Projection apparatus and auto-focus method

Abstract

A projection apparatus including a projection module, a projection lens, an actuator, a distance sensor and a controller is provided. The projection module is adapted to project an image beam onto a projection surface to generate a projection image. The projection lens is disposed on a transmission path of the image beam. The actuator is connected to the projection lens and configured to adjust a focal length of the projection lens. The distance sensor is configured to sense a projection distance between the projection apparatus and the projection surface. The controller is electrically connected to the projection module, the actuator and the distance sensor, and is configured to adjust the focal length of the projection lens according to a look-up table and the projection distance sensed by the distance sensor, so as to perform automatic focusing. The lookup table includes a plurality of focal-length segments. The focal length falls within one of the focal-length segments. After confirming an end of a focus adjustment phase, the controller updates a minimum value and a maximum value of the one of the focal-length segments. An auto-focus method is also provided.

Dependencies are inferred from the claim text.