Patent ID: 6255788
Filing Date: 2001-07-03
Classification: H01J

Abstract:
A cathode ray tube provided with an electron gun having at least an electron beam generating unit comprising a cathode, a first grid electrode and a second grid electrode arranged in the order named for generating a plurality of electron beams arrayed in a horizontal direction and for controlling said plurality of electron beams, comprising:a main lens unit comprising a plurality of electrodes including a focus electrode and a final accelerating electrode for focusing said plurality of electron beams onto a fluorescent screen, said focus electrode comprising a plurality of electrode members, and said final accelerating electrode being disposed downstream of said focus electrode and adapted to be supplied with a first voltage;a final main lens formed between said final accelerating electrode and one of said plurality of electrode members adjacent to said final accelerating electrode;an electrostatic quadrupole lens formed in a first space between adjacent ones of said plurality of electrode members,one of said adjacent ones of said plurality of electrode members defining said first space being adapted to be supplied with a first focus voltage of a fixed value,another of said adjacent ones of said plurality of electrode members defining said first space being adapted to be supplied with a second focus voltage comprised of a fixed voltage and a dynamic voltage varying in synchronism with deflection of said plurality of electron beams,said first and second focus voltages being lower than said first voltage, but being higher than a voltage applied to said second grid electrode, andsaid electrostatic quadrupole lens being configured so as to focus said plurality of electron beams in one of the horizontal and vertical directions and to diverge said plurality of electron beams in another of the horizontal and vertical directions depending upon which is the higher of said first focus voltage and said second focus voltage; anda third electrostatic lens disposed between said final main lens and said electrostatic quadrupole lens and formed in a second space between adjacent ones of said plurality of electrode members,one of said adjacent ones of said plurality of electrode members defining said second space being adapted to be supplied with said first focus voltage,another of said adjacent ones of said plurality of electrode members defining said second space being adapted to be supplied with said second focus voltage, andsaid third electrostatic lens being configured so as to decrease a focusing action on said plurality of electron beams in both the horizontal and vertical directions with increasing deflection of said plurality of electron beams.