US2857550A - Variable counter circuit - Google Patents

Description

Oct. 21, 1958 R. A. com

VARIABLE COUNTER CIRCUIT 2 Sheets-Sheet Filed Feb. 29, 1956 COUNT OUT EVERY 11m PULSE ON SPADE S3 ON SPADE $0 INVENTOR.

RUDOLPH A. COLA ATTORNEY Oct. 21, 1958 2,857,550

R. A. ,COLA

VARIABLE COUNTER CIRCUIT Filed Feb. 29. 1956 l: a I, R o v l; a T 47 45 Fig.5 5 My 3 H6) 9 89 Se 57 S6 S5 S4 S3 52 S] 'S o 5 T8 [XE S/\ S 4 3 2 l o g f r y (fl r X f S 35 35 35 35 35 35 35 35 35 35 RI Y R; R| R| R R2 R R2 Fag R R; R2 RT RT RT RT RT CA M .JQ 1 I Fig. 6 INVEIIVTOR.

RUDOLPH A. COLA BY 6km Tfiw ATTORNEY 2 Sheets- Sheet 2' x United States Patent VARIABLE COUNTER CIRCUIT Application February 29, 1956, Serial No. 568,459 9 Claims. (Cl. 315-65) This invention relates to counter circuits and more particularly concerns a magnetron beam switching tube and circuit for providing a counter capable of increased speed of operation, of variable counting, and of bi-directional counting.

Devices of this general type have heretofore required elaborate control apparatus for regulating their operation. In most prior hard tube variable counters which operate with as high a vacuum as is practical to produce, the interconnections have utilized capacitive or inductive coupling devices, either alone or together, which cause serious time delays. Some devices of this character utilizing an electron beam have achieved improvements in speed of operation but require extensive and complex circuits for cleaning the beam from one position and resetting it at another position.

A11 important object of this invention is to provide an improved method for obtaining a variable count by simultaneously clearing an electron beam from one position and resetting emitted electrons into a beam on another position whenever the first position is reached in a counting sequence.

Another important object of this invention is to provide a variable counter circuit wherein one position of a beam switching tube is rendered unstable and drives another po{ sition into beam forming condition during the period when the beam dwells unstably on the one position and before the beam in that one position i cleared therefrom.

Another important object of this invention is to provide an adjustable variable counter wherein any position of a beam switching tube is adjustable to provide unstable beam-holding conditions and to drive any other particular position of the tube into beam forming conditions during the transient dwell of the beam on the unstable position.

Still another important object of this invention is to provide an improved bi-directional variable counter.

Various other objects, advantages and meritorious features of the invention will become more fully apparent from the following specification, appended claims and accompanying drawings wherein:

Fig. 1 is a schematic view of a magnetron beam switching tube;

Fig. 2 is a current and characteristics;

Fig. 3 is a schematic diagram of a magnetron beam switching tube and associated counter circuitry;

Fig. 4 is a voltage-time plot of potentials on electrodes of a magnetron beam switching tube;

Fig. 5 is a schematic diagram of an for a variable counter; and

Fig. 6 is a schematic diagram of a bi-directional counter.

As shown in Fig. l, the magnetron beam switching tube 30 is a multiposition beam tube of the type shown and described in U. S. Patent No. 2,721,955 to Sin-pih Fan et al. This tube 30 comprises an evacuated and sealed envelope, an elongated cylindrical cathode 32 around which are disposed coaxial and concentric arrays of elecvoltage plot of spade electrode adjustment circuit trodes. The array nearest the cathode comprises a plurality of trough shaped elements 33 with their convex surfaces facing the cathode 32. Elements 33 are commonly known as spades. Surrounding the first array is a second array of collector electrodes 34, commonly called targets. Each target 34 has a portion thereof aligned to cover the space between adjacent spades 33 and a short extension at one edge of this aligned portion which extension extends toward the concave surface of a spade. A third array of switching electrodes or grids 35 is positioned between the spades and the targets. Each grid 35 is aligned with an extending side portion of a spade 33 and near to the edge of target 34 which is opposite to the short extension of the target.

A magnetic field represented by the head-on view of arrow head H permeates tube 36, with its flux flowing substantially parallel to the cathode and toward the observer of Fig. l. The strength of field H is adjusted to about two or three times the magnetron cut-ofl value, for

about volts on the spades 33 relative to cathode 32.

of the spade electrodes and produces the IR drop which holds the beam stably in that position.

However, a negative voltage applied to the grid 35, which is nearest the target 34 which is taking the beam current, causes the beam to fan out toward that grid 35 until it strikes the next spade 33 as well. This current produces a voltage drop in this next spade which causes the beam to switch to the next target. This switching can be continued by lowering the potential of the grid 35 which is in the same interspade space as is the beam, drawing the beam over to the next spade and thence to the next target. Similar voltage variation on grids other than the one near the electron beam do not cause this switching until the beam is in the same inter-spade space. The

beam switches from one tar et to the next within a small ,7

, tential. Witha proper sequence of switching potentials on sequential grids 35, the electron beam advances clockwise around tube 30, energizing each target 34 in succession.

When the tube 30 is turned on, magnetic field H will keep the tube beam cut oif, since the field H exceeds the field needed for magnetron type cut-ofi, with supply volt age +E applied. However, one of spades 33 can be lowered from +E to ground potential by closing switch 37. This change upsets the voltage gradients in the tube and electrons form a beam which grazes the spade 33 which has a lowered potential and strikes the target 34 adjacent to the spade in the clockwise direction. As soon as part of the beam current fiows to this spade, the resulting IR voltage drop in resistor 36 will hold the spades voltage down and keep the beam stably in position after switch 37 is opened.

The beam switching action of grids 35 can be provided in at least two ways. With alternate grids in common connections, to provide two such circuits of alternate grids, an alternating voltage f can be applied on a center tapped or balanced circuit between these connections to switch the beam one position every half cycle. When one set of grids is driven negative so far as to cause switching, the other set of grids is driven to an equal and opposite positive voltage. This positive voltage on each next grid following each negative-driven grid will preventswitching the above described spadecharacteristics.

lowing half" cycle, the next switching step occurs because voltage polarities reverse every half cycle. In place of a push-pull drive to the switching grids 35,, all grids can be in one common connection 3% and driven by negative going pulses 39 which are controlled tube of" switching level for only long enough for-a single switching step to occur; after which the grids-are brought-'back'to a bias voltage to leave the beam stably in position until thenext pulse-39 -is-applied= Resistors 106 'must have aload line which must be below the load lines for'both R and-R as shown for 'Be onFig; 2, in order to hold the beamstably. Characteristiccurve 44) 'i's-fora spade when the beam isswitchingoven to. that spade, from a previous counter clockwise position, and existsonly so long as the preceding spade remains at its depressed potential: The spade which has been holding the beam is called the j. spade, and the spade to which the beam is switching: is called thei l-l spade. Accordingly curve 40 is calledthe j+l characteristic and 'curve- 41 is called the characteristic. 'I hiscur-ve 40 is not a stable beam-position, but collapses toc urve- 41 as the potential of the preceding spade rises due: to loss of its portionof the beam current, and as the beam strikesthe next target and grazes' the-next or jJ-hl spade. Accordingly, any value of spade resistor 106 ;lower in ohmic'value than R will presenta sloped line: on Fig. 2 with a slope which is greater than-that for and will not-cause enough IR- dropon the associated spadeto holdthe'beam stably. A value of resistance between R and'R will hold the beam only momentarily until the preceding or j+l spades characteristic collapses-from 40 to'41, as-the beam switches. Resistance values lower than R are wholly unsuitable for spade resistors.

Fig. 3, shows a variable counter circuit which-utilizes The magnetrn ;beam switching tube 30-of this circuit has its electrodes displaced linearly in a line'but may be coaxially arranged as in -Fig.' l. Switches 45 and are provided to change connections for various beam positions and thus to vary the count for tube 30.- Switch 45 reconnects target 34 from load resistor R to thelead connecting to the junction of resistors R1 and R Switch 46- shunts spade resistor R with additional resistor R 7'5)" iS connected by switch 45 backto the junction of R' and R and spade S is connected by switch 46 to a sistance which: is toolow in ohmic value to hold the beam stably-once-the'preceding spade returns to supply voltage Vg. Switching grids 35 areconnected to a balancedi circuit with bias +V, from center-tap to ground.

The beam is initially held by spade. S striking target T5. As th'e beam is advanced by voltages on switching grids-.35; itreaches. spade S and target T Target cureaaniplegiven this isthree pulses. By properselection off-the spadertarget position which is connected, as spade 'and targct-T are connected-in v3, anycount up; to the total number ofipositions. in: ,tube'jtlzcanbe obtained.

7 As shown, the switches are actuated for a c'ou'ntmf'three. Target T (which is three-targets from resistance-R' placing it in parallel with R to'giveare- When the count equals the total number of positions, no

cut-ofi=resetconnections are used. The normal cycle of beam switching brings the beam around to the reset position. This is a count for which no variable counter circuit is needed, but all lower counts require a circuit for clearing and resetting as above described.

Fig. 4 shows the voltage, variations which occur on spades S and S for the connections shown in Fig.3.

When no electron current-.strikesthese spades, their potential is V small portion strikes spade S this spade dropsinpotential by the amount of the IR drop, through parallel a spade resistors-R ,and; R' havinga resistance-K' i. e., I XR The beam is held on this position for only a short interval oftime. As soon as the preceding spade returns to voltage V this IR drop is not enough to hold the beam and the beam cuts-01f allowing the spade S to rise in potential at a rate determinedby its RC constant, R s. C where G isthespades'capacityrto other elec trodes and toground. However; while the-beam is on spade S and target-T3, the larger target current flows through R and produces an IR voltage drop I R on spade S which is a larger 1R drop than thation- S5. When' the beam on target T cutsofi; spade S begins to riseinpotential; but a new beam forms onspade Sfi'be fore its potential can rise beyond beam-forming l'evel;

which must be charged-imthe sum' of aspade andta=tar5 getscapacity, C plusC the RC time constant for spade S is longer thanthat for--spade'-S soa beam resetting action on spade S 'is assured due to an adequatelower potential remaining on spade-S after the beamis'cut'otf L of target-T The simultaneous occurrence of beajrnclean' ing and beam-resettin g, limited only in a slight manner by the time constant ofresistorR- and-spadecapacity-"Gf -in thelowering of-the potential on spadeS, insures speed and highly reliable operation.

Th'e'switches 45 and46of Fig. 3 provide the'proper connections for stable beam-holding and=transfer when 7 in one of theirpositions and for'beam clearing-and re 7 setting when.in-the other position; 7 From inspection,;it can b'e'seen that this requires a large number-of 'double pole, double-throw switches to provide a full-range 'of variable counting. Fig." 5 showsa multi-positioir switch which provides the required reconnections' for" various countswhich can'be selected. One switch member- 47 connects to the selected counts target, which} in Fi'gfs istarget-Tgfor acount 11:4." Bridging member-493s disconnected" from target T andits; associated resistor: R Anotherswitch member 48 connectsregistor Ry to the resistor R5; for the particular spade 33' which i540 be rendered unstable... Movement of the switch to,

various; positions accomplished theabove reconnections for whatever positionis selected. .The-resistor's shown as R and R could be lumped and placedin-the circuit byz'target'current fronrtherselected target; Spades-which:

are'ini'ore; than two positions removed from spaderSs quickly I collapse from -.char.acteristic- 40 to: characteristic 4Lbecause the preceding. spade rises-cquickly in:its?po'= tential. whenathe beam: advances. from: it; However;.

where the resistors R are shown. The important factor is that the ohmic value of R and R plus R in parallel be-equal to'the resistance;:R" needed to'make each-particular positions spade unstable for beamholding-after the preceding-or j spade returnsto'voltage V There is a variation of the ohmic valu'eneeded for R" ';d'e pending. on the position of the selected spade withzrespect to spade S This variation=arises from: the dependenceof thetransient spadecharacteristicv lil, shown in Fig. 2, upon the voltage of the preceding spade.- What ever the count-that i's'used, spade S -is the spade which is-rloweredin potentialby theIRdrop throughsR-g. caused When the beam is switched to where a.

s'pades within two positions of spade S do not collapse their characteristic as rapidly, due to the proximity of spade S which does not rise in potential. A lower value load resistance is required for spades near spade S to facilitate beam cut-oil in those positions.

Fig. 6 shows a .bi-directional counter. Only the odd numbered positions 1, 3, 5, 7 and 9 are provided with spade resistors R and R and target resistor R for stable beam holding. Even positions 0, 2, 4, 6 and 8 are unstable positions in that resistors R" are too low in ohmic value to enable the associated spade to hold the beam stably, so the beam is cleared. Targets of even positions are connected to spade electrodes of odd positions to reset a new beam on the particular odd position to which a particular even target is connected. With multiple-pole, double-throw switch 50 connected as shown, switching pulses will advance the beam to the left in Fig. 6 which is clockwise in the circular configuration shown in Fig. l.

Assume the beam is on target T and the next switching pulse moves the beam to target T connected to a resistor R" and accordingly is unstable for beam holding. Target T connects to resistors R and R for spade S Target current lowers the potential of spade S so the beam is reset to target T The practical sequence is a rapid beam switch from target T to target T when a switching pulse was applied. For this circuit, switching grids 35 are in a single common circuit and pulses of controlled short duration are applied to all gridssimultaneously. With this connection of switching grids 35, the next pulse will switch the beam from target T to T to cutoff, while a reset of the beam to target T occurs. In this manner the beam moves to positions 1, 3, 5, 7 and 9 in sequence.

With switch 50 thrown to the presently dotted position of Fig. 6, beam movement will be to the right or counter-clockwise in the circular configuration shown in Fig. 1. With the beam on target T the next switching pulse moves the beam to target T and to cut-off as described. However, target T connects to R and R for spade S to where a beam is reset on target T The next switching pulse moves the beam to target T and cut-oil, while target current from target T lowers the potential of spade S and causes a beam to reset on target T The sequence thus is 1, 9, 7, 5, 3, 1, etc, when switch 50 is connected to dotted position.

There is thus provided a variable counter providing for high speed and highly reliable operation at any count within the beam switching tubes maximum count capability, which can provide for bi-directional counting sequence.

What is claimed is:

1. A variable counter comprising a magnetron beam switching tube having a plurality of positions each including a beam forming and holding electrode, a switching grid and a target electrode, first resistance means for connecting said beam forming and holding electrodes to a voltage supply, second resistance means for connecting said target electrodes to a voltage supply, first circuit switching means connecting a selected target electrode to said first resistance means where connected to a particular beam forming and holding electrode, and second circuit switching means connecting a selected beam forming and holding electrode associated with said selected target electrode to said first resistance means to provide a lower resistance connection thereto than is provided by said first resistance means to all other beam forming and holding electrodes.

2. A variable counter comprising a magnetron beam switching tube having a cathode, a. plurality of spade electrodes of switching grid electrodes and of target electrodes with said electrodes associated in groups of one of each type to provide beam holding positions therein, first resistance means having a plurality of Spade S is 6 branches connected 'to said spade electrodes, second resistance means connected to said target electrodes, and a multiposition multipole connecting means having a first pole connected to said first resistance means .where connected to a particular spade electrode and connectable to said target electrodes in single sequence, a circuit interrupting means disconnecting said target electrodes from said second resistance means in the same single sequence and a secondpole connectable to branches-of said first resistance means particular to each spade elec trade in the same single sequence to provide a parallel path in said first resistance means. i

3. A variable counter comprising a magnetron beam switching tube having a plurality of beam holding positions with each positionincluding a spade electrode, a

switching grid electrode and a target electrode tune tionally associated'together, resistance means having a plurality of conductive paths and separately connected to said spade electrodes and to said target electrodes, first switching means connecting said target electrodes i in single sequence to said resistance means where connected to a particular spade electrode, and secondswitching means connecting at'least two conductive paths of said resistance means in parallel circuit to said .spade elec trodes in the same single sequence;

4. A variable counteras in claim 3, wherein said first switching means .includes a. disconnecting means .to break in thersame single sequence. the 'separate connece tions of said target electrodes to said resistance means.

5. A variable counter comprising a magnetron beam switching tube having a plurality of electron beam holding positions each including an electron beam forming and holding electrode, a beam switching electrode, and a target electrode, a plurality of first resistors connected one to each of said beam forming and holding electrodes and adapted to be connected to a common voltage supply, a plurality of second resistors provided for connection one each in parallel with each of said first resistors and means for making and breaking said last named parallel connection, a plurality of third resistors connected to each of said target electrodes and adapted to be connected to a common voltage supply, means for connecting each of said target electrodes to by-pass its third resistor, means connected to one of said beam forming electrodes for automatically lowering-the electrical potential thereon when electron flow to said target electrodes is interrupted, and switching means connected to the target electrodes at said odd-numbered positions for switch-- ing to ditferent beam holding electrodes for directing an electron beam in one direction or in the opposite direction in said tube.

6. A variable counter comprising a magnetron beam switching tube having a plurality of odd and even-numrenders said electrodes unable to hold an electron beam 7 in the even-numbered positions, second resistance means connected to each beam holding electrode of the oddnumber'ed positions and having sulficient resistance to render said electrodes capable of holding an electron beam in position, third resistance means connected to each of the target electrodes at an odd-numbered position and adapted to be coupled to a voltage supply, and switching means for connecting the target electrodes at even-numbered positions either to the resistance means switching tube having a plurality of odd and even-unnu- :beamfin .pdsitionuthind resistance means connected to each of the target electmdes att anz odd-numberfidPOS iQH land; adaptedrrto -be eouplndr o;a. v a ensupp yl ,and

.switchiiiglrmeansz ccnneeted;;tg said targetelectrodes, at

thee oddammberpdaspgsitions;f x co p n s id l nngs zmultbp it ne --tron mhe-hav nga plu ality i b am holding p icns:;wi h-.cach sp si iqn; nc ud g r e electrode adapted; tbli eceive an 1stron; eam,. pa electrode adapted-t0 form; and; hold v anyelectron' beam on its asso- V ciate di target' electrode,rand a switching electrode adapted to switch an electrontbeami from; one positionto the next;

*aVaiiabIeresistai'icemeans coupled to 'each spade electrode and having 'a-range ofi resistance values sucht that each-spade may beioperated in both stable and unstable fla l e m in heiuns ab e c ndit cn conditi ns; eac i pade be ng abl eholiiank elm-.011

minh s a lea ondi i niapd unable tqholdiamlfict ime nsi ciapled ach; arget l c tode fan selec iv ly; i quplingz any: 11a;- get electrode o s ele t d sp de lectrode scrthaitzanielertron bea g mayethereby be resetfrom;an;unstab1e spade t i lect d: spa e- V .9- A v riab e' cnnt nc pri mg, m l isp i i nclec I i ons e m u ghav ngap m lity of beamholdingsn tions; with; each pqsitign including; a target, electrgde adapted te receive an elect on beam a spade electrode adapted to fgrm andholsiqantelcctronbeam on its. associated' target; electrode, an d aswitching electrode adapted tqtswi tchanelectronbeamfr m on n sitn 9": n

a resistanceemeans cqnnectedr (:9 each spade.- electrode and of sufficient magnitude to gender each spade stable in operation; m ea ns adagtedic be cqugl edgtqeach sgade. to render each spade unstable; in ope r'atiqn a nd unable; to

forth and held an electron beam; andme ans-fcqugledt to 7 each target electrode for selectively coupling any target electrode tc a selectedispade electrode so that an electron beam may thereby be resetffrcm an unstable. spade to said. selectedTsbade.

Refeifencies Citedinthefile bf thispate'iit UNITE STAT-ES PATENTS 25633801 ,A1fven Aug. 14,1951 7 2591-9 97. Backmark- Apr. 1952

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