US3890529A - Compound electrostatic lens system - Google Patents

Compound electrostatic lens system Download PDF

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Publication number
US3890529A
US3890529A US473539A US47353974A US3890529A US 3890529 A US3890529 A US 3890529A US 473539 A US473539 A US 473539A US 47353974 A US47353974 A US 47353974A US 3890529 A US3890529 A US 3890529A
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section
serrations
pattern
electrode
sections
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US473539A
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Rudolf G E Hutter
Herman O Dressel
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Verizon Laboratories Inc
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GTE Laboratories Inc
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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
    • H01J29/465—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement for simultaneous focalisation and deflection of ray or beam

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  • US. Pat. No. 2,080,449 to von Ardenne discloses an electrode system for use in a cathode-ray tube in which one electrode is used to focus the electron beam and another electrode, which is compound of cylindrical sections, is used to accelerate the focused beam.
  • U.S. Pat. No. 2,312,723 to Llewellyn discloses an electrode system in which two adjacent cylinders are abutted at a cyclic crenel to produce an accelerating electrode. Llewellyn changes the cylinders into cones for use in focusing.
  • an Einzel lens By the use of at least three cylinders substantially abutted but insulated at serrated or crenellated joints, and where the potential distribution is rotationally symmetrical about the cylinder axis everywhere the electron beam traverses the lens, an Einzel lens can be constructed. If the angular dependent terms are multiplied by radius factors of eight or higher, as by constructing serrations with octupolar (or higher order) symmetry, then even fifth-order lens aberrations are not affected by non-rotationally-symmetrical components of the potential distribution. This analysis is closely confirmed by experiment, so that the axial potential distribution may safely be used to calculate paraxial and third order lens properties. Furthermore, if one can assume that the potential variation across the insulated gap between cylinders is linear, then the potential distribution is essentially the same as that for truly rotationally symmetrical structures.
  • the shape of the serrations can be chosen to alter the potential variation along the cylinder while entrance and exit poteptials and length and radius of the lens remain constant.
  • FIG. 1 is an overall view of a compound electrode lens system according to the invention.
  • FIG. 2 is a cross-sectional view of a portion of the electrode to show one mode of construction.
  • FIGS. 3, 4 and 5 illustrate developed or unrolled forms of three octupolar electrodes of three cylindrical electrode sections each.
  • FIG. 6 illustrates a developed l2-pole electrode of three cylindrical electrode sections.
  • FIG. 7 illustrates a developed octupolar electrode of four cylindrical electrode sections.
  • FIG. I is an overall diagram of a compound electrostatic electrode system according to the present invention.
  • An electron beam e is supplied by a cathode 2 and directed through a compound cylindrical electrode to a target which is not illustrated.
  • the electrode illustrated in FIG. 1 comprises first, second and third cylindrical electrode sections 6, 8 and 10.
  • the first elec trode section 6 is even ended at one end 12 and terminates in serrations of a first pattern at its other end I4.
  • the second electrode section 8 has one of its ends 16 substantially adjacent to but insulated from the end 14 of the first section 6. End 16 of section 8 terminates in serrations which complement or fill in the serrations of the first pattern in end 14.
  • the other end 18 of electrode section 8 terminates in serrations of a second pattern, which may be the same as or different from the first pattern.
  • the third section I0 has one end 20 substantially adjacent to but insulated from the end I8 of the second section 8.
  • the end 20 of the third section terminates in serrations which complement or fill in the serrations of the second pattern in end 18.
  • the other end 22 of electrode section is even ended.
  • a means is provided for applying chosen potentials V V and V to each of the three sections.
  • potentials V, and V are equal, while potential V is different.
  • the first and second patterns are cyclic patterns which repeat around the circumference of the cylindrical sections.
  • the patterns preferably repeat at least eight times around the circumference, so that angular dependent terms for potential distribution within the cylindrical electrodes are multiplied by radius factors (measured from the cylinder axis) of the order eight or higher, whereby even fifth-order lens aberrations are not affected by non-rotationally symmetrical components of the potential distribution.
  • the pattern must be circumferentially periodic and must be of higher order than octupolar symmetry. For such symmetry, a diameter line constructed at any point on the cylindrical axis of the electrode and rotated to any rotational position will find points of equal potential at its opposite ends.
  • FIG. 2 illustrates a preferred method of constructing such a compound electrode.
  • a non-conductive substrate 26 (shown in cross section) forms the outer wall of electrode 4 and is plated on its inside surface with patterned metal conductors 28 separated by empty insulation gaps 30.
  • FIGS. 3, 4 and 5 illustrate electrode systems with octupolar symmetry. These figures represent developed or unrolled versions of the cylindrical electrode system as in FIG. 1.
  • the embodiment of FIG. 3 uses first and second patterns of serrations, both of which are in a sawtooth form. As illustrated, the cylindrical sections 6, 8 and 10 are separated by a narrow non-conductive ribbon such that each cylindrical section is substantially adjacent to but insulated from the adjacent cylindrical section.
  • the embodiments of FIGS. 4 and 5 use curved cyclical patterns of serrations.
  • FIG. 6 illustrates a symmetrical pattern of higher order than eight. Specifically, this cylical pattern repeats twelve times around the circumference.
  • FIG. 7 illustrates an electrode system in which the middle electrode section 8 is further broken down into two subsections 8a and 8b which are substantially adjacent to but insulated from each other. These subsections may have different voltages applied thereto.
  • the use of subsections allows the use of multiple potential steps in sequence, thereby distributing the potential change at the boundary over many insulated regions, reducing the breakdown problem between adjacent electrodes.
  • a compound electrostatic electrode lens system for combined focusing and acceleration of an electron beam comprising:
  • the second section having one end substantially adjacent to but insulated from the other end of the first section, the one end of the second section terminating in serrations which fill in the serrations of a first pattern of the first section, the other end of the second section terminating in serrations of a second pattern,
  • the third section having one end substantially adjacent to but insulated from the other end of the second section, the one end of the third section terminating in serrations which fill in the serrations of a second pattern of the second section, the other end of the third section being even ended, and
  • both the first pattern and the second pattern are cyclic patterns which repeat at least eight times around the circumference of the cylindrical sections and which are diametrically symmetrical with respect to the axis of the cylindrical sections at all points on the axis and all rotational positions of the diameter.

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Abstract

A cylindrical electrostatic electrode system for use as an electron lens. Several cylindrical sections, while insulated from each other, are provided with complimentary end serrations and abutted together. The serrations are rotationally symmetrical with repetition factors of eight or higher. The electrode segments are provided with different potentials, whereby axial potential distribution can be closely controlled with no resulting low-order angular dependent lens aberrations.

Description

United States Patent [191 Hutter et al.
[ June 17, 1975 COMPOUND ELECTROSTATIC LENS SYSTEM [75) Inventors: Rudolf G. E. Butter, New York,
N.Y.; Herman O. Dressel, Lynnfield, Mass.
[73] Assignee: GTE Laboratories Incorporated,
Waltham, Mass.
22 Filed: May 28,1974
211 Appl.No.:473,539
52 use: ..313/460;3l5/ISX 5| Int. Cl HOlj 29/02; HOlj 29/48 58 Field ofSearch ..313/44|.450, 449, 44s,
[56] References Cited UNITED STATES PATENTS 3,73l.l36 5/l973 Roussin 313/434 X Primary ExaminerRobert Segal Attorney, Agent, or Firmlrving M. Kriegsman; Leslie J. Hart [57] ABSTRACT 5 Claims, 6 Drawing Figures CATllOM COMPOUND ELECTROSTATIC LENS SYSTEM BACKGROUND OF THE INVENTION l. FIELD ,OF THE. INVENTION This invention relates to eiectrostatic electron lenses, and especially to multi-electrode cylindrical lenses of the type used in cathode-ray tubes.
2. DESCRIPTION OF THE PRIOR ART US. Pat. No. 3,678,320 to Barten describes an electrode system for cathode-ray tubes in which two adjacent cylindrical grids are abutted at a preferably sinusoidal set of crenels. The number of sinusoidal cycles around the circumference of the grids is normally three, which is both low in number and nonsymmetrical, resulting in low order angular dependent lens aberrations.
US. Pat. No. 2,080,449 to von Ardenne discloses an electrode system for use in a cathode-ray tube in which one electrode is used to focus the electron beam and another electrode, which is compound of cylindrical sections, is used to accelerate the focused beam.
U.S. Pat. No. 2,312,723 to Llewellyn discloses an electrode system in which two adjacent cylinders are abutted at a cyclic crenel to produce an accelerating electrode. Llewellyn changes the cylinders into cones for use in focusing.
SUMMARY OF THE INVENTION By the use of at least three cylinders substantially abutted but insulated at serrated or crenellated joints, and where the potential distribution is rotationally symmetrical about the cylinder axis everywhere the electron beam traverses the lens, an Einzel lens can be constructed. If the angular dependent terms are multiplied by radius factors of eight or higher, as by constructing serrations with octupolar (or higher order) symmetry, then even fifth-order lens aberrations are not affected by non-rotationally-symmetrical components of the potential distribution. This analysis is closely confirmed by experiment, so that the axial potential distribution may safely be used to calculate paraxial and third order lens properties. Furthermore, if one can assume that the potential variation across the insulated gap between cylinders is linear, then the potential distribution is essentially the same as that for truly rotationally symmetrical structures.
The shape of the serrations can be chosen to alter the potential variation along the cylinder while entrance and exit poteptials and length and radius of the lens remain constant.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall view of a compound electrode lens system according to the invention.
FIG. 2 is a cross-sectional view of a portion of the electrode to show one mode of construction.
FIGS. 3, 4 and 5 illustrate developed or unrolled forms of three octupolar electrodes of three cylindrical electrode sections each.
FIG. 6 illustrates a developed l2-pole electrode of three cylindrical electrode sections.
FIG. 7 illustrates a developed octupolar electrode of four cylindrical electrode sections.
DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. I is an overall diagram of a compound electrostatic electrode system according to the present invention. An electron beam e is supplied by a cathode 2 and directed through a compound cylindrical electrode to a target which is not illustrated. The electrode illustrated in FIG. 1 comprises first, second and third cylindrical electrode sections 6, 8 and 10. The first elec trode section 6 is even ended at one end 12 and terminates in serrations of a first pattern at its other end I4. The second electrode section 8 has one of its ends 16 substantially adjacent to but insulated from the end 14 of the first section 6. End 16 of section 8 terminates in serrations which complement or fill in the serrations of the first pattern in end 14. The other end 18 of electrode section 8 terminates in serrations ofa second pattern, which may be the same as or different from the first pattern. The third section I0 has one end 20 substantially adjacent to but insulated from the end I8 of the second section 8. The end 20 of the third section terminates in serrations which complement or fill in the serrations of the second pattern in end 18. The other end 22 of electrode section is even ended.
A means is provided for applying chosen potentials V V and V to each of the three sections. In a preferred embodiment in which the electrostatic lens system is used as an Einzel lens, potentials V, and V are equal, while potential V is different.
The first and second patterns are cyclic patterns which repeat around the circumference of the cylindrical sections. The patterns preferably repeat at least eight times around the circumference, so that angular dependent terms for potential distribution within the cylindrical electrodes are multiplied by radius factors (measured from the cylinder axis) of the order eight or higher, whereby even fifth-order lens aberrations are not affected by non-rotationally symmetrical components of the potential distribution.
The pattern must be circumferentially periodic and must be of higher order than octupolar symmetry. For such symmetry, a diameter line constructed at any point on the cylindrical axis of the electrode and rotated to any rotational position will find points of equal potential at its opposite ends.
FIG. 2 illustrates a preferred method of constructing such a compound electrode. A non-conductive substrate 26 (shown in cross section) forms the outer wall of electrode 4 and is plated on its inside surface with patterned metal conductors 28 separated by empty insulation gaps 30.
FIGS. 3, 4 and 5 illustrate electrode systems with octupolar symmetry. These figures represent developed or unrolled versions of the cylindrical electrode system as in FIG. 1. The embodiment of FIG. 3 uses first and second patterns of serrations, both of which are in a sawtooth form. As illustrated, the cylindrical sections 6, 8 and 10 are separated by a narrow non-conductive ribbon such that each cylindrical section is substantially adjacent to but insulated from the adjacent cylindrical section. The embodiments of FIGS. 4 and 5 use curved cyclical patterns of serrations.
FIG. 6 illustrates a symmetrical pattern of higher order than eight. Specifically, this cylical pattern repeats twelve times around the circumference.
FIG. 7 illustrates an electrode system in which the middle electrode section 8 is further broken down into two subsections 8a and 8b which are substantially adjacent to but insulated from each other. These subsections may have different voltages applied thereto. The use of subsections allows the use of multiple potential steps in sequence, thereby distributing the potential change at the boundary over many insulated regions, reducing the breakdown problem between adjacent electrodes.
What is claimed is:
l. A compound electrostatic electrode lens system for combined focusing and acceleration of an electron beam comprising:
A. first, second and third cylindrical electrode sections,
By the first section being even ended at one end and terminating in serrations of a first pattern at its other end,
C, the second section having one end substantially adjacent to but insulated from the other end of the first section, the one end of the second section terminating in serrations which fill in the serrations of a first pattern of the first section, the other end of the second section terminating in serrations of a second pattern,
D. the third section having one end substantially adjacent to but insulated from the other end of the second section, the one end of the third section terminating in serrations which fill in the serrations of a second pattern of the second section, the other end of the third section being even ended, and
E. means for applying chosen potentials to each of the three sections,
wherein both the first pattern and the second pattern are cyclic patterns which repeat at least eight times around the circumference of the cylindrical sections and which are diametrically symmetrical with respect to the axis of the cylindrical sections at all points on the axis and all rotational positions of the diameter.
2. A system according to claim 1 for use as an Einzel lens wherein the means for applying chosen potentials comprises means for applying a first potential to the first and third sections and for applying a second potential to the second section.
3. A system according to claim 1 wherein the cyclic patterns repeat eight times around said circumference.
4. A system according to claim 1 wherein at least one of said patterns is a sawtooth pattern.
5. A system according to claim 1, wherein the second section is divided into a plurality of cylindrical subsections arranged in axial sequence along the electrode system, the ends of two end subsections forming the end of the second section, subsections being substantially adjacent to but insulated from sequential subsections with further symmetrical patterns of serrations therebetween.

Claims (5)

1. A compound electrostatic electrode lens system for combined focusing and acceleration of an electron beam comprising: A. first, second and third cylindrical electrode sections, GB. the first section being even ended at one end and terminating in serrations of a first pattern at its other end, C. the second section having one end substantially adjacent to but insulated from the other end of the first section, the one end of the second section terminating in serrations which fill in the serrations of a first pattern of the first section, the other end of the second section terminating in serrations of a second pattern, D. the third section having one end substantially adjacent to but insulated from the other end of the second section, the one end of the third section terminating in serrations which fill in the serrations of a second pattern of the second section, the other end of the third section being even ended, and E. means for applying chosen potentials to each of the three sections, wherein both the first pattern and the second pattern are cyclic patterns which repeat at least eight times around the circumference of the cylindrical sections and which are diametrically symmetrical with respect to the axis of the cylindrical sections at all points on the axis and all rotational positions of the diameter.
2. A system according to claim 1 for use as an Einzel lens wherein the means for applying chosen potentials comprises means for applying a first potential to the first and third sections and for applying a second potential to the second section.
3. A system according to claim 1 wherein the cyclic patterns repeat eight times around said circumference.
4. A system according to claim 1 wherein at least one of said patterns is a sawtooth pattern.
5. A system according to claim 1, wherein the second section is divided into a plurality of cylindrical subsections arranged in axial sequence along the electrode system, the ends of two end subsections forming the end of the second section, subsections being substantially adjacent to but insulated from sequential subsections with further symmetrical patterns of serrations therebetween.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2559950A1 (en) * 1984-02-20 1985-08-23 Sony Corp CATHODE RAY TUBE
US4651050A (en) * 1984-02-16 1987-03-17 Sony Corporation Cathode ray tube

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3731136A (en) * 1971-04-19 1973-05-01 Gen Electric Cylindrical electrode system for focusing and deflecting an electron beam

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3731136A (en) * 1971-04-19 1973-05-01 Gen Electric Cylindrical electrode system for focusing and deflecting an electron beam

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4651050A (en) * 1984-02-16 1987-03-17 Sony Corporation Cathode ray tube
FR2559950A1 (en) * 1984-02-20 1985-08-23 Sony Corp CATHODE RAY TUBE
US4933597A (en) * 1984-02-20 1990-06-12 Sony Corporation Cathode ray tube

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