US2385339A - Signaling device - Google Patents

Description

Sept. 25, 1945. (5, E ATKlNs 2,385,339 SIGNALING DEVICE yFiled oct. 2e, 194s 2 sheets-sheet 1 46] 22 I6) l5 I6, 35 l? 33 ATTORNEY Sept' 25, 1945 G. E. -ATKlNs l 2,385,339

/N VEN To@ @y G. E. A Tlf/NS y ATTORNEY Patented Sept. 25, 1945 UNITED STATES PATENT OFFICE SIGNALING DEVICE Application October 26, 1943, Serial No. 507,705

9 Claims.

This invention relates to signaling devices and particularly to such devices as employed to gencrate and record telephone call signals in a sound powered telephone system.

Sound powered telephone systems are, in general, characterized by the absence of auxiliary power sources, such as batteries, for furnishing the power required for the transmission of speech signals. In such systems speech signals are generated in the coils of an electromagnetic sound powered unit comprising essentially a permanent magnet, a balanced armature and a diaphragm coupled to the armature. In a transmitter unit the diaphragm is acoustically actuated by speech signals impinging on the diaphragm and the armature is correspondingly vibrated in the field furnished by the permanent magnet to cause the generation of speech frequency currents in the coils. Conversely, in a receiver unit speech frequency currents applied to the receiver coils cause the armature and its coupled diaphragm to vibrate at the frequency of the incoming signals to produce audible speech signals.

Such systems are lacking in complete simplicity in that the transmission of telephone call signals1 requires the use of auxiliarybatteries for the energization of the call indicator, particularly where it is desirable that the manifestation of an incoming call persist indenitely and until such time as the call is answered at the called station. In a particular system of this character, a visual signal in the nature of an electronic tube is employed as a call indicator and responds to the transmission of an acoustic signal of a level higher than the level of speech signals to visually indicate the arrivai of an incoming call. Such a call signal requires a biasing Voltage, furnished by a battery, not only to eiect its operation but also to maintain it locked operated until extinguished by some act on the part of the subscriber at the called station or of an opera-tor at an exchange.

It is the object of this invention to provide an improved combined audible and visual signal device which functions without the aid of batteries or other auxiliary source of power to furnish a permanent call signal in a sound powered telephone system.

This object is attained in accordance with a feature of the invention by combining, in a unitary structure, a visual signal indicator, in the nature of an annunciator drop, and an audible signal device, in the nature of a vibratable gong, and by placing the operation of both devices under the single control of an ultra-sensitive electromagnetic system consisting essentially of a -coil and a balanced armature system including pole-pieces, permanent magnet means for producing a ilux between the pole-pieces and an armature vibratable in the air gap located between the pole-pieces.

More particularly, the combined visual and audible signal device of this invention embodies an electromagnetic system of the type dened above whose armature is loosely coupled to a latch bar and when vibrated causes the latch bar to release a gravity operated mechanism, which combines an annunciator drop signal, or target, and the striker for a vibratable sound emitting device in such a manner that the target is operated as a visual signal and the sound emitting device is simultaneously actuated as an audible signal.

Another feature of the invention resides in mechanically coupling the sound emitting device with its operating unit whereby the unit functions, in response to the Vibrations of the sound signal, as an inertia type transmitter to provide an answer-back signal in a sound powered tele- `phone system.

In systems of the general character described above the call signal is initiated at a calling station either by shouting into the telephone transmitter or by slapping the transmitter mouthpiece. Either operation serves to compress the air in the cavity in front of the diaphragm with which such transmitters are equipped, causing the diaphragm to move back and swing the attached armature far off center in one direction. This action induces a surge of current in the coil surrounding the armature. The armature in snapping back overthrows center and induces a second surge in the coil in the opposite direction. In order to simplify the generation of such call signals the telephone handset employed in a system in which the combined visual and audible signal device of this invention is used to particular advantage, is equipped with a manually operable button which functions, through a plucking mechanism, to directly agitate the receiver diaphragm and thus generate, in the receiver coils, a call signal of sufficient intensity to actuate the combined visual and audible signaling device as a call indicator.

These and other features of the invention will be readily understood from the following description when read in connection with the accompanying drawings, in which:

Fig. 1 is a View of the ultra-sensitive signal device taken along the line I-I of Fig. 2, looking in the direction of the arrows, and shows the target, or drop which constitutes the Visual signaling element;

Fig. 2 is a top plan view of the signal device;

Fig. 3 is a view of the signal device taken along the line 3--3 of Fig. 2, looking in the direction of the arrows;

Fig. 4 is an outline view of the receiver portion of a sound powered telephone handset showing the diaphragm actuating mechanism and its operating button;

Figs. and 6 are detail views of the dlaphragm actuatingmechanism showing the same in its normal and operated positions, respectively; and

Fig. '7 is a circuit diagram showing schematically a sound powered telephone handset located at the calling end of a line and the ultra-sensitive call signal device located at the answering end of the line.

The basic element of the signaling device shown particularly in Figs. 1, 2 and 3 and schematically in Fig. '7 is an electromagnetic system comprising essentially a coil and a balanced armature system including pole-pieces, permanent magnet means for producing a flux between the pole-pieces and a vibratile armature. This element is mounted on a base plate I3 preferably of a non-magnetic material such as brass and comprises a pair of substantially identical U-shaped magnetic members I2 and a pair of similar short bar magnets I3. Each of the magnetic members I2 comprises a rpair of parallel pole tips or anges I4 and arms I5 extending from opposite sides of the tip's or flanges I4. The arms I 5 abut opposite ends of the magnets I3 which space the members I2 in parallel relation, with the tips or flanges of one member I2 opposite and aligned with those of the other whereby two identical air gapsare formed. Like poles of the magnets I3 abut the same magnetic member I2 so that two magnetic circuits of substantially the same reluctance and magnetomotive force having a common branch through the pole tips I4 and the air gaps are formed.

The ends of the magnets I3 are ground so that air gaps of the desired length are formed between juxtaposed pole tips I4. The magnetic members I2 are securely clamped against the magnets i3 by non-magnetic bolts I5 which extend through apertures in the base plate I0. Preferably, the magnets I3 vare provided with longitudinal grooves I'I as shown in Fig. 2, in which the bolts I6 are fitted and thereby position the magnets with respect to the plate I0.

Extending between the pole tips I4 with its ends located in the air-gaps between juxtaposed pole tips I4 is a magnetic armature I8 which is pivotallsr mounted at its center between non-magnetic supports I9 and has one end aiixed to the connecting pin or rod 20. The supports I9, which may be, for example, phosphor bronze strips notched at their adjacent ends to engage the sides of the armature are fitted into slots 2| in parallel non-magnetic support blocks 22 and are locked in the slots as by screws or bolts 23. The blocks 22 in turn are alixed to the lower magnetic member I2 by screws 24 threaded into the blocks.

The armature I8 is encompassed by a pair of coils 25 carried by insulating forms or bobbins 23 positioned between the flanges or pole tips I4. Electrical connection may be made to the coils 25 through suitable conductors.

Fixed in any suitable manner to the upper magnetic member I2 is a bracket 39 having a pair of oppositely disposed upturned projections which are apertured to receive the rod 3I. The rod 3| passes through a latch bar 32 and provides a pivot bearing therefor. At its right end, viewing Figs. 2 and 3, the bar 32 is provided with a bore or hole through which the free end of rod or pin 2i) extends. The upper end of the rod 2i) is flared slightly and is provided with a fixed collar 33 so that the rod 29 may experience an upward thrust,

viewing Fig. 3, without influencing the latch bar 32 but when pulled downward it will cause the latch bar 32 to pvot on the rod 3| to cause its forward end to be raised.

The latch 32 is notched near its forward end to receive the upper edge of a weighted element 34 and to thereby retain the element 34 in its normal unoperated position shown in Fig. 3. The weighted element 34 has fixed thereto, in any suitable manner so as to project outwardly therefrom, a clapper rod 35 which carries at its end a striker 3B. The element 34 is carried by and xed to the rod 31 which has one end supported by a set screw 38 carried by an extension 39 of the plate I and its other end passing through an aperture in a similar oppositely disposed extension 49 of plate I9.

The rod 3'! carries a collar 4I which is fixed to the rod and abuts the inner surface of the plate extension 48. Fixed to the collar 4I is a rod 42 which carries a target 43. The target 43 normally assumes a position directly in back of the circular hole 44 located in the plate extension 40. Near its outer end the rod 31 carries a pin or handle 43 which, as will be described hereinafter, is manually operable to reset the target.

Aixed to the under-side of the plate Il) is a gong 48 which may be secured to the bolt 49 by means of a nut 5l). The bolt 49 itself is screwed into a threaded hole in the plate I0. By virtue of this mounting the gong is mechanically coupled to the electromagnetic unit for a purpose to be indicated hereinafter. The gong is so positioned relative to the clapper rod 35 and its striker 36 that when the weighted element is actuated, as will be described presently, the striker 36 contacts the gong causing it to vibrate. To permit the clapper rod 35 freedom of movement, the plate I 0 is slotted at 55 and the inner edge of this slot is so disposed relative to the edge of the gong that the striker 36 statically clears the gong after having struck it, thus allowing undamped vibrations of the gong.

When the coils 25 are energized, the armature I8 is vibratedk and. through the loose coupling effected by the connecting rod 20 the latch bar is actuated and pivots about the rod 3|. The forward end of the latch is thus raised causing the release of the weighted element 34 which rotates, under the action of gravity, with the rod 35 in a counter-clockwise direction as viewed in Fig, 3. The striker 36, accordingly, impinges against the gong 48 causing the latter to vibrate and emit an audible tone. The shaft 31 in rotating carries with it the target 43 so that it is removed from its normal position in back of the aperture 44. It will be understood that, in practice, a plurality of such devices would be mounted on a switchboard and the disappearance of the target would identify the particular line calling. If desirable the gong may bevmade common to a plurality of such devices to function as a cornmon audible signal in conjunction with a plurality of individual line identifying visual signals.

In Fig. 4 there is disclosed a sound powered unit of substantially the same type disclosed in Figs. 2 and 3 and mounted in the receiver portion of a telephonehandset. The unit disclosed in Fig. 4 distinguishes from that shown in Figs. 2 and 3 principally in that a diaphragm 6D is Xed to the connecting rod 2U in place of the latch bar 32. Suffice it to say that when the diaphragm is agitated, the armature I8vis vibrated causing an electromotive force to be generated in the coils 425', As a means for agitating the diaphragm 60 there is disclosed a plucking mechanism comprising a reed spring 62 which is arched at its center and has each of its ends turned in and secured to the supporting bracket 63 by rivets 64 or by any other suitable means. At one end` of the spring there is integrally formed a plucking finger 65. As shown in Fig. 5, the hooked end of the nger 65 is normally located opposite and below the end of a projection 66 iitted to the diaphragm 69. A button 61 which protrudes through an aperture in the handset casing 68, as shown in Fig. 4, has its operating end abutting the spring 62 at the apex of its arch. When the button is depressed by the thumb of the party employing the handset, the spring 62 assumes the position illustrated in Fig. 6. During the transition from normal to operated positions the inclined end of the plucking finger 65 is raised to the position shown in i Fig. 6 and in moving to this position it passes over the edge of the projection S6 causing the diaphragm to be agitated. When the button 6'! is released it is restored to normal by the action of spring 62 in resuming its normal unactuated condition. In snapping back to its normal position the nger 65 again agitates the diaphragm 60 through the projection 66.

The E-shaped member 68 mounted on the bracket 63 has a central portion which serves as a stop for the button 61 and limits its downward movement. The two outer portions insure uniformity in the operations of the spring as well as correct action of the plucking linger 65 on the diaphragm projection 66. .In locating the projection 56 on the diaphragm consideration must be given to the desired intensity of the call signal. In aixing the projection substantially midway between the corrugations 'l0 of the diaphragm 53 and its support at 'Il the diaphragm is agitated sufliciently to produce a signal of average intensity. If a greater intensity is desired the point of attachment of the projection E6 would be closer to the corrugated portion of the diaphragm and further removed from the support 1I.

The button 61 is provided with a collar 'l2 which abuts the rim of the aperture through which the shank of the button protrudes from the casing and is normally held in this position by the action of spring 62. The bracket 63 is secured to the receiver unit by screws 18. f

Referring now to Fig. '7, the line L is shown terminating at two remotely separated points in jacks J1 and J2. The jack J1 may be located at a calling station and the jack J2 at a central switchboard. When it is desired to communicate with the central station over line L the party whose station is equipped with the handset S would connect the set to the line by inserting plug P into jack J1 and then depress the button 6l `and release it. The diaphragm 66 is thus agitated in the manner hereinbefore described and a corresponding current generated in the coils This current traverses the line L by way of the normal contacts of push to talk key H and the contacts of plug P and jack J1 and energizes the coils 25 of the combined audible and visual signal D at the central ofiice. The armature i3 vibrates at the frequency of the current traversing the coils and actuates the latch 32 in the manner previously described. The weighted member 34 is thereby released and falls, due to the action of gravity, to the position indicated by the dash-dot outline shown in Fig. 3.

The gong 48 is struck by the striker 36 and the target 43 moved to an indicating position.

It will be observed that due to the loose coupling of the armature I8 and the latch 32 as effected by the connecting pin 20, the latch will be actuated on the iirst surge of current if of a polarity such as to cause the armature to pull the connecting pin 2|] downwardly, viewing Fig. 3. However, if the first current surge is of the opposite polarity the pin 28 moves freely in the hole in the latch 32 and will function on the second current surge to actuate the latch. Thus it is unnecessary to polarize the call signal indicator so as to render it operative on a particular polarity of incoming current and no undue strain is placed on the armature or on the connecting pin should the polarity of the first current surge be such as to move the pin upwardly, viewing Fig. 3.

Due to the mechanical coupling of the gong with the call indicator unit the vibrations of the former when actuated are transmitted to the indicator unit causing it to function as an inertia type transmitter and the voltage resulting from the reverberations of the gong and induced in the coils 25 is transmitted back over the line L to the receiver of the telephone set S at which the call signal was initiated. The receiver unit responds' to this voltage to produce an answer back signal as an indication that the call signal has been successfully recorded at the called station.

As previously described, the plate I0 is slotted at 55 to allow freedom of movement of the clapper rod 35 to and from its actuated position. The rod 35 when actuated strikes the back edge of the slot 55 and is designed to have sufficient weight and flexibility to continue in its movement towards and to strike the gong and then to come to rest in a position in which the striker 36 statically clears the gong. This static clearance precludes the striker resting against the gong and damping its vibrations after it has been struck.

After receipt of the combined audible and visual call signal, the operator at the central station .would restore the signal unit to normal unoperated condition by rotating the hand lever l in a clockwise direction thereby rotating the shaft or rod 3l and the associated clapped rod and target to normal positions. In this position the edge of the weighted member 34 reengages the groove or slot near the outer end of the latch 32 and is thereby maintained in its normal restored position. The call may be answered in the usual well known manner.

After the calling subscriber has received the answer back signal, as above described, the button il may be actuated to eiifectively remove the coils 25 of the receiver unit from the line and the transmitter unit utilized for the transmis- A sion of speech signals over the line L.

The telephone set S has been illustrated as equipped with a plug ended cord for associating the set with-the line L. It will be understood that the connection of the set to a line may be made by the regular switchhook contacts which are housed within the stand or cradle support usually provided for supporting the yhandset It will also be understood that when the line L is seized at the central station in response to the actuation of the combined audible and visual signal device D the circuit to the coils 25 is opened at the jack contacts 19 to effectively remove the` coils from the line during the transmission of speech signals.

What is claimed is:

1. The combination, in a signalling device, of a sound emitting device, a striker therefor, gravity operated means for Vcontrolling the operation of said striker, a latch normally maintaining said gravity operated means in restrained position, and means for actuating said latch to release said gravity operated means comprising an electromagnetically operated device including a balanced armature, and means comprising a connecting pin loosely coupling said latch and said armature.

2. The combination, in a combined audible and visual telephone call indicating apparatus, of a sound emitting device, a target indicator having a normal display position, a striker for said sound emitting device, a rod supporting said target indicator and said striker, a weighted element carried by said rod and adapted, when released, to rotate said rod to cause said striker to actuate said sound emitting device and said target indicator to be moved from its4 normal position, a latch normally engaging said Weighted element and holding it in a restrained position, and means for actuating said latch comprising an electromagnetic system including a balanced armature, and a connecting pin fixed to one end `of said armature and loosely associated with said latch.

3. The combination deiined in claim 2 wherein manually operable means is mounted on said rod for restoring said striker and target indicator to normal positions.

4. The combination, in a call indicator, of a sound emitting device, a striker therefor, and an electromagnetic system for actuating said striker including a base-plate, an electromagnetic unit mounted on said base-plate comprising a pair of permanent magnets having oppositely disposed juxtaposed pole-pieces, an armature pivotally mounted at its mid-point so that its extremities extend into the air-gaps effected by said juxtaposed pole-pieces, a coil encircling said armatureresponsive to alternating current for vibrating said armature, means controlled by said armature, when vibrated, for causing said striker to actuate and vibrate said sound emitting device, and means mechanically coupling said sound emitting device to said electromagnetic unit whereby said unit functions in response to the vibrations of said sound emitting device as an inertia type transmitter and a current, corresponding in frequency to the frequency of vibration of said sound emitting device, is developed in said coil.

5. In combination, an armature, an electromagnetic unit comprising a coil and a magnetic circuit including air-gaps in which said armature vibrates upon the application of alternating current to said coil, said unit being vibratable relative to said armature to cause a current of a frequency, corresponding to the frequency at which said unit is vibrated, to be developed in said coil, and means for vibrating said unit relative to said armature comprising .a vibratable sound emitting device mechanically coupled to said electromagnetic unit, and means for vibrating said sound emitting device.

6. In combination, an armature, an electromagnetic unit comprising a coil and a magarmature vibrates upon the application of alternating current to said coil, said unit being vibratable relative to said armature to cause a current of a frequency, corresponding to the frequency at which said unit is vibrated, to be developed in said coil, and means for vibrating said unit relative to said armature comprising a vibratable sound emitting devict,` mechanically coupled to said electromagnetic unit, and means for vibrating said sound emitting device comprising a striker controlled by said armature.

7. The combination, in a combined audible and visual signaling device, of a vibratable sound emitting device, an annunciator target having a normal display position, a striker for vibrating said sound emitting device, common means supporting said striker and said annunciator target, gravity operated means for controlling the operation of said common means, means comprising a latch for maintaining said gravity operated means in a normal restrained position, land means for actuating said latch to cause the release of said gravity operated means whereupon said striker engages said sound emitting device and said annunciator target is moved from its normal position, comprising a vibratable armature, alternating current responsive means for vibrating said armature, and means loosely coupling said armature and said latch.

8. In combination, in a signaling device, a vibratable sound emitting device, means for actuating said sound emitting device, an electromagnetic unit including a coil and a vibratable armature, said coil being responsive to alternating current rfor vibrating said armature, means responsive to the vibration of said armature for causing said actuating means to vibrate said sound emitting device, and means mechanically coupling said sound emitting device and said electromagnetic unit whereby the vibrations of said sound emitting device are transmitted to said electromagnetic unit to cause the generation in 'said coil of a current of a frequency corresponding to the frequency of vibration of said sound emitting device.

9. In a combined audible and visual call indicating apparatus, a vibratable gong, a striker for vibrating said gong, a target, a rotatable rod xedly supporting said striker and target, gravity operated means for rotating said rod to cause said striker to strike said gong and said target to assume a signal displaying position, said gravity operated means being fixed to said rod, a latch normally engaging said gravity operated means so.as to hold said rod in a restrained position, and means for actuating said latch to release said gravity operated means and thereby cause said rod to be rotated comprising an electromagnet having juxtaposed flux producing permanent magnet poles, an armature mounted at its midpoint so that its extremities assume positions between juxtaposed poles of said electromagnet whereby said armature is normally held in a condition of balance by the permanent magnet ux, and a coil encircling said armature and responsive to alternating current to cause said armature to oscillate, and means coupling said armature and said latch in such a manner that said armature when actuated in one direction moves independently of said latch and when moved in the opposite direction functions to actuate said latch.

GEORGE E. ATKINS.

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