Autofocus camera and optical device with variable focal length intended to be integrated into such a camera

An autofocus camera comprising:

• an image sensor,
• an optical block comprising a plurality of lenses with fixed focal length,
• an optical device with variable focal length comprising:
• a deformable membrane,
• a support to which a peripheral anchoring area of said membrane is connected,
• a cavity filled with a constant volume of fluid, said cavity being delimited at least in part by said membrane and a support wall, and
• an actuation device of a region of the membrane located between the peripheral anchoring area and a central part of the membrane, configured to bend by application of electrical actuation voltage so as to displace some of the fluid volume towards the centre or towards the periphery of the cavity,
• wherein at least one region of the optical device distinct from the central part and the actuation region of the membrane is stressed mechanically permanently by a component of the autofocus camera so as to cause permanent deformation of the central part of the membrane by the fluid, the focal distance of the optical device at rest under the effect of said mechanical stress being different from the focal distance of said optical device at rest prior to application of said stress.

An optical device with variable focal length, the optical device comprising:

• a deformable membrane,
• a support to which a peripheral anchoring area of said membrane is connected,
• a cavity filled with a constant volume of fluid, said cavity being delimited at least in part by said membrane and a support wall, and
• an actuation device of a region of the membrane located between the peripheral anchoring area and a central part of the membrane, configured to bend by application of electrical actuation voltage so as to displace some of the fluid volume towards the centre or towards the periphery of the cavity,
• wherein at least one region of the optical device distinct from the central part and the actuation region of the membrane is configured to be stressed mechanically permanently by a component of an autofocus camera so as to cause permanent deformation of the membrane by the fluid, the focal distance of the optical device at rest under the effect of said mechanical stress being different from the focal distance of said optical device at rest prior to application of said stress.

A method of manufacturing an autofocus camera, the method comprising:

• assembling an optical block on an image sensor, wherein the optical block comprises a plurality of lenses with fixed focal length, and
• assembling an optical device with variable focal length on the whole formed by the optical block and the image sensor, wherein:
• the optical device comprises:
• a deformable membrane,
• a support to which a peripheral anchoring area of said membrane is connected,
• a cavity filled with a constant volume of fluid, said cavity being delimited at least in part by said membrane and a support wall, and
• an actuation device of a region of the membrane located between the peripheral anchoring area and a central part of the membrane, configured to bend by application of electrical actuation voltage so as to displace some of the fluid volume towards the centre or towards the periphery of the cavity, and
• the assembling the optical device on the whole comprises applying mechanical stress on a region of said optical device separate from the central part and of the actuation region of the membrane, the effect of said stress being displacing some of the fluid volume and deforming the central part of the membrane so as to vary the focal distance of the optical device at rest.