Patent ID: 7814619

Claim:
An opening and closing device comprising: a roughly cylindrical stator; a pair of stator cam profiles formed at an end of the stator parallel to a central axis of the stator, the stator cam profiles radially opposing each other; a roughly ring-like rotor sharing the central axis with the stator, the rotor having a substantially planar axial surface proximal to the stator and a substantially planar axial surface distal to the stator, the rotor further having an inner circumferential surface that defines an axial space; the rotor being rotatable relative to the stator and movable along the central axis; a pair of rotor cams protruding orthogonally from the inner circumferential surface of the rotor toward the central axis of the stator; and a spring pushing the rotor against the stator, the spring resiliently contacting the distal axial surface of the rotor; wherein the spring pushes each of the pair of rotor cams against each of the pair of stator cam profiles, at least a part of the stator is movable into the axial space defined by the inner circumferential surface of the rotor, and a diameter of the axial space of the rotor is larger than an outer diameter of the stator, a side face of the rotor cams contacting the stator cam profiles is round, each of the rotor cams reciprocally slides on the pair of stator cam profiles, and each stator cam profile is a concavo-convex cam profile configured by continuously forming a projecting portion, a first tilting portion and a second tilting portion extending from the projecting portion to both sides in a circumference direction, a third tilting portion extending from the second tilting portion, and a first concave portion extending from the third tilting portion, and a projecting surface of the first tilting portion of one of the pair of stator cam profiles and a surface of the first concave portion of the other of the pair of stator cam profiles are aligned along an axis which is parallel to the central axis of the stator, wherein at a point in the rotation of the rotor relative to the stator, at least a part of the pair of stator cam profiles extends through the axial space of the rotor from the proximal axial surface to the distal axial surface.