US3819984A - Side-by-side dual gun crt having horizontal deflector plates provided with side shields for correction of geometric distortion - Google Patents

Side-by-side dual gun crt having horizontal deflector plates provided with side shields for correction of geometric distortion Download PDF

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Publication number
US3819984A
US3819984A US00331457A US33145773A US3819984A US 3819984 A US3819984 A US 3819984A US 00331457 A US00331457 A US 00331457A US 33145773 A US33145773 A US 33145773A US 3819984 A US3819984 A US 3819984A
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United States
Prior art keywords
electron beam
deflection
electron
horizontal deflection
horizontal
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Expired - Lifetime
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US00331457A
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English (en)
Inventor
K Hawken
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Tektronix Inc
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Tektronix Inc
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Publication date
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Priority to US00331457A priority Critical patent/US3819984A/en
Priority to NL7401634A priority patent/NL7401634A/xx
Priority to DE19742406060 priority patent/DE2406060A1/de
Priority to FR7405098A priority patent/FR2217795B3/fr
Priority to JP49017091A priority patent/JPS5041468A/ja
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Publication of US3819984A publication Critical patent/US3819984A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
    • H01J31/12—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen
    • 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
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/701—Systems for correcting deviation or convergence of a plurality of beams by means of magnetic fields at least
    • H01J29/702—Convergence correction arrangements therefor
    • H01J29/705—Dynamic convergence systems
    • 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
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/72—Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
    • H01J29/74—Deflecting by electric fields only
    • 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
    • H01J29/80—Arrangements for controlling the ray or beam after passing the main deflection system, e.g. for post-acceleration or post-concentration, for colour switching

Definitions

  • ABSTRACT A cathode ray tube having dual electron beam guns and associated deflection means is described in which the electron beam guns are disposed in a plane containing the tube axis and such that the electron beam guns are located in planes spaced to the left and right of the tube axis which are normal to the first mentioned plane so that the electron beam guns are parallel to provide asymmetrical horizontal scanning thereby requiring less space in the tube neck.
  • the horizontal deflection plate means is provided with side shields which provides dynamic geometry correction as the tube is operated.
  • RAMP 74 can. 82
  • VERT AMP has Fig-4C Fig4B Fig-4A SIDE-BY-SIDE DUAL GUN CRT HAVING HORIZONTAL DEFLECTOR PLATES PROVIDED WITH SIDE SHIELDS FOR CORRECTION OF GEOIVETRIC DISTORTION BACKGROUND OF THE INVENTION
  • the present invention relates generally to electron beam tubes having dual beams and associated deflection means, and more particularly to cathode ray tubes having dual electron beam guns that provide asymmetrical horizontal scanning and side shield means are provided by the horizontal deflection plate means to provide dynamic geometry correction during operation of the tube.
  • Cathode ray tubes having dual electron beam guns are known wherein stacked electron guns are disposed above and below the tube axis in a plane passing therethrough so that the horizontal angle of sweep of the electron beams are swept across the tube target equiangularly on each side of the tube or gun axis.
  • the guns are angled, but such angling distorts the scanned pattern from a rectangle to a trapezoid. With stacked guns, this trapezoidal distortion is easily corrected by adjusting the horizontal deflectors to be nonparallel from side to side thereby affecting the horizontal sensitivity as the tube is scanned vertically.
  • PDA divergent post deflection accelleration
  • the present invention reduces CRT volume in the gun area by disposing the electron beam guns side-byside and parallel to each other and in a plane containing the tube axis and the use of side shield means by the deflection plates for the horizontal scan in order to correct for trapezoidal distortion.
  • An object of the present invention is to provide a dual beam CRT in which parallel electron beam guns are disposed side-by-side to render the gun area smaller.
  • Another object of the present invention is the provision of a dual beam CRT wherein the horizontal deflection means is provided with dynamic geometry correction means.
  • a further object of the present invention is to provide a dual beam CRT in which the dynamic geometry correction means comprises side shield means to prevent trapezoidal distortion.
  • An additional object of the present invention is the provision of a dual beam CRT having two pairs of horizontal deflection plates in which side shield plate means extend inwardly from the outer plates and cover the gap between respective pairs of the plates.
  • a still further object of the present invention is to provide an improved cathode ray tube having two electron beam deflection means in which trapezoidal distortion is eliminated from the beam displays in a simple and inexpensive manner.
  • FIG. I is a schematic diagram of the cathode ray tube of the present invention.
  • FIG. 2 is a horizontal sectional view taken along the line 2-2 of FIG. 1 formed of the deflection means;
  • FIG. 3 is a view taken along the line 3-3 of FIG. 1;
  • FIGS. 4A, 4B and 4C illustrate rectangular displays formed by an electron beam on the fluorescent screen of a cathode ray tube.
  • a cathode ray tube 10 or other electron beam deflection device has an evacuated envelope 12 of glass, ceramic or other suitable insulating material in which a fluorescent screen 14 of phosphor material coated on the inner surface of a light transparent faceplate 16 which is secured onto the front end of such envelope.
  • a thin metallic coating 17 preferably of aluminum is disposed on the gun side of screen 14.
  • Two separate electron guns of conventional design are disposed in envelope 12 which include cathodes 18 and 20, control grids 22 and 24 and focusing anodes 26 and 28.
  • two separate electron beam deflection systems are provided in envelope 12 including a first pair of vertical deflection plates 30 and a second pair of vertical deflection plates 32 as well as a first pair of horizontal deflection plates 34 and a second pair of horizontal deflection plates 36.
  • cathode 18 has associated therewith control grid 22, focusing anodes 26, vertical deflection plates 30 and horizontal deflection plates 34 for controlling the electron beam 18a emanating from cathode 18 whereas cathode 20 has associated therewith control grid 24, focusing anodes 28, vertical deflection plates 32 and horizontal deflection plates 36 for controlling the electron beam 20a emitted from cathode 20.
  • Cathodes l8 and 20 operate at 3KV.
  • Horizontal deflection plates 34 and 36 are identical in configuration and each pair comprises an outer planar plate 38 and an inner plate 40 which has a rear section disposed at a slight angle away from its electron beam axis and a forward section disposed at a greater angle away from its electron beam axis.
  • the horizontal deflector plates are usually essentially flat plates facing each other and bent to form a wedge-shaped spacing between them.
  • Side shields 42 are provided by outer plates 38 which cover the gap between plates 38 and 40 at least along forward sections of plates 40. Side shields 42 can be integral extensions of plates 38 or additional metallic members secured as by welding onto plates 38.
  • Side shields 42 may also extend from plates 40, and they may have an angular edge, when they are part of plates 38, which coincides with the angular disposition of the forward section of plates 40.
  • side shields 42 may be independent plates disposed in position adjacent plates 38 and 40 via dielectric mounting means in a conventional manner.
  • An inner gun shield 44 is disposed between the pairs of horizontal deflection plates 34 and 36 in order to prevent the electrostatic fields generated by the respective pairs of horizontal deflection plates from affecting each other. Shield 44 is operated at near the average potential of the potential of the horizontal deflection means.
  • Compensator plates 46 are mounted between the pairs of vertical deflection plates to prevent the electrostatic fields of these vertical deflection means from interfering with each other as well as providing compensation so that the characteristic impedance is constant therealong. Plates 46 are operated at near the average potential of the vertical deflection means.
  • isolation shield 48 is disposed between the output ends of the vertical deflection plates 30 and 32 and the imput ends of the horizontal deflection plates 34 and 36 and it includes vertical slots 50 and 52 through which the electron beams 18a and 20a pass. Shield 48 isolates the electrostatic fields of the vertical deflection means from the electrostatic fields of the horizontal deflection means and it is operated at near the average potential of the vertical and horizontal deflection means.
  • An annular mounting and shielding member 54 is disposed in envelope 12 so that it has the output ends of horizontal deflection means 34 and 36 positioned therein and it is operated at near ground potential. Member 54 serves to shield the horizontal deflection means from the high voltage of post deflection acceleration 56 which consists of a conductive coating on the interior surface of envelope 12 in electrical contact with metallic coating 17 and has an operating voltage of ZOKV thereon.
  • a scan expansion mesh 58 is secured on the member 54 which has an outwardly-directed hemispherical configuration to provide diverging lens for scan expansion and it causes the electron beams to be effectively scanned over the screen in full overlap operation.
  • lnput signals are applied at input terminals 60 and 62 which are connected respectively to vertical amplifiers 64 and 66.
  • the outputs from vertical amplifiers 64 and 66 are connected respectively to vertical deflection means 30 and 32.
  • Horizontal ramp generators 68 and 70 are triggered in response to the receipt of input signals at input terminals 60 and 62 by providing trigger circuits 72 and 74 having their inputs connected respectively to input terminals 60 and 62 and having their outputs connected respectively to the inputs of horizontal ramp generators 68 and 70 which in turn have their outputs connected respectively to horizontal deflection means 34 and 36.
  • electron beams 18a and 20a emitted respectively from cathodes l8 and 20 are properly focused by focusing anodes 26 and 28, thereafter vertical deflection means 30 and 32 and horizontal deflection means 34 and 36 operate on the focused electron beams to deflect the beams in accordance with the signals at input terminals 60 and 62 whereafter the beams are passed through scan expansion mesh 58 whereby they are accelerated about 2lKV before they strike the target comprising phosphor layer 14 and metallic coating 17 which produces light images of these electron beams, which under most circumstances, will be the signal waveform traces of the vertical deflection signals.
  • the thin film of aluminum which is several angstroms thick, is electron transparent and reflects the light emitted by the phosphor layer 16 to increase the brightness of the displays in a conventional manner.
  • the electron guns and their associated deflection means are disposed side by side instead of in a conventional stacked condition so that the axes of these dual electron guns and associated deflection means are located in a plane containing tube axis TA.
  • the axis of the electron guns are disposed equidistantly on each side of tube axis TA.
  • the parallel disposition of the electron guns enables the neck of the CRT to be smaller so that more room is provided in an instrument in which the CRT is disposed.
  • the left electron beam 18a is scanned a small angle to the left when viewing the screen and a large angle to the right over the entire screen
  • the right electron beam 200 is scanned a large angle to the left and a small angle to the right over the entire screen.
  • the electron beams can simultaneously scan over the entire screen in an overlapping manner thereby displaying dual images thereon for observation.
  • the display generated by the left electron gun means would provide a trapezoidal display as shown in FIG. 4A whereby the horizontal lines above and below the center horizontal line will de viate away therefrom in a direction from left to right, whereas the display generated by the right electron gun means would provide a trapezoidal display as shown in FIG. 4B whereby the horizontal lines above and below the center horizontal line will deviate away therefrom in a direction opposite to that of the display of the left gun means as shown by FIG. 4A.
  • the interaction of the electrostatic fields of the vertical and horizontal deflection means without side shields 42 for the horizontal deflection means will provide displays having trapezoidal distortion as shown by FIGS.
  • the invention relative to the provision of side shield means for the horizontal deflection means can also be used in the case of a storage CRT wherein the electron gun and associated deflection means are offset relative to the tube axis and the flood gun axis is coincident with the tube axis so that only a single flood gun is used, and in its axis being coincident with the tube axis, the flood gun electrons are uniformly distributed over the screen.
  • the vertical deflection means as hereinabove described, can be used in a CRT which will operate up to megahertz, however, for CRT operation above this bandwidth, the vertical deflection means will be of the type disclosed in US. Pat. No. 3,694,689.
  • An electron beam apparatus comprising:
  • dual electron gun means disposed side-by-side in said envelope on each side of a central axis of said envelope and spaced from said target means for generating electron beams therefrom;
  • deflection means for each of said dual electron gun means disposed between said electron gun means and said target means for deflecting said electron beams over said target means in accordance with signal voltages applied thereto to provide image displays thereover.
  • An electron beam apparatus according to claim 1 wherein said deflection means are disposed to deflect said electron beams over said target means in simultaneous overlapping relationship.
  • deflection means comprise vertical deflection means and horizontal deflection means with the vertical and horizontal deflection means for one of said dual electron gun means deflecting the electron beam thereof a small angle and then a large angle during a horizontal scanning operation thereof and with the vertical and horizontal deflection means for the other of said dual electron gun means deflecting the electron beam thereof a large angle and then a small angle during a horizontal scanning operation thereof.
  • An electron beam apparatus according to claim 1 wherein means are provided by said deflection means to correct for trapezoidal deflection of said electron beams.
  • a cathode ray tube comprising:
  • electron gun means disposed in said envelope for generating electron beam means and being spaced from said target means;
  • deflection means disposed in said envelope between said target means and said electron gun means and including vertical and horizontal deflection plate means for deflecting said electron beam means over said target means in accordance with signal voltages applied to said vertical and horizontal deflection plate means;
  • a cathode ray tube according to claim 8 wherein said electron gun means comprise dual electron gun means and said deflection means comprise independent vertical and horizontal deflection means for each of said dual electron gun means.
  • a horizontal deflection system for an electron beam apparatus comprising:
  • spaced plate means having rear sections and forward sections;
  • side shield means disposed at right angles relative to at least said forward sections and covering the gap therebetween.
  • a horizontal deflection system according to claim 12 wherein said plate means comprise pairs of spaced plate means disposed in alignment and said side shield means are integrally connected to outer plate members which extend toward each other.

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  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
US00331457A 1973-02-12 1973-02-12 Side-by-side dual gun crt having horizontal deflector plates provided with side shields for correction of geometric distortion Expired - Lifetime US3819984A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US00331457A US3819984A (en) 1973-02-12 1973-02-12 Side-by-side dual gun crt having horizontal deflector plates provided with side shields for correction of geometric distortion
NL7401634A NL7401634A (enrdf_load_stackoverflow) 1973-02-12 1974-02-06
DE19742406060 DE2406060A1 (de) 1973-02-12 1974-02-08 Elektronenstrahlvorrichtung
FR7405098A FR2217795B3 (enrdf_load_stackoverflow) 1973-02-12 1974-02-11
JP49017091A JPS5041468A (enrdf_load_stackoverflow) 1973-02-12 1974-02-12

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00331457A US3819984A (en) 1973-02-12 1973-02-12 Side-by-side dual gun crt having horizontal deflector plates provided with side shields for correction of geometric distortion

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US3819984A true US3819984A (en) 1974-06-25

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US (1) US3819984A (enrdf_load_stackoverflow)
JP (1) JPS5041468A (enrdf_load_stackoverflow)
DE (1) DE2406060A1 (enrdf_load_stackoverflow)
FR (1) FR2217795B3 (enrdf_load_stackoverflow)
NL (1) NL7401634A (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921025A (en) * 1974-07-05 1975-11-18 Tektronix Inc Dual-beam CRT with vertical trace bowing correction means
US3983444A (en) * 1974-07-05 1976-09-28 Tektronix, Inc. Dual beam CRT with inner gun and outer gun shield means for correcting keystone distortion
US4335380A (en) * 1980-06-16 1982-06-15 Wright David Y Multi-beam raster scan display monitor
US4371808A (en) * 1979-12-07 1983-02-01 Iwatsu Electric Co., Ltd. One-gun two-beam cathode ray tube
US4424466A (en) 1979-10-02 1984-01-03 U.S. Philips Corporation Cathode ray tube with multipole correction ring
US5825123A (en) * 1996-03-28 1998-10-20 Retsky; Michael W. Method and apparatus for deflecting a charged particle stream
US6437500B1 (en) * 1999-08-27 2002-08-20 Sony Corporation Seamless electron transfer for multiple-gun direct view CRTS

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921025A (en) * 1974-07-05 1975-11-18 Tektronix Inc Dual-beam CRT with vertical trace bowing correction means
DE2529505A1 (de) * 1974-07-05 1976-01-29 Tektronix Inc Zweistrahlige kathodenstrahlroehre
US3983444A (en) * 1974-07-05 1976-09-28 Tektronix, Inc. Dual beam CRT with inner gun and outer gun shield means for correcting keystone distortion
US4424466A (en) 1979-10-02 1984-01-03 U.S. Philips Corporation Cathode ray tube with multipole correction ring
US4371808A (en) * 1979-12-07 1983-02-01 Iwatsu Electric Co., Ltd. One-gun two-beam cathode ray tube
US4335380A (en) * 1980-06-16 1982-06-15 Wright David Y Multi-beam raster scan display monitor
US5825123A (en) * 1996-03-28 1998-10-20 Retsky; Michael W. Method and apparatus for deflecting a charged particle stream
US6437500B1 (en) * 1999-08-27 2002-08-20 Sony Corporation Seamless electron transfer for multiple-gun direct view CRTS

Also Published As

Publication number Publication date
NL7401634A (enrdf_load_stackoverflow) 1974-08-14
FR2217795B3 (enrdf_load_stackoverflow) 1976-11-26
DE2406060A1 (de) 1974-08-15
FR2217795A1 (enrdf_load_stackoverflow) 1974-09-06
JPS5041468A (enrdf_load_stackoverflow) 1975-04-15

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