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