CN100403417C - Optical pickup unit and information recording apparatus using the same - Google Patents

Abstract

An optical pickup unit for recording information on and/or reproducing information from a multilayer information recording medium including multiple recording surfaces in each of which a guide groove on which the information is to be recorded is spirally formed is disclosed. The optical pickup unit includes a light source, a diffraction element configured to split the light beam emitted from the light source into a main light beam and first and second sub light beams, an objective lens for focusing the main and sub light beams onto a recording surface of the multilayer information recording medium, and multiple light receiving elements each divided into light receiving parts so as to receive the main and sub light beams reflected from the recording surface. The focused first and second sub light beams are disposed at respective positions at least 3/2 tracks away from the focused main light beam on the recording surface.

Description

Optical pick-up unit and the information record carrier that uses it

Technical field

Relate generally to optical pick-up unit of the present invention and information record carrier, relate to such optical pick-up unit and the information record carrier that uses it on concrete, described optical pick-up unit is by using differential push-pull method and come on the recording surface of multi-layered information recording medium recorded information and from its information reproduction, described differential push-pull method being used to detect and control the position of the light beam that is sent.

Background technology

In information record carrier, launch main beam from light source to the recording surface of information recording carrier with its guide groove that has write down information (information track), so that recorded information on described information recording carrier, or according to from the light of described recording surface reflection from described information recording carrier information reproduction.Described information record carrier comprises optical pick-up unit, is used for launching main beam on the recording surface of described information recording carrier, and receives from the light of described recording surface reflection.

And as shown in fig. 1, described optical pick-up unit comprises light source 11, comprises the optical system of object lens 16 and separated light receiving element 19.Described optical system also comprises coupled lens 12, beam splitter 14 and deflecting mirror 15.Described optical system will be directed to the recording surface of information recording carrier 18 from light source 11 emitted light beams, and will be directed to predetermined light-receiving position from the Returning beam of recording surface reflection, in described location arrangements described separated light receiving element 19.Described separated light receiving element 19 is not only exported the information reproduction of the data that write down on recording surface, and output comprises the signal of the information that the position of control optical pick-up unit itself and object lens 16 is required.These signals are fed, so that control their position, thereby scioptics gearing 17 is carried out drive controlling.

In precalculated position record data on the recording surface and the data that are reproduced in the precalculated position record on the recording surface, should accurately on the precalculated position of recording surface, launch main beam for accurately.This feasible position that must accurately detect the main beam of being launched.As a result, proposed the whole bag of tricks, be used to use the position of detecting the main beam of being launched on recording surface from the Returning beam of recording surface reflection, the some of them method has dropped into practicality.

As the method that is used for detecting from the Returning beam that writes down surface reflection certainly the position of the main beam on recording surface, a kind of push-pull method that is called is widely adopted.

As shown in Figure 2, according to described push-pull method, the light beam that sends from light source is separated into a main beam 1 and two beamlets 2, so that each of described main beam 1 and described beamlet 2 half track space of radial missing on recording surface each other.Received by three separated light receiving element 19a-19c respectively from the main beam 1 of recording surface reflection and the Returning beam of two beamlets 2, as shown in Figure 3.Each of described separated light receiving element 19a-19c is divided into two parts.Each acquisition push-pull signal from described separated light receiving element 19a-19c.From the sub-push-pull signal (SPP) of the push-pull signal (MPP) of main beam 1 and two beamlets 2 and between difference obtain equation (1) to seek rail error signal (DPP) as follows:

DPP＝MPP-K(SPP) ...(1)

Wherein, K is an integer.According to detection like this seek the rail error signal, carry out the so-called rail control of seeking, be used for upwards driving object lens in the footpath of information recording carrier.

On information recording carrier during recorded information, the reflectance varies of guide groove.Therefore, as shown in Fig. 4 A, on information recording carrier with the process from the center to its peripheral direction recorded information, because poor on the reflectivity between non-recorded part 4 and the recording section 5, with the first beamlet 2a and the second beamlet 2b arrange make on the CD scanning direction the first beamlet 2a with main beam 1 be directed to its inboard, the second beamlet 2b is directed to the deviation that its outside has caused differential push-pull signal with main beam 1.Therefore, according to Japanese Laid-Open Patent Application 2004-164720 number, as shown in Fig. 4 B, the first and second beamlet 2a and 2b are arranged and make on the first recording surface 2a on the CD scanning direction is directed to main beam 1 outside it, the second beamlet 2b is directed to its inboard with main beam 1, eliminate the influence of the difference of the reflectivity in each of the first and second beamlet 2a and 2b thus, and therefore reduced the deviation in the differential push-pull signal.

Use multi-layered information recording medium to be used as being used to improving the means of the capacity of information recording carrier.In described multi-layered information recording medium, current those media that drop into actual use comprise DVD+R bilayer (DL) dish and DVD-ROM bilayer (DL) dish.

Fig. 5 shows the structure of DVD+R DL dish.Referring to Fig. 5, described DVD+R DL dish comprises 1 layer of 0 layer of substrate, 0 layer of dyeing, semi-transparent film, middle layer, 1 layer of dyeing, reflectance coating and substrate, and they begin to pile up from light incident (object lens) side with described order.

Record is as from the 0 layer of signal message to the variation of dyeing the refractive index 1 layer, on guide groove that dye.Usually, can use polycarbonate for 1 layer for 0 layer of substrate and substrate, and can use UV treatment (UV cure) or thermosetting resin for the middle layer.For semi-transparent film, can use silicon, silver or aluminium, and can use silver or aluminium for reflectance coating.

On each recording surface, form guide groove spirally.The hand of spiral is different between the L1 layer on the opposite side of the L0 layer of L0 layer on the object lens side and object lens.This structure---wherein the hand of spiral of guide groove is different between L0 layer and L1 layer---is called as " relative orbit path (OTP) ".

In the OTP dual layer discs, on the L0 layer with from the center of dish to the direction of periphery and on the L1 layer (from described periphery to described center) recorded information in the opposite direction.

About prior art, can be with reference to Japanese Laid-Open Patent Application 2003-196860 and 2002-015442 number.

Fig. 6 A shows the traditional arrangement of under the situation of DVD+R DL disc recording information main beam 1 and beamlet 2a and 2b.Be in the process of recorded information in the L0 layer, can use that disclosed above-mentioned technology obtains good push-pull signal in Japanese Laid-Open Patent Application 2004-164720 number, this is because there is not the difference of reflectivity in each of beamlet 2a and 2b.

Yet, being in the process of recorded information in the L1 layer (wherein with from the periphery of dish to the direction recorded information at center), the zone of recording section 5 is opposite, as shown in Fig. 6 B.As a result, in each of beamlet 2a and 2b, cause the difference of reflectivity, therefore in push-pull signal, cause deviation.That is, under the situation of recorded information on the multi-layered information recording medium with OTP structure, the technology that Japanese Laid-Open Patent Application is 2004-164720 number has problem: cause deviation in one of recording layer of recording medium.

Summary of the invention

Therefore, general objects of the present invention provides a kind of optical pick-up unit, has wherein eliminated above-mentioned shortcoming.

One of the present invention purpose more specifically provides a kind of optical pick-up unit, it can be from wherein obtaining good beamlet signal at the different multi-layered information recording medium of the hand of spiral of each recording surface upper rail, and come on described recording medium recorded information and from described recording medium reproducing information by using such as the differential push-pull signal that obtains from described good beamlet signal and the stabilization signal the lens position signal.

Of the present invention another more specifically purpose provide a kind of information record carrier that uses described optical pick-up unit.

One or more above-mentioned purpose of the present invention realizes by a kind of optical pick-up unit is provided, described optical pick-up unit is used on multi-layered information recording medium recorded information and/or from described multi-layered information recording medium information reproduction, described multi-layered information recording medium comprises a plurality of recording surfaces, in each recording surface, form spirally as the guide groove that will write down the information track of described information on it, wherein, the hand of spiral of guide groove replaces between recording surface, described optical pick-up unit comprises: light source is used to launch light beam; Diffraction element, its described beam separation that is configured to send from described light source is the main beam and first and second beamlets; Object lens are used for described main beam and described first and second beamlets are focused on one of recording surface of described multi-layered information recording medium; And, a plurality of light receiving elements, each all is divided into a plurality of light receiving parts, described light receiving part is shaped by any way, so that receive from the main beam and first and second beamlets of the reflection of one of recording surface, wherein, first and second beamlets that focused on are arranged on the relevant position on one of recording surface, so that satisfy condition $h\sin \mathrm{\θ}\≥(n+\frac{1}{2})\×\mathrm{TP}$ Wherein, h is the distance between one of first and second beamlets of the main beam of the focusing on one of recording surface and focusing, θ is by described information track and is connected the main beam that is focused on one of recording surface and angle that the straight line of one of first and second beamlets of focusing forms, n is the integer more than or equal to 1, and TP is a track space.

According to one aspect of the present invention, each beamlet is disposed in the zone of a recording section on the recording surface of multi-layered information recording medium or in the zone of a non-recorded part, in described recording section, write down information by main beam.Therefore, might obtain good signal, and in the reflectivity of each beamlet, not have difference.

One or more above-mentioned purpose of the present invention realizes by a kind of information record carrier that also described information record carrier comprises: according to optical pick-up unit of the present invention; Signal processing, it is configured to produce to promote mainly according to the signal from the light receiving element of described optical pick-up unit draw first of signal, first beamlet and seek second of the rail error signal and second beamlet and seek the rail error signal, described promote mainly draw signal be described main beam seek the rail error signal; Described signal processing is configured to seek rail error signal sum and produce sub-push-pull signal by calculating described first and second; And described signal processing is configured to produce differential push-pull signal by calculating in the described difference of drawing signal and being multiplied by between the described sub-push-pull signal of correction factor of promoting mainly; The track controller, it is configured to come the described object lens of control on orbital direction according to described differential push-pull signal; And, driver, it is configured to drive described object lens.

According to one aspect of the present invention, can on each recording surface of multi-layered information recording medium, stably carry out and seek rail control, wherein, and in each recording surface, the hand of spiral difference of guide groove.

The one or more of above-mentioned purpose of the present invention realize by a kind of information record carrier that also described information record carrier comprises: according to optical pick-up unit of the present invention; Signal processing, it is configured to produce to promote mainly according to the signal from the light receiving element of described optical pick-up unit draw first of signal, first beamlet and seek second of the rail error signal and second beamlet and seek the rail error signal, described promote mainly draw signal be described main beam seek the rail error signal; Described signal processing is configured to seek rail error signal sum and produce sub-push-pull signal by calculating described first and second; And described signal processing is configured to produce differential push-pull signal by calculating in the described difference of drawing signal and being multiplied by between the described sub-push-pull signal of correction factor of promoting mainly; The lens controller, it is configured to proofread and correct according to the lens position signal displacement of object lens; And driver, it is configured to drive described object lens.

According to one aspect of the present invention, for the hand of spiral of guide groove wherein different multi-layered information recording medium in each recording surface, might be when seeking operation with respect to the high speed of each recording surface the position of control object lens.

According to one aspect of the present invention,, can obtain good beamlet signal with respect to each recording surface for the hand of spiral of guide groove wherein different multi-layered information recording medium in each of its recording surface.And, can during writing down, obtain agonic good differential push-pull signal, lens position signal and track cross signal with respect to each recording surface, also be like this even between non-recorded part and recording section, there is the difference of reflectivity.As a result, might carry out the good control of object lens position, so as can be accurately, recorded information and on multi-layered information recording medium stably from described multi-layered information recording medium information reproduction.

Description of drawings

By describing in detail below in conjunction with accompanying drawing, other purposes of the present invention, feature and advantage will become apparent, wherein:

Fig. 1 is the synoptic diagram that traditional optical pick-up unit is shown;

Fig. 2 is the figure that the traditional arrangement of the main beam that is focused on the recording surface and beamlet is shown;

Fig. 3 is the circuit diagram that three light receiving elements and calculated signals device are shown, and each of described three light receiving elements all is divided into two parts that are used to receive main beam shown in Fig. 2 and beamlet;

Fig. 4 A and 4B are each figure that shows the traditional arrangement of main beam on the recording surface that is focused information recording carrier and beamlet;

Fig. 5 is the figure that the structure of multi-layered information recording medium (dual layer discs) is shown;

Fig. 6 A and 6B are each figure that the traditional arrangement of main beam on the recording surface that focuses on multi-layered information recording medium (dual layer discs) and beamlet is shown;

Fig. 7 A and 7B are that each all illustrates according to one embodiment of the present of invention, focuses on the figure of the layout of main beam on the recording surface of multi-layered information recording medium (dual layer discs) and beamlet;

Fig. 8 is used for the figure of diagram according to the position relation between main beam and beamlet of the first embodiment of the present invention;

Fig. 9 is the synoptic diagram that illustrates according to the optical pick-up unit of the first embodiment of the present invention;

Figure 10 illustrates according to three light receiving elements of the first embodiment of the present invention and the circuit diagram of calculated signals device, and each of described three light receiving elements all is divided into two parts that are used to receive main beam and beamlet; And

Figure 11 is the block scheme that illustrates according to the information record carrier of the second embodiment of the present invention.

Embodiment

Referring now to accompanying drawing, embodiments of the invention is described.

Below, for the purpose of simplifying the description, the dual layer discs that will have two recording surfaces is used as the example of multi-layered information recording medium.But, the invention is not restricted to dual layer discs.And, in the accompanying drawings, be indicated as identical label with aforesaid those components identical, and omit its explanation.

Fig. 7 A and 7B are that each all illustrates according to the first embodiment of the present invention, is focused the figure of the layout of main beam 1 on the recording surface of multi-layered information recording medium (dual layer discs) and beamlet 2a and 2b.Fig. 7 A show wherein light beam 1,2a and 2b each focus on recording surface (L0 layer, Fig. 5) state on of object lens side.In Fig. 7 A, with from the center of dish to direction recorded information on recording surface of periphery.Dual layer discs is around the rotation of described disk center.In Fig. 7 A, described dual layer discs turns clockwise, so that scan described recording surface counterclockwise by light beam 1,2a and 2b.Therefore, tail (back) the side identifying recording layer of the main beam 1 on the side of center (interior) and on the CD scanning direction (forming recording section 5).Described data are recorded on the groove.Therefore, main beam 1 is focused into a bundle point on groove.

According to first embodiment, beamlet 2a and 2b are focused into the bundle point on the corresponding platform (land), described corresponding platform respectively the periphery of main beam 1 (outside) on side and center (interior) side with main beam 1 at a distance of 3/2 track (track space) or longer distance.

Beamlet 2a and 2b are disposed in such position, so that first beamlet 2 is in its right side (periphery) side and detect the diffraction light of the groove of non-recorded part 4 on the side of its left side (center) with being equal to, and the second beamlet 2b is equal to the diffraction light of the groove of ground detection record part 5 in its right side (periphery) side with on the side of its left side (center).As a result, in each of beamlet 2a and 2b, obtain good signal, and be not subjected to the influence of the difference of the reflectivity between non-recorded part 4 and recording section 5.

Fig. 7 B show wherein light beam 1,2a and 2b each focus on recording surface (L1 layer, Fig. 5) state on the distally of object lens.In Fig. 7 B, with from the periphery of dish to direction recorded information on recording surface at center.As mentioned above, dual layer discs is around disk center's rotation.In Fig. 7 B, described dual layer discs turns clockwise, so that light beam 1,2a and 23b scan described recording surface counterclockwise.Therefore, on the CD scanning direction, the periphery of main beam 1 (outside) side and afterbody (back) side identifying recording layer (forming recording section 5).

Be in the process of recorded information in the L1 layer, the first beamlet 2a is equal to the diffraction light of the groove of ground detection record part 5 in its right side (periphery) side with on the side of its left side (center), and the second beamlet 2b its right side (periphery) side and on the side of its left side (center) diffraction light of the groove of detection non-recorded part 4 with being equal to.As a result, in each of beamlet 2a and 2b, obtain good signal, and be not subjected to the influence of the difference of the reflectivity between non-recorded part 4 and recording section 5.

According to first embodiment, on the CD scanning direction, the first beamlet 2a be disposed in its periphery (outside) before the main beam 1 on the side, the second beamlet 2b is disposed in after the main beam 1 on the heart (interior) side therein.Perhaps, on the CD scanning direction, the first beamlet 2a can be disposed in its periphery (outside) after the main beam 1 on the side, the second beamlet 2b is disposed in before the main beam 1 on the heart (interior) side therein, as long as each of beamlet 2a and 2b and main beam 1 apart 3/2 track or longer distance.

Illustrate in greater detail this first embodiment referring to Fig. 8.Referring to Fig. 8, suppose that focusing on main beam 1 on the recording surface and the distance between the first beamlet 2a (or second beamlet 2b), focusing on angle, the track space (radial distance between the guide groove at information recording carrier) that the straight line of main beam 1 on the recording surface and the first beamlet 2a (or second beamlet 2b) forms by information track and connection be respectively h, θ and TP, arrange that then main beam 1 and beamlet 2a and 2b are to satisfy following formula:

$h\sin \mathrm{\θ}\≥(n+\frac{1}{2})\×\mathrm{TP}\·\·\·\left(2\right)$

Wherein, n is the integer more than or equal to 1.

On concrete, coiling recorded information to DVD+RDL or from the situation of its information reproduction, can arrange that light beam 1,2a and 2b are to satisfy following formula:

$h\sin \mathrm{\θ}\≥(n+\frac{1}{2})\×0.74\left(\mathrm{\μm}\right)\·\·\·\left(3\right)$

This makes and might obtain good signal with respect to DVD+R (or DVD-R) multilayer disc, and does not have difference in each of beamlet 2a and 2b on reflectivity, and the track space of described DVD+R (or DVD-R) multilayer disc is 0.74 micron.

And, to blue light dual layer discs recorded information or from the situation of its information reproduction, can arrange that light beam 1,2a and 2b are to satisfy following formula:

$h\sin \mathrm{\θ}\≥(n+\frac{1}{2})\×0.35\left(\mathrm{\μm}\right)\·\·\·\left(4\right)$

This makes and might obtain good signal with respect to the blue light multilayer disc, and does not have difference in each of beamlet 2a and 2b on reflectivity, and the track space of described blue light multilayer disc is 0.35 micron.

Generally, might because the influence of the distortion of its substrate and birefringent influence and with signal distributions near the periphery of information recording carrier.Therefore, preferably, on the platform of 3/2 track or longer distance, beamlet is being positioned at as far as possible near-earth near main beam with main beam.

Can on the platform of 3/2 track or longer distance, obtain good signal by each beamlet being positioned at main beam.

Therefore, preferably, arrange each of beamlet 2a and 2b at recording surface, to satisfy following formula:

$h\sin \mathrm{\θ}=\frac{3}{2}\×\mathrm{TP}\·\·\·\left(5\right)$

This makes to bear seeks the rail error in the inside part of multi-layered information recording medium and outermost part.

In this, for DVD+R DL dish, each the position that beamlet 2a and 2b are set is to satisfy following formula:

hsinθ＝1.11(μm) ...(6)

This makes and might obtain good signal with respect to DVD+R (or DVD-R) multilayer disc, and in each of beamlet 2a and 2b, on reflectivity, there is not difference, the track space of described DVD+R (or DVD-R) multilayer disc is 0.74 micron, and might bear and seek the rail error in the inside part of described DVD+R (or DVD-R) dish and outermost part.

And for the blue light dual layer discs, each the position that beamlet 2a and 2b are set is to satisfy following formula:

hsinθ＝0.525(μm) ...(7)

This makes and might obtain good signal with respect to the blue light multilayer disc, and in each of beamlet 2a and 2b, on reflectivity, there is not difference, the track space of described blue light multilayer disc is 0.35 micron, and might bear and seek the rail error in the inside part of described multilayer Blu-ray disc and outermost part.

Fig. 9 is the synoptic diagram that illustrates according to the optical pick-up unit of first embodiment.Except the configuration of Fig. 1, the optical pick-up unit of Fig. 9 also comprises diffraction element 13.Be separated into 0 rank main beam 1 and positive 1 rank, first beamlet 2a and negative 1 rank, the second beamlet 2b from the diffracted element 13 of light of light source 11 emissions.Each of light beam 1,2a and 2b is focused on the recording surface of dual layer discs (multi-layered information recording medium) 18 by object lens 16.Has the optical path that it is changed by beam splitter 14 from each of recording surface beam reflected 1,2a and 2b, so that separated light receiving element 19 detects.

Be controlled at each the position of the beamlet 2a of the focusing on the recording surface and 2b by rotate diffraction element 13 with respect to principal plane.

Detect from main beam 1 and the beamlet 2a and the 2b of recording surface reflection by separated light receiving element 19.Figure 10 shows the configuration of separated light receiving element 19.Referring to Figure 10, separated light receiving element 19 comprises three light receiving element 19a to 19c, and each is divided into a plurality of parts that are shaped by any way, promptly, its optical receiving surface is divided into two parts, is respectively applied for and receives main beam, first beamlet and second beamlet.

The optical receiving surface of light receiving element 19a is divided into two part A and B, is respectively applied for to detect the part that focuses on as the main beam on the recording surface as shown in Fig. 7 A and the 7B 1 aWith bThe optical receiving surface of light receiving element 19b is divided into two portion C and D, is respectively applied for to detect the part that focuses on as the first beamlet 2a on the recording surface as shown in Fig. 7 A and the 7B cWith dThe optical receiving surface of light receiving element 19c is divided into two part E and F, is respectively applied for to detect the part that focuses on as the second beamlet 2b on the recording surface as shown in Fig. 7 A and the 7B eWith f

Followingly obtain to promote mainly and draw signal (MPP) by calculating the right side in main beam 1 and the difference between the left signal:

$\mathrm{MPP}=\frac{(A-B)}{(A+B)}\·\·\·\left(8\right)$

Followingly obtain the first sub-push-pull signal (SPP1) by the right side and the difference of calculating in the first beamlet 2a between the left signal:

$\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1=\frac{(C-D)}{(C+D)}\&CenterDot;\&CenterDot;\&CenterDot;\left(9\right)$

Followingly obtain the second sub-push-pull signal (SPP2) by the right side and the difference of calculating in the second beamlet 2b between the left signal:

$\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2=\frac{(E-F)}{(E+F)}\&CenterDot;\&CenterDot;\&CenterDot;\left(10\right)$

Following by calculate the first sub-push-pull signal (SPP1) and the second sub-push-pull signal (SPP2) with obtain sub-push-pull signal (SPP):

SPP＝SPP1+SPP2 ...(11)

Followingly obtain differential push-pull signal (DPP) in the difference of promoting mainly between the sub-push-pull signal (SPP) of drawing signal (MPP) and being multiplied by correction factor K by calculating:

DPP＝MPP-K×SPP ...(12)

Wherein, K is an integer.

At this, MPP and SPP differ 180 degree on phase place, cause the deviation that causes owing to the optical axis displacement on the same plus or minus direction of MPP and SPP.Therefore, the value by K is set to the ratio of main beam 1 and the light quantity of beamlet 2a and 2b, and MPP and SPP mate on amplitude, so that the deviation of the push-pull method that causes owing to the optical axis displacement of elimination generally.This makes that might carry out the stable rail of seeking controls.

And, as shown in Figure 7A, for example, improved the reflectivity of the second beamlet 2b because of the recording section 5 on the recording surface in the L0 layer.Suppose that the raising rate at the reflectivity of this point is r, then at the first and second sub-push-pull signal SPP1 ' of this point with SPP2 ' is following provides:

$\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1}^{\&prime;}=\frac{(C-D)}{(C+D)}=\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1,\\ {\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2}^{\&prime;}=\frac{(\mathrm{rE}-\mathrm{rF})}{(\mathrm{rE}+\mathrm{rF})}=\frac{(E-F)}{(E+F)}=\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2\end{array}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(13\right)$

Therefore, when on the recording surface at dual layer discs main beam 1 being focused under the situation about being focused at the supercentral bundle point of groove and with each of beamlet 2a and 2b at the supercentral bundle point of corresponding platform, following equation is true:

MPP′＝SPP1′＝SPP2′＝DPP＝0 ...(14)

Wherein, MPP ' draws signal corresponding to promoting mainly of SPP1 ' and SPP2 '.

Therefore, during writing down, do not cause deviation, therefore obtained good differential push-pull signal.

Equally, in the L1 layer, the reflectivity of the first beamlet 2a also improves because of the recording section 5 on recording surface.Suppose that the raising rate at the reflectivity of this point is r, then SPP1 ' and SPP2 ' are following provides:

$\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1}^{\&prime;}=\frac{(\mathrm{rC}-\mathrm{rD})}{(\mathrm{rC}+\mathrm{rD})}=\frac{(C-D)}{(C+D)}\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1,\\ {\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2}^{\&prime;}=\frac{(E-F)}{(E+F)}=\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2\end{array}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(15\right)$

Therefore, when on the recording surface at dual layer discs main beam 1 being focused under the situation about being focused at the supercentral bundle point of groove and with each of beamlet 2a and 2b at the supercentral bundle point of corresponding platform, following equation is true:

MPP′＝SPP1′＝SPP2′＝DPP＝0 ...(16)

Therefore, during writing down, do not cause deviation, therefore obtained good differential push-pull signal.

At this,, the following describes the situation of classic method for relatively.In the L0 of Fig. 6 A layer, for example, improved the reflectivity of the second beamlet 2b because of the recording section on recording surface 5.Suppose that the raising rate at the reflectivity of this point is r, then SPP1 ' and SPP2 ' are following provides:

$\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1}^{\&prime;}=\frac{(C-D)}{(C+D)}=\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1,\\ {\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2}^{\&prime;}=\frac{(\mathrm{rE}-\mathrm{rF})}{(\mathrm{rE}+\mathrm{rF})}=\frac{(E-F)}{(E+F)}=\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2\end{array}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(17\right)$

Therefore, when on the recording surface at dual layer discs main beam 1 being focused under the situation about being focused at the supercentral bundle point of groove and with each of beamlet 2a and 2b at the supercentral bundle point of corresponding platform, following equation is true:

MPP′＝SPP1′＝SPP2′＝DPP＝0 ...(18)

Therefore, during writing down, do not cause deviation, therefore obtained good differential push-pull signal.

But, as shown in Fig. 6 B, in the L1 layer because the recording section on recording surface 5, therefore, the first beamlet 2a on peripheral (outer) side reflectivity and the second beamlet 2b peripheral (outside) reflectivity raising on the side.Therefore, suppose that the raising rate at the reflectivity of this point is r, SPP1 ' and SPP2 ' are following to be provided:

$\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1}^{\&prime;}=\frac{(C-D)}{(C+D)},\\ {\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2}^{\&prime;}=\frac{(E-\mathrm{rF})}{(E+\mathrm{rF})}\end{array}\&CenterDot;\&CenterDot;\&CenterDot;\left(19\right)$

Therefore, differential push-pull signal (DPP) comprises following deviation N (r):

$N\left(r\right)=-K(\frac{(C-D)}{(C+\mathrm{rD})}+\frac{(E-\mathrm{rF})}{(E+\mathrm{rF})})\&CenterDot;\&CenterDot;\&CenterDot;\left(20\right)$

And under the situation of the radially high-speed mobile optical pick-up unit of double-layer CD, object lens 16 are shifted because of its inertia.In order to eliminate the influence of this displacement, the displacement of using lens position signal (optical axis displacement component) to proofread and correct object lens 16.Suppose that the lens position signal is LP, then with following the providing of described lens position signal:

LP＝MPP+K×SPP ...(21)

At this, MPP and SPP differ 180 degree on phase place, and cause on the same plus or minus direction of MPP and SPP because the deviation of optical axis displacement.Therefore, the value by K is set to the ratio of main beam 1 and the light quantity of beamlet 2a and 2b, and MPP and SPP mate on amplitude, the result, and the elimination amplitude error is so that only obtain optical axis displacement component as the lens position signal.This feasible position that might accurately control object lens 16.

At this, for example, in the L0 layer shown in Fig. 7 A, because the recording section on recording surface 5, improved the reflectivity of the second beamlet 2b.Suppose that the raising rate at the reflectivity of this point is r, then SPP1 ' and SPP2 ' are following provides:

$\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1}^{\&prime;}=\frac{(C-D)}{(C+D)}=\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1,\\ {\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2}^{\&prime;}=\frac{(\mathrm{rE}-\mathrm{rF})}{(\mathrm{rE}+\mathrm{rF})}=\frac{(E-F)}{(E+F)}=\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2\end{array}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(22\right)$

Therefore, when on the recording surface at dual layer discs main beam 1 being focused under the situation about being focused at the supercentral bundle point of groove and with each of beamlet 2a and 2b at the supercentral bundle point of corresponding platform, following equation is true:

MPP′＝SPP1′＝SPP2′＝LP＝0 ...(23)

Therefore, during writing down, do not cause deviation, therefore obtained good lens position signal.

Equally, in the L1 layer shown in Fig. 7 B, the reflectivity of the first beamlet 2a also improves because of the recording section 5 on recording surface.Suppose that the raising rate at the reflectivity of this point is r, then SPP1 ' and SPP2 ' are following provides:

$\begin{array}{c}{\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1}^{\&prime;}=\frac{(\mathrm{rC}-\mathrm{rD})}{(\mathrm{rC}+\mathrm{rD})}=\frac{(C-D)}{(C+D)}\mathrm{<figure-callout\; id="1"\; label="SPP"\; filenames="C20058000167000201.png,C20058000167000211.png"\; state="\{\{state\}\}">SPP</figure-callout>}1,\\ {\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2}^{\&prime;}=\frac{(E-F)}{(E+F)}=\mathrm{<figure-callout\; id="2"\; label="SPP"\; filenames="C20058000167000201.png"\; state="\{\{state\}\}">SPP</figure-callout>}2\end{array}\&CenterDot;\&CenterDot;\&CenterDot;\&CenterDot;\left(24\right)$

Therefore, when on the recording surface at dual layer discs main beam 1 being focused under the situation about being focused at the supercentral bundle point of groove and with each of beamlet 2a and 2b at the supercentral bundle point of corresponding platform, following equation is true:

MPP′＝SPP1′＝SPP2′＝LP＝0 ...(25)

Therefore, during writing down, do not cause deviation, therefore obtained good lens position signal.

Figure 11 is the block scheme that illustrates according to the information record carrier of the second embodiment of the present invention.Referring to Figure 11, dual layer discs 18a makes each of its recording surface rotate on same direction by main shaft (SP) motor 20.Receive from main beam and two beamlets according to optical pick-up unit of the present invention 10 in the dual layer discs 18a reflection of separated light receiving element 19a on to the above-mentioned separated light receiving surface A of 19c (Figure 10) to F.The light beam that is received carries out opto-electronic conversion at the separated light receiving element 19a of correspondence in 19c, so that be output to calculated signals device 21.In described calculated signals device 21, the output of optical pick-up unit 10 is converted into magnitude of voltage in current/voltage amplifier 21a, and described magnitude of voltage is fed to DPP counting circuit 21b, LP counting circuit 21c and TC counting circuit 21d each.DPP counting circuit 21b produces above-mentioned differential push-pull signal (DPP).LP counting circuit 21c produces above-mentioned lens position signal (LP).TC counting circuit 21d produces track cross signal (TC).These signals are fed to object lens controller 22, and described object lens controller 22 comprises the track controller that is used for control object lens on orbital direction and is used to proofread and correct the lens controller of the displacement of object lens.As a result, by driver drives and control object lens.

Described information record carrier comprises control section 30, and it comprises object lens controller 22, seeks electromotor control circuit 23 and main shaft (SP) electromotor control circuit 24.Seek electromotor control circuit 23 controls and seek motor 31.Seek the motor 31 mobile optical pickup unit 10 that makes progress in the footpath of dual layer discs 18a.SP electromotor control circuit 24 control spindle drive motors 20.

Go up under the situation of executive logging at the multi-layered information recording medium (dual layer discs) that adopt coloring material, inorganic material or photochromics (photopolymer) for its recording layer, it is big that the difference of the reflectivity between non-recorded part and recording section trends towards becoming.Because recorded information on non-recorded part always is so especially true under the situation of executive logging on the write-once multi-layered information recording medium.Therefore, according to one aspect of the present invention, can be to obtain under the situation of executive logging on such multi-layered information recording medium more stable signal.

According to one aspect of the present invention, each beamlet is disposed in the zone of the recording section on the recording surface of multi-layered information recording medium or in the zone of non-recorded part, in described recording section, has write down information by main beam.Therefore, might obtain good signal, and on the reflectivity of each beamlet, not have difference.

According to one aspect of the present invention, can on each recording surface of multi-layered information recording medium, stably carry out and seek rail control, wherein, and in each recording surface, the hand of spiral difference of guide groove.

According to one aspect of the present invention, for the different multi-layered information recording medium of the hand of spiral of guide groove in each recording surface wherein, might be seek the rail operation with respect to the high speed of each recording surface the time position of control object lens.

According to according to optical pick-up unit of the present invention with use its information record carrier,, can obtain good beamlet with respect to each recording surface with respect to the different multi-layered information recording medium of the hand of spiral of groove on its each recording surface wherein.And, can during writing down, obtain agonic good differential push-pull signal, lens position signal and track cross signal with respect to each recording surface, also be like this even between non-recorded part and recording section, there is the difference of reflectivity.As a result, might carry out the good control of object lens position, so as can be accurately, recorded information and on multi-layered information recording medium stably from described multi-layered information recording medium information reproduction.Therefore the present invention can be used for using the optical pick-up unit of differential push-pull method, described differential push-pull method is used to detect and control the position of emitted light beams on the recording surface of multi-layered information recording medium, and the present invention can be used for using the information record carrier of described optical pick-up unit.

The invention is not restricted to concrete disclosed embodiment, and can change without departing from the scope of the invention and revise.

The Japanese priority patent application that the application submits to based on the Japanese priority patent application of submitting on October 18th, 2004 2004-302662 number with on March 8th, 2005 2005-063861 number, its whole content is comprised in this by reference.

Claims (12)

1. optical pick-up unit, be used on multi-layered information recording medium recorded information and/or from described multi-layered information recording medium information reproduction, described multi-layered information recording medium comprises a plurality of recording surfaces, form spirally in each recording surface therein as the guide groove that will write down the information track of described information on it, wherein, alternately, described optical pick-up unit comprises the hand of spiral of guide groove between recording surface:

Light source is used to launch light beam;

Diffraction element, it is configured to the described beam separation from described light emitted is the main beam and first and second beamlets;

Object lens are used for described main beam and described first and second beamlets are focused on one of recording surface of described multi-layered information recording medium; And

A plurality of light receiving elements, each is divided into a plurality of light receiving parts, and described light receiving part is shaped by any way, so that receive from the main beam and first and second beamlets of the reflection of one of described recording surface,

Wherein, first and second beamlets that focused on are disposed on the relevant position on one of recording surface, so that satisfy condition

$h\sin \mathrm{\&theta;}\&GreaterEqual;(n+\frac{1}{2})\&times;\mathrm{TP}$

Wherein, h is the distance between one of first and second beamlets of the main beam of the focusing on one of recording surface and focusing, θ is by described information track and is connected the main beam that is focused on one of recording surface and angle that the straight line of one of first and second beamlets of focusing forms, n is the integer more than or equal to 1, and TP is a track space.

2. according to the optical pick-up unit of claim 1, wherein, to DVD+R multi-layer disc recording information or under the situation of its information reproduction, first and second beamlets of focusing are disposed on the relevant position on one of recording surface, so that satisfy condition

3. according to the optical pick-up unit of claim 1, wherein, to blue light multi-layer disc recording information or under the situation of its information reproduction, first and second beamlets of focusing are disposed on the relevant position on one of recording surface, so that satisfy condition

4. according to the optical pick-up unit of claim 1, wherein, first and second beamlets of focusing be disposed on one of recording surface, with the main beam that focuses on the relevant position of 3/2 track.

5. according to the optical pick-up unit of claim 4, wherein, first and second beamlets that are focused are disposed on the relevant position on one of recording surface, so that satisfy condition

Hsin θ=1.11 micron.

6. according to the optical pick-up unit of claim 4, wherein, first and second beamlets of focusing are disposed on the relevant position on one of recording surface, so that satisfy condition

Hsin θ=0.525 micron.

7. information record carrier comprises:

Optical pick-up unit according to claim 1;

Signal processing, it is configured to produce to promote mainly according to the signal from the light receiving element of described optical pick-up unit draw first of signal, first beamlet and seek second of the rail error signal and second beamlet and seek the rail error signal, described promote mainly draw signal be described main beam seek the rail error signal; Described signal processing is configured to seek rail error signal sum and produce sub-push-pull signal by calculating described first and second; And described signal processing is configured to produce differential push-pull signal by calculating in the described difference of drawing signal and being multiplied by between the described sub-push-pull signal of correction factor of promoting mainly;

The track controller, its be configured to according to described differential push-pull signal and on orbital direction the described object lens of control; And

Driver, it is configured to drive described object lens.

8. according to the information record carrier of claim 7, wherein, described correction factor is the ratio of the light summation of the light quantity of main beam and described first and second beamlets.

9. according to the information record carrier of claim 7, wherein, with the multi-layered information recording medium of write-once as to its record and/or from the multi-layered information recording medium of its information reproduction.

10. information record carrier comprises:

Optical pick-up unit according to claim 1;

Signal processing, it is configured to produce to promote mainly according to the signal from the light receiving element of described optical pick-up unit draw first of signal, first beamlet and seek second of the rail error signal and second beamlet and seek the rail error signal, described promote mainly draw signal be described main beam seek the rail error signal; Described signal processing is configured to seek rail error signal sum and produce sub-push-pull signal by calculating described first and second; And described signal processing is configured to produce differential push-pull signal by calculating in the described difference of drawing signal and being multiplied by between the described sub-push-pull signal of correction factor of promoting mainly;

The lens controller, it is configured to proofread and correct according to the lens position signal displacement of object lens; And

Driver, it is configured to drive described object lens.

11. according to the information record carrier of claim 10, wherein, described correction factor is the ratio of the light summation of the light quantity of main beam and described first and second beamlets.

12. according to the information record carrier of claim 10, wherein, with the multi-layered information recording medium of write-once as to its record and/or from the multi-layered information recording medium of its information reproduction.

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