US2491902A - Batteryless impulse transmitter - Google Patents

Description

Deb. 20, 1949 J, (JSTUNE 2,491,902

BATTERYLESS IMPULSE TRANSMITTER Filed May 9, 1946 INVENTOR. JOHN E. OSTLINE ATTORNEY Patented Dec. 20, 1949 BATTERYLESS DWPULSE TRANSMITTER John E. Ostline, Chicago, 111., assignor to Automatic Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application May 9, 1946, Serial No. 668,449

3 Claims.

The present invention relates in general to impulse transmission and more particularly to impulse senders or calling devices of the type employed in telephone and like signalling systems.

Such calling devices most frequently take the form of a manually operable dial, and it has been customary in the past to provide each dial with impulse contacts arranged to generate impulses by momentarily interrupting the flow of battery current in a suitable signalling circuit. The need for a battery or some similar source of current connected to the signalling circuit to supply the current therein has made it impractical to employ a conventional dial in some situations, however (for instance, in sound powered telephone systems where no such source of current is readily available). Moreover, even where a source of direct current is at hand it frequently is undesirable to employ interrupted direct current signalling, due to the transmission characteristics of the Signalling circuit or for other reasons.

It is the general object of the present inven tion, therefore, to provide a dial which will be suitable for use in the above situations, and which is simple and economical in construction and reliable in operation.

In keeping with this object one feature of the invention resides in the provision of a calling device which does not depend upon a battery or any similar auxiliary source of current for its ability to produce electrical impulses.

Another feature resides in the provision of a calling device capable of generating impulses which are better suited for transmission over signalling circuits of the kind frequently encountered in practice than are make-and-break direct current impulses. In particular, each impulse generated by the calling device of the invention comprises a transitory impulse of current.

Impulses of this character are obtained by providing interlinked magnetic and electrical circuits on the calling device, together with dialcontrolled means for altering the linkage between the two in order to generate impulses in the electrical circuit. More specifically, the mag netic circuit is energized by a permanent magnet at the calling device, and mechanism is provided to alternately increase and decrease the reluctance of the magnetic circuit thereby to induce impulses into the associated electricalcircuit. These impulses alternate in polarity, and according to another feature of the invention the impulses of one polarity are higher in voltage 2 and have a steeper wave front than do those of the opposite polarity.

Qther objects and features of the invention will be made clear in the ensuing description of one embodiment thereof, reference being made to the accompanying drawings wherein:

Fig. l is a side elevation of the calling device according to the invention,

Fig. 2 is a rear elevation of the calling device,

Fig. 3 is a cross-sectional view taken along the line 3-fi of Fig. 1, showing the magnetic circuit of the calling device and. the electrical coil associated therewith,

Fig. i is a view taken along line t-- l of Fig. 2,

Fig. 5 is a schematic diagram of the calling device showing same connected to a suitable re-- sponding device, and

Fig. 6 shows a modified arrangement of the magnetic and electrical circuits in the calling device.

The calling device of the instant invention is substantially identical to that shown in Obergfell Patent No. 1,642,822, granted September 20, 1927, with the exception that the impulse cam of the patent has been modified in shape and the associated impulse contacts have been replaced by an improved magneto or induced impulse generator which now will be described.

This generator comprises a permanent magnet.

good retentivity, such as an alloy containingaluminum, nickel, and cobalt, while the pole pieces may be of soft iron or other suitable mag netic material. One of the pole pieces E3 provided with an extension of reduced size over which a coil l 4 is fitted; the end of the pole piece, being bent over at [5 to hold the coil in place and also to form a pole face of enlarged area.

Adjacent the other pole piece E2 is a nonmagnetic channel member 58 formed of brass or like material. A pair of nonmagnetic screws 5"! extending through the channel member and pole pieces serve to clamp these members securely to magnet II. This forms a rigid assembly which is attached to the body of the dial it? by means of nonmagnetic clamping block it and a screw 2| extending therethrough into a tapped hole in H3.

A portion of the channel I6 is cut away at one end, leaving a pair of forwardly projecting lugs 22 which carry a pivot pin 23; and a pivotal armature 24 is mounted on this pin. Made of soft iron or other suitable magnetic material, the

armature has a strip of nonmagnetic material 25 rigidly affixed thereto by screws 26. One end of this strip is arched away from the armature to provide a space between the strip and the armature for receiving pivot pin 23. The other end of the strip comprises an elongated finger which is adapted to cooperate with the impulse cam 21.

In order to dial a digit the finger hole plate 23 is rotated away from its normal position in the usual manner and permitted to restore. During the return of the plate to normal under the influence or" its restoring spring 29, the dial gear train causes cam 21 to rotate in a counterclockwise direction at a uniform speed controlled by the governor til, the number of revolutions of the cam being determined by the value of the digit dialled, as is described in the before-mentioned Obergiell patent. The cam is so shaped that during the first one half revolution thereof it causes the extended finger 25 to move armature 22- rather slowly away from its normal position against pole face it. At the end of the first half revolution the set-0 1T in the cam permits the armature to snap back against the pole face, it being understood that the armature is always pulled in this direction due to the attractive forces which are set up between the pole face and the armature by magnet. l l. This mode of operation is repeated on the ensuing half revolutions of cam 21.

Each movement of the armature away from pole face it increases the reluctance of the mag.- netic circuit (shown dotted in Fig. 5), and the consequent change in flux linkage with coil l4 induces in] the coil a transitory voltage impulse of a certain polarity; conversely each time the armatm'e snaps back to normal from the position to which it has been displaced by cam 21 the reluctance of the magnetic circuit is reduced, producing a flux changewhich. induces in the coil transitory voltage impulse of the opposite polarity- Ehe rate of change in flux linkage manifestly is considerably faster when the armature snaps back to normal than when the camslowly moves the armature away from normal, and accordingly the impulse induced in the coil on the return movement of the armature has' a somewhat higher voltage and a steeper wave front than the impulse induced during the armatures movement away from normal.

Consi erable variation. in. the strength and wave-i of the impulses generated by the dial may be obtained by altering the space relationsh'L reen the finger. 25 and cam 27; this adjustment is easily made by loosening screw 2!, mo the magnetic structure of the induced impuise generator slightly on the base i8 thereby to alter the position of 25 with respect to the'cam,

then again tightening screw 21. use, the coil Hi may beconnect'edover a line to any suitable form of impulse registering-equipm t, it being remembered that no auxiliary roe electrical current needs tobe connected to th line to energizeithe-registering-equipment. Fo instance, as shown'in Fig. 5;-it may be connest over line to a relay 32 which is so poi uhat it will respond only to the impulses impressed upon the iinewhen the armature snaps back normal, contact 33 thus closing momentar to transmit an impulse over conductor 34 res onsive to each return of the armature 2A to normal.

Fig. 6 illustrates schematicallya modifiedfo'rm' of induced impulse generator for use in the dial,

tel

wherein the magnetic circuit comprises a permanent magnet 35, two identical pole pieces 36 and 3'5, and an armature 38. The armature is free to turn above a pivot 39, but normally is held by a spring ii in the position shown, so that the from magnet 35 follows the path indicated by solid arrows. When cam 2? rotates in a counterclockwise direction due to an operation of the finger hole plate of the dial, it slowly moves armature 38 against the tension of spring H to the position shown dotted and then permits the armature to snap back to normal under the influence of the spring, this process being reonc for each half revolution of the cam.

On the slow movement of the armature to its dotted position the direction of flux through said armature reverses, as indicated by the dotted arrows, and this induces in a coil 42 which encircles the armature a transitory voltage impulse of a certain polarity; on the more rapid return of the armature to normal the flux through the armature again reverses, inducing in the coil a voltage impulse of the opposite polarity. Since the latter flux reversal takes place more quickly than the former, the consequent impulse induced in coil 42 is of a higher voltage and has a steeper Wave front. The terminals of coil l2 may be connected over a line to any suitable responding device, as explained in connection with Fig. 5.

Having described the invention in detail, what I believe to be new and desire to have protected by Letters Patent is set forth in the appended claims.

What is claimed is:

1. In an impulse sender, a magnetic circuit including a pole piece and an armature, a coil encircling a branch said magnetic circuit, a manually operable finger dial rotatable in accordance, with the number impulses to be trans'l-iitted, spring means normally holding said armature in position against said pole piece and cam means controlled by the operation of the dial for noving the armature slowly away from its pole piece to induce a single weak impulse of current in one direction in said coil and cooperating with said spring means to cause said armature to restore rapidly to its original position to induce a s 'de strong impulse of current in the opposite d tion in said coil for each impulse to be mitted.

2 An impulse sender having a rotatable dial manually rotated to different positions and hav-- ing means for rotatably returning said dial after each manual operation, a magnetic circuit including a pole piece and an armature, a cam, coupling means for coupling said cam to said dial only on said return movement of said dial, said cam controlled by said coupling means on the return movement of the dial to move the armature slowly in a single movement in one direction away from its pole piece and spring means for quickly returning said armature to its pole piece in another single movement in the opposite direction for each movement of the dial through one position on said return movement, a coil wound around a portion of the magnetic circuit, a single weak impulse of current being induced into said coil by a slow change in reluctance in said magnetic circuit in response to each slow movement of said armature in said one direction and a single strong impulse of current be ing induced in said coil by a quick change in reluctance in said magnetic circuit in response to each said quick return movement of said armature in said opposite direction for each position through which the dial rotates on said return movement.

3. In an impulse sender, a magnetic circuit including pole pieces and an armature normally held against said pole pieces, a coil encircling said armature, a manually operable finger dial rotatable in accordance with the number of impulses to be transmitted, cam means controlled by the operation of the dial for moving said armature in a number of alternate slow and rapid movements of said armature dependent upon the number of impulses to be transmitted, one end of said armature being moved slowly away from one of said pole pieces to the other of said pole pieces and the other end of said armature being moved slowly away from said other pole piece by said cam means to said one pole piece to slowly reverse said magnetic circuit through said armature to thereby induce a weak impulse of current in one direction in said coil in response to each slow movement of said armature. a spring connected to said armature for returning said armature to normal, said armature jointly controlled by said spring and said cam means for causing said armature to restore rapidly to normal to rapidly reverse said magnetic circuit back to normal to thereby induce a strong impulse of current in the other direction in said coil in response to each rapid movement of said armature.

JOHN E. OSTLINE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,307,342 Brown June 24, 1919 2,136,630 Massonneau Nov. 15, 1938 2,220,088 Dowey Nov. 5, 1940 2,254,378 Mallina Sept. 2, 1941

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