US1729281A - Electric horn - Google Patents

Description

Se t. 24, 1929. w. a. CONNOLLY ELECTRIC HORN Filed March 30, 1925 lllll Hmvennwr 2 Patented Sept. 24, 1929 UNITED STATES PATENT OFFICE NEW YORK, ASSIGNOR TO NORTH EAST CORPORATION OF NEW YORK ELECTRIC HORN Application filed men so, 1925. Serial m. 19,374.

This invention relates to electric horns of the kind in which a diaphragm is vibrated by the action of an electromagnet energized by an alternating or intermittent current.

One object of the invention is to produce a horn, of the type in question, in which the tone is substantially improved without complicating the construction. It has been found that a pleasing and penetrating tone is secured where a high overtone, such as an octave, is combined with the principal tone. I

have discovered that this may be accomplished by utilizing the magnetic armature as a resonant member. Another object of the invention is to simplify the mechanism of the horn as a whole, and to this end I propose to use various features of construction describedhereinafter and illustrated in the accompanying drawings.

In the drawings, Fig. 1 is a side-elevation, partly in section, of a simple form of horn embodyln' the invention. Fig. 2 is a bottom view 0 the diaphragm and the armature attached thereto, Fig. 3 is a top plan-view of the electromagnet and its housing. Fig. 4 is a side-elevation, partly in section, of another embodiment of the invention; and Fig. 5 is a plan-view of the rear portion of the horn shown in Fig. 4, also partly in section.

The horn shown in Figs. 1, 2 and 3 has the usual front portion 10, constituting the hornproper or projector, and. a diaphragm 11 for vibrating the air in the projector. The armature 12 is in the form of a disc, and is fastened concentrically to the diaphragm by a central boss 13. The magnet has a central core 14, surrounded by a winding in the form of a coil, and the coil is enclosed by a cup-shaped iron or steel shell 16. The magnetic circuit is completed through this shell and through the air-gap between the edge of the shell and the periphery of the armature. The magnet is mounted in a cup-shapedhousing 17 which is fastened to the projector and to the periph cry of the diaphragm.

The coil 15 is energized by an alternating or intermittingcurrent, in any convenient manner, and this results in a vibration of the armature towards and from the magnet. The

resonant action of the armature is securedby providing an air-gap between the boss 13 and the core 14 of a width such that these parts strike together when the armature and diaphragm are vibrated, while at the same time the clearance between the shell 16 and the armature is great enough so that these parts radial slots to diminish eddy currents therei in. These slots are not necessarily used, however.

Figs. 4 and 5 show an embodiment of the invention in which a circuit-breaker is used to render the magnetizing current intermittent. In this case the diaphragm 11 is clamped between the projector and an iron member 18. This member isdrawn from' sheet-metal and is so formed as to provide the core and the shell of the magnet, the core being formed by a hollow central rearward projection 19, around which the coil 15 is placed. The armature-disc 20 is fixed on a stem 21 secured to the middle of thediaphragm, and at its rear portion this stem is attached to the middle of a blade-spring 22, which serves to prevent lateral motion of the stem. A shoulder or flange 23 on the stem is arranged to engage the magnet-core 19 when the armature is drawn forwardly, thus causing the armature to ring and to transmit high-pitched vibrations through the stem to the cliaphragn'i. Two posts 24 and25 are fixed on the member 18, and the ends of the spring 22'are fixed upon these posts. A crossbar 26 is fixed upon, but insulated from, the posts and it carries an adjustable stationary contact 27. A movable contact 28 is mounted on a spring-blade 29 which is fixed at one end upon the post 24.

The inner end of the contact-spring 29 is perforated to clear the stem 21, and this stem carries a nut or abutment 30 so adjusted as to engage and move the contact-spring and thus interrupt the current at each forward vibration of the armature and the stem. The contact carrying bar 26 may be connected, by a wire 31, with an external source of current, and the circuit is completed through the winding 15 in any ordinary or suitable manner.

I am aware that it has been previously proposed to construct horns of the general form shown in Fig. 1, in which the parts are so arranged that the armature strikes against the magnet-poles, and thus modifies the tones emitted by the diaphragm. In such previous horns, however, it has been customary to use a U-shaped magnet so that the armature is struck at points remote from its central point of attachment. This prevents the armature from ringing with-a clear and definite note, and causes the sound of the horn to be noisy and harsh without any definite relation between the principal tone and the overtones.

The invention is not limited to the embodiments thereof hereinbefore described and illustrated in the accompanying drawings, but it may be embodied in various other forms within the scope of the following claims.

The invention claimed is:

1. A magnetic horn comprising: a vibratory assembly including a diaphragm and a sonorous armature connected together only at their middle portions; and a magnet comprising a central core surrounded by a coil; the middle part of the vibratory assembly being arranged to engage and be arrested by the magnet core at each vibration, while the air-gap between all other portions of the magnet and the armature is suificient to prevent engagement of such otherportions.

2. A magnetic horn comprising: a stationary assembly includingan electromagnet, and a vibratory assembly including a diaphragm and an armature; the diaphragm and armature being attached rigidly) together at their central points but eing otherwise free from each other, and the stationary and the vibratory assemblies having centrally located portions which interengage to arrest the vibratory movement at one extreme; the clearance between the stationary assembly and the armature being substantially greater at all other points than it is at said centrally located portions.

3. A sound signal having a vibratory assembly comprising a diaphragm and an armature attached thereto, the diaphra m, as loaded with the armature, having a (felinite natural frequency of vibration; the armature constituting in itself a sonorously vil ratory body attached to the diaphragm at a point such that it ma have independent vibratory movement 0 a frequency ap- WILLIAM B. CQNNOLLY.

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