Control mechanism for screen rollers
OwnerAnders Sandsborginventor
Life of this patent
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Abstract
A spring roller-mounted pull-out screen for use as a child safety barrier across a doorway has a control mechanism which prevents the screen from extending when impacted by a child. The roller is locked against rotation in a direction allowing the screen to unwind unless released by a manual push-button. The roller automatically locks after the screen has been extended and fitted in place. The automatic locking mechanism operates by a friction drive which releases a pawl to spring into engagement with a ratchet wheel when the screen has been pulled out and released.
Claims14
In a spring roller-mounted pull-out screen structure comprising a length of screen material wound on a roller which is journalled between opposite end caps of an elongate casing and which is spring-biased to rotate in a first direction for winding the material onto the roller, the improvement comprising a roller control mechanism including a rotary body connected to the roller for rotation therewith, an arresting body releasably engaged with the rotary body having means for locking the roller against rotation in a second direction unwinding the material from the roller while permitting rotation of the roller in the first direction, manually operable means for moving the arresting body out of engagement with the rotary body enabling the roller to be rotated in the second direction and motion responsive means for automatically re-engaging the arresting body with the rotary body responsive to rotation of the roller in the first direction.
In a spring roller-mounted pull-out screen structure comprising a length of screen material wound on a roller which is journalled between opposite end caps of an elongate casing and which is spring-biased to rotate in a first direction for winding the material onto the roller, the improvement comprising a roller control mechanism including a rotary body connected to the roller for rotation therewith, an arresting body releasably engaged with the rotary body for locking the roller against rotation in a second direction unwinding the material from the roller, manually operable means for moving the arresting body out of engagement with the rotary body enabling the roller to be rotated in the second direction and motion responsive means for automatically re-engaging the arresting body with the rotary body responsive to rotation of the roller in the first direction, wherein the rotary body comprises a ratchet wheel and the arresting body comprises a pawl biased into engagement with teeth on the ratchet wheel, further wherein the motion responsive means comprises a cylinder integral with the ratchet wheel and a moveable cam member interposed between the cylinder and the pawl, the cam member having a blocking position with opposed surfaces thereof engaging the cylinder and the pawl respectively when the pawl is moved out engagement with the ratchet wheel, with differential friction forces being developed between said opposed surfaces and the cylinder and pawl respectively when the cylinder is rotated in opposite directions for automatically moving the cam member out of the blocking position when the cylinder is rotated in the first direction and for preventing the cam member being moved out of the blocking position when the cylinder is rotated in the second direction.
A bidirectionally movable body in combination with a control mechanism for controlling movement of the bidirectionally movable body in a first direction, the control mechanism comprising an arresting body having a first position proximal the moveable body for arresting movement of the movable body in said first direction and a second position distal the moveable body releasing the moveable body for movement in said first direction;
- biasing means urging the arresting body toward the first position, a moveable cam member interposed between the bodies the cam member having a blocking position holding the arresting body in the second position with opposite surfaces of the cam member in frictional engagement with the respective bodies, the respective bodies developing differential friction forces with the cam member for inducing movement of the cam member out of the blocking position responsive to movement of the moveable body in a second direction opposite said first direction and the mechanism further including means preventing the cam member being moved out the blocking position responsive to movement of the moveable body in the first direction.
Dependencies are inferred from the claim text.