DIMMING DEVICE FOR EXPOSURE LAMP

摘要

PURPOSE:To simplify a constitution and to decrease the number of components by generating a trigger pulse through software by using a microcomputer and controlling the turn-on angle of a thyristor by using this pulse and then controlling electric supply power to a lamp. CONSTITUTION:An exposure lamp 4 is connected to an AC power source 37 through a bilateral thyristor 38. The rays of light from the lamp 4 are transmitted to a photodiode 31 through a glass fiber 24 and converted into a current value, which is converted into a voltage value by a current voltage converting circuit 32; and the voltage value is digitized by an A/D converter 35 and digital data is inputted to the microcomputer 36. The microcomputer 36 generates the trigger pulse according to the level of the input data and controls the turn-on angle of the thyristor 38 to control the electric supply power to the lamp 4. Thus, the trigger pulse is generated through software, so the constitution is simplified and the number of components is decreased.