US2769942A - Voice coil for loud speakers - Google Patents

Description

NOV. 6, 1956 ss N 7 2,769,942

VOICE COIL. FOR LOUD SPEAKERS 2 Sheets-Sheet l Filed Nov. 26, 1954 INVENTOR. W?

Nov. 6, 1956 J. A. HASSAN VOICE COIL FOR LOUD SPEAKERS 2 SheetsSheet 2 Filed Nov. 26, 1954 BY 7 IIZ2TOR I M 004 tends to move said voice coil the 2,769,942 VOICE COIL FOR LOUD SPEAKERS Joseph A. Hassan, Weymouth, Mass., assignor of one-half to Fauthal A. Hassan, Weymouth, Mass.

Application November 26, 1954, Serial No. 471,202 2 Claims. (Cl. 317-158) its excursion, keeps within an effective influence of the magnetic flux, especially when reaches the voice coil. Since the low frequency current greatest distance, my invention is particularly effective in this respect.

To accomplish this, said coil winding, extending along the length of the coil form, is shorter than that commonly same length, being three layers thick, hence the resistance remains, at least, the same as in a two-layer, coil winding of greater length on said form.

The foregoing and other objects which the nature of the invention is better understood may be fall within the scope of my claims.

In the drawings:

Fig. 1 is a longitudinal, sectional view of a ducing device having my voice coil.

Fig. 2 is an enlarged, fragmentary, sectional view showing the voice coil in normal position in said device.

Fig. 3 is a view similar to- Fig. 2; but showing the voice coil in an actuated position therein.

Fig. 4 is a top plan view of my voice coil.

Fig. 5 is a fragmentary, elevational view, showing a free end of the voice coil wire with a flattened portion.

Fig. 6 is a longitudinal, sectional view of a modified form of voice coil.

Fig. 7 is a longitudinal, sectional view fied form of voice coil.

Fig. 8 is a perspective View of the voice coil shown in Fig. 7.

Fig. 9 is a longitudinal sectional view of another modified form of voice coil.

Fig. 10 is a sectional view taken on line 1010 of Fig. 9.

Fig. 11 is an enlarged, sectional view taken on line 11-11 of Fig. 9.

As illustrated, my device has the usual instrumentalities to actuate or vibrate the diaphragm. These include the usual magnetic frame it) embodying at its upper part an inwardly extending portion 12. A field pole 14, having a base portion 16, is attached to said frame 10 and extends upwardly therefrom. A voice coil has a form 18 around which is a coil winding 26. This form 18 is split or separated as at 22.

Said coil winding starts with a free end 24, then the sound proof another modi- Wire is wound around said form 18 until three layers of wire 25 are provided. At the completion of this third and outside layer this leaves another free end 26 at the lower or opposite end of the voice coil from that of said free end 24. A portion of this free end 26 is then flattened, as at 28, until it is of no more thickness, and preferably of lesser thickness, than that of the coil form 18, hence its two thinner sides of said flattened portion are and outer peripheral surfaces thereof, hence it takes no space outside the voice coil and has noeflect on the magnetic flux.

The foregoing arrangement enables the use of a shorter voice coil while using the same length of winding wire, thus keeping the whole voice coil, during actuation, within effective influence of said flux. This maintains the volume satisfactorily constant and the sounds distinctive.

In Figure 6 of the drawings, 1 show a modified form of voice coil in which the coil winding of wire starts with a free end 39 and the winding continues for two layers of wire terminating in another free end 32 extending from thesecond layer. Then a separate wire 36, starting with a free end 34 is wound outside the other latter wire being or shallow space left between the outer parts of the encircling wire portions that lie alongside and in contact with each other. Said wires are, of course, circular in cross This enables the use of three layers of wire; without taking as much space as the three layers shown in Figures 1, 2 and 3, so that the voice coil is of somewhat reduced thickness.

A free end 37 of the wire of the third layer extends beyond an end of the coil winding and a flattened portion 38 thereof extends between the two ends of said form 18 in the manner previously explained, being within the inner and outer peripheral surfaces thereof. This free end 37 is soldered, as at 39, to said free end 32 that extends from said second layer, thus connecting the second material such as aluminum or other metal, being split as at 43. The winding starts with the usual free end 44 and the other free end 46 from the third layer of wire is soldered, as at 48, to said conductive said coil form 42 beyond said coil winding at an opposite end of the coil winding to said soldering point 48. Said soldering point 52 is located at an opposite side of said split from said point 48 so that the metal coil form 42 between said solder points provides the maximum travel for the electrical current while serving as a conductor in place of wire.

My device has the usual parts, including a compliance spider 56 surrounding and attached to the upper part of said coil form 18. A conical diaphragm its smaller end to said voice coil form 18. Outside said diaphragm 58 is the usual diaphra m support 60 of genof said spider 56 is attached.

in Fig. 9 of the drawings, instead of a voice coil form, I provide a combination of an independent voice coil winding 66 and a connector 68, the latter commencing where the coil winding 66 ends, being attached to an end of said Winding by cement. The diaphragm 58 will connect to the opposite end of said connector 68. The coil winding 66 is similar to that shown in Fig. l; but without a coil form. This assembly of a plurality of layers of wire, having an interior space, preferably has an indentation 70 forcibly made therein, surface of the coil winding 66 and extending inwardly from one end to the other.

A portion of a free end 72 of the voice coil winding 66 is flattened as at 74, and laid in said indentation 70 and cemented thereto. The size of the indentation 70 relative to said flattened portion 74 is such that the latter is wholly received within said indentation, thus not occupying any space in the magnetic gap. The free end 72 is then attached to said connector 68, as by cement, or laid alongside thereof, and extends between opposite ends thereof and beyond.

This arrangement eliminates the voice coil form within the coil winding 66, hence use of a smaller magnetic gap is possible to movably receive said coil winding 66 and said connector 68 beyond it. This reduction in the size of the magnetic gap results in a stronger magnetic flux, for a given magnet size.

What I claim is:

1. A voice coil comprising a non-magnetic form having a split therein extending the length thereof, and a coil winding embodying wire extending around said form in two layers, said coil winding having a free end extending from an inner said layer and another free end extending from the second of said layers, a separate wire, providing a third layer, outside said second layer embodying a free end extending between two portions of said form opposite commencing at the outer said split and beyond, and electricity conducting means uniting both said latter free ends, said wire forming said three layers being substantially circular in cross section, said separate wire lying partly in the dips between two portions of wire that are alongside of and in contact with each other and that form said first two layers.

2. A voice coil comprising a non-magnetic form having a split therein extending the length thereof, and a coil winding embodying wire extending around said form in two layers, said coil winding having a free end extending from an inner said layer and another free end extending from the second of said layers, a separate wire, providing a third layer, outside said second layer embodying a free end extending between two portions of said form opposite said split and beyond and Within the interior and exterior peripheral surfaces thereof, and electricity conducting means uniting both said latter free ends, said wire forming said three layers being substantially circular in cross section, said separate wire lying partly in the dips between two portions of wire that are alongside of and in contact with each other and that form said first two layers.

References Cited in the file of this patent UNITED STATES PATENTS 1,869,230 Tirnmons July 26, 1932 1,976,895 Snell Oct. 16, 1934 2,084,945 Cornwell June 22, 1937 2,503,243 Cohen Apr. 11, 1950

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