Abstract: A multibeam electron gun comprises two spaced successive electrodes individually held in position from a common electrically-insulating support. One electrode comprises a single metal plate having at least three electron-beam defining first apertures therein. The other electrode is a composite structure comprising a support plate and a second metal plate having at least three electron-beam-defining second apertures therein. Each of the first and second plates includes substantially triangularly-shaped alignment apertures which are mutually aligned so that the beam-defining apertures are aligned along common axes.

Abstract: The present invention is an improvement in an electron gun for use in a cathode ray tube. Such gun includes at least one cathode and a plurality of electrodes spaced from the cathode. At least two of the electrodes form a main focusing lens and the electrode nearest the cathode which forms the main focusing lens includes extrusions about an aperture therein. The improvement comprises means located at the end of the gun opposite the cathode for blocking the exit from the gun of electrons emitted from the extrusions.

Abstract: A high definition page display system for graphics and text utilizing shaped beams in a CRT is disclosed. Information for the several lines which are written simultaneously is made available in parallel. The invention is described in terms of a character set and text generation, but the same principles apply to any other graphic or bit map and to storage in ROMs or loadable RAMs. Each beam of a multiple CRT tube is biased to generate a portion of a character or grahic as it scans across the tube. It takes 12 lines to scan a character with a N-beam tube, 12 over N character scans are therefore required. With the same scanning speed as with a single beam, this factor can be used to increase definition (i.e. number of lines.) Also the advantage of multiple beams can be used to reduce scanning speed, if this is useful to improve brightness or spot definition, or to increase the number of dots per line.

Abstract: An electron gun for a color picture tube is disclosed in which three parallel electron beams emitted toward a fluorescent screen and arranged so as to define one and the same plane are focused on the fluorescent screen by a main lens, electrodes constituting the main lens are spaced apart from each other, the electrodes include at least two envelopes and electrode plates disposed at the confronting end faces of the envelopes, each of the electrode plates has a single aperture for transmitting a central one of the electron beams, the path of each outer electron beam is surrounded partly by one of end portions of each electrode plate, and at least one of the electrode plates is placed in a corresponding one of the envelopes such that the electrode plate is recessed from the end face of the corresponding envelope confronting the other envelope.

Abstract: An electron gun assembly includes a plurality of cathode assemblies and a plurality of spaced successive electrodes mounted on at least two electrically-insulative support rods. At least one of the electrodes comprises a deep-drawn substantially rectangular cup-shaped member having a base portion, a supporting flange portion, including a plurality of attachment tabs, and a sidewall extending therebetween. The sidewall includes a plurality of reinforcing ribs formed therein which extend substantially from the supporting flange portion to the opposite end of the sidewall adjacent to the base. The reinforcing ribs minimize the flexure of the sidewall.

Abstract: A cathode-ray tube 10 with a deflection system 15 and an electron gun 14 having a magnetic ring 19 attached thereto is designed so that the magnetic ring 19 is not covered by the deflection system 15. To achieve this, the magnetic ring 19 is placed further to the back of the color-picture tube 10 than in conventional tubes, and/or the deflection system 15 is made shorter at the back. On an adjusting apparatus comprising both a magnetizing device and a deflection-system-positioning device, the magnetization of the magnetic ring and the positioning of the deflection system of such a tube 10 can be performed simultaneously and independent of each other. The measure can be taken on all tubes having a deflection system 15 and a magnetic ring 19 for adjusting the positions of at least two electron beams; in the case of color-picture tubes, color purity and static convergence are adjusted with such a ring.

Abstract: An improved color picture tube has an inline electron gun for generating and directing three electron beams, a center beam and two side beams, along coplanar paths toward a screen of the tube. The gun includes prefocus lens electrodes and main focus lens electrodes for focusing the electron beams. The main focus lens is formed by two spaced electrode members. The improvement includes the combination of features related to these two electrode members. One of the electrodes forming the main focus lens is an internal conductive coating on the neck. The other electrode includes three parts. First, there is a cylindrical portion that is smaller in diameter than the neck and is located in overlapped relation with respect to the conductive internal coating. Second, an apertured portion of the electrode includes three inline apertures which are aligned with the electron beam paths.

Abstract: An improved color picture tube has an inline electron gun for generating and directing three electron beams, a center beam and two side beams, along coplanar paths toward a screen of the tube. The gun includes a main focusing lens for focusing the electron beams. The main focusing lens is formed by two spaced electrodes, each having three separate inline apertures therein. Each electrode also includes a peripheral rim. The peripheral rims of the two electrodes face each other. The apertured portion of each electrode is within a recess set back from the rim. The recesses of the electrodes have substantially the same dimension perpendicular to the inline directions of the inline apertures as the dimension parallel to the inline direction of the inline apertures. However, the recesses have lesser dimensions along diagonals angled at approximately 45 degrees with respect to the inline direction of the inline apertures.

Abstract: In-line electron gun structure for color cathode ray tubes in which the final focusing and accelerating electrodes each employ three in-line tapered, partially overlapping apertures in facing relationship, and at least one pair of integral electron beam correctors associated with the central aperture of the focusing electrode. Such structure is produced by deep drawing a workpiece having an hour-glass shaped hole for each corrector pair desired.

Abstract: An improved color picture tube has an inline electron gun for generating and directing three electron beams, a center beam and two side beams, along coplanar paths toward a screen of the tube. The gun includes a main focus lens for focusing the electron beams. The main focus lens is formed by two spaced electrode members, each having three separate inline apertures therein, a center aperture and two side apertures. The improvement comprises each of the apertures in each of the focus lens electrodes having a shape that distorts a portion of the focus lens thereat, to at least partially compensate for an astigmatic effect within the tube that acts on an associated electron beam. The side apertures in both of the electrodes are nonsymmetrical about axes that pass through the respective side apertures and are perpendicular to the initial coplanar paths of the electron beams.

Abstract: An electron gun used in a color picture tube having means for emitting three electron beams toward the fluorescent screen, and main lenses for focusing the electron beams on the fluorescent screen. The main lenses are constituted by two envelopes spaced out from each other and adapted to surround the electron beams, and two electrode plates located on the confronting end surfaces of the envelopes and provided with three apertures aligning on a line for conducting the three electron beams. At least one of the two electrode plates is recessed relative to another electrode plate and disposed inside the envelope, and the recessed electrode plate is structured such that non-rotational symmetry of the lens caused by the recess of the electrode is corrected.

Abstract: A curved, electrically-conductive foil or gauze member is provided in a second cylindrical accelerating electrode of an electron gun for a cathode ray tube. The curvature of the foil or gauze member initially decreases with distance from the longitudinal axis of the electrode, thereby modifying the shape of the field produced by the electrode and minimizing spherical aberration. The curvature preferably varies according to a zero order Bessel function. Spherical aberration can be made negative by adjusting the relative positions of the member and nearby ends of the second and an adjacent first cylindrical accelerating electrode.

Abstract: A color picture tube includes a screen and an improved inline gun for generating and directing three inline electron beams along separate paths toward the screen. The improved electron gun has an asymmetric beam-forming region and an asymmetric main focus lens. The asymmetry of the main focus lens is matched with the asymmetry of the beam-forming region to focus substantially all portions of each of the beams at the screen.

Abstract: An in-line electron gun in a color TV cathode ray tube generates three coplanar electron beams. The raster pattern projected by the center beam is diminished in vertical height so as to be non-coextensive with the two off-axis beams. The gun is characterized by having two pairs of inwardly converging but non-intersecting magnetic field enhancer means, one of each pair being located at a point of beam egress and embracing in symmetrical relationship one of the off-axis beams. Each member of each of the pairs comprises an L-shaped bracket with the brackets defining an opening therebetween, with one leg of each bracket providing for attachment to the electrode. The brackets, the predetermined angle and distance, and their separation and length are such that the enhancer means is effective to divert the flux of the vertical deflection field through the openings between the enhancer means.

Abstract: Planar apertured shunts surrounding the outer apertures of the final convergence electrode of a color cathode ray tube electron gun, used for correction of the beam-deflecting magnetic fields associated with the outer electron beams, are captivated by apertured retaining means, having shunt-accommodating pockets surrounded by a peripheral seating rim affixed to the bottom of the convergence electrode.

Abstract: The invention relates to incorporating improved beam shielding means into the unitized focusing electrode structure of a plural beam in-line color cathode ray tube electron gun assembly. At least a portion of the G3 electrode structure is fabricated of a magnetic alloy material. Positioned forward and adjacent to the magnetic portion is an apertured planar shielding means also fabricated of magnetic material. The cooperation of these adjoining magnetic areas provides significant shielding of the beams from the deleterious back-field of the deflection yoke.

Abstract: The invention pertains to the achievement of improved lensing means employed in compact plural beam in-line CRT electron gun assemblies resulting in small round spot sizes on the screen. Such is effected by forming cooperating tapered apertures in a low potential lensing electrode and similar facing apertures in an adjacent high potential lensing electrode. The larger openings of the two sets of facing tapered apertures provide lenses of larger than normal dimensions. Additionally, partial overlapping of the apertures permits even larger lenses in the available electrode areas, thereby effecting further improved lensing of the beams.

Abstract: In-line electron gun structure for color cathode ray tubes in which the final focusing and accelerating electrodes each employ three in-line tapered, partially overlapping apertures in facing relationship, and at least one aperture opening, preferably the central aperture of the focusing electrode, is elongated to provide electron beam spot-shaping.

Abstract: An electron gun having arc suppression means is described. In one of the preferred embodiments of the electron gun, at least one cathode is provided for generating an electron beam along a beam path. A plurality of electrodes are serially disposed along the beam path. The electrodes include at least one low voltage electrode and at least one high voltage electrode. A plurality of resistors interconnect selected ones of the electrodes. The interconnected electrodes normally operate at substantially the same voltage, and the resistors act as a voltage divider in the event of an arc and prevent damaging cascading arcs.

Abstract: An inline electron gun, for use in a cathode-ray tube, comprises four electrode means. The first electrode means forms three inline electron beams including a center beam and two outer beams. The second electrode means pre-focuses each of the electron beams individually and converges the two outer beams toward the center beam to cross-over each other within the electron gun. The third electrode means provides a common main focus lens for the three electron beams at the crossover of the beams. And, the fourth electrode means provides a common post-focusing lens for the three electron beams which causes the two outer beams to converge with the center beam near a screen of the tube.

Abstract: An inline electron gun for a cathode-ray tube includes a plurality of cathodes, a control grid, a screen grid and a main focus lens arranged successively in alignment with the cathodes for focusing a plurality of electron beams onto a screen. The screen grid has a given thickness with a plurality of transverse slots formed therein. The slots have a depth less than the thickness of the screen grid. An aperture is formed in each of the slots. The outer slots are asymmetric with respect to the apertures therein and are displaced transversely toward the center aperture. The transverse slots in the screen grid compensate for the vertical flare distortion of the beam spot at off-center positions on the screen and the asymmetric location of the outer slots reduces the horizontal convergence sensitivity of the outer beams with respect to focus voltage change.

Abstract: An inline electron gun for a cathode-ray tube includes a plurality of cathodes, a control grid, a screen grid and a main focus lens arranged successively in alignment with the cathodes for focusing a plurality of electron beams along beam paths onto a screen. The screen grid has a functional grid area with a given thickness. A recessed portion is formed within the functional grid area. A plurality of apertures are formed within the recessed portion of the screen grid. The recessed portion is surrounded by a peripheral rim which is in proximity to the outer apertures thereby affecting the electrostatic field in the vicinity of the outer electron beam paths.

Abstract: In-line electron gun structure for color cathode ray tubes in which the final focussing and accelerating electrodes each employ three in-line tapered, partially overlapping apertures in facing relationship, and at least one pair of electron beam spot-shaping inserts associated with the central aperture of the focussing electrode.

Abstract: An electron gun for a high resolution color display tube comprises three inline cathode assemblies, a control grid with three inline apertures, a screen grid with three inline apertures and slots at each aperture on a side facing away from the control grid, a first focusing electrode having three inline apertures facing the screen grid and three inline apertures facing away from the screen grid, and a second focusing electrode having three inline apertures facing the first focusing electrode. The diameters of the control grid apertures are in the range of 0.43 mm to 0.59 mm. The screen grid is spaced 0.13 mm to 0.26 mm from the control grid. The diameters of the screen grid apertures are in the range of 0.43 mm to 0.59 mm, and their thickness is in the range of 0.20 mm to 0.31 mm. The ratio of the depth of the slots in the screen grid to their widths is in the range of 0.13 to 0.23. The diameters of the apertures in the facing portions of both focusing electrodes are in the range of 4.06 mm to 5.

Abstract: An electron gun comprises at least one cathode for generating an electron beam along a beam path and a plurality of electrodes serially disposed along the beam path. The electrodes include at least one accelerating and focusing electrode having two spaced-apart electrode sections axially separated along a plane substantially perpendicular to the beam path. An arc-suppression resistor interconnects the spaced-apart electrode sections of the electrode. The interconnected electrode sections normally operate at substantially the same voltage. The arc-suppression resistor acts in the event of an arc to limit the arc current and prevent damaging cascading arcs.

Abstract: An inline electron gun in a color picture tube is improved by the addition of two slots that are spaced sufficiently close to and inward from the two apertures in a portion of the screen grid electrode facing an accelerating and focusing electrode. The slots cause a distortion of the electrostatic field formed between the two electrodes at the two apertures. The field distortion compensates for an opposite distortion within the main lens of the electron gun.

Abstract: A cathode-ray tube has in a neck section of a hermetically sealed, evacuated envelope an electron-gun mount assembly in which of a cathode for emitting an electron beam, a first grid electrode section for forming a crossover point and for accelerating the electron beam and a second grid electrode section for focusing the electron beam are mounted on a plurality of insulative supporting bars. A conductive member is provided on an outer surface portion of the neck section, an inner surface portion thereof, and/or an outer surface portion of the supporting bars which surround a portion of the electron-gun mount assembly including the first grid electrode section but excepting the second grid electrode section.

Abstract: An electron gun system for a three beam color display tube. Slot-shaped openings are provided in the sides of cup-shaped focusing electrodes of the system to facilitate alignment during assembly. The electrodes are stacked on a jig having a pin passing through central electron beam apertures of the respective electrodes. Arms having V-shaped ends are then passed through the slot-shaped openings until they engage collars of the electrodes which define the apertures in the respective electrodes.

Abstract: An electron gun for a color picture tube comprises opposing cup-shaped electrodes each having a plurality of openings laterally aligned in a row, the electrodes being combined such that the openings face each other to form electron lenses. The openings are formed in flat bottom walls of said electrodes, a width of a bridge portion between adjacent openings is 0.5 to 1.5 times a thickness of the bottom wall of each electrode, and corrective plate electrodes are arranged to oppose bridge portions with a predetermined distance therefrom. The electrodes are combined such that spherical aberration of said electron lenses as a whole can be reduced when one of the electrodes is applied with a voltage which is higher than that applied to the other.

Abstract: A magnetic focusing type cathode ray tube includes a magnetic yoke assembly, for magnetically focusing and converging three in-line electron beams, having a pair of magnetic yokes opposing each other with a predetermined gap therebetween. The magnetic cylinders on the cathode side are so formed as to have a strong magnetic shield effect while the magnetic cylinders on the screen side are weak in magnetic shield effect. The radial components in the magnetic field produced in the magnetic gap, which act on the side beams in a direction perpendicular to an in-line direction, are reverse in polarity on the cathode side and screen side so that radial components emerge so as to converge the beams in a tube axis direction.

Abstract: The electrodes of an electron-gun system of a color-picture tube are heated less as their distance from the cathode of the system increases. The electrode materials are so chosen with respect to their coefficients of expansion that no mechanical stresses are caused in the system structure despite the different temperatures.

Abstract: An electron gun having at least one arc-suppression resistor located in a zero electric field gradient area of the electron gun is described. In the electron gun, at least one cathode is provided for generating an electron beam. A plurality of electrodes are also provided for directing the beam along the beam path. The electrodes include at least one accelerating and focusing electrode which is a split member having two spaced apart sections. The electron gun also includes at least one arc-suppression resistor which interconnects the spaced apart sections of the split electrode and is located in a zero electric field gradient area of the split member.

Abstract: A magnetic focusing type cathode ray tube comprising a magnetic focusing device positioned in front of a three beam in-line type cathode for focusing the electron beam emitted from the cathode. The magnetic focusing device is constructed of a magnetic yoke assembly having a pair of magnetic yoke members. Each magnetic yoke member has three cylindrical magnetic yoke portions through which an electron beam can pass, and one common cylindrical magnetic yoke portion having a larger diameter which completely surrounds the three electron beam passages. The cylindrical magnetic yoke portions of the yoke members are spaced equidistantly, facing each other in the electron beam passages.

Abstract: A color picture tube with an in-line multi-stage focusing type electron gun assembly which can suppress generation of spark discharges and which can be improved in withstand voltage characteristics. The electron gun assembly comprises a metallic shielding member facing the fluorescent screen and maintained at the anode potential. The shielding member is displaced, in the direction of a tube axis and toward the base, from an edge facing the base of an inner graphite coating formed on the inner wall of the neck tube by a predetermined distance or more. The metallic shielding member shields electrostatically the edge of the inner graphite coating from the grid electrodes and cathode electrode close to the base and at lower potentials. At least one of focusing voltage feed conductors for third and fifth grid electrodes is wired so as to run through a gap between the inner wall of the neck tube and a bead glass for supporting the electrodes of the electron gun assembly.

Abstract: An improved in-line type electromagnetic focusing cathode-ray tube which comprises magnetic yokes, a focusing magnetic field generating permanent magnet, a deflecting magnetic field control element and a cup-shaped spacer member for separating the magnetic yokes from the deflecting magnetic field control element. The deflecting magnetic field control element is disposed at a distance l.gtoreq.0.26 D from an end of the magnetic yoke closest to a fluorescent screen, where D is an outer diameter of the magnetic yoke, so that a beam spot on the fluorescent screen has substantially circular shape to attain an excellent focusing characteristic.

Abstract: An auxiliary grid which is formed with one or more elongated slits through which pass electron beams is disposed in a prefocusing system in a cathode-ray tube, and a dynamic voltage which varies in level with increase in horizontal deflection angle is applied to the auxiliary grid so that axial asymmetry of the prefocusing system can be increased with increase in the horizontal deflection angle. As a consequence, the beam spot can be maintained substantially in the form of a true circle not only at the center of the screen but also at the portions adjacent to the peripheries thereof. Thus, the resolution at the portions adjacent to the peripheries of the screen can be improved and consequently high-quality images can be represented over the whole surface of the screen.

Abstract: In a device for displaying pictures with a display tube and a self-converging system of deflection coils, the focusing in the direction in which the focusing is substantially independent of the deflection by the system of the deflection coils is effected by means of two quadrupole lenses and in the direction at right angles thereto by the focusing lens. This makes it possible to use dynamic focusing in said latter direction without defocusing in another direction and to obtain a sharp spot all over the screen. By providing an octupole lens coaxially around the electron beam and the center of the focusing lens it also becomes possible to reduce the spherical aberration.

Abstract: A color television picture tube of three in-line gun type wherein a ring-shaped ferrite permanent magnet or magnets are disposed around a neck portion of the tube, at least a pair of mutually-opposing pole pieces made of highly permeable magnetic material are provided within the tube neck portion as a part of the gun assembly so as to be magnetized by the ring magnet or magnets and to form an electron beam magnetic focusing lens system. In the picture tube, the pole pieces are each of a substantially elliptical cross section as viewed from a plane perpendicular to the tube axis, and spaces are provided between an inner wall of the tube neck portion and the pole pieces to accommodate support rods for gun assembling.

Abstract: An inline electron gun in a color picture tube is improved by the addition of two slot apertures that are spaced sufficiently close to and outward from the two outer apertures in a portion of a focusing electrode facing a screen grid electrode to cause a distortion of the electrostatic field formed between the two electrodes at the two outer apertures. The electrostatic field distortion causes two outer electron beams to converge toward a center electron beam.

Abstract: In an electron gun that includes a cathode, a control grid, a screen grid and at least two main focus lens electrodes, an improvement comprises the screen grid including a first portion having a circular aperture, a second portion having at least one elongated aperture and a third portion having a circular aperture. The first and third portions are electrically insulated from the second portion.

Abstract: An electromagnetic focusing cathode-ray tube in which plural pairs of magnetic material members are arranged within the tube along the tube axis, the magnetic material members in each pair are disposed to oppose each other in the direction of the tube axis with a gap defined therebetween, and the plural magnetic material member pairs and one or more permanent magnet disposed internally or externally of the tube are combined such that magnetic focusing fields having their senses or directions opposite to each other in the direction of the tube axis are formed at the respective gaps associated with the adjacent magnetic material pairs.

Abstract: An improvement is made in a color picture tube having an inline electron gun for generating and directing a plurality of electron beams along coplanar paths toward a screen of the tube. The gun includes a main focus lens for focusing the electron beams which is formed by two spaced electrodes. Each electrode includes a portion having a plurality of apertures therein equal to the number of electron beams. Each electrode also includes a peripheral rim. The peripheral rims of the two electrodes face each other and the apertured portion of each electrode is within a recess set back from the rim. The improvement comprises the depths of the apertures in the electrodes being equal to the thickness of material of the electrodes. This aperture structure permits greater penetration of the electrostatic lines of the main focus lens into the electrodes behind the apertured portions of the electrodes. This penetration of electrostatic lines provides a converging field for off-axis electron beams.

Abstract: A television camera tube with electrostatic focusing comprising a triode section at the first stage having a cathode a first grid and a second grid, an electrostatic focusing lens section at the next stage having a third, fourth and fifth grids of cylindrical electrode configuration, and a sixth grid with mesh electrode configuration at the last stage, these electrodes being coaxially arranged in a cylindrical glass envelope, the length of the fourth grid is greater than 1.15 times the inner diameter thereof but equal to or smaller than 2.30 times the inner diameter thereof.

Abstract: An improved beam focusing structure, in the form of overlapping lenses, is incorporated into the forward portion of the unitized main focusing electrode of a compactly-dimensioned CRT three-beam in-line electron gun assembly. Such is accomplished by forming a common, elongated and configurated focusing electrode aperture to accommodate passage of the three beams therethrough. A pair of planar wall elements, spatially positioned in the aperture, to define the three lenses, have concave arcuately shaped forward edges formed in acccordance with the spacing between the focusing electrode and an adjacent plural apertured accelerating electrode.

Abstract: An electron gun for use in a cathode ray tube includes beam forming electrodes and beam focusing electrodes. A gun improvement comprises the beam forming electrodes including a cathode, a control grid adjacent to the cathode and two screen grids. A first screen grid is located adjacent to the control grid. A second screen grid is located between the first screen grid and the beam focusing electrodes. Preferably, the second screen grid and the control grid are grounded.

Abstract: An improved color picture tube has an inline electron gun for generating and directing three electron beams, a center beam and two side beams, along coplanar paths toward a screen of the tube. The gun includes a main focus lens for focusing the electron beams. The main focus lens is formed by two spaced electrode members each having three separate inline apertures therein. Each electrode also includes a peripheral rim. The peripheral rims of the two electrodes face each other. The apertured portion of each electrode is within a recess set back from the rim. The main focus lens electrode closest to the screen includes a slot on the side facing the screen. The slot extends in the direction of the three electron beam paths.

Abstract: An improved color picture tube has an inline electron gun for generating and directing three electron beams, a center beam and two side beams, along coplanar paths toward a screen of the tube. The gun includes a main focus lens for focusing the electron beams. The main focus lens is formed by two spaced electrode members each having three separate inline apertures therein. Each electrode also includes a peripheral rim. The peripheral rims of the two electrodes face each other. The apertured portion of each electrode is within a recess set back from the rim. The width of the recess in at least one of the electrodes is wider at the center beam path than at the side beam paths, measured perpendicular to the plane containing the electron beam paths.

Abstract: In a picture tube comprising an envelope including a phosphor screen and an electron gun generating an electron beam, wherein the electron beam is deflected by magnetic deflecting fields, the electron gun comprising a triode section and a focusing section along a path of the electron beam, the triode sections being provided with an electrode containing a non-circular aperture having major and minor axes of symmetry, the major axis being parallel to a horizontal direction the focusing section having a means for forming an electrostatic focusing lens having a vertical focal length and a horizontal focal length, said vertical focal length more elongated than said horizontal focal length.

Abstract: A novel apparatus and method for focussing beams of charged particles comprising planar arrays of electrostatic quadrupoles. The quadrupole arrays may comprise electrodes which are shared by two or more quadrupoles. Such quadrupole arrays are particularly adapted to providing strong focussing forces for high current, high brightness, beams of charged particles, said beams further comprising a plurality of parallel beams, or beamlets, each such beamlet being focussed by one quadrupole of the array. Such arrays may be incorporated in various devices wherein beams of charged particles are accelerated or transported, such as linear accelerators, klystron tubes, beam transport lines, etc.

Abstract: An improved color picture tube has an inline electron gun for generating and directing three electron beams, a center beam and two side beams, along coplanar paths toward a screen of the tube. The gun includes a main focus lens for focusing the electron beams. The main focus lens is formed by two spaced electrode members each having three separate inline apertures therein. Each electrode also includes a peripheral rim. The peripheral rims of the two electrodes face each other. The apertured portion of each electrode is within a recess set back from the rim. The width of the recess in at least one of the electrodes is wider at the side beam paths than at the outer beam path, measured perpendicular to the plane containing the electron beam paths.