Headrest device for a vehicle seat

A headrest device which is mountable to a stay means extending from the top of a backrest of a vehicle seat, said headrest comprising the following elements, the terms vertical, horizontal, upper and lower being used on the assumption that the headrest is attached to the stay means extending from the backrest of the vehicle seat when the backrest is in its essentially vertical orientation,

• a stationary frame portion, said stationary frame portion including (a) first and second spaced apart plates fixedly attachable to said stay means so as to be vertically oriented, said first and second plates having corresponding elongated openings therein whose elongated dimensions are vertically oriented and said first and second plates defining facing inner sides and non-facing outer sides, and (b) at least one upper guide projection and at least one lower guide projection extending away from the outer sides of each of the first and second plates from respective points above and below the elongated openings therein,
• a movable frame portion, said movable frame portion including (a) first and second spaced apart side panels which are respectively positioned adjacent the outer sides of said first and second plates, each of said first and second side panels including a horizontal upper guide groove through which at least one upper guide projection from the associated plate extends, a horizontal lower guide groove through which at least one lower guide projection from the associated plate extends, and a hole located between the upper and lower guide grooves, and (b) a central panel extending between said first and second side panels,
• a braking mechanism, said braking mechanism including (a) an outer case fixedly secured to the first side panel of said movable frame portion so as to cover the hole therein, said outer case including an aperture therein and an inner peripheral surface, (b) an inner case rotatably positioned within said outer case, said inner case defining two engagement edges and including an operating shaft which projects toward the hole in said first end panel and an actuating shaft which extends through the aperture in said outer case, and (c) a coil spring positioned between said inner case and said outer case, said coil spring having engagement portions at its opposite ends which are adapted to contact a corresponding engagement edge of said inner case so as to allow the coil spring to be brought in pressure contact with the inner peripheral surface of said outer case, and
• an eccentric cam mechanism which is capable of moving said movable frame portion forward and backward with respect to said stationary frame portion, said eccentric cam mechanism including (a) first and second disc elements which are respectively located within the elongated openings in said first and second plates, (b) a connecting tube extending between said first and second disc elements, (c) a first support arm connected to said first disc element, said first support arm including a base which is rotatably positioned in the hole in said first panel, and (d) a second support arm connected to said second disc and having a free end which is rotatably positioned in the hole in said second side panel.