Non-contact thermal temperature controller

A temperature control device for use in controlling temperature of a heated element, the device comprising:

• plural non-contact sensors directed at different parts of the heated element to generate sensor signals;
• a differential amplifier that processes the generated sensor signals to produce a temperature indication signal;
• a mapping circuit connected to the differential amplifier so as to perform a mapping function on the temperature indication signal to produce a mapped temperature signal;
• a first comparison circuit connected to the mapping circuit so as to receive the mapped temperature signal and compare the mapped temperature signal to a predetermined temperature setting threshold, and produce a comparison result;
• a speed determination circuit connected to receive a pulse signal indicative of the rotational speed of the heated element so as to produce a speed status signal;
• and
• a modulation circuit connected to receive the comparison result from the first comparison circuit and the speed status signal, causing heating of the heated element to be modulated so as to maintain the temperature of the heated element at a temperature corresponding to the predetermined temperature setting threshold.

An electrophotographic printing device having a hot roller for fixing images on a recording medium, and having a control circuit for controlling temperature of the hot roller, the control circuit comprising:

• plural non-contact sensors directed at different parts of the hot roll to generate sensor signals;
• a differential amplifier that processes the generated sensor signals to produce a temperature indication signal;
• a mapping circuit connected to the differential amplifier so as to perform a mapping function on the temperature indication signal to produce a mapped temperature signal;
• a first comparison circuit connected to the mapping circuit so as to receive the mapped temperature signal and compare the mapped temperature signal to a predetermined temperature setting threshold, and produce a comparison result;
• a speed determination circuit connected to receive a pulse signal indicative of the rotational speed of the hot roll so as to produce a hot roll speed status signal;
• and
• a modulation circuit connected to receive the comparison result from the first comparison circuit and the hot roll speed status signal, causing heating of the hot roll to be modulated so as to maintain the temperature of the hot roll at a temperature corresponding to the predetermined temperature setting threshold.

A temperature control device for use in controlling temperature of an electrophotographic hot roll, the device comprising:

• plural non-contact sensors directed at different parts of the hot roll to generate sensor signals, wherein one of the non-contact sensors is directed at a portion of the hot roll having a thermally conductive coating, and another of the non-contact sensors is directed to a black body strip on the hot roll;
• a differential amplifier that processes the generated sensor signals to produce a temperature indication signal;
• a display circuit connected to receive the temperature indication signal and provide a visual display of temperature of the hot roll;
• a PROM circuit connected to the differential amplifier so as to perform a mapping function on the temperature indication signal to produce a mapped temperature signal;
• a first comparison circuit connected to the PROM circuit so as to receive the mapped temperature signal and compare the mapped temperature signal to a predetermined temperature setting threshold, and produce a comparison result;
• a speed determination circuit connected to receive a pulse signal indicative of the rotational speed of the hot roll so as to produce a hot roll speed status signal;
• a modulation circuit connected to receive the comparison result from the first comparison circuit and the hot roll speed status signal, causing heating of the hot roll to be modulated so as to maintain the temperature of the hot roll at a temperature corresponding to the predetermined temperature setting threshold;
• and
• a second comparison circuit connected to the PROM circuit so as to receive the mapped temperature signal and compare the mapped temperature signal to a predetermined maximum temperature threshold, wherein the second comparison circuit initiates an alarm signal in the event that the mapped temperature signal exceeds the predetermined maximum temperature threshold.