Patent ID: 7969082

Claim:
An electron beam apparatus comprising: an insulating member which has a concave portion on its surface; a cathode which is positioned astride an outer surface of the insulating member and an inner surface of the concave portion; a gate which is positioned opposite to the cathode on the outer surface of the insulating member; and an anode which is positioned opposite to the cathode so that the gate is disposed between the anode and the cathode, wherein an angle θ between a surface of a portion of the cathode which is positioned on the inner surface of the concave portion and a virtual plane of which a normal line is a line connecting respective aperture side ends of the cathode and the gate in a region of the concave portion that the cathode and the gate are mutually opposed satisfies an expression (1) θ≧15×( h 2/ d ) 0.5 +(230 ×Vf −0.6 −35) (0°<θ<90°) (1) where d: a shortest distance between the cathode and the gate in the region of the concave portion that the cathode and the gate are mutually opposed [nm], h 2 : a height of a side member of the gate in a direction parallel with that of the shortest distance d [nm], and Vf: a driving voltage [V].