US3287593A - Cold cathode electron discharge device - Google Patents

Cold cathode electron discharge device Download PDF

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US3287593A
US3287593A US158737A US15873761A US3287593A US 3287593 A US3287593 A US 3287593A US 158737 A US158737 A US 158737A US 15873761 A US15873761 A US 15873761A US 3287593 A US3287593 A US 3287593A
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envelope
gas
photo
window
cathode
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US158737A
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Charles Daniel
Veron Serge
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Thales SA
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CSF Compagnie Generale de Telegraphie sans Fil SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J63/00—Cathode-ray or electron-stream lamps
    • H01J63/08—Lamps with gas plasma excited by the ray or stream
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • 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
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/36—Photoelectric screens; Charge-storage screens
    • H01J29/38—Photoelectric screens; Charge-storage screens not using charge storage, e.g. photo-emissive screen, extended cathode
    • H01J29/385—Photocathodes comprising a layer which modified the wave length of impinging radiation
    • 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
    • H01J29/481—Electron guns using field-emission, photo-emission, or secondary-emission electron source
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0064—Tubes with cold main electrodes (including cold cathodes)

Definitions

  • the present invention relates to electron discharge devices, and more particularly to electron tubes with coldcathode structures.
  • Still a further object of the present invention resides in the provision of a cold-cathode structure which lends itself especially to pulsed operation.
  • FIGURE 1 is a cross sectional view through a cathode structure in accordance with the present invention.
  • FIGURE 2 is a cross sectional view through an electron tube incorporating the cathode structure in accordance with the present invention.
  • the cold-cathode structure for electron tubes is characterized in that it comprises a vacuum-tight envelope, provided with a transparent window and containing gas under low pressure, a transparent layer of photo-emissive substance deposited on said window on the outside of the envelope, and means to produce luminescent discharges on the inside of the envelope in such a manner as to excite the photo-electric emission of the said substance.
  • the cathode structure shown therein comprises a gas chamber 1 of which the vacuum-tight envelope is constituted by a metallic cylinder 2, closed by a wall or window of transparent glass 3 or analogous material and a piece 4 made of ceramic material or glass, traversed by a metal electrode in the form of a rod 5.
  • the chamber 1 encloses gas under slight pressure and its inner surface is covered by a fluorescent material 6.
  • a voltage source 9 may be connected between the electrode and the metallic wall 2 of the gas chamber 1 while an interrupter or switch 10 of any suitable construction permits opening and closing of the circuit.
  • the gas within the chamber 1 is continuously ionized and the gaseous discharges excite or produce an emission of light from the fluorescent material 6.
  • This light which traverses the window 3, in turn excites the photo-emissive substance 8 and produces an electron emission in the latter.
  • a fluorescent cover such as cover 6 along the internal walls of the gas chamber 1 is not always necessary, as the choice of the gas and of the additives determine whether the gaseous discharge is or is not sufliciently luminescent in itself to excite the photocathode 8.
  • a product having a very short emission duration in order that the photo-cathode may operate as a system with very short pulses which obviously implies emissions of light also by means of pulses of short duration. feet, to withdraw from the photo-cathode currents which are much larger than in continuous emission operation, because the gaseous discharge adapts itself very well to a pulsed operation, under the condition that the intervals between pulses are not smaller than the time of deionization of the gas.
  • FIGURE 2 illustrates very schematically, and only as an illustrative example of the application of the present invention, a cathode ray tube 11 utilizing, as cathode, a structure 1 in accordance with the present invention whereby identical reference numerals designate again the same elements in FIGURE 2tas in FIGURE 1.
  • the cathode structure 1 there are provided within the tube 11 the usual electrodes, such as the Wehnelt electrode 12, anodes 13, 14, 15, drflection plates 16, etc.
  • the photo-emissive layer 8 of the cathode 1 and the other electrodes receive their respective potentials from a voltage source 16, connected to the terminals of the voltage divider 17.
  • the potentiometer assembly 16, 17 provides also the voltage which serves to produce the gaseous discharge 5 within the chamber 1, that is, the direct-current voltage oetween the electrode 5 and the metallic wall of the envelope 1, this metallic wall 1 being connected to the photo cathode 8.
  • the source 16 including that determining the emission of the cold cathode.
  • the envelope of the tube 11 is evacuated as is usual but that of the cathode structure 1 contains a gas of any suitable known type as described hereinabove.
  • the power furnished to the photo-emissive cathodes is considerably smaller than that furnished to cathodes of the thermionic emission type.
  • the cold cathodes are capable to emit electrons by short pulses, which is totally impossible with hot cathodes by reason of the thermal inertia.
  • the output of a photo-emissive cathode according to the present invention may be readily modulated by applying the modulation signals to the discharge voltage of the gas.
  • the cathode and control grid of a tube may be simultaneously modulated by distinct modulating sources.
  • the photo cathode receives light reflected from reflective surfaces surrounding the cathode in any suitable manner.
  • the photo-emissive layer in that case, need not be transparent and its thickness might be substantially increased. The light which upon reflec- Such a system permits, in eftion is used to operate the cathode could thereby be produced in any suitable conventional manner.
  • a cold cathode structure comprising a gas-tight envelope including a metallic portion and a window transparent to light, said envelope being filled with a rarified gas, a photo-emissive coating on the outer surface of said window, an electrode disposed within said envelope, and means for establishing a difference of potential between said inner electrode and said metallic portion of the envelope, thereby to produce luminescent electric discharges in said gas.
  • a col-d cathode structure comprising a gas tight envelope including a metallic portion, a dielectric portion and a window transparent to light, said envelope being filledwith rarified gas, a photo-emissive coating on the outer surface of said window, an electrode disposed within said envelope and traversing said dielectric portion, and means for establishing a difference of potential between said electrode and said metallic portion of the envelope thereby to produce luminescent electric discharges in said gas.
  • a cold cathode structure comprising a gas tight envelope including a metallic portion, a dielectric portion and a window transparent to light, said enevelope being filled with a r-arified gas, a photo-emissive coating on the outer surface of said window, a transparent metallie layer interposed between said window and said photoemissive coating, an electrode disposed within said envelope and traversing said dielectric portion, and means for establishing a difference of potential between said electrode and said metallic portion of the envelope thereby to produce luminescent electric discharges in said gas.
  • a cold cathode structure comprising a gas tight envelope including a metallic portion, the inner surface of said envelope being coated with a fluorescent substance, a dielectric portion and a window transparent to light, said envelope being filled with a rarified gas, a photo-emissive coating on the outer surface of said window, a transparent metallic layer interposed between said Window and said photo-emissive coating,'an electrode disposed within said envelope and traversing said dielectric portion, and means for establishing a difference of potential between said electrode and said metallic portion of the envelope thereby to produce luminescent electric discharges in said gas.

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  • Vessels And Coating Films For Discharge Lamps (AREA)
  • Discharge Lamp (AREA)
  • Image-Pickup Tubes, Image-Amplification Tubes, And Storage Tubes (AREA)

Description

1966 D. CHARLES ETAL 3,287,593
COLD CATHODE ELECTRON DISCHARGE DEVICE Filed Dec. 12, 1961 ii ii 8 5 mvzmoas D- CHAR LE5 K S-VERON I ATTORN United States Patent Paris, France I Filed Dec. 12, 1961, Set. No. 158,737
Claims priority, application France, Dec. 21, 1960,
847,559 I 4 Claims. (Cl. 313-346) The present invention relates to electron discharge devices, and more particularly to electron tubes with coldcathode structures.
In particular, it is an object of the present invention to provide a novel, improved cathode structure for this type of tube which elfectively avoids the shortcomings and inconveniences of analogous prior art constructions by simple and relatively inexpensive means.
It is another object of the present invention to provide a cold cathode structure for electron tubes which requires less power for proper operation thereof than thermionicemissi-on type cathodes.
Still a further object of the present invention resides in the provision of a cold-cathode structure which lends itself especially to pulsed operation.
These and further objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one embodiment in accordance with the present invention, and wherein FIGURE 1 is a cross sectional view through a cathode structure in accordance with the present invention, and
FIGURE 2 is a cross sectional view through an electron tube incorporating the cathode structure in accordance with the present invention.
According to the present invention, the cold-cathode structure for electron tubes is characterized in that it comprises a vacuum-tight envelope, provided with a transparent window and containing gas under low pressure, a transparent layer of photo-emissive substance deposited on said window on the outside of the envelope, and means to produce luminescent discharges on the inside of the envelope in such a manner as to excite the photo-electric emission of the said substance.
Referring now to the drawing wherein like reference numerals are used throughout the two views to designate corresponding parts, and more particularly to FIGURE 1, the cathode structure shown therein comprises a gas chamber 1 of which the vacuum-tight envelope is constituted by a metallic cylinder 2, closed by a wall or window of transparent glass 3 or analogous material and a piece 4 made of ceramic material or glass, traversed by a metal electrode in the form of a rod 5.
The chamber 1 encloses gas under slight pressure and its inner surface is covered by a fluorescent material 6.
A conductive layer or film 7, which is relatively thin and transparent, covers the outer face of the window 3, and this conductive film 7 is, in its turn, covered by a semi-transparent layer of photo-emissive material 8.
Finally, a voltage source 9 may be connected between the electrode and the metallic wall 2 of the gas chamber 1 while an interrupter or switch 10 of any suitable construction permits opening and closing of the circuit.
In operation, when the voltage source 9 is operatively connected with the metallic member 2 and with the electrode 5 by closure of the switch 10, the gas within the chamber 1 is continuously ionized and the gaseous discharges excite or produce an emission of light from the fluorescent material 6. This light, which traverses the window 3, in turn excites the photo-emissive substance 8 and produces an electron emission in the latter.
It is to be noted that a fluorescent cover such as cover 6 along the internal walls of the gas chamber 1 is not always necessary, as the choice of the gas and of the additives determine whether the gaseous discharge is or is not sufliciently luminescent in itself to excite the photocathode 8.
In the case in which the use of a fluorescent material is necessary, there is preferably utilized a product having a very short emission duration in order that the photo-cathode may operate as a system with very short pulses which obviously implies emissions of light also by means of pulses of short duration. feet, to withdraw from the photo-cathode currents which are much larger than in continuous emission operation, because the gaseous discharge adapts itself very well to a pulsed operation, under the condition that the intervals between pulses are not smaller than the time of deionization of the gas.
FIGURE 2 illustrates very schematically, and only as an illustrative example of the application of the present invention, a cathode ray tube 11 utilizing, as cathode, a structure 1 in accordance with the present invention whereby identical reference numerals designate again the same elements in FIGURE 2tas in FIGURE 1.
In addition to the cathode structure 1, there are provided within the tube 11 the usual electrodes, such as the Wehnelt electrode 12, anodes 13, 14, 15, drflection plates 16, etc.
The photo-emissive layer 8 of the cathode 1 and the other electrodes receive their respective potentials from a voltage source 16, connected to the terminals of the voltage divider 17.
It may be seen from FIGURE 2 of the drawing that the potentiometer assembly 16, 17 provides also the voltage which serves to produce the gaseous discharge 5 within the chamber 1, that is, the direct-current voltage oetween the electrode 5 and the metallic wall of the envelope 1, this metallic wall 1 being connected to the photo cathode 8. Thus, all of the voltages are provided by the source 16, including that determining the emission of the cold cathode.
The envelope of the tube 11 is evacuated as is usual but that of the cathode structure 1 contains a gas of any suitable known type as described hereinabove.
The electron tubes equipped with cold cathodes in accordance with the present invention present the following advantages:
(1) The power furnished to the photo-emissive cathodes is considerably smaller than that furnished to cathodes of the thermionic emission type.
(2) The cold cathodes are capable to emit electrons by short pulses, which is totally impossible with hot cathodes by reason of the thermal inertia.
(3) The output of a photo-emissive cathode according to the present invention may be readily modulated by applying the modulation signals to the discharge voltage of the gas.
(4) The cathode and control grid of a tube may be simultaneously modulated by distinct modulating sources.
While we have shown and described one embodiment in accordance with the present invention, it is understood that the same is not limited thereto, but is susceptible of many changes and modifications within the spirit and scope thereof. For example, the present invention lends itself readily to various modifications in its actual construction and realization, different from that shown in FIGURE 1. Thus, in particular, a structure may also be utilized in which the photo cathode receives light reflected from reflective surfaces surrounding the cathode in any suitable manner. The photo-emissive layer, in that case, need not be transparent and its thickness might be substantially increased. The light which upon reflec- Such a system permits, in eftion is used to operate the cathode could thereby be produced in any suitable conventional manner.
Thus, it is obvious that the present invention is not limited to the details shown and described herein, but is susceptible of many changes and modifications within the spirit and scope thereof, and We therefore do not wish to be limited to the details shown and described herein, but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.
We claim:
1. A cold cathode structure comprising a gas-tight envelope including a metallic portion and a window transparent to light, said envelope being filled with a rarified gas, a photo-emissive coating on the outer surface of said window, an electrode disposed within said envelope, and means for establishing a difference of potential between said inner electrode and said metallic portion of the envelope, thereby to produce luminescent electric discharges in said gas.
2. A col-d cathode structure comprising a gas tight envelope including a metallic portion, a dielectric portion and a window transparent to light, said envelope being filledwith rarified gas, a photo-emissive coating on the outer surface of said window, an electrode disposed within said envelope and traversing said dielectric portion, and means for establishing a difference of potential between said electrode and said metallic portion of the envelope thereby to produce luminescent electric discharges in said gas.
. 3. A cold cathode structure comprising a gas tight envelope including a metallic portion, a dielectric portion and a window transparent to light, said enevelope being filled with a r-arified gas, a photo-emissive coating on the outer surface of said window, a transparent metallie layer interposed between said window and said photoemissive coating, an electrode disposed within said envelope and traversing said dielectric portion, and means for establishing a difference of potential between said electrode and said metallic portion of the envelope thereby to produce luminescent electric discharges in said gas.
4. A cold cathode structure comprising a gas tight envelope including a metallic portion, the inner surface of said envelope being coated with a fluorescent substance, a dielectric portion and a window transparent to light, said envelope being filled with a rarified gas, a photo-emissive coating on the outer surface of said window, a transparent metallic layer interposed between said Window and said photo-emissive coating,'an electrode disposed within said envelope and traversing said dielectric portion, and means for establishing a difference of potential between said electrode and said metallic portion of the envelope thereby to produce luminescent electric discharges in said gas.
References Cited by the Examiner UNITED STATES PATENTS Re. 23,802 3/1954 Sheldon 313-346 X 2,136,292 11/1938 Gabor 313--213 X 2,438,181 3/1948 Norehead et a1. 313--210 X 2,659,833 11/1953 Anderson 313-227 2,953,701 9/1960 Gale 313346 X FOREIGN PATENTS 274,441 6/ 1951 Switzerland.
JOHN W. HUCKERT, Primary Examiner.
DAVID J. GALVIN, Examiner.
I D. KALLAM, A. S. KATZ, D. E. PITCHENIK,
Assistant Examiners.

Claims (1)

1. A COLD CATHODE STRUCTURE COMPRISING A GAS-TIGHT ENVELOPE INCLUDING A METALLIC PORTION AND A WINDOW TRANSPARENT TO LIGHT, SAID ENVELOPE BEING FILLED WITH A RARIFIED GAS, A PHOTO-EMISSIVE COATING ON THE OUTER SURFACE OF SAID WINDOW, AN ELECTRODE DISPOSED WITHIN SAID ENVELOPE, AND MEANS FOR ESTABLISHING A DIFFERENCE OF POTENTIAL BETWEEN SAID INNER ELECTRODE AND SAID METALLIC PORTION OF THE ENVELOPE, THEREBY TO PRODUCE LUMINESCENT ELECTRIC DISCHARGES IN SAID GAS.
US158737A 1960-12-21 1961-12-12 Cold cathode electron discharge device Expired - Lifetime US3287593A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3421047A (en) * 1965-03-17 1969-01-07 Stromberg Carlson Corp Cathode-ray tube control circuitry
US4069438A (en) * 1974-10-03 1978-01-17 General Electric Company Photoemissive cathode and method of using comprising either cadmiumtelluride or cesium iodide
FR2494487A1 (en) * 1980-11-14 1982-05-21 Kreindel July Coaxial source for electron beam welding etc. - has cathode anode chamber cathode structure with central emission apertures

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2136292A (en) * 1935-04-29 1938-11-08 Gabor Denes Electric discharge device
US2438181A (en) * 1943-05-27 1948-03-23 Westinghouse Electric Corp Fluorescent and/or cathode glow lamp and method
CH274441A (en) * 1947-11-26 1951-03-31 Philips Nv Electrical discharge tube with a cathode which is provided with a supply of emitting compounds.
US2659833A (en) * 1949-11-09 1953-11-17 Hanovia Chemical & Mfg Co Ultraviolet vapor electric discharge device
USRE23802E (en) * 1948-11-05 1954-03-16 Photocathode
US2953701A (en) * 1957-09-05 1960-09-20 High Voltage Engineering Corp Sealed-off diode with electron emitting anode

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2136292A (en) * 1935-04-29 1938-11-08 Gabor Denes Electric discharge device
US2438181A (en) * 1943-05-27 1948-03-23 Westinghouse Electric Corp Fluorescent and/or cathode glow lamp and method
CH274441A (en) * 1947-11-26 1951-03-31 Philips Nv Electrical discharge tube with a cathode which is provided with a supply of emitting compounds.
USRE23802E (en) * 1948-11-05 1954-03-16 Photocathode
US2659833A (en) * 1949-11-09 1953-11-17 Hanovia Chemical & Mfg Co Ultraviolet vapor electric discharge device
US2953701A (en) * 1957-09-05 1960-09-20 High Voltage Engineering Corp Sealed-off diode with electron emitting anode

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3421047A (en) * 1965-03-17 1969-01-07 Stromberg Carlson Corp Cathode-ray tube control circuitry
US4069438A (en) * 1974-10-03 1978-01-17 General Electric Company Photoemissive cathode and method of using comprising either cadmiumtelluride or cesium iodide
FR2494487A1 (en) * 1980-11-14 1982-05-21 Kreindel July Coaxial source for electron beam welding etc. - has cathode anode chamber cathode structure with central emission apertures

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DE1197990B (en) 1965-08-05
GB931384A (en) 1963-07-17

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