Rapid and Precise Zoom Lens Design Based on Voice Coil Motors with Tunnel Magnetoresistance Sensors

Abstract

In response to the zooming delay issue during the transition from a wide-area search to high-resolution target identification in high-magnification zoom lenses, we propose a drive technology based on voice coil motors. The linear motion of the motor is directly converted into the linear movement of the zoom lens group, significantly enhancing the zoom speed. Additionally, we introduce a high-precision closed-loop control technology utilizing a magnetic scale to achieve the rapid and precise positioning of the zoom lens group. The magnetic scale detection technology achieves precise positioning by detecting periodic changes in the magnetic field, working in conjunction with tunnel magnetoresistance sensors. Demonstrated with a 40× zoom lens example, this study elaborates on the motion trajectory planning and structural dimension design process of a voice coil motor, culminating in the assembly of a physical prototype. Practical validation experiments show that the full zoom time of the lens utilizing our technology is less than 0.3 s, where the full zoom time refers to the time required for the lens to zoom from the wide-angle end to the telephoto end. In positioning accuracy test experiments, lenses using our technology achieved a positioning deviation of less than 5 μm.