Seat cushion

Claim 1

A SEAT CUSHION FOR PROVIDING RELIEF FROM PRESSURE AT THE BASE OF THE SPINE OF A PERSON SITTING ON SAID CUSHION AND USABLE ON A CHAIR OR THE LIKE HAVING A BACK PORTION AND A SOFT SEAT SURFACE OR AN IRREGULAR HARD SEAT SURFACE COMPRISING: A RESILIENT CUSHIONING ELEMENT, A RECESS IN SAID CUSHIONING ELEMENT LOCATED IN A POSITION TO UNDERLIE THE BASE OF SAID SPINE, A RIGID BOARD-LIKE ELEMENT, MEANS FOR SELECTIVELY MAINTAINING SAID RIGID BOARD-LIKE ELEMENT IN UNDERLYING RELATIONSHIP RELATIVE TO SAID RESILIENT CUSHIONING ELEMENT TO LEND RIGIDITY THERETO WHEN SAID SEAT CUSHION IS LOCATED ON SAID SOFT SEAT SURFACE TO THEREBY PREVENT SAID SEAT CUSHION FROM SINKING INTO SAID SOFT SEAT SURFACE TO AN EXTENT WHICH WOULD PERMIT SAID SOFT SEAT SURFACE TO EFFECTIVELY EXERT PRESSURE ON THE BASE OF SAID SPINE THROUGH SAID RECESS, SAID MEANS FOR SELECTIVELY MAINTAINING SAID RIGID BOARD-LIKE ELEMENT IN UNDERLYING RELATIONSHIP RELATIVE TO SAID RESILIENT ELEMENT INCLUDING MEANS FOR PERMITTING SELECTIVE REMOVAL OF SIAD RIGID BOARD-LIKE ELEMENT FROM UNDERLYING RELATIONSHIP RELATIVE TO SAID RESILIENT CUSHIONING ELEMENT TO THEREBY PERMIT SAID RESILIENT CUSHIONING ELEMENT TO ADAPT ITSELF TO THE CONTOUR OF SAID IRREGULAR HARD SEAT SURFACE AND THEREFORE BE FIRMLY SUPPORTED THEREBY, BACKREST MEANS HAVING A REAR SURFACE FOR ENGAGING THE BACK PORTION OF SAID CHAIR AND A FRONT SURFACE FOR CRADLING THE LUMBAR REGION OF A PERSON''S BACK, AND MEANS FOR ATTACHING SAID BACKREST PORTION RELATIVE TO SAID RESILIENT CUSHIONING ELEMENT TO THEREBY CAUSE SAID BACKREST PORTION TO PREVENT BOTH FORE AND AFT MOVEMENT AND LATERAL MOVEMENT OF SAID SEAT CUSHION WHEN SAID BACKREST PORTION IS HELD BETWEEN A PERSON''S BACK AND THE BACK PORTION OF SAID CHAIR AND SAID SEAT CUSHION IS LOCATED ON EITHER SAID SOFT SURFACE OR SAID IRREGULAR HARD SEAT SURFACE TO THEREBY TEND TO PREVENT SAID RECESSED PORTION OF SAID RESILIENT CUSHIONING ELEMENT FROM MOVING OUT OF UNDERLYING RELATIONSHIP WITH THE BASE OF SAID SPINE.