| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a line head constituted to prevent an image quality from being degraded even when a driving time exceeds a fixed time, and to provide an image forming apparatus using the same. <P>SOLUTION: In an example of a figure (a), a light emitting element is subjected to constant voltage control by impressing a fixed voltage Va at the beginning. When the driving time of the light emitting element exceeds 250 hours, the light emitting element is passed through the constant voltage control by raising the driving voltage from Va to Vb. In other words, the light emitting element is subjected to the constant voltage control by changing the application voltage in accordance with the driving time. A figure (b) shows the relation between the driving time and an emission quantity of light of the light emitting element. The emission quantity of light decreases from the beginning Ia to Ix when the driving time exceeds 200 hours. The emission quantity of light is improved to Ib because the application voltage is raised from Va to Vb as above when the driving time exceeds 250 hours. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
