US2191590A - Television apparatus - Google Patents

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Publication number
US2191590A
US2191590A US109576A US10957636A US2191590A US 2191590 A US2191590 A US 2191590A US 109576 A US109576 A US 109576A US 10957636 A US10957636 A US 10957636A US 2191590 A US2191590 A US 2191590A
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Prior art keywords
cathode
multiplier
photo
electron
image analyzer
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Expired - Lifetime
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US109576A
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Schwartz Erich
Ruska Ernst
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FIRM FERNSEH AG
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FIRM FERNSEH AG
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/023Electrodes; Screens; Mounting, supporting, spacing or insulating thereof secondary-electron emitting electrode arrangements

Definitions

  • the present invention relates to an arrangement which permits combining an image analyzer with an electron multiplier.
  • Such a. combination is of importance since the image analyzer does not fulfill those exact accumulator requirements which it is theoretically supposed to fulfill, and since the subsequently necessary amplification of the image analyzer signals is preferably efiected in an amplifier of which the first stages are as free as possible from crackling tube noises which at most are equal to those of the image analyzer per se.
  • Such amplifiers, free f1om crackling tube noises are usually operated by means of electron multiplier arrangements.
  • a tube is attached to the image analyzer, which tube contains a photo-cathode of which the emission is controlled by the signal currents of the image analyzer.
  • photo-cathodes as is well known, have a smaller crackling tube noise effect than incandescent cathodes.
  • the electrons emanating from this photo-cathode are multiplied in an attached multiplying tube.
  • the photo-cathode which is energized by a constant light source may be of point-like type and may be delineated on a diaphragm by an electron lens, the said diaphragm forming the inlet opening for the multip ier, or it may be disposed directly in the vicinity of this inlet opening. Any radiation of desired wave length may be used for energizing the photo-cathode, 9. g. even Roentgen ray radiation.
  • Fig. 1 shows the combination of an image analyzer With a multiplier.
  • Fig. 2 illustrates a further embodiment of the multiplier.
  • Fig. 3 shows a tube which combines the image analyzer and the multiplier in one housing.
  • FIG. 1 A indicates an image analyzer of ordinary construction, B is the discharge tube of the invention, whereas C represents the electron multiplier which is combined With the discharle tube B to form a single vacuum tube.
  • the image analyzer comprises an anode I and a photo-electric mosaic 2 from which the displacement currents flow to signal plate 3 and thence across resistance 4 back to battery 5.
  • the voltage drop in resistance a is coupled to an ordinary amplifier tube, in accordance with the present invention the voltage drop is applied across resistanoe 4 to the Wehnelt cylinder l8 and the cathode 6 of the discharge tube B.
  • the cathode 5 is not, as customary, activated to produce thermionic electron emission, but is provided with a coating of caesium or other alkali earth metal.
  • the cathode is energized to the emitting point by means of a constant light source 8 which is projected by a lens 9 and mirror l0 onto cathode 6.
  • the mirror may be located in vacuo and fastened to one of the electrodes of the discharge tube B.
  • the electron lens which is here indicated as a magnetic collector coil l, delineates the cathode 6 on the anode diaphragm M. Behind the diaphragm l4 there is disposed an electron multiplier of known type. Such a multiplier is shown and described in detail in the Philo T. Farnsworth Patents Nos. 2,071,515 and 2,071,517, issued February 23, 1937.
  • the secondarily emissive cathodes are represented by the electrodes Il and l2 and the accelerating anode by the annular electrode I3.
  • the electrons which emanate from the photo-cathode are not gath ered by a. separate collectr coil and shot into the multiplier, but they issue through an opening 14 directly into the space between the electrodes H and [2.
  • the control is efiected by a grid I which is used in lieu of the Wehnelt cylinder [8 of Fig. 1.
  • the image analyzer is combined with the multiplier into one housng l6.
  • the optical image is thrown on the moSaic surface 2, to the metallic rear side 3 of which the cathode 8 is attached.
  • the resistance 4 may likewise'be disposed inside the tube between the cathode 3 and Wehnelt cylinder 18.
  • the electron ray produced by cathode 6 passes through diaphragm l4 into the multiplier, as shown in Fig. 1.
  • the entire tube may be disposed inside a common collecter coil ll adapted to produce an image of the cathode 6 and the cathode of the image analyzer in the ratio of 1:1.
  • means for energizing said multiplier from said dissectcr comprising a photo-enfissive cathode axially alined with said multiplier, means for constantly illuminating said cathode, a Wehnelt cylinder disposed about said cathode, an entry port to said multiplier in registry with said cathode, and means for energizing said Wehnelt cylinder from the output of said dissector.
  • means for utilizing the output of said dissector to control said multiplier comprising a photo-cathode disposed in said envelope in axial alinement with said multiplier cathodes, a beam aperture formed through one of said cathodes alined with said photo-cathode, means for directing a constant intensity light upon said said enVel0pe alined with said aperture, a control electrode disposed about said photoemisslve cathode, an external source et constant intensity light, means for focusing such light* upon said photo-cathode, means for focusing photoemssien from said photo-cathode upon said. multiplier cathode aperture, and means for leading a signal potential to said control electrode.
  • An evacuated cylindrlcal insulating envelope an image dissector disposed within one and of said envelope, an alternating current multiplier adapted to be energized by photoemissicn disposed within the opposite and there0f, an apertured entrance to said multiplier, a photo-cathode disposed between said dissector and multiplier in registry with said apertured entrance, an external source of constant intensity light, means for focusing light thereirom upon said photo-cathode, a control electrode about said photo-cathode, means for energlzng said controlelectrode from said dissector, and means for Iocusing emission from said photo-cathode upon said apertured multiplier entrance.
  • an electron multiplier a photo-cathode
  • means for continucusly energiz ing said photo-cathode to the point of emissicn of electrons means for guiding electrons from said photo-cathode to said electron multiplier, and means for modulating the flow of electrons to said electron multiplier in accordance with signals.

Description

Patented Feb. 27, 1940 PATENT OFFICE TLVISION APPARATUS Erch Schwartz and Ernst Ruska, Berlin-Zchlen- (1 1, Germany. ass g o s to the firm Fernseh Aktiengesellschafi, Germany Zelflenflorf, near Berlin,
Application November 6, 1936, Serial No. 109,576 In Germany November 9, 1935 Claims.
The present invention relates to an arrangement which permits combining an image analyzer with an electron multiplier. Such a. combination is of importance since the image analyzer does not fulfill those exact accumulator requirements which it is theoretically supposed to fulfill, and since the subsequently necessary amplification of the image analyzer signals is preferably efiected in an amplifier of which the first stages are as free as possible from crackling tube noises which at most are equal to those of the image analyzer per se. Such amplifiers, free f1om crackling tube noises, are usually operated by means of electron multiplier arrangements.
' The combination of image analyzer and multiplier is difficult to secure because the signal currents of the image analyzer fiowing as displacer ment currents in the conductor must again be converted into free electron currents in order to be able to engender the secondary emission eect in the electron multiplier. The conversion of galvanic conduction currents into currents of free electrons by means of electric glow discharges is not serviceable in this connection because the incandescent cathode required positively introduces a screen efiect. A further difliculty resides in the fact that the free electron currents which are set free by the signal currents of the image analyzer must be directed towards a small surface, the inlet point of the electron multiplier.
In accordance with the invention a tube is attached to the image analyzer, which tube contains a photo-cathode of which the emission is controlled by the signal currents of the image analyzer. Such photo-cathodes, as is well known, have a smaller crackling tube noise effect than incandescent cathodes. The electrons emanating from this photo-cathode are multiplied in an attached multiplying tube. The photo-cathode which is energized by a constant light source may be of point-like type and may be delineated on a diaphragm by an electron lens, the said diaphragm forming the inlet opening for the multip ier, or it may be disposed directly in the vicinity of this inlet opening. Any radiation of desired wave length may be used for energizing the photo-cathode, 9. g. even Roentgen ray radiation.
Embodiments of the invention are schematically illustrated in the drawing wherein:
Fig. 1 shows the combination of an image analyzer With a multiplier.
Fig. 2 illustrates a further embodiment of the multiplier.
Fig. 3 shows a tube which combines the image analyzer and the multiplier in one housing.
In Fig. 1, A indicates an image analyzer of ordinary construction, B is the discharge tube of the invention, whereas C represents the electron multiplier which is combined With the discharle tube B to form a single vacuum tube.
The image analyzer comprises an anode I and a photo-electric mosaic 2 from which the displacement currents flow to signal plate 3 and thence across resistance 4 back to battery 5. Whereas normally the voltage drop in resistance a is coupled to an ordinary amplifier tube, in accordance with the present invention the voltage drop is applied across resistanoe 4 to the Wehnelt cylinder l8 and the cathode 6 of the discharge tube B. The cathode 5 is not, as customary, activated to produce thermionic electron emission, but is provided with a coating of caesium or other alkali earth metal. The cathode is energized to the emitting point by means of a constant light source 8 which is projected by a lens 9 and mirror l0 onto cathode 6. The mirror may be located in vacuo and fastened to one of the electrodes of the discharge tube B. The electron lens, which is here indicated as a magnetic collector coil l, delineates the cathode 6 on the anode diaphragm M. Behind the diaphragm l4 there is disposed an electron multiplier of known type. Such a multiplier is shown and described in detail in the Philo T. Farnsworth Patents Nos. 2,071,515 and 2,071,517, issued February 23, 1937. In these patents there is shown a method of causing an electron cloud to oscillate back and forth between two secondarily emissive cathodes, producing an amplified stream at each impact on the cathodes, and being focused during successive passages by a magnetic focusing coil. After each impact. the electron cloud is accelerated toward the opposite cathode by a charge on a cylindrical accelerating anode placed midway of the cathodes. and the final velocity before each cathode impact suificient to produce secondaries is insured by an alternating potential built up on cathodes themselves through a resonant circuit connecting them, as described in detail in the patents referred to above. In the figures, the secondarily emissive cathodes are represented by the electrodes Il and l2 and the accelerating anode by the annular electrode I3. The photo-'- cathode 6, the saturation current of which is determined by the luminosity of the light source 8, emits an electron current which is modulated by the signal voltage at the Wehnelt cylinder I8.
This varies the number of primary electrons shot into the multiplier.
In accordance with Fig. 2 the electrons which emanate from the photo-cathode are not gath ered by a. separate collectr coil and shot into the multiplier, but they issue through an opening 14 directly into the space between the electrodes H and [2. The control is efiected by a grid I which is used in lieu of the Wehnelt cylinder [8 of Fig. 1.
In Fig. 3, the image analyzer is combined with the multiplier into one housng l6. The optical image is thrown on the moSaic surface 2, to the metallic rear side 3 of which the cathode 8 is attached. The resistance 4 may likewise'be disposed inside the tube between the cathode 3 and Wehnelt cylinder 18. The electron ray produced by cathode 6 passes through diaphragm l4 into the multiplier, as shown in Fig. 1. The entire tube may be disposed inside a common collecter coil ll adapted to produce an image of the cathode 6 and the cathode of the image analyzer in the ratio of 1:1.
We claim:
1. In combination with a dissector and an alternating current multiplier, means for energizing said multiplier from said dissectcr comprising a photo-enfissive cathode axially alined with said multiplier, means for constantly illuminating said cathode, a Wehnelt cylinder disposed about said cathode, an entry port to said multiplier in registry with said cathode, and means for energizing said Wehnelt cylinder from the output of said dissector.
2. In combination with a dissector and a multiplier having an envelope enclosng two opposed cathodes and a cylindrical anode intermediate thereof positioned symmetrically about the axis of said envelope, means for utilizing the output of said dissector to control said multiplier, comprising a photo-cathode disposed in said envelope in axial alinement with said multiplier cathodes, a beam aperture formed through one of said cathodes alined with said photo-cathode, means for directing a constant intensity light upon said said enVel0pe alined with said aperture, a control electrode disposed about said photoemisslve cathode, an external source et constant intensity light, means for focusing such light* upon said photo-cathode, means for focusing photoemssien from said photo-cathode upon said. multiplier cathode aperture, and means for leading a signal potential to said control electrode.
4. An evacuated cylindrlcal insulating envelope, an image dissector disposed within one and of said envelope, an alternating current multiplier adapted to be energized by photoemissicn disposed within the opposite and there0f, an apertured entrance to said multiplier, a photo-cathode disposed between said dissector and multiplier in registry with said apertured entrance, an external source of constant intensity light, means for focusing light thereirom upon said photo-cathode, a control electrode about said photo-cathode, means for energlzng said controlelectrode from said dissector, and means for Iocusing emission from said photo-cathode upon said apertured multiplier entrance.
5. In combination, an electron multiplier, a photo-cathode, means for continucusly energiz ing said photo-cathode to the point of emissicn of electrons, means for guiding electrons from said photo-cathode to said electron multiplier, and means for modulating the flow of electrons to said electron multiplier in accordance with signals.
ERNST RUSKA ERCH SCHWARTZ.
US109576A 1935-11-09 1936-11-06 Television apparatus Expired - Lifetime US2191590A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2440735A (en) * 1943-06-05 1948-05-04 Farnsworth Res Corp Electrooptical device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2440735A (en) * 1943-06-05 1948-05-04 Farnsworth Res Corp Electrooptical device

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FR813219A (en) 1937-05-28
GB484598A (en) 1938-05-09

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