FIG 4 is a cross sectional view of {TAIL ~ an electron gun unit} of {HEAD ~ the third embodiment} 
FIG 4 is a cross sectional view of { TAIL ~ an electron gun unit } of { HEAD ~ the third embodiment }
OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD