TWI393134B - Method for calculating an initial driving signal and automatic power control system and method - Google Patents

Description

Automatic power control system and method and method for calculating initial drive signal

This invention relates to optical disk drives, and more particularly to automatic power control systems for optical disk drives.

The optical disc drive uses a read head to project a laser light onto a data layer of a disc to write data to or read data from the data layer. When the high-power laser light is read from the hair, the laser light melts the data layer of the optical disk or changes the phase of the data layer to depict the data pattern thereon, thereby completing the burning of the data on the optical disk. When reading low-power laser light from a hair, low-power laser light cannot melt the data layer of the disc or change the phase of the data layer. At this time, the read head decodes the data pattern according to the pattern of the laser light reflected from the disc to read the data from the optical disc. The read head of the disc must therefore be able to produce laser light with different power values under different application functions.

The read head produces laser light with a laser diode. The laser light power generated by the laser diode is controlled by a drive current. When the read head continues to produce laser light, heat is generated to cause the temperature of the read head to rise. As the temperature of the read head increases, the drive current must also rise to control the laser diode to emit laser light having a fixed power value. Figure 1 shows the relationship between laser power and drive current. When the temperature of the read head is T ₁ , the relationship between the laser light power and the drive current is L ₀ . When the temperature of the read head is T ₂ , the relationship between the laser light power and the drive current is L ₁ or L ₂ . The relationship lines L ₀ and L ₁ have different current compensation values Ith(T ₁ ) and Ith(T ₂ ), while the relationship lines L ₁ and L ₂ have different slopes.

In order to avoid the power reduction of the laser light when the temperature of the read head rises, the optical disk drive must include an automatic power control mechanism to adjust the driving current of the laser diode according to the temperature in order to maintain the laser power constant. Figure 2 is a schematic diagram of signals generated by conventional automatic power control mechanisms. The conventional automatic power control mechanism is a closed loop control system. When the read head writes data to the optical disc drive at a laser power, the read head generates a drive current to operate the laser diode to generate a laser light, and a front end detection diode detects the power of the reflected laser light. To generate a front end detection diode output signal. The front-end detection diode output signal is then sampled as a reference for calculating the drive current of the laser diode. In the second, the laser light generated by the laser diode includes a plurality of powers such as cooling power, erasing power, writing power, and overdrive (OD) power to write data to the optical disc. For example, the erase power and write power of the front-end detection diode output signal are sampled as a reference for calculating the drive current of the laser diode.

When the optical disk drive is a Blu-ray disc player, the data density is high. Therefore, the power value of the laser light used to write the data to the Blu-ray disc continues for a short period of time and the burning speed becomes faster. Figure 3 is a schematic diagram of the signals generated by the automatic power control mechanism corresponding to the Blu-ray disc. The Blu-ray disc includes at least two different areas, such as a data area and an automatic power control area. The automatic power control zone is used for automatic power control, while the data zone is for general data writing. When the read head writes data (such as the None-return-to-zero (NRZ) signal) to the Blu-ray disc at a high burn rate, the power of the laser light is maintained for a short period of time. Since the front-end detection diode takes a period of time to generate a stable output signal, the output signal of the front-end detection diode cannot converge in a short time for each power, and thus cannot be used as a basis for automatic power control. Therefore, Blu-ray discs include an automatic power control area to solve this problem, but the disc player may not have enough time at the beginning of data writing to achieve stable write power. Therefore, there is a need for an automatic power control method for use with an optical disk drive.

In view of the above, it is an object of the present invention to provide a method of calculating an initial drive signal to solve the problems of the prior art. In one embodiment, the initial drive signal drives a read head of a disc drive for reading data from a disc or writing data to the optical disc, the optical disc including a plurality of automatic power control regions And a plurality of data areas, the automatic power control areas and the data areas are spaced apart from each other. First, in the automatic control regions, the read head is driven by a start drive signal to emit a laser light. Then, one of the detected light intensity of the laser light is obtained. Then, a modified start driving signal is obtained according to the detected intensity and a target intensity.

The invention further provides an automatic power control system for an optical disk drive. In one embodiment, the optical disk drive has a read head having a front end detecting diode for reading data from a optical disk or writing data to the optical disk. The system includes a plurality of automatic power control regions and a plurality of data regions, and the automatic power control system includes a power initial value setting module and a compensator. The power initial value setting module drives the read head to emit a laser light by using an initial driving signal in the automatic control areas. The compensator obtains a detection intensity of the laser light by the front end detecting diode, and calculates a modified initial driving signal according to the detection intensity and a target intensity.

The present invention further provides an automatic power control system for an optical disk drive to control the power of a laser beam. In one embodiment, the optical disc drive includes a read head and a front end detection diode, the read head receives a driving signal to generate the laser light, and the front end detecting diode detects the laser light. An analog input signal is generated. The automatic power control system includes an analog to digital converter, a compensator, a controller, and a digital to analog converter. The analog to digital converter converts the analog input signal into a digital data. The compensator generates at least one driving component data according to the digital data and a target value when a compensation driving signal is enabled. The controller is enabled to compensate for the drive signal. The digital-to-analog converter converts the drive component data into one analog type to drive the constituent signal.

The present invention provides a method of automatic power control for an optical disk drive to control the power of a laser beam. In one embodiment, the optical disc drive includes a read head and a front end detection diode, the read head receives a driving signal to generate the laser light, and the front end detecting diode detects the laser light. Generate an analog input signal. First, enable a compensation drive signal. When a digital drive signal is enabled, the analog input signal is converted to a digital data. When the compensation driving signal is enabled, at least one driving component data is generated according to the digital data and a target value. Then, the driving component data is converted into one analog type driving component signal.

The above and other objects, features, and advantages of the present invention will become more apparent and understood.

The automatic power control system controls the power of the laser light emitted by the read head of the optical disk drive. 4 is a block diagram of a disk drive 400 including an automatic power control system 406 in accordance with the present invention. In one embodiment, the optical disk drive 400 includes a front end detection diode 410, an automatic power control system 406, a laser diode driver 416, and a laser diode 418. The laser diode driver 416 generates a driving current I according to the plurality of driving composition signals I1 to I4 and the plurality of driving enable signals OE1 to OE4. The power of the laser light will decrease with various operating conditions, such as a rise in temperature or an increase in the speed of the disc. The automatic power control system 406 thus performs an automatic power control procedure to adjust the drive current I of the laser diode 418 as a function of various operating conditions in order to maintain the power of the laser light emitted by the laser diode 418 stable.

The front end detection diode 410 first samples the laser diode output power to obtain an analog input signal R. The automatic power control system 406 then adjusts the drive composition signals I1~I4 based on the analog input signal R. In one embodiment, the automatic power control system 406 includes a write pulse generator 402, a sample pulse generator 404, a controller 430, two sample hold circuits 412a and 412b, two low pass filters 411a and 411b, analog to A digital converter 413, a compensator 414, and a digital to analog converter 415. In one embodiment, although the laser diode 418 emits laser light having a plurality of power values, the automatic power control system 406 uses only two of the power values to control all of the power values. In an embodiment, the two powers are write power and erase power. Figure 5 is a flow diagram of a method 900 of performing automatic power control in accordance with the present invention. First, the sample and hold modules 412a and 412b sample an analog input signal R according to the sample pulse signals SH1 and SH2, respectively, to obtain two analog input signals Sa1 and Sb1 corresponding to the write power and the erase power, respectively (step 902). The sample pulse generator 404 generates sample pulse signals SH1 and SH2 to indicate which segment of the analog input signal R corresponds to the write power and the erase power. The low pass filters 411a and 411b then filter the analog input signals Sa1 and Sb1 to obtain signals Sa2 and Sb2.

When the low pass filters 411a and 411b start generating the signals Sa2 and Sb2, the filtered signals Sa2 and Sb2 are not stable. Therefore, the controller 430 determines the timing at which the digitalized drive signal AD_trig and the compensated drive signal Ctrl_trig are enabled (step 904). In one embodiment, when the filtered signals Sa2 and Sb2 are stable, the controller 430 enables the digitized drive signal AD_trig. In an embodiment, the controller 430 generates the digitized driving signal AD_trig and the compensation driving signal Ctrl_trig according to the signal APC_area. The surface of the optical disk read or written by the optical disk drive 400 is divided into an automatic power control area (APC area) and a data area, wherein the automatic power control area and the data area are spaced apart from each other. The data area is used to store general data, while the automatic power control area is used for automatic power control. The signal APC_area is used to indicate whether the laser light of the optical disc is projected to the automatic power control area of the optical disc.

When the digitized drive signal AD_trig is enabled, the analog to digital converter 413 converts the filtered analog input signals Sa2 and Sb2 into digital data Sa3 and Sb3 (step 906). Similarly, when the analog to digital converter 413 is just beginning to generate the digital data Sa3 and Sb3, the digital data Sa3 and Sb3 are not stable. Therefore, when the digital data Sa3 and Sb3 are stable, the controller 430 enables compensation of the drive signal Ctrl_trig. When the compensation drive signal Ctrl_trig is enabled, the compensator 414 generates drive composition signals d1, d2, d3, d4 based on the digital data Sa3 and Sb3 and a target value (step 908). In one embodiment, the compensator 414 compares the digital data Sa3 obtained by the write power detection with a target write power value to generate a power intensity difference, and adjusts the power intensity difference to drive the laser diode. The drive of the laser light that emits the write power constitutes a signal d3. Since each power value is proportional, the other modified driving component signals d1, d2, and d4 can be calculated according to the power intensity difference.

The digit to analog converter 415 then converts the drive constituent signals d1, d2, d3, d4 from digital to analog to obtain the drive constituent signals I1, I2, I3, I4 (step 910). Next, the laser diode driver 416 generates a driving current I according to the driving composition signals I1, I2, I3, and I4 and the driver enable signals OE1 to OE4 (step 912). The write pulse generator 402 generates driver enable signals OE1, OE2, OE3, OE4 corresponding to the drive composition signals I1, I2, I3, I4, respectively. Whenever one of the driver enable signals OE1, OE2, OE3, OE4 is enabled, the laser diode driver 416 applies one of the corresponding drive component signals I1, I2, I3, I4 to the drive current. I. Finally, the laser diode 418 generates laser light having a power determined by the drive current I to complete the automatic power control procedure. Therefore, even if the temperature of the laser diode 418 changes, the laser diode 418 can still produce laser light having an accurate power P when the automatic power control program is performed. Thereafter, the optical disk drive 400 continues the data writing.

Figure 6 is a schematic diagram showing the sampling process of the analog input signal generated by the front end detecting diode according to the present invention. When the automatic power control program is performed, the laser diode 418 projects a laser light to an automatic power control region in accordance with the control WSR of the write pulse generator 402. The power of the laser light is converted between the two power values I1, I2. In one embodiment, the laser light is maintained at each of the power values I1, I2 for a period of 20T to stabilize the output produced by the front end detection diode. The front end detection diode 410 requires time T1 to detect a stable signal of the power value I2, and time T2 is required to detect the stable signal of the power value I1. When the analog input signal is stable, the sample pulse generator 404 generates sample pulses SH1 and SH2 to drive the sample and hold circuits 412a and 412b to sample analog input signals to obtain analog input signals Sa1 and Sb1.

Figure 7 is a schematic illustration of the operation of analog to digital converter 413 and compensator 414 in accordance with the present invention. The automatic power control system 400 performs an automatic power control procedure when the laser diode 418 is located on the dynamic power control region of the optical disc. When the current detecting diode 410 generates an analog input signal, the sampling pulse generator 404 generates a sampling pulse signal SH1 indicating a paragraph of the analog input signal corresponding to the first power value, and the sample and hold circuit 412a is based on the sampling pulse wave. Signal SH1 samples the analog input signal to obtain an analog input signal Sa1. When the analog input signal Sa1 is stable, the controller 430 enables the digitized drive signal AD_trig, and the analog-to-digital converter 413 starts converting the analog input signal Sa1 to the digital data Sa3. When the digital data Sa3 is stabilized, the controller 430 enables compensation of the drive signal Ctrl_trig, and the compensator 414 starts to adjust the drive composition current I1 according to the digital data Sa3.

The digitized drive signal AD_trig has a delay time D1 compared to the ADC_area signal indicating whether the laser light is incident on the automatic power control zone. The compensation drive signal has a delay time D2 compared to the digitized drive signal AD_trig. In one embodiment, the delay times D1 and D2 are zero. In addition, the automatic power control system 400 can operate normally even if the digitalized drive signal AD_trig is not generated. In one embodiment, the controller 430 only generates the compensation drive signal Ctrl_trig to drive the compensation action of the compensator 414, and the analog-to-digital converter 413 does not directly convert the analog signals Sa2 and Sb2 according to the indication of the digitized drive signal AD_trig. Sa3 and Sb3.

Figure 8 is a flow diagram of a method 500 of operation of the compensator 414 in accordance with the present invention. When the sample and hold circuits 412a and 412b sample the data Sa1 and Sb1, the analog to digital converter 413 generates the digital data Sa3 and Sb3 according to the data Sa1 and Sb1 (step 502), and the compensator 414 adjusts the driving composition current according to the digital data Sa3 and Sb3. Signals I1~I4 (step 504). Otherwise, when the sample and hold circuits 412a and 412b do not sample the data Sa1 and Sb1, the analog to digital converter 413 does not generate the digital data Sa3 and Sb3 (step 502), and the compensator 414 does not adjust the drive composition current signals I1 to I4 (steps) 506). In another embodiment, the analog to digital converter 413 can directly sample the analog input signal without operating in accordance with the actions of the sample and hold circuits 412a and 412b, and the compensator 414 is controlled by the control signal Ctrl_trig to calculate the drive composition currents I1 to I4.

The aforementioned automatic power control program is performed when the laser light emitted from the laser diode 418 is projected on an automatic power control area (APC area). Therefore, the aforementioned automatic power control program is referred to as an APC area automatic power control mode. However, the conventional automatic power control program is performed when data is written on the re-data area, and is therefore referred to as a general automatic power control mode. The general automatic power control mode may cause an error when the data burning speed of the automatic power control system 400 is too high. Accordingly, the present invention provides a method of switching between an APC area automatic power control mode and a general automatic power control mode. Figure 9 is a flow diagram of a method 600 for switching between an APC area automatic power control mode and a general automatic power control mode in accordance with the present invention. When the data burning speed of the automatic power control system 400 exceeds a threshold value (step 602), the APC area automatic power control mode is employed (step 602). When the data burn-in speed of the automatic power control system 400 is below a threshold (step 602), a general automatic power control mode is employed (step 606).

Figure 10 is a block diagram of an optical disk drive 700 incorporating an automatic power control system 706 in accordance with the present invention. The optical disk drive 700 of FIG. 10 is similar to the automatic power control system 400 of FIG. 4 except for the digitizing module 713, the compensator 714, and the controller 730. In one embodiment, the digitization module 713 includes an analog to digital converter 722 and filters 724, 725. The analog to digital converter 722 converts the analog input signals Sa2 and Sa3 into digital data Sa3 and Sb3. When the analog to digital converter 722 has just started generating the digital data Sa3 and Sb3, the digital data Sa3 and Sb3 are unstable. Therefore, when the digital data Sa3 and Sb3 are stable, the controller 730 enables the drive signal F_trig_a and F_trig_b to be filtered, and the filters 724 and 725 then start filtering the digital data Sa3 and Sb3 to obtain the filtered digital data Sa4 and Sb4.

The filtered digital data Sa4 and Sb4 are then sent to a compensator 714. In one embodiment, the compensator 714 includes two subtractors 726 and 727, and a compensation filter 728. The subtracters 726 and 727 subtract the filtered digit data Sa4 and Sb4 from the two target values Sa* and Sb*, respectively, to obtain power intensity differences Sa5 and Sb5. The compensation filter 728 then filters the power intensity differences Sa5 and Sb5 to obtain the drive composition signals d1, d2, d3, d4. When the subtractors 726 and 727 start generating the power intensity difference signals Sa5 and Sb5, the power intensity difference signals Sa5 and Sb5 are unstable. After the power intensity difference signals Sa5 and Sb5 are stabilized, the controller 730 enables compensation of the drive signal Ctrl_trig to drive the compensation filter 728 for filtering, thereby generating drive component signals d1, d2, d3, d4. In addition, the automatic power control system 700 can operate only in accordance with the compensation drive signal Ctrl_trig without the filter drive signals F_trig_a and F_trig_b. In one embodiment, the controller 730 only generates the compensation drive signal Ctrl_trig to drive the compensation filter 728 for filtering, and the filters 724 and 725 directly filter the digital data Sa3 and Sb3 to obtain the filtered digital data Sa4 and Sb4. In one embodiment, the compensation filter 728 is an integrator. When the compensation drive signal Ctrl_trig is disabled, the compensation filter 728 does not integrate the signals Sa5 and Sb5, and the drive composition signals d1, d2, d3, d4 are maintained at the original size.

Figure 11 is a schematic illustration of signals of an embodiment of an automatic power control routine in accordance with the present invention. When the read head is above the data area, the write pulse generator 402 generates drive enable signals OE1 OE OE4 to control the laser diode driver 416 to generate the drive current I, and the power of the laser light is shown in FIG. Upper half. When the read head writes general data into the data area, the drive current changes rapidly, and it is difficult for the automatic power control system to have a stable detection signal size for calculating the correction drive signal. When the read head is on the automatic power control region, the write pulse generator 402 generates drive enable signals OE1 OE OE4 to control the laser diode 416 to generate the drive current I. Furthermore, the enabling sections of the drive enable signals OE1 OE OE4 can be extended. For example, the durations t3 and t4 of the two power values are extended compared to the durations t1 and t2. The front end detection diode 410 can thus generate a stable analog input signal R, and the sample and hold circuits 412a and 412b can sample the analog input signal R to obtain reliable data Sa1 and Sb1 for compensation.

Figure 12 is a block diagram of an optical disk drive 100 including an automatic power control system 106 in accordance with the present invention. In one embodiment, the optical disc drive 100 includes an automatic power control system 106, a laser diode driver 116, a laser diode 118, and a front end detection diode 110. In one embodiment, the automatic power control system 106 includes a controller 101, a write pulse generator 102, a sample pulse generator 104, a sample and hold circuit 112, a compensator 114, and a power initial value setting module 120. The laser diode driver 116 generates a driving current I according to the plurality of driving composition signals d1 and the driving enable signal OEi. The laser diode 118 then emits laser light at a power P determined by the drive current. In one embodiment, the power initial value setting module 120 is configured to set an initial current value of each of the driving component signals I1, I2, I3, and I4 at the start of the programming. Therefore, the CD player needs to determine the initial drive current.

Figure 13 is a flow chart of an automatic power control method 800 for an optical disk drive in accordance with the present invention. The surface of the optical disc is assumed to be distinguished as an automatic power control area and a data area, and the automatic power control area and the data area are spaced apart from each other. The data area is used to store general data, while the automatic power control area is used for automatic power control. In one embodiment, the optical disc is a Blu-ray disc, and the optical disc drive utilizes an automatic power control region to determine the initial drive current for data burning. First, the controller 101 determines whether the laser diode 118 projects a laser beam into the automatic power control region of the optical disk (step 802). When the laser light is projected onto the automatic power control area of the optical disc, the controller 101 instructs the write pulse generator 102 to generate a drive enable signal OEi corresponding to the test data. Otherwise, the controller 102 instructs the write pulse generator 102 to generate a drive enable signal OEi corresponding to the general data.

When the laser light is projected onto the automatic power control area of the optical disc, the automatic power control system 106 begins the initial drive signal calculation routine to set the initial drive signal for the laser light to be emitted by the read head of the drive. When the laser light is projected on the automatic power control area of the optical disc, the power initial value setting module 120 generates an initial driving composition signal for the laser diode driver 114 to drive the laser diode 118 to emit the laser light with the power P. (Step 804). The laser diode 118 then projects at least one laser light of the power value P in accordance with the drive current I in the automatic power control region. In an embodiment, the at least one power value P includes read power, cooling power, erase power, and excessive drive power.

The front end detection diode 110 then detects the magnitude of the reflected light of the laser to obtain a detection signal R corresponding to at least one power value P (step 806). When the detection signal R is substantially stable, the sampling pulse generator 104 generates a sampling pulse signal SH. The sample and hold circuit 112 then samples the size of the detection signal R according to the sample pulse signal SH to obtain a plurality of detection signal sizes pi corresponding to the equal power values P, respectively. Because the detection signal size pi is proportional to the power value P, the compensator 114 then calculates a modified initial drive signal di based on the detected signal size pi and a target value. In one embodiment, the compensator 114 compares the detected signal size pi with the target value to generate a power intensity difference, and adjusts the initial driving signal according to the power intensity difference to obtain the modified initial driving signal di. The modified initial drive signal di is stored in the power initial value setting module 120 for general data writing or next initial driving signal calculation. In one embodiment, the initial drive signal stored in the power initial value setting module 120 is updated in each initial drive signal calculation program. In another embodiment, the initial drive signal stored in the power initialized module 120 is adjusted until the initial drive signal calculation program produces a stable result.

In an embodiment, the calculation of the initial drive signal di includes the following steps. First, the compensator 114 compares the detected signal strength pi with the target value to generate a power intensity difference (step 808). Next, the compensator 114 adjusts the initial drive signal according to the power intensity difference to obtain an intermediate start drive signal di (step 810). When the laser diode P generates a laser power P corresponding to the intermediate initial driving signal di, the front-end detecting diode 110 detects a detecting signal R, and the sample-and-hold circuit 112 then samples the detected signal R to obtain The intermediate initial drive signal strength pi (step 812). In one embodiment, after at least two detected signal strengths are obtained, the compensator 114 implements an interpolation algorithm to obtain the modified drive signal di. The automatic power control system 106 then determines whether the power intensity difference between the detected intensity and the target intensity is within a predetermined range (step 814). When the power intensity difference is not within the predetermined range, the automatic power control system 106 recursively proceeds to steps 808, 810, 812 until the power intensity difference is within a predetermined range to stabilize the laser power.

Figure 14 is a block diagram of a laser diode driver 200 in accordance with the present invention. The laser diode driver 200 includes a plurality of current amplifiers 202, 204, 206, 208, 210 and an adder 212. Each current amplifier corresponds to a particular power value. For example, current amplifiers 202, 204, 206, 208, 210 correspond to read power, cooling power, erase power, write power, and overdrive power, respectively. The compensator 114 generates drive composition signals d0, d1, d2, d3, d4 corresponding to different power values, respectively. When the drive enable signal OE0 corresponding to the read power is enabled, the current amplifier 202 amplifies the drive composition signal d0 corresponding to the read power to obtain the drive composition current i0 corresponding to the obtained power. Current amplifiers 204, 206, 208, 210 operate in the same manner as current amplifier 202. Next, the adder 212 adds the drive component currents i0, i1, i2, i3, i4 to obtain a drive current I. The laser diode 214 then produces laser light having a power P corresponding to the drive current I. For convenience of explanation, the embodiments of FIGS. 17-20 include only the number of power values less than FIG.

Figure 15 is a diagram showing the relationship between the power value P of the laser light and the drive enable signals OE0 to OE4 in accordance with the present invention. It is assumed that the power of the laser light sequentially emits the read power P0, the overdrive power P4, the write power P3, the overdrive power P4, the cooling power P1, and the erase power P2. The read power P0 needs to be equal to the drive current of the drive composition current i0, so the drive enable signal OE0 is first enabled for generating laser light having the read power P0. The overdrive power P4 needs to be equal to the drive current of the drive composition currents i1, i2, i3, i4, so the drive enable signals OE1, OE2, OE3, OE4 are then enabled for generating laser light with excessive drive power P4. . The write power P3 needs to be equal to the drive current of the drive composition currents i1, i2, i3, so the drive enable signals OE1, OE2, OE3 are then enabled for generating laser light with write power P3. The cooling power P1 needs to be equal to the driving current that drives the constituent current i1, so the driving enable signal OE1 is then enabled for generating laser light having the cooling power P1. Finally, the deletion of the power P2 requires a drive current equal to the sum of the drive composition currents i1, i2, so that the drive enable signals OE1, OE2 are then enabled for generating laser light with the cancellation power P2.

Figure 16 is a block diagram of a compensator 300 in accordance with the present invention. The compensator 300 includes a subtractor 302 and a compensation filter 304. In one embodiment, the compensation filter 304 is an integrator. The subtracter 302 subtracts a detected signal strength pi generated by the sample and hold circuit 112 from a target power value Pi to obtain a power intensity difference. The compensation filter 304 then integrates the power intensity difference to obtain a drive composition signal di. The detected signal strength pi, the target power value Pi, and the drive composition signal di correspond to cooling power, erasing power, writing power, or excessive driving power. Since the closed loop of the automatic power control system has a bandwidth limitation, it takes some transition time to stabilize the power of the laser light. When the initial value of the drive component signal di is set correctly, the transition time can be reduced to zero. However, the initial value of the driving component signal di is determined not only by the detected signal strength pi, the target power value Pi, but also by the temperature of the laser diode. Therefore, a method of determining the initial value is needed. The power initial value setting module 120 thus generates an initial value to be delivered to the compensator 114, and the compensation filter 304 can begin to output the driving composition signal di according to the initial value. The subsequent laser diode driver 116 then generates a drive current I in accordance with the drive composition signal di to control the laser light power P of the laser diode 118.

Figure 17 is a diagram showing the test power of the laser light emitted by the laser diode 116 in accordance with the present invention. When the automatic power control system 106 begins the automatic power control routine, the optical drive moves the laser diode 118 over the automatic power control area of the optical disc. The laser diode 118 then sequentially emits laser light having powers P4, P3, P2, P1 in the automatic power control region. The first power value is the overdrive power P4, which lasts for Tp4. The second power value is the write power P3, which lasts for Tp3. The third power value is the erasing power P2, which lasts for Tp2. The fourth power value is the cooling power P1, which lasts for Tp1. The front-end detection diode 110 then detects the reflected light of the laser light to obtain a detection intensity, wherein the times Tp1, Tp2, Tp3, and Tp4 are longer than the time for which the detection intensity is stable. Therefore, the compensator 114 can generate a corresponding driving composition signal according to the detected intensity. The sample and hold circuit 112 obtains the detected intensity values p1, p2, p3, and p4 corresponding to the power values P1, P2, P3, and P4 according to the sampled pulse wave detection intensity, and the compensator 114 is based on the detected intensity values p1 and p2. , p3, p4 generate drive component signals d0, d1, d2, d3, d4 to generate the drive current I of the laser diode driver 116, thereby causing the laser diode 118 to generate a laser light.

Figure 18 is a schematic illustration of another embodiment of the test power of the laser light emitted by the laser diode 116 in accordance with the present invention. In one embodiment, the laser diode 118 sequentially emits laser light having power P2, P3, P1 in the automatic power control region. The first power value is the erasing power P2, which lasts for Tp2. The second power value is the write power P3, which lasts for Tp3. The third power value is the cooling power P1, which lasts for Tp1. The front end detection diode 110 then detects the reflected light of the laser light to obtain a detection intensity. The sample and hold circuit 112 obtains the detected intensity values p2, p3, and p1 corresponding to the power values P2, P3, and P1 according to the sampling pulse wave detection intensity, and the compensator 114 generates the driving according to the detected intensity values p2, p3, and p1. The signals d0, d1, d2, d3, d4 are composed to generate a drive current I of the laser diode driver 116, thereby causing the laser diode 118 to generate a laser beam.

In the embodiment of Figures 17, 18, the optical disk drive 100 produces laser light of three or four power values for power calculation. The sample and hold circuit 112 then samples four or three detected signal strengths corresponding to the power values. However, the compensator 114 must generate five kinds of drive composition signals d0, d1, d2, d3, d4 based on only four or three detected signal intensities. Referring to Figure 1, the relationship between the drive current and the laser power at a particular temperature T is determined by the slope s(T) and the differential current Ith(T). Therefore, the automatic power control system 106 can determine the slope s(T) and the differential current Ith(T) according to the detected signal strength sampled by the sample and hold circuit 112, and estimate the corresponding one according to the slope s(T) and the differential current Ith(T). All five drives of a particular power value make up the signal magnitudes d0, d1, d2, d3, d4. In an embodiment, the formulas for estimating the driving composition signal magnitudes d0, d1, d2, d3, and d4 according to the slope s(T) and the differential current Ith(T) are as follows:

P0=(i0-Ith(T))×s(T);

P1=(i1-Ith(T))×s(T);

P2=P1+i2×s(T);

P3=P2+i3×s(T);

P4=P3+i4×s(T)

P0 is the read power, P1 is the cooling power, P2 is the delete power, P3 is the write power, P4 is the overdrive power, and i0, i1, i2, i3, i4 are the drive composition current signals of Fig. 15.

When the optical disk drive is started, the optical disk drive 100 does not know the temperature of the laser diode 118. Therefore, the laser diode driver 116 cannot determine the slope of the drive current I to cause the laser diode 118 to generate laser light of a suitable power. The optical disk drive 100 thus performs an automatic power start procedure to calculate the drive current I in advance before the optical disk drive officially burns the data. The automatic power start program is also called the pre-burning program, in which the automatic power control area of the optical disc is burned by the pre-burning, and the data area is generally recorded. Figure 19 is a schematic diagram of a pre-programming process in accordance with the present invention. In one embodiment, before the CD player records the data to a target address of the optical disc, the optical disc drive writes the test data to the pre-burning program in the automatic power control area in front of the target address. In other embodiments, before the CD player records the data to a target address of the optical disc, the optical disc drive writes the test data before any automatic power control area to perform a pre-burning program, and then jumps to the target address to burn. data.

After the current programming process begins, the automatic power control system 106 performs a first automatic power control procedure in the first automatic power control region to perform the first adjustment di according to the detected intensity pi of the reflected light of the laser light. When the laser light exits the first automatic power control region, the automatic power control system 106 stops the transmission of the laser light until it reaches the second automatic power control region. The automatic power control system 106 then performs three additional automatic power control procedures one after the other to make three additional adjustments depending on the detected intensity pi of the reflected light of the laser light, which are only three examples. When the automatic power control bandwidth becomes lower or the current laser power is higher than the target laser power, the automatic power control system 106 must perform more automatic power control procedures in other automatic power control regions in order to obtain a convergent laser power. Finally, the detected signal strength pi is equal to the target laser power, and the calculation process of the drive current ends. The CD player can then burn the data to the target address with the correct laser power.

Figure 20 is a schematic illustration of another embodiment of a pre-burning program in accordance with the present invention. In the pre-programming process, the optical disk drive 100 moves the laser diode 119 of the read head to the automatic power control area of the optical disk, and performs 4 automatic power control programs in the automatic power control area to perform 4 times of laser light. The calculation of the power. In one embodiment, the automatic power control zone is the optimal automatic power control zone for the optical disc. When the calculation of the laser power Pi is completed, the optical disk drive can move the laser diode 118 to the target address for normal programming.

Although the present invention has been disclosed in the above preferred embodiments, it is not intended to limit the invention, and it is intended that the invention may be modified and modified without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

400. . . CD player

402. . . Write pulse generator

404. . . Sampling pulse generator

410. . . Front end detection diode

430. . . Controller

406. . . Automatic power control system

412a, 412b. . . Sample and hold circuit

411a, 411b. . . Low pass filter

413. . . Analog to digital converter

414. . . Compensator

415. . . Digital to analog converter

416. . . Laser diode driver

418. . . Laser diode

700. . . CD player

702. . . Write pulse generator

704. . . Sampling pulse generator

706. . . Automatic power control system

730. . . Controller

710. . . Front end detection diode

712a, 712b. . . Sample and hold module

711a, 711b. . . Low pass filter

713. . . Digital module

722. . . Analog to digital converter

724,725. . . filter

714. . . Compensator

728. . . Compensation filter

715. . . Digital to analog converter

716. . . Laser diode driver

718. . . Laser diode

100. . . CD player

101. . . Controller

102. . . Write pulse generator

104. . . Sampling pulse generator

106. . . Automatic power control system

112. . . Sample and hold circuit

114. . . Compensator

116. . . Laser diode driver

118. . . Laser diode

110. . . Front end detection diode

120. . . Power initial setting module

202,204,206,208,210. . . Current amplifier

214. . . Laser diode

300. . . Compensator

302. . . Subtractor

304. . . Compensation filter

Figure 1 shows the relationship between laser light power and drive current;

Figure 2 is a schematic diagram of signals generated by conventional automatic power control mechanisms;

Figure 3 is a schematic diagram of signals generated by an automatic power control mechanism corresponding to a Blu-ray disc;

Figure 4 is a block diagram of an optical disk drive including an automatic power control system in accordance with the present invention;

Figure 5 is a flow chart of a method for performing automatic power control in accordance with the present invention;

Figure 6 is a schematic diagram showing a sampling process of an analog input signal generated by a front-end detecting diode according to the present invention;

Figure 7 is a schematic illustration of the operation of an analog to digital converter and compensator in accordance with the present invention;

Figure 8 is a flow chart showing the operation of the compensator according to the present invention;

Figure 9 is a flow chart showing a method of switching between an automatic power control mode and a general power control mode in accordance with the present invention;

Figure 10 is a block diagram of an optical disk drive including an automatic power control system in accordance with the present invention;

Figure 11 is a diagram showing signals of an embodiment of an automatic power control program in accordance with the present invention;

Figure 12 is a block diagram of an optical disk drive including an automatic power control system in accordance with the present invention;

Figure 13 is a flow chart showing an automatic power control method of the optical disk drive according to the present invention;

Figure 14 is a block diagram of a laser diode driver in accordance with the present invention;

Figure 15 is a diagram showing the relationship between the power value of the laser light and the drive enable signal according to the present invention;

Figure 16 is a block diagram of a compensator according to the present invention;

Figure 17 is a view showing the test power of the laser light emitted by the laser diode according to the present invention;

Figure 18 is a view showing another embodiment of the test power of the laser light emitted by the laser diode according to the present invention;

Figure 19 is a schematic diagram of a pre-burning program according to the present invention;

Figure 20 is a schematic illustration of another embodiment of a pre-burning program in accordance with the present invention.

Claims (20)

A method for calculating an initial drive signal, wherein the initial drive signal drives a read head of a disc drive for reading data from a disc or writing data to the optical disc, the optical disc comprising a plurality of An automatic power control area and a plurality of data areas, the automatic power control areas and the data areas are spaced apart from each other, and the method includes: driving, in the automatic control areas, the read head to emit a Laser light; obtaining a detection intensity of the laser light; and calculating a modified initial driving signal according to the detection intensity and a target intensity. The method for calculating an initial driving signal according to claim 1, wherein the calculating the initial driving signal comprises: comparing the detected intensity with the target intensity to generate a power intensity difference; and determining the power intensity according to the power intensity The initial drive signal is differentially adjusted to obtain the modified start drive signal. The method for calculating an initial driving signal as described in claim 1, wherein the initial driving signal is used to drive a read power, a cooling power, a cancellation power, a write power, or an overdrive. power. A method of calculating an initial drive signal as described in claim 1 wherein the optical disk drive is a Blu-ray disk drive. The method for calculating an initial driving signal as described in claim 1, wherein the calculating of the modified initial driving signal comprises: (a) comparing the detected intensity and the target intensity to generate a power intensity difference; (b) Adjusting the initial drive signal according to the power intensity difference to obtain an intermediate start drive signal; (c) obtaining an intermediate start drive signal strength; (d) repeating steps (a), (b), (c) Determine the correction start drive signal. A method of calculating an initial drive signal as described in claim 5, wherein the determining step obtains at least two detected intensities to perform an interpolation algorithm to obtain the modified start drive signal. A method for calculating an initial drive signal as described in claim 5, wherein the determining step recursively performs steps (a), (b), and (c) until the detected intensity and the target intensity The power intensity difference is within a predetermined range. An automatic power control system for an optical disc drive, the optical disc drive having a read head having a front end detecting diode for reading data or writing data from a disc To the optical disc, the optical disc includes a plurality of automatic power control areas and a plurality of data areas, and the automatic power control system includes: a power initial value setting module, wherein the automatic driving control area drives the reading by using an initial driving signal Taking a head to emit a laser light; and a compensator for obtaining a detection intensity of the laser light by the front end detecting diode, and calculating a modified initial driving signal according to the detecting intensity and a target intensity. The automatic power control system of claim 8, wherein the initial driving signal is used to drive a read power, a cooling power, a cancellation power, a write power, or an overdrive power. The automatic power control system of claim 8, wherein the optical disk drive is a Blu-ray disk drive. The automatic power control system of claim 8, wherein the compensator calculates the modified initial driving signal according to the following steps: comparing the detected intensity and the target intensity to generate a power intensity difference; The power intensity difference adjusts the initial drive signal to obtain the modified start drive signal. The automatic power control system of claim 8, wherein the compensator calculates the modified start drive signal according to the following steps: (a) comparing the detected intensity and the target intensity to generate a power intensity difference; (b) adjusting the initial drive signal according to the power intensity difference to obtain an intermediate start drive signal; (c) obtaining an intermediate start drive signal strength; (d) repeating steps (a), (b), (c) ) to determine the correction start drive signal. The automatic power control system of claim 12, wherein the compensator obtains at least two detection intensities to perform an interpolation calculation to obtain the modified start drive signal. The automatic power control system of claim 12, wherein the compensator recursively performs steps (a), (b), and (c) until the power intensity difference between the detected intensity and the target intensity Within a predetermined range. An automatic power control system for an optical disk drive to control the power of a laser light, wherein the optical disk drive includes a read head and a front end detecting diode, and the read head receives a driving signal to generate the lightning Shooting light, the front end detecting diode detects the laser light to generate an analog input signal, the automatic power control system includes: an analog to digital converter, converting the analog input signal into a digital data; a compensator, And coupled to the analog to digital converter, when a compensation driving signal is enabled, generating at least one driving component data according to the digital data and a target value; a controller coupled to the analog to digital converter and the The compensator enables a compensation driving signal; and a digital to analog converter coupled to the compensator to convert the driving component data into one analog type driving component signal. The automatic power control system of claim 15, wherein the automatic power control system further comprises: at least one filter coupled between the analog to digital converter and the compensator, when a filter driving signal The digital data is filtered when enabled; wherein the controller enables the filtered drive signal when automatic power control is implemented. The automatic power control system of claim 15, wherein the compensator comprises: at least one subtractor, subtracting the digital data from the target value to obtain a power intensity difference; and a compensation filter, filtering the The power intensity difference is used to generate the drive composition data. An automatic power control method for an optical disk drive to control the power of a laser light, wherein the optical disk drive includes a read head and a front end detecting diode, and the read head receives a driving signal to generate the Laser light, the front end detecting diode detects the laser light to generate an analog input signal, the method comprising the steps of: enabling a compensation driving signal; and inputting the analog input when a digital driving signal is enabled The signal is converted into a digital data; when the compensation driving signal is enabled, at least one driving component data is generated according to the digital data and a target value; and the driving component data is converted into one analog type driving component signal. The method of automatic power control according to claim 18, wherein the method further comprises: filtering the digital data with at least one filter when a filtered driving signal is enabled. The method for automatic power control according to claim 18, wherein the generating of the at least one driving component data further comprises: subtracting the digital data from the target value to obtain a power intensity difference; and filtering the power intensity difference. To generate the drive component data.