Fixed-focus photographing module and focusing device and method thereof

A focusing apparatus, configured to perform a focusing operation on a pre-assembled photographing module, the pre-assembled photographing module comprising a circuit board, a photosensing component assembled in the circuit board, a lens assembly holder disposed on the circuit board and an optical lens assembly pre-assembled to the lens assembly holder, the optical lens assembly being exposed at an exterior of the lens assembly holder, and the optical lens assembly being positioned in a photosensing path of the photosensing component,

• wherein the optical lens assembly is mounted on an outer side of a top end of the lens assembly holder, and wherein the top end of the lens assembly holder has an outer groove, and a glue layer formed between the optical lens assembly and the lens assembly holder directly packages the optical lens assembly in the outer groove of the lens assembly holder,
• wherein the focusing apparatus comprising:
• a computing device, connected to the pre-assembled photographing module to acquire an image captured by the pre-assembled photographing module;
• and
• a focusing mechanism, the focusing mechanism comprising a lens assembly holding apparatus and a photosensing assembly holding apparatus, the lens assembly holding apparatus holding, at a top side of the lens assembly holder of the pre-assembled photographing module, the optical lens assembly, the photosensing assembly holding apparatus being configured to directly or indirectly hold the lens assembly holder, the computing device adjusting a relative position between the optical lens assembly and the lens assembly holder by analyzing the image captured by the pre-assembled photographing module, to adjust a relative position between the optical lens assembly and a photosensing chip, so that the pre-assembled photographing module outputting a required clear image to complete the focusing operation.