CN1737911A

CN1737911A - Feedback correction method and system for CD-ROM drive

Info

Publication number: CN1737911A
Application number: CN 200410064107
Authority: CN
Inventors: 郑新平
Original assignee: Lite On IT Corp
Current assignee: Lite On IT Corp
Priority date: 2004-08-19
Filing date: 2004-08-19
Publication date: 2006-02-22
Anticipated expiration: 2024-08-19
Also published as: CN100498938C

Abstract

This invention relates to driver granting correction method and system method, wihc comprises the following steps: a, optical head generating one RF signals; converter coupling the RF signals to generate one digital signal to convert analogue signal into digital signal; detector receives the digital signals to generate multiple pseudo jitter as value of digital signal over zero bit; the computer receives multiple pseudo jitter to use the computation one granting signal to optical head.

Description

The feedback correction method of CD-ROM drive and system

Technical field

The invention relates to a kind of feedback correction method and system of CD-ROM drive, particularly utilize the method that shake (pseudo jitter) generation back coupling is proofreaied and correct of intending.

Background technology

In traditional CD-ROM system, utilize dither signal (jitter) to differentiate the quality of CD-ROM system operation usually.The optical system of optical read head is the key factor of decision amount of jitter number.In other words, if the design of Optical System of optical read head is bad, amount of jitter is just high.So general CD-ROM drive can be feedback dither signal to optical read head, to proofread and correct the error of its optical system.With blue light (blue-ray) CD-ROM drive is example, in order to compensate disc uneven thickness or spherical aberration that dual layer disc produced, generally uses dither signal and produces feedback signal, with the compensation mistake that spherical aberration was produced.

Fig. 1 is existing CD-ROM drive back coupling corrective system, and in order to reading radio frequency signal, wave filter 102 is in order to do pre-process to radiofrequency signal as optical read head 101.Analog-digital converter (Analogto Digital Converter:ADC) the 103rd is a digital signal with radiofrequency signal sampling (sample).Its output after balanced device 104 compensation such as grade of this digital signal is divided into two paths (path).The one, export a phase-locked loop (phase lock loop:PLL) 109 to, also feedback to analog-digital converter 103 and balanced device 104, the sequential when providing processing digital signal by this this phase-locked loop; Another outgoing route of balanced device 104 then is to export digital analog converter 105 in order to convert digital signal to simulating signal, does signal post-processing input jiffer measurer (jitter meter) 108 again through low-pass filter (low pass filter) 106 and cutter (slicer) 107 again.Shake measurer 108 is the signal of comparison cutter 107 and the sequential that phase-locked loop 109 is produced, by shaking to detect.Because being still with simulated mode, the measurement of shake measures, so just signal need be done complicated as mentioned above processing to measure to such an extent that shake.The jitter value that measures then feedback to optical read head to control its focal zone.

The measurement of shake as shown in Figure 2.0 rank of axle 303 and 304 expressions.When on behalf of an amount of jitter, waveform 301 be zero from the viewed signal waveform of A point, waveform 302 representatives when amount of jitter is non-vanishing from the A point measure signal waveform.Relatively waveform 301 and waveform 302 can find a little 3011 and put 3021 a phase differential 305 is arranged, and this phase differential 305 promptly are defined as shake (jitter), and in other words Dou Dong measurement must be by just being learnt by simulating signal.And existing shake measurer converts this phase differential to magnitude of voltage, feedback to optical read head with control optical read head read the zone.

Therefore in existing technology, the generation of feedback signal still can't produce with digital form.And repeatedly conversion between numeral and the simulating signal also causes the degree of difficulty of signal reduction, and is easy to generate signal delay and distortion.Making for system has also increased difficulty relatively.

Blu-ray drives is in order to compensate disc uneven thickness or spherical aberration that dual layer disc produced, can adopt dither signal to proofread and correct optical system in its optical read/write head as feedbacking usually.Right if directly adopt the back coupling circuit of above-mentioned complexity like this, may have the problem that integration is gone up and cost heightens and produce.

Summary of the invention

Because in the foregoing invention background, handle existing can't be to the problem of total system effective digital, provide in this inventive method and to intend shake (pseudo jitter) and produce feedback signal, one of its purpose be to solve existing can't digitized problem.

The objective of the invention is provides a kind of method and system that produces feedback signal in order to reduce the cost of manufacture of CD-ROM drive, gives up the measurement method of existing jitter simulation formula, utilizes simple detection signal position jump apart from big or small as shake, can be directly as feedback signal.

For being provided, CD-ROM drive when using beam expander, can obtain feedback signal, provide a kind of CD-ROM drive to produce the method and system of feedback signal in this, with rf digital signal through the processing such as gradeization, adjust the rank, position after, then can utilize the position jump that departs from foundation as feedback signal.

According to above-mentioned purpose, the invention provides a kind of back coupling corrective system and method for CD-ROM drive: optical read head (pickup head) produces a radiofrequency signal (RF signals); Converter this radiofrequency signal that is coupled produces a digital signal, and wherein converter becomes digital signal with analog signal conversion; Detecting device (detector) receives this digital radio signal and produces a plurality of plan shakes (pseudojitter), the value on range zero rank when wherein a plurality of plans are dithered as these digital signal leap zero-bit rank; And counter utilizes computing to produce a feedback signal and gives optical read head for receiving a plurality of plan shakes.

Description of drawings

Fig. 1 is the back coupling corrective system configuration diagram of existing CD-ROM drive;

Fig. 2 is the measurement synoptic diagram of existing shake;

Fig. 3 is the back coupling corrective system synoptic diagram according to a CD-ROM drive of the present invention; And

Fig. 4 intends shake according to of the present invention one to measure synoptic diagram.

Embodiment

Next be detailed description of the present invention, in the following explanation description of the feedback correction method of CD-ROM drive and system do not comprised the complete description of detailed composition and operation principles.The existing skill that the present invention continued to use is only done quoting of emphasis formula at this, to help elaboration of the present invention.And hereinafter relevant diagram also draws according to actual ratio, and its effect is only giving expression to feature of the present invention.

Optical read head in the back coupling corrective system of CD-ROM drive and the method (pickup head) produces a radiofrequency signal (RF signals).Converter is coupled this radiofrequency signal to produce a digital signal, and wherein converter becomes the conversion of signals of simulation the signal of numeral.Detecting device (detector) receives this digital radio signal and produces a plurality of plan shakes (pseudo jitter), and a plurality of plan is shaken the value on range zero rank when can be these digital signal leap zero-bit rank.Counter utilizes computing to produce a feedback signal and gives optical read head for receiving a plurality of plan shakes.

Consult Fig. 3 and be according to a CD-ROM drive of one embodiment of the invention and feedback the corrective system block schematic diagram.One optical read head 401, it is launched on the optical disc in a laser beam to a rotation and receives and output one radiofrequency signal.In an embodiment, laser beam is a blue laser beam, and it is adjustable haircuts out the laser of different capacity size to read or write the data on the optical disc.Secondly, the sphere that is caused because of the disc thickness inequality for compensation differs, optical read head 401 is to comprise a beam expander (beam expander), the size that beam expander its role is to adjust laser beam is to meet the required luminous point size of CD-ROM drive (as have two layers because of recording layer when reading dual layer disc, if having no idea to adjust the recording layer of laser spot sizes with the different focal positions of read/write without beam expander).It also receives feedback signal by to adjust laser spot sizes to eliminate situations such as sphere differs.

Wave filter 402 receives above-mentioned radiofrequency signal and it is carried out the processing that filtering noise and simulation etc. are changed.Be not limited to above-mentioned ground, wave filter 402 more comprises the function that radiofrequency signal is amplified, and for example comprises a prime amplifier (preamplifier).In an embodiment, it is not noise in the frequency of operation with filtering that wave filter 402 comprises a preposition low-pass filter (Pre-LPF) and Hi-pass filter (HPF).Analog-digital converter 403 will change a digital signal into through the radiofrequency signal of wave filter 402 filtrations.Digital equalizer 405 is in order to this digital signal such as compensation such as gradeization.In an embodiment, digital equalizer 405 can use a restriction balanced device (limit equalizer), the restriction balanced device is in order to limit the amplitude of this digital signal, make it must pass through the zero-bit rank, can promote the signal noise ratio (SNR) of this digital signal thus, help follow-up signal Processing.Be not limited to above-mentioned ground at this, digital equalizer 405 no doubt is used to improve signal, gets final product yet only need that in the present invention digital signal is adjusted to accurate position, zero-bit rank.

Afterwards, its output after digital equalizer 405 compensation such as grade of this digital signal is divided into two paths (path).The one, export a phase-locked loop (phase lock loop:PLL) 404 to, also feedback to analog-digital converter 403 and digital equalizer 405, the sequential when providing processing digital signal by this this phase-locked loop; Another outgoing route of digital equalizer 405 then is a detecting device 406.It detects the rank, position of this digital signal and the gap between the zero-bit rank is used as the plan shake size of one in the present embodiment (pseudo jitter).Because detected plan shake size is a jump distance, therefore promptly can be used as feedback signal as long as see through simple processing.In this embodiment, promptly utilizing average computation device 407 will intend the shake size carries out obtaining a mean value behind the simple operation, root-mean-square valve for example, arithmetic mean value etc., again this mean value is considered as a feedback signal feedback to optical read head 401 to adjust the usefulness of beam expanders as optical read head 401.

Fig. 4 is the plan shake in order to obtain in explanation one embodiment of the invention.Axle 51 is expression one zero-bit rank.One radiofrequency signal is a digital signal behind analog digital conversion and balanced device, for example puts 501,502,503,504,505,506.Be under zero the situation, can get signal point 501,502,503,504,505,506 as shown in FIG. in amount of jitter, its rank are respectively 0,2,2,0, and-2 ,-2.But because of the disc thickness inequality, can cause sphere to differ in the practical operation, or because of other factors such as thermonoise etc. when non-vanishing (be amount of jitter), just can produce the situation of deviation point 5041.Making the former point 504 that should be positioned at the zero-bit rank but in fact come across a little 5041 a component level that departs from puts.In present embodiment, detecting device detects the difference between deviation point 5041 and the point 5041, promptly becomes a jump 52 after taking absolute value, and is the size of the plan shake of gained in the present embodiment.

Here be noted that because spherical aberration effect or other effect cause signal can't pass through the zero-bit rank, and the position jump between this is the plan shake.Here be noted that also that intending shake becomes symmetry to the zero-bit rank usually.During as the signal quality difference, intending shake can be very big, relative, and when signal quality was good, intending shake can be very little.So using and intending shake is feasible as a feedback signal, and this system architecture does not need to convert switched digital signal to simulating signal once more.Cost in quality that just promotes product on the industry applications greatly and reduction making.

The above is preferred embodiment of the present invention only, is not in order to limit claim of the present invention; All other do not break away from the equivalence of being finished under the disclosed spirit and changes or modification, all should be included in the following claim.

Claims

1. a CD-ROM drive produces the method for feedback signal, it is characterized in that comprising:

Receive a radiofrequency signal;

This radiofrequency signal of digitizing is to produce a digital signal;

Adjust this digital signal, be adjusted to pre-determined bit rank from raw bits rank of this digital signal;

Detect a plurality of plan shakes of this digital signal after adjusting; And

Produce a feedback signal, this feedback signal is based on these a plurality of plan shakes and produces.

2. CD-ROM drive as claimed in claim 1 produces the method for feedback signal, it is characterized in that: described this digitization step is the sequential sampling that is produced according to a phase-locked loop.

3. CD-ROM drive as claimed in claim 1 produces the method for feedback signal, it is characterized in that: described this set-up procedure comprises and waits this digital signal of change.

4. CD-ROM drive as claimed in claim 1 produces the method for feedback signal, it is characterized in that: described should plans the shake is the distance on this digital signal of calculating and these pre-determined bit rank when crossing over these pre-determined bit rank.

5. CD-ROM drive as claimed in claim 1 produces the method for feedback signal, it is characterized in that: described this generation step comprises the root-mean-square valve of calculating these a plurality of plan shakes.

6. CD-ROM drive as claimed in claim 1 produces the method for feedback signal, it is characterized in that: described this generation step comprises the arithmetic mean value of calculating these a plurality of plan shakes.

7. the back coupling corrective system of a CD-ROM drive is characterized in that comprising:

One optical read head produces a radiofrequency signal;

One converter this radiofrequency signal that is coupled produces a digital signal, and wherein this converter becomes digital signal with analog signal conversion;

One detecting device receives this digital signal and produces a plurality of plan shakes; And

One counter produces a feedback signal to control this optical read head for receiving this a plurality of plan shakes with a computing.

8. the back coupling corrective system of CD-ROM drive as claimed in claim 7 is characterized in that: described this optical read head use blue laser beam.

9. the back coupling corrective system of CD-ROM drive as claimed in claim 7, it is characterized in that: described this converter is an analog-digital converter and a digital equalizer.

10. the back coupling corrective system of CD-ROM drive as claimed in claim 9 is characterized in that: described this analog-digital converter and this digital equalizer have digital phase locked loop control.

11. the back coupling corrective system of CD-ROM drive as claimed in claim 9 is characterized in that: described this digital equalizer is a restriction balanced device.

12. the back coupling corrective system as the 7th described CD-ROM drive of claim is characterized in that: the described beam expander (beam expander) that more comprises is accepted this feedback signal to control this optical read head.

13. the back coupling corrective system as the 7th described CD-ROM drive of claim is characterized in that: the distance of distance zero when described these a plurality of plans are dithered as these digital signal leap zero-bit rank.