Convertible hospital bed-chair

Claim 1

MATTRESS SPRING FRAME STRUCTURE FOR A HOSPITAL BED AND CONVERTIBLE TO A CHAIR COMPRISING A PIVOTABLE SUPPORT BASE SECURED TO A BEDSTEAD FRAME WITH THE BASE BEING ROTATABLE ABOUT AN AXIS NORMAL TO THE FRAME, A SPRING FRAME HEAD SECTION PIVOTALLY CONNECTED TO SAID BASE, A SPRING FRAME CENTRAL SECTION PIVOTALLY CONNECTED TO SAID BASE AND EXTENDING GENERALLY AWAY FROM SAID HEAD SECTION, A SPRING FRAME FOOT SECTION PIVOTALLY CONNECTED TO SAID CENTRAL SECTION, MEANS FOR RELEASABLY LOCKING SAID FOOT AND CENTRAL SECTIONS AGAINST ROTATION IN ONE DIRECTION RELATIVE TO ONE ANOTHER, A PAIR OF SUPPORT ARMS PIVOTALLY SECURED ADJACENT OPPOSITE SIDES OF SAID BASE AND SLIDABLY ENGAGING SPACED SIDE PORTIONS OF SAID HEAD SECTION IN SUPPORTING RELATION THERETO, MEANS FOR RELATIVELY PIVOTING SAID SUPPORT ARMS TO EFFECT ROTATION OF SAID HEAD SECTION, MEANS FOR SELECTIVELY LOCKING SAID HEAD SECTION AT DIFFERENT POSITIONS THROUGHOUT ITS ROTATION, A SECOND PAIR OF SUPPORT ARMS PIVOTALLY SECURED ADJACENT OPPOSITE SIDES OF SAID BASE AND SLIDABLY ENGAGING SPACED SIDE PORTION OF SAID CENTRAL SECTION, MEANS FOR SELECTIVELY PIVOTING SAID SECOND SUPPORT ARMS TO EFFECT ROTATION OF SAID CENTRAL SECTION, MEANS FOR SELECTIVELY LOCKING SAID CENTRAL SECTION AT POSITIONS THROUGHOUT ITS ROTATION, MEANS FOR SELECTIVELY LOCKING SAID FOOT SECTION AT VARIOUS POSITIONS THROUGHOUT ITS ROTATION, AND MEANS FOR SELECTIVELY POSITIONING SAID LAST NAMED MEANS IN UNOBSTRUCTING RELATION TO ROTATIONAL MOVEMENT OF SAID PIVOTABLE BASE ON SAID BED STEAD.