US3375390A - Electron optical system having spiral collimating electrode adjacent the target - Google Patents

Electron optical system having spiral collimating electrode adjacent the target Download PDF

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US3375390A
US3375390A US518160A US51816066A US3375390A US 3375390 A US3375390 A US 3375390A US 518160 A US518160 A US 518160A US 51816066 A US51816066 A US 51816066A US 3375390 A US3375390 A US 3375390A
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electrode
target
spiral
lens
electron beam
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Schlesinger Kurt
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General Electric Co
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General Electric Co
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Priority to GB42792/66A priority patent/GB1142747A/en
Priority to FR87366A priority patent/FR1504388A/fr
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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
    • H01J29/58—Arrangements for focusing or reflecting ray or beam
    • 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
    • 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
    • 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
    • H01J2229/4824—Constructional arrangements of electrodes
    • H01J2229/4827—Electrodes formed on surface of common cylindrical support

Definitions

  • the present invention relates to ultra high resolution electron optical systems as disclosed in US. Patent 3,223,- 871 Schlesinger assigned to the same assigness as the present invention, and particularly to improved cathode ray tubes which embody such electron optical systems in combination with a specific collimating lens adjacent the target of said tubes.
  • One object of the invention is to provide an electron optical system for producing an electron beam having a target spot size which is extremely small, e.g., a few microns in diameter, at target beam current levels providing desirable energy transfer to the target, e.g., sev' eral microamperes.
  • Another object is to provide such an electron optical system wherein the electron beam can be readily defiected through a substantial target-scanning angle, e.g., of the order of 40 degrees, and wherein the overall physical length of the electron optical system is conveniently small.
  • a substantial target-scanning angle e.g., of the order of 40 degrees
  • Another object is to provide an electron optical system of the character described wherein defiection-defoc-using of the electron beam is minimized.
  • Another object is to provide an electron optical system of the character described including convenient means for precisely controlling the cross sectional shape of the target scanning electron beam.
  • Another object is to provide an electron optical system of the character described including convenient means for precise-1y controlling the cross sectional shape of the target scanning electron beam.
  • Another object is to provide an electron optical system of the character described which does not require critical mechanical alignment of the structural elements thereof.
  • Another object is to provide an improved cathode ray tube embodying an electron optical system of the foregoing character and a non-linear spiral collimating lens adjacent the target of said tube.
  • FIG. 1 is an axial sectional view of a preferred cathode ray tube constructed according to my invention
  • FIG. 2 is an enlarged fragmentary view of a portion of the structure of FIG. 1;
  • FIG. 3 is an enlarged transverse sectional view of the structure of FIG. 1 taken on line 3-3 thereof;
  • FIG. 4 is an enlarged transverse sectional view of the structure of FIG. 1, taken on line 4-4 thereof;
  • FIG. 5 is a view similar to FIG. 4 showing an alternative form of one feature of the invention.
  • FIG. 6 is a schematic diagram of circuitry associated with the apparatus of FIG. 5.
  • FIG. 1 An electronic optical system constructed in accordance 3,375,390 Patented Mar. 26, 1968 with my invention is shown in FIG. 1 embodied in a cathode ray tube which includes an envelope having an elongated neck 2, and an enlarged funnel portion 4 closed by a face plate 6.
  • a target in the form of a luminescent screen 8 On-the interior of face plate 6 is a target in the form of a luminescent screen 8.
  • the screen 8 may consist preferably of a continuous transparent film of luminescent material which may be of the vapor-phase deposited type such as taught by US. Patents 2,675,331; 2,685,530 and 2,887,401, commonly assigned herewith.
  • a plurality of sections Arranged in order coaxially within the neck portion of the envelope from the base or rearward end of the neck toward the target screen 8 are a plurality of sections hereinafter to be described in greater detail. These sections include an electron beam generating section 10, a prefocusing lens section 20, an electrically neck-elongating section 30, and a main focus lens section 40.
  • electrons are emitted from an axially located cathode 11 which is preferably of the high current-density type such as a dispenser cathode.
  • the emitted electrons pass through axially apertured collimator electrode 12, first anode-13, beam intensity modulating gate electrode 14, and a meniscus electrode 15. As best shown in FIG.
  • anode 13 has a forwardly projecting (towards screen 8) convex surface 16 which, together with the confronting rearwardly directed or facing con cavity 17 of the gate electrode 14 which, as illustrated, is in receiving relationship to the projecting surface 16, form a focusing electrostatic field, the equipotential surfaces of which are hyperboloids of revolution symmetrical with the axis of the tube neck and asymptotic to rear- Wardly concave conical surface 17 of approximately 109 apex angle whose apex faces screen 8 or away from said emitter and lies on the tube neck axis in substantial coincidence with the central aperture 18 in the meniscus electrode.
  • the characteristics of such a focusing electrostatic field are described in more detail in US. Patent 2,995,676 Schlesinger commonly assigned herewith.
  • the field between the anode 13 and the gate electrode 14 forms in the aperture 18 an effective virtual cathode of demagnified size relative to the actual cathode 11 and thus illuminates the aperture 18 with an electron beam of density many times that of the emission density from the actual cathode 11, for resulting maximum brightness at the screen 8.
  • the cathode 11 was operated as ground potential, collimator 12 at about +10 volts, anode 13 and meniscus 15 at about 500 volts, the beam intensity modulation was achieved by varying the potential of gate 14 between 5 and +10 volts, and current densities of about 25 amperes per square centimeter at aperture 18 were achieved with emission density at the cathode of only about 2 amperes per square centimeter.
  • the electron beam emerges from the aperture 18 into the pre'focusing lens section 20, Within which is formed an electrostatic field whose equipotentials are hyperboloids of revolution coaxial with the tube neck axis, and asymptotic to and within a coaxial forwardly concave conical surface 21 of approximately 109 apex angle having its apex facing emitter 11 and located in substantial coincidence with aperture 18.
  • the forward end of the prefocusing lens section is terminated by a transverse axially apertured conductive wall 22 having a coaxial opening 23 and spaced from the conical surface 21 by a supporting insulating cylinder 24.
  • the two surfaces 21 and 22 serve to form the hyperbolic electrostatic field within the prefocusing lens section 20, and, if desired, the formation of such field may be augmented by further electrode means, such as resistive coatings on the cylinder 24 having local potentials corresponding to the local space potential of the prefocusing lens field.
  • the electrically neck-elongating section 30 which includes an accelerating cylindrical spiral electrode 31 arranged coaxially with the neck axis.
  • the spiral electrode 31 may conveniently consist, as shown, of a conductive spiral coating of uniform pitch on the interior surface of an insulating support cylinder 32. Desirably the spiral electrode 31 has a high impedance of the order of 30-50 megohms to minimize power consumption.
  • Wall 22 and the rearward end of the spiral electrode 31 are connected by a lead 35 to a suitable adjustable potential source, shown schematically as potentiomcter 50, which may provide to lead 35 a relatively low potential of the order of 100 to 800 volts.
  • a conductive coating 33 on the exterior of the insulating cylinder 32 serves as an electrostatic shield for the spiral electrode and also conveniently provides part of a conductive path from the forward end of electrode 31 to a conductor 53 of substantially higher potential, which may be for example of the order of 7,000 volts, so as to provide a substantial accelerating field within spiral electrode 31.
  • Annular conductive caps 27, 36 are provided at each end of the cylinder 32 to facilitate mechanical support and provide convenient electrical connections to the ends of spiral electrode 31.
  • the forward end of the cylinder 32 is closed by a transverse conductive wall 37 having a central aperture 38.
  • the main focusing lens section 40 of the tube Forward of the aperture 38 and partially supported by wall 37 is the main focusing lens section 40 of the tube, which may be of any suitable type including a unipotential lens, but is here shown as a bipotential lens.
  • Section 40 includes as one element of the bipotential lens a coaxial conductive cylinder 41 of diminished diameter relative to electrode 31 and having an enlarged mouth 42 at its forward end. Cylinder 41 preferably has the same potential as the forward end of spiral electrode 31.
  • aperture 38 serves as a limiting aperture minimizing aberration through the lens section 40, and another transverse wall 43 intermediate the ends of cylinder 41 has an axial aperture 44 and serves as a shield to cut down emission of stray electrons from the lens section 40.
  • the forward end of the lens section 40 is spaced by an annular insulator 45 from a supporting conductive sleeve 46 which in turn is connected by conductive support fingers 47 to the neck wall.
  • Sleeve 46 forms the second element of the bipotential lens and is electrically connected by fingers 47 and an internal conductive coating 48 at the front of the neck and on the inner surface of the envelope funnel 4 to the high voltage terminal 51 of the tube, which may have a potential several times that of cylinder 41, for example 20 kv.
  • a suitable deflection yoke 49 is provided for scanning the electron beam on the screen 8.
  • FIG. 1 is a cross sectional view of a preferred embodiment of this invention.
  • the continuous coating type electrode 48 has been terminated adjacent the neck section of the bulb 4 to define an electrode 54.
  • Electrode 54 includes a terminal 55 for application of a desired voltage which in one example is about 9.5 kilovolts.
  • band electrode 56 is employed as a transitional electrode to stabilize electron trajectories prior to entry into the following electrical field.
  • Cylindrical or band electrodes are employed in conjunction with spiral electrodes, for example between spiral electrodes to smooth out the abrupt changes in electrical fields between spiral electrodes.
  • Spiral electrode 58 is of the non linear type, i.e., the number of turns or helices per unit axial length of the helix, increases in the axial direction toward target 8.
  • This hon linearity provides for increasing electrical resistance axially and an electrical field pattern which collimates electrons from the main focusing lens to provide more normal landing on target 8.
  • other forms of electrodes which provide the increased resistance such as tapered section electrodes
  • the spiral electrode has been found to be the most feasible. Examples of this and other forms of spiral electrodes are found in US. Patent 3,143,681 Schlesinger, assigned to the same assignee as the present invention. A further description of the spiral electrode '58 found in Correction of Deflection-Aberrations by Analog Computer, Schlesinger & Wagner, IEEE Transactions on Electron Devices, vol. ED-l2, #8, August 1965, pp. 478-484. General information on spiral lenses may be found in Technical Documentary Report No.
  • a suitable terminal 59 is provided for spiral electrode 58.
  • Suitable potentials at the terminals 57 and 59 have been found to be 6 kv. and 18 kv. respectively.
  • the specific dimensions of the spiral electrode 58 are chosen to provide the desired results in a given tube and application. However, the direct use of an increasing resistance spiral will provide superior performance as compared to electrode 48 of FIG. 1.
  • an electron beam of high current density for example of the order of 25 ampes per square centimeter, substantially demagnified in cross section by the focusing field between anode 13 and gate 14, and modulated in intensity by a control signal applied to gate 14, is supplied to aperture 18, and forms there a virtual cathode.
  • the prefocus-ing lens section 20 operates to provide a virtual image of the virtual cathode at aperture 18, which virtual image serves as the object for the main focusing lens 40. It has been found that the accelerating section has the electrical effect of elongating the distance from the principal plane of the main focusing lens to its effective object plane.
  • the magnification of the main focusing lens is proportional to the image distance divided by the eifective object distance, for a fixed image distance between the screen 8 and the main focusing lens 40 the image size or electron beam spot size on the screen is correspondingly decreased by the neck-elongating or object distance-elongating action of spiral accelerating electrode 31.
  • Dynamic focusing as well as control of resolution is provided conveniently by varying the potential of the wall 22 relative to the potential of surface 21 of the meniscus electrode 15, which in turn modifies the action of the prefocusing lens section 20.
  • the potential of wall 22 is increased above that of surface 21, the overall effect of the prefocus lens becomes positive or converging, and the virtual image of the aperture 18 produced by the prefocus lens sect1on moves rearwardly and increases in size. Since this virtual image serves as the effective object for the main focusing lens 40, the overall effect at the screen is one of moderate spot size enlargement with a considerable increase in beam current, such that the current density observed at the screen remains substantially constant.
  • the neck-elongating section may be arranged to act as a moderate converging lens for the electron beam, as well as an accelerator, for example by changing the spiral 31 from a uniform pitch to one having a pitch progressively increasing toward wall 37.
  • care must be taken that the converging lens action of the section 30 is not made so strong as to produce a second crossover of the electron beam before it reaches the screen 8, since such a result would cause undesired enlargement of the spot size at the screw.
  • adjustable centering coils 60 are provided, external to the tube neck in the vicinity of the electron beam generating section 10, to provide centering at aperture 18.
  • a similar set of coils 67 is provided in the vicinity of the spiral electrode 31 to provide centering at aperture 38. To avoid repetition, only coils 60 will be described in detail, it being understood that coils 67 are similar in all respects except for increased length, as is apparent from FIG. 1.
  • the centering coil assembly 60 outside section 10 consists of an insulating cylindrical support 61 on which are mounted two pairs of electromagnetic coils, the windings of the coils being designated AA, BB, CC, and DD for clarity.
  • Coils AA and BB are wound in series and supplied from a remote source of reversible-polarity, adjustable amplitude direct current, which may be for example a battery 62 and a potentiometer 63, and are for centering the beam in the horizontal direction.
  • Coils CC and DD are likewise wound in series and supplied from a remote source of reversible-polarity adjustable amplitude direct current, which as shown may be battery 62 and a potentiometer 64, and are for centering the beam in the vertical direction.
  • a remote source of reversible-polarity adjustable amplitude direct current which as shown may be battery 62 and a potentiometer 64, and are for centering the beam in the vertical direction.
  • an assembly of beam shaping coils 70 is provided external to the tube neck in the vicinity of the main focus lens section 40.
  • This beam shaping coil assembly 70 is shown in detail in the cross sectional view of FIG. 4. It consists of an insulating support cylinder 71 which is rotatably adjustable about the neck axis and on which are mounted four coils EE, FF, GG, and HH each arranged to subtend a 90 angle in a plane transverse to the neck axis.
  • the coils are Wound in series in a sense such as to develop two mutually perpendicular pairs of magnetic poles wherein adjacent poles are of opposite polarity and diametrically opposed poles have the same polarity, as shown in FIG. 4.
  • the coils are connected to a remote source of reversible-polarity adjustable-amplitude direct current, which may be for example a potentiometer 64 and battery 62 as shown in FIG. 3.
  • the N and S negative poles there shown which result from the current in coils E E, FF, GG, and HH, indicate how the mutually orthogonal forces of an electron beam passing in an axial direction through the field generated by coils EE, FF, GG and HH tend to correct ellipticity of the beam.
  • a beam having an undesired degree of ellipticity for example with a major axis 95, can be conveniently rendered circular in cross section merely by properly rotating the coil assembly 70 so that the beam compressing transverse magnetic fields thereof, as shown by poles N and S and vectors 72, coincide with and compress .the major axis of the ellipse, and the beam expanding transverse magnetic forces thereof, as shown by vectors 73, coincide with and expand the minor axis of the ellipse, and adjusting the current through the coils of assembly 70 for the desired degree of roundness of the beam.
  • a desired degree of ellipticity is required, such may be obtained even from a beam of perfectly circular cross section by suitably angularly adjusting the coil assembly and properly adjusting the amount of current through the coils of assembly 70.
  • the coil assembly 70 provides magnetic fields through the tube neck at the main focus lens section 40 which cannot provide any deflection of the beam in a manner such as would afiect its centering but which do distort or change as desired the cross sectional shape of the electron beam.
  • FIGS. 5 and 6 Alternative means for Vernier control of the cross sectional shape of the electron beam are shown are in FIGS. 5 and 6.
  • the apparatus of FIGS. 5 and 6 has the advantage that it effects control of beam shape entirely electrically, eliminating any need for mechanical rotation of a coil assembly around the tube neck.
  • This alternative beam shaping means includes an assembly of coils arranged external to the tube neck in the vicinity of the main focus lens section 40, and shown in detail in FIG. 5.
  • the coils of FIG. 5 are arranged and energized to provide magnetic fields which produce pairs of force vectors which act along the major and minor ellipse axes of the electron beam, similar to the action of vectors 72 and 73 of FIG. 4, except that with the apparatus of FIGS.
  • the force vectors can be electrically rotated through 360 to any desired angle of orientation, and the amplitude of each pair of vectors can be electrically varied from a maximum in one sense through zero to a maximum in the opposite sense.
  • the apparatus of FIGS. 5 and 6 can correct for, or introduce, any degree of ellipticity of the beam at any angular orientation of the ellipse axes.
  • FIG. 5 eight identical coils are provided in two sets of four coils each, designated A1, A2, A3, A4, and B1, B2, B3, B4.
  • the coils of the A set subtend adjacent angles of at the neck axis, and the coils of the B set likewise subtend adjacent angles of 90 but are displaced 45 relative to the A coils.
  • Each of the two current paths of each coil which extends parallel to the neck axis is centered in a sector subtending an angle of 22 /2 at the neck axis. Designating the current flow directions by plus and minus signs, the coil arrangement will be evident from FIG. 5.
  • All four A coils are wound in series and are supplied by direct current of controllable amplitude and reversible polarity, and all four B coils are Wound in series and supplies by direct current of controllable amplitude and reversible polarity, separately from the A coils.
  • the diametrically spaced coils of each set e.g., coils A2 and A4, provide magnetic poles of one polarity, say the North poles designated NA in FIG. 5, while the remaining coils A1 and A3 of the same set provide poles of opposite polarity, shown as SA in FIG. 5.
  • Such poles NA and SA correspond in function and effect to the N and S poles of FIG. 4.
  • the B coils provide poles SB and NB of FIG. 5.
  • the eight coils are capable of providing eight magnetic poles spaced 45 about the axis of the electron beam.
  • the polarity of any diametrically spaced pair of poles is always identical, and the polarity of any 90 spaced poles is always different, so that regardless of the effect on ellipticity there is no net effect on the centering of the electron beam.
  • the strength and polarity of each such pole may be adjusted from maximum in one sense through zero to maximum in the opposite sense, and thus the summed values of the mutually perpendicular pairs of force vectors exerted on the electron beam by such poles may be madeto rotate to any angle and have any desired amplitude.
  • the circuit of FIG. 6 includes a pair of field intensity control potentiometers 105, 113, which provide for control of the amplitude of the current fed to the A and B coils, respectively, and a pair of field orientation control potentiometers 103, 111.
  • the potentiometers 103 and 111 serve to impose a sine-cosine relationship on the variations in current amplitude and polarity supplied the respective A and B coil sets, and this enables control of the angular orientation of the summed force vectors produced by the magnetic poles of FIG. 5, throughout the entire 360.
  • one side of the A coil series is grounded, and the other side is connected through a current limiting resistor 101 and field orientation control potentiometer 103 to the field intensity control potentiometer 105 which with battery 107 provides a source of reversible polarity adjustable amplitude direct current.
  • one side of the B coil series is grounded and the other side is connected through resistor 109 and orientation control potentiometer 111 to a source of reversible polarity adjustable amplitude direct current at intensity control potentiometer 113.
  • the movable contacts 140, 141 of potentiometers 105, 113 are ganged, and their stationary windings are connected to battery 107 with opposite polarity.
  • Potentiometer 103 has four equal segments separating five terminals 115, 123, 124, 125, 126, and potentiometer 111 likewise has four equal segments separating five terminals 116, 127, 128, 129, 130.
  • the movable contacts 135, 136 of potentiometers 103 and 111 are ganged.
  • terminals 115, 124 and 126 of potentiometer 103 and the terminals 128 and 130 of potentiometer 111 are grounded, while terminals 123 and 129 are joined, 125 and 127 are joined, and 116 and 126 are joined.
  • Intensity control potentiometer 113 determines the maximum current of one polarity available to the B coils from the terminal 129 of potentiometer 111 and available to the A coils from terminal 123 of potentiometer 103, while potentiometer 105 controls the maximum current of the opposite polarity available to the A coils from terminal 125 of potentiometer 103 and available to the B coils from terminal 127 of potentiometer 111.
  • potentiometers 103, 113 control the maximum values of the currents available from contacts 135, 136, and hence control the amplitude of the force vectors affecting the ellipticity of the electron beam.
  • any degree of ellipticity may be introduced into or removed from the electron beam, without affecting its centering.
  • a high resolution electron optical system for a cathode ray tube or the ilke which permits the generation of extremely fine electron beam spot sizes of as little as a few microns diameter and within an overall length which is conveniently small.
  • the mechanical structure of a cathode ray tube embodying suc-h electron optical system is relatively simple and rugged, and associated means surrounding the axis of the system is provided for obtaining precise centering of the electron 'beam and thereby relaxing the tolerances of alignment of the parts.
  • a cathode ray tube constructed as above described has been found to provide very large screen current density of the order up to 2.0 amperes per square centimeter, with screen power loadings of up to approximately 50 kw. per square centimeter at 20 kw. screen potential and with a resolution of up to the equivalent of 10,000 raster lines on a 5" tube face. Such resolution is the equivalent of up to 400 complete TV pictures arranged in a square or up to million dots or 25 million bits of four increments per bit.
  • An electron optical system comprising, arranged in coaxial relation along a reference axis, an electron beam source, a target spaced from said source, a main electron beam focusing lens disposed between said source and said target, prefocusing electron lens means between said electron beam source and said main lens for providing an electron optical virtual image of said electron beam source for imaging on said target by said main focusing lens, a pair of electrode means in said prefocusing electron lens means and arranged for the application of different potentials thereto for adjusting the axial position of said virtual image, and a collimating electrode means between said main lens and said target to effectuate normal landing of electrons of said target, said collimating electrode being a non-linear spiral electrode of increasing electrical resistance per unit axial length towards said target including a cyclindrical constant electrical resistance portion at the end thereof facing said electron beam source.
  • an electron optical system comprising, arranged in coaxial relation, an electron beam source, a target spaced from said source, a main electron beam focusing lens disposed between said source and said target, an electron beam prefocusing electron lens disposed between said electron beam source and said target for providing an electron optical image of said electron beam source for imaging on said target by said main focusing lens, and accelerating spiral electrode means providing an axial electron accelerating field between said prefocusing lens and said main lens, and means for varying the strength of said accelerating field to vary the effective object distance of said main lens to reduce spot size on said target, the improvement comprising a spiral collimating electrode of increasing resistance towards said target coaxially positioned between said main focusing lens and said target to provide normal landing of electrons on said target.
  • spiral collimating electrode is a non linear spiral having increasing electrical resistance per unit of axial length in a direction towards said target.
  • an electron optical system comprising, arranged in coaxial relation along a reference axis, an electron beam source including an emitter, electrode means forming an electrostatic field having equipotential surfaces which are hyperboloids asymptotic to a conical surface of approximately 109 apex angle coaxial with said reference axis and with said apex facing away from said emitter, a target spaced from said source, a main electron beam focusing lens disposed between said source and said target, spiral accelerating electrode means providing an axial electron accelerating field between said main focusing lens and said electron beam source, and a prefocusing electron lens between said source and said accelerating electrode means for providing an electron optical virtual image of said electron beam source for imaging on said target by said main focusing lens, the improvement comprising a non linear spiral electrode positioned coaxially between said main lens and said target and having increasing electrical resistance in the axial direction towards said target to provide normal landing of electrons on said target.
  • an electron optical system comprising, arranged in coaxial relation, an electron beam source, a target spaced from said source, a main electron beam focusing lens disposed between said source and said target, prefocusing electron lens means between said source and said main lens for providing electron optical virtual image of said electron beam source for imaging on said target by said main lens, electrical means for controlling the effective object distance of said main lens, electron beam ellipticity control means including electromagnetic coil means for forming a plurality of transverse magnetic fields in the path of said beam and having diametrically spaced pairs of magnetic poles quadrilaterally spaced in a plane transverse to said beam, the poles of each diametrically spaced pair being of the same polarity and the adjacent poles of each quadrilaterally spaced set being of opposite polarity, and means for varying the strength and polarity of said poles, the improvement comprising (a) a non linear spiral collimating electrode positioned coaxially between said main lens and said target,
  • said spiral lens having increasing electrical resistance in a direction toward said target to provide normal landing of electrons on said target.
  • an electron optical system including an electron beam source and a target spaced from said source along a reference axis, said electron beam source including an anode electrode and a gate electrode, said anode electrode having a forwardly projecting convex surface coaxial with said reference axis, said gate electrode having a rearwardly directed concavity coaxial with said axis, said concavity being centrally apertured for passage of said electron beam, said gate electrode being adapted to have applied thereto modulation signals for varying the flow of electrons in said beam, prefocus lens means coaxially disposed between said target and said beam source and including an electrode having a forwardly concave conical surface of approximately 109 apex angle caxial with said axis and with the apex thereof facing said electron beam source, an axially apertured transverse electrode axially spaced forward of said conical surface, means forming an axial virtual cathode opening in said conical surface, means for directing said electron beam axially through said virtual cathode opening, electrode
  • an electron optical system including an electron beam source and a target spaced from said source along a reference axis, said electron beam source including an anode electrode and a gate electrode, said anode electrode having a forwardly projecting convex surface coaxial with said reference axis, said gate electrode having a rearwardly directed concavity coaxial with said axis, said concavity being centrally apertured for passage of said electron beam, said gate electrode being adapted to have applied thereto modulation signals for varying the flow of electrons in said beam, prefocus lens means forming between said target and said beam source an electrostatic field having equipotential surfaces which are hyperboloids asymptotic to a forwardly concave conical surface of approximately 109 apex angle coaxial with said reference axis with the apex of said conical surface facing said electron beam source, means for directing said electron beam axially into said prefocus lens field, electrode means forming a coaxial main focus lens intermediate said prefocus lens and said target, axially extending cylindrical
  • coaxial prefocus lens means forming an electrostatic field having equipotential surfaces which are hyperboloids asymptotic to a forwardly concave conical surface of approximately 109 apex angle coaxial with said axis, coaxial cylindrical spiral electrode means extending axially from said prefocus lens from the larger opening of said conical surface and forming a uniform axial electron accelerating field, and an axially apertured transverse electrode electrically connected to said spiral electrode separating said prefocus lens and said spiral electrode, and means for adjusting the potential of said transverse electrode, the improvement comprising (a) a non linear spiral collimating electrode positioned coaxially with and axially spaced from said transverse electrode to have a different potential applied thereto,
  • said collimating electrode having increasing electrical resistance per unit axial length in a direction away from said transverse electrode to collimate electrons emerging therefrom.

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US518160A 1966-01-03 1966-01-03 Electron optical system having spiral collimating electrode adjacent the target Expired - Lifetime US3375390A (en)

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US518160A US3375390A (en) 1966-01-03 1966-01-03 Electron optical system having spiral collimating electrode adjacent the target
GB42792/66A GB1142747A (en) 1966-01-03 1966-09-26 Improvements in electron optical systems
FR87366A FR1504388A (fr) 1966-01-03 1966-12-14 Système électro-optique

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Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3569772A (en) * 1966-01-28 1971-03-09 Telefunken Patent Cathode ray tube having an electrostatic accelerating lens
US3666985A (en) * 1969-10-20 1972-05-30 Gen Electric High resolution electron optic system for camera tubes
US3748514A (en) * 1971-08-18 1973-07-24 A Standaart Multi-beam cathode ray tube character display
US3810030A (en) * 1970-05-21 1974-05-07 Haefely & Cie Ag Emil Apparatus for focussing the beam of a particle accelerator
US3909655A (en) * 1972-07-05 1975-09-30 Thorn Electrical Ind Ltd Cathode ray tube having cylinder with internal resistive helix
US4142133A (en) * 1976-10-20 1979-02-27 Balandin Genrikh D Cathode-ray tube with variable energy of beam electrons
EP0198532A1 (fr) * 1985-04-01 1986-10-22 Koninklijke Philips Electronics N.V. Appareil de prise de vues
US4692658A (en) * 1986-04-28 1987-09-08 Rca Corporation Imaging system having an improved support bead and connector
US4713879A (en) * 1985-03-28 1987-12-22 U.S. Philips Corporation Method of manufacturing a device having an electric resistance layer and the use of the method
US4853601A (en) * 1987-11-02 1989-08-01 Tektronix, Inc. Multiple beam electron discharge tube having bipotential acceleration and convergence electrode structure
US4853589A (en) * 1987-03-25 1989-08-01 U.S. Philips Corporation Electron beam device having an electron gun and a method of making the electron gun
US4857797A (en) * 1986-02-17 1989-08-15 U.S. Philips Corporation Cathode ray tube having a tubular electron gun structure
EP0342761A1 (fr) * 1988-05-20 1989-11-23 Koninklijke Philips Electronics N.V. Tube image comportant une lentille de focalisation hélicoidale munie d'un élément de lentille ne présentant pas de symétrie de révolution
EP0362922A1 (fr) * 1988-09-21 1990-04-11 Koninklijke Philips Electronics N.V. Tube à rayons cathodiques comportant une lentille de focalisation en spirale
US4945283A (en) * 1988-01-27 1990-07-31 U.S. Philips Corporation Cathode ray tube having a tubular focus structure
US4988928A (en) * 1989-01-12 1991-01-29 U.S. Philips Corporation Picture display device

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL8500500A (nl) * 1985-02-22 1986-09-16 Philips Nv Kathodestraalbuis met een stigmator voor bundelfoutcorrectie.

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3040205A (en) * 1960-05-31 1962-06-19 Harold R Walker Electrostatic vidicon

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3040205A (en) * 1960-05-31 1962-06-19 Harold R Walker Electrostatic vidicon

Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3569772A (en) * 1966-01-28 1971-03-09 Telefunken Patent Cathode ray tube having an electrostatic accelerating lens
US3666985A (en) * 1969-10-20 1972-05-30 Gen Electric High resolution electron optic system for camera tubes
US3810030A (en) * 1970-05-21 1974-05-07 Haefely & Cie Ag Emil Apparatus for focussing the beam of a particle accelerator
US3748514A (en) * 1971-08-18 1973-07-24 A Standaart Multi-beam cathode ray tube character display
US3909655A (en) * 1972-07-05 1975-09-30 Thorn Electrical Ind Ltd Cathode ray tube having cylinder with internal resistive helix
US4142133A (en) * 1976-10-20 1979-02-27 Balandin Genrikh D Cathode-ray tube with variable energy of beam electrons
US4713879A (en) * 1985-03-28 1987-12-22 U.S. Philips Corporation Method of manufacturing a device having an electric resistance layer and the use of the method
EP0198532A1 (fr) * 1985-04-01 1986-10-22 Koninklijke Philips Electronics N.V. Appareil de prise de vues
US4857797A (en) * 1986-02-17 1989-08-15 U.S. Philips Corporation Cathode ray tube having a tubular electron gun structure
US4692658A (en) * 1986-04-28 1987-09-08 Rca Corporation Imaging system having an improved support bead and connector
US4853589A (en) * 1987-03-25 1989-08-01 U.S. Philips Corporation Electron beam device having an electron gun and a method of making the electron gun
US4853601A (en) * 1987-11-02 1989-08-01 Tektronix, Inc. Multiple beam electron discharge tube having bipotential acceleration and convergence electrode structure
US4945283A (en) * 1988-01-27 1990-07-31 U.S. Philips Corporation Cathode ray tube having a tubular focus structure
EP0342761A1 (fr) * 1988-05-20 1989-11-23 Koninklijke Philips Electronics N.V. Tube image comportant une lentille de focalisation hélicoidale munie d'un élément de lentille ne présentant pas de symétrie de révolution
EP0362922A1 (fr) * 1988-09-21 1990-04-11 Koninklijke Philips Electronics N.V. Tube à rayons cathodiques comportant une lentille de focalisation en spirale
US4961023A (en) * 1988-09-21 1990-10-02 U.S. Philips Corporation Cathode ray tube including a helical focusing lens
US4988928A (en) * 1989-01-12 1991-01-29 U.S. Philips Corporation Picture display device

Also Published As

Publication number Publication date
GB1142747A (en) 1969-02-12
FR1504388A (fr) 1967-12-01

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