Abstract: A cathode ray tube includes an evacuated envelope having a panel portion having a phosphor screen, a neck portion and a funnel portion connecting the panel portion and the neck portion; an electron gun housed in the neck portion having a cathode, a first grid electrode, a second grid electrode, plural focus electrodes and an anode arranged in the order named and fixed in predetermined axially spaced relationship by two glass beads; a voltage-dividing resistor attached to one of the two glass beads for producing an intermediate voltage to be applied to a first one of the plural focus electrodes adjacent to the anode by dividing a voltage applied to the anode; and a metal conductor facing and attached to a second one of the plural focus electrodes to surround the voltage-dividing resistor and the one of the two glass beads, the second one of the plural focus electrodes being disposed upstream of the first one of the plural focus electrodes.

Abstract: There is provided a cathode ray tube capable of displaying high quality images by suppressing eddy current from occurring and by realizing the velocity modulation. A cylindrical focusing electrode is divided into first cylindrical focusing electrode 4B and second cylindrical focusing electrode 4T and the gap between the both electrodes formed and divided by optimizing the length of the second cylindrical focusing electrode 4T in the tube axial direction is enlarged substantially to increase the infiltration of the velocity modulating magnetic field to the non-electric space of the focusing electrode 4. An electrode 4a having the equal potential with the focusing electrode 4 is disposed at the gap to suppress eddy current from being generated.

Abstract: A display device comprising a deflection unit and a cathode ray tube having an in-line electron gun. The electron gun comprises a main lens portion having means for generating a main lens field and a quadrupole field. During operation, the intensity of said fields is dynamically varied. The electron gun comprises a prefocusing lens portion having means for generating a prefocusing lens field and a further quadrupole field. During operation, the intensity of said fields is controlled in such a way that, in operation, the first quadrupole field and the main lens cause a dynamically converging effect in a direction parallel to the in-line plane, and the second quadrupole field and the prefocusing lens cause a dynamically diverging effect in a direction parallel to the in-line plane, the dynamically converging effect compensating the dynamically diverging effect in the direction parallel to the in-line plane. By virtue thereof, an improved picture reproduction can be obtained.

Abstract: A color CRT is driven by focusing and accelerating an electron beam emitted from a cathode by forming electron lenses including a quadrupole lens by applying a predetermined voltage to the cathode of an electron gun installed in a neck portion of a funnel and each of electrodes, focusing the electron beam on a fluorescent film by applying a voltage having a horizontal dynamic waveform having a ratio of slopes of 6.85 or more between a unilateral area of 90% and a unilateral area of 50% of a raster area to which a video signal of an image is applied, to at least one of the electrodes forming the quadrupole lens, synchronized with a horizontal deflection signal of a deflection yoke installed at a cone portion of the funnel, in order to deflect an electron beam emitted from the electron gun and scan the deflected electron beam onto the fluorescent film of a panel sealed to the funnel, and forming an image by having the deflected electron beam land on the fluorescent film and excite the fluorescent film.

Abstract: In the electron gun assembly of a cathode ray tube, a main electron lens portion is formed by a fifth grid to an eighth grid, and incorporates a quadrupole lens. The fifth grid receives a voltage obtained by superposing, on a voltage as a reference voltage, a dynamic voltage that parabolically changes with an increase when the electron beam is deflected amount of the electron beam. The sixth grid receives a voltage obtained by superposing, on a voltage as a reference voltage, a dynamic voltage that parabolically changes with an increase when the electron beam is deflected amount of the electron beam. The seventh grid receives the voltage, while the eighth grid receives an anode voltage.

Abstract: A colour display device (19) is disclosed having an improved focus performance. In state-of-the-art colour display tubes, a static voltage is applied to the focusing electrode (23). This means that only one focus voltage is available for the entire range of beam currents. In general, due to the fact that the diameter of the electron beams (7,8,9) increases as the beam current increases, the focus voltage is a function of this beam current, which itself is determined by the cathode voltage. In this invention, a colour display device (19) is disclosed in which the voltage on the focusing electrode (23) is changed as a function of the cathode voltages, thereby significantly improving the focus performance.

Abstract: A color cathode ray has an electron gun which includes three cathodes for emitting three in-line electron beams and a plurality of electrodes fixed in a predetermined axially spaced relationship on insulating supports. At least one of the plurality of electrodes is cup-shaped and has a correction electrode therein, and edges of the correction electrode are formed with recesses and sloped portions. A distance L from a mouth of each of the recesses of the correction electrode to an inner wall of the at least one of the plurality of electrodes satisfies the following relationship: L′≦L≦15 &mgr;m, where L′ is a height of a burr caused in press-forming of the recesses.

Abstract: In an inline type electron gun incorporated in a color cathode ray tube, a plurality of electron beams are produced from each of cathodes. A plurality of beam apertures are formed, per cathode, in a first grid and a second grid of the electron gun. The second grid consists of a plurality of split grids spaced apart from each other in the traveling direction of electron beams. The beam apertures formed in at least one of the split grids constituting the second grid are positionally eccentric to the beam apertures formed in another split grid. A voltage of a waveform synchronized with a deflection period is impressed from a circuit in a display apparatus to at least one of the split grids constituting the second grid. And the electron lens effect of the second grid is changed in accordance with the impressed voltage waveform, thereby correcting the positional deviation of the plural electron beams caused in the peripheral area of a fluorescent screen.

Abstract: An electron gun is provided for a CRT. The electrode gun includes three cathodes for emitting electron beams, a plurality of acceleration electrodes, and a focus electrode and an anode.

Abstract: Electron gun in a CRT including a main lens electrode having a focus electrode and an anode for focusing electron beams emitted from cathodes onto a screen, an electrostatic field controlling body fitted in each of the focus electrode and the anode each having three electron beam pass through holes, wherein each of outer holes in the electrostatic field controlling body fitted to each of the focus electrode and the anode has a form of a combination of a circle and a rectangle with reference to a vertical axis through a center of the hole in a direction opposite for facing outer holes of the focus electrode and the anode, thereby enlarging a main lens diameter, and providing a spot substantially circular and smaller.

Abstract: An electron gun assembly in a cathode-ray tube apparatus includes a quadrupole lens that is created in accordance with deflection of electron beams. The quadrupole lens is created by two mutually opposing grids. The two grids have non-circular electron beam passage holes in their mutually facing surfaces. Each electron beam passage hole has a waist portion which minimizes a horizontal or vertical dimension of a region for passing the associated electron beam.

Abstract: A color cathode ray tube equipped with an in-line electron gun comprising three cathodes for emitting three electron beams of an in-line arrangement toward a fluorescent screen, and a main lens for focusing the aid three electron beams on the fluorescent screen. The main lens includes a first main lens electrode and a second main lens electrode arranged in a spaced relationship in a direction of an axis of the tube and having different voltages applied thereto. Each of the first and second main lens electrodes have a single opening common to the three electron beams at opposing ends thereof, and at least one of the first main lens electrode and the second main lens electrode have therein three apertures for electron beam passage which are set back from the opposing ends, wherein T and S have values in the region where the following inequalities are satisfied, 2 S +14.6≦T ≦28.1, and 4.

Abstract: A color display device comprises an electron gun, a display screen and a flat color selection electrode as well as a deflection means. The distance between the electron beams is dynamically varied, whereby the distance in the deflection space decreases as the beams are deflected in at least one direction. The reduction of the distance enables the distance between the color selection electrode and the display screen to be increased in that direction. As a result, the curvature of the inner surface of the color selection electrode may be increased, which has a positive effect on the strength and doming behavior of the color selection electrode.

Abstract: A color picture tube has an electron gun assembly directed to a shadow mask spaced from a fluorescent screen by a predetermined distance in the bulb thereof, and a high voltage is supplied through a conductive layer formed on the inner surface of the bulb and a bulb spacer to an accelerating electrode of the electron gun assembly, wherein the contact resistance between the conductive layer and the bulb spacer is reduced to be equal to or less than 1 kilo-ohms so that the accelerating electrode is free from electrical influence of parabola voltage applied to a focusing electrode, whereby an undesirable lens is prevented and, accordingly, the electron beams are not deviated from the target trajectories.

Abstract: A color cathode ray tube having at least an electron gun, constituted by a cathode for forming a plurality of electron beams arranged in-line, and a focusing electrode and an anode constituting a main lens for focusing and accelerating the electron beams and a fluorescent screen. The focusing electrode includes at least a first division electrode and a second division electrode arranged with a gap for controlling a scanning speed of the electron beams in common. The second division electrode is opposed to the anode and has, in an opposed surface thereof, a single opening for passing the plurality of electron beams in common. A length of the first division electrode in the axial direction of the tube is longer than a length of the second division electrode in the axial direction of the tube.

Abstract: Single beam color CRT of the beam tracking type having a display screen comprising a plurality of parallel phosphor lines, the CRT being equipped with a Distributed Main Lens type electron gun. The distributed main lens has a plurality of oblong grids which each have a single, oblong, beam passing aperture. The longitudinal axes of the grids and of the apertures are transverse to the direction of the phosphor lines. Correction means are provided to compensate for the astigmatism introduced by the main lens.

Abstract: A cathode-ray tube that has an electron gun including a final-stage main lens made up of a last accelerating electrode and a focusing electrode and having a focus action stronger in horizontal direction than in vertical direction, an electron lens of a first kind formed between the divided focus electrodes and having a focus action stronger in the vertical direction than the horizontal direction to vary the cross sectional shape of an electron beam with an increase of the deflection amount, an electron lens of a second kind formed between the divided focus electrodes for weakening the lens strength with an increase of the deflection amount of an electron beam, and an electron lens of a third kind made up of at least one electrode constituting a three electrode section and having a focus action stronger in the horizontal direction than in the vertical direction. The dynamic focus voltage which decreases with an increasing deflection amount is reduced.

Abstract: A free space electron switch is disclosed. The switch, which is useful in high speed telecommunications traffic, has an array of cathodes for emitting free space electrons. A grid of aiming anodes and, a focusing grid for forming electrons from the cathode into an electron beam are provided. A plurality of output ports for receiving the electron beam from each cathode is provided, the output ports having a phosphor coating facing the side of the channel remote from the cathode.

Abstract: An electron gun assembly forms an electron beam generator, pre-focusing lens, sub-lens, and main lens. The sub-lens has a weaker horizontal focusing power than the vertical one, and the main lens has a stronger horizontal focusing power than the vertical one. When the electron beam is not deflected, a first quadrupole lens is formed between the pre-focusing lens and sub-lens, and a second quadrupole lens is formed between the sub-lens and-main lens. At least one grid forming each of the first and second quadrupole lenses receives a dynamic focusing voltage which parabolically changes in synchronism with the deflection magnetic field and becomes higher when the electron beam is deflected than when it is not deflected.

Abstract: A display apparatus including a CRT provided with an electron gun having a focusing electrode which is applied with a dynamic focusing voltage for focusing electrons drawn from a cathode of the CRT is disclosed. The display apparatus includes a dynamic focusing circuit for producing the dynamic focusing voltage by superimposing, on a dc voltage supplied from outside, an ac voltage which has a waveform varying in synchronization with horizontal and vertical deflections of an electron beam flowing to a fluorescent screen on the anode. The display apparatus further includes a compensator for lowering the dc voltage supplied to the dynamic focusing circuit by a predetermined value while a brightness signal indicative of brightness of a screen of the CRT exceeds a threshold value.

Abstract: An intermediate electrode at a middle voltage which takes a value between a focusing voltage and an anode voltage is disposed between a focusing electrode and an anode of an in-line type electron gun. The intermediate electrode has a single opening whose diameter in the horizontal direction (in-line direction) is greater than the diameter thereof in the direction perpendicular to the horizontal direction so as to allow three electron beams to pass therethrough. The intermediate electrode also has a plate electrode provided therein with three electron beam apertures which respectively allow three electron beams to pass therethrough. Inside of the focusing electrode, a plate electrode provided with three electron beam apertures is provided.

Abstract: An electron gun for a cathode ray tube includes a triode having cathodes, a first grid and a second grid, one or more third grids through which electron beams emitted from the cathode pass, a fourth grid opposing the third grids and forming a main focus lens with the third grid, a shield cup connected to the fourth grid and supplying a high voltage to the fourth grid, and a correction grid disposed between the fourth grid and the shield cup and having R, G, and B beam through holes arranged along a line. The R and B beam through holes have openings with asymmetrical shapes that are symmetrical with respect to each other and relative to the straight line, balancing astigmatisms and improving resolution.

Abstract: A focus electrode is constituted by a first type of focus electrode group to which a first focus voltage is applied, and a second type of focus electrode group to which a second focus voltage is applied. Between the first type of focus electrode group and the second type of focus electrode group are formed a lens at least having a lens action for correcting the field curvature and an electrostatic quadrupole lens. The center axes of the outer electron beam passage holes in the first type of focus electrode forming the lens at least having a lens action for correcting the field curvature are deviated on a horizontal plane from the center axes of the outer electron beam passage holes in the second type of focus electrode. The electrostatic quadrupole lens produces dissimilar intensities for the outer electron beams and for the center electron beam.

Abstract: A color cathode-ray tube including a main lens section comprising an anode to which an anode voltage is applied, and a focus electrode. The focus electrode has first type of focus electrode group to which a first focus voltage is applied, and a second type of focus electrode group to which a second focus voltage is applied which is obtained by superposing on a predetermined voltage a voltage that changes depending upon the deflecting amount of the electron beams. Between the first type of focus electrode group and the second type of focus electrode group are formed in a dynamic lens and an electrostatic quadrupole lens. Three electron beam passage holes are formed in the electrodes that form the dynamic lens and the centers for the outer electron beam passage holes in the first type of focus electrode group are deviated relative to the centers of the outer electron beam passage holes in the second type of focus electrode group in the horizontal direction.

Abstract: A color cathode ray tube has an electron gun in its neck portion. The electron gun includes plural focus electrodes and an anode fixed in axially spaced relationship by two support rods. The electron gun also includes a voltage-dividing resistor for producing a voltage applied to a first focus electrode by dividing a voltage applied to the anode, and a metal conductor surrounding the resistor and fixed to a second focus electrode upstream of the first focus electrode. The resistor is disposed in the vicinity of one of the support rods, is formed of an insulating film, a resistance pattern, and a substrate disposed in the order named from the insulating film toward the neck portion. The resistance pattern is such that a potential difference between the metal conductor and a portion of the resistance pattern facing the metal conductor is equal to or smaller than 4 kV.

Abstract: An inline electron gun includes three inline cathodes arranged in a same plane, a prefocus lens and a main focus lens which includes a plurality of electrodes for converging or diverging a thermion emitted by the cathodes to form electron beams. Focus lenses include a rim or a lip at opposite ends to form a large aperture. The main focus lens may include a focus electrode, an anode electrode and a subsidiary electrode arranged between the focus electrode and the anode electrode to define a beam course of respective red, green and blue electron beams. The focus electrode has symmetrical rectangular slots in its wall to define a green aperture of the subsidiary electrode, whereby the slots decrease influence of the electric field to the electron beam passing through the green aperture so that the red, green and blue spots on the screen have a uniform vertical diameter.

Abstract: The present invention provides a method of carrying out an electric discharge processing to an electron tube having a field emission cold cathode device, wherein at least a high voltage electrode of the electron tube is maintained in a high voltage range, whilst all electrodes of the electron tube except for the at least high voltage electrode are maintained in a lower voltage range than the high voltage range.

Abstract: For use in a beam index color cathode ray tube (CRT), a multi-beam group electron gun directs first and second groups of vertically aligned electron beams on respective parallel, horizontally aligned color phosphor stripes on the CRT's display screen. Each group of electron beams includes three beams, one for each of the three primary colors of red, green and blue. The first and second electron beam groups are horizontally offset from one another, with the upper, intermediate and lower electron beams in each group tracing the same horizontal phosphor stripe as the beams scan the display screen and with a time delay provided to synchronize the video information of both electron beam groups. A color video signal is provided either to a respective cathode or to a respective segmented conductive portion containing a beam passing aperture in the electron gun's G1 control grid for individually modulating each beam with color video image information.

Abstract: A cathode ray tube includes a phosphor screen, an electron gun having a plurality of electrodes, a deflection device, and a plurality of magnetic pieces being disposed on opposite sides in a direction of scanning line of an electron beam of a trajectory of and undetected electron beam in a magnetic deflection field generated by the deflection device. The plurality of magnetic pieces have a portion extending in a direction of an axis of the cathode ray tube on each of the opposite sides. The portion includes a pair of parts disposed above and below a plane containing the axis and the scanning line and having a first axial length greater than a second axial length of the portion as measured in the plane.

Abstract: A main lens of an electron gun assembly comprises a sixth grid, a seventh grid, an eighth grid, and a ninth grid. An asymmetric lens section is created between a fifth grid and the sixth grid on a cathode side of the main lens. The asymmetric lens section has such asymmetry that lens functions of the asymmetric lens section acting on the electron beams are different between the horizontal direction and the vertical direction, and has a lens power varying in synchronism with the deflection of the electron beams. In this asymmetric lens, the asymmetry for a center beam differs from that for side beams.

Abstract: Electron gun for a color CRT having main lens forming electrodes wherein a depth from a rim portion of an anode to an electrostatic field control electrode is deeper than the depth from the rim portion of a cathode to the electrostatic field control electrode, and a DQ lens action of a center beam portion formed by the DQ lens unit being weaker than the DQ lens action of an outer electron beam portion, whereby reducing a spot diameter by enlarging a main lens diameter and correcting inconsistency between a center beam and an outer beam in the DQ lens.

Abstract: Cathode venting for electron guns is improved by forming one or more vent holes around the apertures in the triode and any pre-focus lens. This configuration places the vent holes next to the active area of the cathode and provides a line of sight from the cathode to the funnel. If separate alignment holes are used to protect the aperture, one or more vent holes are provided in addition to the alignment holes. The pattern of vent and alignment holes is preferably rotationally symmetric about the aperture so that they do not effect the beam.

Abstract: A dual-gun, single neck CRT focuses two beams, with significantly differing energies, onto a secondary emission target while maintaining compatibility with a standard fourteen-rotation stem and achieving FTU in excess of 95%. A pair of Einzel guns (write and erase) are mounted in parallel and aligned in the vertical direction rather than the horizontal inside the CRT. The write and erase guns are configured to share a common second accelerator electrode, a common final accelerator electrode, mounting beads and a magnetic deflection yoke. The guns' focus voltages are independently adjusted so that both the write and erase beams have the same focal length.

Abstract: A color cathode ray tube has a three in-line beam electron gun. The electron gun includes a first group of focus electrodes supplied with a first fixed focus voltage and a second group of focus electrodes supplied with a second focus voltage comprised of a fixed voltage and a dynamic voltage synchronized with beam deflection. Plural axially spaced electrostatic quadrupole lenses are formed between facing ones of the first and second groups of focus electrodes. One of the plural electrostatic quadrupole lenses nearest to the cathodes is configured so as to produce a lens action weaker on two side electron beams than on the center electron beam.

Abstract: An electron gun for a cathode ray tube includes a triode portion composed of three cathodes arranged in a horizontal line, and control and screen electrodes sequentially placed next to the cathode. First to fourth focusing electrodes are sequentially arranged one after another next to the screen electrode. The first focusing electrode has a first side facing the screen electrode and a second side facing a second focusing electrode. Three circular-shaped beam passage holes are formed in both sides of the first focusing electrode. The second focusing electrode has a first side facing the first focusing electrode and a second side facing the third focusing electrode. Three vertically elongated beam passage holes are formed in the first side facing the first focusing electrode and three circular-shaped beam passage holes are formed in the second side facing the third focusing electrode.

Abstract: An electron gun of a color cathode ra tube includes (1) a beam forming region having cathodes, a G1 electrode and a G2 electrode and (2) a main lens formed of plural electrodes including a G3 electrode supplied with a fixed focus voltage and an accelerating electrode. The main lens includes a final lens formed between the accelerating electrode and an electrode opposing the accelerating electrode and configured so that outer electron beats are deflected toward a trajectory of a center electron beam and a lens strength of the final lens weakens with beam deflection The electron gun also has at least one multipole lens located between the final lens and the beam forming region and configured so as to change a cross sectional shape of the electron beams with beam deflection, and a lens formed between a pair of electrodes located between the final lens and the beam forming region and having axially spaced opposing surfaces each having opposing center beam apertures and opposing outer beam apertures.

Abstract: A color cathode ray tube including a panel section having a phosphor layer formed on an internal surface thereof, a neck portion having an electron gun assembly for emission of three electron beams therein, and a funnel section connecting the panel section and the neck portion. The electron gun assembly includes three cathodes and a plurality of grid electrodes disposed along a tube axis. The grid electrodes includes at least one plate-shaped electrode which has a fixed support structure. The plate-shaped electrode has three bulged portions along an electron beam passage, a first electron beam passage hole being formed in a respective bulged portion and a second electron beam passage being hole formed in a top face portion of a respective bulge portion. A diameter of the first electron beam passage hole is greater than a diameter of the second electron beam passage hole.

Abstract: A color cathode ray tube having an electron gun including an electron beam generating portion arrayed in a horizontal direction for generating three electron beams, and a main lens for focusing the three electron beams from the electron beam generating portion upon a fluorescent face. A final stage of the main lens is formed between a focusing electrode and an accelerating electrode. The focusing electrode is divided into at least two focusing electrode parts. A quadrupole electron lens is formed for each of the electron beams between a first focusing electrode part and a second focusing electrode part, and the strength of the quadrupole electron lens for the central electron beam is different from the strength of the quadrupole electron lens for the side electron beams.

Abstract: The electron beam generating section in an electron gun assembly includes a cathode having an electron emitting surface. The surface of the cathode is divided into at least three regions of first, second and third regions which have different electron emission capabilities. The first region is arranged in the center of the surface of the cathode. The second region has its portions arranged on opposite sides of the first region in the horizontal direction. The third region has its portions arranged on opposite sides of the first region in the vertical direction.

Abstract: There is provided an electron gun for a cathode-ray tube, comprising a triode having a control electrode and an accelerating electrode for controlling the amount of electron beams emitted from a plurality of cathodes and accelerating the electron beams, a front focusing lens part configured of a plurality of electrodes focusing and accelerating a predetermined amount of the electron beams, and a main lens part configured of a plurality of electrodes for focusing the electron beams on a screen, in which the diameter of beam passage hole of the accelerating electrode of the triode corresponds to 140-220% of that of the control electrode. The thickness of the control electrode corresponds to 20-30% of the diameter of beam passage hole of the control electrode, and the distance between the control electrode and the accelerating electrode corresponds to 40-80% of the beam passage hole diameter of the control electrode.

Abstract: A grid for use in a linear electron beam tube such as an IOT or TWT includes a grid section and a focus electrode between which is included an accommodation portion. The grid is mounted in the tube by a mounting flange around its outer periphery. During use, the grid section becomes hot and consequently expands but the mounting flange remains relatively cool being connected to a relatively massive structure. Thin flexible strips of the accommodation section permit movement between the mounting flange and the grid section due to differential thermal expansion, thus minimising distortion to the grid section which might otherwise occur if it were connected directly to the mounting flange and hence fixed in its outer diameter length. In other embodiments, the focus electrode is omitted.

Abstract: A color cathode ray tube having at least an electron gun and a fluorescent screen. The electron gun forms a plurality of electron beams arranged in line and includes a focusing electrode and an anode having a gap and providing a main lens for focusing and accelerating the electron beams. The focusing electrode includes at least a first division electrode and a second division electrode having the same potential and arranged with a gap in the axial direction of the tube. The second division electrode is opposed to said anode and has, in the opposed surface thereof, a single opening for passing the plurality of electron beams in common. The second division electrode is opposed to the first division electrode and has, in the opposed surface thereof, individual electron beam passing openings for the respective electron beams.

Abstract: It is intended to improve the focus characteristic while not requiring an increased focus voltage and hence enabling use of a general-purpose flyback transformer. A focus electrode for formation of a final-stage main lens that focuses electron beams generated by a beam generating section of an electron gun onto a phosphor screen is divided into a plurality of electrode members. The divisional electrode members form plural stages of electron lenses whose focusing power varies in synchronism with the deflection amount of the electron beams.

Abstract: The present invention provides a color cathode ray tube which can improve the focusing characteristics in a wide range of a phosphor screen by setting the total length of a focus electrode divided in multi-stages within a given value and properly selecting the mounting position and the sensitivity of an electrostatic quadrupole lens. A focus electrode G5 which constitutes a final stage main lens includes a plurality of electrode members G5-1, G5-2, G5-3, G5-4 which constitute an electrostatic quadrupole lens and a curvature-of image-field correction lens, and assuming the distance from a surface of the focus electrode G5 which faces an anode G6 in an opposed manner to the final-stage main lens-side position of the electrostatic quadrupole lens as L2, a relationship of 7.55≦L2≦11.5 is set.

Abstract: In order to ensure high luminance while enabling lighting of a gas discharge tube, an opening area S of a focusing opening was narrowed down into a range of 0.15 to 0.5 mm2. In addition, in order to attain a uniform emission with high luminance, while taking the aforementioned opening area S into consideration, the inventor noted a relation between an opening length A in a longitudinal direction of the focusing opening and an opening length B thereof in a direction perpendicular to the longitudinal direction. Then the shape of the focusing opening was specified by use of an equation to define the relation of B/A and the value thereof was narrowed into a range of 0.1 to 0.5. By limiting the focusing opening by the various parameters in this way, the inventor succeeded in specifying uniform slit light with a good lighting property and with high luminance in the gas discharge tube.

Abstract: In a color picture tube, a main lens of an electron gun is formed by a focus electrode to which a focus voltage, is applied an intermediate electrode to which an intermediate voltage between the focus voltage is applied and an anode voltage, and an anode electrode to which the anode voltage is applied. The focus electrode and the anode electrode are cylindrical, and plate electrodes are secured to the inner walls of the respective focus and anode electrodes, and the intermediate electrode has a construction in which a middle plate electrode is sandwiched between two cylindrical electrodes. Accordingly, it is possible to provide an electron gun which is easy to manufacture and has a superior focus performance and is reduced in performance variability.

Abstract: A three in-line beam type color CRT includes a focus electrode and an anode. The focus electrode includes a first focus sub-electrode supplied with a first fixed focus voltage and a second focus sub-electrode supplied with a second fixed voltage superposed with a dynamic voltage synchronized with beam deflection, and the first and second focus sub-electrodes form a quadrupole lens therebetween. Two side electron beams are deflected toward a center electron beam with increasing dynamic voltage in the quadrupole lens. An axial distance Lgf (mm) from a cathode side end of the first focus sub-electrode to an anode side end of the second focus sub-electrode, an axial distance Ls (mm) from the end of the second focus sub-electrode to the phosphor screen, and a useful diagonal dimension D (mm) of the phosphor screen satisfy 0.06×Ls (mm) ≦Lgf (mm)≦26 (mm) and 1.50≦D/Ls≦1.70.

Abstract: The present invention discloses an electron gun assembly for color cathode ray tube capable of preventing a moiré phenomenon and improving the resolution.

Abstract: A color cathode ray tube has G1-G5 electrodes and an anode. The G5 electrode is divided into sub-electrodes supplied alternately with a first fixed focus voltage and a second focus voltage which is a second fixed voltage superposed with a dynamic voltage, at least one electrostatic quadrupole lens is formed between adjacent ones of the sub-electrodes, and two of the sub-electrodes are supplied with the second focus voltage. The following inequalities are satisfied: 0.0625×L (mm)≦B−20A/(3&phgr;)≦22.0 mm, L (mm)≦352 mm, where A is an axial length of the G4 electrode, &phgr; (mm) is an average diameter of a center aperture in the G4 electrode, B (mm) is a length from a cathode side end to a phosphor screen side end of said G5 electrode to the phosphor screen.

Abstract: In a self-convergent type color cathode ray tube apparatus, three in-line electron beams emitted from an electron gun assembly are deflected by non-uniform magnetic fields generated by a deflection yoke and thus self-converged onto a screen. The electron gun assembly has a second grid and a third grid. First and second auxiliary grids are disposed between the second and third grids. A dynamic voltage varying in synchronism with deflection of the electron beams is applied to the first auxiliary grid situated on the second grid side. A fixed voltage is applied to the second auxiliary grid situated on the third grid side. Accordingly, the second grid, the first and second auxiliary grids and the third grid form an electron lens such that a higher astigmatism is provided by focusing in a direction perpendicular to a direction of arrangement of the three electron beams than by focusing in the direction of arrangement of the three electron beams and the degree of the astigmatism is dynamically varied.