Abstract: A rotation hinge configured in a portable electrical device includes a tube sequentially stringing a base coupled to a main housing of the portable electrical device, a cam module and a fixing plate coupled to a sub-housing of the portable electrical device, and engaging with a riveting plate. The cam module has a designed curve surface and at least two recesses positioned thereon. Each section of the designed curve surface between the recesses has an arc-shape projection portion. Each recess of the designed curve surface contacts an elastic sliding portion. While the cam module rotates, the elastic sliding portion moves from the recess and moves along the designed curve surface. While the elastic sliding portion contacts the arc-shape projection portion, a compression force stored in the elastic sliding portion is maximized. Therefore, the sub-housing is advanced to rotate by the elastic sliding portion releasing the compression force.

Abstract: A rotation hinge configured in a portable electrical device includes a tube sequentially stringing a base coupled to a main housing of the portable electrical device, a cam module and a fixing plate coupled to a sub-housing of the portable electrical device, and engaging with a riveting plate. The cam module has a designed curve surface and at least two recesses positioned thereon. Each section of the designed curve surface between the recesses has an arc-shape projection portion. Each recess of the designed curve surface contacts an elastic sliding portion. While the cam module rotates, the elastic sliding portion moves from the recess and moves along the designed curve surface. While the elastic sliding portion contacts the arc-shape projection portion, a compression force stored in the elastic sliding portion is maximized. Therefore, the sub-housing is advanced to rotate by the elastic sliding portion releasing the compression force.