Patent attributes
For each air cell, air is supplied and discharged through one of three lines independent of one another, every third cell being connected to the common line. The control unit controls inflation and deflation of air cells in turn in such an alternate manner that first the pressure of air in the air cells on the first line is increased and decreased, secondly the pressure of air in the air cells on the second line is increased and decreased, then the pressure of air in the air cells on the third line is increased and decreased. Thereafter, when the back tilt angle of the back bottom has reached a predetermined angle or greater, the control unit increases the pressure of air cells whose pressure is being lowered at that moment so as to produce an inflated mode similar to that of the other air cells. Then, while the back bottom is being raised, the control unit performs an inflation and deflation control of individual lines alternately on a cycle shorter than that in a normal control mode. With this arrangement, it is possible to prevent shrinkage of the air mattress in the bed longitudinal direction, prevent the bed user from sliding on the bed, and further prevent the bed user from getting bedsores.
