US1767679A

US1767679A - Truncated horn speaker having plurality of chambers

Info

Publication number: US1767679A
Application number: US193811A
Authority: US
Inventors: Hutchison Miller Reese
Original assignee: ACOUSTIC PRODUCTS Co
Current assignee: ACOUSTIC PRODUCTS Co
Priority date: 1927-05-24
Filing date: 1927-05-24
Publication date: 1930-06-24
Anticipated expiration: 1947-06-24

Description

June \24, 1930. M. R. HUTCHISON TRUNCATED HORN SPEAKER HAVING PLURALI'IY OF CHAMBERS Filed May 24, 1927 v 3 Sheets-Sheet l INVENTOR. Mum

W 91. Aim

June 24, 1930. M. R. HUTCHIS ON 1,767,579

TRUNCATED HORN SPEAKER- HAVING PLURALITY OF CHAMBERS Filed May 24, 1927 3 Sheets-Sheet 2 I KAIEIZL fiZTOR 4 ATT RNEY.

Jime 24, 1930. M, R, HUTCHISON 1,767,679

TRUNCATED HORN SPEAKER HAVING PLUHALITY OF CHAMBERS Filed May 24, 1927 s Sheets-Sheet 5 MM W ATTORNEY.

A Patented June 24, 1930 UNITED {STATES PATENT! OFFICE MILLER REESE HUTCHISON, OF WEST ORANGE, NEW JERSEY, ASSIQNOB, BY HESNE ASSIGNMENTS, 1'0 ACOUSTIC PRODUCTS COMPANY, 01' NEW YORK, N.-Y., A COB- PORATION OI DELAWARE TRUNCATED 'KOBN SPEAKER HAVING PLURATJTY OF CKAMBBBB Application fled Kay),

This invention relates to sound propagatin devices of the type in which a mechanical diaphragm is utilized for imparting vibrations to a fluid medium.

A dia hragm of a sound reproducing device sucr as a telephone receiver or a socallcd loud speaker, acts as a piston for producing compressions and rarefactions of a column of air enclosed within the horn or within the receiver. The action of the diaphragm is opposed by the friction and inert1a of the diaphragm itself and by the pressure of the air column. The horn may correspond to an open end pipe which has the characteristic of bein resonant to an air wave having a length ouble that of the pipe. If the diaphra 'm vibrates at this resonant frequency of the horn, the vibrations thereof will be in phase with the vibrations which are set up in the air column, and, consequently, less resistance will be exerted upon the diaphragm than will be the case if the vibrations in that element and the air column were not in synchronism.

This invention provides a sound pro agating device having a new and efiicient iaphragm for imparting vibrations to an air column, and in which the friction of the air column is reduced to a minimum. The reflection of the pro agated waves back onto the diaphragm is argely prevented b the provision of an air space of constant y increasing cross section from the diaphragm to the open end of the receiver or horn.

The above desirable features are accomplishcd in the present invention by producing waves comprising rarefactions and compressions in a disk-shaped air 5 ace, the thickness of which increases from t 1e center toward the periphery. At the center where the movement of the diaphragm is greatest the highest pressure is exerted and as the wave which is produced travels outwardly in concentric circles the cross section of the air space constantly increases. At the outer periphery of the disk the waves ma be defiected at right angles and applie to an annular air column of constantl increasing cross section forming a horn. T e invention provides for the continuous progression of 1927; Serial in. 193,514.

the produced waves from thecenter of the diap ra m to the outward extremity of the horn an thereby lar 1y prevents the reflection against the diap ragm as well as eliminating all inert air space which would pro-' duce a damping effect upon the diaphragm. The outer annular air space may be divided into a plurality of columns of different lengths, each of the columns being resonant to a wave of different frequenc such as a note of the chromatic scale. ith such an arrangement the various notes of the chromatic scale may be reproduced.

The invention also consists in certain new and original features of construction and combinations of parts hereinafter set forth and eiaimed.

. Althou h the novel features which are believed to e characteristic of this invention will be specifically pointed out in the claims appende hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its or anizatron, ma be better understood by referring to the fo lowing description taken in connection with the accom anying drawing forming a part thereof, 1n which like reference characters have been used to denote like parts in the various figures. Since such illustration is, however, primarily for purposes of disclosure, it will be understood that the structure and the method of operation thereof may be modified in various respects without departing from the broad spirit and scope of the invention.

One embodiment of the invention has been shown for purposes of illustration in the accompanying drawing, in which Fig. 1 is a front elevation of a sound propagating device constructed in accordance with this invention;

Fig. 2 is a section taken on the line 2-2 of Fig. 1;

Fig. 3 is an end elevation of the device provided with resonating sections of different lengths;

Fig. 4 is a section taken on the line 4-4 of Fig. 3;

Fig. 5 is an elevation partly broken away showing the invention applied to a multihorn pancake type loud speaker; and

Fig. 6 is a section on the line 6-6 of and in particular to Figs. 1 and 2, a-

cup shaped diaphragm 1 is peripherally mounted on casing 3, and is actuated b an electromagnetic unit 2, which ma be 0 an desired type, such as for exam e, the wel known push-pull ty in whic a force is continuously applie to the armature durin movement in both directions. The movabTe armature may be rigidly connected to diaphragm 1, by connecting link 4 for the cur se of imparting vibrations thereto. iDiSlE S having a slightl cone sha ed cross section is located para lel to an slightly spaced from diaphragm 1 and provides in connection with said iaphragm, a disk-like air space of cross section increasing toward the periphery thereof, and of minimum cross section at the point at which the vibrations of diaphragm 1 are of greatest amplitude. Y

Diaphragm 1 may be extended to form a slightly tapered cylindrical member 7 terminating in a bell 10. The edges of disk 5 may also be extended to form a tapered c lindrical member 8 which is flared oppositely to member 7, and provides in connection therewith an annular air space of continuously increasing cross section. Cylinder 8 may be provided with a hell 9 similar in shape to hell 10 which is formed upon memher 7, said bells forming the opening of the annular air space through which waves are to be propagated. Supportin members 11 may be employed for rigidTy holding

members

7 and 8 in spaced relationshi 1 h considering the operation of Fig. 1, when the dia hragm 1 is forced toward disk 5, the air or other gaseous medium therebetween will be compressed, the greatest compression occurring at the center of the diaphragm, at which point link 4 is attached, and at which point the thickness of the disk of air between the diaphragm and disk 5 is the least. The compression thereby introduced into the air disk will be propagated outwardly in circles of progressively increasing diameter until the edge of the disk and the cup-shaped diaphragm is reached. At this point the concentric circles will be deflected in a direction substantially at right angles and will be propagated out through the horn shaped annular space between

cylinders

7 and 8. Said cylinders should be so shaped that the cross section of the annular air 5 ace will increase by an amount such that t a friction of said cylinders on the moving air column will be reduced to a minimum. Furthermore, the opening between bells 9 and 10 should be such that waves ma be transferred to the surrounding atmosp ere most efiiciently.

Referring to Figs. 3 and 4, the various elements described 1n connection with Fig. 1 are represented by similar reference numerals, and co uently will not be described in detail. In igs. 3 and 4, however,

members

7 and 8 have been shown as extended at a considerable angle to a line normal to the diaphragm, member 8 in effect being cone shafiled and terminating in an apex 14.

e annular space between said

members

7 and 8 has been divided longitudinally by fins '12 in the manner shown in Fig. 3 where- .by a plurality of se arate air columns are produced through w ich the air waves are independently propagated. The entire assembly has been shown as truncated, the end thereof terminating in a line 13. This arrangement allows each of the air columns to be of a different length whereby they may resonate at different frequencies. Obviouslfy, the line 13 may take any desired form or imparting the required characteristics ,to the various air columns. It has been shown as a straight line by way of illustration only. In order to accurately reproduce musical notes, the annular air space may be divided into 12 columns and the len h of each column may be such that it wi l resonate to a particular note of the chromatic scale. As shownin Fig. 3 24 columns may be employed and arranged so that two columns resonate to each of the notes of the scale.

In the operation of a device constructed as above, a sound wave, after being reflected from the cup shaped periphery of the diaphragm 1, will be impressed u on each of the various air columns into w ich the annular space between

members

7 and 8 have been divided. The wave will, however, impart the greatest vibrations to the air column which is resonant to the fre uency of the wave, and will be re-enforce by said air column and propagated into the surrounding space thereby. The vibrations of frequencies other than those present in the chromatic scale will not find a resonant air column and consequently will not be amplified. The invention, therefore, provides not only forthe selective amplification of the various musical notes but effectively suppresses notes of other frequencies, such as for example, those produced by static.

In the modification-shown in Fi 5 and 6, the invention is shown.as ap ied to a pancake type speaker-in which t e air column between

disks

20 and 21 is divided by a plurality of spirally extending members 22 into various spiral air columns of different 7 lengths and resonant to different frequencies. The diaphra m 1 and the disk 5 cooperating therewit together with the vanous actuating elements are similar to those disclosed in Fig. 1 and are given similar reference numerals.

In the operation of this device, the air waves after increasing in diameter until the periphery of diaphragm 1 is reached are refiected into thevarious spiral air columns through which they are impressed upon the surrounding medium. Each air column then selects and amplifies the wave to which it resonates.

By the present invention, a sound propagating device is produced in which the reflection in-the various air columns and the friction in. the diaphragm is materially reduced. The diaphragm is allowed to act as piston for producing rarefactions and compressions on the medium acted upon, such as air, but the force required to move the diaphra is reduced to a minimum by reason of t e continuously increasing cross section of the air column in which the vibrations are set up. Bv providing a plurality of air columns, eac resonatin at a frequency corresponding to a note in the chromatic scale, the accurate reproduction of musical notes is assured with a consequent elimination of undesired notes of lower frequencies, or of f uencies which are not multiples of one of t e notes of said scale.

A reproducing unit constructed in accordance herewith is capable of accurately reproducing all musical notes and of preserving the-tonal qualities thereof but serves to su press all notes of other frequencies. T e reproduction is es ecially efiiclent by reason of the reduced friction throughout the air column.

While certain novel features of the invention' have been shown and described and are pointed out in the annexed claims, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its olperation may be made by those skilled in t e art without departing from the spirit of the invention.

What is claimed is:

' 1. A sound pro agating device comprising a substantially at diaphragm and a cone shaped disk s aced therefrom to form a substantially dis shaped space having a eater cross section at the periphery thereof't an at the center.

' said diaphragm to form in connection therewith a disk like air space of increasing crosssection, said diaphragm and said member belar space of increasing cross section and a plurality of longitudinally extending memers for dividing said annular air space into a plurality of separate air columns, each of said air columns being of a suitable length to resonate to a note corresponding to a particular frequency in the chromatic scale.

3. A sound reproducing device comprising a diaphragm means for imparting vibrations thereto, a member co-operating with said dia hragm to form in connection therewith a disk like air space having a cross section increasing toward the periphery, said diaphragm and said member being extended and flared to produce an annular space of increasing cross section, and a. plurality of Ion itudinally extending members dividing said annular air space into a plurality of separate air columns, each of said air columns being resonant to notes of a definite frequency.

4. A sound reproducing device comprising a diaphragm, means for imparting vibrations thereto, a member co-operating with said diaphragm to form in connection there with a disk like air space of cross section in creasing toward the periphery( said diaphragm and said mem er being extended at substantially right angles and flared ,to produce an annular space of increasing cross section, and a plurality of longitudinally extending-members for dividing said annular air space into a plurality of separate air columns, each of said air columns being resonant to waves of a different frequency.

5. A sound reproducing device com rising a cup shaped diaphragm peripheral y supported, means for vibrating the center portion thereof, a member co-operating with said diaphragm to form in connection therewith a disk llke air space of cross section increasing toward the periphery, said dial vphragrn and said member being extended at substantially right angles and flared to produce an annular space of increasing cross section, a plurality of longitudinally extending members for dividing said annular air space into a lurality of separate air columns, each 0 said air columns being of a suitable len h to resonate to a note having a particular reg uencgto the chromatic scale.

Signed at ork, in the county of New York and State of New Yorkthis 20 day of May, A. D. 1927.

MILLER REESE HUTCHISON.

ing extended and flared to produce an annu-