Adjustable height mechanism for a collapsible support frame

摘要

An adjustable height mechanism for use in devices employing a collapsible scissors frame supporting an object is disclosed having a pair of pawls secured to the sliding leg of the scissors frame and slidably mounted onto a pair of guide rails. A central channel is positioned between the guide rails and receives a guide member extending from the leg to provide additional tracking and lateral stability during movement of the leg. A pair of spring biased, pivoting ratchet arms are mounted to the supported object and include a series of ratchet stops and a finger grip. The ratchet arms engage the pawls to restrict movement of the leg of the scissors frame in one direction while allowing ratcheting free movement in the opposite direction. The finger grips can be used by the user to squeeze the free ends of the arms together and release the ratcheting engagement with the pawls to provide height adjustment of the object supported by the scissors frame.