Patent ID: 8544525

Claim:
A bidirectionally operable/switchable pull cord mechanism for a window shade comprising a frame ( 1 ), a shade ( 2 ), a shade driving mechanism ( 3 ), and an endless bead chain or pull cord ( 4 ) for driving the shade driving mechanism ( 3 ), with the shade driving mechanism ( 3 ) fixed to the frame ( 1 ) and driving the shade ( 2 ) to release/wind or to move in a horizontal direction, with a barrel ( 5 ) mounted to the frame ( 1 ) at a location corresponding to the bead chain or pull cord ( 4 ), with the barrel ( 5 ) including a peripheral wall having a slit ( 6 ) extending in an axial direction, with a sliding block ( 7 ) slideably received in the barrel ( 5 ), with a handle ( 8 ) mounted outside of the barrel ( 5 ), with the sliding block ( 7 ) connected to the handle ( 8 ) by a link ( 9 ) extending through the slit ( 6 ), with the bead chain or pull cord ( 4 ) received in the barrel ( 5 ), with a fixed pulley ( 10 ) mounted to an end of the barrel ( 5 ), with the bead chain or pull cord ( 4 ) wound around the fixed pulley ( 10 ), with the sliding block ( 7 ) including a passageway ( 11 ) in an intermediate portion thereof, with a follower device ( 12 ) mounted in the passageway ( 11 ), with the sliding block ( 7 ) connected by the follower device ( 12 ) to a section ( 4 a ) of the bead chain or pull cord ( 4 ) extending through the passageway ( 11 ), with the follower device ( 12 ) including a pivotal plate ( 12 a ), a gear ( 12 b ), and a positioning block ( 12 c ), with the pivotal plate ( 12 a ) pivotably supported in the passageway ( 11 ) by a shaft ( 12 d ), with the pivotal plate ( 12 a ) including a rear side ( 12 a 1 ), with the passageway ( 11 ) having a wall ( 11 a ) facing the rear side ( 12 a 1 ) of the pivotal plate ( 12 a ), with a recess defined in one of the rear side ( 12 a 1 ) of the pivotal plate ( 12 a ) and the wall ( 11 a ) of the passageway ( 11 ), with the positioning block ( 12 c ) located between the rear side ( 12 a 1 ) of the pivotal plate ( 12 a ) and the wall ( 11 a ) of the passageway ( 11 ), with the gear ( 12 b ) located between the section ( 4 a ) of the bead chain or pull cord ( 4 ) and a front side ( 12 a 2 ) of the pivotal plate ( 12 a ) opposite to the rear side ( 12 a 1 ).