Abstract: The present invention includes a cathode-ray tube (10) capable of providing a high-brightness, high-resolution large screen display that is compatible with, for example, field sequential liquid crystal color display systems and monochrome imaging systems. Preferably, the tube includes a small-diameter cathode assembly (14 of 110) with an adjacent small-diameter control grid electrode (38 or 114). The small diameters of the cathode assembly and the control grid electrode result in relatively little capacitance and are, therefore, compatible with relatively high video signal bandwidths. A thick accelerating electrode (66 or 150) is positioned adjacent the control grid electrode to prefocus the electron beam and, thereby, form it with relatively low spherical aberration. In a preferred embodiment, the electron beam is modulated in a push-pull manner by applying a video modulation signal and its inverse to the cathode and the control grid electrode.

Abstract: A cathode-ray tube (10) includes a prefocusing lens (14) and an adjacent high-voltage einzel focus lens (16) to form an electron beam with low spherical aberration. The high-voltage einzel focus lens includes a central lens element (52) positioned between a pair of outer lens elements (54) and (56). The outer lens elements receive a common high-voltage potential of more than about 12 kilovolts. The prefocusing lens includes a G3 electrode positioned between an anode (48) and a first one of the outer lens elements of the einzel focus lens. The G3 electrode receives the high voltage applied to the outer lens elements. In a preferred embodiment, the G3 electrode is a flat end disc plate (57b) on the end of the first one of the outer lens elements.

Abstract: An integrated grid (G1/G2) assembly having enhanced mechanical strength and rigidity is provided for use in an electron gun assembly of a cathode ray tube (CRT). In the integrated grid assembly, the first and second grids (35 and 40, respectively) are fixed in relationship to one another, both axially and radially, by means of an insulating element (50) and a collar element (55). Brazed joints are preferably provided at the interface of the insulating element (50) with the second grid (40) and the collar element (55) to enhance the mechanical strength and rigidity of the assembly. An integrated grid (G1/G2)/anode assembly may be provided by mounting anode assembly (45) fixedly with respect to second grid (40) by means of second insulating element (60) and second collar element (65). Methods for assembling the integrated grid assemblies are also disclosed.

Abstract: A cathode-ray tube (54) includes a bipotential electrode structure (50) that converges the electrons in an electron beam. The bipotential electrode structure includes a cylindrical metallic electrode (56) positioned within a neck portion (66) of an evacuated glass envelope (52) and an electrically resistive coating (58) on an interior surface (60) of the neck portion. The resistive coating has a terminal end (64) positioned adjacent the metallic electrode. An electrically and thermally conductive coating (62) on the interior surface of the neck portion covers the terminal end of the resistive coating and partly overlaps the metallic electrode. The conductive coating functions to prevent electric "punch-through" between the interior and exterior surfaces of the tubular envelope. The conductive coating also allows relatively efficient operation of a beam deflection apparatus.

Abstract: Apparatus for correcting astigmatism produced by the electromagnetic deflection yoke of a cathode-ray-tube includes stigmator electrodes provided with elongated slots through which the cathode-ray-tube's electron beam or beams pass. Appropriate correction voltages, stored in digital memory, are applied to the stigmator and focus electrodes for bringing about re-focusing of the electron beam in appropriate axes for restoring a single point focus.

Abstract: A multiple beam cathode-ray tube employs a bipotential electrode structure to provide acceleration and convergence of the electron beams without the use of a resistive helix coil. In a preferred embodiment, the bipotential electrode structure (10) is employed in a cathode-ray tube (14) in which a cathode (28) and a grid electrode structure (30) cooperate to form plural beams of high velocity electrons. The bipotential electrode structure includes an immersion lens cylinder (16) that is positioned upstream of a tubular electrode element (18). The outer diameter (226) of the immersion lens cylinder is less than the inner diameter (228) of the tubular electrode element, thereby allowing the downstream end of the immersion lens cylinder to extend into the upstream end of the tubular electrode element. A potential difference applied between the immersion lens cylinder and the tubular electrode element accelerates the electrons in the multiple beams and converges them to form an array of crossovers at a plane (64).

Abstract: Apparatus for correcting astigmatism produced by the electromagnetic deflection yoke of a cathode-ray-tube includes plural stigmator electrodes provided with elongated slots through which the cathode-ray-tube's electron beam passes. Appropriate correction voltages, stored in digital memory, are applied to the stigmator and focus electrodes for bringing about re-focusing of the electron beam in appropriate axes for restoring a single point focus on the cathode-ray-rube's screen.

Abstract: A very high resolution cathode-ray tube is provided with a combination cylindrical high voltage electrode and particle trap disk that is supported by a multiplicity of spring fingers from the interior wall of the cathode-ray tube neck. One set of the spring fingers contacts the high voltage coating on the interior of the cathode-ray tube envelope. The particle trap portion is provided with an aperture smaller than the adjacent circumferential edge of the lower voltage electron lens electrode in the adjacent electron gun structure, while the higher voltage electron portion is larger in diameter than the lower voltage electrode of the electron gun structure and overlaps the lower voltage electrode. A ring getter device is supported from the higher voltage electrode.

Abstract: A cathode and grid assembly includes a first grid of small diameter secured to a planar inner surface of a ceramic means and over a central opening in the ceramic means and a second grid having a first planar section secured to a planar outer surface of the ceramic means, a second planar section positioned within the central opening and a frustum of a cone section interconnecting the first and second planar sections with the frustum of a cone section extending along a frustum of a cone outer surface of the ceramic means.

Abstract: A cathode ray tube is provided with a rectangular box-shaped lens intermediate the tube's screen and beam deflection plates for amplifying beam deflections in both the horizontal and vertical axes. In one form, useful in either monoaccelerator or PDA tubes, the lens includes four tubular elements disposed end-to-end and spaced apart a sufficient distance to isolate them electrically. The adjacent ends of each pair of the elements are oppositely curved to provide electron lenses having vertical cylindrical mid-surfaces. The radii of the cylindrical surfaces and the voltages applied to each element are adjusted to provide a lens system that produces minimum distortion and optimum linearity in the resultant display.