JPS624763B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a tone arm for a record player, etc. The tone arm is preferably lightweight and highly rigid. However, the two are contradictory. In other words, if you try to reduce the weight, the rigidity will decrease, and if you try to increase the rigidity, the weight will increase. Although it is conceivable to use cemented carbide as the material, this is not suitable because it is inconvenient to process and its specific gravity is several times as large. An object of the present invention is to provide a tone arm that is lightweight, has high rigidity, and is easy to process. According to the present invention, there is provided a tone arm in which a plurality of thin-walled, hollow cylindrical pipes are juxtaposed and closely fixed to each other substantially parallel to each other. A high tone arm can be obtained, and its material can be easily processed. The wall thickness of the pipe used is 1/20 of the pipe diameter.
The following may be sufficient, and weight reduction can be achieved by this. Further, it is sufficient that one of the pipes has a predetermined length as a tone arm, and high rigidity can be maintained even if the other pipes are made shorter than that. The number of pipes is 3~
Eight are representative. In addition to straight pipes of the same diameter, tapered pipes, etc. can be handled in a similar manner. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a pickup device using a composite pipe type tone arm according to the present invention. The tone arm 1 according to the present invention includes three thin-walled hollow cylindrical pipes as shown in FIG. 2 arranged in parallel to each other and fixed in close contact with each other. A typical example is one in which thin-walled, hollow cylindrical pipes of books are arranged parallel to each other and closely fixed to each other, but an appropriate number of other pipes can be used. Further, as shown in FIG. 3, the diameters of the pipes do not necessarily have to be the same. Further, a tapered pipe may be used instead of a cylindrical straight pipe.
Weight reduction can be achieved by using a pipe with a small diameter. Even if the pipe diameter is reduced, rigidity remains high. Alternatively, the overall pipe diameter may be reduced, and a larger diameter pipe may be arranged on the outside, as shown in FIGS. 5 and 6. This allows further weight reduction. In this case, the inner pipes are closely fixed not only to each other but also to the inner surface of the outer pipe. The common method for closely fixing pipes is thermosetting adhesive using epoxy resin, etc., but other methods such as welding, ultrasonic welding, friction welding, electron beam welding, etc. can also be applied. In the case shown in FIG. 7, one pipe 2 has a predetermined length as a tone arm, and the other pipes 3 and 4 are made shorter than that, and the pipes 3 and 4 are arranged in the middle of the pipe 2. It is tightly fixed. It has been confirmed through experiments that even in this case, the rigidity is maintained at a high level (in the drawing, it consists of three pipes, but the structure is not limited to this). This not only helps in reducing the weight of the tone arm, but also facilitates machining of the attachment portion to the shell 5, the attachment portion to the arm support portion, etc. Furthermore, it has been found that the wall thickness of the pipe may be thin, about 1/20 of the pipe diameter or less. By passing the left channel of the signal line from the pickup through one pipe and the right channel through another pipe, crosstalk due to mutual induction can be prevented. The frequency characteristics of a conventional single pipe tone arm and a composite pipe tone arm according to the present invention were measured to confirm the effects of the tone arm according to the present invention. The tone arms used for this measurement had the same configuration except for the number of pipes, as shown in the table below. Furthermore, as a representative example of the composite pipe type tone arm according to the present invention, the one in which three tone arms are arranged in parallel as shown in FIG. 2 was selected as a representative one.

[Table] The frequency characteristics were measured for each tone arm using the same pick-up cartridge, the same turntable, and the same test record for frequency characteristics testing. In addition, as a test record, due to the frequency characteristics of 4 to 100 Hz, the one made by Nippon Columbia Co., Ltd.
A record model number DENON (registered trademark) The instrument used to measure the frequency characteristics was a 2305 pen recorder type high-speed level recorder manufactured by Bru¨el & Kjoer. The results of these measurements are shown in Figures 8A and 8B as well as Figures 9A and 9B. Figure 8A shows the frequency response of a conventional single-pipe tonearm from 4 to 100Hz, and Figure 8B shows the frequency response of the same tonearm from 20Hz to 100Hz.
Each shows the frequency characteristics of 20KHz. Furthermore, Fig. 9A shows the frequency characteristics of the composite pipe type tone arm according to the present invention at 4 to 100 Hz, and Fig. 9B shows the frequency characteristics of the same inventive tone arm from 20 Hz to 20 KHz.
shows the frequency characteristics of Comparing these frequency characteristics, resonance points a and b (FIGS. 8A and 8B) appear in the conventional single-pipe tone arm due to bending. On the other hand, in the composite pipe type tone arm according to the present invention, as shown in FIGS. 9A and 9B,
No resonance appears. Therefore, by closely fixing a plurality of pipes substantially parallel to each other as in the present invention, resonance due to bending or twisting of the tone arm does not occur, and rigidity against bending or twisting is increased. This can be confirmed.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view of a pickup device using a tone arm according to one embodiment of the present invention, FIG. 1A is a sectional view taken along line A-A in FIG. 1, and FIG. 2 is an embodiment of the tone arm 3 to 6 are front views showing various examples of the tone arm, and FIG. 7 is a perspective view of the tone arm showing still another example.
8A and 8B are graphs showing the frequency characteristics of a conventional single pipe tonearm, and FIGS. 9A and 9B are graphs showing the frequency characteristics of the composite pipe tonearm of the present invention. 1...Tone arm, 2, 3, 4...Pipe.

Claims (1)

[Scope of Claims] 1. A tone arm comprising at least two thin-walled, hollow cylindrical pipes arranged side by side and closely fixed in substantially parallel relation to each other. 2. The tone arm according to claim 1, having three pipes. 3. The tone arm according to claim 2, wherein one of the three pipes has a different diameter. 4. The tone arm according to claim 2, wherein all three pipes have the same diameter. 5. The tone arm according to claim 1, having seven pipes. 6. The tone arm according to claim 5, wherein all seven pipes have the same diameter. 7. One of the pipes has a predetermined length as a tone arm, the other pipe is shorter than that, and the other pipe is closely fixed at an intermediate position of the one pipe. The tone arm according to claim 1, characterized in that: 8. The tone arm according to claim 1, wherein the left channel signal line is passed through one pipe and the right channel signal line is passed through the other pipe. 9. The tone arm according to claim 1, wherein the wall thickness of the pipe is about 1/20 or less of the pipe diameter.