US2345925A - Pulse-counting circuit - Google Patents

Description

April 4, 1944. E FERRELL I 2,345,925

PULSE-COUNTING CIRCUIT Filed Oct. 31, 1941 2 Sheets-Sheet l r F/G.

lNl/E/VTOR y E. B. FERRELL April 4, 1944. FERRELL 2,345,925

' PULSE-COUNTING CIRCUIT Filed Oct. 51, 1941 2 Sheets-sheaf 2 FIG. 5

INVENTOR E B. FERRELL Patented Apr. 4, 1944 2,345,925 PULSE-COUNTING CIRCUIT Enoch B. Ferrell, Chatham,

Bell Telephone Laboratories,

York, N.

N. J., assignor to Incorporated, New

Y., a corporation or New York Application October 31, 1941, Serial No. 417,322

Claims.

This invention relates to telephone systems and has for its object to provide improved pulsing equipment for such systems.

In automatic telephone systems, the directive operation 01 the switching devices is generally controlled by series of pulses. Two types of pulse are most commonly used, namely, interruptions of a previously closed circuit or ground pulses in shunt of the battery supplied the pulsing circuit. In either case the pulse relay closes a hack contact at each pulse.

For the purpose of controlling the switching operations, in some systems the pulse relay acts directly on the switch magnets, while in other systems the number of pulses is counted by a series of relays, known as counting relays.

The most widely employed counting relay arrangement requires two relays for each pulse to he recorded. Another arrangement employs six pairs of relays for counting ten pulses while a still more economical arrangement is enabled to employ six single relays for counting pulses by interposing a pulse halver, made up of three relays, between the pulse relay and the counting relays.

In accordance with the present invention a still further saving in number of relays is attained by the use of accurately timed mercury contact relays.

More specifically, a single relay is enabled to act as a pulse halver by the use of accurately timed pulses and a transfer contact on the pulse halver which closes its alternate contact subsequent to the termination of the actuating pulse.

Alternatively, the pulse halver may be emitted by using as counting relays a chain of single relays each having timed contacts.

Switching elements of the type suitable for use in producing the accurately timed pulses of the present invention are disclosed in United States Patent No. 2,295,602, granted to C. E. Pollard, Jr... September 15, 3.942.

The invention will be more clearly understood from a. consideration of the followingdescription in connection with the drawings in which:

Fig. 1 shows the pulse halver;

Fig. 2 shows the pulse halver in connection with a chain of simple relays;

Fig. 3 shows the timed contact relay as a binary counter;

Fig. 4 shows the timed contact relay in one form of register;

Fig. 5 shows the timed contact relay in another term or register;

ill

' contact member of this Fig. 6 shows the contact arrangements used in the circuits of Figs. 3 to 5; and

Figs. '7, 8A, 8B and 88 show the used for pulsing. v

Referring first to Fig. 6, a brief. description will be given of the type of switch element especially serviceable for the purpose of the invention. These switch element 55 to it are very similar and each comprises a glass envelope l, positioned in the aligned openings of the pole- pieces 2 and 3 of a magnetic circuit including an energizing coil i8 schematically shown.

Positioned within the envelope is a cylindrical guide sleeve 4, entirely open at its upper end and partially closed at its lower end, and supported on and secured to the upper end of terminal wire ii. The guide sleeve lis made or" a non-magnetic material which is wettable by mercury. Sealed through the upper end wall or the envelope are two parallelly disposed contact members 5 and l, having their ends which extend into the envelope bent at right angles toward each other to form two stationary contact portions 8 and 9.

Movable within the guide sleeve d is a cylindrical tubular armature it, the upper end of which in elements l l and i8 is entirely open and the lower end of which is closed except for the therein. In switch elements l5 and Hi the bottom of armature i ll is entirely open and the top has a narrow collar to strengthen it. ihe armature is made of magnetic material but its surfaces are so treated that they are readily wetted by mercury. Secured to the inner surface of the armature is a contact member l2 which may be formed by doubling a length of wire, bending the looped end at right angles and flattening the same to provide a widened contact portion 3 for engagement with the contact portions 8 and 9 of the contact members 6 and l. A type has the property of condilcting mercury to the surface of the contacts with which it cooperates.

To complete the switch element, a measured amount of mercury it is deposited in the bottom of the envelope, the envelope is evacuated and refilled with a gas at the proper pressure. Due to the wettable character of the guide 4 and the armature ID, the mercury rises to the positions shown in Fig. 6. The surface tension of the mercury acting between the armature l0 and the guide 4 holds the contact portion I3 firmly against the contact a when coil 48 is not energized. A film of mercury also lies between these contact members. In the switch elements l1 and I8, contact portions 8 and 9 are flattened to increase form. of contact the surface tension between them and contact is. These switch elements are therefore designed to consume definite time intervals between the energization. oi the operating magnet 63, the opening of the lower, or normal contact and the closure of the upper, or alternate contact. By varying the size of the contact elements and the size of the aperture ii in the armature i3, these time intervals may be regulated as desired. The reverse movement following deenergization of the relay magnet is is similarly controlled.

In the case of switch elements 55 and it, since quick action is required, the bottom wall of the armature iii is omitted as above mentioned. In addition, the contact members 3 and e are unflattened,-as shown, to give a linear contacting surface with contact is which is easily disrupted,

By placing contact members 3 and 3 closer together, a continuity closure may be obtained as shown in Figs. '7, 8A, 8B and 80. Fig. 3A shows the position of the contact members 8, 9 and it, when the relay coil is energized. When thecoil is deenergized in response to a pulse the armature moves downward under the force of the surface tension and contact member it draws out the film of mercury connecting it with member 3, as shown in Fig. 83. Contact member 3 is near enough so that member it makes contact therewith through the mercury films on their faces before the upper film breaks, thereby connecting contact members 3 and 9. When the member 63 is drawn against member '3 the mercury film breaks down and the contact is opened as shown in Fig. 8C. These switch elements and their function are described in greater detail in the aboveidentified Pollard patent.

Relays may be designed having one or more switch elements like those shown in- Figs. 6 and '7. A possible arrangement of the operating magnet and the switch elements is shown in United States Patent 2,247,493 to H. C. Harrison et al., July 1, 1941.

In the circuits shown in Figs. 1 to 5, relays 20, All, 53 and EB employ one switch element a which is of the type shown in Fig. '7 and which functions as described in connection with Figs. 8A, 8B and 8G to make one time'd closure between contacts 8 and 9 in response to each opening of the circuit of the operating magnet,

Other relays, such as relays 42, 44 and 48 employ four switch elements as shown in Fig. 6, that is, one timed transfer contact t (element l3) one timed transfer contact at which has its two fixed contacts connected together (element l1), and two quick operating contacts 0 (elements l5 and l6);

Relays like relays 2|, 4!, 5| employ only three switch elements, namely, one element. t and twov elements 0, while the relays of Fig. 5 employ five switch elements, the four elements of Fig. 6 with an additional element 0.

With no current flowing in the magnet winding the contacts take up the positions shown in Figs. 6 and 7, the movable member l3 being held in normal contact with the contact member 3 under the force of the surface tension as stated hereinbefore. Whenever an energizing circuit for the operating magnet of one of these relays is closed, a magnetic flux is set up between the pole-pieces, such as pole- pieces 2 and 3, and each of the armatures l0 rises, carrying with it contact member l3. In the case of switch element 0 the normal contact between member l3 and member 8 is immediately broken, followed at once by the closure of the alternate contact between It is obvious that, although switch elements c and t are shown as transfer switches, the wiring may be varied to use only the make or the break function.

In Figs. 1 to 5 the relays are shown with conventional armatures and contacts but, with the exception of relays 38 to 3&3, each armature with its associated contacts represents one of the switch elements, each armature being lettered to indicate the type of switch element represented thereby. In each case the armature corresponds to the movable member it, the back contact corresponds to member t and the front contact to member 9.

Referring now to Figs. 1 and 2, relay 231s a.

pulsing relay normally operated over the dial contact and responding to dial pulses to close a contact at each interruption of its circuit by the dial. This relay as pointed out above is equipped with a switch element of the type described in connection with Figs. '7, 8A, 8B and 8C. No connection is made to the armature contact l3, whereby a contact of measured duration takes place between the contact elements 8 and 9 at each interruption of the line current. Contact.

member 8 being cylindrical in form, when relay 2|] is reenergized the surface tension is insufilcient to make a closure. For convenience, all contacts of this type have been indicated by the letter a as they appear in the circuits.

Relay M is provided with two or more quick acting contact switch elements 0, such as shown at l5 and H6 in Fig. 6, together with a switch element,.shown at t, like element i8 of Fig. 6. Contacts t and a are adjusted so that contact t closes its alternate contact after the termination of the closure by contact a.

Fig. 1, therefore, functions as follows. At the interruption of its circuit, relay 23 makes a measured closure at its contact 11. Ground over this contact completes a circuit extending over the contact t in normal position of relay 2!, through the winding of relay 2| to battery through resistance 22. Relay 2| immediately closes its quick acting contacts 0, locking to ground over the upper contact. After a measured interval, greater than the closed time of contact a, contact t closes its alternate contact. At the next closure of contact a, ground is connected over this alternate contact of contact 2h. to resistance 22, so that the winding of relay 2| is short-circuited and the contacts 0 fall back, followed after a measured interval by contact t. Relay 2|, therefore, acts as a pulse halver, closing a. circuit over conductor 23 at each odd-numbered pulse and over conductor 24 at each even-numbered pulse.

In Fig. 2 the pulse hulver relay 2! is shown controlling a set of conventional counting relays. Ground connected to conductor 23 in response to the first pulse operates relay 3| over back contacts of even-numbered relays 34 and 32. Relay While only four relays have been shown, any desired number may be employed.

In Figs. 3, 4 and 5, relays of the type of relay 2| are formed into chains for counting and registering series of pulses.

Relays 42, 44 and 48 of Fig. 3 have contact assemblies such as shown in Fig. 6. That is, each relay has two or more quick acting switch elements 0, such as contacts l5 and H5, in which no circuit connection is made to contact member 6, one transfer contact t like switch element l8 and one contact it like switch element H. In the case of element I! contact members 6 and 7 are connected together so thatcontact 13 closes the same circuit when in contact with either element but in moving from contact 8 to contact 9 causes a measured interruption of the circuit. Relays 52, 54, and 55 of Fig. 4 and relays H to E6 of Fig. 5 are similarly equipped. Relays 4! and 51 lack contact it while on relay 60 contact if is not wired.

In Fig. 3 counting is binary in character and the arrangement is particularly adapted for tim ing operations. Fig 4 shows a chain of relays suitable for acting as a sender register of the type which transfers the designation by code to a decoder or marker, while Fig. 5 shows a chain of relays suitabl for direct counting, for example, under the control of revertive pulses.

More specifically, in F ig. 3, when contact a of relay 40 closes, ground is connected over the normal contact of contact tit to the winding of relay 4| and battery. Relay 4i locks over upper contact 410 and contacts d211,, 4472, Min, etc., to ground. After contact 40a reopens, contact lit closes its front contact. The second closure of contact lba operates relay 32 which looks over contacts 120,4471 and 3811.. When relay 42 operates, contact 4212 opens, releasing relay 4i and then recloses. Therefore the third pulse operates relay 4|, and since relay 42 is locked operated, the fourth pulse operates relay d4. Cohtact 541a releases relays ll and d2. Relays ll and 42 recycle so that the eighth pulse operates relay 48. Contact Min releases relays d4, 42 and M. Addi tional relays similarly wired would require H3, 32, etc., pulses to operate, thus providing means for measuring long time intervals at the expense of a comparatively few relays.

In Fig. 4, pulsing relay 5B responds to incoming pulses such as dial pulses to close contact 55a. At the first closure, relay 5| operates in a circuit over the normal contacts of contacts 531? and Mt. Relay 5| looks over contacts 550, 5272, 5472, 5512 and Glln. Contact 5It closes its front contact after contact 50a opens. The second pulse operates relay 52 which looks over contacts 52c, 5511, 551i and 51m and releases relay 5|. \vith relay 5i released, the third pulse reoperates relay 55 which locks as above, relay 52 having reclosed contact 5211. With both relays 5| and 52 operated, the fourth pulse operate relay 54, which locks over contacts 550, 55a and 6011. and releases relays 5i and 52. The fifth pulse operates relay 55, which locks over contacts 55c and 5812 and releases relay 54.

With relay 5% released, relays 5|, 52 and 54 are reoperated as above described by the sixth, seventh, eighth and ninth pulses. When relay 54 operates in response to the ninth pulse, with relay 55 held operated, the tenth pulse is directed to relay 6!! which looks and releases relays 54 and 55.

Relays 5!, 52, 54 and 55 ground conductors 6|,

62, 64 and 65, respectively, when operated. From the above description it will be apparent that the conductors will be grounded in accordance with a code such that the sum of the units digits of the conductor numbers grounded at the end of any pulse will correspond to the number of the pulse. Since this is the code used in transferring designations from the crossbar sender to the marker, it is apparent that such an arrangement as that of Fig. 4 would find use in the crossbar system.

The circuit of Fig. 5 is arranged to ground one of ten conductors to indicate the number of pulses received and might be useful to count revertive pulses in a crossbar sender.

The pulsing circuit controlled by relay 10 at the beginning of pulsing extends over normal contacts 752?, Mt, 7323, 721i and Ht to the winding of relay "H. At each pulse the corresponding relay operates its t contact to extend the pulsing circuit to the next relay. Each relay'locks over the 12 contacts of higher numbered relays and opens its own n contact to release the lower numbered relay. Relay '55, however, looks over the contact fin, so that it remains operated after relay 15 operates in response to the sixth pulse. With relays l5 and operated a branch of the pulsing circuit is extended to the winding of relay lll over contacts i and lot so that relay ll responds to the seventh pulse. The operation of relay H releases relay l5 restoring the pulsing circuit to operate relays l2, l3 and it in response to the eighth, ninth and tenth pulses. The inner armatures of relays it to V5 receive ground over a normal contact of relay :76 and when operated extend ground to conductors at to 85, respectively. The outer armatures of relays ii to l5 receive ground over an alternate contact of relay l6. Relay 75 is held operated after relay '15 operates from the sixth pulse and together they ground conductor 85, while relays if to i l, operated with relay l6, ground conductors 8i! to 50, respectively.

What is claimed is:

i. In combination, a source of pulses of fixed predetermined duration and a relay for receiving said pu1ses,'said relay having a locking contact and a timed transfer contact, the time of travel of said transfer contact adjusted to overlap an operating pulse and cause the closure of the alternate contact after the termination of said operating pulse,

2. In combination, a source of pulses of fixed predetermined duration and a set of relays for receiving said pulses, each of said relays having a locking contact and a timed transfer contact, the time of travel of said transfer contact adjusted to overlap an operating pulse and cause the closure of the alternate contact after the termination of said operating pulse to prepare a circuit for operating the next relay in said set in response to the next pulse.

3. In combination, a source of pulses of predetermined duration and a set of relays for receiving said pulses, each of said relays having a locking contact and a transfer contact, said transfer contact adjusted to close its alternate contact after the termination of an operating pulse to prepare a circuit for operating the next relay in said set in response to the next pulse, all but the first of said relays having a normally closed contact over which extend the locking circuits of relays earlier in the set, said normally closed contacts being opened momentarily during the operation of the corresponding relay to release all earlier relays and to permit them to reoperate in response to subsequent pulses.

4. In combination, a pulse halving arrangement employing a pulsing relay having a contact which closes for a measured interval at each incoming pulse irrespective of the length of said pulse, and an auxiliary relay having a transfer contact timed to consume more than said meas= sured interval in moving from one contact to the other, said transfer contact alternately closing a circuit tooperate said auxiliary relay assaaac and a circuit to short-circuit said auxiliary relay.

5. In combination, a pulsing relay having a contact which closes for a measured interval at each incoming pulse irrespective of the length of said pulse, and a relay operated over said contact having a transfer contact timed to consume more than saidweasured interval in moving from one contact to the other.

ENOCH FER.

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