US3500121A

US3500121A - Electronic counting or timekeeping system using glow discharge tube without permanent anode

Info

Publication number: US3500121A
Application number: US705793A
Authority: US
Inventors: Heinz A De Koster; Michael J Ingenito
Original assignee: General Time Corp
Current assignee: General Time Corp
Priority date: 1968-02-15
Filing date: 1968-02-15
Publication date: 1970-03-10
Anticipated expiration: 1987-03-10

Description

March 10, 1970 ELECTRONIC COUNTING 0R TIMEKEEPING SYSTEM USING GLOW DISCHARGE TUBE WITHOUT PERMANENT ANODE Filed Feb. 15, 1968 H. A. DE KOSTER ET AL 4 Sheets-Sheet l 1 r r 1 a1 El 1 L 1 T w T :1 @l l l 1: r 1, T- a 1: 1 ,l 11 M H 11 H ,4. ok/mrrm MICHAEL J. [NGENITO Arrvs March 10, 1970 H. A. DE KOSTER ETAL ELECTRONIC COUNTING OR TIMEKEEPING SYSTEM USING GLOW Filed Feb. 1.5, 1968 DISCHARGE TUBE WITHOUT PERMANENT ANODE 4 Sheets-Sheet 2 Cz loh l 20 an I 269/ PULSE s cm a CIRCUIT bsg Invenrroas March 10, 1970 H. A. DE KOSTER ETAL 3,500,121 ELECTRONIC COUNTING OR TIMEKEEPING SYSTEM USING GLOW DISCHARGE TUBE WITHOUT PERMANENT ANODE 4 Sheets-Sheet 5 Filed Feb. 15, 1968 DUAL FLIP FLOP S o R MW o r s5 -a 2 :1 N .J. I A L M m mm Arrvs.

H. A. DE KOSTER ETAL ELECTRONIC COUNTING OR TIMEKEEPING SYSTEM USING GLOW March 10, 1970 DISCHARGE TUBE WITHOUT PERMANENT ANODE 4 Sheets-Sheet 4 Filed Feb. 15, 1968 III u llll 5 N65625: uziutkw no x3818 1% u w II lill j 3N wZI 2o mofimfit mo Sago ow M23 0 MN 13m E-E n6 samba Imwmroas H51: 17. d /fosrflf MICHAEL J'. [NGENITO b 1%;4, MAJ, 4 012? @M Arrvs.

United States Patent 3,500,121 ELECTRONIC COUNTING OR TIMEKEEPING SYSTEM USING GLOW DISCHARGE TUBE WITHOUT PERMANENT AN ODE Heinz A. de Koster, Stamford, Conn., and Michael J.

Ingenito, Bronx, N.Y. (both General Time Corporation, Central Research Laboratory, Progress Drive, Stamford, Conn. 06902) Filed Feb. 15, 1968, Ser. No. 705,793 Int. Cl. H01j 17/36; H03k 23/18, 23/38 US. Cl. 31584.6 12 Claims ABSTRACT OF THE DISCLOSURE An electronic counting or timekeeping system including a glow discharge tube having a series of spaced internal electrodes for counting successive electrical input signals. The electrodes are connected in two operative groups, with at least one electrode of each group being located between each pair of successive electrodes in each other group. Electrical control means are connected to the two electrode groups for applying a transfer potential across successive pairs of adjacent electrodes in response to the input signals so as to step the glow discharge along successive electrodes in the series with each electrode functioning alternately as cathode and anode, so that no permanent anode is required.

The present invention relates generally to timepieces and, more particularly, to an improved electronic timepiece having an improved electronic counting system.

In copending applications Ser. No, 524,027 filed Feb. 1, 1966, by H. A. de Koster and entitled Electronic Clocks; Ser. No. 581,592 filed Sept. 23, 1966, by H. A. de Koster and M. Ingenito and entitled Electronic Counters; and Ser. No. 581,591 filed Sept. 23, 1966, by H. A. de Koster and M. Ingenito and entitled Electronic Countersjall of which are owned by the assignee of the present invention, there are described several different electronic timepieces having improved electronic counting systems utilizing gas discharge tubes. The counting i achieved by stepping the glow discharge along successive cathodes which are typically arranged to serve as time indicating elements as well as operative elements of the electronic counting system. As explained in detail in the copending applications, the glow discharge is formed and transferred by the application of controlled electrical potentials across the various gaps between the indicating cathodes and one or more permanent anodes.

It is a primary object of the present invention to provide an improved glow discharge timepiece which eliminates one of the basic physical components of such devices as proposed heretofore. Thus, an important related object of the invention is to provide such an improved timepiece which requires fewer parts than similar timepieces proposed heretofore and, consequently, can be constructed in a relatively compact assembly, at a relatively low cost, and with fewer assembling operations.

It is another object of the present invention to provide such an improved glow discharge timepiece which permits the use of a greater variety of ionizable gases, including gas combinations having a flat Paschen-minimum such as Penning mixtures.

A further object of the invention is to provide an improved glow discharge timepiece of the foregoing type which permits the use of a greater variety of electrode materials, including relatively low cost materials such as aluminum, iron, nickel and the like.

Still another object of the present invention is to provide a glow discharge counter which has all the advantages described above and can be used in applications other than a timepiece.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIGURE 1 is a simplified perspective view of an electronic timepiece embodying the present invention with portions thereof broken away to show the internal structure, and partially showing the electrode arrangement therein;

FIGS. 2a and 212 form a schematic circuit diagram of the electrical control system in the timepiece of FIG. 1;

FIG. 3 is a pulse diagram depicting the operation of the system of FIGS. 2a and 2b; and

FIG. 4 is a schematic diagram illustrating the voltage levels at a series of exemplary electrodes connected to a modified electrical control system during one cycle of the operation thereof.

In order to understand the present invention, the principles of gas discharges must be borne in mind. To obtain a gas discharge, a pair of electrodes are spaced apart in an envelope containing an ionizable gas, usually at low pressure, and an electrical potential is applied across the electrodes. Since ideal gases do not conduct electricity, initially no current should flow between the positively charged electrode (the anode) and the negatively charged electrode (the cathode). However, the gas between the electrodes is subject at all times to bombardment by cosmic rays and other nuclear radiation from natural sources, as a result of which the gas atoms emit electrons and become ionized, i.e., they lose or gain an electron and become positive or negative ions. The positive ions are, of course, attracted to the cathode. If the potential between the cathode and the anode is small or the spacing great, an ionized atom will likely combine wtih a free electron in the gas, again becoming a neutral atom, before reaching the cathode, and, consequently, only a very small current will flow between the cathode and anode. A few positive ions that have travelled far enough, if the voltage is great enough, will gain sutficient energy and momentum that, upon hitting the cathode, they release one or more electrons. Furthermore, electrons and negative ions travelling toward the anode may gain sufficient momentum to ionize a gas atom upon collision, if the potential and the distance travelled before collision with the gas molecule are great enough. At low potentials and great electrode spacing, the loss of ions and electrons by diffusion to the walls of the vessel and by recombination into neutral atoms, is much more likely than the production of new ions through the various described collision processes. However, for any given electrode spacing, there is a certain characteristic potential, herein called the breakdown voltage, at which more ions are created by collision processes than are lost by diffusion and recombination. At this point, the current flowing in the discha ge increases abruptly and would become infinite if it were not for the external resistance in the circuit. There then exists a region of intense ionization which emits a characteristic glow, ordinarily spaced approximately half a millimeter from the cathode, known as the cathode glow. Ordinarily, the glow will not cover the entire surface of the cathode, the particular area covered being proportioned to the current between the electrodes.

If a potential equal to or greater than the breakdown voltage is applied across the electrodes of a gas discharge tube in which no glow is present, a certain amount of time, called the ionization time, in the order of some microseconds, is required for the ionization and thus the current to build up to that limited by the external resistance in the circuit.

If a pair of electrodes are located adjacent to an existing glow discharge, within a few millimeters for example, the

space between the electrodes is partially ionized due to diffusion of electrons and ions from the adjacent glow discharge. This degree of ionization is much greater than that due to natural sources, and reduces the breakdown voltage to the so-called transfer voltage, and this effect can be used to transfer the glow discharge from one cathode to an adjacent cathode. Electrodes next to a glowing cathode that have such a reduced breakdown voltage (the transfer voltage) are generally referred to as primed electrodes.

When a glow discharge exists between a cathode and an anode, a characteristic potential will exist therebetween, herein called the maintaining voltage, which again is a characteristic of the gas. In order to maintain a glow discharge, the external circuitry connected to the cathode and anode must be able to supply current to them at the maintaining voltage. If the potential supplied to the cathode and anode is allowed to drop below the maintaining voltage, the glow discharge will terminate, but the cathode will remain primed for the deionization time of the gas, i.e., the time required for most of the ionized atoms to recombine with free electrons. For most gases this time is in the order of some microseconds and is much larger than the ionization time. For further understanding of the characteristics of such gas discharge devices, reference may be made to such texts as: Action and Swith, Cold Cathode Discharge Tubes, Academic Press, Inc., New York, 1963; Rudolf Seeliger, Angewandte Atomphysik, Julius Springer, Berlin, 1938; and Leonard B. Loeb, Basic Processes of Gaseous Electronics, 2nd edition, University of California Press, 1955 Turning now to the drawings and referring first to FIGURE 1, there is illustrated a glow discharge timepiece having four concentric circular arrays or series of electrodes P, S, M and H, three of which serve as indicators of the time in seconds (S), minutes (M), and hours (H) in a manner similar to that of conventional mechanical clock hands. In this case, however, the indication is by the position of a glow discharge in each of the three electrode series S, M and H. More particularly, the glow in the series of electrodes S serves as a sweep second indicator, the glow in the series of electrodes M serves as a minute indicator, and the glow in the series of electrodes H serves as an hour indicator. The purpose of the fourth electrode series P is to divide the frequency of pulses derived from the available power line to provide a pulse input frequency of one pulse per second for the electrode series S.

The four electrodes series P, S, M and H are all supported on a common substrate 11 which also forms one wall of a hermetically sealed chamber filled with a suitable ionizable gas such as argon or the like. The other wall of the gas chamber is formed by a cupped or dished cover plate 12 which is transparent or translucent to permit viewing of the glowing electrodes therein, and is hermetically sealed to the substrate 11 by means of a sealing gasket 13. For the purpose of isolating the various electrode series from each other, a plurality of annular

transparent walls

14, 15 and 16 may be conveniently formed as integral parts of the cover plate 12 and hermetically sealed to the substrate 11 between the respective electrode series. Finally, the electrodes are electrically connected to appropriate input means and control circuitry for controlling the stepping of the time-indicating glow discharge around the respective electrode series. The particular means of forming the illustrative glow discharge tube and the electrical connections thereto, the particular materials employed therein, and the particular dimensions and configuration thereof do not form a part of the present invention, and specific exemplary embodiments have already been described in detail in the aforementioned copending applications. Such description will not be repeated herein, since reference may be had to the copending applications, particularly Ser, No. 524,027, for a moredetailed understanding there f, and since the present invention is equally applicable to a wide variety of such systems.

Turning next to FIGS. 2a and 2b, there is illustrated an electronic control system for initiating a glow discharge in each of the four electrode series P, S, M and H, and controlling the movement of each glow discharge around each respective electrode series to provide a complete timekeeping and indicating system. Movement of the glow discharge is synchronized with electrical input signals derived from an available power line and representing uniform time intervals. In the particular system illustrated, each electrode series P, S, M and H is divided into two electrode groups, i.e., alternate electrodes (e.g., oddnumbered electrodes P1, P3, P5 are interconnected to form a first electrode group, and the intervening electrodes (e.g., even-numbered electrodes P2, P4, P6 are interconnected to form a second electrode group. To control the direction of the glow discharge transfer, the electrodes have an asymmetrical configuration so that the application of a transfer potential to the electrodes on both sides of a glowing electrode will initiate a glow discharge at only one of such electrodes. However, it should be understood that the present invention is not limited to the particular electrode system illustrated, but is equally applicable to a variety of other systems having three or more electrode groups, other types of directional control means and the like. Several such systems, including the illustrative two-group, asymmetrical electrode system, are described in detail in the aforementioned copending applications, particularly Ser. Nos. 581,591 and 581,592.

The electrical input signals representing repetitive time intervals to be counted by the system of FIGS. 2a and 2b, are derived from a conventional 60-cycle A.-C. supply connected to input terminals 20 of a conventional pulseshaping circuit 21, and applied to a dual flip flop 22. The flip flop 22 in turn produces output pulses for triggering a switching circuit 23 associated with the first series of electrodes P. Thus, the illustrative timekeeping system is of the synchronous type, since it relies on the oscillations of the available power line signal as the timekeeping standard. However, it is to be understood that this invention is not limited to a synchronous system, but rather is equally applicable to systems using other timekeeping standards, such as self-contained electrical or electromechanical oscillators for example.

For the purpose of turning the control system on and olf, a manually operated switch S1 is connected between the input terminals 20 and the pulse shaping circuit 21 so that when the switch S1 is open, the A.-C. signal is disconnected from the system to render it inoperative. When the switch S1 is closed, the pulse shaping circuit 21 responds to the power line signal applied to the input terminals thereof to produce a series of output pulses for triggering the dual flip flop 22 via line 24 in synchronism with the oscillations of the power line input signal. These pulses are fed from the pulse shaper 21 to the flip flop 22 via line 24 to a toggle switch S2 and then on through a line 25, for reasons to be described below.

In accordance with the present invention, an electrical control system is operatively connected to the first and second electrode groups of each series for applying a transfer potential across successive pairs of adjacent electrodes in each series in response to the input signals derived from the available power line so as to step the glow discharge along successive electrodes with each electrode functioning alternately as cathode and anode. Thus, in the illustrative embodiment, a source of transfer potential V1 is operatively connected to the electrode series P, and the electronic switching circuit 23 responds to the signals from the flip flop 22 to apply the transfer potential alternately to the first and second electrode groups with each group functioning alternately as cathode and anode, More particularly, as the first flip flop of the dual unit 22 is switched back and forth between its two stable states in response to the triggering pulses from the shaping circuit 21, a square wave output generated in

lines

26, 27 is applied to the switching circuit 23 to turn two transistors Q1 and Q2 therein alternately on and off, thereby controlling the voltage levels at the two P-electrode groups.

When the flip flop connected to

lines

26, 27, is in one state, transistor Q1 is saturated by the flip flop output signal applied thereto via line 26 and resistor R1, and transistor Q2 is cut off, so that the first group of electrodes P (theodd-numbered electrodes in FIGS. 2a and 2b) is grounded and the second group of electrodes P (the evennumbered electrodes) is at the transfer potential. In this operative state, a glow discharge is formed at one of the first-group electrodes, e.g., P3, and the two electrodes, e.g., P2 and P4, on opposite sides of the glowing electrode function as dual anodes. The glow discharge current path in this condition is from V1 through resistor R4, through electrodes P2 and P4 (anodes) into electrode P3 (cathode), and finally through the saturated transistor Q1 to ground. Since electrodes P2 and P4 are directly adjacent the glowing electrode P3, they are primed by the diffusion of ions from P3. This condition is maintained, with electrode P3 glowing, until the next pulse from the shaping circuit 21 switches the flip flop connected to

lines

26, 27 to its other stable state, whereupon the conditions of the transistors Q1, Q2 are reversed. That is, transistor Q1 is cut off and transistor Q2 is saturated by the flip flop output signal applied thereto via line 26 and resistor R2, so that the second-group electrodes P are at the transfer potential, and the first-group electrodes P are grounded. In this operative state, the glow discharge current path is from V1 through resistor R3, through electrodes P3 and P5 (anodes) into electrode P4 (cathode), and finally through the saturated transistor Q2 to ground.

When this reversal of conditions occurs, the glow discharge is transferred from the electrode P3 to one of the primed electrodes P2 or P4. In the illustrative electrode system, the electrodes are provided with laterally projecting tabs or directors d (FIGS. 1 and 2) to form an asymmetrical electrode configuration that is designed to always transfer the glow discharge in a clockwise direction. Consequently, in the particular example described above, the glow discharge would be transferred from electrode P3 to the primed electrode P4, rather than the other primed electrode P2. In other words, the directors 0. cause the electrode P4 to be primed to a greater degree than electrode P2 by creating an asymmetrical electric field configuration relative to the main body portions of the electrode, thereby producing preferential breakdown conditions on one side of the glowing electrode so that the glow discharge will always be transferred in that direction.

Upon receipt of a further pulse from the shaping circuit 21, the flip flop connected to

lines

26, 27 is returned to its first stable state again, and the resulting output signals in

lines

26, 27 restore transistors Q1, Q2 to their first condition, i.e., transistor Q1 is saturated to connect the first-group electrodes P to ground, and transistor Q2 is cut off to apply the transfer potential to the secondgroup electrodes P. It can thus be seen that the condiditions of the two electrode groups in series P are continuously switched back and forth in synchronism with the triggering pulses derived from the 60-cycle power line, so that the two electrode groups function alternately as cathodes and anodes. In effect, the electronic control system associated with the two electrode groups utilizes the idle electrodes adjacent the glowing electrode (cathode) as anodes, so that no separate permanent anode is needed. This, of course, eliminates at least one entire component for each electrode series, thereby permitting attendant reductions in the overall size and cost of the device, as well as reducing the number of assembling operations required.

In order to provide protection against negative spikes fed back from the collectors of the high voltage switching transistors Q1, Q2, diodes D1, D2 are connected from the flip

flop output lines

26, 27, respectively, to ground. Such spikes are often caused by capacitive coupling between the collectors of the switching transistors Q1, Q2, due to the capacitance of the interleaved electrodes of the first and second electrode groups.

As the glow discharge is stepped along successive electrodes P in response to the timing pulses derived from the power line signal, it advances at a rate of sixty electrodes or positions per second, i.e., at the same rate as the timing pulses. Since there are 60 electrodes in the series P, the glow discharge advances around the entire series of electrodes once each second. Accordingly, if an output pulse is produced in response to the completion of each cycle, it can be seen that the first electrode series P effectively divides the power line frequency by 60 and, therefore, can be used as a source of seconds pulses, i.e., pulses generated at a rate of one pulse per second. These seconds pulses, in turn, can be used to control a second electrode series to provide a sweep second glow, while at the same time providing a source of minutes pulses, i.e., pulses generated at a rate of one pulse per minute, and so on.

In order to generate a second pulse in response to the completion of each 60-pulse count by the first electrodes series P, the input to the second flip flop of the dual unit 21 is connected to electrode P60 via switching transistors Q3 and Q4. More particularly, when the glow discharge current path is through electrode P60 as the cathode, transistor Q3, which is normally cut off, becomes forward biased, and transistor Q4 becomes cut off. As transistor Q4 is cut off, the second flip flop of unit 21, i.e., the flip flop connected to output lines 26s, 27s is triggered by a pulse supplied from a voltage source V2 via resistor R5 and the normally closed contacts of a toggle switch S1 to be described in more detail below. To permit the use of a low voltage transistor for switching transistor Q3, a diode D3 is connected in the collector circuit thereof, with the connection to the transistor Q4 being made between diode D3 and a resistor R6 connected to a voltage source V3. A capacitor C1 connected across resistor R7 in the base-collector circuit of transistor Q3 prevents false triggering of the transistor Q3 such as might be caused by capacitive current flowing into the electrode P60 when the even-numbered electrodes are grounded through the high voltage switching transistor Q2. The capacitor C1 prevents such false triggering by slowing down the normal glow current triggering of transistor Q3.

When transistor Q3 is cut off, i.e., while the electrodes P1-P59 are counting from 1 to 59, transistor Q4 provides a conductive path from voltage source V2 through resistor R5 to ground. When the glow discharge is finally transferred to electrode P60, however, the signal applied to transistor Q4 via resistors R8 and R9, in response to the switching action of transistor Q3, cuts off transistor Q4, and the resulting rising waveform at the collector of Q4 triggers the second flip flop in the dual unit 21 via input line 45. Consequently, it can be seen that an output pulse will be produced in the output lines 26s, 27s, from the second flip flop in response to each completion of a 60-count by the electrodes P, thereby supplying a source of seconds pulses generated at a rate of one pulse per second.

At this point, it will be appreciated that each of the remaining three counting stages S, M, and H of the complete timekeeping system illustrated in FIGS. 2a and 2b functions in exactly the same manner described above for the first stage P. The control circuits associated with the remaining three stages are identical to the circuit already described in connection with the first stage, and thus have been identified by the same reference symbols with the addition of the distinguishing sufiix s for the second stage, m for the third stage, and h for the fourth stage. The only differences among the four stages in the illustrative system are that the third stage M produces three output pulses per cycle, at a rate of one pulse per 20 minutes, and the fourth stage H contains only 36 electrodes instead of 60. Thus, it can be seen that the glow discharge will be stepped around the electrode series H at a rate of one position per 20 minutes, and one complete revolution or cycle will be completed each 12 hours. In order to produce the two extra pulses per cycle, electrodes M20 and M40 (not shown) are connected to the transistor Q3m so that a transfer pulse for electrode series H is produced each time the glow discharge arrives at one of the electrodes M20, M40, and M60.

The specific function of each of the four counting stages in an actual timekeeping system will also be apparent from the description given thus far, but these functions will now be summarized to facilitate an understanding thereof. Since the oscillations in the available power line signal occur at a rate of 60 cycles per second, the pulses which trigger the first counting stage occur at the same rate. Thus, the specific function of the first counting stage P is to divide these pulses by 60, so as to produce triggering pulses for the second counting stage S at a rate of one pulse per second. These pulses have been referred to above as the seconds pulses. The second counting stage S divides the seconds pulses by 60 to produce triggering pulses for the third counting stage M at a rate of one pulse per minute, and at the same time provides a continual display or indication of the seconds being counted in a manner similar to that of the conventional sweep second hand in mechnaical time indicators. In this case, it is the glow, rather than a mechanical hand, which sweeps around the clock face at a rate of one revolution per minute.

The output pulses from the second counting stage S, which are referred to as minutes pulses, trigger the third counting stage M which again divides the pulse rate by 20 to provide triggering pulses for the fourth counting stage H at a rate of one pulse every 20 minutes. As in the case of the second counting stage S, the third counting stage M also serves to provide a visible display or indication of the minutes as they are counted in the same manner as a conventional minute hand in a mechanical time indicating system. Again, it is the glow, rather than a mechanical clock hand which moves around the clock face to indicate the time. The fourth counting stage H counts the one-third hour pulses generated every 20 minutes by the third counting stage M and provides a continual visible indication of the instantaneous count, thereby serving the same function as a conventional hour hand in a mechanical time indicating system. Thus it can be seen that the illustrative system includes an hour indicator, a minutes indiactor, and a sweep second indicator so as to indicate the time to an observer in the same manner as a conventional mechanical clock, but Without the use of any moving parts whatever.

In order to provide a better understanding of the electronic control system shown in FIGS. 2a and 2b, a pulse diagram depicting the operation thereof has been shown in FIG. 3. Referring to FIG. 3, the available 60-cycle power line signal 30 is applied across the input terminal 20 of the pulse shaping circuit 21 so as to produce output pulses 31 in line 24 at a rate of 60 pulses per second. The pulses 60 trigger the first flip flop in the dual flip flop unit 22 so as to produce an output signal 32 on line 26 and output signal 33 on line 27. The

signals

32 and 33 turn the two switching transistors Q1 and Q2 alternately on and off, with the first transistor Q1 being off when the second transistor Q2 is on and vice versa, so as to generate

signals

34 and 35 at the collectors of the two transistors Q1 and Q2, respectively. The

signals

34 and 35 cause the transfer potential to be applied across successive pairs of adjacent electrodes in synchronism with the timing pulses 31 as described previously. Each time a 60-count is completed by the first electrode series P, transistor Q3 becomes forward biased, producing a collector signal 36, and transistor Q4 is cut off, producing a collector signal 37 which triggers the second flip flop of the dual unit 22. The operating sequence is then repeated for the second counting stage, with the second flip fiop of the unit 22 producing an output signal 32s on line 26s and a signal 33s on output line 27s. The signals 32s and 33s switch the transistors Qls and Q2s for the second counting stage alternately on and ofi', thereby producing signal 34s on the line to the odd-numbered electrode S, and signal 35s on the line to the even-numbered electrode S so as to step the glow discharge around the electrode series S at a rate of one transfer per second. The second-stage counting cycle is then completed in the same manner described above for the first-stage, and the third-stage and fourthstage counting cycles follow in cascade fashion.

For the purpose of initiating a glow discharge at selected electrodes in each series P, S, M and H when the system is first started, a push button switch S3 causes an initiating signal to be applied to the selected electrode. More particularly, when the switch S3 is in the position illustrated in FIG. 2a, a capacitor C2 is connected across a positive voltage source V4, thereby charging the capacitor; when the switch S3 is thrown to the other position, the capacitor C2 discharges, thereby supplying a negative signal through blocking diodes D4, D4s, D4m and D411 to electrodes P59, S59 and M59 in the electrode series P, S and M, respectively, and to electrode H36 in the electrode series H. The system is always pre-set to apply the positive transfer potential to the even-numbered electrodes in series P, S and M, so that the application of the negative voltage to the odd-numbered electrodes P59, S59 and M59 causes a voltage greater than the breakdown potential to be applied across such electrodes, thereby initiating a glow discharge at the cathodes P59, S59 and M59. The breakdown potential is maintained only for the duration of the signal from the discharging capacitor C2, but the transfer potential applied to the glowing electrodes is sufficient to maintain the glow discharge once it has been initiated. A resistor R10 and diode D5 are connected in parallel across electrodes P57 and PS9 so that the signal from capacitor C2 is applied only to electrode P59, while still connecting electrode P59 to switching circuit 23 for the normal glow discharge transfer thereto during steady state operation.

The operation is the same at each of the other electrode series S, M and H, except that in series H the control system is pre-set to apply the transfer potential to the odd-numbered electrodes, and the initiation signal from diode D411 is applied to the even-numbered electrode H36. The glow discharge is thus initiated at electrode H36.

In orderto set the glow discharges in the time-indicating electrode series S, M and H to the particular positions corresponding to the correct time, the toggle switch S2 may be thrown in a first direction to advance the indicating glow discharges at a very fast (VF) rate for a rapid approximate setting, and then to a second position for advancing the indicating glow discharges at a fast (F) rate for fine setting. Both the VF and the F rates are substantially faster than the normal rate of advancement of the indicating glow discharges. The particular positions shown for the

various switching elements

40, 41, 42 and 43 of toggle switch S2 in FIG. 2a represent the normal positions for the steady state timekeeping operation of the system.

If it is desired to advance the indicating glow discharges at a VP rate, the toggle switch is thrown in a first direction so as to switch element 40 from contact 82a to S211 and element 41 from contact S20 to contact 82d. In this position, line frequency pulses from the pulse shaper are fed through a line 44 directly to the flip-flop 22111 for controlling the minutes-indicating electrode series M so as to advance the glow discharge along the electrodes M at a rate of 60 positions per second, rather than the normal rate of 60 positions per hour. This rapid advancement of the glow discharge rate in the electrode series M also increases the rate of advancement of the glow discharge in the hours-indicating electrode series H to a rate of three positions per second rather than three positions per hour.

After an approximate time setting has been made, the toggle switch S1 is thrown in the other direction so as to return switching

elements

40, 41 to their normal positions, and to switch element 42 from contact 82a to 82 and element 43 from contact S2g to $211. This causes the line frequency pulses from the pulse shaper to be fed through a line 45 to the flip flop controlling the rate of advancement of the glow discharge in the seconds-indicating electrode series S so as to increase the rate of advancement of the glow discharge in this electrode series from one position per second to 60 positions per second. Again, the rate of advancement of the glow discharges in the two following electrode series M and H are increased proportionately. This rate of advancement is 60 times as fast as normal, but slow enough to permit the glow discharges to be set precisely at the correct time.

In the glow discharge tubes that have been proposed heretofore, for counting and/ or timekeeping purposes, including those described in the aforementioned copending applications, the glow discharge is formed by applying a controlled electrical potential across an electrode gap formed between a permanent anode and one of a plurality of cathodes. In the present invention, on the other hand, the permanent anode is eliminated by utilizing the display electrodes alternately as both cathodes and anodes. As can be seen from the foregoing detailed description, the electrical control means associated with each electrode series automatically applies the transfer voltage across successive pairs of adjacent display electrodes in response to successive electrode input signals so as to step the glow discharge along successive electrodes, with each electrode functioning alternately as cathode and anode.

As mentioned previously, this invention is not limited to systems having two electrode groups in which the transfer voltage is applied alternately to the two groups, but is equally applicable to systems using three or more electrode groups with the transfer voltage being cyclically applied across different pairs of the electrode groups in sequence. Several exemplary systems utilizing three electrode groups are described in detail in the aforementioned copending applications, and FIG. 4 of the present drawings illustrates schematically how the present invention may be embodied in such a system. It can be seen that the twelve electrodes illustrated schematically in FIG. 4 are interconnected in three different groups identified by the reference symbols I, II and III. In the particular operative state illustrated, the transfer potential is applied to Group I, and the particular electrode that is glowing within that group is electrode 3, with

electrodes

2 and 4 serving as anodes. The voltage levels on the various electrodes are illustrated schematically on lines A, B, C and D. As can be seen from line A, all the electrodes in group I are negative, while all the electrodes in groups II and III are positive. The glow appears only on electrode III because this is the only electrode that was primed at the time of the previous transfer, and this electrode is isolated from all the other electrodes in the same group by a large positive voltage barrier provided by

electrodes

1 and 2 on one side, and

electrodes

4 and 5 on the other side. When the transfer potential is switched from group I to group III, the electrodes of group I change from negative to positive, the electrodes of group III change from positive to negative, and the electrodes of group II remain positive. In the situation illustrated in line B the electrode 3 is still glowing, but the potential on the electrodes of group III has dropped to zero. In the situation illustrated in line C, the glow discharge has been transferred to electrode 4 in group III, and the potential on the electrodes of group I is zero. In line D, the electrodes of group I are at full positive potential, so that the maximum differential exists between the electrodes of group III on the one hand, and the electrodes of groups I and II on the other hand. Thus, the transfer of the glow discharge to electrode 4 is completed; electrode 4 is the cathode, and electrodes 3 and 5 are the anodes.

As can be seen from the schematic illustrations in FIG. 4, the area in which the glow discharge transfer takes place is located between two large positive potential barriers provided by

electrodes

2 and 5 in Group II. Thus, it is virtually impossible for the glow discharge to be transferred to any electrode other than number 4, so the transfer action is extremely reliable. Moreover, the deionization time of the gas, as well as other gas parameters are of considerably less importance than in systems having permanent anodes. For example, gas combinations with a fiat Paschen-minimum such as Penning mixtures can be used in glow discharge counting tubes embodying the present invention. Also, because of the changing polarity of the electrodes any effect that the glow discharge might have on adjacent electrodes is minimized, and thus it is possible to use lower cost electrode materials such as aluminum, iron or nickel, as contrasted with the more expensive molybdenum for example.

The following is a list of the values employed for the various circuit elements in a preferred embodiment of the illustrative circuit, although it is to be understood that the invention is not limited to this particular circuit or these particular values:

Q1, Q2 2N3439. Q3, Q4 2N2926. Dual Flip Flop 22 SN7302 (Texas Inst.). D1, D2, D3, D4, D5 IN2070A. R1, R2 2.2K. R3, R4 220K, 1 w. R5 1.8K. R6 4.7K R7 680 R8 6.8K R9 1K R10 56K C1 0.001. C2 5.0, 150 v. V1 300 v V2 4 v. V3 -2 12 v V4 v Unless otherwise indicated, all the above resistor values are in ohms, 0.25 w. 10% cc., and the capacitor values are in microfarads, 50 v.

Exemplary electrode dimensions, using the general electrode configurations shown in FIG. 1, are 0.388" by 0.250 for the P, 0.294 by 0.250 for the S electrodes, 0.563" by 0.067 for the M electrodes, and 0.414 by 0.067" for the H electrodes. The body portions of the P and S electrodes are spaced by 0.205" with directing tabs 0.127" long; the M electrodes are spaced by 0.180" at the inner ends with directing tabs 0.102" long and located 0.187" from the inner ends of the electrodes; and the H electrodes are spaced by 0.223" at the inner ends and located 0.167",from the inner ends of the electrodes. The directing tabs all taper from a width of approximately 0.020 at the bases thereof to about 0.010" at the tips.

Using the above values, the anode voltage at the collector of the particular transistor Q1 or Q2 that is cut off is volts, and the normal glow discharge current is about 1.0 ma. for electrode series P and H, about 0.75 ma. for electrode series S, and about 1.5 ma. for electrode series H. The maintaining voltage is approximately 150 volts, the transfer voltage (to initiate glow discharge at primed electrodes) is about 200 volts, and the breakdown voltage (to initiate glow at unprimed electrodes) is about 250 volts.

We claim as our invention:

1. An improved timepiece comprising the combination of a glow discharge tube containing an ionizable gas and a series of spaced internal electrodes for counting successive time intervals in response to electrical input signals representing said time intervals, first electrical input means operatively connected to a first group of said electrodes and second electrical input means operatively connected to a second group of said electrodes, at least one electrode of said first group being located between each pair of successive electrodes of said second group and at least one electrode of said second group being located between each pair of successive electrodes of said first group, and electrical control means operatively connected to said first and second electrode groups for applying a transfer potential across successive pairs of adjacent electrodes in response to said electrical input signals so as to step the glow discharge along successive electrodes in said series with each electrode functioning alternately as cathode and anode.

2. An improved timepiece as set forth in claim 1 which includes a third electrical input means operatively connected to a third group of said electrodes with at least one electrode of said third group being located between each pair of successive electrodes of said first and second groups, and said electrical control means is operatively connected to said third electrode group as well as said first and second groups whereby each of said electrodes in said first, second, and third groups functions alternately as cathode and anode.

3. An improved timepiece comprising the combination of a glow discharge tube containing an ionizable gas and a plurality of spaced internal electrodes for counting successive time intervals in response to electrical input signals representing said time intervals, two or more electrical input means operatively connected to two or more groups of said electrodes, each pair of successive electrodes in each one of said groups having at least one electrode of each other group located therebetween, electrical control means operatively connected to said electrical input means for cyclically applying a transfer potential across different pairs of said electrode groups in sequence so as to repetitively transfer a glow discharge from an electrode of one group directly to an adjacent electrode of another group thereby stepping the glow discharge sequentially along said plurality of electrodes with each electrode group functioning aternately as cathode and anode.

4. An improved timepiece comprising the combination of a glow discharge tube containing an ionizable gas and a series of spaced internal electrodes for counting successive time intervals in response to electrical input signals representing said time intervals, first electrical input means operatively connected to a first group of said electrodes and second electrical input means operatively connected to a second group of said electrodes, at least one electrode of said first group being located between each pair of successive electrodes of said second group and at least one electrode of said second group being located between each pair of successive electrodes of said first group, an electrical control circuit operatively connected to said first and second electrical input means for applying a transfer potential for said glow discharge tube cyclically to said first and second electrode groups, one group at a time, in response to said electrical input signals so as to repetitively transfer the glow discharge directly between successive electrodes in said series, said control circuit including means for maintaining said glow discharge at each of said electrodes until the glow discharge is transferred to the next successive electrode whereby a continuous display of the instantaneous count or time is provided, said control circuit also including means for cyclically connecting successive electrodes in said circuit as anodes for the electrodes to which said transfer potential is applied whereby each individual electrode functions alternately as cathode and anode.

5. An improved timepiece comprising the combination of a glow discharge tube containing an ionizable gas and a series of spaced internal electrodes for counting successive time intervals in response to electrical input signals representing said time intervals, first electrical input means operatively connected to a first group of said electrodes and second electrical input means operatively, connected to a second group of said electrodes, at least one electrode of said first group being located between each pair of successive electrodes of said second group and at least one electrode of said second group being located between each pair of successive electrodes of said first group, electrical control means operatively connected to said first and second electrode groups for applying a transfer potential across successive pairs of adjacent electrodes in response to said electrical inputs signals so as to step the glow discharge along successive electrodes in said series with each electrode functioning alternately as cathode and anode, and directional control means operatively associated with said electrodes for automatically directing the successive glow discharge transfers continuously in the same direction.

6. An improved timepiece comprising the combination of a glow discharge tube containing an ionizable gas and a series of spaced internal electrodes for counting successive time intervals in response to electrical input signals representing said time intervals, alternate electrodes in said series being interconnected to form a first operative group of electrodes, and intervening electrodes in said series being interconnected to form a second operative group of electrodes, means for initiating a glow discharge at one of said electrodes, and means for applying a square wave across said first and second electrode groups for applying a transfer potential for said glow discharge tube alternately to said first and second electrode groups so as to step the glow discharge along successive electrodes in said series with each electrode functioning alternately as cathode and anode, said square Wave being synchronized with said electrical input signals so that the stepping movement of said glow discharge is also synchronized with said electrical input signals.

7. An improved timepiece comprising the combination of a glow discharge tube containing an ionizable ga and a series of spaced internal electrodes for counting successive time intervals in response to electrical input signals representing said time intervals, means interconnecting a first group of said electrodes to form a first operative electrode group, and means interconnecting a second group of said electrodes to form a second operative electrode group, means for initiating in a glow discharge at one of said electrodes, at source of transfer potential operatively connected to said electrodes, and first and second electronic switching means operatively connected to said source of transfer potential and said first and second electrode groups, and electronic control means responsive to said electrical input signals for turning said electronic switching means alternately on and off, said first switching means being off when said second switching means is on and vice versa, so as to apply said transfer potential alternately across successive pairs of adjacent electrodes so as to step the glow discharge along successive electrodes in said series in synchronism with said electrical input signals, with each electrode functioning alternately as cathode and anode.

8. An improved timekeeping method comprising the steps of providing a glow discharge tube containing an ionizable gas and a series of spaced internal electrodes in which a first group of said electrodes are interconnected to form a first electrode group and a second group of 13 charge at one of said electrodes, and applying a transfer potential across successive pairs of adjacent electrodes to step the glow discharge along successive electrodes in said series with each electrode functioning alternately as cathode and anode.

9. An improved timekeeping method as set forth in claim 8 in which said glow discharge tubeincludes a third group of interconnected electrodes with at least one electrode of said third group being located between each pair of successive electrodes in said first and second groups.

10. An improved timekeeping method comprising the steps of providing a glow discharge tube containing an ionizable gas and a series of spaced internal electrodes which are interconnected to form two or more electrode groups with each pair of successive electrodes in each of said groups having at least one electrode of each other group located therebetween, initiating a glow discharge at one of said electrodes, and cyclically applying a transfer potential for said glow discharge tube across ditferent pairs of said electrode groups in sequence to repetitively transfer the glow discharge of one group directly to an adjacent electrode of another group thereby stepping the glow discharge sequentially along said electrodes with each electrode group functioning alternately as cathode and anode.

11, An improved electronic counter comprising the combination of a glow discharge tube containing an ionizable gas and a series of spaced internal electrodes for counting successive electrical input signals, first electrical input means operatively connected to a first group of said electrodes and second electrical input means operatively connected to a second group of said electrodes, at least one electrode of said first group being located between each pair of successive electrodes of said second group and at least one electrode of said second group being located between each pair of successive electrodes of said first group, and electrical control means operatively connected to said first and second electrode groups for applying a transfer potential across successive pairs of adjacent electrodes in response to said electrical input signals so as to step the glow discharge along successive electrodes in said series with each electrode functioning alternately as cathode and anode.

12. An improved electronic counter comprising the combination of a glow discharge tube containing an ionizable gas and a plurality of spaced internal electrodes 10 for counting successive electrical input signals, two or more electrical input means operatively connected to two or more groups of said electrodes, each pair of successive electrodes in each one of said groups having at least one electrode of each other group located therebetween,

15 electrical control means operatively connected to said electrical input means 'for cyclically applying a transfer potential across difierent pairs of said electrode groups in sequence so as to repetitively transfer a glow discharge from an electrode of one group directly to an adjacent 20 electrode of another group thereby stepping the glow discharge sequentially along said plurality of electrodes with each electrode group functioning alternately as cathode and anode.

References Cited JAMES W. LAWRENCE, Primary Examiner 35 v. LAFRANCHI, Assistant Examiner US. Cl. X.R.