US2899675A - Failure circuit for counting chains - Google Patents

Description

Aug. 11, 1959 M. A. CLEMENT FAILURE CIRCUIT FOR COUNTNG CHAINS Filed March 5, 1957 INVENTOA BY We l i. 50671 ATTORNEY llmobm mmnSn.

Unite FAILURE CIRCUIT FOR COUNTING CHAINS Application March 5, 1957, Serial No. 644,020

4 Claims. (Cl. 340-248) This invention relates to counting chains and, more particularly, to a circuit responsive to the failure of a pulse- -operated counting chain.

Pulse counting chains are well known in the art, and may consist of a plurality of elements each of which has two discrete operating conditions which may be characterized as an on condition, indicative of a count, and an olf condition. The elements themselves are usually composed of gas discharge devices, vacuum tubes or relays, and are so interconnected that at all times at least one element is in the on condition. The switching of a particular element in the chain from an off condition to an on condition is dependent on two things; namely, that a pulse -be applied to this particular element and that the element in the chain immediately preceding this particular element be in an on condition.

It will be seen, therefore, that successive elements in the chain are switched on in response to successive pulses applied thereto.

Depending upon the specific type of pulse-operated counting chain employed, the switching of a particular element to an on condition may or may not be effective in switching some or all of the preceding elements in the chain which are in an on condition to an olf condition.

In addition, a pulse-operated counting chain may be open ended or it may be connected in a ring. In case of an open-ended counting chain, the maximum number of pulses which can be counted is equal to the number of elements in the chain, and in order to start a new cycle, external reset means must be employed. In the case of a ringeconnected chain, the rst element in the chain is switched from an off condition to an on condition in response to a pulse being applied thereto and the last element in the counting chain being in an on condition.

From the foregoing discussion it will be seen that although pulse-operated counting chains may differ from one another in many particulars, they are all characterized the fact that they depend for their proper operation upon some one element in the chain being switched from a rst discrete operating condition to a second discrete operating condition in response to each pulse applied to the chain. However, if an element is defective it will not be switched when it should in response to a pulse, andthe counting chain will fail to operate. Since a pulseoperated counting chain may be utilized in a complex system for controlling the sequence of operation of a plurality of other circuits in the system, it will be seen that an unindicated failure of the counting chain can be disastrous.

This invention contemplates a circuit responsive to a pulse applied to the chain and the failure of an element of the chain to be switched to `an on condition thereby for indicating such a failure.

It is therefore an object of this invention to provide means for indicating the failure of a pulse-operated counting chain.

Patent O 2,899,675 Patented Aug. 11, 1959 It is a further object of this invention to provide means, in cooperative relationship with the pulse-operated counting chain comprising a plurality of elements each having a discrete on condition and a discrete off condition, for indicating the yfailure of any element of the chain to be switched to an on condition during the time interval that a pulse is being applied thereto.

It is a still further object of this invention to provide means, in cooperative relationship with a pulse-operated counting chain comprising a plurality of elements each Ahaving a Vdiscrete on condition and a discrete o condition, for giving an alarm and/or stopping the further application of pulses to the chain in response to the failure of any elements of the chain to be switched to an on condition during the time interval that a pulse is being applied thereto.

Although the features of the invention which are believed to be vnovel are set forth with particularity in the appended claims, these and other objects of the invention, as well as its organization and method of operation, can best be understood by reference to the following description taken in conjunction with the accompanying drawing, in which the sole ligure illustrates a preferred embodiment of the invention in cooperative relationship with a typical pulse-operated counting chain.

Referring now to the drawing, there is shown a typical pulse-operated counting chain utilizing cold-cathode triodes as elements thereof. Counting chain 100 consists of priming triode 102-0 and two or more pulse counting triodes 102-1 to 102-N (only the first and last of which have `been shown in the drawing).

Cathode 104-0 of priming triode 102-0 is connected to a point of reference potential through resistance 106-0, which is by-passed by capacitance 1118-0. In a similar manner the cathodes 104-1 to 104-N of counting triodes 102-1 to 102-N, respectively, are connected to the point of reference potential through resistances 106-1 to 106-N, respectively, which are by-passed by capacitances 1084 to 10S-N, respectively.

Cathode 104-0 of priming triode 102-0 is coupled -to control electrode 110-1 of the rst counting triode 102-1 through serially connected resistances 112-1 and 114-1. Resistance 112-1 has a high value relative to both resistances 106-1 and 114-1. The control electrode of each succeeding counting triode is coupled to the cathode of the counting triode immediately preceding it in an identical manner, control electrode 110-N of the last counting triode 102N being connected to the cathode of the next to the last counting triode through serially connected resistances 112-N and 114-N. Pulses from pulse vinput source 116, |which may be controlled or uncontrolled, are applied to lthe respective junctions of resistances 112-1 to 112N and 114-1 to 114-N through capacitances 118-1 to 11S-N, respectively, as shown. Thus, the input circuits of all the counting triodes in the chain are identical.

Anodes 120-0 of priming triode 102-0 and anodes 120-1 to 1Z0-N of counting triodes 102-1 to 102-N are connected in parallel to a point of positive potential B-lthrough resistance 122, as shown.

VA'voltage divider consisting of serially-connected resistances 124 and 126 is coupled between the point 0f positive potential and the point of reference potential. The potential appearing at the junction of resistances 124 and 126 is applied to control electrode 110-0 of priming triode 102-0 through normally-open reset switch 128 and resistance 130. An integrating circuit composed of resistance 132 and capacitance 134 is connected between the junction of reset switch 128 and resistance 130 and the point of reference potential, as shown.

The cathodes 104-0 to 104-N, respectively, of each triode of the chain is connected to a respective output V3 conductor designated output O to output N, respectively. In addition, if it is'wished fto control the start of "pulsing of pulse input source 116, a pulse start conductor is connected between cathode 104-0 of .priming triode 102-'0 and pulse input source 116.

In cooperative relationship with counting chain 100 is the failure circuit contemplated by this invention. This failure circuit comprises a cold-cathode `triode 136 having a cathode 138, an anode 140 `and a control electrode 142. Cathode l13S is connected to the point of reference potential through resistance 144, and anode 140 is connected -to the point of positive potential through normally closed switch 146 yand current-operated failure indicating means 148. If it is wished to control pulse input source 116 to stop further pulsing in response to the operation of current-operated failure indicating means 148, a pulsestop conductor is connected between current-operated failure indicating means 148 and pulse input source 116. Current-operated failure indicating means 148 may include an alarm responsive to the operation thereof and/ or means yfor placing a signal potential on the pulse stop conductor in response "to 'the operation thereof. This may Vbe accomplished by means `of a current-operated relay, for instance.

Pulses vfrom pulse input source 116 are applied to control Velectrode 142 of triode 136 through seriallyconnected capacitance 150 and resistances 152 and 154.` The Ajunction- ot resistances 152 and 154 is connected to the point'of reference potential through a large resistance 156 shunted by serially-connected capacitance v158 and resistance v160.

In addition, output 1 to output N of counting triodes 102-1 to 102-N are connected to cathode -138 of triode `136 through an input circuit consisting of `unidirectional conducting devices 162-1 to 162-N, poled as shown, and resistance 164 and capacitance 166.

A cycle of operation of the counting chain is initiated 'by momentarily closing reset switch 128. This causes the positive potential at the junction of resistances 124 and 126 of the voltage divider tobe applied to control electrode 110-0 of priming triode 102-0 to eiect Ythe vfiring thereof. The presence of the integrating circuit consisting of resistance 132 and capacitance 134 assures that the ring potential will be applied for a sufficient time to tire priming triode 2-0 even lit reset switch 128 is reopened very-quickly.

The iiring of priming triode 102-0 provides a-conduction path extending from the point of positive potential through resistance 122, the anode and cathode of priming triode 102-0 and resistance 106-0 'to the point of reference potential, and results in a voltage drop across yresistance 106-0 which places cathode 104-0 Vat some positive potential. This positive potential causes capacitance 10S-O to become charged and also positively biases control electrode 11G-1 of therst counting triode 102-1 through serially connected resistances 112-"1 and 114-1. AIn addition, the positive potential on cathode 104-0 is applied to the output O conductor Where it `may be utilized to condition some other circuit for operation.

If pulse input source 116 is controlled, positive 4potential is applied thereto over the pulse start conductor to thereby eect'the initiation of pulsing by pulse input source 116. Each of the pulses from pulse input source 116 is applied through capacitances 118-1 to "11S-N and resistances 114-1 to 114-N, respectively, to control electrodes 1'10-1 to 110-N of counting triodes -102-1 to 102-N, and is also applied Ythrough capacitance 150 and 'resistances 152 and `154 to control lelectrode 142 of triode 136.

The amplitude of each'of the dpulses applied to control electrodes 110-'1 'to 1'10-N, respectively, is insuftcient, by itself, to re any of the counting-triodes 102-1 to r1M-N. 'Howeven when the controlv electrode vof a' counting triode is positively biased, the sum of the positive bias and the amplitude of the pulse is suioient to tire this triode. Therefore, in response to the rst pulse, only the first counting triode 102-1 will be red, since it is the only one having a positive bias applied to its control electrode at this time.

The initiation of conduction through first counting triode 102-1 provides a voltage drop across resistance 122 in addition to that provided by priming triode 102-0, to thereby lower the anode-cathode voltage across priming triode 102-0 sufficiently to cause it to extinguish. Since it is the initiation of conduction of iirst counting triode 1112-1 which causes priming triode 102-0 to extinguish, it should be understood that there is a short interval of time prior to the extinction of priming triode 102-0 when both triodes 102-0 and 102-1 are conducting.

The initiation of conduction through first counting triode 101-1 causes cathode l1414-1 thereof to rise quite quickly in potential, applying a positive voltage `to the output 1 conductor, where it conditions some second other circuit for operation. The extinction of priming triode 102-0 4causes the previously described positive potential on the output lO conductor to decay at a relatively VAslow rate due to the discharge time constant of capacitance 10S-O.

The quick rise in potential on cathode 104-1 also causes a positive pulse to be applied to cathode 138 of triode 136 through unidirectional conducting device 162-1 and capacitance 166, which presents a small impedance to the quick rise.

When tirst counting triode 102-1 is conducting, the positive potential on its cathode 104-1 positively biases the control electrode of the second counting triode in the chain, so that it will tire in response to the second pulse from pulse input source 116 and cause rst counting triode y1112-1 to be extinguished, in an identical manner to that previously described. Therefore, yeach subsequent pulse is effective in firing the next succeeding counting triode and in extingiushing the preceding triode.

In response to the tiring of each counting triode, the quick rise in potential on its cathode causes a pulse `to be applied -to cathode 138 lof triode 136 through the unidirectional conducting device individual thereto in the manner previously described. The extinction ofthe preceding counting triode is of negligible eiect Yso Yfar as ytriode 136 is concerned, since capacitance 166 presents a large impedance to the relatively slow decay-of the positive potential on the cathode of the preceding-counting triode.

At any time during the cycle, or at `the end of the cycle when t'he last counting tri-ode 102-N isi-conducting, a new cycle may be initiated by momentarily closing reset switch 128. This causes primingf'triode Y10'2-0 to lire, in the manner previously described, and `the Yring thereof is effective in extinguishing that triode in the counting chain which is conducting at this time because of the added voltage drop in resistance 122.

As previously described, each pulse is applied to control electrode 142 of triode 136 'through capacitance 150 and resistances 152 and V154. However, due to the time constant provided by capacitances 'and '158 `and resistances 152 and 160, `the -potential at control electrode 142 does not rise immediately in response to the initiation of a pulse, but rises relatively slowly during the interval ofthe pulse. The potential on control electrode'1'42 does, nevertheless, ultimately reach a value which would bersuiiicient to re triode 136 if it were Ynot vfor the previously described pulse applied to oathode 138 of triode V1256 'in'response to the tiring of the next triode in the counting chain. Thus, 'so 'long as 'the counting-chain is operating properly, triode 'V136 will not fire.

However, 'if one of the triodes in the counting chain is defective, sothat it does not iire in response to afpulse `applied thereto wlhen its control electrode is positively biased by the preceding triode, its cathode will not rise in potential, and no positive pulse will be applied through the unidirectional conducting device individual thereto and capacitance 166 to cathode 138 of triode 136. in this case, the pulse-derived potential on control electrode 142 of triode 136 will cause it to fire when it rises suiiiciently, `since there is no counter-'balancing pulse applied to cathode 138. The firing of triode 136 renders it conducting and is effective in operating current-operated failure indicating means 148 which, when operated, provides an alarm and/ or provides a signal potential on the pulse stop conductor for stopping further pulsing of pulse input `source 116. Triode 136 remains conducting and currentoperated failure indicating means 148 remains operated until normally closed switch 146 is opened.

While there has been described what is at present considered to be a preferred embodiment of the invention, it will be obvious to those skilled in the art the various changes and modifications which may be made therein without departing from the invention, and it is aimed in the appended claims to cover all such changes and modifications as `fall within the true spirit and scope of the invention.

I claim:

1. First means including a pulse-operated counting chain, wherein said chain includes a first terminal adapted to be coupled to a source of pulses of a given amplitude, a plurality of cold-cathode discharge devices each having a cathode, anode, and control electrode, individual second means comprising a first resistance shunted by a rst capacitance connecting the cathode of each of said devices to a point of reference potential, a second resistance connected between a point of positive potential and the anodes of all of said devices, third means for momentarily applying a positive potential to said control electrode of the first device of said chain to effect the conduction thereof, individual fourth means connecting the control electrode of each device following said first device to the cathode of the immediately preceding device of the chain to thereby bias each of these control electrodes at the potential of the cathode to which it is connected, fifth means coupled between each fourth means and said first terminal for applying pulses to the control electrodes of each of said devices following said first device, said given amplitude being per se insuicient to cause firing of a device of said chain but when added to the bias provided by a conducting preceding device being sufficient to normally cause firing of that device; and in combination therewith sixth means for indicating the failure of a device of said chain -to be fired by a pulse applied thereto, wherein said sixth means includes a second terminal, a third resistance coupled between said second terminal and said Ipoint of reference potential, individual unidirectional ccnducting means connecting the cathode of the cathode of each device following said iirst device to said second terminal, each unidirectional conducting means being poled to be conductive when the cathode to which it is connected is at a positive potential, 4another coldcathode discharge device having a cathode, anode and control electrode, a fourth resistance connecting said cathode of said other device to said point of reference potential, a second capacitance coupling said cathode of said other device to said second terminal, seventh means -including current-operated failure indicating means connecting the anode of said other device to a point of positive potential, and an input circuit for coupling the control electrode of said other device to said first terminal for applying pulses thereto.

2. The combination defined in claim 1, wherein said input circuit includes a first serially-connected resistance land capacitance coupled between said first terminal and `said control electrode of said other device, and a second serially-connected resistance and capacitance coupled 'Jetween said control electrode of said other device and said point of reference potential.

3. The combination defined in claim 1, wherein said first means further includes a controlled source of pulses coupled to said first terminal, and eighth means coupled between said current-operated failure indicating means and said source of pulses to effect the stoppage of said source of pulses in response to the operation of said current-operated failure indicating means.

4. The combination defined in claim 3, wherein said source of pulses is normally unoperated, and wherein said first means further includes ninth means coupled between the cathode of said first device of said chain and said source of pulses for initiating the operation thereof to provide a series of pulses in response to a positive potential being present on the cathode of said first device of said chain.

References Cited in the file of this patent UNITED STATES PATENTS 2,589,465 Weiner Mar. 18, 1952 2,597,428 Bachelet May 20, 1952 2,623,108 Holden Dec. 23, 1952

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