Method and device for generating a stable power control signal
Method and device for generating a stable power control signal in a CD recorder. The power control signal for controlling a laser diode may be a read level, an erase level and a write level. A pickup device outputs a feedback control signal to a read control circuit, and a read power control voltage is thus obtained. Then, the read power control voltage is inputted to a write control circuit, which generates first and second write power control voltages. The read level equals a reference voltage added by the read power control voltage, the erase level equals the read level added by the first write power control voltage, and the write level equals the erase level added by the second write power control voltage, so the read power control voltage and thus the read, erase and write levels are automatically and dynamically adjusted as the feedback control signal varies.
This application This patent application is a reissue application for commonly assigned U.S. Pat. No. 7,286,462, issued Oct. 23, 2007 from U.S. patent application Ser. No. 10/990,909 which claims the benefit of the U.S. provisional application Ser. No. 60/520,711, filed Nov. 17, 2003, the subject matter of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The invention relates in general to a method and a device for generating a stable power control signal in a CD recorder, and more particularly to a method for controlling a power control signal of a laser diode such that the read power control voltage is automatically and dynamically adjusted as a feedback control signal varies, and a read level, an erase level and a write level of the power control signal are also automatically and dynamically adjusted as the read power control voltage varies.
2. Description of the Related Art
When a conventional CD-RW (CD-ReWritable) recorder is writing a disk, a power control signal for controlling a laser diode may be a read level V_bias, an erase level V_erase and a write level V_write. When the recorder wants to read a CD-RW, the level of the power control signal is the read level V_bias. When the recorder is erasing data on the CD-RW disk, the level of the power control signal is the erase level V_erase. When the recorder wants to write data on the CD-RW disk, the level of the power control signal is the write level V_write. The power control signal controls the laser diode to generate a laser beam to read, erase, or write the CD-RW disk.
The CD-RW recorder further has a monitor diode for generating a current iM according to the intensity of the laser beam generated by the laser diode. An OP amplifier processes the current iM and then generates a feedback control signal FPDO.
In general, the read level V_bias, the erase level V_erase and the write level V_write are generated by generating a read power control voltage VRDCO, a first write power control voltage VW1DCO and a second write power control voltage VW2DCO. The read level V_bias equals a sum of a reference voltage Vref and the read power control voltage VRDCO, the erase level V_erase equals a sum of the read level V_bias and the first write power control voltage VW1DCO, and the write level V_write equals a sum of the erase level V_erase and the second write power control voltage VW2DCO.
The S/II 206 samples the feedback control signal FPDO according to a pulse signal E_Pulse of
However, because the circuit for generating the read power control voltage VRDCO is an open loop control system, the read power control voltage VRDCO will change as the temperature rises after a long term usage of the recorder. At this time, the read level V_bias, the first power control voltage VW1DCO and the second power control voltage VW2DCO will shift and errors occur, and the write quality is influenced.
SUMMARY OF THE INVENTIONIt is therefore an object of the invention to provide a method and a device for generating a stable power control signal, wherein the method and device can effectively improve the problem of the varying power control signal caused by the temperature variation in the long-term writing process.
The invention achieves the above-identified object by providing a CD recorder having a power control signal. The power control signal has a read level, an erase level and a write level. The read level equals a sum of a reference voltage and a read power control voltage, the erase level equals a sum of the read level and a first write power control voltage, and the write level equals a sum of the erase level and a second write power control voltage. The CD recorder of the invention includes a pickup device, a read control circuit and a write control circuit. The pickup device is for reading, erasing or writing a disk and generating a feedback control signal. The pickup device includes a laser diode and a monitor diode. The laser diode receives the power control signal, which enables the laser diode to generate a laser beam to read, erase or write the disk. The monitor diode senses intensity of the laser beam. The CD recorder generates the feedback control signal according to the intensity of the laser beam sensed by the monitor diode. The read control circuit has a read target value digital-to-analog converter for storing a plurality of first digital values and converting one of the first digital values into a first analog value. The read control circuit generates the read power control voltage according to the feedback control signal and the first analog value. The write control circuit has a write target value digital-to-analog converter for storing a plurality of second digital values and converting one of the second digital values into a second analog value. The write control circuit generates the first write power control voltage and the second write power control voltage according to the read power control voltage and the second analog value. The read power control voltage is automatically and dynamically adjusted as the feedback control signal varies, such that the read level, the erase level and the write level of the power control signal are also automatically and dynamically adjusted as the read power control voltage varies.
Other objects, features, and advantages of the invention will become apparent from the following detailed description of the preferred but non-limiting embodiments. The following description is made with reference to the accompanying drawings.
Please refer to
On the other hand, the write target value digital-to-analog converter (WDAC) 410 selects one of the stored digital values, and converts the selected digital values into a second analog signal A7 for output. The read power control voltage VRDCO′, which is inputted form the A4 end, and the second analog signal A7 are added together to obtain a sum, which is inputted to the low-pass filter 408 to obtain the first write power control voltage VW1DCO′. The amplifier 412 amplifies the first write power control voltage VW1DCO′ by G′ times to obtain the second write power control voltage VW2DCO′.
In this case, the read power control voltage VRDCO′ is generated in a close loop control manner by feeding back the feedback control signal FPDO′. The first write power control voltage VW1DCO′ and the second write power control voltage VW2DCO′ are generated in an open loop control manner. Thus, when the recorder is used for a long time such that the temperature of the laser diode 301 rises, the read power control voltage VRDCO′ is automatically and dynamically adjusted as the level of the feedback control signal FPDO′ varies.
In this case, because the first write power control voltage VW1DCO′ is generated in an open loop control manner, the value of the first write power control voltage VW1DCO′ basically does not tend to vary as the temperature changes, and the relationship between VW2DCO′ and VW1DCO is only determined by the magnification power G′ of the amplifier 412. Consequently, the erase level V_erase at this time equals (Vref+VRDCO′(TP3)+VW1DCO′).
The characteristic curves of the laser diode 301 have a linear zone LN. No matter how the temperature changes, the slope in the linear zone LN is kept constant. Because the erase level V_erase is still in the linear zone after it is risen to (Vref+VRDCO′(TP3)+VW1DCO′), the erase level V_erase at this time still enables the laser diode to generate the erase power P_erase.
Before the product of the invention is shipped out, an optimum setting value is obtained after the first write power control voltage VW1DCO′ is corrected. When the recorder is used, the read power control voltage VRDCO′ is dynamically adjusted as the feedback control signal FPDO′ varies, and simultaneously enables the erase level V_erase and the write level V_write to be dynamically adjusted as the feedback control signal FPDO′ varies. So, the invention can dynamically adjust the read level V_bias, the erase level V_erase and the write level V_write with the temperature variation, such that the laser diode generates the constant read power P_bias, erase power P_erase and write power P_write to keep the write quality of the recorder.
While the invention has been described by way of example and in terms of a preferred embodiment, it is to be understood that the invention is not limited thereto. On the contrary, it is intended to cover various modifications and similar arrangements and procedures, and the scope of the appended claims therefore should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements and procedures.
Claims
1. A CD recorder having a power control signal, which has a read level, an erase level and a write level, wherein the read level equals a sum of a reference voltage and a read power control voltage, the erase level equals a sum of the read level and a first write power control voltage, and the write level equals a sum of the erase level and a second write power control voltage, the CD recorder comprising:
- a pickup device for reading, erasing or writing a disk and generating a feedback control signal, the pickup device comprising: a laser diode for receiving the power control signal, which enables the laser diode to generate a laser beam to read, erase or write the disk; and a monitor diode for sensing intensity of the laser beam, wherein the CD recorder generates the feedback control signal according to the intensity of the laser beam sensed by the monitor diode;
- a read control circuit having a read target value digital-to-analog converter for storing a plurality of first digital values and converting one of the first digital values into a first analog value, wherein the read control circuit generates the read power control voltage according to the feedback control signal and the first analog value; and
- a write control circuit having a write target value digital-to-analog converter for storing a plurality of second digital values and converting one of the second digital values into a second analog value, wherein the write control circuit generates the first write power control voltage and the second write power control voltage according to the read power control voltage and the second analog value, wherein the read power control voltage is automatically and dynamically adjusted as the feedback control signal varies, such that the read level, the erase level and the write level of the power control signal are also automatically and dynamically adjusted as the read power control voltage varies.
2. The CD recorder according to claim 1, wherein the read control circuit further has:
- a sample and hold circuit for receiving the feedback control signal and obtaining a third analog value;
- a subtracter for subtracting the third analog value from the first analog value and outputting a difference between the first and third analog values; and
- a first low-pass filter for receiving the outputted difference of the subtracter and obtaining the read power control voltage.
3. The CD recorder according to claim 2, wherein the write control circuit further has:
- an adder for adding the read power control voltage and the second analog value together to obtain a sum, and outputting the sum to a second low-pass filter so as to obtain the first write power control voltage; and
- an amplifier for receiving the first write power control voltage and obtaining the second write power control voltage.
4. The CD recorder according to claim 3, wherein the read power control voltage is generated in a close loop control manner by feeding back the feedback control signal, and the first write power control voltage and the second write power control voltage are generated in an open loop control manner.
5. The CD recorder according to claim 4, wherein a magnification power exists in a relationship between the first and second write power control voltages outputted from the write control circuit.
6. The CD recorder according to claim 5, wherein the write target value digital-to-analog converter has an optimum setting value obtained after correction before the CD recorder is shipped out.
7. A method for generating a stable power control signal in a read control circuit and a write control circuit of a CD recorder, wherein the CD recorder has a laser diode and a monitor diode, the laser diode generates a laser beam to read, erase or write a disk, the CD recorder generates a feedback control signal according to intensity of the laser beam sensed by the monitor diode, the method enables the read control circuit to generate a read power control voltage and the write control circuit to generate a first write power control voltage and a second write power control voltage, the power control signal for controlling the laser diode has a read level, an erase level and a write level, the read level equals a sum of a reference voltage and the read power control voltage, the erase level equals a sum of the read level and the first write power control voltage, and the write level equals a sum of the erase level and the second write power control voltage, the method comprising the steps of:
- inputting the feedback control signal to the read control circuit to obtain the read power control voltage; and
- inputting the read power control voltage to the write control circuit to generate the first write power control voltage and the second write power control voltage, wherein the read power control voltage is automatically and dynamically adjusted as the feedback control signal varies, such that the read level, the erase level and the write level of the power control signal are also automatically and dynamically adjusted as the read power control voltage varies.
8. The method according to claim 7, wherein the read level enables the laser diode to generate a read power, the erase level enables the laser diode to generate an erase power, and the write level enables the laser diode to generate a write power.
9. The method according to claim 7, wherein the read power control voltage is generated in a close loop control manner by feeding back the feedback control signal, and the first write power control voltage and the second write power control voltage are generated in an open loop control manner.
10. A control device for generating a stable power control signal in a CD recorder, the CD recorder using a power control signal to access an optical disk, the power control signal having a read level, an erase level and a write level, the read level equaling a sum of a reference voltage and a read power control voltage, the erase level equaling a sum of the read level and a first write power control voltage, and the write level equaling a sum of the erase level and a second write power control voltage, the control device comprising:
- a read control circuit having a read target value digital-to-analog converter for storing a plurality of first digital values and converting one of the first digital values into a first analog value, the read control circuit generating the read power control voltage according to the feedback control signal and the first analog value; and
- a write control circuit having a write target value digital-to-analog converter for storing a plurality of second digital values and converting one of the second digital values into a second analog value, the write control circuit generating the first write power control voltage and the second write power control voltage according to the read power control voltage and the second analog value, wherein the read power control voltage is automatically and dynamically adjusted as the feedback control signal varies, such that the read level, the erase level and the write level of the power control signal are also automatically and dynamically adjusted as the read power control voltage varies.
11. The control device according to claim 10, wherein the read control circuit further has:
- a sample and hold circuit for receiving the feedback control signal and obtaining a third analog value;
- a subtracter for subtracting the third analog value from the first analog value and outputting a difference between the first and third analog values; and
- a first low-pass filter for receiving the outputted difference of the subtracter and obtaining the read power control voltage.
12. The control device according to claim 11, wherein the write control circuit further has:
- an adder for adding the read power control voltage and the second analog value together to obtain a sum, and outputting the sum to a second low-pass filter so as to obtain the first write power control voltage; and
- an amplifier for receiving the first write power control voltage and obtaining the second write power control voltage.
13. The control device according to claim 12, wherein the read power control voltage is generated in a close loop control manner by feeding back the feedback control signal, and the first write power control voltage and the second write power control voltage are generated in an open loop control manner.
14. The control device according to claim 13, wherein a magnification power exists in a relationship between the first and second write power control voltages outputted from the write control circuit.
15. The control device according to claim 14, wherein the write target value digital-to-analog converter has an optimum setting value obtained after correction before the CD recorder is shipped out.
16. The control device according to claim 14, wherein the CD recorder comprising:
- a pickup device for reading, erasing or writing the optical disk and generating a feedback control signal, the pickup device comprising: a laser diode for receiving the power control signal, which enables the laser diode to generate a laser beam to read, erase or write the disk; and a monitor diode for sensing intensity of the laser beam, wherein the CD recorder generates the feedback control signal according to the intensity of the laser beam sensed by the monitor diode.
17. A method for providing power control signals in an optical disk drive, comprising:
- receiving a feedback control signal that is based on an intensity of a laser output of the optical disk drive;
- providing a read power control signal according to the feedback control signal;
- providing a first write power control signal according to the read power control signal; and
- providing a second write power control signal according to the read power control signal.
18. The method according to claim 17, further comprising:
- inputting the feedback control signal to a read control circuit of the optical disk drive to generate the read power control signal; and
- inputting the read power control signal to a write control circuit of the optical disk drive to generate the first write power control signal and the second write power control signal.
19. The method according to claim 17, wherein the laser output has a read level, an erase level, and a write level, further wherein:
- the read level equals a sum of a reference signal of the laser output and the read power control signal;
- the erase level equals a sum of the read level and the first write power control signal; and
- the write level equals a sum of the erase level and the second write power control signal.
20. The method according to claim 19, wherein the read power control signal is automatically and dynamically adjusted as the feedback control signal varies, such that the read level, the erase level and the write level are also automatically and dynamically adjusted as the read power control signal varies.
21. The method according to claim 19, wherein the read level enables a laser diode associated with the laser output to generate a read power, the erase level enables the laser diode to generate an erase power, and the write level enables the laser diode to generate a write power.
22. The method according to claim 17, wherein the read power control signal is generated in a close loop control manner by feeding back the feedback control signal, and the first write power control signal and the second write power control signal are generated in an open loop control manner.
23. A control device for providing power control signals in an optical disk drive, comprising:
- a feedback control circuit configured to receive a feedback control signal that is based on an intensity of a laser output of the optical disk drive;
- a read control circuit configured to provide a read power control signal according to the feedback control signal;
- a write control circuit configured to provide a first write power control signal according to the read power control signal, and to provide a second write power control signal according to the read power control signal.
24. The control device according to claim 23, wherein the laser output has a read level, an erase level, and a write level, wherein:
- the read level is approximately equal to a sum of a reference signal of the laser output and the read power control signal;
- the erase level is approximately equal to a sum of the read level and the first write power control signal; and
- the write level is approximately equal to a sum of the erase level and the second write power control signal.
25. The control device according to claim 24, wherein the read control circuit is configured to automatically and dynamically adjust the read power control signal as the feedback control signal varies, enabling the read level, the erase level and the write level to also be automatically and dynamically adjusted as the read power control signal varies.
26. The method according to claim 23, wherein the read control circuit generates the read power control signal in a close loop control manner by feeding back the feedback control signal, and wherein write control circuit generates the first write power control signal and the second write power control signal in an open loop control manner.
27. A control device for providing power control signals in an optical disk drive, comprising:
- a feedback control means for receiving a feedback control signal that is based on an intensity of a laser output of the optical disk drive;
- a read control means for providing a read power control signal according to the feedback control signal;
- a write control means for providing a first write power control signal according to the read power control signal, and further to provide a second write power control signal according to the read power control signal.
28. The control device according to claim 27, wherein the laser output has a read level, an erase level, and a write level, wherein:
- the read level is approximately equal to a sum of a reference signal of the laser output and the read power control signal;
- the erase level is approximately equal to a sum of the read level and the first write power control signal; and
- the write level is approximately equal to a sum of the erase level and the second write power control signal.
29. The control device according to claim 28, wherein the read control means automatically and dynamically adjusts the read power control signal as the feedback control signal varies, enabling the read level, the erase level and the write level to also be automatically and dynamically adjusted as the read power control signal varies.
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Type: Grant
Filed: Oct 22, 2009
Date of Patent: Jun 14, 2011
Assignee: Han Holdings, LLC (Wilmington, DE)
Inventors: Chin-Yin Tsai (Taipei), Yi-Lin Lai (Taipei)
Primary Examiner: Peter Vincent Agustin
Attorney: Perkins Coie LLP
Application Number: 12/604,307
International Classification: G11B 7/00 (20060101);