US2802103A

US2802103A - Commutating circuit

Info

Publication number: US2802103A
Application number: US314864A
Authority: US
Inventors: Arthur G Fitzpatrick; Kuchinsky Saul
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1952-10-15
Filing date: 1952-10-15
Publication date: 1957-08-06
Anticipated expiration: 1974-08-06

Description

1957 A. G. FITZPATRICK ETAL 2,802,103

COMMUTATlNG CIRCUIT Filed Oct. 15. 1952 3 Sheets-Sheet 1 INVENTORS ARTHUR G. FITZPATRICK' SgUL KUCHINSKY ATTORNEYS AWL 6, 1957 A. G. FITZPATRICK arm. 2,802,103

conuun'i'mc cmcun' Filed Oct. 15, 1952 3 Shee ts-Sheet 2 ARTHUR G. FITZPATRICK SAUL KUCHINSKY ATTORNEY I30 HO United States Patent COMlVIUTATlN G CIRCUIT Arthur G. Fitzpatrick, Audubon, N. J., and Saul Kuchinsky, Philadelphia, Pa., assignors to Burroughs COI'POI'Q- tion, Detroit, Mich., a corporation of Michigan Application October 15, 1952, Serial No. 314,864

Claims. (Cl. 250-27) This invention relates generally to commutating devices and more particularly to electromagnetic bi-directional counters.

Usually counting of the type to which this invention relates is performed electrically by a series of electron discharge devices arranged in what is known in the art as a counting ring. Gaseous discharge devices or high vacuum tubes are often employed in such counting rings. In the case of gaseous discharge devices each counting stage employs a single gas tube. If high vacuum tubes are em-' ployed there is required a minimum of two tubes per stage to perform the counting function. This is both expensive and relatively complex. A recent development in the electronic counting art is a high vacuum tube capable of causing an electron beam to impinge on any one of a plurality of targets in a consecutive order or a selective order and having a single input conductor upon which the pulses to be counted are impressed. This tube utilizes the motion of an electron stream in an electric field and a magnetic field perpendicular to said electric field. Under these circumstances the path of the charged particle, the electron, follows an equipotential line. If a series of electrodes hereinafter known as spade electrodes are advantageously spaced to form a concentric ring around said cathode between said cathode and said anode, the electron beam can be caused to move successively to various positions by establishing potentials of the said spade electrodes so that a cathode equipotential line is established along a preferred path from said cathode to a point sufiiciently near said anode so that a large portion of the electron beam will impinge upon said anode, and a small portion of the electron beam will impinge upon said spade electrode. By inserting an external load resistance in circuits individually connected with the said electrodes that portion of the electron beam intercepted by a particular spade electrode will cause said electron beam to be locked in that position by virtue of creating a substantially equipotential line.

. It is an object of this invention to provide a bi-directional counting device utilizing electron discharge devices having crossed magnetic and electric field propelled electron beams.

It is a further object of the invention to provide a high speed bi-directional pulse counting device.

A third object of the invention isa stable and reliable bi-directional counting device.

Another object of the invention is to provide an inexpensive high speed bi-directional counting device.

A fifth object of the invention is a high speed bi-directional counting device capable of converting a decimal input into a coded output.

A further object is to provide bi-directional counting means capable of operating over a wide frequency range extending from 0 operations per second to a frequency in excess of 200,000 operations per second.

Another object of the invention is to provide a high speed bi-directional counter capable of encoding decimal input signals into binary signals, or the like.

In accordance with one embodiment of the invention bi-directional operation is obtained by paralleling a master and a slave counter through common output cir-' cuits, but without the use of rotating electromagnetic fields and in which said counters are electron discharge devices.

utilizing crossed electric and magnetic field to propel electron beams along a plurality of discreteselectable paths which follow substantially equipotential lines. One of the electron beams of the two counting. means is caused to rotate in a, first direction in which thecount increases.

and the other electron beam of the said two counting means is caused to rotate in the opposite direction, in

which the count decreases when input pulses to be counted 7 Either counting are impressed upon the input means. means can be the master counting means or the slave counting means, but at any given time one must be the master and the other must be the slave counting means. Determination of which counting means is to be the master and which is to be the slave is made by external electronic means such as a flip flop means which simultaneously will enable one of the counting means (the master counting means) to count and will disable the other (the slave counting means) from counting.

In accordance with one feature of the invention each of said first and second counting means has associated therewith a means to create a uni-directional magnetic field so that one of said counting means is adapted to always rotate in a first direction when acting as the master counting means and the other of said counting means is adapted to always rotate in a second direction when said other of said counting means is acting as said master counting means, thus eliminating any necessity for reversing a magnetic field.

In accordance with another feature of the invention a pair of electronic counting means each having a plurality of output elements and each having an input means common to said plurality of output elements in such a manner that said output elements will becomeenergized in a preselectable order having corresponding ones of said output elements connected to a common terminal through a plurality of loads each individual to each pair of corresponding ones of said output elements of the pair of counting means.

These and other objects and features of the invention will be more fully understood from the following detailed description when read in conjunction with the drawings in which:

Fig. l is a perspective view of an electron discharge device having a plurality of individual output elements selectable by energization of input means to said electron discharge device common to each of said plurality of output means; V

Fig. 2 is a schematic diagram of a circuit embodying the invention; a

I Fig. 2A is a schematic diagram of a flip-flop usable with the circuit of Fig. 2; and

Fig. 3 is a schematic view of the tube shown in Fig. 1 with external circuitry adapted to enable operation thereof.

Referring now to Fig. 1 there is shown a perspective view of an electron discharge device which is suitable for use in carrying out the present invention.

It has been discussed hereinbefore that it is necessary that the electron discharge device have the characteristic of counting input pulses and being capable of manifesting the results of such counting through external circuit means. The electron discharge device shown in Fig. 1 which is a high vacuum tube has a cathode 10 adapted to emit an electron stream along its length. The number of positions of the electron beam which are possible in said tube, that is, the number of possible counting positions, is determined by the number of spade electrodes 11,

Patented Aug. 6, 1957 12, 13, 14, 15, 16, 17, 18, 19, and 20. In the case shown there are ten ditferent and discrete positions. The functions of the spade electrodes will be described in more detail hereinafter. The said cathode is of a-cylindrical construction and is of a nonmagnetic material." The details of construction of the spade electrodes, cathode, anode, and other elements of the tube structure shown in Fig. l are not of themselvespart of the present invention, but are discussed in detail in United States Patent Application Serial Number 291,531, filed June 3, 1952, by Saul Kuchinsky and entitled Multi-Position Beam Tube. Coding means which might also be used in connection with the present invention are described in the copending Kuchinskyapplication, Serial No. 304,344 for Pulse Code Modulation System.

Anode 24 is positioned. around the said spades 11 through and is substantially concentric with the spade arrangement and the cathode 10. A plurality of columns of' apertures are provided in the anode 24, each column of apertures being substantially parallel with the cathode 10 in the embodiment shown in Fig. l. The maximum number of apertures in any given row of this embodiment is four and the minimum number is zero. The aperture positions of each column, whether or not an aperture actually exists in each position, correspond to the four aperture positions of every other column in the axial sense with respect to the cathode. Thus, all the aperture positions existing in the anode 24 would lie in the intersection of the anode. 24 with four plane surfaces each being substantially perpendicular to the axis of the cylindrical anode 24. The intersection of these four imaginary plane surfaces can be arbitrarily designated as defining four levels of aperture positions, each level of aperture positions including one aperture position from each of said rows of apertures. Assume that the lowest or first level of aperture position comprises actual apertures 25 and 26 of two different rows of apertures and also the first level aperture positions for the other rows of apertures. Since the aperture positions in the other IOWs. do not exist in the portion of the anode visible to the eye in the drawing of Fig. 1 they are not shown therein. The second level of apertures comprises actual aperture 27 and the second level aperture positions of all the other rows of apertures. The third level of apertures. comprises apertures 28 and 29. The fourth level of apertures comprises aperture 30. The anode 24has four lips such as

lips

33 and 34, 35 and 36 thereon at either end. These lips fit into circular apertures provided therefor in the mica spacer 21. For example, lip 34 of anode 24 fits into aperture 27 of mica spacer 21.

Collector rings 39, 40, 41, and 42 are secured to

ceramic support rods

43, 44, 45, 46. Alignment for collector rings 39, 40, 41, and 42 can be obtained by securing

support rods

43, 44, 45,and 46 in apertures provided therefor in mica spacers 21 and 37. Each of the four collector rings 39, 40, 41, and 42 is positioned so as to be aligned with a. particular level of aperture positions of anode 24. Further, as can be seen from Fig. l, collector rings 39 through42 are positioned outside anode 24 and are concentric therewith.

The base of the tube which may be either of a ceramic, glass or other insulating material has 18 leads extending therefrom. Ten of these leads are secured individually to the ten lips of the ten spade electrodes where the said lips come through the apertures provided therefor in mica spacer 21. One terminal is connected to one of the lips of the anode 24 which protrudes through the mica spacer 21. Four of the leads are individually electrically connected to each of the four collector rings 39 to 42. Two of the terminals extending from the base of the tube are electrically connected to the heater which is not shown in the drawing. Another terminal extending from the base of the tube is connected directly to the cathode 1 0.

It can be seen by reference to Fig. 1 that the four collector rings 39, 40, 41, and 42 spaced concentrically around the anode 24 collect that part of the electron beam passing through the apertures in the anode 24. Each collector electrode encircling the anode will be associated with the corresponding level of aperture positions in each column although each column may not have an actual aperture path position. Thus, in a tube having four possible aperture positions such as the one illustrated in Fig. 1 there will be four collector rings, one for each of the four possible aperture positions in each column. The apertures may be coded in accordance with the binary system. A portion of the electron beam passes through a coded column of apertures and is collected by the collector rings in accordance with said code and then detected and amplified by means well known in the art. In this manner the particular position of the electron beam is detected. More specifically, the pockets of the tube, beginning with the spade electrodes 50 and 51 of Fig. 3 can be coded to represent the numbers 0, l, 2, 3, 4 5, 6, 7, 8, and 9. A pocket is defined as that area bounded by two adjacent spade electrodes and the portion of the anode 61 therebetween.

Thus, assuming that the electron beam is at the zero or index position, if eight input pulses are applied to the input lead 64 the electron beam will advance to and impinge in the pocket representing the number 8 defined between spade electrodes 58 and 59 and in which pocket the anode apertures are arranged in a binary code equivalent to 8. It is to be understood that the use of the collector rings represents but one embodiment of the type coding ring that can be utilized in the invention. The particular embodiment used in Fig. 2 does not utilize collector rings but indicates the position of the electron beam by a load circuit associated individually with the particular associated spade electrode upon which the electron beam is impinging.

Referring now to Fig. 2 there is shown a schematic sketch of a circuit embodying the invention. The tubes and 81 are of the type shown in Fig. 1 with the exception that the collector rings and associated anode apertures are not shown. Each of the tubes 80 and 81 has ten spade electrodes therein which may, by way of example, be arbitrarily designated to represent decimal digits ranging from 0 to 9. For example, in tube 80 spade electrode 82 represents the decimal digit 0; spade electrode 83 represents the decimal digits 1; spade electrode 84 represents the decimal digit 2; spade electrode 85 represents the decimal digit 3; spade electrode 86 represents the decimal digit 4; spade electrode 37 represents the decimal digit "5; spade electrode 88 representsthe decimal digit 6; spade electrode 89 represents the decimal digit 7; spade electrode 90 represents the decimal digit 8; and spade electrode 91 represents the decimal digit 9.

Referring now to tube 81, spade electrode 92 repre sents decimal digit 0; spadejelectrode 93 represents decimal rigit "1; spade electrode 94 represents decimal digit 2; spade electrode 95 represents decimal digit "3; spade electrode 96 represents decimal digit 4"; spade electrode 97 represents decimal digit 5; spade electrode 98 represents decimal digit 6; spade electrode 99 represents decimal digit 7; spade electrode 100 represents decimal digit 8"; and spade electrode 101 represents decimal digit 9. Since the spade electrodes are respectively positionally. associated with the possible stable beam positions, or counting positions, the digits associated with the spades in the above description may be considered, also, to be the numerical values assigned such counting positions. Other values, however, may be arbitrarily assigned as, for instance, the sequence 0, 10, 20, 30, etc, or 0, 100,200, 300, etc.

The spade electrodes of tube 80 are associated with corresponding spade electrodes of tube 81. For example, spade electrode 82 representing the decimal digit 0" of tube 80 is connected to the spade electrode 92 representing decimal digit of 0 of tube 81 in a circuit extending to conductor 102 and conductor 103. Similarly, every other spade electrode representing a particular decimal digit of tube 80 is connected to the spade electrode representing the corresponding decimal digit of tube 81 to make ten pairs of spade electrodes, each pair of said ten pairs consisting of a spade electrode from tube 80 and a spade electrode from tube 81. Each of these ten pairs of spade electrodes is connected to a +250 volt source 104 through an impedance network individual to each of said pairs of spade electrodes. For example, the pair of spade electrodes 82 and 92 are connected to 250 volt battery source 104 through the parallel combination of 90,000 ohm resistance 105 and microfarad capacitor 106.

Anode 107 of tube 80 is connected to anode 108 of tube 81 and to 250 volt supply 130 through conductor 109. Negative input pulses are applied to the anodes 107, and 108 of tubes 80 and 81 by means of input conductor 110. Zeroizing the two tubes 80 and 81 is accomplished by means of spring arm 111 which is adapted to disconnect 250 volt source 104 from the spade electrodes 82 and 92 of tubes 80 and 81. When spring arm 111 makes contact with contact 134 the spades 82 and 92 are connected to ground through 500,000 ohm resistance 112 and 90,000 ohm resistance 105. Since ground potential is negative with respect to the potential of the cathodes 113 and 114 of tubes 80 and 81 respectively, the electron beam is caused to impinge in those pockets of tubes 80 and 81 representing the 0 decimal digit positions inasmuch as a cathode equipotential line is established thereby between the cathode and extending into the space between the ground potential spade electrode and the positive potential of the anode. It is to be noted that the anodes are ordinarily maintained at a potential substantially in excess of the cathode potential. More specifically, in the absence of a negative input pulse on input conductor 110 and when the spring arm 111 makes contact with contact 133, which is the normal operating position for spring arm 11, the potential of the cathode of the master tube is 150 volts the potential of the anodes 107 and 108 is 250 volts, and the potential of the spade electrodes upon which the electron beam is not impinging is 25 0 volts.

Triodes 115 an 116, which may be of twin triode type #5687, manufactured by Tung Sol Lamp Works of Newark, New Jersey, a corporation of the State of Delaware, perform the function of regulating the beam current of tubes 80 and 81. This operation is also described in the above mentioned Kuchinsky application, Serial No. 304,344. The triodes in the present invention thus determine which of the tubes 80 or 81 shall be the master tube and which tube shall be the slave tube. Thus, it is possible by the application of oppositely varying voltages to grids 119 and 120 to select, through the operation of tubes 115' and 116, which of the counting tubes 80 or 81 is active for counting purposes at a given time. More specifically, the plate 117 of tube 115 is connected to cathode 113 of tube 80, and the plate 118 of tube 116 is.

connected to the cathode 114 of tube 81. The grids 119 and 120 of

triodes

115 and 116 are connected to the output er a bistable'state flip flop circuit by way of leads making connection with

grid terminals

141 and 142, respectively. A suitable flip flop circuit for this purpose, of conventional design, is illustrated in Fig. 2A, which also shows the connection to

grid terminals

141 and 142. The cathodes 121 and 122 of

triodes

115 and 116, respectively, are connected to ground respectively through variable 1500

ohm resistances

123 and 124. Since the grids 119 and 120 of

tubes

115 and 116 respectively are connected to an output of a flip flop means, the potential of each of the grids 119 and 120 will alternatively assume one of two potentials exclusively. More specifically, when the grid 119 of tube 115 is at its high potential, the grid 120 of tube 116 will be at its low potential and when the grid 119 of tube 115 is. atits low potential the grid-120 will be at its high potential. The potential of the plates '117 and 118 will also assume one of two potentials depending on the potential of the associated grid. For example, when the grid 119 of tube 115 is at its high value, plate 117 thereof will adopt its low potential and when the grid 119 is at its low potential, the plate 117 will assume its high potential. The potential of the plates 117 and 118 determines which of the two tubes and 81 shall be the master tube and which shall be the slave tube. For example, if there is a positive signal applied to the grid 119 of tube 115, plate 117 is consequently at its low potential. This low potential in the preferred embodiment described herein is of the order of 150 volts. Spade electrodes 82 through 91 and associated load networks are at a potential of positive 250 volts from battery source 104. These potentials are appropriate to permit operation of the tube 80, thus making it the master tube. Plate 118 of tube 116 will be at a high potential due to a low grid potential. Consequently, the cathode 114 of tube 81 will be at its high potential. Under these conditions tube 81 will have no appreciable electron current flow from its cathode to any of the spade electrodes 92 through 101 or to the anode 108, that is there will be no electron beam which can be advanced for counting purposes and the tube therefore is inactive for such purposes. The low potential and the high potential which represent the outputs of the flip flop circuit (Fig. 2A) which are applied to grids 119 and 120 of tubes and 116 respectively are a negative 25 volts and ground potential. In the circuit of Fig. 2A these potentials are obtained from the plate circuits of tubes supplied with positively grounded plate battery.

' Referring now to Figs. 1 and 3 the operation of the structure shown in Fig. 1 will be described by reference to Fig. 3 which schematically shows the beam switching tube and associated circuitry. In general, each time a negative pulse is applied to the anode 61 the electron beam is caused to step from one pocket to an adjacent pocket. When the power is first applied to the tube a zeroizing negative pulse applied to terminal 62 will cause spade electrode 50 to assume the approximate potential of its cathode. If this input pulse is a few volts negative with respect to the potential of the cathode 60, the electron beam will flow to the spade electrode 50 since the path of said electron beam will follow an equipotential line. Once the electron beam impinges upon spade 50 it locks in through resistance 63 and the path of the electron beam tends to switch or move in a clockwise direction (assuming the magnetic field to have the appropriate polarity) and only a small portion thereof continues to impinge upon spade electrode. The remainder of the electron beam impinges upon that portion of the anode 61 between spade electrode 50 and spade electrode 51. The negative input pulse upon terminal 62 can be removed and the electron beam will continue to impinge upon the said portions of the anode 61 and spade electrode 50 since the electron beam current flowing through resistance 63 maintains the potential of spade 50 at a sufficiently low value as to maintain a substantially equipotential line. Thus, upon initial operation of the tube, the electron beam can be caused to always flow to the same position. In effect, a negative pulse applied upon input lead 62 has the result of zeroizing the tube to zero position. I

Input pulses to be counted are applied upon input terminal 64. These input pulses in the embodiment shown in Fig. 3 are of a negative potential. This negative potential which is applied upon the anode 61 of the tube establishes an equipotential line of cathode potential somewhere between spade 51 and anode 61. Assuming that the electron beam just prior to the pulse was in its zero position or being directed into the pocket between spades 50 and 51 the new equipotential line created between spade 51 and anode 61 will permit the electron beam to rotate in a clockwise direction (assuming the magnetic field to have the proper polarity) with reference to Fig. 3

until a portion of it impinges upon spade electrode 51 and the remainder impinges upon that portion of anode 61 between spade electrode 50 and spade electrode 51. As soon as the electron beam impinges upon electrode 51 it creates a current in the path which may be traced from the cathode 60 through spade electrode 51, resistance 65, conductor 66, conductor 67, conductor 68, to positive 250 volt battery source 69.

The potential drop across resistance 65 due to this current creates an equipotential line at the potential of the cathode from the cathode 60 to spade electrode 51. Inasmuch as the entire surface of the spade electrode 51 is at this low potential and since the center line of the path of the electron beam will tend to rotate in a clockwise direction with reference to Fig. 3 the greater portion of the electron beam will be caused to impinge upon that portion of the anode 61 between spade electrode 51 and spade electrode 52. A small portion of the electron beam, however, will remain impinged upon spade electrode 51 to maintain the electron beam in a locked position. Ap-

plication of another negative pulse upon the anode 61 will cause the electron beam to transfer to the pocket defined between

spade electrodes

52 and 53. By application of successive negative input pulses upon input condoctor 64 the electron beam can be caused to move successively from pocket to pocket in a clockwise direction.

The operation of the circuit shown in Fig. 2 will now be described.

To zeroize the circuit, spring arm 111 makes contact with contact 134 which places spade 82 of tube 80 and spade 92 of tube 81 at ground potential in a circuit which can be traced from ground through resistance 112, resistance 105 and in parallel paths along conductor 102 to spade 82 and conductor 103 to spade 92. Presumably, all the other spade electrodes. of tubes 80 and 81 are at a positive 250 volts potential from battery source 104. The anodes are also at a potential of 250 volts from the power supply represented by block element 130. Flip flop output signals from the bistable state flip flop circuit (Fig. 2A) are connected to grids 119 and 120 of

tubes

115 and 116 respectively so that one of the grids 119 and 120 is at ground potential and the other grid at negative volts potential. Assume that grid 119 of tube 115 is at ground potential and that grid 120 of tube 116 is at negative 25 volts potential. The plate 117 of tube 115 will be at a potential of approximately 150 volts as will be the cathode 113 of tube 80. An electron beam will then exist from cathode 113 to the pocket defined by

spade electrodes

82 and 83 and will be locked upon spade electrode 82. Since grid 120 of tube 116 is at negative 25 volts potential, no appreciable electron current exists between cathode 114 of tube 81 and any of the spade electrodes or the anodes thereof. Tube 81 is thus inactivated for counting purposes.

Contact 133 normally connects spade 82 of tube 80 and spade 92 of tube 81 to positive 250 volt source 104 through a load impedance similar to the load impedance of all the other spade electrodes of tubes 80 and 81. Additionally, contact 133 normally connects battery source 104 to ground through resistance 112. It can be seen that the closure of contact 133 causes the load characteristics of allthe spades shown in both tubes 80 and 81 to be the same. It is to be noted that the electron beam in tube 80 will continue to impinge upon spade electrode 82 after the closure of spring arm 111 with contact 134 because of the holding effect produced by the voltage drop across resistance 105 when beam current flows to spade 82.

Assume that a negative 100 volt pulse is applied to the input conductor 110 and to the anodes 107 and 108. The anode 107 is thereby caused to be at its cathode potential. In accordance with the description of the operation of Fig. 2 the electron beam will move to the adjacent pocket defined by spade electrodes 83 and 84 and, more specifically, will become locked in by virtue of its impinging upon spade electrode 83 which represents the decimal digit position of l. A second negative pulse of suitable duration applied to input conductor 110 will cause the electron beam of tube to move from the second pocket to the third pocket defined as being between spade electrodes 84 and 85. In this particular pocket the electron beam becomes locked upon spade electrode 84 by means of current flow through its associated load impedance from battery source 104. Each additional negative pulse applied to conductor will cause the electron beam to step to the next adjacent pocket. It should be noted than an individual capacitance which supplements the interelectrode capacitance of the tube at each beam position is connected in parallel with each corresponding load resistance associated with the spade electrode of the tubes 80 and 81. For example, capacitance 106 is connected in parallel with resistance 105. Thus, while the electron beam is locked in upon the associated, spade electrode 82, capacitance 106 will become charged to a potential substantially equal to the voltage drop across resistance 105. The particular plate of the capacitor 106 connected to the spade 82 will have a potential fairly close to cathode potential. Consequently, when it is desired to shift the master tube from tube 80 to tube 81, the charge on capacitor 106 will cause the electron beam of the new master tube 81 to impinge upon the corresponding spade electrode of that which the electron beam of tube 80 was locked at the time of the shift from tube 80 to tube 81. The transferring of the master role from tube 80 to tube 81 and the slave role from tube 81 to tube 80 is accomplished, as has been discussed hereinbefore, by a flip flop means not shown, the outputs of which are connected to the grids 119 and 120 of

tubes

115 and 116 respectively. It is to be noted that the transfer is effected specifically by causing the potential of cathode 113 of tube 80 to change from volts to 240 volts at the same time as the potential of cathode 114 is shifted from 240 volts to 150 volts. It should further be noted that the switching must take place faster than the spade resistance-capacitance discharge time since the position of the electron beam in the new master tube is determined by the charge on the capacitance associated with the spade electrode upon which the electron beam of the old master tube impinged just before the switching occurred.

Tube 80, now the inactive or slave tube, has no appreciable electron current from its cathode to any of its spades or to its anode, but the new active or master tube 81 has an appreciable electron current to one of its spade electrodes and to its anode. Subsequently, any pulses applied to input conductor 110 will now cause the electron beam of tube 81 to rotate in a direction opposite the direction which the electron beam of the tube 80 rotated when it was the master tube since the polarity of the magnetic field permeating the tube 81 is of opposite polarity to the field permeating the tube 80. Thus, if seven pulses have been applied by an input conductor 110 while tube 80 was the master tube, the electron beam of tube 80 would have been impinging upon spade electrode 89 which represents decimal degit "7." If at that time switching had occurred to make tube 81 the master tube, the electron beam would have impinged upon spade electrode 99 of tube 81 since the voltage across spade impedance of that spade is lowered as a result of the impingement of the electron beam of the tube 80 on spade 89. Then, if three negative pulses, for example, had been applied on input conductor 110, the electron beam of tube 81 would have moved to impinge upon spade electrode 96 which is representative of the decimal digit 4.

It can thus be seen that the device can be made to count additively or subtractively depending upon the condition of a bistable device such as a flip flop circuit. The signals on the two output leads of such a bistable circuit device. afford a means for selecting, in described manner, which of the two counting tubes is to be active and which is to be inactive for counting purposes at a given time. It can further be seen that the feature which determines which of the two tubes, when active, operates to cause an addition to the count and which subtraction therefrom depends on the sense of the change in counting value of the counting positions successively assumed by the beam as it is non-reversibly advanced from one counting position to another by the counted pulses. This assignment of counting values is arbitrary to the extent that it is not dependent on the arrangement of the elements of the counting tubes, it being necessary only that the same sequence of numerical values be assigned to the counting positions of both tubes and that the electrode groups in like-valued counting positions in the two tubes be interconnected to have common input and common output circuit means, as described. Output signals may be taken either from the spade electrodes directly or preferably from collector targets such as those of the tube of Fig. 1 since switching stability is thereby not affected appreciably and coded output signals may be directly afforded if desired.

It is to be noted that the inventions herein shown and described are but preferred embodiments of the same and that various changes and alterations may be made incomponent values, arrangements and other circuit parameters without departing from the spirit or scope of the invention.

We claim:

1. Bidirectional counting apparatus comprising first electronic counting means and second electronic counting means, said first and second counting means being adapted to be selectively and alternately master and slave counting means, signal input means and output means common to said first and second counting means, switching means adapted to selectively cause one of said first and second counting means to be operated as a master counting means and the other of said first and second counting means to be operated as the slave counting means, one of said counting means being adapted to count in an additive direction and the other of said counting means adapted to count in a subtractive direction.

2. Bidirectional counting apparatus in accordance with claim 1 in which each of said first counting means and said second counting means comprises an hermetically sealed envelope, a cathode secured within said envelope, an anode like beam advancement electrode secured within said envelope, a plurality of spade electrodes positioned within said envelope between said cathode and said beam advancement electrode, said plurality of spade electrodes being arranged to form a row of spaced spade electrodes each substantially equidistant from said anode, means to accelerate an electron beam from said cathode toward said anode, a second means to vary the potential of said anode, and a third means to create a magnetic field substantially parallel with each of said electrodes, each individual spade electrode of said first counting means being electrically coupled to an individual one of said spade electrodes of said second counting means, and a plurality of impedance means each individually connected to individual pairs of said connected spade electrodes.

3. Bidirectional counting apparatus in accordance with claim 1 in which said first counting means and said second counting means each comprises an hermetically sealed envelope, electron emission means secured within said envelope, anode means secured within said envelope, a plurality of electrodes spaced substantially uniformly apart in a row between said cathode and said anode means, first means to accelerate said electron emission toward said anode means, means to create a magnetic field substantially perpendicular to said row of electrodes and substantially perpendicular to the direction of the initial acceleration of said electron emission, a plurality of collector electrodes positioned behind said anode with respect to'said cathode, said plurality of collector electrodes being substantially parallel with each other and substantially equidistant from said anode, said anode having a plurality of coded columns of apertures therein, each column of coded apertures being positioned in a space between a pair of adjacent electrodes, said plurality of collector electrodes being adapted to'individually intercept electron emission passing through each of said coded apertures in any preselected one of said columns of apertures, each of said plurality of electrodes of said first counting means being individually connected to one each of said plurality of electrodes of said second counting means, and a plurality of impedance means individually connected with one each of said pairs of connected spade electrodes.

4. Bidirectional counting apparatus in accordance with claim 1 in which each of said first counting means and said second counting means comprises an hermetically sealed envelope, an elongated cathode secured within said envelope, a beam advancement control anode secured within said envelope, a plurality of spade electrodes positioned within said envelope between said cathode and said anode, said plurality of spade electrodes being arranged to form a row of spaced spade electrodes each substantially equidistant from said anode, a first means to accelerate an electron beam from said cathode toward said anode, a second means to vary the potential of said anode, and a third means to create a magnetic field substantially parallel With said elongated cathode, and in which said switching means is adapted to cause the potential of the cathode means of the master counting means to assume a potential to cause the electron beam to be accelerated from said cathode of said master counting means to the anode of said master counting means and adapted to cause the potential of the slave counting means to assume a potential to disable the electron beam from being accelerated from the cathode of said slave counting means towards the anode of said slave counting means, each of said plurality of spade electrodes of said first counting means being individually connected to one each of said plurality of spade electrodes of said second counting means, and a plurality of impedance means individually connected with one each of said pairs of connected spade electrodes.

5. Bidirectional counting apparatus comprising a first counting means and a second counting means, each of said first and second counting means comprising a plurality of electrodes adapted to indicate the count position of said first and second counting means, an input means common to both said first and second counting means, switching means adapted to cause a selected one of said first and second counting means to be the master counting means and adapted to cause the other of said first and second counting means to be the slave counting means, one of said counting means being adapted to count in an additive direction and the other of said counting means being adapted to count in a subtractive direction, and a plurality of impedance means each individually common to a pair of said electrodes of said first and second counting means, each of said electrodes of each of said pairs of electrodes representative of corresponding count positions of said first and second counting means.

6. Bidirectional counting apparatus in accordance with claim 5 in which said first counting means and said second counting means each comprises an hermetically sealed envelope, a cathode secured within said envelope, anode means secured within said envelope, said plurality of electrodes spaced uniformly apart between said cathode and said anode means, said plurality of electrodes further being spaced substantially equidistant from said anode, potential means to accelerate electron emission from said cathode, magnetic means adapted to cause said electron emission to follow a path along an equipotential line substantially equidistant from said plurality of electrodes, said common input means including means to apply *negative signal voltage pulses upon said anode means to cause said electron beam to step from one of said plurality of electrodes to another of said plurality of electrodes, said plurality of impedance means includ ing a plurality of resistive means adapted to cause the potential of said spade electrode to decrease when receiving a portion of the electron emission, a plurality of columns of coded apertures in said anode, and a plurality of collector electrodes adapted to intercept the electrons flowing through said apertures, each of said collector electrodes being positioned so as to intercept only the electron flow through one aperture of each of the columns of apertures.

7. Bidirectional counting apparatus in accordance with claim in which said first counting means and said second counting means each comprises an hermetically sealed envelope, cathode means secured within said envelope, anode means secured within said envelope, means adapted to cause said electron beam to follow an equipotential line partially determined by said anode means, said plurality of electrodes being uniformly spaced and positioned between said cathode means and said anode means so as to be substantially equidistant from said anode, said plurality of impedance means being adapted to cause the potential of said plurality of electrodes to decrease when said electron beam impinges thereon, means to impress negative pulses upon said anode means, a plurality of columns of apertures in said anode, each of said columns of apertures being individually positioned in juxtaposition with the spaces between adjacent electrodes of said plurality of electrodes, each of said columns of apertures defining a code symbol, and a plurality of collector ring electrodes positioned behind said anode means with respect to said cathode in such a position that electron emission passing through any given aperture in any given column of apertures will be intercepted by only one particular collector ring.

8. Bidirectional counting apparatus comprising first counting means and second counting means, each of said first and second counting means comprising a plurality of count indicating electrode means, a plurality of output circuits individually common to a pair of said electrode means, each of said pairs of electrode means comprising an electrode of each of said first and second counting means and having corresponding count positions, switching means adapted to selectively-control which one of said counting means will operate at a given moment count signal means common to said first and second counting means, one of said counting means being adapted to countin an additive direction and the other of said counting means being adapted to count in a subtractive direction.

9. In combination, two multi-position electron discharge devices each having crossed electric and magnetic fields for forming and propelling an electron beam along any one of a plurality of discrete selectable beam paths defining the diiterent beam positions, the magnetic fields of the two devices being of opposite polarity, each of said beam positions being adjacent to an output electrode whereby the electron beam impinges on individual ones thereof as the beam advances, output electrodes associated with corresponding beam positions in each tube being coupled together and having a common output impedance, each of said tubes having a beam advancement control electrode, signal input means common to both beam advancement control electrodes, and switching means for determining which of said devices will be operative during a given time interval.

10. The combination defined in claim 9, wherein said output electrodes are arranged coaxially around a cathode and wherein the polarity of the magnetic fields of the two devices are established to cause rotation of the electron beam about their respective axes in opposite directions.

11. In combination, two multi-position electron discharge devices each utilizing crossed electric and magnetic fields for forming and propelling an electron beam along any one of a plurality of discrete selectable beam paths defining the difierent beam positions, the magnetic fields of the two devices being of opposite polarity, each of said beam positions being adjacent to an output electrode whereby the electron beam impinges on individual ones thereof as the beam advances, output electrodes associated with corresponding beam positions in each tube being connected together and having a common output impedance, each of said tubes having a beam advancement control electrode, signal input means common to both beam advancement control electrodes, and electronic switching means for selectively determining which of said devices will be operative during a given time interval.

12. In combination, two multi-position electron discharge devices each utilizing crossed electric and fixed magnetic fields for forming and propelling an electron beam along any one of a plurality of discrete selectable beam paths defining the different beam positions, the magnetic fields ot' the two devices being of opposite polarity, each, of said beam positions being adjacent to an output electrode whereby the electron beam impinges on individual ones thereof as the beam advances, output electrodes associated with corresponding beam positions in each being connected together and having a common output impedance, each of said tubes having a beam advancement control electrode, signal input means common to both beam advancement control electrodes, and electronic switching means for selectively determining which of said devices will be operative during a given time interval, the common output impedances being chosen to present characteristics providing a time constant such that the initial position to which the electron beam will form in one tube as it is made operative corresponds to the position of the electron beam in the tube which was previously made operative by the bistable electronic switching means.

13. Bi-directional pulse counting apparatus comprising, in combination, a pair of similar electron discharge devices for forming and successively displacing an electron beam through a sequence of counting positions in response to the interaction of crossed electric and magnetic fields, the counting values assigned successive counting positions forming the same sequence of numbers in both devices; each of said devices having within an evacuated envelope a central elongated emissive cathode, a plurality of spaced-apart spade electrodes encircling said cathode equal in number to and respectively positionally associated with said counting positions, at least a portion of the current of a formed beam when in a counting position being received by the associated spade electrode, and electrostatically controlled means having a portion thereof adjacent each of said spade electrodes effective when suitably energized to cause non-reversible advancement of a formed beam from one counting position to the next such position and thereby produce counting changes in a constant and predetermined sense; means producing an electrostatic field between said cathode and said spade electrodes and producing a magnetic field normal thereto and parallel to said cathode for beam forming purposes; beam current responsive means individual to the circuits of said spade electrodes for locking a formed beam in a counting position; means for causing one, only, of said devices to be active for counting purposes at a time and for selecting the active device; output means operatively associated with both devices for materializing the value of the count at a given time in response to beam current of the then active device and means for simultaneously applying to said beam advancement means of both devices a sequence of pulses to be counted, each adapted to cause the beam in the active device to advance one counting position, the change in value of the counting positionsof the two devices relative to the respective directions of advancement of a formed beam therein being such that advancement of the beam in one device, when active, causes an addition to the count and advancement of the beam in the other device when active, causes a subtraction from the count.

14. A bi-directional pulse counting circuit comprising a pair of similar electron discharge devices for forming and successively displacing an electron beam through a sequence of counting positions in response to the interaction of crossed electric and magnetic fields, the counting values assigned successive counting positions forming the same sequence of numbers in both devices; each of said devices including magnetic means and electrode means for forming a beam at a counting position and further including pulse responsive means for advancing the beam one counting position at a time in a given predetermined direction along said sequence of positions, the change in counting value of the counting positions in one of said devices being in an additive direction as the beam therein moves in its said given direction while the change in counting value of the counting positions of the other device being in a subtractive direction as the beam therein moves in its said given direction; means causing one, only, of said devices to be active for counting purposes at a time and for selecting the active device; output means openatively associated with both said devices for materializing the value of the count at a given time in response to beam current of the then active device, and means for simultaneously applying to said beam advancement means of both devices a sequence of pulses to be counted, the sense of change in counting position value with advancement of the beam in the active device determining the direction, additive or subtractive, in which said pulses are counted by the apparatus.

15. A bi-directional pulse counting circuit comprising a pair of similar electron discharge devices for forming and successively displacing an electron beam through a sequence of counting positions in response to the interaction of crossed electric and magnetic fields, the counting values. assigned successive counting positions forming the same sequence of numbers in both devices; means for selectively activating one of said devices and simultaneously deactivating the other, and means for advancing the beam in the active device one counting position at a time in pre-determined direction through said sequence of positions responsive to the individual pulses of a sequence of pulses applied simultaneously to both devices, said predetermined direction of advancement of the beam in the active device relative to change in counting position value causing additive counting by one device and subtractive counting by the other device.

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