US2576093A - Cathode-ray tube circuit - Google Patents

Description

Nov. 27, 1951 M. ARDITI cATHoDE-RAY TUBE CIRCUIT Filed Aug. l0, 1946 .llllll .NGN Q w 39.99

N wmw Patented Nov. 27, 1951 CATHODE-RAY TUBE CIRCUIT Maurice Arditi, New York, N. Y., assignor by mesne assignments, to International Standard Electric Corporation, New York, N. Y., a corporation of Delaware Application August 10, 1946, Serial No. 689,795

This invention relates to cathode ray tube sys tems, particularly of the type in which the electron beam moves past one or more target elements.

Cathode ray tube arrangements of the type to 5 which this invention relates are used for many purposes, such as for example, pulse amplifiers, switching systems, electronic distributors, electronic mixers, modulators and demodulators for time-modulated pulse systems, etc. In such arrangements, accuracy in functioning is generally highly important. For this purpose, a relatively low current density beam is preferred since it can be readily controlled with particular reference tosharpness of outline and deflection. On the other hand, where such a relatively low beam is utilized, the output is generally inadequate.

An object of the present invention is the pro- Vision of an improved cathode ray tube system of the type in which a beam is swept across one or more target elements.

Another object is theprovision of a cathode ray tube system utilizing a relatively low density beam while providing a relatively high input.

According to a feature of the present invention, a relatively low density beam is swept over a target element. When the beam strikes the target element, which may be a secondary emission electrode, the Voltage thus developed is fed back to some element controlling the electron current drawn from the cathode, as for example, the grid. This Voltage is applied in such a direction as to cause a relatively large rise in this current. The large increase of current from the cathode causes a defocussing of the beam with the defocussed electrons impinging upon one of the electrodes nearer the cathode than the target element, which may be either said grid or some other element of the electron optical system such as a focussing cylinder. The current is taken off from said last-mentioned electrode and the voltage derived therefrom serves as the output voltage. In one given example, the current thus taken on was equal to about a hundred times the current in the beam.

Other and further objects of the present invention will become apparent and the invention will be better understood from the following description of embodiments thereof, reference being had to the drawings, in which:

Fig. l is a schematic and block diagram of a pulse amplifier embodying my invention; and

"traverses a path such that it will pass across 11 Claims. (Cl. 315-12) Referring now to the system of Fig. 1, a cathode ray tube l includes an envelope 2 within which are arranged a cathode 3 and a control element, which may be for example, a grid 4, controlling the value of current `drawn from said cathode. For the purpose of forming a beam, Various forms of electron optical systems may be employed which may include for example, a first anode 5. When the beam is focussed very little,

if any, current flows to the anode 5, most of the current being ccnned to the beam which passes through anode 5. A second anode 6 is employed having an aperture 1 therein, through which the beam may pass to strike a target element in the form of a secondary emission electrode 8. The beam is moved laterally by any suitable means such as for example, a set of deflection plates 9, which are normally biased by means of a battery I0 so that the beam will not pass through the aperture 1. For ease of control, the beam is preferably of relatively light current density.

The pulses which are to be amplified, may be supplied by a source Il, and are applied in opposition to the bias of battery Ii) to deflection plates 9 to deflect the beam so that it ""network, generally designated by the numeral l2,

to the control element'or grid 4, altering the bias applied to said element by any suitable biasing means such as a battery I3, to substantially increase the current drawn from the cathode.

rThis is a cumulative effect which rapidly rises Fig. 2 is a schematic and block Ydiagram of a modulator. for aY multi-channel time-modulated pulse system,l embodying my invention.

to a point of equilibrium. As a result the beam is thereby spread or defocussed near the grid, causing most of the defocussed electrons to be xdrawn to the first anode 5, as represented in Fig.

This produces a relatively large current flow through the resistor lll in series with the first anode 5, and this large current, or the voltage produced thereby across resistor It, is used as output. In one system similar to the one herein described, the current in the focussed beam was 10() microamperes whereas said increased current drawn by the first anode was approximately 10 milliamperes, being an increase of a hundred times the current density of the focused beam. 'The input pulses from source ll produces output pulses in the output of the system which are considerably amplified.

Referring now to Fig. 2, the system there illustrated is a `modulator and mixer for multichannel time modulated pulse systems. This system includes a cathode ray tube I5 having electron beam-producing elements which may consist for example, of a cathode I 6, grid I'I, first focussing anode I8, deflection plates I9 for producing deflections along an X and Y axis (in rectangular coordinates). Grid I'IV may be suitably biased by a battery 3d provided with a by-pass condenser 35 for high frequency energy to pass by the battery. The sweep movement chosen forA the purpose of illustrating the presenty invention is circular and the deflecting Waves for producing this sweep movement are Vobtainedy from an oscillator 25J and phaser 2I. The controlwaves obtained from phaser 2I are two sine Waves separated in phase by 90.

A commutator plate 22 having# a series of' apertures 23 arranged in a circular manner, divides the beam during its sweep movement into segments. rIhe apertures for the signal channels are preferably shaped in the form of sectors, the sides thereof being defined by the radii of the plate 22.

To, yeffect signal deflection of the beam segments, a circular electrode 24 is provided with a series of small electrodes 25 disposed in equispaced relation about the edge of the electrode 24. The electrodes 25' are arranged so that a correspcndingbeam segment passing through one of the apertures 23 passes between a correspond.- ing one of said electrodes 25 and the circular electrode 25. The signal'is applied to diferent ones. of the small electrodes 25 from diierent input channels 26. The input signal is preferablysteppedup by step-uptransformers 2l before application to the electrodes.

The target system with which the electrons Y ciV the beam cooperate to produce energy flow comprises a modulator plate 28y and a secondary electron emission ring 29. The potential of the modulator plate 28 is higher than the ring 29 so that when theelectrons impinge upon the ring 29, the ring emits secondary electrons which flow to the modulator plate 28. The modulator plate 28 is provided with narrow slots 35, one for each channel, for passage of the beam for impingement upon ring 29. The central portion of the. slots for the signal channels are preferably disposed at an acute angle with respect to the direction of signal deflection produced by the potential diierences between the small plates 25 and circular electrode 213. The end portions of the slots, however, are disposed parallel to the direction of signal deflection.

In the absence of signal modulation, the beam passes through the center of the central portion of the slots When, however, a signal is applied to1 the small electrodes 25 in the suitable channels, these deect the beam so that it passes through other portions of the slots, thereb-y varying the time at which said beam passes through said slots, and thus the pulse produced by said beam passing through the slot is modulated in time. For further details of the system thus. far described, reference may be had to the copending application of Labin-D. D. Grieg, Sil-93, Serial No. 567,414, filed December 9, 1944, for Signal Transmitting System, now U. S. Patent No. 2,495,738 issued January 3l, 1950.

In accordance with a feature of the present invention, whenever the beam passes through the slots 38 to strike the ring 2d, the resultant pulses are fed back through a circuit arrangement 3I to the control element of grid I1 to produce thereby an increase of thecurrent-drawn from cathode I6. This increased current .causes a spreading or defocussing of the beam near the cathode with the increased current impinging upon the rst anode I8. The current flowing through the iirst anode I8 is fed across an output resistor 32 to the output 33. The portion of the beam: still passing through the rst cylindrical anode` I8 is then deflected by the deflecting electrodes so as to move past the slot, thereby terminating the pulse fed back to the control element of grid I1. Thus, in the distributor a relatively low intensity beam may be used reducing the danger ofv cross talk, but highly amplined output pulses'V may be obtained.

Numerous other modications will occur to those versed-'in the art from the teachings hereof. Accordingly, while I have described above the principles of my invention in connection with specic apparatus, and particular modications thereof, it is to be clearly understood that this: descriptiony isv made only by Way of example andfnot as a limitation on the scope ofmy invention..

I claim:

l. A cathode ray tube. system comprising a cathode for emitting. electrons, control means for determining the electron current drawn from said. cathode, means for. focussing said. electrons to produce anelectronbeam, means for moving vthe beamv over a given path, a target element mounted in said path, meansconnected tov said target element responsive to the impinging of the Y increase said current, and an electrode adjacent to the path of the-electron beam for drawing said increased current, said increased current beine` K the output fromv said system.

2. A cathode rayv tubesystem according to claim 1 wherein the increasing of said current defocusses thebeam, and said electrode is mounted with its physical. structure adjacent the path Y of the focussedvbeam, and is. adapted to be impingedupon by the defocussed beam.

31 A cathode ray tube system, according to claim l', wherein said electrode is mounted adjacentv the cathode..

4;. A cathode ray tube system according to claim i wherein said electrode is mounted closer tothe cathode than said target element.

5; VIn a cathode'ray tube system, means for producing a relatively sharp electron beam, means for 'moving'said beam, means responsive to movement of said beam for producing an electrical pulse, an output electrode4 normally having its physicalstructure adjacent the path of movement of said beam, and-control electrode means in the path ofY said electron beam responsive to saidelectrical pulse for ldecreasing the sharpness of' saidv beam whereby it will impinge upon said outputA electrode.

6. Ina cathode-ray distributor system, meansfor producing a cathode ray beam, means for moving' saidbeam over a given path, a plurality oitarget elements mounted in said path responsivev to impingementof the beam thereon to produce-electricalvpulses, a control electrode in the path of said electron*l beam, a second electrodeA to increase` the? current" in saidV beamwherebyV said beam will; impinge uponsaid V .secondelecv trode, and an output circuit coupled to said second electrode.

7. A cathode ray distributor system according to claim 6 further comprising individual signal channel means operatively associated with each of said target elements, whereby the pulses in said out circuit will vary in accordance with sig'- nals in said channels.

8. A pulse amplifying system comprising a cathode ray tube having a cathode for emitting electrons, control means for determining the electric current drawn from said cathode, means for focussing said electrons to produce an electron beam, means responsive to an input pulse for moving the beam over a given path, a target element mounted in said path, and an electrode mounted to draw substantially negligible current from said beam; means connected to said moving means for applying an input pulse from an external source to said moving means to cause said beam to move over said path and during the course of this movement impinge on the target element; and means connected to the target element responsive to the impinging of the beam on the target element for producing a voltage, a circuit connected to the -said last mentioned means for applying said voltage to said control means for conditioning said control means to increase the current, said increased current being drawn by said electrode and serving as output.

9. A pulse amplifying system according to claim l8 wherein said increased current causes said -beam to spread adjacent the cathode, said electrode being mounted adjacent the path of the electron beam, to receive electrons from the spread portion of said beam.

10. In a multi-channel pulse modulator, means for producing a beam of electrons including a cathode for emitting electrons and control means for determining the electron current drawn from said cathode, means to cause the beam to have a given sweep movementl a plurality of signal channel input circuits, means associated with said input circuits to control deflection of the beam successively during its sweep movement according to increments of the input signals of said circuits, a target element mounted in the path of the deflected beam, beam responsive means connected to the said target element to produce pulses of energy time modulated according to the corresponding signal deection of said beam, means connected to said last mentioned means responsive to each of said pulses for producing a voltage, a circuit connected to said responsive means for producing a voltage for applying said voltage to said control means and conditioning said control means to increase said electron current, and an electrode mounted adjacent to the said electron beam for drawing said increased current, the current drawn by said electrode serving as output for the modulator.

11. A multi-channel pulse modulator according to claim 10 wherein said increased current causes the beam to spread adjacent the cathode, and said electrode has its physical structure surrounding the path of the electron vbeam for receiving said spread portion of said beam.

MAURICE ARDITI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,358,902 Ziebolz Sept. 26, 1944 2,361,766 Hadekel Oct. 31, 1944 2,418,133 Miller et al. Apr. 1, 1947 2,462,896 Ransom Mar. l, 1949 2,468,085 Labin Apr. 26, 1949 2,516,886 Labin Aug. 1, 1950

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