Conveyance seat

1 . A conveyance seat, comprising:

a seat back frame;

a skin material covering the seat back frame;

a movable body arranged between the seat back frame and the skin material and protruding forward with respect to the seat back frame; and

a control device controlling movement of the movable body, wherein

the movable body has

right and left first movable bodies arranged at upper parts of the seat back frame, and

a second movable body arranged below the first movable bodies in the seat back frame,

each of the first movable bodies is a shoulder movable body configured to support a shoulder of a seated occupant, the shoulder movable body including an inflatable and deflatable shoulder fluid bag,

the second movable body is a lumbar movable body configured to support a waist of the seated occupant, the lumbar movable body including an inflatable and deflatable lumbar fluid bag, and

the control device:

acquires pressure signals related to pressure applied to the shoulder fluid bag and the lumbar fluid bag,

determines a seating posture of the seated occupant by comparing determination conditions for determining the sitting posture of the seated occupant with the pressure signals, and

based on a determination result of the seating posture, inflates one of the shoulder fluid bag and the lumbar fluid bag that corresponds to a part of the seated occupant that is bent forward in the seating posture, and

deflates the other of the shoulder fluid bag and the lumbar fluid bag based on an amount of inflation of the one of the shoulder fluid bag and the lumbar fluid bag.

2 . The conveyance seat according to claim 1 , wherein

the control device performs control based on the pressure signal so as to limit the amount of protrusion of the bag body.

3 . The conveyance seat according to claim 1 , wherein the control device acquires a steering angle signal related to a steering angle of a conveyance and controls the amount of protrusion of the movable body in real time based on the steering angle signal.

4 . The conveyance seat according to claim 1 , wherein the first movable bodies have inside first movable bodies arranged on both the right and left sides of the seat back frame in the seat width direction and right and left outside first movable bodies arranged at positions outside the inside first movable bodies in the seat width direction.

5 . The conveyance seat according to claim 1 , wherein

the seat back frame has

right and left lower side frames extending in the up to down direction,

right and left upper side frames attached to respective upper end portions of the right and left lower side frames and pivotable in the front to back direction with respect to the lower side frames, and

an upper frame connecting the upper side frames, and

at least a portion of the first movable body is arranged at a position between the right and left upper side frames in the seat width direction.

6 . The conveyance seat according to claim 5 , comprising a seat cushion frame, wherein

the seat back frame is attached to a rear end portion of the seat cushion frame and is pivotable in the front to back direction with respect to the seat cushion frame, and

the control device acquires a first pivoting angle signal related to a pivoting angle of the seat back frame with respect to the seat cushion frame and a second pivoting angle signal related to a pivoting angle of the upper side frame with respect to the lower side frame and controls the amount of protrusion of the movable body based on the first pivoting angle signal and the second pivoting angle signal.

7 . The conveyance seat according to claim 1 , comprising a lifting and lowering mechanism supporting the first movable body to be capable of ascending and descending in the up to down direction with respect to the seat back frame.

8 . The conveyance seat according to claim 7 , wherein

the lifting and lowering mechanism supports the second movable body to be capable of ascending and descending in the up to down direction with respect to the seat back frame, and

the control device controls the lifting and lowering mechanism so as to lift and lower the first movable body to correspond to a position of the second movable body in the up to down direction.

9 . The conveyance seat according to claim 1 , wherein

the movable body has right and left third movable bodies arranged at positions between the first and second movable bodies in the up to down direction of the seat back frame, the third movable body has a plurality of inflatable and deflatable bag bodies, and

the plurality of bag bodies are stacked, have mutually different sizes, and are disposed in mutually different directions.

10 . The conveyance seat according to claim 1 , wherein

the control device inflates the shoulder fluid bag and deflates the lumbar fluid bag in a case where it is determined that the seating posture of the seated occupant is stooped back.

11 . The conveyance seat according to claim 1 , wherein

the control device inflates the lumbar fluid bag and deflates the shoulder fluid bag in a case where it is determined that the seating posture of the seated occupant is curved back.