CN100380490C

CN100380490C - Method for identifying CD

Info

Publication number: CN100380490C
Application number: CNB2005100751586A
Authority: CN
Inventors: 陈志豪
Original assignee: Via Technologies Inc
Current assignee: Via Technologies Inc
Priority date: 2005-06-08
Filing date: 2005-06-08
Publication date: 2008-04-09
Anticipated expiration: 2025-06-08
Also published as: CN1719535A

Abstract

The present invention relates to a CD identification method which is used for distinguishing the kind of a source CD in the traveling period of an optical read head. Firstly, the detection is carried out in order to obtain a first RF quasi position signal, wherein the peak value of the first RF quasi position signal is bigger than a first threshold value. Then, in scheduled time from the time when the first RF quasi position signal is obtained, the peak value of a second RF quasi position signal bigger than a second threshold value is detected, and otherwise, between the scheduled time and the traveling period of the optical read head, the peak value of the second RF quasi position signal bigger than a third threshold value is detected. In addition, if the peak value of the second RF quasi position signal greater than the third threshold value is not detected, the source CD is a single layer sheet. Hereby, a CD player can correctly identify whether the source CD belongs to one of a single layer sheet, a DVD double layer sheet and an SACD double layer sheet, and then the correct content of the CD is read.

Description

CD identification method

Technical field

The present invention relates to a kind of CD identification and double-layer CD sheet method of discrimination, particularly relate to a kind of according to the accurate position of RF signal (signal is signal, below all be called signal) to differentiate the CD identification and the double-layer CD sheet method of discrimination of CD-RW discsCD-RW kind.

Background technology

Along with the continuous lifting of Information of Science and Technology level, various Storage Medias obtain exploitation in succession, in the hope of more suiting numerous consuming public's user demand.The visible Storage Media in market is CD-RW discsCD-RW (Compact Disk at present; CD), it is the Storage Media that utilizes luminous energy to keep a record and read, have high record density (capacity is big), noise is little, the life-span is long, volume is little, easy to carry, can substitute arbitrarily, advantage such as cost is low and can not be subjected to that surface dirt influences when reading, its usable range is quite extensive, the scope that can write down and read comprises literal, figure, image, sound, video signal and animation etc., not only become the people's livelihood consumer goods of music, film, recreation, more become the topmost Storage Media of computing information today.Generally speaking, existing Storage Media product can generally be divided into three types according to its record different with read functions:

1. read-only type (Read Only) CD-RW discsCD-RW is as laser disc CD Audio, compact disk read only memory sheet CD-ROM, video CDs (CD Video), digital audio-video CD-RW discsCD-RW DVD-Video, digital CD-RW discsCD-RW DVD-ROM.

2. writable disposable type (Write Once And Read Only) or claim recordable type (Recordable) is as CD-R (can write down the dispensable mould CD-RW discsCD-RW).

3. rewritable type (Rewritable) or claim erasable type (Erasable) is as MO (magneto-optic video disc), MD (miniature light video disc), PD (phase change CD-RW discsCD-RW), CD-RW (rewritable type CD-RW discsCD-RW DVD-RAM (digital rewritable type CD-RW discsCD-RW).

Wherein, read-only type CD-RW discsCD-RW is mainly used in and makes audio compact disc, video disc etc.; Writable disposable type CD-RW discsCD-RW only can be once write activity, do not possess the erasable function, mainly be applicable to the data that record needs long preservation can not be disappeared again to fall (data is data, below all be called data), as the foundation of secretarial document, Graphic Documentation, medical history information etc.; Rewritable type CD-RW discsCD-RW then possesses the function that can repeatedly write down, read with wiping.After occurring digital audio-video laser disc product DVD of new generation in recent years, because more traditional CD-RW discsCD-RW has many advantages, for example because the memory capacity of DVD is seven times of compact disk read only memory sheet at least, can reach 20 times at the most, therefore capacity is bigger, and the audio-visual quality of DVD CD-RW discsCD-RW is excellent, its horizontal resolution is (the video recording analysis ability far surpasses VCD) up to 500, captions show 32 kinds, number of channels reaches eight and (can hold multi-lingual, multinational captions) etc., showing that all DVD is better than original CD product, expecting that generally interior DVD CD-RW discsCD-RW of several years will definitely become the main flow commodity in laser disc market gradually.

In addition, a kind of SACD of being called (Super Audio Compact Disc) and to be known as be the Storage Media of " super CD " is after the invention of CD, successfully surmounts the new product and the music video disc new spec of CD recording quality.The sampling frequency of SACD is up to 2822.4MHz, it is 64 times that general CD 44.1KHz takes a sample, and therefore the SACD frequency range also makes SACD improve original CD music and gives the chill stereotype of people, and present with finer and smoother, more details, more soft sound especially up to more than the 100KHz.Further, the record type of SACD is to record with DSD recording technology (DirectStream Digital) mode, the PCM record type of forgoing traditional, with the high sampling mode of all signals with 2.8224MHz (being 64 times that CD 44.1kHz takes a sample), that is per second 2,800,000 sub-samplings, with 0 and 1 continuous quantization, can listen the dynamic range of frequency domain to be about 120dB, may include the about 1000kHz of frequency domain, with the mode changing pulse digital signal directly analogy music signal waveform, just so-called " directly bit element flow numeral " (bit is the position, below all be called bit) is because store music with the space that is four times in CD nearly, therefore can provide more outstanding sound effect, add sampling number of times height, so the waveform of taking a sample is very round suitable, very near original analogy waveform.

In addition, SACD is not owing to adopt multidigit unit, so can save the bit transitions program, issuable distortion and noise have been reduced because of digital filtering, and be subjected to the influence of power supply or external disturbance owing to easy as multidigit metasystem (bit is healed the higher position more easily), therefore quality can be more stable in theory, and SACD also can hold multichannel and image, the tonequality of SACD multichannel has comprised 6 independently tracks, each track can be read and not pass through any compression and complete DSD specification (Full DSD Bit Rate), with respect to general DVD, because through overcompression, so only can hear the tonequality of 96K/24Bit.Because the location of SACD self and 1bit quantize the succinct and advantage of DSD direct data flow process at technical elements, therefore the salty SACD of recognizing has preferable tonequality.

On the other hand, the data access technology of CD-ROM device also promotes along with the Storage Media variation, and its primary structure comprises to be responsible for stablizing rotating mechanism, the control circuit of controlling this optical read/write head and signal processing circuit of rotation or the like by reading on the CD-RW discsCD-RW with the optical read/write head of tracer signal, mobile this optical read/write head to driving mechanism, the maintenance CD-RW discsCD-RW of ad-hoc location.Wherein, optical read/write head is the key part and component of CD-ROM device, it is formed subsystem and comprises the optical system of being made up of LASER Light Source, collimation lens, collecting objective, cylindrical lens, OPTICAL SENSORS (or claiming optical receiver) etc., the focusing of being made up of Liar group, elastic support and power and mechanical energy transducer follows rail system (or being categorized as mechanical drive system), and the electromagnetic driving system of being made up of focus servo, rail searching servo, circulation orbital servo and Spindle Motor control etc. (or being categorized as servo-control system).One carry at this, because factors such as rotation and exterior vibration can influence the mechanical precision of CD-ROM device, the trajectory generation that causes laser light up and down with about skew or rotation rock, so CD-ROM device needs respectively to focus on and follows the rail action to drive laser spot accurately in alignment with CD-RW discsCD-RW groove (pit and land).

At present several focusing and modification methods that comparatively extensively adopt, comprise method of astigmatism (astigmatic), critical angle method (critical angel), right spot method (spot size), cutter lot or luck by which people are brought together (knife edge) and Fu Kefa (foucault) etc., be by comparing in positive burnt, near burnt focusing result burnt and far away in the formed reception difference of OPTICAL SENSORS, to obtain focus error signal (focusing errorsignal; FES), feedback by this and produce voltage and go to drive focus actuator (focus actuator) and revise focusing accuracy, and then provide servo-control system to adjust luminous point, wherein because near nearly Jiao that object lens are caused when moving up and down focus point will make focus error signal produce the positive and negative variation of amplitude with Jiao far away, so this focus error signal curve of a S shape normally; The rail that follows commonly used then comprises i-beam push-pull method (single beam), three-beam method (three beam) and dithering (wobble) etc. with modification method, be respectively by the received light intensity difference of OPTICAL SENSORS of relatively using sensitization in four fens with six fens sensitization, to obtain tracking error signal (tracking errorsignal; TES), as following the foundation of rail correction, wherein this tracking error signal also has the sigmoid curve that is similar to this focus error signal, produces voltage with back coupling and goes driving actuator by this.

From the above, with the method for astigmatism is example, focus error signal and RF signal (radio frequencysignal) are in wave form varies that OPTICAL SENSORS presented as shown in Figure 1, wherein the first half of Fig. 1 is the focus error signal value variation synoptic diagram of method of astigmatism, its rectangular coordinates transverse axis is represented the distance in object lens and CD-RW discsCD-RW reflection horizon, the longitudinal axis is represented the amplitude of focus error signal value, and focus error signal value waveform can be divided into nearly burnt zone 110, positive burnt zone 120 and burnt zone 130 far away, waveform segment in these zones is to represent nearly Jiao in regular turn, focus error signal value when positive Jiao is extremely far burnt changes, and positive focus 140 shows not have focusing error this moment, and positive burnt regional 120 width are that suitable CD-RW discsCD-RW data reads the scope on opportunity.On the other hand, the Lower Half of Fig. 1 is that the RF signal value of method of astigmatism changes synoptic diagram, and its rectangular coordinates transverse axis is represented the distance in object lens and CD-RW discsCD-RW reflection horizon, and the longitudinal axis is then represented the amplitude of RF signal value.One carry at this, the peak of RF accurate position signal (RF level signal) is the reflection strength that is defined as the RF signal to peak value (being the DC value), and the positive focus 140 of focus error signal is corresponding to RF signal peak 150 positions, meaning is that the RF signal reaches maximal value when correct focusing, and this RF signal amplitude is greater than a critical value 160.

Further, aforementioned each focus method all can produce focus error signal, and signal waveform all is similar sigmoid curve, when object lens arrive correct focal position, the focus error signal value is all zero, and in positive dirction and negative direction apart from correct focal position, each can produce the maximal value of a positive and negative focus error signal, promptly be respectively focus error signal peak value and valley, curve between two extreme values then is near linear, therefore can use linear control method to reach the job requirement of focus servosystem in this linear zone.On the practice, in the control loop design in this linear zone, the characteristic that can utilize focus error signal and RF signal usually is to judge whether correct focusing, and wherein the waveform of RF signal is a secondary parabolic curve under shed, that is sinusoidal wave positive half cycle.When optical read/write head makes that by the bottom is up mobile the RF signal is higher than a certain critical value, then expression focuses on the range of linearity that has entered the S curve, and the RF signal can reach maximal value when correct focusing, therefore can judge whether near the correct focusing that the focuses on zero cross-point FZC (focus zero crossing point) of representative, just aforesaid positive focus 140 by focus error signal and RF signal.

Because the Development Technology of CD-RW discsCD-RW and CD-ROM device is to present positive correlation, and the integration trend of all kinds of information products, therefore along with the significantly growth of numerous smooth stored prods with weed out the old and bring forth the new, the CD-ROM device with complex function that is used to read the video disc audiovisual materials is in the correct and quick interpretation of Storage Media kind, and the design of optical R/W signal control circuit and chip also needs superior day by day.So, develop a kind of mechanism satisfying the correct and demand of interpretation fast of aforesaid Storage Media kind, and provide CD-ROM device one smoothly the Storage Media data read flow process, real in needing one of research and development problem of processing badly.

This shows, in order to solve the above problems, relevant manufacturer there's no one who doesn't or isn't seeks solution painstakingly, but does not see always that for a long time suitable design finished by development, and not having appropriate method to address the above problem in the conventional method, this obviously is the problem that the anxious desire of relevant dealer solves.Therefore how to found a kind of new CD identification method, just become the current industry utmost point to need improved target.

The inventor is based on being engaged in this type of product design manufacturing abundant for many years practical experience and professional knowledge, and cooperates the utilization of scientific principle, actively studied innovation, in the hope of founding a kind of new CD identification method.Through constantly research, design, and after studying repeatedly and improving, create the present invention who has practical value finally.

Summary of the invention

A fundamental purpose of the present invention, be to provide a kind of double-layer CD sheet method of discrimination, be to be used to differentiate in the optical read head moving period pair of lamina CD-RW discsCD-RW kind, its step is at first to detect to obtain the accurate position of one the one RF signal, wherein the accurate position of this RF signal comprises one the one RF accurate position signal peak and one first threshold value, and the accurate position of this RF signal peak is greater than this first threshold value.Then, in obtaining the accurate position of RF signal in one schedule time, detect the accurate position of the 2nd a RF signal whether occurs,, use this kind of differentiation double-layer CD sheet and belong to a DVD double-layer CD sheet to obtain the accurate position of corresponding the 2nd RF signal peak greater than one second threshold value.If the accurate position of the 2nd RF signal peak that there is no in during this greater than this second threshold value occurs, before just then after the schedule time, finishing to optical read head moving period during this period of time in the middle of, whether detecting has the accurate position of this 2nd RF signal peak greater than one the 3rd threshold value to occur, and uses this kind of differentiation double-layer CD sheet and belongs to a SACD CD-RW discsCD-RW.Therefore, if in order to read the content of SACD CD-RW discsCD-RW, CD-ROM device can be by double-layer CD sheet method of discrimination of the present invention, correctly and fast differentiating this double-layer CD sheet kind in optical read head moving period is a SACD CD-RW discsCD-RW, a but not DVD double-layer tablet, then LASER Light Source is focused on the CD layer correctly to read data, the Storage Media data reads flow process to carry out smoothly.

A syllabus of the present invention, be to provide a kind of CD identification method, be to be used to differentiate in the optical read head moving period CD-RW discsCD-RW kind, its step is at first to detect to obtain the accurate position of one the one RF signal, wherein the accurate position of this RF signal comprises one the one RF accurate position signal peak and one first threshold value, and the accurate position of this RF signal peak is greater than this first threshold value.Then, in obtaining the accurate position of RF signal in one schedule time, detect the accurate position of the 2nd a RF signal whether occurs,, use this kind of differentiation double-layer CD sheet and belong to a DVD double-layer CD sheet to obtain the accurate position of corresponding the 2nd RF signal peak greater than one second threshold value.If the accurate position of the 2nd RF signal peak that there is no in during this greater than this second threshold value occurs, before just then after the schedule time, finishing to optical read head moving period during this period of time in the middle of, whether detecting has the accurate position of this 2nd RF signal peak greater than one the 3rd threshold value to occur, and uses this kind of differentiation double-layer CD sheet and belongs to a SACD CD-RW discsCD-RW.At last, as if the accurate position of the 2nd RF signal peak that does not record all the time in this optical read head moving period greater than this 3rd threshold value, CD-ROM device just judges that this CD-RW discsCD-RW kind belongs to a single-layer sheet.Therefore, CD-ROM device can be by CD identification method of the present invention, correctly and fast determines kind under the CD-RW discsCD-RW of source in optical read head moving period, correctly reads data in focusing on following after the rail relative program carries out then.

Reach advantage in order to achieve the above object, double-layer CD sheet method of discrimination of the present invention and CD identification method, be according to the accurate position of RF signal peak size and the kind of opportunity occur in an optical read head moving period with decision source CD-RW discsCD-RW, correctly read the CD-RW discsCD-RW inside information for pick-up head for optical disk player, therefore whether really put into CD-ROM device for read if can differentiate CD-RW discsCD-RW fast, and correctly the kind of interpretation source CD-RW discsCD-RW is to belong to the DVD double-layer tablet, SACD CD-RW discsCD-RW or single-layer sheet one of them, correctly read the CD-RW discsCD-RW content for CD-ROM device and optical read head to relevant position.

The present invention compared with prior art has tangible advantage and beneficial effect.Via as can be known above-mentioned, the invention relates to a kind of CD identification method, it is the kind that is used to differentiate in the optical read head moving period source CD-RW discsCD-RW, its step is that detecting earlier is to obtain the accurate position of one the one RF signal, wherein the accurate position of the RF signal peak of the accurate position of this RF signal is greater than one first threshold value, detect the accurate position of the 2nd RF signal peak in one schedule time in obtaining the accurate position of this RF signal then greater than the accurate position of one the 2nd RF signal of second threshold value, otherwise in after the schedule time to the accurate signal peak of this 2nd RF of detecting between the optical read head moving period greater than the 3rd threshold value.In addition, as if the accurate position of the 2nd RF signal peak that does not record greater than the 3rd threshold value, the CD-RW discsCD-RW of then originating is a single-layer sheet.By this, but this source CD-RW discsCD-RW of CD-ROM device correct decision be belong to a single-layer sheet, a DVD double-layer tablet and a SACD double-layer tablet one of them, read out correct CD-RW discsCD-RW content then.

In sum, the CD identification method that the present invention is special has above-mentioned many advantages and practical value, and in class methods, do not see have similar design to publish or use and really genus innovation, no matter it is all having bigger improvement on method or on the function, have large improvement technically, and produced handy and practical effect, thereby be suitable for practicality more, and have the extensive value of industry, really be a new and innovative, progressive, practical new design.

Above-mentioned explanation only is the general introduction of technical solution of the present invention, for can clearer understanding technological means of the present invention, and can be implemented according to the content of instructions, and for above-mentioned and other purposes, feature and advantage of the present invention can be become apparent, below especially exemplified by preferred embodiment, and conjunction with figs., be described in detail as follows.

Description of drawings

Fig. 1 changes synoptic diagram for focus error signal value and RF signal value according to known method of astigmatism;

Fig. 2 is the flow chart of steps for the double-layer CD sheet method of discrimination of foundation a preferred embodiment of the present invention;

Fig. 3 is the method for astigmatism focusing and OPTICAL SENSORS synoptic diagram for one preferred embodiment of foundation known techniques;

Fig. 4 is the flow chart of steps for the CD identification method of foundation a preferred embodiment of the present invention; And

Fig. 5 is the synoptic diagram for accurate position signal of RF in the optical read head moving period of foundation a preferred embodiment of the present invention and threshold value waveform.

120 positive burnt zones, 110 nearly burnt zones

130 burnt zones far away, 140 positive focuses

150RF signal peak 160 critical values

300 CD-RW discsCD-RW, 310 object lens

320 cylindrical lenss

330,330a, 330b, four fens OPTICAL SENSORS of 330c

331,332,333,334 optical diodes

510 optical read head motion tracks, 511 optical read head position low spots

The accurate position of high point 520 the one RF, 512 optical read head positions signal

The accurate position of 521 the one RF signal peak 522 first threshold values

The accurate position of 530 schedule times 540,560 the 2nd RF signal

541, the accurate position of 561 the 2nd RF signal peak

542 second threshold values

562 the 3rd threshold values

Embodiment

Reach technological means and the effect that predetermined goal of the invention is taked for further setting forth the present invention, below in conjunction with accompanying drawing and preferred embodiment, to its embodiment of CD identification method, method, step, feature and the effect thereof that foundation the present invention proposes, describe in detail as after.

The invention relates to time of occurrence and the CD identification method of size with differentiation CD-RW discsCD-RW kind according to the accurate position of RF signal.See also shown in Figure 2ly, it is double-layer CD sheet method of discrimination of the present invention one preferred embodiment.In this embodiment, the flow process of this double-layer CD sheet method of discrimination comprises following steps: at first, in step S200 the position of one optical read head is moved from low to high, the omnidistance temporal summation that is spent is an optical read head moving period, then detect to obtain the accurate position of one the one RF signal RFLVL 1 in step S220, wherein the RF standard position signal peak RFLVL 1_Peak of the accurate position of this RF signal RFLVL 1 is greater than the first threshold value RFLVL 1_Thr1.Carry out step S240 then, whether detecting occurs greater than the accurate position of one the 2nd RF signal peak RFLVL 2_Peak of one the 2nd RF signal RFLVL 2 of one second threshold value RFLVL 2_thr_2 in obtaining the accurate position of RF signal RFLVL 1 one schedule time T0, so can differentiate this kind double-layer CD sheet and belong to a DVD double-layer CD sheet.If the accurate position of the 2nd RF signal peak RFLVL 2_Peak that there is no in during this greater than this second threshold value RFLVL 2_thr_2 occurs, just then carry out step S260, before behind schedule time T0, finishing to optical read head moving period during this period of time in the middle of, whether detecting has the accurate position of this 2nd RF signal peak RFLVL 2_Peak greater than one the 3rd threshold value RFLVL 3_thr_3 to occur, and so is that this kind of decidable double-layer CD sheet belongs to a SACD CD-RW discsCD-RW.

One carry at this, the purpose that focuses on is in order to the distance between monitoring CD-RW discsCD-RW and the object lens, to keep the correct focal length that reads, and in order to further specify flesh and blood and the constituted mode of the accurate position of RF signal RFLVL in the preferred embodiment of the present invention, enumerate and narrate the account form of the method for astigmatism type of focusing commonly used and RF signal and focus error signal value at this, with as according to the accurate signal of RF of double-layer CD sheet method of discrimination of the present invention and CD identification method and the aid illustration of focus error signal value.Fig. 3 is the method for astigmatism focusing and OPTICAL SENSORS synoptic diagram for one preferred embodiment of foundation known techniques.Because method of astigmatism is to use object lens 310, one cylindrical lens 320 and one or four fens OPTICAL SENSORS 330, when changing, the distance of the object lens 310 of the reflection horizon of CD-RW discsCD-RW 300 and optical read head cause focal position not simultaneously, luminous point on this four fens OPTICAL SENSORS 330 presents difformity, the focus error signal value can be utilized formula F ES=(A+C)-(B+D) try to achieve, and the RF signal then can utilize formula RF=(A+B+C+D) to try to achieve, and the peak of the accurate position of RF signal RFLVL is the reflection strength of RF signal to peak value, optical diode A331 wherein, B332, C333 will produce the unlike signal value because receiving different intensities of reflected light respectively with D334, for example regional 110 the time when being positioned at nearly Jiao shown in Figure 1, because a little less than optical diode A331 and C333 are subjected to light, and optical diode B332 and D334 are subjected to light stronger, therefore result shown in four fens OPTICAL SENSORS 330a will produce the focus error signal of negative value.For example regional 120 the time again when being positioned at positive Jiao, because four optical diodes 331 to 334 are subjected to light intensity identical, make that resulting focus error signal is zero when correct focusing, result shown in four fens OPTICAL SENSORS 330b, and the accurate position of RF signal and RF signal reaches maximal value, and meaning promptly produces the accurate position of RF signal peak RFLVL_Peak.In addition, regional 130 the time when being positioned at Jiao far away, optical diode A331 and C333 are subjected to light stronger, and a little less than optical diode B332 and D334 be subjected to light, result shown in four fens OPTICAL SENSORS 330c, therefore produce on the occasion of focus error signal.Then, focus servosystem can with this focus error signal and RF signal as input, provide suitable compensation with compensating circuit again, focus on action and result to adjust.

See also shown in Figure 4ly, it is CD identification method one preferred embodiment of the present invention.In this embodiment, the flow process of this CD identification method comprises following steps: at first, in step S400 the position of one optical read head is moved from low to high, the omnidistance temporal summation that is spent is an optical read head moving period, then detect to obtain the accurate position of one the one RF signal RFLVL 1 in step S420, wherein the accurate position of this RF signal RFLVL 1 comprises one the one RF accurate position signal peak RFLVL1_Peak and one first threshold value RFLVL 1_Thr1 at least, and the accurate position of this RF signal peak RFLVL1_Peak is greater than this first threshold value RFLVL 1_Thr1.One carry at this, if in this optical read head moving period, do not record a RF accurate position signal RFLVL 1 of the accurate position of its RF signal peak RFLVL 1_Peak all the time greater than the first threshold value RFLVL 1_Thr1, then can be judged to be by CD-ROM device and not put into CD-RW discsCD-RW in step S490, and send mistake and subsequent alerts message, relevant and correct running program with the indication user.

Then, after completing steps S420, carry out step S440, whether detecting occurs greater than the accurate position of one the 2nd RF signal peak RFLVL 2_Peak of one the 2nd RF signal RFLVL 2 of one second threshold value RFLVL 2_thr_2 in obtaining the accurate position of RF signal RFLVL 1 one schedule time T0, so can differentiate this kind double-layer CD sheet and belong to a DVD double-layer CD sheet.If the accurate position of the 2nd RF signal peak RFLVL 2_Peak that there is no in during this greater than this second threshold value RFLVL 2_thr_2 occurs, just then carry out step S460, before behind schedule time T0, finishing to optical read head moving period during this period of time in the middle of, whether detecting has this 2nd RF signal peak RFLVL 2_Peak greater than one the 3rd threshold value RFLVL 3_thr_3 to occur, and so is that this kind of decidable double-layer CD sheet belongs to a SACD CD-RW discsCD-RW.At last, as if the accurate position of the 2nd RF signal peak RFLVL 2_Peak that does not record all the time in this optical read head moving period greater than this 3rd threshold value RFLVL 3_thr_3, then CD-ROM device just judges that in step S480 this CD-RW discsCD-RW kind belongs to a single-layer sheet.Finish in case the CD-RW discsCD-RW kind is judged, CD-ROM device just can be carried out the correct data fetch program according to the attribute of this CD-RW discsCD-RW.

In order to further specify the present invention and relevant preferred embodiment, see also shown in Figure 5ly, it is the synoptic diagram for RF accurate position signal and threshold value waveform in the optical read head of the present invention moving period.The oblique line that extends by lower-left to upper right side represent optical read head in optical read/write head moving period by the formed track 510 in low spot 511 lofty perches 512 shift positions, in this one-period, CD identification method one preferred embodiment according to Fig. 4, when the optical read head position when step S400 is moved by low spot 511 lofty perches 512, record the accurate position of one the one RF signal RFLVL 1 520 in step S420, its waveform as previously mentioned, it is the sinusoidal wave upper half parabolic curve that becomes that Open Side Down, wherein the accurate position of this RF signal RFLVL 1 520 comprises the accurate position of RF signal peak RFLVL 1_Peak 521 and one first threshold value RFLVL 1_T,hr1 522 at least, and the accurate position of this RF signal peak RFLVL 1_Peak521 amplitude is greater than this first threshold value RFLVL 1_T,hr1 522.Then, in step S440, whether detecting occurs greater than accurate signal peak RFLVL2_Peak 541 of one the 2nd RF of the accurate position of one the 2nd RF signal RFLVL 2 540 of one second threshold value RFLVL 2,_th,r_2 542 (its waveform also is the sinusoidal wave upper half parabolic curve that becomes that Open Side Down) in obtaining the accurate position of RF signal RFLVL 1 520 one schedule time T0 530, can differentiate this kind double-layer CD sheet and belongs to a DVD double-layer CD sheet as if occurring.If the accurate position of the 2nd RF signal peak RFLVL 2_Peak 541 that there is no in during this greater than this second threshold value RFLVL 2,_th,r_2 542 occurs, just then carry out step S460, height points 512 before schedule time T0 530 back to optical read head moving periods finish during this period of time in the middle of, whether detecting has the accurate position of the 2nd RF signal peak RFLVL 2_Peak 561 greater than the accurate position of this 2nd RF signal RFLVL2 560 of one the 3rd threshold value RFLVL 3,_th,r_3 562 to occur, if occur is that this kind of decidable double-layer CD sheet belongs to a SACD CD-RW discsCD-RW, at last, if do not record the accurate position of the 2nd RF signal peak RFLVL 2_Peak 561 greater than the accurate position of the 2nd RF signal RFLVL2 560 of this 3rd threshold value RFLVL 3,_th,r_3 562 all the time in this optical read head moving period, then CD-ROM device just judges that in step S480 this CD-RW discsCD-RW kind belongs to a single-layer sheet.Finish in case the CD-RW discsCD-RW kind is judged, CD-ROM device just can be carried out the correct data fetch program according to the attribute of this CD-RW discsCD-RW.

The above, it only is preferred embodiment of the present invention, be not that the present invention is done any pro forma restriction, though the present invention discloses as above with preferred embodiment, yet be not in order to limit the present invention, any those skilled in the art, in not breaking away from the technical solution of the present invention scope, when the method that can utilize above-mentioned announcement and technology contents are made a little change or be modified to the equivalent embodiment of equivalent variations, in every case be the content that does not break away from technical solution of the present invention, according to technical spirit of the present invention to any simple modification that above embodiment did, equivalent variations and modification all still belong in the scope of technical solution of the present invention.

Claims

1. a double-layer CD sheet method of discrimination is to be used to differentiate pair of lamina CD-RW discsCD-RW kind in the optical read head moving period, it is characterized in that it may further comprise the steps:

Detecting is to obtain the accurate position of one the one RF signal, and wherein the accurate position of RF signal comprises one the one RF accurate position signal peak and one first threshold value, and the accurate position of RF signal peak is greater than this first threshold value;

Detect the one two RF accurate position signal of its peak value greater than one second threshold value in one schedule time in obtaining the accurate position of RF signal, differentiating this double-layer CD sheet is a DVD double-layer CD sheet; And

In after this schedule time to its peak value of detecting between this optical read head moving period greater than the accurate position of the 2nd RF of one the 3rd threshold value signal, differentiating this double-layer CD sheet is a SACD CD-RW discsCD-RW.

2. a CD identification method is to be used to differentiate a CD-RW discsCD-RW kind in the optical read head moving period, it is characterized in that it may further comprise the steps:

Detecting is to obtain the accurate position of one the one RF signal, and wherein the accurate position of this RF signal comprises one the one RF accurate position signal peak and one first threshold value, and the accurate position of RF signal peak is greater than this first threshold value;

Detect the one two RF accurate position signal of its peak value greater than one second threshold value in one schedule time in obtaining the accurate position of RF signal, differentiating this CD-RW discsCD-RW kind is a DVD double-layer CD sheet; And

In after this schedule time to its peak value of detecting between this optical read head moving period greater than the accurate position of the 2nd RF of one the 3rd threshold value signal, differentiating this CD-RW discsCD-RW kind is a SACD CD-RW discsCD-RW.

3. CD identification method according to claim 2 is characterized in that wherein this CD-RW discsCD-RW kind is a single-layer sheet if do not record the accurate position of the 2nd RF signal of its peak value greater than the 3rd threshold value in this optical read head moving period.