 0 mW level will be described with reference to FIG. FIG. 4 shows the light emission pulse and drive current configuration for recording on the RW media. As shown in FIG. 3, the bottom current iBT is configured by adding a threshold current iTH for driving up to a threshold at which the LD starts light emission and a reproduction current iRD for driving from the threshold current level to the bottom level where the light emission intensity is low. is there. That is, the configuration of the bottom current is iBT = iTH + iRD. The current iBS of the erase portion is obtained by adding the reproduction current iRD of the bottom current to the erase current iER. This current value is set in the erase DAC 25 which is a D / A converter for generating an erase current. The bottom current iBT is determined only for the threshold current iTH and is obtained as iBT = iTH, and is set to the bottom DAC that is a D / A converter for generating the bottom current. As a result, the bottom power with the minimum light emission intensity can be set to 0 mW without changing the peak power level with the maximum light emission intensity, and the current at the bottom level of the multi-pulse part can be reduced.

  Here, since the bottom power is 0 mW or less, there is no fluctuation in the bottom power level even if the threshold current iTH is further reduced (referred to as bottom extraction in this embodiment). By further reducing the bottom current iBT and further reducing the drive current, the bottom current can be reduced without changing the bottom power. For this reason, it is possible to suppress the heat generation of the LD due to high power in high-speed recording, etc., and it is possible to suppress the fluctuation of the light emission power due to the fluctuation of the IL characteristic of the LD that fluctuates in temperature. Can be maintained. Furthermore, in an LD in which the variation of the IL characteristic due to temperature is small, it is possible to reduce the power consumption of the drive by making the bottom current as low as possible.

  FIG. 5 is a diagram showing a change in the light emission waveform when the bottom power level is changed. When controlling the bottom power to 0 mW or less, if the bottom current is reduced below the threshold current, it is necessary to drive a current from the current level below the threshold current to the peak power level, and the rise and fall times of the current There are cases where the light emission power due to the fluctuations. When the current is reduced below the threshold current, the rise and fall characteristics of the light emission pulse are deteriorated, and the pulse emits light shorter than the case where the light emission waveform of the multi-pulse part draws the bottom current. As a result, the desired power cannot be emitted.

  A recording power control method for correcting the fluctuation of the light emission pulse will be described with reference to FIG. In FIG. 5, a solid line waveform indicated by (A) in FIG. 5 is a recording light emission waveform of the RW media when the bottom power level is not reduced. In the recording light emission waveform of the RW medium when the bottom power level is not reduced, the bottom power level is Pbt and the peak power level is Ppk. The broken line waveform shown in FIG. 5B is a recording light emission waveform when the above-described bottom power level is controlled to 0 mW or less. In the light emission waveform indicated by the broken line with the bottom power level being 0 mW or less, the bottom power level is Pbt ', and the current is driven from the bottom power level Pbt' to the peak power level Ppk. Since the bottom power level Pbt ′ is lower than the bottom power level Pbt in a state where normal bottom extraction is not performed, the rise time becomes long before driving to the peak power level Ppk, and as a result, the width of the light emission pulse becomes short. . As a result, the set multi-pulse width Tmp becomes shorter as the rise time increases and the multi-pulse width Tmp ′ that actually emits light becomes shorter. Therefore, it becomes impossible to emit light with a pulse having a desired multi-pulse width, the average power of the multi-pulse part also fluctuates, and the peak power level Ppk with the maximum light emission power cannot be emitted with the desired power.

  A recording light emission control method for eliminating this phenomenon will be described below.

  The multi-pulse width of the RW recording light emission waveform in a state where the bottom power level is normal and the bottom extraction is not performed is Tmp, and the light emission waveform of the recording of the RW media in the state where the bottom extraction is performed as shown by a broken line in FIG. The multi-pulse width is Tmp ′. Assuming that the multipulse width reduced by the bottom extraction is ΔTmp, the multipulse width ΔTmp can be calculated by the following (Equation 2).

ΔTmp = Tmp−Tmp ′ (Expression 2)
The fluctuation of the light emission pulse is corrected by setting a long multi-pulse width of the light emission waveform of the recording of the RW media in the state where the bottom extraction is performed. That is, the variation ΔTmp of the multi-pulse part due to the bottom current reduction is measured in advance, and Tmp = Tmp ′ + ΔTmp is set and corrected according to the variation, whereby light can be emitted with a desired light emission power.

  In the control for controlling the bottom power to 0 mW or less, in the LD that is less affected by the distortion of the light emission power due to the temperature, it is possible to suppress the heat generation of the LD by making the bottom current as small as possible.

  The present invention provides an optical disc apparatus capable of suppressing variations in bottom power during recording, reducing power fluctuation due to heat of the LD, suppressing heat generation of the LD, and maintaining recording characteristics in a good state. Available. It can also contribute to lower power consumption of the optical disk drive.

The block diagram for realizing the light emission current adjustment method according to the embodiment of the present invention. Flowchart for controlling bottom current according to an embodiment of the present invention The figure which shows the relationship (IL characteristic) of the light emission intensity level and light emission current which concerns on embodiment of this invention. The figure which shows the setting of the average electric current of the multipulse part which concerns on embodiment of this invention, and the electric current of an erase part The figure which shows the change of the light emission waveform when changing the bottom power level which concerns on embodiment of this invention. Block diagram of pickup control unit of optical disk apparatus The figure which shows the waveform of the record emission intensity in the past The figure which shows the pattern of the electric current sent through the laser light source in the past The figure which shows the structure of the D / A converter used in order to generate | occur | produce the light emission current in the past. Diagram showing changes in emission waveform due to temperature fluctuations in the past

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk 2 Pickup module 3 Spindle motor 4 Optical pick-up 5 Carriage 6 Feed part 7 Feed motor 8 Analog signal processing part 9 Servo processing part 10 Motor drive part 11 Digital signal processing part 12 Laser drive part 13 Controller 20 Laser unit 21 Sample hold circuit (S / H circuit)
22 Power control unit 23 Laser driver (LDD)
24 peak D / A converter (peak DAC)
25 Erase D / A Converter (Erase DAC)
26 Playback D / A Converter (Reproduction DAC)
27 Threshold D / A Converter (Threshold DAC)

Claims (7)

A multi-pulse part composed of a peak power level with a maximum light emission intensity and a bottom power level with a minimum light emission intensity for recording on an optical disc, and recording between the peak power level and the bottom power level. In the recording power control method of an optical disc apparatus for recording / reproducing information by irradiating the optical disc with a laser beam with a light emission intensity pattern comprising an erase portion configured with an erase power level for erasing the recorded information, the multi-pulse A recording power control method for an optical disc apparatus, wherein the current is controlled so that an average current of a portion becomes equal to a current of the erase portion. 2. The recording power control method for an optical disc apparatus according to claim 1, wherein a bottom current during recording on the optical disc is set to a light emission intensity pattern that reduces to a 0 mW level equal to or less than a threshold current. In the control to reduce the bottom current to the 0 mW level below the threshold current, when driving the current from the 0 mW level to the peak power level, the fluctuation of the peak power level caused by the delay of the rise and fall times of the current below the threshold current 3. The recording power control method for an optical disc apparatus according to claim 2, wherein the pulse width of the multi-pulse part is corrected in consideration of the above. 3. The recording power control method for an optical disc apparatus according to claim 2, wherein the bottom current is made as small as possible in a laser diode that is not affected by the distortion of the light emission power due to temperature. A multi-pulse part composed of a peak power level with a maximum light emission intensity and a bottom power level with a minimum light emission intensity for recording on an optical disc, and recording between the peak power level and the bottom power level. In an optical disk apparatus that records and reproduces information by irradiating an optical disk with laser light with a light emission intensity pattern composed of an erase section configured with an erase power level for erasing the recorded information, an average current of the multi-pulse section is calculated. An optical disc apparatus comprising means for controlling a current so as to be equal to a current of the erase section. 6. The optical disc apparatus according to claim 5, wherein a bottom emission current during recording on the optical disc is a light emission intensity pattern with a 0 mW level equal to or less than a threshold current. In the control to reduce the bottom current to 0 mW level below the threshold current, when the current is driven from 0 mW level to the peak power level, the fluctuation of the peak power level due to the rise and fall time of the current below the threshold current is considered 7. The optical disk apparatus according to claim 6, further comprising means for correcting a pulse width of the multi-pulse part.

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