Patent ID: 12222577

FIG.1represents elements of an optical device2constructed in accordance with the teachings of the invention.

Such an optical device2includes at least a lens12;52;92, at least a motor14;54;94and at least a transmission system16;56;96configured to move at least a portion of the lens12;52;92and thereby change the optical power provided along an optical axis X of the lens12;52;92when the motor14;54;94is operated.

In the present example, the optical device2includes:a first motor14, a lens12having a variable spherical power (along the optical axis X of the lens12) and a first transmission system16configured to rotate a ring of the lens12and change the spherical power (along the optical axis X of the lens12) when the first motor14is operated;a second motor54, a first cylindrical lens52(i.e. a lens having a cylindrical power along the optical axis X of the lens52) and a second transmission system56configured to rotate the first cylindrical lens52to change the optical power (here the axis of the cylindrical correction) when the second motor54is operated;a third motor94, a second cylindrical lens92(i.e. a lens having a cylindrical power along the optical axis X of the lens52) and a third transmission system96configured to rotate the second cylindrical lens92to change the optical power (here the axis of the cylindrical correction) when the second motor54is operated.

These elements are mounted in a framework8of the optical device2such that the lens12having a variable spherical power, the first cylindrical lens52and the second cylindrical lens92have the same optical axis X (as schematically represented inFIG.1). Reference can be made to document WO2015/107303 for further details on this aspect.

As shown inFIG.1, the optical device2also includes a control circuit6designed to control motion of the motor(s), here of the first motor14, of the second motor54, and of the third motor94, such that the lens or combination of lenses12,52,92provides a sought optical power, as explained in document WO2015/107303.

The optical device2can thus be used to provide a predefined optical correction to an eye of a person (when this eye is situated along the optical axis X). The optical device2can thus be included in an optical equipment, such as a refractor (or phoropter), to be used for instance when subjecting a patient to a subjective refraction test.

In the present embodiment, each motor14;54;94includes an encoder for determining an angular position of the output shaft18;58of the concerned motor14;54;94and for transmitting an item of information representing this angular position to the control circuit6(based on which the control circuit6can precisely control the position of the concerned output shaft18;58).

The first transmission system16and the second transmission system56will now be described with reference toFIGS.2to5. The third transmission system96is constructed in a manner identical to the second transmission system56and will not therefore be further described.

Each transmission system16;56comprises a driving member20;60rotatively coupled to the output shaft18;58of the corresponding motor14;54and a control member22;62designed so as to produce, when moving, a change in the optical power provided along an optical axis X of the concerned lens12;52.

The driving member20;60is mounted with respect to the output shaft18;58of the corresponding motor14;54so as to be connected or affixed to the output shaft18;58such that the driving member20;60and the output shaft18;58are coupled when rotating (i.e. when the corresponding motor14;54operates) around the output shaft axis. The driving member20;60may however in practice be mounted with respect to the output shaft18;58so as to move in translation with respect to the output shaft18;58along the axis of the output shaft18;58.

In the present embodiment, the driving member20;60is a worm screw. This worm screw20;60is here affixed to the output shaft18;58with the axis of the worm screw20;60extending along the axis of the output shaft18;58, such that rotation of the output shaft18;58(when operating the motor14;54) results in rotation of the worm screw20;60(around the axis of the worm screw20;60).

In the present embodiment, the control member22;62is a toothed wheel. This toothed wheel22;62meshes with the worm screw20;60such that rotation of the worm screw20;60(around the axis of the worm screw20;60) produces a rotation of the toothed wheel22;62around the axis of the toothed wheel22;62(the axis of the toothed wheel22;62being perpendicular to the axis of the worm screw20;60, i.e. perpendicular to the axis of the output shaft18;58of the motor14;54, and/or being situated at a distance from the axis of the worm screw20;60).

FIGS.2and3show details of the first transmission system16.

As visible inFIG.2, in the present embodiment, the framework8comprises a frame9and a sleeve24. The frame9is for instance made of a plastic material, such as polyether ether ketone (PEEK). The sleeve24is for instance made of metal, e.g. stainless steel.

The sleeve24is for instance received in a complementary recess26formed in the frame9and retained in this complementary recess26thanks to a ring28affixed to the frame9by means of screws30.

The sleeve24defines a through aperture32through which the output shaft18of the motor14and the driving member20extend. The through aperture32comprises a first cylindrical portion34for partly accommodating the motor14and a second cylindrical portion36for accommodating a rolling bearing at least (here two rolling bearings38,40).

The sleeve24forms a ring-shaped wall42at an axial end of the second cylindrical portion36for a bearing38to abut, as further explained below.

The frame9defines a cavity44communicating with the recess26. In the present embodiment, the cavity44comprises (sequentially along an axis of the cavity44, from a portion situated near the recess26to a portion situated away from the recess26):a first cylindrical portion45having a first diameter;a second cylindrical portion46having a second diameter smaller than the first diameter; and, here,a third cylindrical portion47having a third diameter smaller than the second diameter.

The first cylindrical portion45accommodates in the present example a spring washer43. The frame9has a ring shaped wall49(connecting the first cylindrical portion45and the second cylindrical portion46, i.e. formed by the difference in diameter between the first cylindrical portion45and the second cylindrical portion46).

The spring washer43is thus held (axially) between the wall49and the outer race of the rolling bearing40and presses the rolling bearing assembly38,40against the wall42formed in framework8(here in the sleeve24).

A further rolling bearing48is accommodated in the cavity at the level of the third cylindrical portion47. The rolling bearing48is able to translate axially under the force of the spring washer43and is mounted tight on the driving member20.

The driving member20comprises a first axial portion23, a second axial portion25and a threaded portion21separating (i.e. extending between, here along the axis of the driving member20) the first axial portion23and the second axial portion25.

The second cylindrical portion46has a diameter (second diameter as mentioned above) larger than the external diameter of the threaded portion21of the driving member20(for the cavity44to accommodate the driving member20).

The rolling bearings38,40are mounted on the first axial portion23of the driving member20. Precisely here, the first axial portion23of the driving member20is press fit into respective inner races of the rolling bearings38,40.

The further rolling bearing48is mounted on the second axial portion25of the driving member20. Precisely here, the second axial portion25of the driving member20is press fit into the inner race of the further rolling bearing48.

The driving member20is thus rotatably mounted in the framework8(rotating around an axis of the driving member20, corresponding here to the output shaft axis).

Thanks to the construction just described, as the rolling bearing assembly38,40is urged against the wall42of the framework8thanks to the spring washer43and the driving member20is press fit into inner races of the rolling bearings38,40, the driving member20is maintained in a predetermined axial position along the axis of the output shaft18(identical here to the axis of the driving member20) relative to the framework8.

The spring washer43may for instance be selected so as to exert, along the axis of the output shaft18, a biasing force greater than a force exerted by the driving member20on the control member22for driving the control member22into motion (for example, three times greater than said force exerted by the driving member20or more, here four times greater than said force exerted by the driving member20or more).

The stiffness of the spring is dimensioned/chosen so that the thermal expansions do not significantly influence the biasing force exerted by the spring washer43along the axis of the output shaft18.

For example, the force exerted by the driving member20on the control member22for driving the control member22into motion is between 0.05 N and 0.2 N, here 0.1 N; the biasing force exerted by the spring washer43along the axis of the output shaft18is between 0.2 N and 1 N, here 0.4 N.

Motion of the control member22(here by rotation) can thus be precisely controlled by corresponding motion of the driving member20(itself driven by the motor14). Control of the optical power (here of the spherical power) provided by the lens12along the lens axis X is thus improved.

In the present case, rotation of the control member22is converted into a translation movement by a screw arrangement (not shown), this translation movement producing the deformation of a deformable membrane (not shown) of the lens12, thus varying the spherical power of the lens12.

FIGS.4and5show details of the second transmission system56.

As shown inFIG.4, the framework8also includes here a bushing64(in addition to the frame already mentioned). The bushing64is for instance made of metal, e.g. stainless steel.

The frame9defines a cavity84comprising (sequentially along an axis of the cavity84, from a portion situated near the motor54to a portion situated away from the motor54):a first cylindrical portion85having a fourth diameter;a second cylindrical portion86having a fifth diameter smaller than the third diameter; and, here,a third cylindrical portion87having a sixth diameter smaller than the second diameter.

The bushing64is here received in the cavity84at the level of the first cylindrical portion85. A portion of the bushing64has a cylindrical shape having a diameter corresponding to the fourth diameter mentioned above. The bushing64is for instance affixed to the frame9by means of a clip68cooperating with a groove70formed on the bushing64.

The bushing64defines a through aperture72through which the output shaft58of the motor54and an end of the driving member60extend.

The bushing64defines a first recess74partly receiving the motor54and a second recess76(situated axially opposite the first recess74) accommodating a rolling bearing78.

The second recess76defines a ring-shaped wall82against which the rolling bearing78abuts, as further explained below.

The driving member60comprises a first axial portion63, a second axial portion65and a threaded portion61separating (i.e. extending between, here along the axis of the driving member60) the first axial portion63and the second axial portion65.

The second cylindrical portion86has a diameter (fifth diameter as mentioned above) larger than the external diameter of the threaded portion61of the driving member60(for the cavity84to accommodate the driving member60).

The rolling bearing78is mounted on the first axial portion63of the driving member60. Precisely here, an end portion of the first axial portion63of the driving member60is press fit into respective inner races of the rolling bearing78.

Another rolling bearing80is mounted on the second axial portion65of the driving member60. Precisely here, the second axial portion65of the driving member60is press fit into the inner race of the other rolling bearing80.

As visible inFIGS.4&5, this rolling bearing80is accommodated in the cavity84, here in the third cylindrical portion87of the cavity84. The external diameter of the rolling bearing80corresponds here (in practice is equal to) the diameter of the third cylindrical portion (sixth diameter) so that the rolling bearing80may move (by translation along the axis of the driving member60, i.e. here the axis of the output shaft58) within the third cylindrical portion87.

The driving member60is thus rotatably mounted in the framework8(rotating around an axis of the driving member60, corresponding here to the output shaft axis).

A coil spring83is interposed between an end wall81of the cavity84(i.e. here an end wall of the third cylindrical portion) and the rolling bearing80(precisely here the outer race of the rolling bearing80).

In the present embodiment, a ring89is further interposed between the coil spring83and the rolling bearing80. The circular edge of the ring89(circular edge directed towards the rolling bearing80) contacts only the outer race of the rolling bearing80, which ensures that the force produced by the compressed coil spring83applies only on the outer race of the rolling bearing80and not on the inner race of the rolling bearing80(which would hinder rotation of the control member60).

As the coil spring83is compressed between the end wall81and the rolling bearing80, the coil spring83urges the assembly comprising the driving member60and the rolling bearings78,80towards the motor54up to abutment of the rolling bearing76against the wall82.

The driving member60is consequently maintained in a predetermined axial position along the axis of the output shaft58(identical here to the axis of the driving member60) relative to the framework8.

The coil spring83may for instance be selected so as to exert, along the axis of the output shaft58, a biasing force greater than a force exerted by the driving member60on the control member62for driving the control member62into motion.

Motion of the control member62(here by rotation, resulting in the same rotation of the cylindrical lens52) can thus be precisely controlled by corresponding motion of the driving member60(itself driven by the motor54). Control of the optical power (here of the cylindrical correction) provided by the cylindrical lens52along the lens axis X is thus improved.