| 摘要 |
PROBLEM TO BE SOLVED: To detect the amount of displacement and the amount of change in density accurately, while reducing stand-by time of a user.SOLUTION: A CPU 209 determines light-emitting amount Led2 for causing light-emitting elements 253, 256 to emit light in detecting a displacement amount detection toner pattern 258 and a density change amount detection toner pattern 259 by means of an optical sensor unit 225, on the basis of a result obtained by the optical sensor unit 225 detecting an intermediate transfer belt 219 when the light-emitting elements 253, 256 emit light with preset light-emitting amount Led1. |
