JPS5938797Y2 - Magnetic circuit of pick-up cartridge - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a magnetic circuit applied to a power generation section of a pickup cartridge (hereinafter abbreviated as "cartridge") for reproducing records.

A magnetic circuit used in a conventional cartridge is constructed by overlapping a U-shaped yoke and a pair of pole pieces connected to a cylinder, and a coil is arranged around this overlapping portion.

With this configuration, the pole pieces cannot be overlapped after the coil is wound around the yoke, so
The coil is wound around a bobbin having a predetermined center hole, and an assembly procedure is adopted in which a yoke and a pole piece are inserted and overlapped within the center hole of the bobbin.

This requires a complicated process of winding a coil around a bobbin and assembling this coil with a yoke and pole piece.In addition, the bobbin that exists between the coil and yoke obstructs the magnetic coupling between them, resulting in the reproduction frequency characteristics In particular, this causes a phenomenon in which the output voltage decreases.

That is, to explain the prior art in detail using FIG. 6, in the magnetic circuit used in the conventional cartridge, the yoke 21 and the pole piece 22 must be overlapped within the center hole of the coil bobbin 25.

At this time, since the pickup cartridge is small (the pole piece, yoke, etc. are only about 4 to 6 mm and 8 degrees), the assembly work is extremely difficult.

When combining them, put the pole piece 22 on one side (for example, the right side) as shown in Figure 6, and then move the yoke 21
must be inserted into the bobbin 25.

At this time, there are 25 or 2 coil bobbins, so yoke 21
must be placed on the same side of pole piece 22.

Therefore, it is extremely difficult to hold the two bobbins on the same side and insert the yoke there.

Since the small pole piece 22 and yoke 21 are in contact with each other on only one side, if the center hole of the bobbin 25 is large, a space (gap) will be created between them, increasing magnetic resistance and reducing efficiency. decreases.

This idea allows the coil to be wound directly on the yoke,
Therefore, it is an object of the present invention to provide a magnetic circuit that can eliminate the above-mentioned drawbacks regarding assembly work and frequency characteristics.

An embodiment of this invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 indicates a U-shaped yoke, and reference numeral 2 indicates a pair of pole pieces integral with the cylinder.

As shown in FIG. 2, the two open ends of the yoke 1 are each formed with a recess 1a that opens at the end surface.

When the yoke 2 is made of ferrite, it is impossible to form it with a recess 1a having such a shape, and the pole piece 2 is inserted into the recess 1a, and the cartridge is inserted therein. A magnetic circuit is constructed.

The most suitable shape for the recess 1a is a blind hole as shown in Fig. 3, but if it is difficult to form the recess 1a due to various conditions, it may be necessary to have both sides exposed to the outside as shown in Fig. 4. It may be in the form of a communicating slit.

The structure shown in FIG. 2 can be easily assembled by stacking the thin plate 11 having the shape shown in FIG. 5A and the thin plate 12 provided with the notch 12a as shown in FIG. 5B. can be realized.

In the magnetic circuit configured in this way, the pole screw 2 is
In order to be inserted into the recess 1a opened in the end face of the yoke 1, it is possible to combine the chini yoke 1 in which the coil 4 is wound around the yoke 1 and the pole piece 2.

Therefore, the coil 4 can be wound directly onto the yoke 1 without using a bobbin, and the magnetic loss between the yoke 1 and the coil 4 is greatly reduced, resulting in significant improvements in power generation efficiency and frequency characteristics. be related to

This is because when the pole piece 2 is coupled to the yoke 1 on the top and bottom or left and right surfaces, the magnetic coupling area increases, magnetic loss is reduced, and eddy currents due to the coupling surface can be removed by the laminated yoke. have

Particularly in the case of a solid yoke, the magnetic flux tends to flow to the edge portion of the recess 1a, making it difficult for magnetic coupling to increase, but by stacking the yoke, the magnetic flux flows uniformly.

Further, since it is only necessary to insert the pole piece 2 into the yoke 1, assembly can be performed regardless of the position of the coil 4.

Even if there are two pole pieces 2, work efficiency is greatly improved compared to the conventional method.

and at least both sides of pole piece 2 and yoke 1
Since they are in contact with each other, the magnetic resistance can be lowered.
Even if a gap is created between one surface, the magnetic resistance will not increase because the other surface is in contact.

[Brief explanation of the drawing]

Fig. 1 is an exploded plan view of a magnetic circuit according to an embodiment of the invention, Fig. 2 is a perspective view of the yoke, Fig. 3 is a sectional view thereof, and Fig. 4 is a sectional view of another yoke. , Figure 5A
, B are plan views of thin plates used to construct the yoke. FIG. 6A9 shows an exploded plan view of a conventional magnetic circuit. DESCRIPTION OF SYMBOLS 1... Yoke, 1a... Recess, 2... Pole piece, 3... Cylinder 11... Thin plate, 12...
Thin plate, 12a...notch.

Claims (1)

[Scope of utility model registration request] A U-shaped yoke 1 made of laminated thin plates, and this yoke 1
The yoke 1 consists of a pair of pole pieces 2 coupled to the yoke 1 and a coil 4 provided on the outer periphery of the yoke 1, and the yoke 1 has a yoke 11 extended by a U-shaped end face and a recess 1a opening at the end face. A magnetic circuit for a pickup cartridge, characterized in that the pair of pole pieces 2 are respectively inserted into recesses 1a of the yoke 1 after a coil 4 is provided on the yoke 1.