{HEAD ~ An object} of {TAIL ~ the invention} is to eliminate the disposition change of plural beam spots on the inner face of a drum 
of
{ HEAD ~ An object } of { TAIL ~ the invention } is to eliminate the disposition change of plural beam spots on the inner face of a drum
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH