CA1213048A - Apparatus for recording and/or reading information on an optically readable disc - Google Patents
Apparatus for recording and/or reading information on an optically readable discInfo
- Publication number
- CA1213048A CA1213048A CA000439258A CA439258A CA1213048A CA 1213048 A CA1213048 A CA 1213048A CA 000439258 A CA000439258 A CA 000439258A CA 439258 A CA439258 A CA 439258A CA 1213048 A CA1213048 A CA 1213048A
- Authority
- CA
- Canada
- Prior art keywords
- drive means
- carrier
- lens system
- axis
- along
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
Abstract
ABSTRACT:
An apparatus for recording and/or reading infor-mation on an optically readable disc (3) comprises a car-rier (6) which can be driven along a first axis (4) in order to move a lens system (1), which is arranged on the carrier relative to the disc. The lens system is also driven along the first axis by drive means (33) which act directly, i.e. not via the supporting means (21, 22) in order to minimize the load exerted on these supporting means.
An apparatus for recording and/or reading infor-mation on an optically readable disc (3) comprises a car-rier (6) which can be driven along a first axis (4) in order to move a lens system (1), which is arranged on the carrier relative to the disc. The lens system is also driven along the first axis by drive means (33) which act directly, i.e. not via the supporting means (21, 22) in order to minimize the load exerted on these supporting means.
Description
3~L8 ~1-IN lO 58~ 9-1983 "~pparatus for recording and/or reading information on an o-ptically readable disc."
The invention relates to apparatus for recording and/or reading in:formation on an optically readable disc which apparatus comprises- a frame; a carrier which is movable relative to the frame along a first axis; first electrodynamic drive means for driving the carrier along the first a~is; a lens system which is arranged on -the carrier and which is movable relative thereto along a second a~is perpendicular to the first a~is; second elec-trodynamic drive means for driving the lens system along the second axis; and a lens system-supporting arrangement comprising supporting means arranged between the carrier and the lens system. ~Ierein "frame" is to be understood to mean that Part of the apparatus with which the carrier co-operates directly via the first electrod,vnamic drive means. The frame itself may also be movabla rela-tive to another part of the aPParatUs. The term "lens system" is to be understood to mean a system comprising at least one lens. The lens system may comprise, for example~ a bodily movable objective but it may alternatively form a Part of 2n ~l object:ive whose other part may be rigidly connected to the carrier.
Apparatus as described above is known in various versions, for e~ample in optical video-disc players~ optical audio-disc players or peripheral computer
The invention relates to apparatus for recording and/or reading in:formation on an optically readable disc which apparatus comprises- a frame; a carrier which is movable relative to the frame along a first axis; first electrodynamic drive means for driving the carrier along the first a~is; a lens system which is arranged on -the carrier and which is movable relative thereto along a second a~is perpendicular to the first a~is; second elec-trodynamic drive means for driving the lens system along the second axis; and a lens system-supporting arrangement comprising supporting means arranged between the carrier and the lens system. ~Ierein "frame" is to be understood to mean that Part of the apparatus with which the carrier co-operates directly via the first electrod,vnamic drive means. The frame itself may also be movabla rela-tive to another part of the aPParatUs. The term "lens system" is to be understood to mean a system comprising at least one lens. The lens system may comprise, for example~ a bodily movable objective but it may alternatively form a Part of 2n ~l object:ive whose other part may be rigidly connected to the carrier.
Apparatus as described above is known in various versions, for e~ample in optical video-disc players~ optical audio-disc players or peripheral computer
2~ equipment for the storage and reproduction of information on optical storage discs. In all these devices the lens system is movable along the focusing a~is in order to enable movements of the information surface, which in~
evi-tably occur during rotation of the disc, to be followed accurately wi-th the laser beam ~hich is formed to a read sPot. This is necessary because the depth of focus o~ the lens systems used is of the order of magnitude of a few microns only. Therefore, there must be provided one or
evi-tably occur during rotation of the disc, to be followed accurately wi-th the laser beam ~hich is formed to a read sPot. This is necessary because the depth of focus o~ the lens systems used is of the order of magnitude of a few microns only. Therefore, there must be provided one or
3~
PHN 10 5~3 2 more supporting arrangements which permi-t the focusing movements of the lens system and, depending on the con-struction of the apparatus, permit radial movements for ~ollowing the track and tangential movement for correcting time errors. The supporting arrangements inhibit undesired movements of the lens system. The radial travel of the carrier on which the lens system is arranged is such that the read spot can reach every track on the optically read-able disc. For the rapid location of a track, or for rapidly finding a blank part of the optically readable disc in order to record information in this part, it is important that the slide can be moved rapidly along the radial path. Since the lens system has a certain mass, radial forces are exerted on the lens system during the fast radial movements of the carrier r which forces may be of an amplitude such that problems may arise when the lens system is simultaneously moved along the focusing axis, perpendicularly to said path. Depending on the type of lens system supporting arrangement used, these problems may be friction problems and bandwidth problems. This will be explained in more detail with reference to some known devices of the afore-mentioned type.
U.SO Patent 4,443,721 describes a device in which the lens system comprises an objective which is mov-ably supported on t~e carrier by means of a plurality ofblade springs which extend in the same direction as the first axis. The carrier comprises a translating slide.
The bandwidth for the slide drive is limited because at high frequencies the blade springs are no longer suffici-ently rigid in the direction of translation. The defor-mation of the blade springs then gives rise to movements of the objective relative to the slide in the direction of translation.
It is also known, for example from United States Patent Specification 4,021,101 (PHN 7938) to use a sleeve supporting arrange-~Z~
PIIN lO 5~3 3 ~ 19~3 ment for -the lens system. The lens system is an obJec-tive ~hich is movable in a supporting sleeve, which in-evitably gives rise to some ~ric-tion. The o'bjective is movable relative to a transla-ting slide. In -the case of slo-~ or uni~orm -transla-t:ional movemen-ts o~ the slide this ~riction is very low because no forces ac-t on the objec-tive in the direction o~ translation and7 consequen-tly, in a direction normal to the ~riction sur~aces o~ -the lens-system supporting arrangement. This is di~ferent i~
the slide must be moved with high accelerations and de-celerations. The ~rictional ~orces then occurring depend directly on the accelerations and decelerations o~ the slide movemen-t. Both the movements o~ the objective along the ~ocusing axis and the movements o~ the slide are con-trolled by electronic servo-circuits. The variable fric-tion in a ~ocusing supporting arrangement gi-ves rise to cross-talk between the two servo-circuits. Another problem is caused by the radial clearance between -the objective and the sleeve. Tracking becomes more di~icult when 20 radial ~orces are exerted on -the objective because then the objec-tive does not occupy a well-de~ined position in the sleeve but is urged either against one wall or against the other wall, depending on the direction o~ movement o~
the slide. This may be precluded by providing a prestress 25 in the lens-system supporting arrangement. fIowever~ this lead5 to an increase Or the ~riction in the supporting arrangement, which is undesirable ~or several reasons, whilst the modulation o~ the ~rictional ~orce as a result o~ the accelerations and decelerations o~ the slide Per-30 sists It is an object of the invention to provide anapparatus o~ the a~ore-mentioned type which largely miti-gates the ~riction problems and 'bandwidth problems des-cribed in the foregoing. To this end the invention is 35 characterized in that -there are provided third drive means ~or subjecting the lens system directly, i.e. not via the suPPorting rneans, -to ~orces acting along the ~irst axis. By driving the lens system along -the ~irst a~is not B
PHN lO 583 4 indirectly or not only indirectly via the supporting means but directly or also directly by separate third drive means, it is possible to avoid subjecting the supporting means to considerable forces during the acceleration and deceleration of -~he carrier. Undesired forces exerted on the supporting means can be eliminated almost completely with an embodiment of the i~vention which is characterized in that the ratio between the driving forces exerted by the first drive means and by the third drive means respec-tively on the carrier and on the lens system including theparts connected thereto is at least roughly equal to the ratio between ~he masses of the carrier and the lens system including said parts. As a result of this the driving forces along the first axis exerted on the lens system and on the carrier give rise to at least roughly equal accel-erations and decelerations. In principle this means that no forces at all which act along the first axis have to be transmitted by the lens system supporting means.
In the apparatus in accordance with the afore-mentioned U.S. Patent 4,443,721 the irst drive means com-prise stationary first drive means on the frame and mov-able first drive means on the slide. These two means cooperate magn~tical]y in an air gap which extends paral-lel to the first axis. In such an apparatus an embodiment of the invention can be of advantage which is character-ized in that said third drive means comprise movable third drive means connected to the lens system, which movable third drive means cooperate magnetically in said air gap with the first drive means arranged on the frame. The advantages of this last-mentioned embodiment will be described in more detail with reference to the drawings.
An embodlment of the invention will now be descrihed in more detail, by way of example, with refer-ence to the drawings, in which:
Fig. l is a plan view of an apparatus in accor~
dance with the invention, L3~8 , PIIN lO 5S3 5 8-9-1983 Fig. 2 is a longitudinal sectional view taken on -the lines II-II in ~ig. 1, and Fig. 3 is a transverse sectional vie~ -taken on the lines -CII-III in Fig. 1~
The apparatus shown in Figs. 1 to 3 -transla-tes a lens system in the form of an objective I aLong a radial ~irst a~is or path 4 relative to a disc 3 which rotates abou~ an axis of rotation 2. The apparatus comprises a frame 5 and a carrier in the form of a slide 6 which n carries -the objective 1 and which can be translated rela-tive to the frame along the radial path 4. The frame carries sta-tionary first drive means in the form o~ two permanent stator magnets 7A and 7B, which extend parallel to the pa-th 4 and which are magnetised transversely of said path, the directions of magne-tisation being indi-cated by arrows in Fig. 1. r~lovable ~'irs-t drive means comprising two translatable drive coils 8A and 8B of an electrically conductive material are movable in the mag-netic ~ield o~ the stator magnets.
A Parallel-guide arrangement for the slide 6 comprises two guide rods 9A and 9B and four sliding bearing bushes 10 made of tetra-fluoroethylene. The guide rods are secured to the ~rame 5 by screws 11. The rods 9A
and 9B form part of a s-tator yoke wi-th air gaps 12A and ~5 12B respectively between the stator magnet 7~ and the guide rod 9A and between the stator magne-t 7B and the guide rod 9B, respectively. The drive coils 8A and 8B are arranged aro~d the guide rods 9~ and 9B respectively and form a structural part o~' -the slide. In addi-tion to the 30 coils the slide comprises two end plates ll~ and 15. These end plates serve to interconnect -the two coilsand are preferably made of a non-rnagnetisable light-~eight but strong material such as a plastics or aluminium.
The objective I is movable relative to the 35 slide 6 along a second axis, namely its optical axis 18 so as to enable the movements of the disc ~ to be followed by means o~ the read spot 19 ~ormed by a radiation beann 20 emitted by a radiation source, not shown. The okjective , ~l3~
Pl-IN 10 5~3 6 8-9-1983 is supported on the slide 6 by a lens system or o'bjective-supporting arrangement comprising two blacle sPrings 21 at -the upper side of the slide and two 'blade sPringS 22 at the lower side. The objective :is arranged on a unit 2'3, which is bodily movable to a limited e~ctent along the optical a.Yis 18 and which at its ends carries movable second or ~ocusing dri-ve means ln the :E'orm of two actua-tor coils 24~ and 2l~B. The upper parts of these actuator coils 2~ and 24B are movable in the air gaps 12.h and 12B res-pecti~ely between the guide rods 9~ and 9B and the stator ma~,nets 7L~ and 7B, so that the actuator coils cooperate with the field of the stator magnets to e.~cert forces on the objec tive along the optical a~is. Thus, the stator magnets are used both for driving the slide along the path 1l and for driving the objective along the a~is 18.
The frame 5 is made ot' a magnetisable ma-terial, f`or e~ample irong and forms part of a stator yoke which carries the permanent magnets 7~ and 7B and of ~hich the guide rods 9~ and 9B also form part, as already s-tated.
The frame 5 is shaped substantially as an open box having a bottom 25 and upright walls 26A~ 26B and 27~, 27B. l`hese walls are not joined to one another at the corners of the frame. The comple-te frame is f`ormed from a singrle blanl~ of sheet material, the walls being 25 forme(l by portions which are b~nt up from -the bottom 25. 't`he stator mag~nets 7A and 7B are secured to the inner sides o~ the walls 26~ and 26B, for e~caMple b~ a suitable adhesive. The lines of force magnetic o~ the ma~lets e~ctend from the magrnets 7~ and 7B through the air 3a gaps 12~ and '12B to the guide rods 91~ and 9B, whose ends are mounted on portions of the walls 27~ and 27B. Thus the guide rods are in contact hTith the magnetisable frame 5, so that the magnetic circui-t is closed through the Erame.
In order to ensure that the guide rods 9A and 9B e~tent e~cac tly Parallel to each other and are disposed at the same level, recesses 28 ~Ti th V-shaped bo-ttoms are formed in the walls 27~ and 27B to receive the rods. These ~Z~3~
PI~ 10 583 7 8-9-19X3 recesses can be formed with the required accuracy by a sim-ple machining operation. No stringen-t requirements are imposed on the accuracy of the other parts of the frame 5. The accuracy o~ the guide arrangement for the slide 6 is mainly determined by the accuracy of the shaPe and dimensions of the guide rods 9~ and 9B and the accuracy with which they extend parallel to each other and are supported at the same level by the frame.
In the wall 27A an apert-ure 29 is ~ormed which serves inter alia for the passage o~' the radiation beam 20. On its underside the objective 1 carries a re~lecting element 30 which reflects the radiation beam through an angle of 90 . The aperture 29 may also serve for the passage of the electrical connecting wires to the coils 8A and SB on the slide and -the actuator coils 24~ and 24B. These connecting wires and other electrical connec-tions have been omitted from the drawings for the salse o~ simplicity and are irrelevant to the present invention.
The means which are generally required ~or detecting the 20 position of the objective 1 in the path 4 are not shown and are also irrelevant to the present invention.
For exerting direc-tly on the objective 1, i.e. not via the blade springs 21 and 22~ ~orces which act along the radial path 4, third objective-drive means 25 are provided in the form of two drive coils 33~ and 33B.
In the air gaps 12~ and 12B these coils cooperate mag-netically with the permanen-t mag~netic stator, which there-fore serves not onl~ for driving -the slide ~ along the axis 4 and for driving the objective along the axis -18, 30 but also ~or exerting radial forces on the objective 1.
The coils 33A and 33B are arranged around the guide rods 9A and 9B and have a rec-tangular shaPe so -that the~ do not impede movements o~ the objective along the ~ocusing axis. The objective 1 is arranged in a mo~mt 34. This 35 mount together with two aluminium plates 35 glued to two opposite sides o~ said ~ount~ the coils 33A and 33B
glued between said plates, and the coils 24A and 24B~
which are also glued to the plates 35, constitute the uni-t . .
~3~8 Pl~ 10 5~3 ~ 8-9-19~3 2~.
The drive coils ~A and SB for the slide and the drive coils 33A and 33B for -the objective are dimensioned so tha-t the radial driving forces e~erted on the slide 6 and on the objective 1 respectively have the same ratio as the respective masses of the slide and of the unit 23. As a result of this, no radial forces have to be transmitted via the springs 21 and 22 to the end plate 1 4 at one end and to the mount 24 at the other end~
Several embodiments of the invention are pos-sible within the scope of the invention as defined by the Claims. For example, it is not necessary to drive the objective in the radial direction by means of coils ~hich cooperate with the permanen-t magnetic stator of the slide drive~ Third drive means may be employed which are com-pletely independent of the first drive means and which comprise a separate s-tator. The use of blade springs for the objective-supporting arrangement ensures that relative movaments in the radial direction between the slide and ~ the objective are precluded, even if the ratio between the respective driving forces is not completely correct.
The invention is not only applicable to apparatus for rotating optical disc but it may also be used in apparatus in which a stationary, no-t necessarily round, disc is 25 read and/or reeorded b~ means of a carrier which is movable in a plurality of direc-tions.
Alternatively~ the apparatus in accordance with the invention may be a modification of a l~nown focusing device in whicll the lens system is driven in the focusing 30 direction by first drive means and is driven in a direction perpendicular to the optical axis by second drive means.
The lens system is flexibly supported on the carrier which is movable in the focusing direction. By providing this known focusing device with additional third drive means 35 which subject the lenS system to forces which aet in the focusing direction and which are exerted directly, i e.
not v the ~lexible suPporting means, this device can also be improved in a manner which is characteristic of the . .
~IIN 10 5~3 ~-9-19~3 p:resent invention.
It will be eviden-t ~rom the ~oregoing -that the scope of -the inven-tion is no-t limited to the embo~imen-ts sho~ and described herein but covers all appara-tuses 5 mentioned in the opening paragraph in -which a lens system is arranged on a carrier which is driven along a first axis and is movable relative thereto by second drive means along a second axis normal to the first axis, which apparatuses have been improved, in order to minimize the l.oad exerted on the suPPorting means arranged between the lens system and the carrier, by the addition o~ third drive means which drive the lens s~stem directly along the first axis.
PHN 10 5~3 2 more supporting arrangements which permi-t the focusing movements of the lens system and, depending on the con-struction of the apparatus, permit radial movements for ~ollowing the track and tangential movement for correcting time errors. The supporting arrangements inhibit undesired movements of the lens system. The radial travel of the carrier on which the lens system is arranged is such that the read spot can reach every track on the optically read-able disc. For the rapid location of a track, or for rapidly finding a blank part of the optically readable disc in order to record information in this part, it is important that the slide can be moved rapidly along the radial path. Since the lens system has a certain mass, radial forces are exerted on the lens system during the fast radial movements of the carrier r which forces may be of an amplitude such that problems may arise when the lens system is simultaneously moved along the focusing axis, perpendicularly to said path. Depending on the type of lens system supporting arrangement used, these problems may be friction problems and bandwidth problems. This will be explained in more detail with reference to some known devices of the afore-mentioned type.
U.SO Patent 4,443,721 describes a device in which the lens system comprises an objective which is mov-ably supported on t~e carrier by means of a plurality ofblade springs which extend in the same direction as the first axis. The carrier comprises a translating slide.
The bandwidth for the slide drive is limited because at high frequencies the blade springs are no longer suffici-ently rigid in the direction of translation. The defor-mation of the blade springs then gives rise to movements of the objective relative to the slide in the direction of translation.
It is also known, for example from United States Patent Specification 4,021,101 (PHN 7938) to use a sleeve supporting arrange-~Z~
PIIN lO 5~3 3 ~ 19~3 ment for -the lens system. The lens system is an obJec-tive ~hich is movable in a supporting sleeve, which in-evitably gives rise to some ~ric-tion. The o'bjective is movable relative to a transla-ting slide. In -the case of slo-~ or uni~orm -transla-t:ional movemen-ts o~ the slide this ~riction is very low because no forces ac-t on the objec-tive in the direction o~ translation and7 consequen-tly, in a direction normal to the ~riction sur~aces o~ -the lens-system supporting arrangement. This is di~ferent i~
the slide must be moved with high accelerations and de-celerations. The ~rictional ~orces then occurring depend directly on the accelerations and decelerations o~ the slide movemen-t. Both the movements o~ the objective along the ~ocusing axis and the movements o~ the slide are con-trolled by electronic servo-circuits. The variable fric-tion in a ~ocusing supporting arrangement gi-ves rise to cross-talk between the two servo-circuits. Another problem is caused by the radial clearance between -the objective and the sleeve. Tracking becomes more di~icult when 20 radial ~orces are exerted on -the objective because then the objec-tive does not occupy a well-de~ined position in the sleeve but is urged either against one wall or against the other wall, depending on the direction o~ movement o~
the slide. This may be precluded by providing a prestress 25 in the lens-system supporting arrangement. fIowever~ this lead5 to an increase Or the ~riction in the supporting arrangement, which is undesirable ~or several reasons, whilst the modulation o~ the ~rictional ~orce as a result o~ the accelerations and decelerations o~ the slide Per-30 sists It is an object of the invention to provide anapparatus o~ the a~ore-mentioned type which largely miti-gates the ~riction problems and 'bandwidth problems des-cribed in the foregoing. To this end the invention is 35 characterized in that -there are provided third drive means ~or subjecting the lens system directly, i.e. not via the suPPorting rneans, -to ~orces acting along the ~irst axis. By driving the lens system along -the ~irst a~is not B
PHN lO 583 4 indirectly or not only indirectly via the supporting means but directly or also directly by separate third drive means, it is possible to avoid subjecting the supporting means to considerable forces during the acceleration and deceleration of -~he carrier. Undesired forces exerted on the supporting means can be eliminated almost completely with an embodiment of the i~vention which is characterized in that the ratio between the driving forces exerted by the first drive means and by the third drive means respec-tively on the carrier and on the lens system including theparts connected thereto is at least roughly equal to the ratio between ~he masses of the carrier and the lens system including said parts. As a result of this the driving forces along the first axis exerted on the lens system and on the carrier give rise to at least roughly equal accel-erations and decelerations. In principle this means that no forces at all which act along the first axis have to be transmitted by the lens system supporting means.
In the apparatus in accordance with the afore-mentioned U.S. Patent 4,443,721 the irst drive means com-prise stationary first drive means on the frame and mov-able first drive means on the slide. These two means cooperate magn~tical]y in an air gap which extends paral-lel to the first axis. In such an apparatus an embodiment of the invention can be of advantage which is character-ized in that said third drive means comprise movable third drive means connected to the lens system, which movable third drive means cooperate magnetically in said air gap with the first drive means arranged on the frame. The advantages of this last-mentioned embodiment will be described in more detail with reference to the drawings.
An embodlment of the invention will now be descrihed in more detail, by way of example, with refer-ence to the drawings, in which:
Fig. l is a plan view of an apparatus in accor~
dance with the invention, L3~8 , PIIN lO 5S3 5 8-9-1983 Fig. 2 is a longitudinal sectional view taken on -the lines II-II in ~ig. 1, and Fig. 3 is a transverse sectional vie~ -taken on the lines -CII-III in Fig. 1~
The apparatus shown in Figs. 1 to 3 -transla-tes a lens system in the form of an objective I aLong a radial ~irst a~is or path 4 relative to a disc 3 which rotates abou~ an axis of rotation 2. The apparatus comprises a frame 5 and a carrier in the form of a slide 6 which n carries -the objective 1 and which can be translated rela-tive to the frame along the radial path 4. The frame carries sta-tionary first drive means in the form o~ two permanent stator magnets 7A and 7B, which extend parallel to the pa-th 4 and which are magnetised transversely of said path, the directions of magne-tisation being indi-cated by arrows in Fig. 1. r~lovable ~'irs-t drive means comprising two translatable drive coils 8A and 8B of an electrically conductive material are movable in the mag-netic ~ield o~ the stator magnets.
A Parallel-guide arrangement for the slide 6 comprises two guide rods 9A and 9B and four sliding bearing bushes 10 made of tetra-fluoroethylene. The guide rods are secured to the ~rame 5 by screws 11. The rods 9A
and 9B form part of a s-tator yoke wi-th air gaps 12A and ~5 12B respectively between the stator magnet 7~ and the guide rod 9A and between the stator magne-t 7B and the guide rod 9B, respectively. The drive coils 8A and 8B are arranged aro~d the guide rods 9~ and 9B respectively and form a structural part o~' -the slide. In addi-tion to the 30 coils the slide comprises two end plates ll~ and 15. These end plates serve to interconnect -the two coilsand are preferably made of a non-rnagnetisable light-~eight but strong material such as a plastics or aluminium.
The objective I is movable relative to the 35 slide 6 along a second axis, namely its optical axis 18 so as to enable the movements of the disc ~ to be followed by means o~ the read spot 19 ~ormed by a radiation beann 20 emitted by a radiation source, not shown. The okjective , ~l3~
Pl-IN 10 5~3 6 8-9-1983 is supported on the slide 6 by a lens system or o'bjective-supporting arrangement comprising two blacle sPrings 21 at -the upper side of the slide and two 'blade sPringS 22 at the lower side. The objective :is arranged on a unit 2'3, which is bodily movable to a limited e~ctent along the optical a.Yis 18 and which at its ends carries movable second or ~ocusing dri-ve means ln the :E'orm of two actua-tor coils 24~ and 2l~B. The upper parts of these actuator coils 2~ and 24B are movable in the air gaps 12.h and 12B res-pecti~ely between the guide rods 9~ and 9B and the stator ma~,nets 7L~ and 7B, so that the actuator coils cooperate with the field of the stator magnets to e.~cert forces on the objec tive along the optical a~is. Thus, the stator magnets are used both for driving the slide along the path 1l and for driving the objective along the a~is 18.
The frame 5 is made ot' a magnetisable ma-terial, f`or e~ample irong and forms part of a stator yoke which carries the permanent magnets 7~ and 7B and of ~hich the guide rods 9~ and 9B also form part, as already s-tated.
The frame 5 is shaped substantially as an open box having a bottom 25 and upright walls 26A~ 26B and 27~, 27B. l`hese walls are not joined to one another at the corners of the frame. The comple-te frame is f`ormed from a singrle blanl~ of sheet material, the walls being 25 forme(l by portions which are b~nt up from -the bottom 25. 't`he stator mag~nets 7A and 7B are secured to the inner sides o~ the walls 26~ and 26B, for e~caMple b~ a suitable adhesive. The lines of force magnetic o~ the ma~lets e~ctend from the magrnets 7~ and 7B through the air 3a gaps 12~ and '12B to the guide rods 91~ and 9B, whose ends are mounted on portions of the walls 27~ and 27B. Thus the guide rods are in contact hTith the magnetisable frame 5, so that the magnetic circui-t is closed through the Erame.
In order to ensure that the guide rods 9A and 9B e~tent e~cac tly Parallel to each other and are disposed at the same level, recesses 28 ~Ti th V-shaped bo-ttoms are formed in the walls 27~ and 27B to receive the rods. These ~Z~3~
PI~ 10 583 7 8-9-19X3 recesses can be formed with the required accuracy by a sim-ple machining operation. No stringen-t requirements are imposed on the accuracy of the other parts of the frame 5. The accuracy o~ the guide arrangement for the slide 6 is mainly determined by the accuracy of the shaPe and dimensions of the guide rods 9~ and 9B and the accuracy with which they extend parallel to each other and are supported at the same level by the frame.
In the wall 27A an apert-ure 29 is ~ormed which serves inter alia for the passage o~' the radiation beam 20. On its underside the objective 1 carries a re~lecting element 30 which reflects the radiation beam through an angle of 90 . The aperture 29 may also serve for the passage of the electrical connecting wires to the coils 8A and SB on the slide and -the actuator coils 24~ and 24B. These connecting wires and other electrical connec-tions have been omitted from the drawings for the salse o~ simplicity and are irrelevant to the present invention.
The means which are generally required ~or detecting the 20 position of the objective 1 in the path 4 are not shown and are also irrelevant to the present invention.
For exerting direc-tly on the objective 1, i.e. not via the blade springs 21 and 22~ ~orces which act along the radial path 4, third objective-drive means 25 are provided in the form of two drive coils 33~ and 33B.
In the air gaps 12~ and 12B these coils cooperate mag-netically with the permanen-t mag~netic stator, which there-fore serves not onl~ for driving -the slide ~ along the axis 4 and for driving the objective along the axis -18, 30 but also ~or exerting radial forces on the objective 1.
The coils 33A and 33B are arranged around the guide rods 9A and 9B and have a rec-tangular shaPe so -that the~ do not impede movements o~ the objective along the ~ocusing axis. The objective 1 is arranged in a mo~mt 34. This 35 mount together with two aluminium plates 35 glued to two opposite sides o~ said ~ount~ the coils 33A and 33B
glued between said plates, and the coils 24A and 24B~
which are also glued to the plates 35, constitute the uni-t . .
~3~8 Pl~ 10 5~3 ~ 8-9-19~3 2~.
The drive coils ~A and SB for the slide and the drive coils 33A and 33B for -the objective are dimensioned so tha-t the radial driving forces e~erted on the slide 6 and on the objective 1 respectively have the same ratio as the respective masses of the slide and of the unit 23. As a result of this, no radial forces have to be transmitted via the springs 21 and 22 to the end plate 1 4 at one end and to the mount 24 at the other end~
Several embodiments of the invention are pos-sible within the scope of the invention as defined by the Claims. For example, it is not necessary to drive the objective in the radial direction by means of coils ~hich cooperate with the permanen-t magnetic stator of the slide drive~ Third drive means may be employed which are com-pletely independent of the first drive means and which comprise a separate s-tator. The use of blade springs for the objective-supporting arrangement ensures that relative movaments in the radial direction between the slide and ~ the objective are precluded, even if the ratio between the respective driving forces is not completely correct.
The invention is not only applicable to apparatus for rotating optical disc but it may also be used in apparatus in which a stationary, no-t necessarily round, disc is 25 read and/or reeorded b~ means of a carrier which is movable in a plurality of direc-tions.
Alternatively~ the apparatus in accordance with the invention may be a modification of a l~nown focusing device in whicll the lens system is driven in the focusing 30 direction by first drive means and is driven in a direction perpendicular to the optical axis by second drive means.
The lens system is flexibly supported on the carrier which is movable in the focusing direction. By providing this known focusing device with additional third drive means 35 which subject the lenS system to forces which aet in the focusing direction and which are exerted directly, i e.
not v the ~lexible suPporting means, this device can also be improved in a manner which is characteristic of the . .
~IIN 10 5~3 ~-9-19~3 p:resent invention.
It will be eviden-t ~rom the ~oregoing -that the scope of -the inven-tion is no-t limited to the embo~imen-ts sho~ and described herein but covers all appara-tuses 5 mentioned in the opening paragraph in -which a lens system is arranged on a carrier which is driven along a first axis and is movable relative thereto by second drive means along a second axis normal to the first axis, which apparatuses have been improved, in order to minimize the l.oad exerted on the suPPorting means arranged between the lens system and the carrier, by the addition o~ third drive means which drive the lens s~stem directly along the first axis.
Claims (3)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An apparatus for recording and/or reading infor-mation on an optically readable disc, which apparatus com-prises:
- a frame, - a carrier which is movable relative to the frame along a first axis, - first electrodynamic drive means for driving the carrier along the first axis, - a lens system which is arranged on the carrier and which is movable relative thereto along a second axis perpen-dicular to the first axis, - second electrodynamic drive means for driving the lens system along the second axis, and - a lens-system supporting arrangement comprising support-ing means arranged between the carrier and the lens system, characterized in that there are provided third drive means for subjecting the lens system directly, i.e. not via the supporting means, to forces acting along the first axis of the carrier.
- a frame, - a carrier which is movable relative to the frame along a first axis, - first electrodynamic drive means for driving the carrier along the first axis, - a lens system which is arranged on the carrier and which is movable relative thereto along a second axis perpen-dicular to the first axis, - second electrodynamic drive means for driving the lens system along the second axis, and - a lens-system supporting arrangement comprising support-ing means arranged between the carrier and the lens system, characterized in that there are provided third drive means for subjecting the lens system directly, i.e. not via the supporting means, to forces acting along the first axis of the carrier.
2. An apparatus as claimed in Claim 1, characterized in that the ratio between the driving forces exerted by the first drive means and by the third drive means respect-ively on the carrier and on the lens system including the parts connected thereto is at least roughly equal to the ratio between the masses of the carrier and the lens sys-tem including said parts.
3. An apparatus as claimed in Claim 1, in which the first drive means comprise first drive means on the frame and first drive means on the carrier which are movable relative thereto, which two means cooperate magnetically with each other in an air gap which extends parallel to said first axis, characterized in that said third drive means comprise movable third drive means connected to the lens system, which movable third drive means cooperate mag-netically in said air gap with the first drive means arranged on the frame.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL8300540 | 1983-02-14 | ||
| NL8300540 | 1983-02-14 | ||
| EP83201437.7 | 1983-10-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1213048A true CA1213048A (en) | 1986-10-21 |
Family
ID=19841410
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000439258A Expired CA1213048A (en) | 1983-02-14 | 1983-10-19 | Apparatus for recording and/or reading information on an optically readable disc |
Country Status (8)
| Country | Link |
|---|---|
| US (2) | US4504935A (en) |
| EP (1) | EP0118626B1 (en) |
| JP (1) | JPS59148153A (en) |
| CA (1) | CA1213048A (en) |
| DE (1) | DE3373155D1 (en) |
| ES (1) | ES526601A0 (en) |
| HK (1) | HK34989A (en) |
| SG (1) | SG27888G (en) |
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| JPH0719382B2 (en) * | 1986-08-20 | 1995-03-06 | 沖電気工業株式会社 | Objective lens drive |
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| KR920002933B1 (en) * | 1989-05-25 | 1992-04-10 | 삼성전자 주식회사 | Optical pick-up driving apparatus for recording system of optical information |
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| US5265079A (en) | 1991-02-15 | 1993-11-23 | Applied Magnetics Corporation | Seek actuator for optical recording |
| US6141300A (en) * | 1989-06-20 | 2000-10-31 | Discovision Associates | Optical actuator including lens assembly with optical axis having symmetric suspensory forces acting thereon and optical disc system including same |
| JPH0323523A (en) * | 1989-06-21 | 1991-01-31 | Sony Corp | Optical head device |
| DE69026429T2 (en) * | 1989-06-30 | 1996-11-14 | Fuji Xerox Co Ltd | Magneto-optical recording / playback device |
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| JP2937262B2 (en) * | 1989-11-27 | 1999-08-23 | オリンパス光学工業株式会社 | Optical system drive |
| JP2808767B2 (en) * | 1989-12-28 | 1998-10-08 | 富士ゼロックス株式会社 | Optical disk drive |
| JPH03254425A (en) * | 1990-01-31 | 1991-11-13 | Ricoh Co Ltd | Optical disk driver |
| JP2870112B2 (en) * | 1990-04-13 | 1999-03-10 | 三菱電機株式会社 | Flexible disk drive |
| JP2793698B2 (en) * | 1990-06-18 | 1998-09-03 | 株式会社リコー | Focus offset correction method |
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| US6069857A (en) * | 1991-02-15 | 2000-05-30 | Discovision Associates | Optical disc system having improved circuitry for performing blank sector check on readable disc |
| US6236625B1 (en) | 1991-02-15 | 2001-05-22 | Discovision Associates | Optical disc system having current monitoring circuit with controller for laser driver and method for operating same |
| US5729511A (en) * | 1991-02-15 | 1998-03-17 | Discovision Associates | Optical disc system having servo motor and servo error detection assembly operated relative to monitored quad sum signal |
| US5677899A (en) | 1991-02-15 | 1997-10-14 | Discovision Associates | Method for moving carriage assembly from initial position to target position relative to storage medium |
| US5808980A (en) * | 1991-02-15 | 1998-09-15 | Discovision Associates | Seek actuator for optical recording |
| JPH056557A (en) * | 1991-06-28 | 1993-01-14 | Toshiba Corp | Optical device |
| US5177640A (en) * | 1991-10-08 | 1993-01-05 | Applied Magnetics Corporation | Two-axis moving coil actuator |
| US5220222A (en) * | 1991-12-23 | 1993-06-15 | Eastman Kodak Company | Magnetic bushings for an optical access actuator |
| JP3116287B2 (en) * | 1992-02-03 | 2000-12-11 | 株式会社リコー | Optical information recording / reproducing device |
| JP3317997B2 (en) * | 1992-06-03 | 2002-08-26 | 株式会社リコー | Objective lens drive |
| US5381288A (en) * | 1992-06-16 | 1995-01-10 | Applied Magnetics Corporation, Inc. | Center moment suspension assembly |
| US5278820A (en) * | 1992-09-28 | 1994-01-11 | Eastman Kodak Company | Apparatus and method for a radial access mechanism for a disk player/recorder |
| KR100200808B1 (en) * | 1992-11-30 | 1999-06-15 | 윤종용 | Optical pickup driving apparatus |
| JP2762930B2 (en) * | 1994-06-14 | 1998-06-11 | 日本電気株式会社 | Thin inner and outer circumference access optical head |
| JPH0821946A (en) * | 1994-07-08 | 1996-01-23 | Minolta Co Ltd | Lens device driving mechanism using electromechanical conversion element |
| US6434087B1 (en) | 1995-01-25 | 2002-08-13 | Discovision Associates | Optical disc system and method for controlling bias coil and light source to process information on a storage medium |
| US5748578A (en) * | 1995-01-25 | 1998-05-05 | Discovision Associates | Colpitts type oscillator having reduced ringing and improved optical disc system utilizing same |
| US6091684A (en) * | 1995-01-25 | 2000-07-18 | Discovision Associates | Optical disc system and method for changing the rotational rate of an information storage medium |
| US5920539A (en) * | 1995-01-25 | 1999-07-06 | Discovision Associates | Apparatus and method for suppression of electromagnetic emissions having a groove on an external surface for passing an electrical conductor |
| US5745470A (en) * | 1995-05-31 | 1998-04-28 | Kabushiki Kaisha Toshiba | Head moving apparatus which cancels leakage flux |
| US6549507B1 (en) * | 1999-06-11 | 2003-04-15 | Acute Applied Technologies, Inc. | Apparatus with ring shape sleeves |
| JP4395694B2 (en) * | 2001-06-14 | 2010-01-13 | ソニー株式会社 | Objective lens driving device and disk drive device having the same |
| DE102005010868A1 (en) * | 2005-03-07 | 2006-09-14 | Deutsche Thomson-Brandt Gmbh | Scanner for optical storage media |
| AU2013409442B2 (en) * | 2013-12-31 | 2017-05-18 | Halliburton Energy Services, Inc. | Geophone with tunable resonance frequency |
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| US2964903A (en) * | 1958-05-09 | 1960-12-20 | Gen Electric | Thermal positioning device |
| NL7402768A (en) * | 1974-02-28 | 1975-09-01 | Philips Nv | DEVICE FOR WRITING AND / OR DISPLAYING INFORMATION IN RESPECTIVE OF A ROTATING DISK REGISTRATION CARRIER. |
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| JPS5718035A (en) * | 1980-07-03 | 1982-01-29 | Matsushita Electric Ind Co Ltd | Optical recording and reproducing device |
| JPS57122030U (en) * | 1981-01-26 | 1982-07-29 | ||
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| JP2563180B2 (en) * | 1987-07-27 | 1996-12-11 | 日本電信電話株式会社 | Method for manufacturing semiconductor device |
-
1983
- 1983-04-11 US US06/483,804 patent/US4504935A/en not_active Expired - Fee Related
- 1983-10-07 EP EP83201437A patent/EP0118626B1/en not_active Expired
- 1983-10-07 DE DE8383201437T patent/DE3373155D1/en not_active Expired
- 1983-10-19 CA CA000439258A patent/CA1213048A/en not_active Expired
- 1983-10-20 ES ES526601A patent/ES526601A0/en active Granted
- 1983-11-17 JP JP58215152A patent/JPS59148153A/en active Granted
-
1984
- 1984-02-07 US US06/578,382 patent/US4607913A/en not_active Expired - Fee Related
-
1988
- 1988-04-25 SG SG278/88A patent/SG27888G/en unknown
-
1989
- 1989-04-27 HK HK349/89A patent/HK34989A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| SG27888G (en) | 1988-09-30 |
| EP0118626A1 (en) | 1984-09-19 |
| EP0118626B1 (en) | 1987-08-19 |
| DE3373155D1 (en) | 1987-09-24 |
| HK34989A (en) | 1989-05-05 |
| JPS59148153A (en) | 1984-08-24 |
| ES8406768A1 (en) | 1984-07-01 |
| JPH0580052B2 (en) | 1993-11-05 |
| US4504935A (en) | 1985-03-12 |
| ES526601A0 (en) | 1984-07-01 |
| US4607913A (en) | 1986-08-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |