This invention relates to tilt and height control for chairs or the like, and is particularly directed to providing an adjustment mechanism for varying the tilt of a back support and the height of the back support and a seat in a chair.
U.S. Pat. No. 4,328,943 issued on May 11, 1982, directed to a tilt control mechanism for a chair achieving height variation by suitable activation of a gas cylinder mechanism. The control assembly disclosed in that patent is particularly suited for tilt control in a chair in which the seat and back support together tilt as a unit. The present invention, on the other hand, is directed to tilt and height adjustment in a chair in which only the back support tilts.
The present invention provides such control in a compact mechanism utilizing a gas cylinder actuator having a cam surface thereon and which is pivotally mounted so that the cam surface activates the gas cylinder upon appropriate pivotal movement of the actuator. A blocker plate is also utilized which pivotally moves between one position in which tilting of the back support is prevented and another position in which tilting is permitted. The actuator and blocker plate are coupled together so that pivotal movement of one is accompanied by pivotal movement of the other. This is preferably achieved by use of an activating lever having two terminal portions, one of which is responsible for the pivoting of the gas cylinder actuator and the other of which causes pivoting of the blocker plate.
The compactness of the overall assembly of the present invention is achieved in large part by closely mounting with respect to each other the gas cylinder actuator and the blocker plate, both of which are mounted for pivotal movement about axes substantially perpendicular to each other. Additionally, the prevention of tilting in the chair is achieved by the blocking of a pin carried by the moving tilt mechanism, in this case the pin preferably extending through the spring that biases the back support of the chair in an upright position.
The invention will be more completely understood by reference to the following detailed description of a presently preferred embodiment thereof .