performed by moving the fluorescent lamp 71 in the axial direction relative to the photosensitive drum 22 fig1 is a flow chart showing an operation when the aforementioned luminescence controlling apparatus b is used for a print head first in s 21 it is judged whether or not the power supply 7 is turned on when the power supply 7 is turned on yes in s 21 the cpu 77 is initialized in s 22 when it is turned off no in s 21 the routine waits until the power supply 7 is turned on subsequently in s 23 the fluorescent lamp 1 is made to emit light and the image of the original 51 is scanned by the image scanner 21 in s 24 this read image is transmitted as data from the scanner 52 in s 25 data conversion and compression are performed so that the on off information in every dot may be added to the image of one line to this transmitted image data in s 26 a control signal is sent out to the print head from the cpu 77 so that the data is written in the photosensitive drum 22 for every line since the on off control for every image one dot is needed at that time in s 27 the electric discharge direction of the fluorescent lamp 71 is sent into.