Locking device

摘要

A locking device (38) for locking a hollow longitudinally extending tubular roller (12) of a shade (16) of an architectural covering (1) releasably in any unwound position of the shade. The locking device (3 8) comprises the roller (12), a center shaft (28) concentrically arranged within the roller and a return spring (32), capable of being operatively interposed between said roller (12) and said center shaft (28), for biasing said roller (12) towards a fully wound position of said shade (16). It also comprises a disc (42) rotatably mounted on said center shaft (28) radially adjacent a first portion (12A) of the length of a circumferential inner surface of said roller (12) and a plurality of detent projections (82, 86) integrally formed on a second portion (12B) of the length of the inner surface of said roller (12). A cam member (44) is mounted on said center shaft (28), so as to be able to carry out sliding movement transversely, preferably laterally, of said center shaft (28), between two end positions. The cam member (44) has a lateral cam projection (70, 90) for engaging said detent projections (82, 86). Friction means (47, 48, 49) are provided between said disc (42) and said roller (12), for yieldingly engaging said disc (42) to rotate with said roller (12) in either of two opposite rotational directions. The friction means includes a cylindrical cavity (47) housing a coaxially-extending compression spring (48) and a ball (49), radially outwardly of said compression spring; said ball being biased against, and frictionally engaging, said first portion (12A) of the inner surface of said roller (12). The disc (42) has a face (51) that confronts said cam member (44) and is provided with a guide track (52) forming a closed loop in the face of the disc and the cam member (44) is provided with a pawl (74) engaged in said guide track (52) to move said cam member (44) between said two end positions in response to changes in rotational direction of said roller.