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EP0714115A2 - Dispositif d'affichage en couleurs utilisant de lentilles quadrupolaires - Google Patents

Dispositif d'affichage en couleurs utilisant de lentilles quadrupolaires Download PDF

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Publication number
EP0714115A2
EP0714115A2 EP95118059A EP95118059A EP0714115A2 EP 0714115 A2 EP0714115 A2 EP 0714115A2 EP 95118059 A EP95118059 A EP 95118059A EP 95118059 A EP95118059 A EP 95118059A EP 0714115 A2 EP0714115 A2 EP 0714115A2
Authority
EP
European Patent Office
Prior art keywords
electrode
focus
focus electrode
electron beam
voltage
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP95118059A
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German (de)
English (en)
Other versions
EP0714115A3 (fr
Inventor
Yoshiaki Takahashi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Japan Display Inc
Original Assignee
Hitachi Ltd
Hitachi Electronic Devices Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hitachi Ltd, Hitachi Electronic Devices Co Ltd filed Critical Hitachi Ltd
Publication of EP0714115A2 publication Critical patent/EP0714115A2/fr
Publication of EP0714115A3 publication Critical patent/EP0714115A3/fr
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/56—Arrangements for controlling cross-section of ray or beam; Arrangements for correcting aberration of beam, e.g. due to lenses
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/58—Arrangements for focusing or reflecting ray or beam
    • H01J29/62—Electrostatic lenses
    • H01J29/626—Electrostatic lenses producing fields exhibiting periodic axial symmetry, e.g. multipolar fields
    • H01J29/628—Electrostatic lenses producing fields exhibiting periodic axial symmetry, e.g. multipolar fields co-operating with or closely associated to an electron gun
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
    • H01J29/48—Electron guns
    • H01J29/50—Electron guns two or more guns in a single vacuum space, e.g. for plural-ray tube
    • H01J29/503—Three or more guns, the axes of which lay in a common plane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2229/00—Details of cathode ray tubes or electron beam tubes
    • H01J2229/48—Electron guns
    • H01J2229/4834—Electrical arrangements coupled to electrodes, e.g. potentials
    • H01J2229/4837—Electrical arrangements coupled to electrodes, e.g. potentials characterised by the potentials applied
    • H01J2229/4841—Dynamic potentials

Definitions

  • the present invention relates to a color display system and particularly to a cathode ray tube having improved resolution over the entire phosphor screen and a color display system provided with this cathode ray tube.
  • the resolution of a color cathode ray tube depends on the size and shape of beam spots on the phosphor screen.
  • the beam spot formed by impingement of an electron beam emitted from an electron gun onto the phosphor screen and resultant luminescence of the phosphor screen is small in diameter and close to a true circle, it provides a good resolution.
  • the electron beam emitted from the electron gun is deflected horizontally and vertically on the way to the phosphor screen and reaches the phosphor screen.
  • the central area and peripheral area of the phosphor screen are different in the distance from the center of deflection from each other, so that as the deflection of the electron beam increases, the shape of the beam spot elongates vertically for the most part.
  • the two side electron beams are displaced from the tube axis, so that their convergence is degraded in the peripheral area of the phosphor screen and the resolution deteriorates.
  • Fig. 1 is a schematic cross sectional view illustrating a structure example of a color cathode ray tube to which the present invention is applied.
  • Numeral 1 indicates a panel portion, 2 a funnel portion, 3 a neck portion, 4 a phosphor screen, and 5 a shadow mask which is a color selection electrode.
  • Numeral 6 indicates a third electrode, 7 a fourth electrode, 8 a shield cup, 14 a deflection yoke, 15, 16, and 17 center axes of electron beams, and 18 and 19 centers of the side electron beam passage apertures of the fourth electrode 7.
  • Cathode portions K1, K2, and K3, a first electrode 10, and a second electrode 20 constitute a so-called triode portion.
  • the color cathode ray tube comprises an evacuated envelope formed of the panel portion 1 and the neck portion 3 joined to the side wall of the panel portion 1 via the funnel 2, an electron gun incorporated in the neck portion 3, the deflection yoke 14 mounted on the outer wall of the funnel portion 2 and the neck portion 3 in the neighborhood of their junction, and the multi-apertured shadow mask 5 in predetermined spaced relation adjacent to the phosphor screen 4.
  • Striped or dotted phosphors of red, green, and blue are coated on the phosphor screen.
  • Three electron beams emitted from the electron gun are color-selected by the shadow mask 5, impinge on the phosphors associated with the respective electron beams and cause the phosphors to luminesce.
  • the electron gun comprises an electron beam generation portion for generating, accelerating, and controlling three parallel electron beams of in-line arrangement from the cathode portions K1, K2, and K3, a prefocus lens portion for focusing the electron beams slightly, and a main lens portion for focusing the electron beams on the phosphor screen 4 and the three electron beams are deflected by the magnetic deflection yoke 14 so as to scan the beams in a rectangular raster over the phosphor screen 4.
  • the constitution shown in the figure is an example and a variety of electron guns are known in terms of the number of electrodes constituting the electron gun, the shapes of electron beam apertures in the electrodes, and the structures of the electrodes.
  • Fig. 2 is an illustration of the magnetic deflection field by the deflection yoke acting on electron beams.
  • the magnetic deflection field by the magnetic deflection yoke has, as shown in the figure, a pin cushion shaped distortion 14H in the horizontal deflection field and a barrel shaped distortion 14V in the vertical deflection field.
  • Figs. 3A and 3B are illustrations of the deflection and shape distortion of an electron beam spot by the magnetic deflection field.
  • An electron beam B deflected to the periphery of the phosphor screen is subject to diffusing force fh in the horizontal direction and focusing force fv in the vertical direction as shown in Fig. 3B in addition to the force Fh for deflecting the electron beam as shown in Fig. 3A and forms a distorted spot shape.
  • Fig. 4 is an illustration of the beam spot shapes on the phosphor screen.
  • the beam spot OO in the center area of the phosphor screen 3 is circular, the beam spots generated in the peripheral area of the phosphor screen are distorted to a non-circle comprising a core BC of high intensity and a halo BH and particularly the large vertical elongation of the halo BH affects adversely the focus characteristic.
  • Fig. 5 is a cross sectional view illustrating the constitution of the electron gun disclosed in the aforementioned prior art.
  • Symbols K1, K2, and K3 indicate cathodes, numeral 10 a control grid, 20 an accelerating electrode, 30 a first focus electrode, 40 a second focus electrode, 48 a rim electrode, 50 a third focus electrode, 60 an anode, 11, 12, 13, 21, 22, 23, 31, 32, 33, 41a, 42a, 43a, 41b, 42b, 43b, 51a, 52a, 53a, 51b, 52b, 53b, 61, 62, and 63 respective electron beam passage apertures thereof, 44, 45, 46, and 47 vertical plates, and 54 and 55 horizontal plates.
  • Symbol C indicates an electron gun axis (coincides with the tube axis), S1 a displacement of each of the side electron beams from the electron gun axis C, and S2 a displacement of each of the side electron beam passage apertures 61 and 63 of the anode 60 from the electron gun axis C.
  • Fig. 6 is a plan view of the accelerating electrode 20 in a direction of the arrow 100 shown in Fig. 5, and Fig. 7 is also a plan view of the second focus electrode 40 in a direction of the arrow 101, and Fig. 8 is also a plan view of the third focus electrode 50 in a direction of the arrow 102.
  • slits 24, 25, and 26 elongated in the inline direction of the three electron beams are superposed on the three circular electron beam passage apertures 21, 22 and 23 on the first focus electrode 30 side of the accelerating electrode 20.
  • the second focus electrode 40 has the circular electron beam passage apertures 41b, 42b, and 43b on the side of the third focus electrode 50, opposes the third focus electrode 50, and furthermore has a first plate electrode (vertical plate) comprising the four vertical parallel plates 44, 45, 46, and 47 which are attached on the opposite sides of each aperture so as to extent toward the third focus electrode 50.
  • a first plate electrode vertical plate
  • the second focus electrode 40 has the rim electrode 48 which surrounds the first plate electrode and extends a predetermined distance from ends 44a, 45a, 46a, and 47a of the parallel plates toward the third focus electrode 50.
  • the third focus electrode 50 has the three circular electron beam passage apertures 51a, 52a, and 53a on the side of the second focus electrode 40 and has a second plate electrode (horizontal plate) comprising a pair of horizontal parallel plates 54 and 55 which are attached so as to sandwich the three circular electron beam passage apertures vertically and to extend toward the second focus electrode 40.
  • the ends 54a and 55a of the horizontal parallel plates constituting the second plate electrode extend into the rim electrode 48 of the second focus electrode 40 and are spaced a predetermined interval L from the ends 44a, 45a, 46a, and 47a of the vertical parallel plates of the second focus electrode 40 along the electron gun axis.
  • the anode 60 has the three circular electron beam passage apertures 61, 62, and 63 on its end face. Between the displacement S2 of the side electron beam passage apertures 61 and 63 from the electron gun axis and the displacement S1 of the cathodes K1 and K3 and the side electron beam passage apertures of the control grid 10, the accelerating electrode 20, the first focus electrode 30, the second focus electrode 40, and the third focus electrode 50 preceding the anode 60, a relation of S2>S1 is held, a main lens is formed between the third focus electrode 50 and the anode 60, and the side electron beams SB1 and SB2 are converged at a point on the phosphor screen.
  • 50 to 170 V is applied on the cathodes K1, K2, and K3, 0 to-150 V on the control grid 10, 400 to 800 V on the accelerating electrode 20, 5 to 8 kV on the second focus electrode 40 as a focus voltage Vf, 23 to 30 kV on the anode 60 as an anode voltage Eb, and a dynamic voltage DVf which varies in synchronization with the horizontal and vertical deflections of the electron beams on the first focus electrode 30 and the third focus electrode 50.
  • Fig. 9 is an illustration of an electron beam bundle emitted from the accelerating electrode 20 under the aforementioned operating voltage condition and Fig. 10 is a schematic diagram expressing the electron beam trajectories electron-optically.
  • the electron beams leaving the slits 24, 25, and 26 of the accelerating electrode 20 are subjected to a strong vertical focusing action and the cross section of each electron beam is elongated horizontally on the phosphor screen as shown in Fig. 9.
  • the H portion of high current density is formed in the center of each cross section and the L portions of low current density are formed on both sides thereof.
  • the electron trajectories are as shown in Fig. 10, and the electron beam is overfocused horizontally indicated with Ph and underfocused vertically indicated with Pv, due to spherical aberration and the focus voltage is adjusted for focus within the shown range W on the phosphor screen.
  • the beam spot on the phosphor screen at this time has a vertically elongated shape comprising the H portion of high current density.
  • Fig. 11 is an illustration of an effect on beam spots by the parallel plates (vertical plates) 44, 45, 46, and 47 in the second focus electrode 40 and the parallel plates (horizontal plates) 54 and 55 attached to the third focus electrode 50
  • Fig. 12 is an illustration of an effect on a beam spot by the parallel plates (horizontal plates) 54 and 55 attached to the third focus electrode 50.
  • the aforementioned quadrupole lens action acts so as to cancel the effect on the electron beams by the magnetic deflection aberration, so that the electron beams are brought into an optimum focus on the screen.
  • the entrance angle of the electron beam into the main lens formed by the third focus electrode 50 and the anode 60 and the beam diameter are different between the horizontal direction and the vertical direction, and it is impossible to make the shape of the beam spot closer to a circle because the lens magnification in the main lens is different between the horizontal direction and the vertical direction.
  • Figs. 13A and 13B are illustrations of a light-optical equivalent of the quadrupole lens action by the second and third focus electrodes and the electron beam trajectories when the electron beams are deflected horizontally, and Fig. 13A is a horizontal cross sectional view, and Fig. 13B is a vertical cross sectional view.
  • Numeral 70 indicates a crossover point of an electron beam equivalent to an object of the lens system
  • 72 a convex lens representing the horizontal focusing action by a quadrupole lens electric field formed between the second focus electrode and the third focus electrode
  • 73 a main lens
  • 74 a concave lens representing the horizontal diverging action by the magnetic deflection field
  • 75 a phosphor screen
  • 76 an electron beam trajectory
  • 78 a concave lens representing the vertical diverging action
  • 79 a convex lens representing the vertical focusing action by the magnetic deflection field
  • 80 a beam impinging point on the phosphor screen.
  • the electron lens system can be represented by a light-optics equivalent of a sequential arrangement of the convex, convex, and concave lenses in a horizontal cross section from the object 70 side and a sequential arrangement of the concave, convex, and convex lenses in a vertical cross section.
  • the horizontal and vertical entrance angles of the beam impinging on the phosphor screen 75 have a relation of ⁇ H ⁇ V.
  • the horizontal and vertical entrance angles of impinging on the phosphor screen 75 have a relation of ⁇ H ⁇ V, resulting in the relationship of the lens magnifications MV ⁇ MH, and the beam spot diameter becomes elongated horizontally.
  • the slits 24, 25, and 26 are formed in the accelerating electrode 20 as shown in Fig. 6.
  • Figs. 14A and 14B are illustrations of light-optics equivalents representing a correction of the horizontal and vertical lens magnifications by the slits of the accelerating electrode, and Fig. 14A is a horizontal cross sectional view, and Fig. 14B is a vertical cross sectional view.
  • the quadrupole lens electric field generated by the slits of the accelerating electrode produces a convex lens 71 having a weak focusing action in the horizontal direction and a convex lens 77 having a strong focusing action in the vertical direction.
  • the exit angle of the electron beam in the vertical direction is made smaller than that in the horizontal direction by the quadrupole lens electric fields (convex lenses) 71 and 77 generated by the slits of the accelerating electrode.
  • the vertical entrance angle ⁇ 'V of an electron beam which passes through the electron lens system and strikes the beam impinging point 80 on the phosphor screen will not become excessively larger than the horizontal entrance angle ⁇ 'H and ⁇ 'V can be considered to be nearly equal to ⁇ 'H.
  • the vertical and horizontal lens magnifications MV and MH can be considered nearly equal to each other.
  • the quadrupole lens by the slits of the accelerating electrode operates so that the electron beams are elongated horizontally. Therefore, the beam spots on the phosphor screen are elongated vertically from the relation with the aforementioned current density distribution and the cross section of the electron beam is increased by correction of the difference between the horizontal and vertical focal lengths, accordingly the horizontal resolution is easily degraded.
  • the quadrupole lens formed by the slits of the accelerating electrode produces a stronger effect on the electron beam.
  • the vertical diameter of the beam spot increases further, and when the electron beam is deflected to the corners of the phosphor screen, the quadrupole lens action (horizontal elongation of the cross section) on the beam is stronger and the horizontal diameter of the electron beam inside the main lens increases and consequently the spherical aberration affects more adversely, and increases the horizontal diameter of the electron beam.
  • the current density of an electron beam is unevenly distributed so that it is high in the center and low at the peripheries, and the current density distribution is easily imbalanced due to the physical variations of the electrodes and the assembly errors thereof of the electron gun.
  • the electron beam is deflected to the corners of the phosphor screen, the portion of low current density is imbalanced further due to the magnetic deflection field and the image quality is degraded.
  • An object of the present invention is to solve the aforementioned problems with the prior art and to provide a color cathode ray tube having an electron gun which can produce a satisfactory resolution over the entire phosphor screen and a color display system using it.
  • a color cathode ray tube having an electron gun comprising at least a cathode, a control electrode, an accelerating electrode, a focus electrode and an anode spaced axially in the order named, wherein the focus electrode compries at least a first focus electrode, a second focus electrode and a third focus electrode spaced in the order named, the first focus electrode faces the accelerating electrode, a first quadrupole lens structure is formed by at least one of a portion of the first focus electrode facing the second focus electrode and a portion of the second focus electrode facing the first focus electrode, and a second quadrupole lens structure is formed by at least one of a portion of the second focus electrode facing the third focus electrode and a portion of the third focus electrode facing the second focus electrode.
  • a color display system including a color cathode ray tube having an electron gun comprising at least a cathode, a control electrode, an accelerating electrode, a focus electrode and an anode spaced axially in the order named, wherein the focus electrode comprises at least a first focus electrode, a second focus electrode and a third focus electrode spaced in the order named, the first focus electrode faces the accelerating electrode, a first quadrupole lens structure is formed by at least one of a portion of the first focus electrode facing the second focus electrode and a portion of the second focus electrode facing the first focus electrode, a second quadrupole lens structure is formed by at least one of a portion of the second focus electrode facing the third focus electrode and a portion of the third focus electrode facing the second focus electrode, and a dynamic focus voltage varying with deflection of an electron beam to a voltage higher than a voltage applied to the second focus electrode is applied to the first and third focus electrodes so that the first quadrupole lens structure produces horizontally diver
  • the horizontal and vertical lens magnifications can be made equal to each other in the main lens formed between the third focus electrode and the anode, and an electron beam emitted from the cathode produces almost a truly circular and small beam spot.
  • the electron beam When the deflection amount of an electron beam is increased, the electron beam is initially elongated horizontally by horizontally diverging and vertically focusing actions produced by the quadrupole lens formed between the first focus electrode and the second focus electrode and subsequently by vertically diverging and horizontally focusing actions produced by the quadrupole lens formed between the second focus electrode and the third focus electrode, the imbalance between the vertical and horizontal lens magnification is corrected. Furthermore, the amount of correction is varied with the deflection amount of the electron beam, and correction in the lens magnifications can be designed as desired, and the current density distribution in the horizontally elongated electron beam bundle becomes almost uniform unlike that when the accelerating electrode 20 shown in Fig. 6 is used, and the imbalance amount in halo due to the assembling errors of the electron gun is reduced.
  • the electron beam emitted from the cathode can provide a truly circular and small beam spot by the main lens formed between the third focus electrode and the anode.
  • the electric field strength in the spacing between the accelerating electrode and the first focus electrode increases (the lens magnification increases) and the angle of divergence of the electron beam leaving the accelerating electrode is reduced.
  • This reduction of the divergence angle of the electron beam decreases the beam diameter within the preceding one of the two quadrupole lenses and the beam diameter within the main lens when the electron beam is deflected, suppresses the horizontal spreading of the electron beam at a large current and reduces the influences of spherical aberration of the main lens and those of deflection aberration produced by the magnetic deflection field.
  • the reductions in these two aberrations improve uniformity of the shapes of the beam spots over the entire phosphor screen in a range of small to large currents.
  • Fig. 1 is a schematic cross sectional view illustrating a structural example of a color cathode ray tube to which the present invention is applied.
  • Fig. 2 is an illustration of magnetic deflection fields acting on an electron beam generated by a deflection yoke.
  • Figs. 3A and 3B are illustrations of deflection of an electron beam and a distortion of the shape of the electron beam spot by a magnetic deflection field.
  • Fig. 4 is an illustration of shapes of the beam spot on the phosphor screen.
  • Fig. 5 is a cross sectional view illustrating the constitution of an electron gun of the prior art.
  • Fig. 6 is a plan view of the accelerating electrode in a direction of the arrows 100 shown in Fig. 5.
  • Fig. 7 is a plan view of the second focus electrode in a direction of the arrow 101 shown in Fig. 5.
  • Fig. 8 is a plan view of the third focus electrode in a direction of the arrow 102 shown in Fig. 5.
  • Fig. 9 is an illustration of the beam spot shape on the phosphor screen under the operating voltage condition shown in Fig. 5.
  • Fig. 10 is a schematic diagram expressing a lens action on an electron beam.
  • Fig. 11 is an illustration of effects of parallel plates (vertical plates) in the second focus electrode and parallel plates (horizontal plates) attached to the third focus electrode on a beam spot.
  • Fig. 12 is an illustration of an effect of parallel plates (horizontal plates) attached to the third focus electrode on a beam spot.
  • Figs. 13A and 13B are illustrations of electron beam trajectories when an electron beam is deflected horizontally by using light-optics equivalents.
  • Figs. 14A and 14B are illustrations of corrections of the horizontal and vertical lens magnifications by the slits of the accelerating electrode by using light-optics equivalents.
  • Fig. 15 is a cross sectional view illustrating the constitution of an embodiment of an electron gun for a color cathode ray tube of the present invention.
  • Figs. 16A and 16B are a front view of the first focus electrode in a direction of the arrow 103 shown in Fig. 15 and an illustration of an action thereof on an electron beam respectively.
  • Fig. 17 illustrates a lens action on an electron beam in the neighborhood of the accelerating electrode shown in Fig. 15.
  • Fig. 15 is a cross sectional view illustrating the constitution of an embodiment of an electron gun for a color cathode ray tube of the present invention.
  • Fig. 16A is a front view of the first focus plate electrode in a direction of the arrow 103 shown in Fig. 15 and Fig. 16B is an illustration of an action of the electrode shown in Fig. 16A on an electron beam.
  • symbols K1, K2, and K3 indicate cathodes
  • numeral 10 a control electrode
  • 20 an accelerating electrode
  • 30 a first focus electrode
  • 35 a first focus plate electrode
  • 40 a second focus electrode
  • 48 a rim electrode
  • 50 a third focus electrode
  • 60 an anode, 11, 12, 13, 21, 22, 23, 31a, 32a, 33a, 31b, 32b, 33b, 41a, 42a, 43a, 41b, 42b, 43b, 51a, 52a, 53a, 51b, 52b, 53b, 61, 62, and 63 electron beam passage apertures thereof, respectively, 36, 37, and 38 vertically elongated rectangular apertures, 44, 45, 46, and 47 vertical plates, and 54 and 55 horizontal plates.
  • Symbol C indicates an electron gun axis (coincides with the tube axis), S1 a displacement of each of the side electron beams from the electron gun axis C, and S2 a displacement of each of the side electron beam passage apertures 61 and 63 of the anode 60 from the electron gun axis C.
  • the first focus electrode 30 has the circular beam passage apertures 31a, 32a, 33a, 31b, 32b, and 33b.
  • the first focus plate electrode 35 has the vertically elongated rectangular apertures 36, 37, and 38 and is electrically connected to the first focus electrode 30.
  • the second focus electrode 40 has a first plate electrode (vertical plate) formed of the four vertical parallel plates 44, 45, 46, and 47 attached on the opposite sides of each of the three circular electron beam passage apertures 41b, 42b, and 43b on its end face on the side of the third focus electrode 50.
  • the second focus electrode 40 has the rim electrode 48 which surrounds the first plate electrode and extends a predetermined distance from ends 44a, 45a, 46a, and 47a of the parallel plates toward the third focus electrode 50.
  • the third focus electrode 50 has the three circular electron beam passage apertures 51a, 52a, and 53a in its end face on the side of the second focus electrode 40 and has a second plate electrode (horizontal plate) formed of a pair of horizontal parallel plates 54 and 55 attached thereon and extending toward the second focus electrode 40 so as to sandwich the electron beam passage apertures vertically.
  • the ends 54a and 55a of the parallel plates 54 and 55 constituting the second plate electrode extend into the rim electrode 48 of the second focus electrode 40 and are spaced a predetermined interval L from the ends 44a, 45a, 46a, and 47a of the vertical parallel plates of the second focus electrode 40 along the electron gun axis.
  • the three circular electron beam passage apertures 61, 62, and 63 are formed.
  • a relation of S2>S1 is maintained, a main lens is formed between the third focus electrode 50 and the anode 60, and the side electron beams SB1 and SB2 are designed to converge on the center electron beam CB on the phosphor screen.
  • 50 to 170 V is applied on the cathodes, 0 to -150 V on the control grid, 200 to 1000 V on the accelerating electrode, 4 to 10 kV on the second focus electrode 40 (hereinafter V f ), 23 to 30 kV on the anode (hereinafter E b ), and a dynamic voltage DVf which varies in synchronization with the horizontal and vertical deflections of the electron beams on the first focus electrode 30, the first focus plate electrode 35, and the third focus electrode 50.
  • the presence of the vertically elongated rectangular apertures 36, 37, and 38 in the first focus plate electrode 35, the parallel plates (vertical plates) 44, 45, 46, and 47 in the second focus electrode 40, and the parallel plates (horizontal plates) 54 and 55 attached to the third focus electrode 50 exerts no influence on the electron beams and the electron beams from the cathodes form circular and small beam spots on the phosphor screen by the main lens formed between the third focus electrode 50 and the anode 60.
  • the electron beam at this time is subjected to a stronger focusing action than that when the magnetic deflection field is 0, and the angle of beam divergence of the electron beam trajectory Bc in the aperture 31b of the first focus electrode 30 is reduced as indicated by the trajectory Be, and the electron beam enters between the first focus plate electrode 35 and the second focus electrode 40, is horizontally elongated in its cross section by the quadrupole lens action, and then enters the lenses between the second focus electrode 40 and the third focus electrode 50 and between the third focus electrode 50 and the anode 60, successively.
  • a dynamic differential focus voltage Dv for the useful scanned area of the phosphor screen of the color cathode ray tube and a voltage Av applied to the accelerating electrode 20 measured with respect to the control electrode 10 satisfy the following inequality, 0.2 ⁇ Dv/Av ⁇ 4 where a dynamic differential focus voltage Dv is a voltage difference between a dynamic focus voltage when the beam is at the center of the phosphor screen and a dynamic focus voltage when the beam is at the extreme right or left edge and the top or the bottom of the useful scanned area on the phosphor screen.
  • the spreading of the electron beam due to an increase in the current can be suppressed by the enhanced focus lens action by the accelerating electrode 20 and particularly the effect of the spherical aberration due to the horizontal spreading in the main lens by the quadrupole lens formed between the first focus plate electrode 35 and the second focus electrode 40 can be suppressed.
  • the effect of the quadrupole lens formed between the first focus plate electrode 35 and the second focus electrode 40 is reduced because the ratio of the diameter of the electron beam to the diameter of the quadrupole lens is reduced, the beam diameter in the magnetic deflection field is also reduced, aberration caused by the magnetic deflection field (quadrupole lens) is reduced, and a correction of the imbalance between the horizontal and vertical lens magnifications can be maintained.
  • a vertically elongated divergent lens is formed as shown in Fig. 16B by the vertically elongated slits 36, 37, and 38 of the first focus plate electrode 35 and the electron beam is subjected to a diverging action stronger in the horizontal direction than that in the vertical direction (Fh>Fv) and horizontally elongated in its cross section.
  • the aforementioned quadrupole lens electric field for elongating an electron beam vertically is formed by the parallel plates (vertical plates) 44, 45, 46, and 47 in the second focus electrode 40 and the parallel plates (horizontal plates) 54 and 55 attached to the third focus electrode 50, and the potential difference between the third focus electrode 50 and the anode 60 is reduced, and the focusing action by the main lens is weakened.
  • the diameter of the quadrupole lens is large compared to the bundle of horizontally elongated electron beams shaped by the quadrupole lens between the first focus plate electrode 35 and the second focus electrode 40, the current density distribution becomes uniform.
  • An imbalance of the lens magnifications for the horizontally elongated electron beams is corrected between the second focus electrode 40 and the third focus electrode 50 and between the third focus electrode 50 and the anode 60.
  • an electron beam emitted from the cathode is subject to the equal horizontal and vertical lens magnifications of the main lens between the third focus electrode and the anode when the electron beam is not deflected, so that the electron beam spot becomes almost truly circular and small.
  • the electron beam is elongated horizontally by the quadrupole lens exerting horizontally diverging and vertically focusing actions formed between the first focus electrode and the second focus electrode and then an imbalance between the vertical and horizontal lens magnifications is corrected by the quadrupole lens exerting vertically diverging and horizontally focusing actions formed between the second focus electrode and the third focus electrode.
  • a satisfactory resolution can be produced over the entire phosphor screen of from high to low brightness.

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  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
EP95118059A 1994-11-25 1995-11-16 Dispositif d'affichage en couleurs utilisant de lentilles quadrupolaires Withdrawn EP0714115A3 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP291325/94 1994-11-25
JP6291325A JPH08148095A (ja) 1994-11-25 1994-11-25 電子銃およびこの電子銃を備えたカラー陰極線管

Publications (2)

Publication Number Publication Date
EP0714115A2 true EP0714115A2 (fr) 1996-05-29
EP0714115A3 EP0714115A3 (fr) 1997-07-16

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EP95118059A Withdrawn EP0714115A3 (fr) 1994-11-25 1995-11-16 Dispositif d'affichage en couleurs utilisant de lentilles quadrupolaires

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EP (1) EP0714115A3 (fr)
JP (1) JPH08148095A (fr)
KR (1) KR960019453A (fr)
CN (1) CN1130302A (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2000045414A1 (fr) * 1999-01-26 2000-08-03 Kabushiki Kaisha Toshiba Tube cathodique couleur
EP1050896A1 (fr) * 1998-11-20 2000-11-08 Kabushiki Kaisha Toshiba Tube cathodique

Families Citing this family (4)

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Publication number Priority date Publication date Assignee Title
US5936338A (en) * 1994-11-25 1999-08-10 Hitachi, Ltd. Color display system utilizing double quadrupole lenses under optimal control
KR100384675B1 (ko) * 2000-11-28 2003-05-22 가부시키가이샤 히타치세이사쿠쇼 칼라 수상관
KR20030033217A (ko) * 2001-10-19 2003-05-01 삼성에스디아이 주식회사 유니-바이 포텐셜 렌즈를 가지는 음극선관용 전자총
US6949895B2 (en) * 2003-09-03 2005-09-27 Axcelis Technologies, Inc. Unipolar electrostatic quadrupole lens and switching methods for charged beam transport

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JPS6258549A (ja) 1985-09-09 1987-03-14 Matsushita Electronics Corp カラ−受像管装置

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JP2645061B2 (ja) * 1988-03-11 1997-08-25 株式会社東芝 カラー受像管装置
JPH07134953A (ja) * 1993-11-09 1995-05-23 Hitachi Ltd カラー受像管

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JPS6258549A (ja) 1985-09-09 1987-03-14 Matsushita Electronics Corp カラ−受像管装置

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1050896A1 (fr) * 1998-11-20 2000-11-08 Kabushiki Kaisha Toshiba Tube cathodique
EP1050896A4 (fr) * 1998-11-20 2006-08-02 Toshiba Kk Tube cathodique
WO2000045414A1 (fr) * 1999-01-26 2000-08-03 Kabushiki Kaisha Toshiba Tube cathodique couleur
US6489736B1 (en) 1999-01-26 2002-12-03 Kabushiki Kaisha Toshiba Color cathode ray tube apparatus

Also Published As

Publication number Publication date
JPH08148095A (ja) 1996-06-07
CN1130302A (zh) 1996-09-04
KR960019453A (ko) 1996-06-17
EP0714115A3 (fr) 1997-07-16

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