US1784595A - Acoustic device - Google Patents

Description

1930. M. R. HUTCHISON 1,784,595

.ACOUSTIC DEVICE Filed Feb. 18. 1927 2 Sheets-Sheet 2 44 I 44 INVENTOR A TTORNEY Patented Dec. 9, 1930 UNITED STATES'PA-TENT DFFICE I MILLER REESE nuronrson, F LLEWELLYN PARK, WES'I' oRANennEw JERSEY, As-

srenon, BY erasure AssrenMENrs, r0 ACOUSTIC PRODUCTS corrrany, 0E NEW YORK, N. v n cenronarron or DELAWARE g ACOUSTIC nEvIcE Application filed February 18, 1927. Serial no. 169,185,

This invention relates to acoustic devices for producing compressional waves of complex wave form.

The invention has for its principal object the faithful reproduction of speech and music from any surface.

In reproducing speech and music faithfully, it is, of course, essential that there shall be produced not only the fundamental tones corresponding inpitch to that of the voice or musical note being "sounded, but also all of the useful upper harmonics whereby the timber and quality of the sound are recognized by the listener, and whereby a full appreciation may be obtained; and it isalso important that all of the fundamentals and overtones shall be reproduced in the same proportions which were foundin the original.

Heretofore, the faithful reproduction of all the harmonics of speech and music has been attempted by a variety of expedients, in cludmg sheets of paper or parchment, as m the so-called cone type of loud speaker, the horn type, in which a column of air is caused to resonate, and others.

Such expedients have,'however, not proven entirely successful or wholly feasible. .For example, the cone speaker when made in sizes convenient for ordinary use, as in the home, has not responded to a sufficiently wide range of vibration frequencies; and when made so to respond has been too large for convenience. Furthermore, the horn type of loud speaker, when made in ordinary sizes, produces the so-called barrel efiect, at once distracting and disagreeable.

Furthermore, prior types of loudspeakers do not operate satisfactorily in all rooms, the

acoustics depending upon size, shape and furnishings. It is well known, for example,

that the same type of such prior instrument gives different results in different locations. My invention has for one'of its ob ects,

therefor, the use of'someobject to be found in i any room in which reproduction of speech or music is to be efiected, and thus by the selection of an object havinga relatively large surface, the room can be filled with sound.

The selection of the object can readily be made so that a sufficiently large resonating sur- -Figures 1 and 2;

face isprovided to accommodate the room with sound, and effectively to obviate repress on or accentuation of'any band of frequencies. V

By thus employing anobject already forming a part of the room, the acoustics of the room are unchanged, and-since any suitable object, conforming in its resonating characteristics to what the listeners deem desirable, can be selected, the most suitable effect can thus be readily obtained. I The invention relates to an improved method of and means for impressingu'ndulatoryenergy to an object.

According to this feature extremely large vibrating surfaces may readily be employed for the reproduction of sound, without requiring the special use of a large cumbersome vibratory element.

According to another feature of the inven tion the device may be attachedin such manner as to bear against the surface to be vibrated with considerable pressure, so asreffectively to prevent the vibrating element of the device from .leavingthe surface, even during the extremes of its vibration. 1

Another feature relates to stressing the ma terial of the object to be vibrated, thereby assisting considerably in the faithful reproduction of sound.

Other objects will'appear from the followingdescription and claims taken in connection with the accompanying drawings in which Figure 1 is a side elevation of one form of device embodying features of the invention; Figure 2 is a plan view of the device of Figure 1;

' Figure 3 is an endxview from the left of Figure 4 is a detail view partly in section of a portion of Figure 3 with the actuating element in displaced position; and

Figure 5 is a modified form of the structure shown in Figure 1.

Like reference characters refer to like parts in the several-figures of the drawings.

In the following description and claims,

parts, characteristic features and functions will beidentified by specific names for convenience of expression, but they are intended to be as generic in their application to similar parts or equivalent construction as the art will permit.

Referring to the form of the invention illustrated in Figures 1 and 2, there is provided a relatively massive element 10 which may preferably take the form of a horse shoe magnet having one pole designated N and opposed pole designated S. The magnet 10 is sufficiently large so that it has a large moment of inertia, at least with respect to the periodicity of the waves which are to be received, so that it remains inert with respect thereto. There is mounted on the continuous faces of the poles of the magnet 10 a pairof soft iron plates 11, 12 respectively, each'of which is in magnetic contact with its respective magnet pole, being held in position by suitable screws such as 13. Positioned on the plate 11 of one .pole N is a pair-of cores, preferably laminated, shown as at 14, 15, and held in place by clamps 16, 16. .Mounted on the core 14 is an electro-magnet 17, and similarly mounted on the'core 15 is an electro-magnet 18, the magnets 17, 18 being connected in series by a conductor 19. The magnets 17, 18 are understood to be connected by means of binding posts 50, in circuit with a source of undulatory energy of-complex wave form, such as a radio receiving set, an amplifier, a public address system, a phonographic pick-up systemga telephone line or other desired device,

but as such devices form no part ofthe present invention it is thought that a description thereof need not beincludecl herein; A return yoke 20, preferably formed of laminated para-magnetic materialis provided for connecting the outer ends of the cores 14,15,

thus forming a magnet circuit of efiicient type. The contiguous ends of'cores 14, 15 are spaced apart sufficiently so that the free end a of a movable armature or vibrating element 21 may loosely extend there-between.

For supporting the armature 21 there is mounted on the plate 12 of the other pole S a block 30 formed of para-magnetic material and having at its outer end a pair of spaced lugs or ears 31, 32, between which there extends a flat spring plate 33 formed of slightly yielding material. The armature 21 is secured to an intermediate portion of the spring plate 33, which thus forms effectively a pivotal mounting for the armature which thus may be controlled in its movement by the energization of the electromagnets 17 18. The plates 11, 12 are interconnected at their ends by magnetically inert braces 34, for maintaining the parts in relatively fixed relation. The arrangement is such that the armature 21 is operated upon by the magnets 17, 18 in push-pull fashion, i. e., when one of the magnets is energized to attract the free end of the armature, the other magnet repels it and vice versa. The tension of the spring plate 33 is sufficiently great to exert a considerable torque on the armature 21 in a counter clockwise direction as seen in Figure 3.

For supporting the electroresponsive device which has just been described, there is provided in the embodiment shown in Figure 1 a curved bracket 40 formed of a yielding material which is magnetically inert. The element 40 is connected at one end as by machine screws 41 to a block 42 formed of magnetically inert material. The block 42 is secured to the permanent magnet 10 as by screws such as 43 extending therethrough. The other 'end of the supporting means 40 is provided with spaced pads 44 and may be additionally fastened by means of a conventional wood screw 45 to an object 46 which is to be vibrated and which forms the vibratory element. The pads are preferably formed of a soft material such as soft rubber, to form suction pads,to protect the surface of the object 46. A projecting arm operatively interconnecting the armature 21 to the object 46 comprises a substantially rigid rod47, one end the end of the connecting rod 57 contacts at 49 with the surface of .the object 46, and the armature 21 isthus forced, against the'tension of the spring 33, into the position between the pole pieces, as illustrated in Fig.3.

The tension of the spring plate 33' is sufli ciently great to maintain the end 49 of the rod 47 in intimate "contact with the object 46 at all times, even when energy of maximum intensity is impressedupon the device.

In the modified form of the invention shown in Figure 5, the spring bracket 40 is made sufficiently extensive to bring the points of support in proximity to an edge 50 of the object 46 so as to promote relatively free vibration of the middle portion of the object;

It will thus be seen that the device may be applied to any object to be vibrated, without undue harm thereto. For example, the device may be readily attached to the sounding board of a piano and when thus employed? produces excellent results. I have also found that almost any object such as a pane of glass, a table, a door, the floor, etc serves as an excellent vibratory element, when the device is used as has been herein described.

What is claimed is: i 1. A device for vibrating an object inclu ding,-in combination, a vibrating element and electrical means for vibrating the same in response to electrical waves of sound frequency, said vibrating element being adapted to vibrate about a mean position, an arm attached to said vibrating element, resilient means for holding said vibrating element displaced from its mean position to cause the projection of said arm, a support for all of said devices adapted to rest upon the surface to be vibrated, said projecting arm being adapted to project beyond said surface by an amount equal to the displacement of said vibrating element from its mean position.

2. A device for vibrating an object, including, in combination, a permanent magnet, a vibrating element connected to one of the poles thereof, a pair of pole pieces connected to the other pole thereof, and electrical means for magnetizing them in opposition to each other, said vibrating element being adapted to vibrate between said poles, an arm connected to said vibrating element, means for supporting all of said parts from the surface to be vibrated, resilient means for displacing the vibrating element from its mean position between said pole pieces in a direction to project said arm below the surface of support by an amount equal to said displacement.

3. A device of the character described including, in combination, a permanent magnet, a vibrating element connected to one of the poles thereof, a pair of pole pieces connected to the other pole thereof, and electrical means for magnetizing them in opposition to each other, said vibrating element being adapted to vibrate between said poles, an arm connected to said vibrating element, means for supporting all of said parts from a surface, resilient means for displacing the vibrating element from its mean position between said pole pieces in a direction to project said arm below the surface of support by an amount equal to said displacement, said supporting means including suction cups adapted to attach said element without marring the surface.

Signed at New York, in the county of New York and State of New York, this 17th day of February, A. D. 1927.

MILLER REESE HUTCHISON.

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