United States Patent [t9J
`Suzuki
`
`[tl] Patent Number:
`[45] Date of Patent:
`
`5,043,964
`Aug. 27, 1991
`
`[54] LI~EAR PICKUP ACTUATOR FOR ::\-IOVI:\"G
`AN OPTICAL PICKUP I~ A RADIAL
`DIRECTIO:S OF A DISK
`
`[75]
`[73]
`
`[21]
`
`Inventor:
`
`Jun Suzuki, Saitama, Japan
`
`Assignee: Pioneer Electronic Corporation,
`Tokyo, Japan
`Appl. No.: 520,413
`
`[22]
`
`Filed:
`
`May 8, 1990
`
`Related U.S. Application Data
`[63] Continuation of Ser. No. 171,073, Mar. 21, 1988, Pat.
`No. 4,942,562.
`
`Foreign Application Priority Data
`[30]
`Apr. 15, 1987 [JP]
`Japan .................................. 62-93907
`
`[51]
`
`Int. CJ.5 ........................ GllB 7/00; GliB 17/30;
`GliB 21/02
`[52] U.S. CI ............................... 369/44.11; 369/44.22;
`369/44.32; 369/215: 369/219
`[58] Field of Search ..................... 369/215, 219. 44.11,
`. 369/44.14,44.15, 44.16, 44.22
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`4.443.i21 4/1984 Jansen .
`4.547,871 10/1985 Sugiyama et al. ........... 369/44.16 X
`4.570,249 2/1986 Melissin et al. ..................... 369/219
`4,583,212 4/1986 Koida et al. ........................ 369/219
`4,592.037 5/1986 Ohnuki ......................... 369/+4. I 5 X
`
`4,766,583 8/1988 Oinoue et al. ............... 369/+4.16 X
`4,794,580 12/1988 Ikeda et al. .................. 369/44.16 X
`4,823,336 4/1989
`Inada et al. ......................... 369/219
`4.861,138 8/1989 Suzuki .......................... 369/44.22 X
`4,878,214 10/1989 Hinotani ...................... 369/44.15 X
`4,942,562 7/1990 Suzuki ............................. 369/219 X
`
`FOREIGN PATENT DOCC'MENTS
`143356 10/1983 European Pat. Off ..
`212941 8/1986 European Pat. Off ..
`2159293 4/1985 Cnited Kingdom .
`
`Primary Examiner-Stuart S. Levy
`Assistant Examiner-Kenneth B. Wells
`Attorney, Agent, or Firm-Sughrue, Mion, Zinn,
`Macpeak & Seas
`
`[57]
`ABSTRACT
`A pickup actuator includes a slider, an optical pickup
`unit, and at least one suspension arm extending from the
`slider for suspending the pickup unit. The pickup unit
`includes at least one bobbin surrounding a yoke plate,
`upon which a first coil is wound, and further trans(cid:173)
`versely mounted coils attached to the first coil. The
`coils. collectively control movement of the pickup unit
`in tracking, focusing and tilt directions thereof. A fur(cid:173)
`ther bobbin connected to the slider surrounds the yoke
`plate and includes a further coil wound thereabout for
`driving the slider and the pickup unit radially of ·an
`associated optical disk.
`
`11 Claims, 3 Drawing Sheets
`
`0
`7
`------·-~---.
`
`LG Electronics, Inc. et aL
`EXHIBIT 1003
`IPR Petition for
`U.S. Patent No. 6,785,065
`
`

`
`U.S. Patent
`
`Aug. 27, 1991
`
`Sheet 1 of 3
`
`5,043,964
`
`I
`I
`
`(
`Ohl
`
`

`
`U.S. Patent
`
`Aug. 27, 1991
`
`Sheet 2 of 3
`
`5,043,964
`
`FIG. 2
`
`12
`
`l2A
`
`~0 -
`
`12.A
`
`32X
`32Y
`
`32
`ill
`_ __ j
`
`18
`
`43
`
`m
`l._
`
`41
`
`41
`
`FIG. 3
`
`35
`
`34
`
`13
`
`13A ! 31X(31Y) 33 44
`LIV
`
`32X(32Y)
`
`

`
`U.S. Patent
`
`Aug. 27, 1991
`
`Sheet 3 of 3
`
`5,043,964
`
`FIG. 4
`
`T~ING 31A
`
`I!)
`
`z
`-
`V'l
`::::>
`w
`0
`u...
`
`31X ~ 31Y
`TILT
`
`I!)
`z
`-
`V'l
`::::>
`w
`0
`u...
`
`----~5
`
`•.
`
`FIG. 5
`PRIOR ART
`
`

`
`1
`
`5,043,964
`
`LINEAR PICKUP ACI'UATOR FOR MOVING AN
`OPTICAL PICKUP IN A RADIAL DIRECI'IO~ OF
`A DISK
`
`This is a continuation of application No. 07/171,073
`filed Mar. 21, 1988 now U.S. Pat. No. 4,942,562.
`
`BACKGROUND OF THE INVENTION
`The present invention relates. to a pickup actuator,
`and particularly to a pickup actuator having an im(cid:173)
`proved magnetic circuit design which enables the slid(cid:173)
`ing mechanisms to be made light in weight.
`Disk players such as video disk and CD players em(cid:173)
`ploy optical pickups for reading out information stored
`on an optically encoded disk. The pickup is provided
`with a magnetic circuit which is made capable of finely
`driving an objective lens along a focal axis for focusing,
`and in the direction of the encoded information (pits)
`for tracking. A carriage mechanism for driving the
`pickup for moving the same in the radial direction of the
`disk is also provided.
`The carriage mechanism is provided with magnetic
`circuits together with a guide rail which guide the
`pickup along its stroke. The number of magnetic cir(cid:173)
`cuits is three or more in all, together with the magnetic
`circuit provided in the pickup. The magnetic circuits in
`the past have been made large and long, making the
`carriage mechanism overly long and heavy.
`An example of a conventional device is shown in
`FIG. 5. In this device, the pickup 1 is integrated with a
`frame 3, which forms a linear motor, via a stay 2. Yoke
`plates 4 constituting a magnetic circuit pass through
`openings provided in the frame 3. The frame 3 is dis(cid:173)
`posed in an air gap 6 formed by magnets 5, and is mov(cid:173)
`ably supported by a guide bar 7 for linear movement.
`The pickup apparatus of the conventional type in(cid:173)
`cludes 3 independent magnetic circuits. The magnetic
`circuits of the carriage mechanism are so long that the
`total weight is made quite heavy. The power supply
`system for driving the coils is extremely complicated
`and requires a large driving current.
`
`SUMMARY OF THE INVENTION
`The present invention is intended to simplify the
`arrangement of the magnetic circuit system of a car(cid:173)
`riage mechanism to thereby reduce the overall weight
`of the system. In order to obtain this object, the pickup
`actuator includes at least one suspended bobbin support(cid:173)
`ing a coil and loosely fitted around a yoke plate, a sus(cid:173)
`pension arm for suspending the bobbin, at least one
`second coil attached to a side surface o.f the first coil,
`and a pickup unit attached to the bobbin.
`
`BRIEF DESCRIPTION OF THE DRAWING
`FIGURES
`FIG. 1 is a perspective view showing a part of the
`pickup actuator according to the present invention;
`FIG. 2 is a plan view of the apparatus of FIG. 1;
`FIG. 3 is a cross-sectional view taken on line III-III
`of FIG. 2;
`FIG. 4 is a side-view taken along line IV -IV of FIG.
`3; and
`FIG. 5 is a perspective view showing a conventional
`pickup actuator device
`
`2
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`Referring to FIGS. 1-4, an embodiment of the pres-
`S ent invention will be described In the drawings, refer(cid:173)
`ence numeral 10 designates a magnetic circuit unit dis(cid:173)
`posed on a chassis. A spindle motor unit 20 is disposed
`at an end portion of the magnetic circuit unit 10. A
`carriage mechanism 40 is movably attached to the mag-
`10 netic circuit unit 10 so as to move a pickup unit 30 in the
`radial direction of disk D while disk Dis rotated by the
`spindle motor unit 20.
`The carriage mechanism unit 40 includes a slider 43,
`through which a pair of guide rails 41 supported by
`15 holders 42 are inserted, and includes bobbins 31, 32
`suspended from electrically conductive suspension arms
`44 extending from the slider 43. A pair of yoke plates 14
`and 15 extend in the movement direction of the carriage
`40 and are loosely inserted through the bobbins 31, 32.
`20 The bobbins 31 and 32 are supported by the arms 44 in
`the floating state relative to the yoke plates 14, 15. The
`bobbins are movable in the radial direction of the disk
`via the carriage mechanism unit 40 and the arm 44.
`The pickup unit 30 is provided with an objective lens
`25 34, a tilt detection lens 35, and associated circuitry. The
`lenses are disposed on a support 33 located bel\veen the
`bobbins 31 and 32 and are driven together with the
`carriage mechanism 40.
`In the magnetic circuit unit 10, plates 11 and 12 are
`30 disposed with a suitable distance therebetween. not less
`than the stroke of the pickup unit Two pairs of yoke
`plates 13 and 14, 15 and 16. are respectively attached on
`opposite sides of two sets of spacers llA. 12A. The
`plates 11 and 12 are perpendicular support plates which.
`35 connect opposite ends of the pairs of yoke plates 13, 14
`and 15, 16. Plate 11 is positioned at the outer end of the
`pairs of yoke plates, whereas plate 12 (see FIG. 2) is
`positioned at the inner end of the yoke plates closest to
`the spindle motor 20. Air gaps 17 and 18 corresponding
`40 to the thicknesses of the spacers llA and 12A are
`formed between the yoke plates 13 and 14 and between
`the yoke plates 15 and 16, respectively Plate-like mag(cid:173)
`nets 13A and 16A are fixed to the yoke plates 13 and 16
`along their inner surfaces
`A bobbin 36 is fittingly inserted on the yoke plate 14,
`the bobbin 36 being integrated with the slider 43 via a
`carriage coil stay 45. A carriage coil 36A is wound on
`the bobbin 36 to perform the carriage displacement
`operation. Tracking coils 31A and 32A are wound on
`50 the bobbins 31 and 32, respectively. Pairs of tilting and
`focusing coils 31X and 31Y, 32X ·and 32Y are wound
`respectively on the tracking coils 31A and 32A such
`that the coils 31X and 31Y, 32X and 32Y are wound in
`planes perpendicular to the planes in which the tracking
`55 coils 31A and 32A are wound.
`A driving current is supplied to the tracking coils
`31A and 32A, and to the tilting and focusing coils 31X,
`31Y, 32X and 32Y via the suspension arms 44. A current
`is supplied to the carriage coil 36A by a feeder line (not
`60 shown) extending along the carriage coil stay 45.
`A tracking control current is supplied to the tracking
`coils 31A and 32A to control the positioning of a read(cid:173)
`ing light beam with respect to the track of the disk D.
`that is, so that the reading light beam accurately im-
`65 pinges upon the pits formed in the disk. The same cur(cid:173)
`rent is applied to the tilting and focusing coils 3IX and
`31Y so as to control focusing If the disk D is slanted or
`otherwise tilted, a control current is supplied to the pair
`
`45
`
`

`
`5,043,964
`
`3
`of tilting and focusing coils 31X and 31Y so as to con(cid:173)
`trol the tilt of the pickup unit. A carriage driving cur(cid:173)
`rent is supplied to the carriage coil 36A to control the
`advance of the pickup unit 30.
`In order to drive the pickup unit 30 in the focusing 5
`direction, in the tracking direction, or in the tilting
`direction, only the coil elements of the pickup unit 30
`are driven, without moving the slider 43. That is, the
`position and attitude of the pickup unit can be con(cid:173)
`trolled by appropriately energizing the tracking coils 10
`31A and 32A, and the tilting and focusing coils 31X,
`31Y, 32X and 32Y wound on the bobbins 31 and 32. The
`fact that the slider 43 does not move particularly in the
`tracking direction, i.e., in the sliding direction of the
`slider 43, means that no sliding friction is involved, 15
`enabling position-al control to be more easily and finely
`adjusted by the servo mechanism associated with the
`optical system.
`When the pickup unit 30 is driven in the radial direc(cid:173)
`tion, a current is supplied to the carriage coil 36A 20
`wound on bobbin 36 so as to drive the whole of the
`carriage mechanism 40 including the slider 43. In driv(cid:173)
`ing the carriage and the pickup unit, small currents will
`suffice to energize each of the coils because there are no
`heavy magnets required to be moved. Moreover, the
`construction allows the magnets 13A and 16A to be
`commonly employed, reducing the actual number of
`magnets required
`As will be apparent from the foregoing description,
`the pickup actuator according to the present invention
`is arranged so that all of the tracking, focusing and
`carriage movement coils are disposed in the air gap of a
`magnetic circuit unit constituted by a pair of yoke plates
`and magnets fixed to the inner sides of the yoke plates,
`so that the coils can be driven by a common magnetic
`circuit unit. Accordingly, the various magnetic circuits
`can be simplified and the weight of the overall mecha(cid:173)
`nism can be reduced.
`I claim:
`1. A pickup actuator for moving an optical pickup 40
`unit in a radial direction of disk-type media and control(cid:173)
`ling the position of the optical pickup unit, said pickup
`actuator comprising:
`an optical pickup unit;
`a magnetic circuit unit having a magnet extending in 45
`said radial direction, a yoke plate extending parallel
`with said magnet and an air gap defined between
`said magnet and said yoke plate;
`first and second bobbins loosely fitted around said
`yoke plate;
`a first coil wound on said first bobbin;
`a second coil fixed to a side surface of said first coil
`and disposed in said air gap;
`a third coil wound on said second bobbin; and
`means for supporting and connecting an optical 55
`pickup unit to said first and second bobbins.
`
`4
`2. The pickup actuator according to claim 1, wherein
`said first coil is adapted to control the position of said
`optical pickup unit in a tracking direction.
`3. The pickup actuator according to claim 1, \vherein
`said second coil is adapted to control the position of said
`optical pickup unit in the focusing direction.
`4. The pickup actuator according to claim 1, wherein
`said optical pickup unit includes a tilt detection lens for
`detecting the tilt of said optical pickup unit, and
`wherein said second coil is adapted to control the posi(cid:173)
`tion of said optical pickup unit in a tilting direction.
`5. The pickup actuator according to claim 1, wherein
`said third coil is adapted to move said optical pickup
`unit in said radial direction.
`6. The pickup actuator according to claim 1, wherein
`said optical pickup unit includes an objective lens and
`means for supporting said lens.
`7. The pickup actuator according to claim 1, wherein
`said supporting and connecting means includes a sus(cid:173)
`pension arm for suspending said first bobbin in a floating
`state relative to said first yoke plate.
`8. The pickup actuator according to claim 7, wherein
`said supporting and connecting means further includes
`at least one guide rail extending in parallel with said
`25 magnetic circuit and a slider supported on said at least
`one guide rail, said slider being attached to one end of
`said suspension arm for supporting said suspension arm.
`9. The pickup actuator according to claim 7. wherein
`said suspension arm is electrically conductive. and
`30 wherein said first coil and said second coil are energized
`via said suspension arm.
`10. The pickup actuator according to claim 8,
`wherein said second bobbin is connected to said slider.
`11. A pickup actuator for moving an optical pickup
`35 along a magnetic circuit unit including at least one yoke
`plate which is extended in a radial direction of a disk,
`comprising at least one bobbin loosely fitted around said
`yoke plate and movable therealong in the radial direc-
`tion of said disk, a first coil wound on said bobbin. for
`controlling the position of said optical pickup unit in a
`tracking direction. second coil means attached to a side
`surface of said first coil, a suspension arm for suspend(cid:173)
`ing said bobbin in a floating state relative to said yoke
`plate, and an optical pickup unit connected to said bob(cid:173)
`bin;
`said pickup actuator including at least one guide rail.
`a slider supported on said guide rail for movement
`parallel to said guide rail, said suspension arm hav(cid:173)
`ing one end attached to said slider; and
`further including a second bobbin rigidly connected
`to said slider. said second bobbin surrounding said
`yoke plate, and a carriage driving coil wound
`around said second bobbin to thereby control ad(cid:173)
`vance of said optical pickup unit in said radial di(cid:173)
`. rection of said disk.
`* * * * *
`
`50
`
`60
`
`65