Patent ID: 7478972

Claim:
A rotational supporting mechanism supporting a main body and a cover so that the main body and the cover are superposed when in a closed position, and, from the closed position, the cover is rotated 180 degrees in a planar direction in which the cover and the main body are superposed and stopped at a 180-degree rotational position when in an open position, the rotational supporting mechanism comprising: an eccentric cam rotating eccentrically about a fixed rotation axis with respect to said planar direction, said eccentric cam having a peripheral cam surface having a recessed portion corresponding to the closed position at one rotational position comprising a maximum eccentricity of the cam surface at a maximum radius from the axis, and a recessed portion corresponding to the open position at another position comprising a minimum eccentricity of the cam surface at a minimum radius from the axis the positions being 180 degrees opposite to each other through the axis of the eccentric cam; and a pressing means configured to press the cam surface of the eccentric cam by setting a pressing direction to the same direction as that of a line connecting both of the portion corresponding to the closed position and the portion corresponding to the open position when the cover is in the closed position, wherein the pressing means applies a spring biased pressing load to the eccentric cam in the pressing direction and applies a pressing force to prevent the eccentric cam from rotating as the cover rotates between the closed position and the open position; wherein the pressing load applied to the eccentric cam and the pressing force to prevent the eccentric cam from rotating are increased to stop rotational movement of the eccentric cam when the pressing means engages the recessed portion corresponding to the closed position on the cam surface, wherein the pressing load applied to the eccentric cam is reduced as the pressing means approaches a side of the recessed portion corresponding to the open position, and the pressing force to prevent the eccentric cam from rotating is increased to stop the rotational movement of the eccentric cam when the pressing means engages the recess portion corresponding to the open position, wherein one of the eccentric cam and pressing means is attached to the main body, while the other of the eccentric cam and pressing means is attached to the cover so that the cover is rotationally supported.