JP2006209823A - Laser power controller for optical disk device, and laser power control program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the excessive light emission of a laser light source, caused by the sudden change or the like in the ambient temperature of an optical disk device for executing power control of the laser light source by APC. <P>SOLUTION: The output of a photodiode 5 is subjected to I/V conversion, and passed through a sample-and-hold circuit 7, an LPF 8 and an A/D conversion circuit 9 to be converted into digital data. A comparator circuit 10 obtains a difference value δ, between a power monitor value α and a target value β, and a compensator circuit 11 generates and outputs the control data of an LD (laser disk) drive circuit 1 b by using the difference value δ to control power. Based on the LD characteristic data, containing temperature characteristics stored in a memory 23, V-I conversion resistance in an LD drive circuit 1, a reference voltage value or the like for deciding the opening of a D/A converter circuit 12, and the temperature data of a temperature sensor 21, a limiting value generator circuit 22 generates a limiting value L corresponding to an ambient temperature, and by generating a data limiting circuit 20 digital data, having a limiter to be sent to the D/A converter circuit 12, excessive light emission caused by sudden temperature change is suppressed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention belongs to a technical field of an optical disk apparatus that records / reproduces information on / from an optical disk using a laser, and in particular, a laser power control apparatus and a laser in an optical disk apparatus that controls laser power by an APC (Auto Power Control) method. It relates to a power control program.

  In an optical disc apparatus, when performing data recording / reproducing operation by irradiating laser light from a laser diode as a light source to an optical disc such as DVD-RW as an information recording medium, a laser called APC (Auto Power Control) system Power control devices (mechanisms) are frequently used.

  This APC laser power control apparatus is intended to suppress fluctuations in laser power caused by temperature changes or the like, and to maintain a stable optimum laser power at all times in the recording / reproducing mode.

  For example, as a known technique, there is a laser diode (LD) power control circuit in which the APC system having a block configuration as shown in FIG.

  In FIG. 5, the laser light of the laser diode 2 that emits light by being driven by a laser diode driving circuit (hereinafter also referred to as an LD driving circuit) 1 forms a light spot on the optical disk 4 via an optical system such as a beam splitter 3. The reflected light is guided to the photodiode (PD) 5 which is a photodetector by the beam splitter 3, and the beam power of the laser diode 2 is detected as a current value.

  The detected current is converted into a voltage value by a current-voltage conversion circuit (hereinafter also referred to as an IV conversion circuit) 6, and a predetermined power level by a sample and hold circuit (hereinafter also referred to as an S / H circuit) 7. The high-frequency component of the output value is removed by the low-pass filter (LPF) 8 and then converted into digital data of the voltage average value by the AD conversion circuit 9.

  The digital data of the voltage average value is output to the comparison circuit 10 as an optical power monitor value α, and the comparison circuit 10 compares a predetermined power target value β inputted externally with the optical power monitor value α, The difference value δ is output to the compensation circuit 11.

  The compensation circuit 11 generates the control data Dapc for the LD driving circuit 1 by phase compensating the difference value δ input from the comparison circuit 10 based on the input set value relating to the phase compensation. Dapc is output to the DA converter circuit 12 together with a preset peak / erase power setting value.

  The LD driving circuit 1 performs current control on the output power of the laser diode 2 based on the control signal Cs converted into a voltage value by the DA conversion circuit 12, but the control data Dapc uses the difference value δ as the control data Dapc. Since it is generated as data that converges to 0, the optical power monitor value α quickly converges to the power target value β by the operation of the feedback loop, and the output of the laser diode 2 corresponds to the power target value β. Controlled to level.

  The power target value β is a value that gives an optimum beam power in the recording / reproducing mode, and normally different values are set during recording and reproduction.

  Further, in the recording mode, as shown in the signal timing chart for explaining the operation state of the laser power control apparatus in FIG. 7, the pulse is generated by the strategy generation circuit 14 based on the modulation signal a from the modulation circuit 13. Based on the ON / OFF signal (erase power selection signal b, peak power selection signal c), the LD driving circuit 1 causes the laser diode 2 to blink in a multi-pulse like a light emission waveform d.

  Many proposals have been made on the APC laser power control device (mechanism) as described above from various viewpoints.

  For example, in the following [Patent Document 1], as an optical disc apparatus having an APC circuit capable of stabilizing the laser power while keeping the operation speed of the sample and hold circuit low, an output detecting means for monitoring the output of the laser beam, Sample hold means for sample-holding the level of the monitor signal, comparison means for comparing the sample-held signal level with a reference level to detect a difference, and controlling the current supplied to the semiconductor laser according to the difference and the recording signal Driving means for converting, a multi-pulse generating means for converting a recording pulse into a pulse train according to the pulse width, and a pulse control means for making the central portion of the recording pulse converted into a pulse train a non-pulse part when the recording pulse has a predetermined length When the recording pulse has a predetermined length, the timing to indicate the sample hold timing Configuration is disclosed comprising a grayed signal generating means.

  [Patent Document 2] below describes a laser diode (LD) protection circuit including an automatic current control circuit that controls an LD current to be a set value. Monitors the light emission power or temperature, stops the automatic current control when the light emission power exceeds the set value or when the temperature falls below the set temperature, limits the LD current, and sets the light emission power or temperature. An LD protection circuit is disclosed that includes an LD current limiting circuit that restores automatic current control when it is within range.

Japanese Patent Laid-Open No. 11-134692

Japanese Patent Application Laid-Open No. 11-121853

  By the way, the laser diode 2 used in the optical disc apparatus generally has characteristics of light emission power, current value and temperature characteristic as shown in FIG.

  That is, no light is emitted until the current value I reaches the threshold value Ith, and linear characteristics are exhibited above Ith. Further, when light is emitted with a laser power equal to or greater than the maximum rated value Iop as shown in FIG. 6, the life of the laser diode 2 is reduced, and in the worst case, the laser diode itself is destroyed.

  Further, the current-light emission power characteristic of the laser die auto 2 varies as shown in FIG. 6 depending on the ambient temperature. That is, when the temperature becomes high, both Ith and Iop become high, and conversely, when the temperature becomes low, both Ith and Iop become low.

  Normally, if the ambient temperature changes to some extent, the above APC power control can sufficiently absorb the change in the above characteristics, but immediately after operating the optical disk device in a warm place, the laser moves to a low temperature place and turns on the laser. In order to speed up the light emission rise at the time of transition from reproduction to recording, when feedforward control is performed, there is a possibility that more power than necessary is emitted and the laser diode 2 is destroyed. .

  As a countermeasure against the above-described problem, a protection circuit as described in [Patent Document 2] has been considered. However, the laser diode 2 has individual variations, and the values of Ith and Iop, the inclination of characteristics, and the like are also included. It depends on each individual. For this reason, even if current limitation is applied, when laser diodes are replaced, power that causes destruction is output even within the limit value, or conversely up to the maximum rated value. However, there is a possibility that the necessary power is not output due to a limitation even though there is sufficient margin.

  The present invention has been made in view of the above circumstances, and in an optical disc apparatus provided with means for controlling laser power by an APC (Auto Power Control) system, even if there is a variation in the characteristics of the laser diode, the light emission power is converted into a laser. A laser power control device capable of sufficiently responding to a temperature change while keeping it within the maximum rating of the diode, and a laser power control program for causing the computer to function as a processing means for each part in this laser power control device The purpose is to provide.

The present invention relates to a light detection means (5) for detecting, as a current value, a light emission amount of a laser light source (2) in an optical disk apparatus that records / reproduces information on / from an optical disk (4) using laser light.
Current-voltage conversion means (6) for converting the detected current value into a voltage value;
Sample hold means (7) for holding the voltage value for a certain period;
AD conversion means (9) for converting the sampled and held voltage value into a digital value to obtain a laser power monitor value;
A comparison means (10) for comparing the laser power monitor value α with a preset laser power target value β to obtain a difference value δ;
Control data generating means (11) for generating control data Dapc using the difference value δ as error information;
DA conversion means (12) for converting the control data Dapc into a voltage value;
A laser power for converting the voltage value into a laser control current and a laser light source driving means (1) for driving the laser light source (2), and controlling a light emission amount of the laser light source (2). In the control device (18),
Memory means (23) for storing in advance at least one of a parameter for current-optical power characteristics of the laser light source (2) or a parameter for converting the voltage value into a laser control current;
Temperature acquisition means (21) for acquiring the temperature in the optical disc device;
Based on the data inputted from the memory means (23) and the temperature acquisition means (21), the allowable maximum input current value of the laser light source (2) (maximum rated value Iop-pls at the time of pulse light emission or at the time of continuous light emission). Limit value generating means (22) for generating a limit value L so as not to generate a laser control current value larger than the maximum operating current Iop-cw);
Maximum laser control data obtained by adding the control data Dapc and preset data (digital data Der for adding erase power, digital data Dpk for adding peak power) is input from the limit value generating means (22). Data limiting means (20) for controlling so as not to exceed the limit value L,
The above-mentioned problem is solved by providing a laser power control device 30 for an optical disc apparatus characterized by comprising:

In order to control the laser power in the laser power control device 30 of the optical disk device described above, a computer (25) is provided.
A comparison means (10) for comparing the laser power monitor value α with a preset laser power target value β to obtain a difference value δ;
Control data generating means (11) for generating control data Dapc using the difference value δ as error information;
Based on the data input from the memory means (23) and the temperature acquisition means (21), a laser control current value larger than the allowable maximum input current value (Iop-pls or Iop-cw) of the laser light source (2) is obtained. Limit value generating means (22) for generating limit value L so as not to be generated, and maximum laser control data obtained by adding the control data Dapc and preset data (Der, Dpk) are the limit value Data limiting means (20) for controlling so as not to exceed the limit value L inputted from the generating means (22),
The above problem is solved by providing a laser power control program for an optical disc apparatus for functioning as:

  In addition, the number in the said parenthesis respond | corresponds to the code | symbol which shows the member hung up as a specific example by this specification.

Since the present invention has the above configuration, the following effects can be obtained.
(1) In an optical disc apparatus that performs an APC operation, even when the characteristics of a laser light source change due to a sudden change in ambient temperature, a situation that exceeds the maximum rating of the laser and causes laser destruction is prevented in advance. Even when laser light sources having different characteristics are mounted, it is possible to provide a laser power control device that can protect an optimal laser light source without changing hardware.
(2) In the laser power control device, the computer compares the laser power monitor value with a preset laser power target value to obtain a difference value, and uses the difference value as error information to obtain control data. Control data generation means for generating, and a limit for generating a limit value that does not generate a laser control current value larger than the allowable maximum input current value of the laser light source based on data input from the memory means and temperature acquisition means Control is performed so that the maximum laser control data obtained by adding the value generation means, the control data for driving the laser light source, and fixed value data set in advance from the outside does not exceed the limit value input from the limit value generation means. A program suitable for functioning as data restricting means is provided.

  Embodiments of a laser power control apparatus and a laser power control program according to the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram of a laser power control mechanism of an optical disc apparatus including a laser power control apparatus according to the present invention. FIG. 2 is a diagram for explaining a laser power modulation method according to the present invention. FIG. 3 is a block diagram of a laser power control mechanism of an optical disc apparatus including a laser power control apparatus according to the present invention in which a microcomputer is placed at the center of laser power control. FIG. 4 is a flowchart showing an operation procedure of the laser power control apparatus according to the present invention in which a microcomputer is placed at the center of laser power control.

  Hereinafter, an example of an embodiment of a laser power control device and its control program in an optical disk device of the present invention will be described in detail with reference to the drawings.

(1) First Embodiment FIG. 1 shows a block circuit configuration example of a laser power control apparatus according to the present invention.

  As is apparent from a comparison between FIG. 1 and FIG. 5 showing a configuration example of the above-described known laser power control apparatus, this embodiment also performs APC control, and a basic block circuit configuration. Are common.

  That is, in the laser power control apparatus 30 of the present embodiment, the data limiting circuit 20 as the data limiting means surrounded by the broken line frame, the temperature sensor 21 as the temperature acquisition means, and the limit value generation as the limit value generation means. A circuit 22 and a memory 23 (RAM or the like) as a memory means are newly provided. Other circuit portions are the same as those of the laser power control device 18 in FIG.

  Accordingly, the description of the parts common to FIG. 5 is omitted here, and the data limiting circuit 20, the temperature sensor 21, and the limit value generating circuit 22, which are characteristic parts of the present embodiment, are exclusively used. The control operation by the memory 23 will be mainly described.

  The temperature sensor 21 measures the temperature inside the optical disk device (preferably in the vicinity of the laser diode 2 that is a laser light source) at regular time intervals, and outputs temperature data to the limit value generation circuit 22.

  In the memory 23, the threshold current Ith of the laser diode 2, the maximum operating current Iop-pls at the time of pulse emission, the maximum operating current Iop-cw at the time of continuous emission, and how much Ith and Iop when the temperature changes by 5 degrees In addition to the LD characteristic-related data such as whether to shift, the value of the V / I conversion resistance in the LD drive circuit 1, the high and low reference voltage values of the DA conversion circuit 12, and the like are stored. These data are referred to from the limit value generation circuit 22.

  The limit value generation circuit 22 is a limit value obtained by digitalizing the optical power level of the laser diode 2 at that time based on the various data stored in the memory 23 and the temperature data from the temperature sensor 21. L is calculated and output to the data limiting circuit 20.

  This limit value L is calculated from the following equation.

ここに、ＲはＬＤ駆動回路１のＶ／Ｉ変換抵抗値［Ω］、Ｉopはレーザダイオードの最大動作電流値［Ａ］（Ｉ連続又はパルス発光時）、ＧはＬＤ駆動回路１のゲイン、ＶＲＨはＤＡ変換回路１２のＨレベルリファレンス電圧［Ｖ］、ＶＲＬはＤＡ変換回路１２のＬレベルリファレンス電圧［Ｖ］、１０２３はＤＡ変換回路１２が１０ビットの場合のサンプリングである。

Here, R is the V / I conversion resistance value [Ω] of the LD drive circuit 1, Iop is the maximum operating current value [A] of the laser diode (I continuous or pulse emission), G is the gain of the LD drive circuit 1, VRH is the H level reference voltage [V] of the DA conversion circuit 12, VRL is the L level reference voltage [V] of the DA conversion circuit 12, and 1023 is sampling when the DA conversion circuit 12 is 10 bits.

  Next, a method for limiting output data in the data limiting circuit 20 will be described.

  2 and FIG. 7 show that the signals b and c pulsed by the strategy generation circuit 14 based on the modulation signal a output from the modulation circuit 13 at the time of data recording are converted into current values by the LD drive circuit 1, and the laser FIG. 2 illustrates a state in which the laser beam is converted by the diode 2. In FIG. 2, the bottom power control value Ibt, the erase power addition setting value Ier, and the peak power addition setting value Ipk are respectively represented by the DA conversion circuit. 12 is set by output voltage values Vbt, Ver, and Vpk after DA conversion of the digital data Dapc, Der, and Dpk input to 12 (these are collectively referred to as a control signal Cs ′).

  In the present embodiment, the feedback value based on the optical power monitor value α corresponds to Ibt. At this time, the optical power level to be monitored is preferably bottom power, but the bottom power in recording on a rewritable optical disc (DVD-RW, etc.) exists only for a very short period as can be seen from FIG. It is difficult to S / H. Therefore, the erase power level corresponding to a space having a relatively long width is used for feedback control as the optical power monitor value α (see S / H pulse e in FIG. 7). In the case of recording on a write-once optical disc (DVD-R, etc.), the power corresponding to the space portion is the bottom power level, so it is possible to perform S / H.

  Next, the erase power addition setting value Ier and the peak power addition setting value Ipk are values to be added to the bottom power control value Ibt to output the erase power and peak power necessary for recording, respectively. (The fixed value, corresponding to the digital data Der and Dpk expressed as the peak / erase power setting values in FIGS. 1, 3 and 5).

  In the timing chart of FIG. 7, when the erase power selection signal b is H with respect to the modulation signal a, power corresponding to the current value Gx (Vbt + Ver) / R is output. Similarly, when the peak power selection signal c is H, power corresponding to the current value Gx (Vbt + Vpk) / R is output.

  When recording data, the power by the current value Gx (Vbt + Vpk) / R is the highest power, and it is necessary to control so that this current value does not exceed the maximum rated value Iop-pls at the time of pulse emission. Therefore, the data limiting circuit 20 limits Dapc or Dpk so that L> (Dapc + Dpk). When limiting Dpk, it is necessary to simultaneously limit the value of Der so that the ratio ε between the peak power and the erase power maintains a predetermined value.

  As described above, since the limit value L is given as an appropriate value according to the ambient temperature, the control signal after the control data (Dapc + Dpk) limited by the data limiting circuit 20 is converted to a voltage value by the DA conversion means 12. The LD driving circuit 1 that inputs Cs ′ and converts it into a laser control current to drive the laser diode 2 causes the laser diode 2 as a laser light source to emit excessive light even under different environments, thereby causing destruction. Can be prevented.

  In the case of not the data recording mode, for example, in the erasing mode, pulse light emission is not performed, so the maximum rated current value is the maximum rated value Iop-cw during continuous light emission, and the same control is performed so as not to exceed this value. I do.

  Of course, the same restriction process can be performed during playback without high power output.

(2) Second Embodiment In the first embodiment (block configuration in FIG. 1), the laser power control provided with a laser light source protection function with a hardware configuration composed of individual circuit blocks is performed. In this embodiment, the main control is replaced with a microcomputer (hereinafter also referred to as a microcomputer), and control is executed by software. FIG. 3 shows the configuration.

  As apparent from a comparison between FIG. 3 and FIG. 1, the laser power control device 40 of the present embodiment includes the comparison circuit 10, the compensation circuit 11, the data limit circuit 20, and the limit value generation circuit 22 in FIG. 1. Is constituted by the microcomputer 25, but the other circuit portions are the same as those in FIG.

  Here, the microcomputer 25 has a general circuit configuration including a CPU 26, a ROM 27, a RAM 28, and an I / O port 29, and the operation procedure of the functions performed by the circuits 10, 11, 20, and 21 in FIG. Is stored in the ROM 27.

  Then, when the CPU 26 executes the program, the same control as the laser power control device 30 of the first embodiment is performed.

  Hereinafter, the laser power control procedure by the laser power control apparatus 40 of the present embodiment will be described with reference to the flowchart of FIG.

  First, the LD characteristic related data, the VI conversion resistance value, the VRH, VRL, power setting parameter, etc. of the DA conversion circuit 12 stored in the external memory 23 are read and stored in the RAM 28 (step S1).

  Next, an APC target value, an erase power setting value, and a peak power setting value are calculated from the power setting parameters unique to the optical disc apparatus 40, and stored in the RAM 28 (step S2).

  Subsequently, the limit value L is calculated from the LD characteristic related data, the VI conversion resistance value, the VRH and VRL of the DA conversion circuit 12 read in advance, and stored in the RAM 28. The calculation method of the limit value L is the same as that of the first embodiment (step S3).

  When the parameter setting and storage are completed, the laser die auto 2 is turned on, and the APC is turned on immediately thereafter. At this time, in order to prevent laser destruction due to overcurrent, the laser diode 2 is normally set to ON in the reproduction mode (step S4).

  Next, in step S5, the end process is confirmed. That is, when an end command is received from the host computer of the optical disk apparatus, the process proceeds to step S11, and the process ends after APC is turned OFF and the laser diode 2 is turned OFF. If the end command does not come, the process proceeds to step S6 and enters a recording start waiting state. If the recording mode is set, the process proceeds to step S7. If the recording mode remains, the process returns to step S5, and S5 to S6 are repeated.

  In the next step S7, the limit of digital data Dapc, Der, Dpk output to the DA converter circuit 12 is confirmed. It is determined whether or not limit value L> (Dapc + Dpk). If YES, the process proceeds to step S8, and the digital data Dapc, Der, and Dpk are output to the DA converter circuit 12 without limiting the limit value. In the case of NO, the process proceeds to step S12, and by limiting the Dapc or Dpk, the limit process (the control signal Cs ′ composed of the DA conversion circuit 12 (the control signal Cs ′ composed of Dapc, Der, Dpk)) becomes a voltage value corresponding to the limit value L. The digital data Dapc, Der, and Dpk are output to the DA converter circuit 12 after the input is limited to be fixed. In the case of limiting Dpk, the value of Der is also simultaneously limited so that the ratio of peak power and erase power is kept at a predetermined value, as in the first embodiment.

  In the next step S9, a recording end wait state is entered. If the recording is not finished, the process returns to step S7 and the limit process is repeated. When the recording is finished, the process proceeds to step S10 to set the reproduction mode, and then returns to step S5.

  Thereafter, the processes in steps S5 to S10 are repeated until an end command is received, and the laser power control device 40 of the second embodiment is the same as the laser power control device 30 of the first embodiment. Functions and effects can be obtained. These processes can be performed in the same manner in the erase mode and the reproduction mode as in the first embodiment.

  As described above, in the laser power control device and the laser power control program of the present invention, the parameters of the current-optical power characteristics of the laser light source used and the voltage values for the control by the APC method of the light emission power of the laser light source. Based on the parameter for converting the laser current to the laser control current and the temperature change in the optical disc apparatus, the emission power of the laser light source does not exceed the maximum rated value Iop-pls at the time of pulse emission in the current state or continuously Fine power control is performed to limit the maximum operating current Iop-cw at the time of light emission so that the laser light source emits excessive light due to a sudden change in the ambient temperature, etc., leading to a decrease in life or laser destruction. To prevent that.

  Thus, the optimum laser light source power control that cannot be achieved by conventional feedback control by simple light emission power monitoring or APC ON / OFF control by temperature change monitoring is realized.

It is a block block diagram of the laser power control mechanism of the optical disk apparatus containing the laser power control apparatus which concerns on this invention. It is a figure for demonstrating the modulation method of the laser power which concerns on this invention. 1 is a block configuration diagram of a laser power control mechanism of an optical disc apparatus including a laser power control apparatus according to the present invention in which a microcomputer is placed at the center of laser power control. It is a flowchart which shows the operation | movement procedure of the laser power control apparatus which concerns on this invention which installed the microcomputer in the center of laser power control. It is a block block diagram of the laser power control apparatus in the optical disk apparatus of a well-known technique. It is a figure which shows the light emission power of a laser diode, the characteristic of an electric current value, and a temperature characteristic. It is a signal timing chart for demonstrating the operation state of a laser power control apparatus.

Explanation of symbols

1 Laser diode (LD) drive circuit 2 Laser diode (LD)
3 Beam splitter 4 Optical disk 5 Photodiode (PD)
6 Current-voltage conversion circuit (IV conversion circuit)
7 Sample hold circuit (S / H circuit)
8 Low-pass filter (LPF)
9 AD conversion circuit 10 Comparison circuit 11 Compensation circuit 12 DA conversion circuit 13 Modulation circuit 14 Strategy generation circuit 18, 30, 40 Laser power control device 20 Data limit circuit 21 Temperature sensor 22 Limit value generation circuit 23 Memory (external memory)
25 Microcomputer 26 CPU
27 ROM
28 RAM
29 I / O port α Optical power monitor value β Power target value δ Difference value Dapc, Der, Dpk Control data (digital data)
Control signal Ith Laser diode threshold current Iop-pls Maximum operating current during pulse emission Iop-cw Maximum operating current during continuous emission L Limit value

Claims (2)

A light detecting means for detecting, as a current value, a light emission amount of a laser light source in an optical disk apparatus for recording / reproducing information on / from an optical disk using laser light;
Current-voltage conversion means for converting the detected current value into a voltage value;
Sample hold means for holding the voltage value for a certain period;
AD conversion means for converting a sampled and held voltage value into a digital value to obtain a laser power monitor value;
Comparing means for comparing the laser power monitor value with a preset laser power target value to obtain the difference value;
Control data generating means for generating control data using the difference value as error information;
DA conversion means for converting the control data into a voltage value;
A laser power control device that converts the voltage value into a laser control current and includes a feedback loop having a laser light source driving unit that drives the laser light source, and controls the light emission amount of the laser light source;
Memory means for storing in advance at least one of a parameter for current-optical power characteristics of the laser light source or a parameter for converting the voltage value into a laser control current;
Temperature acquisition means for acquiring the temperature in the optical disc device;
Limit value generation means for generating a limit value based on data input from the memory means and temperature acquisition means so as not to generate a laser control current value larger than the allowable maximum input current value of the laser light source;
Data limiting means for controlling the maximum laser control data obtained by adding the control data and preset data so as not to exceed the limit value input from the limit value generating means;
A laser power control apparatus for an optical disc apparatus, comprising: A computer for controlling laser power in the laser power control device for an optical disk device according to claim 1,
A comparison means for comparing the laser power monitor value with a preset laser power target value to obtain a difference value;
Control data generating means for generating control data using the difference value as error information;
Limit value generation means for generating a limit value based on data input from the memory means and temperature acquisition means so as not to generate a laser control current value larger than an allowable maximum input current value of the laser light source, and Data limiting means for controlling the maximum laser control data obtained by adding the control data and preset data so as not to exceed the limit value input from the limit value generating means,
A laser power control program for an optical disc apparatus for causing the function to function as

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