The frequency modulation apparatus 2, wherein {HEAD ~ said predetermined fluctuation range} is ±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 { HEAD ~ said predetermined fluctuation range } is ±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 HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH