CN100401399C

CN100401399C - Optical pickup

Info

Publication number: CN100401399C
Application number: CNB2006100585256A
Authority: CN
Inventors: 下川聪; 手塚耕一
Original assignee: Fujitsu Ltd
Current assignee: Fujitsu Ltd
Priority date: 2005-03-29
Filing date: 2006-03-10
Publication date: 2008-07-09
Anticipated expiration: 2026-03-10
Also published as: CN1841534A

Abstract

An optical pickup is provided for driving objective lenses in focusing and radial directions. The pickup includes a movable member, and objective lenses at the center portion of the movable member. The pickup also includes coil blocks provided at two side portions of the movable member, and pairs of magnets flanking the coil blocks in a tangential direction perpendicular to the focusing and radial directions. Support members are attached to the side portions of the movable member, permitting the movable member to move in the focusing direction and the radial direction. Each coil block includes focusing and tracking coils for driving the movable member in the focusing direction and the radial direction. The center portion of the movable member, below which a reflector is arranged, is thinner than the side portions of the movable member.

Description

Optical pickup

Technical field

The present invention relates to reach the optical disc apparatus that reproduces from CD, the particularly optical pickup in the optical disc apparatus at the enterprising line item of CD.More particularly, the present invention relates to a plurality of object lens are housed so that can have the optical pickup that writes down and reproduce on the polytype CD of different optical characteristic.

Background technology

The enterprising line item of multiple CD and the reproduction of different optical characteristic designed the multiple structure of the optical pickup that is used for optical disc apparatus, so that can be had.Especially, because appearance as the Blu-ray Disc of high-density recording media, to seek such optical disc apparatus from now on, this optical disc apparatus can be at Blu-ray Disc (HD-DVD and Blu-ray Disc) the enterprising line item except traditional ruddiness CD (CD and DVD) and from its reproduction.

In order to reproduce at the enterprising line item of polytype CD with different optical characteristic and from it by enough single optical pickups, main problem is how to give this optical pickup equipment object lens.Considering the method for two kinds of head it offs.A kind of method relates to the equipment single object lens, and these object lens are compatible mutually with the polytype CD with different optical characteristic.Second method relates to a plurality of object lens of equipment, and these object lens are corresponding with described polytype CD.

Next will describe with reference to Figure 14 pair of thickness with the corresponding object lens of key light dish.In Figure 14 (A), symbol 101 representatives and DVD and the compatible mutually object lens of CD.The thickness T a of this compatible objective 101 is about 1.3mm.The blue light object lens of symbol 102 representatives and Blu-ray Disc compatibility.The thickness T b of these blue light object lens 102 is about 2.5mm.Symbol 103 representative can with DVD, CD and the common BD/DVD/CD compatible objective of using of Blu-ray Disc.The thickness T c of this BD/DVD/CD compatible objective 103 is about 4.5mm.When object lens have occupied such 4.5mm thickness, consider that stationary mirror directly places the object lens below, just such problem has appearred, it is also bigger than the thickness (7.3mm) of thin driver used in the notebook computer to be that the thickness of optical pickup becomes, and the thickness of this thin driver is as a judgment criteria of thickness.

Therefore, from reducing the position of thickness, for the light pick-up header structure of the recoding/reproduction that can carry out Blu-ray Disc, DVD and CD, second kind (equipping the method for a plurality of object lens to pick-up head) in the said method is considered to more effective.

Figure 15 is the stereographic map that the used actuator of the disclosed optical pickup of TOHKEMY No.2003-281758 is shown.Actuator 100 is twin shaft driving elements, wherein be installed on the single movable link 111 with the corresponding object lens 112 of the CD with different optical characteristic and 113, and movable link 111 can be by drive on R on the focus direction F and radially.Such actuator 100 can be applied to and be used for having on a plurality of CDs of different optical characteristic record and from the optical pickup of its reproduction.

The actuator 100 of TOHKEMY No.2003-281758 is made of by the movable link 111 that bearing 114 supports pedestal 130.Two

object lens

112 and 113 are installed on the movable link 111 and arrange along R radially.Actuator 100 comprises supporting member 115, first magnetic circuit 150 and second magnetic circuit 160, and wherein, supporting member 115 is connected to bearing 114 with movable link 111, and movable link 111 is supported at focus direction F and radially movable on the R; First magnetic circuit moves movable link 111 on focus direction F; Second magnetic circuit 160 is radially moving movable link 111 on the R.

Consider such fact, promptly compare with the data recording/reproducing zone of low density optical disc, the data recording/reproducing zone of high density compact disc is positioned at the inside, so arrangement mode as

object lens

112 and 113, be set to be positioned at the inboard of CD by the object lens of symbol 112 representative, as the object lens that use together with high density compact disc.

First and second

magnetic circuits

150 and 160 respectively have two groups, and tangential direction (on the direction of the circumference) T that is set to along CD is centered around on the both sides of object lens 112,113.Every group first magnetic circuit 150 comprises focusing magnet 151 and focusing coil 152; Every group second magnetic circuit 160 comprises and follows rail magnet 161 and follow path circle 162.Focusing magnet 151 is permanent magnets with following rail magnet 161; Compare with following rail magnet 161, focusing magnet 151 is positioned at the more lateral of movable link 111.Focusing coil 152 is between movable link 111 and focusing magnet 151; Follow path circle 162 at movable link 111 and follow between the rail magnet 161.

Use the optical pickup of this actuator 100 must be set at shown in Figure 16.That is, below actuator 100, be provided with the light source 140, collimation lens 141 of emission laser L, with the stationary mirror 135 of laser L guiding object lens 112,113 and for by CD reflection this accompanying drawing outside and the photoelectric detector 143 that carries out light quantity or the like detection from the laser L that it returns.Being provided with semi-transparent semi-reflecting lens 142 between light source 140 and stationary mirror 135 makes laser L propagate and will be by CD reflection and from its laser L direct light photodetector 143 that returns to stationary mirror 135 from light source 140.

140 emitted laser L pass semi-transparent semi-reflecting lens 142 from LASER Light Source, by one of stationary mirror 135 guiding

object lens

112 or 113, and the recording surface of irradiation CD, wherein CD is by the clamping of disc rotating mechanism.By the recording surface laser light reflected L of CD through

object lens

112 or 113 and by stationary mirror 135 reflections, then by semi-transparent semi-reflecting lens 142 direct light photodetectors 143.

In the CD pick-up head of the above-mentioned actuator that uses TOHKEMY No.2003-281758, as shown in figure 16, stationary mirror must place the actuator below so that obtain thin shape, and magnetic circuit, stationary mirror and other elements must be made compactly.

But, there is such problem, if promptly magnetic circuit is made compactly, then focus direction or driveability radially descend, power consumption increases, and follows rail precision decline, makes to be difficult to have compact design for magnetic circuit.

In addition, the size of stationary mirror depends on the effective diameter of object lens; As the condition of optical design, stationary mirror laser light reflected beam width must make the design that reduces and approach of stationary mirror size be difficult to especially realize greater than the effective diameter of object lens.

Summary of the invention

The present invention considers above-mentioned situation and proposes.An object of the present invention is to provide a kind of optical pickup, it can easily be made thinly and be compact and can not damage electromagnetic performance or optical property.

According to a first aspect of the invention, provide a kind of being used for to reach the optical pickup that radially drives object lens along focus direction.Described pick-up head of the present invention comprises: movable link, and it comprises core, first side part and the second side part, first side part and second side part radially are separated from each other and are positioned at the side of core; A plurality of object lens, it is arranged on the central part office of movable link; First coil unit and second coil unit, they are separately positioned on first side part and the second sidepiece office of movable link; First magnet is right, and it is positioned at the tangential side of first coil unit, and tangential direction and focus direction are with radially all vertical; Second magnet is right, and it is positioned at the tangential side of second coil unit; A plurality of supporting members, they are installed to first side part and the second side part of movable link, and the mode of installation is to make that movable link can be along focus direction and radial motion; And reverberator, it is in the face of the core of movable link.And each coil unit comprises focusing coil and follows the path circle.Focusing coil has along the coil axis of focus direction extension and is set to be used for drive movable link along focus direction, has the coil axis that tangentially extends and is set to be used for radially drive movable link and follow the path circle.Follow the outside that the path circle is arranged on focusing coil.The core of movable link is thinner than first side part and the second side part of movable link, and reverberator is inserted in first side part and the space between second side part of movable link, to be positioned proximate to the core of movable link.

Preferably, each coil unit can also comprise tangential tilt coil and radial skew coil.The tangential tilt coil is set to be used to make movable link around the axis tilt that radially extends, and the radial skew coil is set to be used to make movable link around the axis tilt that tangentially extends.

Preferably, the tangential tilt coil can have coil axis that extends along focus direction and the openend that is set to the proximity focusing coil.The radial skew coil has the coil axis that extends along focus direction and another (or other) openend that is set to the proximity focusing coil.

Preferably, each magnet can be to make paired magnet have opposite magnetic pole on tangential direction to the mode of arranging.

Preferably, a plurality of object lens can tangentially be arranged side by side.

Preferably, reverberator can comprise a plurality of stationary mirrors corresponding respectively with a plurality of object lens.Stationary mirror be arranged between first coil unit and second coil unit so that tangentially the laser beam of Chuan Boing reflect towards corresponding object lens.

Preferably, optical pickup of the present invention can also comprise bearing, is used for supporting movable link by a plurality of supporting members with cantilevered fashion.Bearing is formed with guide lighting channel, is used to make laser beam tangentially to propagate towards stationary mirror.

According to a second aspect of the invention, provide a kind of optical disc apparatus that combines above-mentioned optical pickup.

According to the present invention, compact optical pickup can be provided, it has comprised said elements (movable link, a plurality of object lens or the like) and their proper function has not been brought infringement.Especially, the core of movable link is made into thinner than each limit that is positioned at the core side.Therefore, can arrange very near the core of movable link towards the reverberator (stationary mirror) of core, this helps to reduce the thickness of optical pickup.

Other aspects of the present invention and advantage thereof are described below with reference to the accompanying drawings.

Description of drawings

Fig. 1 is the exploded perspective view that illustrates according to the optical pickup of first embodiment of the invention;

Fig. 2 is total stereographic map of optical pickup shown in Figure 1;

Fig. 3 illustrates optical pickup shown in Figure 1 has been carried out the partly front view of the example of change;

Fig. 4 is the sectional view of being got along IV-IV line among Fig. 2;

Fig. 5 is the synoptic diagram that the operation to optical pickup shown in Figure 1 describes;

Fig. 6 is the exploded perspective view that optical pickup according to a second embodiment of the present invention is shown;

Fig. 7 is total stereographic map of optical pickup shown in Figure 6;

Fig. 8 is the stereographic map that the operation to optical pickup shown in Figure 6 describes;

Fig. 9 is the stereographic map that the optical pickup of a third embodiment in accordance with the invention is shown;

Figure 10 is the stereographic map that the optical pickup of a fourth embodiment in accordance with the invention is shown;

Figure 11 is the sectional view of being got along IX-IX line among Figure 10;

Figure 12 is the planimetric map that the example to the object lens mounting means describes;

Figure 13 is the stereographic map that the optical disc apparatus that combines optical pickup of the present invention is shown;

Figure 14 is the explanatory that is used for describing with the corresponding object lens thickness of all kinds CD;

Figure 15 is the stereographic map that the used actuator of optical pickup of prior art is shown; And,

Figure 16 is the sectional view of being got along XVI-XVI line among Figure 15.

Embodiment

Fig. 1 illustrates the first aspect of optical pickup of the present invention to Fig. 5.Optical pickup A1 in this respect is equipped with two types lens, corresponding to a plurality of CDs with different optical characteristic (for example Blu-ray Disc, DVD and CD), and is used for carrying out optical recording and reproduction on CD.In every width of cloth figure, a side at CD place is considered to upside among the optical pickup A1, and vertical direction is focus direction F, is R radially along the direction of CD radius, is tangential direction T with focus direction F with the third direction along the CD circumference that radially R is vertical.

As depicted in figs. 1 and 2, optical pickup A1 has movable link 11, two

object lens

12 and 13, bearing 14, many supporting wires 15, forms two a pair of coil units 20, pedestal 30, every group have two magnets two groups of magnets 31 and two stationary mirrors 32 and 33.Coil unit 20 comprises that a focusing coil 21 and two follow path circle 22.Movable link 11,

object lens

12 and 13, bearing 14, supporting wire 15 and coil unit 20 are set to the top assembly; Pedestal 30, magnet 31 and

stationary mirror

32 and 33 are set to lower component.Top assembly and lower component fuse by bearing 14 and pedestal 30 are fastened to independent substrate (not shown) or analog.

Movable link 11 has core 11A and lateral parts 11B, and

object lens

12 and 13 are installed among the center section 11A, lateral parts 11B divide from central division in both sides 11A radially R extend and comprise coil unit 20.Core 11A is thinner than lateral parts 11B, and is formed at the position of more leaning on the top than lateral parts 11B.Two object lens 12 that are provided with among this core 11A that T tangentially is arranged side by side and 13.Lateral parts 11B has the space that penetrates along focus direction F; The part 30A of pedestal 30 (after this being called " core ") inserts this space as magnetic core.Focusing coil 21 is formed on the whole inner wall surface of lateral parts 11B, follows path circle 22 and is formed on the outer wall of both sides towards tangential direction T.The Outboard Sections that jut 11C is formed at lateral parts 11B is towards R radially; The end of the supporting wire 15 of T extension tangentially is connected to these juts 11C.The bottom of supporting wire 15 is fastened to two ends of bearing 14.In this way, movable link 11 can along focus direction F and radially R move but tangentially T move, constitute so-called twin shaft drive system.

Object lens 12 wherein are used on first CD for example record and reproduce from it, and the laser on the focus direction F is passed to focus the light on first CD.Another object lens 13 also make the laser on the focus direction pass, but these object lens 13 are used on second CD record and from its reproduction, the laser focusings that wavelength is different with the situation of first CD are to second CD, and described second CD has in the different optical characteristics of first CD.These first and second CDs have different optical characteristics standards, for example recording density and gauge usually; Specifically, disk types can be CD, DVD, HD-DVD or Blu-ray Disc.In aspect this, object lens 12 wherein are corresponding to CD and DVD, and another object lens 13 are corresponding to Blu-ray Disc.The situation of expectation is that the set-up mode of one of object lens is for making that be consistent along the straight line of this optical lens diameter with the radius of CD.

The thickness of bearing 14 and pedestal 30 are basic identical, and form on R radially more bigger than pedestal 30.The bottom of supporting wire 15 is fastened onto the radially two ends of R extension of bearing 14.This bearing 14 is installed as from lateral approach pedestal 30, and and pedestal 30 between tangentially T have preset space length; Movable link 11 is set to be stacked on the pedestal 30, and its attitude is to be kept with cantilevered fashion by supporting wire 15.Subsequently, in bearing 14 bottoms light-conductive hole or passage 14A are set so that the laser of propagating from the T tangentially of unshowned light source propagates into below the movable link 11 without change.

As light-conductive hole or the other example of passage 14A, can adopt Fig. 3 (A) to the various aperture shape shown in Fig. 3 (C); Even size only needs big to existing under the situation of some alignment error when assembling optical pickup A1, also be enough to make laser to incide on the stationary mirror 32.As the aperture shape that is used for light-conductive hole 14A, when considering performance and manufacturing cost, shape is most preferred shown in Fig. 3 (A); But also can use the shape of fillet, wherein bight 14B becomes round gradually, as shown in Figure 2.

As mentioned above, supporting wire 15 supports movable link 11 with cantilevered fashion; On a lateral parts 11B of movable link 11, be provided with many supporting wires 15.These supporting wires 15 as lead to focusing coil 21 with follow 22 power supplies of path circle.According to the focusing coil on the lateral parts 11B who drives movable link 11 21 with follow path circle 22 required quantity supporting wire is set; Three supporting wires 15 on one side have been shown in Fig. 1 and Fig. 2, but three or more supporting wire also can be set.

Focusing coil 21 has the attitude that coil axis extends along focus direction F, and focusing coil 21 is to be wholely set on the lateral parts 11B of movable link 11.Follow path circle 22 and have the coil axis T attitude of extending tangentially, and to follow path circle 22 be to be wholely set on the lateral parts 11B of movable link 11, be positioned at the outside of two focusing coils 21.Focusing coil 21 is configured such that and the current-carrying part 21A that follows path circle 22 crossover position places is easy to be subjected to the influence of the action of a magnetic field that caused by magnet 31, and following path circle 22 is arranged so that in parallel current-carrying part, one of current-carrying part 22A is easy to be subjected to the influence in the magnetic field that caused by magnet 31, wherein electric current along focus direction F at the opposite direction described parallel current-carrying part of flowing through.Therefore, act on the current-carrying part 21A of focusing coil 21, movable link 11 is moved along focus direction F by making vertical magnetic field; And be independent of this, follow on the current-carrying part 22A of path circle 22, make radially R motion of movable link 11 by vertical magnetic field is acted on.

Magnet 31 is fastened on the pedestal 30 T tangentially surrounds core 30A in both sides position,

stationary mirror

32 and 33 is fastened to bottom part, and the shape of pedestal makes movable link 11 can be arranged between core 30A and the magnet 31 and

stationary mirror

32 and 33 tops.In the bottom of pedestal 30 are cutouts 30B, and its feasible laser of propagating from the T tangentially of unshowned light source can propagate into

stationary mirror

32 and 33 without change.14A is similar to light-conductive hole, and cutouts 30B can adopt various aperture shape, arrives shown in Fig. 3 (C) as Fig. 3 (A).

Magnet 31 roughly is fastened to the Si Jiaochu of pedestal 30; Tangentially T forms one group at two relative magnets of the both sides encirclement magnetic core 30A of portion.Form one group magnet 31 be arranged so that pole orientation tangentially T be reverse direction; Specifically, for example all magnets 31 all are set to the N utmost point towards the 30A of magnetic core portion.In this way, make around along the direction of current of the axis of focus direction F when identical when driving two focusing coils 21, the electromagnetic force of equidirectional acts on the current-carrying part 21A of each focusing coil 21, and whole movable link 11 is moved along focus direction F.The displacement of this moment is controlled by the drive current of adjusting in the focusing coil 21.And, if following the path circle, driving make the direction of current among all current-carrying part 22A that follow path circle 22 identical with the direction of seeing the past from corresponding magnet 31, then the electromagnetic force of equidirectional acts on the current-carrying part 22A, makes the radially R motion of whole movable link 11.The displacement of this moment is controlled by the drive current that adjustment follows in the path circle 22.That is, focusing coil 21 and magnet 31 follow path circle 22 and magnet 31 as the magnetic circuit that follows rail control as the magnetic circuit of focus control.Each magnet 31 all is focus control and follows the common use of rail control.Magnetic circuit and movable link 11, bearing 14, supporting wire 15 and pedestal 30 combine and have formed actuator.By this structure, can make optical pickup A1 thin compact with essential and enough function solenoids.

It is inner and thereon fastening that

stationary mirror

32 and 33 embeds pedestal 30, and be set to the core 11A towards movable link 11, and reflecting surface is tilted to corresponding respectively object lens 11 and 12.The cutouts 30B that each

stationary mirror

32 and 33 is set to the light-conductive hole 14A of tangentially T and bearing 14 and pedestal 30 is relative.Stationary mirror 32 wherein is configured such that the upwards reflection of laser that the direction of T is tangentially propagated, with laser guide object lens 12.Another stationary mirror 33 is configured such that the reflecting surface of reflecting surface and stationary mirror 32 towards opposite, so that the upwards reflection of laser that the direction opposite with last laser of T tangentially propagated, with laser guide object lens 13.Between this

stationary mirror

32 and 33 to two lateral parts 11B of small part insertion movable link 11, be between a pair of coil unit 20, and the core 11A position with regard to movable link 11 is higher than two lateral parts 11B, the core 11A that

stationary mirror

32 and 33 position should as close as possible movable links 11.By this mode, the thickness of optical pickup A1 guarantees that by the thickness of bearing 14 and pedestal 30

stationary mirror

32 and 33 does not increase the thickness of optical pickup A1.Consequently

stationary mirror

32 and 33 can adopt necessity and enough sizes to make the effective diameter of the width of laser beam greater than

object lens

12 and 13 as the optical design condition, thereby can realize having the compact and thin optical pickup A1 of expectation optical property.In this regard, two

stationary mirrors

32 and 33 back-to-back placements; But also can use single stationary mirror, its have integrally formed two towards rightabout reflecting surface.

As shown in Figure 4, optical pickup A1 is loaded into the optical disc apparatus (not shown) with other optical elements such as LASER Light Source 40A and 40B,

collimation lens

41A and 41B,

beam splitter

42A and 42B and photoelectric detector 43A and 43B.CD D places along on the main shaft (not shown) of focus direction F and by its support, makes recording surface relative with optical pickup A1, and CD D centers on main shaft with high speed rotating in record and reproduction process.In Fig. 4, unshowned radially R is along the direction perpendicular to paper plane.Optical disc apparatus also comprise optical element so that laser more effectively incide on

object lens

12 and 13 maybe will be from the light of CD D reflection

direct light photodetector

43A and 43B effectively; These elements are not shown equally.

When the LASER Light Source 40A emission laser L1 that for example places along Fig. 4 tangential direction T left side, this laser L1 tangentially T propagates and passes collimation lens 41A and beam splitter 42A to the right, pass the light-conductive hole 14A in bearing 14 and pedestal 30 left sides and pass cutouts 30B, incide left side stationary mirror 32 without change.Laser L1 by the reflecting surface of stationary mirror 32 along upwards reflection and finally pass object lens 12 and shine CD D of focus direction F.On the other hand, when placing the LASER Light Source 40B emission laser L2 on tangential direction T right side, this laser L2 tangentially T propagates to the left, pass collimation lens 41B and beam splitter 42B, pass the light-conductive hole 14A on bearing 14 and pedestal 30 right sides and pass cutouts 30B, incide stationary mirror 33 without change.Laser L2 is upwards reflected along focus direction F by the reflecting surface of stationary mirror 33 afterwards, and finally passes the recording surface that object lens 13 shine CD D.

In practical operation, when CD D was written into optical disc apparatus, laser L1 and L2 exported simultaneously from two LASER

Light Source

40A and 40B, and laser L1 and L2 shine the recording surface of CD D, and in the reflection of illuminated position.Laser light reflected L1 and L2 pass each self-

corresponding object lens

12 and 13 along downward focus direction F, arrive

beam splitter

42A and 42B to advance with above-mentioned opposite mode, by

beam splitter

42A and 42B reflection and be directed to

photoelectric detector

43A and 43B.

Laser L1 that returns in

photoelectric detector

43A and 43B place detection of reflected and the light quantity of L2, diffraction pattern or the like.According to the output signal from

photoelectric detector

43A and 43B, unshowned disc discriminator circuit is judged the type of CD D.As identification result, but when to judge the current CD D that is written into be not record/reproducible, produce read error and stop laser output from LASER Light

Source

40A and 40B.

On the other hand, when the CD D that is written into is for example during CD, CD D is judged as suitable CD, and with the object lens 12 in left side and stationary mirror 32 and only at the optical element 40A in left side to 43A in the enterprising line item of CD D/reproduction.Similar with it, when the CD D that for example is written into was Blu-ray Disc, CD D was judged as suitable Blu-ray Disc, and the object lens 13 on right side and stationary mirror 33 and only the optical element 40B on the right side be used in the enterprising line item of CD D/reproduction to 43B.

When the enterprising line item of CD D/reproduction, focus error detection operation and tracking error detecting operation carry out with

photoelectric detector

43A and 43B, and when detecting focusing error, driving focusing coil 21 carries out focus control.When detecting tracking error, driving follows path circle 22 and follows rail control.This focus control and follow rail control and realize by FEEDBACK CONTROL.

But in the high speed rotating process, CD D itself has the characteristic of class such as warpage and vibration.Because this specific character of CD D may produce coma because of the pitch angle between the recording surface of the optical axis of laser L1 or L2 and CD D,, just can not in record or reproduction process, guarantee stable low error rate characteristic if often produce this coma.For example, under the situation of DVD or Blu-ray Disc, it has been generally acknowledged that the pitch angle must be in ± 0.7 ° of scope.

In order to satisfy the requirement of this pitch angle, in aspect this, in FEEDBACK CONTROL, use a pair of focusing coil 21 with control object lens 12 and 13 (movable link 11) tangentially T around the inclination (radial skew servocontrol) of axis.That is, except being used for focus control, focusing coil 21 and magnet 31 also are used for the radial skew servocontrol.

Specifically, when carrying out the radial skew servocontrol,

photoelectric detector

43A and 43B detect the radial skew angle around axis of T tangentially.According to the drive current in two focusing coils 21 of detected radial skew angle control, make that generation difference is so that the radial skew angle becomes 0 between the electromagnetic force size at current-carrying part 21A place.In this way, object

lens

12 or 13 optical axis are controlled as from tangential direction T and always look perpendicular to the recording surface of CD D.This radial skew servocontrol is carried out simultaneously with focus control.

As schematically illustrated among Fig. 5 (A), as CD D radially during the R warpage, if the required power along focus direction F of focus control is F0, and what the radial skew servocontrol was required is R0 around the torque of the axis of T tangentially, and drive current is flowed in current-carrying part 21A (not shown) so that electromagnetic force Fa shown in Fig. 5 (B) and Fb produce.That is,, two current-carrying part 21A that are subjected to the electromagnetic induction effect are arranged, and be the electromagnetic force Fa that produces among all current-carrying part 21A and the result of Fb addition along the power F0 of focus direction F for a focusing coil 21, so, F0=2Fa+2Fb.Because electromagnetic force 2Fa that varies in size and 2Fb result from the both sides as the axis S of movable link 11 rotation centers, and these masterpieces are used for from axis S to focusing coil, and 21 distances are x, so, be R0=(2Fa-2Fb) * x around the torque R0 of the axis of T tangentially.By along this power F0 of focus direction F and around the effect of the torque R0 of the axis of T tangentially, object lens 12 and 13 attitude are controlled as and make optical axis is suitable with respect to the recording surface of CD D.Drive current in two focusing coils 21 also can be controlled as and make the electromagnetic force directed in opposite directions.Although not shown among Fig. 5, tangential direction T is perpendicular to paper plane.In Fig. 5, significantly exaggerated the size (arrow length) of the warpage degree of CD D and power so that understand.

Therefore, optical pickup A1 according to this aspect, movable link 11 and

stationary mirror

32 and 33 are combined into along focus direction F overlapping, and when focus direction is looked in the mode of plan view, lateral parts 11B is positioned on the movable link 11, it comprises the coil unit 20 that is set in place between four jiaos magnet 31 integratedly, so that these elements can arrange compactly, so the overall dimension of optical pickup A1 and shape can keep thin and compact.

And when making great efforts to reduce the size and thickness of optical pickup A1, focus control and follow each essential element of rail control and be designed to have the size that is enough to realize fully required electromagnetic performance and optical property is so that can realize stable and accurate control.

In addition, except focus control with follow the rail control, can also carry out the radial skew servocontrol, so that can realize stable more and accurate control.

Fig. 6 illustrates the second aspect of optical pickup to Fig. 8.In the following description, will be endowed identical symbol with the same or analogous component part of the component part spare that had illustrated, and omit its explanation.

The optical pickup A2 of this aspect has the structure identical with first aspect basically.Main difference is the structure of coil unit 20.A coil unit 20 constituted comprise that two focusing coils 21, two follow path circle 22 (omitting), two tangential tilt coils 23 and two radial skew coils 24 (omitting) in Fig. 8 in Fig. 6 and Fig. 7.

Follow similar in path circle 22 and the above-mentioned first aspect, and focusing coil 21 only is used for focus control, and is provided with tangentially two contiguous focusing coils of direction T.Tangential tilt coil 23 is that control (tangential tilt servocontrol) is used, and it is controlled at 0 around the axis tilt of R radially with tangential tilt angle by making movable link 11; These two coils are set to the attitude that coil axis extends along focus direction F, and contiguous each focusing coil 21 along the openend on the upside of focus direction F.Radial skew coil 24 is that control (radial skew servocontrol) is used, and it is controlled at 0 around the axis tilt of T tangentially with the radial skew angle by making movable link 11; These two coils are set to the attitude that coil axis extends along focus direction F, and contiguous each focusing coil 21 is along the openend on the downside of focus direction F.Follow the required quantity of path circle 22, two tangential tilt coils 23 and two radial skew coils 24 according to driving two focusing coils 21, two, supporting wire 15 is arranged on the lateral parts 11B of movable link 11.In Fig. 6 and Fig. 7, four supporting wires 15 are shown on a side but five or more supporting wire also can be set.

In when operation, focus control and follow the similar of rail control and above-mentioned first aspect, and with focusing coil 21 with follow path circle 22 and carry out.Tangential tilt servocontrol and radial skew servocontrol are following carries out.

As shown in Figure 8, for example, around along galvanization in the reverse direction of the axis of focus direction F driving two tangential tilt coils 23 on the side, and drive radially that R has the tangential tilt coil 23 of relative position relation so that direction of current is identical.Then, the tangential tilt coil 23 that two tangential tilt coils 23 that a side of looking from the axis of R radially is provided with and opposite side are provided with, the electromagnetic force of being seen is reverse direction (referring to the arrow that is filled with white).Consequently, the

object lens

12 and 13 that are installed on the movable link 11 are subjected to torque and center on the radially axis r inclination of R.Tilt quantity is to control by the drive current of regulating in the tangential tilt coil 23 in the case.

On the other hand, for example drive two radial skew coils 24 on the side and make around direction of current identically, and drive the radial skew coil 24 that R radially is in relative position relation and make current opposite in direction along the axis of focus direction F.In this way, two radial skew coil 24 places that are provided with on two radial skew coils 24 that are provided with on the side that tangentially the axis t of T looks and opposite side cause electromagnetic force (referring to black arrow) in opposite direction.In this way, the

object lens

12 and 13 that are installed on the movable link 11 are subjected to around tangentially torque and the inclination of the axis t of T.Tilt quantity is to control by the drive current of regulating in the radial skew coil 24.By this control of tangential tilt coil 23 and radial skew coil 24, can control the recording surface of the optical axis of

object lens

12 and 13 perpendicular to CD.

Therefore, by optical pickup A2 of the present invention, can obtain the useful result similar to first aspect, in addition, the tangential tilt servocontrol can also be independent of the radial skew servocontrol and carry out, make can with in addition higher stability carry out accurate control, coma can be reduced to acceptable degree, and can guarantee stable low error rate characteristic.

Fig. 9 illustrates the third aspect of optical pickup.Optical pickup A3 in this respect has the structure substantially similar with second aspect.Difference is that focusing coil 21 is different with the structure of radial skew coil 24.A coil unit 20 is set to have a focusing coil 21, two follows path circle 22 (in Fig. 9, omitting), two tangential tilt coils 23 and a radial skew coil 24.

In each side a focusing coil 21 is set; Two tangential tilt coils 23 are set so that focusing coil 21 is cut apart along the openend on the focus direction F upside in each side.In each side the radial skew coil 24 of a proximity focusing coil 21 along the openend on the focus direction F downside is set.

In when operation, focus control, follow similar in rail control and tangential tilt servocontrol and the second aspect, the radial skew servocontrol is following carries out.

As shown in Figure 9, for example for the radial skew servocontrol, the mode that drives is to make current opposite in direction.Then the radial skew coil 24 that is provided with of two radial skew coils 24 of being provided with of a side of looking and opposite side from the axis t of T tangentially in opposite direction (referring to the arrow of black) electromagnetic force appears.In this way, the

object lens

12 and 13 that are installed on the movable link 11 are subjected to torque and center on the tangentially axis t inclination of T.The tilt quantity of this moment can be controlled by the drive current of regulating in the radial skew coil 24.Similar in this control of radial skew coil 24 and the second aspect, and object

lens

12 and 13 always are controlled to be recording surface perpendicular to CD.

Therefore, the optical pickup A3 according in this respect compares with second aspect, only is provided with a focusing coil 21 and a radial skew coil 24 in each side, makes to simplify loop construction when obtaining the useful result identical with second aspect.

Figure 10 and Figure 11 show the fourth aspect of optical pickup.Optical pickup A4 in this respect has the structure substantially similar with first aspect.Difference is that two object lens 12 and 13 are installed on the movable link 11, and radially R arranges.It is corresponding with two object lens 12 and 13 to be provided with single stationary mirror 35.This stationary mirror 35 is set to upwards reflection and with two object lens 12 of laser guide and 13 of laser, and described laser is to propagate from the side of T tangentially by the light-conductive hole 14A in the bearing 14 etc.The situation of expectation is that two light path parallel ground that pass object lens 12 and 13 form.In fact, be provided with two optical systems (LASER Light Source, collimation lens, beam splitter or the like) shown in Figure 4 in the structure that is adopted, they are only to be arranged in parallel in the side of T tangentially.Certainly, can the common sparing optical element.Perhaps a LASER Light Source 40, collimation lens 41, beam splitter 42 and photoelectric detector 43 can be set as shown in figure 11, these optical elements are shared for dissimilar CD D.In the case, the situation of expectation is, other devices that in stationary mirror 35 fronts the dichroism prism are set or have a wavelength selectivity come switching-over light path.In Figure 11, show one with LASER Light Source 40 grades place the left side example as an example; Certain LASER Light Source etc. also can place the right side, and the reflecting surface of stationary mirror is set to face LASER Light Source etc.In the case, need not in bearing, to be provided with light-conductive hole.

Object lens

12 and 13 mounting means can also use as Figure 12 (A) to the mounting means shown in Figure 12 (F) except top first to shown in the fourth aspect.For example, as shown in Figure 12 (A) and Figure 12 (B), two

object lens

12 and 13 can be set to the angular direction is arranged along movable link 11 upper surfaces.Perhaps, to shown in Figure 12 (F), three or four

object lens

12,13 of suitable spacing can be installed on movable link 11 as Figure 12 (C).No matter which kind of

object lens

12 and 13 mounting means as long as be arranged so that movable link 11 and stationary mirror (not shown among Figure 12) are overlapping, just can make optical pickup approach and compact.

As shown in figure 13, above first be mounted in to A4 to the described optical pickup A1 of fourth aspect and move back and forth on the unit 50, be arranged on optical disc apparatus A0 inside.By inserting from patchhole 51 and CD D is written into the optical disc apparatus A0, and this CD D is supported on the main shaft (not shown).Move back and forth unit 50 and support, and drive unit 53 is set so that move back and forth the radially to-and-fro movement of unit 50 along rail 52 along CD D by radially a pair of rail 52 on recording surface one side of CD D.By in this optical disc apparatus A0, adopt design the CD pick-up head A1 of thin compact to A4, can make overall optical dish device A0 thin compact.

Claims

1. optical pickup is used for along focus direction and radially drives object lens, and described optical pickup comprises:

Movable link, described movable link comprise core, first side part and the second side part, and described first side part and described second side part radially are separated from each other along described, are positioned at the side of described core;

A plurality of object lens, described a plurality of object lens are arranged on the described central part office of described movable link;

First coil unit and second coil unit, described first coil unit and described second coil unit are separately positioned on described first side part and the described second side part of described movable link;

First magnet is right, and described first magnet is to being positioned at the tangential side of described first coil unit, and described tangential direction and described focus direction are with described radially all vertical;

Second magnet is right, and described second magnet is to being positioned at the side of described second coil unit along described tangential direction;

A plurality of supporting members, described a plurality of supporting members are installed to described first side part and the described second side part of described movable link, and the mode of installation is to make that described movable link can be along described focus direction and described radial motion; And

Reverberator, described slotted-type reflector surface is to the described core of described movable link;

Wherein, each described coil unit comprises focusing coil and follows the path circle, described focusing coil has along the coil axis of described focus direction extension and is set to be used for drive described movable link along described focus direction, the described path circle that follows has the coil axis that extends along described tangential direction and is set to be used for along the described movable link of described radial drive, describedly follow the outside that the path circle is arranged on described focusing coil, and

Wherein, the described core of described movable link is thinner than described first side part and the described second side part of described movable link, described reverberator is inserted in described first side part and the space between described second side part of described movable link, to be positioned proximate to the described core of described movable link.

2. optical pickup according to claim 1, wherein, each described coil unit also comprises tangential tilt coil and radial skew coil, described tangential tilt coil is set to be used to make described movable link around along the described axis tilt that radially extends, and described radial skew coil is set to be used to make described movable link around the axis tilt that extends along described tangential direction.

3. optical pickup according to claim 2, wherein, described tangential tilt coil has coil axis that extends along described focus direction and the openend that is set to contiguous described focusing coil, and described radial skew coil has the coil axis that extends along described focus direction and another openend that is set to contiguous described focusing coil.

4. optical pickup according to claim 1, wherein, each magnet is to make described magnet have opposite magnetic pole on described tangential direction to the mode of arranging.

5. optical pickup according to claim 1, wherein, described a plurality of object lens are arranged side by side along described tangential direction.

6. optical pickup according to claim 5, wherein, a plurality of stationary mirrors that described reverberator comprises and described a plurality of object lens are corresponding respectively, described stationary mirror are arranged between described first coil unit and described second coil unit so that reflect towards corresponding described object lens along the laser beam of described tangential direction propagation.

7. optical pickup according to claim 6, also comprise bearing, described bearing supports described movable link by described a plurality of supporting members with cantilevered fashion, wherein, described bearing is formed with guide lighting channel, and described guide lighting channel is used to make described laser beam to propagate towards described stationary mirror along described tangential direction.

8. an optical disc apparatus comprises optical pickup according to claim 1.