| 摘要 |
PURPOSE:To prevent the occurrence of periodical density unevenness by extending the light-emitting time of both outsides in light-emitting element strings on both outsides to the same degree as the light-emitting elements in the inner side among the light-emitting element string. CONSTITUTION:The light-emitting elements 12 are arranged on an anode electrode 11 in a vacuum fluorescent tube in four light-emitting element strings 121-124. The light-emitting element strings 121 and 124 have the same degree of light-emitting time, and they are constituted in such a way that they become longer than the light-emitting time of the light-emitting element string in the inner part. Consequently, the deterioration of a light quantity which is accompanied by deviation from the optical axis of a lens 5 is compensated by the light- emitting time, and the exposure of the even light quantity is executed from respective light-emitting element strings 121-124 on the surface of a photosensitive body 2, whereby the variance of the light quantity in a main scanning direction does not occur. Thus, periodical density unevenness in the main scanning direction does not occur in a recording picture.
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