US2266773A - Electron device - Google Patents

Electron device Download PDF

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Publication number
US2266773A
US2266773A US141910A US14191037A US2266773A US 2266773 A US2266773 A US 2266773A US 141910 A US141910 A US 141910A US 14191037 A US14191037 A US 14191037A US 2266773 A US2266773 A US 2266773A
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United States
Prior art keywords
electrodes
cathode
cross
over
electron
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Expired - Lifetime
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US141910A
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English (en)
Inventor
Russell R Law
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RCA Corp
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RCA Corp
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Publication date
Priority to BE428026D priority Critical patent/BE428026A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US141910A priority patent/US2266773A/en
Priority to FR837811D priority patent/FR837811A/fr
Priority to DER102301D priority patent/DE757643C/de
Application granted granted Critical
Publication of US2266773A publication Critical patent/US2266773A/en
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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
    • H01J29/48—Electron guns
    • H01J29/488—Schematic arrangements of the electrodes for beam forming; Place and form of the elecrodes
    • 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
    • H01J29/64—Magnetic lenses
    • H01J29/66—Magnetic lenses using electromagnetic means 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
    • H01J29/70—Arrangements for deflecting ray or beam
    • H01J29/72—Arrangements for deflecting ray or beam along one straight line or along two perpendicular straight lines
    • H01J29/76—Deflecting by magnetic fields only

Definitions

  • This invention relates to electronic devices and, in particular, to a cathode ray electron gun and focusing system for cathode ray projection tubes for use in television.
  • a cathode ray electron gun and focusing system for cathode ray projection tubes for use in television.
  • To reproduce a picture by television of adequate size it has been proposed to first produce a small primary image which is in turn projected onto a viewing screen of suitable size'by an appropriate optical system.
  • the primary image must be very bright to provide sufficient screen illumination and where the primary image is derived from the energy in an electron beam, a beam of high power is required.
  • cross-over is in accordance with the terminology used by those skilled in the art and defined on page 1399 of the above referred to article by Maloff and Epstein and locates the points on the axis of an 3 electron beam at which minimum areas of the beam takes place.
  • the spot size is dependent upon the control electrode potential, generally the modulation potential superimposed upon a xed potential, due to changes in the size of the first cross-over which is inherent in such designs.
  • the cross-over is inherently large due to the very pronounced eiects of initial velocity of the emitted electrons from the cathode which is present in the formation of a cross-over at low voltage.
  • the ⁇ first cross-over increases in size with increasing beam current, thereby producing the objectionable defocusing eifect known as blooming, in
  • one of the main objects of my invention is to provide a new and improved method and means for producing large images of electrooptically transmitted scenes.
  • An important object of my invention is t0 provide an improved cathode ray projection tube having a new and improved electron gun.
  • Another important object of my invention is to provide an electron gun which will give a high beam current in a small spot whose size is substantially independent of the beams modulation for use in cathode ray tubes.
  • Still another important object of my invention is to provide a cathode ray tube with a. much reduced spherical aberration by the use of magnetic lenses of special design.
  • Another object of my invention is to provide an electron gun with an improved first cross-over.
  • a further object of my invention is to provide an electron gun having a rst cross-over electrostatic lens for accurately focusing a large current from a large area cathode into a small crossover.
  • a still further object of my invention is to provide an electron gun and focusing system in which the full available second anode voltage is used for rst cross-over formation and in which, a small defining aperture ls located at the first crossover for fixing the size and locationof the rst cross-over.
  • Another object of my invention is to provide an improved way of mounting and aligning the cathode and the modulating and focusing electrodes and anodes.
  • Yet another object of my invention is a new method of modulating the beam intensity of a high beam current cathode ray tube.
  • Fig. 1 shows schematically in block diagram, a television reproducing system embodying my improved projection tube and method
  • Fig. 2 shows diagrammatically one form of my projection tube and focusing system
  • Figs.; ⁇ 6 and 7 show in detail two embodiments and aligning the elements of one form of my electron gun.
  • Fig. 1 a cathode ray tube I in register with an optical system 3, shown conventionally as a single .lens although a more complex system may be used, and a viewing screen 5, which may be ofeither the opaque or translucent type in accordance with viewing the projected image from the projection side or the rear side of the screen.
  • an optical system 3 shown conventionally as a single .lens although a more complex system may be used
  • a viewing screen 5 which may be ofeither the opaque or translucent type in accordance with viewing the projected image from the projection side or the rear side of the screen.
  • 'A high current beam of electrons 63 is formed by the electron gun comprising the cathode 25, the electrodes 21, 29, 3I and 33 and the anodes 35 and 31, and projected upon the luminescent screen 39.
  • the screen 39 Under-the impact of the focused beam of electrons light is emitted by the screen 39 which, in turn, is collected by the optical system 3 and focused upon the viewing screen.
  • the 'I'he electrodes 29, 3l and 33 are energized by the electrical energy source 9 and maintained at positive potential with respect to the cathode 25.
  • the rst and second anodes 35 and 31 are energized by the potential source I3.
  • the specially shaped magnetic focusing coil I9 is energized by the power supply II and shielded from the de iecting coils 2l and 23 by a magnetic shield 53.
  • the dei'lecting coils are energized by their respective deector circuits I and I1 for causing the beam to trace a path across the screen 39 in mutually perpendicular directions simultaneously and in synchronism with the transmitting scanning apparatus.
  • the intensity of beam current is modulated bythe video signals by the amplifier 1 which are simultaneously applied to both electrodes 29 and 3l through the coupling condensers 41 'and 49 respectively.
  • Direct coupling can also be used to provide background control or a separate background control tube can be connected to the resistors 43 and 45 at the junction of these resistors and the condensers 41 and 49, so that the potential of the electrodes 29 and 3l may be varied in accordance with the average integrated light intensity of the entire scene in a similar manner disclosed by the pending Kell application Serial No. 565,226 filed September 26, 1931.
  • deflecting and synchronizing circuits, video 'amplifier and power supplies may take the form shown in the complete television receiver shown in U. S. Patent No. 1,975,056, issued to W. L. Carlson on September 25, 1934, and are not described here in detail since any conventional television receiver may be used with my new and improved projection tube.
  • the electrodes 29, 3I and 33 are all energized with positive voltage in a predetermined increasing order by the source 9 as will be pointed out in more detail below.
  • resistors 43 and 45 respectively to maintain the proper bias on electrodes 29 and 3
  • the current density is seen to be greatest in the center and has the maximum values amperes per cm?.
  • the maximum current density is seen'to be only 0.32 In amperes/cm, and
  • the forming system should be as high as possible must recall that the electrons issuing from the first cross-over are to be reimaged on the .distant screen by a final focusing lens.
  • the usable vaperture of the final focusing lens is limited by'v lts aberrations.
  • the spread :ify the beam emerging from the first cross-over must be kept within the limitsv imposed by the available aperture ofthe final focusing. lens. f
  • SecondVthe available voltage may be apportioned to the two functions of first-cross-over formation and final' focusingin any desired manner. vThat is, we may use only a-part of the available voltage for first-cross-over formation, reserving the remainder forffinal focusing; or,
  • ythe entire available potential may be used for lirst-cross-overy formation and final yfocusing may be accomplished by ya'magnetic lens or an f.
  • electrostatic lens of the retarding-electrode type
  • first cross- Jver if formed at some voltage E1 which is a frac- ;ional part of the total voltage E2, final imaging 'nay give a demagnication due to the differing .ndices of refraction in the object and image ;paces. Because of this demagniiication, We ;hould be willing to accept a larger first cross- )ver at low voltage. This characteristic may be feadily analyzed if we neglect the shift in posizion of the equivalent thin lens and consider the magnification to be Image distance EE m Object distance E2 exceeded, it is desirable to use all available voltage for first cross-over formation.
  • This electron gun uses full available voltage for first cross-over formation and has a firstcross-over-dening aperture located at the first cross-over.
  • This first-cross-over-defining aperture serves to fix the size of the electron object imaged on the screen by the final focusing lens.
  • the relative voltages applied to the intermediate electrodes 85, 8l, and 89 determine the potential distribution in the rst-cross-over-forming system. Modulation of the beam current is accomplished by varying the potentials on electrodes and 81. Inasmuch as full second-anode voltage is used for first-cross-over formation, the final focusing-lens object and image space have the same index of refraction and the nal spot size is given by Final spot size:
  • First cross-over-defning aperture size (Image-distance) (Object distance)
  • Image-distance The minimum image distance is fixed by the available defiecting power.
  • the maximum object distance is determined by the available aperture of the final focusing lens and the spread of the beam. It is, therefore, desirable to keep the spread of the beam low. It has been pointed out already that the spread of the beam emerging from the rst-cross-over increases with cathode diameter. Consequently, the cathode should be as small as is consistent with the total desired space current at a practical emission density.
  • the minimum permissible cathode diameter is about l mm.
  • the spherical indentation on the cathode improves the performance of the 'rst-cross-over forming system.
  • Such a curved surface, limitedarea cathode also possessesl advantages in assembly in that a suitable spacer may be interposed between the cathode and the first control grid element for accurately positioning the cathode without contaminating the active emitting surface.
  • iinal focusing may be accomplished by either magnetic or retarding type electrostatic lenses
  • the electron gun illustrated in Fig. 2 Uses a magnetic lens. This choice was based on experimental study which showed that larger aberration-free apertures could be obtained with magnetic lenses than with conventional concentric-cylinder electrostatic lenses.
  • the magnetic ,final-focusing lens illustrated in Fig. 2 is wound vfon a spool of special shape in order to provide a 'more advantageous flux distribution.
  • the shape is such to provide an annular magnetic coil whose inside diameter varies parabolically with the vortex of the parabola toward the axis of the tube.
  • This new and unconventional design of a magnetic focusing lens has made it possible to obtain very small spherical aberration even with relatively large beam diameter.
  • An iron-end plate 53 serves to shield the magnetic lens from the deflecting coils and to prevent interaction between the focusing and deecting fields.
  • the eiective object distance should not ex# ceed 60 mm. since the minimum image distance must be about 160 mm. to give adequate deection sensitivity, the first-cross-over-dening aperture must be about 0.1 mm. in diameter to give a 0.25 mm. spot on the screen.
  • the choice of this final-spot size is based on a consideration of the picture size and number of scanning lines. The picture size is, in turn, iniluenced by the optical system used for projection.
  • is supported from the Wehnelt cylinder 33 by three nichrome uprights 97 spaced 120 around the axis of the cathode 8
  • the indirectly heated cathode has a spherical depression which is coated with electron emitting material.
  • In register and in spaced relation to the cathode are four accelerating electrodes 85, 81, 89 and 9
  • Each of the electrodes is apertured and the aperture size decreases continually from electrode to electrode with electrode 9
  • is in the form of an annular cylinder closed at .the end nearest the cathode.
  • may contact to the coating 31 of the tube I, as shown in Fig. 1.
  • the coating of the bulb which serves as a second anode is a conducting layer and may be, for example, aquadag or a thin layer of silver, or a thin layer of silver which is coated with aquadag, to reduce internal illumination and stray light.
  • the electrodes are held rigidly in alignment and coaxial with one another by the heavy studs IDI,
  • Fig. 6 is a cross-section, only one of the three beads and series of studs being shown. The other two beads and series of studs are spaced around the periphery of the electrodes at an angle of degrees with each other. In one such gun the apertures had the following sizes and voltages applied:
  • my electron gun structure has a rigid unitary assembly supported from the glass press
  • a projection tube constructed as I have described may be subjected to heavy mechanical shock without in any way aiecting the alignment of the elements with respect to one another or with respect to the iluorescent screen within the tube.
  • 3 is positioned right at the cross-over point in accordance with the theory which I have outlined above.
  • FIG. 7 An alternative form of electron gun is shown in Fig. 7 in which, however, an additional electrode is provided.
  • the apertures are no longer uniformly reduced in size as the order of the aperture position is increased from the cathode.
  • the rst-cross-over-defining aperture is of the same size as that shown in Fig. 6.
  • the spacing between the electrodes is no longer uniform and the combination of the nonuniform spacing and change in voltage distribution produces the same potential proportional factor so that the cross-over area is substantially the same as that for the system shown in Fig. 6.
  • One such form of gun shown in Fig. 'l had the following aperture sizes, spacing distances and potentials:
  • Electrodes diameter frgclfilige' Voltage in mches aperture Inche The electrode
  • a V-block has a slot 2
  • trodes 203 and spacers 205 are alternately stacked and maintained adjacent to each other on a spacer support rod 2
  • the stacked spacers and electrodes are then laid in the V 2
  • the faces of the end blocks engaging the stacked elements have centrally located holes so that the spacer rod 2
  • 5 has a copper face 2
  • the electrodes 203 may have the short stud members 22
  • Suitable means may be provided for holding a C clamp to leave the ends of the separators to manipulate the beads and the gas flame.
  • the electrodes and end blocks absorb considerable heat from the flame used to make molten the glass and to heat the studs 22
  • the use of the copper disk to take up the expansion has the further advantage of preventing excessive pressures .building up between the electrodes and the insulating spacers, and thus, avoids crushing of the spacers, which, if not prevented, would result in misalignment of the electrodes.
  • the non-linear modulation characteristic of the beam tends to compensate for the non-linear conversion characteristic of the screen which has generally a curvature of opposite sign to that of the modulation characteristic.
  • ⁇ the overall effect is one calculated to reproduce the transmitted image with identical density values of the original image.
  • a cathode ray tube comprising an envelope, a cathode, a shield electrode concentric with and surrounding said cathode, and displaced longitudinally from said cathode and said shield and in the order named, a plurality of apertured disk electrodes of uniform diameter with decreasing effective apertures in register with said cathode, each of said disk electrodes being adapted to be maintained at positive potential, an anode supported from the wall of the envelope, and a iluorescent screen supported by the envelope normal to the axis of the cathode.
  • a cathode ray tube comprising an envelope, a cathode, a shield electrode concentric with and what I surrounding and supporting said cathode, and displaced longitudinally from said cathode and said shield and in the order named, a plurality of modulating disk electrodes adjacent to and in register with said cathode, a plurality of focusing disk electrodes in register with said modulating electrodes, said focusing electrodes having decreasing eiiective apertures, an anode supported on the wall of the envelope, and a fluorescent screen supported by the envelope normal to the axis of the cathode.
  • a cathode structure for electron devices comprising an apertured cup-shaped electrode, a plurality of supporting members equi-spaced within the cup-member and ailixed to the planar wall of the cup, a metallic cylinder positioned coaxial with the cup-member and projecting through the aperture, and a plurality of support members engaging the metallic cylinder and each of the supporting members.
  • a cathode structure for electron devices comprising an aperture'd cup-shaped electrode, a plurality of supporting members equi-spaced within the cup-member and amxed to the planar emissive material deposited in the recess of the metallic cylinder.
  • An electrode structure for a cathode ray tube comprising a cylindrical electrode planarly closed at one end, said end being'apertured, a cathode supported from within -the cylindrical electrode and projecting through the aperture, a plurality of apertured disk electrodes in register with the cathode, an apertured cup-shaped electrode in register with the cathode and the apertured disk electrodes, stud members afiixed to each of the electrodes, and supporting means engaging the studs and holding the electrodes in predetermined spaced relation.
  • the method of-assembling disk electrodes wherein spacers are used which comprises the steps of alternating stacking spacers and the electrodes, lightly compressing the stacked spacers and electrodes, aligning the spacers and electrodes between guides, compressing under great pres-- sure the aligned electrodes and spacers, aiixing radial support arms to each of the electrodes, said radial arms being equally spaced around the periphery of the electrodes, molding a vitreous body about the radial arms to maintain the electrodes'in predetermined spaced relationship, to-
  • the method of reducing spherical aberration in electron optical systems which comprises the steps of producing electrons from a source. directing the electrons through progressively increasing accelerating elds to produce cross-over,
  • the method of reducing spherical aberration in electron optical systems which comprises the steps of producing electrons from a source, directing the electrons through progressively increasing accelerating fields to produce cross-over, terminating the acceleration at the point of crossover, directing the electrons passing the cross- .over point toward a fluorescent screen, producing intermediate the cross-over point and the uorescent screen an electromagnetic iield Whose intensity varies parabolically as a function of the distance between the cross-over point and the lscreen, producing two mutually perpendicular deiiecting elds for moving the electrons directed toward the fluorescent screen over predetermined scanned areas, and electromagnetically shielding fields from the produced deecting iields.
  • An electrode structure for a cathode ray tube comprising a cylindrical electrode planarly closed at one end, said end being apertured, a cathode supported from within the cylindrical electrode and projecting through the aperture, a plurality of apertured disk electrodes in register with the cathode, said disk electrodes being equispac'ed from each other and having progressively decreasing apertures, an. apertured cup-shaped electrode in register with the cathode and the apertured disk electrodes, stud members aixed to each of the electrodes, and supporting means engaging the studs and holding the electrodes in predetermined spaced relation.
  • An electrode structure for a cathode ray tube comprising a cylindrical electrodeplanarly closed at one end, said end being apertured, a cathode supported from within the cylindrical electrode and projecting through the aperture, a plurality of apertured disk electrodes in register with the cathode, said disk electrodes having equal apertures of the same size and being spaced from each other with progressively increasing distances, an apertured cup-shaped electrode in register with the cathode and the apertured disk electrodes, stud members aflixed to each of the electrodes, and supporting means engaging the studs and holding the electrodes in predeterminedv spaced relation.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Video Image Reproduction Devices For Color Tv Systems (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
US141910A 1937-05-11 1937-05-11 Electron device Expired - Lifetime US2266773A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
BE428026D BE428026A (enrdf_load_stackoverflow) 1937-05-11
US141910A US2266773A (en) 1937-05-11 1937-05-11 Electron device
FR837811D FR837811A (fr) 1937-05-11 1938-05-11 Perfectionnements aux dispositifs électroniques
DER102301D DE757643C (de) 1937-05-11 1938-05-12 Elektromagnetische Elektronenlinse fuer Kathodenstrahlroehren

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Application Number Priority Date Filing Date Title
US141910A US2266773A (en) 1937-05-11 1937-05-11 Electron device

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US2266773A true US2266773A (en) 1941-12-23

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US141910A Expired - Lifetime US2266773A (en) 1937-05-11 1937-05-11 Electron device

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US (1) US2266773A (enrdf_load_stackoverflow)
BE (1) BE428026A (enrdf_load_stackoverflow)
DE (1) DE757643C (enrdf_load_stackoverflow)
FR (1) FR837811A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2483457A (en) * 1945-04-05 1949-10-04 Du Mont Allen B Lab Inc Cathode-ray tube
US2880338A (en) * 1953-10-17 1959-03-31 Pye Ltd Television pick-up tube
US2888606A (en) * 1956-08-27 1959-05-26 Rca Corp Modulation control for cathode ray tubes
US2901665A (en) * 1956-02-13 1959-08-25 Rca Corp Cathode ray tube deflection yoke
US3374387A (en) * 1966-11-18 1968-03-19 Air Force Usa Coaxial line terminating in cathode and control grid of cathode ray tube
US3564320A (en) * 1969-09-29 1971-02-16 Kentucky Electronics Inc Electrode mounting structure for cathode ray tubes

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4724359A (en) * 1986-10-17 1988-02-09 General Electric Company Laminar flow guns for light valves

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1470696A (en) * 1917-12-07 1923-10-16 Western Electric Co Television
US1979392A (en) * 1931-05-04 1934-11-06 Siemens Ag Cathode ray tube
DE585599C (de) * 1931-06-23 1933-10-09 Telefunken Gmbh Einrichtung zur Intensitaetssteuerung von fuer Fernsehen, Tonfilm, Bildtelegraphie o. dgl. verwendeten Kathodenstrahlroehren
DE715021C (de) * 1933-02-06 1941-12-17 Telefunken Gmbh Elektrische Elektronensammellinse fuer Hochvakuumelektronenstrahlroehren
FR769327A (fr) * 1934-02-26 1934-08-23 Robert Lyon & A T Stoyanowsky Perfectionnements aux appareils de télévision et similaires

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2483457A (en) * 1945-04-05 1949-10-04 Du Mont Allen B Lab Inc Cathode-ray tube
US2880338A (en) * 1953-10-17 1959-03-31 Pye Ltd Television pick-up tube
US2901665A (en) * 1956-02-13 1959-08-25 Rca Corp Cathode ray tube deflection yoke
US2888606A (en) * 1956-08-27 1959-05-26 Rca Corp Modulation control for cathode ray tubes
US3374387A (en) * 1966-11-18 1968-03-19 Air Force Usa Coaxial line terminating in cathode and control grid of cathode ray tube
US3564320A (en) * 1969-09-29 1971-02-16 Kentucky Electronics Inc Electrode mounting structure for cathode ray tubes

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Publication number Publication date
BE428026A (enrdf_load_stackoverflow)
DE757643C (de) 1953-02-16
FR837811A (fr) 1939-02-21

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