| 摘要 |
PROBLEM TO BE SOLVED: To correct astigmatism and image curvature aberration of an electron beam spot and to reduce the generation of raster moire by providing a fourth grid electrode, a fifth grid electrode and a phosphor screen with a predetermined relations. SOLUTION: A fourth grid electrode, a fifth grid electrode and a phosphor screen satisfy the relations 0.0625×L(mm)<=B-20A/(3ϕ)<=22.0 mm and L(mm)<=352 mm, where A(mm),ϕ(mm), B(mm) and L(mm) represent the length of the fourth grid electrode in the tube axis direction, the average value of the dimensions in the horizontal and vertical directions of an electron beam passing hole at the center of the fourth grid electrode, the length of the fifth grid electrode in the tube axis direction from the cathode side end face to the phosphor side end face, and the distance of the fifth grid electrode in the tube axis direction from the phosphor screen side end face to the central part of the phosphor screen, respectively. It is preferable that a second focusing voltage be supplied to each of multiple sub-electrodes, including the sub-electrode nearest a anode and an electrostatic quadrupole lens is formed between the sub-electrodes arranged second and third, when counted from the cathode side.
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