CN1252706C - Outputting power method for controlling return circuit and optical read-write head by automatic power - Google Patents
Outputting power method for controlling return circuit and optical read-write head by automatic power Download PDFInfo
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- CN1252706C CN1252706C CN 02145839 CN02145839A CN1252706C CN 1252706 C CN1252706 C CN 1252706C CN 02145839 CN02145839 CN 02145839 CN 02145839 A CN02145839 A CN 02145839A CN 1252706 C CN1252706 C CN 1252706C
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Abstract
The present invention relates to a method for automatically controlling the output power of an optical reading-writing head. The method comprises: shifting a first switch to connect a first output end of a comparison circuit to a power supply and shifting a second switch to connect a first signal source to a driving circuit so as to make the driving circuit control the output power according to a first signal when the output power of the optical reading-writing head is changed; shifting the first switch to connect a first input end of the comparison circuit to a detector and shifting the second switch to connect the output end of the comparison circuit with the driving circuit so as to make the driving circuit control the output power according to a comparison signal when the potential difference between the first input end and the output end of the comparison circuit is gradually stable.
Description
Technical field
The invention provides a kind of method of automatic control output power, refer to a kind of automatic power control circuit method of the output power of the optical read/write head of control one CD player automatically of using especially.
Background technology
In recent years along with the Computing ability is more and more powerful, add that development of internet technology is constantly progressive, make the user utilize computing machine as multimedia audiovisual medium and utilize computing machine as and the starting point linked up of the virtual network world and the various information of a large amount of accesses of world-wide web have been become a kind of trend.In this trend, because the demand to the data memory space heightens, therefore various storage tool also becomes popular product thereupon, wherein utilize CD as the product of medium because CD is honest and clean and volume is light at the bottom of unit price under the same memory capacity, not thin not taking up space and being easy to carry, all very attracted attention all the time, the function of various especially over the years CD player and CD writer is become stronger day by day, reading quality and storage speed constantly upwards promotes, add except the CD of original CD specification, same volume more occurred but the DVD specification of capacity increase several times, the more feasible standard of utilizing CD player and CD writer almost to become every personal computer is equipped with.
CD player and CD writer are utilized optical principle for reading and writing of the data of being stored on the CD, so in reading mechanism and writing mechanism wherein, all rely on an optical read/write head (Pick-Up Head), are generally a laser and/write head.When fetch phase, one CD player or a CD writer are set in a preset value with its laser and/write head output output power of laser, so that the size of this Wavelength of Laser is fixed in when this laser radiation is on a CD, its catoptrical wavelength just can detect the numerical value of light signal for the photodetector on this CD player or the CD writer, and the form of these optical disc storage data, be compacting or imprinting the reflective character pit or the projection that differ on this optical disc surface, or special plated film, make when this photodetector detects this reflected light, can tell a plurality of different reflected light wavelength, and reach purpose by this with the digital store data.And when write phase, one CD writer also is set in a preset value with its laser and/write head output output power of laser, so that the size of this Wavelength of Laser be fixed in when this laser radiation when one can write formula CD (CD-R or CD-RW), the numerical value that this laser can change the part surface plated film character of this write formula CD of being irradiated to, then desire to be stored to the data that this can write the digital form of formula CD according to this CD writer again, this laser and/write head of stepless control is exported a plurality of different wavelength of laser, and utilizes this mode that the data carving of this digital form can be write on the formula CD to this.
See also Fig. 1, in order to allow this CD player or this CD writer when fetch phase and the write phase, the output power of its laser and/write head output can be continued to maintain a preset value and make its not change to some extent along with the change of objective environment (as the variation of temperature etc.), known technology uses in a CD player usually as (the Automatic Power Control Loop of the automatic power control circuit among Fig. 1, APCLoop) 10 form a feedback closed-loop path (Feedback Closed Loop) to reach the purpose of stablizing its output power with an optical read/write head 20, automatic power control circuit 10 includes one drive circuit 18, be electrically connected on optical read/write head 20, be used for driving optical read/write head 20; One comparator circuit 14, it includes a first input end, one second input end and an output terminal, comparator circuit 14 is used for relatively binary signal from this first input end and the input of this second input end to produce a corresponding comparison signal y, and this output terminal is electrically connected on driving circuit 18, is used for exporting comparison signal y to driving circuit 18; One detecting device 12, be used for detection optical read/write head 20 output power and produce a corresponding detection signal ε and import the first input end of detection signal ε to comparator circuit 14; One signal source 16 is used to provide second input end of a signal γ to comparator circuit 14, and signal γ represents the desired value size of output power of the optical read/write head 20 of this CD player.Automatic power control circuit 10 utilizes the detection signal ε that is produced by detecting device 12 to feed back to comparator circuit 14, and utilize the detection signal ε that comparator circuit 14 relatively feeds back and the signal γ of generation entry mark performance number to produce the output power of comparison signal y with control optical read/write head 20, utilize this feedback control mechanism and for the adjustment that the parameter of each element in the loop 10 suits, can make the output power of optical read/write head 20 maintain the size of expection.In inserting different signal amplification circuits or power amplification circuit between each element of automatic power control circuit 10 according to demand (for example between the output terminal and driving circuit 18 of comparator circuit 14, perhaps between the first input end of detecting device 12 and comparator circuit 14), and comparator circuit 14 can use different circuit units to realize, general its includes an operational amplifier (Operational Amplifier) 22, one electric capacity (Capacitor) 24 and two resistance (Resistor) 26 and 28, and interconnect as shown in Figure 1, signal source 16 is generally the signal value that digital controlled signal that a digital signal processing chip (Digital SignalProcessing Chip, DSP Chip) produced converts via a digital/analog converter (D/A Converter) again.
Yet, automatic power control circuit 10 a very serious defective occurs in the output power that this CD player desire changes optical read/write head 20, be that automatic power control circuit 10 needs a period of time just can enter homeostasis, see also Fig. 2, Fig. 2 is shown in the synoptic diagram of the voltage Vc of the signal γ shown in Fig. 1, comparison signal y, detection signal ε and electric capacity 24 along time shaft t change, the parameter that note that each element that can design automatic power control circuit 10 makes that working as signal γ is γ
1And when automatic power control circuit 10 was in homeostasis, comparison signal y was y
1, detection signal ε is γ
1, voltage Vc then is (γ
1-y
1); And work as signal γ is γ
2And when automatic power control circuit 10 was in homeostasis, comparison signal y was y
2, detection signal ε is γ
2, voltage Vc then is (γ
2-y
2).When this CD player desire with the output power of optical read/write head 20 when a lower numerical value is adjusted to a higher numerical value, it is in time t
1The time with signal γ from γ
1Switch to γ
2The voltage of each node in the middle of the automatic power control circuit 10 is converted to a new steady-state value from original steady-state value at this moment, but because the relation of the capacity effect of automatic power control circuit 10 self (can be with electric capacity 24 as representative in Fig. 1, because the capacity effect of automatic power control circuit 10 overwhelming majority is provided by electric capacity 24), just can enter new homeostasis after must charging to the equivalent capacity of this capacity effect, as voltage Vc represented among Fig. 2 in time t
1The time be (γ
1-y
1), via the charging of a period of time just in time t
2The time enter a steady-state value (γ
2-y
2); Similarly, comparison signal y is in time t
1The time be y
1+ (γ
2-γ
1), via the charging of a period of time just in time t
2The time enter a steady-state value y
2Detection signal ε is then in time t
1The time be γ
2, via the charging of a period of time just in time t
2The time enter a steady-state value γ
2And when this CD player desire with the output power of optical read/write head 20 when a higher numerical value is adjusted to a lower numerical value, it is in time t
3The time with signal γ from γ
2Switch to γ
1The voltage of each node in the middle of the automatic power control circuit 10 is converted to a new steady-state value from original steady-state value at this moment, but the relation of the capacity effect of same because automatic power control circuit 10 self, just can enter new homeostasis after must discharging to the equivalent capacity of this capacity effect, as voltage Vc represented among Fig. 2 in time t
3The time be (γ
2-y
2), via the charging of a period of time just in time t
4The time enter a steady-state value (γ
1-y
1); Similarly, comparison signal y is in time t
3The time be y
2-(γ
2-γ
1), via the charging of a period of time just in time t
4The time enter a steady-state value y
1Detection signal ε is then in time t
3The time be γ
1', via the charging of a period of time just in time t
4The time enter a steady-state value γ
1
As mentioned above because automatic power control circuit must discharge and recharge the unstable state equilibrium state of a period of time of causing to the equivalent capacity of wherein capacity effect, many bad influences are arranged for the operation of CD player.In write phase when the reading speed of buffer zone during greater than writing speed (Buffer-Under-Run), the operation that this CD player must stop imprinting entering idle state once again up to working storage, because the overlong time of this unstable state equilibrium state will cause recording power excessive or too small, then in the generation of this tie point (Linking Point) data that make the mistake easily; The overlong time of this unstable state equilibrium state also causes servomotor fault (ServoFailure) easily when fetch phase again, and for example tracking servo motor (Tracking Servo) or focus servo motor (Focusing Servo) are out of hand etc.
Summary of the invention
Fundamental purpose of the present invention be to disclose a kind of in switching an automatic power control circuit two switches (Switch) and can make this automatic power control circuit reach the method for a homeostasis fast, above-mentioned known to solve because the problem that overlong time was caused of unstable state equilibrium state, and when unstable state, utilize and open the loop one default driving voltage is provided, reach the requirement that read/write head output power moment switches.
According to the invention provides a kind of automatic power control circuit method of the output power of the optical read/write head of control one CD player automatically of using, this automatic power control circuit includes a detecting device, is used for detecting the output power of this optical read/write head and produces a corresponding detection signal; One comparator circuit, it includes a first input end, one second input end and an output terminal, and this output terminal is used for exporting a comparison signal; One first switch is used for choosing one to input to this first input end of this comparator circuit from the detection signal of the output signal of a power supply and this detecting device; One first signal source is used to provide one first signal; One drive circuit is electrically connected on this optical read/write head, is used for driving this optical read/write head; And, be used for from this first signal and this comparison signal, choosing a signal to export this driving circuit to a second switch; And this method includes following steps: when desire changes the output power of this optical read/write head, switch this first switch the first input end of this comparator circuit be connected to this power supply, and switch that this second switch connects this first signal source and this driving circuit so that this driving circuit according to the output power of this this optical read/write head of first signal controlling; And afterwards when the potential difference (PD) convergence of the first input end of this comparator circuit and output terminal is stablized, switch this first switch this first input end of this comparator circuit is connected to this detecting device, switch this second switch and connect this output terminal of this comparator circuit and this driving circuit so that this driving circuit is controlled the output power of this optical read/write head according to this comparison signal.
The present invention utilizes two switches that this automatic power control circuit is switched to open circuit (Open Loop) from a closed-loop path when desire changes the output power of this optical read/write head, utilize on the one hand a power supply to accelerate discharging and recharging the time to the equivalent capacity of this automatic power control circuit, then provide a previously selected signal value to control the output power of this optical read/write head on the other hand, up to the new balance stable state of this automatic power control circuit convergence one, utilize this two switch that this automatic power control circuit is switched go back to the closed-loop path again, significantly reduce the purpose that this automatic power control circuit enters balance stable state required time and reach.
Description of drawings
Fig. 1 is the functional block diagram of known automatic power control circuit.
Fig. 2 is the time dependent synoptic diagram of each signal in the automatic power control circuit of Fig. 1.
Fig. 3 is the functional block diagram of automatic power control circuit of the present invention.
Fig. 4 is the time dependent synoptic diagram of each signal in the automatic power control circuit of Fig. 3.
The reference numeral explanation
10,30 automatic power control circuits, 12,32 detecting devices
14,34 comparator circuits, 16 signal sources
18,38 driving circuits, 20,40 optical read/write heads
22,42 operational amplifiers, 24,44 electric capacity
26,28,46,48 resistance
36 secondary signal sources, 50 first signal sources
52 power supplys, 54 first switches
56 second switches
58 ON-OFF control circuit
Embodiment
See also Fig. 3, Fig. 3 represents an automatic power control circuit 30 of the present invention, and it includes a detecting device 32, is used for detecting the output power of an optical read/write head 40 and produces a corresponding detection signal ε; One comparator circuit 34, it includes a first input end, one second input end and an output terminal, comparator circuit 34 is used for relatively from the binary signal of this first output terminal and the input of this second input end producing a corresponding comparison signal y, and this output terminal is used for exporting comparison signal y; One first switch 54 is used for choosing one to input to the first input end of comparator circuit 34 from the detection signal ε of the output signal of a power supply 52 and detecting device 32; One first signal source 50 is used to provide one first signal; One drive circuit 38 is electrically connected on optical read/write head 40, is used for driving optical read/write head 40; One second switch 56 is used for choosing a signal to export driving circuit 38 to from this first signal and comparison signal y; One secondary signal source 36 is used to provide second input end of a secondary signal γ to comparator circuit 34, and secondary signal γ represents the desired value size of output power of the optical read/write head 40 of this CD player; And an ON-OFF control circuit 58, be used for according at least one node signal value in this automatic power control circuit (Node Signal Value) to control first switch 54 and second switch 56.In inserting different signal amplification circuits or power amplification circuit between each element of automatic power control circuit 30 according to demand (for example between the output terminal and driving circuit 38 of comparator circuit 34, perhaps between the first input end of detecting device 32 and comparator circuit 34), detecting device 32 is generally a photodiode (PhotoDiode), be used for detecting the output power of this optical read/write head, and comparator circuit 34 can use different circuit units to realize, general its includes an operational amplifier 42, one electric capacity 44 and two resistance 46 and 48, and interconnect as shown in Figure 3, secondary signal source 36 is generally the signal value that digital controlled signal that a digital signal processing chip produced converts via a digital/analog converter again, power supply 52 can and provide a plurality of output voltage signals (as shown in ensuing embodiment) for a voltage source usually in addition, yet it can also and provide a plurality of output current signals for a current source.In one embodiment of the invention, first signal source 50 is dependent on this CD player and desires to enter the initial calibration program (Calibration) that reads or carry out during write phase, the numerical value that the envelope loop state enters the one group of comparison signal y that obtains behind the homeostasis that closes via automatic power control circuit 30 decides, power supply 52 is then for including the voltage source 52 of a system voltage Vcc and a ground voltage GND, ON-OFF control circuit 58 is controlled first switch 54 and second switch 56 according to comparison signal y and this first signal of this output terminal output of comparator circuit 34 again, its principle of operation is as follows: when secondary signal γ produces step transformation (Step Transition), ON-OFF control circuit 58 switches to voltage source 52 with first switch 54 from detection signal ε, simultaneously second switch 56 is switched to this first signal from comparison signal y; And the number of times that equates when comparison signal y and this first signal is when equaling 2, and 58 of ON-OFF control circuit are switched first switch 54 and are back to detection signal ε from voltage source 52, simultaneously second switch 56 is switched to comparison signal y from this first signal.The above only is preferred embodiment of the present invention, other all have the different application of same characteristic features, all belong to covering scope of the present invention.The detail operations principle of automatic power control circuit 30 of the present invention sees also Fig. 4, and details are as follows.
Fig. 4 is shown in the synoptic diagram that the output signal y ' of the voltage Vc of output signal x, comparison signal y, detection signal ε, electric capacity 44 of the secondary signal γ shown in Fig. 3, first switch and second switch changes along a time shaft t, the parameter that note that each element that can design automatic power control circuit 30 makes that working as secondary signal γ is γ
1And when automatic power control circuit 30 was in homeostasis, output signal x was γ
1, comparison signal y is y
1, detection signal ε is γ
1, voltage Vc then is (γ
2-y
1); And work as signal γ is γ
2And when automatic power control circuit 30 was in homeostasis, output signal x was γ
2, comparison signal y is y
2, detection signal ε is γ
2, voltage Vc then is (γ
2-y
2).When this CD player desire with the output power of optical read/write head 40 when a lower numerical value is adjusted to a higher numerical value, it is in time t
1The time with signal γ from γ
1Switch to γ
2, if this moment is y＞y ', and ON-OFF control circuit 58 switches to the system voltage Vcc of voltage source 52 with first switch 54 from detection signal ε, and (output signal x is in time t as shown in Figure 4
1The time rise to Vcc), then system voltage Vcc is soon with electric capacity 44 chargings, make voltage Vc in very short time from time t
1(γ
1-y
1) entry time t
2Steady-state value (γ
2-y
2), and simultaneously ON-OFF control circuit 58 also switches to this first signal with second switch 56 from comparison signal y, so the numerical value that obtains via initial calibration owing to this first signal is the steady-state value y of itself and comparison signal y
2Very approaching, so this first signal can ought not reach steady-state value y at comparison signal y
2Replace before comparison signal y input driving circuit 38 with produce one with the output power of the very approaching optical read/write head 40 of target power, level off to steady-state value y up to comparison signal y
2After, ON-OFF control circuit 58 is switched this two switch again and automatic power control circuit 30 is switched go back to a closed-loop path provides a function of stablizing output power to bring into play it; And when this CD player desire with the output power of optical read/write head 40 when a higher numerical value is adjusted to a lower numerical value, it is in time t
3The time with signal γ from γ
2Switch to γ
1, if this moment is y＜y ', and ON-OFF control circuit 58 switches to the ground voltage GND of voltage source 52 with first switch 54 from detection signal ε, and (output signal x is in time t as shown in Figure 4
3The time rise to GND), then ground voltage GND is soon with electric capacity 44 discharges, make voltage Vc in very short time from time t
3(γ
2-y
2) entry time t
4The time steady-state value (γ
1-y
1), and simultaneously ON-OFF control circuit 58 also switches to this first signal with second switch 56 from comparison signal y, so the numerical value that obtains via initial calibration owing to this first signal is the steady-state value y of itself and comparison signal y
1Very approaching, so this first signal can ought not reach steady-state value y at comparison signal y
1Replace before comparison signal y input driving circuit 38 with produce one with the output power of the very approaching optical read/write head 40 of target power, level off to steady-state value y up to comparison signal y
1After, ON-OFF control circuit 58 is switched this two switch again and automatic power control circuit 30 is switched go back to a closed-loop path provides a function of stablizing output power to bring into play it.The synoptic diagram of known technology more shown in Figure 2 and synoptic diagram of the present invention shown in Figure 4 as can be known, the time (t of electric capacity 44 chargings among the present invention
2-t
1) and the discharge time (t
4-t
3) more than the time (t of electric capacity in the known technology 24 charging
2-t
1) and the discharge time (t
4-t
3) shorten manyly, the time that comparison signal y promptly also of the present invention arrives steady-state value shortens many than known technology, and this is because the relation that the present invention utilizes a bigger potential difference (PD) that electric capacity 44 is discharged and recharged; And the present invention be used for input driving circuit 38 with the output signal y ' of the second switch of the output power of control optical read/write head 40 almost whole process be maintained at a steady-state value, this is owing to be the relation that replaces its input driving circuit 38 with the fixed signal of another its steady-state value of convergence before comparison signal y ought not reach steady-state value.Then utilize above-mentioned design, automatic power control circuitry 30 of the present invention can reach the purpose that the output power that makes optical read/write head 40 enters the homeostasis state rapidly.
With known utilize an automatic power control circuitry automatically the method for the output power of the optical read/write head of control one CD player compare, method of the present invention has to be utilized one first switch to switch to one to discharge and recharge the equivalent capacity of mechanism with the capacity effect that discharges and recharges this automatic power control circuitry, and the fixed signal of utilizing a second switch to switch to the steady-state value of a convergence comparison signal replaces its input driving circuit driving the feature of this optical read/write head, therefore can make the output power of this optical read/write head enter the homeostasis state rapidly.
The above only is preferred embodiment of the present invention, and all equivalences of doing according to claims of the present invention change and improve, and all should belong to covering scope of the present invention.
Claims (24)
1. one kind is used the automatic power control circuit method of the output power of the optical read/write head of control one CD player automatically, and this automatic power control circuit includes:
One detecting device is used for detecting the output power of this optical read/write head and produces a corresponding detection signal;
One comparator circuit, it includes a first input end, one second input end and an output terminal, and this output terminal is used for exporting a comparison signal;
One first switch is used for choosing one to input to this first input end of this comparator circuit from the detection signal of the output signal of a power supply and this detecting device;
One first signal source is used to provide one first signal;
One drive circuit is electrically connected on this optical read/write head, is used for driving this optical read/write head;
One second switch is used for choosing a signal to export this driving circuit to from this first signal and this comparison signal;
This method includes:
When desire changes the output power of this optical read/write head, switch this first switch the first input end of this comparator circuit be connected to this power supply, and switch that this second switch connects this first signal source and this driving circuit so that this driving circuit according to the output power of this this optical read/write head of first signal controlling; And
Afterwards when the potential difference (PD) convergence of the first input end of this comparator circuit and output terminal is stablized, switch this first switch this first input end of this comparator circuit is connected to this detecting device, switch this second switch and connect this output terminal of this comparator circuit and this driving circuit so that this driving circuit is controlled the output power of this optical read/write head according to this comparison signal.
2. the method for claim 1, wherein this power supply is a voltage source, the output signal of this power supply is a voltage signal.
3. the method for claim 1, wherein this power supply is a current source, the output signal of this power supply is a current signal.
4. the method for claim 1, this comparison signal of proofreading and correct this comparator circuit output when wherein this first signal is stablized owing to the potential difference (PD) convergence of this first input end of this comparator circuit and this output terminal produces.
5. the method for claim 1, wherein this of this comparator circuit second input end is connected in a secondary signal source, be used for importing a secondary signal, and this comparator circuit relatively this detection signal of transmitting of the output signal that transmits of this secondary signal and this power supply or this detecting device to produce this comparison signal.
6. method as claimed in claim 5, wherein this secondary signal source is a digital/analog converter.
7. the method for claim 1, wherein this automatic power control circuit also comprises an ON-OFF control circuit, is used for according to this comparison signal of this output terminal output of this comparator circuit and this first signal to control this first switch and this second switch.
8. method as claimed in claim 7, wherein when desire changes the output power of this optical read/write head, this ON-OFF control circuit elder generation this first switch of switching is connected to this power supply with this first input end of this comparator circuit, and switch this second switch and connect this first signal source and this driving circuit, when the number of times that equates in this comparison signal and this first signal equals a predetermined value afterwards, switch this first switch this first input end of this comparator circuit is connected to this detecting device, and switch this output terminal and this driving circuit that this second switch connects this comparator circuit.
9. the method for claim 1, wherein this comparator circuit includes an operational amplifier, an electric capacity and two resistance.
10. method as claimed in claim 2, wherein this voltage source provides an earthing potential.
11. the method for claim 1, wherein this detecting device is a photodiode, is used for detecting the output power of this optical read/write head.
12. the method for claim 1, wherein this automatic power control circuit also includes an amplifying circuit, is electrically connected on this second switch, is used for amplifying this first signal or this comparison signal.
13. an automatic power control circuit, it is used for controlling automatically the output power of the optical read/write head of a CD player, and this automatic power control circuit includes:
One detecting device is used for detecting the output power of this optical read/write head and produces a corresponding detection signal;
One comparator circuit, it includes a first input end, one second input end and an output terminal, and this output terminal is used for exporting a comparison signal;
One first switch is used for choosing one to input to this first input end of this comparator circuit from the detection signal of the output signal of a power supply and this detecting device;
One first signal source is used to provide one first signal;
One drive circuit is electrically connected on this optical read/write head, is used for driving this optical read/write head;
One second switch is used for choosing a signal to export this driving circuit to from this first signal and this comparison signal;
Wherein when desire changes the output power of this optical read/write head, switch this first switch the first input end of this comparator circuit be connected to this power supply, and switch that this second switch connects this first signal source and this driving circuit so that this driving circuit according to the output power of this this optical read/write head of first signal controlling; And
Afterwards when the potential difference (PD) convergence of the first input end of this comparator circuit and output terminal is stablized, switch this first switch this first input end of this comparator circuit is connected to this detecting device, switch this second switch and connect this output terminal of this comparator circuit and this driving circuit so that this driving circuit is controlled the output power of this optical read/write head according to this comparison signal.
14. automatic power control circuit as claimed in claim 13, wherein this power supply is a voltage source, and the output signal of this power supply is a voltage signal.
15. automatic power control circuit as claimed in claim 13, wherein this power supply is a current source, and the output signal of this power supply is a current signal.
16. automatic power control circuit as claimed in claim 13, this comparison signal of proofreading and correct this comparator circuit output when wherein this first signal is stablized owing to the potential difference (PD) convergence of this first input end of this comparator circuit and this output terminal produces.
17. automatic power control circuit as claimed in claim 13, wherein this of this comparator circuit second input end is connected in a secondary signal source, be used for importing a secondary signal, and this comparator circuit relatively this detection signal of transmitting of the output signal that transmits of this secondary signal and this power supply or this detecting device to produce this comparison signal.
18. automatic power control circuit as claimed in claim 17, wherein this secondary signal source is a digital/analog converter.
19. automatic power control circuit as claimed in claim 13, it also comprises an ON-OFF control circuit, is used for according to this comparison signal of this output terminal output of this comparator circuit and this first signal to control this first switch and this second switch.
20. automatic power control circuit as claimed in claim 19, wherein when desire changes the output power of this optical read/write head, this ON-OFF control circuit elder generation this first switch of switching is connected to this power supply with this first input end of this comparator circuit, and switch this second switch and connect this first signal source and this driving circuit, when the number of times that equates in this comparison signal and this first signal equals a predetermined value afterwards, switch this first switch this first input end of this comparator circuit is connected to this detecting device, and switch this output terminal and this driving circuit that this second switch connects this comparator circuit.
21. automatic power control circuit as claimed in claim 13, wherein this comparator circuit includes an operational amplifier, an electric capacity and two resistance.
22. automatic power control circuit as claimed in claim 14, wherein this voltage source provides an earthing potential.
23. automatic power control circuit as claimed in claim 13, wherein this detecting device is a photodiode, is used for detecting the output power of this optical read/write head.
24. automatic power control circuit as claimed in claim 13, it also includes an amplifying circuit, is electrically connected on this second switch, is used for amplifying this first signal or this comparison signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02145839 CN1252706C (en) | 2002-10-15 | 2002-10-15 | Outputting power method for controlling return circuit and optical read-write head by automatic power |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 02145839 CN1252706C (en) | 2002-10-15 | 2002-10-15 | Outputting power method for controlling return circuit and optical read-write head by automatic power |
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| Publication Number | Publication Date |
|---|---|
| CN1490800A CN1490800A (en) | 2004-04-21 |
| CN1252706C true CN1252706C (en) | 2006-04-19 |
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|---|---|---|---|
| CN 02145839 Expired - Fee Related CN1252706C (en) | 2002-10-15 | 2002-10-15 | Outputting power method for controlling return circuit and optical read-write head by automatic power |
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