Patent ID: 7487699

Claim:
A screw fastening device comprising a device body from which a stationary base extends frontward, a screw-driving tool arranged in the device body and extending into the stationary base, a guide block threadingly fixed to an inside surface, a movable base coupled to and extending outside the stationary base and movable with respect to the stationary base, a positioner fixed to a front end of the movable base, a guide rail extending from a bottom of the movable base, a screw-guiding transmission device arranged at a location inside the movable base, and a guiding and holding device mounted inside the positioner, wherein the guide rail has a front surface that is recessed to form a guide chute and characterized in that the guide rail is provided at the bottom of the movable base and integrally formed with the movable base and has a curved configuration, the guide chute being extended upwardly and in a curved configuration from a lower end to the screw-guiding transmission device inside the movable base, and wherein the guide rail comprises an upper rail member and a lower rail member that are pivoted to each other by means of a lower pivot pin of the upper rail member and a pivoting portion of the lower rail member, a spring being arranged between the lower pivot pin and the pivoting portion to provide a spring force to thereby provide the lower rail member with a resilient returning force so that the lower rail member is moveable frontward when getting into contact with a rechargeable battery of the device to ensure proper movement of a screw strip in the guide chute, whereby a screw strip can be inserted from a lower end of the guide rail into the guide chute and directly extending upward to a chamber defined in the movable base to move the screw strip to a predetermined position, and whereby screws remain in the screw strip are guided by the guide rail to space from a target object to protect the target object from being damaged by being undesirably hit by the screws.