Speaker

Abstract: A speaker comprising: an edge member which includes a plurality of peripheral pieces and a plurality of connecting portions for connecting neighboring ones of the pieces; the neighboring ones of the pieces having cross-sectional shapes symmetric with respect to each other in an axial direction of the edge member, while each of the connecting portions has a cross-sectional shape changing gradually continuously; a diaphragm which is secured to an inner periphery or an outer periphery of the edge member; and a frame which is secured to an outer periphery or an inner periphery of the edge member.

Description: The present invention relates to a speaker, namely a loud speaker, comprising a frame, a diaphragm and an edge member supporting the diaphragm at the frame. Such speakers are generally known. In a known speaker, a cone-shaped diaphragm is attached to a distal end of a voice coil bobbin and a damper is fixed to an outer periphery of the voice coil bobbin. An edge member is provided at an outer peripheral portion of the cone-shaped diaphragm, while the voice coil is held in a magnetic gap of a magnetic circuit. In the known speaker of the above described arrangement, when an electrical signal is applied to the voice coil, a driving force produced in the voice coil is transmitted to the voice coil bobbin so as to vibrate the cone-shaped diaphragm secured to the distal end of the voice coil bobbin. The cone-shaped diaphragm is supported by the damper fixed to the outer periphery of the voice coil bobbin and the edge member. Linearity of a supporting force of the damper and the edge member which support the cone-shaped diaphragm poses a problem especially at the time of reproduction in low-pitched zone and forms a main cause of production of harmonic distortion. In order to improve linearity of the supporting force of the support members, various shapes have been proposed. As a result, an edge member which is formed into a rolled shape having a semicircular cross section is used most popularly at present. By combining this edge member with a damper having a corrugated cross section, linearity of the supporting force of the support members has been improved substantially. Fig. 23 shows vibration states of the rolled edge member. In Fig. 23, reference numeral 7 denotes the cone-shaped diaphragm, reference numeral 9 denotes the rolled edge member and reference numeral 10 denotes a frame to which an outer periphery of the edge member 9 is secured. In Fig. 23, character A represents a neutral vibration state prior to application of an electrical signal to the voice coil, in which the rolled edge member 9 is disposed at a neutral point, character B represents a forward vibration state in which the rolled edge member 9 is forwardly vibrated through an amplitude I from the neutral point and character C represents a rearward vibration state in which the rolled edge member 9 is rearwardly vibrated through the amplitude I from the neutral point. Since the rolled edge member 9 is vibrated through the amplitude I forwardly and rearwardly from the neutral point in the forward and rearward vibration states B and C, respectively as described above, motion of the edge member 9 acting as the support member for the cone-shaped diaphragm 7 does not include a non-linear component. In Fig. 23, when the rolled edge member 9 is vibrated from the neutral vibration state A to the forward vibration state B, the edge member 9 vibrating together with the cone-shaped diaphragm 7 displaces a quantity U1 of air. Meanwhile, when the rolled edge member 9 is vibrated from the neutral vibration state A to the rearward vibration state C, the rolled edge member 9 displaces a quantity U2 of air. Since rolled shape of the rolled edge member 9 is deformed between the forward and rearward vibration states B and C, the quantities U1 and U2 of air become different from each other. Sound pressure characteristics of the speaker is proportional to a sum of a quantity of air displaced by the cone-shaped diaphragm 7 and a quantity of air displaced by the edge member 9. However, in the known speaker, since the quantities U1 and U2 of air displaced by the edge member 9 in the forward and rearward vibrations become different from each other as described above, secondary harmonic distortion is likely to be generated at the time of reproduction in low-pitched zone. From GB-A-2 055 528 a diaphragm support of an electroacoustic transducer is known in which an annular diaphragm is supported by a pair of outer and inner edge members supporting the diaphragm from both sides in an axial sense. The edge members have sets of pleats arranged continuously along the circumferential directions of the diaphragm but directed in opposite directions to each other. It is an object of the present invention to provide a speaker including an edge member for supporting a diaphragm, in which secondary harmonic distortion of sound pressure characteristics is reduced greatly without deterioration of linearity of a supporting force of the edge member. In order to achieve the above and further objects, in accordance with a first aspect of the present invention, there is provided a speaker comprising a frame, a diaphragm and an edge member supporting the diaphragm at the frame, characterized by the edge member including an even number of peripheral pieces and an even number of connecting portions each connecting two neighboring ones of the peripheral pieces; the neighboring ones of the peripheral pieces having, in peripheral direction of the edge member, cross-sectional shapes symmetric with respect to each other, while each of the connecting portions has, in the peripheral direction of the edge member a cross-sectional shape which, when considering cross-sections taken in the peripheral direction of the edge member and successively along points of a line extending from the one of the two neighboring peripheral pieces it connects to the other of the two neighboring peripheral pieces it connects, changes gradually continously from said cross-sectional shape of the one of the two neighboring peripheral pieces to said cross-sectional shape of the other one of the two neighboring peripheral pieces; the diaphragm being secured to an inner periphery of the edge member and the frame being secured to an outer periphery of the edge member, or the diaphragm being secured to an outer periphery of the edge member and the frame being secured to an inner periphery of the edge member. In accordance with a second aspect of the present invention, there is provided a speaker comprising a frame, a diaphragm and an edge member supporting the diaphragm at the frame, characterized by the edge member including a plurality of peripheral connecting portions each constituted by one convexly rolled piece and one concavely rolled piece such that at a boundary between neighboring ones of the connecting portions, a convexly rolled piece of one of the neighboring ones of the connecting portions confronts a corresponding convexly rolled piece of the other of the neighboring ones of the connecting portions; or a concavely rolled piece of one of the neighboring ones of the connecting portions confronts a corresponding concavely rolled piece of the other of the neighboring ones of the connecting portions; successive connecting portions each having alternatively in the peripheral direction of the edge member a cross-sectional shape which, when considering cross-sections taken in the peripheral direction of the edge member and successively along points of a line extending from one neighboring connecting portion to the other neighboring connecting portion, changes gradually continously from totally concave to totally convex or totally convex to totally concave; the diaphragm being secured to an inner periphery of the edge member and the frame being secured to an outer periphery of the edge member, or the diaphragm being secured to an outer periphery of the edge member and the frame being secured to an inner periphery of the edge member; wherein when the diaphragm is vibrated forwardly or rearwardly, a sum of quantities of air displaced by the convexly rolled piece and the concavely rolled piece of each of the connecting portions is set to a predetermined value at all forward and all rearward movements. In accordance with a third aspect of the present invention, there is provided a speaker comprising a frame, a diaphragm and a longish edge member supporting the diaphragm at the frame, characterized in that the longish edge member includes a plurality of peripheral pieces and a plurality of air shields each connecting two neighboring ones of the peripheral pieces such that, when considering the longitudinal direction of the edge member, one end of one of two neighboring peripheral pieces is connected by an air shield to one end of the other one of said two neighboring pripheral pieces, the successive peripheral pieces and air shields being arranged successively in the longitudinal direction of the edge member; the neighboring ones of the peripheral pieces have, in peripheral direction of the edge member, cross-sectional shapes symmetric with respect to each other; and the diaphragm is secured to an inner periphery of the edge member and the frame is secured to an outer periphery of the edge member, or the diaphragm is secured to an outer periphery of the edge member and the frame is secured to an inner periphery of the edge member. Advantageous embodiments of the present invention are definded in the dependent claims. By the above described arrangement of the speaker of the present invention, when the diaphragm is vibrated forwardly and rearwardly, a sum of quantities of air displaced by the neighboring pieces is set to a predetermined value. Therefore, in accordance with the present invention, secondary harmonic distortion of sound pressure characteristics, which would be caused by a difference between quantities of air displaced by the edge member in forward and rearward vibrations of the diaphragm, can be reduced greatly. Features of the present invention will become apparent from the following description taken in conjunction with the preferred embodiments thereof with reference to the accompanying drawings, in which: Fig. 1 is a top plan view of a speaker according to a first embodiment of the present invention; Fig. 2 is a sectional view taken along the line II-II in Fig. 1; Fig. 3 is an enlarged perspective view of a connecting portion of an edge member in the speaker of Fig. 1; Fig. 4 is a top plan view of the connecting portion of the edge member of Fig. 3; Figs. 5(a), 5(b), 5(c), 5(d) and 5(e) are sectional views taken along the lines A-A', B-B', C-C', D-D' and E-E' in Fig. 4, respectively; Fig. 6 is a top plan view of a connecting portion of an edge member in a speaker according to a second embodiment of the present invention; Figs. 7(a), 7(b), 7(c), 7(d) and 7(e) are sectional views taken along the lines A-A', B-B', C-C', D-D' and E-E' in Fig. 6, respectively; Fig. 8 is a top plan view of a speaker according to a third embodiment of the present invention; Fig. 9 is a sectional view taken along the line IX-IX in Fig. 8; Fig. 10 is a top plan view of a connecting portion of an edge member in the speaker of Fig. 8; Figs. 11(a), 11(b), 11(c), 11(d) and 11(e) are sectional views taken along the lines A-A', B-B', C-C', D-D' and E-E' in Fig. 10, respectively; Fig. 12 is a top plan view of a connecting portion of an edge member in a speaker according to a fourth embodiment of the present invention; Figs. 13(a), 13(b), 13(c), 13(d) and 13(e) are sectional views taken along the lines A-A', B-B', C-C', D-D' and E-E' in Fig. 12, respectively; Fig. 14 is a top plan view of a connecting portion of an edge member in a speaker according to a fifth embodiment of the present invention; Figs. 15(a), 15(b), 15(c), 15(d) and 15(e) are sectional views taken along the lines A-A', B-B', C-C', D-D' and E-E' in Fig. 14, respectively; Fig. 16 is a top plan view of a connecting portion of an edge member in a speaker according to a sixth embodiment of the present invention; Figs. 17(a), 17(b), 17(c), 17(d) and 17(e) are sectional views taken along the lines A-A', B-B', C-C', D-D' and E-E' in Fig. 16, respectively; Fig. 18 is a top plan view of a speaker according to a seventh embodiment of the present invention; Fig. 19 is a sectional view of the speaker of Fig. 18; Fig. 20 is a perspective view of a connecting portion of an edge member in the speaker of Fig. 18; Fig. 21 is a perspective view of a connecting portion of an edge member in a speaker according to an eighth embodiment of the present invention; Fig. 22 is a top plan view of a speaker according to a ninth embodiment of the present invention; and Fig. 23 is a view explanatory of vibration states of an edge member of a prior art speaker (already referred to). Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout several views of the accompanying drawings. Referring now to the drawings, there is shown in Figs. 1 to 5, a speaker K1 according to a first embodiment of the present invention. The speaker K1 includes a plate 1, a yoke 2 formed integrally with the plate 1, a magnet 3 fixed to the plate 1, a center pole 4 secured to an upper face of the magnet 3 , a voice coil 5 held in a magnetic gap defined between an outer periphery of the center pole 4 and an inner periphery of the yoke 2, a bobbin 6 for the voice coil 5, a cone-shaped diaphragm 7 attached to a distal end of the bobbin 6, an annular edge member 11 provided at an outer peripheral portion of the diaphragm 7 and a frame 10. The outer peripheral portions of the damper 8 and the edge member 11 are fixed to the frame 10. A magnetic circuit constituted by the plate 1, the yoke 2, the magnet 3 and the center pole 4 is retained by the frame 10. The edge member 11 is circumferentially divided into four pieces, namely, a convexly rolled piece 12, a concavely rolled piece 14, a convexly rolled piece 13 and a concavely rolled piece 15 sequentially such that the convexly rolled pieces 12 and 13 and the concavely rolled pieces 14 and 15 are arranged alternately. The edge member 11 has a connecting portion 16 for connecting the pieces 12 and 15, a connecting portion 17 for connecting the pieces 15 and 13, a connecting portion 18 for connecting the pieces 13 and 14 and a connecting portion 19 for connecting the pieces 14 and 12. Fig. 3 shows the connecting portion 17 of the edge member 11. The convexly rolled piece 13 and the concavely rolled piece 15 have, in peripheral direction of the edge member, cross-sectional shapes symmetric with respect to each other, and are connected by the connecting portion 17 whose cross-sectional shape gradually changes continuously. The connecting portion 17 is constituted by a convexly rolled cross section and a concavely rolled cross section. Shape of the connecting portion 17 is described in more detail with reference to Figs. 4 and 5. As shown in Fig. 5, the connecting portion 17 of the speaker K1 has various cross-sectional shapes along the lines A-A' to E-E' of Fig. 4, respectively. As a point on the connecting portion 17 comes closer to the convexly rolled piece 13, diameter of the convex roll of the connecting portion 17 becomes larger and diameter of the concave roll of the connecting portion 17 becomes smaller as shown in Fig. 5. At a location where the connecting portion 17 reaches the convexly rolled piece 13, diameter of the concave roll of the connecting portion 17 assumes zero and thus, the connecting portion 17 has a cross-sectional shape identical with that of the convexly rolled piece 13. On the contrary, as a point on the connecting portion 17 comes closer to the concavely rolled piece 15, diameter of the concave roll of the connecting portion 17 becomes larger and diameter of the convex roll of the connecting portion 17 becomes smaller. At a location where the connecting portion 17 reaches the concavely rolled piece 15, diameter of the convex roll of the connecting portion 17 assumes zero and thus, the connecting portion 17 has a cross-sectional shape identical with that of the concavely rolled piece 15. Hereinbelow, operation of the speaker K1 of the above described arrangement is described. When an electrical input signal is applied to the voice coil 5, the convexly rolled pieces 12 and 13 and the concavely rolled pieces 14 and 15 which are connected by the connecting portions 16 to 19 act as a support member for the cone-shaped diaphragm 7 without blocking forward and rearward vibrations of the cone-shaped diaphragm 7 and acoustically shield, together with the connecting portions 16 to 19, sound emitted from the back of the cone-shaped diaphragm 7. Initially, when the cone-shaped diaphragm 7 has been vibrated forwardly, the convexly rolled pieces 12 and 13 assume a forward vibration state B of a rolled edge member 9 of a known speaker of Fig. 25 and thus, displace a quantity U1 of air. On the other hand, the concavely rolled pieces 14 and 15 assume a forward vibration state which is obtained by forwardly inverting a rearward vibration state C of Fig. 25 and thus, displace a quantity U2 of air. Subsequently, when the cone-shaped diaphragm 7 has been vibrated rearwardly, the convexly rolled pieces 12 and 13 assume the rearward vibration state C of Fig. 25 and thus, displace the quantity U2 of air. Meanwhile, the concavely rolled pieces 14 and 15 assume a rearward vibration state which is obtained by rearwardly inverting the forward vibration state B and thus, displace the quantity U1 of air. Namely, in forward and rearward vibrations of the cone-shaped diaphragm 7, a sum of quantities of air displaced by the convexly rolled piece 13 and the concavely rolled piece 15 connected by the connecting portion 17 amounts to a predetermined value of (U1+U2) at all times. The same exactly applies to the convexly rolled piece 12 and the concavely rolled piece 15 connected by the connecting portion 16, the convexly rolled piece 13 and the concavely rolled piece 14 connected by the connecting portion 18 and the convexly rolled piece 12 and the concavely rolled piece 14 connected by the connecting portion 19. Meanwhile, the edge member 11 shown in Figs. 4 and 5 of the speaker K1 may also be modified to an edge member 11a of a speaker K2 according to a second embodiment of the present invention as shown in Figs. 6 and 7. In the edge member 11a, the connecting portion 17 of the speaker K1 is replaced by a connecting portion 34 and thus, the convexly rolled piece 13 and the concavely rolled piece 15 are connected by the connecting portion 34. As shown in Fig. 7, the connecting portion 34 of the speaker K2 has various cross-sectional shapes along the lines A-A' to E-E' of Fig. 6, respectively. The speakers K1 and K2 include the edge member, the diaphragm secured to the inner periphery of the edge member and the frame attached to the outer periphery of the edge member. The edge member is circumferentially divided into a plurality of the pieces, while neighboring ones of the pieces have, in peripheral direction of the edge member, cross-sectional shapes symmetric with respect to each other, and are connected by the connecting portions whose cross-sectional shapes change gradually continuously. Thus, in the speakers K1 and K2, the sum of quantities of air displaced by the neighboring pieces of the edge member respectively in both, their forward and rearward vibrations, is set to the predetermined value at each connecting portion. Therefore, in accordance with the first and second embodiments of the present invention, secondary harmonic distortion of sound pressure characteristics, which has been caused by difference between quantities of air displaced by the edge member in its forward and rearward vibrations in the known speakers, can be reduced greatly and thus, it becomes possible to provide a speaker having low distortion. Figs. 8 to 11 show a speaker K3 according to a third embodiment of the present invention. The speaker K3 includes an edge member 11b. Since other constructions of the speaker K3 are similar to those of the speaker K1, only the edge member 11b is described for the sake of brevity, hereinbelow. The edge member 11b includes convexly rolled pieces 20 and 21 and concavely rolled pieces 22 and 23. In the same manner as in the speaker K1, the convexly rolled pieces 20 and 21 have, in peripheral direction of the edge member, a cross-sectional shape symmetric with respect to that of the concavely rolled pieces 22 and 23 and are connected with the concavely rolled pieces 22 and 23 by connecting portions 24, 25, 26 and 27 whose cross-sectional shapes change gradually continuously. By way of example, only the connecting portion 25 and its neighborhood are described with reference to Figs. 10 and 11. In Fig. 10, the convexly rolled piece 21 and the concavely rolled piece 23 are connected by the connecting portion 25. As shown in Fig. 11, the connecting portion 25 of the speaker K3 has various cross-sectional shapes along the lines A-A' to E-E' of Fig. 10, respectively. As is apparent from Figs. 10 and 11(d), the cross-sectional shape of the connecting portion 25 is constituted by opposite convex rolls and one central concave roll interposed between the convex rolls in the radial direction of the edge member 11b. As shown in Fig. 11, as a point on the connecting portion 25 comes closer to the convexly rolled piece 21, diameter of the convex rolls of the connecting portion 25 becomes larger and diameter of the concave roll of the connecting portion 25 becomes smaller. At a location where the connecting portion 25 reaches the convexly rolled piece 21, diameter of the concave roll of the connecting portion 25 assumes zero and thus, the connecting portion 25 has a cross-sectional shape identical with that of the convexly rolled piece 21. On the contrary, as a point on the connecting portion 25 comes closer to the concavely rolled piece 23, diameter of the concave roll of the connecting portion 25 becomes larger and diameter of the convex rolls of the connecting portion becomes smaller. At a location where the connecting portion 25 reaches the concavely rolled piece 23, diameter of the convex rolls assumes zero and thus, the connecting portion 25 has a cross-sectional shape identical with that of the convexly rolled piece 23. Since operation and effects of the speaker K3 are the same as those of the speaker K1, description thereof is abbreviated for the sake of brevity. Meanwhile, the edge member 11b shown in Figs. 10 and 11 of the speaker K3 may also be modified to an edge member 11c of a speaker K4 according to a fourth embodiment of the present invention as shown in Figs. 12 and 13. In the edge member 11c, the connecting portion 25 of the speaker K3 is replaced by a connecting portion 35 and thus, the convexly rolled piece 21 and the concavely rolled piece 23 are connected by the connecting portion 35. As shown in Fig. 13, the connecting portion 35 of the speaker K4 has various cross-sectional shapes along the lines A-A' to E-E' of Fig. 12, respectively. As will be seen from Figs. 12 and 13(c), the cross-sectional shape of the connecting portion 35 is constituted by opposite concave rolls and one central convex roll interposed between the concave rolls in the radial direction of the edge member 11c. The speakers K1 to K4 have four connecting portions. However, in the speakers K1 to K4, it can also be so arranged that any arbitrary even number (≥2) of the connecting portions are provided such that a sum of quantities displaced by one convexly rolled piece and its adjacent concavely rolled piece connected by each connecting portion are set to the predetermined value in forward and rearward vibrations of the cone-shaped diaphragm. As a result, the same effects of the speaker K1 to K4 can be obtained. Furthermore, based on this technical idea, a speaker K5 according to a fifth embodiment of the present invention includes an edge member 11d as shown in Figs. 14 and 15, while a speaker K6 according to a sixth embodiment of the present invention includes an edge member 11e as shown in Figs. 16 and 17. Each of the edge members 11d and 11e is constituted by only a plurality of convexly rolled and concavely rolled connecting portions arranged circumferentially alternately. As shown in Fig. 15, the connecting portions of the speaker K5 have various cross-sectional shapes along the lines A-A' to E-E' in Fig. 14, respectively. As shown in Fig. 17, the connecting portions of the speaker K6 have various cross-sectional shapes along the lines A-A' to E-E' in Fig. 16, respectively. Thus, the edge member 11d includes convexly rolled connecting portions 28 to 30 and concavely rolled connecting portions 31 to 33, while the edge member 11e includes convexly rolled connecting portions 36 to 38 and concavely rolled connecting portions 39 to 41. Meanwhile, the connecting portions of the edge member 11d of the speaker K5 may also be combined with those of the edge member 11e of the speaker K6. Furthermore, the edge member may also be formed by properly combining the connecting portions of the speakers K1 and K2. In addition, the edge member may also be formed by properly combining the connecting portions of the speakers K3 and K4. Meanwhile, in the speakers K1 to K6, the maximum width of the roll of the connecting portions is not necessarily required to be equal to the width of the edge member by employing an arrangement in which a flat portion is provided at one or opposite radial ends of the roll of the connecting portions. Figs. 18 to 20 show a speaker K7 according to a seventh embodiment of the present invention. The speaker K7 includes an edge member 11f. Since other construction of the speaker K7 are similar to those of the speaker K1, only the edge member 11f is described for the sake of brevity, hereinbelow. The edge member 11f includes convexly rolled pieces 43 and 44, concavely rolled pieces 45 and 46 and cylindrical air shields 47, 48, 49 and 50 made of foamed material. The convexly rolled pieces 43 and 44 are connected with the concavely rolled pieces 45 and 46 by the air shields 47 to 50. As shown in Fig. 20, the convexly rolled piece 43 and the concavely rolled piece 46 have cross-sectional shapes, in the peripheral direction of the edge member, which are symmetric with respect to each other, and are connected with each other by the air shield 47. Operation of the speaker K7 of the above described arrangement is described, hereinbelow. When an electrical input is applied to the voice coil 5 on the supposition that the air shields 47 to 50 are made of, for example, flexible material such as urethane rubber, the convexly rolled pieces 43 and 44 and the concavely rolled pieces 45 and 46 act as a support member for the cone-shaped diaphragm 7 without blocking forward and rearward vibrations of the cone-shaped diaphragm 7, while the air shields 47 to 50 acoustically shield sound emitted from the back of the cone-shaped diaphragm 7. Therefore, in forward and rearward vibrations of the cone-shaped diaphragm 7, a sum of quantities displaced by the convexly rolled piece 43 and the concavely rolled piece 46 connected by the connecting portion 47 is set to the predetermined value of (U1+U2) in the same manner as in the speaker K1. Fig. 21 shows an edge member 11g of a speaker K8 according to an eighth embodiment of the present invention. In Fig. 21, a convexly rolled piece 51 and a concavely rolled piece 52 are connected with each other by an air shield 53. The air shield 53 is formed by a hollow hemispherical film. Since other constructions of the speaker K8 are similar to those of the speaker K7, description thereof is abbreviated for the sake of brevity. Fig. 22 shows a speaker K9 according to a ninth embodiment of the present invention. The speaker K9 includes a square diaphragm 54, a square edge member 11h having a square opening surrounding the diaphragm 54 and a frame 63. The square edge member 11h includes a pair of opposed convexly rolled pieces 55 and 56, another pair of opposed concavely rolled pieces 57 and 58 and air shields 59, 60, 61 and 62 made of foamed material. The air shields 59 to 62 are, respectively, provided at four corners of the square edge member 11h so as to connect the convexly rolled pieces 55 and 56 with the concavely rolled pieces 57 and 58. Therefore, the edge member 11h acts as a support member for the diaphragm 54 without blocking forward and rearward vibrations of the diaphragm 54. For forward and rearward vibrations of the diaphragm 54, a sum of quantities displaced by, for example, the convexly rolled piece 55 and the concavely rolled piece 57 connected by the connecting portion 59 is set to the predetermined value of (U1+U2) in the same manner as in the speaker K1.

Claims: A speaker (K1-K4) comprising a frame (10), a diaphragm (7) and an edge member (11) supporting the diaphragm at the frame, characterized by the edge member (11) including an even number of peripheral pieces (12-15) and an even number of connecting portions (16-19) each connecting two neighboring ones of the peripheral pieces (12-15); the neighboring ones of the peripheral pieces (12-15) having, in peripheral direction of the edge member (11), cross-sectional shapes symmetric with respect to each other, while each of the connecting portions (16-19) has, in the peripheral direction of the edge member (11) a cross-sectional shape which, when considering cross-sections taken in the peripheral direction of the edge member (11) and successively along points of a line extending from the one of the two neighboring peripheral pieces it connects to the other of the two neighboring peripheral pieces it connects, changes gradually continously from said cross-sectional shape of the one of the two neighboring peripheral pieces to said cross-sectional shape of the other one of the two neighboring peripheral pieces; the diaphragm (7) being secured to an inner periphery of the edge member (11) and the frame (10) being secured to an outer periphery of the edge member (11), or the diaphragm (7) being secured to an outer periphery of the edge member (11) and the frame (10) being secured to an inner periphery of the edge member (11). A speaker (K1, K2) as claimed in Claim 1, wherein the peripheral pieces (12-15) include a convexly rolled piece (12, 13) and a concavely rolled piece (14, 15), while said cross-sectional shape of each of the connecting portions (16-19) is constituted by one convex roll and one concave roll, wherein as a point on each of the connecting portions (16-19) comes closer to the convexly rolled piece (12, 13), diameter of the convex roll of each of the connecting portions (16-19) becomes larger, while diameter of the concave roll of each of the connecting portions (16-19) becomes smaller and assumes, at a location where each of the connecting portions (16-19) reaches the convexly rolled piece (12, 13), zero such that said cross-sectional shape of each of the connecting portions (16-19) becomes identical with that of the convexly rolled piece (12, 13), wherein as a point on each of the connecting portions (16-19) comes closer to the concavely rolled piece (14, 15), diameter of the concave roll of each of the connecting portions (16-19) becomes larger, while diameter of the convex roll of each of the connecting portions (16-19) becomes smaller and assumes, at a location where each of the connecting portions (16-19) reaches the concavely rolled piece (14, 15), zero such that said cross-sectional shape of each of the connecting portions (16-19) becomes identical with that of the concavely rolled piece (14,15). A speaker (K3) as claimed in Claim 1, wherein the peripheral pieces (20-23) include a convexly rolled piece (20, 21) and a concavely rolled piece (22, 23), while said cross-sectional shape of each of the connecting portions (24-27) is constituted by two convex rolls and one concave roll, wherein as a point on each of the connecting portions (24-27) comes closer to the convexly rolled piece (20, 21), diameter of the convex rolls of each of the connecting portions (24-27) becomes larger, while diameter of the concave roll of each of the connecting portions (24-27) becomes smaller and assumes, at a location where each of the connecting portions (24-27) reaches the convexly rolled piece (20,21), zero such that said cross-sectional shape of each of the connecting portions (24-27) becomes identical with that of the convexly rolled piece (20,21), wherein as a point on each of the connecting portions (24-27) comes closer to the concavely rolled piece (22, 23), diameter of the concave roll of each of the connecting portions (24-27) becomes larger, while diameter of the convex rolls of each of the connecting portions (24-27) becomes smaller and assumes, at a location where each of the connecting portions (24-27) reaches the concavely rolled piece (22, 23), zero such that said cross-sectional shape of each of the connecting portions (24-27) becomes identical with that of the concavely rolled piece (22, 23). A speaker (K4) as claimed in Claim 1, wherein the peripheral pieces (20-23) include a convexly rolled piece (20, 21) and a concavely rolled piece (22, 23), while said cross-sectional shape of each of the connecting portions (35) is constituted by one convex roll and two concave rolls, wherein as a point on each of the connecting portions (35) comes closer to the convexly rolled piece (20, 21), diameter of the convex roll of each of the connecting portions (35) becomes larger, while diameter of the concave rolls of each of the connecting portions (35) becomes smaller and assumes, at a location where each of the connecting portions (35) reaches the convexly rolled piece (20, 21), zero such that said cross-sectional shape of each of the connecting portions (35) becomes identical with that of the convexly rolled piece (20, 21), wherein as a point on each of the connecting portions (35) comes closer to the concavely rolled piece (22, 23), diameter of the concave rolls of each of the connecting portions (35) becomes larger, while diameter of the convex roll of each of the connecting portions (35) becomes smaller and assumes, at a location where each of the connecting portions (35) reaches the concavely rolled piece (22, 23), zero such that said cross-sectional shape of each of the connecting portions (35) becomes identical with that of the concavely rolled piece (22, 23). A speaker (K5, K6) comprising a frame (10), a diaphragm (7) and an edge member (11d, 11e) supporting the diaphragm at the frame, characterized by the edge member (11d, 11e) including a plurality of peripheral connecting portions (28, 31; 29, 32; 30, 33) each constituted by one convexly rolled piece (28-30) and one concavely rolled piece (31-33) such that at a boundary between neighboring ones (28, 31; 29, 32) of the connecting portions (28, 31; 29, 32; 30, 33), a convexly rolled piece (28) of one (28, 31) of the neighboring ones (28, 31; 29, 32) of the connecting portions (28, 31; 29, 32; 30, 33) confronts a corresponding convexly rolled piece (29) of the other (29, 32) of the neighboring ones (28, 31; 29, 32) of the connecting portions (28, 31; 29, 32; 30, 33); or a concavely rolled piece (32) of one (29, 32) of the neighboring ones (29, 32; 30, 33) of the connecting portions (28, 31; 29, 32; 30, 33) confronts a corresponding concavely rolled piece (33) of the other (30, 33) of the neighboring ones (29, 32; 30, 33) of the connecting portions (28, 31; 29, 32; 30, 33); successive connecting portions (28, 31; 29, 32; 30, 33) each having alternatively in the peripheral direction of the edge member (11d, 11e) a cross-sectional shape which, when considering cross-sections taken in the peripheral direction of the edge member (11d, 11e) and successively along points of a line extending from one neighboring connecting portion to the other neighboring connecting portion, changes gradually continously from totally concave to totally convex or totally convex to totally concave; the diaphragm (7) being secured to an inner periphery of the edge member (11d, 11e) and the frame (10) being secured to an outer periphery of the edge member (11d, 11e), or the diaphragm (7) being secured to an outer periphery of the edge member (11d, 11e) and the frame (10) being secured to an inner periphery of the edge member (11d, 11e); wherein when the diaphragm (7) is vibrated forwardly or rearwardly, a sum of quantities of air displaced by the convexly rolled piece (28-30) and the concavely rolled piece (31-33) of each of the connecting portions (28, 31; 29, 32; 30, 33) is set to a predetermined value at all forward and all rearward movements. A speaker (K7-K9) comprising a frame (10), a diaphragm (7; 54) and a longish edge member (11f-11h) supporting the diaphragm at the frame, characterized in that the longish edge member (11f-11h) includes a plurality of peripheral pieces (43-46; 51, 52; 55-58) and a plurality of air shields (47-50; 53; 59-62) each connecting two neighboring ones of the peripheral pieces (43-46; 51, 52; 55-58) such that, when considering the longitudinal direction of the edge member (11f-11h), one end of one of two neighboring peripheral pieces is connected by an air shield to one end of the other one of said two neighboring peripheral pieces, the successive peripheral pieces (43-46; 51, 52; 55-58) and air shields (47-50; 53; 59-62) being arranged successively in the longitudinal direction of the edge member (11f-11h); the neighboring ones of the peripheral pieces (43-46; 51, 52; 55-58) have, in peripheral direction of the edge member (11f-11h), cross-sectional shapes symmetric with respect to each other; and the diaphragm (7; 54) is secured to an inner periphery of the edge member (11f-11h) and the frame (10) is secured to an outer periphery of the edge member (11f-11h), or the diaphragm (7; 54) is secured to an outer periphery of the edge member (11f-11h) and the frame (10) is secured to an inner periphery of the edge member (11f-11). A speaker (K7-K9) as claimed in Claim 6, wherein the air shields (47-50) are made of foamed material such as urethane rubber. A speaker (K8) as claimed in Claim 6, wherein each of the air shields (53) has a hemispherical shape. A speaker (K9) as claimed in Claim 6, wherein the diaphragm (54) has a square shape and the edge member (11h) has a corresponding square shape, the peripheral pieces (55-58) of the edge member (11h) are constituted by a pair of first strips (55, 56) located on two sides of the square shaped diaphragm (54) opposed to each other and having a first cross-sectional shape in the peripheral direction of the edge member (11h), and a pair of second strips (57, 58) located on the other two sides of the square shaped diaphragm (54) opposed to each other and having a second cross-sectional shape in the peripheral direction of the edge member (11h) such that said first and second cross-sectional shapes are symmetric with respect to each other.

Inventors: HONDA KAZUKI, KOURA SATOSHI, SAIKI SHUJI, HONDA, KAZUKI, KOURA, SATOSHI, SAIKI, SHUJI
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1993
Main classification: H04R7
IPC codes: H04R7