GB2029628A - A method for transmission of audio signals and transmission media - Google Patents

Abstract

Audio signals are transmitted over lines (a) between at least half of which no dielectric exists (Figure 9), or (b) at least half of which are formed in the same pattern, on both sides of an insulating substrate. An audio cable may be either woven with at least two warp conductors 92, 93 and woof dielectric threads 91, or a metal spiral 41 with an outer fiber material and/or thermoplastic insulator 44 and two air-paced conductors 35, 36 within the metal spiral 41. <IMAGE>

Description

SPECIFICATION A method for transmission of audio signals and transmission media This invention relates to a method for transmission of audio signals and to transmission media, for example a cable cord, a wiring means and a printed circuit.

It has found that the covering, or the dielectric, of vinyl cords used in wiring various audio devices gives bad influence to the signals. In orderto transmit a signal, it is necessary to provide signal paths, or at least an outward signal path and a return signal path. The outward signal path and the return signal path are, in general, provided by a vinyl cord orthe like, located adjacent each other, and an electric field is created between the two signal paths.

The electric field thus created penetrates the dielectric of the covering of the cord, thus forming dielectric polarization therein. This dielectric polarization is aligned with the direction of the electric field. The reaction of the dielectric polarization motion, in turn, affects the electric field, as a result of which the signal is adversely affected. It is obvious that this influence is increased in proportion to the length of the signal paths.

It is therefore desirable that wiring is formed with a cord whose dielectric constant is as small as possible, especially when handling small electrical signals such as audio signals. However, as it is practically impossible to remove all of the dielectric material from the cable, effort has been made to dispense with the covering dielectric material. No construction in which the electrical conductive path is largely exposed to air has been proposed yet.

In view of foregoing, an object of this invention is to provide a novel method for transmission of audio signals.

Another object of this invention is to provide a cable cord, a wiring means, and a printed circuit which are not harmful for audio signals.

In order to achieve the object, according to the invention, wiring an audio device is performed in such a manner that no dielectric exists at least between the signal paths of channels thereof, or even if there exists dielectric, electrical conductive paths are formed in the same pattern on both surfaces of an insulating support.

Also, in order to achieve the object, a cable according to this invention comprises: an electrical conductive layer obtained by spirally winding a metal strip or a wire; a fiber material provided outside the electrical conductive layer and having elements continuous in the longitudinal direction of the electrical conductive layer and/or a thermoplastic insulator provided together with or outside the fiber material; and at least two electrically conductive paths which are supported in the space defined in the inside of said electrical conductive layer so as to be exposed to air as much as possible.

The principle, nature and utility of the invention will become more apparent from the following detailed description and the appended claim when read in conjunction with the accompanying drawing. Brief Description of the Drawing Figure lisa sectional view showing a cable according to this invention which is used to connect audio devices.

Figure 2 is an explanatory diagram showing a supporting plate assembly of the cable shown in Figure 1.

Figures 3 and 4 are explanatory diagrams showing essential components of one example of a cable according to this invention.

Figure 5 is sectional views showing modifications of a part of the components shown in Figure 4.

Figure 6 is a sectional view showing the example of the cable according to the invention.

Figures 7 and 8 are explanatory diagrams showing devices for manufacturing the cable in another aspect of this invention.

Figure 9 is a sectional view showing a cable including weaving body according to this invention.

Figure 10 is explanatory diagrams showing a cable strip of this invention.

Figure ills a sectional view showing a wiring cable according to the invention, which is applied to a tone arm.

Figure 12 is a sectional view of a tone arm pipe of Figure 11 to which the wiring cable of this invention may be inserted.

Figures 13 and 14 are explanatory diagrams showing wiring elements according to the invention which are used for wiring in a curcuit device.

Figure 15 is an explanatory diagram for a description of experiments from which this invention has been developed.

Figure 16 is also an explanatory diagram for a description of the principle of this invention.

The cable shown in Figure 1 can be used to connect audio devices such as an amplifier and a loudspeaker. In this case, the signal path consists of a flexible conduit 10 and a flexible conductor 11 arranged coaxially with the conduit 10. The diameter of the conduit 10 is from 5mm to several centimeters selected according to requirements. The conduit 10 may be a corrugated pipe as shown in Figure 1, or a metal plate wound spirally, or a plurality of metal rings connected to one another. That is, a variety of conduits may be employed as the pipe 10.

The conductor 11 in the conduit can be supported by a supporting plate assembly 12 as shown in Figure 2. It goes without saying that the supporting plate assembly 12 is made of insulating material.

The supporting plate assembly 12 is a series of substantially elliptic supporting plate elements 12a, 12b, 12c, and so forth which are connected to one another. These supporting plate elements are bent in zigzag form at the connections 12', and are then inserted into the pipe 10. The supporting plate elements 1 2a, 1 2b, 1 2c, and so forth have center holes A, B, C and so forth, respectively into which the conductor 11 is inserted. The supporting plate assembly should have at least two supporting plate elements. In this case, a plurality of supporting plate assemblies each consisting of two supporting plate elements can be arranged at certain intervals. In the supporting plate assembly shown in Figure 2, only one center hole is formed in each supporting plate element. However, sometimes it is necessary to provide more than one conductor in the conduit 10.

Accordingly, in such a case, the number of center holes in each supporting plate element is not always one. The method of supporting the conductor 11 is not limited to the above-described method. That is, the conductor 11 may be supported by a conventional method in which circular insulating plates are disposed at certain intervals, or a method in which the conductor is supported by thread-shaped insulators, or a method in which supporting plates various in configuration are employed.

The conduit 10 is closed by an end plate 13 made of insulating material at the end portion 1 Oa so that dust or the like enters the conduit. A connecting end portion 1 lea is protruded through the end plate 13.

This connecting end portion 1 1a may be an end portion of the conductor 11, or may be a part connected to the conductor 11. The configuration of the end portion 1 1a may be of a female type having a recess according to the configuration of the mating part.

If an elbow 20 is connected to the conduit 10, then the conduit 10 can be readily handled. Similarly as in the conduit 10, the elbow 20 is a metal pipe in which a conductor 21 is arranged coaxially. The conductor 21 is supported by end plates 22 and 23 at both ends 20a and 20b of the elbow 20. One end portion 21a of the portion of the conductor 21 has a recess which is fitted to the end portion 1 1a of the conduit 10. The other end portion 21b of the conductor 21 is so shaped as to match the terminal of the mating equipment. It goes without saying the end portions 21a and 21b of the conductor 21 may be of a male type or a female type according to the configuration of the mating part.

The outside diameter of the end portion 20a of the elbow 20 is equal to the inside diameter of the conduit 10 so that the end portion 20a can be tightly fitted into the conduit 10. The other end portion 20b of the elbow 20 is formed in the same way. The conduit 10 may be connected to the elbow with screws. Alternatively, if the conduit 10 and the elbow 20 are suitably threaded, the former can be screwed into the latter, or the former can be connected to the latter by means of an annular coupling element whose both end portions are threaded.

It may be convenient if a part of the end portion 20b of the elbow 20 is rotatable.

A second embodiment of the cable cord is shown in Figure 3.

Figure 3 shows a support 01 for electrically conductive paths. The support 01 supports conductors 35 and 36 which are the electrically conductive paths, The support 01 is made of an insulating material such as "Mylar" (Registered Trade Mark) or polyester, and has a main part 30 and tooth-shaped parts 31 and 32 (with respective suffix symbols a, b, C, and so forth) extended sideways from both sides of the main part 30. The tooth-shaped parts 31 and 32 are symmetrical with respect to the main part 30.

More specifically, the parts 31a and 32a, 31b and 32b, etc. are arranged symmetrically with respect to the main part 30, and the distance S between adjacent parts 31a and 31b and 31c, etc. and between the adjacent parts 32a and 32b and 32c, etc.

are equal to one another. However, it is not always necessary that they are symmetrical and are spaced the constant value S from one another. The distance S can be varied to the extent that the conductors 35 and 36 remain firmly supported. The distance between the end of the tooth-shaped part 31 and the end ofthetooth-shaped part 32 is largerthan the diameter of an outer cover 40 (described later) into which the support 01 is inserted. Each of the conductors 35 and 36 may be a single wire, or a stranded wire, or a metal strip; a suitable conductor material is acid free copper which is not covered with dielectric. Windows (holes) 33 are formed in the portions of the main part 30 which are on the lines connecting the tooth-shaped parts 31 and 32. The windows 33 are utilized as synchronizing means to distribute the wires in manufacturing the cable.It is desirable that the synchronizing means are provided at constant intervals with respect to the tooth shaped parts 31 and 32. Other suitable synchronizing means include protrusions or magnetic detection means such as a magnetic tape.

The conductors 35 and 36 are arranged in such a manner that they thread between the tooth-shaped parts 31 and 32 of the support 01 in zigzag fashion.

Figure 4 illustrates the aforementioned outer cover 40 into which the support 01 is inserted. As was described before, the inside diameter of the outer cover 40 is smaller than the width W of the support.

The outer cover 40 is cylindrical and comprises a first innermost layer 41 which is formed by spirally winding a metal strip or ribbon with a space between adjacent metal strips. This space is filled with a wire 42 (or a strip much thinner than the metal strip forming the first layer), so that adjacent strips are positively electrically connected. This is to prevent the first layer 41 from having reactance and to prevent variation of the resistance along the length of the cable.

The wire 42 can be brought into contact with the spiral layer 41 in accordance with various methods such as a method in which, as shown in Figure 5(a), the wire 41 is tightly inserted between the adjacent parts of the layer strip 41, a method in which, as shown in Figure 5(b), the upper or lower edges of the adjacent parts of the layer strip 41 are bridged by the wire 42, and a method in which, as shown in Figure 5(c), the edges of the adjacent parts of the layer strip 41 are tapered to receive the wire 42. In this case, all that is necessary is positively to connect the adjacent parts of the layer strip. As shown in Figure 5(d), the metal strip may be in staircase form as shown at 41', or a strip of tapered section.

In order that the cable can withstand tension applied in the longitudinal direction of the first layer 41, a second layer43 of threads or metal wires or the like are provided outside the first layer 41. The second layer 43 may be obtained by laying a plurality of threads or metal wires over the outer wall of the first layer 41 in the longitudinal direction, or the second layer 43 may be a cylindrical cloth or net-like cloth, In this case, the term "cloth or net-like cloth" is intended to mean cloth which is made of all kinds of materials such as cloth of fibers and metal cloth obtained by weaving metal wires etc. In the case where the metal cloth is employed as the second layer 43, the second layer 43 may serve as the wire 42 in the first layer.In this specification, thread-like, wire-like, and cloth-like materials as described above will hereinafter be referred to as "fiber materials".

A third covering layer 44 of thermoplastic insulating material is provided outside or together with the fiber material of the second layer 43. This third layer 44 may be provided after provisions of the second layer 43 or it may be provided together with the second layer 43. In the case where the third layer 44 is provided after the formation of the second layer 43, the third layer 44 is formed on the outside of the second layer 43. In the case where the third layer 44 is provided together with the formation of the second layer 43, the second layer 43 may be buried in the third layer 44. Since the third layer 44 is provided for improved appearance and electrical insulation, it is unnecessary to provide the third layer 44 if these properties are not required.

Figure 6 illustrates a sectional view of a cable which has been completed by inserting the support 01 shown in Figure 3 into the outer cover 40 shown in Figure 4. In Figure 6, those components which have been previously described with reference to Figures 3 and 4 have therefore been similarly numbered, and the fiber material 43 is thread.

The conductors 35 and 36 are supported in the outer cover 40 by alternately bending the toothshaped parts 31 and 32 of the support 01. In other words, as the width W of the support 01 is larger than the inside diameter of the outer cover 40, the conductors can be supported by bending the toothshaped parts 31 and 32 in such a manner that first the tooth-shaped parts 31a and 32a are bent left, then the succeeding tooth-shaped parts 31b and 32b are bent right, then the following tooth-shaped parts 31 c and 32c are bent left, and so on. In this case, as the elastic restoring forces of the tooth-shaped parts 31 and 32 cause the latter to abut against the inner wall of the outer cover 40 the support 01 is fixedly secured to the outer cover 40.Furthermore, as tension is given to the conductors 35 and 36 by alternately bending the tooth-shaped parts 31 and 32 and the conductors 35 and 36 are fixed to connectors (not shown) at the ends of the cable, the conductors 35 and 36 are fixedly secured by the support 01.

In the above-description, the number of conductors (core wires) is two. However, it goes without saying that the technical concept of the invention can be applied to a multicore cable in which the number of conductor is increased more by arranging a plurality of conductors in parallel or by modifying the configuration of the support 01 in such a manner that the tooth-shaped parts are extended radially (in three dimensions).

The support having the tooth-shaped parts has been described. However, any support can be used if it is so designed that the conductors are exposed to air as much as possible. For instance, the conductors may be embedded in a support which is obtained by foaming a dielectric material more than five times, for instance ten to twenty times, its ordinary foaming factor.

Now, a device for manufacturing the above described flexible multicore cable will be described.

Figure 7 shows a device 70 which is used to cause the support 01 to support the conductors 35 and 36 and to insert the conductors 35 and 36 thus sup ported into the outer cover. In this device, as shown in Figure 7, two gears 71 and 72 which engage each other, and two pulleys (only one 73 shown) disposed above these gears 71 and 72 for feeding wires are -provided.

The gears 71 and 72, and the pulley 73 can rotate around the respective axies 1 2 and t3. The gear 71 has first, second and third engaging parts 71a, 71b and 71c (the gear 72 is similarly formed) arranged in the direction of thickness at constant intervals. Since the-gears 71 and 72 are similar in construction to each other, only the gear 71 will be described. The first and second engaging parts 71a and 71b are provided near the two and faces 71 so and 71 S2 of the gear 71, and the third engaging part 71c is positioned near the center of the thickness of the gear 71.

The radius of the gear at the engaging part 71a is equal to that at the engaging part 71b, and the radius at the engaging part 71 c is larger than the radius at the engaging parts 71a and 71b. The gear71 is so arranged that the ends of the parts 71a, 7lb and 71c are at the left-hand side, as viewed in the figure, of the feeding points (designated by 35 and 36) of the wires 35 and 36. Similarly, the gear 72 is so arranged that the ends of the corresponding parts at the right hand side of the wire feeding points. The distance between the engaging parts 71 c of the gear 71 and the corresponding engaging part of the gear 72 is equal to the distance between the adjacent windows.

33 of the support 01.

The pulley 73 is positioned above the engaging parts of the gears 71 and 72 to feed the wire 35.

Similarly, the other pulley (not shown) is positioned below the engaging parts of the gears to feed the wire 36. The function of the other pulley is completeliy the same as that of the pulley 73.

The pulley 73 has a groove 74 cut along its periphery by which the conductor 35 from a conductor supplying source (not shown) is directed to the engaging parts of the gears 71 and 72.

A method of obtaining a conductor supporting structure with the gears 71 and 72 and the pulleys will be described. First, the support 01 is supplied between the gears 71 and 72. The distance between the engaging parts 71c and the corresponding part of the gear 72 is equal to the distance between the synchronizing means 33 of the support 01, and the size of the engaging parts is in correspondence to the size of the synchronizing means. The main part 10 of the support 01 is placed substantially directly below the conductor 35 by engaging the gears 71 and 72. In this case, the engaging part 71 c of the gear 71 is inserted into one window 33 of the support, while the corresponding engaging part of the gear 72 adjacent to the engaging part 71e depresses the support 01. Therefore, the support 01 is fixedly positioned. In this connection, as shown in the figure, the tooth-shaped parts (for instance, 31a and 32a) of the support 01 are bent left by the engaging parts 71a and 71b, whereupon the conductors 35 and 36 are inserted. Next, the central engaging part of the gear 72 is inserted into the following window 33 to position the support, while the tooth-shaped parts (for instance 31b and 32b) of the support 01 are bent right by the outer engaging parts of the gear 72, whereupon the insertion of the conductors 35 and 36 are carried out.

In the above-described manner, whenever the tooth-shaped parts 31 and 32 of the support 01 are bent right and left, the conductors 35 and 36 are inserted in the support 01, and finaliy the assembly of the conductors and the support as shown in Figure 3 can be obtained.

Figure 8 shows a device which, while manufacturing the outer cover 40, inserts the above-described assembly into the outer cover 40, thereby to provide the cable. As shown in Figure 8, the device is provided with a rotary body 80 consisting of a cylindrical part 81 and an opening part 82 extended, in the form of a cone, from one end of the cylindrical part 81. The device further comprises a covering material supplying device 85 which has a bore 86 whose diameter is slightly larger than the diameter ofthe cylindrical part 81 of the rotary body 80. The cylindrical part 81 of the rotary body 80 is inserted into the bore 86 of the covering material supplying device 85.

The metal strip 41 from a metal strip supplying device (not shown), the wire 42 from a wire sup plying device (not shown), and the fiber material 43 from a fiber material supplying device are supplied to the vicinity of the cylindrical part 81 of the rotary body 80.

The covering material supplying device- 85 has a supply passage 87 substantially perpendicular to the bore 86 so as to allow the molten thermoplastic material 44 to flow into the bore 86.

As the metal strip 41, the wire 42, the fiber material 43 and the thermoplastic material 44 are supplied with the rotation of the rotary body 80, the metal strip 41 and the wire 42 are spirally wound to form the first spiral layer, while the fiber material is laid on the spiral layer, and the thermoplastic material 44 is provided on the layer of fiber material. In this operation, the thermoplastic material is cooled and solidified while passing through the bore 86.

In addition, the device as shown in Figure 7 or a device for manufacturing a foamed body in which the conductors are embedded is provided in the vicinity of the opening part 82 of the rotary body 80, so that the support 01 (not shown) supporting the conductors iffed in synchronization with the speed of manufacturing the outer cover 40. The device for manufacturing the support supporting the conductors may be rotated with the rotary body 80, if necessary.

Thus, the cable having core conductors is continuously manufactured while passing through the bore.

In the above description, the wire 42 is supplied.

However, it goes without saying that in the case where the metal strip 41' as shown in Figure 5(d) is employed, it is unnecessary to supply the wire 42.

Furthermore, it is obvious that sometimes it is unnecessary to supply the thermoplastic material.

This kind of wire 90 is shown in Figure 9. Two conductors 92,93 are used as warps and are woven by woofs 91 of dielectric material (polypropylene, nylon, etc.). The conductors 92, 93 and woofs 91 together form a weaving body 90'.

The weaving body 90' is encircled by a spiral 94 of a spring wire or a metal strip. The spiral 94 and the weaving body 90' are wrapped with a metal knitting body 95 which is made of thin metal wires.

It is evident that only the weaving body 90' need be used when an electrical shield is not required.

Figures 10(a) and 10(b) illustrates two embodiments of this invention. More specifically, the first embodiment (Figure 10(a) ) is for one channel, and the second embodiment (Figure 10(b) ) isfortwo channels (as in a stereophonic device).

In the first embodiment of Figure 10(a), electrical conductive paths 101 and 102 are provided on an insulating substrate 100 made of, for instance, a vinyl chloride plate. Similarly, in the second embodiment of Figure 10(b), electrical conductive paths 101, 102,101' and 102' are provided on an insulating substrate 100 made of the same material as described above. These conductive paths 101,102,101' and 102' may be formed by chemical etching as in the case of printed circuit boards, or they may be electrically conductive material bonded to the substrate.

In Figure 10(a), if the conductive paths 101 and 102 are of the negative (-) side and the positive (+) side, respectively, then an electric field is formed as indicated by reference character E. The electric field E will never cross the dielectric on upper side of the substrate 100. Similarly, in Figure 10(b), if the conductive paths 101' and 102' are of the negative (-) side and the positive (+) side of the left channel, and the conductive paths 101' and 102' are of the negative (-) side and the positive (+) of the right channel, respectively, then electric fields are formed as indicated by reference characters E, and ER, respectively. Half of the electric fields will never cross the dielectric.

If the substrate 100 of such a cable has a suitable thickness, it can be readily inserted into a tone arm pipe, a microphone pipe, etc.

Shown in Figure 11 is one application of the cable thus formed. In this case, the cable is applied to the tone arm of a record player. A connector 111 for connecting a cartridge is provided at one end portion 1 10a of a tone arm pipe 110, and a counterweight (not shown) is provided at the other end portion 1 Ob. A pipe 116 serving as a rotary shaft is fixedly secured to the selected portion of the tone arm pipe 110.

In the connector 111 provided at the one end portion 1 Oa of the tone arm pipe 110, there are provided pins 113 held by a pin block 112. A head shell (not shown) connected to the cartridge is inserted into the connector 111 so as to be con nected to the pins 113 thereby to complete the electrical connection loop. The pin block 112 is supported by a spring 113a, and therefore the head shell is inserted into the connector 111 against the elastic force of the spring 11 3a and is held therein.

Accordingly, it will be understood that, when the head shell is inserted into the connector 111 or removed therefrom, the assembly of the block 112 and the pins 113 is moved longitudinally. Therefore, it is necessary to connect the pins 113 to the conductors 1 14a of the cable 114 whose end is brought near the read ends of the pins 113, with connecting wires 115 such as flexible bare metal wires or an ordinary vinyl cord.

A cable 117 is inserted into the pipe 116. This cable 117 is fabricated similarly as in the cable 114; however, it is different from the latter 114 in that the cable 117 is extended sideways at the two end portions 117a and 117b sothatthe cable is held ata suitable position in the pipe 116 and follows the rotation of the arm to some extent, that is, the two end portions 117a and 117b are in contact with the inner wall of the pipe 116, but the remaining portion is not in contact with the inner wall of the pipe 116. In other words, the cable 117 is so designed in configuration that there is suitably frictional resistance between the two end portions 117a and 117b and the inner wall of the pipe 116.

The conductors at the other end of the cable 114 are electrically connected to the conductors at the one 1 17a of the cable 117 with connecting wires 118 such as bare metal wires. Furthermore, pins in the terminal means 120 of the tone arm are also connected to the conductors at the other end 1 17b of the cable 117 with connecting wires 119 such as bare metal wires.

The use of the wiring cable as described above can remarkably improve the efficiency of manufacturing the tone arm and the signal transmission characteristics.

The case where a wiring cable according to the invention is employed for the tone arm has been described; however, it should be noted that the invention is not limited thereto or thereby. For example, the wiring cable may be applied to a microphone set with a support, or it may be used to make connection between audio devices, for instance between an amplifier and its loudspeaker, or it may be used to make connection between printed circuit boards in an amplifier, for instance between an equalizer section and a flat amplifier section.

In this embodiment of Figure 10, the tone arm pipe 110 may be constructed as follows desirably. Figure 12 is a sectional view of a tone arm pipe 110 on the inside wall of which a layer 1 OA of vibration absorbing material is formed. The vibration absorbing material is a material which is permeable and very low in elasticity, such as Motite or high molecular adhesive (trade name: Araldite). Such material permeates well into the metal of the tone arm pipe thereby to reinforce the rigidity of the pipe and to absorb the vibration of the pipe.

A method of manufacturing the tone arm pipe will be described with reference to Figure 12(b). First, a tube 1 10B (its outer diameter being substantially equal to the inside diameter of the pipe 110) made of a material such as cloth or paper high in impregnability is inserted into the pipe 10. Then, the molten Motite is allowed to flow into the pipe 110 from one end to the other. As a result, the Motite is impre gnated into the tube 1 10B and passed through the tube 1 OB and solidifed on the inner wall of the pipe 110, thus forming the layer 1 OA of vibration absorbing material. This method may be applied before or after the pipe is bent as desired.

Another embodiment of the invention is shown in Figure 12(C). In this case, the tone arm pipe is a dual pipe consisting of an outer pipe 110 and an inner pipe 110C. The above-described material which is permeable and very low in elasticity is allowed to flow between the inner pipe and the outer pipe, so as to fill the space between these pipes.

In the case where a wiring cable 100 is disposed in the dual pipe as shown in Figure 12(C), preferably the inner pipe 110C serves as a shield pipe so that the electric fields created by the current flowing in the signal paths of the wiring cable may not penetrate the material. The wiring cable 100 comprises signal paths LE and LR of the right channel and signal paths LE and LL of the left channel, which are formed by, for instance, photo-etching on a substrate made of, for instance, vinyl chloride. If the signal paths LE and LE are grounded electric fields ER and EL are created by the currents in the signal paths. When these electric fields ER and EL cross the above-described vibration absorbing material layer, dielectric polarization may be caused and may reversely affect the audio signal as well known in the art.However, this difficulty can be eliminated by the use of the inner pipe 1 10C because it serves as the shield pipe as was described above. Furthermore, the tone arm of this construction can be readily manufactured because the vibration absorbing material can be readily put in the space between the outer pipe and the inner pipe.

In this case also, the tone arm pipe may be filled with the vibration absorbing material even after it has been bent as desired.

Thus, an excellent tone arm substantially free of self-resonance can be manufactured according to this simple manufacturing method.

Figure 13 shows another embodiment of this invention. In the wiring element shown in Figure 13, portions of a substrate 50, where a circuit is to be formed, are removed by blanking, and conductors 51 and 52 are provided in the portions thus removed. In this case, the dielectric between the conductors 51 and 52 may be of the type which is low in dielectric loss, or no dielectric may be provided.

Alternatively, after the circuit of metal film has been formed on the substrate, the substrate may be removed except for the absolutely necessary portions thereof.

In the wiring element shown in Figure 14, a substrate 60 is made up of vertical bars 60a and horizontal bare 60b arranged in the form of a net having through holes 60c, and conductors 61 and 62 are provided on the substrate 60. This wiring element can be obtained by applying the conventional method of manufacturing printed circuit boards to the substrate 60. It is desirable that the width of the through-holes 60c is longer than the width of the conductors 61 and 62; however, the former may be somewhat shorter than the latter. The squarethrough-holes60careshown in Figure 14; however, the configuration of the through-holes 60c may be any other ones such as for instance a circle.

In the case where a so-called shield wire, which is made up of a core wire covered with a dielectric layer and a braid wire surrounding the dielectric layer, is used, the following fact has been found: In the case where, as shown in Figure 15(a), the core wire 151 of a shield wire 150 is connected to the live side of a signal transmission path while the braid wire 152 thereof is connected to the ground side, current will flow in the conductors in the opposite directions as indicated by the arrows at a time instant. In this case, a signal to be transmitted is reversely affected. If this signal is an audio signal, it is impossible to transmit acoustic information correctly, which results in poor tone quality and lack of presence.

In the case also where, as shown in Figure 15(b), one end 151b of the core wire 151 is connected to one end 1 52b of the braid wire 152, so that the shield wire 150 is inserted in the signal transmission path through the other ends 1 51a and 152a, currents will flow in the conductors in the opposite directions as indicated by the arrows at a time instant. As a result, a signal to be transmitted is badly influenced, and the lack of information is markedly increased.

In the arrangement of Figure 15(c), one end 151b of the core wire 151 is connected to the one end 152b of the braid wire 152, while the other end 1 51a of the core wire 151 is connected to the other end 1 52a of the braid wire 152, and the shield wire 150 thus connected is inserted in the signal transmission path. In this case, currents will flow in the conductors in the same direction as indicated by the arrows at a time instant, and accordingly the signal to be transmitted is not significantly affected.

From the above-described facts, the following conclusion can be obtained: In the case where, as shown in Figure 16(a), there are two conductors {, and 2 perpendicular to the surface of the drawing through which currents flows in the opposite direc tions, a magnetic field exists between the conduc tors t1 and (2, which is the sum of magnetic fields B1 and B2 which are created by the currents in the conductors Ci and (2, respectively.Therefore, if, when the magnetic fields B1 and B2 change alter nately, and there is a dielectric between the conduc tors 11 and (2, then the dielectric polarisation, being affected by the magnetic fields, is vibrated, as a result of the interaction of which an electromotive force is superposed on the conductors 11 and 12.

Accordingly, the contents of information carried by the signal are changed.

In the case where, as shown in Figure 16(b), there are two conductors , and (2 perpendicular to the surface of the drawing through which currents flow in the same direction, magnetic fields B1 and B2 created by the currents in the conductors (i and {2 are cancelled by each other; that is, there is no magnetic field between the conductors 11 and t2.

Accordingly, even if a dielectric is provided between the conductors èa and e2, the dielectric polarisation is not affected and no electromotive force due to the interaction is superposed on the conductors ea and t2. Accordingly, the contents of information carried by the signal is not changed.

Accordingly, for the portions of a printed circuit board or a flexible printed circuit board, the correct transmission of information can be accomplished by forming signal transmission paths in the same pattern on both surfaces of the substrate or the insulating strip (not shown). Furthermore, since the boundary as to whether or not the contents of information carried by the signal are affected by the magnetic fields is 50%, all that is necessary is to form more than a half of the electrical conductive paths in the same pattern.

If the wiring element is formed as described above, information can be transmitted correctly, and the wiring can be ensured from the side of the wiring element where parts are mounted or from the other side where parts are not installed. In addition, parts can be positively secured to the wiring element.

Claims (5)

1. In a method for transmission of audio signals, between at least a half of the transmission lines where audio signals pass through, there exist no dielectric materials.

2. In a method for transmission of audio signals, at least a half of the transmission lines where audio signals pass through, are formed in the same pattern of electrically conductive lines on both sides of an electrically non-conductive substrate.

3. A cable for transmitting audio signals comprising: at least two conductors to which signals are applied and used as warps; and dielectric threads used as woofs weaving said conductors.

4. A flexible multicore cable which comprises: an electrical conductive layer obtained by spirally winding a metal material; a fiber material provided outside of said electrical conductive layer and having elements continuous in the longitudinal direction of said electrical conductive layer and/or a thermoplastic insulator provided together with or outside said fiber material; and at least two electrically conductive paths which are supported in the space defined in the inside of said electrical conductive layer so as to be exposed to air as much as possible.

5. Atransmission line for the passage of audio signals arranged in the same pattern of electrically conductive lines on both sides of an electrically non-conductive substrate.

5. A cable as claimed in claim 4, in which said electrical conductive paths are used as warps, and woven by woofs made of dielectric threads.

6. A cable as claimed in claim 4, in which said electrical conductive paths are embedded in an extremely foamed dielectric material.

New claims or amendments to claims filed on Date of issue of Search Report Superseded claims 1 to 6 New or amended claims:

1. A wiring cable for audio system comprising a flexible conductive tube, a plurality of flexible conductive wires, and insulator means which are dis posed in the tube and suspend the wires discreetly.

2. Aflexible multicoretablewhich comprises: an electrical conductive layer obtained by spirally winding a metal material; a fibre material provided outside of said electrical conductive layer and having elements continuous in the longitudinal direction of said electrical conductive layer and/or a thermoplastic insulator provided together with or outside said fiber material; and at least two electrically conductive paths which are supported in the space defined in the inside of said electrical conductive layer so as to be exposed to air as much as possible.

3. A cable as claimed in claim 2, in which said electrical conductive paths are used as warps, and woven by woofs made of dielectric threads.

4. A cable as claimed in claim 2, in which said electrical conductive paths are embedded in an extremely foamed dielectric material.