US Patent 9652648 Positioning an object with respect to a target location

Systems and methods are provided for positioning an object with respect to a target location, such as for auto-focusing. One implementation includes a positioning device, which includes a reference object having a plurality of dark-shaded bars arranged in parallel with and separated from each other by spaces equal to a width of each of the bars. The positioning device also includes a motor configured to move in a reciprocating manner and a sensor configured to sense at least one of the bars or spaces. The motor is connected to the reference object or the sensor and moves the reference object or sensor with respect to the other. The motor is configured to stop at a target location in two phases of motion.