Patent ID: 7488035

Claim:
An automobile seat, comprising: a seat cushion frame for a seat cushion; a pair of side frames tiltably mounted with respect to said seat cushion frame; a seat back frame mounted on said pair of side frames so as to be rockable within a limited range of angles, said seat back frame having a head rest mounted on an upper portion thereof; a seat back frame holding device that is operable to elastically hold said seat back frame in an original position with respect to said pair of side frames; and a seat back frame rocking mechanism for causing, when an acceleration greater than a predetermined value is imparted to said automobile seat from behind said automobile seat, said seat back frame to undergo a rocking motion in which said seat back frame holding device releases said seat back frame from said original position and said seat back frame rocks with respect to said pair of side frames; wherein said seat back frame rocking mechanism includes a rocking motion preventing member rotatable mounted to one of said pair of side frames and spaced apart from said seat back frame holding device, said rocking motion preventing member (1) preventing said seat back frame from undergoing the rocking motion when the acceleration greater than the predetermined value is not inputted from behind said automobile seat and (2) preventing said seat back frame from undergoing the rocking motion and said seat back frame holding device from releasing said seat back frame so as to prevent erroneous operation in the absence of the acceleration greater than the predetermined value when said pair of side frames are tilted to be inclined rearwardly and a load is applied to said seat back frame; wherein said rocking motion preventing member comprises a rotatable base, an inertial portion that extends radially outwardly from said base, and a stopper that restricts said seat back frame from undergoing the rocking motion by contacting a lower end portion of said seat back frame, such that when the acceleration greater than the predetermined value is inputted from behind said automobile seat, said rocking motion preventing member rotates due to inertial force of said inertial portion to release said stopper from restricting said seat back frame from undergoing the rocking motion; and wherein said rocking motion preventing member has said rotatable base, said inertial portion and said stopper mounted together to rotate about a common center of rotation when the acceleration greater than the predetermined value is inputted from behind said automobile seat.