US2181972A

US2181972A - Control apparatus

Info

Publication number: US2181972A
Application number: US196919A
Authority: US
Inventors: Herrick Roswell Harry
Original assignee: Associated Electric Laboratories Inc
Current assignee: Associated Electric Laboratories Inc
Priority date: 1938-03-19
Filing date: 1938-03-19
Publication date: 1939-12-05
Anticipated expiration: 1956-12-05
Also published as: GB526501A

Description

Dec. 5, 1939. R. H. HERRICK 3 CONTROL APPARATUS Filed March 19, 1958 ATTORNE 'Y$.

a a j 1" I Vo/faqe a. q 1 l v ohn- P P J, B i F 2 Mm I ROSWELL H. HERRICK m Patented Dec. 5, 1939 UNITED STATES CONTROL APPARATUS Roswell Harry Herrick, Oak Park, IlL, assignor to Associated Electric Laboratories, Inc., Chicago, 11]., a corporation of Delaware Application March 19,

12 Claims.

The present invention relates to control apparatus and more particularly to improvements in impulse responsive relay networks wherein electronic devices are utilized to control electro- 'magnetic relays comprising impulse repeating apparatus. I

In an arrangement of the character mentioned, the input or control voltage is usually impressed on the input electrodes of an electron discharge device having included in its output circuit a control relay or other electromagnetic control device which is traversed by theanode current of the controlling electron discharge device: In time, the anode current flowing through the relay winding causes residual magnetism to be developed in the core of the relay. As a consequence, the relay is prevented from properly responding to variations in the voltage impressed on the input electrodes of the controlling electron discharge device. This problem is particularly troublesome in networks wherein the control relay and the electron discharge device arearranged to respond to the impulses of an impulse train, such, for example, as impulse trains of the character utilized in controlling automatic switches conventionally used in automatic telephone systems. More particularly, in an impulse responsive network of this character, it is highly desirable to utilize the steep linear portion of the grid voltage-anode current characteristic of the electron discharge device asthe operating range within which the grid voltage is varied in response to received impulses. By utilizing this portion of the characteristic curve, it is possible to obtain the maximum change in the anode current traversing the control relay winding for a given change in the input voltage impressed on the input electrode of the electron discharge device. When this portion of the-characteristic curve is used, however, the electron discharge device usually is not, even during. periods of non-use,

biased beyondcutoiI and; hence, a steady direct anode current continuously traverses the winding- 1938, Serial No. 196,919

positive response of the control device to changes in the input voltage impressed on the input electrodes of the electron discharge device is at tained.

It is a further object of the invention to provide an improved impulse responsive network of the form described wherein the character of the output or repeated impulses is, within limits, substantially independent of the character oi the received impulses. 10

In the illustrated embodiment of the invention, there is shown a pulsing relay including a winding and a control armature, a condenser, a source of potential for charging the condenser, and a. second relay for alternately connecting the condenser to be charged from the source and to discharge through the winding of the pulsing relay, thereby to cause alternate operation and restoration of the control armature. For the purpose of controlling the second relay, there is provided an electron discharge device including an input electrode and output electrodes, with suitable apparatus for impressing pulses of input voltage on the input electrode. The second relay, mentioned above, is connected. and arranged to be energized in accordance with the current flowing in the output circuit of the electron discharge device. In order to render this second relay positive in operation or to obviate the difliculty as mentioned above, there is also provided circuit apparatus for passing a second current through the winding of the second relay in opposition to the. anode current of the electron discharge device, and of a magnitude substantially different in one sense than the magnitude of the anode current when impulses of input voltage are impressed on the input electrode of the electron discharge device. Further to accomplish thisend, additional apparatus is provided for changing the magnitude of the anode current to a value different in the said one sense than the value of the second or opposing current during the intervals when no input voltage is impressed on the input electrode of the electron discharge device. By this arrangement, the direction of current flow through the winding of the second relay is reversed at the beginning and end of each pulse of input voltage impressed on the input electrode of the electron discharge device and theeflects of residual magnetism are substantially obviated. In order to render the repeated or output impulses of the impulsing relay substantially independent'of the pulses of input voltage applied to the input electrode of the electron discharge device, an additional impedance element is provided in shunt with the winding of the pulsing relay; and the impedance of the winding of the impulsing relay, the capacitance of the condenser for energizing this winding,and the impedance of the additional impedance element are so proportioned relative to each other that theratio of the restored intervals to the ,operated intervals of the pulsing relay is, within limits, independent of the ratio of the corresponding periods for the relay having its winding included in the output circuit of the electron discharge device.

The novel features believed to be characteristic of the invention are set forth with particularity in the appended claims. The invention,

' both as to its organization and method of opera- H and to repeat these impulses over a circuit including the terminals l2 connected to armature springs controlled by an armature l3 of a pulsing relay H. The network comprises an electron discharge device |5in the form of a vacuum tube having an input electrode or control grid Hi and a pair of output electrodes comprising a cathode l1 and an anode l8. The transformer II is provided with a secondary winding |9-which is coupled between the input electrode l6 and the cathode I! by a capacitance element 20. Coupled to the output electrodes of the device I5 is an output circuit which comprises the winding 2| of a control device or relay 22 and the portion 23 of a voltage dividing resistor 24. The resistor portion 24 and the winding 2| are by-passed for alternating currents by a capacitance element 25. In order that the grid voltage of the discharge device l5 may be varied withinthe optimum or steep linear portion of its grid voltage-anode current characteristic in response to pulses of input voltage during operation of the network, the source of bias voltage comprising the drop across the portion 26 of the resistor 24 is arranged to vbe. impressed by way of circuit connections including the secondary winding IQ of the transformer II on the input electrode ii. In order to obviate the difficulty mentioned above or to insure positive response of the relay 22 to variations in input voltage, a priming circuit is pro-' vided for passing a current through the winding 2| of this relay in opposition to the anode current normally flowing in the output circuit of the electron discharge device ID. This priming circuit includes'a portion 21 of the resistor 24 and a second resistor. 28 of relatively high resistance. A source of direct voltage, not shown, is connected between the terminals +13 and B of the voltage dividing resistor 24.

The relay 22 is provided with an armature spring 29 which is arranged to be-operatedbetween two contacts '3|l and 2| to control the energization and deenergization of the pulsing relay l4. More particularly, the armature 29 is connected to one electrode one. condenser '32 which side of the resistor portion 24.

is arranged to be charged over two conductors 33-and 34 from a source of voltage, not shown, but having its terminalsconnected to the

terminals

35 and 36. A circuit comprising the conductor 34 and a third conductor 31 is provided Fig. 1 may best be described by reference to the,

graph illustrated in Fig. 2. In brief, when the network is conditioned for operation and no alternating current impulses are impressed be tween the input terminals Ill of the transformer ll, two components of current are flowing through the winding 2| 'of the relay 22. The first of these components of current is the anode current which flows from the +B terminal of the voltage supply source by way of the anode IS, the electron stream between this anode and the .cathode I1, the winding 2| to the negative The magnitude of this first component of current is determined by the bias impressed on the input electrode I6 of the electron discharge device l5, and, preferably, this bias is chosen bf a value 6b which corresponds to the knee of ,the grid voltage-anode current curveA, whereby the steep linear portion of the curve lying between a and b may be utilized as the range within which the grid voltage is varied when an impulse of input current is impressed on the input terminals "I. With a bias voltage of en, the anode current or the first component of current flowing through the winding 2|.

"position to- .the anode current, since it flows from the positive side of the resistor portion 2'! by way of the winding 2| and the resistor 28 to the negative side of the resistor portion 21. Hence, the second component pf current may be designated as being of negative polarity. This I second component of current, the magnitude of which is indicated in Fig. 2 is at is is substantially diflerent in one sense; that is, it is substantially greater than the anode current in when no input voltage is impressed between the input terminals I of the transformer II. The net current flowing through the winding 2| is the diiference between the two currents i and in and is indicated in Fig. 2 as being of a magnitude in, which is of a negative polarity. The magnitude of the current in is maintained at a value less than the value of current required for operation of the relay 22 and, hence, this 'relay remains restored when no input voltage is impressed between the terminals l0. By

\ suitably proportioning the resistance value of pointed out that the resistance of the priming circuit and, more particularly, the resistor 28, is made high relative to the resistance of the winding 2 I, so that no substantial portion of the direct component of the anode current flowing in the output circuit of the device I5 is by-passed around the winding 2|.

With the relay '22 restored, the condenser 32 is connected by way of the circuit including the two

conductors

33 and 34, the contact and the armature 29 across the source of voltage connected between the terminals and 36. Thus, the condenser 32 is charged to the voltage existing between the

terminals

35 and 36. When a received pulse of alternating voltage, as indicated at B, is applied to the terminals Hi, this voltage is impressed between the input electrode I6 and the cathode l'l through the transformer H and the coupling condenser 20. On one-half of each cycle of this voltage, the negative potential on the electrode I6 is reduced to a value 61) so that the anode current is increased to a theoretical maximum value im. The average or effective value of the current flowing in the anode circuit of the device |5 during repeated positive half cycles of the input voltage is something less than the the opposing component current 1' flowingthrough the winding 2| as a consequence of the provision of the priming circuit. The difference between the two components of current is indicated at 1'0. This current is of a positive polarity and is above the value required to cause operation of the relay 22. As a consequence, this relay operates to move the armature 29 from engagement with thecontact 30 and into engagement with the contact 3| so that the charged condenser 32 discharges through the winding of the relay H and the condenser 38 in parallel. This current is sufficient to cause the operation of the relay I4 so that the armature 3 is moved into engagement with its associated contact to repeat the pulse over the circuit connected to the terminals l2. that the alternating input voltage 3 is no longer applied to the input electrode IS, the anode current is reduced from the average value in to the steady state value in. When this occurs, the priming current ip again predominates and the net current flowing through the winding 2| is reduced to the negative value in. Hence, the relay 22 is caused to restore to reconnect the condenser 32 to again be charged from the voltage cource connected to the

terminals

35 and 35.

During each succeeding pulse of input voltage impressed on the the electrode IS, the above-described sequence of operations is repeated;

From the foregoing description it will be ap parent that, during a series of received impulses, the direction of current flow through the winding 2| of the relay 22 is reversed at the beginning and the end of each pulse of input voltage. Thus, the effect of any residual magnetism which may be developed in the core of the relay 22 is substantially obviated. It will also be noted that, by normally biasing the discharge device |5 to the knee of its grid voltage-anode current characteristic curve, the steep and relatively linear portion of the curve lying between the points a and b is the operating range of the curve through which Obviously, when the pulse is ended, so

the grid voltage is normally varied when the input voltage pulses are impressed on the electrode I6. By biasing the tube to this point, the maximum change in the anode voltage is secured for a given change in the voltage applied to the electrode l6. tion of the specification, the particular arrangement of the circuit for energizing the pulsing relay I4 is such that the ratio of the closed contact period to the open contact period of this relay during each impulse may, within limits, be rendered independent of the ratio of the corresponding periods for the relay 22. More particularly, when the relay 22 is operated to connect the condenser 32 to discharge through the winding of the relay M, the time interval during which the last-mentioned relay will be sufiiciently energized to stay operated depends upon the time constant of the circuit including this winding, the condenser 38 and the charge condenser 32. By suitably proportioning the capacitance of the condenser 32, the capacitance of the condenser 38, and the impedance of the winding of the relay l4 relative to each other, the time constant of the circuit may be rendered such that the relay M will restore before the restoration of the relay 22 or, alternatively, willremain operated during the entire interval when the relay 22 is operated.

Again, by suitably proportioning the capacitance of the condenser 38 with respect to the impedance of the winding of the relay M, the demagnetization of this relay at the end of each period of 'energization may be delayed sufliciently so that the relay M will remain operated after the restoration of the relay 22. Thus, by suitably varying the capacitance values of the two

condensers

32 and 38, the portion of each impulsing period during which the relay I4 is operated may be varied within wide limits. By this arrangement, the ratio of the open circuit to the closed circuit periods of the circuit connected to the terminals |2 may be adjusted to suit the requirements of any particular application.

While there has been described what is at present considered to be the preferred embodiment of the invention, it will be understood that various modifications may be made therein, and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. An impulse responsive network comprising, in combination, a' first relay including a winding and a control armature, a condenser, a source of potential for charging said condenser, a second relay for alternately connecting said condenser to be charged from said source and to discharge through the winding of said first relay, thereby to cause alternate operation and restoration of said control armature, an elctron discharge device including an input electrode and output electrodes, means for impressing pulses of input voltage on said input electrode, an out- 1 put circuit coupled .to said output electrodes, said second relay including a winding connected and arranged to be energized inaccordance with the current flowing in said output circuit, means for passing a second-current through the winding of I said second relay in opposition to said first-mentioned current and of a magnitude substantially different in one sense than the magnitude of said As indicated in the introductory por output electrodes, a control device having a wind ingconnected and arranged to be traversed by a v current which varies substantially in accordance 'with the current flowing in said output circuit,

source of biasing potential, circuit connections for impressing the voltage of said source on said input electrode, and means including said source and said circuit connections for changing the magnitude of said first-mentioned current to a value different in said one sense than the value of said second current when the input voltage impressed on said input electrode is reduced to a predetermined value, whereby the direction of current flow through said winding is reversed when said input voltage is decreased from said substantial value to said predetermined value and when said input voltage is increased from said predetermined value to said substantial value '7. Electrical control apparatus comprising, in combination, an electron discharge device including input and output electrodes, an input circuit coupled to said input electrodes and adapted to have an input voltage impressed thereon, an output circuit coupled to said output electrodes, a control device having a winding connected and arranged to be traversed by a current which varies substantially in accordance with the current flowing in said output circuit, means for passing a second current through said winding in opposition to said first-mentioned current and of a magnitude substantially less than the magnitude of said first-mentioned current when any substantial input voltage is impressed on said input circuit, and means for decreasing said firstmentioned current to a value less than that of said second current when the input voltage impressed on said input circuit is reduced to a predetermined value, whereby the direction of current flow through said winding is reversed when arranged to be traversed by a current which va-.

ries substantially in accordance with the current flowing in said output circuit, means for passing a second current through said winding in opposition'to said first-mentioned current and of a magnitude substantially less than the magnitude of said first-mentioned current when any substantial input voltage is impressed on said input circuit, a source of biasing potential, circuit connections for impressing the voltage of said source on said input electrode, and means including said source and said circuit connections for decreasing said first-mentioned current to a value less than that of said second current when the input voltage impressed on said input circuit is reduced to a predetermined value, whereby the direction of current flow through said winding is reversed when said input voltage is reduced from said substantial value to said predetermined value and when said input voltage is increased from said predetermined value to said substantial value.

9. Electrical control apparatus comprising, in combination, an electron discharge device including an input electrode and output electrodes, means for impressing an input voltage on said input electrode, an output circuit coupled to said output electrodes, a control device having a winding connected in said output circuit to be traversed by the current flowing in said output circuit, a priming circuit including a voltage source for passing a second current through said winding, said priming circuit being so connected and arranged that said second current is in opposition.

to said first-mentioned current and is of a magnitude substantially difi'erent in one sense than the magnitude of said first-mentioned current when any substantial input voltage is impressed on said input electrode, and means for changing the magnitude of said first-mentioned current to a value diiferent in said one sense. than the value of said second current when the input voltage impressed on said input electrode is reduced to a predetermined value, whereby the direction of, current flow through said winding is reversed when said input voltage is decreased from said substantial value to said predetermined value and when said input voltage is increased from said predetermined value to said substantial value.

10. Electrical control apparatus comprising, in combination, an electron discharge device including an input electrode and output electrodes, means for impressing an input voltage on said input electrode, an output circuit coupled to said output electrodes, a control device having a winding connected in said output circuit to be traversed by the current flowing in said output circuit, a priming circuit including a voltage source for passing a second current through said winding, said priming circuit being so connected and arranged that said second current'is in opposition to said first-mentioned current and is of a magnitude substantially different in one sense than the magnitude of said first-mentioned current when any substantial input voltage is impressed on said input electrode, a source of biasing potential, circuit connections for impressing the voltage of said source on said input electrode, and means including said source and said circuit connections for changing the magnitude of said first-mentioned current to a value different in said one sense than the value of said second current when the input voltage impressed on said input electrode is reduced to a predetermined value, whereby the direction of current flow through said winding is reversed when said input voltage is decreased from said substantial value to saidpredetermined value and when said input voltage is increased from said predetermined value to said substantial value.

11. Electrical control apparatus comprising, in combination, an electron discharge device including an input electrode and output electrodes, means for impressing an input voltage on said input electrode, an output circuit coupled to said output electrodes, a control'device having a winding connected in said output circuit to be traversed by the current flowing in said output circuit, a priming circuit including a voltage source for passing a second current through said Winding, said priming circuit being so connected and arranged that said second current is in opposi-v tion to said first-mentioned current and is of a magnitude substantially different in one sense 6 I I Y 9,181,078

' input electrode, an output circuit coupled to said than the magnitude 01' said first-mentioned current when any substantial input voltage is impressed on said input electrode, the resistance of said priming circuit being so proportioned relative to the resistance of said winding that no substantial portion of the direct component of the current in said output circuit is by-passed around said winding and through said priming circuit, and means .for changing the magnitude of one oi said currents so that the magnitude of said iirst-mentione'dcurrent is diiferent in said one sense 'than the value of said-second current when the input voltage impressed on said input electrode is reduced to a predetermined value,

5 whereby the direction of current flow through said winding is reversed when said input voltageis decreased from said substantial value' to said predetermined value and when said input voltage is increased from said predetermined value to said substantial value.

12. Electrical oontrolapparatus comprising, in

combination, an electron discharge device includl output "electrodes, an electro-magnetic control device including a core, a winding and a control element operative between two positions, said winding being connected and arranged to be traversed by the current flowing in said output circuit, means for passing a second current through said windingv in opposition to said iirstmentioned current and oi a magnitude substantially different in one sense than the magnitude of said first-mentioned current when any substantial input voltage is impressed on said input electrode, and'means for changing the magnitude of said first-mentioned current to a value dlflerent in said one sense than the value of said second current when the input voltage impressed on said input" electrode is reduced to a predetermined value, whereby the direction oi current flow through said winding is reversed each time said input voltage is varied between said sub-. stantial and said predetermined values and said control element is positively operated between its said two positions.

. ROSWELL HARRY