System for correcting deflection of belt from its normal path of movement

A system for correcting deflection of a belt from its normal path of movement, wherein a deflection in one direction of the belt trained over a plurality of rollers for movement in a predetermined direction is corrected, at least one of said plurality of rollers being displaceable transversely to its center axis in a manner to allow the moving belt to move rightwardly or leftwardly with respect to the direction of movement of the belt, comprising:

• (a) sensor means located along one side edge of said belt for sensing one side edge portion of said belt as it reaches a predetermined leftward or rightward position and producing a corresponding signal;
• (b) a movable plate with a shaft means supporting said at least one roller at one end thereof for rotation and being able to move in pivotal movement between one position at which said one roller deflects said belt to one direction of leftward or rightward and another position at which said one roller deflects said belt to the other direction in accordance with said signal;
• (c) a cam rotatably mounted to effect pivotal movement of said movable plate;
• and
• (d) a spring clutch connecting said cam to a drive member, causing said cam to rotate through a predetermined angle by a signal produced by said sensor means to displace said movable plate to a corresponding one of positions, and then keeping said cam stationary in that condition till a next signal is produced by said sensor means.