| 摘要 |
PROBLEM TO BE SOLVED: To reduce influence of thermal interference without causing increase of size.SOLUTION: If 40 light emitting parts (ch1 to ch40) are orthogonally projected on virtual lines extending in an S direction corresponding to a sub-scanning direction, when c is a predetermined value, each of the light emitting part ch1 to the light emitting part ch20 has an equal interval of 2c to an adjacent part, each of the light emitting part ch20 to the light emitting part ch21 has an interval of 3c to the adjacent part, and each of the light emitting part ch21 to the light emitting part ch40 has an equal interval of 2c to the adjacent part. Thereby, without increasing size not so much, the intervals between the light emitting parts which are in a region more influenced from other light emitting parts can be widened. Thus, without increasing the size, influence of thermal interference can be reduced than influence in conventional cases. |
