US1535527A - Vibratory system - Google Patents

Description

April 28, 1925. 1,535,527

' H. C. HARRISON VIBRATORY SYSTEM Filed Jan. 1923 PHASE SH/FYER flvvemar: Haw/y Ch r/son by 456 W W.

Patented Apr. 28, 1 925.

UNITED STATES PATENT OFFICE.

HENRY C. HARRISON, OF PORT WASHINGTON, NEW YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

'VIBRATORY SYSTEM.

Application filed January 3, 1923. Serial No. 610,528.

To all whom it may concern.

Be it known that I, I'IENRY C. HARRISON, a citizen of the United States, residing at Port Washington, in the county of Nassau, I State of New York, have invented certain new and useful Improvements in Vibratory Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to vibratory systerns, and more. particularly relates to inechanical vibratory systems which are electrically driven. k One object of this invention is to reduce distortion in a vibratory system.

Another object is to provide means and methods for damping the mechanical vibration of a moving system.

As is well-known in theart, mechanical vibratory systems, such as a telephone receiver diaphragm, or the like, frequently possess resonance characteristics and tend to overemphasize certain frequencies or handsof frequencies, thereby failing to give faithful reproductions of the impressed forces. This resonance is not a serious objection in many cases, but occasions do arise when it is found desirable to. provide some means for overcoming the resonance effect by damping, for example. Y Y 80 In accordance with one form of this invention, a mechanical vibratory system is given a substantially constant response over a wide frequency range by causing a part-of the vibratory system to act as an armature 85 for an electro-magnet which has a magnetizing winding connected to the input terminals of a vacuum tube amplifier. The output terminals of the amplifier are connected to an auxiliary winding on the electromagnet in such a manner that the alternating currents in the auxiliary Winding neutralize the reactive component of the magneto-motive forces of the alternating currents in the first winding. That is, the reactive component of the impedance opposing the flow of eddy currents in the first winding due to the voltages generated by thevibration of the armatureis neutralized so that there will be no reactive effect due to the storage of power in the system, thus giving a pure resistance damping. This arrangement for producing damping by the neutralization of the reactive component of the impedance of the magnetizihg winding is of wide application and capable of use in various types of mechanically vibrating systems.

Referring to the drawings, Fig. 1 illustrates this invention adapted to dampen the vibrations of a telephone receiver diaphragm; Fig. 2 shows how this invention may be applied to dampen the vibrations of the armature of an electrical phonograph recorder; and Fig. 3 illustartes one type of phase shifter which may be employed with this invention.

Referring to Fig. 1, an electromagnetic receiver is disclosed therein comprising a diaphragm 7, coupled by members 8 and 9 to an armature 10, which is pivoted between the pole pieces of a permanent magnet 11. Surrounding the armature 10 are two coils 12 and 13, which are connected to a suitable incoming line 14, such as a telephone line. Alternating currents present in line 14, will in a manner well-known in the art, cause armatu're 10 to vibrate, thereby causing, the vibration of the diaphragm 7, so that sound waves are produced by the diaphragm cor responding to the currents present in line 14. Such an arrangement, however, frequently tends to over-em hasize certain frequencies or hands of requencies, due to resonance in the diaphragm.

Inaccordance with this invention this over-emphasizing of certain frequencies by the telephone diaphragm may be substantially avoided and the vibrating system given a substantially constant'response over a Wide frequency range by having the mechanical system damped in a manner now to be described.

A small electromagnet 15 is placed adj acent the magnetic member 9, whereby the vibration of the armature 10 will cause member 9 to be moved towards and away from the pole pieces of electromagnet 15 in accordance with the signaling or other alternating currents present in line 14. The

magnetizing winding 16 for electromagnet 15 has its terminals connected in series with a source of voltage 17, and a low resistance 18, one side of resistance 18 being connected through a condenser 19 to the control electrode, and the other side of resistance 18 to the cathode of a vacuum tube amplifier 10. The output terminals of amplifier 20 are be so adjusted that the currents in coil 22 substantially neutralize the reactive component of the magneto-motive forces present in the magnet 15 due to the currents in coil 16. With such an arrangement, the eddy currents will be in phase with the voltage induced by the armature vibrations that is in phase with the velocity of the armature and so will give a pure resistance damping. The amount of damping, of course, will be dependent, to some extent upon the size of electromagnet 15 and the number of turns and resistance of winding 16, since the greater the number of turns in winding 16 and the lower the resistance the greater will be the damping.

Electromagnet 15 willftherefore, dampen the vibration of armature 9 and will substantially eliminate the resonance characteristics of the diaphragm 7 whereby the telephone receiver will have a substantially constant response over a wide range of frequency for the currents present in line 14.

The phase shifter 21 may be of a suitable type either of a single section or' a plurality of sections, depending upon the phase shift desired, and also upon the range of frequencies for which it is desired to produce a constant displacement in phase. Fig. 3 for example shows a phase shifter comprising series inductances 40, 41 and 42 and shunt capacities 43 and 44.

Fig. 2 is similar to Fig. 1, except that an electromagnet 15 has its pole pieces close to the pivoted armature 25 of a permanent ma net 26 of an electrical phonograph recorde'r. The lower end of armature 25 is shown to be terminated in a suitable needle 27, which may be employed for producing a sound record 28 corresponding to the electrical currents present in line 29, which is connected in circuit with the two coils 30 and 31 surrounding the armature. Winding 16, amplifier 20, battery 21 and auxiliary winding 22 may therefore be employed in the same manner as in Fig. 1 whereby resonance characteristics in the vibration of armature 25 may be substantially elimimated by the damping effect due to the pres ence of the electromagnet 15 and the presence of the special equipment connected thereto.

The above specific forms of this invention are merely illustrative of the wide field in which this invention may be employed,-and it is to be understood that this invention may be employed in forms widely different from those just described without departing in anywise from the spirit of this invention as defined in the appended claims.

The invention claimed is:

1. A. vibrating system subjected to a force for causing the system to vibrate, a magnetic member subjected to flux variations when said system vibrates a coil surrounding ,said member, means for supplying direct current to said coil, an auxiliary coil'on said member, and means for producing in said aux-- iliary coil alternating currents which substantially neutralize the reactive component of the magneto motive forces of the alternating currents in said first coil produced by the vibration of said system.

2. A vibrating system subjected to a force for causing the system to vibrate, a magnetic member subjected to flux variations when said system vibrates, a coil surrounding said member, and means responsive to said flux variations for substantially neutralizing the reactive component of the magneto motive forces of the alternating currents in said coil produced in said coil by the vibrations of said system.

3. A vibrating system subjected to a force for causing the system to vibrate, a magnetic member subjected to fiux variations when said system vibrates, a coil surrounding said member, amplifying means having input and output terminals, an auxiliary coil on said member, connections between said input terminals and said first coil, and connections between said output terminals and said auxiliary coil, said connections being arranged to produce in said auxiliary coil alternating currents producing magneto motive forces opposing the alternating currents produced in said first winding by the vibration of said system.

4. An electromagnet having an armature, a plurality of windings on said magnet, a vacuum tube having input and output terminals, connections from said input -terminals to one of said windings, connections from said output terminals to a second of said windings, and phase shifting means in said output circuit.

5. An electromagnet having an armature, a plurality of windings on said magnet, a vacuum tube having input and output terminals, connections from said input terminals to one of said windings, means for impressing an audible frequency on said winding. connections from said output terminals to a second of said windings, and means for preventing said tube from singing at' an audible frequency.

' 6. In combination, a magnet having a pivoted armature, a winding surrounding said armature, an electric circuit connected to said winding to cause said armature to vibrate in accordance with currents present in said circuit, an auxiliary electromagnet ubjected to flux variations when said armature vibrates, a magnetizing Winding for said electromagnet, a vacuum tube amplifier, means for supplying direct current to said winding, means for impressing on said amplifier potential variations corresponding to the potential variations produced in said winding by the said flux variations, and means for causing the potential variations amplified by said amplifier to produce magneto motive forces which substantially neutralize the reactive component of the alternating currents in said winding. I

" 7. In combination, a magnet having a pivoted armature, a winding surrounding said armature, an electric circuit connected to said winding to cause the vibration of said armature in accordance with alternating current variations in said circuit, and means for damping the vibration of said armature, said means comprising an an}. iliary electromagnet subjected to flux variations when said armature vibrates, a magnetizing Winding on said electromagnet, means for supplying direct current to said winding, an auxiliary winding on said electromagnet, a vacuum tube amplifier having 7 its input terminals connected to said mags netizing winding and its output terminals connected to said auxiliary winding, and means for causing the reactive component of the alternating currents produced in said magnetizing winding by said flux variations to be substantially neutralized by magnetomotive forces Winding.

In witness whereof, I hereunto subscribe my name this 26th day of December, A. D. 1922.

produced by said auxiliary HENRY "c. 'IIARRISON.

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