US1853850A - Sound reproducing device - Google Patents

Description

Patented Apr. 12, 1932 UNITED STATES PATENT OFFICE LEE DE FOREST, OF NEW YORK, N. Y., ASSIGNOB TO GENERAL TALKING PICTURES COR- PORATION, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE SOUND REPRODUCING DEVICE Application filed December 24, 1928.

This invention relates in general to sound reproducing devices particularly adapted for use in large auditoriums and the like in connection with radio reception talking moi tion pictures and the like.

One of the objects of this invention is the provision of a new form of sound reproducing .device of large size constructed to render it mobile.

A further object of this invention is the provision of a sound reproducing device of this type pivotally mounted on a carriage so that it may be readily moved about and rotated on its pivots when desired.

A further object of this invention is the provision of a sound reproducing device in which a cone type of loud speaker is associated with an exponential horn, so as to load the cone speaker with a large air column.

A still further object of this invention is the provision of a structure of the above type in combination with a plurality ofsound reproducing devices adapted to reproduce the higher notes encountered in the reproduction of sounds.

A more general object of the invention is the provision of a sound reproducing device particularly adapted to reproduce faithfully all the frequencies encountered in the reproduction of speech, music and the like.

A further object of the invention is the provision of a structure of this type which is relatively simple to make and rugged and eflicient in operation.

These and other objects as will appear from the following disclosure are secured by means of this invention.

This invention resides substantially in the combination, construction arrangement and relative location of parts, as will be disclosed hereinafter.

Referring to the drawings,- Figure 1 is a front elevational view of the device;

Figure 2 is a side elevational view; Figure 8 is a rear elevational View; Figure 4 is a horizontal cross-sectional view taken on the line 4-4 of Figure 1 Figure 5 is a vertical cross-sectional view taken on the line 5-5 of Figure 4:.

Serial No. 328,141.

In the use of sound reproducing devices in auditoriums and large rooms it is necessary to produce sufficient volume so that everyone in the room may hear the sound reproduced distinctly without forcing the reproducing device to a point where it distorts the sound and introduces extraneous noises. It is also desirable to have a sound reproducing device which will reproduce all the frequencies normally encountered faithfully without discrimination in favor of any particular notes. The device of this invention meets all these requirements in a simple and useful manner. In addition the structure has been so gotten up that the reproducing device is rendered exceedingly mobile and is arranged so that it may be materially reduced in height when desired and rendered accessible for adjustment and repair.

As shown in the drawings, the device comprises a base member 1 supported on pivoted rollers 2. Extending upwardly from the base member are two converging brackets 3 at the center of the platform laterally braced by means of the member 4. Extending vertically from the front edge of the platform are the converging members 5. The memhere 3 and 5 have the same vertical height and are interconnected by a pivoted rod 7. Pivotally supported on this rod is a large horn member 6 constructed of suitable material for the purpose in what is known as the exponential form. As is well known in the exponential horn the cross-sectional area of the horn increases from the small to the large end according to an exponential law. The horn is of course, provided with the usual bell as indicated at 8. Supported within this horn at the small end thereof is a cone type of reproducer comprising the actuating unit 9 and the conical diaphragm 10. The horn 6 is separate from the casing within which the reproducer is mounted as shown in the drawings so that the horn can be moved on its pivot rod 7. The free edge of the cone is secured to the baflie board 10 to block off the space below it. This board may or may not be secured to the horn proper. As shown the diaphragm 10 has its free edge opening upwardly so as to be in fullcontact with the air column within the horn. Supported on the back of the horn are two actuating units 11 and 12 connected to the metal trumpets 13 and 14 which extend through the bell of the large horn, so as to be adjacent the front thereof. The portions of the trumpets and their actuating units are enclosed by means of the hinged cover 15. In using a device of this type an amplifier is employed having a number of channels, each adapted to pass most efliciently a particular band of frequencies. The low frequency channels would be connected to the cone reproducer at the base of the horn and the high frequency channels would be connected to the trumpets.

By means of such an arrangement the large horn in combination with the cone loaded with a large air column would faithfully reproduce the low notes and the trumpets would faithfully reproduce the high notes. These notes issuing from the bell of the horn would blend into a composite whole. By providing a movable support for the device, it is easy to move it around especially in theatres in its use with talking motion pictures to permit moving it out of the way during actual acts on the stage. Furthermore by pivotally supporting the device on the rod 7, it is possible to swing it horizontall to reduce its vertical height when this is desirable. This also permits of easy access to the parts in adjusting them. If desired the mouth opening of the bell may be covered with any suitable fabric.

From the foregoing disclosure, it will be apparent that I have embodied certain principles in a physical construction which may be varied by those skilled in the art without departing from these principles, and I do not therefore desire to be limited to the disclosure given for purposes of illustration, but rather to the scope of the appended claims.

What I seek to secure by United States Letters Patent is:

1. In a sound reproducing device as described the combination comprising a support, rollers on said support to adapt it for easy movement, a large horn pivotally attached to said support, means in the base of the horn for reproducing sound, and a plurality of sound reproducing devices attached to the horn, so that the sound reproduced thereby will blend with the sound reproduced by the sound reproducing device in the base of the horn.

2. In a sound reproducing device of the type described the combination with an exponential horn, and a. sound reproducing device at the small end of said horn whereby it is loaded by the air column within the horn, of a plurality of sound reproducing devices mounted on said horn and metal horns projecting into said horn and connected to said sound reproducing devices.

3. In a sound reproducing device of the type described, the combination comprisin a cone loud speaker and a flared horn-shaped member within which the cone loud speaker is placed so that the air column formed by the member directly loads the cone of the cone loud speaker.

47. In a sound reproducing device of the type described, the combination comprising a horn having a mouth ortion, said horn having a relatively long air column with re spect to its cross sectional area, and a cone diaphragm mounted within said horn at the end opposite to the mouth portion thereof.

5. In a sound reproducing device of the type described, the combination comprising an exponential horn and a loud speaker having a cone diaphragm mounted within said horn at the small end thereof so that the cone diaphragm is loaded by the air column formed by the exponential horn.

6. In a sound reproducing device of the type described, the combination comprising a horn, a sound reproducing device within said horn having a diaphragm, and a baflie within said horn to which said diaphragm is connected.

7. In a sound reproducing device of the type described, the combination with a horn forming a relatively large air column, a loud speaker mounted within said horn having a cone diaphragm, and a baffle extending transversely of the born to which said cone diaphragm is secured.

8. In a sound reproducing device of the type described, the combination comprising a horn having a mouth portion at one end and said horn diminishing in cross sectional area from the mouth portion to the other end, a cone diaphragm mounted in the smaller end of said horn, a baflle extending across the horn near the small end thereof and connected to the cone diaphragm so that the cone diaphragm is on the opposite side of the baffie with respect to the mouth of the born.

9. In a sound reproducing device of the type described, the combination comprising a horn forming an air column, a loud speaker having a cone diaphragm mounted within said horn so that the cone diaphragm is loaded by the air column formed by the horn,.

and a baflle within said horn extending transversely thereof to which the cone diaphragm is attached, said bafiie being attached to said horn.

In testimony whereof I have hereunto set my hand on this 22nd day of December A. D.,

LEE DE FOREST.

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