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US 5,297,021 AGranted
Zero shear recliner/tilt wheelchair seat
OwnerJames M. Koerlin, J. Leslie Tauszinventors
Life of this patent
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Abstract
A wheelchair seat has a backrest assembly with a counter balance to provide equilibrium. A control loop is included on the sliding backrest to sense the onset of shear and compensate the backrest to a zero shear position during recline. A legrest assembly has a selectable lift arrangement for either independent or recline lift.
Claims7
A reclining back assembly for a user comprising:
- a pivotable backplate assembly support rail;
- a carriage slidably affixed to said support rail;
- a backrest affixed to said carriage;
- means for reclining said pivotable backplate assembly support rail;
- means for sensing shear during recline;
- and
- means for closed loop control responsive to the means for sensing shear during recline to eliminate said shear by moving said carriage.
4 more elements
A process of eliminating shear in a reclining back assembly having a movable backrest comprising the steps of:
- (a) receiving a recline angle input of the reclining back assembly from a recline angle sensor;
- (b) computing a calibrated backrest force without shear at the recline angle received from the recline angle sensor;
- (c) sensing a backrest force including shear;
- (d) comparing (c) to (d), and if c=d, then do nothing, and if b>c, then moving the backrest down until b=c, and if b<c, then moving the backrest up until b=c.
1 more element
Dependencies are inferred from the claim text.