JP3004534U - Signal cable - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to improve the transmission characteristics of a transmission signal in a signal cable in which the periphery of the signal line is covered with a shield line through an insulating layer by simply changing the connection method of the shield line. Get the technology you can. A connection line 3a is drawn from the shielded wire 3 covering the signal line 1 on the side of the input end 1a of the signal line 1 and connected to the input end 2a of the signal line 2. Further, from the shielded wire 4 covering the signal wire 4, a connection wire 4a connected to the signal wire 2 is drawn out on the output end 2b side of the signal wire 2. An acoustic signal is transmitted from the input side to the output side of the signal line 1, and the signal line 2 is connected to the ground potential of the input / output device.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a signal cable, and more particularly to a technique suitable for use as an audio cable or an image cable for connecting between audio equipments or video equipments to improve the transmission efficiency of audio signals or video signals.

[0002]

[Prior art]

 2. Description of the Related Art Conventionally, an audio cable or video cable for connecting audio equipment or video equipment has a pair of signal lines, and a two-core coaxial cable covered with a shield wire provided around the pair of signal lines through an insulating layer. Cables and coaxial cables in which a pair of signal lines are covered with a shield wire via an insulating layer are used.

Audio or video cables are required to faithfully transmit a necessary frequency component in a transmission signal in order to improve transmission efficiency. Therefore, the amplitude characteristic and phase characteristic of a transmission signal are transmitted. There are various techniques for improving the noise reduction and reducing the attenuation or distortion of the signal waveform, and for eliminating the influence of external noise on the transmission signal.

As these ideas, for example, Japanese Patent Publication No. 3-17330 and Japanese Patent Laid-Open No. 1-302612 disclose that a signal line and a shield line covering the signal line with an insulating layer are electrically conductive on the input side. Providing a pair of connected parts and covering this pair with a single ground shield via an insulating layer, or by covering each pair with a ground shield via an insulating layer, loss of transmission signal and external It describes a signal cable that can reduce the effects of noise.

[0005]

[Problems to be solved by the device]

 The above-mentioned conventional signal cable is greatly improved in both the fidelity of the transmission signal and the elimination of external noise, as compared with the signal cable before that. However, it is necessary to dispose three layers of conductors through two layers of insulation, and at the connection part, in addition to the signal line, connect two layers of shielded wire to the signal line and the equipment ground, respectively. Therefore, it is difficult to reduce the manufacturing cost due to the complicated structure.

In some audio equipment and video equipment, the shield wire of the signal cable cannot be connected to the earth of the equipment. In such a case, a protection circuit is newly provided in the equipment. It may be difficult to connect the signal cable because it must be installed or grounded separately.

Therefore, the present invention solves the above-mentioned problems, and the problem is only to change the connection method of the shield wire in a normal signal cable in which the signal wire is covered with the shield wire through an insulating layer. Is to obtain a technology that can easily improve the transmission characteristics of a transmission signal.

[0008]

[Means for Solving the Problems]

 The present invention provides a first signal line and a second signal line, which are respectively connected between a first signal device and a second signal device and are configured to transmit a predetermined signal, and an insulator for the first signal line. A signal cable comprising: a first shield wire that covers via a second shield wire; and a second shield wire that covers a second signal wire via an insulator, wherein the second signal wire is a constant potential wire, and The shield line is connected to the same potential as the second signal line on the first signal device side, and the second shield line is connected to the same potential as the second signal line on the second signal device side.

In the above configuration, the first shield line is conductively connected to the second signal line directly or indirectly on the first signal device side, and the second shield line is directly or indirectly on the second signal device side. It may be conductively connected to the second signal line.

Further, the first shield wire is conductively connected to the second signal wire directly or indirectly on the first signal device side, and the first shield wire is conductively connected to the second shield wire on the second signal device side. There is a case.

In each of the above means, it is preferable that the first signal device is a signal transmitter and the second signal device is a signal receiver.

[0012]

[Action]

 According to claim 1, by connecting the first shield wire and the second shield wire to each other at the same potential as the second signal wire on the opposite sides of the cable, the transmission characteristic of the transmission signal is improved as compared with the conventional one. The S / N ratio of the transmitted signal is improved and an output full of speed and dynamism is obtained. Moreover, since the first shield line and the second shield line are connected to the same potential as the second signal line which is a constant potential line, the shield effect against external noise can be sufficiently exerted, and the first signal line and the second signal line It is possible to prevent external noise from being induced in the second signal line.

Also in the concrete modes shown in claims 2 and 3, the same effects as those of the above claims 1 and 2 are obtained.

In the present invention, it suffices to connect directly or indirectly to the second signal line only on the side of the first signal device, and in the second signal device, the first shield line and the second shield line are connected to the second signal line. Even if it is not desirable to connect to the device or it is difficult to connect to the device, it can be easily connected.

In the fourth aspect, the first signaling device is the signal transmitter and the second signaling device is the signal receiver, whereby the effect described in the first aspect is further enhanced.

[0016]

【Example】

 Next, an embodiment of a signal cable according to the present invention will be described with reference to the accompanying drawings. FIG. 1 shows the structure of a first embodiment according to the present invention. In this embodiment, as shown in FIG. 1A, an audio cable or a video cable is connected between a transmitting device such as a preamplifier and a receiving device such as a power amplifier. The signal lines 1 and 2 are connected between the transmitting device and the receiving device, and are, for example, stranded wires formed by bundling a plurality of pure silver wires or surface-coated oxygen-free copper wires with silver or gold as needed.

The signal line 1 is provided with a shield line 3 via an insulating layer (not shown), and the signal line 2 is provided with a shield line 4 via an insulating layer (not shown). The shielded wires 3 and 4 are braided wires in which copper wires are knitted in a cylindrical shape on the surface of an insulating coating made of synthetic resin formed around the signal wires 1 and 2. Here, the signal line 1 and the shielded line 3 and the signal line 2 and the shielded line 4 may be covered with insulating coatings to form separate cables, or both shielded lines 3 and 4 may be used. May be embedded in an integral insulating coating in a separated state to form an integral cable.

The input end 1 a of the signal line 1 and the input end 2 a of the signal line 2 are connected to a transmitting device, and the output end 1 b of the signal line 1 and the output end 2 b of the signal line 2 are connected to a receiving device. Here, the audio signal or the video signal is applied between the signal line 1 and the signal line 2, and the signal line 2 is connected to the ground lines of the transmitting device and the receiving device.

The shielded wire 3 includes a connecting wire 3 a drawn from the input end 1 a side thereof, and the connecting wire 3 a is conductively connected to the input end 2 a of the signal wire 2. Further, the shielded wire 4 is provided with a connection wire 4 a drawn from the output end 2 b side of the signal wire 2, and this connection wire 4 a is conductively connected to the output end 2 b of the signal wire 2.

In this embodiment, the shielded wires 3 and 4 are both connected to the signal line 2 and indirectly dropped to the ground, so that the shielded wires 3 and 4 are electromagnetically affected by external noise and the like as in the conventional case. It functions as a shield, reduces the influence of external noise, and improves the signal transmission characteristics, especially the transmission signal phase characteristics, by connecting the shield wires 3 and 4 to the opposite ends of the signal wire 2. Therefore, the sound quality of the audio signal or the image quality of the video signal is significantly improved. For example, compared with the case where a conventional multi-core cable is used for the same transmitter / receiver, the sound of some musical instruments of the orchestra that cannot be heard or can only be heard indistinctly with the conventional cable is generated by the cable of this embodiment. Then you will be able to hear clearly. It is extremely difficult to measure the transmission characteristics of a cable with respect to an actual audio signal or video signal because it is greatly affected by the measurement equipment and the arrangement of the cable, etc. For example, regardless of the equipment used, the location, etc., and regardless of the listener, there is always a clear difference from the conventional example.

In a normal coaxial cable, the amplitude characteristic and the phase characteristic with respect to the frequency component of the signal change, the waveform of the transmission signal is attenuated and distorted on the output side, and a good signal cannot be obtained in the receiving device. In this embodiment, the S / N ratio of the signal is improved as a whole, and when it is used as an acoustic cable, a speedy feeling or a dynamic feeling that is clearly discernible can be obtained. Although the details of the cause of the improvement in the transmission characteristics are not clear, the cause is that the shield line 3 and the shield line 4 are conductively connected at the opposite ends of the signal line 2, respectively. The potential fluctuations induced in the shielded wire 3 by the signal propagating to the signal line 2 are less likely to affect the potential of the shielded wire 4 than in the case where both shielded wires are connected to the same side of the signal wire 2, so It is conceivable that the potential fluctuations in the above are reduced or the time constant of the potential fluctuations is shortened, and the stability of signal transmission / reception is improved.

On the other hand, in the techniques disclosed in Japanese Patent Publication No. 3-17330 and Japanese Patent Laid-Open No. 1-302612, a shield wire surrounding a signal line is conductively connected to the signal line itself at the input end. Since the signal line and the shield line have the same potential, the influence of the surroundings on the signal lines 1 and 2 can be reduced and the transmission loss can be reduced. However, since the shield line in this case is held at the same potential as the signal line, it is necessary to further provide a ground shield for external noise around them. In this embodiment, since the shield line 3 is connected to the signal line 2, the signal line 1 and the shield line 3 are not at the same potential, so the transmission loss cannot be reduced as in the above-mentioned document, but the signal The phase characteristic is improved as much as that of the above-mentioned document, and unlike the technique shown in the above-mentioned document, there is no need to provide a double shielded wire, so that there is an effect that it can be manufactured at low cost.

Next, a modification of the above embodiment will be described. As shown in FIG. 1B, in the same configuration as the above-described embodiment, the connection line 3a drawn from the shield line 3 is connected to the signal line 2 on the output end 1b side of the signal line 1. The connection line 4a led out from the shielded line 4 is connected to the signal line 2 at its input side. When connected in this way, the degree of improvement in signal transmission characteristics is slightly weaker than in the above-mentioned embodiment, but a difference from the conventional cable is apparent.

Next, a second embodiment of the signal cable according to the present invention will be described with reference to FIG. In this embodiment, the signal lines 1 and 2 and the shield lines 3 and 4 have the same configurations as in the first embodiment, and the same parts are designated by the same reference numerals and their description is omitted. In this embodiment, the connection line 3a drawn from the shielded line 3 is connected to the signal line 2 on the input end 1a side of the signal line 1, but further on the output end 1b, 2b side of the signal lines 1 and 2. At this point, the shielded wire 3 and the shielded wire 4 are conductively connected to each other by a connecting wire 5.

Also in this embodiment, as in the first embodiment, there is a modification shown in FIG. 2B. In this modification, the connection line 3a drawn from the shield line 3 is connected to the signal line 2 on the side of the output end 1b of the signal line 1, and the side of the input ends 1a and 2a of the signal lines 1 and 2 is connected. The shielded wire 3 and the shielded wire 4 are conductively connected by a connecting wire 5. Further, as shown by dotted lines in FIGS. 2A and 2B, the connection line 4a may be used instead of the connection line 3a for connection.

In the present embodiment, the shield line 3 is directly conductively connected to the signal line 2, but the shield line 4 is conductively connected to the signal line 2 via the connection line 5 and the shield line 3. Has been done. In this embodiment as well, the signal transmission characteristics are improved as compared with the prior art, although there is a degree of difference from the first embodiment. In particular, the example shown in FIG. 2A is the most effective, including the one shown in FIG. This embodiment is particularly suitable when one of the transmitting device and the receiving device cannot be effectively grounded. For example, this is the case when a protective circuit is not provided in the earth line of the device. In this case, the connection line 3a is connected on the side of the equipment that can take the ground. Here, it is preferable in terms of noise prevention that the connecting wire 5 is not connected to the terminal at the cable end, but is connected to both shield wires before the terminal at the cable end.

In this embodiment, the shielded wire 3 and the shielded wire 4 are connected to each other by the connection wire 5, but the potential fluctuation of the shielded wire 3 induced by the signal of the signal wire 1 is different from that of the signal wire 2. However, the connection mode of both shielded wires may reduce the effect of stray capacity between shielded wire 3 and shielded wire 4 (depending on the distance between both wires). Conceivable.

FIG. 3 illustrates a third embodiment according to the present invention. This embodiment shows an example of a signal cable connected between a preamplifier and a power amplifier in an audio system. As shown in FIG. 3A, the shield line 3 is arranged around the signal line 1, and the shield line 4 is arranged around the signal line 2. The input end of the signal line 1 is connected to the output terminal 61 of the preamp 6, and the input end of the signal line 2 is connected to the output terminal 63 of the preamplifier 6. The output terminal 63 of the preamplifier has the same potential as the ground wire, and the ground terminal 62 is provided separately.

The signal line 1 is connected to the input terminal 71 of the power amplifier 7, and the signal line 2 is connected to the input terminal 73 of the power amplifier 7. The input terminal 73 has the same potential as the ground wire, and the ground terminal 72 is provided separately. The connection line 3 a is drawn out from the input side of the shielded line 3 and connected to the ground terminal 62 of the preamplifier 6. A connection line 4a is drawn out from the output side of the shielded line 4 and connected to the ground terminal 72 of the power amplifier 7. FIG. 3 (b) shows a modification of the above embodiment, in which instead of the connecting wire 4a, a connecting wire 5 for conductively connecting the shield wire 3 and the shield wire 4 is provided.

In the third embodiment shown in FIG. 3A, although the shield lines 3 and 4 are indirectly connected to the signal line 2, the third embodiment is similar to the first embodiment shown in FIG. 1A. The same effect is achieved. Further, the modification shown in FIG. 3B has the same configuration as the second embodiment shown in FIG. 2A and has the same effect. Here, in the present embodiment, the cable connected between the preamplifier 6 and the power amplifier 7 is shown as an example, but between the audio or video player and the preamplifier, between the amplifier and the speaker or the monitor, etc. You can connect in the same way.

In each of the above embodiments, when the shielded wire 3 for the signal wire 1 is connected to the signal wire 2 on the input device side, that is, the one shown in FIGS. 1A and 2A is the other one. Have been found to be more effective than. This tendency has been confirmed for multiple devices of different types and manufacturers, and when the cable is connected between the record player, CD player, etc. and the preamplifier, or between the preamplifier and the power amplifier. It has always been confirmed even when connected between a power amplifier and a speaker. Regardless of the environment, always connect shield wire 3 to signal wire 2 on the signal input side and shield wire 4 to output signal. It has been found that it is more preferable to connect to the signal line 2 or the shield line 3 on the side. Although the cable structure is complicated, it has been confirmed that a signal with less noise can be generated by further covering the periphery of the above embodiment with a shield.

[0032]

[Effect of device]

 As described above, according to the present invention, signal transmission is achieved by connecting the first shield line and the second shield line to the same potential as the second signal line, which is a constant potential line, on opposite sides of each other. In addition to improved characteristics, it is possible to realize a signal cable that can be easily manufactured without the need to provide a double shield.

[Brief description of drawings]

FIG. 1 is a conceptual explanatory view (a) showing a configuration of a first embodiment according to the present invention and a conceptual explanatory view (b) showing a modified example of the same embodiment.

FIG. 2 is a conceptual explanatory view (a) showing a configuration of a second embodiment according to the present invention and a conceptual explanatory view (b) showing a modified example of the same embodiment.

FIG. 3 is a conceptual explanatory view (a) showing a configuration of a second embodiment according to the present invention and a conceptual explanatory view (b) showing a modified example of the same embodiment.

[Explanation of symbols]

 1, 2 Signal line 1a, 2a Input terminal 1b, 2b Output terminal 3, 4 Shield wire 3a, 4a, 5 Connection wire 6 Preamplifier 61, 63 Output terminal 7 Power amplifier 71, 73 Input terminal 62, 72 Ground terminal

Claims (6)

[Scope of utility model registration request] 1. A first signal line and a second signal line each connected between a first signal device and a second signal device and configured to transmit a predetermined signal, and the first signal line. It is a signal cable provided with the 1st shield wire which covers via an insulator, and the 2nd shield wire which covers the 2nd signal wire via an insulator, wherein the 2nd signal wire is a constant potential wire. And connecting the first shield wire to the same potential as the second signal line on the first signal device side, and setting the second shield wire to the same potential as the second signal line on the second signal device side. A signal cable characterized by being connected. 2. The method according to claim 1, wherein the first shield wire is conductively connected to the second signal wire directly or indirectly on the first signal equipment side, and the second shield wire is connected to the second signal equipment. A signal cable characterized in that it is electrically conductively connected to the second signal line directly or indirectly on the side. 3. The first shield wire according to claim 1, wherein the first shield wire is conductively connected to the second signal wire directly or indirectly on the first signal equipment side, and the first shield wire is connected to the second signal equipment. A signal cable, characterized in that it is conductively connected to the second shield wire on the side. 4. The signal cable according to claim 1, wherein the first signaling device is a signal transmitter and the second signaling device is a signal receiver. 5. The signal cable according to claim 2, wherein the first signaling device is a signal transmitter and the second signaling device is a signal receiver. 6. The signal cable according to claim 3, wherein the first signaling device is a signal transmitter and the second signaling device is a signal receiver.