US3147398A - Counter circuit and driver therefor - Google Patents

Description

J. CULLIS, JR

COUNTER CIRCUIT AND DRIVER THEREFOR Filed June 22, 1960 Sept. 1, 1964 IN VEN TOR.

A 7'7'ORNE Y mw ww m i JOHN 0ULLI$,JR. 64 @1511 United States Patent 3,147,398 COUNTER CIRCUIT AND DRIVER THEREFQR John Cullis, Jr., Plainiieid, N.J., assignor to Burroughs Corporation, Detroit, Mich, a corporation of Michigan Filed June 22, 1960, Ser. No. 37,987 6 Claims. (Cl. 31584.6)

This invention relates to electronic counters and particularly to driving circuits for counters of the type using a multi-position electron beam switching tube.

The present invention is particularly useful with counting tubes of the type known as magnetron beam switching tubes, for example type 6700 tubes. This type of tube has been used in many counting circuits, and, in general, such circuits have operated well, particularly for high speed counting. However, by comparison with the present invention, these counters have been comparatively complicated. For one thing, these counter circuits used flipflops to drive the beam switching tubes, and, in some instances, the circuitry was further complicated by the inclusion of cathode follower or other circuits as part of the driving circuitry,

The principles and objects of the present invention are concerned with the provision of an improved electronic counter circuit using multiple position magnetron beam switching tubes and characterized by simplicity of circuit design and low cost.

In brief, the counter circuit of the present invention is particularly suited for use with a ten-position magnetron beam switching tube of the type including a central cathode surrounded by a plurality of groups of electrodes, each of which includes an output or target electrode which receives an electron beam and provides an output signal, a spade electrode which forms and holds an electron beam on its associated target electrode, and a switching electrode which serves to switch an electron beam from one position to the next. In the circuit, the target electrodes are connected in two sets, with the targets at the odd-numbered positions in one set and the targets at the even-numbered positions in another set. The switching electrodes are similarly connected in two sets.

A first variable resistance path is coupled between one set of target electrodes and its associated group of switching electrodes, and a second variable resistance path is similarly coupled between the other set of target and switching electrodes. Each path includes a gaseous glow tube which determines the resistance of the path by its state, that is, by whether it is on or oflf. A source of switching pulses is coupled to the two paths and each switching pulse aifects only one of the sets of switching electrodes, the set associated with the low resistance path. When a beam is switched, glow tubes change state, the paths change their relative resistance andthe tube is prepared for the next switching pulse.

The invention is described in greater detail by reference to the single figure of the drawing which is a schematic representation of a magnetron beam switching tube as used in a counter circuit embodying the invention.

The circuit described below is particularly suitable for use with a multi-position type 6700 magnetron beam switching tube. In actual construction, this type of tube is cylindrical in form and is shown schematically in linear form as tube 10 in the drawing. The tube includes an envelope 12 which contains a central longitudinally elongated cathode 14 and ten groups of electrodes spaced radially equidistantly from the cathode and surrounding the cathode. The groups of electrodes are shown numbered 0, 1, 2 9. 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 3,147,398 Patented Sept. 1, 1964 an electron beam on its corresponding target electrode. A geenrally 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 shown schematically at 22 is provided surrounding the tube envelope and coaxial therewith. The magnet provides an axial magnetic field which is utilized in conjunction with electric fields 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 cathode if each of the spades, targets and switching grids carries its normal operating electrical potential. When a spade is suitably lowered in 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 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 several positions, the beam will switch to the most leading position and lock in at this position.

For convenience, in the tube 10 as shown, the oddnumbered and even-numbered groups of electrodes are shown grouped together. In the circuit, the cathode 14 is coupled through a capacitor 24 to a source of reference potential such as ground. The switching electrodes 20 are connected in two sets, with the electrodes at the evennumbered positions in one set and the electrodes at the odd-numbered positions in the other set. The spade electrodes 16 are coupled through spade load resistors 26 to a spade buss 28 which is connected in turn through a common spade resistor 30 to a positive DC. voltage supply V of about 250 volts. Any suitable zero-set circuit is provided for setting an electron beam at the 0 position at the beginning of a counting cycle, if such is desired. One suitable zero-setting circuit comprises, for example, a switch 31 connected between the 0 spade and ground. The switch 31 is normally open, but, when closed and the tube is cleared, it causes a beam to form at the 0 position.

The target electrodes 18 are also connected in two sets, with the targets at the even-numbered positions being in one set and the targets at the odd-numbered positions being in the other set. All of the even-numbered target electrodes are coupled through load resistors 32 to a buss 34 which is coupled in turn through a resistor 36 and capacitor 38 in parallel to the positive DC. power supply V. The target electrodes at the odd-numbered positions are connected through load resistors 32' to a buss 34 which is connected through a resistor 36' and capacitor 38 in parallel to the power supply V. Each target is also provided with a terminal 40 by which it may be connected to any suitable utilization device such as a visual indicator tube, a printer, or the like.

According to the invention, means for driving the beam switching tube includes a first variable resistance path comprising a first voltage regulator tube 42 such as a neon tube having one electrode 44 connected to the target buss 34 and the other electrode 46 connected through a capacitor 47 and a resistor 48 to a buss 50. The junction point 52 of resistor 48 and capacitor 47 is coupled to the switching electrodes at the even-numbered positions. The driving means also includes a second variable resistance path comprising a neon tube 42' which has one electrode 44' connected to the target buss 34' and the second electrode 46' connected through a capacitor 47' and a resistor 48' to the buss 50. The junction point 52 of resistor 48' and capacitor 47 is coupled to the switching electrodes at the odd-numbered positions. The buss 50 is connected through a resistor 54 to ground and through a capacitor 56 to a. source 57 of negative input counting pulses which have an amplitude of about 150 volts. The glow tubes 42 and 42 vary the resistances of the first and second paths, depending on their operating state, that is, whether they are on or olf. If a glow tube is on, the path is a relatively high resistance path, and if a tube is off, the path is a relatively low resistance path.

In operation of the circuit, if power is turned on without the formation of a beam in the tube 10, the voltage applied across the neon tubes 42 and 42' is suflicient to cause both of them to be ignited and to pass current. At this time, the busses 34 and 34 carry a potential of about 235 volts, and the potential at the electrodes 46 and 46 of tubes 42 and 42' is about 175 volts. A beam may be formed at the position by closing the zero-set switch 31. When a beam is formed at the 0 position, current flow through the 0 target to the power supply provides a potential of about 175 volts at the target buss 34. This potential appears on the first electrode 44 of the neon tube 42. At the same time, a potential of about 160 volts appears on the second electrode 46 of tube 42 as a result of current flow through the second neon tube 42'. Thus, with only about volts applied across the first neon tube 42, this tube is extinguished.

The tube 10 is caused to perform a counting operation by the application of negative counting pulses of about 150 volts amplitude from the source 57. The first pulse after the beam has been set at 0, when coupled through the capacitor 56 to the driving circuit of tube 10, sees a high resistance path, the one in which the neon tube 42 is glowing, and a low resistance path, the one in which the neon tube 42 is extinguished. Accordingly, the greater portion of the pulse, as it flows into the high resistance path, is absorbed across resistor 48, and only a small portion is coupled through capacitor 47 to the odd-numbered switching electrodes. This pulse is too small to affect the tube It), and in any case, since the beam is in an evennumbered position, a pulse applied to an odd-numbered switching grid cannot switch the beam. However, in the low resistance path, only a small portion of the input pulse is absorbed by resistor 48, and the greater portion of the pulse is coupled through capacitor 47 to the even-numbered switching grids, including, of course, the switching grid at the position to which the beam is flowing. This pulse thus causes an electron beam to switch by one position into an odd-numbered position, position 1. Current flow through the target load resistor at the 1 position then reduces the potential of the target buss 34' and the first electrode 44' of the second neon tube 42' to such a level that this tube is extinguished. At the same time, when current flow to the 0 target is discontinued, the target buss 34 rises to about 235 volts, which provides sufficient potential across the first neon tube 42 to cause it to glow, In similar fashion, the next switching pulse causes the electron beam to switch from the first position to the second, turns off the second neon tube 42, and turns on the first neon tube 42.

The circuit of the invention thus provides a simple and inexpensive circuit for driving a multi-position beam switching tube as a counter.

What is claimed is:

1. A counter circuit including an electron beam switching tube having a cathode and a plurality of groups of electrodes; each group 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 n65; one group of electrodes to the next; said target electrodes being connected in two sets with alternate targets being connected in a set; the switching electrodes being connected in two sets with alternate switching electrodes in a set; a first current flow path in series with one set of target electrodes and including a gaseous glow tube; and a second current flow path in series with the other set of target electrodes including a gaseous glow tube; said paths alternately having high and low resistance; the path having low resistance having its glow tube off and associated with the set of target electrodes which includes the target electrode receiving an electron beam at any instant; the path having high resistance having its glow tube on; and a source of switching pulses couple through separate impedances to each of said glow tubes and through other separate coupling impedances to said sets of switching electrodes.

2. A counter circuit including an electron beam switching tube having a cathode and a plurality of groups of electrodes; each group 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 target elec trodes being connected in two sets with alternate targets being connected in a set; the switching electrodes being connected in two sets with alternate switching electrodes in a set; a first current flow path in series with one set of target electrodes and coupled to the set of switching electrodes associated therewith; a second current flow path in series with the other set of target electrodes and coupled to the other set of switching electrodes; said paths being adapted to alternately have high and low resistance; the path having low resistance being associated with the set of target electrodes which includes the target electrode receiving an electron beam at any instant; and a source of switching pulses coupled to said paths for applying beam switching pulses thereto through separate impedances, said source thus being coupled both to said glow tubes and to said sets of switching electrodes through voltage-dropping impedances.

3. A counter circuit including an electron beam switching tube having a cathode and a plurality of groups of electrodes; each group 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 target electrodes being connected in two sets with alternate targets being connected in a set; the switching electrodes being connected in two sets with alternate switching electrodes in a set; a first path including a first gaseous glow tube and an impedance coupled between one set of target electrodes and a source of reference potential; coupling means coupling said path to the set of switching electrodes associated with said one set of target electrodes; a second path including a second gaseous glow tube and an impedance coupled between the other set of target electrodes and said source of reference potential; coupling means coupling said second path to the other set of switching electrodes; and a source of beam switching pulses coupled through separate impedances to both of said paths and adapted to aiiect only one set of switching electrodes with each switching pulse, the set of switching electrodes affected being determined by the state of each glow tube and the resultant potential applied across each of said separate impedances and by the potential coupled to each set of switching electrodes.

4. A counter circuit including an electron beam switching tube having a cathode and a plurality of groups of electrodes; each group 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 target electrodes being connected in two sets with alternate targets being connected in a set; the switching electrodes being connected in two sets with alternate switching electrodes in a set; a first current flow path including a first gaseous glow tube coupled between one set of target electrodes and a source of reference potential; coupling means coupling said path to the set of switching electrodes associated with said one set of target electrodes; a second current fiow path including a second gaseous glow tube coupled between the other set of target electrodes and said source of reference potential; coupling means coupling said second path to the other set of switching electrodes; and a source of beam switching pulses coupled to both of said paths and adapted to aifect only one set of switching electrodes with each switching pulse, the set of switching electrodes affected being determined by the state of each glow tube and the resultant potential applied across each of said separate impedances and by the potential coupled to each set of switching electrodes.

5. A counter circuit including an electron beam switching tube having a cathode and a plurality of groups of electrodes; each group 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 target electrodes being connected in two sets with alternate targets being connected in a set; the switching electrodes being connected in two sets with alternate switching electrodes in a set; a first path including a first gaseous glow tube and an impedance coupled between one set of target electrodes and a source of reference potential; coupling means coupling said path to the set of switching electrodes asociated with said one set of target electrodes; a second path including a second gaseous glow tube and an impedance coupled between the other set of target electrodes and said source of reference potential; coupling means coupling said second path to the other set of switching electrodes; said paths being adapted to have relatively high or low impedance depending on the state of its glow tube; and a source of beam switching pulses coupled through separate impedances to both of said paths and adapted to affect only one set of switching electrodes with each switching pulse, the set of switching electrodes affected being the set coupled to the path which exhibits low impedance due to the state of its glow tube.

6. A counter circuit including an electron beam switching tubehaving a cathode and a plurality of groups of electrodes arranged in a series and occupying alternately even-number and odd-number positions in the series; 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 target electrodes being connected in two sets with a first set including the target electrodes at the even-number positions and a second set including the target electrodes at the odd-number positions;

the switching electrodes being connected in two sets with a first set including the switching electrodes at the even-number positions and a second set includin the switching electrodes at the odd-number positions;

a first current flow path in series with said first set of target electrodes and including a first gaseous glow tube; a second current flow path in series with said second set of target electrodes and including a second gaseous glow tube;

said first and second paths alternately being adapted to have relatively high and low impedance depending on whether the glow tube therein is on or ofi, with the impedance being low when a glow tube is off and high when a glow tube is on;

said first glow tube being on in said first path including said first set of target electrodes and said first set of switching electrodes when an electron beam is flowing to a target electrode in said second set, said second glow tube being on in said second path including said second set of target electrodes and said second set of switching electrodes when an electron beam is flowing to a target electrode in said first set;

and a source of switching pulses coupled through separate impedances to each of said first and second current fiow paths for applying beam switching pulses thereto, with a switching pulse being applied to and aifecting only that set of switching electrodes associated with a target electrode which is receiving an electron beam and with a current flow path having low impedance.

Medoff Aug. 26, 1958 Gardberg Jan. 12, 1960

Claims (1)

1. A COUNTER CIRCUIT INCLUDING AN ELECTRON BEAM SWITCHING TUBE HAVING A CATHODE AND A PLURALITY OF GROUPS OF ELECTRODES; EACH GROUP 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 TARGET ELECTRODES BEING CONNECTED IN TWO SETS WITH ALTERNATE TARGETS BEING CONNECTED IN A SET; THE SWITCHING ELECTRODES BEING CONNECTED IN TWO SETS WITH ALTERNATE SWITCHING ELECTRODES IN A SET; A FIRST CURRENT FLOW PATH IN SERIES WITH ONE SET OF TARGET ELECTRODES AND INCLUDING A GASEOUS GLOW TUBE; AND A SECOND CURRENT FLOW PATH IN SERIES WITH THE OTHER SET OF TARGET ELECTRODES INCLUDING A GASEOUS GLOW TUBE; SAID PATHS

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