US1939071A

US1939071A - Impulse-actuated lock-in relaying system

Info

Publication number: US1939071A
Application number: US654644A
Authority: US
Inventors: Thomas H Long
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1933-02-01
Filing date: 1933-02-01
Publication date: 1933-12-12
Anticipated expiration: 1950-12-12

Description

Dec. 12, 1933. L 1,939,071

IIPULSE-ACTUATED LOCK-IN RELAYING SYSTEM Filgd Feb. 1. 1933 l Circa/7f I I I I I I'I I I Scum of Siyna/ impulses. 9

WITNESSES: INVENTOR ATTORNEY Patented Dec. 12, 1933 PATENT OFFICE IMPULSE-ACTUATED LOCK-IN RELAYING SYSTEM Thomas H. Long, Irwin,

Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application February 1, 1933. Serial No. 654,644

12 Claims.

My invention has particular relation to the problem of securing a relaying action, or other control-circuit operation, in response to a signal impulse of shorter duration than has been utilizable for control purposes prior to my invention. In sorting applications, where a light-responsive device is utilized to scan an object or objects for the purpose of sorting, or for the purpose of detecting discolorations therein, it is desirable to speed up the process as much as possible, but prior to my invention, this speeding-up process was limited by the fact that if the signal were ,too brief, it would not lock-in (including the thought of locking-out) a relaying circuit so as to make possible the operation of some control device therefrom. The shortest duration of signal which could thus be utilized, prior to my inention, was of the order of micro-seconds.

The principal object of my invention is to devise some practical means for utilizing an electrical signal of very brief duration, preferably of the order of a few micro-seconds, or even less. I am not limited to any particular application of my relaying system, as in sorting applications, but the same may be utilized in rapid counters, or to prevent chattering which would result from other relaying devices, particularly devices of the so-called balance type, or for other purposes.

A more particular object of my invention is to provide a relaying system of the class described, utilizing what is sometimes known as a flat vapor-arc rectifier, or an evacuating are device comprising two spaced main electrodes in an evacuated tank, with a make-alive electrode in continuous contact with oneofthe main electrodes, forming a cathode spot on the latter when the make-alive electrode is suitably energized, as by passing a few amperes of direct current therethrough from the make-alive electrode to the main electrode on which the cathode spot is to be formed. Such a make-alive electrode may be a resistance rod, such as a molded carborundum material having clay binder or other binder which does not emit gases under operating conditions, or other poorly conducting material which is not destroyed under the operating conditions. The particular effect of such a makealive means is that there is no arc, or other source of electron-emission, in the tank during the period when there is no are playing between the main electrodes, so that, after the current-flow in the main-arc circuit is interrupted, the main arc will not restrike until the make-alive electrode is suitably energised.

With the foregoing and other objects in view, my invention consists in the apparatus and systems hereinafter described and claimed and illustrated in the accompanying drawing, the single figure of which is a diagrammatic view of circuits and apparatus embodying my invention in a preferred form.

As shown in the drawing, my relay system utilizes a source of signal impulses, by which I mean a source for supplying an electrical signal of extremely brief duration, preferably of the order of a few micro-seconds or even less. The signal may be any change in current or voltage, not usually involving a complete cessation of current or voltage in the signal circuit at any time.

For example, if the signal circuit comes from" the amplifying equipment of a scanner utilizing a light beam, its voltage normally will be, say, 1000 volts, which may be reduced to 900 volts for a brief moment of time during the signal impulse, when the scanning light beam flashes over a discoloration on the object scanned. The signal circuit is indicated on the drawing by the numeral 1.

For responding to the signal impulses, I utilize a control means 2 having a control circuit 3, which is responsive to the signal, and a main circuit 4. The control means 2 is shown as a three-electrode amplifier tube having an anode 5, a grid 6, and a hot cathode 7, the anode and the cathode being disposed in the main circuit, while the control circuit is connected to the grid and to the cathode. The grid 6 is connected to the cathode '7 by means of a grid-leak circuit comprising a grid-leak resistor 8 and sometimes also a small biasing battery 9 for reducing the current normally flowing through the grid. The grid 6, with its grid-leak circuit, is coupled to the source of signal impulses through a coupling capacitor 11 in such a way that the expected, change in the signal-circuit conditions, which constitutes the signal, causes current to flow through the capacitor 11 momentarily in the direction from the grid to the signal circuit, as indicated by the signs and in the drawing.

The main circuit 4 also includes, in series relation therein, an arcing device,'such as the flat rectifier 12 which was referred to in the opening paragraphs of this specification. The drawing shows this rectifier diagrammatically as comprising a main anode 13, a cathode 14 of mercury or other vaporizable reconstructing material, and a make-alive electrode 15. The main circuit 4 is normally completed by means of an are passing from the main anode 13 to the cathode 14.

The main circuit 4 also includes a control device or relay 16 for performing the useful function which is required of the relaying system. As shown, the control device 16 is represented as a relay element comprising an actuating coil 17, which is in series circuit relation with the main circuit 4, and one or more movable contact devices 18 and 19. The first contact device 18 may close first, upon the deenergization of the relay, (the relay being normally energized), and may thus be utilized to energize any desired controlled circuit 21, as indicated.

The main circuit 4 is completed by a high-voltage battery 22 which supplies direct current passing through the relay coil 1'], the fiat rectifier 1314 and the amplifier tube 2, returning from the cathode '7 of the latter to the negative terminal of the battery 22.

In operation, the grid 6 of the amplifier tube is normally not active, carrying only a few milliamperes, and permitting the amplifier to carry its normal plate-circuit current, which flows through the main circuit including the fiat rectifier 12 and the relay coil 1'7. In general, the fiat rectifier, being an arcing device, requires a sufiicient current, perhaps of the order of at least one-fourth of an ampere, in order to maintain the arc and hold the relay 16 in its normal actuated condition.

The source of signal impulses is so designed, with detectors and amplifiers, that the signal impulse consists of a sudden drop in the voltage applied to the coupling capacitor 11. For example, the signal-source side of the coupling capacitor may suddenly be made 100 volts more negative than it was before the signal came in. Current will immediately flow through the grid-leak resistor 8, thus imposing on the grid 6 a voltage which is usually not a great deal less than the signal voltage, say, volts, for example. This voltage is sufiicient to interrupt the fiow of platecircuit current through the tube 2, thus also interrupting the arc current in the fiat rectifier 12, causing the cathode spot in the latter to disappear.

It will be noted that the fiat rectifier 12 may be any arcing device comprising two spaced stationary main. electrodes 13 and 14, one of which is always non-electron-emitting and the other one of which emits electrons from its cathode spot when an arc is playing from it to the main anode, but at no other times. It is not essential that the electrode on which the cathode spot appears shall be of a special cathode material,' as a cathode spot may be formed on any conductor, so as to initiate the arc. It is essential, however, that the space between the two main electrodes 13 and 14 shall be subjected to such strong deionizing influence that an arc will not restrike between said electrodes even though voltage is re-applied thereto, after an interruption of the arc, with only a moment's delay, such as 3 or 4 micro-seconds, or even less than 1 micro-second. Such strong deionizing influence may include anything which will quickly deionize the space between the main electrodes, so that the breakdown voltage between the electrodes quickly assumes a sufficiently high value to prevent restriking immediately after the main arc goes out at any time. A very effective deionizing influence of this sort is a good vacuum, such as is ordinarily provided in mercury-arc rectifiers.

therein, and in utilizing a make-alive which is dead during the non-arcing periods, rather than utilizing a keep-alive which is arcing, and thus supplying ions and electrons to main arcing space, all during the'non-arcing period, as in the type of mercury-arc rectifier that hasheretofore been the usual type.

At the same time that the arc is extinguished I in the fiat rectifier 12, as a result of the blocking f or interruption of the main-circuit current l through the amplifier tube 2, the exciting current is interrupted in the relay 16, thus causing this relay to drop its movable contacts 18 and 19.

The principal contacts 18 are shown as closing a circuit 21 for doing the useful work which should be done in response to the signal impulse. The

other movable contacts 19 of the relay are auxiliary contacts which may or may not be utilized,

being shown as energizing the make-alive 15 of the fiat rectifier, from any suitable source such as the battery 24. These auxiliary contacts 19 may either close simultaneously with the main 1 contacts 18, or, preferably, may close slightly later. Assuming that the high negative potential on the grid 6 has meanwhile disappeared, the 1 main arc in the fiat rectifier 12 will practically instantaneously start, as soon as the make-alive electrode 15 is suitably energized from the makealive battery 24,- and a current will thus be reapplied to the energizing coil 1'7 of the relay, causing the latter to begin to pickup its contacts 18 and 19, there being a sufficient sluggishness in this action to enable the controlled circuit 21 to perform its intended useful function.

In order to prevent the application of an extremely high voltage across the main electrodes of the fiat rectifier while the current is collapsing, or becoming zero, in the highly inductive actuating coil 17 of the relay, after an interruption of the main arc circuit, it is very desirable to utilize a small capacitor 25 connected across the relay coil 17 to prevent the presence ot such a high voltage. Otherwise, the high voltage induced in the inductive circuit 1'7 might persist longer than the duration of the signal impulse, and longer than the duration of the high negative bias on the grid 6, thus causing the main arc to restrike prematurely, if the induced voltage was higher than the break-down voltage which could be withstood by the arc space of the fiat rectifier at the moment.

In connection with the coupling capacitor 11 in the grid circuit of the amplifier tube 2, it is preferable that the time constant of this capacitor and the grid-leak resistor 8 shall be at least as long as the minimum expectable duration of signal to which the relay system is adapted to respond, and preferably the time constant should be from 10 to times said duration of signal. Thus, this time constant is the time during which current will fiow, from the hot-cathode conductor and the grid-leak resistor 8, to the coupling capacitor 11, for the purpose of re-adjusting the capacitor-charge to the voltage conditionsexisting in the signal circuit while the signal impulse is being received. While the coupling capacitor 11 is thus charging, or readjusting its charge, the grid 6 gradually becomes less negative, until, at the end of the time constant, it would be restored a large part of the way back to its normal, non-blocking potential. It is thus necessary for the time constant of the capacitor-resistor circuit 118 to be sumciently high to insure that the grid 6 shall not return to its non-blocking potential within the expected duration of the brief signal impulse.

While I have shown my invention in but a single preferred application, and in but a single form of embodiment, it will be obvious that many changes may be made by those skilled in the art, without departing from the essential thought and spirit of my invention. I desire, therefore, that the appended claims shall be accorded the broadest construction consistent with their language and the prior art.

I claim as my invention: i

1. A relay system for obtaining a lock-in response from an electrical signal of very brief duration, comprising a control means having a control circuit and a main circuit so related that said control circuit is adapted to respond instantaneously to said signal to momentarily interrupt the current-flow in said main circuit, said main circuit comprising, in series relation therein, an arcing device comprising two spaced main electrodes between which an arc plays to carry the current normally flowing in said main circuit, said spaced electrodes being subjected to such strong deionizing influence that an arc will not restrike therebetween even though the currentflow is interrupted only momentarily by said control means, a source of current supply for said main circuit, and a control device responsive to the current-flow in said maincircuit.

2. A relay system' for obtaining a lock-in response from an electrical signal of very brief duration, comprising a control means having a control circuit and a main circuit so related that said control circuit is adapted to respond instantaneously to said signal to momentarily interrupt the current-flow in said main circuit, said main circuit comprising, in series relation therein, an arcing device comprising two spaced main electrodes between which an arc plays to carry the current normally flowing in said main circuit, said spaced electrodes being subjected to such strong deionizing influence that an arc will not restrike therebetween even though the currentflow is interrupted only momentarily by said control means, a source of current supply for said main circuit, an electromagnetic relay having an actuating winding energized from said main circuit, and acapacitor shunting said actuating winding.

3. A relay system-for obtaining a lock-in response from an electrical signal as brief as a' few micro-seconds, or less, in duration, comprising a control tube having a control circuit and a main circuit so related that said control circuit is adapted to respond instantaneously to said signal to momentarily interrupt the current-flow in said main circuit, said main circuit comprising, in series relation therein, an evacuated arcing device comprising two spaced main electrodes between which an arc plays to carry the current normally flowing in said main circuit, a source of current supply for said main circuit, and a control device responsive to the current-flow in said main circuit, said evacuated arcing device being of a type which will not restrike its are when its voltage is restored after a brief interruption for the duration of the signal.

4. A relay system for obtaining a lockin response from an electrical signal as brief as a few micro-seconds, or less, in duration, comprising a control tube having a control circuit and a main circuit so related that said control circuit is adapted to respond instantaneously to said signal to momentarily interrupt the current-flow in said main circuit, said main circuit comprising, in series relation therein, an evacuated arcing de- -vice comprising two spaced main electrodes be-' 5. A relay system for obtaining a lock-in response from an electrical signal as brief as a few micro-seconds, or less, in duration, compris ing a control tube having a control circuit and a main circuit so related that said control circuit is adapted to respond instantaneously to said signal to momentarily interrupt the currentflow in said main circuit, said main circuit comprising, in series relation therein, an evacuated arcing device comprising two spaced stationary main electrodes between which an arc plays to carry the current normally flowing in said main circuit, said main electrodes comprising one electrode which is always substantially non-electronemitting and another electrode which ceases emitting electrodes substantially instantaneously upon an interruption of the arc, a source of current supply for said main circuit, and a control device responsive to the current-flow in said main circuit.

6. A relay system for obtaining a lock-in response from an electrical signal as brief as a few micro-seconds or less, in duration, comprising a control tube having a control circuit anda main circuit so related that said control circuit is adapted to respond instantaneously to said signal to momentarily interrupt the current-flow in said main circuit, said main circuit comprising, in series relation therein, an evacuated arcing device comprising two spaced stationary main electrodes between which an arcplays to carry the current normally flowing in said main circuit, said main electrodes comprising a main anode and a vaporizable reconstructing cathode, enclosed in an evacuated tank containing no other source of electron emission when the main-electrode arc is extinguished, asource of current sup-- ply for said main circuit, and a control device responsive to the current-flow in said main circuit.

7. A relay system for obtaining a lock-in response from an electrical signal as brief as a few micro-seconds, or less, in duration, comprising a control tube having a cathode, a grid and an anode, a grid-leak circuit between the grid and the cathode and including a grid-leak resistance, and a capacitor for coupling the grid to the incoming electrial signal in such a manner that the grid becomes strongly negative for the duration of the signal, the time constant of the capacitor and the grid-leak resistance being longer than the minimum expectable duration of signal to which the relay system is adapted to respond, 9. main circuit serially including said anode and said .cathode as apart thereof, said control tube being adapted to respond instantaneously to the incoming electrical signal to substantially block the current-flow in said main circuit for substantially the duration of said signal, said main circuit comprising, in series relation therein, an arcing device comprising two spaced main electrodes, between which an arc plays to carry the current normallyflowing in said main circuit, said spaced electrodes being subjected to such strong deionizing influence that an arc will not restrike therebetween even though the currentflow is interrupted only for the minimum expectable duration of signal to which the relay system is adapted to respond by said control tube, a source of direct-current supply for said main circuit, and a control device responsive to the current-flow in said main circuit.

8. The invention as defined in claim 1, characterized by said arcing device having a makealive electrode in continuous contact with one of the main electrodes for forming a cathode spot on the latter when the make-alive electrode is suitably energized, and means for suitably energizing said make-alive electrode after the control device has accomplished its principal purpose.

9'. The invention as defined in claim 3, characterized by said arcing device having a makealive electrode in continuous contact with one of the main electrodes for forming a cathode spot on the latter when the make-alive electrode is suitably energized, and means for suitably energizing said make-alive electrode after the relay has accomplished its principal purpose.

10. The invention as defined in claim 5, characterized by said arcing device having a makealive electrode in continuous contact with one of the main electrodes for forming a cathode spot on the latter when the make-alive electrode is suitably energized, and means for suitably energizing said make-alive electrode after the control device has accomplished its principal purpose.

11. The invention as defined in claim 6, characterized by said arcing device having a makealive electrode in continuous contact with one THOMAS H. LONG.