METHOD TO MONITOR AND CONTROL HEATER BULB FILAMENT TEMPERATURE TO STABILIZE OPERATION AND EXTEND BULB LIFE IN LIFE IN PRINTING APPLICATIONS

This disclosure relates to the use of heater bulbs in printing applications but can also be applied to other applications of heater bulbs in many other industries. Halogen and incandescent light bulbs are often used in radiant heater and drying applications in the printing process. Some of the more common uses in the printing industry are for fixing of inks to printing substrates, drying of inks and coatings, and heating surfaces of moving parts. The bulbs used in these applications are often expensive, and it is beneficial to maximize their life to reduce the operating cost of the printing press. It is very common to use some form of active control to adjust the power to the bulb heaters to allow for closed loop control of the surface that is being heated. Many existing bulb controllers already monitor the voltage and current to calculate bulb power, then control for constant power. This disclosure takes this further by using the voltage and current data to calculate the bulbs resistance, then the temperature of the filament can be derived using the resistance Vs temperature curves for the filament material (typically a tungsten alloy). The derived temperature data can then be used as an input to the bulb control algorithms to maximize the bulb life, monitor for cooling and environmental changes, and/or to stabilize the bulbs radiated spectrum