Patent ID: 11392020

Abstract:
An autofocus projection apparatus having focal-length fine adjustment is disclosed. A projection light engine including the same is also disclosed. The autofocus projection apparatus comprises a projection lens system, which comprises a first lens group, a second lens group, an aperture stop, a third lens group and a forth lens group arranged from a long conjugate side to a short conjugate side; a stepper motor, a control board, and a time-of-flight (TOF) distance measurement module; wherein the stepper motor is connected to an inner barrel for enclosing the second group lens through an adjustment level and only moves the second lens group for autofocus adjustment based on projection distances measured by the TOF distance measurement module. A 3D TOF module which includes a modulated flash light emitter and a CMOS camera sensor, can be used for automatic keystone correction as well as autofocus distance detection in the projection light engine.