The frequency modulation apparatus 2, wherein said predetermined fluctuation range is {HEAD ~ ±2.0%} or less for {TAIL ~ the reference clock} in said image forming area on said image bearing body 
The frequency modulation apparatus 2 , wherein said predetermined fluctuation range is { HEAD ~ ±2.0 % } or less for { TAIL ~ the reference clock } in said image forming area on said image bearing body
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH