What is a fuser thermistor sensor? Laser printers use the combination of heat and pressure to stick toner particles into paper permanently. And as such the fuser assembly of the laser printer is a vital component devised to melt toner particle and allow it to adhere to paper fibers; resulting in a permanent bond. The fuser therefore must maintain heat temperature that range from between 180 to as much as 210 degrees Fahrenheit. The formulation of toner particles should likewise meet the required melting properties and temperature range to be an effective vehicle for laser printing. If fuser temperature could not be maintained or if the toner formulation does not meet fuser specification, then it will manifest as half-baked toner peeling off over printouts.
In the case of Lexmark laser printers, the fuser’s heating element is a Halogen Lamp designed to heat up and reach the desired temperature range. Because a Halogen Lamp can heat-up very rapidly in short stretches, it can however scourge paper (affects the hygroscopic properties) during printing if left unchecked and uncontrolled or cause the early burn-out of the Halogen lamp. The work of the Thermistor sensor therefore is to maintain the prescribed temperature ranges required for laser printing, particularly when the printer is used over long periods of time.
Lexmark laser printers for commercial use comes with a fuser assembly that is designed as a modular unit which can be replaced as a complete sub-assembly. Said component has a hot upper roller made of aluminum and is coated with Teflon (coating of most frying pans). The Halogen lamp heater is built into the core and comes either in metallic gray or green. The lower pressure roller counterpart is made of silicon based rubber and usually marketed as orange colored. The Thermistor is likewise mounted on the hot fuser roller to precisely monitor the fuser temperature. Heat could damage the silicon rubber pressure rollers which eventually become soft. The Teflon coating of the hot rollers could wear-off and the Halogen lamp may burnout. A dirty Thermister coated with baked-on toner could also cause the fuser assembly to overheat.