a photoelectric conversion element that converts {TAIL ~ an optical signal} into an electrical signal and that accumulates {HEAD ~ signal electric charge}, 
a photoelectric conversion element that converts { TAIL ~ an optical signal } into an electrical signal and that accumulates { HEAD ~ signal electric charge } ,
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH