Patent ID: 7606511

Claim:
An opening and closing device, comprising: a device main body; an opening and closing body pivotally supported by the device main body about a support shaft between a closed position and an open position; and a helical torsion coil spring that urges the opening and closing body positioned at the closed position in the open direction, wherein the helical torsion coil spring is provided and arranged at a position separate from the support shaft, the helical torsion coil spring consisting of: a coil; one end part that extends outward from one end of the coil in a direction tangential to the coil; and an other end part that extends outward from the other end of the coil in a direction tangential to the coil; the coil of the helical torsion coil spring is pivotally held relative to a holding member, which is provided to and arranged on the opening and closing body or the device main body; the one end part of the helical torsion coil spring is movably mated and latched relative to and along a latching slot provided in the holding member, and extends outward from the holding member; the other end part extends outward from one end of the holding member and is movably held relative to a latching means, which is provided to and arranged on the device main body or the opening and closing body; in a state wherein the opening and closing body is positioned at the closed position, the one end part of the helical torsion coil spring pressure contacts one end of the latching slot of the holding member, which urges the opening and closing body in the open direction; and at the approximate angular area where the center of gravity of the opening and closing body goes beyond the support shaft in the open direction when the opening and closing body is pivoted from the closed position in the open direction, the one end part of the helical torsion coil spring separates from one end of the latching slot of the holding member, and the urging of the opening and closing body in the open direction by the helical torsion coil spring ceases until the opening and closing body reaches the open position.