| 摘要 |
PROBLEM TO BE SOLVED: To provide a cathode acquisition method by which a required brightness is obtained.SOLUTION: A cathode acquisition method comprises: a step S106 of producing a plurality of cathodes having an electron emission member and also having a cover part covering a side face of the electron emission material with an empty space between them; a step S108 of measuring the outside diameter of the upper face of the electron emission member for each of the cathodes; a step S110 of measuring the outside diameter of the empty space in the same plane as the upper face of the electron emission member; a step S112 of calculating, for each of the cathodes, an area ratio obtained by dividing the area of the empty space in the same plane by the area of the upper face of the electron emission member; a step of acquiring the upper limit of an area ratio corresponding to a required brightness, by using the relative relation between the brightness and the area ratio; and a step S114 of selecting, from the produced cathodes, a cathode having an area ratio equal to or smaller than the upper limit value. |
