US1678214A - Acoustic amplifier and radiator - Google Patents

Description

July/Z24, 192s.

2 Sheets-Sheet Filed Dec. 24, 1926,

July 24, 1928. 1,678,214

E. A. GRAHAM ACOUSTIC AMPLIFIER AND RADIATOR Filed Dec. 24, 1926 2 Sheets-Sheet 2 lkventor' rial No. 97,130, filed by E Patented July 24, 1928.

NIT'EID STA -s EDWARD (GRAHAM, DECEASED, LATE vBROCKJLZEY, EGND'ON; ENGLAETD, .BY

.MABIAGR'AHJAM, .EXECUTRIX, OF BECKE'NHA'M, I ENGLAND, AND ALFRED GRAHAM,

EXEGUTOR, OF .FO-REST HILL, .LONDON, ENGLAND, ASS IGNORS 0 GRAHAM AMPIJIOEN LIMITED, "OF LONDON, ENGLAND.

ACOUSTIC .AMPLIFIER AND nA-nrjiron.

Application.filednecember'24, 1926,.Seria1 No. 156,967, and rnGreat Britain February 20, 1926. U I

In the specification of an a i plication Secl -ward Alfred Graham, of whom we are executors, for Letters Patent, there "is described an invention having for its ob ject to provide an1mproved acoustic amplifier and radiator f v p v k v bodied, if so de's1 red, 1n a cab net 01' other.

a so

which shall be suitable for use with apparatus in which sound waves are produced or originated by the vibration of a diaphragm,

as in the case of an electro-magnetic telephonic receiver, or the sound box of agramophone, whichshallfbe compact in form, suit- .able .for embodying in a cabinet or casing,

and highly efiicientin use, quality of tone being maintained, together with maximum volume. i v

The invention as described in the said prior specification, 'is characterized in that the sound amplifying and radiating means adapted to co-actwith a sound directing conduit, comprises multiple concave reflecting surfaces one of which is of comparatively large curvature and blends into another which is of comparatively small curvature, the arrangement being such that sound waves projected on to such an amplifier will be radiated therefrom and diffused through the outlet orifice of such acoustic amplifier and radiator.

Now the present invention is an improvement in or modification of the invention claimed in the .said'ear'lier specification, the

improvement or modification consisting in this that although multiple reflecting surfaces are employed, they comprise a concave surface and one or more flat surfaces, the single flat surface, or one at least of such flatsurfaces when several are used, being inclined to the outlet orifice of the acoustic amplifier and radiator.

Thus, the acoustic amplifier and radiator comprises a reflecting element having .a concave reflecting surface and one or more flat secondary reflectingsurtaces such as referred to, and a sound wave developing conduit, the concave reflecting surface and sound conduit being so arranged :in relation to eachother and to the flat reflecting surface or surfaces that sound "impinging on the concave surface will be reflected therefrom and thence be radiated and diff-used through the out let orifice of the acoustic amplifier and radiatorby the flat reflecting surface or surfaces. 5

Such a combination ofrefiecting surfaces can be constructed in numerous ways, each amplifier iandradiator according to the pre sent invention. Fig. :2 shows the acoustic amplifier and radiator in front elevation, the upper portion of the cabinet being raised for the purpose. Fig. .3 is a horizontal section on the line III-{III of-Fig. 1. Figs. 4,5, 6;

and I? are horizontal sections-showing modified constructions. F1gsm8 and 9Lareperspect1ve views showing iturther modifications.

Fig. "10 shows in front elevation a still ,tu'rthermodification. F gs. 1,.2and 3 show one example of an acoustic amplifier and radiator according to the invention, particularly applicable :as. a

sound .amplifyingaud radiating chamber for a loud speaking telephone. It consists ot a v :trough orscoop-like :structure comprising a vertically arranged reflectin element 1 havinga concave reflecting .suriace (hereinfatter calle dflthe concave reflector) a vertically arranged flat reflecting surface 4- {hereinatter called the fiat reflector) constituted by a w a ll inclined to the axis vor theconcave reflector 2 and to the outletorificie, A of the structure, a vertical rear wall 5 connecting the rearends oi the concave and flat .reflectors l and at and arranged parallel to the outlet orifice of the, structure and. which may -.or may not act as a reflector, and top andbottom walls 6 and? which extendover, and

4: and rear wall 5. The refie ctorl which, in horizontalnsection is of parabolic shape, is adapted to coact with a soundwavedeveloping conduit 2 that is of gradually .in-

under .the concavelandnfiat reflectors l and.

creasingcross sectional area and carriescat:

its constricted end,,.a telephonic receiving unit 3. The sound conduit .2, which in this exampleis straight and arranged with its axis coaxial with the principal axis of the concave reflectorl, is carried by the flatq-j will be reflected as a beam from the parabolic I surface of the concave reflector 1 on to the adjacent surface of the flat reflector 4 from whence it will, to a large extent, be radiated outwardly through the outlet orifice A of the structure.

A structure such as described can, as shown, advantageously be housed within a rectangular casing or cabinet 8 in such manner that its open side is parallel with and presented to a perforated front wall 8 of the casing or cabinet, thus causing the flat reflector 4 to assume a substantially diagonal position across the casing or cabinet, thereby affording accommodation; for the telephonic receiver 3 between the flat reflector 4 and the wall of the cabinet, the top and bottom of the cabinet conveniently forming the upper and lower boundary walls 6 and 7 of the trough or scoop shaped structure. One end of the cabinet 8 is provided with a hinged door 9 to admit of ready access to the telephonic receiver 3 for adjustment thereof or for other purpose. Strips 6 and 7 of non-resonant material, such for instance as felt, may advantageously be arranged between the edges of the reflectors 1 and 4 and rear wall 5 and top and bottom walls 6 and 7.

Various modifications of this example can be evolved.

F orinstance, as shown in Fig. 4, the axis 6-00 of the concave reflector 1 may be inclined to the axi of the sound conduit 2 and to the flat rear wall 5 and also to the inclined flat reflector 4, so that the sound waves reflected from the said concave reflector will be directed wholly or partly on to the rear wall 5 which, acting in this case as a reflector, will cause them to be reflected through the outlet orifice of the structure, the fiat reflector 4 also acting to some extent to assist in the outward diffusion of the said waves.

Fig. 5 shows a similar arrangement to Fig. 4 but in which the inclined flat reflector 4 is arranged at a greater angle to the axis mw of the concave reflector 1 than in the arrangement shown in Fig. 4, (practically at right angles to the said axis,) so that the major portion of the sound waves reflected from the concave reflector 1 impinge upon the rear flat reflector 5 and are thence, to a largeextent, reflected on to the inclined flat reflector 4 whence they pass through the outlet orifice of the structure.

flector will impinge against the, flat reflector and be reflected therefrom as a diffused beam of sound waves through the outlet orifice of the structure.

When the principal focal axis of the concave reflector 1 is inclined to the axis of the sound conduit 2, as in Figs. 4, 5 and 6, the actual sound emission portion of the conduit may asshown in Fig. 7 at 2*, be displaced sideways to coincide with the said axis of the reflector.

The concave reflecting surface 2 instead of being of parabolic shape in horizontal sec tion, may be of other conic section.

Although the concave reflector 1 in each of the examples hereinbefore described has been assumed tobe straight in cross sect-ion in all planes parallel to one edge 1 thereof (Figs. 2 and 3), it need not always beso, and in some cases it may be a cone. ve surface corresponding to that swept through by a' curved line rotated about an axis of revolu tion. The curved line may be that of a parabola or any other suitable curve.

Fig. 8shows an arrangement of this kind in which the concave reflector 1 has a resides of acabinet to form the upper and lower boundary walls 6 and 7 of the scoop-like structure, as in the example shown in F igs. 1, 2 and 3, top and bottom walls 6* and 7* maybe combined with the concave and flat reflectors, to form an independent acoustic amplifier and radiator complete in itself, as shown for example in Figs. 8 and 9, and adapted, if desired, to be mounted within an independent cabinet with its outlet orifice A" arranged opposite the front of the cabinet which may be of a perforated or openwork character as shown in Figs. 1 and 2.

When a cabinet is used, a layer 10 (Fig. 3) of sheet material, for instance textile fabric like silk for example, may be arranged be tween the said outlet orifice A and the openwork front of the cabinet. lVhen the acoustic amplifier and radiator is enclosed within a cabinet, the space between it and the cabinet, except that containing the telephonic receiver 3, may be filled with non-sonorous material, asfor instance cotton wool, or other fibrous material, to reduce resonance.

In some cases the construction may be such that the smaller end portion of the conduit 2 extends through one of the horizontal walls 6 or 7 of the scoop-like structure, for example through the upper wall 6' and carries the telephonic receiver 3 outside such wall, as shown for example in Fig. 10.

What we claim is 1. An acoustic amplifier and radiator comprising a concavereflector, a sound conduit having its outlet end opposite said concave reflector and a flat reflector inclined to the axis of said concave reflector and to a sound outlet orifice between them and facing the reflecting surface of said concave reflector.

2. An acoustic amplifier andradiator comprising a concave reflector, a sound conduit having its outletend disposed opposite said concave reflector with its axis coincident with the axis of said concave reflector and a flat reflector inclined to the axes of the concave reflector and sound conduit and facing the reflecting surface of said concave reflector.

3. An acoustic amplifier and radiator com prising a concave reflector, a sound conduit having its outlet end opposite said concave reflector, a flat reflector, a sound outlet orifice arranged between said reflectors, said flat reflector being inclined to the axis of said concave reflector and to said sound outlet orifice and facing the reflecting surface of said concave reflector and a telephonic receiver connected to the inlet end of said conduit. 7 I

4. An acoustic amplifier and radiator comprising a concave reflector, a sound conduit having its outlet end opposite said concave reflector, a flat reflector, and a sound outlet orifice arranged between said reflectors, said flat reflector being inclined to the axis of said concave reflector and to said sound. outlet orifice and facing the reflecting surface of said concave reflector and said conduit extending through said flat reflector.

5. An acoustic amplifier and radiator com prising a concave reflector, a flatreflector inclined to the axis of said concave reflector and facing the reflecting surface of said concave reflector, walls formedwith said concave and flat reflectors, a scoop shapedstructure having a sound out-let orifice at one side, said flat reflector being inclined to the plane of said orifice, and a sound develop ing conduit extending through said structure and having'its outlet orifice disposed opposite said concave reflector.

6. An acoustic amplifier and radiator comprising a concave reflector, a flatreflector inclined to the axis of said concave reflector and facing the reflecting i face of said concave reflector, walls formed ith said concave and flatreflectors, a scoop shaped structure having a sound outlet orifice at one side, said flat reflector being inclined to the plane of said orifice, a sound developing conduit extending through the wall of said structure and having its outlet orifice disposed opposite said concave reflector, and a telephonic receiver connected to the inlet end of said conduit and located outside said structure.

7. An acoustic amplifier and radiator comprising a concave reflector, a flat reflector inclined to the axis of said concave reflector and facing the reflecting surface of said concave reflector, flat walls formed with said concave and flat reflectors, a scoop shaped structure having a rectangularly shaped sound outlet orifice at one side, said flat reflector being inclined to the plane of said orifice, and a sound developingconduit extending through said flat reflector, and having its outlet end disposed opposite said concave reflector.

8. An acoustic amplifier and radiator comprising a concave reflector, a flat reflector inclined to the axis of said concave reflector and facing the reflecting surface of said concave reflector, flat walls, formed with said concave and flat reflectors, a scoop shaped structure having a rectangularly shaped sound outlet orifice at one side, said flat re flector being inclined to the plane of said orifice, a sound developing conduit extending through said flat reflector and havingits outlet end disposed opposite said concave reflector and a telephonic receiver connected to the inlet end of said conduit and located behind said flat reflect-or. v

9. An acoustic amplifier and radiator comprising a concave reflector, a flat reflector inclined to the axis of said concave reflector and facingthe reflecting surface of said concave reflector, a rear wall connecting the rear ends of said concave and flat reflectors, the front ends of said reflectors being spaced apart to form a sound outlet orifice between them, and a sound conduit having its out let end disposed opposite said concave reflector.

10. An acoustic amplifier and radiator comprising a concave reflector, :a flat reflector inclined to the axis of said concave reflector and facing the reflecting surface of said concave reflector, a rear Wall connecting the rear ends of said concave and flat reflectors, the front end of said reflectors being spaced apart to form a sound outlet-orifice flector inclined to the axis of said concave reflector and facing the reflecting surface of said concave reflector, a rear wall connecting the rear ends of said concave and flat reflectors, the front ends of said reflectors being spaced apart to form a sound outlet orifice between them, walls forming with the said concave and flat reflectors and rear wall, a scoop shaped structure having a sound outlet orifice at one side thereof, a sound conduit extending through the wall of said structure and having its outlet end disposed opposite said concave reflector and a telephonic receiver connected to the inlet end of said conduit and located outside said structure. I

12. An acoustic amplifier and radiator comprising a concave reflector, a flat reflector inclined to the axis of said concave reflector and facing the reflecting surface of said concave reflector, and a straight sound conduit extending through said flat reflector and having its outlet end disposed opposite said concave reflector.

13. An acoustic amplifier and radiator comprising a concave reflector, a flat reflector inclined to the axis of said concave reflector and facing the reflecting surface of said concave reflector, said flat reflect-or having its front end spaced away from the front end of said concave reflector so as to form a sound outlet orifice between them, a rear wall connecting the rear ends of said concave and flat reflectors and a straight sound conduitextending through the flat reflector and having its outlet end disposed opposite said concave reflector.

14:, An acoustic amplifier and radiator comprising a concave reflector, a flat reflector inclined to the axis of said concave re flector and facing the reflecting surface of said concave reflector, said flat reflector ha ing its front end spaced away from the front end of said concave reflector so as to form a sound outlet orifice between then'i, and a straight sound conduit extending through the flat reflector and having its outlet end disposed opposite said concave reflector, the axes of said concave reflector and sound conduit being substantially coincident.

15. An acoustic amplifier and radiator comprising a concave reflector, a flat reflector inclined to the axis of said concave reflector and facing the reflecting surface of said concave reflector, said flat reflector having, its front end spaced. away from the front end of said concave reflector so as to form a sound outlet orifice between them, a rear wall connecting the rear ends of said con.- cave and flat reflectors and a straight sound conduit extending through the flat reflector and having its outlet end disposed opposite said concave reflect-or, the axes of said con-- cave reflector and conduit being substantially coincident.

16. An acoustic amplifier and radiator a sound outlet orifice between them, a rearv wall connecting said concave and flat reflectors, walls arranged to form with the concave and flat reflectors and rear wall a scooplike structure, and a straight sound conduit extending through said flat reflector and having its outlet disposed opposite said concave reflector.

17. An acoustic amplifier and radiator comprising a cabinet having a sound exit at its front side, a concave reflector and a flat reflector arranged within said cabinet between the top and bottom thereof with the flat reflector inclined to the axis of said concave reflector and to the front of said cabinet and facing the reflecting surface of said concave reflector, and a sound conduit extending through said flatreflector and having its outlet end disposed opposite said concave reflector.

18. An acoustic amplifier and radiator comprising a cabinet having a sound exit at its front side, a concave reflector and a flat reflector arranged within said cabinet between the top and bottom thereof with the flat reflector inclined to the axis of said concave reflector and to the front of said cabinet and facing the reflecting surface of said concave reflector, non-res0nant material between said reflectors and the top and bottom of said cabinet and a sound conduit extending through said flat reflector and having its outlet end disposed opposite said concave reflector.

19. An acoustic amplifier and radiator comprising a cabinet having a sound exit at its front side, a concave reflector a flat reflector and a rear wall connecting the rear ends of said reflectors, said reflectors and rear wall being arranged vertically within said cabinet and between the top and bottom thereof, and with the flat refleet-or inclined to the axis of said concave reflector and to the front of said cabinet and facing the reflecting surface of said concave reflector, and a sound conduit extending through said flat reflector and having its outlet end disposed opposite said concave reflector.

20. An acoustic amplifier and radiator comprising a cabinet having a sound exit at its front side, a concave reflector, a flat reflector and a rear wall connecting the rear ends of said reflectors, said reflectors and rear wall being arrangedvertically within said cabinet and. between the top and bottom thereof, and with the flat reflector inclined to the axis of said concave reflector and to the frontv of said cabinet and facing the reflecting surface of said concave reflector, non-resonant material between said reflectors and rear wall and the top and bottom of said. cabinet, and a sound conduit extending through the flat reflector and having its outlet end disposed opposite said concave reflector.

21. An acoustic amplifier and radiator comprising a cabinet having a sound exit at its front side, a concave reflector and a flat reflector arranged within said cabinet between the top and bottom thereof with the flat reflector inclined to the axis of said concave reflector and to the front of said cabinet and facing the reflecting surface of said concave reflector, and a straight sound conduit extending through the flat reflector and having its outlet end disposed opposite said concave reflector, the axes of the concave reflector and sound conduit being substantially coincident.

22. An acoustic amplifier and radiator comprising a cabinet having a sound exit at its front side and a door at one end, a concave reflector and a flat reflector arranged within said cabinet between the top and bottom thereof with the flat reflector inclined to the axis of said concave reflector and to the front of said cabinet and facing the reflecting surface of said concave reflector, a sound conduit extending through said flat reflector and having its outlet end disposed opposite said concave reflector and a telephonic receiver connected to the inlet end of said conduit and located within the spaces between the flat reflector and door.

23. An acoustic amplifier and radiator comprising a cabinet having a sound exit at its front side and a door at one end, a concave reflector, a flat reflector, and a rear wall connecting the rear ends of said con.- cave and flat reflectors, said reflectors and rear wall being arranged within said cabinet between the top and bottom thereof with the flat reflector inclined to the axis of said concave reflector and to the front of said cabinet and facing the reflecting surface of said concave reflector, a soundconduit extending through said flat reflector and having its outlet end disposed opposite said concave reflector and a telephonic re ceiver connected to the inlet end of said conduit and located Within the space between the flat reflector and door.

24. An acousticamplifler and radiator comprising a cabinet having a sound exit at the frontand a door at one end, a concave reflector, aflat reflector, and a rear wall connecting the rear ends of said reflectors, said reflectors and rear wall being arranged vertically within said cabinet between the top and bottom walls thereof with the flat reflector inclined to the axis of said concave reflector and to the front of said cabi net, a straight sound conduit extending through the flat reflector and having its outlet end disposed opposite said concave reflector, the axes of said'concave reflector and conduit being substantially coincident, and a telephonic receiver connected to the inlet end of said conduit and located between said flat reflector and door.

25. An acoustic amplifier and radiator comprising a cabinet having a sound exit at one side, a concave reflector and a flat reflector arranged Within said cabinet be tween opposite Walls thereof with the flat reflector inclined to the axis of the concave reflector and to the sound exit side of said cabinet and facing the reflecting surface of said concave reflector, and a sound conduit extending into the space between said reflectors and having its outlet opposite said concave reflector.

Signed at London, England,-this eighth day of December, 1926.

MARIA GRAHAM,

Ea -ecatm'm, ALFRED GRAHAM, Executor of Edward A. Graham, Deceased.

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