MEASURING DEVICE FOR OFF-CENTERING AMOUNT OF ELECTRON GUN

PURPOSE:To quickly obtain the concrete numerical value of an electron gun, by making the air to be jetted out of three nozzles onto the electron gun which is interposed in a spotting jig, and at the same time, by detecting the air pressure. CONSTITUTION:An electron gun 2 whose off-center amount is to be measured is made to interpose in a spotting jig 1. In this case, a round hole 10 of No.3 grid 5 is coupled with No.1 coupling part 13, a round hole 14 of No.6 grid 8 is coupled with No.2 coupling part 15; No.6 grid 8 is closely connected onto a table 12; thus, the positioning of the electron gun 2 relative to the spotting jig 1 is completed. Next, the air is jetted onto a grid whose off-center amount is to be measured out of three nozzles 21a-21c. The change of the air pressure in this case is converted into an electric amount; based upon this result, the off-center amount can be obtained by means of an arithmetic and logic unit.