WO2012076840A2

WO2012076840A2 - A self-contained lens unit

Info

Publication number: WO2012076840A2
Application number: PCT/GB2011/001688
Authority: WO
Inventors: David Nicholas Crosby; Gregor Allan Storey; Richard Edward Taylor; Owen Fletcher Reading
Original assignee: Gici Labs Llp
Priority date: 2010-12-06
Filing date: 2011-12-06
Publication date: 2012-06-14
Also published as: WO2012076840A3; GB2486212A; GB201020637D0

Abstract

A variable power lens unit based on laterally moving optical plates 10 wherein a movable optical plate 13 resides in the cavity of a capsule formed by joining together a capsule front 12 and capsule back 11. The optical plate 13 is able to move within the capsule as directed by a positioning means (not shown).

Description

TITLE: A self-contained lens unit

This invention relates to variable power lenses in particular variable power lenses that use laterally moving optical plates.

Variable power lenses that use laterally moving optical plates have been known in the art for several decades. A description of the basic form of such moving optical plates is given in US3305294 which describes two non-rotationally symmetric refractive elements whose combined optical power is dependent on their lateral position along an actuation axis with respect to each other. Recent products that make use of this sort of variable power lens include eyeglasses such as the Focusspec (Focus On Vision, The Netherlands), Eyejusters (Eyejusters Ltd, United Kingdom) and the Adlens Emergensee (Adlens Ltd, United Kingdom).

Eyeglasses that employ variable power lenses that use laterally moving optical plates offer the ability to produce products that can cater to a wide section of the population using a single product. Alternatively variable power lenses allow for eyeglasses whose optical power can be adjusted to suit variable requirements of a wearer. For example, a natural consequence of ageing is presbyopia, which is the loss of the ability of the eye to change its focusing power. Presbyopia typically results in an individual only being able to experience good vision at a single distance from the eye and is the primary motivation for innovations such as bifocal lenses, wherein the lens features a region of different focussing power to the rest of the lens, and multifocal lenses, wherein focusing power is varied continuously across an extended region of the lens. Both bifocal lenses and multifocal lenses may ameliorate the symptoms of presbyopia but can also bring complications due to the limited field of view afforded at certain focusing powers, and distortions which arise due to the nature of the optical design required. An alternative to these approaches is to change the optical power of a substantial portion of the lens and this may be accomplished with variable power lenses such as those that use laterally moving optical plates.

One problem with variable power lenses that use laterally moving optical plates is the vulnerability of the design to ingress of dirt and moisture between the optical plates which can lead to damage and reduced optical clarity. One known way of counteracting this problem demonstrated by Eyejusters (Eyejusters Ltd, UK) is to allow one lens to be swung away to permit easy cleaning of both optical plates in each lens. Unfortunately for use in eyeglasses this method results in there being a hinge which then requires concealment for aesthetic purposes. A second way of counteracting this problem that is exhibited by the Focusspec product involves concealing the peripheries of the lenses inside a partially-encapsulating eyeglasses frame. Unfortunately for use in eyeglasses this method lacks robustness as routine use of the eyeglasses means that dirt and moisture will eventually get inside between the optical plates unless stringent and expensive design features are included. Both methods result in reduced aesthetic appeal.

It is an object of the present invention to prevent dirt and moisture getting in between the optical plates and hence avoid the need for a hinge or unsightly lens edge concealment thus providing for a more aesthetically pleasing design and improved robustness to dirt and moisture.

Description of the invention The following descriptions of the present invention are applicable to laterally moving optical plate variable power lenses for use in eyeglasses or any other suitable application.

According to a first aspect of the present invention a laterally moving optical plate variable power lens is composed of an optical plate which is wholly enclosed inside a cavity of a capsule where the body of the optical plate, the void of the cavity and body of the capsule are lying substantially perpendicular to the intended optical axis of the laterally moving optical plate variable power lens. The orientation of the optical axis and hence the orientation of the laterally moving optical plate variable power lens may also accommodate a desired degree of pantoscopic tilt when used in ophthalmic eyeglasses or other tilt away from any plane when used in any application.

The optical plate has sufficient clearance within the cavity such that it is able to move within the cavity as directed by a suitable positioning method.

The optical plate has two optical sides which lie substantially perpendicularly to the intended optical axis. One of these optical sides has a form which may be similar to the optical surface described in '294 or of any suitable freeform shape whereas the other optical side has any other suitable form. Such forms may also accommodate any desired pantoscopic tilt when used in ophthalmic eyeglasses or other tilt away from any plane when used in any application. The optical plate may mainly be comprised of a diffractive optical element include or include a diffractive optical element in its body or on one or both of its surfaces.

The cavity has two main internal optical walls which both lie substantially perpendicular to the intended optical axis. One of these two main internal optical walls also has a form which may be similar to the optical surface described in '294 or of any freeform shape whereas the other internal optical wall has any other suitable form. The two external optical walls of the capsule that lie substantially perpendicular to the intended optical axis have any other suitable form.

Alternatively one of the two external optical walls of the capsule may have a form which is similar to the optical surface described in '294 or of any freeform shape whereas both internal optical walls of the capsule have any other suitable form. Other walls and surfaces of the capsule and optical plates not otherwise mentioned have a form which is suitable for the form and function of the lens. Additionally one or both external optical walls may additionally include one or more diffractive optical elements internally or on one or more of their surfaces.

Mounted in any suitable way to the capsule is an actuating device which is in communication with the optical plate. An example of an actuating device would be a rod that is placed through a hole in the side of the capsule and attached to the end of the optical plate at an angle that is substantially in the plane of the plate and substantially parallel with the actuation axis of the lens. Movement of the rod back and forth along its length causes the optical power of the laterally moving optical plate variable power lens to change. Ingress of dirt, moisture or any other undesired element may be prevented by the use of a grommet seal around the rod, an eiastomeric bellows that encloses the end of the rod or any other suitable means. Other actuating devices may make use of cables, magnets, sliding features or any other suitable method or combination of methods. The use of a magnetic coupling can allow for the communication of actuation from the exterior of the lens through to the inside without the need for eiastomeric bellows, a flexible seal or a sealed grommet around a moving element passing from the exterior to the interior of the lens. Actuating devices may in turn be attached to further adjustment devices of any suitable type.

The capsule and optical plate may include features and extra components that allow for successful guidance, movement and positioning of the plate within the void. These may include, but not be limited to, rails, discrete springs, spring features, rods, spigots, dovetails, cams, cables, grooves or any other positioning or guidance method.

The void within the capsule may be filled with a fluid in order to modify and enhance advantageously certain optical characteristics of the lens. Therefore the capsule may have suitable features to allow for filling with a fluid during assembly.

The capsule and optical plate may each be assemblies that are composed of more than one component. However each assembly should still be thought of as fulfilling the functions described.

The capsule may have features that allow attachment to external structures such as bevels, grooves, threaded holes, spigots, tabs or any other suitable feature. Attachment may be accomplished using bolts, rivets, adhesives, wires, enclosing geometry or any other suitable method. Such external structures may include eyeglasses frames or any other applicable structure.

The capsule and optical plate may be composed of any suitable material such as an optical plastic or glass. The capsule and optical plate and any components thereof may be composed of more than one material and assembled using any suitable technique or method. If composed of assemblies then the capsule and optical plate may be composed of components that have features that provide for easy assembly.

The optical walls of the capsule and optical plate may feature any suitable surface form including refractive, diffractive or hybrid refractive-diffractive elements.

According to a second aspect of the present invention a laterally moving optical plate variable power lens is composed of a first and second optical plate which are wholly enclosed inside a cavity of a capsule where the bodies of the optical plates, the void of the cavity and body of the capsule are lying substantially perpendicular to the intended optical axis of the laterally moving optical plate variable power lens. The orientation of the optical axis and hence the orientation of the laterally moving optical plate variable power lens may also accommodate a desired degree of pantoscopic tilt when used in ophthalmic eyeglasses or other tilt away from any plane when used in any application.

The optical plates have clearance on all sides within the cavity and are able to move within the cavity as directed by a suitable positioning method.

The optical plates have two optical sides which lie substantially perpendicularly to the intended optical axis. One of these optical sides on each optical plate has a form which may be similar to the optical surface described in '294 or of any freeform shape whereas the other optical side has any other suitable form. Such forms may also accommodate any desired pantoscopic tilt when used in ophthalmic eyeglasses or other tilt away from any plane when used in any application. The relative orientations of the two optical surfaces as described in '294 or of any freeform shape are such that relevant lateral movement of the place causes a change in the combined optical characteristics of the two optical plates such as a change in spherical power. The optical plates may include diffractive optical elements in their bodies or on one or more of their surfaces.

The cavity has two main internal optical walls which both lie substantially perpendicular to the intended optical axis. The two external optical walls and the two internal walls of the capsule that lie substantially perpendicular to the intended optical axis have any suitable form necessary for successful operation of the invention. One or both external optical walls may include one or more diffractive optical elements internally or on one or more of their surfaces.

The capsule and optical plates may each be assemblies that are composed of more than one component. However each assembly should still be thought of as fulfilling the functions described.

In a similar way to the first aspect of the present invention, this second aspect of the present invention may include means for altering the position of the two optical plates inside the cavity, for mounting the capsule to external structures, for actuating, guiding, moving and positioning the optical plates inside the cavity and for excluding the ingress of dirt, moisture or any other undesired element. Any actuating devices may in turn be attached to further adjustment devices of any suitable type. Furthermore such means include suitable features or mechanisms for allowing substantially equal and opposite directed movement of the two optical plates on the same or substantially parallel linear or curvilinear paths.

The capsule and optical plates may be composed of any suitable material such as an optical plastic or glass. The capsule and optical plates and any components thereof may be composed of more than one material and assembled using any suitable technique or method. If composed of assemblies then the capsule and optical plates may be composed of components that have features that provide for easy assembly.

The optical walls of the capsule and optical plates may feature any suitable surface form including refractive, diffractive or hybrid refractive-diffractive elements.

In both aspects of the current invention the external optical surfaces of the capsule may advantageously be given further optical characteristics such as sphere, cylinder or prism optical powers. Furthermore completed versions of such laterally moving optical plate variable power lenses may be modified after manufacture or assembly such that one or both external optical surfaces may advantageously be given further optical characteristics such as sphere, cylinder or prism optical powers.

Additionally, in both aspects of the present invention a moving optica) plate variable power lens according to the present invention may be designed, adapted, modified or arranged to work with one or more other moving optical plate variable power lens according to the present invention or with other lenses or optical components of a type not described herein. Description of the figures

Figure 1 A view of a lens according to the invention

Figure 2 An exploded front view of a lens according to the invention

Figure 3 An exploded rear view of a lens according to the invention

Figure 4 Locations of cross-sections taken through an assembled lens according to the invention Figure 5 Vertical cross-sections taken through an assembled lens according to the invention Figure 6 A horizontal cross-section through an assembled lens according to the invention

Figure 7 An assembled lens featuring an adjustment means in an embodiment according to the invention

Figure 8 A view of the attachment of an adjustment means to an optical plate in an embodiment according to the invention

A preferred embodiment

Figure 1 shows a moving optical plate variable power lens 10 of the present invention without a lens actuating mechanism attached. The profile of the moving optical plate variable power lens in this embodiment allows for its integration into an eyeglasses frame (not shown). The optical parts consist of a capsule back 11 a capsule front 12 and an optical plate 13. The capsule back 11, capsule front 12 and optical plate 13 are all constructed from an optical polycarbonate which has been injection moulded into the correct shape. The capsule front 12 has a bevel composed of a first angled face 28 and a second angled face 29 which holds the moving optical plate variable power lens 10 inside an eyeglasses frame (not shown). The capsule front 12 and capsule back 11 are joined together in an ultrasonic welding process aided by suitable geometry (not shown) at the joint interface.

With reference to Figure 2 and Figure 3 the capsule back 11 is seen to have an internal spherical optical surface 21, a rear capsule wall 23, an exterior spherical optical surface 34 and an access port 22. The capsule front 12 has an internal freeform surface 31, an external spherical optical surface 27 and a side edge 26. The optical plate 13 is seen to have a freeform optical surface 25, a spherical optical surface 32, sprung arms 24 and a lipped recess 33.

Figure 4 and Figure 5 show the arrangement of the optical surfaces in the embodiment in a null optical power. The optical plate 13 is disposed in between the capsule back 11 and the capsule front 12. The first vertical section 51 shown at the first vertical section line 41 shows the convex nature of the internal freeform surface 31 in the capsule front 12 and the corresponding concave nature of the spherical optical surface 32 in the optical plate 13 along the section at this point. The second vertical section 52 shown at the second vertical section line 42 shows how both the internal freeform surface 31 and the spherical optical surface 32 at this point are approaching piano along the section at this point. The third vertical section 53 shown at the third vertical section line 43 shows the concave nature of the internal freeform surface 31 in the capsule front 12 and the corresponding convex nature of the spherical optical surface 32 in the optical plate 13 along the section at this point. Complementing these cross sectional views is Figure 6 which shows a horizontal cross section 44 at the horizontal section line 44. The offset between the optical plate 13 spherical surface 32 and capsule front 12 internal freeform surface 31 is kept as small as possible whilst allowing sufficient space for lateral movement and any assembly variation. Thus a zero optical power arrangement is seen. The optical plate 13 is kept aligned with respect to the capsule front 12 and the capsule rear 11 by the presence and geometry of the sprung arms 24 and a number of further alignment features (not shown). The sprung arms 24 and further alignment features (not shown)between the spherical surface 32 and internal spherical optical surface 21 also ensure the optical plate 13 move in a curvilinear manner in keeping with the geometry of the rear capsule wall 23. The void 54 between the capsule front 12, capsule rear 11 and optical plate 13 is also shown.

Figure 7 and Figure 8 show a moving optical plate variable power lens with attached lens actuating mechanism 70 according to this embodiment. A stainless steel rod 72 with a collar 81 at one end passes through the access port 22 such that the collar 81 engages with the lipped recess 33. Back and forth movement of the rod 72 causes the optical plate 13 to slide in a curvilinear path between the capsule front 12 and capsule rear 11 hence causing the combined optical power of the freeform optical surface 25 and internal freeform surface 31 to vary. A small amount of clearance between the collar 81 and lipped recess 33 allows the collar 81 to move within the lipped recess 33 thus preventing any jamming of the mechanism. Dirt and moisture are prevented from accessing the assembly by the use of a Viton rubber bellows 71 which attaches to the capsule rear 11 at one end and to a Viton o-ring seal 73 at the other. The o-ring seal 73 fits tightly around the rod 72 thus ensuring a robust sealing arrangement that allows for back and forth movement of the rod 72. The end of the rod 72 is then attached to further adjustment means (not shown) in order to implement inclusion of the moving optical plate variable power lens into a variable power eyeglasses device.

TITLE: A self-contained lens unit

This invention relates to variable power lenses in particular variable power lenses that use laterally moving optica l plates.

Variable power lenses that use laterally moving optical plates have been known in the an for several decades. A description of the basic form of such moving optical plates is given in US3305294 which describes two non-rotationally symmetric refractive elements whose combined optical power Is dependent on their lateral position along an actuation axis with respect to each other. Recent products that make use of this sort of variable power lens include eyeglasses such as the Focusspec (Focus On Vision, The Netherlands), Eyejusters (Eyejusters Ltd, United Kingdom) and the Adlens Emergensee (Adlens Ltd, United Kingdom).

Eyeglasses that employ variable power lenses that use laterally moving optical plates offer the ability to produce products that can cater to a wide section of the population using a single product. Alternatively variable power lenses allow for eyeglasses whose optical power ca n be adjusted to suit variable requirements of a wearer. For example, a natural consequence of ageing is presbyopia, which is the loss of the ability of the eye to change its focusing power. Presbyopia typically resu lts in an individual only being able to experience good vision at a single distance from the eye and is the primary motivation for innovations such as bifocal lenses, wherein the lens features a region of different focussing power to the rest of the lens, and multifocal lenses, wherein focusing power is varied continuously across an extended region of the lens. Both bifocal lenses and multifocal lenses may ameliorate the symptoms of presbyopia but can also bring complications due to the limited field of view afforded at certain focusing powers, and distortions which arise due to the nature of the optical design required. An alternative to these approaches is to change the optical power of a substantial portion of the lens and this may be accomplished with variable power lenses such as those that use laterally moving optical plates.

One problem with variable power lenses that use laterally moving optical plates is the vulnerability of the design to ingress of dirt and moisture between the optical plates which can lead to damage and reduced optical clarity. One known way of counteracting this problem demonstrated by Eyejusters (Eyejusters Ltd, UK) is to allow one lens to be swung away to permit easy cleaning of both optical plates in each lens. Unfortunately for use in eyeglasses this method results in there being a hinge which then requi res concealment for aesthetic purposes. A second way of counteracting this problem that is exhibited by the Focusspec product involves concealing the peripheries of the lenses inside a partially-encapsulating eyeglasses frame. Unfortunately for use in eyeglasses this method lacks robustness as routine use of the eyeglasses means that dirt and moisture will eventually get inside between the optical plates unless stringent and expensive design features are Included. Both methods result in reduced aesthetic appeal.

Description of the Invention The following descriptions of the present invention are applicable to latera lly moving optical plate variable power lenses for use in eyeglasses or any other suitable application.

The optica l plate has sufficient clearance within the cavity such that it is able TO move within the cavity as directed by a suitable positioning method.

The optical plate has two optical sides which lie substantially perpendicularly to the intended optical axis. One of these optical sides has a form which may be simila r to the optical surface described in '294 or of any suitable freeform shape whereas the other optical side has any other suitable form. Such forms may also accommodate any desired pantoscopic tilt when used in ophthalmic eyeglasses or other tilt away from any plane when used in a ny application. The optical plate may main ly be comprised of a dlffractlve optical element Include or include a d if inactive optical element In its body or on one or both of its surfaces.

The cavity has two main internal optical walls which both lie substantially perpendicular to the intended optical axis. One of these two main internal optical walls a lso has a form which may be similar to the optical surface described in '294 or of any Freeform shape whereas the other internal optical wall has any other suitable form. The two external optical walls of the capsule that lie substantially perpendicular to the intended optical axis have any other suitable form.

Alternatively one of the two external optical walls of the capsule may have a form which is similar to the optical surface described in '294 or of any freeform shape whereas both internal optical walls of the capsule have any other suitable form. Other walls and surfaces of the ca psule and optical plates not otherwise mentioned have a form which is suitable for the form and function of the lens. Additionally one or both external optica l walls may additionally include one or more diffractive optical elements internally or on one or more of their surfaces.

Mounted in any suitable way to the capsule is an actuating device which is in communication with the optical plate. An example of an actuating device would be a rod that is placed through a hole in the side of the ca psule and attached to the end of the optical plate at an angle that is substantia lly in the plan« of the plate a nd substantially parallel with the actuation axis of the lens, Movement of the rod back and forth along its length causes the optical power of the laterally moving optical plate variable power lens to change. Ingress of dirt, moisture or any other undesired element may be prevented by the use of a grom met seal around the rod, an elastomeric bellows that encloses the end of the rod or any other suitable means. Other actuating devices may make use of cables, magnets, sliding features or any other suitable method or combination of methods. The use of a magnetic coupling can allow for the communication of actuation from the exterior of the lens through to the inside without the need for elastomeric bellows, a flexible seal or a sealed grommet around a moving element passing from the exterior to the interior of the lens. Actuating devices may in turn be attached to further adjustment devices of any suitable type.

The capsule a nd optical plate may include features and extra components that allow for successful guidance, movement a nd positioning of the plate within the void. These may include, but not be limited to, rails, discrete springs, spring features, rods, spigots, dovetails, cams, cables, grooves or a ny other positioning or guidance method.

The void withi n the capsule may be filled with a fluid in order to modify and enhance advantageously certain optical characteristics of the lens. Therefore the capsule may have suitable features to allow for filling with a fluid during assembly.

The capsule may have features that allow attach ment to external structures such as bevels, grooves, threaded holes, spigots, tabs or any other suitable feature. Attachment may be accomplished using bolts, rivets, adhesives, wires, enclosing geometry or any other suitable method. Such external structures may include eyeglasses frames or any other applicable structure.

The capsule and optical plate may be composed of any suitable material such as an optical plastic or glass. The capsule and optica l plate and any components thereof may be com posed of more than one material and assembled using any suitable technique or method. If composed of assemblies then the capsule and optical plate may be composed of components that have features that provide for easy assembly.

The optica l walls of the capsule and optical plate may feature any suitable surface form including refractive, diffractive or hybrid refractive-dif tractive elements.

According to a second aspect of the present invention a laterally moving optical plate variable power lens is composed of a first and second optical plate which are wholly enclosed inside a cavity of a capsule where the bodies of the optical plates, the void of the cavity and body of the capsule are lying substantially perpendicular to the intended optical axis of the laterally moving optical plate variable power lens. The orientation of the optical axis and hence the orientation of the laterally moving optical plate variable power lens may also accommodate a desired degree of pantoscopic tilt when used in ophthalmic eyeglasses or other tilt away from any plane when used in any a pplication.

The optical plates have cleara nee on all sides within the cavity and are able to move within the cavity as directed by a suitable positioning method.

The optical plates have two optical sides which lie substantia lly perpendicularly to the intended optical axis. One of these optical sides on each optical plate has a form which may be similar to the optical surface described in '294 or of any freeform shape whereas the other optical side has any other suitable form. Such forms may also accommodate any desired pantoscopic tilt when used in ophthalmic eyeglasses or other tilt away from any plane when used in any application. The relative orientations of the two optical surfaces as described in '294 or of any freeform shape are such that relevant lateral movement of the place causes a change in the combined optical characteristics of the two optical plates such as a change in spherical power. The optical plates may include diffractive optical elements in their bodies or on one or more of their surfaces.

The cavity has two main internal optical walls which both lie substantially perpendicular to the intended optical axis. The two external optical walls and the two internal walls of the capsule that lie substantia lly perpendicular to the intended optical axis have any suitable form necessary for successful operation of the Invention. One or both external optical walls may include one or more diffractive optical elements internally or on one or more of their surfaces.

In a similar way to the first aspect of the present invention, this second aspect of the present invention may include means for altering the position of the two optical plates inside the cavity, for mou nting the capsule to external structures, for actuating, guiding, moving and positioning the optical plates inside the cavity and for excluding the ingress of dirt, moisture or any other undesired element Any actuating devices may in turn be attached to further adjustment devices of any suitable type. Furthermore such means include suitable features or mechanisms for allowing substantially equal and opposite directed movement of the two optical plates on the same or substantially parallel linear or curvilinear paths.

The capsule and optical plates may be composed of any suitable material such as an optical plastic or glass. The capsule a nd optica l plates and any components thereof may be composed of more than one material and assembled using any suitable technique or method. If composed of assemblies then the capsule a nd optical plates may be composed of components that have features that provide for easy assembly.

Additionally, in both aspects of the present Invention a moving optical plate variable power lens according to the present Invention may be designed, adapted, modified or arranged to work with one or more other moving optical plate variable power lens according to the present Invention or with other lenses or optica l components of a type not described herein. Description of the flgu res

Figure 1 A view of a lens according to the invention

Figure 2 An exploded front view of a lens according to the Invention

Figure 3 An exploded rear view of a lens according to the invention

Figure 4 Locations of cross-sections taken through an assembled lens according to the invention Figure 5 Vertical cross-sections taken through an assembled lens according to the invention Figure s A horizontal cross-section through an assembled lens according to the invention

Figure 8 A view of the attachment of .an adjustment means to an optical plate in an embodiment according to the invention

A preferred embodiment

Figure 1 shows a moving optical plate variable power lens 10 of the present invention without a lens actuating mechanism attached. The profile of the moving optical plate variable power lens in this embodiment allows for its integration into an eyeglasses frame (not shown). The optical parts consist of a capsule back 11 a capsule front 12 and an optica l plate 13. The capsule back 11, capsule front 12 and optica l plate 13 a re all constructed from an optical polycarbonate which has been injection moulded into the correct shape. The capsule front 12 has a bevel composed of a first a ngled face 28 and a second angled face 29 which holds the moving optical plate variable power lens 10 inside an eyeglasses frame ( not shown). The capsule front 12 and capsule back 11 are joined together in an ultrasonic welding process aided by suitable geometry (not shown) at the joint interface.

With reference to Figure 2 a nd Figure 3 the capsule back 11 is seen to have an internal spherical optical surface 21, a rear capsule wall 23, an exterior spherical optical surface 34 and an access port 22. The capsule front 12 has an interna l freeform surface 31, an external spherical optical surface 27 and a side edge 2S. The optical plate 13 is seen to have a freeform optical su rface 25, a spherical optical surface 32, sprung arms 24 and a lipped recess 33.

Figure 4 and Figure 5 show the arrangement of the optical su rfaces In the embodiment in a null optical power. The optical plate 13 is disposed in between the capsule back 11 and the capsule front 12. The first vertical section 51 shown at the first vertical section line 41 shows the convex nature of the i nternal freeform surface 31 in the capsule front 12 and the corresponding concave nature of the spherical optical surface 32 in the optical plate 13 along the section at this point. The second vertical section 52 shown at the second vertical section line 42 shows how both the internal freeform surface 31 and the spherical optica! surface 32 at this point are approaching piano along the section at this point. The third vertical section 53 shown at the third vertical section line 43 shows the concave nature of the internal freeform surface 31 In the capsule front 12 and the corresponding convex nature of the spherical optical surface 32 In the optical plate 13 a long the section at this point. Complementing these cross sectional views is Figure 6 which shows a horizonta l cross section 44 at the horizontal section line 44. The offset between the optical plate 13 spherical surface 32 and capsule front 12 internal freeform surface 31 is kept as small as possible whilst allowing sufficient space for lateral movement and any assembly variation. Thus a zero optica l power a rra ngement is seen. The optical plate 13 is kept aligned with respect to the capsule front 12 and the capsule rear 11 by the presence and geometry of the sprung arms 24 and a number of further alignment features (not shown). The sprung arms 24 and further alignment features (not shown)between the spherical surface 32 and internal spherical optical surface 21 also ensure the optical plate 13 move in a curvilinear manner in keeping with the geometry of the rear capsule wall 23. The void 54 between the capsule front 12, capsule rear 11 and optical plate 13 is also shown.

Figure 7 and Figure 8 show a moving optical plate variable power lens with attached lens actuating mechanism 70 according to this embodiment. A stainless steel rod 72 with a collar 81 at one end passes through the access port 22 such that the colla r 81 engages with the lipped recess 33. Back a nd forth movement of the rod 72 causes the optical plate 13 to slide in a curvilinear path between the capsule front 12 and capsule rear 11 hence causing the combined optica l power of the freeform optical surface 25 a nd internal freeform surface 31 to vary. A small amount of clearance between the collar 81 and lipped recess 33 allows the collar 81 to move within the lipped recess 33 thus preventing any jam ming of the mechanism. Dirt and moisture are prevented from accessing the assembly by the use of a Viton rubber bellows 71 which attaches to the capsule rear 11 at one end a nd to a Viton o-ring seal 73 at the other. The o-ring seal 73 fits tightly around the rod 72 thus ensuring a robust sealing arrangement that allows for back and forth movement of the rod 72. The end of the rod 72 is then attached to further adjustment means (not shown] in order to implement inclusion of the moving optical piste variable power lens into a variable power eyeglasses device.

Claims

1. A laterally moving plate variable power lens composed of an optical plate wholly enclosed inside the cavity of a capsule such that the body of the optical plate, the void of the cavity and body of the capsule lie substantially perpendicular to the optical axis of the laterally moving plate variable power lens characterised in that:

a. The optical plate has two optical sides which lie substantially perpendicular to the optical axis;

b. The cavity has two optical wa lls which lie substantia llv perpendicular to the optical axis;

c. The capsule has two external optical walls which lie substantially perpendicular to the optical axis;

d. The optical plate is able to move within the capsule as directed by a positioning mea ns.

2. A laterally moving plate variable power lens according to claim 1 characterised in that the positioning means is a rod passing through a hole in the side of the capsule and attached to the end of the optical plate at an angle that is substantially in the plane of the optical plate and substantially parallel to the actuation axis of the lens.

3. A laterally moving plate variable power lens according to claim 2 where a grcmmet seal is placed around the rod and in the hole of the side of the capsule,

d. A laterally moving plate variable power lens according to claim 3 where the grommet seal is an O-ring.

5. A laterally moving plate variable power lens according to claim 4 where the O-ring is made from Viton rubber.

6. A laterally moving plate variable power lens according to claim 2 where elastomeric bellows enclose the end of the rod.

7. A laterally moving plate variable power lens according to claim 1 characterised in that the positioning means Is a cable.

8. A laterally moving plate variable power lens according to claim 1 characterised in that the positioning means uses a magnetic coupling between the exterior and interior of the capsule.

9. A laterally moving plate variable power lens according to claim 1 characterised in that any optical side of the optical plate has a freeform refractive optical surface;

10. A laterally moving plate variable power lens according to claim 1 characterised in that any optical wall of the cavity has a freeform refractive optica I surface;

11. A laterally moving plate variable power lens according to claim 1 characterised in that any external optical wall of the capsule has a freeform refractive optica l surface;

12. A laterally moving plate variable power lens according to claim 1 characterised in that any optical side of the optica l plate has a diffractive optical surface;

13. A laterally moving plate variable power lens according to claim 1 characterised in that any optical wall of the cavity has a diffractive optical surface;

14. A laterally moving plate variable power lens according to claim 1 characterised in that any optical side of the optical plate has a hybrid diffractive- refractive optical surface;

15. A laterally moving plate variable power lens according to claim 1 characterised in that any optical wall of the cavity has a hybrid diffractive- refractive optical surface;

16. A laterally moving plate variable power lens according to claim 1 characterised by a combination of features according to claims 9-15;

17. A laterally moving plate variable power lens according to claim 1 characterised in that the optical plate is equipped with suitable featu res that provide for smooth movement of the optical plate within the cavity;

18. A laterally moving plate variable power lens according to claim 1 characterised in that the positioning means is in communication with an additional adjustment means;

19. A laterally moving plate variable power lens according to claim 1 characterised in that the void of the cavity is filled with a fluid;

20. A laterally moving plate variable power lens according to claim 19 having any suitable means for allowing the filling of the void of the cavity during manufacture;

21. A laterally moving plate variable power lens composed of a first and second optical plate which are wholly enclosed inside the cavity of a capsule such that the bodies of the optical plates, the void of the cavity and body of the capsule lie substa ntially perpendicular to the optical axis of the laterally moving plate variable power lens characterised in that:

a. The first optical plate has two optical sides which lie substantially perpendicular to the optical axis;

b. The second optical plate has two optical sides which lie substantially perpendicular to the optical axis;

c. The cavity has two optical wa lls which lie substantially perpendicular to the optical axis;

d. The capsule has two external optica l walls which lie substantially perpendicular to the optical axis;

e. Both optical plates are able to move within the capsule and relative to each other as directed by a positioning mea ns.

22. A laterally moving plate variable power lens according to claim 21 characterised in that any optical side of the optica l plate has a freeform refractive optical surface;

23. A laterally moving plate variable power lens according to claim 21 characterised in that any optical wall of the cavity has a freeform refractive optical surface;

24. A laterally moving plate variable power lens according to claim 21 characterised in that any external optical wall of the capsule has a freeform refractive optical surface;

25. A laterally moving plate variable power lens according to claim 21 characterised in that any optical side of the optica l plate has a diffractive optical surface;

26. A laterally moving plate variable power lens according to claim 21 characterised in that any optical wall of the cavity has a diffractive optical surface;

27. A laterally moving plate variable power lens according to claim 21 characterised in that any optical side of the optica I plate has a hybrid diffractive- refractive optical surface;

28. A laterally moving plate variable power lens according to claim 21 characterised in that any optical wall of the cavity has a hybrid diffractive-refractive optical surface;

29. A laterally moving plate variable power lens according to claim 21 characterised by a

combination of features according to claims 22-28;

30. A laterally moving plate variable power lens according to claim 21 characterised in that the optical plate is equipped with suitable featu res that provide for smooth movement of the optical plate within the cavity;

31. A laterally moving plate variable power lens according to claim 21 characterised in that the positioning means is in communication with an additional adjustment means;

32. A laterally moving plate variable power lens according to claim 21 characterised in that the void of the cavity is filled with a fluid;

33. A laterally moving plate variable power lens according to claim 32 having any suitable means for allowing the filling of the void of the cavity during manufacture;

34. A laterally moving plate variable power lens according to any preceding claim having suitable means for prevention of ingress of unwanted matter into the void of the cavity;

35. A laterally moving plate variable power lens according to any preceding claim having suitable means of attachment of the capsule to externa l structures;

36. A laterally moving plate variable power lens according to any preceding claim characterised in that one or more aforementioned components are in turn assemblies of one or more components.