Cathode ray tube having an electron gun positioned in the neck portion, the gun comprising a beam-forming part and a focusing structure and the beam-forming part comprising at least a cathode and a metal electrode plate provided with a central aperture, and the focusing structure comprising a hollow tube of an electrically insulating material with inner and outer surfaces and with a layer of high-ohmic resistive material on at least one of the surfaces. The electrodes of the beam-forming part of the electron gun are secured via metal pins to rods for forming an assembly. The hollow tube is directly secured to the metal electrode plate for the purpose of correct alignment. The tube has a first and a second end face, the first end face in one embodiment having a metal plate with a coaxial aperture, and the said metal plate is fixedly connected to the metal electrode plate of the beam-shaping part of the electron gun in such a way that their apertures are coaxial.
A method of manufacturing a cathode ray tube which includes an electron gun (3) having a number of electrodes (7, 8) and a resistive-layer lends system (5), characterized in that the electron gun is sparked in a manufacturing step in which a pulse voltage is applied to an electrode (8) and a direct voltage is applied to a part (9) of the resistive-layer lens system adjacent to said electrode (8) through supply leads. During the sparking step measures are taken to prevent the occurrence of sparks in the resistive-layer lens system (5) per se, which in turn prevents damage to the resistive-layer lens system.
The invention relates to a cathode-ray tube 1 having an electron gun 3 positioned in a neck portion 2. The electron gun 3 is provided with a focusing structure 10 which includes a hollow tube 12 of electrically insulating material. A layer 14 of a material having a high resistance is applied to the inner surface of the hollow tube. The resistance layer 14 is shielded from a getter arrangement 44 positioned in the cathode ray tube 1.
In a cathode-ray tube, a nonmetallic material such as ceramic or the like is used for an electrode 1a part of an electron gun. Consequently, the deterioration of the efficiency of modulation of electron beam trajectories by an eddy current generated at the metallic electrode part of the electron gun in the high-frequency magnetic fields and the heat generation at the electrode can be decreased. The generation of the eddy current by high-frequency magnetic fields by a convergence yoke or the like can be restrained by using a nonmetallic material for the electrode part of the electron gun. Consequently, the efficiency of modulation of electron beam trajectories is not deteriorated also in a high-frequency modulation zone and the heat generation at the electrode part can be also restrained. Less deterioration of efficiency of modulation of electron beam trajectories by the alternating magnetic fields occurs even in the high-frequency modulation zone, for example, more than 100kHz. Therefore, an excessive power is not required in a deflecting yoke, a convergence yoke, a velocity modulation coil or the like, even in a cathode-ray tube that modulates electron beam trajectories at high frequency in a high definition television or the like. As a result, the damage to a neck portion of a cathode-ray tube caused by heat generation at the electrode part also can be prevented.
The invention is directed to an extremely low-capacitance device for shaping an electron beam. The device is based on a ceramic body having a monolithic multi-layer structure. The manufacture of the ceramic body ensues with the assistance of LTCC technology, whereby this method is designationally modified. The body is constructed of pre-sintered ceramic layers whose lateral shrinkage is suppressed. The through apertures of the electrodes for the electron beam are thus arranged exactly coaxially, and the tolerances of the electrode dimensions are decoupled from the shrinkage during sintering. The electron beam of an electron gun is focused and the intensity thereof is modulated with the assistance of such a device.
A cathode-ray tube with high image quality in which electron beams with higher current density than the electron-emitting ability of cathodes are formed and a driving voltage of the cathodes can be decreased. A cathode-ray tube comprises a glass face-panel, a glass funnel connected to the rear part of the face-panel, and an electron gun for emitting electron beams that is contained in a neck portion of the funnel. On the peripheral surface of the funnel, a deflection yoke for deflecting the electron beams emitted from the electron gun is mounted. A phosphor dot for three colors of red, green and blue is applied on the inner surface of the face-panel, thus forming a phosphor screen surface. In the vicinity of the inner surface of the face-panel, a shadow mask is arranged substantially in parallel with the phosphor screen surface. Between the phosphor screen surface of the face-panel and the cathodes in the electron gun, a means for superimposing a plurality of electron beams on the predetermined phosphor dot is provided.
