Abstract: A cathode ray tube comprises a series of quadrupolar lenses for focusing a beam of electrons, emitted from a cathode at one end of an evacuated envelope under the control of a control electrode, at a target screen at the other end of the envelope. After having been focused at the target by adjustment of electric potentials on the quadrupolar lenses, the electron beam will defocus upon change in a potential on the control electrode because then the crossover or initial focusing point of the electron beam will be displaced along the central axis of the envelope. With a view to ready refocusing of the beam at the target, a refocusing lens is provided between the crossover point and the quadrupolar lenses for providing a convering lens action of radial symmetry about the envelope axis. The beam can be refocused through adjustment of a single potential on the refocusing lens rather than through adjustment of several different potentials on the quadrupolar lenses.

Abstract: A generally box-shaped electron lens system for use in an oscilloscopic or storage cathode-ray tube for the amplification of both vertical and horizontal deflections of the electron beam from the gun to the target of the CRT. The lens system comprises two electrodes at least partly displaced from each other along the CRT tube axis, with a gap therebetween for electrically insulating one from the other. A pair of tongues extend either from the gun-side electrode into the target-side electrode, or from the target-side electrode into the gun-side electrode, or two such pairs of tongues extend from both electrodes into interdigitating relation to each other. Upon application of prescribed potentials to the two electrodes, a quadrupolar lens field is created in the space between the pair or pairs of tongues for deflection amplification in both directions. On having been deflected vertically, the beam has its deflection amplified by having its traveling direction inverted with respect to the tube axis.

Abstract: A generally box shaped, electronic lens system for use in a cathode ray tube for amplification of both horizontal and vertical deflection of the electron beam. The lens system comprises two or three electrodes arranged in axial alignment, with an insulating gap or gaps therebetween, so as to encompass the beam trajectories from the deflection system to the target of the CRT. The action of the lens system on the beam is divergent in a horizontal direction and convergent in a vertical direction. The target side electrode has its beam exit end closed by an end plate having defined therein an aperture elongated horizontally. The CRT includes a postaccelerating electrode whose field acts on the beam exit end of the lens system, creating an additional lens at the end plate aperture. The vertical dimension of the aperture gradually increases, and then gradually decreases, from the midpoint toward the opposite extremities of its horizontal dimension.