The first scan unit 110 comprises {TAIL ~ an exposure lamp} 114 and {HEAD ~ a first reflection mirror} 115 
The first scan unit 110 comprises { TAIL ~ an exposure lamp } 114 and { HEAD ~ a first reflection mirror } 115
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH