Optical: systems and elements – Lens – Fluid
Reexamination Certificate
1999-01-15
2001-02-13
Epps, Georgia (Department: 2873)
Optical: systems and elements
Lens
Fluid
C359S665000
Reexamination Certificate
active
06188525
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of fabricating a variable focus lens and to the variable focus lens so constructed.
2. Related Art
It is known to provide a variable focus lens in which one or more transparent flexible membranes are tensioned to define a cavity therebetween in which a transparent fluid is received. Adjustment of the pressure and/or volume of the fluid in the cavity causes variations in the shape of the membranes, and the structure defines a lens of variable focal length.
However, whilst it is known to use such a construction to provide a variable focus lens, no current proposals for fabricating such a lens provide a lightweight structure which can easily be incorporated into spectacles, for example.
The present invention seeks to provide a new method of fabricating a variable focus lens and to provide a new structure for such a lens.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention there is provided a method of fabricating a variable focus lens comprising the steps of interengaging first and second rings to engage a first transparent, flexible membrane and to retain said first flexible membrane across the first ring, interengaging a third ring with said first and second rings to engage a second transparent, flexible membrane and to retain said second flexible membrane across the first ring, whereby the first and second flexible membranes define a cavity therebetween, and holding said first, second and third rings together such that said first and second flexible membranes are each tensioned across said first ring.
A method of an embodiment of the invention enables a variable focus lens to be assembled quickly and easily.
A transparent fluid is to be sealed within the cavity defined between the two flexible membranes. In an embodiment, a duct is provided through said rings, which duct is in communication with said cavity. The duct may be formed from pre-formed bores in said first, second and third rings. However, in a preferred embodiment, said duct is drilled, or otherwise formed, through said rings.
In an embodiment said first ring receives said second and third rings therein and defines the periphery of a peripheral, annular frame for the lens, which annular frame is defined by said first, second and third rings. This annular frame may readily be supported within lens apertures provided in spectacles, for example.
The peripheral shape of the peripheral annular frame, and hence of the individual rings, may be chosen as is required. For example, the annular frame may have a circular, oval, elliptical, or other closed curve, peripheral shape.
Any method for holding the first, second and third rings together to retain the flexible membranes under tension may be used.
In a preferred embodiment, the method further comprises turning, crimping or otherwise deforming the first ring so that the second and third rings are retained within said first ring.
Additionally and/or alternatively, said annular frame may be retained within the frame of a pair of spectacles. In this case, the frame of the spectacles may act to hold the first, second and third rings together. Of course, any other retaining means may additionally and/or alternatively be provided to secure the first, second and third rings in their interengaged position.
According to a further aspect of the present invention there is provided a variable focus lens having a cavity containing a transparent fluid defined between first and second transparent, flexible membranes, wherein each of said first and second flexible membranes is tensioned across and held by a peripheral annular frame, and wherein said annular frame is formed from first, second and third interengaged rings, said first ring receiving the second and third rings therein and defining the periphery of said annular frame.
A variable focus lens of an embodiment of the invention is simple and relatively inexpensive to assemble. Furthermore, the lens may be supported readily within the lens aperture in a pair of spectacles, for example.
The peripheral shape of the peripheral annular frame, and hence of the individual rings, may be chosen as is required. For example, the annular frame may have a circular, oval, elliptical, or other closed curve, peripheral shape.
Any method for holding the first, second and third rings together to retain the flexible membranes under tension may be used.
In an embodiment, the annular frame is arranged to be retained within the frame of a pair of spectacles. In this case, the frame of the spectacles may act to hold the first, second and third rings together. Of course, any other retaining means may additionally and/or alternatively be provided to secure the first, second and third rings in their interengaged position.
It is important that the transparent fluid within said cavity cannot leak. Accordingly, it is preferred that the interengagements between said rings cause the periphery of an appropriate flexible membrane to change direction more than once. This aids in sealing the periphery of the cavity.
It would be possible to construct the lens from a single flexible membrane web appropriately arranged to define two flexible membranes. However, in a preferred embodiment, two separate flexible membranes are provided with the periphery of the first flexible membrane being held by the interengagement of the first and second rings, and the periphery of the second flexible membrane being held by the interengagement of the second and third rings. This provides a simple, yet effective sealed structure for the cavity.
Each of said first and second membranes has a continuous periphery which is held by the respective rings so that it is bent to change direction more than once.
Preferably, each of two adjacent rings has a complementary annular step therein for interengaging the two rings, said interengaged steps also guiding an interposed flexible membrane around two direction changes.
In a preferred embodiment, each of said first and second flexible membranes is of high grade Mylar.
The first, second and third rings may be of any suitable material. Preferably, each of the rings is of a material which is sufficiently rigid to positively interengage with the adjacent ring and to ensure that two interengaged rings can maintain the flexible membrane under tension. The material of the rings is also required to be lightweight to facilitate the incorporation of lenses of the invention in spectacles. Thus, the rings may be made, for example, of a high impact resistant plastics material, or of aluminium, or of titanium.
The transparent fluid retained within the cavity may be any suitable fluid. In a preferred embodiment, the fluid is a silicone oil, for example, an oil of the silicone 703 type.
In a preferred embodiment, the lens is additionally provided with two spaced, substantially parallel sheets of transparent polycarbonate between which the cavity defined by the flexible membranes is arranged. The polycarbonate sheets provide protection to the flexible membranes and are readily tinted, for example, if required. The annular frame may also be received between the polycarbonate sheets if required.
REFERENCES:
patent: 4236629 (1980-12-01), Dwinell
patent: 4913536 (1990-04-01), Barnea
patent: 5233470 (1993-08-01), Wu
patent: 5684637 (1997-11-01), Floyd
patent: 5774274 (1998-06-01), Schachar
patent: 5951193 (1999-09-01), Yamamoto et al.
patent: 5956183 (1999-09-01), Epstein et al.
patent: 5963293 (1999-10-01), Jannard
patent: 5971916 (1999-10-01), Koren
Epps Georgia
Sughrue Mion Zinn Macpeak & Seas, PLLC
Thompson Tim
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