US3329777A - Dynamic ear phone - Google Patents

Description

Jul 4, 1967 DONALD LE ROY KLlEW ER DYNAMIC EAR PHONE Filed July 5, 1964 QIEP" 195:! [L

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R O T N E V m DONALD LEROY KLIEWER ATTORNEY FIG?) JIM 32M 34 United States Patent 3,329,777 DYNAMIC EAR PHONE Donald Le Roy Kliewer, East Providence, R.I., asslgnor to Plastic Mold & Engineering Co., East Providence, R.I., a corporation of Rhode Island Filed July 3, 1964, Ser. No. 380,147 6 Claims. (Cl. 179115.5)

This invention relates to dynamic ear phones and more particularly to an air cushion between a rigid guard and rigid medial auxiliary batten attached to the vibrating diaphragm.

This application is a continuation-in-part of United States application, Ser. No. 282,998, filed May 24, 1963, now Patent No. 3,230,319, for a Dynamic Ear Phone.

One of the objects of the present invention is to remove the fugitive vibrations inherent in a diaphragm especially at high frequencies.

Another object of the present invention is to provide a guard which protects the vibrating diaphragm of an ear phone against probing foreign objects.

Still another object of the present invention is to provide an air cushion stiffening element between a rigid guard and the vibrating diaphragm.

In the past the surface of the diaphragm reacted with a wave producing motion so that more than one sound wave, namely, fugitive sound waves, were produced, interfering with the primary sound wave and the tonal quality of the primary sound wave.

The present invention overcomes the development of the fugitive sound waves by means of an air cushion which stiffens the vibrating diaphragm.

Other objects of the present invention will be pointed out in part and become apparent in part in the following specification and claims.

Referring to the drawings in which similar characters of reference indicate corresponding parts in all the figures:

FIGURE 1 is a vertical medial sectional view through the new and improved dynamic ear phone.

FIGURE 2 is an exploded perspective view of the construction illustrated in FIGURE 1.

FIGURE 3 is a perspective view of a detail in construction of the voice coil attached to the diaphragm.

In proceeding with this invention there is provided a circular frame, generally indicated by reference numeral 11, comprising an outwardly extending circular flange 12, a circular shell 13, and a tapered body section 14 provided with a circular band 15 and a plurality of air ports 16.

Circular flange 12 is provided with a chamber 17 having a stepped wall which provides a guard seat 18, a diaphragm seat 19 and a sloped side 20 terminating at the axial bore 21 of shell 13.

A magnetic structure having inner and outer pole pieces is required. One such structure will be described. Any equivalent structure may be substituted.

A hollow cylindrical member, serving the function of a pole piece, is generally indicated by reference numeral 23 and comprises a cylindrical wall 24 having a bottom plate 25 and a top plate 26 provided with a central opening 27. The hollow area of cylindrical member 23 is indicated by reference numeral 28. Top plate 26 provides the outer pole piece for the magnetic structure and may have a circular recess 38.

Hollow cylindrical member or pole piece 23 is fastened in circular shell 13 by means of a tight fit in axial bore 21.

A solid cylindrical magnet 30 is centrally disposed within hollow cylindrical member 23 and is fastened to bottom plate 25 by means of an electrically insulating cement 32. Bottom plate 25 may be provided with a circular recess 31 for the purpose of holding the insulating cement 32 and to permit the cylindrical magnet 30 to be embedded therein. Magnet 30 projects through central opening 27 with an air gap 33 between cylindrical magnet 30 and the side of central opening 27. The magnet 30 may be termed the inner pole piece. I

A diaphragm, generally indicated by reference numeral 40 is preferably fabricated from a membrane of polyethylene terephthalate or a co-polymer of polyvinylidine chloride. One aspect of the former is known commercially as Mylar and the latter as Saran-Wrap.

Diaphragm 40 is of a shape illustrated in the drawing and consists of a general conical shape having a raised central portion or medial dome 41 and a tapering outwardly extending circular side portion 42 having a circular crimped area 43 which terminates in a fiat rim 44. A plastic cone shaped button 45 having a circular band 46 is placed over medial dome 41 with the circular band 46 fastened to said circular side portion 42 :by means of a heat seal or an adhesive. An air pocket 47 is formed between dome 41 and button 45. Flat rim 44 is secured to diaphragm seat 19 by means of an adhesive.

The tapering outwardly extending circular side portion 42 is the area of the diaphragm which produces the low frequency sound waves. The plastic cone shaped button 45 in cooperation with medial dome 41 produce the high frequency sound waves.

A voice coil 35 having terminal ends 36, 37 is fastened to diaphragm 40 by means of an adhesive 39. Medial dome 41 assists in locating the convolutions of the voice coil in exact medial position on the diaphragm 40. The exact locating of the voice coil on the diaphragm is necessary for the proper location of the voice coil in air gap 33 and the proper functioning of the voice coil and diaphragm.

Voice coil 35 is placed in central opening 27 surrounding cylindrical magnet 30 and within air gap 33.

A guard plate, generally indicated by reference numeral 50, is provided with a plurality of perforations or air spaces 51. Guard plate is preferably fabricated from metal such as aluminum and is fastened to guard seat 18 by means of a press fit.

The structure described supra provides a new and improved dynamic ear phone having superior tonal qualities. However, it has been found that the additional structure about to be described further adds to the tonal qualities of the ear phone.

A cover, generally indicated by reference numeral 52, comprises a base 53, and an integrally formed circular side wall 62 provided with a peripheral edge 63 which is fastened to circular band 15. A cavity 54 is formed between cover 52 and circular frame 11.

Silk in the form of disks 60 or any other air porous material is fastened by means of an adhesive over the ends of air ports 16 and to tapered body section 14 on cavity 54 side of air ports 16. Porous material disks 60 filter the air which passes from chamber 17 to cavity 54 through air ports 16. Cavity 54 is provided for back loading as will hereinafter appear.

Diaphragm 40 divides chamber 17 into two sections. Inner or rear section 17 and outer or front section 17A.

Lead wires 36A, 37A are provided as extentions to terminal ends 36, 37 respectively. Body section 14 is provided with two channels 70, 71. Cover 52 is provided with an opening 73. Lead wires 36A, 37A are passed through opening 73 and channels 70, 71 respectively and are united, as by twisting, to ends 36, 37 respectively.

A rigid guard preferably fabricated from metal (see FIGURE 2) is provided with a centrally located projection 81 which is adapted to fit in an orifice 82 in guard plate 50 and be swedged over to form a rivet 83 as seen in FIGURE 1 whereby rigid guard 80 is fastened to guard plate 50. In this manner an air gap 84 is provided between rigid guard 80 and plastic cone shaped butt-on 45.

The air in air gap 84 becomes a stiffening element acting upon cone shaped button 45 to reduce the frequency of vibrations of button 45 and thereby the fluttering vibrations. In this manner the pitch of the diaphragm 40 is improved especially on the high frequency side of said diaphragm 40.

At high frequency vibrations the diaphragm has a tendency to flutter and produce fugitive vibrations which interfere with the pitch or tonal qualities of the diaphragm.

Rigid guard 80 also prevents a probing object from passing through air spaces 51 to injure diaphragm 40.

In operation, lead wires 36A, 37A are attached to a sound source (not shown) which provides the electrical energy to vibrate the voice coil and diaphragm.

A DC magnetic field exists between magnet 30 and top plate 26 across central opening 27. The vibration of the voice coil 35 in the DC magnetic field transforms the DC current into an AC impedance. The shape of pole piece 23 provides a path for the harnessing of the magnetic lines of force inherent in magnet 30.

Opening 73 is just large enough to accommodate lead wires 36A, 37A. Chamber 54 is filled with atmospheric pressure air. As diaphragm 40 vibrates it moves air in front section 17A through air spaces 51 to produce sound waves. Diaphragm 40 also moves the air in rear section 17 through ports 16 into air filled chamber 54. Porous disks 60 provide a resistance to the movement of air through ports 16. Chamber 54 provides back pressure to the movement of air from ports 16 into chamber 54. In this manner, the air in rear section 17 impedes the vibration of diaphragm 40 and thereby the frequency response and tonal quality of diaphragm 40. Plastic cone shaped button 45 stiffens diaphragm 40 in the medial area whereby the frequency response of the medial area is also impeded.

It is the control of the frequency response of the medial area of the diaphragm 40 through button 45 and the control of the frequency response of the entire diaphragm 40 through the impedance of air in rear section 17 which provides the present structure with the ability to produce both low and high frequency responses and primary sound waves unfettered with secondary sound waves. Secondary sound waves are produced by the uncontrolled vibrations of a diaphragm.

Applicant has produced a diaphragm which is both a tweeter and a woofer.

Having shown and described a preferred embodiment of the present invention by way of example, it should be realized that structural changes could be made and other examples given without departing from either the spirit or scope of this invention.

What I claim is:

1. -A dynamic ear phone comprising a movable diaphragm, a button, means fastening said button to said movable diaphragm, a voice coil, means fastening said voice coil to said diaphragm, a magnetic structure, said magnetic structure having inner and outer pole pieces forming an air gap therebetween, a frame, means mounting said diaphragm to said frame with said voice coil disposed within said air gap, means fastening said magnetic structure to said frame, a guard plate, means fastening said guard plate to said frame and a rigid guard, means securing said rigid guard to said guard plate to form a second air gap between said rigid guard and said button whereby said second air gap provides a stiffening element acting upon said button to reduce the frequency of vibration of said button.

2. A dynamic ear phone comprising a frame having a chamber and a diaphragm seat, a movable diaphragm having a medial dome, a button, means fastening said button to said diaphragm over said medial dome with an air space between said medial dome and button, a voice coil, means fastening said voice coil to said diaphragm, a magnetic structure, said magnetic structure having inner and outer pole pieces provided with an air gap therebetween, means mounting said diaphragm in said diaphragm seat with said voice coil disposed within said air gap, said diaphragm being located in said chamber and dividing said chamber into two sections, means fastening said magnetic structure to said frame, a guard plate, means fastening said guard plate to said frame and a rigid guard, means securing said rigid guard to said guard plate to form a second air gap between said rigid guard and said button whereby said second air gap provides a stiffening element acting upon said button to reduce the frequency of vibration of said button.

3. A dynamic ear phone comprising a frame having a shell provided with an axial bore, a tapered body section provided with a plurality of air ports, and a chamber having a wall provided with a diaphragm seat, a movable diaphragm of a general conical shape having a medial area and a tapering outwardly extending circular side portion, a button, means fastening said button to said diaphragm at said medial area with an air space between said medial area and said button, a voice coil, means fastening said voice coil to said diaphragm at said medial area, a magnetic structure having inner and outer pole pieces provided with an air gap therebetween, means fastening said movable diaphragm in said diaphragm seat with said voice coil disposed within said air gap, said diaphragm being located in asid chamber and dividing said chamber into two sections, means fastening said magnetic structure in said axial bore, a cover provided with a cavity, and means fastening said cover to said frame to provide back pressure on said diaphragm through one of said two sections, said plurality of air ports and said cavity, a guard plate, means fastening said guard plate to said frame and a rigid guard, means securing said rigid guard to said guard plate to form a second air gap between said rigid guard and said button whereby said second air gap provides a stiffening element acting upon said button to reduce the frequency of vibration of said button.

4. A dynamic ear phone comprising a frame having a shell provided with an axial bore, a tapered body section provided with a plurality of air ports, and a chamber having a wall provided with a diaphragm seat, a movable diaphragm fabricated from a membrane of polyethylene terephthalate or a membrane of copolymer polyvinylidine chloride, and having a general conical shape provided with a medial area and a tapering outwardly extending circular side portion having a circular crimped area and a flat rim, a cone shaped button fbricated from plastic material, means fastening said cone shaped button to said diaphragm at said medial are-a with an air space between said medial area and said cone shaped button, a voice coil having terminal ends adapted to extend beyond said frame, means fastening said voice coil to said diaphragm at said medial area, a magnetic structure having inner and outer pole pieces provided with an air gap therebetween, means fastening said movable diaphragm through said flat rim in said diaphragm seat with said voice coil disposed with in said air gap, said diaphragm being located in said chamber, thereby dividing said chamber into a front section and a rear section, means fastening said magnetic structure in said axial bore, a cover provided with a cavity, and means fastening said cover to said frame to provide back pressure on said diaphragm through said rear section, said plurality of air ports and said cavity, a guard plate, means fastening said guard plate to said frame and a rigid guard, means securing said rigid guard to said guard plate to form a second air gap between said rigid guard and said button whereby said second air gap provides a stiffening element acting upon said button to reduce the frequency of vibration of said button.

5. A dynamic ear phone consisting of circular frame having a circular shell provided with an axial bore, a tapered body section provided with a circular band and a plurality of air ports, and a chamber having a stepped wall providing a guard seat, a diaphragm seat and a sloping side terminating at said axial bore, a hollow cylindrical member pole piece comprising a cylindrical wall having a bottom plate and a top plate provided with a central opening, means fastening said hollow cylindrical member pole piece in said axial bore, a cylindrical magnet, electrically insulating means fastening said cylindrical magnet to said bottom plate with one end of said cylindrical magnet located in said central opening, a diaphragm comprising a general conical shape having a medial dome, a tapering outwardly extending circular side portion provided with a circular crimped area and a fiat rim, a cone shaped button, means fastening said cone shaped button over said medial dome and to said tapering outwardly extending circular side portion, means fastening said flat rim to said diaphragm seat, an air pocket located between said medial dome and said button, a voice coil provided with terminal ends, means fastening said voice coil to said diaphragm, said voice coil being located in said central opening and around said cylindrical magnet, a guard plate provided with a plurality of air pockets, means fastening said guard plate in said guard seat, a plurality of air porous disks, means fastening said plurality of air porous disk-s over said plurality of air ports, a cover provided with a base and a circular side wall having a peripheral edge, and means fastening said peripheral edge to said circular band to form a chamber around said shell and hollow cylindrical member pole piece, a guard plate, means fastening said guard plate to said frame and a rigid guard, means securing said rigid guard to said guard plat to form a second air gap between said rigid guard and sai button whereby said second air gap provides a stiifenin element acting upon said button to reduce the frequency 0 vibration of said button.

6. A dynamic ear phone comprising a movable dia phragm, a button, means fastening said button to sai movable diaphragm, a voice coil, means fastening sai voice coil to said diaphragm, a magnetic structure, sai magnetic structure having inner and outer pole piece forming an air gap therebetween, a frame, means mount ing said diaphragm to said frame with said voice coil dis posed within said air gap, means fastening said magneti structure to said frame, a perforated rigid guard plate means fastening said guard plate to said frame and a rigit guard provided with a centrally located projection, mean securing said rigid guard to said perforated rigid guart plate through said centrally located projection to form 1 second :air gap between said rigid guard and said button whereby said second air gap provides a stiffening elemen acting upon said button to reduce the frequency of vibra tion of said button.

No references cited.

KATHLEEN H. CLAFFY, Primary Examiner.

A. MCGILL, Assistant Examiner.

Claims (1)

1. A DYNAMIC EAR PHONE COMPRISING A MOVABLE DIAPHRAGM, A BUTTON, MEANS FASTENING SAID BUTTON TO SAID MOVABLE DIAPHRAGM, A VOICE COIL, MEANS FASTENING SAID VOICE COIL TO SAID DIAPHRAGM, A MAGNETIC STRUCTURE, SAID MAGNETIC STRUCTURE HAVING INNER AND OUTER POLE PIECES FORMING AN AIR GAP THEREBETWEEN, A FRAME, MEANS MOUNTING SAID DIAPHRAGM TO SAID FRAME WITH SAID VOICE COIL DISPOSED WITHIN SAID AIR GAP, MEANS FASTENING SAID MAGNETIC STRUCTURE TO SAID FRAME, A GUARD PLATE, MEANS FASTENING SAID GUARD PLATE TO SAID FRAME AND A RIGID GUARD, MEANS SECURING SAID RIGID GUARD TO SAID GUARD PLATE TO FORM A SECOND AIR GAP BETWEEN SAID RIGID GUARD AND SAID BUTTON WHEREBY SAID SECOND AIR GAP PROVIDES A STIFFENING ELEMENT ACTING UPON SAID BUTTON TO REDUCE THE FREQUENCY OF VIBRATION OF SAID BUTTON.

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