US1696305A - Electromagnetic sounding-board actuator - Google Patents

Description

Dec. 25, 1928. 1,696,305-

M; R. HUTCHISON ELEQTROMAGNETIC SOUNDING BOARD ACTUATOR Filed April 1, 1927 INVENTOR QAZW ATTORNEY Patented Dec. 25, 1928.

l UNITED STATES PTENT QFFICE.

' MILLER iznnsn nuromsoiv, or wear ORANGE, NEW JERSEY, AssIenon, BY mssnn ASSIGNMENTS, TO ACOUSTIC rnonucrs COMPANY, or NEW YORK, N. Y., A. 003.-

PORATION OF DELAWARE.

ELECTROMAGNETIC SOUNDING-BOARD ACTUATOR.

Application filed s in 1, 1927.

This invention relates to new and useful improvements in electromagnetic sounding board actuators such as are used for transforming impulses of electric currents into i sound waves.

Its object is to provide a simple device of great efliciency and to provide a so-called 7 i so i other device which also embodies this insound propagators and which are supported vention.

In Fig. 1, 10 and 11 designate two members which are resonant sounding boards or in substantially parallel relation in a base 12.

v e A bridge, 13 spans the members 10 and 11 1 across the top and may be secured to them in any suitable manner. 14 is aflexible suspension support between the bridge 13 and the electromagnetic unit 15.

v The electromagnetic unit is shown somewhat in detail in Fig. 2. It comprises a body having a permanent magnet to which are rigidly ailixed pole shoes 21 and 22 between which is a coil 23. A vibratory armature 24 is flexibly supported, onthe permanent mag net by a spring 25 which holds it between the ma etic pole shoes. 26 is a push-pull .rod. which forms a rigid connection between the permanent ma net 20 and member 10.

. 27 is a push-pull rod which forms a rigid connection between armature 24 and member 11. The points at which the rods 26 and 27 are connected to the sound propagators are considerably above the center of their length. They are shown in'Fig. 1 as located about one sixth of. the length of the members 10 and 11, as I have found this to be an eifective position.

In operation, the balance of the parts is disturbed by a current which flows through the coil 23. WVhen such a current causes the which form SeriaI No. 180,183.

armature 24 to be attracted by pole shoe 21 and repelled by pole shoe 22, this will cause a movement of the member 10 to the left. The reaction to this force will effect a simultaneousmovement of the body of the electro' magnetic unit 15 and of the member 11 t0 the right. )bviously magnetic pulls in the opposite direction will move the members 10 and 11 in the other directions. Thus any vibrations imparted by the electromagnetic unit 15 to the sound propagators 10 and 11 will always be simultaneous and opposite The results attained by such an organization in the production of sound waves are highly effective and desirable.

The same general effect may be obtained with a loud speaker of the double con-e type, such as illustrated in Fig. 3. In this case the base 12 supports two cones, 10 and 11 the apexes of which are connected by rods 26 and 27 with the armature and body respectively of an electromagnetic unit 15 which is flexibly suspended by a support 14' from the upper peripheries of the cones.

The electro-responsive unit, therefore. comprises two vibratory members which move relatively but in opposite direct-ions. Because of the difl'crence in mass between the armature and the body, their movements are not equal. As a result the armature with its attached member 10, and the bod with its attached member .11, are unequally responsive to electric current variations of a given frequency. Furthermore, the armature and its attached member 10. are more responsive to current variations of certain frequencies than are the body and its attached member 11, and the body and member 11 are more responsive to current variations of an entirely different frequency. Consequently the organization as a whole serves to transform current variations over an extremely large difference of frequencies, into sound Waves of a correspondingly wide range.

Two embodiments of this invention have been illustrated and described to show that it is not limitedto any specific form or con struction and I intend no limitations other than those imposed by the appended claims.

What I claim is:

1. A pair of vibratory sound propagators in bpposed relation, an electromagnetic unit flexibly supported between said ropagators' comprising two relatively movable parts, a

connectionbetween one of the propagators and one of said parts, and another connection between the other of the propagators and the other of said parts.

2. A pair of vibratory sound propagators in 0 posed relation, an electromagnetic unit fles'i ly supported between said propagators comprising two relatively movable parts, a rigid connection between one of the propagators and one of said parts, and another rigid connection between the other of the propagators and the other of said parts, said connections bein in alinement.

3. A pair of vibratory sound propagators in o posed relation, an electromagnetic unit flexibly supported between said propagators comprlsing two relatively movable parts, a rigid connection between one of the propagators and one of said parts, and another rigid connection between the other of the propagators and the other of said parts, said connections being in alinement and offset from the center of said propagators.

4, A pair of sound propagators in o posed relation, an 1 electromagnetic unit exibly supported between said propagators comprising two relatively movable parts of unlike mass, a connection between one of the pro agators and one of said parts, and anot er connection between the other of the propagators and the other of said parts.

5. A pair of sound propagators in o posed relation, an electromagnetic unit flexib y supported between said ropagators comprising two relatively movab e parts of unlike mass, a rigid connection between one of the pro agators and one of said parts, and anot er rigid connection between the other of the propagators and the other of said parts, said connections being in alinement.

6. A pair of sound propagators in o )posed relation, an electromagnetic unit flexibiy supported between said propagators comprising two relatively movable parts of unlike mass, a rigid connection between one of the pro agators and one of said parts, and anot er rigid connection between the other of the propagators and the other of said parts, said connections being in alinement and offset from the center of said propagators.

In witness whereof, I have hereunto set my handthis th day of March, 1927.

MILLER REESE HUTCHISON.

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