To achieve the above objective, the present invention provides the following technical solution: a handheld magnifier with an adjustable
focal length, comprising an upper shell and a lower shell. The upper shell is equipped with a protection plate, a display screen, and a
silicone key, while the lower shell contains a PVC film. A battery, a keyboard, a main board, a wave wheel, a sector gear, a lens
assembly, and a light board are installed between the upper and lower shells. The lens
assembly consists of an FPC cable, a
chip, a guide fixing seat, a roller, a lens holder, a lens cover, and a
glass sheet. Manual precise focusing is achieved through a
mechanical transmission structure consisting of a wave wheel, sector gear, and spiral groove. This structure provides a wide adjustable range of
clarity to accommodate observation needs at different distances.