US1688744A - Multiple acoustic device - Google Patents

Description

Oct. 23, 1928. 1,688,744

A. MCL. NICOLSON MULTIPLE ACOUSTIC DEVICE Filed May 25, 1927 2 Sheets-Sheet 1 Fig. 1

INVENTOR ALEXANDER McLEAN NICOLSOM Oct. 23, 1928.

Filed May 25, 1927 2 Sheets-Sheet Fig. 2

INVENTOR ALEXANDER McLEAN NICOLSON BY V i Q.

A TORNEY Patented Oct. 23', 1928.

UNITED STATES- PATENT OFFICE.

ALEXANDER MCLEAN NIGOLSON, OF NEW YORK, N. Y., ASSIGNOR 'IO wrnnn RADIO,

INC., 01 NEW YORK, N. Y.., A CORPORATION OF DELAWARE.

mourn-LE acousric nnwcn.

Application Med May 25,

This invention relates to an acoustic device, and more particularly to such a device arranged to convert electrical oscillations into acoustic vibrations corresponding thereto: and particularly adapted or the reproduction of speech, music, and the like, from electrical oscillations corresponding to the sounds to be reproduced.

It is an object of this invention to provide such a device employing the principles of acoustic resonance, so arranged as to cover the range of sounds to be reproduced in a uniform manner.

It is a further object of this invention to provide an improved mechanical arrangement of such devices whereby a plurality of resonance chambers or acoustic amplifiers are established, having adjacent walls in com-h mon, and operated by a single energizing means, resulting in a compact and economical construction. 1

Still other objects of my invention will be apparent from the specification.

The features of novelty which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its fundamental principles and as to its practical application will best be understood by reference to the specification and accompanylng drawing, in which;

Fi 1 is an elevation partlyin section of one Eorm of apparatus according to my invention.

Fig. 2 is a similar view of another form thereof.

In accordance with my invention, I provide a plurality of acoustic amplifiers, such for example as horns, havingtheir characteristics so chosen as to be resonant or partially resonant to different acoustic frequencies. I preferably arrange these acoustic devices in a predetermined manner about a common center and in such a manner that one or more walls of the acoustic amplifiers serve as boundaries between two resonance chambers: for example, I may provide a plurality of horns of any suitable material such as wood, metal, fibre, or the like, and so chosen as to be arranged about a common center, preferably although not necessarily one within the other, whereby one or more resonance chambers or acoustic amplifiers are defined by the space enclosed between adjacent walls.

,I also provide one or more devices for conform desired,

1927. Serial No. 194,044.

vertlng electrical oscillations into mechanical vlbratlons for energizing the acoustic amplifiers. may utilize a single such device for energizing all of the acoustic amplifiers, or a plurality of such devices, or if desired, a s1ngle devlce for each acoustic amplifier. The electroresponsive device may take any such for example as a diaphragm actuated by electromagnetic or electro-statlc means, as is known in the art, or one or more p ezo-electric crystal devices of the type described in my copending applicatrons entitled: Cast piezo-electric device, SerialNo. 155,897, filed December 20, 1926 Composite p1ezo-electr1c crystal device, Serial No. 155,898, filedDecember 20, 1926; Composite piezo-electric torsion device, Serial No. 155,899, filed, March 11, 1927; Internally clamped composite piezo-electric torsion device, Serial No. 155,900, filed December 20,

1n composite piezo-electric devices, Serial No. 155,902, filed Dec. 20, 1926.

Referring now more particularly to Fig. 1, 1 designates a horn of any suitable material such as wood, metal, fibre or the like, and 2 a second horn of different dimensions. The operatlng mechanism in this instance is shown as a suitable piezo-electriccrystal devlce 3, for example acrystal of Rochelle salt exhibiting the-well known hour glass configuration and suitably secured as b cementing, by means of Rochelle salt melt comprising Rochelle salt from which the desired quantity of water has been'removed by heatlng 1t at a temperature above its melting point, to a plate or diaphragm 4 on the one end and similarly secured to a second plate or diaphragm 5 on'the other end. Suitable bolts 6 and 7 engaged by nuts 8 and 9 may be provided for the purpose of applying a suitable compressive stress to the crystal devices.

In order to secure the actuating mechanism in the proper position in the horn 2, I may provide an annular ring 10 provided with an opening 12 therein and having a cylindrical extension 11 thereon within which the horn 2 is adapted to be seated, and suitable bolts 13 and 14 engaged by nuts 15 and 16 are provided for the purpose of securing the diaphragm 5 and the annulus 10 originally inposition at the periphery of the plate 5. Similarly, bolts 18 and 19 are provided for the purpose of securing the plate 4 in the horn 1,- but in this instance, instead of providing an annulus, I may provide a plate 17 against which the horn 1 may abut. Bolts 18 and 19 are engaged by nuts 20 and 21 for the purpose of securing plates 4 and 17 in proper spaced relation.

Any suitable arrangement of electrodes maybe provided for energizing the piezoelectric device 3, as described in the applications above referred to: for example, there may be provided a conducting equatorial belt electrode 22 of metal foil to which is connected a lead 23. The other electrodes may consist of the plates 4 and 5, which may be connected electrically through the medium of bolts 6 and 7, and a second lead 24 is connected thereto.

The impression of an electromotive force across the leads 23 and 24, as is known in the art, causes generation of mechanical stresses in the piezo-electric device 3, which stresses are communicated to the diaphragms 4 and 5, and thereby energize horns 1 and 2. It will be noted that a portion at least of the horn 2 serves as a common wall for the acoustic chamber contained within the horn 2 and within horn 1.

By proper choice of the shape and dimensions and mass of the horns 1 and 2 and their relative spacing from each other and of the diaphragms or plates 4 and 5, it will be understood that any desired resonance effect may be produced, ranging from sharp resonance of the two acoustic chambers to a partial or broad resonance: and by proper choice of the constants of the apparatus with regard to the range to be covered, it is possible to'obtain the desired response. 7

In case it is desired to cover a relatively large range of frequencies, such for example as the entire acoustic range, for the purpose of reproducing speech, music and the like with a high degree of fidelity, it will be desired to increase the number of acoustic resonators or amplifiers, and to dispose them over the range of frequencies to be covered: for example, one may respond best to 256 cycles another at 512, another at 1024, and so on, it being understood that the figures given are by way of example and not limitation.

Referring now more particularly to Fig. 2, I have shown an arrangement utilizing five suitable horns 30, 31, 32, 33 and 34, forming as will be seen five acoustic amplifiers or resonance chambers having difierent frequency characteristics. A plurality of actuating devices, in this instance one less than the number of acoustic amplifiers, namely four, are provided in the form of piezoelectric crystal devices 35, 36, 37 and 38.

The crystal device is secured at one basal plane to a late or diaphragm 39 and its other end to p ate or diaphragm 42. The inner end of the horn 30 is closed 1) a backing plate 40 havin an annular ange 41 formed thereon an adapted to receive the plate or diaphragm 47. 'It will be understood that either a common base plate or diaphragm may be used between two adjacent crystals or separate base plates may be used as desired. 4

A pluralityof tie rods 48, 49 and 50 extend from plate 47 to backing plate 40 and are provided with nuts by means of which the desired compression may'be applied to all of the crystal devices. For the purpose of providing a rigid mechanical structure, the iorn 31 is provided at its throat end with an annular ring 58 provided with a cylindrical flange 59 defining a socket within which'the throat of the horn 31 is mounted. Similarly, the horns 32, 33, and 34 are provided vith annular rin s 56, 54, and 52,. provided with cylindrica flanges 57, and 53 defining sockets within which the respective horns are engaged. Suitable bolts 60 and 61 are provided passing through holes in the annular rings 52, 54, 56 and 58, and through backing plate 40. The bolt 60 is provided with suitable nuts 63, 65, 67 and 69, and bolt 61 is provided with nuts 64, 66, 68 and 70, by means of which the respective annular rings may be maintained rigidly in contact with the base of the respective horns a ainst the compression applied by the tie roris 48, 49 and 50. It will thus be seen that a rigid compact mechanical structure is provided, comprising a number of acoustic amplifiers of different naturalfrequencies. For the purpose of energizing the crystal devices 35, 36 and 37 and 38, each of these devices ma be provided with equatorial conducting elt electrodes 72, 73, 74 and 75, which may be connected together and to one terminal of the source of electrical oscillations. The vari: ous plates or diaphragms 39, 42, 43, 44, 45, 46 and 47, may constitute the other electrode of the crystal devices, and may be connected together and to the other terminal of the source. It will be understood, however, that instead of connecting all of the crystals for operation by a single source, tuning devices may be interposed in each crystal circuit, as described in my copending application entitled, Sound reproducin system, Serial No. 180,420, filed April 2, 192

Operation of this arrangement is substantially similar to that of the arran ement shown in Figure 1, it being understoo however, that by the provision of a greater number of acoustic amplifiers of different natural frequencies, it is possible to obtain a more uniform reproduction over a wider band of tig iquencies than will otherwise be obtaina e.

While I have shown and described certain preferred embodiments of my invention, it will be understood that modifications and changes may be made Without departing from the spirit and scope of my invention, as Will be understood by those skilled in the art.

1. An acoustic device comprising a plurality of acoustic amplifiers and a single piezoelectric means for converting electrical oscillations into acoustic vibrations arranged to energize said amplifiers.

2. An acoustic device comprising a plurality of acoustic amplifiers disposed about a common center, and a single piezo-electric means for converting electrical oscillations into acoustic vibrations arranged to energize said amplifiers.

3. An acoustic device comprising a plurality of acoustic amplifiers having a common Wall, and a single piezo-electric means for converting electrical oscillations into acoustic vibrations arranged to energize said amplifiers.

4. An acoustic device comprising a plurality of acoustic amplifiers disposed about a common center and having one Wall in common and piezo-electric means for converting electrical oscillations into acoustic vibrations arranged to energize said amplifiers.

5. An acoustic device comprising a plurality of acoustic amplifiers having difierent natural frequencies, and a single piezo-electric means for convertingelectric-al oscillations into acoustic vibrations arranged to energize said amplifiers.

6. An acoustic device comprising a plural ity of acoustic amplifiers having difierent natural frequencies and disposed about a common center, and a single piezo-electric means for converting electrical oscillations into acoustic vibrations arranged to energize said amplifiers. v

7. An acoustic device comprising a plurality of acoustic amplifiers having difierent natural frequencies and having a Wall in common, and a single piezo-electric means for converting electrical oscillations into acoustic vibrations arranged to energize said amplifiers.

8. An acoustic device comprising a plurality of acoustic amplifiers having difierent natural frequencies and having one Wall in common, and disposed about a common center, and piezo-electric means for converting electrical oscillations into acoustic vibrations arranged to energize said amplifiers.

9. An acoustic device comprising a plurality of acoustic amplifiers having different natural frequencies and having one Wallin common and disposed about. a common center, and a single piezo-electric means for converting electrical oscillations into acoustic Eibrations arranged to energize said ampliers.

10. An acoustic device comprising a plurality of acoustic amplifiers having different natural frequencies and having one Wall in common, and disposed about a common center, and avpiezo-electric crystal device for converting electrical oscillations into acoustic vibrations arranged-to energize said amplifiers.

Signed at NeW'York in the county of New York and State of New York this 23d day of May, A. D. 1927.

ALEXANDER MoLEAN NICOLSON.

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