JPS626569Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an improvement of a tone arm.

For conventional tonearms with the rear end of the arm pipe as the weight axis, vibration isolating is done with rubber etc. inside the weight, but in this method, the resonance frequency is determined by the weight weight versus the spring constant of the anti-vibration rubber. That is, there was a drawback that the resonance frequency of the dynamic damper could not be freely selected. The reason for this is that the size of the weight is normally limited by the dimensions of the cabinet panel and dust cover, so the anti-vibration rubber cannot be thick enough, and that moving the weight causes This is because the resonance frequency changes, the distance from the bearing fulcrum is long, so the mechanical resistance required for response is large, and the bearing does not respond to minute vibrations.

In addition, with tonearms in which the arm pipe and weight shaft are each screwed to a resin arm holder, the strength of the arm holder is generally weak, and the compliance of the joint between the holder and the arm pipe, and the head shell + arm pipe. The vibration that resonates with the total weight of the weight cannot be transmitted to the weight shaft side. Therefore, even if a vibration isolation structure is provided on the weight shaft side, it does not respond to vibrations and does not function as a dynamic damper. on the other hand,
The same goes for resonance caused by the total weight of the weight + weight shaft and the compliance of the joint between the weight shaft and the pipe holder. Originally, only the weight part should vibrate with a movement out of phase with the vibration on the arm pipe side. vibrates and is transmitted to the needle tip. In order to eliminate these drawbacks, by making the pipe holder stronger than the arm pipe, the resonance from the front side of the bearing fulcrum can be transmitted to the rear side, and the mass of the weight part can be reduced by making the pipe holder stronger than the arm pipe. It is sufficient to support the pipe holder with a damper having an internal loss sufficient to reverse the phase, but if the pipe holder is made of resin, even if measures such as mixing carbon fiber are taken, there is a limit and the cost will increase significantly. In addition, the molding time becomes long, burrs are generated, and it takes time and effort to treat the appearance.

Further, as a conventional technique of a tone arm vibration isolation structure, for example, there is a technique as shown in Japanese Utility Model Application Laid-Open No. 55-149809. In this conventional technology, an arm pipe is fixed by a pipe holder, a rod-shaped body is provided protruding from this pipe holder, a rubber bushing is fitted to this rod-shaped body, and a weight shaft is press-fitted into the rubber bushing, thereby connecting the pipe holder and the weight shaft. are connected to suppress partial resonance.

However, in this conventional technology, the connection between the pipe holder and the weight shaft is made by fitting a rubber bushing to a rod-shaped body protruding from the pipe holder and press-fitting the weight shaft, so vibrations on the arm pipe side are transferred to the weight shaft side. In addition to the drawbacks of not being able to sufficiently transmit vibrations, and even if a vibration isolation structure is provided on the weight shaft side, it does not respond to vibrations and does not function as a dynamic damper, since it is connected by a rod-shaped body, It has the disadvantage of being weak in strength.

Therefore, the present invention was devised to eliminate the above-mentioned drawbacks, and is a tone arm consisting of an arm pipe, a pipe holder that fixes the pipe, and a weight shaft that is fixed to the rear end of the arm pipe. In this case, the arm pipe is fixed through the pipe holder, and the weight shaft at the rear end of the arm pipe protruding rearward from the holder has a weight shaft having the same outer diameter as the pipe holder and a slightly larger inner diameter. At the same time, a flange part is formed on the weight shaft side of the arm pipe to be in contact with the pipe holder, and the flange part is the same length as the weight shaft core, the outer diameter is the same as the inner diameter of the weight shaft, and the inner diameter is the same as the outer diameter of the arm pipe. By fitting and fixing the viscoelastic body into the arm pipe and fixing the pipe holder, weight shaft, and arm pipe together, it is possible to provide sufficient reinforcement even if the pipe holder is made of resin, and it is also effective. The purpose of the present invention is to provide a tone arm that can perform vibration isolation.

Hereinafter, the present invention will be explained based on the embodiments shown in the drawings. Fig. 1 is an exploded perspective view showing the main parts of the tone arm according to the invention, and Fig. 2 is a partially cut away main part of the tone arm according to the invention. FIG.

In the drawings, reference numeral 1 denotes an arm pipe, and a predetermined length portion of the rear end 1a of the pipe 1 serves as a weight axis 2. 3 is head shell, 4 is pipe holder,
Reference numeral 5 denotes a cylindrical viscoelastic body made of rubber or the like, and the entire length of the viscoelastic body 5 is approximately the same length as the weight axis 2 described above. The inner diameter of the viscoelastic body 5 is the same as the outer diameter of the weight axis 2, and 5a is the same size as the outer diameter of the weight axis 2.
The flange section is shown. 6 is a weight shaft whose inner diameter is the same as the outer diameter of the viscoelastic body 5;
indicates weight.

Next, the assembly of each of the above components will be explained. First, the rear end 1a of the arm pipe 1 is inserted into the pipe holder 4, and only the weight axis 2 protrudes from the rear end of the holder 4, and is fixed with screws, adhesive, or the like. Incidentally, the arm pipe 1 and the pipe holder 4 may be integrally molded by resin molding. Next, the viscoelastic body 5 is fitted onto the weight shaft core 2, and the weight shaft 6 is fitted onto the viscoelastic body 5, so that the front end of the weight shaft 6 is connected to the flange portion 5a of the viscoelastic body 5.
After fixing the weight shaft 6 in a state where the pipe holder 4 is pressed against the rear end of the pipe holder 4, a weight 7 is attached to the weight shaft 6. In FIG. 2, numeral 8 indicates a lead-out hole (not shown) for a lead wire connected to the cartridge, and numeral 9 indicates a bearing portion.

Therefore, by inserting and fixing the arm pipe 1 into the pipe holder 4 as described above, even if the pipe holder 4 is made of resin, it can be sufficiently reinforced. And in this case, arm pipe 1
The cross-sectional moment of inertia of the pipe holder 4 and the weight axis 2 are all the same as or greater than that of the arm pipe 1, and there are no extremely weak points that are susceptible to concentrated stress, so the energy during resonance is dispersed and the Q is low. Become.

In addition, since the weight axis 2 is the same rigid body as the arm pipe 1, by adjusting the spring constant of the viscoelastic body 5 fitted on the weight axis 2 to the resonance frequency of the arm pipe 1, the viscoelasticity can be adjusted. Due to the internal resistance of the body 5, the vibration phase of the weight 7 is reversed, making it possible to effectively cancel the resonance of the arm pipe 1.

As described above, the present invention is a tone arm consisting of an arm pipe 1, a pipe holder 4 that fixes the pipe, and a weight shaft 6 that is fixed to the rear end of the arm pipe. The weight axis 2 at the rear end of the arm pipe 1 is fixed through the holder 4 and protrudes rearward from the holder 4.
The weight shaft 6 has the same outer diameter as the pipe holder 4 and a slightly larger inner diameter, and a flange 5a is formed on the weight shaft 6 side of the arm pipe 1 to be in contact with the pipe holder 4, and A viscoelastic body 5 having the same length as the weight shaft core 2, the same outer diameter as the inner diameter of the weight shaft 6, and the same inner diameter as the outer diameter of the arm pipe 1 is fitted and fixed onto the arm pipe 1, and is attached to the pipe holder 4. Since the weight shaft 6 and the arm pipe 1 are fixed integrally, even if the pipe holder 4 is made of resin, it can be sufficiently reinforced at low cost. In addition, by effectively performing vibration isolation control, the tone arm, which is the key part of the reproduction system, is protected from unnecessary vibrations, and unnecessary resonance is not generated in the reproduced sound.

Furthermore, since the weight shaft 6 is supported by the weight shaft core 2 having sufficient strength, there is no bending, sagging, distortion, etc. of the weight shaft 6, and a good feel can be obtained. Furthermore, there is no need for an assembly process using screws, etc., and the number of parts can be reduced.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing the main parts of the tone arm according to the present invention, and FIG. 2 is a partially cut side view of the tone arm in an assembled state. 1...Arm pipe, 2...Weight axis, 4
... Pipe holder, 5 ... Viscoelastic body, 6 ... Weight shaft, 7 ... Weight.

Claims (1)

[Scope of utility model registration request] In a tone arm consisting of an arm pipe, a pipe holder for fixing the pipe, and a weight shaft fixed to the rear end of the arm pipe, the arm pipe is fixed through the pipe holder and protrudes rearward from the holder. A weight axis at the rear end has the same outer diameter as the pipe holder and a slightly larger inner diameter, and a flange portion is formed on the weight axis side of the arm pipe to contact the pipe holder, and A viscoelastic body having the same length as the weight shaft core, the same outer diameter as the inner diameter of the weight shaft, and the same inner diameter as the outer diameter of the arm pipe is fitted and fixed onto the arm pipe, and the pipe holder, weight shaft, and arm pipe are connected. A tone arm characterized by being fixed in one piece.