Patent ID: 8514558

Claim:
A hinge assembly coupled between a first plate and a second plate of a portable device, comprising: a base element; a first rotation element comprising a first rotational axle, which is coupled to the first plate and is rotatably coupled to the base element, and a first gear coupled to the first rotational axle; a second rotation element comprising a second rotational axle, which is coupled to the second plate and is rotatably coupled to the base element, and a second gear coupled to the second rotational axle; a power transfer gear rotatably coupled to the base element and arranged to transfer rotation torque between the first gear and the second gear such that the first gear rotates in a same direction as the second gear; and an elastic module to restrict rotation of the base element relative to the first rotation element, wherein rotation of the hinge assembly causes a vertical arrangement between the first plate and the second plate to vary while maintaining a parallel arrangement of the first plate and the second plate.