US1276287A

US1276287A - Sound-directing appliance.

Info

Publication number: US1276287A
Application number: US2758015A
Authority: US
Inventors: Eric Magnus Campbell Tigerstedt
Original assignee: Individual
Current assignee: Individual
Priority date: 1915-05-12
Filing date: 1915-05-12
Publication date: 1918-08-20
Anticipated expiration: 1935-08-20

Description

E. M. C. TIGERSTEDT; SOUND DIRECTING APPLIANCE. APPLICATION FILED MAYI'Z, 1915.

Patented Aug. 20, 19181 said nineties oaMrBEILL rxenns'runr, or oornnnnonn, ENMARK.

. soUnD-nnanofrme nrrmanoii.

To all whom it may! concern: I Be it known that I, Emo- MAGNUS CAMP- BELL TIeERsrED'r, a subject of the Emperor of Russia, residing at Copenhagen, "Denmark, have invented certain new and useful Improvements in Sound-Directing Appli-.

ances 'pf. which the following is a specification. i

This invention relates to diaphragms and particularly to such as are used for ,gramophones, phonographs, talklng or recording machines,-receivers or transmitters of telephone's, or other similar devices in whichdiaphragms are employed for receiving, recording or produclng sound waves,

In" devices of the type referred to it was common'practice to provide, opposite the diaphragm, a guide for the sound waves, as, for instance, a mouth-piece or thelike,-having'aoentra-lopening for the passage of the sound waves. Since-the central opening in theguide' was usually comparatively small the massof the diaphragm caused to vibrate by thesound waves was also comparatively small. Thus, with devices, as heretofore constructed, much difliculty' has been exper encedjin transmitting'sound waves to somewhat far distances, and .no "mechanism has,

to myknowledge, heretoforebeen' devised embodying any practicable means for enablingija clean transmission of sound waves to'fa'r distances so that they will be clearly comprehended at distant places.

The object of the present lnvention is to obviate the aforesaid difi'iculties and to correct a vital imperfection. .To this end-'1 provide means whereby the sound waves will be conveyed from the rim of the diaphragm to its center and vice versa, thereby enabling.

the diaphragm topbe acted upon by or to produce a greater quantity of sound waves.

In the drawings several constructional forms of the arrangement according to the invention are shown.

tion, of a diaphragm for producing sound waves by means of a record plate.

Fig. 2 is a similarv sectional view showing a receiver provided with the invention.

Figs.';3 and 4 are similar-sectional views showing ,two other embodimentsof the invention;

' Referring to Fig. 1, dis a diaphragm from the rim fjof which extends a diverging funnel or trumpet a. In the funnel or trumpet a a-certain distance apart from and opposite Specification of Letters "Patent Figure 1 is a side elevation, partly in sec-v v Patented Aug. so, rare.

' Application filed'May 12,11915. Serial No. 27,580.

the diaphragm d is fixed by means of bands or straps 0 a wall, preferably of special shap'eas will be afterward explained-or a cone 7), The wall or the base of the cone 2) is so arranged in the trumpet'a as to leave an annular gap for the passage of the sound waves between its circumference. and the smaller end of the trumpet a.

In the constructional form, as shown in F g.1, the diaphragm d is vibrated or operated upon by means. of a bell-crank levere I pivoted at f and provided with a stylus which is actuated by the records on the record plate hi and cone 3) is similar tothat in-Fig. 1. In the base of the hollow cone 6 a magnet g is provided the coils of which are wound in anopposite direction to the windings of a mag net .11 arranged below the diaphragm d. The windings of the two magnets are connected in series in a telephonev exchange, not shown.

Normally the forces of the two magnets neutralize each other, and, therefore, the diaphragm will remain perfectly plane. in operation the magnetic force of the one electro-magnet will be increased, and that of the other decreased. This arrangement results in perferctly equal over-vibrations of'the diaphragm whichare independent of the position of the'latter; The amplitude of the diaphragm also becomes larger and more vigorous. 4

The efliciency may generally be still further increased by providing the base of the-cone lgj-in the form of another diaphragm, as shown in Figs. 3 and 4.

Fig. 3 illustrates the invention as applied to a transmitter. {The diaphragm d is provided at the smaller end of a mouth-piece a" and cooperates with a carbon grain microphone la. -This carbon grain microphone k is connected .in series carbon grain microphone Z provided in the with another hollow-cone b the-base of which forms a sec- 0nd diaphragm n opposite the first dia- "phragm 03. The sound waves entering the mouth-piece a. pass through the annular gap 0 and 'move in a radial direction to the center ofthe diaphragms d and n. At the center. they will hit upon each other and cause an energetic vibration of the dia-' phragms. v The receiver according to Fig. 4 differs In Fig. 2 the invention is shown in connection with a receiver. The general ar- 9 rangement of the diaphragm d, trumpet w from the construction shown in Fig. 2 in that the base 01 the cone 5 provides a second diaphragm p opposite the diaphragm (Z. and that the electro-magnet 9 does not project through the. base'ot but is inclosed in the cone Z2.

1. In a sound directing appliance, the combination of a diaphragm, a funnel, the opening of which is in direct opposition to the diaphragm, and means including a portion provided with a plane surface closely overlying the diaphragm for conveying the sound waves from the rim of said diaphragm to the central portion of the same, and vice versa.

2. In a sound directing appliance, the

' combination of a diaphragm, a funnel, a

conesshaped element within said funnel, the base wallof said cone being in direct and close opposition to the diaphragm, the base portion of the cone being located centrally within the narrower opening of the funnel,

whereby an annular gap is formed-between the rim of said opening and the base of the cone, for directing the sound waves from said annular gap near the circumference of the diaphragm toward the central portion v of the same, and vice versa.

3. In a sound directing appliance, the combination of a diaphragm, a funnel, a closed cone-shaped element within said tunnel, the closing base of said cone being in direct and close opposition to the diaphragm, the base portion of the cone being located centrally within the narrower opening of the funnel, whereby an annular gap is formed between the rim of said opening and the base of the cone, for directing the sound Waves from said annular gap near the circumference'of the diaphragm toward the central'portion of the same, and vice versa;

and means for'imparting vibrations to said diaphragm.

4:- In a sound directing appliance, the

ga arass? combination of a diaphragm, a funnel, a cone within said funnel, a second diaphragm forming the base wall of said cone and in direct opposition to the first named diaphragm, whereby an annular gap is formed between the narrower end of the funnel andthe base wall of the cone, for directing the sound waves from said annular gap at the circumference of the first named diaphragm toward the central portion of the same, and vice versa,

5. In a .sound directing appliance, the combination of a diaphragm, a funneL-a cone in said funnel, a second diaphragm forming the base portion of said cone and in direct opposition to the first named diaphragm, whereby an annular gap is formed between the narrower end of the funnel and the base portion of the cone, for directing the sound waves from said annular gap'at the circui'nterence of saidfirst named dia phragm toward the central portion of the same, and vice versa, and electromagnets cooperating with both of said diaphragms.

6. In a sound directing appliance, the combination of a diaphragm, a funnel, a cone in said funnel, a second diaphragm forming the base portion of the cone and in direct opposition to said first named diaphragm, whereby an annulargap is formed between the narrower end of the funnel and the base portion of the cone, for directing the sound waves from said annular gap near the circumference of the first named diaphragm toward. the central portion of the same, and vice versa, and tele phone magnets for imparting vibratory mo tion to both of said diaphragms.

In testimony whereof I afliX my signature in presence of two witnesses.

ERIC MAGNUS CAMPBELL TIGERSTEDT.

lVitnesses: Vreoo BLOEoJ A. IV. AHLSTADT.