METHOD AND DEVICES FOR MAKING ELECTRO-ACOUSTIC TRANSDUCER APPARATUS

Abstract: The method of making the diaphragm (28) includes pressing on the front face of a film (11) at spaced apart areas to deform it progressively into a series of closely-spaced generally U-shaped projections (P). A manufacturing device presses the sides of the projections inwardly to rigidify them. The transducer magnet assembly (75) includes a series of elongated magnet pole-piece strips (76, 77) which confine magnets and are arranged in parallel spaced-apart rows with the ends thereof into transverse elongated grooves (91) extending within a pair of elongated cross-piece end members. The driver is fixed together in a precise manner by flowing an adhesive material into the grooves (91), and then by allowing such material to harden.

Description: Description *έii2d_and_Devicea_for_Ma ing Electro-acouatic_Tranaducer_ABEaratus_ Tβchnical_Field_ The preaent invention relatea in general to a method and devicea for making electro-acouatic tranaducer apparatus, and it more particularly relates to auch a method and devicea to facilitate modern, high-apeed maaa production of electro-acouatic tranaducer apparatus having a aubatantially flat, planar diaphragm. In both co-pending U.S. Patents, Serial No. 389,423 filed June 17, 1982, now U.S. Patent 4,491,698, and Serial No. 503,947, filed October 13, 1983, there ia diacloaed a new and improved electro-acouatic tranaducer having a generally flat or planar face compoaed of a film material configured with a aeries of spaced-apart projections bearing magnet means. It would be highly deβirable to have a proceas and manu acturing devices for constructing auch diaphragms from film material according to modern high speed production techniques. In this regard, auch a process ahould be capable of producing on a continuous basis, the diaphragms in a highly effective, reliable and efficient manner. The resulting tranaducer diaphragms include a aeriea of very closely apaced projections bearing magnetic means for co-acting electro-acouatically with a tranaducer diaphragm magnet aβse bly. The projections must fit in substantially perfect registry within a series of closely- spaced gaps or openings of the magnet atructure of the driver, to move freely therewithin. The resulting projections must be made in a precise, equally apaced apart manner, and yet be produced at a high rate of speed according to modern aaa production techniques. If they should be made in anything less than a highly accurate manner, the resulting projections would not properly register within, and extend into the closely spaced magnet atructure of the transducer driver, and move freely therewithin in an uninhibited operation. Additionally, it would be highly deairable to have a method of making a new and improved tranaducer driver, which can be preciaely and accurately made to accommodate the projections of the aforesaid diaphragm. Such a new driver must also be made according to modern, efficient production techniques. 5iSSiQSϋ£§_2 _l!lΣSΣltJ.2Q_ Therefore, it is the principal object of the present invention to provide a new and improved method and manufacturing devices for making a transducer apparatus according to modern high speed manufacturing techniques. Another object of the present invention is to provide such a new and improved transducer diaphragm driver and a method of manufacturing it, in an efficient and effective manner. Briefly, in accordance with the present invention, the above and further objects and features of the present invention are realized by providing a method and manufacturing devices for making an electro-acouatic tranaducer apparatus according to an efficient and reliable manufacturing process. The method of making the diaphragm includes pressing on the front face of a film at apaced apart areas to deform it progressively into a series of closely-spaced generally U-shaped projections. A manufacturing device preβses the sides of the projections inwardly to rigidif them. The transducer magnet assembly includes a aeries elongated magnet pole-piece strips which confine magnets and are arranged in parallel spaced-apart rows with the ends thereof fitted into transverse elongated groovea extending within a pair of elongated cross-piece end members. The driver is fixed together in a precise manner by flowing an adhesive material into the grooves, and then by allowing such material to harden. In a preferred embodiment, the diaphragm is made fr a blank, which includes the sheet of insulating film material, preferably having a pair of identical conducto patterns printed on its opposite sides. The pattern is commonly called a "Greek pattern", wherein the conductor move back and forth in relatively long, straight, spaced parallel lines, their ends being joined by relatively short, straight transverse lines which are perpendicular to the long lines, thereby completing a Greek or serpentine pattern. The method of making the transducers allows them to be produced continuously at a suitable production rate, and yet maintain precise tolerances, relative to both spacing of the projectiona on the diaphragm and the thickness dimension of the projections. Similarly, the method of making the magnet assembly enables the interva between the gaps formed by the pole piece strips to be maintained precisely in a highly reliable and efficient manner. l£A§£_5§§2ϊ!iE*:A2?-:_25-!._5ϊ-3yiπ9§_ The above-mentioned and other objects and features o this invention and the manner of attaining them will become apparent, and the invention itself will be beat understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein: Fig. 1 is a flow chart diagram illustrating the method of making a transducer diaphragm according to the present invention; Fig. 2 is a partially schematic, fragmentary perspective view of the projection forming device used according to the method illustrated in Fig. 1, and constructed according to the present invention; Fig. 3 is a schematic view of an elevational view of the manufacturing devicea uaad according to the method illustrated in Fig. 1; Fig. 4 is an elevational view of a diaphragm projection being acted upon by a pinch forming manufacturing device constructed according to the present invention; Fig. 5 is an elevational, sectional reduced-scale view of a diaphragm projection after the side rigidifying pinches are formed therein; Fig. 6 la a pictorial, fragmentary view of a transducer driver in the proceaa of being assembled according to the method of the present invention; Fig. 7 is a sectional elevation view of the driver of Fig. β, shown in a reduced scale, in the completed state; Fig. 8 is a fragmentary, pictorial view of another projection forming device used according to the method illustrated in Fig. 1, and constructed according to the present invention, the device being illustrated in an intermediate closed position; Fig. SA is a similar view of the device of Fig. 8, illustrating it in a fully open position in preparation or the projection forming operation; Fig. 8B is a similar view of the device of Fig. 8, illustrating it in a fully closed position at the completion of the projection forming operation; Fig. 8C is an enlarged detail view of the tip portion of a projection being formed, shown in Fig. 8; Fig. 9 is a partially schematic side elevational view of a further projection forming device operating according to the method of the present Invention illustrated in Fig. 1, and constructed according to the present invention; Fig. 10 is a partially schematic front elevational sectional view of the device of Fig. 9 taken substantially on line 10-10 thereof; Fig. 11 is a schematic front elevational sectional view of the device of Fig. 9 taken substantially on line 11-11 thereof; Fig. 12 is a partly schematic face view of a film blank of the diaphragm of Fig. 2, prior to its final folding, illustrating the blank with a portion thereof broken away to show the conductors being shown schematically as lines for illustration purposes; and Fig. 13 is a preferred wiring pattern for the inventive diaphragm. Best_ gde_for_Carrj£ing_Out_the_.In ention_ Referring now to the drawings, and more particularly to Figa. 1-3, there ia shown a flow diagram of a manufacturing method 10, which is carried out according to the present invention, for making electro-acoustic transducer diaphragms,such as the diaphragm shown schematically in Fig. 3. The diaphragms are described more fully in the aforementioned co-pending U.S. patent applications. The diaphragma are formed from a blank stock 11 composed of suitable thermoformable film material, such as the materials disclosed in the aforementioned patent applications. The continuous web of blank stock 11 has disposed thereon a aeriea of individual conductors 11A (Fig. 2) and 11B (Figs. 4 and 5) on opposite sides thereof. The conductors are deposited on the film blank atock 11 according to conventional printed circuit techniques. The arrangement and placement of the conductors is described in greater detail in the aforementioned co-pending patent applications. As indicated in Fig. 1, and s.a shown in Figs. 2 and 3,the blank stock 11 is moved continuously along a horizontal path of travel, and la heated, as indicated at 12 (Fig. 1) at a heating station 12A (Fig. 3). After heating the blank atock to a suitable temperature, the blank stock is moved to a projection forming station generally indicated at 13 (Fig. 3), where a series of closely spaced, parallel, generally U-shaped projections P, are formed by means of a projection forming manufacturing device 23 with the conductor patterns positioned at both the inside and the outside of the tip portions thereof. As indicated in Fig. 1 at 14, the projections P are formed tranaveraely to the path of travel of the blank stock 11, according to a continuous mode of operation. As indicated at 16 in Fig. 1, the next step in the process ia to anneal the formed blank atock 11 at an annealing station 17 as shown in Fig. 3. An annealing tank 15 contains a glycerine bath 15A which heats the formed blank 11 to a suitable annealing temperature. Thereafter, the annealed blank is cooled. According to an attaching step IS as indicated in Fig. 1, at an attaching station 19 aa shown in Fig. 3, a rigid backing sheet 21 is then affixed to the front of the annealed and formed blank stock, by any suitable technique, such as the application of a suitable adhesive, solvent, or by heat welding or the like. In thia manner, the rigid backing sheet 21 is affixed to the flat front (lower) surface of the formed blank stock to rigidify it, for maintaining the projections P substantially perpendicular to the flat backing sheet 21. Once the backing sheet is attached, the next step is to sever the completed diaphragm from the blank as indicated at 20 in Fig. 1. In this regard, a lower knife blade 22 co-acts with an upper reciprocating knife blade 24 to sever the formed portion of the stock from the remaining portion thereof. It will become apparent to those skilled in the art that other suitable cutting techniquea may alao be employed. Aa a result, a completed diaphragm auch aa the diaphragm 28 is separated from the main body of the stock. Referring now to Fig. 2, the film blank stock 11 includes a series of equally spaced-apart sprocket holes 33 arranged along one marginal edge thereof extending in the path of the atock. A seriea of equally apaced-apart sprocket holes 35 are aligned along the oppoaite marginal edge thereof, whereby a pair of aprocketa, auch as the sprocket 37 engaging the holes 33, drive the blank stock 11 along a horizontal path as indicated in Fig. 2. As shown in Fig. 2, at the projection forming atation 13, the device 23 includes a series of elongated apaced- apart tranaversely extending clamping bara 39 are moved continuously through a closed-loop path- for continuously engaging the upper surface of the blank stock 11 aa it moves horizontally from right to left, aa viewed in Fig. 2 of the drawings. The upper bars 39 move continuously through a closed-loop path of travel in a clockwise direction aa viewed in Fig. 1. Similarly, a aerieβ of lower elongated apaced-apart transversely extending clamping bara 42 move through a closed loop path in a counter-clockwise direction to engage the underside of the blank stock 11 as it moves leftwardly in Fig. 2 of the drawings. The upper and lower clamping bars engage the film atock on opposite facea thereof directly opposite one another. The upper bars 39 engage the areas of the blank atock 11 midway between pairs of groups of tranaveraely extending conductors, such as the conductors 44A and 44B. Similarly, like corresponding ones of the lower bars 42 engages the lower face of the blank atock 11 in positions directly opposite correaponding onea of the upper bar 39 and in synchronism therewith, to clamp the atock 11 in spaced-apart poβitiona as indicated in Figs. 2 and 3 of the drawings, aa the stock continues to move leftwardly . A series of spaced-apart knife blades 46 move with the lower bars 42 are interweaved therewith. In this manner, once the upper and lower clamping bars 39 and 42 engage opposite surfaces of the blank stock 11, the knife blades 46 move through a continuous closed-loop counter¬ clockwise path of travel and engage the lower face of the stock 11 in alignment with the transversely extending groups of conductors, auch aa the conductora 44B on the upper aur ace, to puah upwardly on the moving blank to form the projectiona P aa ahown in Fig. 3 of the drawings. In order to facilitate the formation of the projections P, the upper and lower pairs of clamping bars 39 and 42 move simultaneously toward one another to allow the lower knife blade 46 to urge the blank upwardly between the converging upper bars 39. As indicated in Fig. 3, the upper bars 39 are generally T-shaped in cross- section throughout their longitudinal lengths, and as pairs of the bars 39 move into close proximity to one another, they assume complimentary-shaped receaaea for receiving the formed projectiona therebetween. The lower bars are generally rectangular in cross-section throughout their lengths, and the knife blades 46 each has an upper rounded or otherwise contoured upper edge to form the inner surface of the tip portion of the projectiona P. The outer aurface of the tip portions are moved into engagement with the upper portions of the T-shaped pairs of clamping bars 39 to serve as a backing member to cooperate with the upwardly moving knife bladea. As shown in Fig. 3 of the drawings, once the knife blades 46 push sufficiently upwardly to form the projections P, they then remain in position during the heat treating step of the process. After heat treating and cooling, the knife blades 46 retract downwardly away from the blank stock 11. Also, in synchronism therewith, the lower clamping bara 46 alao move farther apart aa they travel through their cloaed- loop path downwardly away from the atock 11 in the counter-clockwise path of travel to enable the cycle of operation to be repeated continuously. Similarly, as the lower clamping bars 42 move away from the lower face of the blank stock 11, the upper -10- clamping bars 39 move upwardly away from the upper surface of the blank through their clockwise path of travel and then back to repeat the cycle of operation. As they move away from the blank, the bars 39 move apart to return to their original spacing in preparation for their downward decent onto the blank aa described previously. Suitable control mechanisms (not shown) ara provided to maintain the continuous synchronous movement of the clamping bara and knife blades, relative to the continuously moving blank stock. Referring now to Figs. 4 and 5 of the drawings, there is shown a pinch forming manufacturing device generally indicated at 48 for providing the projections, such aa the projection P of Fig. 4 with a pair of inwardly extending pinches or gussets 51 and 52 in a pair of parallel transversely extending legs 54 and 56 to rigidify them. In this regard, the two pinchea or guaaetβ 51 and 52, as shown in Fig. 5, cause the legs 54 and 56, to be fused together in selected spaced-apart areas as more fully described in the foregoing mentioned patent applications, to help maintain them in a perpendicular configuration, relative to the backing sheet to be attached to the formed sheet. In this manner, the projection P remains in a perpendicular confIgurβtion relative to the backing sheet, aa explained more fully in the aforementioned co-pending patent applications. The manufacturing device 48 comprises a pair of pinch forming units 58 and 61 disposed on opposite aidea of the projection P. The units 58 and 61 are generally similar to one another, and therefore only the unit 58 will be described in greater detail. -li ¬ lt ahould be understood that pairs of like units (not shown) are positioned on each side of each projection, so that the multiple pinches are formed in each one of the projectiona. Similar pinch forming devices (not shown) are positioned along the path of travel of the blank at a suitable poaitlon (not ahown) between the forming position 13, and the annealing position 17 to provide each one of the projections with the desired pinches. The unit 58 generally includes a pair of elongated by members 63 and 65 which are pivotally attached at thei upper ends at 67 to swing apart into engagement with adjacent projectiona. A pair of bulboua part* 69 and 72 project outwardly from the lower portions of the respective members 63 and 65. The bulbous part 72 swings rightwardly in the direction of the arrow into engagement with the left leg 54 to form the pinch 51. The part 69 swings simultaneously leftwardly into engagement with a right le (not ahown) of an adjacent projection (not shown) , to for a pinch therein. The units 58 and 61 are heated to facilitate the deformation of the legs of the projections to readily deform inwardly and to fuse them together. The parallel extending legs of each projection thus are deformed at selected locations inwardly until they engage one another and fuse together. In this manner, the legs are, at selected spaced-apart areas, then locked together to rigidify the structure of the projection P relative to th backing aheet. In this regard, once the blank atock 11 i then moved through the hot glycerine bath 15 (Fig. 3). The heated pinched portions are then cooled to form a rigid configuration. Referring now to Fig. 12, there ia ahown a film blank 234, which ia similar to the blank 11 of Fig. 2, and which is formed generally of any suitable high temperature group of thermoplastic blend material. The preferred material ia polyaulfone, such as the polyaul one sold under the trademark "UDEL" by Union Carbide of Danbury, Connecticut. Other suitable compositions include "ULTEM" by General Exβctric Company; "POLYETHER SULFONE" (polyphenyl aulfone) , sold by Imperial Chemical Industries, and "RADEL" (polyphenyl aulfone) aold by Union Carbide. Also, suitable polycarbonates, auch aa "LEXAN" aold by General Electric Company, may be employed. Polyimideβ may also be employed. In general, the high temperature thermoplastic material ahould have a relatively high glass transition temperature point, as well aa a relatively high heat deflection temperature. In this regard, the sheet 234A is annealed and formed to the desired shape. In order to maintain the desired shape, during high temperature operation and even in elevated ambient temperatures, which can occur when the loudspeaker is employed in a closed vehicle parked in the sun, the annealing temperature should be preferably in the range of about 300 degrees F. and 375 degrees F., and preferably about 330 degrees F. when the polyaulfone "UDEL" is employed. However, it is to be understood that the materials having lower annealing temperaturea may alao be employed satisfactorily, but the foregoing temperature range is preferred as well aa highter temperatures for other materials. The sheet has a thickness of about 3 Mils., and the conductors are about 1 Mil. in thickneas. Thβ sheet 234A includes a conductor pattern, generally indicated at 267, deposited on the front side of the sheet 234A. This pattern electrically interconnects a pair of terminals 263 and 265. A mirror-image of the conductor pattern, generally indicated at 267A, is deposited on the reverse side of the sheet 234A and is diapoaed oppoaite and in registration with, the conductor pattern 234 on the front aide thereof. In thia manner, the aheet 234A haa a greater tendency to lie flat and not be warped, thereby greatly facilitating the folding thereof into the desired shape, as well as facilitating the storage of the blanks. After being folded along the longitudinal conductors, into the shape as shown in Figs. 4 and 5, the folded sheet 234A assumes the desired shape, with little or no bowing from end to end. It haa been found that if the two conductor patterns are not disposed in registration with one another, the folded sheet becomes bowed from end to end, or it otherwise becomes warped. The conductor patterns 234 and 234A are connected electrically together, in parallel. In thia regard, the terminals 263 and 265 of the pattern 234 and corresponding terminals (not shown) of the pattern 234A on the reverse side of the sheet 234A are connected electrically. Aa ahown in Fig. 12, a terminal wire 263A ia soldered to the terminal 263 and ita corresponding terminal on the reverse side of the sheet 234A, since the solder and the distal end of the wire 263A or an eyelet (not shown) extend through a hole in the aheet 234A. Similarly, a terminal wire 265A is connected electrically to the terminal 265 and to the corresponding terminal of the conductor pattern 267A. The conductor pattern 267 (Fig. 12) is a replicated Greek pattern which includes a transverse portion 269 integrally connected electrically at one of its ends to the terminal 263. At ita other end, transverse conductor 269 connects to the longitudinal conductor 241, which in turn, ia connected integrally to an outer tranaveraely extending portion 272. A longitudinal portion 274 extenda from the transverse portion 272 to a transverse portion 276. Thus, the portions 241, 272 and 274 comprise a U- shaped portion of the pattern. Similarly, a longitudinal portion 278 extenda between the transverse portion 276 and another transversely extending portion 281, to complete a U-ahaped configuration, comprised of portions 274, 276 and 278. A longitudinal portion 283 extenda between the tranaverae portion 281 and another tranaverae portion 285 to cauae the portiona 278, 281 and 283 to aaaume a U-ahaped configuration. A longitudinal portion 287 integrally connects the transverse portion 285 and a longer transverse portion 289, which integrally connects to a longitudinal portion 292 diapoβed near the marginal edge thereof. A tranaverae portion 294 interconnecta the conductor portion 292 and the longitudinal intermediate conductor portion 240. The portiona 283, 285 and 287 alao assume a U-shaped configuration. The conductor portion 240 interconnecta transverse portion 294 with another transverse portion 298. The portion 298 extends parallel to the portion 272, which in turn ia disposed between the portion 298 and the transverse longer portion 289. A longitudinal portion 401 extenda between the tranaverae portion 298 and a tranaverae portion 403. The portion 401 extenda parallel to the portion 274, and the portion 403 extenda parallel to the portion 276. A longitudinal portion 405 connects the portion 403 and a transverse portion 407 which, in turn, is disposed parallel to the portion 281. A longitudinal portion 409, is disposed parallel to the portion 283 and connects the portion 407 and a transverse portion 412. The portion 409 extends parallel to the portion 283 and the portion 412 extends parallel to the portion 285. A longitudinal portion 414 extenda parallel to the portion 287, and interconnecta the portion 412 and a ahort tranaverae portion 416. A longitudinal portion 418 connects the portion 416 and a long transverse portion 421. The portion 418 is disposed near the left margin edge of the blank 234. The portion 421 extends parallel to the bottom marginal edge thereof. The longitudinal conductor 239 ia connected between the long tranaveraely extending portion 421 and a short transversely extending portion 423. A longitudinal portion 424 extends parallel to the portion 401 and interconnects the portion 423 and a transverse portion 426. Similarly, a longitudinal portion 428 extenda parallel to the portion 426 and another transverse portion 431. A longitudinal portion 433 extenda between the portion 431 and a tranaverae portion 435. A longitudinal portion 437 interconnects the portion 435 and a ahort connecting portion 439, which terminates at the terminal 265. For convenience of expression, the outside conductors 418, 421, 292 and 289 are herein called "return" conductors and the conductors within the Greek or serpentine pattern conductors 239-241, 272, 298, 423. . .285, 412, 435, 287, 414, 437 are called the "active" conductora. The active conductora form the voice coil in the magnetic gaps and the return conductors complete the voice coil circuit. It haa been found that auperior reaulta are produced when a particular type of pattern ia uaed to make the Inventive diaphragm and that the beat of this type of pattern is shown in Fig. 13, which gives the best mechanical balance to the diaphragm. In general, there should be an odd-number of longitudinal groups 300-308 of conductors in the Greek or serpentine pattern itaelf. Thia way, one pattern 304 ia on a center projection P, and an equal number of longitudinal patterns are on the outboard sides opposite the center. The two transverse adjacent groups 310, 312 and outboard groups 314, 316 are equally offset on opposite ends of the diaphragm and opposing sides of the center projection P carrying group 304. Each of the five longitudinal groups (300-308) has an odd number of apaced parallel conductors. As seen in Figs. 3, 4, and 5, this odd number places at leaat one conductor on the bottom and βeveral directly oppoaite each other on the aides of the diaphragm fold which forma projection P. The opposite ends of the voice coil appear at terminals 318, 320 (Fig. 13) which are exactly diagonally opposed to each other. A lightweight, braided, very flexible copper wire is connected to each of theβe terminala in any suitable manner, auch aa by aolder, for example. When making thia connection, care ia taken to maintain the balance along thia diagonal, with reapect to the center of gravity and to keep the connection aa light as possible. It will be observed that it is necessary to return to. the start of the Greek or serpentine pattern after each complete loop of a voice coil conductor through all longitudinal and transverse groups. For example, if a single path is traced from terminal 318 through the groups 300-316, it will be found that the path ends at 322. Therefore, a return conductor extending along the perimeter of the pattern takes the path back to 324 where it again entera into the Greek or aerpentine pattern. Likewise, if the pattern is traced, the conductor from terminal 320 emerges from the Greek or serpentine pattern at 326. From there, another return conductor extending around the perimeter of the pattern takea the path back to 328 where it reenters the pattern. It ia important to note that the return conductors are at locations where they do not enter the magnetic gaps. There are an odd number of return paths forming each of the groups 330, 332. These two groups "collide" at points 334, 336. The conductor extending between points 334, 336 forms the common center conductor of the longitudinal and transverse groups 300-316. While this principle may be applied to make any suitable size of a diaphragm, a substantially improved reault haa been found when the exact pattern ahown in Fig. 10 ia followed. The width to length ratio of the outaide of the entire pattern, including the return conductora, is approximately 2:1. In one embodiment which was built and teβted, with excellent reβults, the pattern was 4-3/4 inches wide and 9-inchea long. The exact ratio of thia pattern (9 divided by 4.75) ia 1:1.895. In thia same embodiment, which was built and tested, the film was 3- mils thick, each of the conductors was 30-thousandths of an inch wide, and the space between conductors and within the groups was 10-thousandths of an inch wide. A technique, similar to that used to make printed circuit boards, ia uβed to conatruct the diaphragm film. Since thia technique involvea an etching of material which undercuta the conductive material, an "etch factor" ahould be added to the apacing of the conductora on a mask used to make the diaphragm. The aheet of film supporting this conductor pattern is folded in the exact centers of the longitudinal groupβ ao that the center conductor of each of theae groupa ia in the bottoms of the projections P Csee Fig. 2) . Mirror image of the pattern is made on the opposite aide of the aheet of film, again by a uae of known techniquea used to make double aided printed circuit boards. The pattern is printed, in exact back-to-back register, on the opposite sides of the sheet of film so that, if the sheet is held up to the light, only one pattern is seen. Suitable connections may be made through or around the film so that the conductors forming the patterns on the opposite sides of the sheet are connected in parallel. The parallel connection ia normally preferred aince the reaiatance of the voice coil ia effectively reduced by substantially 50 by doubling the conductive path. However, the two patterns could also be connected in series. Impedance matching is important when the length of wirea connecting a loudapeaker, for example, into a circuit, becomea aignificant. Thua, aometimea it may be possible to match impedance merely by selecting between making aeries and parallel connectlona of the patterna printed on the opposite aides of the aheet. Although it ia moat convenient to uae the printed circuit approach to make the inventive diaphragm, other manufacturing techniques may also be used in special circumstances. For example, extremely large diaphragms may be made by stamping the conductive pattern from foil, and then bonding the resulting pattern of foil onto the sheet of plastic material. Or, an implantation process may be used to form conductive atripa in extremely small diaphragms. In some cases, wires may be used to form the conductive patterns. When wires are used, a coating ia added to bond the wires and film or other supporting substrate into a solid mass. Referring now to Figs. 6 and 7 of the drawings, there is shown an electro-acoustic transducer magnet assembly 75, which is constructed according to the present invention, and which is adapted to interact electro- magnetically with a tranaducer diaphragm made by the process of Fig. 1. As shown in broken lines in Fig. 6, a diaphragm 78, constructed according to the method of the present invention, is suspended within an opening (not shown) in a front driver frame aa ahown in broken linea at 83, for attachment to a auitable apeaker encloaure (not ahown) . The projections, such as the projection P of the diaphragm 78, fit within spaces, auch as the space or gap 85 shown in Fig. 7, between a series of parallel, spaced- apart elongated steel pole piece atripa, such aa the strips 76 and 77. A aeriea of permanent magnets, auch aa the permanent magnets 79-82 (Fig. 6), are disposed or sandwiched tightly between the pole piece strips. In thia regard, the permanent magnets are in the form of blocks, and are arranged in a spaced-apart manner, between a pair of pole piece strips, such as the magnets 79 and 80 positioned between the adjacent strips 76 and 77. A pair of complementary-shaped elongated end bars 86 and & each include oppositely-disposed elongated grooves 91 and 93 for receiving the ends of the pole piece strips. As shown in Fig. 6, a block 98 composed of hardened epoxy material fills the grove 91 in the end bar 86 to fix the ends of the pole piece strips in place in a critically-aligned spaced-apart manner, to the end bar 86 in a perpendicular configuration relative thereto. Considering now the method of construction of the magnet assembly unit in accordance with the present invention, as shown in Fig. 6, the pole piece strips and magnets are critically-aligned in the desired position and are held in place within the end bars, by suitable means (not shown), such as fixtures and/or adheaiveβ. Thereafter, the entire assembly is raised into an upright attitude at a position of about 45 degrees relative to the horizontal. Once the unit is disposed aa ahown in Fig. 6, epoxy is deposited via supply tube 96 which has its exit end 95 disposed slightly above the groove 93 in the end bar &S . it will become apparent to those skilled in the art that other techniques may also be used for supplying epoxy to the grooves. In this regard, with the assembly disposed in the attitude aa ahown, the groove 93 ia opened upwardly. Once in place, the epoxy material 94 ia delivered to the elongated groove 93. In thia manner, the material 94 flows into the groove 93 to fill it and, thus to imbed or flow around the lower ends of the strips in the epoxy material. The material 94 is then allowed to harden to form an epoxy block, which is similar to the block 98. In order to receive an adequate quantity of epoxy material to rigidly aecure and imbed the atrip enda, the end bars, such as the end bar 88, includea an inwardly extending projection or lip, auch aa the projection 99, defining the lower portion of the groove 93 of the bar 88. In this manner, when the unit is disposed in the approximate 45 degree attitude as ahown, the level L (Fig. 6) can rise sufficiently high to cover over and imbed the atrip ends in proper position. Since the elongated grooves are provided in the end bars, the pole piece strip ends need not fit precisely therewithin -- only a loose tolerance fit is required. Thus, only gross tolerances need be observed, and hence the cost of manufacturing the driver assembly is reduced, as compared to the situation where a close fitting tolerance would otherwise be required. Also, should subsequent design modifications require different sizes or shapea of pole piece atripa, the aame end bars can be employed. For example, if thicker or thinner strips are required for a certain application, the same end bars may still be employed for such application. After reviewing the foregoing, it will become apparent to those skilled in the art that, in place of an elongated groove, a series of wide grooves (not shown) may be provided for individually and loosely receiving the ends the strips. Each such wide groove would be substantially wider than the thickness of the strips, and in this manner, a smaller quantity of epoxy would be employed. Referring now to Fig. 8, 8A, 8B and &C, there ia ahown another diaphragm projection forming manufacturing device 100, which ia alao conatructed according to the present invention, and which forms a aeries of projections, such as the projection P shown in solid lines in Fig. 8B and in broken lines In Fig. 8, which illustrates the projection in the proceaa of being formed, from a aheet 101 of blank atock compoaed of similar film material aa the blank atock of Figa. 2 and 3. The device 100 can be uaed in place of the device 23 of Fig. 2 and 3, to form the diaphragm projectiona according to the method of Fig. 1. The device 100 generally comprises a aeriea of pairs of 10 parallel, spaced-apart upper clamping bars, such aa the upper clamping bara 103 and 104, for engaging with their bottom surfaces the upper surface of the blank stock material when it is disposed in an initial flat, substantially horizontal disposition, as indicated in Fig. 8A, which shows the device 100 in preparation for the formation of the projection P. Similarly, a series of pairs of parallel, spaced-apart lower clamping bars, such as the lower clamping bars 105 and 107, engage the blank stock 101 on its bottom surface and directly below the upper bars to press the stock tightly and releasably therebetween. In order to mount the clamping bars in a transversely moveable manner, each one of the upper clamping bars is rollably suspended from an upper track 109. Likewise, each one of the lower clamping bars is rollably mounted from below in a lower track 110. In this manner, the clamping bars are adapted to slide toward one another during the projection forming process, as indicated by the arrows in Fig. 8. A control linkage 112 is pivotally attached to a vertically disposed knife bar 113, which is disposed mid¬ way between the pair of clamping bars. The knife is positioned below the stock 101 to push upwardly on it from below, to form the projection P. It ahould be understood that there ia a similar control linkage (not shown) pivotally mounted on the opposite end of the knife bar 113, and pivotally attached to the other ends of the clamping bars 105 and 107 in a similar manner as the linkage 112. The control linkages, auch aa the linkage 112 causes the knife bar 113 to be maintained in the proper centrally-disposed position relative to the clamping bars, during the projection forming operation. An upper backing bar 115 is vertically reciprocatively mounted above the blank 101 directly opposite the knife bar 113. The function of the backing bar 115 ia to cauae the uppermoat conductor 116 to be crimped or creaaed during the projection forming operation. In thia regard, as the knife blade 113 pushes upwardly on the blank 101, it ia firβt moved into firm engagement with the concave groove on the bottom edge of the upper backing bar 115, which aubaequently retracts in unison with the upward movement of the knife blade. In ao doing, aa best seen in Fig. 8C, conductors 116 and 116A on opposite sides of the tip portion of the projection P, the conductors 116 and 116A become crimped or creaaed simultaneously, aince they are compoaed of a thin, soft metal, such as aluminum. In this manner, the conductors 116 and 116A do not tend to de-laminate from the blank 101, which becomes formed by action of the lower knife blade 113, and the backing bar aa a result of the operation of the device 100. In order to facilitate the crimping operation, the upper edge 113A is rounded and engages the inner conductor 116A. Similarly, the bottom edge 115A of the bar 115 engages the outer conductor 116. Thus, the device 100 forms tranaveraely extending projectiona in the stock in a similar manner as device 23. However, the device 100 can be used on cut sheets of the stock, instead of a continuous web of stock as shown in Figs. 2 and 3 for use with the device 23. In this regard, the diaphragms can be formed by the device 100, either singly, or in multiple numbers that can be subsequently severed apart. In operation, the sheet of the blank 101 is first clamped securely between the pairs of upper and lower clamping bars, which move through a rectilinear path of travel toward the blank. It ia underatood that there are other auch paira of clamping bara (not ahown) , each being aligned as described in connection with the device 23. Thereafter, the paira of oppoaed clamping bara move together in unison with and in synchronism with the upwardly moving knife bar 113 to form the projection P. Just prior to the converging sideward movement of the paira of bara, the backing bar 115 and the knife bar 113 move rectilinearly toward one another to clamp the conductors 116 and 116A and the blank therebetween. Thereafter, the knife bar is then moved upwardly forcibly by means (not ahown) to puah the backing bar upwardly and, at the same time, pull the clamping bars together by means of the linkage 112. In this manner, the projection P is formed as shown in Fig. 8B, and the conductora 116 and 116A are crimped longitudinally simultaneously therewith. In thia manner, the projectiona are formed in a gentle, non-abraaive manner to avoid damaging the conductors. It should be noted that the upper clamping bars 103 and 104 are generally T-shaped in a similar manner aa the upper bara of the device of Fig. 1, to form a complementary shaped recess for the projection P, when the blank ia disposed as indicated in broken lines at 101. The bara 103 and 104 do not come into contact with one another in their closed position, because the knife bar and the blank are disposed therebetween. After the projection P is formed, the pair of opposed clamping bars are retracted away from the blank to permit the formed blank to be removed from the device 100, and thereafter to be reset. In order to support the clamping bara rollably on the tracka 109 and 110, each block includea a pair of wheela or rollers, auch as the wheels 117 and 119, on the bar 103. In thi3 manner, the blocks are rollably supported by the tracks. Considering now the control linkage in greater detail with reference to Fig. 8, the linkage 112 generally comprises a pair of lower links 122 and 124, which are attached pivotally at their upper enda to the respective pivot points 126 and 128 on their respective bars 105 and 107. The lower ends of the links 122 and 124 are pivotally connected together at a reciprocatively rectllinearly alideable pivot point 129, along a vertically diapoaed elongated alot or groove 131 in one side edge of the knife bar 113. A pair of upper links 132 and 134 are pivotally attached at their lower ends to the respective pivot points 126 and 128. The upper enda of the links 132 and 134 are pivotally attached together at an upper pivot point 136, which ia fixed to the upper end portion of the knife blade 113 vertically above the lower alideable pivot point 129. It will become apparent to those skilled in the art that the orientation of the components of the device 100, can be varied. For example, the knife bar can be oriented above the blank and press downwardly on it, against the backing bar, which would be disposed below the blank. Referring now to Figs. 9, 10 and 11, there ia shown a projection forming manufacturing device 141, which is also constructed in accordance with the preaent invention, and which also enables diaphragm projections to be formed in a continuous-web blank stock 142 according to the method illustrated in Fig. 1. In thia regard, the device 141 could be uaed in place of the device 23 of Figa. 2 and 3. Aa ahown in Fig. 9, the devicel41 generally compriaea a series of longitudinally spaced-apart rowa of rollera, such aa the upper row of rollers 143 and 145. Similarly, below the web of blank atock 142, there ia diapoaed a aeriea of rowa of longitudinally apaced-apart upper rows of rollers, auch aa the lower rowa 147 and 149, diapoaed below correaponding ones of the upper rowa of rollers, auch aa the respective upper rollers 143 and 145. As best seen in Figs. 10 and 11 of the drawings, each row of upper and lower rollers comprise a aeriea of transversely spaced-apart rollers, and the lower rollers are each interleaved with the upper rollers. The lower rollers are diapoaed progressively upwardly relative to the upper rollers in the direction of travel of the blank atock, to cause the formation of the desired projections, by causing the lower rollers to press the blank atock upwardly between pairs of the upper rollers. Aa shown in Fig. 10, the blank stock is fed between the upper and lower rollers and the projections have only commenced to be formed. In Fig. 11, the final rollers have completed the formation of the projectiona. Considering now the upper rollers 143 as shown in Fig. 10, the upper rollers 143 include a series of spaced-apart rollers 152. There is one more upper roller than the number of projectiona to be formed. In the present example, five projections are formed, therefore there are six upper rollers provided, and there is one lower roller for each projection. In thia regard, the projectiona are formed in the spacea between the aix upper rollers. A common axle 156 extends transversely above the blank stock 142 for rollably supporting the upper rollers. The lower rollers are mounted on the axle 160 below the blank in a spaced-apart manner. Referring now to Fig. 11, the upper rollers 145 are mounted in a spaced-apart manner on a common axle 163 above the blank atock 142. The set of lower spaced-apart rollers 164 are mounted on a lower common axle 166 below the blank stock. The lower rollers are interleaved with the upper rollers, and are positioned in close proximity to the roller 163 to form the projections P in the blank stock 101. While particular embodiments of the present invention have been disclosed, it is to be understood that various different modifications are possible and are contemplated within the true spirit and scope of the appended claima. For example, various different types and kinds of materials can be employed for the various parts, such as the bars and rollers for the mechanisms described previously. There is no intention, therefore, of limitations to the exact abstract or disclosure herein presented.

Claims: Claims 1. A method of making a transducer diaphragm comprising: using a generally flat atock having a conductive meana arranged on at least one face thereof with a series of parallel apaced-apart portiona; preaaing on aaid film on the front face thereof at spaced-apart areas to deform it progressively into a series of substantially U-shaped projections disposed between said areaa, each projection having at leaat one of aaid portiona of aaid conductive means on the tip portion thereof; and causing said projections to move into close proximity to one another in a parallel manner as said projectiona are being formed. 2. A method according to claim 1, wherein aaid puahing includea guiding said film transversely into a group of spaced-apart forming rollers arranged with said groupa being apaced apart in the transverse direction of movement of said stock, the rollers of each group being apaced closer together in the direction of movement. 3. A method according to claim 1, wherein said pressing includes moving spaced-apart first members into engagement with the front face of said stock and positioning spaced-apart second members on the rear face of said atock ataggered relative to aaid first members to be interleaved therewith. -3θ- 4. A method according to claim 2, further including moving said atock along a path of travel and forming aaid projections aa the atock movea along aaid path. 5. A method according to claim 3, wherein aaid aembera are moved into engagement with aaid atock tranaverβely to the path of travel thereof. 6. A method according to claim 3, further including moving a third aet of members into engagement with said front face of aaid stock opposite the first-mentioned members on the said rear face to clamp aaid film therebetween. 7. A method according to claim 6, further including moving pairs of said first bars together aa said second bars move rearwardly therebetween to form the projections therebetween. 8. A method of making a transducer assembly for co- acting electromagnetically with a diaphragm having projectiona thereon, comprising: aaae bling a aet of elongated magnet pole-piece strips in parallel spaced-apart rows, with the ends thereof being disposed with elongated grooves within a pair of elongated end membera; flowing a hardenable material into aaid grooveβ; and cauaing aaid material to harden into a block. 9. A method according to claim 8, further including uaing strips having undercuta to define aaid groovea, securing the strips and the members in place in a critical alignment, and disposing the secured strips and members in an angular upright disposition to facilitate said flowing of material. 10. An tranaducer aaae bly for co-acting electromagnetically with a diaphragm having projectiona thereon, conatructed by the method according to claim 8. 11. A device for facilitating the making of a tranaducer diaphragm, having projections thereon, comprising: a pair of first and second members pivotally connected together at their upper enda; and the lower enda of aaid membera having a pair of inwardly facing die parts for pressing into engagement with said projections. 12. Apparatus for forming a transducer diaphragm, comprising: a aeries of spaced apart first bara for engaging the front side of a stock to be formed into said diaphragm; a aeriea of aecond bara for engaging the opposite side of said stock interleaved with said first bars; meana for tranaveraely movably mounting aaid bars and blades; and meana for coordinating the upward movement of the blades with the sideward movement of the first bara. 13. In an electro-acoustic tranaducer diaphragm conductor meana comprising: a conductor at leaat partially arranged in a Greek pattern having an odd number of groups of longitudinal conductor portiona, with return conductor portions extending along the perimeter of said pattern to complete a conductive path, whereby the weight of the conductor is uniformly distributed about the geometrical center of said conductor. 14. Conductor meana according to claim 13, wherein aaid pattern la a replicated Greek pattern having an odd number of replicationa. 15. Conductor means according to claim 14, wherein said return conductor portions being arranged with an odd number of aaid return conductora on each aide of aaid pattern. 16. Conductor meana according to claim 15, wherein the opposite ends of said conductor terminate at a pair of electrical terminals disposed in a spaced-apart manner, said terminals being equally spaced from the geometrical center of said conductor and being arranged on an imaginary line extending through said geometrical center. 17. Conductor means according to claim 16, wherein the groupa of aaid odd number of return conductora on each aide of aaid pattern collide or merge at the central conductor portion of the outer groups of said longitudinal conductor portions.

Inventors: LARSON DAVID A
Applicants: LFF & ASS
Application year: 1985
Main classification: H04R31
IPC codes: H04R9, H04R31