JPS6117675Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a moving coil type pick-up cartridge.

2. Description of the Related Art Conventionally, moving coil type pickup cartridges are known, such as those shown in FIGS. 1 and 2, for example. To explain these figures, first, Fig. 1 shows a pick-up cartridge A, in which 1 is a magnet, 2,
3 is a yoke, 4 is a pole piece, and yoke 2
A magnetic gap 5 is formed between the rear end surface of the pole piece 4 and the front end surface of the pole piece 4. A coil 7 is arranged in this magnetic gap 5 and wound around a winding core 6. A cantilever 9 placed through a hole 8 formed at the end is fixed, and a needle tip 10 is fixed to the tip of the cantilever 9. Based on the above configuration, the vibration captured by the needle tip 10 is transmitted to the winding core 6 and the coil 7 via the cantilever 9, and the coil 7 rotates and vibrates in the magnetic gap 5 to cut the magnetic flux. , a voltage is induced in this coil 7. However, according to this pick-up cart cartridge A,
There is a winding core 6 around which the coil 7 is wound in the magnetic gap 5, and since the coil 7 is configured to vibrate together with the winding core 6 in the direction of the arrow shown in the figure, the interval between the magnetic gaps 5 is large. There is a drawback that the magnetic flux in the magnetic gap 5 cannot be increased, and therefore the output voltage cannot be increased. Also, FIG. 2 shows a pick-up cartridge B (the same parts in FIG. 2 as in FIG. 1 are given the same reference numerals), and the differences between this figure and FIG. 1 will be explained. Then, the pole piece 4 is arranged with its tip facing into the hole 8 formed at the end of the yoke 2, and the outer peripheral surface of the tip of the pole piece 4 and the hole 8
A magnetic gap 5 is formed between the magnetic gap 5 and the inner surface, and a coil 7 is arranged in the magnetic gap 5 so as to be wound around the cylindrical portion of a bobbin 11 having a cylindrical shape with a bottom. The bobbin 11 has a cantilever 9 on the outside of its bottom, and the inside of the bottom is supported by the tip end surface of the pole piece 4 via a damper 12. The bobbin 11 is supported on the pole piece 4 side by a suspension wire 1 stretched between the cantilever 9 and the pole piece 4.
It is done by 3. In the pick-up cartridge B having the above configuration, the coil 7 is wound around the cylindrical portion of the bobbin 11 in the magnetic gap 5. Therefore, the pickup cartridge B has a larger magnetic gap than the one using the winding core 6 shown in FIG. The interval can be narrowed down to 5. However, since the coil 7 and bobbin 11 also vibrate in the direction of the arrow in the pick-up cartridge B, the distance between the magnetic gap 5 and the coil 7 and the bobbin 11 are reduced to the outer peripheral surface of the tip of the pole piece 4 or the inner surface of the hole 8 of the yoke 2. It is necessary to set it so that it does not touch. Therefore, the problem that occurred with the pick-up cartridge A in Fig. 1 is as follows.
This pick-up cartridge B also does not fundamentally solve the problem.

In view of the above-mentioned circumstances, this invention provides a moving coil type pickup cartridge in which the magnetic gap in which the vibration system coil is arranged can be configured narrowly, thereby efficiently extracting the output voltage. be. To explain the features of this device, the front end surface of the pole piece constituting one of the magnetic poles is formed into a depressed conical shape, and a damper having a conical surface corresponding to this front end surface is provided. A vibration system is held in between, and the coil of this vibration system is wound around a hollow hemispherical coil bobbin, and this coil bobbin is arranged so that its spherical core coincides with the center of vibration of the vibration system. One magnetic pole is arranged so as to extend inside the coil bobbin when it is at the reference position, and each surface of this one magnetic pole and the other magnetic pole opposing it is along a spherical surface with the vibration center as the spherical core. It has a configuration formed on a curved surface.

Hereinafter, an embodiment of this invention will be described with respect to a pickup cartridge C shown in FIGS. 3 to 5. In Fig. 3, 14 is a magnet;
15 and 16 are yokes, and 17 is a pole piece. The pole piece 17 is arranged such that its tip 17a is inserted into a hole 18 formed at the end of the yoke 15, and the outer peripheral surface of the tip 17a, which is one magnetic pole, and the hole 18, which is the other magnetic pole, are disposed. A magnetic gap 19 is formed between the inner surface and the inner surface. In this case, both the outer circumferential surface of the tip portion 17a and the inner surface of the hole 18 are formed into curved surfaces along a spherical surface whose spherical center is the vibration center of a vibration system 20, which will be described later. Further, a suspension wire holder 21 is inserted into the pole piece 17 in the axial direction of the center thereof, and the front end surface 22 of the pole piece 17, including the front end surface of the suspension wire holder 21, is shaped like a concave cone. It is formed. The vibration system 20 includes a cantilever 24 having a needle tip 23 at its tip, a coil bobbin 26 having a coil 25 wound around its outer circumferential surface, a support member 27 that supports the cantilever 24 and the coil bobbin 26, and a support member 27 that supports the cantilever 24 and the coil bobbin 26. base 2
A damper 28 interposed between the rear end surface of the pole piece 7a and the front end surface 22 of the pole piece 17, and a suspension wire 29 that tensions and fixes the support member 27 to the suspension wire holder 21 side via the damper 28.
It is composed of. In this vibration system 20, the above-mentioned members constituting this are arranged on the extension axis of the pole piece 17, and the vibration center is located approximately at the center of the hole 18 in the front-rear direction on the extension axis. It is located. In FIG. 3, the position of the vibration center is indicated by a. Vibration system 20
To further explain, the cantilever 24 is formed into a substantially pipe shape, and the large diameter base 24
a is fitted and fixed to the tip 27b of the support member 27 made of a material such as synthetic resin. The coil bobbin 26 is formed in the shape of a hollow hemisphere, and is arranged so that its center coincides with the vibration center position a, and the edge 26a is located at the magnetic gap 19.
The edge 26b of the hole formed on the front side and facing inside is fixed to the base 27a of the support member 27. Based on this configuration, pole piece 1
The distal end portion 17a of the coil bobbin 26 is arranged so as to extend into the inside of the coil bobbin 26 when the coil bobbin 26 is at a reference position (a position in which no vibration is applied). The coil 25 consists of four coil blocks 25a, 25b, 25c, and 25d to generate stereo left and right signals using a push pull.
As shown in FIG. 4, each coil block 25a, 25b, 25c, 25d is arranged annularly around the extension axis of the pole piece 17 on the outer peripheral surface of the coil bobbin 26 at a position of 45 degrees left and right with respect to the vertical line. As shown in FIG. 5, each coil block 25a, 25b, 25c, and 25d is arranged with a portion thereof facing the magnetic field 19a in the magnetic gap 19. The damper 28 is made of an elastic material such as rubber, and has a surface that contacts the front end surface 22 of the pole piece 17 in a shape corresponding to the front end surface 22, that is, a protruding conical shape. However,
The front end of a suspension wire 29 is fixed to the center of the base 27a of the support member 27, and the rear end of the suspension wire 29 connects to a through hole 30 formed in the axial direction of the center of the damper 28 and the suspension wire. It is inserted and fixed into the holder 21. The suspension wire holder 21
is fixedly held on the pole piece 17 by a set screw 31, and thereby the vibration system 20 is held on the pole piece 17. Further, a viscous fluid such as silicone oil is interposed in the magnetic gap 19 in order to obtain a good damping effect of the vibration system 20 when the vibration system 20 vibrates.

As mentioned above, the pick-up cart cartridge C includes the pole piece 1 that defines the magnetic gap 19.
The outer peripheral surface of the tip 17a of the yoke 15 and the inner surface of the hole 18 formed in the yoke 15 are each formed in a spherical shape with the vibration center position a of the vibration system 20 as the spherical center,
Further, a coil bobbin 26 arranged facing into the magnetic gap 19 is formed into a hollow hemispherical shape with the spherical center at the position a, and furthermore, this coil bobbin 26
6, a coil 25 is arranged in a spherical shape with the position a as the spherical center. Therefore, the coil bobbin 26 and the coil 25 in the vibration system 20
vibrates on a spherical surface with the spherical center at the position a, so the outer peripheral surface of the tip 17a or the hole 18
There is no fear that it will come into contact with the inner surface of the body.

In addition, as in the above-described embodiment, in the support structure of the vibration system 20, the front end surface 22 of the pole piece 17 is formed into a concave conical shape, and the rear end surface of the damper 28 that comes into contact with this front end surface 22 is formed into a protruding conical shape. By forming it in a shape, the center of rotational vibration of the vibration system can be made clear, and modulation distortion can be reduced.

As is clear from the above explanation, according to this invention, the coil bobbin around which the coil of the vibration system is wound is formed into a hollow hemispherical shape, and the spherical core of this coil bobbin becomes the center of rotational vibration of the vibration system. west,
Furthermore, since the opposing magnetic pole surfaces are formed into curved surfaces along the spherical surface with the center of the rotational vibration as the spherical core, it is possible to narrow the interval between the magnetic gaps in which the coil and coil bobbin are arranged. Since the magnetic flux density in the magnetic gap can be increased, the output voltage can be increased.In addition, the coil bobbin can be moved with large amplitude, and the joint surface between the damper and the pole piece can be made conical. As a result, the vibration center of the vibration system is stabilized, so that it is possible to reduce modulation distortion and improve traceability.

[Brief explanation of the drawing]

Figures 1 and 2 are longitudinal sectional side views of main parts of a conventional moving coil type pick-up cartridge;
The figure is a longitudinal sectional side view of a main part of the moving coil type pickup cartridge according to the invention, and FIGS. 4 and 5 are explanatory diagrams showing the arrangement of the coils of the vibration system in the pickup cartridge. 14...Magnet, 15,16...Yoke,
17...Pole piece, 19...Magnetic gap,
20... Vibration system, 25... Coil.

Claims (1)

[Scope of utility model registration request] In a moving coil type pickup cartridge, in which one magnetic pole is arranged around the other magnetic pole, and at least a part of a vibration system coil is arranged in a magnetic gap formed between these two magnetic poles, the one magnetic pole is The front end surface of the constituent pole pieces is formed into a concave conical shape, and on this front end surface,
The vibration system is held via a damper having a conical surface that protrudes to engage with the front end surface, and the coil is wound around a hollow hemispherical coil bobbin, The coil bobbin is arranged so that its spherical core coincides with the vibration center of a vibration system including the coil bobbin, and the one magnetic pole is arranged so as to extend into the inside of the coil bobbin when the coil bobbin is at a reference position. ,
A moving coil type pick-up cartridge characterized in that each surface of the one magnetic pole and the other magnetic pole opposing the magnetic pole are formed into curved surfaces along a spherical surface having the vibration center as the spherical core.