Abstract: One embodiment relates to a high-voltage electron gun including an insulator stand-off having a resistive layer. The resistive layer is at least on an interior surface of the insulator stand-off. A cathode holder is coupled to one end of the insulator 115 stand-off, and an anode is coupled to the other end. The resistive layer advantageously increases the surface breakdown field strength for the insulator stand-off and so enables a compact design for the high-voltage electron gun. Other embodiments, aspects and feature are also disclosed.

Abstract: In an accelerating tube which uses a conductive insulator, there is a possibility that the dopant concentration on a surface of the conductive insulator becomes non-uniform so that the surface resistance of the conductive insulator becomes non-uniform. Accordingly, a circumferential groove is formed on the inner surface of the conductive insulator accelerating tube in plural stages, and metal is metalized along inner portions of the grooves. When the resistance of a specific portion on the surface of the accelerating tube differs from the resistance of an area around the specific portion, the potential of the metalized region on the inner surface of the accelerating tube becomes a fixed value and hence, the potential distribution on the inner surface of the accelerating tube in the vertical direction can be maintained substantially equal without regard to the circumferential direction.

Abstract: An electron beam source includes a base and a tip fixed to the base and extending from the base. The tip includes a core and a coating applied to the core. The core has a surface that includes a first material. The coating includes a second material which is different from the first material. The second material forms a surface of the tip, and the second coating includes more than 30% by weight of a lanthanide element.

Abstract: A light source device includes first and second electrodes, an arc tube having a main body section having a discharge space in which the first and second electrodes are disposed with a distance and a sealing section disposed on each of the both ends of the main body section, a primary reflecting mirror disposed on the side of the first electrode, a secondary reflecting mirror disposed on the side of the second electrode, and a current drive device that generates an alternating current for causing the discharge between the first and second electrodes, and power control by controlling the alternating current so that supplying energy in an anodic term of the first electrode becomes smaller than supplying energy in a cathode term.

Abstract: Provided is a Schottky emitter having the conical end with a radius of curvature of 2.0 ?m on the emission side of an electron beam. Since a radius of curvature is 1 ?m or more, a focal length of an electron gun can be longer than in a conventional practice wherein a radius of curvature is in the range of from 0.5 ?m to not more than 0.6 ?m. The focal length was found to be roughly proportional to the radius of the curvature. Since the angular current intensity (the beam current per unit solid angle) is proportional to square of the electron gun focal length, the former can be improved by an order of magnitude within a practicable increase in the emitter radius. A higher angular current intensity means a larger beam current available from the electron gun and the invention enables the Schottky emitters to be used in applications which require relatively high beam current of microampere regime such as microfocus X-ray tube, electron probe micro-analyzer, and electron beam lithography system.

Abstract: A system and method for limiting emittance growth in an electron beam is disclosed. The system includes an emitter element configured to generate an electron beam and an extraction electrode positioned adjacent to the emitter element to extract the electron beam out therefrom, the extraction electrode including an opening therethrough. The system also includes a meshed grid disposed in the opening of the extraction electrode to enhance intensity and uniformity of an electric field at a surface of the emitter element and an emittance compensation electrode (ECE) positioned adjacent to the meshed grid on the side of the meshed grid opposite that of the emitter element and configured to control emittance growth of the electron beam.

Abstract: An electron gun (10) includes an electron multiplier (22, 22?, 22?, 110) has a receiving end (50, 50?, 50?) for receiving primary electrons and an output end (54, 54?, 54?) that emits secondary electrons responsive to primary electrons arriving at the receiving end. An electron emitter (20, 20?, 20?, 102) is arranged at the receiving end of the electron multiplier for supplying primary electrons thereto. At least one of an electrical and a magnetic focusing component (14, 16) is arranged at the open output end of the electron multiplier for focusing the secondary electrons to define an electron beam. In a suitable embodiment, the electron multiplier includes a generally conical substrate (74, 90) and an electron mirror (52, 521, 522, 523, 921, 922) including a high secondary electron yield film (70) disposed on an outer surface of the conical substrate.

Abstract: An electron source includes a vacuum chamber within which a vacuum is maintained by a vacuum pump. An insulated receptacle is mounted within the vacuum chamber and has a receptacle mounting flange. The receptacle mounting flange is used to establish a coordinate system having an electron beam axis and a lateral plane, wherein the lateral plane is transverse to the electron beam axis. An adapter is mounted to the receptacle and is adjustable in five degrees of freedom with respect to the coordinate system. A cathode and focus electrode are adjustable in at least four degrees of freedom and are pre-aligned with respect to one another prior to being installed on the adapter. An anode is mounted in the vacuum chamber and is aligned at a predetermined distance from the cathode with respect to the coordinate system.

Abstract: The present invention provides a cathode ray tube which exhibits a favorable contrast by enhancing a speed modulation effect. A front-stage anode electrode and a focus electrode which constitute an electron gun are respectively divided into a plurality of portions. A plurality of portions of the divided front-stage anode electrode are arranged in the tube axis direction at given intervals and are electrically connected with each other. A plurality of portions of the divided focus electrode are arranged in the tube axis direction at given intervals and are electrically connected with each other. Due to gaps formed in the front-stage anode electrode and the focus electrode, the speed modulation effect is increased.

Abstract: Electron gun in a color cathode ray tube including a separate plate electrode having a thickness thicker than a focusing electrode or an anode, a smooth outer circumference of a rim part, and single electron beam pass through hole for passing of three electron beam in common each fitted to opposite edges of the focusing electrode and the anode, thereby preventing deformation of the plate electrodes, enlarging diameters of the electron beam pass through holes, to allow formation of accurate large sized main focusing electrostatic lens, improving focusing onto a screen, and preventing occurrence of discharge between the focusing electrode and the anode.

Abstract: A main lens is composed of a dynamic focus electrode, a first auxiliary electrode, a second auxiliary electrode and an anode, which are successively arranged in a direction of travel of electron beams. A sub-lens provided on a cathode side of the main lens is composed of a third grid, a fourth grid and a fifth grid. The first auxiliary electrode is connected to the fourth grid, and both are connected to a voltage supply terminal on a resistor near the fourth grid. A fixed focus voltage is applied to the third grid and fifth grid sandwiching the fourth grid.

Abstract: A lens structure of a pre-focus part of an Hi-UPF electron gun to be used for a cathode ray tube has a cathode, a control electrode, an acceleration electrode, a first anode, a focus electrode and a second anode arranged in this order. The first anode and the second anode are to be commonly supplied with an anode voltage, and the focus electrode is to be supplied with a focus electrode. In a cathode ray tube of this construction, in the pre-focus part, the control electrode has an electrode beam passage hole of 0.57 mm or smaller and the distance in the vicinity of the electron beam passage hole between the acceleration electrode and the first anode is 1.9 mm or smaller.

Abstract: In a cathode ray tube including a cathode and a first and a second electrodes provided with an electron passing aperture, in which the first and the second electrodes are disposed in front of and coaxially with the cathode so that electron beam from the cathode passes through the electron passing aperture, the cathode voltage at the cutoff operation is set up from 50 V to 80 V on the basis of the first electrode to thereby realize a high luminance.

Abstract: An electrode of an electron gun, and an electron gun for a cathode ray tube are provided. The electron gun includes an outer-rim electrode having a large-diameter electron beam passing hole through which three electron beams pass, and an inner electrode installed inside the outer-rim electrode member, and having three electron beam passing holes disposed in an in-line arrangement and recesses formed at peripheries of the electron beam passing holes, the recesses having an eccentricity distance larger than an eccentricity distance between centers of the three electron beam passing holes.

Abstract: A cathode ray tube has a phosphor screen and an electron gun. The electron gun includes an electron beam generating section and an electron beam focusing section for focusing an electron beam from the electron beam generating section onto the phosphor screen. The electron beam generating section and the electron beam focusing section are mounted in predetermined spaced relationship on plural insulator support rods. The electron beam focusing section includes at least one compound electrode formed of a first electrode member, a second electrode member and a plate-like electrode member sandwiched therebetween. The plate-like electrode member is fabricated from a material thicker than materials from which the first and second electrode members are fabricated. The plate-like electrode member is laser-welded to the first and second electrode members at points of edges of the first and second electrode members.

Abstract: An electrode of an electron gun for a cathode ray tube including a first electrode member having a large-diameter electron beam passing aperture through which three electron beams pass, and a second electrode member in the first electrode member so as to be spaced apart from the edge of the first electrode member and having three small-diameter electron beam passing apertures, wherein a slanted portion extends from the edge of the first electrode member toward the interior of the large-diameter electron beam passing aperture.

Abstract: An electrode unit of an electron gun for a cathode ray tube including an outer rim electrode having a large-diameter electron beam passing hole through which three electron beams pass, and an inner electrode installed within the outer rim electrode and having a central electron beam passing hole disposed at its center and side electron beam passing holes disposed at opposite sides of the central electron beam passing hole. The side electron beam passing holes each have first and second curved sides along the sides closest to the central electron beam passing hole and opposite those sides, and linear portions connecting the first and second curved portions. The vertical and horizontal dimensions of the side electron beam passing holes are equal to each other.

Abstract: A beam-forming region (BFR) such as used in cathode ray tube (CRT) electron guns includes a cathode, a decelerating first electrode (G1), an accelerating secondelectrode (G2), an accelerating third electrode (G3) and an additional electrode (G2′) that introduces a pre-focusing lens. The decelerating first electrode (G1) and the accelerating second electrode include aperture arrays that introduce multiple emitting areas on the surface of the cathode. Electrons emitted from the cathode surface pass through their respective apertures and are then converged into a single high current beam by the pre-focusing lens. The high current electron beam passes through any one of many possible main-lens structures, which focuses the beam onto a phosphorescent display screen. The beam is swept across the display screen in a rater like manner while being modulated by a video source signal.

Abstract: The in-line type electron gun includes an electron beam generating section for generating and directing plural electron beams along toward a phosphor screen, and an electron beam focusing section for focusing the plural electron beams from the electron beam generating section onto the phosphor screen. The electron beam focusing section includes a focus electrode, at least one intermediate electrode and an anode supplied with a highest voltage arranged in the order named. The at least one intermediate electrode is supplied with an intermediate voltage between the highest voltage and a voltage supplied to the focus electrode. The following relationship is satisfied: 1.55≦D/L≦1.72, and 18.2 mm≦d≦26 mm,where D (mm) is a diagonal length of a usable display area of the phosphor screen, L (mm) is a distance from a center of the phosphor screen to an end of the anode facing toward the focus electrode, and d (mm) is an outside diameter of the neck portion.

Abstract: An electron gun for a cathode ray tube includes a triode portion composed of a cathode, a first grid electrode and a second grid electrode. Each of the first and second grid electrodes has beam-guide holes. The beam-guide hole of the first grid electrode is larger than the beam-guide hole of the second grid electrode. The hole portion of the first grid electrode is thinner than the hole portion of the second grid electrode. The distance between the first grid electrode and the second grid electrode is two or three times greater than as the distance between the cathode and the first grid electrode.

Abstract: A focusing electrode in an electron gun for a color cathode ray tube or high definition industrial picture tube includes a first and second focusing electrodes. A recess portion in one end of the first focusing electrode is oriented to face burring parts of the second focusing electrode. An electron beam and a surrounding portion pass through holes in the first focusing electrode to reduce the space between the first and second focusing electrodes. This improves the static convergence drift.

Abstract: A one-piece grid assembly for use in an electron gun for a miniature cathode-ray tube application that consists of a core made of an electrically insulating material, a first grid deposited on the core, and a second grid deposited on the core that is spaced apart from the first grid, and a method of making the one-piece grid assembly by first compression molding the core and then depositing the grid by plating are disclosed.

Abstract: A color cathode ray tube has a phosphor screen and an in-line electron gun. Each of the focus electrode and the anode of has a single opening for passing three electron beams. The single opening has a diameter larger in a horizontal direction than a diameter thereof in a vertical direction. Each of the focus electrode and the anode has a plate electrode placed therein and forming apertures for passing the three electron beams respectively. The focus electrode and the anode forms a main lens therebetween. The distance from the main lens to the phosphor screen is 360 mm or less, the outside diameter T in mm of the neck portion of the evacuated envelope housing the electron gun satisfies 23.5 mm.ltoreq.T.ltoreq.25.3 mm, the value D in mm of twice the distance from the center of a trajectory of a side electron beam to a vertical edge of the single opening in each of the focus electrode and the anode satisfies 6.5 mm<D.ltoreq.8.

Abstract: A color cathode ray tube includes an evacuated envelope formed of a panel portion having a phosphor screen, a neck portion and a funnel portion connecting the panel portion and the neck portion, and an in-line electron gun housed in the neck portion. The in-line electron gun includes a main lens and an electrostatic quadrupole lens. The focus electrode of the electron gun has a single opening at one end thereof for passing the three electron beams and opposes an anode to form a main lens therebetween. The single opening has a diameter larger in a horizontal direction than a diameter thereof in a vertical direction. A distance from the main lens to the phosphor screen is not larger than 300 mm, an outer diameter T of the neck portion housing the in-line electron gun satisfies the following inequality: 23.2 mm.ltoreq.T.ltoreq.25.

Abstract: An improved inline electron gun of the invention includes a plurality of electrodes spaced from three cathodes. The electrodes form at least a beam forming region and a main focus lens in the paths of three electron beams, a center beam and two side beams. The main focus lens is formed by the facing portions of two electrodes. The improvement comprises the facing portions of the main focus electrodes including a first part, and a second part positioned within the first part. The first part includes a single aperture therein. The second part includes three inline apertures therein. The first part includes four spaced ledges, and the second part is attached to the four ledges.

Abstract: A Focusing electrode in an electron gun for a color cathode ray tube provides a higher degree of freedom in electron gun design and reduces errors during assembly of the electron gun. A first focusing electrode that receives a constant voltage has vertically elongated electron beam pass-through holes formed in it. A second focusing electrode that receives a dynamic voltage has electron beam pass-through holes that include a pair of burring parts formed on their upper and lower edges. The burring parts are disposed in each of the vertically elongated electron beam pass-through holes in the first focusing electrode without changing a horizontal diameter of the electron beam pass-through holes in the first focusing electrode.

Abstract: A color cathode ray tube includes an in-line electron gun. The electron gun includes at least a tubular part which is composed of two (or more) folded portions which are secured to each other.

Abstract: In an electron gun for a cathode ray tube in which a focus electrode group includes a single platelike electrode having three apertures arrayed in one plane and a thickness equal to a depth of each of the three apertures, a tapered surface is formed on the entrance side and/or exit side of each of the three apertures, the tapered surface having a diameter larger than the aperture diameter and having a linear or curved shape in cross section, and a step which extends in the direction of the depth is formed around an aperture periphery of the tapered surface. With this constitution, the concentricity between each of the tapered surfaces and a respective one of the apertures can be measured with high precision on the basis of the boundary between each of the tapered surfaces and the corresponding one of the steps, thereby improving the precision of measurement of the concentricity between each of the apertures formed in the platelike electrode and the tapered surface formed around the aperture periphery.

Abstract: A color cathode ray tube has an evacuated envelope including a panel portion having a phosphor screen and a neck portion, and an in-line electron gun including a main lens and an electrostatic quadrupole lens and housed in the neck portion. The focus electrode of the main lens has a single opening at its one end for the three electron beams. The single opening has a diameter larger than a horizontal direction than that in a vertical direction. A distance from the main lens to the phosphor screen is not larger than 300 mm, an outer diameter T of the neck portion satisfies the following inequality: 23.2 mm.ltoreq.T.ltoreq.25.9 mm, and a value D of twice a distance from the side electron beams to a vertical edge of the single opening satisfies the following inequality: 50 mm.ltoreq.D.ltoreq.6.5 mm.

Abstract: An in-line electron gun for a color CRT includes a static electrode (39') applied with a static voltage, and a dynamic electrode (40') applied with a dynamic voltage. A side of the static electrode (39') facing toward the dynamic electrode (40') is formed with a common opening for the electron beams, and a plain electrode (21) having three apertures (20) is positioned inside the static electrode (39'). The dynamic electrode (40') has a pair of lens reinforcement partitions (38) having round horizontal partitions (41) disposed in a vicinity of the apertures (20) and has a curvature similar to that of the apertures (20), and linear partitions (42) formed integral with the round partitions (41) to provide a static facing side of the dynamic electrode (40') with a quadrupole effect. The in-line electron gun reduces the voltage difference of the peak-to-peak voltage of the dynamic voltage reducing the production cost of the dynamic voltage supply.

Abstract: An in-line electron gun for a color cathode ray tube is disclosed including a main focusing electrode and an accelerating electrode common for electron beams and having an elliptical aperture. An auxiliary electrode disposed within each of the main focusing electrode and accelerating electrode and being retreated from rims of the main focusing electrode and accelerating electrode, respectively. In addition, a shield cup is installed adjacent to the accelerating electrode, the shield cup having an aperture that is horizontally longer than vertically.

Abstract: Color cathode ray tube (1) device having an electron gun (6) of the in-line type for generating three electron beams (7,8,9), a display screen (10) and deflection coils (11) for scanning the electron beams over the display screen. The electron gun includes a main lens part for focusing the electron beams on the display screen, the main lens part comprising main lens electrodes (26, 27) having apertures for passing of the electron beams, at least one of said main lens electrodes comprising two sub-electrodes (26a, 26b) adjacent to each other, each of the sub-electrodes having a central (311, 321) and two outer apertures (312, 322, 313, 323), whereby in operation between the adjacent sub-electrodes an astigmatic quadrupole field is generated. For the central apertures of the sub-electrodes it holds:xQa.ltoreq.xQband for the two outer apertures of the sub-electrodes it holds:yQa.ltoreq.yQb.

Abstract: A color cathode ray tube has an evacuated envelope including a panel portion having a phosphor screen and a neck portion, and an in-line electron gun including a main lens and an electrostatic quadrupole lens and housed in the neck portion. The focus electrode of the main lens has a single opening at its one end for the three electron beams. The single opening has a diameter larger in a horizontal direction than that in a vertical direction. A distance from the main lens to the phosphor screen is not larger than 300 mm, an outer diameter T of the neck portion satisfies the following inequality: 23.2 mm.ltoreq.T.ltoreq.25.9 mm, and a value D of twice a distance from the side electron beams to a vertical edge of the single opening satisfies the following inequality: 5.0 mm.ltoreq.D.ltoreq.6.5 mm.

Abstract: An electron gun which has an assembly precision improved by the reduction of deformation of an electrode during assembly as well as good focusing performance due to the elimination of positional deviation of electron beams. The electron gun comprises a composite electrode including at least two electrode elements united together and a plurality of electrodes sequentially arrayed along a single axis at predetermined intervals. In the electron gun, opposed faces of the electrode elements of the composite electrode are perpendicular to the axis and the opposed faces are provided with projections which serve to constitute the composite electrode when the projections are united together in opposed relationship to each other.

Abstract: In a conventional construction of an electron gun with quadrupole lenses, a grid part with elongated apertures all arranged in the same direction cannot be easily secured to alignment mandrels of circular cross section. As a result, grid movement during assembly can cause a misalignment that deteriorates the tube resolution. The present invention includes arranging circular and elongated apertures in the same grid part, and also alternately arranging circular and elongated apertures in adjacent grid parts, so as to secure the grid parts to the mandrels and automatically maintain the alignment during gun assembly. The aperture combinations described herein produce electron lens astigmatism of approximately the same strength and sign for each beam of an in-line gun.

Abstract: A color cathode ray tube equipped with an electron gun having a main lens with a large equivalent aperture by suppressing spherical aberration and astigmatism of the main lens sufficiently. The main lens for converging the three electron beams, which are arranged generally in parallel in one direction toward the fluorescent face, upon the fluorescent face, includes two electrodes arranged to confront each other with such flattened apertures that the diameter H taken in the one direction is larger than a diameter V taken perpendicularly to the one direction. The orbits of the two side ones of the three electron beams passing through the main lens have a constant gap S from the orbit of the center electron beam. The relations of H=2(S+R) and R>S hold, if the distance between the orbits of the two side electron beams and the inner circumference, as taken in the one direction, of the electrodes constituting the main lens is designated at R.

Abstract: There is provided an electron gun which has an assembly precision improved by the reduction of deformation of an electrode during assembly as well as good focusing performance due to the elimination of positional deviation of electron beams. There is also provided a method of assembling such an electron gun. The electron gun comprises a composite electrode including at least two electrode elements united together and a plurality of electrodes sequentially arrayed along a single axis at predetermined intervals. In the electron gun, opposed faces of the electrode elements of the composite electrode are perpendicular to the axis and the opposed faces are provided with projections 1a and 1b which serve to constitute the composite electrode when the projections are united together in opposed relationship to each other.

Abstract: An electron gun for a color cathode-ray tube, adapted for large television sets or high-definition monitors, has first and second quadrupole electrodes connected to a static voltage focus electrode and to a dynamic voltage focus electrode, respectively, to form a quadrupole lens. The first quadrupole electrode is composed of first electrode pieces connected to the static voltage focus electrode and arranged on left and right sides of three beam-passing apertures formed on the static voltage focus electrode, and each of the first electrode pieces has at least one arc having a radius identical to or larger than that of the beam-passing apertures. The second quadrupole electrode is composed of second electrode pieces connected to upper and lower portions of the dynamic voltage focus electrode, and each of the second electrode pieces has arcs having a radius identical or larger than that of the beam-passing apertures. The first electrode pieces are inserted inside of the second electrode pieces.

Abstract: In an electron gun for a CRT in which a plurality of cylindrical electrodes are arranged and fixed in series to control a path of electron beams emitted from a cathode, a cylindrical support member is disposed between at least two adjacent cylindrical electrodes so that the two cylindrical electrodes are arranged coaxially. One end portion of the cylindrical support member and one cylindrical electrode are fixed to each other by fitting the former into the latter or vice versa, and the other end portion of the cylindrical support member and the other cylindrical electrode are fixed to each other by fitting the former into the latter or vice versa.

Abstract: In-line electron guns for color picture tube improving the resolution of the color picture tube. The guns not only exhibit the special quality of a large aperture of lens but also achieve the desired mechanical strength of electrodes by arranging .OR right.-shaped inner electrode plates in the envelope electrodes respectively. Each of first and second accelerating/focusing electrodes for focusing three electron beams of the electron beam sources on the phosphor screen includes an envelope electrode and an electrostatic field control electrode placed in the envelope electrode. The envelope electrode includes a predetermined length of hollow envelope part and a predetermined width of rim part extending from an edge of the hollow envelope part. The electrostatic field control electrode includes a plate electrode sided by predetermined width of blades at opposed sides thereof. This blade sided plate electrode is holed at its center so as to have a center beam passing opening.

Abstract: Disclosed is a color cathode ray tube equipped with a main electronic lens section for focusing a plurality of in-line electron beams on a screen section. The main electronic lens section includes a plurality of grids each having electron-beam through holes and securely supported by a plurality of insulating supports. At least one of the grids has a rectangular cup portion with a substantially rectangular cross section for commonly enclosing the plurality of in-line electron beams and a face having electron-beam through holes formed at least at one end and substantially perpendicular to the rectangular cup portion. The ratio of an outside diameter L.sub.H of the substantially rectangular portion in a long-axial direction to an outside length L.sub.S thereof in a short-axial direction, L.sub.H /L.sub.S, is set to 2.5<L.sub.H /L.sub.S <4.4, and the ratio of the outside length L.sub.S to a diameter D.sub.V of the electron-beam through holes in the same short-axial direction, L.sub.S /D.sub.V, is set to 1.

Abstract: A vacuum tube includes a ceramic element and a conductive element. A conductive connection consisting of a first layer containing silver and a filler and a second layer containing silver, gold or copper is formed between the ceramic element and the conductive element. The two above-mentioned layers are bonded together by means of diffusion bonding.

Abstract: A cathode ray tube has a gun electrode construction which elongates horizontally a cross section of an electron beam and whose elongating strength weakens as a focusing voltage increases.

Abstract: In an electron gun wherein an electric field which is established between the axially opposed parts of a pair of electrodes forming a main lens has a rotationally-asymmetric distribution; electric-field correcting plates (54, 65 in FIG. 1B) are provided in the respective electrodes (5, 6) so as to render a lens action on electron beams substantially rotationally symmetric. The electron beams form smaller spots on the fluorescent screen of a cathode-ray tube than in the prior art.

Abstract: An electrode structure of an electron gun for a cathode ray tube has a plurality of cathodes for emitting thermions, grid electrodes to form an electron beam of thermions, a first acceleration and focus electrode, a second acceleration and focus electrode and a dipole lens system which forms a circular beam spot on a screen of the cathode ray tube by removing the horizontal lengthening of the beam spot due to an increase in the amount of deflection of the beam in the peripheral portion of the screen of the cathode ray tube. The dipole lens system has a first electrode and a second electrode to which a dynamic voltage of a predetermined range is applied. The first electrode of the dipole lens system has opening portions which pierce the upper and lower sides of the first accelerator and focus electrode. The second electrode of the dipole lens system has horizontal plates which cover the opening portions with a predetermined gap.

Abstract: A cathode-ray tube has an electron gun sealed in a neck in confronting relationship to the phosphor screen. The electron gun comprises a cathode assembly for emitting three electron beams, a main lens region for passing the electron beams therethrough, the main lens means including a high-voltage electrode or grid closer to the phosphor screen, and an assembly of electrostatic deflection plates, positioned closer to the phosphor screen than the high-voltage electrode, for converging the electron beams as one spot on the phosphor screen. An electrostatic convergence electrode assembly is disposed between the high-voltage electrode and the deflection plates. The electrostatic convergence electrode assembly may comprise three or two juxtaposed flat electrodes having electron beam passage holes.

Abstract: An electron gun such as used in a cathode ray tube (CRT) includes an Einzel lens having charged G3, G4 and G5 grids for focusing an electron beam on the CRT's display screen. The G3, G4 and G5 grids are cylindrical and have the same inner diameter, with their respective longitudinal axes colinear and aligned with the electron beam axis. Where T is the thickness of a grid and L is the G3-G4 or G4-G5 spacing, or gap, shielding against stray electrostatic fields within the grids arising from stray electrons on either a grid-supporting glass bead or on the inner surface of the CRT's neck portion is provided by maintaining the relationship 3.0.gtoreq.T/L.gtoreq.0.75. Another embodiment employs thinner grids having a thickness t with outward turned end flanges, or folded edges, disposed about facing edges of adjacent grids having a thickness T, where T>t and the above-stated relationship of T/L is maintained.

Abstract: An electron gun for a color cathode ray tube having sequentially formed a cathode, a control electrode, a screen electrode, a focus electrode and a final accelerating electrode, wherein the focus electrode is constituted by first and second focus electrodes. The first focus electrode includes an evenly formed electron beam inlet plane and an electron beam outlet plane in which a portion for shaping a central electron beam passing hole is formed convexly in respect to portions for shaping outer electron beam passing holes, while the second focus electrode comprises an evenly formed electron beam outlet plane and an electron beam inlet plane in which a portion for shaping a central electron beam passing hole is formed concavely in respect to portions for shaping outer electron beam passing holes. The quadruple lens formed between outer electron beam passing holes is formed asymmetrically, to improve the convergence characteristic.

Abstract: An electron gun for a color cathode ray tube includes a last accelerating electrode having a large-caliber electron beam passing hole for commonly passing red, blue, and green electron beams. Both ends of the beam passing hole include circular arc portions formed with a predetermined curvature. The center portions where the green electron beam passes through protrude by a predetermined width. The length of the protrusion in the horizontal direction satisfies the following inequality: L<H-2R(1+cos .alpha.), where H designates the horizontal width of the large-caliber electron beam passing hole, R is the radius of the circular arc portions and .alpha. is the angle between a line drawn from either center of the circular arc portions to an adjacent apex of the protrusions and a line connecting centers of both circular arc portions.

Abstract: In a multi-focusing type electron gun in which first through eighth electrodes and a shield cup are provided, the sixth electrode which forms the center of a second unipotential lens is formed by a primary electrode and a corresponding secondary electrode. The center aperture of the primary electrode has a larger inside diameter than lateral apertures thereof, which is equal to the inside diameter of the lateral apertures of the secondary electrode. The center aperture of the secondary electrode has a comparatively smaller inside diameter than the lateral apertures thereof but which is equal to the inside diameter of the lateral apertures of the primary electrode, so that a voltage difference of the second unipotential lens becomes uniform to obtain an expanded focus lens.