US2704328A - Electron-beam tube oscillator - Google Patents

Description

March 15, 1955 H. J. WOLKSTEIN 2,704,328

ELECTRON-BEAM TUBE OSCILLATOR Filed-Nov. :s, 1950 2 Shets-Sheet 1 (I) BEAM Cur OFF Zhwentor HERBERT J WOLKSTE/N Gttorneg March 15, 1955 H. J. WOLKSTEIN ELECTRON-BEAM TUBE OSCILLATOR Filed Nov. 3, 1950 2 Sheets-Sheet 2 hwwii a i fis/ezfler d WdL/(SFE/N 5 Gttorneg nitd States Patent ELEoTRoN-BEAM TUBE OSCILLATOR Herbert J. Wolkstein, Newark, N. 1., assignor to National Union Radio Corporation, Orange, N. .I., a corporation of Delaware Application November 3, 1950, Serial No. 194,765

9 Claims. (Cl. 250-36) This invention relates to electronic tube apparatus, and more particularly to electron tubes for effecting counting or storing of electrical pulses.

A principal object of the invention relates to a cathoderay tube having a novel electrode array whereby the cathode-ray beam can be used under one condition to trigger a target element up to a beam holding potential, and in another condition the same beam can be used to discharge the said target element, and then the beam automatically pie-positions itself in alignment with a succeeding target element.

Another object is to provide a cathode-ray tube with a novel arrangement of electrodes whereby the beam can he stepped around a cylindrical array of targets and discharge electrodes under control of beam intensity modulating pulses which are used to key the beam on and off.

A feature of the invention relates to an electronic tube for pulse counting, comprising an electron gun for developing a beam of electrons, a plurality of sets of counting control elements each set including a beam deflector, a target electrode and an intervening target discharging electrode, and with all the sets disposed in substantially cylindrical array around the normal or axial trajectory of the beam.

Another feature of the invention relates to a counting tube of the cathode-ray type, wherein the beam-deflecting, beam-stepping, and the holding elements are all mounted around the normal or undeflected axial trajectory of the beam. As a result of this construction, the tube can be made smaller and more compact than conventional counting tubes, and does not require precise gun and target alignment.

Another feature relates to a novel construction of pulse generator of the cathode-ray beam type.

Other features and advantages not particularly enumerated, will become apparent after a consideration of the following detailed description and the appended claims.

In the drawing, which represents by way of example a preferred embodiment,

Fig. 1 is a schematic single-plane diagrammatic view of the more important elements of a cathode-ray tube embodying the features of the invention.

Fig. 2 is a view of a complete tube, in perspective, and associated circuits according to the invention.

Fig. 3 is a longitudinal sectional view of the tube of Fig. 2.

Fig. 4 is a schematic block diagram of a counting circuit that may be controlled by the system of Fig. 2.

Various kinds of counting tubes have been designed heretofore, employing a cathode-ray beam. In one kind of tube, the counting targets are arranged in a linear row or rows and reliance is placed upon the variable amplitude of the beam-deflecting pulses to cause the beam to step to successively spaced targets. In general, in that type of tube, the stepping pulses are applied to the beam deflector plates, and their relative magnitudes control the angular deviation of the beam from its normal position. In another kind of tube, the targets are arranged in a circle, and the combined variable energization of coordinate deflector plates causes the beam to step around the targets. In both these prior types of tubes it is necessary to design and construct the tube with the utmost precision of orientation between the targets and the normal trajectory of the beam from the electron gun. In accordance with the present invention,

trodes 12A, 128,

2,704,328 Patented Mar. 15, 1955 there are located between the targets and deflector plates at corresponding set of target discharge electrodes which become effective immediately upon the receipt of a pulse to be counted, to discharge a previously-energized target; and simultaneously raising the potential on the corresponding deflector plate whereby the beam automatically pre-positions itself in alignment with the next target and is held until the receipt of a succeeding pulse.

Referring to Fig. 1, which shows the essential elements of a cathode-ray tube in schematic or diagrammatic form, the numeral 10 represents a cathode-ray beam which is produced by any well-known electron gun such as is conventionally used in cathode-ray tubes. Surrounding the beam are sets of electrodes. Merely for simplicity in showing, it will be assumed that the beam is to assume four successive counting positions A, B, C, X. Each of these sets of electrodes comprises a beam-deflecting plate 11, a secondary emission target 12, and a cooperating target discharge electrode 13. Thus the set of electrodes for the A position comprises electrodes 11A, 12A, 13A; similarly the corresponding electrodes for the B position are designated 11B, 12B, 13B; for the C position 11C, 12C, 13C; and for the position 11X, 12X, 13X. The deflecting electrode A HA is directly connected to its associated discharge electrode 13A and also directly to the target electrode 12X of the X position. Likewise the deflector element 11B is directly connected to its associated discharge electrode 138 and also directly to the target electrode 12A of the A position. Similarly, the deflector element 11C of the C position is directly connected to its associated discharge electrode 33C and also directly to the target electrode 123 of the 8 position. Likewise the deflector element 11X of the X position is directly connected to its associated discharge electrode 13X and also directly to the target electrode 12C of the C position.

Normally, in the absence of any received positive pulses on the control grid, the beam it is blanked-01f, for example by applying a suitable negative bias to the usual control grid embodied in the cathode-ray tube. In Fig. 1 the blanked-off beam at the different positions it would assume if not blanked-off, is represented by the unshaded dotted circles MA, MB, lbC, itlX. The on beam position is represented by the shaded corresponding dotted squares. Therefore with none of the sets of electrodes energized, the beam 10 would, if not blankedofl, tend to follow a straight line trajectory down the length of the tube symmetrically positioned with respect to all the various electrodes. Each of the target elec- 12C, 12X, has a secondary electron emission surface which when struck by the cathode-ray beam, causes the said target to assume a high positive floating potential by reason of the fact that the ratio of secondary emission to primary emission is rather high. By means of suitable circuits to be described hereinbelow, this floating potential is maintained until the said target is discharged in response to the next beam-on pulse. By any suitable means, the cycle of operations is such that with the beam blessed to cut-off at the control grid, the deflector plate 11A will be pulsed by any suitable means to a positive potential. This tends to pro-position the blanked-otf beam as if it were at the point 10A. It will be understood that all the target electrodes 12A, 12B, 12C, 12X, are carried by an insulating backing or member, so that when they are pulsed to a positive potential, by any means, they remain at that potential until a discharge path is provided. In accordance with the present invention, the targets are pulsed to their high positive potential by the cathode-ray beam, and this same beam also is used to discharge the targets successively as successive pulses are received.

With the target 12K and deflector plate 11A initially brought to a high positive potential as above-mentioned, the beam 10 remains cut off awaiting the receipt of the first pulse to be counted. On the receipt of the first positive pulse at the control grid, the beam is keyed on, and instantaneously finds itself at position 10A, Where it impinges on discharge electrode 13A which causes the positive potential on target 12X and on deflector plate 11A to drop. As the positive potential on plate 11A above in connection with Fig. 1.

drops, the beam moves towards its axial position, but in doing so, it impinges on target 12A. On striking target 12A, the beam causes the release of secondary electrons, raising that target to a high positive floating potential which likewise raises the potential of deflector plate 11B. Thus the beam is moved away from the target 12A towards position 103. The rate at which it moves from position A to position 103, will of course be a function of the time rate of discharge of the plate 11A and the building-up of the positive charge on plate 11B. In the meanwhile, the first positive pulse has ceased, and the beam is cut oif. However, the plate 11B and the target 12A remain at their high positive floating potential, as will be described in connection with Fig. 2. Upon rcccipt of the next positive pulse at the control grid, the beam is keyed on, and immediately strikes discharge electrode 138 which is directly connected to the deflecting plate 11B, thus discharging target 12A and dropping the potential of deflector plate 11B. The beam therefore moves towards position 10C, but is in the meanwhile keyed ofi by the cessation of the second pulse on the control grid. The same cycle of operations occurs for each succeeding pulse that is received on the control grid.

Referring to Fig. 2, there is shown in composite per spective and schematic wiring diagram form, a tube and associated circuits employing the principles explained In Fig. 2, there is shown a suitable evacuated enclosing bulb or envelope 14,

. having mounted at one end an electron gun 15 for developing a focussed beam of electrons. This gun may be of any construction well known in the cathode-ray tube art, comprising for example the electron-emitting cathode 16, the apertured control grid 17, and the successive accelerating and focussing anodes 18, 19, 20, which are connected tto successively higher positive direct current potentials as is well known in the cathode-ray tube art. Preferably also, the inner surface of the bulb 14 is provided with a conductive coating 21, for example of Aquadag, which is connected to the terminal 22 of high positive direct current potential ordinarily referred to as the second anode potential, and derived from a suitable direct current source 23, the negative terminal of which may be grounded. The control grid 17 is biassed negatively with respect to the cathode 16 by a suitable adjustable negative direct current bias source 24 which is connected to the grid 17 through a suitable resistor 25. The source 26 of input pulses to be counted is also coupled through a condenser 27 to the control grid 17, these pulses being positive. However, in the absence of such pulses, the grid 17 is statically biassed from the source 24 so as to blank-off the electron beam.

Suitably mounted adjacent the opposite end of the bulb 14 is an insulator plate or disc 28 which carries a series of secondary emission targets 12A.12X, each of these targets being provided with a separate lead-in member 29, 30, 31, 32. Merely for clarity in Showing, the targets 12A-12X are shown spaced from the plate 28. It will be understood, of course, that these targets can be attached in any suitable manner to the said plate, and can be connected to the respective lead-ins 29-32 in any well-known manner. Mounted in front of the plate 28 on the side facing the electron gun is an apertured metal disc or plate 33 which is arranged to act as a secondary electron collector, and for that purpose it is provided with a lead-in conductor 34 which is connected to a terminal 35 on the direct current power supply which is at a higher positive potential than the terminal 22, for example the terminal 35 may be at 200 volts more positive than the terminal 22. The secondary electron collector electrode 33 has a series of enlarged apertures 36, 37, 38, 39, in alignment with the respective targets 12A-12X. Mounted between the collector 33 and the electron gun are a series of discharge electrodes 13A -13X. These discharge electrodes are arranged in a circular array on a greater radius than the array of the targets 12A-12X. Each discharge electrode is connected to a corresponding secondary emission target as indicated in Fig. 1. Thus, discharge electrode 13A is connected by conductor 40 to lead-in 32, and thence to target 12X. Likewise, the discharge electrode 13B is connected by conductor 41 to lead-in 30 and to target 12A; discharge electrode 130 is connected by conductor 42 to lead-in 30, and thus to target 12B. Similarly,

discharge electrode 13X is connected by conductor 43 to lead-in 31, and thence to target 12C.

While in the drawing the discharge electrodes 13A13X are shown spaced from the collector 33, and with their respective conductors passing through corresponding openings 44, 45, 46, 47 in the collector, so as to be insulated therefrom, it will be understood that the discharge electrodes 13A-13X may be carried by the collector 33 butsuitably insulated therefrom and with the respective conductors 4043 likewise insulated from the collector.

Suitably mounted between the electron gun and the discharge electrodes are the beam deflector plates 11A11X. Plate 11A is connected by conductor 48 to discharge electrode 13A; deflector plate 11B is connected by conductor 49 to discharge electrode 13B; deflector plate 11C is connected by conductor 50 to discharge electrode 130, and deflector plate 11X is connected by conductor 51 to discharge electrode 13X. In order to maintain each of the targets 12A--12X at its pulsed high positive potential as a result of the electron beam striking it, each target is provided With a separate potential maintaining circuit of any well-known type. Thus as shown in Fig. 2, each of the targets is connected by a respective conductor 52, 53, 54, 55, to respective plate electrodes or dynodes 56, 57, 58, 59, of a so-called flood gun tube 60. This tube may be of any well-known type having an evacuated enclosing envelope 61, with an electron-emitting cathode 62, a first control grid 63, a collector grid 64, and the series of dynodes 56-59. Each of the dynodes 5659 is connected through a respective resistor 65-68 to the second anode potential terminal 22 as is the cathode 61. However, the collector grid 64 is connected to terminal 35 which is 200 volts more positive than the cathode. Consequently, when the targets 12A12X are not pulsed to their high floating potential as above described, the dynodes 56-59 are at the potential of terminal 22. The first control grid 63 is biassed negatively with respect to the cathode an adjustable amount under control of a suitable adjustable direct current biassing source 69.

As described previously, when deflection plate 11A is pulsed to high float, by an external suitable means, secondary surface 12X and dynode 56 connected by conductors 40, and 32 will also go to high positive potential. This high positive potential will draw current from cathode 61 of tube and knock secondary electrons from surface 56. These secondary electrons will be collected by collector anode 64. The flow of secondary electrons through load resistance 65 wi maintain the high float condition.

Thereupon the beam in the off condition is prepositioned and maintained as it were, at the point 10A of Fig. 1. When the beam is keyed on, it impinges on discharge electrode 13A. It will discharge the high float condition of dynode 56. Dynode load resistance 65 will go to low float as well as deflector 11A. Thereupon the beam falls, impinging on surface 12A and thereby charging it and associated dynode 57 to high positive float. Secondary current through dynode resistance 66 from surface 57 will maintain this positive potential until discharged. The beam then will return to the blanked condition and be prepositioned at 10B due to the positive potential of deflection element 11B. Upon application of input positive pulse to 26 the beam will dischargethe dynode, load resistance 66 and deflector 11B will go to low float condition. The beam will impinge on surface 123 charging it and associated dynode 58 to high positive float condition. This float condition will be maintained by the secondary current through resistance 67 from dynode 58. The beam thereupon will be blanked off and electrostatically prepositioncd at 10C due to the maintenance of the high positive potential across resistance 67 which is connected to deflection 110. An additional input positive pulse will turn the beam on discharging dynode 58. Resistor 67 and deflector will go to low float. The beam will fall, striking secondary surface 12C and thereby bringing it and dynode 59 to high float by secondary current through resistor 68. The beam is blanked and prepositioned to position 10X by deflector 11X which is connected to dynode 59. Subsequent positive pulses applied to 26 will repeat the above cycle.

From the above it can be seen that dynode 59 tied to secondary surface 12X will produce a positive output pulse once in every X input pulses. This assumes each counter consists of X number of target sections. In eflect this allows the realization of a step down count ratio. Thereupon the output pulse can be made to drive successive electron counting circuits of the type described herein. Fig. 4 illustrates interconnection of two counters producing a count downratio of one, on X pulses. This output could actuate an amplifier which can be utilized to trigger an additional circuit in well-known manner.

The manner of use of the apparatus of the system shown in Fig. 2 will be clear from the foregoing descrip tions, it being understood, of course, that the duration of each pulse to be counted, as applied to the control grid 17, is greater than the transit time of the beam, in dropping from each discharge electrode to the associated target electrode.

From the foregoing descriptions, it will be seen that the electron beam instead of being deflected a variable amount by a variable amplitude signal input, produces its own deflection voltage. In other words, the incoming pulses merely key the beam on and off. It will be understood, of course, that the invention is not limited to an actual keying off of the beam. For example, the beam may having a normal intensity which is so low that when it strikes a discharge electrode at such low intensity, it exerts very little discharging action on the previously positively-charged floating target electrode. On the other hand, when the beam is modulated to high intensity by an incoming pulse, this intensity is of suflicient amount to efl'ect the necessary discharge of the previously-charged target.

While the invention finds its primary utility as a pulsecounting or pulse-recording system, it will be seen that if the cut-off bias from the source 24 is removed so that the beam is continually leaving the gun, the beam will automatically step around from target to target, and will continue to step until it is blanked-off in any suitable way. The frequency of stepping of the beam will then be dependent upon the transit time of the beam and the dynode load constants.

The dynode load capacity for each target section is the summation of the dynode capacity together with the associated deflector plate and secondary surface capacity. This capacity is charged through the cathode beam when a secondary target is struck. When a discharge element is struck, the capacity is partially discharged through the beam drawing primary current. The beam in effect shunts the dynode load. Additional discharge takes place through the dynode load resistance so that high float is not sustained. The additional discharge through the dynode load is expressed by =Eoe /rC. Pulse input reoccurence rate must not exceed the time necessary for discharge as outlined above, together with the time the beam takes in transit from the discharge element of one section to the secondary surface of the succeeding target section. By the expression floating potential as employed herein is means that an electrode which is normally insulated from external circuits is brought to a steady positive potential and remains at that potential until it is discharged by the impinging cathode-ray beam.

Various changes and modifications may be made in the disclosed embodiment without departing from the spirit and scope of the invention.

What is claimed is:

1. Apparatus of the type described, comprising means to develop a deflectable beam of electrons having a normal trajectory, a plurality of electrode sets with the sets successively surrounding said trajectory, each set comprising in sequence along the said trajectory a beam deflector, a deflector discharge electrode, and a secondary emission target; means directly connecting the deflector element and discharge electrode of each set, means directly correcting the target of one set to the deflector element of the next succeeding set, and means to modulate the beam intensity under control of received signal elements to cause the beam automatically to charge and discharge each deflector element in succession in accordance with the number of said received signal elements.

2. Apparatus of the type described, comprising means to develop a deflectable beam of electrons having a normal trajectory; a plurality of electrode sets successively surrounding said trajectory each set comprising a beam deflector, a deflector discharge electrode and a secondary emission target; means to modulate the beam intensity between lower'and upper limits corresponding to received electric signals, one of said deflectors being initially charged to a floating potential to pro-position the beam trajectory so that it is in the path of the associated discharge electrode; means to increase the beam intensity to complete a discharge path between one of said deflector electrodes and its associated discharge electrode for causing the beam to return partially to its normal trajectory, the secondary emission target associated with said one of said deflectors being mounted so as to be bombarded by the beam during said partial return; and means effective in response to said bombarding to cause another deflector to assume a predetermined floating potential corresponding to the potential of the target bombarded by said beam.

3. Apparatus according to claim 2, in which each of said secondary emission targets is connected to corresponding electron tube means for causing each target to maintain a predetermined positive floating potential after it is bombarded by said beam in response to a succeeding signal intensity modulation of said beam.

4. Apparatus of the type described, comprising a cathode-ray tube having an electron gun for developing a beam of electrons having a normal trajectory, a beam intensity control electrode, a plurality of deflector elements surrounding said trajectory, a plurality of secondary emission targets surrounding said trajectory, a plurality of deflector discharge electrodes surrounding said trajectory; means to modulate the intensity of said beam under control of applied electric signals; and means including said targets, said discharge electrodes, said deflector electrodes and said beam for automatically deflecting the beam successively to said deflector elements in response to electric signals successively applied to said control electrode.

5. Apparatus according to claim 4, in which said deflector elements, secondary emission targets and deflector discharge electrodes are arranged in successive sets around said trajectory; and said last-mentioned means includes a connection between the deflector element and the discharge electrode of one set and. the secondary emission target of a preceding set.

6. Apparatus according to claim 4, in which each of said targets is brought to a predetermined positive floating potential when impinged upon by said signal-modulated beam, and separate means are provided for maintaining each target at its said floating potential after said impingement ceases.

7. A pulse generator apparatus, comprising means to develop a deflectable beam of electrons said beam having a normal trajectory, a plurality of electrode sets surrounding said trajectory each set including a beam deflector, a secondary emission target and a deflector discharge electrode; an intensity control element for said beam; means to bias said element to maintain said beam at a predetermined intensity; and electrical connections between the deflector element discharge electrode of one set and a secondary emission target of a preceding set for cooperating with said beam to cause the beam to automatically step itself around from one target to another at a predetermined rate.

8. Apparatus of the type described, comprising in combination, means to develop a deflectable electron beam, means to key the beam OE and on in response to signal pulses, a plurality of sets of electrodes each set located at a respectively difierent position to which the beam is to be deflected in response to successive keying pulses, each set of electrodes including a secondary emission target, a beam deflector electrode and a target discharge electrode, said target being responsive to impingement of the beam thereon to cause it to assume a predetermined positive potential, means to apply an initial starting pulse to the deflector electrode of one set so that when the beam is keyed on by a first signal pulse it assumes a position in registry with the discharge electrode of said one set and automatically causes the beam to proceed to the target electrode of said one set, and an electric connection between said target electrode of one set and the deflector electrode of a succeeding set for simultaneously raising the positive potential of said deflector electrode of said succeeding set to deflect the beam thereto in response to a said signal pulse.

9. Apparatus of the type described, comprising means to develop a deflectable electron beam, a plurality of successively arranged sets of electrodes located at respectively difierent-positions to which the beam is to be defiected in response to successive signal pulses, each electrodc set including a beam deflector electrode, a'secondary electron emission target and a discharge electrode, means connecting the deflector electrode-of each set to its associated discharge electrode, means connecting the target'of each set to the deflector electrode of the next succeeding set, and means to apply signal pulses to modulate the beam to step to the successive sets of electrodes in accordance with the number of signal pulses.

maim d; cues in the file of this patent UNITED STATE. PATENTS.

Schlesinger Dec. 26, 1939 Hollman Feb. 13, 1940 Hellman Jan. 28, 1941 Roscncrans Jan. 30, 1945 Skellett Feb. 19, 1946 Snyder Sears Mar. 18, 1947 Rosen July 26, 1949

Images