Projection lamp control arrangement

Abstract

A control circuit is provided in projection apparatus to control the operating characteristics of the projection lamp. The projection lamp control circuit maintains a constant illumination output and color temperature of the projection lamp to provide improved operation and increased lamp operating life. The desired operating point of the projection lamp is accurately maintained by sensing the operating point of the projection lamp and utilizing the sensed deviation from the desired operating point to vary the output of a blower that provides cooling of the lamp. Thus, the operating point and color temperature of the projection lamp is accurately maintained in a closed loop arrangement by sensing the operating point of the lamp and controlling the blower output. The control arrangement provides a first predetermined blower output during the projection lamp-off mode, a second predetermined blower output (off in a specific arrangement) during the projection lamp ignition and start-up mode and a variable output in a closed loop arrangement during normal projection lamp operation.

Dependencies are inferred from the claim text.