CN1897131A - Optical head and disk reproducing apparatus - Google Patents
Optical head and disk reproducing apparatus Download PDFInfo
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- CN1897131A CN1897131A CN 200610106385 CN200610106385A CN1897131A CN 1897131 A CN1897131 A CN 1897131A CN 200610106385 CN200610106385 CN 200610106385 CN 200610106385 A CN200610106385 A CN 200610106385A CN 1897131 A CN1897131 A CN 1897131A
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Abstract
There is provided an optical head which have no such problems regarding increase in cost and size thereof and can reduce errors by suppressing crosstalk components attributable to reflection on lands of a magneto-optical recording medium and thereby prevent degradation of reproduction characteristics. An optical element (24) includes a light separating section (30) for separating outgoing light and return light, and a phase compensation section (31) for imparting phase compensation to light incident thereon. The optical element (24) is provided on a light path of return light between an objective lens (26) and a photodetector (28), so as to be closer to the photodetector than the light separating section is. This makes it possible to impart the phase compensation to the return light and prevent the degradation of reproduction characteristics. Light separating elements such as beam splitter are no more necessary in the configuration, with the result that decreases in size and cost can be realized.
Description
Technical field
The present invention relates to a kind of optical head and apparatus for replaying disc.
Background technology
Registered trademark) and the record of Hi-MD (registered trademark) and/or the device of playback comprise in the apparatus for replaying disc and can carry out the different multiple Magnetooptic recording medium of physical format, for example carry out MD (Mini Disc:.At least the optical head that apparatus for replaying disc had that carries out the playback of this multiple Magnetooptic recording medium comprises: the light source that penetrates laser; Object lens, the laser focusing that will penetrate from light source is to the information recording surface of Magnetooptic recording medium; Optical system, separate by the information recording surface reflection of Magnetooptic recording medium, as the laser of loop light; And signal conversion part, will be converted to electric signal by the laser that optical system is separated.
In Magnetooptic recording mediums such as MD, Hi-MD, on its information recording surface, be provided with the guiding groove that is called pit.When the playback Magnetooptic recording medium, apparatus for replaying disc passes through from the laser radiation pit of light source ejaculation, and reads the information that writes down in the pit by the reflection of light light of this irradiation.In the last few years, in order to write down more information signal and to reduce track pitch to Magnetooptic recording medium as far as possible, the densification of Magnetooptic recording medium was developed.
The track pitch of the MD that uses in the prior art is 1.6 μ m, and the track pitch of the Hi-MD of Kai Fa realized high density recording in recent years is 1.25 μ m.And, record EFM (Eight to Fourteen Modulation in the pit of MD, 8 to 14 modulation methods) data of having modulated, record RLL (1-7) PP (RLL:Run Length Limited, the run length of the physical format of employing in the pit of Hi-MD as the high-density recording higher than MD density; PP:Parity preserve/Prohibit rmtr (Repeated Minimum TransitionRunlength), odd even keeps/the minimum transition distance of swimming repeats control) data of modulation.As have compatible optical head between different MD of physical format and Hi-MD, using from the Wavelength of Laser of light source ejaculation is 0.45 device as the numerical aperture NA of 780nm, object lens.
When using this optical head, the spot diameter of the laser that penetrates from light source is greater than track pitch, and spot diameter overflows from pit sometimes.The surface reflection of the base station that the light quilt that overflows from pit is adjacent with pit is blended in the light that is reflected by pit, is converted to electric signal together.This phenomenon is called crosstalks, and sneaks in the reflected light because of pit in other light electrical signal converted, for example information playback signal (RF signal), produces more dislocation, becomes the reason that causes playback performance to descend.
Therefore following optical head has been proposed:, prevent playback performance descend (for example opening 2003-296960 communique (14-15 page or leaf, Figure 16)) with reference to the spy by the phase compensation element limits is installed from the crosstalk components of base station and reduce error in from the catoptrical light path of Magnetooptic recording medium.
Figure 15 is the concise and to the point outboard profile that the spy opens the formation of the disclosed optical head 1 of 2003-296960 communique.Optical head 1 as the discrete optical system has: the semiconductor Laser device 2 that penetrates laser; Separation is from the grating 3 of the light of semiconductor Laser device 2 ejaculations; See through or reflect the spectroscope 4 of incident light; Making incident light is the collimation lens 5 of directional light; With the object lens 6 of laser focusing to Magnetooptic recording medium 11; Regulate the phase compensation element 7 of the phase place of incident light; The wollaston prism 8 of separating incident light; In incident light, produce the cylindrical lens 9 of astigmatism; Be converted to the photodetector 10 as photo detector of electric signal with the light that will inject.
As the semiconductor Laser device 2 of the light source that penetrates light, for example when Magnetooptic recording medium 11 is MD or Hi-MD, penetrate the laser of wavelength 780nm.Semiconductor Laser device 2 is connected with the not shown external circuit that drive current is provided, can be by change the intensity of laser from the magnitude of current of this external circuit.
Grating 3 is that the light that will penetrate from semiconductor Laser device 2 is separated into 0 order diffraction light ,-1 order diffraction light and+1 order diffraction diffraction of light grating.Spectroscope 4 makes from semiconductor Laser device 2 ejaculations and towards the outlet of Magnetooptic recording medium 11 light transmission, and reflection is by the loop light of Magnetooptic recording medium 11 reflections.Collimation lens 5 makes the scattered light that penetrates and be injected into wherein from semiconductor Laser device 2 be directional light and penetrate.
Wollaston prism 8, to reflect by Magnetooptic recording medium 11 reflection, by spectroscope 4 and see through phase compensation element 7 and the loop light injected separates, and make the light transmission cylindrical lens 9 of this separation and be injected in the predetermined light area of following photodetector 10.9 pairs of incident lights of cylindrical lens are given astigmatism, so that photodetector 10 exportable focus error signals (FE signal).Photodetector 10 is the signal conversion parts that formed predetermined light area, and the laser of injecting is converted to electric signal, and exports above-mentioned FE signal, RF signal and tracking error signal (TE signal) by computing.
Laser from semiconductor Laser device 2 penetrates sees through grating 3, spectroscope 4 and collimation lens 5, is injected into object lens 6, and optically focused is to the information recording surface of Magnetooptic recording medium 11.And the laser of optically focused to the information recording surface of Magnetooptic recording medium 11, on the reflecting surface of Magnetooptic recording medium 11, be reflected, see through object lens 6 and collimation lens 5 by spectroscope 4 reflections, and through phase compensation element 7, separated by wollaston prism 8, further see through cylindrical lens 9 and receive by photodetector 10.In photodetector 10, the laser that receives is converted to electric signal, export above-mentioned each signal.
Open in the 2003-296960 communique in the disclosed optical head 1 the spy, the phase place of the light that is reflected by Magnetooptic recording medium 11 is suitably adjusted by phase compensation element 7, because the phase place of the light that is reflected by base station is adjusted, therefore the reduction of crosstalking all can prevent the decline of the playback performance of MD and Hi-MD to Magnetooptic recording medium 11 arbitrarily.
But, open in the 2003-296960 communique in the disclosed optical head 1 the spy because phase compensation element 7 is installed, produce cost than the cost of the optical head that does not use the phase compensation element increase, and the problem of maximization.Therefore need a kind of can not produce that cost increases and optical head maximization problem, can be limited in the crosstalk components that the reflected light of the base station of Magnetooptic recording medium causes and reduce error, can prevent the optical head that playback performance descends.
Summary of the invention
The object of the present invention is to provide a kind of optical head and apparatus for replaying disc, can not produce that cost increases and optical head maximization problem, can be limited in the crosstalk components that the reflected light of the base station of Magnetooptic recording medium causes and reduce error, and can prevent that playback performance from descending.
The present invention is a kind of optical head, writes down and/or playback information to the optical recording media irradiates light, it is characterized in that having: the light source that penetrates light; Object lens that will be from outlet light optically focused that light source penetrates to optical recording media; Reception is penetrated and by the photo detector of the loop light of optical recording media reflection from light source; And be arranged on optical element on the light path of the loop light between object lens and the photo detector, wherein, optical element has: the light separated part of separating outlet light and loop light; With the phase compensation portion that the light of injecting is carried out phase compensation, phase compensation portion is set to than light separated part near photo detector.
According to the present invention, optical head has: the light source that penetrates light; Object lens that will be from outlet light optically focused that light source penetrates to optical recording media; Reception is penetrated and by the photo detector of the loop light of optical recording media reflection from light source; And be arranged on optical element on the light path of the loop light between object lens and the photo detector, that have phase compensation portion.In this optical head, loop light by the optical recording media reflection is injected in the phase compensation portion of optical element, thus incident light is carried out phase compensation, can be limited in the crosstalk components that the reflected light of the base station of optical recording media causes and reduce error, therefore can prevent the decline of playback performance.
Further, optical element has: the light separated part of separating outlet light and loop light; With the phase compensation portion that the light of injecting is carried out phase compensation, wherein, phase compensation portion is provided with than the close photo detector of light separated part.Therefore, for example by making optical element, thereby need not to be provided with the light resolution elements such as spectroscope that when separating outlet light and be directed to optical recording media one side loop light are directed to photo detector one side with loop light and with the outlet light that separates with light separated part and phase compensation integrally.Light resolution elements such as spectroscope, bigger as the optical accessories volume, cost is higher, therefore thisly can not make miniaturization and the cost degradation that can realize optical head with the structure of light resolution element.
And, the invention is characterized in, in optical element, phase compensation portion towards the inclined light shaft setting of the face of a side of photo detector with respect to the loop light between object lens and the photo detector.
And, according to the present invention, since in the optical element phase compensation portion towards the inclined light shaft setting of the face of a side of photo detector with respect to the loop light between object lens and the photo detector, therefore can produce astigmatism to incident light, need not the optical accessories that cylindrical lens etc. is used to produce astigmatism.Therefore, can reduce the accessory number, and realize the further miniaturization of optical head.
And, the invention is characterized in that comprise scattering angle adjustment element, it is configured between optical element and the object lens, adjusts the scattering of light angle that is injected into object lens.
And,,, therefore can realize the miniaturization of optical head and improve coupling efficiency owing to comprise the scattering angle adjustment element that is configured between optical element and the object lens, is used to adjust the scattering of light angle that is injected into object lens according to the present invention.
And the invention is characterized in that phase compensation portion is the phase compensation glass with a plurality of cut zone of cutting apart, in the phase compensation glass, the refractive index of at least one cut zone is different with the refractive index of other cut zone.
And according to the present invention, phase compensation portion is the phase compensation glass with a plurality of cut zone of cutting apart, and in the phase compensation glass, the refractive index of at least one cut zone is different with the refractive index of other cut zone.When scattered light is injected into phase compensation glass, the incident angle of incident light near the optical axis of luminous point with periphery at luminous point near different, the optical path length of the distance of in phase compensation glass, advancing as incident light near the optical axis of luminous point with periphery at luminous point near different, therefore by see through phase changing capacity that phase compensation glass is endowed near the optical axis of luminous point with periphery at luminous point near different, in luminous point, phase changing capacity produces fluctuation, but the phase compensation glass that has a plurality of cut zone of cutting apart by use, can suitably set the refractive index in each cut zone, and make the phase changing capacity unanimity in the luminous point.
And the invention is characterized in that the direction that a plurality of cut zone of phase compensation glass are arranged is parallel with the radial direction of the optical recording media that is in record or playback mode.
And according to the present invention, the direction that a plurality of cut zone of phase compensation glass are arranged is parallel with the radial direction of the optical recording media that is in record or playback mode.In the luminous point of the light that is injected into phase compensation glass, do not contain the information playback signal in the light of the radial direction periphery of luminous point.Therefore on the radial direction of luminous point, the incident angle of the critical portion of the part that contains the part of information playback signal and do not contain, incident angle than the periphery in the tangential direction vertical with radial direction is little, therefore with on tangential direction, give phase compensation and compare, giving phase compensation can be carried out unanimity in luminous point phase change on the radial direction, so the difference of its phase compensation amount of giving is less.Given this, preferably on radial direction, give phase compensation, parallel by the direction that cut zone is arranged with the radial direction of optical recording media, be reduced in the difference of the phase compensation amount of giving in the luminous point, can more easily make the interior phase change unanimity of luminous point.
And, the invention is characterized in that phase compensation portion has: liquid crystal cell, it has a plurality of cut zone of cutting apart; Voltage application portion applies voltage respectively to a plurality of cut zone of liquid crystal cell, and makes the variations in refractive index of each cut zone; And control part, the phase compensation amount that adjustment applies according to each cut zone respectively the light of the cut zone that is injected into liquid crystal cell, and control applies the action of the voltage application portion of voltage to the cut zone of liquid crystal cell, is applied in consistent phase change so that seen through the luminous point of liquid crystal cell in this luminous point.
And according to the present invention, phase compensation portion has: liquid crystal cell, and it has a plurality of cut zone of cutting apart; Voltage application portion applies voltage respectively and makes the variations in refractive index of each cut zone a plurality of cut zone of liquid crystal cell; And control part, control applies the action of the voltage application portion of voltage to the cut zone of liquid crystal cell.The phase compensation amount that the control part adjustment applies according to each cut zone the light of the cut zone that is injected into liquid crystal cell, and the action of control voltage application portion are applied in consistent phase change so that seen through the luminous point of liquid crystal cell in this luminous point.Therefore, can reduce the poor of phase changing capacity in the luminous point that the incident angle because of the light that is injected into liquid crystal cell causes, further improve the playback performance of optical recording media.Further, when being equipped on when between multiple optical recording media, having compatible apparatus for replaying disc, all can give best phase compensation amount to any one of this multiple optical recording media.
And, the invention is characterized in that liquid crystal cell is with respect to the inclined light shaft setting of the loop light between light separated part and the photo detector.
And,,, need not the optical accessories that cylindrical lens etc. produces astigmatism because liquid crystal cell with respect to the inclined light shaft setting of the loop light between light separated part and the photo detector, therefore can produce astigmatism to incident light according to the present invention.Therefore can reduce the accessory number, realize the miniaturization of optical head.
And, the invention is characterized in that each cut zone of liquid crystal cell has transparency electrode.
Therefore and according to the present invention, as the electrode that is used for applying to liquid crystal cell voltage, the transparency electrode of having used each cut zone all to have can prevent that light from being covered by electrode and the light intensity that produces descends.
And, the invention is characterized in that the direction that a plurality of cut zone of liquid crystal cell are arranged is parallel with the radial direction of the optical recording media that is in record or playback mode.
And, according to the present invention, because the direction that a plurality of cut zone of liquid crystal cell are arranged is parallel with the radial direction of the optical recording media that is in record or playback mode, therefore as mentioned above, can be reduced to the difference that makes the phase compensation amount that in luminous point, carries out consistent phase change and give.
And, the invention is characterized in that the direction that liquid crystal cell tilts with respect to the optical axis of the loop light between light separated part and the photo detector is the radial direction that is in the optical recording media of record or playback mode.
And, according to the present invention, the direction that tilts with respect to the optical axis of the loop light between light separated part and the photo detector owing to liquid crystal cell is the radial direction that is in the optical recording media of record or playback mode, therefore as mentioned above, on radial direction, the be arranged in parallel liquid crystal cell of cut zone of utilization, the phase change unanimity in the luminous point can be made, and astigmatism can be produced.
And, the invention is characterized in that comprise the scattering angle adjustment element that the scattering of light angle that is injected into object lens is adjusted, scattering angle is adjusted element and is configured between light source and the object lens.
And, according to the present invention, adjust element owing to have the scattering angles such as coupled lens that are configured between light source and the object lens, are used to adjust the scattering of light angle that is injected into object lens, therefore can realize the miniaturization of optical head and improve coupling efficiency.
And, the invention is characterized in, comprise the anisotropy element, its will by optical recording media reflection and by the light separating part from, separate from the loop light of optical recording media, and be injected in the photo detector, the anisotropy element is configured between liquid crystal cell and the photo detector.
And, according to the present invention, since have be configured between liquid crystal cell and the photo detector, be used for by optical recording media reflection and by the light separating part from separate and be injected into the anisotropy elements such as wollaston prism of photo detector from the loop light of optical recording media, therefore can make light be injected in the light area that photo detector has acquired information replay signal etc.
And, the invention is characterized in that it is the following laser of 780nm that light source penetrates wavelength, the numerical aperture NA of object lens is more than 0.45.
And, according to the present invention, be the following laser of 780nm because light source penetrates wavelength, the numerical aperture NA of object lens is more than 0.45, therefore can obtain the good information replay signal by corresponding various optical recording medias.
And, the invention provides a kind of apparatus for replaying disc, it is characterized in that having above-mentioned optical head.
And, according to the present invention, owing to have above-mentioned any one optical head, therefore can provide a kind of apparatus for replaying disc, it can not increase cost and not produce the maximization problem, can limit the crosstalk components that the reflected light of the base station of optical recording media produces and reduce error, can prevent the decline of playback performance.And apparatus for replaying disc is not defined as the device of only information that is recorded in the optical recording media being reset, and it comprises the device that records information to optical recording media and the information that records optical recording media is reset.
Purpose of the present invention, characteristic, and advantage can be able to clearly by the following detailed description and the accompanying drawings.
Description of drawings
Fig. 1 is the outboard profile of reduced representation as the formation of the optical head of one embodiment of the present invention.
Fig. 2 is illustrated in the concise and to the point vertical view that forms the form of luminous point on the information recording surface of optical recording media.
Fig. 3 is the vertical view of the formation of schematic representation phase compensation glass.
Fig. 4 is the vertical view of the formation of a plurality of light areas of being provided with on the schematic representation photodetector.
Fig. 5 is the circuit diagram of the electrical structure of expression photodetector.
Fig. 6 is the sectional view of reduced representation as the formation of the optical head of second embodiment of the invention.
Fig. 7 is the vertical view of the formation of schematic representation liquid crystal cell.
Fig. 8 A and Fig. 8 B represent that schematically scattered light is injected into the sectional view of the form of liquid crystal cell.
Fig. 9 be expression for the scattered light that is injected into undivided liquid crystal cell, on average give incident light when all with the phase compensation amount of the best on the optical axis center, the figure of the phase changing capacity that everybody of spot radius direction deposits.
Figure 10 is the expression liquid crystal cell with a plurality of cut zone shown in Figure 7 to the figure of the phase compensation amount of giving as the incident light of scattered light.
Figure 11 is the process flow diagram of the controlled step of the control part of expression when liquid crystal cell applies voltage.
Figure 12 is expression to being injected into scattered light with the liquid crystal cell that is divided into a plurality of cut zone, the figure of phase changing capacity when giving phase compensation amount according to each cut zone.
Figure 13 is expression by the error rate that is not split into the optical recording media playback time of a plurality of liquid crystal cells when giving phase compensation, and the figure of the error rate of optical recording media playback time when giving phase compensation by the liquid crystal cell with a plurality of cut zone.
Figure 14 is the outboard profile of reduced representation as the formation of the optical head of third embodiment of the invention.
Figure 15 is the outboard profile that the schematic representation spy opens the formation of disclosed optical head in the 2003-296960 communique.
Embodiment
Followingly preferred implementation of the present invention is elaborated with reference to accompanying drawing.
Fig. 1 is the outboard profile of reduced representation as the formation of the optical head 21 of one embodiment of the present invention.Optical head 21 comprises: semiconductor Laser device 22, grating 23, optical element 24, scattering angle are adjusted element 25, object lens 26, wollaston prism 27 and photodetector 28.
The optical head 21 of present embodiment is characterised in that, optical element 24 is set on the light path of the loop light (Complex road light) between object lens 26 and the photodetector 28, and this optical element 24 comprises: light separated part 30, separate outlet light (toward road light) and loop light; With phase compensation glass 31, give phase compensation to the light of injecting as phase compensation portion.
And in the present invention, " phase compensation amount " is meant the amount of the phase change that phase compensation portion gives incident light, and " phase changing capacity " is meant the variable quantity of phase place of having been given the light of phase compensation amount by phase compensation portion.
For example can use half-mirror etc. as light separated part 30.In the light separated part 30 and towards the face of the opposite side of a side of phase compensation glass 31, be set to respect to following two inclined light shafts: the optical axis that penetrates and be injected into the outlet light of light separated part 30 from semiconductor Laser device 22; And penetrate, reflected and be injected into the optical axis of loop light by optical recording media 29 from semiconductor Laser device 22.In the light separated part 30 of present embodiment, the outlet light that reflection is penetrated from semiconductor Laser device 22 also is directed to object lens 26, sees through the loop light that penetrates and reflected by optical recording media 29 from semiconductor Laser device 22.
Scattering angle adjustment unit 25 is arranged between optical element 24 and the object lens 26, adjusts the scattering of light angle that is injected into object lens 26.As scattering angle adjustment unit 25, for example can use incident light as the collimation lens of directional light, change the coupled lens etc. of the scattering angle of incident light.Wherein, preferred use can realize optical head 21 in the miniaturization on the emergent light optical axis direction and the miniaturization on object lens 26 focus direction and can improve coupled lens from the outgoing light intensity of object lens 26.The light of having been adjusted scattering angle by scattering angle adjustment element 25 is injected in the object lens 26.
The light optically focused that object lens 26 will penetrate from semiconductor Laser device 22 is to optical recording media 29.Object lens 26, for example, when optical recording media 29 was optical recording media such as Magnetooptic recording medium such as MD, Hi-MD or CD, using numerical aperture NA was 0.45 object lens.And when optical recording media 29 was optical recording media such as DVD, using numerical aperture NA was 0.6 object lens; When optical recording media 29 was optical recording media such as Blu-ray disc, using numerical aperture NA was 0.85 object lens.
Fig. 2 is illustrated in the concise and to the point vertical view that forms the form of luminous point 41 on the information recording surface of optical recording media 29.On the information recording surface of optical recording media 29, form the pit 42 of the guiding groove shape of recorded information replay signal.In addition, three-dimensional X-Y-Z axle shown in Figure 2 is carried out as giving a definition.If with the vertical direction (focus direction) of information recording surface of the optical recording media 29 that is in record or playback mode is X-direction, be Y direction if be in the radial direction (tracking direction) of the optical recording media 29 of record or playback mode, direction, promptly vertical with the tracking direction direction (tangential direction) of establishing pit 42 extensions of optical recording media 29 are Z-direction.The radial direction of optical recording media 29 of expression Y direction, be from semiconductor Laser device 22 penetrate and the optical axis of the light of optically focused to the information recording surface of optical recording media 29 radial direction of optical recording media 29.These X-Y-Z three axial definition are general in this manual.
On playback optical recording media 29 during the information of record, optical head 21 is by the inside of the luminous point 41 irradiation pits 42 of the laser that penetrates from semiconductor Laser device 22, the information that the reflected light of the laser by this irradiation is read record in the pit 42.
When optical recording media 29 was MD, track pitch 43 was 1.6 μ m, when it is that track pitch 43 is 1.25 μ m when realizing the Hi-MD of high density recording.When carry out information record or playback time by 21 pairs of optical recording medias of optical head 29, the diameter of luminous point that penetrates and shine the laser of optical recording media 29 from semiconductor Laser device 22 for example is 1.6 μ m, and this time point 41 overflows from pit 42.
The light of the light point area 41a of the part of overflowing from pit 42, the surface reflection at the base station 44 adjacent with pit 42 is blended in the light that is reflected by pit 42.This phenomenon is called crosstalks, because other light are blended in the light that is reflected by pit 42, therefore be accepted in the following photodetector 28 of this light and produce more mistake in electrical signal converted, for example information playback signal (RF signal), cause the decline of playback performance.
In the optical element 24 of the optical head 21 of present embodiment, in order to prevent the decline of this playback performance, be provided with phase compensation glass 31 as phase compensation portion, it is by giving phase compensation to loop light, restriction is from the crosstalk components of base station 44, and minimizing makes mistakes.Below the formation of phase compensation glass 31 is described.
Fig. 3 is the vertical view of the formation of schematic representation phase compensation glass 31.Phase compensation glass 31 is characterised in that, the shape of overlooking is the flat-shaped part of rectangle, be divided into a plurality of (being three in the present embodiment) cut zone 31a, 31b, 31c by the cut-off rule 51,52 that extends on Z-direction, the direction that a plurality of cut zone 31a, 31b, 31c arrange writes down or the radial direction of the optical recording media 29 of playback mode, is that Y direction is parallel with being in.And, in the present embodiment, a plurality of cut zone 31a, the 31b of phase compensation glass 31, the refractive index of 31c are different separately, set the refractive index of cut zone 31a, 31b, 31c, make the phase change of the light that is injected into each cut zone and gives phase compensation consistent in luminous point.
At this, in the face of injecting at incident light, the problem that produced when being injected into the phase compensation glass of refractive index unanimity of scattered light describes.When light is injected into phase compensation glass, if the incident angle difference of incident light, then this incident light distance of in phase compensation glass, advancing, be the optical path length difference, therefore seen through the phase changing capacity difference of the light of phase compensation glass.The change of this phase changing capacity not only can have problems in the different a plurality of light of incident angle, and when incident light is scattered light, at near the light the optical axis of luminous point, and be between near the periphery of both sides at center the light with the optical axis of luminous point, also can have problems.
Promptly, when scattered light is injected into phase compensation glass, the incident angle of incident light near the optical axis of luminous point with periphery at luminous point near different, so incident light in phase compensation glass forward travel distance, be optical path length, near the optical axis of luminous point with the periphery of luminous point near different.And, when near the optical axis of optical path length at luminous point and near the periphery at luminous point not simultaneously, by seeing through phase changing capacity that phase compensation glass is endowed near the optical axis of luminous point and different between near the periphery at luminous point.Therefore, when using the phase compensation glass of refractive index unanimity in the face that incident light is injected, near the polarized condition of the light the luminous point periphery changes elliptical polarized light into from linear polarization, and phase changing capacity produces fluctuation in luminous point.
At this problem, the phase compensation glass 31 of present embodiment has a plurality of divided cut zone 31a, 31b, 31c, set the refractive index of cut zone 31a, 31b, 31c respectively, make the phase change of the light that is injected into each cut zone and is endowed phase compensation consistent in luminous point.Therefore, can make the phase changing capacity unanimity of light in this luminous point of having given phase compensation by phase compensation glass 31.
And phase compensation glass 31 preferably, carries out phase change so that the polarizing axis of light that is adjusted to linear polarization with the radial direction that is in the record or the optical recording media 29 of playback mode, be that Y direction is parallel.It is the reasons are as follows.
Wherein, because phase place represented by ripple, therefore catoptrical phase place be may be partitioned into P ripple as the ripple of Y direction, and considers as the S ripple of the ripple of Z-direction.When optical recording media 29 is MD, from the catoptrical phase place of optical recording media 29 for having the state (S-P=0 °) of P ripple, S ripple substantially simultaneously.But when optical recording media 29 is Hi-MD, become the state (S-P=δ) of P Bob S ripple delay δ from the reflected light of optical recording media 29.
As mentioned above, on Z-direction, till the periphery of luminous point 41, contain the information playback signal that writes down in the pit 41.Therefore be that the S ripple postpones in the method for δ at the ripple that makes Z-direction, light to the periphery that is injected into phase compensation glass 31 also needs to give phase change, when the phase compensation glass 31 that the optical head 21 that uses present embodiment is had, also can produce the poor of the interior phase changing capacity of small luminous point.
On the other hand, on Y direction, on the periphery of luminous point 41, do not contain the information playback signal of record in the pit 41.Therefore, at the ripple that makes Y direction is that the P ripple shifts to an earlier date in the method for δ, do not contain the information playback signal owing to be injected into the periphery of the light of phase compensation glass 31, even therefore produce the poor of the interior adjacent variable quantity of small luminous point, on the Y direction of luminous point, contain the part of information playback signal and do not contain the incident angle of critical portion of part of this signal littler, do not have the poor of phase changing capacity basically as the information playback signal that is obtained than the incident angle of luminous point periphery.
As mentioned above, on the Y direction of luminous point 41, contain the part of information playback signal and do not contain the incident angle of critical portion of the part of this signal, littler than the incident angle of the periphery in the Z-direction vertical with Y direction.Therefore, compare with give phase change on Z-direction, giving phase change can be carried out unanimity in luminous point phase change on the Y direction, therefore the difference of the phase compensation amount of giving is less.Therefore, each cut zone 31a, 31b, 31c to phase compensation glass 31 give preferred phase change respectively, so that the orientation of the cut zone 31a of phase compensation glass 31,31b, 31c is parallel with the Y direction of optical recording media 29, and be reduced in the difference of the phase compensation amount of giving in the luminous point.Thereby can more easily make the phase change unanimity of luminous point.
Further, the optical element 24 of present embodiment is set to: the face towards a side of photodetector 28 of phase compensation glass 31, and with respect to the inclined light shaft of the loop light between object lens 26 and the photodetector 28.Thereby can be with respect to the incident light that is injected into phase compensation glass 31, promptly the loop light from optical recording media 29 produces astigmatism, its formation can not use cylindrical lens etc. to be used to produce the optical accessories of astigmatism, therefore can reduce the accessory number, realize the further miniaturization of optical head.
And, by making the face tilt towards a side of photodetector 28 of phase compensation glass 31, as the light in the periphery of the luminous point of the incident light of scattered light, with another periphery of the opposite side of this periphery in light between the difference of optical path length might become big, but as described in present embodiment, by cutting apart phase compensation glass 31, and in each cut zone, set appropriate refractive index, even phase compensation glass 31 tilted configuration also can prevent to produce the poor of phase changing capacity in luminous point.
Seen through the loop light from optical recording media 29 of above-mentioned phase compensation glass 31, given phase change and astigmatism, and be injected into wollaston prism 27 by phase compensation glass 31.
Fig. 4 is the vertical view of the formation of a plurality of light areas of setting on the schematic representation photodetector 28.Photodetector 28 for example has: four light areas that will be divided into the rectangle of four equal areas are configured to light area A, B, C, the D of the ranks shape of two row, two row; In the both sides of light area A～D along two light area E, F of the rectangle of Y direction configuration; And in the both sides of light area A～D along two light area I, J of the rectangle of Z-direction configuration.Receive the 0 order diffraction light that is separated by grating 23 in the A～D of light area, the light of this reception produces astigmatism by phase compensation glass 31, and is used for the main signal by wollaston prism 27 separation, exports the FE signal by method of astigmatism in the A～D of this light area.Receive-1 order diffraction light and+1 order diffraction light that is separated by grating 23 and detect the TE signal in light area E, F, the light of above-mentioned reception is used for the main signal by wollaston prism 27 separation.Receive the 0 order diffraction light that is separated by grating 23 and detect the RF signal in light area I, J, the light of above-mentioned reception is used for I, the J signal by wollaston prism 27 separation.
Fig. 5 is the circuit diagram of the electrical structure of expression photodetector 28.Photodetector 28 has: as arithmetical unit OA1, the OA2 of totalizer; Arithmetical unit OA3, OA4, OA5 as subtracter.In photodetector 28,, utilize arithmetical unit OA1～OA5 shown in following formula, to export each electric signal by each light area A～J receiving loop light.And in following formula,, before the letter of each light area of expression, add " S " and represent for from the value shown in the detected signal in each light area.
The FE signal=(SA+SA)-(SB+SD)
TE signal=SE-SF
RF signal=SI-SJ
Below the action of optical head 21 is described.The laser that penetrates from semiconductor Laser device 22, by grating 23 be separated into 0 order diffraction light ,+1 order diffraction light, and-1 order diffraction light, in light separated part 30 reflections of optical element 24.Change by scattering angle adjustment unit 25 its scattering angles in light separated part 30 laser light reflected, by the information recording surface of object lens 26 optically focused to optical recording media 29.The light of optically focused to the optical recording media 29 by optical recording media 29 reflections, sees through object lens 26 and scattering angle and adjusts element 25, and see through the light separated part 30 of optical element 24, be injected into the integrally formed phase compensation glass 31 of light separated part in.
Given the loop light of phase change and astigmatism by phase compensation glass 31, separated by wollaston prism 27, and on the precalculated position of photodetector 28, be subjected to light.Photodetector 28 utilizes each electric signal of the laser output FE signal, TE signal and the FR signal that receive.
As mentioned above, in the optical head 21 of present embodiment, phase compensation glass 31 is split into refractive index different a plurality of regional 31a, 31b, 31c, thereby can make the phase compensation amount of giving incident light according to each regional change, therefore can reduce the poor of the interior phase changing capacity of luminous point, improve the playback performance of optical recording media 29.Further, by being obliquely installed phase compensation glass 31, thereby do not need to be used to produce the optical accessories such as cylindrical lens of astigmatism, can realize the miniaturization of optical head.
This optical head 21 is not limited to above-mentioned formation, can carry out various changes.In the optical head 21 of present embodiment, use with cut-off rule 51,52 as phase compensation glass 31 to be the different device of the refractive index on border, but be not limited thereto, for example also can use the graded index glass of variations in refractive index in the face of phase compensation glass etc.
Fig. 6 is the sectional view of reduced representation as the formation of the optical head 61 of second embodiment of the invention.The optical head 61 of present embodiment and the optical head 21 of above-mentioned first embodiment are similar, the part of correspondence are marked with identical with reference to label, and omit its explanation.
The optical head 61 of second embodiment is characterised in that to have: liquid crystal cell 63 as the phase compensation portion of optical element 62, has a plurality of divided cut zone; Voltage application portion 64 applies voltage respectively to a plurality of cut zone of liquid crystal cell 63, makes the variations in refractive index of each cut zone; Control part 65, the phase compensation amount that adjustment applies according to each cut zone the light of the cut zone that is injected into liquid crystal cell 63, and control the action that the cut zone of liquid crystal cell 63 is applied the voltage application portion 64 of voltage, make the luminous point that has seen through liquid crystal cell 63 in this luminous point, be endowed consistent phase change.
Fig. 7 is the vertical view of the formation of schematic representation liquid crystal cell 63.Liquid crystal cell 63 is wholely set with the light separated part 30 of optical element 62, disposes than light separated part 30 close photodetectors 28.And, the liquid crystal cell 63 that the optical head 61 of present embodiment is had is that plan view shape is the flat-shaped part of rectangle, has cut zone 63a, the 63b, the 63c that are divided into a plurality of (in the present embodiment being three) on Z-direction by the cut- off rule 53,54 that extends.And the direction that a plurality of cut zone 63a, 63b, 63c arrange is with the radial direction of the optical recording media 29 that is in record or playback mode, be that Y direction is parallel.
Be respectively equipped with a pair of transparency electrode among each cut zone 63a of liquid crystal cell 63,63b, the 63c and be disposed at liquid crystal layer between a pair of transparency electrode, above-mentioned a pair of transparency electrode by the transparency electrode that connects with voltage application portion 64, and another transparency electrode of the relative configuration of transparency electrode that is connected with above-mentioned voltage application portion 64 constitute.This liquid crystal layer and transparency electrode are sealed by glass substrate.
Via each cut zone 63a, 63b, transparency electrode that 63c had respectively, apply voltage to liquid crystal cell 63 from voltage application portion 64.Therefore, voltage application portion 64 is constituted as: can apply different magnitudes of voltage respectively to cut zone 63a, 63b, 63c.The electrode that a plurality of cut zone had as liquid crystal cell 63 uses transparency electrode, thereby light can not covered by electrode, therefore can prevent to descend by the light intensity of liquid crystal cell 63.In liquid crystal cell 63, by between a pair of transparency electrode, applying voltage, change the refractive index of liquid crystal layer, give phase change by this change of refractive to incident light.
Apply the liquid crystal cell 63 of voltage by voltage application portion 64, give phase compensation to incident light, make incident light roughly polarisation be linear polarization.Apply the voltage application portion of voltage to each transparency electrode of the liquid crystal cell 63 with cut zone, have not shown power supply and PWM (PulseWidth Modulation).The action of voltage application portion 64 is by control part 65 controls.
Control part 65, the phase compensation amount that adjustment is given according to each cut zone the light of the cut zone 63a, the 63b that are injected into liquid crystal cell 63,63c, and control is given consistent phase change to the action of cut zone 63a, the 63b of liquid crystal cell 63, voltage application portion 64 that 63c applies voltage so that seen through the luminous point of liquid crystal cell 63 in this luminous point.To phase changing capacity in the luminous point of the scattered light that is injected into liquid crystal cell 63 produce difference reason, and the method for adjusting phase compensation amount for the difference that reduces this phase changing capacity discussing after a while.
And, control part 65, the action of control voltage application portion 64 makes that not only the poor of phase changing capacity in the luminous point reduces, and the feasible phase compensation amount that can adjust liquid crystal cell 63 according to the kind of optical recording media 29.Control part 65 detects the kind of optical recording media 29, according to the kind of detected optical recording media 29, each cut zone of liquid crystal cell 63 is applied predetermined voltage.Kind according to optical recording media 29, should be applied to the voltage of each cut zone of liquid crystal cell 63, promptly obtain to give the voltage of the refractive index of appropriate phase compensation to incident light, can test in advance and try to achieve, and be stored among the storer 65a that is provided with on the control part 65 in modes such as table datas according to the kind of optical recording media 29 and cut zone 63a, 63b, the 63c of liquid crystal cell 63.Storer 65a is for example by LSI formations such as (Large ScaleIntegration, large scale integrated circuits).
Control part 65, according to the electric signal that obtains by photodetector 28, when for example using Magnetooptic recording medium, according to TOC (the Table of Contents that writes down in advance in this Magnetooptic recording medium as optical recording media 29, catalogue) information etc. is carried out the kind of optical recording media 29 and is differentiated.
Further, there is the problem that causes various performance change such as its optical property because of temperature variation in liquid crystal cell 63, but in the optical head 61 of present embodiment, near liquid crystal cell 63, be provided with the not shown temperature sensor of the surface temperature of measuring liquid crystal cell 63, that utilizes among the storer 65a storage in advance has set up related table data with temperature and voltage, and the various changes of properties that the temperature variation of following liquid crystal cell 63 is produced are proofreaied and correct.
When using liquid crystal cell as phase compensation portion, compare when using phase compensation glass as phase compensation portion, the difference that is injected into the phase changing capacity in the luminous point of scattered light of liquid crystal cell further becomes big.Below the difference of the phase changing capacity in the luminous point of scattered light further enlarges when using liquid crystal cell reason, and adjust phase compensation amounts by the liquid crystal cell 63 of present embodiment and describe with the method that reduces the phase changing capacity difference.
Fig. 8 A and Fig. 8 B represent that schematically scattered light is injected into the sectional view of the form of liquid crystal cell 66.In Fig. 8 A, represent that schematically the light 67a of luminous point in a periphery as the incident light of scattered light is injected into the state in the liquid crystal cell 66.In Fig. 8 B, the luminous point of schematically representing incident light with another periphery of an opposite side of periphery shown in Fig. 8 A in light 67b be injected into the state of liquid crystal cell 66.
When light was injected into liquid crystal cell, because the anisotropy of the refractive index of the liquid crystal of formation liquid crystal cell, when the incident angle of incident light changed, liquid crystal phase was for the variations in refractive index of incident light.And, when the incident angle of the light that is injected into liquid crystal cell changed, though it is identical to be applied to the voltage of liquid crystal cell, and the refraction performance of liquid crystal cell self was identical, but owing to follow the variations in refractive index of this light of the variation of incident angle, the phase changing capacity of light is different with required amount.
The change of this phase changing capacity not only becomes problem between the different a plurality of light of incident angle, and when the only scattered light injected, near the light the optical axis of luminous point, and be also to become problem between near the periphery of both sides at center the light with the optical axis of luminous point.And, because incident angle difference, and near the refractive index of the liquid crystal near the refractive index of the liquid crystal optical spot centre and the luminous point periphery produces when differing from, because this refringence, it is poor that near the phase changing capacity near phase changing capacity the optical spot centre and luminous point periphery produces.
Wherein, the difference of the phase changing capacity of the phase changing capacity of optical spot centre and luminous point periphery is shown in following formula (1).Wherein, " refractive index poor " is meant: the voltage of liquid crystal cell is identical, the refraction performance of liquid crystal cell self is identical although be applied to, the refractive index of the refractive index of the optical spot centre that produces along with the variation of incident angle and luminous point periphery poor.
(phase changing capacity poor)
=(refractive index poor) * (thickness of liquid crystal) * 360/ (incident light wavelength) ... (1)
As shown in Equation (1), in same luminous point when phase changing capacity produces fluctuation, even near the optimum phase compensation amount the optical spot centre is given as the luminous point of the incident light of scattered light all, the phase changing capacity in the luminous point periphery of this incident light also can become the phase changing capacity different with optimum value.
Fig. 9 be expression for the scattered light that is injected into undivided liquid crystal cell, on average give incident light when all with the phase compensation amount of the best on the optical axis center, the figure of the phase changing capacity that everybody of spot radius direction deposits.Liquid crystal cell, it is all to give luminous point in the optimum phase compensation amount of optical axis center (optical spot centre) as the incident light of scattered light.Thereby near the optical spot centre of incident light, can make incident light be roughly linear polarization.
But as mentioned above, although it is all that the phase compensation amount of the best that will be identical with optical spot centre is given luminous point, but, so become the value that departs from the optimum phase variable quantity because the incident angle of incident light is different with the optical axis center part in as the luminous point periphery of the incident light of scattered light.So, when the phase changing capacity of luminous point periphery departed from optimum value, near the polarized condition of the light the luminous point periphery changed elliptical polarized light into from linear polarization.
This in order to reduce by resulting from the difference of the different refractive index of the incident angle of light and the fluctuation of phase changing capacity in the luminous point that produces, in the optical head 61 of present embodiment, use as the above-mentioned liquid crystal cell 63 that is split into a plurality of cut zone 63a, 63b, 63c that has shown in Figure 7.Liquid crystal cell with cut zone 63a, 63b, 63c 63 shown in Figure 7, can be different values by making the magnitude of voltage that is applied on cut zone 63a, 63b, the transparency electrode that 63c had respectively, and the refractive index to incident light among each cut zone 63a, 63b, the 63c is set at different values, can change the phase compensation amount that the light that is injected into each cut zone 63a, 63b, 63c is given.
The figure of Figure 10 phase compensation amount that to be 63 pairs of expression liquid crystal cells with a plurality of cut zone shown in Figure 7 give as the incident light of scattered light.In Figure 10, be illustrated in the phase compensation amount of among each cut zone 63a, 63b, the 63c incident light being given with solid line.And in Figure 10, the phase changing capacity when line 71 expressions shown in the double dot dash line are given consistent phase compensation amount to being injected into the above-mentioned scattered light that is not divided into a plurality of liquid crystal cells in luminous point.
In cut zone 63a, distolateral at the phase changing capacity of the reality luminous point periphery littler than optimum value given the phase compensation amount bigger than the phase compensation amount of giving near optical spot centre.In cut zone 63b,, therefore do not change phase compensation amount because the difference of the phase changing capacity of actual phase changing capacity and the best is less.In cut zone 63c, distolateral at another of the phase changing capacity of the reality luminous point periphery bigger than optimum value, give the phase compensation amount littler than near the phase compensation amount of optical spot centre, giving.
As mentioned above, for cut zone 63a, the 63b that changes liquid crystal cell 63, the phase compensation amount among the 63c, be applied to the magnitude of voltage of the transparency electrode that cut zone 63a, 63b, 63c had, for example can use by test and wait the value of trying to achieve in advance and being stored among the storer 65a that control part 65 has etc.
Figure 11 is the process flow diagram of the controlled step of the control part 65 of expression when liquid crystal cell 63 applies voltage.In the present embodiment, playback is recorded in as the MD of optical recording media 29 or the situation of the information among the Hi-MD describes.In step s0,,, advance to step s1 afterwards with the information of playback optical recording media 29 to control part 65 output signals.
In step s1, control part 65 carries out the kind of optical recording media 29 and judges according to the TOC information of storing in advance in the optical recording media 29.After having judged the kind of optical recording media 29, advance to step s2.
In step s2, control part 65 is according to the kind of information of the optical recording media 29 that obtains among the step s1, and decision is applied to the magnitude of voltage of liquid crystal cell 63.This magnitude of voltage is the value of trying to achieve and being stored in storer 65a according to the kind of optical recording media 29 by test etc. in advance.After having determined to be applied to the magnitude of voltage of liquid crystal cell 63, advance to step s3.
In step s3, the action of control part 65 control voltage application portion 64 is applied to liquid crystal cell 63 with the magnitude of voltage that will determine in step s2.Action control by 65 pairs of voltage application portion 64 of control part is applied to liquid crystal cell 63 with predetermined magnitude of voltage.After predetermined magnitude of voltage is applied to liquid crystal cell 63, advance to step s4, the finishing control action.
The figure of the phase changing capacity 72 that Figure 12 is expression when being injected into the scattered light with the liquid crystal cell 63 that is divided into a plurality of cut zone and giving phase compensation amount according to each cut zone.Be divided into liquid crystal cell 63 a plurality of, changing applying magnitude of voltage and changing phase compensation amount near the center of luminous point and near the periphery from voltage application portion 64, thereby the interior phase changing capacity of luminous point and the difference of optimum value are reduced, reduce the poor of the interior phase changing capacity of luminous point.
Figure 13 is expression by the error rate that is not split into a plurality of liquid crystal cells optical recording media 29 playback times when giving phase compensation, and the figure of the error rate of optical recording media 29 playback times when giving phase compensation by the liquid crystal cell 63 with a plurality of cut zone.To by be not split into a plurality of liquid crystal cells when giving phase compensation the error rate of (prior art) represent that with white circle the error rate of (the present invention) is represented with black circles when giving phase compensation by optical head 61 liquid crystal cells 63 that possess, that have a plurality of cut zone of present embodiment.And the phase compensation amount of representing with transverse axis when using the liquid crystal cell 63 with a plurality of cut zone is illustrated in the phase compensation amount that cut zone 63 is given.Error rate is the measured value of the number of makeing mistakes of generation in the unit interval in addition.In the measurement of error rate,, used MD as optical recording media 29.
As shown in figure 13, in phase compensation amount is certain limit (about 90 °～120 °) major part in addition, error rate when giving phase change by liquid crystal cell 63 with a plurality of cut zone, with do not compare by being split into the error rate of a plurality of liquid crystal cells when giving phase change, significantly reduce.Therefore, by liquid crystal cell being divided into a plurality of and near near the suitable magnitude of voltage of selecting the to be applied to liquid crystal cell center of luminous point and periphery, can change the phase compensation amount in each cut zone, and phase changing capacity poor in the reduction luminous point, can improve the playback performance of optical recording media 29.
Figure 14 is the outboard profile of reduced representation as the formation of the optical head 81 of third embodiment of the invention.Optical head 81 has: semiconductor Laser device 22, grating 23, spectroscope 82, coupled lens 25, object lens 26, liquid crystal cell 63, voltage application portion 64, control part 65, wollaston prism 27 and photodetector 28.In the present embodiment, as the spectroscope 82 of light separated part, and the liquid crystal cell 63 that constitutes phase compensation portion not by integrally formed.
The optical head 81 of present embodiment is characterised in that, comprising: liquid crystal cell 63, be arranged on the spectroscope 82 and light path as the light separated part as the loop light between the photodetector 28 of photo detector, and have and be divided into a plurality of cut zone; Voltage application portion 64 applies voltage respectively and changes the refractive index of each cut zone a plurality of cut zone of liquid crystal cell 63; With control part 65, the phase compensation amount that adjustment applies according to each cut zone the light of the cut zone that is injected into liquid crystal cell 63, and control applies the action of the voltage application portion 64 of voltage to the cut zone of liquid crystal cell 63, gives consistent phase change so that seen through the luminous point of liquid crystal cell 63 in this luminous point.
Spectroscope 82 is to separate the outlet light that penetrates from semiconductor Laser device 22, and penetrate and the light separated part of the loop light that reflected by optical recording media 29 from semiconductor Laser device 22.Spectroscope 82 is to separate the outlet light that penetrates from semiconductor Laser device 22, and penetrate and the light separated part of the loop light that reflected by optical recording media 29 from semiconductor Laser device 22.Spectroscope 82 makes the outlet light transmission that penetrates from semiconductor Laser device 22 and is directed to object lens 26, and the loop light that reflection is reflected by optical recording media 29 also is directed to photodetector 28.
Coupled lens 25 is that the scattering angle of adjusting the scattering of light angle that is injected into object lens 26 is adjusted element, is configured between semiconductor Laser device 22 and the object lens 26, further is configured in the present embodiment between spectroscope 82 and the object lens 26.Coupled lens 25 makes from semiconductor Laser device 22 and penetrates and see through grating 23 and spectroscope 82 and the scattering of light angle injected for example reduces the back and penetrates, and incident light is injected in the object lens 26.When using this coupled lens 25, can realize optical head 81 in miniaturization on the emergent light optical axis direction and the miniaturization on the focus direction of object lens 26, and can improve outgoing light intensity from object lens 26.
Further, in the present embodiment, it is characterized in that, liquid crystal cell 63 is with respect to the inclined light shaft setting of the loop light between spectroscope 82 and the photodetector 28, and the direction that liquid crystal cell 63 tilts with respect to the optical axis of the loop light between spectroscope 82 and the photodetector 28 is the radial direction (Y direction) that is in the optical recording media 29 of record or playback mode.
Further, the direction that liquid crystal cell 63 tilts with respect to the optical axis of the loop light between spectroscope 82 and the photodetector 28 is the radial direction that is in the optical recording media 29 of record or playback mode, is Y direction, therefore as mentioned above, utilization is the parallel liquid crystal cell 63 that cut zone 63a, 63b, 63c are arranged of cutting apart on Y direction, can make the phase change unanimity in the luminous point, and can give astigmatism luminous point.
Further, use liquid crystal cell 63 as phase compensation portion, thus can be according to the voltage that applies from voltage application portion 64, and making the phase compensation amount of incident light being given at each playback time is optimum value.Therefore, the optical head 61 of present embodiment for example is equipped on when having compatible apparatus for replaying disc between MD and Hi-MD,, all can gives best phase compensation amount at MD playback time and Hi-MD playback time.
Apparatus for replaying disc with aforesaid optical head of the present invention can reduce the poor of phase changing capacity in the luminous point that the incident angle because of light produces, can further improve the playback performance of optical recording media 29.And, in having the apparatus for replaying disc of optical head of the present invention, only be not limited to device that the information of record in the optical recording media 29 is reset, also carry out optical recording media 29 recorded informations and device that the information of record in the optical recording media 29 is reset.
The present invention can implement under the prerequisite that does not break away from its spirit and purport in every way.Therefore the foregoing description only is simple example from every side, and scope of the present invention is not subjected to any constraint of instructions text shown in the claim scope.Further, distortion, the change that belongs to the claim scope all belongs to scope of the present invention.
Claims (14)
1. an optical head writes down and/or playback information to the optical recording media irradiates light, it is characterized in that,
Have: the light source that penetrates light;
Object lens that will be from outlet light optically focused that light source penetrates to optical recording media;
Reception is penetrated and by the photo detector of the loop light of optical recording media reflection from light source; With
Be arranged on the optical element on the light path of the loop light between object lens and the photo detector,
Wherein, optical element has:
The light separated part of separating outlet light and loop light; With
The phase compensation portion that the light of injecting is carried out phase compensation,
Phase compensation portion is set to than light separated part near photo detector.
2. optical head according to claim 1 is characterized in that,
In the optical element, phase compensation portion towards the inclined light shaft setting of the face of a side of photo detector with respect to the loop light between object lens and the photo detector.
3. optical head according to claim 1 is characterized in that,
Comprise scattering angle adjustment element, it is configured between optical element and the object lens, adjusts the scattering of light angle that is injected into object lens.
4. optical head according to claim 1 is characterized in that,
Phase compensation portion is the phase compensation glass with a plurality of cut zone of cutting apart,
In the phase compensation glass, the refractive index of at least one cut zone is different with the refractive index of other cut zone.
5. optical head according to claim 4 is characterized in that,
The direction that a plurality of cut zone of phase compensation glass are arranged, parallel with the radial direction of the optical recording media that is in record or playback mode.
6. optical head according to claim 1 is characterized in that,
Phase compensation portion has:
Liquid crystal cell, it has a plurality of cut zone of cutting apart;
Voltage application portion applies voltage respectively to a plurality of cut zone of liquid crystal cell, and makes the variations in refractive index of each cut zone; With
Control part, the phase compensation amount that adjustment applies according to each cut zone respectively the light of the cut zone that is injected into liquid crystal cell, and control applies the action of the voltage application portion of voltage to the cut zone of liquid crystal cell, is applied in consistent phase change so that seen through the luminous point of liquid crystal cell in this luminous point.
7. optical head according to claim 6 is characterized in that,
Liquid crystal cell is with respect to the inclined light shaft setting of the loop light between light separated part and the photo detector.
8. optical head according to claim 6 is characterized in that,
Each cut zone of liquid crystal cell has transparency electrode.
9. optical head according to claim 6 is characterized in that,
The direction that a plurality of cut zone of liquid crystal cell are arranged, parallel with the radial direction of the optical recording media that is in record or playback mode.
10. optical head according to claim 7 is characterized in that,
The direction that liquid crystal cell tilts with respect to the optical axis of the loop light between light separated part and the photo detector is the radial direction that is in the optical recording media of record or playback mode.
11. optical head according to claim 6 is characterized in that,
Comprise the scattering angle adjustment element that the scattering of light angle that is injected into object lens is adjusted,
Scattering angle is adjusted element and is configured between light source and the object lens.
12. optical head according to claim 6 is characterized in that,
Comprise the anisotropy element, its will by optical recording media reflection and by the light separating part from, separate from the loop light of optical recording media, and be injected in the photo detector,
The anisotropy element is configured between liquid crystal cell and the photo detector.
13. optical head according to claim 1 is characterized in that,
It is the following laser of 780nm that light source penetrates wavelength, and the numerical aperture NA of object lens is more than 0.45.
14. an apparatus for replaying disc is characterized in that, has the described optical head of claim 1.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2005205733 | 2005-07-14 | ||
| JP2005205733A JP4523504B2 (en) | 2005-07-14 | 2005-07-14 | Optical head and disk reproducing apparatus |
| JP2005224602 | 2005-08-02 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1897131A true CN1897131A (en) | 2007-01-17 |
| CN100481222C CN100481222C (en) | 2009-04-22 |
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|---|---|---|---|
| CNB2006101063855A Expired - Fee Related CN100481222C (en) | 2005-07-14 | 2006-07-14 | Optical head and disk reproducing apparatus |
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| JP (1) | JP4523504B2 (en) |
| CN (1) | CN100481222C (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4523512B2 (en) * | 2005-08-02 | 2010-08-11 | シャープ株式会社 | Optical head and disk reproducing apparatus |
| JP7294970B2 (en) * | 2019-09-20 | 2023-06-20 | スタンレー電気株式会社 | Vehicle lighting system |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000306278A (en) * | 1999-04-16 | 2000-11-02 | Canon Inc | Optical information reproducing device |
| JP2003296960A (en) * | 2002-03-29 | 2003-10-17 | Sony Corp | Optical head and disk player |
| JP4302642B2 (en) * | 2005-01-14 | 2009-07-29 | シャープ株式会社 | Optical head and disk reproducing apparatus |
-
2005
- 2005-07-14 JP JP2005205733A patent/JP4523504B2/en not_active Expired - Fee Related
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| JP2007026512A (en) | 2007-02-01 |
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