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US 5,712,721 AGranted
Switchable lens
AssigneeThe Technology Partnership PLC
InventorTimothy Andrew Large
Life of this patent
Estimating the term…
Abstract
A lens assembly (1) comprises a lens (2;10,11;20) the focal length of which may be changed by application of an electric or magnetic field. A switching means (4,15) provides a drive impulse to change the focal length of the lens (2;10,11;20). An integral power source (4,15) provides power for the switching means. A lens which can be switched between near and distance vision by the user is thereby provided.
Claims24
A lens assembly comprising:
- a lens including a layer of cholesteric liquid crystal having a property which may be switched by application of an electric or magnetic field, said property being at least one of focal length, absorption, color and effective aperture, without employing a polarizer;
- switching means coupled to the lens to provide a drive impulse to switch the property of the lens;
- and
- a power source coupled to the switching means to provide power for the switching means.
1 more element
A lens assembly comprising:
- a lens having a property which may be switched by application of an electric or magnetic field, said property being at least one of focal length, absorption, color and effective aperture;
- switching means coupled to the lens to provide a drive impulse to switch the property of the lens;
- a power source coupled to the switching means to provide power for the switching means;
- and
- wherein the switching means includes means for detecting a drop in a level of ambient light and changing the property of the lens when the level of detected light level drops for longer than a predetermined period of time.
2 more elements
An assembly according to claim 14 wherein the liquid crystal contains a dichroic dye.
A lens assembly comprising:
- a lens having a property which may be switched by application of an electric or magnetic field, said property being at least one of focal length, absorption, color and effective aperture;
- switching means coupled to the lens to provide a drive impulse to switch the property of the lens;
- and
- a power source coupled to the switching means to provide power for the switching means wherein the power source is a battery which is operable using tear fluid.
1 more element
A lens assembly comprising:
- a lens including a layer of liquid crystal which may be switched between two different focal lengths, independent of polarization of the incident light, by application of an electric or magnetic field;
- switching means coupled to the lens to provide a drive impulse to switch the focal length of the lens;
- and
- a power source coupled to the switching means to provide power for the switching means.
1 more element
Dependencies are inferred from the claim text.