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Canon patent describes novel liquid lens design
Another interesting patent has been discovered by Japanese blogger Egami, which shows a new method devised by Canon to adjust the shape of meniscus lens that seems different from the more straightforward method used by competitors. Canon's method uses the same 'electrowetting' principle as existing designs but does so to create a series of pumps, allowing faster and more precise control over the resultant lens.
Rather than directly distorting a lens formed from the barrier between two fluids, Canon's design features a series of parallel electrodes around the edges of the lens that end up forming individually controllable pumps. Selectively engaging these pumps pushes more of one of the fluids into the main lens chamber, changing the shape of the lens.
Liquid lenses are not new; in fact there are many already in use in industrial applications, such as those marketed by Varioptic. The company's site offers a good primer on how electrowetting is used to create variable-focus lenses.
However, whereas Verioptic's design seeks to directly change the shape of the lens, placing electrodes above and below the fluid lens' surface, Canon's design effectively turns this design through 90 degrees, and uses the the controllable fluid surfaces as pumps to move fluid in and out of a central chamber, which then acts as the lens.
|Canon's patent describes a novel way to control a liquid lens. The patent can be seen here or by clicking on the image.|
The design can be used in an essentially binary manner, with each 'pump' flipping between a relaxed or pumped state - which means the lens can be refocused quickly and precisely by engaging the desired number of pumps.
Canon's patents indicate that the idea is fairly well developed - with one design featuring a series of triangular pumps arranged in a concentric ring pattern. The patent suggests such a lens could be used for a cell phone or surveillance camera.