| 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 (b), a light emitting element is subjected to constant current control by a fixed current Fa at the beginning. When the driving time of the light emitting element exceeds 250 hours. the light emitting element is passed through the constant current control by raising the driving current from Fa to Fb. Therefore, an emission quantity of light is improved to Ib although it has decreased from Ia to Ix. A driving voltage of the light emitting element has a characteristic of a figure (a). The measured driving voltage is compared with a preliminarily set threshold value Vth. When the driving voltage exceeds the threshold value, the driving current becomes Fb and the driving voltage at this time is raised to Vb. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
