US1944861A - Loud speaker cone - Google Patents

Description

Jan. 23, 1934. R. R. DU PUY 1,944,861

LOUD SPEAKER CONE Original Filed Nov. 22. 1929 19 IN V EN TOR.

i'to. 3

Patented Jan. 23, 1934 LOUD SPEAKER CONE Richard R. Du Puy, St. Paul, Minn, assignor to Wright, De Coster, Inc., St. Paul, Minn, a corporation of Minnesota Original application November 22, 1929, Serial No. 409,147. Divided and this application April 29, 1932. Serial No. 608,205

2 Claims.

My invention relates to improvements in radio loud speaker cones, of that type wherein a comparatively flexible cone, as of paper, is employed.

The present application is a division of my co-pending application, Serial Number 409,147,

filed November 22nd, 1929, for Speaker cone.

My invention has for its object particularly to provide means for constructing the cone with respect to vibration to prevent loosening and breaking of attached parts, etc.

This and other objects of my invention will be more specifically set forth in the following descriptio-n and the accompanying drawing, where- Figure 1 is a view in front elevation of the cone fitted with my improvement.

Figure 2 is a sectional view on line 2-2 of Figure 1; and

Figure 3 is a plan view of the vibratory center for the cone.

In the drawing, A represents a cone of the usual construction, preferably made of paper, and having the usual cylindrical throat portion 2. Surrounding the throat portion 2 is a voice coil 3. In carryingout my invention, the voice coil 3 is connected to a source of electrical supply, as a transformer, by the following means:

Secured in the cone adjacent to the throat, as shown in solid lines in Figure l, or adjacent to the outer edge of the cone, as shown in dotted lines in Figure 1, are two spaced apart eyelets 4 and 5. A conducting wire 6 leads from the transformer, not shown, to the eyelet 4, being secured in position underneath the eyelet 4, and a return wire '7 is similarly connected from the eyelet 5 to the voice circuit. Wires 8 and 9 lead from the eyelets 4 and 5 to the voice coil 3, the wires 8 and 9 being preferably glued down to the face of the cone. If desired, the wires 8 and 9 may be extended down to a point adjacent the lower edge of the cone, as indicated at 9a and 9b and secured to eyelets 4a. and 4b.

Across the throat 2 of the cone, I provide a flexible diaphragm 10, as of leather, the edges of the diaphragm 10 being secured as by gluing underneath the cone adjacent to its throat, as shown in Figure 2. The diaphragm 10 is formed with a central opening 11 to permit fastening of the member 10 to a portion of the loud speaker mechanism, not shown, in a well known manner, to centralize the cone with respect to other portions of the loud speaker.

An annular mounting ring 12 is constructed of sheet material such as stiff cardboard or metal, 55 the opening therein being slightly larger than the diameter of the lower end of the cone A. An annular strip 13 of fiexible material, preferably soft leather, is secured between the ring 12 and the cone A. The ring 12 is provided with openings 14 to permit fastening the cone to the loud speaker frame in a customary manner. This construction, combined with the flexible leather member 10, permits the cone to float more or less freely within the limits of movement of the flexible members 10 and 13 at the same time keeping the cone centralized with respect to its axis.

As it will be understood, the coil 3, when energized, acts in the usual manner to vibrate the cone and transform the pulsations of the voice circuit into sound waves.

The provision of the imperforate leather diaphragm 10 across the throat of the loud speaker, permits free and undisturbed vibration of the cone, and, at the same time, seals the throat of the cone against the admission of dust and moisture to the interior of the coil housing, not shown, which is located beyond the throat. This is a very material advantage for outdoor loud speakers, such as those used for public address and similar systems.

By using oiled leather for this member 10 and using a water proof material for the cone itself, the device is particularly unaffected by weather. Furthermore, since the voice coils usually operate within close limits between the core of the coil and the surrounding coil housing, the entrance of dust particles in the spaces between the voice coils and associated parts are apt to cause friction and binding, which destroys the proper functioning of the speaker.

While leather is specified as the throat material, it is possible that some equivalent substance might be produced which would operate as eifectively as leather, although at present leather is preferred to any other material, due to the fact that it withstands vibration better than any material found to date. The main feature lies in the fact, however, that the throat is imperforate.

I claim:

1. In a loud speaker cone of the character described, a truncated conical diaphragm, a cylindrical coil support mounted upon the truncated end of said cone to be substantially coaxial therewith and to extend outwardly therefrom, a voice coil supported by said cylindrical portion, and a skin diaphragm fixedly secured across said cylindrical element and imperforate except for a single central opening adapted to receive a fastening member for securing said skin diaphragm to a supporting element to permit limited vibratory movement of said cylindrical member and said cone with respect to said supporting element.

2. In a loud speaker cone of the character described, a conical diaphragm, a cylindrical coil support secured to the apex end of said cone to be co-axial therewith and to extend outwardly

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