CN101165790A

CN101165790A - Optical pickup apparatus and optical disc apparatus using same

Info

Publication number: CN101165790A
Application number: CNA200710091083XA
Authority: CN
Inventors: 神定利昌; 北田保夫; 山崎和良; 川村友人; 小西义郎
Original assignee: Hitachi Media Electronics Co Ltd
Current assignee: Hitachi Media Electronics Co Ltd
Priority date: 2006-10-18
Filing date: 2007-04-06
Publication date: 2008-04-23
Anticipated expiration: 2027-04-06
Also published as: JP2008102998A; JP4357518B2; CN101165790B

Abstract

An optical pickup apparatus is provided with a dividing element having a plurality of regions. The dividing element is capable of dividing a light flux reflected by the optical disc into a plurality of light fluxes having different outgoing directions. Each region of the dividing element and light receiving parts of a light detector are structured such that when a target information recording layer of the optical disc is brought into focus, a light flux reflected from the target information recording layer is focused on the light receiving parts of the light detector, and a light flux reflected from other information recording layer than the target information recording layer is not irradiated onto the light receiving parts of the light detector.

Description

Optical Pickup device and optical disc apparatus with it

Technical field

The optical disc apparatus that the present invention relates on CD, to carry out recording of information or reproduction with and employed optical Pickup device, the optical disc apparatus that particularly relates to recording of information on the CD of a plurality of information recording layers or reproduction with lamination with and employed optical Pickup device.

Background technology

As the method for the recording capacity that increases CD, studied the technology of the multiplayer optical disk of laminated information recording layer.DVD (Digital Versatile Disc: digital universal disc) or BD (Blu-ray Disc: Blu-ray disc), HD-DVD (High Density Digital Versatile Disc: in the standard high-density digital general dish) with the double-layer CD of the two-layer information recording layer of spacer stack of about 20～55 μ m just in commercialization.Also studied the CD more than three layers as high capacity technology more in addition.

At the record that carries out this multiplayer optical disk or when reproducing, for the focus that makes laser exactly to being positioned at zone of interest, must get rid of the focus error signal that the parasitic light from other layers causes or the deviation of tracking error signal as far as possible.

As the method for getting rid of from the influence of the parasitic light of other layers, for example, in " the Electricity feelings Reported skill Reported CPM2005-149 of Communications Society (2005-10) ", put down in writing to follow the tracks of and be disposed at the zone that does not have the multilayer parasitic light with optical detector.

Summary of the invention

But in " the Electricity feelings Reported skill Reported CPM2005-149 of Communications Society (2005-10) ", the influence of focus error signal is not put down in writing at parasitic light.

In addition, in " the Electricity feelings Reported skill Reported CPM2005-149 of Communications Society (2005-10) " because the light accepting part that tracking error signal must be used be disposed at the light accepting part used at focus error signal around the outside that produces from the parasitic light of other layers, so the increasing of the size of photodetector.

And, as the background technology of this light picker, for example Japanese patent laid-open 9-223321 communique is arranged.In this communique, as problem record " provide a kind of and can reduce optics and the optical information reproducing apparatus of simplification device; and a kind of method of adjustment that can adjust the optical information reproducing apparatus of tracking error signal according to the characteristic of CD is provided ", as solution record " optical information reproducing apparatus possesses: the light picker with the object lens that light shine CD; The direction that is equivalent to track is generally perpendicularly cut apart hot spot from the ejaculation light of CD, the heart of hot spot centering is become first of end regions and middle zone cut apart module; Further to the direction almost parallel ground of the track that is equivalent to CD cut apart end regions and middle zone hot spot second cut apart module; Have reception and cut apart the photo detector that module and above-mentioned second is cut apart a plurality of light receiving units of the light that module cuts apart by first; Receive the output computing each other of light receiving unit of cutting apart the light in the middle zone that module cuts apart by second, detect the tracking error generation module of the relative displacement of track and object lens; The computing of output signal with the output signal of tracking error generation module by hot spot dislocation signal detection module, the drift correction module of the deviation of correction tracking error signal; On the direction of the track of crosscut CD, drive the objective lens device of object lens; The tracking Control mechanism of drive controlling objective lens device; And when access with the input of tracking Control module output as hot spot dislocation signal detection module, when the information regeneration of CD with the input of tracking Control module, via the drift correction module, switch to the handover module of the output of tracking error generation module ".

Because in general optical Pickup device positively shines hot spot on the track record of the regulation that is positioned at CD, so the detection by focus error signal makes the object lens displacement on focus direction, outside on focus direction, adjusting, detect tracking error signal, make object lens follow the tracks of adjustment to the radial direction displacement of disc recording medium.These signals carry out the position control of object lens.

Though as method for testing track error signal, push pull mode is known in the middle of this, exist direct current change (hereinafter referred to as the DC deviation) the such problem that is easy to generate greater than the tracking direction displacement of object lens.Therefore, the differential push pull mode that can reduce this DC deviation is extensively used.

Differential push pull mode (DPP:Differential Push Pull) is divided into main beam and side beam by diffraction grating with light beam, and the hot spot of the main beam of use radial direction and the hot spot of side beam reduce the DC deviation.

But owing to form a plurality of hot spots on CD, the light utilization ratio of main beam reduces.This main beam not only generates focus error signal and tracking error signal, also has the effect that generates record mark on writing down with CD.Being recorded in record when use CD, because big more then its writing speed of the light quantity of the main beam on the CD is fast more, so, become unfavorable at use diffraction grating in the optical system of road from the viewpoint of record speed multiplay.

Therefore in JP-A-9-223321, on dish, form a hot spot, by its reflected light is assigned to a plurality of zones, even object lens also detect the stable tracking error signal that does not have the DC deviation at the tracking direction top offset.There is the light utilization ratio not reduce by this formation, can improves the advantage of record speed multiplay.(hereinafter referred to as a light beam mode)

But, if carry out the subregion of this detecting device of JP-A-9-223321, generation problem in recording type optical disc such as BD-RE, BD-R for example then.Under the situation of recording type optical disc, the zone (hereinafter referred to as posting field) that exists the zone that is not recorded (hereinafter referred to as posting field not) and be recorded.Become the problem of the not posting field that can't be reduced in this subregion of JP-A-9-223321 on dish and the deviation of the tracking error signal of the boundary portion place generation of posting field.

The object of the invention is to provide a kind of optical disc apparatus, and it can obtain the optical head and the optical disc apparatus with it of stable servosignal in the record-playback of multiplayer optical disk.

As an example that is used to address the above problem, optical head of the present invention has: light source; Be used for to converge in from the light beam that above-mentioned light source penetrates the object lens on the above-mentioned CD; Be used for to be divided into the cutting element of multiple light beams by the light beam of above-mentioned CD reflection; Be used to converge collector lens by the light beam of above-mentioned CD reflection; And be used for that the light beam that will be converged by above-mentioned collector lens is received by a plurality of light accepting parts and the photodetector that is transformed into electric signal,

Above-mentioned cutting element has: first cut zone that is configured in substantial middle; Distinguished by first cut-off rule, and second cut zone that constitutes of four zones that dispose across above-mentioned first cut zone by the direction along first cut-off rule; And distinguished with second cut-off rule of the above-mentioned first cut-off rule quadrature, and the 3rd cut zone that constitutes of four zones that dispose across above-mentioned first cut zone by the direction along above-mentioned second cut-off rule,

Each zone of above-mentioned first to the 3rd cut zone constitutes: when the purpose information recording layer focusing at above-mentioned CD, folded light beam from the above-mentioned purpose information recording layer focuses on the light accepting part of above-mentioned photodetector, does not shine the above-mentioned light accepting part of above-mentioned photodetector from the folded light beam of the record-playback layer beyond the above-mentioned purpose information recording layer.

According to the present invention, in a pencil tracing mode, can obtain stable focus error signal and tracking error signal.

In addition, in the present invention, improve deviation as not posting field with the tracking error signal of the boundary portion place generation of posting field of the problem points in the above-mentioned light beam mode.Even specifically provide a kind of usefulness to have optical Pickup device or optical information reproducing apparatus or apparatus for optically recording and reproducing information that the CD of the boundary portion of posting field and posting field not also can detect the new tracking error signal detection module of the tracking error signal after stable.

The object of the invention is to provide a kind of optical Pickup device and apparatus for optically recording and reproducing information that can detect stable tracking error signal.

Above-mentioned purpose can be by the realization that constitutes described in claims as an one example.

Description of drawings

Fig. 1 is the synoptic diagram of expression as the formation of the optical head of embodiments of the invention.

Fig. 2 is the synoptic diagram of the shape of polarizing diffraction grating in the expression embodiments of the invention.

Fig. 3 is the synoptic diagram of the shape of photodetector and light pattern in the expression embodiments of the invention.

Fig. 4 A～4F is the synoptic diagram of the situation that light pattern changes in the expression embodiments of the invention.

Fig. 5 A～5E is the synoptic diagram of the situation that light pattern changes in the expression embodiments of the invention.

Fig. 6 A～6E is the synoptic diagram of the shape of the light pattern in the double-layer CD in the expression embodiments of the invention.

Fig. 7 is the synoptic diagram of second embodiment of polarizing diffraction grating among expression the present invention.

Fig. 8 is the synoptic diagram of the shape of the light pattern among second embodiment of polarizing diffraction grating among expression the present invention.

Fig. 9 is the synoptic diagram of the 3rd embodiment of polarizing diffraction grating among expression the present invention.

Figure 10 is the synoptic diagram of the shape of the light pattern among the 3rd embodiment of polarizing diffraction grating among expression the present invention.

Figure 11 is the skeleton diagram that carries the optical disc apparatus of optical head of the present invention.

Figure 12 is the synoptic diagram of the configuration of optical disc apparatus and CD among the explanation embodiment 4.

Figure 13 is the synoptic diagram that uses the optical Pickup device of a light beam mode among the explanation embodiment 4.

Figure 14 is the synoptic diagram of light accepting part of the present invention or diffraction grating face among the explanation embodiment 4.

The synoptic diagram of the DC deviation that Figure 15 is the explanation object lens that make Figure 12 when interior periphery top offset.

Figure 16 A～16C is the synoptic diagram of the deviation that illustrates that schematically the boundary of the not posting field under the light beam mode and posting field among the embodiment 4 takes place.

Figure 17 A, 17B are with the not characteristic of posting field and posting field and JP-A-9-223321 synoptic diagram relatively among the embodiment 4.

Figure 18 A, 18B are the synoptic diagram of the effect of the present invention that causes of the difference of the dividing method of light accepting part or diffraction grating face among the explanation embodiment 4.

Figure 19 A, 19B are the synoptic diagram of the diffraction grating face beyond Figure 14 among the expression embodiment 4.

Figure 20 is the synoptic diagram that uses the optical Pickup device of a light beam mode among the explanation embodiment 4.

Figure 21 is the synoptic diagram of light accepting part or diffraction grating face among the explanation embodiment 5.

Figure 22 A, 22B are with the not characteristic of posting field and posting field and JP-A-9-223321 synoptic diagram relatively among the embodiment 5.

Figure 23 A, 23B are the light accepting part beyond Figure 19 A, the 19B or the synoptic diagram of diffraction grating face among the expression embodiment 5.

Figure 24 is the synoptic diagram that uses the optical Pickup device of a light beam mode among the explanation embodiment 6.

Figure 25 A, 25B are the synoptic diagram of light accepting part among the explanation embodiment 6.

Figure 26 is the synoptic diagram of the optical Pickup device of the use one light beam mode beyond Figure 24 among the explanation embodiment 6.

Figure 27 is the synoptic diagram that uses the optical Pickup device of a light beam mode among the explanation embodiment 7.

Figure 28 is the synoptic diagram of diffraction grating face among the explanation embodiment 7.

Figure 29 is the synoptic diagram of light accepting part among the explanation embodiment 7.

Figure 30 is the synoptic diagram of optical reproducing apparatus among the explanation embodiment 8.

Figure 31 is the synoptic diagram of optical information reproducing apparatus among the explanation embodiment 9.

Embodiment

The embodiment of optical head of the present invention at first, is described.

Optical head of the present invention for example, will be divided into from the reflected light of multiplayer optical disk by cutting element and to penetrate the different a plurality of folded light beams of direction, constitute the light beam of being cut apart and focus on diverse location on the photodetector.And, constitute by in the folded light beam of cutting element, use folded light beam by the zone that does not comprise beam center, by knife-edge method detection of focus error signal, use folded light beam detection tracking error signal by the zone that does not comprise beam center.And then each zone of cutting element is configured to when focusing on zone of interest with light accepting part, does not enter the light accepting part that the servosignal of photodetector is used from the parasitic light of other layers.

Below, describe optical head of the present invention and embodiment in detail referring to figs. 1 through Fig. 5 with its optical disc apparatus.

[embodiment 1]

The laser 2 that penetrates from semiconductor laser 1 is polarized spectroscope 3 reflections, becomes parallel beam by collimation lens 4.Parallel beam is converged on the CD 8 by object lens 7 by polarizing diffraction grating 5,1/4 wavelength plate 6.CD 8 is provided with

ground floor

9 and 10 two record-playback layers of the second layer (information recording layer), is formed with track (not shown) respectively on the direction of arrow 11.

When certain one deck of two record-playback layers that focus on CD, see through

object lens

7,1/4 wavelength plate 6 by 8 laser light reflected of CD, by polarizing diffraction grating 5 light beam is divided into a plurality of zones, on different directions, advance respectively.Then, see through collimation lens 4, polarization spectroscope 3 and focus in photodetector 12.

Be formed with a plurality of light accepting parts 13 on photodetector 12, the light beam irradiates of being cut apart by polarizing diffraction grating 5 is in each light accepting part 13.According to shining, calculate these outputs and generate focus error signal and tracking error signal in the light quantity of light accepting part 13 and from photodetector 12 output electric signal.

In the following description,, will become vertical direction to the face of CD 8 to be defined as the Z axle, tracking direction will be defined as Y-axis being used to write down or reproducing and optical head is faced toward under the situation of CD, with follow the tracks of vertical direction and be defined as X-axis.The optical axis almost parallel of the light beam of Z axle and ejaculation object lens 1.

The shape of polarizing diffraction grating 5 in Fig. 2 presentation graphs 1.Polarizing diffraction grating 5 is divided into a plurality of zones, and in Fig. 2, solid line is represented the boundary line in zone.In addition, in Fig. 2, the profile of laser beam is schematically represented in double dot dash line, and oblique line portion schematically represents the pattern of recommending that the track because of CD produces.

Be formed with cut-off rule 15 on the Y direction by beam center 14 in polarizing diffraction grating 5, on X-direction, be formed with cut-off rule 16.In addition, on polarizing diffraction grating 5, be formed with: to beam center 14 point symmetries, by four zones that comprise beam center 14 (cut zone (first cut zone) that zone C 1～C4) constitutes; To beam center 14 point symmetries,, comprise the cut zone (second cut zone) that four zones (regional A1 to A4) of a part of the cut-off rule 16 of X-direction constitute by not comprising beam center 14; And,, comprise the cut zone (the 3rd cut zone) that four zones (area B 1 is to B4) of a part of the cut-off rule 15 of Y direction constitute by not comprising beam center 14 to beam center 14 point symmetries.

In when record or when reproducing, optical head is faced toward under the situation on surface of CD, cut-off rule 15 roughly is orthogonal to the orbital direction of CD, and cut-off rule 16 is roughly parallel to the orbital direction of CD.

Zone A1 to A4 by the cut-off rule 16 of the X-direction by beam center 14, not the Y direction by beam center 14 two cut-off rules 17, not the X-direction by beam center 14 four cut-off rules 18 and be that the center becomes four cut-off rules 19 of about 30 angles of spending to separate to Y direction with beam center 14.The interval u of the Y direction of four cut-off rules 18 of X-direction sets for to comprise and recommends pattern, sets about 55～70% scope of beam diameter in an embodiment for.

In addition, regional A1 to A4 is configured to across zone C 1 to C4.Zone A1 to A4 forms regional A1 and A2 is the line symmetry with regional A4 and A3 with respect to cut-off rule 15 respectively.

And area B 1 to B4 also is configured to across zone C 1 to C4.Area B 1 is the line symmetry with area B 2 with respect to cut-off rule 16, and area B 4 is the line symmetry with area B 3 with respect to cut-off rule 16.

Comprise at regional A and to recommend pattern and according to the shape of the light accepting part 13 of photodetector 12, interval w with two cut-off rules 17 of Y direction in parasitic light does not enter the condition of light accepting part sets as far as possible for a short time, sets about 25～30% scope of beam diameter in an embodiment for.Become the cut-off rule 19 of the angle of about 30 degree to set parasitic light for to Y direction and do not enter light accepting part 13.

In addition, according to the shape of the light accepting part 13 of photodetector 12, the interval v with two cut-off rules 20 of the X-direction on area B and border zone C in parasitic light does not enter the condition of light accepting part 13 sets as far as possible for a short time.

Shape of formed diffraction grating is gone up in each zone, though respectively be identical shaped with C3, C2 with C4 to zone C 1, the zone beyond their becomes mutual different shape.Light beam is separated into ± 1 time diffraction light and shining in photodetector 12 in each diffraction grating.

Fig. 3 represents the shape and the shape of shining the light pattern on photodetector of the light accepting part 13 of photodetector 12.Fig. 3 only represents the catoptrical light pattern from the record-playback layer, does not represent the light pattern from the parasitic light of other layers.

When focusing on the record-playback layer, pool focus 21 by record-playback layer institute laser light reflected on photodetector 12, it shines 18 light accepting parts 13 in formed A to T on photodetector 12.

Light accepting part M, N, O, P are the light accepting parts that is used for by two knife-edge method detection of focus error signals.If will be shone by regional A1 diffraction on photodetector 12 ± light beam of 1 diffraction light is expressed as a1+, a1-, then light beam a1-shines in the border of light accepting part M and N, light beam a2-shines in the border of light accepting part P and O, light beam a3-shines in the border of light accepting part P and N, and light beam a4-shines in the border of light accepting part M and O.If represent output with a to j respectively from light accepting part A to J, express output with m to t respectively from light accepting part M to T, then focus error signal (FES) can by

(FES)＝(m+p)-(n+o)

Such arithmetic expression is tried to achieve.

Light accepting part E, F, G, H and light accepting part Q, R, S, T are disposed at the outside of light accepting part A, B, C, D and light accepting part M, N, O, P respectively in addition, light beam a1+, a2+, a3+, a4+ shine in light accepting part A, B, C, D, light beam b1+, b2+, b3+, b4+ shine in light accepting part E, F, G, H, light beam b1-, b2-, b3-, b4-shine in light accepting part Q, R, S, T, and these are used for the detection of tracking error signal.Make light accepting part Q, R, S, T be output as q, r, s, t respectively.

Recommend method tracking error signal (TES) can by

(TES)＝((a+e+b+f)-(c+g+d+h))-K((q+r)-(s+t))

Such arithmetic expression is tried to achieve.K is a constant, because of following the tracks of action under situation about moving on the X-direction, determines the value of K at object lens 7, makes not produce deviation in (TES).

In addition, the tracking error signal of DPD method (DPD) can detect that (a+e is c+g) with (b+f, phase differential d+h) and trying to achieve.

Light accepting part I, J are disposed at the outside of light accepting part E, F, G, H, and light beam c1+, c3+ shine in light accepting part I, and light beam c2+, c4+ shine in light accepting part J.These cooperate with other signals and are used for the detection of reproducing signal (RF), by

(RF)＝a+b+c+d+e+f+g+h+i+j

Such arithmetic expression is tried to achieve.

In addition, light beam c1-, c2-, c3-, c4-shine in the position that does not have light accepting part 13, and these are not utilized in the detection of signal.

Fig. 4 A～4F shines the situation of variation of light pattern of each light beam on photodetector 12 and the waveform of focus error signal (FES) when representing to focus on.Fig. 4 A～4C, 4E, 4F are corresponding to Fig. 4 D (a)～(e).

Represent+light pattern of 1 diffraction light 22 with the grid pattern, represent the light pattern of-1 diffraction light 23 with oblique line.Focus on the boundary line of light accepting part M～P closing focal position (c) light pattern, this moment, focus error signal was 0.Follow the focused light pattern to strengthen, (b) (d) time focus error signal obtain greatly, minimal value.And then (a) that strengthen at light pattern (e) locates that light does not shine in light accepting part 13 and focus error signal is 0.

Following and defocusing light pattern is middle auxocardia with the focal point of (c), though the light pattern in C1～C4 zone of this moment also enlarges, but because near the light pattern the beam center that does not comprise zone C 1～C4 beyond the zone of light accepting part I, J, so light pattern breaks away from light accepting part 13.In the light accepting part M to P of detection of focus error signal, according to the expansion of the light pattern of area B 1 to B4 and zone C 1 to C4, light pattern breaks away from light accepting part M to P.

Explain the variation of light pattern at the light accepting part M～P place of detection of focus error signal with reference to Fig. 5 A～5E.Fig. 5 A～5E is illustrated in the variation of light pattern 25 of the light beam a2-on the border that is concentrated on sensitive surface O and P when closing focus.(b) (c) (d) is corresponding with Fig. 4 A～4F, (a ') (e ') respectively expression (a) with (b), the state of (d) and (e) centre.Light beam converges in the position that is equivalent to beam center 16 in (c), and the focal point (beam center) with (c) is middle auxocardia to light pattern 25 along with carrying out astigmatism., so light pattern 25 break away from light accepting part M～Ps at (a ') (e ') locate become fully break away from light accepting part M～P because the imaginary

light pattern

26,27 of the light beam b2-that is equivalent to be radiated at other light accepting parts and c2-enlarges this moment, shine less than state.

The interval Wp of the X-direction of the light pattern of the regional A1～A4 in Fig. 4 A～4F because when determining to defocus according to the width w of the cut-off rule 17 of polarizing diffraction grating 5 is so the relation of the width w of the shape of light accepting part 13 and cut-off rule 17 is specified to light pattern and is not radiated at light accepting part 13 when defocusing.

In addition, because light accepting part 13 is disposed at interval between the Wp,, can make the photodetector miniaturization so, can dispose light accepting part nearby each other compared with the situation in the outside that light accepting part 13 is disposed at the light pattern when defocusing.

In addition, defocus and light pattern when enlarging following, if the irradiation of the light pattern in the zone beyond light accepting part M～P then produces distortion in the focus error signal waveform and becomes the reasons of error that focuses on when introducing.Become the oblique line portion 24 of cut-off rule 19 formed regional A of the angles of about 30 degree to be arranged in to shine in the light pattern of light accepting part A～D by Y direction and do not incide light accepting part M～P when enlarging with defocusing with polarizing diffraction grating 5.By the configuration of light accepting part, this oblique line portion can not need.

Fig. 6 A～E represents the shape of the light pattern on the photodetector 12 in the dual layer discs and the waveform of focus error signal (FES).Represent catoptrical light pattern 28 with the grid pattern, represent catoptrical light pattern 29 from the second layer 10 with oblique line from ground floor 9.Fig. 6 B is corresponding to Fig. 6 A (a), and Fig. 6 C and D are corresponding to Fig. 6 A (b), and Fig. 6 E is corresponding to Fig. 6 A (c).

The focus error signal waveform (FE) of dual layer discs can be used as the focus error signal waveform (FE1) that generates in ground floor 9 places, with synthetic the trying to achieve of the focus error signal waveform (FE2) that generates in the second layer 10 places.Fig. 6 B is the situation of the

light pattern

28,29 when focusing on ground floor 9, and light pattern 28 focuses on the detecting device 12, and light pattern 29 this moment (parasitic light) shines outside light accepting part 13.

Follow focus to move to the second layer 10 from ground floor 9, light pattern 28 becomes big and light pattern 29 diminishes, locate at the ground floor 9 and the intermediate point (b) of the second layer 10, shown in Fig. 6 C and D, light pattern 28 becomes the state that shines hardly in light accepting part M～P much at one with the size of light pattern 29.Locate at (c) that focus on the second layer 10, shown in Fig. 6 E, light pattern 29 focuses on the photodetector 12, and light pattern 28 (parasitic light) shines outside light accepting part 13.

Though focus error signal can calculate the output of light accepting part M～P and try to achieve, but closing the focus place because parasitic light does not shine in light accepting part M～P, so do not produce the deviation that parasitic light causes, in addition because the dislocation of the discrete or light accepting part 13 of the intensity distributions of laser 2 and light pattern is not produced the deviation that parasitic light causes yet, so can obtain stable focus error signal.

Though and then the waveform (FE1) that the focus error signal waveform (FE) of dual layer discs generates in ground floor 9 places twists with overlapping big more the generation more of the waveform (FE2) of the second layer 10 places generation, produce to focus on and introduce error, but owing to shine hardly in light accepting part M～P at intermediate point (b) the vicinity light pattern of ground floor 9 in the present embodiment with the second layer 10, so (FE1) little with output (FE2), the distortion of focus error signal waveform (FE) is also little.

Though same tracking error signal also can calculate the output of light accepting part A～H, Q～T and try to achieve, but because parasitic light does not shine in light accepting part A～H, Q～T in closing focus, so can not produced the stable tracking error signal of the deviation that parasitic light causes.

Though because light accepting part I, J comprise the center of light beam, even also stay on the light accepting part and become parasitic light so light pattern strengthens near the center of light beam light, but because this part is not used in the detection of focus error signal or tracking error signal, only be used for the detection of reproducing signal, so also be out of question even have in the parasitic light practicality.

As mentioned above owing to be subjected to the influence of parasitic light, thus can change in polarizing diffraction grating 5 institute's diffraction ± balance of the light quantity of 1 diffraction light.Increase so that detect the light quantity of the light accepting part of reproducing signal by the light quantity that increases+1 diffraction light 22, thereby the SN that improves reproducing signal is possible, though this moment, the light quantity of-1 diffraction light 23 reduced, but can not become greatly, so as long as the restriction of consideration on electric owing to reduce the deviation that parasitic light causes by light quantity.

Polarizing diffraction grating 5 can be fixed with 1/4 wavelength plate integratedly so that move with object lens 7 in the above-described embodiments, also can fix respectively in addition so that with object lens 7 motions.With the fixing respectively situation of object lens 7 under, though if object lens 7 move on X-direction because of following the tracks of action, then the profile of the light beam that double dot dash line is represented among Fig. 2 also moves on directions X, thereby cut-off rule 15 staggers from beam center 14, but because the position of the interval Wp of the light pattern that is manifested on photodetector 12 corresponding to the width w of cut-off rule 17 is constant with size, institute's parasitic light does not in this case shine in light accepting part 13 yet.Because the profile of light beam moves on directions X, so the situation that the value of recommending the K in the arithmetic expression of tracking error signal (TES) of method and one are fixed is different.

Polarizing diffraction grating 5 is not limited to the shape of the foregoing description.Other embodiment of polarizing diffraction grating below are described.

[embodiment 2]

Fig. 7, Fig. 8 represent polarizing diffraction grating 5 second embodiment cut zone shape and this moment shine the light pattern on photodetector 12 shape.Catoptrical light pattern 28 from ground floor 9 focuses on the photodetector 12, and the catoptrical light pattern 29 (parasitic light) from the second layer 10 of this moment is represented with oblique line.Different with first embodiment, the width W c of the X-direction of zone C 1～C4 is narrow.Area B 1～B4 enlarges because of narrowed width.The shape of zone A1～A4 is identical with first embodiment.Because area B 1～B4 enlarges,, can expect to increase the effect of the output of tracking error signal so though for the dislocation of photodetector 12, parasitic light becomes and enters light accepting part E～F, Q～T easily.

[embodiment 3]

Fig. 9, Figure 10 represent polarizing diffraction grating 5 the 3rd embodiment cut zone shape and this moment shine the light pattern on photodetector 12 shape.Catoptrical light pattern 28 from ground floor 9 focuses on the photodetector, and the catoptrical light pattern 29 (parasitic light) from the second layer 10 of this moment is represented with oblique line.

Different with first embodiment, four cut-off rules 18 of the X-direction by beam center 14 not be that the center becomes four cut-off rules 19 of about 30 angles of spending to be extended to Y direction with beam center 14.Therefore the area owing to area B 1～B4 reduces, so output q～t of light accepting part Q～T reduces, recommend the arithmetic expression of the tracking error signal of method, (TES)=((a+e+b+f)-(c+g+d+h))-K ((q+r)-(s+t)) though in the value of K must be big, but because the area of A1～A4 increases, so can expect to increase the effect of the output of tracking error signal.

Though the cutting element of light beam uses the polarizing diffraction grating in the foregoing description, is disposed between collimation lens and 1/4 wavelength plate, also common diffraction grating can be disposed between polarization spectroscope and the photodetector.

Can expect utilization to the optical disc apparatus that on CD, carries out the recording of information reproduction.

When focusing on the zone of interest of CD, owing to break away from the light accepting part that the servosignal of photodetector is used from the parasitic light of other layers, it is possible obtaining servosignal so only receive the reflected light of zone of interest, can not produced the stable focus error signal and the tracking error signal of the deviation that the parasitic light from other layers causes.

Next, the optical disc apparatus with optical head of the present invention is described.

Figure 11 is the skeleton diagram of concrete example that expression is equipped with the optical disc apparatus of optical head shown in Figure 1.The catoptron 30 that not shown being used to changes the direction of laser among semiconductor laser 1 shown in Figure 1, polarization spectroscope 3, polarizing

diffraction grating

5,1/4 wavelength plate 6, photodetector 12 and Fig. 1 is adhesively fixed in housing 31.Collimation lens 4 is fixed in housing 31 under the state that can move along optical axis by travel mechanism 32, with under each situation of record-playback on the second layer 10, the spherical aberration that can move to the laser 2 that is concentrated on CD 8 becomes minimum position at record-playback on the ground floor 9 of CD 8.

Object lens 7 are installed on the support 34 that coil 33 is packed into, are combined to form actuator with not shown magnet and can be to the face shake and the eccentric object lens 7 of following the trail of of CD 8.

In addition, housing 31 can move on the radial direction of CD 8 by motor 35 and lead screw 36.CD 8 is fixed in spindle drive motor 37.

Each constitutes the action at position by system, control circuit 47 controls, at first makes 46 actions of spindle drive motor driving circuit and drive shaft motor 37 when carrying out record-playback, rotary CD 8.

Then make the drive circuit for laser action and make semiconductor laser 1 luminous.

According to the output of photodetector 12, generate focus error signals by servosignal generative circuit 43, based on this signal, carry out focus control, so that make the focal point of the laser 2 that object lens 7 cause aim at the record-playback layer by actuator driving circuit 45 driving actuator.

Under the situation of the focal point that makes laser 2 in alignment with ground floor 9, make collimation lens 5 move to position corresponding to ground floor 9 after, the detection of focus error signal.Because focus error signal can obtain waveform shown in Figure 6, so carry out focus control at place, the first laminated focal position.

Then make access control circuit 44 actions and make motor 35 rotations, make housing 31 move to the interior week of CD 8 or the desired locations of periphery via lead screw 36.

Then, according to the output of photodetector 12,, make the focal point of laser 2 follow the trail of tracking Control on the track of CD 8 by actuator driving circuit 45 driving actuator based on the tracking error signal that is generated by servosignal generative circuit 43.

Then, according to the output of photodetector 12, by the data-signal on the track of information signal reproducing circuit 42 reproduction CDs 8.

In addition, information is being recorded under the situation of CD 8, is making drive circuit for laser 41 action corresponding to recorded information, the output of semiconductor laser modulation 1 and form record mark in orbit by system, control circuit 47.

After the record-playback layer being moved to from ground floor 9 under the situation of the second layer 10, stops tracking Control by system, control circuit 47, with stop focus control in make actuator driving circuit 45 action and the focal point of laser instrument 2 moved to the second layer.Then carry out focus control, so that the focal point of laser closes in the second layer with the timing driving actuator of the second laminated focal position of detection of focus error signal.After then making collimation lens 4 move to position, make the tracking Control on the focal point track rail of laser 2 based on the focus error signal driving actuator corresponding to the second layer 10.When the reproducing movement at the second layer 10 places and operation of recording and ground floor 9, similarly carry out.

Though polarizing

diffraction grating

5,1/4 wavelength plate 6 is fixed in housing 31 in the above-described embodiments, also can be fixed in the support 34 identical and with object lens 7 motions with object lens 7.

Though above embodiment for optical head of the present invention and the optical disc apparatus with it is understood embodiment in more detail, but the invention is not restricted to the foregoing description, in the scope that does not break away from spirit of the present invention, also can comprise various variation and improvement example.

For example, though in the above-described embodiment, a record or a reproduction of reproducing the CD of layer (information recording layer) institute lamination for double record be illustrated, but also the present invention can be applied to the record-playback layer institute lamination more than three layers CD record or reproduce.

In addition, the configuration pattern of the light accepting part of photodetector also is not limited to above-mentioned example, under the situation of the purpose information recording layer that focuses on CD, so long as do not shine light accepting part in photodetector from the folded light beam of the record-playback layer beyond the purpose record-playback layer, light accepting part can at random dispose.

In addition, though in above-mentioned formula embodiment, constitute first cut zone by four zones of C1 to C4, but the invention is not restricted to this, can constitute first cut zone, also can constitute by two zones by a zone, and then, also can constitute by zone more than four.

[embodiment 4]

Figure 12 is the summary pie graph of an example of the optical Pickup device of the expression fourth embodiment of the present invention.

As shown in figure 12, optical Pickup device 101 constitutes and can drive on the radial direction of CD 100 by driving mechanism 107.Be equipped with object lens 102 on the actuator 105 on this external optical Pickup device, light shines on the CD from these object lens 102.The light that penetrates from object lens 102 forms hot spot at CD, from CD reflection.Generate focus error signal, tracking error signal by detecting this reflected light.

In above-mentioned this optical disc apparatus, Figure 13 represents optical system.Though here BD is described, also can be HD DVD or other recording modes.

From semiconductor laser 50, penetrate the roughly light beam of 405nm of wavelength as diverging light.Be transformed into the light beam of almost parallel by collimation lens 51 from the light beam of semiconductor laser 50 ejaculations.The light beam that sees through collimation lens 51 is reflected by spectroscope 52.And a part of light beam sees through spectroscope 52 and incides preposition monitor 53.In general under the situation of the CD that information is recorded in recordable types such as BD-RE, BD-R, because the light quantity of regulation is shone the record surface in CD, so be necessary to control accurately the light quantity of semiconductor laser.Therefore, preposition monitor 53 feeds back to the driving circuit (not shown) of semiconductor laser 50 in that signal record during in the CD of recordable type, is detected the variation of the light quantity of semiconductor laser 50.Light quantity on the monitoring compact disc becomes possibility thus.

Spectroscope 52 beam reflected incide optical beam expander 54.Optical beam expander 54 is by changing the dispersing of light beam, convergence state, is used to compensate the spherical aberration that the tectal thickness error of CD 100 causes.The light beam of outgoing beam extender 54 is straightened catoptron 55 reflections, through behind 1/4 wavelength plate 56, is converged on the CD 100 by the object lens 102 that are equipped on actuator 105.

See through

object lens

102,1/4 wavelength plate 56, erect catoptron 55, optical beam expander 54, spectroscope 52 by CD 100 beam reflected.The light beam of transmitted beam extender 52 is branched off into through the light beam of spectroscope 57 and beam reflected.

Detect spectroscope 57 beam reflected focus error signals by knife-edge method.In addition, though in the focus detection mode, use knife-edge method here, be not limited thereto.In addition because edge of a knife mode is its explanation of known Therefore, omited.The light beam that sees through spectroscope 56 incides detecting device 108.By signal and the tracking error signal on these detecting device 108 detection CDs.

Figure 14 represents light accepting part pattern of the present invention.Light accepting part 108 has area I (zone 1), regional J (regional 2), regional G (zone 3), four zones of regional H (zone 4), and area I (zone 1) and regional G (zone 3) and regional J (zone 2) and regional H (zone 4) are to the center line line symmetry of light accepting part.In addition, area I (zone 1) is characterised in that along with the width that leaves central shaft 500 directions in the approximate vertical direction from central shaft (or center line) 500 narrows with regional J (zone 2).

Here, with reference to Figure 14 the tracking error signal detection principle of one light beam mode is described.On the detecting device face, take place by 0 diffraction light of dish diffraction and the zone of ± 1 diffraction light interference.Because the state of the interference in this zone is different because of the facula position on the track, so can utilize it hot spot to be disposed at the orbital position of expectation.In fact, by calculate 0 diffraction light ,+the interference region Z1 of 1 diffraction light in the difference generation push-pull signal of resulting signal among the interference region Z2 of resulting signal and 0 diffraction light ,-1 diffraction light.In addition, change because of the facula position on the track hardly beyond this interference region.One light beam mode is utilized this characteristic.

At length describe below.Light beam is along with the displacement of the object lens direction of arrow top offset at Figure 14 on light accepting part.Meanwhile the intensity distributions center is also at same direction top offset.Because of these two kinds of influences, (I-J) the DC deviation takes place in the signal.In addition, in (G-H) signal the DC deviation takes place also.Figure 15 represents (I-J) signal of object lens displacement and (G-H) departure of signal.According to this figure, (I-J) signal and (G-H) the departure generation DC deviation almost linear of signal as can be known to the displacement of object lens.Therefore, if carry out following computing as can be known then can detect the repressed tracking error signal of DC deviation.

(tracking error signal)=(I-J)-k (G-H) (formula 1)

Here k revises the DC deviation of (I-J) signal and (G-H) coefficient of the DC deviation of signal.Like this, a light beam mode detects the tracking error signal that suppresses deviation becomes possibility.

Next, the deviation to the tracking error signal of the boundary portion place generation of not posting field and posting field on the dish describes.Figure 16 A～16C schematically represents the not synoptic diagram of the tracking error signal waveform of a light beam mode of the boundary of posting field and posting field.Figure 16 A represents to suppress the situation of deviation, and Figure 16 B represents because of the situation of over-correction in opposition side generation deviation.And Figure 16 C is the tracking error signal that suppresses deviation.

In the such tracking error signal waveform of Figure 16 A, 16B, tracking error signal strengthens because of discrete the grade with the Uncrossed possibility of origin position.If tracking error signal does not intersect, then become problem on the servocontrol.(tracking Control is carried out servocontrol at this origin position.) therefore, the preferred as can be known such waveform of Figure 16 C.

Here, consider the ratio of bottom, the ratio at top as the index of the deviation of tracking error signal.The ratio of so-called bottom is taken as (a-c)/(c+d) shown in Figure 16 A～16C.It is taken as the tracking error signal bottom value at posting field place and tracking error signal bottom value poor of the boundary of posting field and posting field not, the tracking error signal amplitude that is recorded the zone removes, that is to say with the tracking error signal amplitude ratio situation of posting field under any bottom of expression all be in downside.

In contrast, the ratio at top is taken as (b-d)/(c+d).This becomes the tracking error signal bottom value at posting field place and tracking error signal bottom value poor of the boundary of posting field and posting field not, the tracking error signal amplitude that is recorded location removes, that is to say with the tracking error signal amplitude ratio situation of posting field under any top of expression all be in upside.

Because if these two indexs are positive value as can be known, though then as Figure 16 C hot spot never posting field move to posting field, the tracking error signal amplitude is variation at leisure also, so servocontrol is stablized.But be under the situation of relation of positive value, negative value two indexs, be a problem owing to suppressing deviation.

In addition, the DC deviation also takes place at object lens in the deviation of tracking error signal under the situation of tracking direction top offset.Therefore, be necessary to suppress simultaneously the not border of posting field, posting field and the deviation that the object lens displacement causes.

Carry out the evaluation of the deviation of the tracking error signal that the boundary portion place of not posting field, posting field under the situation of original object lens displacement takes place below.Here, the design conditions in the emulation are as follows.

Wavelength: 405nm

Object lens NA:0.85

Track space: 0.32 μ m

Objective focal length: 1.41mm

Figure 17 A represents to use the light accepting part of the present invention and JP-A-9-223321 and the ratio at the top of object lens when the orbital direction top offset, and Figure 17 B represents the ratio of bottom.Condition as light accepting part of the present invention, ratio t1 for the area I of the beam diameter that incides detecting device (zone 1) and the interval of regional J (zone 2) is taken as t1=d2/d1=0.19, ratio t2 for the area I of the beam diameter that incides detecting device (zone 1) and the breadth extreme of the central axis direction of regional J (zone 2) is taken as t2=d3/d1=0.5, for the central axis direction perpendicular to area I (zone 1) and regional J (zone 2), the tilt angle theta of the profile in zone is taken as θ=10deg.

The JP-A-9-223321 of Figure 17 A, 17B most object lens displacement place in the ratio at top becomes negative value.And Di Bu ratio becomes positive value as can be known, and deviation takes place.

In contrast, the displacement of the ratio of the ratio at top of the present invention, bottom, object lens for just, can suppress the not deviation on the border of posting field and posting field in nearly all scope as can be known.

Next the effect that the cut-off rule that makes area I, regional J is tilted describes.Figure 18 A, 18B are the results that the situation of situation about not tilting and inclination is carried out emulation, and Figure 18 A represents the ratio at top, and Figure 18 B represents the ratio of bottom.And the condition as light accepting part is taken as t1=0.19, t2=0.5, θ=10deg and t1=0.19, t2=0.5, θ=0deg.

In the ratio at top, in nearly all zone of the displacement of object lens, be positive value, in addition, the ratio of bottom is greatly improved in for negative zone in the object lens displacement.Like this, the situation that cut-off rule is tilted can suppress the not deviation on the border of posting field and posting field.Be 0 degree＜θ＜15 degree particularly at θ, t1, t2 are for the light beam of the light accepting part that incides detecting device 10, can obtain DC deviation and the deviation on the border of posting field and posting field big effect of improving in suppressing not under the condition of diameter 0＜t1＜0.35,0＜t2＜0.70.

If merely consider, if then as shown in Figure 14 along with area I and regional J leave in the approximate vertical direction from central shaft 500, the width of central shaft 500 directions narrows, for the object lens displacement, can think because the area of the interference region (interference region Z1 or interference region Z2) of the detection in the light accepting part zone (area I or regional J) of object lens sense of displacement reduces, so the tracking error signal amplitude reduces terrifically.But, in fact, with object lens displacement while, the intensity distributions displacement of the twice of object lens displacement, light beam on the object lens sense of displacement.Therefore, on the light accepting part zone of object lens sense of displacement (area I or regional J), though area reduces strength-enhanced.In addition, on the light accepting part zone (regional J or area I) opposite with the object lens sense of displacement, intensity weakens and the area increasing.The tracking error signal amplitude is difficult to reduce thus, becomes the DC drift correction and also is easy to constitute.And then, because the deviation on the border of posting field and posting field does not take place near interference region (interference region Z1 or interference region Z2) significantly, so displacement for object lens, make the outside of interference region incide the light accepting part of DC deviation detection side, it is effective suppressing in the deviation on the border of posting field and posting field not.

Though it can be to have the straight line of other angle to the straight line of track almost parallel with from it that Figure 14 represents the cut-off rule of detecting device inboard, also can be as Figure 19 A, the cut-off rule of light accepting part inboard is a circular arc, is that straight line is also no problem as Figure 19 B.

In addition, though be expressed as the pattern of light accepting part here, even but certainly as the optical system of Figure 20, disposing diffraction grating 61 with the same pattern of pattern of light accepting part, interior diffraction direction, a plurality of light accepting parts place detection signal of angle on detecting device in zone that changes separately also has same effect.

[embodiment 5]

The pattern of the light accepting part different that Figure 21 represents the fifth embodiment of the present invention with embodiment 4.Be to be provided with middle section Y (zone 5) with embodiment 4 different.Middle section is t3 to the ratio of the axial length of beam diameter central authorities of the light accepting part that is incident in detecting device 108, is t4 perpendicular to the ratio of the length of the direction of the axis of centres.If this light accepting part carries out following computing then can generate tracking error signal.

(tracking error signal)=(C-D)-k{ (A-B)+(E-F) } (formula 2)

Figure 22 A represents to use the light accepting part of the present invention and JP-A-9-223321 and the ratio at the top of object lens when the orbital direction top offset, and Figure 22 B represents the ratio of bottom.Condition as light accepting part of the present invention is taken as t1=0.19, t2=0.54, and t3=0.19, t4=0.19, θ=10deg calculates.

According to Figure 22 A, 22B, the tracking error signal of JP-A-9-223321, the characteristic on the border of posting field and posting field is along with the change in displacement of object lens is very big.In contrast, the displacement of tracking error signal of the present invention and object lens is irrelevant.Therefore, do not need the displacement of object lens is controlled especially.In addition, the displacement of object lens for just, can suppress the not deviation on the border of posting field and posting field in nearly all scope as can be known.

Thus, even also can carry out stable tracking Control by being taken as this detecting device pattern object lens of the present invention displacement.Be 0 degree＜θ＜15 degree particularly at θ, t1, t2, t3, t4 are 0＜t1＜0.35 to the beam diameter of the light accepting part that is incident in detecting

device

10,0＜t2＜0.70, under the condition of 0＜t3＜0.35,0＜t4＜0.35 the DC deviation and not the deviation on the border of posting field and posting field suppress to improve effect.

In embodiment 4 also as mentioned above because the deviation on the border of posting field and posting field does not take place near interference region (interference region Z1 or interference region Z2) significantly, so the central portion of detection faces is not easy to influence.And then, because coefficient k can be taken as suitable value, pretend to the result improves not the deviation on the border of posting field and posting field and suppress effect and become possibility by not detecting this zone as tracking error signal.

Though it can be to have the straight line of other angle to the straight line of track almost parallel with from it that Figure 21 represents the cut-off rule of detecting device inboard, can as Figure 23 A, the cut-off rule of light accepting part inboard be circular arc also, be straight line is also no problem as Figure 23 B.

In addition, though be expressed as the pattern of light accepting part here, even certainly dispose the diffraction grating 61 with the same pattern of pattern of light accepting part as embodiment 4, a plurality of light accepting parts place detection signal on detecting device also has same effect.

[embodiment 6]

Figure 24 represents the optical system of the optical Pickup device of the sixth embodiment of the present invention.Give same label to the optics identical with the embodiment of the invention 4 shown in Fig. 13.Though here BD is described, also can be HD DVD or other recording modes.

From semiconductor laser 50, penetrate the roughly light beam of 405nm of wavelength as diverging light.The light beam that penetrates from semiconductor laser 50 is reflected by spectroscope 52.Yi Bufen light beam sees through spectroscope 52 and is incident in preposition monitor 53 in addition.Be transformed into the light beam of almost parallel by collimation lens 51 by spectroscope 52 beam reflected.The light beam that sees through collimation lens 51 incides optical beam expander 54.The light beam of outgoing beam extender 54 is straightened catoptron 55 reflections, through behind 1/4 wavelength plate 56, is converged on the CD 100 by the object lens 102 that are equipped on actuator 5.

See through

object lens

2,1/4 wavelength plate 56, erect catoptron 55, optical beam expander 54, collimation lens 51, spectroscope 52 by CD 100 beam reflected.

See through the light beam of spectroscope 52, be branched off into light beam that generates focus error signal (0 diffraction light) and the light beam that generates tracking error signal (+1 diffraction light or-1 diffraction light) by diffraction grating 63.Here, though in the diffraction grating of Figure 14 of embodiment 4, be illustrated, even the diffraction grating of Figure 21 of Figure 19 A of embodiment 1 or Figure 19 B or embodiment 5 or Figure 23 A or Figure 23 B is also no problem.

Light beam by 63 branches of diffraction grating incides the detection lens.Detecting the lens place, light beam provides the astigmatism of regulation when seeing through, and is used for focus error signal and detects.In addition, because provide astigmatism, spherical aberration when generating diffracted grating 63 diffraction of the light beam of tracking error signal, converge on the light accepting part so see through the light beam of detection lens 59.

Figure 25 A, 25B represent detecting device 64 and the light beam that is detected.Detecting device 64 is divided into the zone 40～43 and tracking error signal zone 44～47 that focus detection is used.Because about focus error signal is known, its explanation of Therefore, omited.The light beam of diffracted grating 63 diffraction is because in separately location diffraction direction difference, so the light beam of the regional G institute diffraction of Figure 12 incides the zone 45 of Figure 25 A, 25B, incided zone 46 by the light beam of regional H diffraction, incided zone 44 by the light beam of area I diffraction, incided zone 47 by the light beam of regional J diffraction.Generate tracking error signal thus.Here the RF signal can detect by getting focus error signal sum or tracking error signal sum or focus error signal and tracking error signal sum.In addition, for the DPD of the tracking error signal detection mode that adopted among the DVD-ROM etc. (DifferentialPhase Ditection: differential phase detection) also be to use the detection signal in the zone 40～43 that focusing error uses promptly can be corresponding.

Constitute by being taken as this optical system, not only can obtain tracking error signal but also can obtain other signals.Though diffraction grating 63 is configured in detection side here, uses polarizing diffraction grating 65 as shown in Figure 26 and be configured in that to approach the object lens place also no problem.

[embodiment 7]

Figure 27 represents the optical system of the optical Pickup device of the seventh embodiment of the present invention.Give same label to the optics identical with the embodiment of the invention 4 shown in Fig. 13.Though here BD is described, also can be HD DVD or other recording modes.

From semiconductor laser 90, the wavelength roughly light beam of 405nm penetrates the light beam of P polarized light as diverging light.The light beam that penetrates from semiconductor laser 90 sees through spectroscope 91, and mirror 92 reflections are reflected.Wherein the outer a part of light beam of effective diameter incides preposition monitor 93.Mirror 92 beam reflected that are reflected incide attachment lens 94, collimation lens 95.Because can on the direction of optical axis, drive collimation lens 95, so by changing the spherical aberration that the dispersing of light beam, tectal thickness error that convergence state can compensate CD 100 cause by drive unit (not shown).

The light beam that sees through the P polarized light of collimation lens 95 incides polarizing diffraction grating 66 of the present invention.The light beam that incides the P polarized light of polarizing diffraction grating 66 sees through same as before, is straightened catoptron 96 reflections, becomes circularly polarized light through behind 1/4 wavelength plate 97.The light beam that becomes circularly polarized light is converged on the CD 100 by the object lens 102 that are equipped on actuator 105.

See through

object lens

102,1/4 wavelength plate 97 by CD 100 beam reflected.The light beam of circularly polarized light becomes the S polarized light by 1/4 wavelength plate 97.The light beam of S polarized light is straightened catoptron 96 reflections, incides polarizing diffraction grating 66.The S polarized light of incident is divided into a plurality of light beams by polarizing diffraction grating 66.The light beam that sees through polarizing diffraction grating 66 is reflected by spectroscope 91 via collimation lens 95, attachment lens 94, catoptron 92, incides detecting device 67.

Figure 28,29 expressions are not only considered tracking error signal but also are considered pattern (Figure 28), the detecting device 67 (Figure 29) of the polarizing diffraction grating 66 of focus error signal.Polarizing diffraction grating 66 is diffraction ± 1 time diffraction of light gratings only, and the light beam of diffraction is different with angle of diffraction in location diffraction direction separately.For the sake of simplicity, in Figure 29, with the textual representation in zone light beam from the area diffraction separately of polarizing diffraction grating shown in Figure 28.In addition, the subscript type of this literal is+by+1 diffraction light of expression, for--1 diffraction light of expression then.For example the area L of Figure 28 polarizing diffraction grating 66+74 ,-1 diffraction light in zone that 1 diffraction light incides Figure 29 detecting device 67 incides zone 83.

The focus error signal detection mode is an edge of a knife mode, utilizes-1 diffraction light by regional N, the P of polarizing diffraction grating 66, Q, O diffraction to detect.Because edge of a knife mode is known, its explanation of Therefore, omited.Tracking error signal detects with the detection signal in zone 70～79, zone 81～84 and tries to achieve by carrying out following computing.

(tracking error signal)={ (N ₊+ L ₊)+(P ₊+ R ₊)-(O ₊+ M ₊)+(Q ₊+ S ₊)-k{ (L _-+ R _-)+(M _-+ S _-) (formula 3)

Polarizing diffraction grating 66 is for focus detection etc. and be divided into a plurality of zones, is Figure 21 similar detection mode with embodiment 2 from the viewpoint of tracking error signal.

And then the RF input uses the detection signal in zone 70～79 to try to achieve by carrying out following computing.

(RF signal)=N ₊+ P ₊+ Q ₊+ O ₊+ L ₊+ R ₊+ S ₊+ M ₊+ T ₊+ U ₊(formula 4)

The DPD input is tried to achieve by carrying out following computing with the detection signal in zone 70～77 in addition.

(DPD signal)={ (N ₊+ L ₊)+(Q ₊+ S ₊)-((P ₊+ R ₊)+(O+M ₊)) (formula 5)

Constitute not only tracking error signal but also obtain other signals and become possibility by being taken as this optical system.

[embodiment 8]

In embodiment 8, the optical reproducing apparatus that is equipped with optical Pickup device 1 is described.Figure 30 is that the summary of optical reproducing apparatus constitutes.Optical Pickup device 101 is provided with the mechanism that can drive along the radial direction of CD 100, carries out position control according to the access control signal from access-control scheme 172.

From laser instrument lighting circuit 177 laser drive current of regulation is supplied to semiconductor laser in the optical Pickup device 101, penetrate laser according to the light quantity of reproducing with regulation from semiconductor laser.In addition, laser instrument lighting circuit 177 also can be packed in the optical Pickup device 101.

The signal that photodetector in optical Pickup device 101 is exported sends to servosignal generative circuit 174 and information signal reproducing circuit 175.In servosignal generative circuit 174, generate servosignals such as focus error signal, tracking error signal and skewed control signal based on signal from above-mentioned photodetector, via the actuator that actuator driving circuit 173 drives in the optical Pickup device 101, carry out the position control of object lens based on these.

In above-mentioned information signal reproducing circuit 175, be recorded in information signal in the CD 100 based on signal reproduction from above-mentioned photodetector.

The part of resulting signal sends to control circuit 176 in above-mentioned servosignal generative circuit 174 and information signal reproducing circuit 175.On this control circuit 176, be connected with spindle drive motor driving circuit 171, access-control scheme 172, servosignal generative circuit 174, laser instrument lighting circuit 177, spherical aberration correction element driving circuit 179 etc., make the correction etc. of the different spherical aberrations that cause of control, disc substrate thickness of servocontrol, the semiconductor laser amount of emitted light in the optical Pickup device 101 of control, object lens of Spin Control, access direction and access site of the spindle drive motor 180 of CD 100 rotation.

[embodiment 9]

In embodiment 9, the optical recording transcriber that is equipped with optical Pickup device 101 is described.Figure 31 is that the summary of optical recording transcriber constitutes.In this device with above-mentioned Figure 30 in the difference of the optical information reproducing apparatus that illustrates be, between control circuit 176 and laser instrument lighting circuit 177, be provided with information signal recording circuit 178, carry out the control of lighting of laser instrument lighting circuit 177 based on record controls signal, the additional function that writes the information of expectation to CD 100 from information signal recording circuit 178.

Claims

1. optical head is used for light beam irradiates is left with predetermined distance and the CD of a plurality of information recording layers of lamination mutually having, and detects the folded light beam from described CD, it is characterized in that having:

Light source;

Be used for to converge in from the light beam that described light source penetrates the object lens on the described CD;

Be used for to be divided into the cutting element of multiple light beams by the light beam of described CD reflection;

Be used to converge collector lens by the light beam of described CD reflection; And

Be used for being transformed into the photodetector of electric signal by a plurality of light accepting parts receptions by the light beam that described collector lens converges,

Wherein, described cutting element has:

Be configured in first cut zone of substantial middle;

Distinguished by first cut-off rule, and second cut zone that constitutes of four zones that dispose across described first cut zone by the direction along first cut-off rule; And

Distinguished with second cut-off rule of the described first cut-off rule quadrature, and the 3rd cut zone that constitutes of four zones that dispose across described first cut zone by the direction along described second cut-off rule,

Each zone of described first to the 3rd cut zone constitutes: when the purpose information recording layer focusing at described CD, folded light beam from described purpose information recording layer focuses on the light accepting part of described photodetector, does not shine the described light accepting part of described photodetector from the folded light beam of the record-playback layer beyond the described purpose information recording layer.

2. optical head as claimed in claim 1 is characterized in that:

The focus error signal that produces by the beam detection knife-edge method by described second cut zone,

By beam detection tracking error signal by described second cut zone and the 3rd cut zone,

By the drift correction signal of the described tracking error signal of beam detection by described the 3rd cut zone,

By beam detection reproducing signal by described first, second and the 3rd cut zone.

3. optical head as claimed in claim 1 is characterized in that:

On each zone of described cutting element, be formed with diffraction grating,

By-1 diffraction light detection of focus error signal by the described second cut zone diffraction,

Use by the described second and the 3rd cut zone diffraction+1 diffraction light detects tracking error signal,

By detecting the drift correction signal of tracking error signal by-1 diffraction light of described the 3rd cut zone diffraction,

By by described first, second and the 3rd cut zone diffraction+1 time the diffraction light sum detects reproducing signal.

4. optical head as claimed in claim 3 is characterized in that:

Described diffraction grating form make by each area diffraction of described cutting element+light quantity of 1 diffraction light is greater than the light quantity of-1 diffraction light.

5. an optical disc apparatus is characterized in that, comprising:

The described optical head of claim 1;

Be used to drive the drive circuit for laser of described light source;

Be used for generating the servosignal generative circuit of servosignal according to the output signal of the photodetector of described optical head;

Be used for reproducing the information signal reproducing circuit of the information that is recorded in described CD according to the output signal of the photodetector of described optical head; And

Control the system, control circuit of described drive circuit for laser, described servosignal generative circuit and described information signal reproducing circuit.

6. optical Pickup device is characterized in that having:

Penetrate the semiconductor laser of laser;

Will be from the object lens of light beam irradiates on CD of described semiconductor laser ejaculation; And

Reception is from the photodetector of the light beam of CD reflection,

Wherein, described photodetector comprise have zone 1, the light accepting part in zone 2, zone 3, four zones such as 4, zone,

The zone 1 of described light accepting part and zone 3 and zone 2 and zone 4 center line line symmetries with respect to described light accepting part,

The zone 1 of described light accepting part and regional 2 is narrowed width along with leaving described center line,

Output is by zone 1, zone 2, zone 3, the zone 4 detected signals of described light accepting part.

7. optical Pickup device is characterized in that having:

Penetrate the semiconductor laser of laser;

Will be from the object lens of light beam irradiates on CD of described semiconductor laser ejaculation;

Make from the diffraction grating of the light beam branch of CD reflection; And

Reception is by the photodetector of the light beam of described diffraction grating branch,

Wherein, described diffraction grating has four zones in zone 1, zone 2, zone 3, zone 4,

Described diffraction grating area 1 and zone 3 and zone 2 and zone 4 center line line symmetries with respect to described diffraction grating,

Described diffraction grating area 1 and regional 2 is narrowed width along with leaving described center line,

Output is according to the detected signal of diffraction light in described diffraction grating area 1, zone 2, zone 3, zone 4.

8. optical Pickup device is characterized in that having:

Penetrate the semiconductor laser of laser;

Reception is from the photodetector of the light beam of CD reflection,

Wherein, described photodetector comprise have zone 1, the light accepting part in zone 2, zone 3, zone 4, five zones such as 5, zone,

The zone 5 of described light accepting part is formed on the described center line and with respect to described center line line symmetry,

9. optical Pickup device is characterized in that having:

Penetrate the semiconductor laser of laser;

Wherein, described diffraction grating has five zones in zone 1, zone 2, zone 3, zone 4, zone 5,

Described diffraction grating area 5 is formed on the described center line and with respect to described center line line symmetry,

10. optical Pickup device is characterized in that having:

Penetrate the semiconductor laser of laser;

Reception is from the photodetector of the light beam of CD reflection,

Wherein, described photodetector comprise have zone 1, zone 2, zone 3, zone 4, zone 5, zone 6, zone 7 light accepting part,

The zone 1 of described light accepting part and zone 3 and zone 6 and zone 2 and zone 4 and zone 7 center line line symmetries with respect to described light accepting part,

The zone 5 of described light accepting part further is subdivided into four zones in zone 8, zone 9, zone 10, zone 11, and zone 8 and zone 10 form with respect to described center line line symmetry with zone 9 and zone 11,

The zone 1 of described light accepting part and zone 2 be narrowed width along with leaving described center line, and zone 1 further is divided into two on the direction vertical with described center line with regional 2,

Output is by zone 1, zone 2, zone 3, zone 4, zone 5, zone 6, the zone 7 detected signals of described light accepting part.

11. an optical Pickup device is characterized in that having:

Penetrate the semiconductor laser of laser;

Wherein, described diffraction grating has zone 1, zone 2, zone 3, zone 4, zone 5, zone 6, zone 7,

Described diffraction grating area 1 and zone 3 and zone 6 and zone 2 and zone 4 and zone 7 center line line symmetries with respect to described diffraction grating,

Described diffraction grating area 5 further is subdivided into four zones in zone 8, zone 9, zone 10, zone 11, and zone 8 and zone 10 form with respect to described center line line symmetry with zone 9 and zone 11,

Described diffraction grating area 1 and zone 2 be narrowed width along with leaving described center line, and zone 1 further is divided into two on the direction vertical with described center line with regional 2,

Output is according to the detected signal of diffraction light in described diffraction grating area 1, zone 2, zone 3, zone 4, zone 5, zone 6, zone 7.

12., it is characterized in that as each described optical Pickup device in the claim 6～11:

Described regional 1 has the limit that has tilt angle theta with respect to the direction vertical with described center line with zone 2 regional profile,

Described tilt angle theta is 0 degree＜θ＜15 degree.

13. an optical disc apparatus is characterized in that having:

Each described optical Pickup device in the claim 6～11; With

Use generates the servosignal generative circuit of tracking error signal from the signal of described optical Pickup device output,

Described servosignal generative circuit generates tracking error signal with formula (A1-A2)-k * (A3-A4), wherein, sets:

Incide described regionally 1, the signal that is detected by described detecting device is A1;

Incide described regionally 2, the signal that is detected by described detecting device is A2;

Incide described regionally 3, the signal that is detected by described detecting device is A3;

Incide described regionally 4, the signal that is detected by described detecting device is A4;

Revising described regional 1, zone 2 is k with the coefficient of the light quantity in zone 3, zone 4.