OPTICAL WRITING HEAD

摘要

PURPOSE:To reproduce a left and right symmetric figure by forming a light emitting region into a shape having a symmetric axis in a sub-scanning direction. CONSTITUTION:A narrow strip like light emitting part 21 is provided in the hermetically sealed case 20 of an optical writing head H along a main scanning direction X and one filamentous cathode 22 is provided under tension in parallel to said light emitting part 21. When the cathode 22 is heated, thermoelectrons are generated and attracted to an acceleration grid electrode 28 to which positive voltage is applied to be accelerated and a part thereof passes through an acceleration slit 28a. At this time, positive voltage is applied to eight anode electrodes 23 successively from a single side and, when the thermoelectrons are attracted to the anode electrodes 23 to which positive voltage is applied, said thermoelectrons pass only through a selection slit 26a to which positive voltage is applied to reach a fluorescent body 24. Each pixel of an image is reproduced using a light emitting region 24a formed into an oval shape having a symmetric axis in a sub-scanning direction Y so that both of the straight line whose intersecting angle with a main scanning direction X is theta' and a straight line of (pi-theta') have the same continuity. By this method, a left and right symmetric figure can be recorded on a photosensitive body and a left and right symmetric image can be reproduced and, therefore, image qualty is enhanced.