JPS5915188Y2 - Magnetic circuit for MC type cartridge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic circuit for a moving coil (hereinafter referred to as MC) type cartridge in a record player.

The applicant has previously developed an extremely good first channel that is lightweight, provides high output, and does not cause crosstalk between both channels.
We have proposed a printed coil for MC type cartridges as shown in Figures and Figure 2.

That is, FIG. 1 shows a surface view of the printed coil, and in the center of the substrate 1 there is a hole 1a for fixing the cantilever.
is formed, and on the right side there is a semicircular coil 2,
On the left side, a semicircular coil 3 is formed which is wound in the opposite direction to the coil 2.

Then, the winding centers 2 a and 3 a of both coils 2 and 3 are connected, and output is taken out from their outer winding ends 2 b and 3 b.

Figure 2 shows the back side from the front side with the coils 2 and 3 in the front view of Figure 1 removed, and the pattern on the front side is rotated 90 degrees to the left as it is. Coils 2' and 3' are printed.

In the above, if the area outside the two-dot chain line in FIGS. 1 and 2 is located within the magnetic gap, and the magnetic field is configured to flow perpendicularly to the plane of the paper in the depth direction, the printed coil
When the coils 2 and 3 move in the direction of the arrow, an electromotive force is generated in the direction of the arrow, and this electromotive force is caused by the connection of the winding centers 2a and 3a,
The added state appears between the winding outer ends 2b and 3b.

Furthermore, when moving in the L' direction, an electromotive force is generated in the direction opposite to the arrow.

As described above, by vibrating in the L and L' directions, a corresponding electromotive force can be obtained.

Note that when R and R' vibrate in the forward direction, the upper and lower parts of the coils 2 and 3 cut the magnetic flux, producing an electromotive force, but this electromotive force is canceled out, so the outer end 2b, No output appears between 3b.

On the other hand, since the coil on the back side has a pattern with an angular difference of 90 degrees, the electromotive force when R and R' vibrate in the forward direction is added and output is output at the outer winding ends 2'b and 3'b. The electromotive force generated when vibrating in the L and L' directions is canceled out.

Therefore, vibrations in the L and L' directions occur only at the outer ends 2b and 3b of the coils 2 and 3 on the front surface, and vibrations in the R and R' forward directions occur only at the outer ends 2'b of the coils 2' and 3' on the back surface. , 3'b, respectively, and no crosstalk occurs between the front and back coils.

Therefore, the printed coil A is incorporated into a magnetic circuit as shown in FIG. 3 so as to apply a magnetic field to the outer coil part from the two-dot chain line. At the surfaces 5a and 6a, a magnetic flux distribution occurs as shown in the figure, and therefore the printed coil A
Magnetic flux also flows inside the two-dot chain line, and the printed coil A
An electromotive force is generated in the opposite direction, reducing the overall output.

Furthermore, since the magnetic flux of the printed coil A toward the outside of the two-dot chain line is relatively reduced, the decrease in output is further exacerbated.

Note that 7 is a cantilever to which a stylus tip (not shown) is attached to the tip, 8 is a damper, and 9 is a holder that supports the cantilever by a suspension wire (not shown).

The present invention focuses on the above-mentioned drawbacks of the magnetic circuit, and aims to provide a magnetic circuit that eliminates the above-mentioned problems by concentrating magnetic flux only in the magnetic gap.

Hereinafter, one embodiment of the present invention will be described. In FIG. 4, 10 is a magnet), 11.12 is a yoke, and the tip of the yoke 11.12 has a circular hole 11a in which a cantilever, a holder, etc. are located; 12a are formed concentrically, and a ring-shaped pole piece 13 is formed inside the tip of the pole piece 12a.
．． 14 are attached concentrically leaving a gap 15.

The pole pieces 13 and 14 are made of a magnetic material with a high saturation magnetic flux density, such as an Fe--Co alloy, and rings 16 and 17 made of a magnetic material are attached to the inner circumference thereof.

The rings 16 and 17 are made of a material with a low saturation magnetic flux density, such as S-15C.

In the above, the magnetic flux from the magnet 10 is
, 12, When the magnetic flux flows through the pole pieces 13, 14 and the rings 16 and 17, the rings 16 and 17 are saturated with a certain magnetic flux density, so no more magnetic flux passes through them, and only passes through the pole pieces 13 and 14. It becomes like this.

Therefore, if a static magnetic flux greater than that which saturates the rings 16 and 17 is applied by the magnet 10, the magnetic flux density at the gap 15 will be as shown in FIG.
The magnetic flux density of the ring-shaped opposing portion (magnetic gap) a of 3.14 is large, and the difference from the magnetic flux density of the inner peripheral portion a is extremely significant.

Therefore, if the outer circumferential portion of the printed coil is located at the opposing portion a, the above-mentioned conventional problems will not occur, and a large output voltage can be obtained.

In addition, although the pole pieces 13, 14 and the rings 16, 17 are ring-shaped in the above description, they may be divided into a plurality of pieces in the circumferential direction.

From the above, according to the present invention, there is a large difference in magnetic flux density between the part of the magnetic gap where the pole pieces face and the part of the gap corresponding to the inner circumference of the pole piece, that is, the magnetic flux density of the former part is higher than that of the latter. Since it is sufficiently large in comparison, a large output voltage can be obtained by locating the part of the generating coil that is effective for power generation in the magnetic gap, and locating the other part in the gap corresponding to the inner circumference of the pole piece. You will be able to do this.

[Brief explanation of the drawing]

Figure 1 is a front view of the printed coil, Figure 2 is a view from the front to the back, Figure 3 is a diagram of a conventional power generation mechanism, Figure 4 is a diagram of the magnetic circuit of this embodiment, and Figure 5 is a diagram of the magnetic circuit of this embodiment. BB' in Figure 4
It is a magnetic flux density characteristic diagram of a wire. 13.14...Pole piece, 16.17...
...A ring of magnetic material.

Claims (1)

[Scope of utility model registration request] A substrate with a hole for fixing the cantilever formed in the center, and a circular arc portion on the outside at a symmetrical position with respect to the hole on one side of the substrate, the centers of the windings are interconnected, and the output is taken out from the outer end of the winding. semicircular coils formed in opposite directions, and semicircular coils formed on the other surface of the substrate with the coils on the one surface rotated by 90 degrees about the hole. In the MC type cartridge equipped with a moving coil consisting of a coil, pole pieces through which magnetic flux from the magnet flows are opposed to each other, and the circular arc portion of the semicircular coil is positioned between the opposing surfaces of the pole pieces. A magnetic circuit for an MC type cartridge, comprising a gap formed therein and a magnetic material having a saturation magnetic flux density lower than that of the pole piece provided on the inner wall of at least one pole piece.