US Patent 7497566 Image transfer element with balanced constant load force

An image transfer mechanism includes a pressure element and a lever system. The lever system has a load attachment point with a range of position that depends on the thickness of a print medium positioned between the imaging element and the pressure element. A load mechanism includes a load connector with a distal end attached to the lever system load attachment point so that displacement of the lever system attachment point causes longitudinal movement of the load connector. The load mechanism applies a load that is substantially constant throughout the range of position of the lever system load attachment point. The load mechanism includes a spring and a crank attached to the spring and to the proximal end of the load connector. The crank is configured so that a change in the spring force produces a lesser change in the load force at the distal end of the load connector.