US 2391924 A
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Jan. 3, ma
D. E. RUTTER, ET AL PHONE AND METHOD OF MAKING Filed July 16, 1941 FIG 1 1 DONALD E. RUTTER INVENTORS HARRY B. SHAPII Patented Jan. 1, 1946 PHONE AND METHOD OF MAKING SAME Donald E. Rutter, East Cleveland, Harry. B. Shapiro, Cleveland, and Walter J. Brown, Cleveland Heights, Ohio; said Harry B. Shapiro now by judicial change of name Harry B.- Shaper: assignors to The Brush Development Company, Cleveland, Ohio, a corporation of Ohio Application July 1.6, 1941, Serial No. 402,608 I v 13Claims. (Cl. 179-107) Our invention pertains to earphones and more particularly to the small type of phone which is adapted to fit in a person's outer ear.
An object of our invention is to provide a small phone which is adapted to fit into ears of many different sizes and shapes.
A further object of our invention is to provide an insert type earphone in which the shape of the earphone case helps .to hold the device in the wearers ear.
Another object of our invention is to provide an insert type piezoelectric earphone shaped to accommodate a relatively large crystal unit and in which the shape of the case cooperates with retaining means to hold the device in the wearer's ear.
Still another object of our-invention is to provide a piezoelectric earphone which is easily and quickly assembled.
It is also an'obiect of our invention to provide an encased earphone in which one portion of the case is adapted to yieldably conform to the contours of the wearer's ear to cooperate with the general shape of the earphone to hold the device in the wearer's ear.
A further object of our invention is to provide an earphone having a cord connected to the leads of an electro-mechanical transducer in a manner to cause-a pull on the cord to tighten the con nection between the cord and the "leads of the transducer. I
Another object of our invention is to provide an insert earphone adapted to withstand rapid changes in the surrounding air pressure.
It is another object of our invention to provide an insert type earphone subassembly primarily adapted to be placed in a mass production case which will fit many'diiferent ears but which may readily be placed in a special case moulded to fit an unusual ear;
Still another object of our invention is to provide an insert type earphone subassembly which is operable without an enclosing case.
A further object of our invention is to provide a new and improved method of assembling an earphone.
Another object of my invention is to provide a diaphragm of large area for an insert type earphone and to position the diaphragm drive pin to obtain the maximum volume 01' displacement for a, given amount of movement oi the drive pin.
Other objects and a fuller understanding of my invention may be had by referring to the follow- Junction with the accompanying drawing in which:
Figure 1 is an enlarged cross sectional view illustrating a step in the process of assembling an earphone in which a cutting die is shaping a diaphragm.
Figure 2'is an enlarged cross section illustrating the use of the cutting die as a Jig for positioning some 01' theparts of the earphone.
Figure 3 is an enlarged cross sectional view illustrating a further step in the process of assembling the earphone.
Figure 4' is an enlarged isometric view of an earphone subassembly with portions broken away to more clearly illustrate the parts.
Figure 5 is an enlarged isometric view of another earphone subassembly with portions broken awfly- Figure 8 is an enlarged plan view of the portion or the earphone which is adapted to fit against the wearer's ear.
. Figure 7 is a slightly enlarged view showing an earphone in position in the wearer's ear.
Figure 8 is a sectional view taken along line -8---8 of Figure 6, and
Figure 9 is an enlarged sectional view taken,
along line 0-9 of Figure 8.
In the construction and assembly of piezo-electrio earphones which are adapted to be inserted in a person's outer ear it is very important that the parts be accurately positioned with respect to each other, and especially important that the diaphragm and the crystal unit be accurately V positioned with respect to each other. To eflect this accurate positioning oi parts for an earphone which is adapted to be made by mass production methods we have devised a novel earphone sub- II to shear on the outside waste material 13.. With the cutting die I I in place a mounting frame I4 is positioned against the diaphragm it. This step is illustratedgin Figure 2. An adhesive may be applied to either the frame or the diaphragm to cause them to stick together. In connecting ing detailed description and claims, takenin con- 66 the frame ll to the diaphragm i! the cutting die i I acts as a jig to very accurately position the frame with respect to the diaphragm. The frame preferably engages the cutting die substantially entirely around its circumference but it may engage the die only at a few spaced intervals.
The frame I4 is formed of a plastic or other suitable material and has three notches ii in it for receiving three comers of a piezo-electric crystal unit I6. Connected to the fourth corner of the crystal unit is a drive pin H which is adapted to be connected to and actuate the diaphragm I! as an alternating current potential is applied to the crystal unit. The frame i4 also has a quirk or shoulder 8 for positioning the diaphragm l2.
Figure 3 illustrates the positioning of the crystal unit It in the mounting frame ll in a manner to cause the crystal unit to be accurately placed with respect to the diaphragm. Three corners of the crystal unit are placed in the three notches I! in the mounting frame It and the drive pin i1 is placed through a hole I! in the diaphragm l2 and lnto'a hole is in the die section l0. Thehole il in the die section is slightly larger than the drive pin i1 to enable the pin to be easily positioned therein, and has a substantial length for receiving the pin I! to cause the pin II to be accurately positioned with respect to the die section I and consequently accurately positioned with respect to the diaphragm i2 and the mounting frame I. with the pin H in the hole is the crystal unit may be rotated slightly about the pin as a center to position the corners of the crystal unit in the centers of the three notches I! in the mounting frame I. Adhesive material may be applied to the three corners of the crystal unit either before or after the unit is positioned in the frame to fasten them to the frame I, and adhesive may be applied to the drive pin to secure it to the diaphragm ii. The cutting die ii may then be removed from the forming die It and from around theframe i4, and the frame I4 with its associaied diaphragm and crystal unit may be removed from the die section II.
By following thesesteps in assembling an earphone, an operative subassembly consisting of the frame N, the diaphragm l2, and the crystal unit I6 is constructed in a manner which assures accurate alignment of parts even though the work is done ra idly. By utilizing the cutting die Ii as a Jig to position the frame with respect to the diaphragm, and utilizing the die section I 0 as a jig to position the crystal unit drive pin II with respect to the diaphragm l2 and the frame it, the closest manufacturing tolerances may be maintained thereby asalring a high quality earphone subassembly.
After the earphone subassembly consisting of frame ll, diaphragm l2, and crystal unit ll has been removed from the forming die II, a guard plate 25 is secured by an adhesive or other suitable means to the edge of the diaphragm 12 to protect the diaphragm from deformation and puncturing during submquent assembly work and while the earphone is being worn.
The diaphragm I2 is on the order of io.ooo of an inch thick and the crystal is on the order oi" 95 of an inch thick. Accordingly the subassembly must be handled carefully but when it is provided with a guard plate 2', and when the top surface of the crystal unit I 6 is below the edge of the mounting frame ll (as illustrated in Fig ure 4) extreme care which slows .down subsequent assembly work does not have to be exercised; The subassembly may be handled to position it it to manufacturers who prefer to use their own earphone cases. This is highly desirable as many units may be mounted in standard mass production earphone cases which-will fit most person's ears, but other units may be mounted on earphone cases moulded to fit ears which require special cases in order to provide sumcient support to hold the earphone in the users ear. Therefore, in order to provide an earphone for all persons who might desire one it is necessary to have an operative subassembly which can be mounted into a special case without requiring the services of a specialist to do so, and which may be mounted in standard types of mass production cases.
The crystal unit ll is comprised of two connected Rochelle salt crystal slabs 20 and two leads 40 attached to the slabs 2|! and adapted to connect the earphone into an electrical circuit which applies an alternating current to the crystals 20 to cause the crystals 2| to vibrate and actuate the diaphragm l2 according to the well known piezo-electric manner. For more detailed description of the piezo-electric action'reference may be made to Charles B. Sawyers Reissue Patent Number 20,680, and for a more detailed description of a three cornered mounting reference may be made to A. L. W. Williams Patent Number 2,105,011. The leads are very thin and in order to connect them into the electrical circuit we provide the mounting frame II with a terminal bar 4| about which the leads may be wrapped to provide a firm base for terminal clips 3|. The terminal clips ll (only one is shown) are co slide over the rminal bar 4| with a lead 40 positioned between each clip II and the terminal bar 4|. The mounting frame I is preferably formed of a plastic material and accordingly no insulator is needed in the terminal bar between the two clips 3|. However, if the terminal bar were made of a conductive material an insulator to electrically separate the two leads 4. could be added. A ridge 2 or notches 43 can be added to the terminal to prevent the two terminal clips 3| from sliding into engagement with each other. Figures 5 and 6 illustrate two halves of an earphone case which is.adapted to fit in many ears of different size and shape to hold the earphone in place. Figure 5 shows an outside portion 2' cl an earphonecase, and Figure 6 shows an inside portion 21 of an earphone case. The outside portion 28 constitutes that part of the case which can be seen in the ear ofa wearer as is illustrated in Figure 7, and the inside portion 21 constitutes the part of the case which lies against the wearcuit which supplies the earphone, and pass through a hole 32 in a raised portion 3| in the case I, through a hole II between the guard plate ll and a raised lug I4, and connect to the terminal clips ii.
The case portion 20 is egg" shaped in plan with a first end portion 44 and a second end portion 4|. The end portions and 4| are shaped as arcs of. circles, the arc of the first end I having aradius which, isgreater thantheradiul ofthearcoftheaecondendportionllandtbe ted in the electrical circuit and sides of the case may be substantially straight lines tangent to the two arcs, or slightly curved lines joining thetwo arcs. The guard plate 28 is circular and has a radius slightly less than the radius of the first end portion 44 of the case portion 26. Accordingly whenthe guard 28 is placed in the first end of the case it will stay in that position, and a pull on the twisted cord 26, 36 will cause the guard plate to wedge into a narrower part of the case 26 to prevent further movement. An adhesive 46 may be placed to thin at the apex. sealed as is illustrated in the cross sectionalview 6 or it may have an opening 61 as is illustrated in around the edge of the guard plate 28 where the plate engages the case portion 26 to prevent the guard plate 28 from moving after it has been placed in the case 26.
To connect the operative subassembly to the case portion 26, the-guard plate 28 is positioned over the crystal 26 and the operative subassembly and the case portion pushed together. The edge of the case portion 26 fits outside of a step 6| constituting part of the edge of the mounting frame l4. Z x
The inside case portion 21 (Figure 6) is adapted to engage the diaphragm guard 25, the outside edge of the diaphragm l2, and a step 41 on the edge of the mounting frame i4, and lie between formed of a soft yieldable' plastic material and with a cross section which tapers from fairly thick at the location where it joins the body portion 46, The apex may be completely Figure 6. By forming the snout 66 of a yieldable material with a cross section tapering to thin at the apex discomfort to the wearer's ear is reduced. when the earphone is placed in the wearer's ear the snout 66 yieldably assumes the direction of the ear canal with-very little pressure on the walls thereof and substantially completely seals the ear canal against extraneous sound entering from the the outside case portion 26 and the wearer's ear.;
earphone case to the case without damaging theoperating parts. This is effected by mounting the guard plate 28 directly to a portion of the case and by prow'ding the raised lug 34 which operates as a snubber post. Figure 8 best illustrates the operation of the lug 34 as a snubber post. The cord '29, 36 enters the earphone through the hole 32 in the raised portion 35 of the outside case portion 26, passes through the hole 33 between the lug 34 and the guard plate 28, bends back upon itself around the lug 34, and is connected to the terminal clip 3| in such a manner that a pull on the cord 29, 36 causes the terminal clip 3| to more closely engage the terminal bar 4|, and hence to more closely engage the lead 46. Most of the force of the pull on the wire 26, 36 is taken by the guard plate 28 and transferred to the case 26 and the rest of the pull is taken by the terminal bar 4| and transferred to'the case 21.
The inside case portion 21 is comprised of a body portion 48 shaped in plan substantially the same as the plan of the outside'case portion 26, a horn-shaped lug or ear engaging portion 46 connected to the body portion. and a snout 66. The lug 49 is adapted to lie in the groove between the helix 56 and the antihelix 66 of the ear and engage the bottom and both sides of the groove. It may be composed of a soft plastic material in order that it will adjust itself to slightly different shaped ears and aid in holding the earphone in place. By forming the lug 46 ofa soft formable plastic material it will engage the bottom and both sides of the groove without excessive springpressure against either the helix or the antihelix which in time is apt to cause discomfort no matter how slight the pressure is. The body portion 48 is formed of a yieldable plastic material which is fairly thick around the edges where "it engages the mounting frame l4. The snout 66 is adapted to project into the ear canal which joins the outer ear with the inner ear. The snout 66 is outside and against sound from the earphone leaking to the outside. The body portion 46 and the snout 66 of the case portion 21 are soft and yieldable. Accordingly a careless person handling the earphone might squeeze it too hard and damage the diaphragm l2 and the crystal 26 were it not for the diaphragm guard 26. Further, in an earphone having a sound snout with opening 61 in its end it is probable that the wearer will at some time try to clean the earphone with a match, toothpick, or pin. The diaphragm guard 26 is positioned to prevent damage from this source. The guard 26 may be made of sheet metal or plastic material with holes. 24 through it as is illustrated in Figures 8 and 9.
.By forming the engaging portion 46 and the snout 66 of formable soft plastic material which many ears although the ears vary to a certain extent in size and shape. The smaller end portion 45 of the case is adapted to lie in the concha of the ear with the tragus 68 and the antitragus 66 engaging the top portion of the outside case 1 26, and with the raised portion 66 extending slightly out from between the tragus 68 and the antitragus 66. The curve of the engaging portion 46 and the snout 66 cooperate with the general wedge shape of the earphone case to prevent the earphone from sliding downward in the ear even though a fairly hard pulling force is exerted on the cord 26, 36.
The diaphragm 12 has a shape in plan substantially the same as the plan shape of the body portion 48 of the inside case portion 21. The end 66 of the diaphragm I2 is an arc of a circle and the end 66 of the diaphragm is an arc of a circle having a smaller radius than the radius of the end 66 and having a different center. Each of the two sides of the diaphragm I2 is a straight or slightly curved line joining the two arcs. This shape provides a diaphragm of maximum area for the earphone, but introduces a compliance along the major axis which reduces the efliciency of the piston action of the diaphragm. The major axis may be defined as the centerline of the diaphragm extending through the centers of the arcs which describe the ends of" the diaphragm. or the major axis may be defined as the axis about which the diaphragm is symmetrical. To increase the efficiency of the piston action we have provided a diaphragm which is substantially conical in cross section and which is driven by'the crystal unit 16 from oil-center. The distance from the large end 66 to the apex of the diaphragm being greater than the distance from the small end 66 to the apex. This combination of an off-center drive for a conical diaphragm which is eg -shape" in plan provides substantially the maximum air the apex of the diaphragm.
displacement for a given movement of the crystal drive unit It. By connectingthe drive pinoifcenter the shorter side of the diaphragm becomes more stiif than the longer side and tends to act as a lever to increase the movement ofthe'longer 5 side of the diaphragm thereby increasing the total volume displaced by the entire diaphragm. Further, it provides space for a larger crystal unit 20 thereby increasing the amount of movement at If it is desired that the earphon be used in airplanes where the pressure around the earphone is subject to rapid changes we provide a pressure equalizing hole 23 in the outside case portion 28. The hole 23 communicates with the inside of the earphone on the convex side of the diaphragm to establish an air passage for equalizing the internal air pressure with the external air pressure.
A small amount of air leakage between the snout II and the walls of the ear canal will enter the inside of the earphone on the concave side of the diaphragm through the opening 51 in the shout thereby equalizing the air pressure on both sides of the earphone diaphragm ii. The air pressure on both sides of the diaphragm of the wear-- er's ear will also be substantially equalized due to a slight amount of leakage around the snout 50.
Although we have described our invention with a certain degree ofparticularity it is to be understood that various changes can be made in the size, shape, and arrangement of parts without departing from the spirit and scope of our invention.
l. The process of constructing an operative earphonesubassembly having a preformed frame and a crystal unit; the steps of said process comprising: forming a diaphragm from sheet material using die means, cutting said diaphragm .from said sheet material using die means, fastion the said crystal unit with respect tothe said diaphragm.
2. The process of assembling an arphone hay-j ing a crystal unit with a drive pin which comprises the steps of cutting a diaphragm between a first and a second die section, securing a preformed frame member to said diaphragm utilizing said second die section as a Jig to accurately position the said frame with respect to the said diaphragm, securing said crystal unit to th said frame utilizing said first die section as a jig to accurately position the said crystal unit with. respect to the said dia hragm, and securing the drive pin of the said crystal unit to the said diaphragm. I
3. The process of constructing an earphone subassembly comprised of a diaphragm, a frame, and a crystal unit; the steps of said process com-' prising:' cutting said diaphragm between die means, securing said frame to said diaphragm utilizing said die means to accurately position the frame with respect to the diaphragm, and securing said crystal unit in said frame utilizing said die means to accurately position the crystal unit with respect to the diaphragm.
4. The process of constructing an operative earphone subassembly havinga preformed-diaphragm, a preformed frame, and a preformed crystal unit; the steps of said process comprising; die cuttingsaid formed diaphragm, securing said frame to said diaphragm utilizing said cutting die to accurately position the frame with respect to the said diaphragm, and securing said crystal unit to said fram and to said diaphragm utilizing-said die to accurately position the crystal unit with respect to the said diaphragm.
5. In an insert earphone; a case adapted to be mounted.within the ear of a wearer, a non-conductive terminal bar within and supported by said case, an electromechanical transducer unit including lead means sup orted in said case with the said lead means engaging the terminal bar,
cable means extending into said case, terminal clip means connected to said cable means and adapted to slidably engage said lead means and said terminal bar, and means for causing said terminal clip means to slide into closer engagement with the said terminal bar as said cable means is pulled from outside of the said case.
6. In a piezoelectric insert earphone, a case adapted to be mounted within the ear of a wearer, a terminal bar positioned within and supported by said case, a piezoelectric unit including a lead means positioned in said case and said lead means engaging said terminal bar, cable means extending into said case, terminal contact clip means connected to said cable means and adapted to slidably engage said terminal bar and said lead means, and snubber means engaging said cable means between the terminal contact clip means and the point where the said cable means extends through the said case into the said enclosure.
7. A cable connection for an encased piezoelectricunit having a Rochelle salt crystal unit with lead means connected thereto comprising, in combination, a terminal bar in engagement with said lead means, terminal contact clip means adapted to slidably engage the said terminal bar to estabiish' an electrical connection with said lead means, cable means connected to said terminal contact clip-and adapted when subject to a pull to cause-said contact clip to more firmly engage said terminal bar.
8. An insert type of earphone, comprising in combination, a piezoelectric crystal unit having leads adapted to connect said unit in an electrical transmission path; a conical diaphragm having an ofl-center apex, a drive pin connected to said crystal unit and connected to said oil-center apex of said diaphragm; a case enclosing said crystal unit, said diaphragm, and said'drive pm; said case including a soft flexible portion adapted to fit against the ear of the wearer; and guard means positioned between the soft portion of the case and the diaphragm to protect the diaphragm.
9. In an earphone, a mounting member having a body portion conforming substantially to the.
portion and a second end portion adapted to engage the sides of the ear canal, said snout having a cross-sectional thickness progressively decreasing from said first end portion to said second end portion, and a telephone receiver connected to said body portion.
10; In an earphone, a case which is rounded .j atafirstlargeendportionandroundedatasec ond smaller end portion and which'has side partionsioiningthe'firstlargerendportionwithths of, a transducer mounted within said case and in- ,o
eluding lead means extending through said case to the outside thereof, said lead means being anchored'to said disk whereby a pull on said lead means from outside of said case causes said disk to slide toward the smaller end portion-of said case and wedge between the said side portions thereof. 11. In an insert type of earphone; electromechanical transducer means for connection in an electrical transmission path, diaphragm means including a drive pin connected to said transducer 15 means, a case enclosing said transducer means and said diaphragm means and including a soft flexible portion adapted to flt against the ear' of the wearer, and guard means connected to said case and positioned between the soft portion of 20 said disk tends to slide toward the smaller end portion of said case and wedges between the side i 7 portions thereof and said terminal clip means the case and the diaphragm to protect the said diaphragm. f
12. The invention as set forth in claim 11 further characterized in this, that said guard means extends substantially entirely across one face of 25 said case and has a plurality of small holes therethrough for permitting transmission of sound v pressure from said diaphragm into the soft flexi ble portion which fits into a wearer's ear.
13. In an earph0ne,'a case which is rounded at a first end portion, and rounded at a second smaller end portion and which has side portions joining the first end portion with the smaller end portion to form a generally tapering case adapted to be. mounted within the ear of a wearer, a disk of a size slightly smaller'than the first end portion and larger than said smaller end portion slidably mounted in the larger end portion thereof and having a snubber post mounted on one face thereof, an-electrically non-conductive terminal bar within and supported by said case, an electromechanical transducer unit including lead means supported in said case with the said lead means engaging the terminal bar, cable means extending into said case around said snubber means and having terminal clip means connected on the end thereof and adapted to slidably engage said lead.
means and said terminal bar 'whereby upon said cable means being pulled away from said case slide into closer engagement with said terminal of all tensional strain.
HARRY B. SHAPIRO. WALTER J. BROWN.