Connecting line for audio apparatus

Abstract: A conductor (42a) of an audio pin cable is electrically and mechanically connected at both ends thereof to the terminals inside of pin plugs (41a, 45a). A vibration attenuating member such as a cross section-enlarging member (43a) is joined at the middle portion of the conductor (42a) . The conductor (42a) and the cross section-enlarging member (43a) are coated around the periphery with an insulating member (44a). When a longitudinal wave passes through the conductor (42a), the cross section-enlarging member (43a) attenuates the longitudinal vibration transmission through the audio pin cable, thus achieving reproduced sounds as close to the original sounds as possible.

Description: The present invention relates to a connecting line for audio apparatus, and more particularly to a connecting line used for audio apparatus and/or for electric components inside of the audio apparatus, such as audio pin cables, audio lead wires, etc. One of the conventional audio connecting lines is, for example, an audio cable disclosed in Japanese Unexamined Patent Publication No. 335040/1996. The audio cable disclosed therein has connecting plugs at both ends thereof, each plug having a plus terminal and a minus terminal, and comprises two independent cables one of which is a plus cable connecting the plus terminals and the other of which is a minus cable connecting the minus terminals, so that mutual interference due to the magnetic field generated in the cables can be attenuated to provide improved sound quality. As shown above, the conventional technique relating to audio connecting lines aims to improve the sound quality, only in view of electromagnetic phenomena. However, when an audio cable as mentioned above is used to accomplish high fidelity reproduction, there arises a problem of unstable sound quality. To solve this problem, the inventor of this invention carried out extensive research and found the following. When reproducing a sound, audio apparatus such as an audio reproducing device, an audio amplifier and a speaker vibrate mechanically and the vibration is transmitted, in the form of longitudinal vibration, through a conductor inside of the audio connecting line and convoluted into an electric signal in the audio apparatus, which deteriorates reproduced sound quality. This phenomenon occurs not only between audio apparatus but also between electric components inside of the audio apparatus, such as between amplifiers circuit, capacitors and transformers, thus likewise deteriorating reproduced sound quality. The present invention provides a connecting line used for audio apparatus and/or for electric components inside of the audio apparatus and comprises: a conductor mechanically and electrically connected at an end thereof to an audio apparatus or to an electric component thereof; and attenuation means for attenuating the longitudinal vibration transmitted through the conductor. With the above construction, the attenuation means can attenuate the longitudinal vibration transmitted through the conductor and prevent vibration transmission between audio apparatus and between electric components inside of the audio apparatus, thus achieving reproduced sounds as close to the original sounds as possible. The above conductor may comprise a first conductor having a first cross-sectional area perpendicular to the axial direction of the first conductor, and the attenuation means comprises a cross section-enlarging member mechanically connected with the first conductor and enlarging the cross section perpendicular to the axial direction of the first conductor from the first cross-sectional area to a second cross-sectional area. The above conductor may instead comprise a first conductor having a first cross-sectional area perpendicular to the axial direction of the first-conductor, and the attenuation means comprises a second conductor electrically and mechanically connected to the first conductor and having a second cross-sectional area perpendicular to the axial direction of the second conductor, the second cross-sectional area being larger than the first one. Further the above conductor may comprise a first conductor extending along a first direction, and the attenuation means comprises a second conductor an end of which is electrically and mechanically connected to an end of the first conductor and the second conductor extends along a second axial direction intersecting with the first axial direction. Particular embodiments of connecting lines in accordance with this invention will now be described with reference to the accompanying drawings, in which:- Fig. 1 is a block diagram illustrating the construction of an audio system comprising audio connecting lines ; Fig. 2 is a partially sectional view illustrating the construction of an audio pin cable of a first embodiment of the invention; Fig. 3 is a diagram for illustrating how to determine longitudinal vibration attenuating characteristics of the audio pin cable shown in Fig. 2; Fig. 4 is a diagram showing frequency characteristics of the sound pressure determined at a measurement point A; Fig. 5 is a diagram showing frequency characteristics of the sound pressure determined at a measurement point B; Fig. 6 is a diagram showing frequency characteristics of the sound pressure measured at a measurement point C; Fig. 7 is a partially sectional view illustrating the construction of an audio pin cable of a second embodiment of the invention; and, Fig. 8 is a partially sectional view illustrating the construction of an audio pin cable of a third embodiment of the invention. Fig. 1 is a block diagram illustrating the construction of an audio system using audio connecting lines according to the invention. Referring to Fig. 1, the audio system comprises a reproducing device 1, a main amplifier 2, a speaker 3 and audio pin cables 4a, 4b. The reproducing device 1 is connected to the main amplifier 2 via the audio pin cable 4a. An audio signal reproduced by the reproducing device 1 is transmitted via the audio pin cable 4a to the main amplifier 2. The main amplifier 2 is connected to the speaker 3 via the audio pin cable 4b. The audio signal amplified by the main amplifier 2 is transmitted via the audio pin cable 4b to the speaker 3 where the audio signal is reproduced as an audible sound. For simplification of explanation, a 1-channel audio signal reproducing system is shown in the above audio system. In the case of reproducing 2-channel stereo signals from right and left channels, each of the channels comprise audio pin cables 4a, 4b, and audio signals are separately transmitted through the channels comprising audio pin cables 4a, 4b. Examples of the reproducing device 1 are record players, CD drives, MD drives, DVD drives and the like. The present invention can be used for connection of any audio apparatus, whether of analog or digital signal type, inclusive of image output apparatus having an audio signal reproducing function. The audio pin cables of the first embodiment of the invention for use as audio pin cables 4a, 4b in Fig. 1 are now described in detail. Fig. 2 is a partially sectional view illustrating the construction of the audio pin cable of the first embodiment. Referring to Fig. 2, the audio pin cable includes pin plugs 41a, 45a, a conductor 42a, a cross section-enlarging member 43a and an insulating member 44a. The terminals inside of the pin plugs 41a, 45a are electrically and mechanically connected to the conductor 42a. The cross section-enlarging member 43a is caulked and fixed at the middle portion of the conductor 42a. The conductor 42a and the cross section-enlarging member 43a are coated around the periphery thereof with the insulating member 44a. In this embodiment, for example, commercially available pin plugs can be used as pin plugs 41a, 45a, a copper wire (0.32 mm in diameter and 1000 mm long) as the conductor 42a, and a lead block (10 mm in diameter and 5 mm long) as the cross section-enlarging member 43a. Usable as the insulating member 44a are, for example, synthetic resins having insulating properties, such as vinyl resin. These are mentioned as examples and any change can be made according to the use conditions. In this specification, "mechanically connected" means connected mechanically so that vibration can be transmitted. The longitudinal vibration attenuating characteristics of the audio pin cable shown in Fig. 2 are now described. Fig. 3 is a diagram for illustrating how to determine longitudinal vibration attenuating characteristics of the audio pin cable shown in Fig. 2. Referring to Fig. 3, the method for determining longitudinal vibration attenuating characteristics of the audio pin cable is described. A straightened audio pin cable placed on a felt is hit at the point O, followed by measurement of the sound pressures at the measurement points A, B and C with the electronic sound measuring apparatus "FSB-7B" (product of Fuji Telecom, Co., Ltd.). Frequency analysis of the measured sound pressures is carried out using the digital oscilloscope "TDS-754A" (product of Tectronics, Co., Ltd.). The hit point O is 50 mm away from the left end of the pin plug 45a. From the same, the measurement point A is 100 mm away, the measurement point B 250 mm away, the center of the cross section-enlarging member 43a 500 mm away and the measurement point C 750 mm away. Figs. 4-6 show frequency characteristics of the sound pressures at the measurement points A, B and C, determined according to the above measurement method. It is evident from Figs. 4 and 5 that from the point A to point B where the cross section-enlarging member 43a is not included, the sound pressure hardly deceases, which indicates that the longitudinal vibration inside of the conductor 42a hardly attenuates. On the other hand, it is evident from Figs. 4 and 6 that from the point A to point C between which the cross section-enlarging-member 43a is included, the sound pressure decreases by about several to 40 dB, which indicates that the longitudinal vibration inside of the conductor 42a is attenuated sufficiently. This can be explained as follows. When a longitudinal vibration passes through a linear, elastic and substantially uniform conductor 42a, the conductor 42a gives force to the cross section-enlarging member 43a at the connection between the conductor 42a and the cross section-enlarging member 43a. In this embodiment, the cross-sectional area of the cross section-enlarging member 43a is about 1000 times as large as that of the conductor 42a. However, elastic modulus of the cross section-enlarging member 43a 1.62 x 10 6 N/cm 2 (lead: 1.62 x 10 11 dyn/cm 2 ) is about 1/10 that of the conductor 42a 12.3 x 10 6 N/cm 2 (copper: 12.3 x 10 11 dyn/cm 2 ). Considering these circumstances, it is assumed that the cross section-enlarging member 43a substantially increases the cross-sectional area of the conductor 42a about 100 times. Accordingly, the longitudinal wave passing through the conductor 42a attenuates by about 14 dB and is transmitted to the cross section-enlarging member 43a. Consequently, as already mentioned above, from the point A to point C between which the cross section-enlarging member 43a is included, the sound pressure decreases by about several to 40 dB and the longitudinal vibration inside of the conductor 42a is sufficiently attenuated. As shown above, with use of the audio pin cable of the first embodiment, the cross section-enlarging member 43a attenuates the longitudinal vibration transmitted through the conductor 42a and prevents vibration transmission between a reproducing device 1, a main amplifier 2 and a speaker 3, thus making reproduced sounds as close to the original sounds. The above-mentioned cross sectional ratio of the cross section-enlarging member 43a to the conductor 42a and material are simply examples and, insofar as the cross section-enlarging member can attenuate by at least 3 dB the longitudinal wave transmitted through the conductor, others can also be used to produce similar effects so that good reproduction characteristics can be obtained. The audio pin cables of the second embodiment of the invention for use as audio pin cables 4a, 4b in Fig. 1 are now described in detail. Fig. 7 is a partially sectional view illustrating the construction of the audio pin cable of the second embodiment. Referring to Fig. 7, the audio pin cable includes pin plugs 41b, 45b, a first conductor 42b, a second conductor 46b and an insulating member 44b: The terminals inside of pin plugs 41b, 45b are electrically and mechanically connected to the first conductor 42b and the second conductor 46b respectively. An end of the first conductor 42b is electrically and mechanically connected to an end of the second conductor 46b. The first conductor 42b and second conductor 46b are coated around the periphery thereof with an insulating member 44b. In this embodiment, for example, commercially available pin plugs can be used as pin plugs 41b, 45b, a copper wire (0.32 mm in diameter) as the first conductor 42b, and a copper wire (3 mm in diameter) as the second conductor 46b. Usable as the insulating member 44b are, for example, synthetic resins having insulating properties, such as vinyl resin. These are mentioned as examples and any change can be made according to the use conditions. The longitudinal vibration attenuation characteristics of the audio pin cable shown in Fig. 7 are now described. When a longitudinal vibration passes through a linear, elastic and substantially uniform first conductor 42b, the end face of the first conductor 42b gives force to the end face of the second conductor 46b at the connection. In this embodiment, the cross-sectional area of the second conductor 46b is about 100 times as large as that of the first conductor 42b. Accordingly, when the vibration is transmitted from the first conductor 42b to the second conductor 46b, the amplitude of the longitudinal wave is attenuated to approximately one-fifth. That is, the longitudinal wave passed through the first conductor 42b attenuates by about 14 dB, when transmitted to the second conductor 46b. Thus, similarly to the first embodiment, the audio pin cable of the second embodiment can attenuate the longitudinal vibration at the moment of longitudinal wave transmission from the first conductor 42b to the second conductor 46b, and prevent vibration transmission between a reproducing device 1, a main amplifier 2 and a speaker 3, thus making reproduced sounds as close to the original sounds. The above cross sectional ratio of the second conductor 46b to the first conductor 42b and material are mentioned as examples, and others can also be used to produce similar effects. As in the case of the first embodiment, insofar as the longitudinal wave transmitted from the first conductor to the second conductor is attenuated by at least 3 dB, good reproduction characteristics can be obtained. The audio pin cables of a third embodiment of the invention for use as audio pin cables 4a, 4b in Fig. 1 are now described in detail. Fig. 8 is a partially sectional view illustrating the construction of the audio pin cable of the third embodiment. Referring to Fig. 8, the audio pin cable includes pin plugs 41c, 45c, a first conductor 42c, a second conductor 46c and an insulating member 44c. The terminals inside of the pin plugs 41c, 45c are electrically and mechanically connected to the first conductor 42c and the second conductor 46c respectively. An end of the first conductor 42c is electrically and mechanically connected to an end of the second conductor 46c, at right angles to each other. The first conductor 42c and the second conductor 46c are coated around the periphery thereof with the insulating member 44c. In this embodiment, for example, commercially available pin plugs can be used as pin plugs 41c, 45c, and copper wires (0.32 mm in diameter) as the first and second conductors 42c, 46c. Usable as the insulating member 44c are, for example, synthetic resins having insulating properties, such as vinyl resin. These are mentioned as examples and any change can be made according to the use conditions. The longitudinal vibration attenuation characteristics of the audio pin cable shown in Fig. 8 are now described. When a longitudinal wave passes through a linear, elastic and substantially uniform first conductor 42c, the end face of the first conductor 42c gives force to the end face of the second conductor 46c at the connection. In this embodiment, the first conductor 42c and the second conductor 46c are connected at right angles to each other, and the cross sectional ratio of the first conductor 42c to the second conductor 46c is 1. In this case, the longitudinal wave actually attenuates by about 3 dB, although it is ideal that no longitudinal wave is transmitted from the first conductor 42c to the second conductor 46c. Thus, similarly to the first embodiment, the audio pin cable of the third embodiment can attenuate the longitudinal vibration at the moment of longitudinal wave transmission from the first conductor 42c to the second conductor 46c, and prevent vibration transmission between the reproducing device 1, the main amplifier 2 and the speaker 3, thus making reproduced sounds as close to the original sounds. The above-mentioned angle between the second conductor 46c and the first conductor 42c, the cross sectional ratio of the first conductor 42c to the second conductor 46c and material are simply examples. As in the case of the first embodiment, others can also be used insofar the longitudinal wave transmitted from the first conductor to the second conductor is attenuated by at least 3 dB. To obtain good reproduction characteristics, it is desirable that the first conductor 42c and second conductor 46c are connected at an angle of 75 to 105 degrees, preferably at an angle of 80 to 100 degrees. In the third embodiment, an L-shaped audio pin cable having only one corner is illustrated but cables of other shapes, such as multi-cornered, zigzagged or spiral cables, can be used to produce similar effects. In the third embodiment, two separate conductors are connected to make the corner. The corner made by bending one conductor can also achieve a similar effect. The above embodiments illustrate the case of applying the present invention to audio pin cables. Similar effects can be produced by applying the invention to other audio connecting lines, such as an audio lead wire for connecting electric components inside of audio apparatus, an audio harness comprising a plurality of the above audio pin cables, an power supply cable for providing electric power to audio apparatus or electronic components inside thereof, a speaker cable and the like. Also, a suitable combination of the above embodiments can be used to achieve similar effects. The present invention can be applied not only to the general "audio apparatus" but also to any "audible sound output apparatus", such as electronic hearing aids and electronic stethoscopes in the field of medical equipment.

Claims: A connecting line (4a, 4b) used for audio apparatus and/or for electric components inside of the audio apparatus, the connecting line comprising: a conductor (42a, 42b, 42c) mechanically and electrically connected at an end thereof to an audio apparatus or to an electric component thereof; and attenuation means (43a, 46b, 46c) for attenuating the longitudinal vibration transmitted through the conductor. The connecting line according to claim 1 wherein the conductor comprises a first conductor (42a) having a first cross-sectional area perpendicular to the axial direction of the first conductor, and the attenuation means comprises a cross section-enlarging member (43a) mechanically connected with the first conductor and enlarging the cross section perpendicular to the axial direction of the conductor from the first cross-sectional area to a second cross-sectional area. The connecting line according to claim 1 wherein the conductor comprises a first conductor (42b) having a first cross-sectional area perpendicular to the axial direction of the first conductor; and the attenuation means comprises a second conductor (46b) electrically and mechanically connected to the first conductor and having a second cross-sectional area perpendicular to the axial direction of the second conductor, the second cross-sectional area being larger than the first one. The connecting line according to claim 1 wherein the conductor comprises a first conductor (42c) extending along a first direction; and the attenuation means comprises a second conductor (46c) an end of which is electrically and mechanically connected to the first conductor and the second conductor extends along a second axial direction intersecting with the first axial direction.

Inventors: YOSHII HIROYUKI, YOSHII, HIROYUKI
Applicants: ASCII CORP, TIME DOMAIN CORP, ASCII CORPORATION, TIME DOMAIN CORPORATION
Application year: 1998
Main classification: H01B11
IPC codes: H01B11, H01B7