US3292730A

US3292730A - Speaker cone unit

Info

Publication number: US3292730A
Application number: US522166A
Authority: US
Inventors: Harry J Moskow
Original assignee: MCGREGOR ELECTRONICS Inc
Current assignee: MCGREGOR ELECTRONICS Inc
Priority date: 1966-01-21
Filing date: 1966-01-21
Publication date: 1966-12-20
Anticipated expiration: 1983-12-20

Description

Dec. 20, 1966 H. J. MOSKOW SPEAKER CONE UNIT 5 Sheets-Sheet 1 Filed Jan. 21, 1966 uvmvron HAP/Q71]. MOS/(0W M United States Patent 3,292,730 SPEAKER CONE UNIT Harry J. Moskow, Skokie, Ill., assignor to McGregor Electronics, Inc., McGregor, Iowa, a corporation of Delaware Filed Jan. 21, 1966, Ser. No. 522,166

1 Claim. (Cl. 18l32) This invention relates to radio and television speaker cone apparatus.

It is common practice in the radio and television industries to employ a speaker cone apparatus or unit which includes a speaker cone assembly embodying a main and outer speaker cone within which is arranged an auxiliary inner speaker cone, or so-called whizzer cone, which vibrates with the outer or primary speaker cone at loW frequencies while vibrating or resonating independently of the outer or primary speaker cone at high frequencies. Such auxiliary or so-called whizzer cones have heretofore been made of felted paper or like paper stock impreg- 'nated with a water-resistant material but they have been subject to number of objections and among these is thefact that notwithstanding the use of water-resistant impregnating materials in the paper stock of such auxiliary or so-cal led whizzer cones they tend to absorb moisture, particularly in warm humid climates, and to warp, with the result that they lose sensitivity in the high or upper frequency ranges in which they are primarily intended to operate.

An object of the present invention is, therefore, to provide 'a new and improved speaker cone unit for television and radio use and embodying a new and improved auxiliary or so-called whizzer cone which is resistant to the action of humidity and resulting Warpage and exhibits a higher degree of sensitivity in the higher or upper frequency ranges than is exhibited by the impregnated felted paper auxiliary whizzer speaker cones heretofore used.

Another object of the invention is to provide a new and improved auxiliary whizzer cone unit for a television or radio speaker apparatus which is relatively simple and less expensive to manufacture than the prior impregnated felted paper stock auxiliary or whizzer cones since it does not require the operation of impregnating it with a waterresistant material.

A further object of the invention is to provide a new and improved auxiliary speaker or whizzer cone which may be made from any one of a variety of plastic resinous mate-rials by various molding methods or techniques, such, for example, as vacuum molding.

An additional object of the present invention is to provide a new and improved speaker cone unit for radio and television apparatus embodying a molded plastic resinous auxiliary speaker cone unit which is resistant to the action of moisture and resulting warpage and exhibits no loss of sensitivity in the 'upper range of high frequencies in the order of from 10,000 to 20,000 cycles per second in which prior impregnated felted paper auxiliary or whizzer cones have exhibited loss of sensitivity.

Other objects will appear hereinafter.

In the drawings:

FIG. 1 is a top plan view of a speaker cone assembly embodying the present invention;

FIG. 2 is a side elevational view of the speaker cone assembly illustrated in FIG. 1;

FIG. 3 is a top plan view as seen from the top of FIG. 1;

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FIG. 4 is a central vertical sectional view.

FIG. 5 is a perspective view illustrating a typical embodiment of the new auxiliary speaker or whizzer cone;

FIG. 6 is an enlarged fragmentary sectional detail view of the new auxiliary speaker whizzer cone mounted in position of use;

FIG. 7 is a graph il'lustrating the vibration or resonance performance characteristics of a prior art impregnated felted paper auxiliary speaker or whizzer cone prior to being subjected to a humidity test;

FIG. 8 is a graph illustrating the vibration or resonance performance characteristics of the prior art paper auxiliary whizzer cone which forms the subject matter of the humidity test illustrated in FIG. 7 after it had been subjected to a humidity test;

FIG. 9 is a graph illustrating the vibration or resonance performance characterist cs of the new auxiliary speaker or whizzer cone of the present invention before it had been subjected to a humidity test;

FIG. 10 is a graph illustrating the vibration or resonance performance characteristics of the new auxiliary whizzer cone of the present invention, and which forms the subject matter of the test illustrated in FIG. 9, after it had been subjected to a humidity test; and

FIG. 11 is a sectional view illustrating a part of a typical apparatus used in making the humidity tests hereinafter referred to.

A typical embodiment of the new television or radio speaker cone apparatus is illustrated in FIGS. 1 to 4, inclusive, of the drawings, wherein it is generally indicated at 10, and includes a frame unit 11 which is shown as being rectangular in form but may be circular, or other form or shape, and has a rearwardly extending and conical-shaped portion 12. The rear portion of the frame unit 11 is attached to a box-like magnet housing 13 in which a magnet unit 14 is arranged and a voice coil 15 is attached to the housing frame unit 11 at the front end thereof and has electrical connections 16 attached thereto.

A frusto-conical shaped primary or outer flexible speaker cone 17 is arranged within the frame unit 11 and has a rearwardly extending annular flange portion 18 which is attached to the voice coil 15 (FIG. 6). The primary or outer flexible speaker cone 17 is preferably made of felted paper stock, or like material, impregnated with suitable water-resistant material, and has an annular front marginal flange portion 19 which is adhesively attached to the frame unit 12.

The present invention is particularly concerned with the provision of a new flexible auxiliary speaker or socalled whizzer cone, which is generally indicated at 20 in the drawings, and comprises a generally frusto-conical shaped body 21 having a rearwardly extending annular attaching flange portion 22 which is adhesively attached, as at 23, to the annular rear wall 18 of the primary or outer speaker cone 17 (FIG. 6), in a manner which will be described hereinafter. The inner and auxiliary speaker cone unit 24 also includes a convexly forwardly curved rear wall portion 24 (FIG. 6).

The new flexible auxiliary or whizzer cone 20 may be made of any suitable plastic resinous material or elastomer, such, for example, as high impact polystyrene resin, acetate resin, acetate butyrate resins, acrylic resins, rigid vinyl resins, nylon resins, polyteflone resins, phenolic resins, and propionate resins, and it may be made by any suitable molding method or technique such, for example, as vacuum molding, injection molding, or the like. However, I have found that the new auxiliary or whizzer cone 20 is preferably made of high impact polystyrene resin and in order to mount it in position of use I preferably apply a suitable hydrocarbon thinner or solvent for the polystyrene resin or an adhesive cement made by dissolving some of the material of which the auxiliary speaker or so-called whizzer cone is made in a suitable solvent therefor, to the outer surface of the annular attaching flange 22 thereof so as to soften the outer surface of the annular attaching flange 22 somewhat. The annular attaching flange 22 is then inserted into the annular rear wall portion 18 of the primary or outer cone 17 and allowed to dry, thereby adhesively attaching the inner auxiliary speaker cone 20 to the primary or outer speaker cone 17, as at 23.

The permissible thickness of the wall structure of the new auxiliary speaker or whizzer cone 20 is from 0.005" to 0.010" for an auxiliary speaker or whizzer cone which is from /2" to %1" in diameter across the inner or bottom wall 24 but if the length of the auxiliary speaker or whizzer cone is increased, and if the diameter of the inner or rear wall 24 is increased to 4 the permissible range for the thickness of the wall of the new auxiliary whizzer cone is from 0.005 to 0.025 which is approximately the maximum useful diameter for the new auxiliary whizzer cone 20.

FIG. 7 of the drawings is a graph showing the results of a test as to the vibration or resonance characteristics of a felted paper auxiliary whizzer cone from which the water-resistant impregnating material had been removed by dissolving it out with a solvent. The graph is generally indicated at 25 and includes ordinates 26 representing sensitivity in terms of decibels and abscissae 27 in terms of frequencies in cycles per second.

FIG. 8 is a graph showing the results of a test as to the vibration or resonance characteristics of the same felted paper auxiliary whizzer cone unit, which formed the subject matter of the test illustrated in FIG. 7, after it had been subjected to high humidity conditions for 12 hours.

Thus, as may be seen by comparing FIGS. 7 and 8, the sensitivity of the prior art auxiliary impregnated felted paper whizzer cone declined in the area of interest 28, namely, in the upper or high frequency range of 10,000 to 20,000 cycles per second, after it had been subjected to a twelve-hour humidity test, namely, from a range of sensitivity 29 of from approximately 3.5 to 13 decibels (FIG. 7) to a range of sensitivity of from approximately 2.0 to 7 decibels (FIG. 8). Such a loss of sensitivity is highly significant at high frequencies in the order of from 10,000 to 20,000 cycles per second.

FIG. 9 is a graph illustrating the results of a test made as to the vibration and resonance characteristics of a typical specimen of an auxiliary cone or whizzer cone unit 20 made in accordance with the present invention, and molded from high impact polystyrene resin, having a diameter of across the annular inner or bottom wall 24 and having a wall thickness of 0.005 inch. This auxiliary or whizzer cone unit 20 of the present invention was the same in overall size and wall thickness as the felted paper cone used in making the performance tests, the results of which are illustrated in FIGS. 7 and 8.

FIG. is a graph illustrating the results of a test on the performance characteristics of the same specimen of the new plastic resinous auxiliary speaker cone or whizzer unit, the results of a performance test on which are illustrated in FIG. 9, after the same had been subjected to a humidity test for 12 hours, normally to an at- .mosphere of 85 percent humidity (plus or minus five percent) and under the same conditions used in the humidity test on the felted paper auxiliary cone the performance characteristics of which are illustrated in FIGS. 7 and 8.

Thus, in FIGS. 9 and 10 those parts of the graph which are comparable to or which correspond to similar parts of the graphs illustrated in FIGS. 7 and 8 have been given the same reference numerals followed by the additional and distinguishing reference character a.

Thus, as shown in FIG. 9, in the area 28a, that is, in the high frequency range of between 10,000 and 20,000 cycles per second, the new plastic resinous auxiliary speaker cone exhibited a sensitivity in the range of from approximately 13 to 22 decibels, prior to the humidity test, which is substantially in excess of and substantially greater than the range of sensitivity between 3.5 and 13 decibels for the dry felted paper auxiliary cone or whizzer unit (FIG. 7). a

However, the superiorityof the new molded plastic resinous auxiliary speaker cone 20 over felted paper stock under high humidity conditions is best illustrated in FIG. 10, in which it will be note-d that in the area of interest 28a, that is, at high frequencies in the range of between 10,000 and 20,000 cycles per second, in the range of sensitivity 29a continued to be and remained between 13 and 22 decibels, thus indicating no loss of sensitivity at the lower end of the range of sensitivity in the upper range of sensitivity after the humidity test.

In making the tests, the results of which are illustrated in FIGS. 7 to 10, inclusive, the new molded plastic resinous speaker cone exhibited no warpage after it had been subjected to high humidity conditions for 12 hours, whereas there was substantial warpage in the felted paper auxiliary cone (FIG. 8).

Moreover, it has been found that while the use of various water-resistant impregnating materials decreases the loss of sensitivity of the prior impregnated felted paper auxiliary cones such water-resistant impregnating materials do not entirely eliminate moisture ab orption and resulting warpage and loss of sensitivity at high frequencies in the order of 10,000 to 20,000 cycles per second.

A typical apparatus which may be employed in making the humidity tests hereinbefore referred to is illustrated in FIG. 11 of the drawings, and comprises a suitable water-containing vessel 30 in the upper portion of which the auxiliary whizzer cones, as 20, may be disposed with the outer speaker cone 17 resting on and closing the open upper end portion of the vessel 30, the water in which may be heated in any suitable manner, so as to direct the water vapor therefrom against and into contact with the auxiliary whizzer cone, as 17.

It will thus be seen from the foregoing description, considered in conjunction with the accompanying drawings, that the present invention provides a new and improved auxiliary speaker cone unit for television and radio apparatus, and thus has the desirable advantages and characteristics, and accomplishes its intended objects including those hereinbefore pointed out and others whichare inherent in the invention.

I claim:

A speaker cone unit for radio and television apparatus comprising (a) a frame unit having a rearwardly extending generally frusto-conical shaped portion;

(b) a primary and outer frusto-conical shaped flexible speaker cone member arranged within said generally frusto-conical shaped frame portion and having a cylindrical rear end portion, and a front end terminating in a planar flange the marginal edges of whic are attached to the frame unit;

(c) said primary outer frusto-conical speaker cone member being composed of fiber material impregnated with water-resistant material;

(d) an auxiliary and inner frusto-conical shaped flexible speaker cone member arranged within the said primary and outer frusto-conical shaped flexible speaker cone member and including a cylindrical rear end flange portion fitting within and adhesively attached to the said cylindrical rear end portion of the said primary outer flexible speaker cone member;

(e) said auxiliary and inner frusto-conical shaped flexible cone member being composed of synthetic plas- 3,292,730 5 6 tic resinous material and a wall thickness in the order References Cited by the Examiner between substantially five thousandths (0.005) and TAT twenty-five thousandths (0.025") of an inch; UNITED S Es PATENTS ('f) said auxiliary cone member having at its inner end 2,003,908 6/1935 Smlth et a1 an integral convexly forwardly curved rear Wall; and 5 2565069 8/1951 Engholm (g) which cone unit is highly resistant to the action of 2,615,995 10/1952 V013? 179-4155 moisture under conditions of high humidity and 3,213,209 10/1965 Doehtzsch Which exhibits no substantial loss of sensitivity in the upper range of high frequencies in the order of from RICHARD WILKINSON Prlmary Examiner 10,000 to 20,000 cycles per second. 10 STEPHEN J. TOMSKY, Examiner.