Then, {HEAD ~ an original light image} is exposed to {TAIL ~ the thus charged surface} of the drum 1 through an exposure system 4 thereby forming an electrostatic latent image 
is exposed to
Then , { HEAD ~ an original light image } is exposed to { TAIL ~ the thus charged surface } of the drum 1 through an exposure system 4 thereby forming an electrostatic latent image
OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH