Abstract: A hinge has a central element and a surrounding element. One of the central element and the surrounding element is formed by injection molding, and the other element is then formed on the priorly-formed element by injection molding such that a limit segment is mounted around the neck segment having a smallest outer width of the central element, which keeps the surrounding element from departing from the central element, and further simplifies a structure of the hinge. Because a melting point of the element formed priorly is higher than a melting point of the element formed later, the element formed later does not attach to the element formed priorly, and the two elements are relatively rotatable. Finally, because the manufacture of the hinge is accomplished after injection molding twice, the process of manufacturing the hinge is more convenient, faster and lowers the cost.

Abstract: A rotatable seat for a sucker has a stationary plate and a rotating plate. When in used, the stationary plate is attached to the platform of the car by tape or other ways. Because an outside surface of the rotating plate is smooth, the assistant device can be attached to the smooth outside surface easily and securely by sucker. Then the assistant device is connected securely to the platform. Because a mounting segment of the rotating plate is mounted in a mounting hole of the stationary plate, and multiple outside positioning segments on the mounting segment engage with multiple inside positioning segments on the mounting hole, the rotating plate and the stationary plate are relatively rotatable, and are selectively held at specific angles. Thus, the assistant device can be adjusted to a fine visual angle for the user on the passenger seat or the rear seat.

Abstract: A manufacturing method for a hinge has steps of forming one of a central element and a surrounding element by injection molding, cooling down the formed element, and forming the other element on the priorly-formed element by injection molding such that a limit segment of the surrounding element is mounted around the neck segment, which keeps the surrounding element from departing axially from the central element, and further simplifies a structure of the hinge. Because a melting point of the element formed priorly is higher than a melting point of the element formed later, the element formed later does not attach to the element formed priorly. Therefore, the two elements are relatively rotatable. Finally, because a manufacturing process is accomplished after injection molding twice, the process is more convenient and faster, and the cost is lowered.

Abstract: A hinge has a central element and a surrounding element. One of the central element and the surrounding element is formed by injection molding, and the other element is then formed on the priorly-formed element by injection molding such that a limit segment is mounted around the neck segment having a smallest outer width of the central element, which keeps the surrounding element from departing from the central element, and further simplifies a structure of the hinge. Because a melting point of the element formed priorly is higher than a melting point of the element formed later, the element formed later does not attach to the element formed priorly, and the two elements are relatively rotatable. Finally, because the manufacture of the hinge is accomplished after injection molding twice, the process of manufacturing the hinge is more convenient, faster and lowers the cost.