Patent ID: 7758114
Filing Date: 2010-07-20
Classification: B60N

Abstract:
1. A structure of seat back of vehicle seat in combination with a headrest, wherein said headrest has at least one stay portion and is displaceable between a home position where the headrest normally supports a head of a seat occupant on the vehicle seat and an upwardly displaced point to which the headrest is to be displaced upwardly from said home position, said structure of seat back of vehicle seat comprising: a seat back frame including: an upper frame member defined upwardly of the seat back; and a pair of lateral frame members extending downwardly from said upper frame member, a pair of rotating links, each having an end portion and a pivotal point, said pair of rotating links being pivotally connected, at the respective pivotal points thereof, with said pair of lateral frame members of said seat back frame, respectively; a support shaft rotatably connected between said end portion of one of said pair of rotating links and said end portion of another of said pair of rotating links, such that clockwise and anticlockwise rotation of said pair of rotating links relative to the respective two pivotal points thereof causes vertical displacement of said support shaft along an arcuate path; at least one holder bracket of a substantially cylindrical configuration, and said at least one holder bracket being integrally provided to said support shaft, said at least one stay portion of said headrest being inserted and retained in said at least one holder bracket, at least one guide element fixed on said upper frame member of said seat back frame, said at least one guide element being so formed that said at least one holder bracket is slidingly inserted therein so as to be inclinable relative thereto, with such an arrangement that, upon anticlockwise rotation of said pair of rotating links relative to the respective two pivotal points thereof, said at least one holder bracket is moved through said guide element in a direction upwardly of said seat back frame, so that said headrest is displaced to said upwardly displaced point, while being inclined relative to said guide element in a direction forwardly of said seat back frame; a pressure receiving element including a first pressure-receiving region for receiving a load applied from a lumbar part of seat occupant and a second pressure-receiving region for receiving a load applied from a dorsal part of said seat occupant, wherein said first and second pressure-receiving regions are defined integrally with each other in said pressure-receiving element; said pressure receiving element being connected with said support shaft and disposed in said seat back frame so as to extend along a vertical direction of said seat back frame; a crank element rotatably connected between said pair of lateral frame members of said seat back frame so as to be rotatable in a direction backwardly and upwardly of the seat back frame; said crank element being movably connected with said pressure receiving element; and a biasing means having a predetermined biasing force, said biasing means being adapted for normally biasing said headrest to said home position, wherein, in case of a rear-end collision, upon a load in excess of said predetermined biasing force being applied from said lumbar and dorsal parts in a direction backwardly of the seat back to said pressure receiving element under inertia of said seat occupant, said pressure receiving element is displaced in a direction upwardly of the seat back frame, with simultaneous backward and upward rotation of said crank element, thereby causing upward displacement of said support shaft and simultaneous anticlockwise rotation of said pair of rotating links relative to the respective two pivotal points thereof, thus resulting in said headrest being displaced in a direction from said home position towards said upwardly displaced point.