Moving guide actuation of fluid lenses
An example device may include a fluid lens having a membrane assembly including a membrane and one or more membrane attachments, a substrate, a fluid located within an enclosure formed at least in part by the membrane and the substrate, and a support structure, attached to the substrate, including an actuation guide. The device may include an actuator mechanically coupled to the actuation guide and configured to change an orientation of the actuation guide relative to another device component, such as a substrate or frame. An example actuation guide may engage with the membrane attachment, and the movement of the membrane attachment along the actuation guide in response to the change in the orientation of the actuation guide may adjust an optical property, such as a focal length, of the fluid lens.
1. A device comprising a fluid lens, wherein the fluid lens comprises:
a membrane assembly comprising a membrane and a membrane attachment;
a substrate;
a fluid located within an enclosure formed at least in part by the membrane and the substrate;
a support structure, attached to the substrate, comprising an actuation guide that comprises a guide post; and
an actuator, mechanically coupled to the actuation guide and configured to change an orientation of the guide post relative to the substrate, wherein:
the actuation guide engages with the membrane attachment and enables a movement of the membrane attachment along the guide post;
the movement of the membrane attachment along the guide post in response to a change in the orientation of the guide post adjusts a focal length of the fluid lens; and
the actuator is configured to urge the guide post towards a normal or parallel orientation of a direction of elongation of the guide post relative to the substrate.
2. The device of claim 1 , wherein:
the membrane assembly comprises a peripheral structure disposed around a peripheral portion of the membrane;
the peripheral structure comprises a guide wire or a flexible ring; and
the membrane attachment is attached to the peripheral structure.
3. The device of claim 1 , wherein the membrane attachment follows a guide path as the actuator changes the orientation of the actuation guide relative to the substrate.
4. The device of claim 3 , wherein:
the membrane is an elastic membrane under tension;
the membrane has an elastic energy; and
the elastic energy of the membrane is substantially independent of a location of the membrane attachment on the guide path.
5. The device of claim 1 , wherein the guide post is a straight guide post, and the membrane attachment follows a curved guide path as the orientation of the guide post relative to the substrate is changed by the actuator.
6. The device of claim 1 , wherein the actuation guide is hingedly attached to the substrate.
7. The device of claim 1 , further comprising a spring located between the actuation guide and the substrate.
8. The device of claim 1 , wherein the actuator is a piezoelectric actuator.
9. The device of claim 1 , wherein the actuator is located between an actuator support and the actuation guide, and the actuator support is rigidly attached to the substrate.
10. The device of claim 1 , wherein:
the membrane attachment comprises a roller configured to engage with the actuation guide; and
the roller moves along a surface of the actuation guide as the orientation of the actuation guide relative to the substrate is changed by the actuator.
11. The device of claim 10 , wherein the roller comprises an axle and at least one roller wheel and the roller has a generally circular periphery.
12. The device of claim 10 , wherein the roller comprises a cam.
13. The device of claim 1 , wherein the support structure comprises a slot, and a portion of the membrane attachment extends through the slot and engages with a surface of the support structure.
14. The device of claim 1 , wherein the actuation guide moves through an angular range of between approximately 5 degrees and approximately 20 degrees as the fluid lens is adjusted through a focal length range of the fluid lens.
15. The device of claim 1 , wherein:
the device comprises a plurality of support structures including the support structure, and a plurality of membrane attachments including the membrane attachment; and
each support structure of the plurality of support structures is configured to engage with a respective membrane attachment of the plurality of membrane attachments.
16. The device of claim 1 , wherein:
the fluid lens is sized for use with a human eye; the fluid lens has a diameter, width, or analogous dimension between approximately 20 mm and approximately 80 mm;
the substrate is an optically transparent substrate; the membrane is an optically transparent membrane; and
the fluid comprises an optically transparent liquid.
17. The device of claim 1 , wherein the device is a head-mounted device, and the head-mounted device comprises at least one of an ophthalmic device configured to be used as eyewear, an augmented reality device, or a virtual reality device.
18. A method, comprising:
attaching a plurality of membrane attachments to a membrane of a fluid lens;
engaging each membrane attachment of the plurality of membrane attachments with an actuation guide of a respective support structure;
mechanically coupling each actuation guide to an actuator; and
adjusting an orientation of each actuation guide relative to an optic axis of the fluid lens to adjust a focal length of the fluid lens, wherein
each actuation guide comprises a guide post, is supported by a substrate, and is configured to enable a movement of one of the plurality of membrane attachments along the guide post;
the movement of the one of the plurality of membrane attachment along the guide post in response to a change in an orientation of the guide post adjusts the focal length of the fluid lens; and
the actuator is configured to urge the guide post towards a normal orientation or a parallel orientation of a direction of elongation of the guide post relative to the substrate.
19. The method of claim 18 , wherein an elastic energy within the membrane is substantially unchanged as the focal length of the fluid lens is adjusted.