CN101354895A - Method for balancing and adjusting CD ROM focus - Google Patents

Abstract

The invention relates to a method for adjusting focus balance of a CD driver. Firstly, a reference value is returned to zero; variables and direction for adjusting the position of focus balance are preset; according to the preset variables for adjusting the position of focus balance, a new C1C2 signal is generated; whether the new C1C2 signal value is larger than the former C1C2 signal value is compared; if yes, the direction of the adjusting variable is changed; otherwise, the direction of the original adjusting variable is maintained; secondly, whether the new C1C2 signal value is larger than the target value of C1C2T is checked; if yes, the adjusting step is returned and the position of focus balance is continuously adjusted; otherwise, the adjustment is finished so as to rapidly achieve the position of focus balance.

Description

Method for balancing and adjusting CD ROM focus

Technical field

The present invention relates to a kind of CD-ROM drive (optical disk drive), relate in particular to CD-ROM drive when reading CD, read head is in order to adjust the method that focuses on the equilibrium position.

Background technology

Because discs is with small intensive mark record data, CD-ROM drive must utilize the optical read head projecting laser to focus on the mark, by the catoptrical power of mark, convert digital signal to, and then through being decoded as data-signal, therefore whether focusing is correct, and directly the power of signal and the correctness of data are read in influence.

As shown in Figure 1, it is the focusing balance adjustment method (Focus balancecalibration) of known CD-ROM drive, utilizes read head 1 projecting beam 2 to discs 3, by discs 3 light beam 2 is reflected through read head 1, is radiated at light energy converter 4.Light energy converter 4 has four light receivers such as the A of being divided into, B, C and D, receives zones different in the folded light beam respectively, and the light quantity that conversion receives is the electric signal of relative intensity.Input amplifier (Amplifer) 5 then, electric signal addition respectively with A, C and B, D light receiver, form (A+C) and reach (B+D) two-part electric signal, again (A+C)-(B+D) both subtract each other the formation difference signal, after amplifying, form focus error signal FE (Focus Error), transfer to compensator 6.Form control signal by compensator (Compensator) 6, adjust read head via focusing servo unit (Focusing Servo Unit) 7 controls, to lock focus point on the mark of quick rotation and vibrations discs 3, make four light receivers of light energy converter 4 can correctly receive folded light beam, form the radiofrequency signal RF (Radio Frequency) of (A+B+C+D) through amplifier 8 additions, to represent the signal of mark, improve radiofrequency signal RF is converted to outputting data signals through modulating unit (Modulator) 9 reliability.

But focus point is the regional extent of a small distance, the focus point of aforementioned focusing adjustment locking, and may not be certain is the strongest position of radiofrequency signal RF.And the method that aforementioned focusing adjustment utilizes small electric signal to judge as calculation, be subjected to the systematic error of CD-ROM drive own easily, for example system's LASER Light Source is throwed the influence of the precision of non-uniform beam, optical system or four light receivers reception finish matter heterogeneous bodies of light energy converter 4 etc., is difficult for guaranteeing really locking focus point.Therefore, other has the adjustment focalizer of known CD-ROM drive, and the radiofrequency signal RF by amplifier 8 outputs utilizes radiofrequency signal change-over circuit (Radio FrequencyRipple Circuit), and promptly the RFRP circuit 10, radiofrequency signal RF are converted to the RFRP signal of waveform.By focusing on balancing unit 11 records and comparing the several RFRP signals in front and back, find out the strongest RFRP signal, produce error signal, form control signal through compensator 6, and cooperate focus error signal FE to lock the focus point scope, adjust the focused condition that read heads 1 reach the strongest RFRP signal by focusing servo unit 7 control, guarantee that directly radiofrequency signal RF that read head 1 reads mark is for the strongest, in order to decoding.

Yet single radiofrequency signal RF only represents the mark of dual code (Binary Code) 1 or 0, and the transcoding of still needing not is the directly signal of output of CD-ROM drive.With known EFM (Eight to FourteenModulation) 8-14 transcoding is example, will transfer the mark of 14bit originally to for the 8bit digital signal encoding, and 1 or 0 form with binary numerical value forms mark on discs.Therefore, read head must read the radiofrequency signal RF of 14bit mark complete one by one, could be correctly decoded the digital signal into 8bit through modulating unit 9, the radiofrequency signal RF that makes single mark can not guarantee that for the strongest other mark in the same group of digital signal also is the strongest.Sometimes in seeking the process of the strongest radiofrequency signal RF, adjust and focus on the several marks that often make in the same group of digital signal and become fuzzyly, cause and can't decode smoothly, so that seek the method for the strongest radiofrequency signal RF, still can't effectively promote the usefulness of CD-ROM drive integral body.Therefore, the focusing balance adjustment method of known CD-ROM drive still has problem to exist, and has to be solved.

Summary of the invention

The object of the present invention is to provide a kind of method for balancing and adjusting CD ROM focus, by detecting the quality of decoding quality in the modulated process, adjust the equilibrium position that focuses on automatically, to promote the overall efficiency of CD-ROM drive.

Another purpose of the present invention is providing a kind of method for balancing and adjusting CD ROM focus, utilizes and judges that front and back adjustment focuses on balance convergent direction and speed, to reach suitable focusing equilibrium position fast.

In order to reach the purpose of aforementioned invention, method for balancing and adjusting CD ROM focus of the present invention, reference value at first makes zero, preestablish and adjust variable and the direction that focuses on the equilibrium position, according to the default variable that focuses on the equilibrium position of adjusting, produce new C1C2 signal, newer C1C2 signal value is greater than previous C1C2 signal value, in this way, then change the direction of adjusting variable Δ FB, otherwise keep the direction of former adjustment variable Δ FB, and then check new C1C2 signal value＞C1C2T desired value, in this way, then be back to set-up procedure and continue to adjust the focusing equilibrium position, otherwise finish to adjust.

Description of drawings

Fig. 1 is the functional block diagram of the focus adjustment means of known CD-ROM drive.

Fig. 2 is the data structure of CD.

Fig. 3 is the functional block diagram of the focus adjustment means of CD-ROM drive of the present invention.

Fig. 4 is the process flow diagram of the focusing balance adjustment method of CD-ROM drive of the present invention.

The reference numeral explanation

20 modulating units

21 C1C2 signal generators

22 focus on balance calculation unit

23 compensators

24 focusing servo unit

25 read heads

26 signal processing units

27 debug unit

28 decoding units

S1 begins set-up procedure

S2 is C1C2n＞C1C2T step relatively

S3 adjusts FB variable step

S4 produces the C1C2n step

S5 is C1C2n＞C1C2n-1 step relatively

S6 keeps variable direction step

S7 changes variable direction step

S8 is C1C2n＞C1C2 T step relatively

The S9 end step

Embodiment

Relevant the present invention for achieving the above object, technological means that is adopted and effect thereof, especially exemplified by preferred embodiment, and accompanying drawings is as follows.

General CD discs is provided with the track bar of a spiral shape by inner ring to outer ring, track bar is a Lead-In Area (Lead-in Region) at the beginning, include catalogue (Table of Contents, abbreviate TOC as), track bar is divided into many fan sections (Sector) then, each fan section includes by 2352 data bytes (byte) and 98 subcodes (Subcode) byte, 98 frameworks (Frame) that behind the EFM modulating-coding, are divided into, as shown in Figure 2, the data structure that shows each framework, it at first is a synchronous code (SYNC), one subcode (Subcode), data field (Data), debug C1 district (Error Correct Code, be called for short ECC), data field and debug C2 district, wherein, debug C1C2 district is in order to solve the decoding error that is taken place in the reading of data process.A leading-out zone (Lead-out Region) is then followed in last fan section, the position that expression CD discs record data finish.

Please refer to Fig. 3, it is that CD ROM focus balance of the present invention is adjusted function, comprises a modulating unit 20, C1C2 signal generator 21, focuses on balance calculation unit 22, compensator 23 and focusing servo unit 24.Mainly read head in the CD-ROM drive 25 is read the radiofrequency signal RF that the discs mark is exported, decoding through modulating unit 20, be modulated in the data digital signal process, C1C2 signal generator 21 is with regard to C1C2 signal that decoding quality produced, utilize to focus on balance calculation unit 22 generations one error signal, transfer to compensator 23, cooperate focus error signal FE to form focus control signal, automatically adjust the focusing equilibrium position by focusing servo unit 24 control read heads, to keep decoding quality.

Wherein, modulating unit 20 comprises signal processing unit 26, debug unit 27 and decoding unit 28 etc.Signal processing unit 26 is an analog/digital signal conversion device, can convert the radiofrequency signal RF that is received from read head 25 to digital signal, i.e. 0 in the dual code or 1.27 dual codes that signal processing unit 26 is changed in debug unit (ECC, ErrorCorrect Code), whether wrong, to proofread and correct if differentiating the mark of reading one by one.Errorless mark after the interpretation utilizes decoding unit 28 decode modulated to be digital signal, as the output of CD-ROM drive.

In aforesaid modulated process, mark is read in order to proofread and correct in debug unit 27, in order to carrying out decode modulated.At the errors number of being read in the debug process, produce a relative C1C2 signal by C1C2 signal generator 21.When the C1C2 signal value was big more, it is many more that the mark mistake is read in representative, is not easy to carry out decode modulated more.Otherwise, when the C1C2 signal value more hour, it is less that the mark mistake is read in representative, carries out decode modulated easily.Therefore, debug unit 27 can be according to the C1C2 signal value, decodes or shows that mistake stops decode modulated.

In addition, focus on the C1C2 signal of balance calculation unit 22 in order to relatively to import by C1C2 signal generator 21.The main utilization adjusted the focusing equilibrium position, and the C1C2 signal value that produces is judged the convergent direction and the speed that focus on the equilibrium position relatively relatively, and suitable decision adjustment focuses on the amount of balance.Mat compensator 23 is adjusted the read head lens via focusing servo unit 24 and is moved up and down, and reaches to focus on the equilibrium position, and the C1C2 signal value is maintained below the desired value C1C2T, in order to decoding, improves the CD-ROM drive overall efficiency.

As shown in Figure 4, it adjusts the flow process that focuses on balance for the present invention.Too much when decoding error, cause the C1C2 signal value not when zone of reasonableness, the present invention promptly begins to adjust the focusing equilibrium position, utilizes C1C2 signal value convergence direction and speed, and the C1C2 signal value is got back to below the desired value C1C2T as early as possible.Before beginning to adjust, CD-ROM drive preestablishes and adjusts the variable Δ FB that focuses on balance is a scheduled volume, Δ FB=5 etc. for example, and set the direction of position convergent direction that focuses on balance for increasing, and to set acceptable C1C2 signal target value be C1C2T.It is as follows that it adjusts the step that focuses on balance method:

Step S1: begin to adjust the focusing equilibrium position, at first making zero focuses on the reference value FB=0 of equilibrium position.

Step S2: the C1C2 signal that will import at present is made as C1C2n, and it is relatively big or small with desired value C1C2T, do you that is whether check C1C2n＞C1C2T? if the C1C2n signal value is less than desired value C1C2T, just the errors number of C1C2n is in acceptable zone of reasonableness, then keep the position of former focusing balance, and enter step S9; If the C1C2n signal value is greater than desired value C1C2T, just the errors number of C1C2n is not in acceptable zone of reasonableness, and C1C2n's is too much wrong, and the position that focuses on balance is bad, needs to adjust the position that focuses on balance, then enters next step.

Step S 3: according to setting the direction of position convergent direction for increasing that focuses on balance, adjusting the position FB that focuses on balance increases by a predetermined amount delta FB.

Step S4: make ordinal number n=n+1 to produce new C1C2n signal.

Step S5:, whether promptly check C1C2n＞C1C2n-1 with new C1C2n signal value and previous C1C2n-1 signal value size relatively? if C1C2n less than C1C2n-1, then enters step S 6, if C1C2n greater than C1C2n-1, then enters step S7.

Step S6: during less than C1C2n-1, then increasing direction is correct convergence direction at C1C2n, keeps the default direction of former variable, and promptly the direction of Zeng Jiaing enters step S8 then.

Step S7:, then increase direction and be wrong convergence direction during greater than C1C2n-1 at C1C2n, then change the default direction of variable, promptly the direction of Jian Shaoing enters next step S8 then.

Is step S8: row checked C1C2n＞desired value C1C2T again? check promptly whether in the reasonable scope adjusted C1C2n, as C1C2n＞C1C2T, the mistake of then representing C1C2n is too much, the position that focuses on balance is still bad, need further to adjust again the position that focuses on balance, then be back to step S3, continue set-up procedure.If C1C2n is less than desired value C1C2T, just adjusted C1C2n, its errors number is then kept the position of existing focusing balance in acceptable zone of reasonableness, and enters next step.

Step S9: after adjusting the focusing equilibrium position, C1C2n signal value one is got back to below the desired value C1C2T, finishes set-up procedure immediately.

Therefore, the present invention can utilize the signal processing unit in the modulating unit to convert digital signal to the radiofrequency signal RF of read head output, again the mark of reading with differentiation of debug unit and correction.And utilize in the debug process, the C1C2 signal generator produces the C1C2 signal of representing error rate, by focusing on the C1C2 signal value that balance calculation unit calculation produces relatively relatively, check the convergent direction and the speed that focus on the equilibrium position, decision adjustment focuses on the amount of balance, transfer to compensator, cooperate focus error signal FE to form focus control signal, with focusing servo unit control read head, reach suitable focusing equilibrium position fast, produce to reduce mistake by the whole C1C2 of reduction of one group mark signal value, to save the running time of debug unit debug.Make the digital signal of the smooth decode modulated of decoding unit, promote the overall efficiency of CD-ROM drive for output.

The aforementioned adjustment of the present invention focuses on the embodiment of balance method, though as an illustration with the variable Δ FB that preestablishes direction that the position convergent direction that focuses on balance is increases and the focusing balance of fixing, set the direction of position convergent direction that focuses on balance for reducing, or with the variable Δ FB of revocable focusing balance, also can realize purpose of the present invention, and not take off technology category of the present invention.

The above person, only be that scope of the present invention is not limited to described preferred embodiment, all any changes of doing according to claim of the present invention in order to convenient explanation preferred embodiment of the present invention, under the premise of without departing from the spirit of the present invention, the scope that all belongs to claim of the present invention.

Claims (11)

1. method for balancing and adjusting CD ROM focus, its step comprises:

(1) reference value that makes zero;

(2) adjust the variable Δ FB that focuses on the equilibrium position, produce new C1C2 signal;

(3) whether check new C1C2 signal value＞C1C2T desired value? if new C1C2 signal value then is back to step (2) greater than C1C2T signal target value, if otherwise new C1C2 signal value smaller or equal to the C1C2T desired value, then enter next step; And

(4) finish to adjust.

2. according to the described method for balancing and adjusting CD ROM focus of claim 1, wherein to preestablish C1C2 signal target value be C1C2T to this CD-ROM drive.

3. according to the described method for balancing and adjusting CD ROM focus of claim 1, wherein the reference value that makes zero of this step (1) is for focusing on equilibrium position reference value FB=0.

4. according to the described method for balancing and adjusting CD ROM focus of claim 1, further comprise step after wherein this step (1) is finished:

(1a) whether check C1C2 signal value＞C1C2T desired value? if the C1C2 signal value, then enters step (4) smaller or equal to the C1C2T desired value, if the C1C2 signal value greater than C1C2T signal target value, then enters step (2).

5. according to the described method for balancing and adjusting CD ROM focus of claim 1, wherein this CD-ROM drive preestablishes and adjusts variable Δ FB and the direction that focuses on the equilibrium position.

6. according to the described method for balancing and adjusting CD ROM focus of claim 5, wherein the each variable Δ FB that changes in this step (2) adjustment focusing equilibrium position is a scheduled volume.

7. according to the described method for balancing and adjusting CD ROM focus of claim 6, wherein further comprise step after this step (2):

(2a) is newer C1C2 signal value greater than previous C1C2 signal value? if new C1C2 signal value is greater than previous C1C2 signal value, then change the direction of variable Δ FB, and enter step (3), if otherwise newly the C1C2 signal value is smaller or equal to previous C1C2 signal value, the direction of then keeping former variable Δ FB enters step (3).

8. according to the described method for balancing and adjusting CD ROM focus of claim 7, wherein the direction setting of this variable Δ FB is the direction of increase.

9. according to the described method for balancing and adjusting CD ROM focus of claim 7, wherein the direction setting of this variable Δ FB is the direction of minimizing.

10. according to the described method for balancing and adjusting CD ROM focus of claim 7, wherein this variable Δ FB is a revocable scheduled volume.

11. according to the described method for balancing and adjusting CD ROM focus of claim 7, wherein this variable Δ FB is a fixing scheduled volume.

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