TECHNICAL FIELD

The present disclosure relates to stereo imaging. More specifically, this disclosure pertains to a compact folded-parallel-light-channel (FPLC) stereo imaging system synchronously generating a left view and a right view of a scene, and also providing both disparity and convergence angle control. The disclosed stereo imaging system finds utility in a variety of devices including compact mobile devices such as cell phones and smartphones.

BACKGROUND OF THE INVENTION

A critical point in designing an embedded imaging system for a handheld or other mobile device such as a smartphone is to ensure the height (thickness) of the imaging system is smaller than (or, at least, close to) the thickness of the cell phone. The image sensor of a cell phone imaging system is of a fixed dimension (4.80×3.60 mm). To ensure images of the same size as the image sensor are produced, one cannot unlimitedly reduce the sizes of the lenses used in a cell phone imaging system. Hence, a telephoto camera usually cannot be used for a mobile device such as a smartphone since such a camera when equipped with camera comprising a plurality of lenses disposed to refract light to form an image at a cell phone camera image sensor (CPCIS), would require at least 14 mm for its height (seeFIG. 1for an example) while the thickness of a typical smartphone is between 7 and 9 mm only.

To allow a telephoto camera equipped with a CPCIS to be embedded in a smartphone, prior art devices are known (seeFIG. 2) wherein the telephoto camera is “folded” by inserting a light-folding mirror in the lens system so that the optical axis (see dotted line) is redirected from vertical to horizontal once it reaches the folding mirror. The image sensor is installed on an orientation defining a plane oriented vertically to a plane defined by the ground, instead of parallel to a plane defined by the ground. By folding a telephoto camera equipped with a CPCIS in this manner, the height of the camera can be made as small as 7 mm and consequently can be embedded into a smart cell phone. As examples, see U.S. Pat. No. 9,316,810 to Mercado and U.S. Pat. No. 9,172,856 to Bohn et al., the entire disclosures of each of which are incorporated herein by reference.

In theory, a stereo imaging system could be provided by arranging two identical imaging systems such as those shown inFIG. 2symmetrically as shown inFIG. 3. Such a hypothetical stereo imaging system could be embedded in a mobile device such as a smartphone completely. However, the only way to provide disparity (interocular distance) control for such a stereo imaging system would be to configure each of the left and right imaging systems to translate laterally in their entirety relative to one another. This is illustrated inFIG. 3. Such an arrangement, while hypothetically configurable, would require additional packaging space potentially not available in small mobile devices such as smartphones.

Accordingly, a need in the art is identified for improvements to imaging systems for small mobile devices, providing stereo imaging systems including such convergence and disparity control. The following disclosure describes a folded-parallel-light-channel stereo imaging system for a mobile device configured to allow disparity and convergence angle control without requiring motion of each entire unit relative to one another.

SUMMARY OF THE INVENTION

To solve the foregoing problems and address the identified need in the art, in one aspect of the present disclosure a stereo imaging system having convergence angle and disparity control is provided, comprising a pair of pivoting folded-parallel-light-channel (FPLC) units arranged to provide a virtual left side view and a virtual right side view of a scene. Each FPLC unit comprises a fixed lens unit adapted to focus reflected light comprising an image of a scene to an image sensor, and a laterally translatable light-redirecting unit comprising a reflector adapted to define a parallel image reflection path to the fixed lens unit via a collimated light beam comprising substantially parallel light beams. The stereo imaging system further includes a disparity-adjusting mechanism adapted to alter a distance between the pair of pivoting FPLC units and a convergence-angle-adjusting mechanism adapted to pivot the pivoting FPLC units.

In embodiments, the disparity-adjusting mechanism comprises a first actuator operatively connected to a cam assembly. In embodiments, the convergence-angle-adjusting mechanism comprises a second actuator adapted to pivot a pair of pivoting housings each respectively carrying a one of the pair of FPLC units.

In embodiments, the reflector defines a planar reflective surface. A concave lens may be disposed between the reflector and an image inlet of each of the pair of FPLC units. This concave lens defines a lens field of view that is the same as a field of view of the fixed lens unit. In alternative embodiments, the reflector defines an arcuate reflective surface. The arcuate reflective surface may be configured to define a reflector field of view that is the same as a field of view of the fixed lens unit. In embodiments, the fixed lens unit defines a wide-angle lens unit. In alternative embodiments, the fixed lens unit defines a telephoto lens unit.

In another aspect, a stereo imaging system having convergence angle and disparity control is provided, comprising a pair of pivoting folded-parallel-light-channel (FPLC) units arranged to provide a virtual left side view and a virtual right side view of a scene. Each FPLC unit comprises a fixed lens unit adapted to focus reflected light comprising an image of a scene to an image sensor and a laterally translatable light-redirecting unit comprising a planar reflector adapted to define a parallel image reflection path to the fixed lens unit via a collimated light beam comprising substantially parallel light beams. The disclosed system further includes a disparity-adjusting mechanism adapted to alter a distance between the pair of pivoting FPLC units and a convergence-angle-adjusting mechanism adapted to pivot the pivoting FPLC units. The disparity-adjusting mechanism and the convergence-angle-adjusting mechanism may be as described above.

In yet another aspect, a stereo imaging system having convergence angle and disparity control is provided, comprising a pair of pivoting folded-parallel-light-channel (FPLC) units arranged to provide a virtual left side view and a virtual right side view of a scene. Each FPLC unit comprises a fixed lens unit adapted to focus reflected light comprising an image of a scene to an image sensor and a laterally translatable light-redirecting unit comprising an arcuate reflector adapted to define a parallel image reflection path to the fixed lens unit via a collimated light beam comprising substantially parallel light beams. The disclosed system further includes a disparity-adjusting mechanism adapted to alter a distance between the pair of pivoting FPLC units and a convergence-angle-adjusting mechanism adapted to pivot the pivoting FPLC units. The disparity-adjusting mechanism and the convergence-angle-adjusting mechanism may be as described above.

These and other embodiments, aspects, advantages, and features of the present invention will be set forth in the description which follows, and in part will become apparent to those of ordinary skill in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims. Unless otherwise indicated, any patent and/or non-patent citations discussed herein are specifically incorporated by reference in their entirety into the present disclosure.

