Patent ID: 7360736

Claim:
A monodirectional braking mechanism for use with a device for extending and retracting a sheet of material on a roller, the braking mechanism comprising: a) one or more than one housing, where the housing is a tubular structure having an inner surface and comprising saw teeth equally spaced around the entire inner surface; b) one or more than one rotor within the housing; c) a brake controller connected to the rotor, the brake controller comprising a ratchet gear comprising one or more than one elastic catching element extending from the shaft of the rotor which engages the saw teeth in order to actuate the braking mechanism; and d) a brake operatively coupled with the brake controller; where each of the saw teeth comprises two sides, a first side and a second side, extending from the inner surface of the housing and intersecting at a point, and where the first side is a different length than the second side; where the braking mechanism reduces the force or rate, or both the force and rate, of rotation of the roller as the roller is rotated in a second rotation direction but has substantially no effect on the force or rate of rotation of the roller when the roller is rotated in a first rotation direction; and where the first rotation direction is the reverse of the second rotation direction.