US2940047A - Multi-position electronic gating circuits - Google Patents

Description

June 7, 1960 J. R. BETHKE ETAL MULTIPOSITION ELECTRONIC GATING CIRCUITS 2 Sheets-Sheet 1 Filed Sept DEVICE GATING GATING INPUT SIGNAL SYNC PULSE GENERATOR COMMUTATING 79 DEVICE BINARY COUNTER SWITCHING CIRCUIT SWITCHING vloz INPUT SIGNAL u S R Y 6 O K W SS HRN I rd VU H m NBRC 1 .TW 5 R R I 6 N EL v L HBU I A 00A 6 O N JDnS WT I mm HI S V1 U m AN 8 W N S Y S 9 B m oi M 9 \T G B A G mm m w w Em T I M R TE R E i E C Tm .1 FTI UV 8 SUV m o m NME A O W m AM mw 8 1 r 2 m E U m: 8 G 9 SW 8 W E mm E H E 67; a++ GATING P DEVICE IOOg I O SIGNAL SYNC ATTORNEY ilnitedli States Patent MULTI-POSITION ELECTRONIC GATING CIRCUITS John R. Bethke, Paoli, Robert R. Driscoll, Philadelphia, and Saul Kuchinsky, Phoenixville, Pa., assignors to Burroughs Corporation, Detroit, Mich, a corporation of Michigan Filed Sept. 14, 1955, Ser. No. 534,232

12 Claims. (Cl. 328-'52) This invention relates generally to multi-position electron beam position tubes and more particularly to means for gating signals from any one of a plurality of positions of a multi-position electron beam tube circuit to a corresponding utilization device.

There is now available in the art a multi-position beam switching tube having a plurality of compartments each containing one of a plurality of target electrodes arranged concentrically around an elongated cathode,; Each of the target electrodes is associated with a cor responding spade electrode used for locking the cathode,; ray beam in a stable position upon its target electrode in a selected compartment. A magnetic field is created substantially parallel to the elongated cathode throughout the tube so that an electron beam formed at the cathode of the tube will tend to follow a substantially equipotential path established by the potentials coupled to the various electrodes. By analogy the tubes are known as magnetron beam switching tubes. A potential source coupled to the spade electrodes creates an electrostatic field which is converted by lowering the potential of a single spade electrode to establish a substantially equipotential line from a particular target electrode to the cathode so that the electron beam will flow from the cathode to a single compartment defined by the said particular target. A small portion of the electron beam locks upon the associated spade electrode and reduces its potential by means of a load impedance to thereby hold the spade at reduced potential and direct the remainder of the electron beam upon the corresponding target electrode.

Because of the magnetic field, the electron beam has a tendency to continuously rotate in a tight spiral around the cathode in one direction and would re-enter the cathode if it were not loccked upon a particular spade electrode. When a substantially equipotential line is created between the cathode and the compartment adjacent to the compartment upon which the electron beam is impinging, the electron beam is caused to advance to the said adjacent compartment where it locks upon the spade electrode thereof. In some of the earlier tubes, this type of advancing may be accomplished by lowering the potential of either the spade electrode or the target electrode, as is described in the US. Backmark Patent 2,591,997. A more recent development has resulted in the provision of a switching or control grid electrode in each compartment for producing more reliable beam switching and locking. Such tubes are described in the US. Patent 2,721,955,

issued to Sin-pih Fan and Saul Kuchinsky on October 25,

1955. The switching electrode of one compartment, upon being reduced sulficiently in potential, performs the function of establishing an equipotential path between the cathode and a spade electrode of an adjacent compartment to deflect the electron beam and cause it to become locked in upon the adjacent compartment. If the potentials of successive ones of the switching electrodes are caused to assume a potential such as to establish an equipotential path between the associated compartment 'f'ice and the cathode, the electron beam will be caused to step consecutively from one compartment to the next. This has been accomplished in one manner by connecting one set of alternate switching electrodes (hereinafter referred to as even numbered electrodes) to one output terminal of a circuit such as a complemented flip-flop 0r binary counter circuit and connecting the other set of (odd numbered) alternate switching electrodes to the other output of the flip-flop or binary circuit. Successive input pulses to the flip-flop circuit would then cause the electron beam to advance progressively from one compartment to the next.

For many difierent output circuit applications of these multi-position tubes, it has been desirable to effect selective gating of the beam arriving at a particular target electrode to a load circuit. For example, in multiplexing operations, it is usual to gate in at a number of different circuits modulated signals at corresponding successive time intervals. In this manner, the beam tubes hereinbefore described are well adapted to switch a plurality of different modulated signals at high speeds. However, when such devices are used to produce high speed commutating of a plurality of channels and it is desirable to gate the channels selectively only at specified intervals, in the past it has been necessary to provide a separate gating circuit in each of the multiple channels. Whenever a gating circuit is necessary for each of the target electrodes of a beam switching tube, in all except extremely high speed operations, circuit economy has been marginal in use of the beam tubes in view of alternative circuits such as conventional cascade flip-flop dis tributors.

Therefore, it is a general object of the invention to provide improved multi-position electronic gating circuits for beam switching tubes of the type described hereinbefore.

An object of the present invention is to provide a system including a multiple position electron beam tube in which the electron beam may be channeled to a load circuit at any of its various beam positions in response to a single gating circuit.

Another object of the invention is to provide a simplified magnetron type electron'beam switching tube transfer system in which a single gating circuit may be used to elfect transfer of information from one tube to another.

A still further object of the invention is to provide magnetron beam tube gating circuits adaptable for operation with magnetic matrix memory systems.

Thus, in accordance with the invention, a circuit is provided for selectively gating a signal at any one of several individual load circuits respectively coupled to any one of the multiple target positions in response to gating pulses at a single electronic gating circuit. This gating circuit may comprise a normally cutoff triode amplifier tube which is commonly coupled to one terminal of each of a plurality of load devices which have their other terminal connected respectively to each of the beam tube targets for receiving beam current as the beam dwells upon the corresponding targets during switching from one target position to the other.. To effect the gating operation an auxiliary beam current path is provided for each target so that the beam current is not passed through the corresponding loads unless the gating tube is made conductive by a corresponding gating input signal pulse. In the simplest configuration the auxiliary path may comprise a crystal diode coupled to a supply voltage somewhat less positive with respect to the beam tube cathode than a futher potential coupled to the gating tube anode.

Thus, the preferred beam current path is through the gat- In this manner, coincidence era-te any oneof the-multiple leads directly from beam current of the switching tube.

Other'objects and features of the invention will be more fully understood from the following detailed de scription thereof when read in conjunction with the drawingsgin which:

Fig. 1 is a perspective assembly view mt a multi-position magnetron beam switching tube utilized with the invention; 7 7

Fig. .2 'is a schematic circuit diagram of a multi-posit-ion electronic gating circuitembodying the invention;

Fig. .3 is a simplified block diagram circuit of a multiposition .gating circuitafforded by the invention;

Fig; 4 is a schematic circuit diagram of a coincidence signal magnetic matrix memory constructed in accordance with the teachings of the invention;

Fig. .5 :is a schematic circuit :diagram of -a magnetron beam tube 'information transfer circuit embodying the invention; and i v Fig. 6 is a simplified hlock idiagram of atransfer circuit incorporating the invention.

7 Referring now to Fig. 1, there is shown a :perspective view of .a magnetron beam fswitching tube which used in accordance with this invention. a

This :type tube is well .known .in the art, and is supplied by Lformerly Haydn Brothers of New Jersey, now the Electronic Tube Division of Burroughs Corporation, =under .the type number 6700 (MO-l). Consequently,

' only enough description will be given herein of the structure and theory of operation :of the tube 9 of Fig. '1 to enable an understanding of the present invention. The cathode 41 is positioned within thehermetically sealed envelope .10. A plurality of elongated spade electrodes 31'throngh 40, having a U-shaped cross section, .are positio'ned concentrically about the cathode 41. .In the structure shown in *Fig. 1, there areten such spade :electrodes.

Similarly, there are ten elongated target ele'ctrodes 1-1- through 20,.having an L-shaped cross section, likewise positioned concentrically around the .cathode 41,-a'nd each having-the extension of the Lpositioned within itheitrough of one of the ten spade electrodes, and having Ethe :base

of the -L spanning the spacebetween two adjacent :spades. Each target with its two adjacent spades defines'ia :compartment for receiving the beam in one ofits ten stable locked in positions. Tenswitching electrodes 21 through 30 are also positioned concentricallyiaround the cathode 41 and are each individually po'sitioned in one of'th'e compartments between 'the open base end of a target electrode and one extending leg of 'a spade electrode. For example, switching electrode 21 :is positioned between the extending leg of spade electrode 40' and the open base end of target electrode '11. The concentric magnet 42 placed about the envelope 10 produces amagnetic field in the tube that is substantially parallel to the elongated cathode 41. Thismagneticifield is of a polarity 'which will cause an electron beam extendingontwardly from thecathode41 to sweep around the tube in a'clockwise direction (viewed from ,the top :of the tube) in accordance with wellkno'wn principles. Each ofthe spade'.

electrodes: is adapted to lock the electron beam in a particular compartment by a lowering of its potential. The

gating signal nt the single gating tube is required to opi 7 beam to advance to that clockwisespade electrode which willhold the beam 'in the compartment adjacent the one upon which it impinges in the absence of a switching potential.

With reference to the embodiment of Fig. 2, the various elements of the tube of' Fig. 2 are schematically 'drawn in order to make the schematic presentation of the drawing more easily understood. This type of presentation, which is related to the tnbe'of Fig. 1 by utilization of similar reference characters, -is-used throughout the following specification and drawings. Thns,.the three groups of tube electrodes comprising the targets 20, 19, etc., the spades 40, 39, etc., and the switching electrodes 30, 29, etc., are arranged in a straight line so that the respective groups of electrodes for the tube positions 0, 1, etc., are adjacent to each other. In Fig. 2 only the first five tube compartments are illustrated, and similar construction is employed for further tube elements such as found in a ten position tube of the type described in connection with 'Fig. 1. Each of the spade resistors 60, 59, etc. is chosen tohave a value such as 100,000 ohms for locking'the beam-in at a particular target position by flow of beam current to the corresponding spade electrodes 40,39, etc. The beam is switched "from posischematically by the open and filled circular notation,

which may be "designated respectively as the even and odd grid groups. Ashereinbefore described, application of :anegative switching signal of'about 50 volts to'one of the respective groups will cause the-tube to switch the beam a single position regardless of the duration of the switching signal above a minimum amplitude and'time (in the order of 0.2 microsecond).- The next switching signal 'to effect switching must therefore be applied to V the alternate group of grids. -Thus, negative switching signals maybe applied at the Zero andone gate terminals 63 and 64 from a-suitable circuit snch'as -'a conventional bistable 'flip-fiop'counter which is actuated by successive switching pulses at an input I complementing terminal. This type 'ofbinary counter circuit 'is indicatedin block diagram form 65in Fig. 3.

Each target electrode 20, '19, etc. is coupled to the spade voltage supply atterminal-66 by one of the respective diodes'fiti, 79, etc. which provides a low impedance 7 unilateral conductive path for the beam currentarriving at any one of the corresponding target electrodes; A

beam'rernains locked in by means of the electronbeam flowing through a spade impedance connected to the-particular 'spade electrode upon which the electron beam is impinging thereby causing eno'ugh potential drop across said impedance to establish 'a substantially equipotential path somewhere between the two adjacent spade electrodes and the cathode to cause the beam to impinge upon'the intervening'base of the associated target electrod'e. The switching electrodes perform the function of deflecting the electron beam to impinge upon the next consecutivespa'de electrode by distorting the electric field within "a particular compartment to cause the electron loadcircuit illustrated by the inductances 90, 89, etc. is coupled to the corresponding target electrodes '20, 19, etc. to alternatively receive beam current whenever the beam impinges upon a corresponding target electrode. These coils maybe, for example, relay coils which are operated to select digits of a Teletype code in the manner described in the US. Patent 2,099,065to'W. H. T. Holden, issued November 16, 1937. Likewise, as is -discussed hereinafter in detail in connection with Fig. 4

in amore complex switching system, the inductances 90,

89, etc. may comprise bistable state magnetic storage-devices. In general the magnetron beam switching tubes hereinbefore described provide sufiicient beam current to operate either relay coils of the type'applicable-to the hereinbefore described circuit, or conventional bistable state magnetic storage devices'of thetype Well known in the art. In "either instance, it is desirable to selectively actuate one or more of the inductances 90, 89, "etcindividually in response to input signal intelligence. For this reason, the gating circuit 67 is provided for.connection between the common buss '68 coupled to one end of each of the load inductances 90, 89, etc. and a supply potential more positivethan the spade potential available at terminal 66. In particular, for operation with a gating triode tube '91 which may comprise one-half of a 5687 type duo-trickle tube, the voltage provided at termihal 69 may be 200 volts, whereas the spade potential'at terminal 66 is 100 volts. The triode 91 is normally maintained at cutoff potential by means of the C supply potential and the pro'per setting of the potentiometer 92. Accordingly, a suitable positive gating pulse for overcoming cut-off and causing tube 91 to tend to fully conduct is applied at the gate input terminal 93 through condenser 94. The gating potential is developed across the grid resistor 95 to turn on the normally cuto'fi triode tube 91 and thereby establish a preferred beam current path through any one of the respective load inductances 90, 89, etc. as the beam strikes the corresponding target. Because of the uni-directional properties of the diodes 80, 79, etc. no current will pass to the spade potential terminal 66 from the target supply terminal 69. However,'when the beam impinges upon a particular target such as 20, because of the higher potential at terminal 69, current will flow to the load inductor 90 for the duration of the period that the beam is striking the target 20 or the duration of the gating pulse, whichever is the shorter. This action causes the diode 80 to be completely cut off by sending the cathode more positive than the anode potential at the spade supply level of terminal 66. Accordingly, upon coincidence of a gating input signal at terminal 93 and presence of the beam upon one of the targets 20, 19, etc., a particular one of the inductance lo'ad circuits 90, 89, etc. will be chosen.

In general, the operation of a system in the manner described in connection with Fig. 2 is illustrated by the block diagram presentation of Fig. 3 wherein similar elements to those hereinbefore described are identified by similar reference characters which are primed to indicate that certain variations from a specific circuit shown may be made by those skilled in the art with departing from the spirit or the scope of the present invention.

In order to assure the selection of a single load circuit in response to a discrete length gating input signal from some signal source 98, a common synchronizing pulse generator 99 may be employed for operating both the switching circuit 65 and the gating device 67. Thus, for producing a gating signal at the gating device 67', the coincidence of a synchronizing pulse from generator 99 and an input signal from source 98 is required at the and circuit 100. Likewise, if periodic switching from the synchronizing pulse generator 99 is not desired, but switching in response to some intelligence source, a further and circuit 101 may be supplied for operation from simultaneous synchronizing pulses from generator 99 and switching signals from a signal input source 102. In this manner, it is assured that when the synchronizing pulses occur for a long enough duration, the load circuits 90, 89, etc. will be fully operated by the beam current at a single switching position. If the duty cycle is short, that is, the synchronizing pulses are spaced far enough apart, a generally uncritical switching signal or input gating signal width may be tolerated without gating the signal during two switching intervals so that the gating occurs upon two successive target electrodes. In general, the switching time of the tube is extremely rapid so that the synchronizing pulse will cause the beam to arrive on a particular target by the time the gating device is fully actuated. However, should unusual conditio'ns be encountered, the delay circuit 103 may be inserted in the gating lead to assure that the beam is switched to the particular target before the gating device 67' is opened. It is, of course, to be recognized that, under some types of circuit operation, it might be desired to normally pass information to the load circuits as the beam is switched, and therefore the gating devices might be normally open or conductive, and be closed by application of a gating input signal. To select a single load device in this type of operation, the delay circuit 103 would be replaced by a unistable state flip-flop or multivibrator type circuit which is set with one synchronizing pulse and reset automatically before the following synchronizing for more than the period of dwell of the beam upon one of the target electrodes.

Application of the invention to a more complex gating problem as associated with the selection of magnetic cores in a matrix type memory system is illustrated in Fig. 4. In general, the gating principles are identical with the circuit described in connection with Fig. 2 except that a plurality of load circuits is coupled with each target electrode of the beam switching tube 9. Thus, a separate gating tube 67a through 67e is required for each of the five rows of magnetic cores shown in the drawings. Each gating tube is coupled by a corresponding lead 104 through 108 to one end of each winding 109 about a static magnetic storage element 110 along one of the corresponding rows of elements. Each beam tube target 20, 19, etc. is coupled by an ano'de lead 20', 19', etc. along each of the columns of magnetic elements 110 at the other end of the windings 109. Thus, as the beam is stepped from target to target in the switching tube 9, each of the columns of cores is scanned, and by selection of one of the rows by opening the corresponding gating tube circuits 67a through 67e an individual core at the intersection of a column and row may be energized directly by means of beam current flowing in the switching tube 9. Thus, it is evident that the gating principles afforded by the present invention may be extended to include more complex systems, and are particularly useful in connection with the binary static magnetic storage or matrix memory devices by a coincident selection technique for applying a single current to a single winding about the elements.

In some cases it is desirable to use the switching tubes themselves as storage devices for decimal numbers, and in this case it is sometimes necessary to transfer the stored information comprising the beam position from one beam switching tube to another. The gating circuit of the present invention is employed in performing this transfer function as shown schematically in Fig. 5. The gating operation of the left hand tube section is identical to that hereinbefo're described, with the exception that the load circuits are replaced with 15.0K ohm resistors 90", 89", etc. in this embodiment. It is desirable to transfer the indication from the transferor tube 9 to the transferee tube 9. To assure that the transfer is properlymade, it is necessary to clear or blank the beam in the, transferee tube 9'. For this purpose the clearing circuit is provided, which comprises the normally cutoff amplifier tube 121', which may be similar to tube 91 in the gating circuit 67. This tube is maintained at cutoff by proper adjustment of the C bias voltage at the potentiometer 122 so that an input signal arriving by way of capacitor 123 and developed at the grid input resistor 124 may cause the tube to conduct through its load resistor 125. This conduction when resistor 125 has a value of about 10.0K ohms is effective to reduce the potential at the bus 126 about 70.0 volts, which thereby reduces the potential of all the spade electrodes 40', 39, etc. enough to cause the beam in the tube 9' to extinguish. When the beam is extinguished, all of the spade electrodes 40, 39, etc. are at the same potential and one spade electrode must be reduced in potential in order to reestablish the beam at a particular tube position. Thus, a transfer of the beam position of transfer or tube 9 is made from one of the transfer leads 190, 189, etc. by means of a decrease of spade potential developed across the corresponding 50.0 K ohm resistors 130, 129, etc. When the transferee tube 9 is cleared, therefore, it is evident that the transfer is effected by an input signal at the terminal 93 of the gating'circuit 67, which causes a decrease in potential at that particular target load resistor 90", 89",

etc. corresponding to the position of the beam in the transferee tube 9" along one of the corresponding transfer '7 leads-190, 189, etc. by means of the intervening capacitors 146 and series diodes 141. The diodes 141in the absence of the gating operation normally serve to uncouple the spade circuits of the transferee tube'9 from thetarget circuits of the transferor tube 9 because of their unilaterally conductive characteristics, socapacitors 140 can be omitted when D.-C, coupling is: required.

In order to effect automatic clearing and transfer, synchronous operation of the clearing and. gating tubesis accomplished. by means of the waveforms 150 ,151and' 152 applied at the corresponding terminals, A, B, C and D. In this respect the input waveformISil is applied to input terminals A and C. of the respective-gating circuit 67 and transfer circuit 129. However, the RC- coupling circuit94, 95 of the gating circuit is designed to couple the. input waveform in undistorted fo'rm to the grid circuit B of the gating tube 91 as shown by the waveform 51, whereas the RC coupling circuit 123, 124 of the clearing tube 121 serves to differentiate the input waveform '150 to provide a waveform of the type152 at the grid terminal D of the clearing tube 121. Thus, the positive leading edge of the waveform causes the clearing tube to conduct and thereby clear the transferee tube 9' to a properly receptive condition for receiving the transfer of information from the transferor tube 9 in response to operation of the gating circuit 67. Since the clearing tube '121' is normally cutoff, the negative spike of the waveform 152' has no effect upon circuit operation. A 'general'block diagram of the transfer circuit is shown in Fig. 6 to indicate the general circuit operation. It'js noted, in general, that the beam is switchedfromx position to position in the transferor and transferee commutating devices in synchronism in order to effect. a one for one transfer of. the indication from one device to. the other. It is Within'the concept of the present invention to employ gating circuits other than that specifically described and to clear the transferee tube in some other manner, if desired. It is clear,'however, from the foregoing description of the invention, its operatio'n and mode of construction that an improved and useful gating device is provided for direct high speed operation of relay and storage circuits in an efficient and economical manner. Therefore, the appended claims are directed to features of novelty believed descriptive of the nature and scope of the invention.

What is claimed is:

1. A multiposition gating circuit comprising in combination, a commutating device having a plurality of output positions, means for stepping the device from position to position, a first potential terminal, a diode coupling each said output position to said first potential terminal, a loadicircuit coupled to each output position, a second potential terminal for providing a potential higher than the first terminal, a gating discharge device coupling all the said load circuits commonly to said second terminal, means for selectively operating said discharge device at discrete periods in synchronism with the means for stepping the commutating device, wherein said commutating device is a multi-position transferor magnetron beam switching tube, a further multi-position transferee magnetron beam switching tube is provided and coupled position for position with the load circuits of said transferor tube for selectively receiving the contents of the transfero'r tube in response to operation of said gating discharge device, means for commonly switching both tubes from position to position, and means is provided responsive to'synchronism with the operatingof the gating discharge device for clearing the transferee tube.

'2. A multi-position gating circuit comprising in combination, a magnetron beam switching tube having a plurality' of-target electrodes defining output positions for receiving beam current, means for switching the beam roni position to position, separate high impedance load circuits coupled to' dififcrent target electrodes, a preferred low impedance unil'ateralbeam current path coupled to said diflerenttarget electrodes-normally to conduct beam current. impinging upon the respective target electrodes, a single normally inactivated gating circuit commonly coupled to a plurality of the load circuits for blocking the impedance uniltateral beam current path at the corresponding target electrodes in activated condition, and means for selectively activating the gating circuit to transfer beam current from the low impedance path to the load'circuits of the target electrodes upon which the beam impinges.

3. In combination, a first multi-position transf'eror commutating device, a second multipo'sition transferee commutating device, a switching circuit for causing the transferor device to step from one position to another, output elements connected with the transferor device providing an electrical signal denoting a selected position,'input elements connected with corresponding positions of the transferee device for establishing a separate electrical condition in response to said electrical signals at any one of said output elements, a separate signal developing impedance device coupled to each said output element, a first low impedance path coupled to each impedance device to normally shunt the signal thereat, a single gating circuit common to all of said impedance devices'coupled to disable said low impedance paths and thereby provide a signal at the one impedance device denoting the position of the transferor commutating device, and means operable in synchronism with said gating circuit to clear the position of the transferee commutating device.

4. A circuit including two multi-position magnetron beam switching tubes, each having a plurality of target electrodes for receiving the beam to define-the respective positions and each having a corresponding number of beam forming input electrodes, for transferring position indications from one tube to another, comprising in combination, separate load impedance elements coupled to a plurality of target electrodes'of the first tube, circuit connections to the second tube to establish each of the input elements at the same potential at which beam is extinguished, a normally inactive circuit individually coupling each of the elements to a corresponding input elec trode of the second tube to thereby cause the beam to be formed at the corresponding positionin the second tube in response to beam current flow through the respective impedance element of the first tube, means for stepping the beam-s in at least one tube from position to position, a first alternative beam current path from each target electrode of the first tube actuated in the inactive circuit condition, a preferred alternative beam current path from each load impedance element, selectively actuable gating means in the preferred path common to. all the load impedance elements, beam blanking means for said second tube, and means for synchronously operating the beam blanking means and actuating saidgating means to thereby first clear the second tube and then to eifect transfer of the position indicated in the first tube to the second tube.

5'.- A multi-position gating circuit comprising in combination, a commutating device having a plurality of output positions, means in said device for providing a current flow therein and generating a pulse at each output position in sequence, a first low impedance current path comprising a unilaterally conductive device connected to each output position to provide a current pulse path normally conducting current as each pulse is'presented at its sequential output position, a load circuitconnected to each output position, a single gating circuit coupled to a plurality of the outputvpositions of saiddevice and normally not conducting current through any of said load circuits, and means coupled to said gating circuit for turning it on and thus for blocking the unilaterally conductive low impedance path to thereby transfer the currenlt1 pulse to the load circuit from the low impedance pat v 6. A'muhi-position gating circuit comprising a magnetron beam switching tube including a cathode and a plurality of groups of electrodes, each group including an output target electrode for providing an output signal, each target being connected through a first current flow path including a unidirectionally conductive device to a first reference potential, said first path being normally conductive, each target being coupled to a separate load to a second current flow path including a common gating circuit and a second reference potential, said gating circuit being normally closed and said second current flow paths being non-conductive so that all of the current from a target passes through a unidirectionally conductive device, means coupled to said gating circuit for rendering it conductive and thereby coupling said target electrodes to said second reference potential and rendering said second current paths conductive while effectively blocking said first current paths.

7. A multi-position gating circuit comprising a magnetron beam switching tube including a cathode and a plurality of groups of electrodes, each group including a target output electrode for providing an output signal, each target being connected through a first current flow path including a diode to a first positive reference potential, said first path being normally conductive, each target being connected to a second current flow path including a separate load coupled through a common gating electron flow device to a second more positive reference potential, said gating device being normally closed and said second current flow paths being non-conductive, means in said gating circuit for rendering said gate conductive and thereby coupling said target electrodes to said second reference potential and rendering said second current paths conductive while effectively blocking said diodes.

8. A multi-position gating circuit comprising a magnetron beam switching tube including a cathode and a plurality of groups of electrodes, each group including a target output electrode for providing an output signal, each target being connected through a first current flow path including a diode to a first positive reference potential, said first path being normally conductive, each target being connected to a second current flow path including a separate load coupled through a common gating tube and a second more positive reference potential, said tube including at least a cathode, an anode, and a control grid, each target being connected to the cathode of the gate, said gating tube being normally closed and said second current flow path being non-conductive, said gating tube being adapted to be rendered conductive and thereby coupling said target electrodes to said second reference potential and rendering said second current paths conductive while blocking said diodes.

9. A multiple output gating circuit including an electron beam switching tube having a cathode and a plurality of groups of electrodes; each group of electrodes including an output target electrode which receives an electron beam and produces an output signal therefrom, a spade electrode which holds an electron beam on its associated target electrode, and a switching electrode which serves to switch an electron beam from one group of electrodes to the next; a load circuit coupled to each target electrode; means coupled to said tube for causing an electron beam to switch from one group of electrodes to the next and thereby execute a counting operation; the beam, when at each position, flowing to the target electrode at that position and providing a stream of current which is available to the load circuit at that position; and a single gate means coupled to all of said output electrodes of said tube for controlling the flow of current to each load from its target electrode; said single gate means normally being closed and preventing the flow of current from any target electrode to its load circuit, said gate means also being adapted to be opened to allow current flow from a target electrode to its load circuit.

10. The circuit defined in claim 9 wherein a current flow path provided between each target electrode and its load circuit is normally blocked and current cannot flow to the load, and the gate means is operable to gate on a selected target and allow current to flow in the path between said selected target and its load circuit.

11. The circuit defined in claim 9 wherein a current flow path is provided between each target electrode and its load circuit, gating means is coupled to each of said current flow paths and is adapted to block said paths and prevent current flow from each target to its load while allowing the normal counting operation of stid tube to proceed, said gating means also being adapted to selectively open said paths and allow current flow from a target to its load circuit.

12. The circuit defined in claim 9 wherein said gate means comprises a single electron discharge device coupled to each of said output electrodes, said device being adapted to be rendered non-conductive so that it prevents current flow from any target to its load without aflecting the normal operation of the switching tube, said device also being adapted to be rendered conductive so that it allows current flow from a selected target to its load.

References Cited in the file of this patent UNITED STATES PATENTS 2,195,864 Knoop Apr. 2, 1940 2,224,677 Hanscom Dec. 10, 1940 2,361,766 Hadekel Oct. 31, 1944 2,404,920 Overbeck July 30, 1946 2,499,844 Boothroyd Mar. 7, 1950 2,563,589 Hertog Aug. 7, 1951 2,596,199 Bennett May 13, 1952 2,597,796 I-Iindall May 20, 1952 2,631,232 Baracket Mar. 10, 1953 2,835,808 Bethke May 22, 1958

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