A flat configuration CRT having positioned behind one or more line cathodes an array of control electrodes for electron beam modulation and shield electrodes for mutually shielding the control electrodes, in which the shield electrodes are connected as a plurality of electrically separate blocks. DC voltages applied to the respective blocks are adjusted such as to establish identical levels of beam current for electron beams which are generated by emission from the line cathodes, thereby enabling accuracy requirements for spacing between these electrodes and the line cathodes to be substantially reduced.