Abstract: A lower inertial compact disk driving device is disclosed. The disk and laser head are static and optical unit device are used as a medium of the laser optical path. Furthermore, a rough tracing unit device is used to change the optical path projected by optical unit device on the compact disk, a precise tracing unit device is used to control the optical spot to emit to the desired compact disk track precisely; the precise tracing unit device includes two fixed shelves, two permanent magnets, a tracing movable block and a balance movable block, the tracing movable block and balance movable block are wound around focus coils, respectively, and are hung between two fixed shelves by elastic wire, the central thereof is installed with the steel wire whose end connects to the optical unit device. The focusing error from the laser beam passing through the optical unit device is converted into a focusing driving voltage which is applied to the focus coil so that a magnetic field is generated.

Abstract: A stopping device for tape measures, consisting of a lower housing, a locking button, a spring, a tape roller and an upper housing, arranged in such a way that when the locking button is pushed upwards, the lower part of the stopping spring is released from the outer stopping rim of the tape roller which allows the tape to be retracted automatically using the tension of the helical spring of the tape roller, and releasing the locking button allows the tension of the helical spring to return to its initial position, thereby pressing against the outer stopping rim on one side of the tape roller and providing the mechanism for stopping it.