US2831051A - Vibrato producing loud speaker - Google Patents

Description

April 15, 1958 E. D. TElKOWSKl 2,831,051

VIBRATO PRODUCING LOUD SPEAKER Filed Oct. 5, 1953 2 Sheets-5heet l JNVENTOR.

C nal era D /Eiiau/xli J l/wwey "Wm 1W- April 15, 1958 E. D. TEIKOWSKI VIBRATO PRODUCING LOUD SPEAKER Filed Oct. 5. 1953 2 Sheets-Sheet 2h V 5 mw m A, ha Z w W W 1 4 m w I w W 4w m 7 WY 3 a 62 a 6 2 2 3 6 2 q a 3 r a United States Patent "IBRATO PRODUCING LOUD SPEAKER Edward D. Teikowski, Milwaukee, Wis. Application October 5,1953, Serial No. 383376 11 Claims. (Cl. 179-1) This invention relates generally to loud speakers and more particularly to an improved loud speaker mounting for imposing a vibrato effect upon the reproduced sound.

Tone qualities may be substantially improved and rendered more pleasing by imposing'a vibrato effect upon the sound, and-for this reason manymeans have been devised for producing the vibrato efiect. It may be produced mechanically by reproducing the sound in a loud speaker, and rotating the speaker or directing the sound from it into a rotating horn. Such an arrangement imposes the vibrato effect upon the sound to render it much more pleasing to the senses. Howevenfor maximum tone quality, it has been found necessary to transmit the sound to two speakers, one a high frequency speaker and the other a low frequency speaker, and rotate both of the speakers or direct the sound emanating therefrom into suitable rotating horns. This requires a cumbersome and expensive apparatus.

it is therefore a general object of the present invention. to provide an improved loud speaker mounting for producinga vibrato effect upon the sound being reproduced.

Another object of thepresent invention is to provide an improved loud speaker mounting for producing a vibrato eifect of maximum quality on the sound being reproduced while utilizing only one loud speaker.

Another object is to provide a loud speaker system which improves the tone quality of the sound being reproduced.

Another object is to provide a rotating loud speaker mounted in a resonator for improving the tone quality of the sound being reproduced.

Another object is to provide an improved resonator for use with a loud speaker to improve the tone quality of the sound being reproduced by the loud speaker.

Another object is to provide a loud speaker system in which the sound being reproduced is distributed evenly over a wide area.

A further object is to provide an improved loud speakor mounting for producing a vibrato effect upon sound which is efficient in operation but of sturdy and simple construction.

According to this invention the improved loud speaker mounting comprises a cabinet having two bearings fixed therein for rotatably supporting a vertical shaft. The shaft in turn carried two oppositely disposed loud speakers, only one of which is operated at any one time for reproducing sound, the other serving as a spare speaker as Well as to balance the shaft'for smooth rotation. The shaft is rotated by an electric motor while the loud spealo er is reproducing sound to. produce a vibrato effect upon the sound. The speaker is connected to astandard amplitier through the bearings which. areelectrically conductive for transmitting the current .to the shaft which is connected tothe speakercoil to operatein the manner-of a slip ring connection. The resonant mounting .of the speaker includes a metal cowl completely surrounding the speaker,. with .a flanged .disk.;supported concentrically withthe cowl to the rear of the speaker and spaced slight- ZhdBLllSl ly from the rear opening of the cowl. This arrangement has been found to enhance the tone quality of the sound being reproduced by the loud speaker to a much greater degree than the same sound would have if reproduced by a rotating loudspeaker without the resonant mounting.

The foregoing and other objects of this invention, which will become more fully apparent from the following de tailed description of an embodiment thereof, may be achieved by the apparatus herein described by way of example, in connection with the illustrations of its structural components in the accompanying drawings, in which:

Figure l is a perspective view of a cabinet housing the loud speaker mounting comprising the present invention;

Figure 2 is a plan view of the aparatus illustrated in Figure 1 with the cabinet top partially cut away to reveal the interior mechanism;

Figure 3 is a view partly in front elevation and partly in vertical section taken substantially along the plane represented by theline 33 in Figure 2; and,

Figure is a fragmentary detail view in verticalsection depicting the construction of the upper bearing for supporting the shaft carrying the loud speakers.

Referring more specifically to the drawings and particularly to Figure 1 thereof, Where there is shown acabi net 5 of a type suitable for housing the loud speaker arrangement comprising the present invention. An octagonally shaped cabinet is illustrated as a suitable configuration, although it is to be understood that the cabinet maybe constructed in any desirable shape suitable for enclosing and supporting the loud speaker mounting of the present invention.

In the illustrated embodiment, each of the eight sides of thecabinet 5 isflprovided with a centrally located opening .6 through which the sound emanating from the loud spea.:er within is emitted. Theopenings 6 are covered with a relatively coarse mesh fabric which wil not unduly interfere with the passage of sound, the fabric covering being provided for=the sake of appearance only. Two of the sides of thecabinet 5 are supported byhinges 7 so that they will serve as doors 8 for gaining access to the mechanism housed within the cabinet.

As clearly shown in Figure 3, the interior of the cabinet Sis provided with twobearings 12 and 13 for rotatably supporting a vertical shaft The bearing 12 is centrally secured to the top of thecabinet 5 while thebearing 13 is similarly fixed to the bottom of the cabinet. Thelower bearing 13 comprises a cylindrical portion 15 having aflange 16 formed integrally therewith for receiving screws 17 which secure the bearing to the floor of thecabinet 5. A cone shaped recess is form the top of the cylindrical.portion 5 for receiving a complementarytapered end 1-9-formed on the lower end of theshaft 14. Thus theshaft 14 is firmly supported against lateral movement but is free torotate within theconical recess 18.

The upper-encirof theshaft 14 is similarly supported by the bearing 12 which is constructed to facilitate the assembly and removal of theshaft 14 as clearly shown in Figure 4-. The bearing 12 includes acylindrical portion 23=having afiange 24 for receivingscrews 25 which are screwed into the top of thecabinet 5 to securethe bearing in position. In this instance, however, thecylindrical portion 23 is not formed to provide a bearing surface for theshaft 14 as in thelower bearing 13, but instead'is'provided with a concentric bore 26 for receiving acoil spring 27 and aplug 23 slidably mounted therein.

TheplugZSis urgedoutwardly of thebore 26 by thespring 23, and its exposed end is formed to present aconical recess 32 similar to theconical recess 18 of thelower bearing 13. However, in this instance, theshaft 14 is not in direct engagement with therecess 32, but

is provided with anadapter 33 having atapered end 34 complementary to therecess 32 for engagement therewith to rotatably support the upper end of theshaft 14. Theadapter 33 is rigidly secured to the upper end of theshaft 14 to rotate with it, the end of the shaft being disposed within abore 35 formed axially in the end of theadapter 33 opposite thetapered end 34. However, theshaft 14 is electrically insulated from theadapter 33 by aninsulating material 36 lining thebore 35 for reasons to be subsequently described.

Thespring 27 functions to yieldably urge theplug 28 into engagement with theadapter 33 to firmly support theshaft 14 against lateral displacement but leaves it free to rotate. To remove theshaft 14 from its supportingbearings 12 and 13, it is only necessary to raise it against the pressure of thespring 27 to disengage thetapered end 19 from therecess 18 and displace the its removal. On the other hand, to replace it, it is only necessary to engage thetapered end 34 of theadapter 33 with therecess 32 and force theplug 28 upwardly against the pressure of thespring 27 to permit thetapered end 19 to be moved into engagement with theconical recess 13. Theshaft 14 may then be released and the downward pressure of thespring 27 will serve to securely retain theshaft 14 and itsadapter 32 within therecesses 18 and 32 respectively.

Two cone typeloud speakers 40 are rigidly secured to theshaft 14 in opposed relationship to rotate with it for producing the vibrato effect, the speakers being disposed within a resonator mounting for enhancing the quality of the tone, and generally identified in the drawings by thereference numeral 41. The two speakers 46 and theirresonant mounting 41 are identical in construction and therefore only one of them will be referred to, which will serve to describe both of them. In Figure 3 one of the speaker assemblies is shown in side elevation and a sectional view of the other is shown to illustrate the details of construction.

As there shown, thespeaker 40 is disposed within theresonator mounting 41 comprising acowl 42 of cylindrical shape for enclosing and supporting thespeaker 40. The forward end of thecowl 42 is bent inwardly to form an inwardly extendingflange 43 to which aperipheral flange 44 of the cone of thespeaker 40 is secured for rigidly supporting the speaker within thecowl 42.

The rear end of thecowl 42 is bent outwardly to form an outwardly extendingflange 48 through which thecowl 42 is attached to adisc 49 in spaced relationship by means ofrivets 50 passing throughspacers 51. The spacers serve to position the disc 49 a slight distance from the rear opening of thecowl 42. Thedisc 49 is shaped to form aflange 52 extending forwardly over the cowl 42 a slight distance from the periphery of theflange 48 to provide anannular space 53 for the passage of sound reflected from thedisc 49. Thus, thecowl 42 and thedisc 49 combine in the particular disclosed arrangement to form theresonator 41 for enhancing the quality of the sound, which is emitted from the forward opening of thecowl 42 as well as from its rearward opening through theannular space 53.

The two speaker assemblies are supported on theshaft 14 by a pair ofbrackets 56, each comprising asleeve 57 fixed to theshaft 14 by aset screw 58. Achannel member 59 is secured to thesleeve 57 and its extendinglegs 60 are each attached to one of thediscs 49 to thereby support the two speaker assemblies on theshaft 14 in opposed relationship to rotate with the shaft. 7

Although two speaker assemblies are illustrated in the drawings, they are utilized individually, the other serving as a spare speaker conveniently available for immediate shaft laterally to free it from the bearings and permit use in the event of a failure of the other. In addition, it serves to balance the shaft for smooth and even rotation, eliminating the necessity of ballast to balance the overhanging weight of the other speaker.

Thespeaker 40 is energized by a standard amplifier indicated diagrammatically in Figure 3 and identified by thereference numeral 64. The sound is received by theamplifier 64 from its source through a standard microphone (not shown) and transmitted to the speaker 5-5) by a pair ofconductors 65 and 66. The conductor is connected to the upper bearing 12 while theconductor 66 is connected to thelower bearing 13.

Since the bearing i2 is electrically conductive and has metal to. metal contact with theadapter 33, the electric current travels from the bearing 12 to theadapter 33. Aconductor 67 is connected to theadapter 33 and carries the current to aplug 68, the current being pre vented from entering theshaft 14 from theadapter 33 by reason of theelectrical insulation 36 separating the adapter from the shaft.

As previously stated, each of the two speaker assemblies are identical in construction, and therefore both are provided with ajack 72 adapted to receive theplug 68 and carry the current therefrom for energizing the speaker. With this arrangement theplug 68 may be inserted into either one of the twojacks 72 to connect either one of the twospeakers 49 with theamplifier 64. However, since only oneplug 68 is provided, only one speaker at a time can be connected, and either one may be selected with a minimum of efiort, simply by transferring theplug 68 from one of thejacks 72 to the other.

From thejack 72 the current is carried to thespeaker 40 by aconductor 73. The path of the current then continues from thespeaker 40 through aconductor 74 to theshaft 14 which is separated from the other part of the circuit by theinsulation 36 as previously described. Here again, by reason of the metal to metal contact with hearing 13, the current passes from theshaft 14 to thebearing 13, and thence is carried back to theamplifier 64 by theconductor 66 to complete the circuit. Thus, the specific bearing arrangement shown is particularly adaptable for the present application in that thebearings 12 and 13 efiiciently support theshaft 14 and its associated speakers for rotational movement, and also serve to carry the energizing current to the rotating speakers.

In order to impose the pleasant vibrato effect on the sound emanating from thespeakers 40 it is necessary to rotate the speakers while the sound is being reproduced as previously stated. Power for rotating theshaft 14 with itsspeakers 40 and their resonator mounting 41 is obtained from anelectric motor 77. A vibration absorbing mounting 78 is provided for supporting themotor 77 on the floor of the cabinet 15 to eliminate any adverse effects on the speakers 41) from any vibration which may be created by themotor 77 when energized.

Apulley 79 is keyed to the drive shaft of themotor 77, and asimilar pulley 80 is fixed to theshaft 14. The power from themotor 77 is transmitted to theshaft 14 by a V-belt 81 interconnecting the twopulleys 79 and 80. Thus, rotation of thespeakers 40 is effected by energization of themotor 77 to produce the pleasant vibrato effect on the sound reproduced by thespeakers 40, which is further enhanced by the resonator mounting 41.

From the foregoing description of the construction and operation of a practical embodiment of the improved vibrato producing loud speaker provided by the present invention, it will be apparent that the apparatus is especially adapted to improve the tone quality of sound reproduced by the energized speaker by reason of the combined effect of the rotational movement of the speaker with the resonator mounting in which the speaker is supported.

Although the illustrative embodiment of the invention assnosi has been described in considerable detail for the purpose of setting forth an operative and practical exemplifying structure, it is to be understood that the structure shown and described is intended to be illustrative only, and that various characteristics of the invention may be incorporated in other structural forms without departing from the spirit and scope of the invention as defined in the subjoined claims.

The principles of the invention having now been fully explained in connection with the foregoing description of embodying structure, I hereby claim as my invention:

1. In an apparatus for enhancing the tone quality of reproduced sound, a cabinet, a shaft rotatably mounted in said cabinet, a pair of resonator mountings supported on said shaft in opposed relationship to rotate with it, a speaker supported within each of said resonator mountings so that the tone of the sound emanating from said speakers is enhanced by he sympathetic vibration of said resonator mountings, and an amplifier connectible to either one of said speakers selectively for individual energization, whereby the tone quality of the sound re produced by either one of the speakers while they are rotating is enhanced by reason of the combined effect of the rotational movement of the speaker and the resonator mounting in which the speaker is supported.

2. In an apparatus for enhancing the tone quality of reproduced sound, a cabinet, a shaft rotatably mounted in said cabinet, a resonator mounting supported on said shaft to rotate with it, a speaker supported within said resonator mounting so that the tone of the sound emanating from said speaker is enhanced by the sympathetic vibration of said resonator mounting, and an amplifier connected to said speaker to energize it, whereby the tone quality of the sound reproduced by the speaker while it is rotated through a circle by revolving said shaft is enhanced by reason of the combined effect of the rotational movement of said speaker with the resonator mounting in which the speaker is supported.

3. In an apparatus for imposing a vibrato effect upon reproduced sound, a cabinet, an electrically conductive shaft, an electrically conductive adapter rigidly secured to one end of said shaft and electrically insulated therefrom, a bearing fixed to the top of said cabinet and adapted to receive said adapter for rotatably supporting one end of said shaft while maintaining electrical conductivity with the rotating adapter, a second bearing fixed to the bottom of said cabinet in alignment with said first bearing and adapted to receive the end of the shaft opposite the adapter for rotatably supporting it while maintaining electrical conductivity with it so that the shaft is rotatably supported by said bearings, a pair of speakers supported on said shaft in opposed relationship to rotate with it, a jack fixed to each of said speakers and electrically connected therewith, a plug connected to said adapter and adapted to be inserted into either one of said speakers to electrically connect the adapter with either one of the speakers, a pair of conductors, each electrically connecting one of the speakers with the shaft, and an amplifier having one of its output terminals connected to the top bearing and the other to the bottom bearing, whereby either one of said speakers may be individually energized by the amplifier while it is rotating by inserting said plug in either one of said jacks so that one side of the circuit will be carried by one bearing and the adapter to the plug and speaker, and the other side of the circuit Will be carried by the shaft and the other bearing.

4. in an apparatus for imposing a vibrato effect upon reproduced sound, a cabinet, an electrically conductive shaft, an electrically conductive adapter rigidly secured to one end of said shaft and electrically insulated therefrom, a bearing fixed to one end of said cabinet and adapted to receive said adapter for rotatably supporting one end of said shaft while maintaining electrical conductivity with the rotating adapter, a second bearing fixed to the other end of said cabinet in alignment with said first bearing and adapted to receive the end of the shaft opposite the adapter for rotatably supporting it while maintaining electrical conductivity with it so that the shaft is rotatably supported by said bearings, a pair of speakers supported on said shaft in opposed relationship to rotate with it, an electrical conductor having one end connected to the adapter and the other end connectable to either one of the speakers selectively for electrically connecting either one of the speakers to the adapter, a

pair of conductors, each electrically connecting one of the speakers with the shaft, and an amplifier having one of its output terminals connected to said first bearing and the other to said second bearing, whereby either one of said speakers may e individually energized by the amplifier while it is rotating by connecting said conductor with either one of the speakers so that one side 0 the circuit will be carried by one bearing and the to the speaker, and the other side of the circuit will be carried by the shaft and the other bearing.

5. in an apparatus for imposing a vibrato effect upon reproduced sound, a cabinet, an electrically conductive shaft, an electrically conductive adapter rigidly secured to one end of said shaft and electrically insulated there from, a bearing fixed to one end of said cabinet and adapted to receive said adapter for rotatably supporting one end of said shaft while maintaining electrical conductivity with the rotating adapter, a second bearing fixed to the other end of said cabinet in alignment with said first bearing and adapted to receive the end of the shaft opposite the adapter for rotatably supporting it while maintaining electrical conductivity with it so that the shaft is rotatably supported by said bearings, a speaker mounted on said shaft to rotate with it, an electrical conductor connecting the adapter to the speaker for electrically connecting the speaker to the adapter, a second electrical conductor electrically connecting the speaker with the shaft, and an amplifier having one of its output terminals connected to said first bearing and the other to said second bearing, whereby one side of the circuit will be carried by one bearing and the adapter to the speaker, and the other side of the circuit will be carried by the shaft and the other hearing so that the speaker may be energized by the amplifier While it is rotating with said shaft.

6. In an apparatus for enhancing the tone quality of reproduced sound, a cabinet, a shaft having its ends tapered into a conical configuration, a bearing fixed to the lower end of said cabinet and presenting a conical recess complementary to a tapered end of the shaft for receiving said tapered end to rotatably support one end of the shaft, a bearing member secured to the upper end of the cabinet and having a concentric bore in alignment with said lower bearing, a plug slidably disposed Within said bore and presenting a conical recess complementary to a tapered end of the shaft for receiving it to rotatably support the other end of said shaft, a spring disposed Within said here to yieldably urge said plug outwardly of said bore into contact with its cooperating tapered end of the shaft so that the shaft may be readily removed from or assembled into its position between said bearings by raising the shaft while in engagement with the conical recess of said plug against the force of said spring to raise the lower end of the shaft above the lower hearing so that it may be displaced laterally into or out of engagement with the lower bearing, and a loud speaker mounted on said shaft to rotate with it and having electrical connection with an amplifier for energizing it, whereby the tone quality of the sound reproduced by the loud speaker may be enhanced by rotating the shaft to cause a corresponding rotation of the speaker while it is reproducing the sound.

7. in an apparatus for enhancing the tone quality of reproduced sound, a cabinet, a shaft having its ends tapered into a conical configuration, a bearing fixed to the lower end of said cabinet and presenting a conical recess complementary to a tapered end of said shaft for receiving said tapered end to rotatably support one end of the shaft, a bearing member secured to the upper end of the cabinet and having a concentric bore in alignment with said lower bearing, a plug slidably disposed within said bore and presenting a conical recess complementary to a tapered end of the shaft for receiving it to rotatably support the other end of said shaft, a spring disposed within said bore to yieldably urge the plug outwardly of said bore into contact with its cooperating tapered end of the shaft so that the shaft may be readily removed from or assembled into its position between said hearings by raising the shaft while in engagement with the conical recess of said plug against the force of said spring to raise the lower end of the shaft above the lower bearing so that it may be displaced laterally into or out of engagement with the lower bearing, a pair of disks fixed to said shaft in opposed relationship, a peripheral flange fixed to each of said disks and extending from the disks in a direction away from said shaft, a pair of cowls with each cowl having a front opening at one end and a rear opening at its opposite end, each of said cowls being supported by one of said disks in concentric relationship therewith to extend outwardly from the disk with its rear opening being adjacent to said disk and soaced from the surface of said disk but being located within the area defined by said flange so that said flange surrounds the end of said cowl that is adjacent to the surface of said disk to form an annular opening between a portion of the surface of said cowl and'said flange, a loud speaker mounted within each of said cowls at the ends opposite the disks so that the sound emanating therefrom may pass through the front opening of the cowl and through said annular opening, and an amplifier connectable to either one of said speakers selectively for individual energization, whereby the tone quality of the sound reproduced by either one of the speakers while they are rotating is en hanced by reason of the combined effect of the rota tional movement of said speaker and the sympathetic vibration of said cowl and flanged disk.

8. In an apparatus for enhancing the tone quality of reproduced sound, a cabinet, a shaft having its ends tapered into a conical configuration, a bearing fixed to the lower end of said cabinet and presenting a conical recess complementary to a tapered end of said shaft for receiving said tapered end to rotatably support one end of the shaft, a bearing member secured to the upper end of the cabinet and having a concentric bore in alignment with said lower bearing, a plug slidably disposed within said bore and presenting a conical recess complementary to a tapered end of the shaft for receiving it to rotatably support the other end of said shaft, a spring disposed within said bore to yieldably urge the plug outwardly of said bore into contact with its cooperating tapered end of the shaft so that the shaft may be readily removed from and assembled into its position between said bearings by raising the shaft while in engagement with the conical recess of said plug against the force of said spring to raise the lower end of the shaft above the lower bearing so that it may be displaced laterally into or out of engagement with the lower bearing, a resonator mounting supported on said shaft, a speaker supported within said resonator mounting so that the tone of the sound emanating from said speaker is enhanced by the sympathetic vibration of said resonator mounting, and an amplifier connected to said speaker to energize it, whereby the tone quality of the sound reproduced by the speaker while it is rotated through a circle by revolving said shaft is enhanced by reason of the combined effect of the rotation movement of the speaker and the resonator mounting in which the speaker is supported.

9. in an apparatus for enhancing the quality of reproduced sound, a cabinet, a shaft rotatably mounted in said cabinet, a pair of disks fixed to said shaft in opposed relationship, a peripheral flange fixed to each of said disks and extending from the disks in a direction away from said shaft, a pair of cowls of substantially cylindrical configuration having a smaller diameter than the diameter of the circle defined by said flange with each cowl hazing from opening at one end and a rear opening at its opposite end, each of said cowls being supported by one of said disks in concentric relationship therewith to extend outwardly from the disk with its rear opening being adjacent to said disk and spaced from the surface said disk but being located within the area defined by said flange so that said flange surrounds the end of said cowl that is adjacent to the surface of said disk to form an annular opening between a portion of the surface of said cowl and said flange, and a loud speaker mounted within each of said cowls at the ends opposite the disks so that the sound emanating therefrom may pass through the front opening of the cowl and through said annular opening, whereby the tone quality of the sound reproduced by either one of the speakers while they are rotating will be rendered more pleasant to the car by reason of the combined effect of the rotational movement of the speaker and the sympathetic vibration of said cowl and flanged disk.

l0. In an apparatus for enhancing the quality of reproduced sound, a cabinet, a shaft rotatably mounted in said cabinet, a pair of disks fixed to said shaft in opposed relationship, a peripheral flange fixed to each of said disks and extending from the disks in a direction away from said shaft, 21 pair of cowls with each cowl having a front opening at one end and a rear opening at its opposite end, each of said cowls being supported by one of said disks in concentric relationship therewith to extend outwardly from the disk with its rear opening being adjacent to said disk and spaced from the surface of said disk but being located within the area defined by said flange so that said flange surrounds the end of said cowl that is adjacent to the surface of said disk to form an annular opening between a portion of the surface of said cowl and said flange, a loud speaker mounted within each of said cowls at the ends opposite the disks so that the sound emanating therefrom may pass through the front opening of the cowl and through the annular opening, and an amplifier connectable to either one of said speakers selectively for individual energization, whereby the tone quality of the sound reproduced by either one of the speakers while they are rotating is enhanced by reason of the combined effect of the rotational movement of the speaker and the resonance produced by said cowl and flanged disk.

11. In an apparatus for imposing a vibrato effect upon reproduced sound, a cabinet, a shaft rotatably mounted in said cabinet, a disk fixed to said shaft to rotate with it, a flange fixed to said disk and extending from the disk in a direction away from said shaft, a cowl having a front opening at one end and a rear opening at its opposite end and being supported by said disk in concentric relationship therewith to extend outwardly from the disk with its rear opening being adjacent to said disk and spaced from the surface of said disk but being located within the area defined by said flange so that said flange surrounds the end of said cowl that is adjacent to the surface of said disk to form an annular opening between a portion of the surface of said cowl and said flange, and a loud speaker mounted within said cowl at the end opposite the disk so that the sound emanating therefrom may pass through the front opening of said cowl as well as through the rear opening of said cowl and the annular opening, whereby the tone quality of the sound reproduced by the speaker while it is rotating with the shaft will be rendered References Cited in the file of this patent UNITED STATES PATENTS Leslie Ian. 9, 1951 10 Myers Apr. 10, 1900 Hoch Feb. 25, 1930 Kannenberg June 23, 1942 Mankowitz Dec. 20, 1949

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