1. Field of the Invention
This invention is related to an optical axis orientating device and, more particularly, to an optical axis orientating device for a liquid lens.
2. Description of the Prior Art
Generally, a liquid lens refers to a focal length tuning lenses. In optical systems, focal length tuning lenses can be categorized into mechanical tuning lenses and electrical tuning lenses. As for mechanical tuning lenses, the tuning function is achieved by a motor which moves lenses forward or backward. However, due to the pursuit of miniaturization of digital cameras or mobile phones with an image-capturing function, mechanical tuning lenses are replaced with electrical tuning lenses in many light-and-thin cameras for the reason of thick lens and large volume.
In the prior art, an electrical tuning lens takes a droplet as a lens. The shape and curvature of the droplet can be controlled by use of an electrowetting mechanism to adjust the focal length of the droplet. However, if the droplet is not centered well, an optical axis of the droplet may be skew and cause the lens to focus inaccurately.
As shown in FIG. 1, one centering method is to dispose the droplet on the recess of the bell structure to prohibit the droplet from rolling. As shown in FIG. 2, another centering method is to dispose the droplet in a fluid chamber and then dispose another liquid to assist in centering the droplet. Because these two liquids are immiscible, a cambered interface in FIG. 2 is formed after the surface tension is balanced.
The drawbacks of the foregoing prior arts are a complicated manufacture process and high manufacture cost. Therefore, the invention provides an optical axis orientating device for a liquid lens to solve the above problems.