US3016473A

US3016473A - Counting circuits

Info

Publication number: US3016473A
Application number: US816815A
Authority: US
Inventors: Jr John Cullis
Original assignee: Burroughs Corp
Current assignee: Unisys Corp
Priority date: 1959-05-29
Filing date: 1959-05-29
Publication date: 1962-01-09
Anticipated expiration: 1979-01-09

Description

Jan. 9, 1962 J, CULUS, JR 3,016,473

COUNTING CIRCUITS Filed May 29, 1959 INPUT dl INVENTOR.

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United States Patent O 3,016,473 COUNTING CIRCUITS .lohn Cullis, Jr., PlainiieldN.J., assigner to Burroughs Corporation, Detroit, Mich., a corporation of Michigan Filed May 29, 1959, Ser. No. 816,815 Claims. .(Cl. S15-8.5)

This invention relates to counting circuits and particularly to counting circuits employing multi-position counting tubes.

One type of multi-position counting tube is known as a magnetron beam switching tube and includes a plurality of groups of electrodes, at each of which an electron beam may be formed and from each of which an output signal may be obtained. Generally, in using such a tube in a counting circuit, after a predetermined counting operation has been performed, the electron beam is cleared from the group of electrodes to which it is flowing and the beam is reset at a predetermined zero position, which represents the starting point for the next counting cycle. Many circuits are known for clearing and resetting lan electron beam in a beam switching tube, and, while these circuits are generally satisfactory, each has a specific utility and kmay not be universally applicable. The present invention is particularly concerned with zero-setting an electron beam where simplicity and economy are desirable and high speed of operation is not a primary requirement.

In addition, a problem arises in multiple stage counters using a magnetron beam switching tube for each stage. Genreally, the O or rest position of each tube is also the position from which a carry pulse is transmitted from one tube to the next tube in the count-ing chain. Thus, when a tube is reset and the beam forms in the zero position, the usual output carry pulse also appears. However, he generation of this carry pulse is an undesirable Aadjunct to the reset operation, and its effect must be counteracted in some manner.

Accordingly, the purposes and objects of the invention are concerned with the provision of a novel beam clearing and zero-setting circuit for use with a multiple output electron beam switching tube, the circuit being characterized by its comparative simplicity and eiliciency combined with a satisfactory speed of operation.

The objects of the invention are also concerned with the provision of an improvedY counting circuit using magnetron beam switching tubes and havingrimproved means for clearing and resetting an electron beam and for counteracting the eiect of a carry pulse generated during the resetting operation. t

In brief, the circuit of the invention employed with a magnetron beam switching tube, for example a Type 6700 tube, includes means for arbitrarily selecting one t of the tube positions or groups of electrodes as the zero position which represents the starting position in a counting cycle. Resetting circuit means are provided coupled to the tube position which is adjacent to, and lagging, the zero position for for-ming a-beam at said lagging position. Means are also provided coupled to the switching elec- ICC FIG. 2 is a schematic representation of the tube 'of FIG. 1 and a circuit embodying the invention; and

FIG. 3 is a schematic representation of a multiple stage counter embodying the invention.

The circuits described below are particularly suitable for use with a multi-position .electron beam tube such' as the Type 6700 magnetron beam :switching tube.` This type of tube is shown in FIG; 1 as'tube `10` vand includes, brielly, an envelope 12 which contains a centrallongitudinally elongated cathode 14 and ten groups'of'electrodes spaced radially equidistantlyfrorn the cathode'iand surrounding the cathode. Each group of electrodes includes a generally U-shaped elongated spade electrode 16 and a generally L-shaped target electrode 18 positioned so that each target occupies the space between adjacent spade electrodes. Each spade electrode serves to form and hold an electro-n beam on its corresponding target electrode. A generally rod-like switching electrode 20 is also included in each group of electrodes and'is positioned between one edge of each target electrode and the adjacent spade electrode. The switching electrodes are known as switching grids. An open-ended cylindrical permanent magnet 22 is provided Surrounding the tube envelope land coaxial therewith. The magnet' provides an axial lmagnetic field which is utilized in conjunction with electric -iields Within the tube to form and switch an electron beam from the cathode to each of the groups of electrodes. The direction in which the beam switches, that is clockwise or counterclockwise, is always the same and is determined by the orientation of the electric and magnetic fields.

Briefly, in operation of tube 10, electrons emitted by the cathode are retained at the catohde if each of 4the spades, targets and switching grids carries its normal operating electrical potential. When a spade or switching grid experiences `a suitable lowering of its potential, an electron beam is formed and directed to the corresponding target electrode. The electron beam may be switched from one target electrode to the next by thus suitably altering the electrical potentials of a spade or switching grid. Under normal operating conditions, whenever electrode voltages are such that a beam might be supported at sever-a1 positions, the beam will switch to the most leading position and lock in at this position.

In the circuit of FIG. 2, the tube 10 is -shown in schematic, linear form with only tive positions or groups of electrodes shown and numbered 0, 1, 2-. 8, 9, with the 0 group representi-ng the first position in a counting cycle and group 9 representing the last position. In the circuit, the cathode 14 is connected through a suitable resistor 24 to ground. The cathode is'also coupled through a capacitor 26 to a source 28 of positive pulses 30 which are used to clear an electron beam from any position in the tube. Each of the spade electrodes 16is coupled through a spade load resistor 32 to a spade buss 34, which is coupled through a common trode at the lagging position for simultaneously causing van electron beam to switch to the predetermined zero position as soon as it begins to form at the lagging position. When the beam switches to and sets at the zero position, a'carry pulse is generated, the effect o-f which is counteracted by the overwhelming inuence of theresetting means. f

The invention is described in greater detail by reference to the drawing wherein: A

FIG. l is a perspective view, partly in section, of an electron tube used in practicing the invention;

spade resistor 36 to a buss 38 which is connected to Aa suitable `positive D.C. power supply Vp of ,about 300 volts. According to the invention, a source 40 of negative zero-set pulses 42 is coupled through a capacitor 44 to the 9 spade, that is, the spade electrode at the 9 position. The 9 position is the position adjacent to and lagging the 0 position, which is the first-position in the counting cycle of the tube. The 0 position is the one at which it is desired to reset the electron beam.

The target electrodes 18 are connected' through suitable pairs of load resistors S0 and 52 to the buss 38 which is `coupled to the positive D.C. power supply Vp. In

addition, an auxiliary output tap 56 is provided at each target between the resistors of the pairs for connection to a utilization device or circuit, if desired. Thus, the

target electrodes may be connected, for example to the cathodes of a cathode glow indicator tube, or to ya printing mechanism or the like.

The switching grid electrodes 20 are connected in pairs, with the grids at the even-numbered positions being connected together in one set and the grids at the odd-numbered positions being connected together in another set. Each set of grids is then connected to a driver circuit to be described below so that first one and then the other set of grids is energized and, thus, the beam is caused to move from position to position in the tube.

The driver for the beam switching tube includes a bistable multivibrator 60 which is coupled to two cathode follower amplifiers at 62, one of which controls the operation of the even-numbered switching grids and the other of which controls the operation of the odd-number v switching grids. The multivibrator may be of any wellknown form and may include, for example, a iirst triode 66 including cathode 68, control grid 70, and anode 72, and a second triode 74 including a cathode 76, a control grid 7S, and an anode 80. The cathodes 68 and '76 are coupled together through a resistor 82 to ground. A capacitor 84 is provided across the resistor 82. The control grid 70 of the first triode 66 is coupled through suitable resistors 86 and 8S to ground, and the control grid 78 of the second triode 74 is connected through a resistor 90 to ground. The control grid 7) of the rst triode is connected through a parallel combination of resistor 92 and capacitor 94 to the anode 3G of the second triode. The control grid 78 of the second triode is similarly connected through a parallel combination of resistor 96 and capacitor 98 to the anode of the iirst triode. The

anodes

72 and 80 of the triodes are connected through

suitable load resistors

100 and 102 to a common coupling capacitor 104 and then to a source 166 of negative input pulses 108. The anodes are also connected through a common resistor 110 to a suitable power source. The source 40 of negative reset pulses is coupled through a suitable capacitor 112 to the control grid of the iirst triode. 'Ihis connection may be made specifically to a point between the two resistors v86 and 88.

The cathode followers at 62 include a first triode 114 having a cathode 116, control grid 118, and an anode 120, and a second triode 122 having a cathode 124, control grid 126, and anode 128. The two

anodes

120 and 128 are connected together to a power source not illustrated. The two

control grids

118 and 126 are connected through

suitable resistors

130 and 132, respectively, to ground, `and the control grid of the rst triode is coupled through a coupling capacitor 134 having a neon voltage regulator tube 136 in parallel with it to the anode of the second triode 74 of the multivibrator. The control grid 126 of the second cathode follower triode is similarly coupled through a parallel combination of coupling capacitor 138 and a neon voltage regulator tube 140 to the anode of the rst flip-flop triode 66. The cathode 116 of the first cathode follower triode is coupled through a parallel combination of resistor 142 and capacitor 144 to ground, and it is also coupled to the set of odd-numbered switching grids of the tube 10. The cathode of the second cathode follower triode is coupled through a parallel combination of resistor 146 and capacitor 148 to ground and to the set of even-numbered switching grids of the tube 10.

In operation of the cricuit of FIG. 2, let it be assumed that the tube is counting in normal fashion and that an electron beam is being switched from position to position under the inuence of switching pulses which areapplied rst to one set of switching grids and then to the other .set of switching grids. During the switching operation, the multivibrator circuit operates in conventional fashon with lfirst one triode conducting and then the other conducting, with the first triode 66 controlling the operation of cathode follower 64 to provide switchingpulses for the set of even-numbered switching grid electrodes, and the second triode 74 controlling the operation of cathode follower 62 to provide switching pulsesfor' the set of odd-numbered switching grids.

When it is desired to clear the electron beam and reset it at the zero position, a positive pulse 30 is applied to the cathode 14 from the source 28. This pulse has an amplitude of about 250 volts and raises the potential of the cathode to such a level that a beam cannot be sustained in the tube, and it is cleared from the position at which it is formed. After the beam lhas been cleared, a negative reset pulse 42 from the source 40 is applied both to the 9 spade and to the con-trol grid 70 of the triode 66 of thelmultivibrator. This pulse 42 has an amplitude of about 250 volts and lowers the potential of the 9 spade suiiiciently so that an electron beam forms and ows to the 9 position. At the same time, the multovibrator is set so that the triode 74 is in the conductive state. When the triode 74 becames conductive, its anode Si) is reduced in potential and the control grid 118 of the cathode follower tube 114, similarly, is reduced in potential. At the same time, the cathode of the tube 114 becomes more negative, and this negative potential is applied t-o the odd-numbered gn'd electrodes, including the 9 grid. T he application of this negative potential to the 9 grid causes the electron beam which is present at the 9 position to switch immediately to the zero position and the desired reset operation is accomplished.

A multiple stage counter using the principles of the invention is shown in Iblock diagram in FIG. 3. ln the circuit, two or more beam switching tubes 15d and 152, of the type shown in FIG. l, are connected in series, with each tube being provided with essentially the same circuit elements as shown in FIG. 2. A iirst bistable multivibrator driver 154 is provided for tube 150 and has two output lines, one line 156 connected to the even-numbered switching electrodes of tube and the other line 158 connected to the `odd-numbered switching electrodes of tube 154i. The multivibrator circuit 154 is provided with an input terminal 160 by means of which input counting pulses are applied, and it is also provided with a reset terminal 162 connected as in FIG. 2.

The second beam switching tube 152, similarly, is provided with a bistable multivibrator driver 164 having two output lines166 and 168 connected to the evennumbered grids and to the odd-numbered grids thereof, respectively. The input lead 170 to the multivibrator 164 is coupled to the 0 target of the tube 150 which provides carry pulses which `act as input driving pulses therefor. The second multivibrator 164 is also provided with a reset terminal y172. The 9 spades of both

tubes

150 and 152 are `also provided with reset termin-als 174 and 176, respectively, connected as in FIG. 2. Tube 152 is also provided with an output or carry terminal 177 for transmitting carry pulses to the next stage of the counter if one is provided.

In the circuit of FIG. 3, input pulses applied to terminal 160 of the multivibrator 154 are negative pulses of about 55'volts. Reset pulses applied to .terminal'162 of multivibrator 154, terminal 172 of the multivibrator 164, and terminals 174 and 176 of the

tubes

150 and 152 are negative pulses of about 250 volts. The carry pulses from the

tubes

150 and 152 are negative pulses of about 150 volts. p

In operation of the counter circuit of FIG. 3, each input pulse to the multivibrator 154 provides an output pulse on one or the other of the output lines l.156er 15S and these output pulses applied to the switching electrodes of tube 156 cause an electron beam to switch from position to position inthe tube. When the beam in the tube 150 reaches the end of its counting cycle and passes from the 9 position to the O position, a carry pulse from the 0 vtarget is applied to the input of the second multivibrator 146 and provides anV output signal therefrom which causes an electron beam in the second beam switching tube 152 to switch by one position` AtA some time in the counting cycle when it is desired to reset one or both

tubes

150 and 152, a reset pulse is applied to both multivibrators y154 and 164 and to both 9 spade electrodes of

tubes

150 and 152. The application of the reset pulse to the 9 spade electrodes causes an electron beam to form in the positions `as described above. The formation of an electron beam in the 0 position of tube 150 provides a carry pulse which might ordinarily operate the multivibrator `164 to cause the beam in the second tube 15-2 to switch. However, the reset pulse which is applied simultaneously to the multivibrator circuits is of such magnitude, about 250 volts, that it overwhelms the pulse from the 0 target, about l() volts, which thus has no effect on the second multivibrator 164. The reset pulse is of suciently long time duration that its effect on the multivibrator exceeds that of the carry pulse. Thus, the reset operation is achieved without adverse effects from a carry pulse generated at the same time.

What is claimed is:

1. A counter circuit including a magnetron beam switching tube having a cathode and a plurality of groups of electrodes each comprising a counting position; each group of electrodes including a 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; circuit means coupled to said switching electrodes for applying pulses thereto and causing an electron beam to switch from position to position; beam resetting means coupled to one of said positions to form lan electron beam thereat, said resetting means also being coupled to said circuit means to energize the same and apply a pulse to the switching electrode at said one position to cause the electron beam to switch to the next position at substantially the same time that it begins to form at said one position.

2. A counter circuit including a magnetron beam switching tube having a cathode and a plurality of groups of electrodes each comprising -a counting position; each group of electrodes including a target electrode which receives Ian electron beam and produces an output signal therefrom, la 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; said switching electrodes being connected in two sets, one set including the odd-numbered switching electrodes and one set including the even-numbered switching electrodes; a bistable multivibrator having two output lines, one output line being connected to one set of switching electrodes and the other output line being connected to the other set of switching electrodes; beam resetting means coupled Ito one of said positions to form an electron beam thereat, said resetting means also being coupled through said multivibrator to act on the switching electrode at said one position to cause the beam to switch to the next position.

3. A counter circuit including a magnetron beam switching tube having a cathode and a plurality of groups of electrodes each comprising a counting position; each group of electrodes including a 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; said switching electrodes being connected in two sets, one set including the odd-numbered switching electrodes and one set including the even-numbered switching electrodes; a bistable multivibrator having .two output 1ines,'one output line being connected to one set of switching electrodes and the other output line being connected to the other set of switching electrodes; beam resetting means `coupled to one of said positions to form an electron ybeam thereat, said resetting means also being coupled to said multivibrator to cause said multivibrator to apply a switching pulse to the switching electrode at said one position to cause the beam to switch to the next position.

4. A counter circuit including a magnetron beam switching tube having a-cathode and a plurality of groups ofV electrodes each comprising a counting position; each group of electrodes including a ytarget 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; said switching electrodes being connected in two sets, one set including the oddnumbered switching electrodes and one set including the even-numbered switching electrodes, a bistable multivibrator having two output lines, one output line being connected through a rst cathode follower amplier to one set of switching electrodes and the other output line being connected through a second cathode follower amplifier to the other set of switching electrodes; beam resetting means coupled to one of said positions to form an electron beam thereat, said resetting means also being coupled through -said multivibrator and itscathode follower to act on the switching electrode at said one position to cause the beam to switch to the next position.

5. A counter circuit including a magnetron beam switching tube having a cathode and a plurality of groups of electrodes; each group of electrodes including a target elect-rode which receivesV 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; one position in said -tube selected to be the zero position at which an electron beam is to be formed; beam resetting means coupled to the spade electrode at the adjacent lagging position for initiating the formation of an elect-ron beam at the lagging position, -said resetting means also being coupled to the switching electrode at said lagging position so that when said resetting means is operated to form a beam at said lagging position the electron beam immediately switches from said lagging position to the selected zero position.

6. A counter circuit including a magnetron beam switching tube having -a cathode and a plurality of groups of electrodes; each group of electrodes including a 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; switching means coupled to said switching electrodes for causing an electron beam to switch from position .to position; one position in saidtube being selected to be the zero position at which an electron beam is to be formed; beam resetting means coupled to the spade electrode at the adjacent lagging position for lowering the spade potentiall thereat and thereby forming an electron beam at the lagging position; said resetting means also being coupled to said switching means for energizing the switching electrode at said lagging position so that an electron beam immediately switchesfrom said lagging position to the selected zero position.

7. A multiple stage counter including a plurality of magnetron beam switching tubes each having a cathode anda plurality of lgroups of electrodes; each group of electrodes including a 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 vof electrodes to the next; a bistable multivibrator coupled to the input-of each tube; signal carry means coupling one position of one tube to the multivibrator associated with the nexty tube; beam resetting means coupled to each tube and to each multivibrator; the effect of said beam resetting -means on said multivibrators being adapted to exceed the effect of said signal carry means thereon. f

8. A multiple stage counter including a plurality of magnetron beam switching tubes each having a cathode and a plurality of groups of electrodes; each group of electrodes including a 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 bistable multivibrator coupled to the input of each beam switching tube; signal carry means coupled between one position of one tube and the input of the multivibrator associated With the next tube and adapted to transmit a carry pulse thereto; beam resetting means coupled to each tube and to each multivibrator and adapted to apply reset pulses thereto; said reset pulses being of greater amplitude and longer time duration than said carry pulses so that said reset pulses serve to set said multivibrator in a preferred operating condition in spite of the presence of a carry pulse at the multivibrator.

9,. A counter circuit including a magnetron beam switching tube having a cathode and a plurality of groups of electrodes each comprising a counting position; each group of electrodes including a 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; means coupled to one of said positions to form an electron beam thereat; and beam-switching means. coupled to all of said switching electrodes; said beam-settingl means being coupled to and adapted to energize said beam-switching means at substantially the same time that it acts to set a beam at said one position whereby an electron beam is se at said one position and switched from said one position at substantially the same time.

10. A counter circuit including a magnetron beam switching tube having a cathode and a plurality of groups of electrodes each comprising a counting position; each group of electrodes including a 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; beam-switching means coupled to said switching electrodes and adapted to cause an electron beam to switch from position to position; and beam-setting means, coupled to one of the electrodes in one of said groups of electrodes adjacent to the position at which it is desired to set an electron beam; said beam setting means also being coupled to said beam switching means for causing it to perform its function on the switching electrode at said one position at substantialiy the same time as said beam setting means performs its function whereby a beam which tends to form at said one position is immediately switched to the next desired position.

References Cited in the le of this patent UNITED STATES PATENTS 2,807,748 Lee Sept. 24, 1957 2,839,702 Fan et al June 17, 1958 2,856,558 Cola Oct. 14, 1958 2,871,399 Scuitto Jan. 27, 1959