JPH021997Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an MC type pick-up cartridge having an electromagnetic braking effect.

As shown in Fig. 1, the conventional MC type pick-up cartridge has yokes 2a and 2b fixed to both ends of a magnet 1, and a pole piece 3 fixed to one yoke 2a and the other yoke 2b. A magnetic gap 4 is formed, a cantilever 5 is fixed to the center, and a winding frame 7, in which the generating coils 6L and 6R are wound so that their winding axes are perpendicular to each other, is positioned in the magnetic gap and is inserted through a damper 8. It has a structure in which it is supported by the pole piece 3 so that it can freely vibrate. Damping of such a vibration system is determined by the mechanical properties of the damper (rubber) 8, the compression state, and the contact area with the reel 7, but damping by the damper 8 alone is insufficient to damp the vibration system. Furthermore, since the viscoelasticity of the damper material (rubber) has frequency characteristics, it is not possible to effectively suppress the resonance of the vibration system, and it is not possible to obtain flat frequency characteristics.

Generally, the characteristics of an MC type pickup cartridge, including the tone arm that supports the cartridge body, can be expressed as follows.

Characteristics of high-pitched sounds In the high-pitched range, the mass ma of the cartridge vibration system, the elasticity sr of the record, and the elasticity sb of the supporting part of the reel 7 (damper 8) cause resonance, and the mass ma vibrates greatly, showing a resonance peak. . This is called treble resonance, and its frequency h is is given by the solid line in FIG.

Characteristics of Bass Range In the bass range, the tone arm mass mt and the elasticity sb of the support portion (damper 8) of the winding frame 7 cause resonance, and the mass mt vibrates greatly, exhibiting a resonance peak. This is called bass resonance, and its frequency l is is given by the solid line in FIG.

In other words, the MC type pick-up cartridge exhibits resonance peaks at the high-pitched resonance frequency h and the low-pitched resonance frequency l, and has the characteristics as shown by the solid line in Figure 5.
As described above, damping using only the damper 8 that constitutes the support portion of the winding frame 7 cannot effectively suppress the resonance of the vibration system, making it impossible to obtain flat frequency characteristics.

The present invention is an improvement on such conventional drawbacks, and will be explained below with reference to the drawings.

To explain in FIG. 2, the rectangular winding frame 7
The generating coils 6L and 6R of the left and right channels are wound around the mutually orthogonal ends of the coil so that their winding axes are orthogonal to each other, and the short coils 9 and 9 are wound around the remaining ends that are orthogonal to each other. be.

FIGS. 3 and 4 show other embodiments, and FIG. 3 shows arm portions 7L of a cross-shaped winding frame 7 that are perpendicular to each other,
7R, left and right channel generator coils 6L, 6R
, and the remaining arm portions 7L′, which are orthogonal to each other.
It has a structure in which short coils 9, 9 are wound around the winding frame 7R', and FIG. However, it has a structure in which a short coil 9 is wound around the remaining arm portion.

In the above structure, the winding frame 7 vibrates in the magnetic gap 4.
Since it has a structure in which the short coil 9 is wound around the
The short coil 9 has a magnetic flux density B of the magnetic gap 4,
A back electromotive force proportional to the length l and speed ν of the coil is induced. A current flows through the short coil 9 due to this back electromotive force, and this current causes the short coil 9 to reduce the above back electromotive voltage.
A force acts to suppress the vibration of the winding frame 7. That is, the vibration of the winding frame 7 is damped by the back electromotive force induced in the short coil 9. This braking force is proportional to the induced back electromotive force, and this back electromotive force is proportional to the speed ν of the shot coil 9, that is, the speed of the winding frame 7. Therefore, this back electromotive force, that is, the braking force is proportional to the high-pitched resonance frequency h, It reaches its maximum near the resonance peak of the bass resonance frequency l. Therefore, according to the present invention, in addition to the damping effect provided by the damper 8, the short coil 9
Since the electromagnetic damping effect is added, the vibration system is sufficiently damped, and the above electromagnetic damping reaches its maximum near the resonance peaks of the high-pitched resonance frequency h and the low-pitched resonance frequency l, effectively suppressing both resonance peaks. Therefore, an effective damping effect can be obtained over the entire frequency band. Therefore, as shown by the dotted line in FIG. 5, the resonance of the vibration system, particularly the resonance at the high-pitched resonance frequency h and the low-pitched resonance frequency l, is effectively suppressed, resulting in the advantage that flat frequency characteristics can be obtained.

[Brief explanation of the drawing]

Figure 1 shows the structure of a conventional MC type pick-up cartridge, and Figures 2 to 4 show the structure of a conventional MC type pick-up cartridge.
FIG. 5 is a diagram showing the main parts of the MC type pickup cartridge, and FIG. 5 is a diagram showing the frequency characteristics of the conventional example and the present invention. 1 is a magnet, 2a and 2b are yokes, 3 is a pole piece, 4 is a magnetic gap, 5 is a cantilever,
7 is a winding frame, 8 is a damper, 6L and 6R are power generation coils, and 9 is a short coil.

Claims (1)

[Scope of utility model registration request] Yokes 2a and 2b are fixed to both ends of the magnet 1, a magnetic gap 4 is formed by a pole piece 3 fixed to one yoke 2a and the other yoke 2b, and a winding frame 7 with a cantilever 5 fixed to the center is formed. In a structure in which the magnet is placed in the magnetic gap 4 and supported to vibrate freely on the pole piece 3 via the damper 8, the generator coils 6L and 6R are wound around the winding frame 7, and a short coil 9 is also wound around the winding frame 7. MC type pick-up cart cartridge.