An electron gun assembly for a cathode ray tube includes a cathode for emitting an electron beam, and a plurality of electrodes mounted in a row with predetermined gaps therebetween. The electrodes include a focus electrode for receiving a focus voltage, and an anode electrode surrounding part of the focus electrode for receiving an anode voltage. A support is used to fix the electrodes in an aligned configuration, and a first auxiliary support secures the focus electrode to the support. The focus electrode includes an intermediate aperture section, a small aperture section, and a large aperture section, while the anode electrode includes a large aperture section and a small aperture section. Two second auxiliary supports secure the anode electrode to the support.

An electron gun includes a cathode (K), a control electrode (1), an accelerating electrode (2), a first anode (3), a focus electrode (4), and a second anode (5), which electrodes are arranged in a tube axial direction at predetermined intervals; and electrode supports (11, 21, 31, 41, 51) provided to a side wall of each electrode and embedded in and secured to insulating supports (6); wherein the focus electrode (4) is cylindrical an has three different diameters respectively provided at a cathode side portion, an intermediate portion and a panel side portion, the panel side portion of the focus electrode (4) is inserted into the second anode (5) to constitute a main lens section, the inner diameter of the intermediate portion of the focus electrode (4) is smaller than the inner diameter of the panel side portion and larger than the inner diameter of the cathode side portion and the electrode support (41) is provided at the intermediate portion of the focus electrode (4). The electron gun including an electrode support (41) provided at the intermediate portion of the focus electrode (4) reduces deformation of the focus electrode (4).

In order to improve the definition and the breakdown behavior in a tube neck (16) that includes an anode cylinder (20) and a focusing cylinder (19), the tube neck (16) is made of a non-conductive material, particularly a ceramic. The inner surface of the anode cylinder (20) and the inner surface and the outer surface of the focusing cylinder (19) are coated with an electrically conductive material (21).

A projection type cathode ray tube has a panel and an electron gun. The electron gun has a plurality of electrodes including a cathode, a control electrode, an accelerating electrode, a first anode, a focus electrode and a second anode, which electrodes are arranged in a tube axial direction at predetermined intervals. The second anode has a first cylindrical portion at the panel side and a second cylindrical portion at the cathode side, the first cylindrical portion having a larger inner dinner diameter than the inner diameter of the second cylindrical portion. The focus electrode has a panel side cylindrical portion with an inner diameter D1 and a length L1, an intermediate cylindrical portion with an inner diameter D3 and a length L3, and a cathode side cylindrical portion with an inner diameter D2 and a length L2. The inner diameters D1, D2, and D3 are different from each other. The focus electrode also has a first funnel like connecting portion between the panel side cylindrical portion and the intermediate cylindrical portion.

A low voltage Einzel gun design maximizes the size of the second main lens to reduce spherical aberrations thereby reducing spot-size and improving focus quality. The gun's final accelerator electrode is formed as an internal conductive coating on the neck, which is connected to anode potential through an anode button. The jumper between the final and second accelerator electrodes is removed and the second accelerator electrode is connected through the high voltage stem pin to an external potential. Connection of the high voltage stem pin to anode potential defines an Einzel gun. The focus electrode is now connected to one of the low voltage stem pins. In a high voltage Einzel gun, connecting the second accelerator electrode and focus electrode to the high voltage and a low voltage stem pin, respectively, would cause arcing between the pins.