CA1160875A - Pivoting mirror device - Google Patents
Pivoting mirror deviceInfo
- Publication number
- CA1160875A CA1160875A CA000389037A CA389037A CA1160875A CA 1160875 A CA1160875 A CA 1160875A CA 000389037 A CA000389037 A CA 000389037A CA 389037 A CA389037 A CA 389037A CA 1160875 A CA1160875 A CA 1160875A
- Authority
- CA
- Canada
- Prior art keywords
- pivoting
- mirror
- bearing support
- bearing
- section
- 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
- G11B7/09—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B7/0925—Electromechanical actuators for lens positioning
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B7/00—Mountings, adjusting means, or light-tight connections, for optical elements
- G02B7/18—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors
- G02B7/182—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors for mirrors
- G02B7/1821—Mountings, adjusting means, or light-tight connections, for optical elements for prisms; for mirrors for mirrors for rotating or oscillating mirrors
Abstract
ABSTRACT:
A pivoting-mirror device for are apparatus for optically reading information tracks on an information carrier comprises a pivoting mirror which is pivotable about one or more pivotal axes with the aid of a mirror bearing arrangement, which arrangement comprises a rigid bearing support and an elastic bearing made of an elasto-meric material, which is connected both to the pivoting mirror and to the bearing support and which partly sur-rounds the bearing support. In order to obtain a suit-able ratio between the rigidity of the pivoting mirror bearing in desired pivoting directions and the rigidity in undesired directions of movement, the portion of the bearing support located in the elastic material has a cross-section in a plane or planer perpendicular to the pivotal axis or axes which varies from a minimum trans-verse dimension at the end of the bearing support near the pivoting mirror to a maximum transverse dimension at a location which is more remote from the pivoting mir-ror.
A pivoting-mirror device for are apparatus for optically reading information tracks on an information carrier comprises a pivoting mirror which is pivotable about one or more pivotal axes with the aid of a mirror bearing arrangement, which arrangement comprises a rigid bearing support and an elastic bearing made of an elasto-meric material, which is connected both to the pivoting mirror and to the bearing support and which partly sur-rounds the bearing support. In order to obtain a suit-able ratio between the rigidity of the pivoting mirror bearing in desired pivoting directions and the rigidity in undesired directions of movement, the portion of the bearing support located in the elastic material has a cross-section in a plane or planer perpendicular to the pivotal axis or axes which varies from a minimum trans-verse dimension at the end of the bearing support near the pivoting mirror to a maximum transverse dimension at a location which is more remote from the pivoting mir-ror.
Description
~6~S
t "Pivoting-mirror device".
~, .
The invention relates to a pivoting-mirror device for an apparatus which scans information tracks on an in~ormation carrier with the aid of a radiation beam, which device comprises: a pivo-ting mirror which is pivotable about at least one pivotal a~is and which has a radiation-reflecting front and, on the reverse side , . .
a back, and a pivotal mirror bearing arrangement com-prising a rigid bearing support having a first end which is situated near the back of the pivoting mirror and a second end which is remote therefrom~ and an elastic bearing of an elastorneric material which is connected both to--the back oP the pivoting mirror and to the bearing support, which material surrounds the first end of -the bearing support and a portion of the bearing support adjacent the first end.
A pivoting-mirror device of this type is Icnown from United States Paten-t Speci-~ication No. 4,021 ,og6.
In this earlier specification it is proposed to make the mirror bearing of the pivoting-snirror device ~rom silicone rubber, liquid silicone rubber being applied through an inle-t duct in the rigid bearing support. The pivo-ting mirror and the bearing suppor~ and brought into a rnu~ual spatial relationship which at leas-t substantially corres-~,~
ponds -to the spatial relationship t~at should e~ist in -the ~inished pivoting mirror device, and à silicone rubber compound is applied through the inlet duct in a viscous mouldable oondition in order to fill the space between the back of the pivoting mirror and the first end o~` the bear-ing support. Subsequently, -the silicone rubber is allowed to cure. In view of the problems which occur duriIlg the manufacture of such pivoting-mirror devices, especially the problems in handling the viscous silicone rubber corn-pound and -the long curing time which is required, Uni-ted , ~e ,; .
~.L~ 75 States Patent Specification No. 4,129,930 proposes to manufacture the elastic bearing ini-tially as a ~inished part and to af~ix it to the pivoting mirror at a later stage A suitable elastomeric material for a bearing manufactured 5 in accordance with this method is, for example, chloroprene rubber. It is possible to interconnec-t the bearing support and -the elastic bearing in a mould by means of a moulding method and during the manufacture of the elastic bearing, After the moulding operation the bearing support and the elastic bearing together constitute an easy-to-handle mounting unit.
One of the problems associated with pivoting-mirror devices with elastic bearings is that in the directions in which the pivoting mirror has -to be pivotable a high elasticity is required, but in all other directions of movement the 'bearing should have a high rigidity. In the first-mentioned United States Patent Specification ~,021, og6 a pivoting-mirror device is described in ~hich the bearing support is tubular and has an opening which fac-es the back of thel~ivoting rrlirror, The silicone rub'bercompound is no-t ~e~ loca-ted 'between the open end of the h bearing support and the baclc of -the pivoting mirror, but also partl~ surrounds the bearing support. The piVOtiIlg mirror is p:ivotable about an~ axis which is perpendicular to the optical axis of the pivoting mirror and ~hich passes through a pivotingcentre near the first end of the bearing support. Owing to the presence o~ the tubular portion o~
the bearing support inside the part of the rubber compound which is connec-ted to the back of the pivo-ting mirror~ the mirror bearing arrangement is sufficientl~ rigid for translational movements perpendicular to -the optical axis of -the pivoting-mirror device. However~ this adversel~ affec-ts -the elastici-ty of the pivoting bearing arrangement in the desired pivoting directions. In view of these conflic-ting requirements it is important to have a bearing arrangeme1lt which has a desired degree of elasticit~ in -the desired pivoting d:irection or pivoting directions Wit]l a rninimal volume of elastomeric elastic material. In another known pivoting-mirror device the pivoting mirror is only pivotable about a single axis perpendicular -to the optical axis o~ the pivoting mirror, and the bearing support has such a shape that an elonga~te elastic bearing is ob-tained when the silicone rubber compound is applied. In this bearing arrangement the silicone rubber is located onl-~ between the pivoting mirror and the bearing support, so that no parts o~ the bearing support penetrate into the elastic bearingO As a result o~ this the elasticity o~` the pivotal bearing arrangernent is high in the desired pivoting directions. However, the resistance to trans-lational movements perpendicular to the pivotal axis ,~, is very small.
It is the object o~ the invention to provide a pivoting-mirror device of the type mentioned in the open-- ing paragraph, comprising a mirror bearing arrangement which has a high elasticit~ in the desired pivoting ; directions and which is moreover robust and has a higher resistance to movements o~ the pivoting mirror in undesired directions. To this end the inven-tion is characterized in that the said por-tion o~ the bearing support which is locat-ed adjacent the ~irst end has a cross-section in a plane perpendicular to said pivotal a~is which varies ~rom a minimum transverse dimension at the ~rst end to a maximum transverse dimension at a location nearer the second end.
Owing to the~esence o~ a part o~ the bearing support inside the elastomeric material the bearing arrangement ` will have the desired rigidi-ty. Since said portion has said var~ing cross-section, the bearing also has a high elasti-city in the desired pivoting direction or pivoting direct-ions. As will be described in more detail hereinafter, it is possible -to give the bearing a maximum elasticit~ ~or a specific volume o~ elastomeric material, allowance being made ~or the permissible load bearing capacity o~ the elastomeric material.
An embodiment of the invention is characterized in that the elastomeric material surrounds -the bearing .,~ .
;~"
3'7~
support over the entire length of said portion of varying cross-section, the bearing support also being surrounded by a layer of elastomeric material at the said location where the cross-section has -the maximum transverse dimens-ion. This layer of elastomeric material only has a limitedin-fluence on the elas-ticity of the bearing and thus vir-tually consti-tutes a protective enclosure for the more inwardly disposed portion of the bearing which is of greater significance for the elastic properties of the bearing arrangement. Owing to the enclosure, environmental in-fluences can onl~ cause slight variations in -the properties of the bearing arrangement in the course of time.
A ~urther embodiment of the invention is cha-rac-terizedin that for affixing the elastomeric material to the bearing support the bearing support has a constricted portion adjoining said portion of varying cross-section.
This embodiment is of special significance -from -the point o-f view of manufacturing technology. The presence of -the con-striction prevents the elastomeric ma-terial from being drawn or slid off the bearing support.
~^~ An optimum combination of propertles of the .~ bearing arrangement with respect -to the elasticity in the des:Lred directions and rigiclity in the other ~irections is obtained with an embodimen-t of the invention ~hich is characteri~ed in tha-t said cross-section has the form of a longitudinal section of a truncated cone.
: The invention will now be described in more ` detail with re~`erence -to -the drawings, in which:
`j Fig. 1 is a perspective view, partly in cross-section and drawn to an enlarged scale, of a pivo-ting-mirror device in accordance wi-th the invention, suitable :~or pivotal movements about two axes which are perpen-dicular to each other, Fig. 2 is a graph of -the stress profile in -the elastic material of the bearing arrangement of the pivotin~-mirror device shown in Fig. I in the case of the maximum deflection, Fig, 3 is a sectional ~iew, drawn to an .~ .
`I
S
-enlarged scale and to illustrate the graph of ~'ig. 2, of a part of thebearing arrangement of the pivoting-mirror device shown in Fig. 1~ and Fig. L~ is an exploded respective view of a 5 pivoting-mirror device in accordance with the inven-tion, suitable for pivotal movements about a single pivotal axis.
The pivoting-mirror device shown in ~ig. 1 is sui-table for use in optical video ~isc players, a light lD beam produced by a laser being employed for scanning information tracks on a video disc. The device comprises a pivoting mirror 1 with a radiation-re~lecting ~ront 2 and, on the reverse side, a back 3. Fig. 1 shows an axis - 4, hereinafter referred to as the "optical axis" of -the 15 pivoting mirror. This axis ~extends perpendicularly to the front 2 of the pivoting mirror and passes through the centre thereof when the pivoting mirror is in its neutral position The pivoting mirror is pivotable about two pivotal axes 5 and 6 in directions which are symbolically 20 represented by two arcuate double-headed arrows 7 and o, and is suitable both for the correctionof errors in the track position of the optical disc and for timing error corrections. The axes 5 and 6 pass through a point C on the optical axis ~, which point may be regarded as -the 25 pivoting cen-tre of the pivoting mirror. In principle, the pivoting mirror is pivotable about any axis through the cen-tre C perpendicular -to the optical a~is ~, but the pivotal movement-s may practically always be regarded as combinations of pivotal movements about the axes 5 and 6.
The pivoting~mirror device comprises a mirror bearing arrangement 9, which comprises a rigid bearing support IO. A first end 11 of the bearing support is disposed near the back 3 of the pivoting mirror, whilst the second end 12 is remote from the back of the pivoting mirror. ~n elastic bearing 13 is connected to the back 3 of the pivoting mirror 1 and to the bearing support IO.
Said bearing consists o~ an elastomeric material, which surrounds -the first e-nd of the bearing support 10 and a 8~7 --6_ portion 1L~ of the bearing suppor-t adjacent -the first end.
Said portion 1~ of the bearing support -lO has a cross-sec-tion in planar perpendicular to -the pivotal axes 5 and 6 which varies from a minimum transverse dimension at -the first end 11 to a maximum -transverse dimension at;a location 15 situa-ted nearer the second end 12. (See in particular Fig. 3), The bearing support 10 is secured in a plastics frame 17 by means o* a screw 'l6, which frame is in -turn mounted on a metal frame carrier 18. The frame carrier has a threaded stud 19 secured thereto, by means of which the pivoting-mirror device can be mounted in a video disc player. For controlling the pivotal movements of the pi-voting mirror I there is provided a plurality of permanent magnets, glued to the back 3, two of sai.d magnets 20A and 21A being visible ~ Fig, 1. The permanent magne-ts are radially magnetized, so that their magnetic field lines extend parallel to the reflecting surface 2 of the pivoting mirror. In grooves in the frame 17 control colls are arranged,, three of said coils~ designated 22A, 22B and 23A being shown in Fig. 1. The coil 22A cooperates with -the permanent magnet 20A for elactrically controlling pivo-tal movement of the pivoting rnirrol- in the directions in dicated by the double-headed arrow 7. The coil 22B on the other side of the pivoting mirror cooperates with a per-manent m~gnet in a similar way. The coil 23A cooperates with the permanent magnet 2lA for electrically controlling pivotal moveme,nt of the pivoting mirror in the directions indicated by the double-headed arrow ~. Qn the other side of'the pivoting mirror there is arranged a similar coil ànd a similar permanent magne-t ~or the same purpose.
The favourable properties of the pivoting-mirror device shown in Fig. I will be discussed more comprehensi~ely with reference to Figs. ? and 3. These Fig6., in sectional view (and to an enlarged scale), show a part of the pivoting-mirror device of Fig. 'I in the region of the portion 14 of the bearing suppor-t. This portion has a cross{~ction i~ planes containing the optical .
axis 4 which varies ~rom a Minimum transverse dimens:ion at the first end 11 to a maximum transverse dimension at a location 15 situated nearer the second end 12. Above the part o~ the pivoting mirror device shown in Eig. 3, Fig. 2 shows two axes 2~ and 25 which are perpendicular to each other. The axis 24 intersects the optical a~is 4 o~ the pivoting-mirror device perpendicularly. The axis 25 inter-; sects -the axis 24 perpendicularly and is parallel to the optical axis 4. The axis 24 will be referred to as the X-axis, whilst the axis 25 will be re~erred to as the ~ -axis. The ~ -axis relates to tensile and compressive stresses occurring in the elastic material o~ the elastic bearing and the X-axis to the location o~ a point in the cross--section X-X (Fig. 3), where the bearing 13 and the back 3 of the pivoting mirror 1 are connected to each other.
As is known, the ~o:Llowing approximated relationship is valid ~or tensi:Le stresses in elastic materials:
~ E- ~ 1 rN/ 21 where: ~ is the stress in Newtons per square metre a-t a speci~ic point in a cross-section o~ the elastic material, 1 is the original length o~ the elongat.ed body i~ me-tres, measured in the direction in which the elongat-ion occurs, ~ 1 is the elongation or, in other words, the ohangle in lengthl in metres, and 3n E is young's modulus in Newtons per square metre.
As ls apparent ~rom tllis relationship, the .:.
stres~ in a cross-section depends linearly on the elongat-ion which occurs. In the absence o~ the bearing support, 35 if the elastic bearing 13 were completely made of an elastomeric material~ the stress in the cross-section X-~in the case o~ tilting in the direction o~ the arrow 26 would vary in acc~rdance with the line 27 in ~ig. ?.
~owever owing to the presence of the por-tion l4 of the bearing support, which portion has the form of a trun-cated cone, -the stress profile from point X2 on the X~axis no longer follows the line 27 but a horizontal line 28 between X2 and X3. Since between these two values of X
the circumferential surface area o~the trunca-ted cone varies linearly from a larger diame-ter to a smaller diam-eter, the length of -the elastomeric material which is ~ub-jected to a tensile stress decreases linearly between X2 and X3. It will be evident that, in view of this linear character of the dependence of the stress in the elastorn-eric material on the elongation which occurs, a constant tensile stress will be obtained over the portion between X2 ana X3 owing -to the presence of the cone-shaped portion 14. In an identical manner a constan-t compressive stress will occur between points XL~ and X5, so that between these two last-rnentioned points the stress profile ~ill exhibit a horizontal portion 29. Since the first end of the portion 14 of the bearing support is truncated, the stress between the points X3 and X4 will vary steeply in accordance with the line 3O~ which interconnec-ts the lines 28 and 29. Fig.
t "Pivoting-mirror device".
~, .
The invention relates to a pivoting-mirror device for an apparatus which scans information tracks on an in~ormation carrier with the aid of a radiation beam, which device comprises: a pivo-ting mirror which is pivotable about at least one pivotal a~is and which has a radiation-reflecting front and, on the reverse side , . .
a back, and a pivotal mirror bearing arrangement com-prising a rigid bearing support having a first end which is situated near the back of the pivoting mirror and a second end which is remote therefrom~ and an elastic bearing of an elastorneric material which is connected both to--the back oP the pivoting mirror and to the bearing support, which material surrounds the first end of -the bearing support and a portion of the bearing support adjacent the first end.
A pivoting-mirror device of this type is Icnown from United States Paten-t Speci-~ication No. 4,021 ,og6.
In this earlier specification it is proposed to make the mirror bearing of the pivoting-snirror device ~rom silicone rubber, liquid silicone rubber being applied through an inle-t duct in the rigid bearing support. The pivo-ting mirror and the bearing suppor~ and brought into a rnu~ual spatial relationship which at leas-t substantially corres-~,~
ponds -to the spatial relationship t~at should e~ist in -the ~inished pivoting mirror device, and à silicone rubber compound is applied through the inlet duct in a viscous mouldable oondition in order to fill the space between the back of the pivoting mirror and the first end o~` the bear-ing support. Subsequently, -the silicone rubber is allowed to cure. In view of the problems which occur duriIlg the manufacture of such pivoting-mirror devices, especially the problems in handling the viscous silicone rubber corn-pound and -the long curing time which is required, Uni-ted , ~e ,; .
~.L~ 75 States Patent Specification No. 4,129,930 proposes to manufacture the elastic bearing ini-tially as a ~inished part and to af~ix it to the pivoting mirror at a later stage A suitable elastomeric material for a bearing manufactured 5 in accordance with this method is, for example, chloroprene rubber. It is possible to interconnec-t the bearing support and -the elastic bearing in a mould by means of a moulding method and during the manufacture of the elastic bearing, After the moulding operation the bearing support and the elastic bearing together constitute an easy-to-handle mounting unit.
One of the problems associated with pivoting-mirror devices with elastic bearings is that in the directions in which the pivoting mirror has -to be pivotable a high elasticity is required, but in all other directions of movement the 'bearing should have a high rigidity. In the first-mentioned United States Patent Specification ~,021, og6 a pivoting-mirror device is described in ~hich the bearing support is tubular and has an opening which fac-es the back of thel~ivoting rrlirror, The silicone rub'bercompound is no-t ~e~ loca-ted 'between the open end of the h bearing support and the baclc of -the pivoting mirror, but also partl~ surrounds the bearing support. The piVOtiIlg mirror is p:ivotable about an~ axis which is perpendicular to the optical axis of the pivoting mirror and ~hich passes through a pivotingcentre near the first end of the bearing support. Owing to the presence o~ the tubular portion o~
the bearing support inside the part of the rubber compound which is connec-ted to the back of the pivo-ting mirror~ the mirror bearing arrangement is sufficientl~ rigid for translational movements perpendicular to -the optical axis of -the pivoting-mirror device. However~ this adversel~ affec-ts -the elastici-ty of the pivoting bearing arrangement in the desired pivoting directions. In view of these conflic-ting requirements it is important to have a bearing arrangeme1lt which has a desired degree of elasticit~ in -the desired pivoting d:irection or pivoting directions Wit]l a rninimal volume of elastomeric elastic material. In another known pivoting-mirror device the pivoting mirror is only pivotable about a single axis perpendicular -to the optical axis o~ the pivoting mirror, and the bearing support has such a shape that an elonga~te elastic bearing is ob-tained when the silicone rubber compound is applied. In this bearing arrangement the silicone rubber is located onl-~ between the pivoting mirror and the bearing support, so that no parts o~ the bearing support penetrate into the elastic bearingO As a result o~ this the elasticity o~` the pivotal bearing arrangernent is high in the desired pivoting directions. However, the resistance to trans-lational movements perpendicular to the pivotal axis ,~, is very small.
It is the object o~ the invention to provide a pivoting-mirror device of the type mentioned in the open-- ing paragraph, comprising a mirror bearing arrangement which has a high elasticit~ in the desired pivoting ; directions and which is moreover robust and has a higher resistance to movements o~ the pivoting mirror in undesired directions. To this end the inven-tion is characterized in that the said por-tion o~ the bearing support which is locat-ed adjacent the ~irst end has a cross-section in a plane perpendicular to said pivotal a~is which varies ~rom a minimum transverse dimension at the ~rst end to a maximum transverse dimension at a location nearer the second end.
Owing to the~esence o~ a part o~ the bearing support inside the elastomeric material the bearing arrangement ` will have the desired rigidi-ty. Since said portion has said var~ing cross-section, the bearing also has a high elasti-city in the desired pivoting direction or pivoting direct-ions. As will be described in more detail hereinafter, it is possible -to give the bearing a maximum elasticit~ ~or a specific volume o~ elastomeric material, allowance being made ~or the permissible load bearing capacity o~ the elastomeric material.
An embodiment of the invention is characterized in that the elastomeric material surrounds -the bearing .,~ .
;~"
3'7~
support over the entire length of said portion of varying cross-section, the bearing support also being surrounded by a layer of elastomeric material at the said location where the cross-section has -the maximum transverse dimens-ion. This layer of elastomeric material only has a limitedin-fluence on the elas-ticity of the bearing and thus vir-tually consti-tutes a protective enclosure for the more inwardly disposed portion of the bearing which is of greater significance for the elastic properties of the bearing arrangement. Owing to the enclosure, environmental in-fluences can onl~ cause slight variations in -the properties of the bearing arrangement in the course of time.
A ~urther embodiment of the invention is cha-rac-terizedin that for affixing the elastomeric material to the bearing support the bearing support has a constricted portion adjoining said portion of varying cross-section.
This embodiment is of special significance -from -the point o-f view of manufacturing technology. The presence of -the con-striction prevents the elastomeric ma-terial from being drawn or slid off the bearing support.
~^~ An optimum combination of propertles of the .~ bearing arrangement with respect -to the elasticity in the des:Lred directions and rigiclity in the other ~irections is obtained with an embodimen-t of the invention ~hich is characteri~ed in tha-t said cross-section has the form of a longitudinal section of a truncated cone.
: The invention will now be described in more ` detail with re~`erence -to -the drawings, in which:
`j Fig. 1 is a perspective view, partly in cross-section and drawn to an enlarged scale, of a pivo-ting-mirror device in accordance wi-th the invention, suitable :~or pivotal movements about two axes which are perpen-dicular to each other, Fig. 2 is a graph of -the stress profile in -the elastic material of the bearing arrangement of the pivotin~-mirror device shown in Fig. I in the case of the maximum deflection, Fig, 3 is a sectional ~iew, drawn to an .~ .
`I
S
-enlarged scale and to illustrate the graph of ~'ig. 2, of a part of thebearing arrangement of the pivoting-mirror device shown in Fig. 1~ and Fig. L~ is an exploded respective view of a 5 pivoting-mirror device in accordance with the inven-tion, suitable for pivotal movements about a single pivotal axis.
The pivoting-mirror device shown in ~ig. 1 is sui-table for use in optical video ~isc players, a light lD beam produced by a laser being employed for scanning information tracks on a video disc. The device comprises a pivoting mirror 1 with a radiation-re~lecting ~ront 2 and, on the reverse side, a back 3. Fig. 1 shows an axis - 4, hereinafter referred to as the "optical axis" of -the 15 pivoting mirror. This axis ~extends perpendicularly to the front 2 of the pivoting mirror and passes through the centre thereof when the pivoting mirror is in its neutral position The pivoting mirror is pivotable about two pivotal axes 5 and 6 in directions which are symbolically 20 represented by two arcuate double-headed arrows 7 and o, and is suitable both for the correctionof errors in the track position of the optical disc and for timing error corrections. The axes 5 and 6 pass through a point C on the optical axis ~, which point may be regarded as -the 25 pivoting cen-tre of the pivoting mirror. In principle, the pivoting mirror is pivotable about any axis through the cen-tre C perpendicular -to the optical a~is ~, but the pivotal movement-s may practically always be regarded as combinations of pivotal movements about the axes 5 and 6.
The pivoting~mirror device comprises a mirror bearing arrangement 9, which comprises a rigid bearing support IO. A first end 11 of the bearing support is disposed near the back 3 of the pivoting mirror, whilst the second end 12 is remote from the back of the pivoting mirror. ~n elastic bearing 13 is connected to the back 3 of the pivoting mirror 1 and to the bearing support IO.
Said bearing consists o~ an elastomeric material, which surrounds -the first e-nd of the bearing support 10 and a 8~7 --6_ portion 1L~ of the bearing suppor-t adjacent -the first end.
Said portion 1~ of the bearing support -lO has a cross-sec-tion in planar perpendicular to -the pivotal axes 5 and 6 which varies from a minimum transverse dimension at -the first end 11 to a maximum -transverse dimension at;a location 15 situa-ted nearer the second end 12. (See in particular Fig. 3), The bearing support 10 is secured in a plastics frame 17 by means o* a screw 'l6, which frame is in -turn mounted on a metal frame carrier 18. The frame carrier has a threaded stud 19 secured thereto, by means of which the pivoting-mirror device can be mounted in a video disc player. For controlling the pivotal movements of the pi-voting mirror I there is provided a plurality of permanent magnets, glued to the back 3, two of sai.d magnets 20A and 21A being visible ~ Fig, 1. The permanent magne-ts are radially magnetized, so that their magnetic field lines extend parallel to the reflecting surface 2 of the pivoting mirror. In grooves in the frame 17 control colls are arranged,, three of said coils~ designated 22A, 22B and 23A being shown in Fig. 1. The coil 22A cooperates with -the permanent magnet 20A for elactrically controlling pivo-tal movement of the pivoting rnirrol- in the directions in dicated by the double-headed arrow 7. The coil 22B on the other side of the pivoting mirror cooperates with a per-manent m~gnet in a similar way. The coil 23A cooperates with the permanent magnet 2lA for electrically controlling pivotal moveme,nt of the pivoting mirror in the directions indicated by the double-headed arrow ~. Qn the other side of'the pivoting mirror there is arranged a similar coil ànd a similar permanent magne-t ~or the same purpose.
The favourable properties of the pivoting-mirror device shown in Fig. I will be discussed more comprehensi~ely with reference to Figs. ? and 3. These Fig6., in sectional view (and to an enlarged scale), show a part of the pivoting-mirror device of Fig. 'I in the region of the portion 14 of the bearing suppor-t. This portion has a cross{~ction i~ planes containing the optical .
axis 4 which varies ~rom a Minimum transverse dimens:ion at the first end 11 to a maximum transverse dimension at a location 15 situated nearer the second end 12. Above the part o~ the pivoting mirror device shown in Eig. 3, Fig. 2 shows two axes 2~ and 25 which are perpendicular to each other. The axis 24 intersects the optical a~is 4 o~ the pivoting-mirror device perpendicularly. The axis 25 inter-; sects -the axis 24 perpendicularly and is parallel to the optical axis 4. The axis 24 will be referred to as the X-axis, whilst the axis 25 will be re~erred to as the ~ -axis. The ~ -axis relates to tensile and compressive stresses occurring in the elastic material o~ the elastic bearing and the X-axis to the location o~ a point in the cross--section X-X (Fig. 3), where the bearing 13 and the back 3 of the pivoting mirror 1 are connected to each other.
As is known, the ~o:Llowing approximated relationship is valid ~or tensi:Le stresses in elastic materials:
~ E- ~ 1 rN/ 21 where: ~ is the stress in Newtons per square metre a-t a speci~ic point in a cross-section o~ the elastic material, 1 is the original length o~ the elongat.ed body i~ me-tres, measured in the direction in which the elongat-ion occurs, ~ 1 is the elongation or, in other words, the ohangle in lengthl in metres, and 3n E is young's modulus in Newtons per square metre.
As ls apparent ~rom tllis relationship, the .:.
stres~ in a cross-section depends linearly on the elongat-ion which occurs. In the absence o~ the bearing support, 35 if the elastic bearing 13 were completely made of an elastomeric material~ the stress in the cross-section X-~in the case o~ tilting in the direction o~ the arrow 26 would vary in acc~rdance with the line 27 in ~ig. ?.
~owever owing to the presence of the por-tion l4 of the bearing support, which portion has the form of a trun-cated cone, -the stress profile from point X2 on the X~axis no longer follows the line 27 but a horizontal line 28 between X2 and X3. Since between these two values of X
the circumferential surface area o~the trunca-ted cone varies linearly from a larger diame-ter to a smaller diam-eter, the length of -the elastomeric material which is ~ub-jected to a tensile stress decreases linearly between X2 and X3. It will be evident that, in view of this linear character of the dependence of the stress in the elastorn-eric material on the elongation which occurs, a constant tensile stress will be obtained over the portion between X2 ana X3 owing -to the presence of the cone-shaped portion 14. In an identical manner a constan-t compressive stress will occur between points XL~ and X5, so that between these two last-rnentioned points the stress profile ~ill exhibit a horizontal portion 29. Since the first end of the portion 14 of the bearing support is truncated, the stress between the points X3 and X4 will vary steeply in accordance with the line 3O~ which interconnec-ts the lines 28 and 29. Fig.
2 shows a broken line ~1, which indicates the maximum per-i miss:Lble tensile stress in the elastonleric material. The location of -the lines 28 and 29 ahove and below the X-axis respectively is determined by the magnitude o~ the stress t in the elas-tomeric material ~hich is considered to be permissible. ~s can be seen in Fig. 2, the portions of ~1 the stress profile above and below the X-axis have sub-stantially rec-tangular shapes. The enclosed cross-hatched areas therefore have a substantially maximum surface area.
This means that a minimum amount of elastic material is : employed due to the presence of the frusto conical portion 14, starting ~rom a speci~ic desired resistance to pivoting and a speci~ic t~pe o~ elastomeric material. This means that 35 by approximation an optimum rig~idity of the bearing exis-ts in directions o-ther than the desired directions.
The embodiment o~` Fig. 4 concerns a pivoting-mirror device in accordance with -the invention which is suitable for pivoting in the directions indicated b~ the double-headed arrow 31 about only one pivotal axis 32. The device ~omprises a pivoting mirror 33 with a radiation-reflecting ~ront 34 and a back 35. rrhe mirror bearing 36 comprises a rigid bearing support 37 having a ~irst end 38 situated near the back 35 o~ the pivoting mirror 33 and an end 39 which is remote there~rom. ~urtherrnore, there is provided an elastic bearing 4O o:~ an elastomeric material, which bearing is connected to -the back 35 of the pivoting mirror and to the bearing suppor-t 37 and ~hich material surrounds a ~irst end 38 o~ the bearing support and also a portion 41 o~ the bearing support adjacent the first end. This portion of the bearing suppcrt has a cross-section in a plane perpendicular to the pivotal a~is 32 which has the ~orm of a longitudinal section of a trun-ca-ted cone, speci~icall~, a cross-section identical to the cross-section of the portion 14 of the pivotal bearing arrangement in Figs. 1 and 3. There~ore, Figs. 2 and 3 are also illustrative of the properties o~ the pivotal bearing arrangement ~6.
The pivoting-mirror device shown in Fig. 4 comprises a frame carrier 42 to which the bearing support 37 is secured by a plate 43. The bearing support has tw~
limbs 44 and 45, which are passed through openings 46 and 47, which are bounded ~ a pDr*ibni.48 of the frame carrier 42. The plate 43 has slots 49 and 5O to receive the limbs 44 and 45. After the limbs 44 and 45 have been passed through the openings 46, 47 and -the slots 49, 5O, the ends of -the limbs are slightly twisted so that the limbs cannot be withdrawn.
At its underside the pivoting mirror 34 carries two rod-shaped permanent magnets 51 and 52. A control coil 53 of substantially rectangular shape is moun-ted on the frame carrier 42 between the upright members 54 to 57. This guarantees a co-axial alignment o~ the coil 53 relative to the pivo-ting mirror 34.
This means that a minimum amount of elastic material is : employed due to the presence of the frusto conical portion 14, starting ~rom a speci~ic desired resistance to pivoting and a speci~ic t~pe o~ elastomeric material. This means that 35 by approximation an optimum rig~idity of the bearing exis-ts in directions o-ther than the desired directions.
The embodiment o~` Fig. 4 concerns a pivoting-mirror device in accordance with -the invention which is suitable for pivoting in the directions indicated b~ the double-headed arrow 31 about only one pivotal axis 32. The device ~omprises a pivoting mirror 33 with a radiation-reflecting ~ront 34 and a back 35. rrhe mirror bearing 36 comprises a rigid bearing support 37 having a ~irst end 38 situated near the back 35 o~ the pivoting mirror 33 and an end 39 which is remote there~rom. ~urtherrnore, there is provided an elastic bearing 4O o:~ an elastomeric material, which bearing is connected to -the back 35 of the pivoting mirror and to the bearing suppor-t 37 and ~hich material surrounds a ~irst end 38 o~ the bearing support and also a portion 41 o~ the bearing support adjacent the first end. This portion of the bearing suppcrt has a cross-section in a plane perpendicular to the pivotal a~is 32 which has the ~orm of a longitudinal section of a trun-ca-ted cone, speci~icall~, a cross-section identical to the cross-section of the portion 14 of the pivotal bearing arrangement in Figs. 1 and 3. There~ore, Figs. 2 and 3 are also illustrative of the properties o~ the pivotal bearing arrangement ~6.
The pivoting-mirror device shown in Fig. 4 comprises a frame carrier 42 to which the bearing support 37 is secured by a plate 43. The bearing support has tw~
limbs 44 and 45, which are passed through openings 46 and 47, which are bounded ~ a pDr*ibni.48 of the frame carrier 42. The plate 43 has slots 49 and 5O to receive the limbs 44 and 45. After the limbs 44 and 45 have been passed through the openings 46, 47 and -the slots 49, 5O, the ends of -the limbs are slightly twisted so that the limbs cannot be withdrawn.
At its underside the pivoting mirror 34 carries two rod-shaped permanent magnets 51 and 52. A control coil 53 of substantially rectangular shape is moun-ted on the frame carrier 42 between the upright members 54 to 57. This guarantees a co-axial alignment o~ the coil 53 relative to the pivo-ting mirror 34.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A pivoting-mirror device for an apparatus which scans information tracks on an information carrier with the aid of a radiation beam, which device comprises:
- a pivoting mirror which is pivotable about at least one pivotal axis and which has a radiation-reflecting front and, on the reverse side, a back, and a pivotal mirror bearing arrangement comprising:
- a rigid bearing support having a first end situated near the back of the pivoting mirror and a second end which is remote therefrom, and - an elastic bearing of an elastomeric mater-ial which is connected both to the back of the pivoting mirror and to the bearing sup-port, which material surrounds the first end of the bearing support and a portion of the bearing support adjacent, the first end, characterized in that said portion of the bearing support which is situated adjacent the first end has a cross-section in a plane perpendicular to said pivotal axis which varies from a minimum transverse dimension at the first end to a maximum transverse dimension at a location situated nearer the second end.
- a pivoting mirror which is pivotable about at least one pivotal axis and which has a radiation-reflecting front and, on the reverse side, a back, and a pivotal mirror bearing arrangement comprising:
- a rigid bearing support having a first end situated near the back of the pivoting mirror and a second end which is remote therefrom, and - an elastic bearing of an elastomeric mater-ial which is connected both to the back of the pivoting mirror and to the bearing sup-port, which material surrounds the first end of the bearing support and a portion of the bearing support adjacent, the first end, characterized in that said portion of the bearing support which is situated adjacent the first end has a cross-section in a plane perpendicular to said pivotal axis which varies from a minimum transverse dimension at the first end to a maximum transverse dimension at a location situated nearer the second end.
2. A pivoting-mirror device as claimed in Claim 1, characterized in that the elastomeric material sur-rounds the bearing support over the entire length of said portion of varying cross-section, the bearing support also being surrounded by a layer of elastomeric material at the said location where the cross-section has the max-imum transverse dimension.
3. A pivoting-mirror device as claimed in Claim 2, characterized in that for affixing the elastomeric material to the bearing support, the bearing support has a constricted portion adjoining said portion of varying cross-section.
4. A pivoting-mirror device as claimed in Claim 1, 2 or 3, characterized in that said cross-section has the form of a longitudinal section of a truncated cone.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL8005948A NL8005948A (en) | 1980-10-30 | 1980-10-30 | SWING MIRROR. |
| NL8005948 | 1980-10-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1160875A true CA1160875A (en) | 1984-01-24 |
Family
ID=19836080
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000389037A Expired CA1160875A (en) | 1980-10-30 | 1981-10-29 | Pivoting mirror device |
Country Status (9)
| Country | Link |
|---|---|
| US (1) | US4376572A (en) |
| EP (1) | EP0051331B1 (en) |
| JP (1) | JPH0214014Y2 (en) |
| AT (1) | ATE8823T1 (en) |
| AU (1) | AU541896B2 (en) |
| CA (1) | CA1160875A (en) |
| DE (1) | DE3165257D1 (en) |
| ES (1) | ES269689Y (en) |
| NL (1) | NL8005948A (en) |
Families Citing this family (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5939434U (en) * | 1982-09-08 | 1984-03-13 | パイオニア株式会社 | Optical component support structure |
| US4616226A (en) * | 1982-11-12 | 1986-10-07 | The Garrett Corporation | Peripheral vision artificial horizon device and associated methods |
| US4743903A (en) * | 1982-11-12 | 1988-05-10 | The Garrett Corporation | Peripheral vision artificial horizon device and associated methods |
| FR2622710A1 (en) * | 1987-10-30 | 1989-05-05 | Sciaky Sa | Device for control of the pivoting of a tool, especially of a mirror for reflecting a laser beam |
| US5276545A (en) * | 1989-03-24 | 1994-01-04 | Nicolet Instrument Corporation | Mirror alignment and damping device |
| US5040860A (en) * | 1990-08-29 | 1991-08-20 | Litton Systems, Inc. | Momentum-balance mechanism for use with a scan mirror or other component |
| US5187612A (en) * | 1990-11-15 | 1993-02-16 | Gap Technologies, Inc. | Gyrating programmable scanner |
| JPH0528523A (en) * | 1991-07-16 | 1993-02-05 | Sharp Corp | Mirror driving device |
| US5239361A (en) * | 1991-10-25 | 1993-08-24 | Nicolet Instrument Corporation | Dynamic mirror alignment device for the interferometer of an infrared spectrometer |
| IT1286550B1 (en) * | 1996-02-13 | 1998-07-15 | El En S R L | DEVICE AND METHOD OF DEFLECTION OF A LASER BEAM BY MEANS OF A SINGLE MIRROR |
| US5883712A (en) * | 1997-05-21 | 1999-03-16 | Nicolet Instrument Corporation | Interferometer of an infrared spectrometer with dynamic moving mirror alignment |
| US7643196B2 (en) * | 2005-12-16 | 2010-01-05 | The Charles Stark Draper Laboratory, Inc. | Systems, methods and devices for actuating a moveable miniature platform |
| US7797252B2 (en) * | 2006-10-20 | 2010-09-14 | Target Brands, Inc. | Service plan product and associated system |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB337084A (en) * | 1929-07-11 | 1930-10-30 | Selenophon Licht & Tonbildges | Damping device for oscillographs, particularly for photographically recording sound |
| DE660974C (en) * | 1933-02-15 | 1938-06-07 | Telefunken Gmbh | Damping device for oscilloscopes |
| CH354117A (en) * | 1957-09-25 | 1961-05-15 | Philips Ag | Device for swiveling at least one reflective surface according to at least one electrical variable |
| NL174608C (en) * | 1975-10-20 | 1984-07-02 | Philips Nv | METHOD FOR THE MANUFACTURE OF A TILT MIRROR DEVICE AND A TILT MIRROR DEVICE MADE ACCORDING TO THIS METHOD |
| ES465879A1 (en) * | 1977-01-13 | 1979-01-01 | Philips Nv | Method of manufacturing an electrically controllable pivoting mirror device |
-
1980
- 1980-10-30 NL NL8005948A patent/NL8005948A/en not_active Application Discontinuation
-
1981
- 1981-01-29 US US06/229,419 patent/US4376572A/en not_active Expired - Fee Related
- 1981-10-22 AT AT81201166T patent/ATE8823T1/en not_active IP Right Cessation
- 1981-10-22 DE DE8181201166T patent/DE3165257D1/en not_active Expired
- 1981-10-22 EP EP81201166A patent/EP0051331B1/en not_active Expired
- 1981-10-27 JP JP1981159149U patent/JPH0214014Y2/ja not_active Expired
- 1981-10-28 ES ES1981269689U patent/ES269689Y/en not_active Expired
- 1981-10-28 AU AU76892/81A patent/AU541896B2/en not_active Ceased
- 1981-10-29 CA CA000389037A patent/CA1160875A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| ES269689U (en) | 1983-07-01 |
| ATE8823T1 (en) | 1984-08-15 |
| AU541896B2 (en) | 1985-01-24 |
| AU7689281A (en) | 1982-05-06 |
| JPH0214014Y2 (en) | 1990-04-17 |
| US4376572A (en) | 1983-03-15 |
| ES269689Y (en) | 1984-01-16 |
| EP0051331A1 (en) | 1982-05-12 |
| EP0051331B1 (en) | 1984-08-01 |
| NL8005948A (en) | 1982-05-17 |
| DE3165257D1 (en) | 1984-09-06 |
| JPS5791142U (en) | 1982-06-04 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |