US2248899A - Telephone system - Google Patents

Description

July 8, 1941. r. N. SAATY TELEPHONE SYSTEM Filed Aug. 3, 1940 4 Sheets-Sheet 1 INVENTQR Theodore M Sam BY fl ATTOR July 8, 1941. T. N. SAATY TELEPHONE SYSTEM 4 Sheets-Sheet 2 Filed Aug. 3, 1940 INVENTOR Theodore W. Saa

(2 4 il] gi Rains July 8, 1941. SAATY 2,248,899

TELEPHONE SYSTEM Filed Aug. 3, 1940 4 Sheets-Sheet 3 INVENTOR k'odoreM Saafy ATT RN EYS July 8, 1941. sAATY 2,248,899

EEEEEEEEEEEEEE Mv NNNNNN OR Theodor .ZW Study Patented July 8, 1941 TELEPHONE SYSTEM Theodore N. Saaty,

Providence, R. I., asslgnor to Screw Machine Products Company, Inc.,

Providence, R. L,

a corporation of Rhode Island Application August 3, 1940, Serial No. 350,843

9 Claim.

This invention relates to communication and more particularly to anautomatic telephone system and apparatus used in conjunction therewith.

An object of this invention is to provide an automatic telephone system wherein the calling station is connected through a central station to the called station in an efficient and dependable manner with a minimum amount of equipment and a minimum number of lines between the various stations of the system. Another object is to provide an automatic telephone system which performs its various operations with maximum efliciency in a minimum of time, and which is flexible in use so that it is adaptable for efficient operation under a wide variety of conditions. Another object is to provide equipment of the above character which is sturdy and durable in construction and which is light in weight and can be constructed with a minimum of materials.

A further object is to provide a system of communication for use in an establishment such as one having a large number of offices where it is desirable for each ofiice to have communication with each of the other offices, and where the number of stations in the system may be increased without disturbing the original equipment. A further object is to provide a system of communication wherein one of a number of stations may carry on telephone conversation with the other stations and wherein one or more of these stations has auxiliary talking andreceiving equipment. Another object is to provide a system of two-way communication between any number of stations by means of a circuit having a minimum number of wires. Another object is to provide a telephone station wherein the dialing is automatic and the equipment is so arranged that errors in dialing are reduced to a minimum. A further object is to provide a telephone system which is dependable in its operation even though part or all of the stations are called infrequently. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combination of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of which will be indicated in the following claims.

In the drawings:

Figure 1 is a'diagrammatic representation of the main portion of a telephone station of a system constituting one embodiment of the invention;

Figure 2 is a diagrammatic representation of a telephone handset which is used in conjunction with the apparatus of Figure 1;

Figure 3 is a perspective view of a gear assembly which drives the timing cam at the lefthand side of Figure 1;

Figure 4 is a front elevation of a portion of the keyboard of the apparatus of Figure 1;

Figure 5 is a perspective view, with certain associated parts omitted, of a latch release mechanism shown diagrammatically in the central portion of Figure 1;

Figure 6 is a sectional view of the key assembly shown at the top of Fig ure 1;

Figure 7 is a multiple-unit contact assembly which is used in conjunction with the embodiment of Figure 1;

Figure 8 is a view on the line 8-8 of Figure 7; and

Figures 9 and 10 are perspective views of a portion of the apparatus of Figures 6 and 7 showing contactor arms which are associated therewith.

This application is a continuation-in-part of my copending application Serial No. 148,075 filed June 14, 1937, and reference may be had to that application for a more detailed discussion of certain phases of the embodiment of the present application. The embodiment of my copending application is hereby incorporated into the present application and the embodiment of the present application differs from the prior embodiment as herein pointed out.

In telephone systems, and particularly automatic systems where a party at one station automatically calls another station, it is important that the equipment be adaptable for use under a wide variety of conditions. Furthermore, the equipment should be dependable in operation even though parts of the equipment remain unused over a long period of time. The various automatic operations of such equipment should be carried on quickly and efficiently as a delay in completing a call is often a serious matter. In addition to avoiding tying up the equipment, the feature of saving time in completing calls may be a vital point in favor of installing automatic equipment.

Under some circumstances of use, it is important that the party being called be informed as to the calling party as this permits the called party to select calls which must be answered. In the past there have been frequent occasions when an organization having automatic equipment has gradually expanded so that the original equipof one of the keys ment can no longer handle the large number of stations. It is important under these circumstances that the equipment be easily adaptable for expansion without disturbing the original installation. Furthermore, it is desirable that equipment be standardized so that it may be manufactured, installed and serviced efliciently, and at the same time, the initial cost oi a small installation must be small.

At times, one particular station of a system must be provided with auxiliary equipment, and this auxiliary equipment must not interfere with the normal operation of the system. For example, under some circumstances, it is desirable that the user be permitted to talk and listen through either a handset or a microphone and loud speaker.

It is an object of this invention to provide a system which attains these ends by providing a number of cooperating units wherein each unit of the system performs its functions in a dependable and efficient manner. In the illustrative embodiment, the major portion of one station is shown in Figure l, and the mechanical details of certain operating units of the system are shown in the other figures. As indicated above, this system is related to that of my copending application, and reference may be had to that application for certain details of the system which have been omitted from the present detailed description for the sake of brevity. In this embodiment, the term dialing has been used in the sense of producing a set of impulses or a signal which identifies a station which is being called, even though in the present embodiment this operation is carried on by a. motordriven mechanism which diiIers from the normal telephone dial. The term selecting" is used in the sense of connecting the calling station with the station being called, in the present embodiment this being done by means of the central selector relay which has a pair of wipers which are moved along an arcuate path. The term ringing has been used in the sense of being a signal at the station being called, and in the present embodiment, this signal notifies the called station of the particular party calling.

Referring particularly to Figure 1, the station consists of a group of units, the major ones of which are the keyboard assembly 50, the mo.- tor assembly unit 52, the amplifier unit 54, the loud speaker unit 56, and the chassis assembly 58. External circuits enter the chassis assembly through receptacles 40 and 60; these external circuits are the main line circuits which are connected through receptacle 60 and a privacy handset unit 62 (see Figure 2) which is connected through receptacle 40. The privacy handset unit is used to dial beyond the capacity of the keyboard, and to carry on conversations without the use of the loud speaker unit.

The main circuit in this embodiment comprises three wires which are not shown but which extend from receptacle 60 to the switchboard at the central station. These three wires have been designated the C-circuit, the L-circult and the S-circuit, and they are connected in receptacle 60 to terminals i, 2 and 3, respectively. The C-clrcuit is common to all stations of the system and is connected at all times to all. of the stations. The L-circuit connects its particular station to the central selector relay, and accordingly, each station is provided with its own L-circuit. The S-circuit is similar to the L-circuit in that it extends from its station to the central selector relay, the L-circuit and the S-circuit being used to carry the dialing" signal for the selecting operation and for carrying on subsequent signaling and conversations. Terminal l is connected to the positive side of a thirty-volt battery l2 which has its other side connected to a terminal 6. Terminal l is also connected through a lead I" to one side voi a I twenty-flve-volt, sixty-cycle, alternating current source, the other side of which is connected through a lead I92 to a terminal 6. A onehundred-and-twenty-five-volt battery I has its negative side connected through a lead I96 to terminal 8 and has its other side connected through a lead I" to a terminal I. The uses or these various voltage sources is more fully discussed below.

As indicated above, this apparatus is easily adaptable for use under a wide variety of conditions, and under some circumstances, certain of its parts perform functions which are other than their normal functions. However, certain of the normal functions of the various units will be briefly outlined at this time. The central portion of the apparatus is the chassis assembly 56, and this chassis assembly connects the other units together and coordinates their actions. The chassis assembly in itseli includes a number or operating units which are more fully explained below, and among these are the following: a potentiometer unit I60 which is used tocontrol the volume of the output or the loud speaker unit 66; a. resistance unit I66 which is regulated to control the tone of the output of the loud speaker unit 56; a privacy relay 36 which is eifeotive when energized to disconnect the loud speaker and microphone circuits when the privacy handset unit 62 (Figure 2) is being used; a keyboard release relay 96 which is shown with its associated mechanism in Figure 5, and which, after being energized and then deenergized, automatically releases all of the key latches on the keyboard; a control relay 36 which is enersized to condition the station for talking; a buzzer relay which is energized when there is an incoming call to perform the buzzer" or ringing operation; a microphone unit It which is used to transmit voice from the station when the privacy handset unit is not being used; and a voltage divider Hill which has an adjustable voltage pick-up I02.

The amplifier unit 54 receives the voice signals from the incoming circuits and transmits these signals, suitably amplified, to the loud speaker unit 56. As indicated above, the volume and tone or the output of the loud speaker unit 56 are controlled respectively by units I60 and I66, and this control is exerted throu h the amplifier unit 64. The loud speaker unit 66 receives the amplified voicesignals and translates them into sound. The keyboard assembly 50 includes the various control keys with one key for each station which may be called, and with additional keys to permit manual control oi the talking and ringing operations.

The keyboard assembly 50 is connected by means of a number of leads to the terminals of a commutator assembly H6, which is part of the motor assembly unit 52. The motor assembly unit is connected to the chassis assembly 68, and is effective to connect and disconnect the various circuits at the proper times depending upon the control exerted by the units of the chassis assembly. The motor assembly unit 62 is provided with a constant speed motor I20 which drives a shaft I22 (shown partly in broken lines) through a worm gear unit I24. When a station is to be called, motor I20 rotates shaft I22 two complete revolutions, and during the first of these revolutions a dialing" signal, or a set of dialing impulses, is transmitted to the central selector relay, which dialing impulses correspond to the station being called. The central selector relay thereupon connects the calling station to the called station and during the second revolution of shaft I22, a "ringing" signal is transmitted over the circuit set up to the called station, and this ringing signal identifies the calling station so that the party being called knows who is calling.

The dialing signal is produced by the combined action of the commutator assembly H8 and a cam I28 with its associated switch I42, and the "ringing signal is initiated by a cam I20 and its associated switch I48. A control cam I32 controls the completing of the dialing and ringing circuits so that .the circuit of switch I42 is first closed and the circuit of switch I48 is held open so that the dialing operation is performed; and then the circuit of switch I48 is closed and the circuit of switch I42 is opened so that the ringing operation is performed. Control cam I32 also stops the operation of motor I20 when the ringing signal has been completed. Cams I28 and I29 are keyed directly to shaft I22, and cam I32 is rotatably mounted on the shaft and is mechanically connected thereto through the gear assembly shown in Figure 3. This gear assembly drives cam I32 with an intermittent motion, and cam I32 completes one revolution at the time shaft I22 completes its two revolutions.

Motor assembly unit 52 is provided with a normally energized relay I which is deenergized to permit the carrying on of the dialing and ringing operations when one of the keys is pressed. A control relay 24 is also provided which performs a number of control functions including the control of the starting and the continued operation of motor I20.

As indicated above, shaft I22 rotates two complete revolutions during the signaling operation, there being one revolution during which the calling station is being connected to' the called station, and there being one revolution during which a ringing" signal is being transmitted to the called station. The mechanical connection for driving cam I32 is shown in Figure 3 with cam I32 loosely mounted on the shaft, and with a gear unit to transmit intermittent movement to the cam.

Accordingly, rigidly attached to cam I32 is a gear 320 which meshes with an intermediate gear 322 which is mounted to rotate freely on its shaft 324 which is parallel to shaft I22. Keyed to shaft I22 and adapted to mesh with intermediate gear 322 is a segment gear 326 which has teeth around one-half of its periphery. Thus, when shaft I22 rotates one revolution, gear 326 is engaging and rotating gear 322 during one-half of the revolution, or 180, and during the other half of the revolution gear 322 remains stationary. Accordingly, cam I32 is rotated through 180 during each 360 movement of shaft I22, and at the end of each two revolutions of shaft I22, the elements return to the position of Figure 1. As previously pointed out, cam I32 operates a number of switches, and by using this'type of drive for cam I 32, the switches are opened and closed at a rapid rate and in the proper timed relationship. At

the same time, the operating mechanism is compact and sturdy.

In this embodiment, the stopping of motor I20 is controlled by cam I32 so that the motor is stopped only when the cam reaches a predetermined position. Thus, each dialing and ringing cycle is started with cam I32 in the proper position, and any error which might appear in one cycle of operations is not carried into the next cycle of operations.

As indicated above, the keyboard assembly 50 is provided with a number of keys which are independently operable, and there is a separate key for each station to be called. Certain details of the construction of the keyboard assembly are shown in Figures 4, 5 and 6, though in Figure 5, certain of the elements are omitted to show the operating relationship between the other elements. A panel 260 is provided with a number of rectangular holes 261, and through each hole extends the front of a key 266 with the keys in alignment both vertically and horizontally. Each key bears a notation upon its face corresponding to the station which is called when the key is pressed, keys 266-I, 266-2 and 2663 being marked President, Vice President and Superintendent respectively. When the operator desires to talk to a particular person, he merely presses the name of that person, and the mechanism is automatically operated to provide the proper connection. It has been found that by providing this construction, the operator does not make errors in calling the wrong station, and at the same time, the call is completed in a minimum of time and without effort.

When one of the station keys is pressed to connect a station, the key is latched in its inner position by means of a latch mechanism, the details of which are shown best in Figures 5 and 6. Referring to Figure 6, at the right of panel 260 is a false front 26I, and rigidly mounted in. a hole in the false front is a sleeve-bearing assembly 265 through which the key shaft 263 extends. A coil spring 264 bearsat the left against the head of the key and at the right against a flange on the sleeve-bearing assembly 265, and the key is therefore urged to the left, or outwardly, by the spring. Upon the right-hand end of shaft 263 is a cam collar 268 which has a cam flange 269 with beveled surfaces 210 and 2H. Cam collar 268 is held in place by a plunger 214 which is threaded onto the end of'shaft 263 and the right-hand end of which operates the key switch.

The left-hand side of beveled flange 269 is provided with an annular latch surface 280. Extending above each latch cam is a latch bar I30 which is rockably supported by a rockable bar 216. Latch bar I30 has a downwardly extending flange with a lower edge 28I, and when the key is pushed to the right to the position shown in broken lines, the latch edge 28I rides up over cam surface 2' and down over, surface 210 to the side of surface 280. When in this position, the key is securely latched, and the key is held in its depressed position until released. As shown in Figure 5, the rockable bars 216 are supported at their ends by brackets 283 (only one of which is shown).

Under some circumstances, a key remains in the depressed position after a call has been completed, and it is important that the pressing of a particular key release all of the other keys which are depressed. Accordingly, the latching mechanism is constructed so that the pressing of a key releases all of the latches, and then the latching mechanism is eflective to hold only the one key in the depressed position. Accordingly, all of the latch bars I30 are mechanically linked together by a latch release bar 002 which is pivoted to the left end of a latch release arm 300 extending from each of the latch bars. Thus. when any one of the keys is pushed inwardly, raising its latch bar, all of the latch bars are raised, and as a result, any key which has been held inwardly by its latch is released. When released in this manner, the initial movement of the latch lifts edge 20I (Figure 6) upwardly along surface 260, and when the edge 20I rides onto cam surface 210, the spring 264 urging the key to the left, assists in raising the latch bar.

As indicated above, Figure shows a latch release mechanism which is operated by the keyboard release relay 96. Accordingly, latch release bar 302 is provided with a transverse ridge 304, and movably mounted in cooperating relationship with respect to ridge 304 is a dog 306. Dog 306 hangs from the right-hand end of an armature 308 which is pivoted at its left-hand end to a base 3I0. A spring (not shown) normally holds the armature and the dog in the raised position, but when the solenoid 3l2 is energized, armature 308 is drawn downwardly, and the lower end of dog 306 swings in below ridge 304. Later when the solenoid is deenergized, armature 000 moves upwardly, lifting dog 306 and raising latch release bar 302. The raising of latch release bar 302 lifts all of the latch bars I30, and any keys which have been latched in their depressed 'positions are moved outwardly by their respective springs.

The privacy handset unit shown in Figure 2 is provided with a number of independently operating units which are as follows: a transmitter 200 and an associated earpiece 202; a manual ringing button I84 which is used to signal the called station; a dial I10 which is provided with a dial latch I16 which normally permits the winding of the dial but prevents the return of the dial; a dial spring (not shown) which tends to turn the dial clockwise toward a stop (not shown); a make-and-break contactor unit I1I which is operated by the rotation of dial I10; and a latch relay unit I12 which has a latch hook I14 engaging dial latch I16 and carried by an armature I18. Latch hook I14 is pulled to the right by the energization of a solenoid I13, and this movement releases dial latch I16 so that the dial may rotate freely.

In use, the dial latch is in the position shown, and the dial is manually rotated to a position corresponding to the particular station to be called, and the dial is held in this position by the dial latch. Solenoid I13 is then energized so that latch hook I14 is pulled to the right and dial latch I16 is thereby released. Dial I10 is automatically returned to its normal position by the dial spring, and during this return movement, the contactor unit I1I transmits the dialing signal to the central selector relay.

The connecting of the handset into the cir cult is controlled by switch 43 having contacts M and 42. When the handset is at rest, its cradle I69 holds contact 42 out of engagement with contact 4|, and when the handset is lifted for use, the cradle moves upwardly and switch 43 automatically closes. As pointed out elsewhere, the closing of switch 43 energizes privacy relay 38 (Figure l) and also actuates the key latch release relay ,96 shown in Figure 5. Subsequently, when the handset is replaced on cradle I, the solenoid of relay 06 is deenergized so that any keys which are depressed on the keyboard are released. When desirable, the manual ringing button I04 may be operated to transmit a ringing signal to the called station. When solenoid I12 is energized, its armature I10 swings.

upwardly to thereby move contact I00 into engagement with contact I02. This permits the impulses from the dialing contact unit I1I to go out over the calling circuit.

Figures 7 to 10 show a multipleunit contact assembly of the central selector relay which is sturdy in construction and which has a number of advantages in use. As shown best in Figure 7, a pair of angle bars 330 and 032 are provided, each having a plurality of supporting posts 304 rigidly attached thereto, and extending between these angle bars are arcuate bridge members 336 of insulating material. Supported by bridge members 336 are rods 330 each of which extends through a set of holes which are in alignment in the bridge members. The holes in each bridge member through which rods 330 extend are positioned along an arcuate line which is near the center line of the bridge member, and in radial alignment with each rod 330 is a contact clip 340. When assembled for use, a set of wires 342 is positioned as shown around the periphery of the bridge members and an insulated jumper 344 connects each of the contact clips 340 to one of the wires 342.

As shown in Figures 9 and 10, a pair of wipers 346 and 340 are provided for each of the bridge members 336, and when these wipers are rotated, wiper 346 moves along a line to engage contact clips 340 and wiper 340 moves along a line to engage rods 3 30. In practice, each rod 330 and its associated wire 342 is the calling circuit of a particular station to be called, and during the selecting operation, wipers 346 and 340 are swung clockwise by the dialing" impulses with a step-by-step movement, stopping at the end of each movement in engagement with one rod and its associated contact clip. When the selecting operation is completed, the calling station is connected to a particular station depending upon the number of impulses in the dialing signal. Illustratively, wipers 346 and 340 are shown in Figure 9 engaging the first rod 330 and clip 340; after three impulses have been transmitted, the wipers are in the position shown in Figure 10, engaging the rod, designated 330, and the contact clip 340' corresponding to the wire designated 342. If no further selecting impulses are transmitted, the calling station is connected to the station corresponding to rod 330' and wire 342.

Referring again to Figure 1. for convenience, the various electrical lines have been given a single number, even though a break is made in the line at a jack or at a fuse, and during normal use any one line is at one potential throughout. Whenever a switch is provided, the line on one side of the switch is given one numeral and the line on the other side of the switch is given another. numeral. In connection withkeyboard assembly 50, the various key switches I00 have been given separate sub-numerals, I, 2, etc., and the corresponding plungers 214 have been given subnumerals, I, 2, etc. Likewise, the leads 340 connecting the switches and the corresponding contacts I46 of the commutator assembly IIO have been given sub-numerals, I, --2, etc.

.as to move contact 64 into engagement with Under normal conditions, the solenoid II of relay I has one side connected through line 360 to terminal 8 of receptacle 60, and thus to the negative side of battery I2, and the other side of the solenoid is connecteed through line 352 to key switch I08I2. All of the key switches I08 are in series and have been designated I06I2 to I08- -I, and the other side 01 key switch I08-I is connected to line 354 which extends to terminal I of receptacle 60, which is connected to the positive side of battery I2. Thus, with all of the key switches closed, line 352 is connected through the key switches to the positive side of battery I2, and the solenoid II of relay I0 is connected directly across the battery.

This energizes the relay and'holds armature I4 to the right so that contact I6 is out or engagement with contact I8. Contact I8 is connected to line 354 and thus to the positive side of battery I2, and contact I6 is connected through line 356 to the juncture 20 of two resistance units 2I and 22. When the dialing" operation is to occur, one of the keys is pressed, thereby opening the corresponding key switch I08, and this breaks the circuit to solenoid II of relay I0 and deenergizes the relay with the result that armature I4 moves to the left and contact I6 engages contact I8. This carries current from line 354 through line 356 to the juncture of resistance units 2I and 22. At the right, resistance unit 22 is connected through a line 358 to one side of the solenoid 360 of relay 24 and the other side 01' the solenoid is connected directly to line 350 which extends to the negative side of battery I2. Thus, solenoid 360 01' relay 24 is connected in series with resistance unit 22 directly across battery I2, and the solenoid is partially energized.

Resistance unit 22 has a resistance oi 450 ohms, and the partial energization of solenoid 360 is sufficient to swing armature 26 counterclockwise to thereby operate through a dummy switch unit 36I and move switch contactor arm 28 to the right so that contact 30 is moved away from contact 32. Switch contactor arm 28 and contact 32 are connected to line 354, and contact 32 is connected through lead 362 to switch 34 of the privacy relay 38. The other side of switch 34 is connected through line 362 to the solenoid 364 of control relay 36, and the other side of solenoid 364 is connected to line 350. Thus, the control relay normally may be energized and the movement of contact 30 away from contact 32 prevents the energization of control relay 36 and, as will be explained below, this resets the mechanism to the normal starting position.

It should be noted at this time that switch 34 is held closed during this operation by the energization of privacy relay 38 which has one side connected through line 350 to the negative side terminal 40-6 of of battery I2 and which has its other side connected through line 366 to terminal 40-3 of receptacle 40. As will be explained below, terminal 40-3 is connected through the privacy handset unit 62 (Figure 2) to terminal 40-I (Figure 1) of receptacle 40 which is connected through line 368 to contact 45'of the switch assembly I36; with cam I32 in the position shown, contact 45 is in engagement with contact 44 which is connected through line 354 to the positive side of battery I2. In this way, privacy relay 38 is held energized and switch 34 is held closed.

To answer a call, control relay 36 is energized suiilciently to swing armature 68 to the left so contact 66.; Contact 66 is connected through line 310 to terminal 3 01' receptacle 60 which, as pointed out above, is. connected to the outgoing S-circuit, and contact 64 is connected through line {.312 to the sensitive transmitter circuit. The sensitive transmitter circuit includes a three mfd. condenser unit I06, a choke-coil I04 and a microphone unit 98, all of which are connected through a line 314. The other side of the microphone unit 96 is connected through a line 316 to the adjustable tap I02 on the voltage divider unit I00, which is connected directly between lines 360 and 364. The other side of the choke coil unit I04 is connected to line 354 which is connected through terminal I of receptacle 60 to the positive side of battery I2.

The swinging of armature 68 also opens the circuit of the buzzer relay 90 by moving contact 10 away from contact I2, and the circuit of the privacy handset unit is closed by the movement 01 contact I0 into engagement with contact I4. Contact I2 is connected through line 380 to the buzzer relay 90 and contact I0 is connected through line 382 to terminal 2 of receptacle 60 which is connected to the'outgoing L-circuit Contact 14 is connected through line 384 to terminal I6 of the privacy relay 38 and also to receptacle 40. Terminal 40-6 is connected as shown in Figure 2 through line 386 to the handset transmitter 200.

Control relay 36 also closes a circuit which provides the plate voltage to the amplifier unit 54 by swinging armature 61 to the right sufflciently to move contact into engagement with contact 82, contact 80 being connected through line 390 to terminal I of receptacle 60 and thus to the positive side of battery I94, and contact 82 being connected through line 392 to the plate of the tube in the amplifier unit. The swinging of armature 61 to the right also moves contact 84 into engagement with contact 86 and this supplies field current to the loud speaker unit 56. That is, contact 86 is connected directly to the field winding of the loud speaker through line 393, and contact 84 is connected through line 394 to terminal 40-8 of receptacle 40 which is connected through the privacy handset unit 62 to terminal 40-I and terminal 40-I is connected through line 368, contacts 45 and 44 and line-354 to the positive sideof battery I2. The other side of the loud speaker ileld winding is connected to the negative side of battery I2 through line 350.

One side of buzzer relay 90 is connected directly to line 350 and the buzzer relay is operated on incoming calls when it receives a signal through contacts 92 and 94. As indicated above, contact 92 is connected through line 380 to contact I2 and when control relay 36 is deenergized, contact I2 is connected through contact I0 to line 382 which is connected through terminal 2 of receptacle 60 to the L-circuit. Line 360 also extends to terminal 5 of receptacle 60 and is connected through this terminal to an auxiliary external buzzer (not shown). This external buzzer operates in parallel with buzzer relay 90 and is used as a remote signal.

As indicated above, privacy relay 38 is energized when the handset of privacy handset unit 62 (Figure 2) is removed from the cradle I69, thus bringing contact 42 into engagement with contact H. The energization of privacy relay 38 inserts the talking circuit of the privacy handset In place of the talking circuit of the amplifier unit.

In this embodiment, the keyboard assembly 66 is provided with twelve key switches I66, but key switches I06-I and I06-2 are provided with additional switch units and are used for other purposes. Accordingly, key switch Hit-I is provided with an auxiliary switch II6 which opens and closes with key switch III6-I, and when the key corresponding to this switch unit is pressed, a manual signal is transmitted over the line. Similarly, key switch I66-2 is provided with an auxiliary switch II2 which opens and closes with key switch I66-2 and when the key corresponding to this switch unit is pressed, the station is automatically connected to the general call line. This general call line is used to call a particular person when the caller does not know the station at which the person being called will answer.

An additional manual ringing switch H4 is provided to be used in transmitting a manual code ring to the receiving station. Switch H4 is normally open and has one side connected to line 364 and the other side connected to line 362. As indicated above, line 362 is connected to the L-circuit and line 394 is connected to terminal 40-6 of receptacle 46, and thus through the privacy handset unit of Figure 2 to terminal 46-I of receptacle 46 and through line 366, contacts 45 and 44 and line 354 to terminal I of receptacle 66 which is connected to the C-circult. A similar switch H6 is provided which is used in connection with the handset unit to remotely release the dial mechanism of the handset unit. Switch I I6 has one side connected to line 362 and the other side connected through line 366 to the solenoid 664 of control relay 36. As explained above, line 662 is connected through contacts 30 and 32 of relay 24, and during the mechanical dialing operation contacts 36 and 32 are separated so that switch H6 is rendered ineffective.

In this embodiment key switches III6 and switches III! and H2 ar normally closed, and current flows through all or some of them depending upon the station being called. Thus the contacts carry current and do not corrode, and infrequent use of a particular key does not impair its condition.

Passing now to the motor assembly unit 62 and its operation, motor I26 is normally stationary, but when once started, it rotates shaft I22 through two complete revolutions to thereby carry on the dialing and signaling operation. During this procedure, control cam I32 actuates the switch assembly I36 to cause the various operations to be performed in the proper sequence. Cam I32 is rotated one complete revolution while shaft I22 is completing two revolutions, but the movement of cam I32 is intermittent, in this embodiment the drive being through the gear unit of Figure 3.

Cam I32 has four sections or segments designated A, B, C and D. These segments are contacted by a switch operating arm I34 which is spring pressed against the cam and which controls the positioning of the various contacts of switch unit I36. When the mechanism is idle, trm I34 engages segment A of the cam and vhen in this position, the only two contacts of switch assembly I36 which are engaged are 46 and 44. As indicated above, when contacts 44 and 45 are in engagement, line 366 is connected line 364 which extends to the positive side of 66 to the positive side of battery I2.

battery I2, and line 366 is connected to the privacy handset unit and to the manual ringing switch II4. Thus, the dialing? operation may be carried on with the handset and the operator may use the manual ringing switch II4.

When a key is pressed, solenoid 366 of relay 24 is partially energized in the manner outlined above. The partial energization of solenoid 366 of relay 24 swings armature 26 to the right and moves contact 36 out of engagement with contact 32 and into engagement with contact 3|. This connects the positive side of battery I2 through line 664, contacts 36 and 3|, line 6, contacts 34 and 36, and line 406 to the motor. The other side of the motor is connected to line 366 which extends to the negative side of the battery, and the motor is therefore started.

Relay 24 also conditions the circuits for the impulsing operations. Accordingly, line U6 is also connected through resistance unit I64 and line 366 to solenoid 364 of control relay 36. Due to the presenc of resistance unit I64 in the circuit, control relay 36 is only partially energized, and this partial energization is sumcient to swing armature 66 to the left, but it is insufllcient to move armature 61 as armature 61 has only a small portion extending over the core of the solenoid. The swinging of armature 66 to the left moves contact 64 into engagement with contact 66 and contact III is moved away from contact 12 and into engagement with contact I4.

When motor I26 starts its operation, timing cam I32 is immediately rotated clockwise so that segment B is positioned below arm I34, and this moves contact 44 away from contact 46 and contact I46 is moved into engagement with contact I36. Contact I46 is connected to line 316 which. as pointed out above, is connected through terminal 3 of receptacle 66 to the outgoing S-cir cult, and contact I66 is connected through line 466 to impulsing switch I42. The other side of impulsing switch I42 is connected through line 462 to a sliding contact I44 of the commutator assembly II6. Sliding contact I44 engages wiper I26 and as the wiper is rotated clockwise across contacts I46 a circuit is completed between each of the contacts and impulsing switch I42.

Impulsing switch I42 is closed by impulsing cam I26, and the cam I26 and wiper I26 are accurately positioned on shaft I22 with respect to each other. When wiper I26 is moving between the various contacts I46, impulsing switch I42 is open, but when wiper I26 is in complete engagement with each of the contacts, switch I42 is closed and then opened again. Thus, the impulsing is initiated by the impulsing switch.

Contact I46 is connected to line 354 which is connected through terminal I oi receptacle Contact I46-I is connected through line 346I to the juncture of switches I66-I and IIl6--2, and contacts I 46-2, 6-3, etc., are similarly connected through correspondingly numbered lines to the junctures of the other key switches.

As pointed out above, the key switches I06 are connected in series with one side of key switch l66--I connected to line 354 so that when all of the switches are closed, the positive potential of battery I2 is carried through all of the switches and along all of lines 346 to all of the contacts I46. However, when one of the key switches is opened, this disconnects the lines 346 which are b yond it in the circuit from the battery and the corresponding contacts I48 are disconnected.

Illustratively, if key switch I88-3 is opened by the pressing of its key 286, lines 348-I and 348-2 remain connected to line 354 and contacts I46, I46I and I48-2 remain connected to the battery while the remainder of the lines and the remainder oi the contacts are disconnected. Thus, as wiper I28 moves over the top of contact I46, the closing of switch I42 initiates an impulse which is transmitted over the outgoing circuit. Switch I42 then opens and the wiper moves to contact I48-I whereupon switch I42 momentarily closes again to send out a second impulse. A third impulse is sent out through contact I46-2, but the remainderof the contacts are disconnected and no further impulses are transmitted. In this way, the calling station will be connected to the called station which isidentified by thre impulses.

At the beginning of the second rotation of shaft I22, cam I32 is turned so that segment C engages arm I34, and this moves contact I48 away from contact I38 to thereby open the dialing circuit of switch I42. Simultaneously, contact 44 is moved into engagement with contact 45 and this connects line 354 to the ringing circuit as outlined above. The ringing switch I48 has one side connected to line 368 and has its other side connected through line 406 to switch II2, the other side of which is connected through switch I I8 to line 382 which is connected through terminal 2 of receptacle 58 to the L-circuit. The ringing cam I28 is so shaped as to close switch I48 at the proper intervals to transmit a code ring to the station being called. Accordingly, cam I 28 is provided with raised segments X, Y and Z, and when the cam rotates clockwise, a ringing signal is transmitted of one long ring and two short rings.

It will b noted that this ringing circuit is com. pleted through switches H2 and H8 which are switches operated simultaneously with key switches I882 and I 88I, respectively. As indicated above, key switch I88-I is used to call a station when it is desirable to ring manually and thus the motor unit carries on its usual oper ation except that the ringing circuit is open. Key switch I882 is used to answer a call on the general call circuit, which is a general line connecting all of the central selector relays and in this embodiment having its bus positioned in place of the first station. The station is connected to this general call circuit in the same manner as it is connected to the other station but no ringing signal should be transmitted. Accordingly, when the key corresponding to switches I88-2 and H2 is pressed, motor I20 carries on its usual operations, but the ringing circuit is held open so that there is no ringing signal.

At the end of the signaling cycle, cam I32 is moved so that its segment D engages operating arm I34 to thereby move contact 44 upwardly so that contact 45 is moved into engagement with contact I58, and contact I58 is moved into engagement with contact I52. which is connected to the positive side of battery I2, is connected through contacts 44 and I58 to line 488 which carries the potential of the positive side of the battery to motor I28, the normal circuit being from relay 24 through contacts 38 and 3I, line M8 and contacts 34 and 35. By connecting line 488 directly to line 354, this normal Thus, line 354,

circuit to the motor from the positive side 01' the battery may be broken without stopping the motor.

Contact I52 is connected to line 358 which, as indicated above, is connected to one side of solenoid 368 of relay 24. Solenoid 368 was initially only partially energized as it was connected in series with resistance unit 22 across the battery, and this partial energization was insuflicient to raise armature 25 as armature 25 extends only a.

short distance over the top 01' the solenoid core. However, the connecting of line 358 directly to line 354 through contacts 44 and I58 fully energizes solenoid 368. When solenoid 368 is fully energized, armature 25 is swung to the left, thereby moving contact 2| into engagement with contact 23 and lifting contact 34 away from contact 35. By moving contact 34away from contact 35, the above-recited circuit connecting line 488 to line 354 is broken and the motor receives power through contacts I 58 and 44 in the manner outlined above.

As pointed out above, the initial energization of relay 24 as the motor was started resulted in the partial energization of control relay 38, the solenoid of the control relay being in series with resistance unit I54. However, when relay 24 is fully energized, and armature 25 moves contact 2| into engagement with contact 23,-resistance unit I54 is shorted out of the control relay circuit, and the positive side of the battery is carried from line 354 through contacts 38 and 3|,

line 8, contacts 23 and 2| and line 398 directly to the solenoid 364 of control relay 36. This full energization of relay 36 lifts armature 61 and contact 88 is moved into engagement with contact 82 and contact 84 is moved into engagement with contact 85. This is efiective in the manner outlined above to condition the transmitting and receiving circuits.

When these operations are completed, timing cam I32 is moved on to the position of rest as shown so that contacts 45, I58 and I52 are separated to thereby stop motor I28 and break the direct connection between solenoid 388 of relay 24 and line 354. However, solenoid 368 remains partially energized as it is still connected in series with resistance unit 22 and contacts I6 and I8 of relay I0 to line 354 and this partial energization is sufficient to maintain armatures 25 and 26 in their raised positions.

If a key is pressed so that the impulsing mechanism or motor unit 52 starts its operations and the key is then released, it is important that motor I 28 continue to rotate until timing cam I32 is returned to its normal position of rest as shown. This result is insured by the provision of resistance units 2I and 22 which are connected in series and deliver partial current to solenoid 388 of relay 24 when motor I20 is energized. Thus. during the major portion of the impulsing cycle, it the key is opened so as to energize relay I8 and move contact I8 away from contact I6, power is delivered from line 354 through contacts 38 and 3I, line 0, contacts 34 and 35, line 488 and resistance units 2I and 22 to line 358 and thence to solenoid 368. Even though the presence of these two resistance units in serieswith solenoid 368 cuts down the energization of the relay, the partial energization is still suflicient to hold armature 28 in the raised position. Later, when segment D engages operating arm I34, to connect line 408 directly to line 354, current will also tend to flow down through line'488 through resistance units 2I and 22 to line 356, and solenoid 366 remains energized even though contact I52 is not engaged by contact I56.

The filament of the pentode amplifying tube 4|2 isheated by the twenty-five-volt, sixty-cycle alternating current source and has one side connected through line 4 to terminal 6 of receptacle 66 and thus to line I62; the other side is connected through line 354 to terminal I or receptacle 66 and thus to line I66. When desirable, the alternating current source may be dispensed with and the filament may be heated from battery I2. When this is to be done switch H6 is closed and the filament is supplied with its operating current through line 4, through the jumper line H6 and switch 4I8 from the negative side of battery I2, and from the positive side of the battery through line 354. The input to the amplifier providing the voice currents comes in through line 426 through the two mid. condenser 422 to the primary of the input transformer I56 and the other side of which is connected through the common return line-354. The voice currents are induced in the secondary of the input transformer I56 and pass to the grid I64 of the pentode amplifying tube H2 and to the plate of the tube, and then through line 424 to the input of the loud speaker circuit. A spark gap 426 is provided from the secondary of the amplifying transformer I56 to the negative side of the power supply to dissipate induced stray currents. A one-hundredohm choke coil 426 is provided from the input line 426 of the amplifier to the'common return line 354; this provides the input circuit with a positive polarity when it is connected into the operating circuit so that there is energizing current to the L-circuit of the selector. The onehundred-ohm choke coil supplies plate current for tube 4 I 2, and causes the voice currents to flow through the two mfd. condenser.

The amplifier input line 424 extends to the power output transformer I56, the primary of which is connected to battery I64 which is of one hundred and twenty-five volts. An indicator is provided at the loud speaker unit in the form of a miniature neon-lamp 436 which is provided with a timing circuit to cause the neon-lamp to flash periodically when plate current is being supplied to the amplifier unit. The field coil 432 of the loud speaker has one side connected to line 356 and thus to the negative side of battery I2, and the other side of the field coil is connected through line 363 to contact 66 of control relay 36 and thus through contact 64 and line 364 to terminal 46-6 of receptacle 46. As has been explained in detail above, terminal 466 is connected to the outgoing C-circuit through terminal I of receptacle 66.

A volume control potentiometer I66 is provided which is connected across the secondary of the amplifying transformer I56 and which has a movable contact arm I62 which is connected to the grid I64 of the pentode tube 4I2. By swinging arm I62 from one end of the resistance unit to the other, the polarity of the grid is varied, thus affecting the volume.

A tone-control unit I61 is provided which includes a variable high resistance unit I66 and a one-tenth mfd. condenser I66 which are connected in series across the loud speaker output transformer I56. The movable contactor of the resistance unit I66 is moved to regulate the line 316 to terminal 3 of receptacle 66.

amount of resistance in the circuit, and in this Way, the tone-control unit is adjusted to absorb the desirable amount or the higher audioirequenciesj when the privacy handset unit of Figure 2 is used, the removal of the handset from cradle I66 permits contact 42 to move into engagement with contact 4|. This connects line 666 (Figure 1) from receptacle 463 (see Figure 2) through line 436, contacts 42 and H, line 436, terminal 46-I of receptacle 46 (Figure 1), line 366 and contacts 45 and 44 to line 354 which is connected to the positive side of battery I2. As indicated above, line 366 is connected to the solenoid of privacy relay 36 and thus the closing of contacts 42 and 4! (Figure 2) energizes the privacy relay; line 366 is also connected to the keyboard release relay 66 so that this relay is energized. Bubsequently, when the handset is replaced on the cradle, relay 96 is deenergized and any depressed keys on the keyboard are released in the manner pointed out above.

When it is desirable to dial manually and yet use microphone 66 and the loud speaker unit 56, the dial I16 0! the privacy handset unit is used for this purpose. Accordingly, the dial is first set to the position corresponding to the proper dialing and switch I I6 is then closed with the result that relay I12 is energized to release the dial and send out the signal, This energization of relay I12 occurs due to the fact that one side of the relay solenoid I13 is connected through line 446 to terminal 46-1 of receptacle 46 and thus through line 366, switch II6, line 362 and contacts 32 and 36 of relay 24 to the positive side of battery I2 through line 354. The other side of solenoid I13 is connected through line 442 to terminal 46-4 of receptacle 46 which is connected through line 356 to the negative side of battery I2.

The energization of relay I12 (Figure 2) moves latch hook I14 to the right to thereby release latch I16 and at the same time, armature I16 lifts contact I66 into engagement with contact I82. spring to rotate dial I16 and thereby actuate the make-and-break contactor unit HI and initiate the proper dialing impulses. The closing oi contacts I66 and I62 permits the impulses to go out over the dialing circuit, the circuit from the make-and-break contactor unit being through line 444, contacts I66 and I32, line 446, terminal 46-2 of receptacle 46 and thus to the outgoing S- circuit through line 312, contacts 64 and 66 and When the conversation is completed, switch I I6 is raised manually, but if the operator fails to do this, the initiating of another call will release the latch on the switch.

At times, it is desirable to omit the use of the privacy handset unit and under these circumstances, the unit is disconnected at receptacle 46. A normally open switch 446 at receptacle 46 is closed when the handset unit is removed to provide the connection between terminals 46-I and 46-6.

When the general call line is removed from the system, two additional contacts I460 and 617 of the commutator assembly III; are energized by closing a pair of normally open manual switches 446 and 456. Also, at this time, line 362 is connected to line 466 by means of a jumper 452 and a normally open switch 454.

as many possible embodiments may be made oi the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter here- The releasing oi latch I16 permits the dial inbefore set forth, or shown in the accompanying drawings, is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In apparatus of the character described, a contactor assembly comprising, a supporting frame construction formed by'a pair of spaced parallel frame members and a plurality of bridge members of insulating material extending in parallel relationship between said frame members, a plurality of contactor rods rigidly supported in parallel relationship and substantially parallel to said frame members with all of said rods positioned substantially along a plane which is a segment of a cylinder and with said rods thus providing arcuately extending rows of contacts, and auxiliary contactor means rigidly carried by said bridge members with a row of auxiliary contacts along each bridge member with the axis of the arcuate row of auxiliary contacts substantially coincident with the axis of said segment of a cylinder.

2. In apparatus of the character described, a contactor assembly comprising, a supporting frame construction formed by a pair of spaced parallel frame members and means to rigidly support said frame members, a plurality of arcuate bridge members of insulating material extending in parallel relationship between said frame members, a plurality of elongated contactor members rigidly supported by said bridge members in parallel relationship and positioned substantially on a plane which forms a segment of a cylinder which plane intersects each of said bridge members along an arcuate line which arcuate line has its axis substantially coincident with the axis of the bridge member.

3. In an automatic telephone system in which a plurality of stations may communicate with each other and in which intercommunication is completed by a central selector mechanism including a central selector relay and wherein said plurality of stations includes an executive station, the combination with said relay of an impulsing mechanism at said executive station to produce a variety of impulse designs in accordance with which said central selector relay connects the calling station to the proper called station, said impulsing mechanism being mounted behind a front panel and comprising, an impulsing unit which is capable of producing a selected number of impulses of predetermined characteristics, and means connecting said impulsing unit to a line which extends to said central selector relay and including a switch structure and a plurality of operating keys to operate said switch structure, said keys being adapted to be individually operated to thereby determine the number of impulses to be produced by said impulsing unit, said keys being positioned to be operated from said front panel and each of said keys having a key surface upon which appears a notation corresponding to the station which is connected in response to the actuation of the key.

4. In an automatic telephone system in which a plurality of stations may communicate with each other and in which intercommunication is completed by a central selector mechanism including a central selector relay and wherein said plurality of stations includes an executive station, the combination with said relay of an impulsing mechanism at said executive station to produce a variety of impulse designs in accordance with which said central selector relay connects the calling station .to the proper called station, said impulsing mechanism being mounted behind a front panel and comprising, an impulsing unit which is capable of producing a selected operated to thereby determine the number of im-' pulses to be produced by said impulsing unit, said keys being positioned to be operated from said front panel and each of said keys having a key surface upon which appears a notation corresponding to the station which is connected in response to the actuation of the key, a motoroperated impulsing unit which is controlled by said keys, an auxiliary manual impulsing unit to permit manual dialing of a station to be called, and an auxiliary key means to render said auxiliary manual impulsing unit effective and to simultaneously render said motor-operated impulsing unit ineffective.

, 5. In a telephone system having a plurality of transmitting and receiving stations in which one station is automatically connected to another, a signal switch mechanism comprising: a rotatable shaft; a switch-operating cam rigidly mounted on said shaft; a wiper rigidly mounted on said shaft and positioned to successively engage a plurality of contacts when said shaft is rotated; a control cam mounted to be rotated by i the rotation of said shaft and having four distinct segment portions designated as first, secw ond, third and fourth segments; a switch assembly unit including, a cam follower member which engages said control cam and assumes a position corresponding to the four segments of said control cam, a first switch unit which is held closed when said second segment engages said follower member, and a second switch unit which istheld closed when said third segment engages said follower member; and circuit means including, a circuit which is completed by the closing of said first switch unit to connect said wiper in the outgoing circuit so that an impulsing signal is produced to designate the station being called, a second circuit which is completed by the closing of said first switch unit to cause said switch-operating cam to be effective when said follower member engages said second segment, circuit means to form an interlock circuit when said first segment moves out of engagement with said follower member to insure the continuance of the delivery of power to said shaft, and means responsive to the engagement of said follower member by said fourth segment to stop said shaft when said control cam is returned to its initial position. i

6. In an automatic telephone system in which a plurality of stations ,may communicate with each other and in which interconnection is completed by a central selector mechanism including a central selector relay, and wherein said plurality of stations includes an executive station, the combination with said relay of an impulsing mechanism at said executive station "to produce a variety of impulse designs in accordance with which said central selector relay connects the calling station to the proper called station, said impulsing mechanism comprising, an impulsing unit which is capable of producing a selected number of impulses of predeterminedcharacteristics, and means connecting said impulsing'unit to a line which extends to said central selector relay and including a plurality of key switches which are connected in series and which are adapted to be individually operated to thereby determine the number of impulses to be produced by said impulsing unit, and a plurality of keys including a key associated with each of said key switches, which key has a key surface upon which appears a notation corresponding to the station which is connected in response to the key being actuated.

7. In a telephone system having a plurality of transmitting and receiving stations in which one station is automatically connected to another, a signal switch mechanism comprising: a rotatable shaft; a first switch-operating cam rigidly mounted on said shaft; a second switch-operating cam rigidly mounted on said shaft; a control cam rotatably mounted on said shaft having four distinct segment portions designated as first, second, third and fourth segments; means imparting an undulant movement to said control cam and deriving its power from said shaft; a switch assembly unit including, a cam follower member which engages said control cam and assumes four distinct positions corresponding to the four segments of said control cam, a first switch unit which is held closed when said third segment engages said follower member, a second switch unit which is closed when said second segment engages said follower member, and third and fourth switch units which are held closed when said fourth segment engages said follower member; and circuit means including, a circuit which is completed by the closing of said second switch unit to cause said first switch-operating cam to be effective when said second segment engages said follower member, a second circuit which is completed by the closing of said first switch unit to cause said second switch-operating cam to be effective when said follower member engages said third segment, and means to form an interlock circuit when said first segment moves out of engagement with said follower memher to insure the continuance of the delivery of power to said shaft and to maintain said interlock until said cams are returned to their initial positions.

8. In an automatic telephone system in which a plurality of stations may communicate with each other and in which interconnection is completed by a central selector mechanism including a plurality of central selector relays, said central selector mechanism including a contact assembly and a plurality of pairs of wipers each pair of which is part of one of said central selector relays and is adapted to be moved in step-by-step fashion to successively engage the various pairs of contacts of said contact assembly, said contact assembly comprising a pair of angle-bars between which are mounted a plurality of bridge members of insulating material and a plurality of rods extending parallel to said angle-:bars and rigidly supported by said bridge members, the combination with one of said relays of an impulsing mechanism at one of said stations to produce a variety of impulse designs in accordance with which the pair of wiper arms assume a position on said contact assembly.

9. In apparatus of the character described, a contact assembly comprising, a pair of frame members rigidly supported in spaced parallel relationship, a plurality of arcuate bridge members of insulating material extending in parallel relationship between said frame members and having a common axis which is parallel to said frame members, a plurality of contact rods rigidly supported by said bridge members in parallel relationship with respect to said common axis and substantially on a plane which forms a segment of a cylinder, and a plurality of contact clips attached to each of said bndgwnehz-Jers and insulated from said contact rods.

THEODORE N. SAATY.

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