Seat control means for chair of the tall-cushion type

Claim 1

A CHAIR COMPRISING A CHAIR FRAME HAVING ARM PORTIONS, A BODY-SUPPORTING STRUCTURE COMPRISING A SEAT UNIT AND BACK-REST, SAID SEAT UNIT HAVING A T-CUSHION CONSTRUCTION INCLUDING A PAIR OF LATERALLY-PROJECTING FRONT EXTENSION PORTINS OVERYLING THE FORWARD EDGES OF THE CHAIR FRAME ARM PORTIONS, PIVOT MEANS MOUNTING THE FORWARD PORTION OF THE SEAT UNIT ON THE CHAIR FRAME FOR TILTING MOVEMENT WITHOUT REARWARD DISPLACEMENT FROM AND UPRIGHT SITTING POSITION TO A TILTED SITTING POSITION WITH THE FRONT END OF THE SEAT RISING RELATIVE TO THE CHAIR FRAME AND THE REAR OF THE SEAT DROPPING RELATIVE TO THE CHAIR FRAME, AND CONTROL MEANS MOUNTING THE REAR PORTION OF THE SEAT UNIT ON THE CHAIR FRAME AND RESTRAINING THE BODYSUPPORTING STRUCTURE FROM TILTING MOVEMENT ABOUT SAID PIVOT MEANS IN THE UPRIGHT SITTING POSITION, SAID CONTROL MEANS INCLUDING A PAIR OF LINKS CONNECTED END-TO-END AT A KNEE PIVOT, ONE OF SAID LINKS BEING PIVOTALLY MOUNTED ON THE SUPPORT FRAME AND OTHER OF SAID LINKS BEING PIVOTALLY CONNECTED TO THE REAR PORTION OF THE BODY-SUPPORTING STRUCTURE, THE PAIR OF LINKS BEING SUBSTANTIALLY IN AXIAL ALIGNMENT IN THE UPRIGHT SITTING POSITION TO SUPPORT THE REAR PORTION OF THE BODY-SUPPORTING STRUCTURE, AND ACTUATING MEANS INDEPENDENT OF SAID LINKS AND SEAT UNIT FOR MOVING SAID LINKS OUT OF AXIAL ALIGNMENT TO INITATE MOVEMENT OF THE BODY-SUPPORTING STRUCTURE TO THE TILTED SITTING POSITION, THE PAIR OF LINKS TURNING RELATIVE TO EACH OTHER AT THEIR KNEE PIVOT TO DECREASE THE DISTANCE BETWEEN SAID PIVOTAL MOUNT AND THE PIVOTAL CONNECTION WITH THE BODY-SUPPORTING STRUCTURE WHEREBY TO PERMIT THE REAR PORTION OF THE LATTER TO DROP AS THE BODY-SUPPORTING STRUCTURE TURNS ABOUT SAID PIVOT MEANS WITHOUT REARWARD DISPLACEMENT RELATIVE TO THE CHAIR FRAME, WHEREBY THE SEAT UNIT FRONT EXTENSION PORTIONS MOVE ALONG THE FORWARD EDGES OF THE ARM PORTIONS WITHOUT ENGAGING THE LATTER.