Importance

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Abstract

A sensor is disclosed for use with a paper feeding machine such as a printer, copier, or the like wherein a removable module comprises a paper source, the sensor determining when the paper in said module reaches a predetermined level corresponding to a low paper condition indicating the need to refill the cartridge. The sensor is mountable in the paper feeding machine adjacent the insertion point of the module, where a lever extending into the path of the module detects the presence and absence of the module. An arm is biased away from the insertion point of the module when the lever is in the position indicating no module, which allows the module to be inserted into the machine without interference with the arm, and is biased to contact the uppermost sheet of paper in the module when the lever indicates the presence of the module. Dominant and subservient springs operating in opposite directions are preferably used to accomplish the biasing of the arm and lever, and a rod contacting the lever and the arm is used to communicate the position of the lever to the arm and determine the position of the arm. The sensor also preferably includes an interrupter plate which rotates in a fixed relationship with the arm, such that a position of the arm in contact with the paper corresponding to a low paper level condition also determines the corresponding position of the interrupter plate. A circuit, such as a light emitter and light detector, can be placed such that the interrupter plate pivots between the light emitter and light detector only when the arm member is in the position corresponding to the low paper level condition. In a preferred embodiment, the position of the circuit can be adjusted by the user to vary the position at which the low paper condition occurs.

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First Claim