A seat back recliner is revealed. A seat back is pivotally connected to and positioned on a rear end of a seat part of a chair while a cylinder is disposed between the seat part and the seat back. A reclined angle of the seat back is adjustable under control of the cylinder. Thereby a user sitting on the chair can directly adjust the seat back to the reclined angle required. The reclined seat back allows a user to lie back and have the greatest level of comfort and relaxation while sitting on the chair.

A theater chair comprises a flip-up/flip-down seat, a reclining backrest, and a reclining seat. An actuator is operatively connected to the reclining backrest for moving the backrest and seat from a normal or default upright position to any one of a multitude of reclined positions. The flip-up/flip-down seat is provided with a spring for returning the seat to its upright position when the seat is unoccupied. A sensor is operatively associated with the seat so as to effectively monitor the orientation of the seat. When the seat is vacated, the sensor will detect movement of the seat and send an appropriate signal to a control circuit which is operatively connected to the actuator. After a predetermined period of time, the actuator will be actuated so as to return the backrest from the reclined position to the default upright position.