Invalid bed with lifting mechanism

Claim 1

AN INVALID BED-LIFT APPARATUS COMPRISING A SUB-FRAME ASSEMBLY ADAPTED TO BE MAINTAINED IN A RELATIVELY FIXED POSITION, AN ELONGATED MATTRESS SECTION FOR SUPPORTING AN INVALID THEREON DISPOSED IN OVERLYING RELATIONSHIP TO SAID SUB-FRAME ASSEMBLY, AND MEANS INTERPOSED BETWEEN AND OPERATIVELY CONNECTED WITH SAID SUB-FRAME ASSEMBLY AND SAID MATTRESS SECTION FOR SELECTIVE DISPLACEMENT OF SAID MATTRESS SECTION BETWEEN A HORIZONTALLY DISPOSED POSITION AND A RELATIVELY ELEVATED, HORIZONTALLY DISPOSED POSITION OR A RELATIVELY INCLINED POSITION, SAID MEANS INCLUDES LIFT MEANS CARRIED BY SAID SUB-FRAME ASSEMBLY AND CONNECTED TO SAID MATTRESS SECTION AT A POINT INTERMEDIATE THE ENDS THEREOF FORMING A FULCRUM POINT ABOUT WHICH SAID MATTRESS SECTION MAY ROTATE IN A VERTICAL PLANE AND SELECTIVELY OPERABLE FOR DISPLACEMENT OF SAID FULCRUM POINT IN A VERTICAL PLANE, AND LEVER MEANS INTERCONNECTED BETWEEN SAID SUB-FRAME ASSEMBLY AND SAID MATTRESS SECTION AND LIFT MEANS FOR CONTROLLING THE ROTATION OF SAID MATTRESS SECTION ABOUT SAID FULCRUM POINT IN PREDETERMINED RELATIONSHIP TO VERTICAL DISPLACEMENT OF SAID FULCRUM POINT, SAID LEVER MEANS BEING OPERABLE TO MAINTAIN SAID MATTRESS SECTION HORIZONTALLY DISPOSED DURING VERTICAL DISPLACEMENT OF SAID FULCRUM POINT BY SAID LIFT MEANS BETWEEN A FIRST POSITION AND A RELATIVELY ELEVATED, SECOND POSITION, AND ROTATING SAID MATTRESS SECTION TO AN INCLINED POSITION DURING VERTICAL DISPLACEMENT OF SAID FULCRUM POINT BY SAID LIFT MEANS BETWEEN SAID SECOND POSITION AND A THIRD, FURTHER ELEVATED POSITION.