Patent ID: 8721093
Filing Date: 2014-05-13
Classification: G03B

Abstract:
1. A method of automatic focusing of a projecting device, comprising the steps of: a. providing an image light source to project an image onto a plane through a first image lens; b. providing an image sensor to sense the image on the plane through a second image lens; c. moving the second image lens in a predetermined direction of an optical axis for a predetermined distance, and activating the image sensor to sense the image on the plane to get a definition of the image after every movement of the second image lens, and locating the second image lens at a position where the definition is greatest; d. moving the first image lens in a predetermined direction of an optical axis for a predetermined distance, and activating the image sensor to sense the image on the plane to get a definition of the image after every movement of the first image lens, and locating the first image lens at a position where the definition is greatest; wherein the definition of the image defined in the step c and step d is contrast of the image; and wherein the step c further includes the steps of: