CN101593527A - Optical head and CD drive - Google Patents

Abstract

The invention provides a kind of optical head and CD drive.Optical head according to the embodiment of the invention is configured to and can moves along the predetermined radial direction of the CD that is loaded into the pre-position, and comprises: first lens, and its first laser beam that is configured to be included in first wavelength coverage focuses on the CD; Second lens, its second laser beam that is configured to be included in second wavelength coverage focuses on the CD with the incoming laser beam that is included in the 3rd laser beam in the wavelength range, second wavelength coverage is shorter than first wavelength coverage, and wavelength range is shorter than second wavelength coverage; And the lens supports module, it is configured to first lens and second lens are supported so that they are on the orbital direction of CD and put; And this lens supports module with first lens supports on the shifting axle on the predetermined radial direction.

Description

Optical head and CD drive

Technical field

One embodiment of the present of invention relate to a kind of optical head that is used to utilize the different wavelength of laser bundle to handle and has different qualities the CD of (for example recording density etc.), and this optical head comprises two lens.One embodiment of the present of invention also relate to the CD drive that adopts this optical head.

Background technology

Nowadays, the CD of various standards is comparatively in vogue.Known just has: high-resolution DVD (HD DVD)/Blu-ray Disc (BD, Blu-ray Disc that the compact-disc that the laser beam of utilizing wavelength to be about 780nm is handled (CD), digital versatile disc (DVD) that the laser beam of utilizing wavelength to be about 650nm is handled and the laser beam of utilizing wavelength to be about 405nm are handled ^TM).

For the CD to these various standards is handled, Japanese Patent Application Publication No.2007-257777 has proposed a kind of CD drive that combines two lens.This CD drive that is proposed comprises the semiconductor laser that is used to launch the CD laser beam, be used to another semiconductor laser of launching another semiconductor laser of DVD laser beam and being used to launch HD DVD/BD laser beam, and this CD drive comprises that also one is used to make the CD laser beam to focus on CD to go up or make HD DVD/BD laser beam to focus on lens on the HD DVD and another to be used to make HD DVD/BD laser beam to focus on lens on the BD.

Yet, because the optical head of aforementioned lights disk drive combines two lens, so this CD drive has been subjected to the influence of lens position skew.To describe the situation of the universal optical head that has merged lens below, promptly the lens mount of optical head is supporting the situation of lens.Optical head (lens mount) can move on the predetermined radial direction of the CD that is loaded into the pre-position, and lens mount supports lens so that the center of the center of shifting axle and lens is complementary.So, on the shifting axle that is centered close to lens mount of the lens that lens mount supported.In other words, on the normal that is centered close to track (track) of lens.

But, when optical head combines two lens, that is, and when a lens mount is supporting two lens, if the center of certain lens is aligned to the position on the shifting axle of lens mount, the position on the shifting axle of the misalignment lens mount of another lens so.That is to say, the misalignment of another lens the position on the normal of track.For example, even want to adopt a kind of perfect differential push-pull (DPP) method of following the rail method that CD handles that is proved to be to be used for, this method also can be subjected to the influence of aforementioned lens skew.

Summary of the invention

An object of the present invention is to provide optical head and CD drive, when a lens mount supported a plurality of lens, described optical head and CD drive were not vulnerable to the influence of any lens position skew.

According to a first aspect of the invention, a kind of optical head is provided, it is configured to and can moves on the predetermined radial direction of the CD that is loaded into the pre-position, and it comprises: first light emitting module, and it is configured to give off first laser beam that is included in first wavelength coverage; Second light emitting module, it is configured to give off second laser beam that is included in second wavelength coverage, and described second wavelength coverage is shorter than described first wavelength coverage; The 3rd light emitting module, it is configured to give off the 3rd laser beam that is included in the wavelength range, and described wavelength range is shorter than described second wavelength coverage; First lens, it is configured to first laser beam is focused on the CD that is loaded into the pre-position; Second lens, it is configured to the incoming laser beam of second laser beam and the 3rd laser beam is focused on the CD that is loaded into the pre-position; The lens supports module, it is configured to first lens and second lens are supported so that they are on the orbital direction of the CD that is loaded into the pre-position and put; First detection module, it is configured to detect the reflected light of first laser beam from CD reflection; And second detection module, it is configured to detect one of second laser beam and the 3rd laser beam reflected light from CD reflection; Wherein, described lens supports module with first lens supports move along predetermined radial direction the axle on.

According to a second aspect of the invention, a kind of CD drive is provided, it comprises a kind of optical head, described optical head is configured to and can moves along the predetermined radial direction of the CD that is loaded into the pre-position, described CD drive comprises: first light emitting module, and it is configured to give off first laser beam that is included in first wavelength coverage; Second light emitting module, it is configured to give off second laser beam that is included in second wavelength coverage, and described second wavelength coverage is shorter than described first wavelength coverage; The 3rd light emitting module, it is configured to give off the 3rd laser beam that is included in the wavelength range, and described wavelength range is shorter than described second wavelength coverage; First lens, it is configured to first laser beam is focused on the CD that is loaded into the pre-position; Second lens, it is configured to the incoming laser beam of second laser beam and the 3rd laser beam is focused on the CD that is loaded into the pre-position; The lens supports module, it is configured to first lens and second lens are supported so that they are along the orbital direction of the CD that is loaded into the pre-position and put; First detection module, its be configured to detect first laser beam from CD reflection reflected light; Second detection module, its be configured to detect one of second laser beam and the 3rd laser beam from CD reflection reflected light; Control module, it is configured to control according to one of the first detection module and second detection module detected reflected light and follows rail; And read module, it is configured to come the data of reading and recording on CD according to one of the first detection module and second detection module detected reflected light, wherein, described lens supports module with first lens supports along predetermined radial direction move the axle on.

To set forth other purpose of the present invention and advantage in the instructions hereinafter, and described purpose and advantage will partly become clear by following description, perhaps can be by practice of the present invention is understood.Can realize and obtain objects and advantages of the present invention by following means of pointing out specially and combination thereof.

Description of drawings

The accompanying drawing of incorporating among the present invention and constituting the part of instructions shows embodiments of the invention, and with the detailed description of above-mentioned describe, in general terms and the embodiment that hereinafter provides principle of the present invention has been described.

Fig. 1 shows the schematic block diagram according to the layout of the CD drive of the embodiment of the invention;

Fig. 2 shows the synoptic diagram according to the structure of the optical head of this embodiment;

Fig. 3 shows the view according to the area dividing of the diffraction element of this embodiment;

Fig. 4 shows the view according to the surveyed area of the photodetection module of this embodiment;

Fig. 5 is the view that is used to explain according to the layout of CD object lens of the present invention and HD DVD/BD/DVD object lens; And

Fig. 6 is the view that is used to explain the DPP method.

Embodiment

Hereinafter will be by describing according to various embodiments of the present invention with reference to the accompanying drawings.Generally, optical head according to an embodiment of the invention is a kind of like this optical head: it is configured to and can moves along the predetermined radial direction of the CD that is loaded into the pre-position, it comprises: first light emitting module, and it is configured to give off first laser beam that is included in first wavelength coverage; Second light emitting module, it is configured to give off second laser beam that is included in second wavelength coverage, and described second wavelength coverage is shorter than described first wavelength coverage; The 3rd light emitting module, it is configured to give off the 3rd laser beam that is included in the wavelength range, and described wavelength range is shorter than described second wavelength coverage; First lens, it is configured to first laser beam is focused on the CD that is loaded into the pre-position; Second lens, it is configured to the incoming laser beam of second laser beam and the 3rd laser beam is focused on the CD that is loaded into the pre-position; The lens supports module, it is configured to first lens and second lens are supported so that they are on the orbital direction of the CD that is loaded into the pre-position and put; First detection module, it is configured to detect the reflected light of first laser beam from CD reflection; And second detection module, it is configured to detect a reflected light from CD reflection in second laser beam and the 3rd laser beam; And the lens supports module with first lens supports move along predetermined radial direction the axle on.

Embodiments of the invention hereinafter are described with reference to the accompanying drawings.

Fig. 1 shows the synoptic diagram according to the layout of the CD drive of the embodiment of the invention.CD drive comprises optical head 1, prime amplifier 2, signal processing module 3, control module 4, LD driver module 5, wave recording generation module 6, storer 7 etc.

CD drive focuses on by the laser beam that optical head 1 is emitted on the information recording layer of CD and writes down or playback of information.The light of CD reflection passes through the optical system of optical head 1 once more, and is detected by photodetector (the general photodetection module 25 of DVD/HD DVD/BD or be included in CD photodetection module in the CD holographic cell 13, this will be described hereinafter) and to be electric signal.Detected electric signal is amplified by prime amplifier 2, and is output subsequently to signal processing module 3, and signal processing module 3 comprises servo module, RF signal processing module, address signal processing module etc.

Servo module produces such as focus signal, follows the servosignal rail signal, the tilt signals according to the detected electric signal of optical head 1, and with these signals export to respectively optical head 1 focus actuator, follow rail actuator and tilt actuators.That is to say that signal processing module 3 (servo module) plays the effect that follows the rail control module.

The RF signal processing module to the handling with signal of optical head 1 detected electric signal, carries out playback to the information such as the user profile that is write down by mainly.As demodulation method in this case, known have dicing method and a PRML method.That is to say that signal processing module 3 (RF signal processing module) plays the effect of the read module that the data that are recorded on the CD M are read.

The address signal processing module is read physical address information by handling detected signal, the record position on this physical address information indication CD, and the address signal processing module exports the physical address information of being read to control module 4.Control module 4 is read the information such as user profile of expecting the position based on this address information, perhaps the information such as user profile is recorded in the desired locations place.In this case, the tracer signal processing module that is included in the wave recording generation module 6 is modulated into user profile the data that are suitable for video disc recording.At this moment, data-modulated adopts the modulator approach such as (1,10) run length (RLL) modulation, (1,7) RLL modulation and so on.In (1,10) RLL modulation, the shortest employed symbol is 2T in the data-modulated, and employed long symbol is 11T in the data-modulated.And, wave recording generation module 6 produces the signal that is used to control laser emitting waveform based on incoming symbol, and laser diode (LD) driver module 5 comes the driving laser diode based on this laser emitting waveform control signal, thereby records the information on the CD.

Fig. 2 shows the synoptic diagram of the structure of optical head 1.Optical head 1 comprises: HDDVD/BD light source 11, DVD light source 12, CD holographic cell 13, Amici prism 14, polarization beam apparatus (PBS) 15, spectroscope 16, collimation lens (CL) 17, λ/4 (quarter-wave) wave plate 18, CD deviation prism 19, HD DVD/BD/DVD deflecting mirror 20, diffraction element 21 ((HOE) forms by the polarization holography optical element), CD object lens 22, HD DVD/BD/DVD object lens 23, actuator 24, the general photodetection module 25 of DVD/HD DVD/BD, and the multiplying power convertible lens 26 that is used to change the enlargement factor of CD.

HD DVD/BD light source 11 comprises that it can launch the laser beam that for example is about 405nm with the corresponding wavelength of HD DVD/BD as laser diode of semiconductor Laser device etc.Similarly, DVD light source 12 comprises that it can launch the laser beam that for example is about 650nm with the corresponding wavelength of DVD as laser diode of semiconductor Laser device etc.

CD holographic cell 13 be one by with semiconductor laser (can launch the laser beam that is about 780nm with the corresponding wavelength of CD), be used to obtain various servosignals photodiode, be used for beam split and integrate the unit for preparing with grating of obtaining servosignal etc., it can obtain signal by only laser beam being focused on the CD.

The laser beam that HD DVD/BD light source 11 is emitted is propagated through Amici prism 14 and polarization beam apparatus 15, reflected by spectroscope 16, and collimated lens 17 collimates.After this, laser beam process λ/4 wave plates (Polarization Control sheet) 18, and be converted into circularly polarized light.Subsequently, laser beam is propagated through CD deviation prism 19, and, propagate process then by the formed diffraction element 21 of beam splitting element (being holographic plate (polarization holography optical element [HOE])), and be directed to DVD/BD/DVD object lens 23 by 20 reflections of HDDVD/BD/DVD deflecting mirror.Notice that HD DVD/BD/DVD object lens 23, diffraction element 21 and CD object lens 22 are integrally supported by lens mount 27.

23 pairs on HD DVD/BD/DVD object lens are directed to the convergence that the laser beam of HD DVD/BD/DVD object lens 23 is scheduled to, and this laser beam focuses on arbitrary recording layer of CD M.Notice that guide groove, track and record mark (being recorded data) array is that the spacing with 0.34 μ m or 0.4 μ m is formed on according to concentric shape or spiral helicine mode on each recording layer of CD M.For example, DVD/BD/DVD object lens 23 are made of plastics, and its numerical aperture is 0.65 (at HD DVD) or 0.85 (at BD).

Laser beam after HD DVD/BD/DVD object lens 23 are scheduled to assemble is propagated the overlayer that passes through CD, and focuses on (or its adjacent position) on certain recording layer.Like this, formed tuftlet spot at the place, focal position of HD DVD/BD/DVD object lens 23 from the laser beam of HD DVD/BD light source 11.

HD DVD/BD/DVD object lens 23 are arranged on pre-position on the focus direction (thickness direction of each recording layer) by object lens driving mechanism (for example comprising drive coil or magnet).Notice that so-called to follow rail control be a kind of like this position control to HD DVD/BD/DVD object lens 23: mobile HD DVD/BD/DVD object lens 23 on orbital direction are so that be complementary the tuftlet spot of laser beam and the center of track (record mark array).So-called focus control is a kind of like this position control to HD DVD/BD/DVD object lens 23: its by at mobile HD DVD/BD/DVD object lens 23 on the focus direction so as to make each recording layer and HD DVD/BD/DVD object lens 23 between the focal length of distance and HD DVD/BD/DVD object lens 23 be complementary.

The arbitrary recording layer institute laser light reflected bundle of CD M is received by HD DVD/BD/DVD object lens 23, and is converted into the cross section bundle shape of almost parallel, is back to diffraction element 21 subsequently.

Diffraction element 21 only works to the light that comprises the particular circle polarized light component, and it carries out beam splitting and diffraction to form a plurality of light beams to this light.That is to say that the light beam of outwards advancing passes through diffraction element 21,21 diffraction of the then diffracted element of the light beam of back advancing hardly diffractedly.This diffraction element 21 is divided into a plurality of presumptive areas, and for example as shown in Figure 3, each zone has different diffraction and diffraction grating direction (diffraction gratingdirections).

Each light beam behind these diffraction element 21 diffraction is reflected by HD DVD/BD/DVD deflecting mirror 20, and is converted and import to the linearly polarized photon that light differs 90 ° by λ/4 wave plates 18.As a result, these light beams are polarized beam splitter 15 reflections.

Because the convergence that collimation lens 17 produces makes these light beam irradiates on the light receiving surface of the general photodetection module 25 of DVD/HDDVD/BD.At this moment, the folded light beam after diffraction element 21 beam splitting is to focus on layout that sets in advance the surveyed area (light area) in the general photodetection module 25 of DVD/HD DVD/BD and the corresponding mode of shape.For example, when having arranged surveyed area as shown in Figure 4, propagate through the regional FA of diffraction element 21 and FB and by the light beam of its diffraction and be focused on border between regional O1 and O2 and regional P1 and the P2 respectively, thereby based on the focus error signal of so-called knife-edge method.The signal that is obtained is input to the servo module of signal processing module 3.Propagate through regional MA, MB, MC and MD and by the light beam of its diffraction and focus on regional A, B, C and the D place of the general photodetection module 25 of DVD/HD DVD/BD respectively, recommend (PP) signal thereby obtain at differential phase detection (DPD) signal of ROM dish or at what R or RW coiled.Propagate through region S A and SB and by the light beam of its diffraction and focus on the area E and the F place of the general photodetection module 25 of DVD/HD DVD/BD, the lens owing to HDDVD/BD/DVD object lens 23 are moved the signal that the skew of the PP signal that produces compensates thereby obtain.And the RF signal processing module of signal processing module 3 obtains the RF signal by all signals are carried out the phase Calais.

The signal Processing of HD DVD/BD system has been described.

Similarly, 12 emitted laser bundles of DVD light source are reflected by Amici prism 14, and the HD DVD/BD light path through is much at one focused on the recording surface of CD M by HD DVD/BD/DVD object lens 23, and be recorded surface reflection, 21 diffraction of diffracted subsequently element.Diffracted beam is received by the general photodetection module 25 of DVD/HD DVD/BD.In this case, because the wavelength of the laser beam that the wavelength of the laser beam that emitted of DVD light source 12 is emitted greater than HD DVD/BD light source 11, so the angle of diffraction of 21 diffraction of diffraction element becomes greater than HD DVD/BD system.For this reason, regional a to f, o1 and p2 are used in the light area of the general photodetection module 25 of DVD/HD DVD/BD.

The signal Processing of dvd system has been described.

13 emitted laser bundles of CD holographic cell are propagated through multiplying power convertible lens 26 and spectroscope 16, and collimated lens 17 are corrected into almost parallel light.In addition, λ/4 wave plates 18 are converted to the approximate circle polarized light with laser beam by linearly polarized photon, and laser beam is reflected by CD deviation prism 19 then, and is directed to CD object lens 22.The laser beam that enters CD object lens 22 convergence that becomes, and on the recording surface of CD M, focus on.And, back propagate with the path identical from the reflected light that the recording layer of CD M reflects, and the CD photodetection module that is comprised in the CD holographic cell 13 receives with access path.The photodetection module converts received reflected light to electric signal.The servo module of signal processing module 3 produces servosignal (comprise based on the rail that follows of DPP method and controlling) according to this electric signal, and the RF signal processing module in the signal processing module produces the RF signal.

CD object lens 22 and HD DVD/BD/DVD object lens 23 hereinafter will be described.

For example, the 3 wavelength compatible objective that the different wavelength of laser Shu Jinhang of HD DVD, DVD and CD focuses on have been proposed to be used for to be used in.Utilize this lens, with regard to the relation between the wavelength of HD DVD and CD laser beam, the enlargement factor of HD DVD and CD must have than big difference.This is because the wavelength of CD laser beam almost is the twice of HD DVD laser beam wavelength.In the object lens that diffraction grating are used on the lens,, be difficult to improve the diffraction efficiency of these two wavelength so, thereby produce a large amount of diffraction loss if these diffraction grating have equal enlargement factor relation.

On the contrary, the optical head of present embodiment comprises CD object lens 22 and HD DVD/BD/DVD object lens 23 respectively.So, realized having the objective lens design of good optical performance and light service efficiency, and the optical head that has higher anti-lens offset characteristic and support the high power speed recording be provided.

, can come actuator 24 is optimized when carrying out crooked adjusting to actuator 24 (actuator 24 combines CD object lens 22 and HDDVD/BD/DVD object lens 23) at HD DVD that requires stricter lurching allowance and DVD.Because CD has the crooked allowance of broad, so the actuator 24 that is optimized at HD DVD and DVD is supported CD.Alternatively, can be at actuator 24 adjusted CD object lens 22.

And, CD object lens 22 and HD DVD/BD/DVD object lens 23 will be described below.As shown in Figure 5, lens mount 27 integrally supports HD DVD/BD/DVD object lens 23 and CD object lens 22.Optical head 1 (lens mount 27) can move on the predetermined radial direction of the CD that is loaded into the pre-position.Lens mount 27 integrally supports HD DVD/BD/DVD object lens 23 and CD object lens 22 along the orbital direction of the CD that is loaded into this pre-position, and CD object lens 22 are supported on along on the shifting axle of predetermined radial direction.That is, lens mount 27 is supported on CD object lens 22 on the position that is offset without any normal direction.In other words, lens mount 27 supports HD DVD/BD/DVD object lens 23 and CD object lens 22 making it on tangential direction and to put, and CD object lens 22 is supported on the feed line of the center of spindle motor and optical head.

So the DPP method that is proved to be a kind of fabulous rail method of following is applicable to that CD handles.That is, can use the universal optical system unit of handling at CD.For HD DVD, BD and DVD, realized adopting the receiving system design of the integrated HOE of actuator, multiplayer optical disk can be relatively easily supported in this design, and being used for the processing of HD dvd system and being used for the processing of dvd system can a shared photo detector, thereby has greatly reduced cost and size.

When the integrated HOE of actuator used with aforementioned 3 wavelength compatible objective, the light of HOE institute diffraction entered more likely that CD is subjected to optical module and parasitic light during as recording/playback CD.On the contrary, the optical head of present embodiment is not subjected to the influence of parasitic light.

Below the problem of DPP method will briefly be described referring to Fig. 6.As shown in Figure 6, in the time of on being radiated at CD, obtain the DPP signal based on the reflected light component of main beam MB, beamlet SB1 and beamlet SB2, these light beams have alternately formed groove track G and ridge track L on this CD.That is to say, can obtain DPP by following formula:

DPP＝MPP-K(SPP1+SPP2)

Wherein

MPP: recommend (PP) signal with main beam MB is corresponding

SPP1: with the corresponding PP signal of beamlet SB1

SPP2: with the corresponding PP signal of beamlet SB2

K: coefficient

When the position of lens center from normal moves to track, owing to changing along the radial position of the distance of disc radial direction between main beam MB and beamlet SB1 and the SB2 along with object lens, so change with beamlet SB1 and the corresponding PP signal of SB2 phase place, and the PP changes in amplitude of the DPP signal that is calculated is very big with respect to track crossing.As a result, the precision of following rail control based on the DPP signal reduces.

Therefore, in the present embodiment, for the DPP method being applied to the processing without any the CD system of lens position skew, CD object lens 22 are supported on the center and optical head feed line of spindle motor, thereby have avoided the reduction that follows the rail control accuracy when using the DPP method.

Can obtain following effect by the foregoing description.

(1) be similar to infinite system owing to adapting to, and can both guarantee higher light utilization efficiency three kinds of wavelength, thus can guarantee higher anti-lens offset behavior, and support the high power literary sketch to go into.

(2) when the actuator that combines object lens is carried out crooked adjusting, can optimize actuator at the HD DVD and the DVD that require strict more lurching allowance.

(3) when having used, can guarantee the compatibility between HD DVD and the DVD with the integrated HOE of the corresponding actuator of HD DVD/BD/DVD object lens.Similarly, can guarantee the DATA-PDIC compatibility.

(4) when having used with the integrated HOE of HD DVD/BD/DVD object lens 23 corresponding actuators, the light of the integrated HOE of actuator institute diffraction can not enter CD as parasitic light and be subjected to optical module when carrying out the CD processing.

The various modules of CD drive described here are implemented as the parts on software application, hardware and/or software module or the one or more computing machine (for example server).Though each module has been described respectively, their may be shared a plurality of or bottom logical OR code that all are identical.

To those skilled in the art, can draw other advantage and remodeling at an easy rate.Therefore, more the invention is not restricted to specific detail and the representative embodiment that this paper illustrates and described in the wide region.So, can under the situation of the spirit or scope of the overall thought of the present invention that does not break away from the claims and the equivalent form of value thereof and limited, make various modifications.

Claims (5)

1. optical head, it is configured to and can moves along the predetermined radial direction of the CD that is loaded into the pre-position, it is characterized in that comprising:

First light emitting module, it is configured to give off first laser beam that is included in first wavelength coverage;

Second light emitting module, it is configured to give off second laser beam that is included in second wavelength coverage, and described second wavelength coverage is shorter than described first wavelength coverage;

The 3rd light emitting module, it is configured to give off the 3rd laser beam that is included in the wavelength range, and described wavelength range is shorter than described second wavelength coverage;

First lens, it is configured to first laser beam is focused on the CD that is loaded into the pre-position;

Second lens, it is configured to the incoming laser beam of second laser beam and the 3rd laser beam is focused on the CD that is loaded into the pre-position;

The lens supports module, it is configured to first lens and second lens are supported so that they are on the orbital direction of the CD that is loaded into the pre-position and put;

First detection module, it is configured to detect the reflected light of first laser beam from CD reflection; And

Second detection module, it is configured to detect one of second laser beam and the 3rd laser beam reflected light from CD reflection,

Wherein, described lens supports module with first lens supports on the shifting axle on the predetermined radial direction.

2. optical head as claimed in claim 1 is characterized in that, first lens focus on first laser beam that is used for CD, and

Second lens focus on second laser beam that is used for DVD and the incoming laser beam that is used for the 3rd laser beam of HD DVD.

3. CD drive, it comprises a kind of optical head, and described optical head is configured to and can moves along the predetermined radial direction of the CD that is loaded into the pre-position, and described CD drive is characterised in that and comprises:

First light emitting module, it is configured to give off first laser beam that is included in first wavelength coverage;

Second light emitting module, it is configured to give off second laser beam that is included in second wavelength coverage, and described second wavelength coverage is shorter than described first wavelength coverage;

The 3rd light emitting module, it is configured to give off the 3rd laser beam that is included in the wavelength range, and described wavelength range is shorter than described second wavelength coverage;

First lens, it is configured to first laser beam is focused on the CD that is loaded into the pre-position;

Second lens, it is configured to the incoming laser beam of second laser beam and the 3rd laser beam is focused on the CD that is loaded into the pre-position;

The lens supports module, it is configured to first lens and second lens are supported so that they are on the orbital direction of the CD that is loaded into the pre-position and put;

First detection module, it is configured to detect the reflected light of first laser beam from CD reflection;

Second detection module, it is configured to detect one of second laser beam and the 3rd laser beam reflected light from CD reflection;

Control module, it is configured to control according to one of the first detection module and second detection module detected reflected light and follows rail; And

Read module, it is configured to come the data of reading and recording on CD according to one of the first detection module and second detection module detected reflected light,

Wherein, described lens supports module with first lens supports on the shifting axle on the predetermined radial direction.

4. CD drive as claimed in claim 3 is characterized in that, control module is controlled by the differential push-pull method according to the reflected light component of first laser beam and followed rail.

5. CD drive as claimed in claim 4, it further comprises the polarization holography optical element, described optical element carries out diffraction to the reflected light through one of second laser beam of second lens and the 3rd laser beam, and the reflected light behind the diffraction is guided to second detection module.

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