JPS5928119B2 - Electromagnetic cartridge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a pickup cartridge used for record reproduction, particularly an electromagnetic cartridge.

Generally, electromagnetic pickups are classified into three types: moving magnet type, moving coil type, and moving iron piece type.

The movable magnet type is widely used due to its advantages such as high output and ease of assembly, but there are restrictions on reducing the equivalent mass, and the high electrical impedance leaves problems such as deterioration of electrical system transmission performance. was.

The moving coil type has manufacturing difficulties such as the method of drawing out the coil and winding method, the difficulty of replacing the needle, and the need for a step-up transformer due to the small output voltage. There was a problem.

The movable iron piece type has the problem that the linearity of the output signal with respect to the displacement of the vibrator due to the magnetic saturation of the magnetic circuit may deteriorate, and at the same time, the output voltage may decrease.

The present invention is an improved version of the above-mentioned electromagnetic car (IJ), and its purpose is first to improve the characteristics by using a soft magnetic material for the vibrator and reducing the uniformity of the vibration system. It's about trying.

The second objective is to improve electrical transmission characteristics.

Thirdly, the linearity of magnetic flux change with respect to needle tip displacement is improved,
The purpose is to prevent magnetostriction.

The fourth point is to obtain a sufficient induction S/N ratio.

Fifth, the objective is to simplify the component parts, make the manufacturing process easier, and improve processing and assembly accuracy.

The present invention will be described in detail below with reference to figures showing examples.

FIG. 1 shows the structure of an electromagnetic cartridge according to the present invention, and three types of structures with different arrangements of permanent magnets in the magnetic circuit are shown as A, B, and C, respectively.

Figures 2 and 4 show the principle of operation of the electromagnetic cartridge of the present invention in a flat type vibrator and a cylindrical type vibrator, with reference to Figure 1B. B represents the operating state with respect to displacement, B represents the operating state when no displacement is applied, and C represents the operating state with respect to the displacement of the vibrator when the positioning needle is displaced upward.

FIG. 3 shows the relationship between the change in the magnetic flux direction inside each pole piece and the needle tip displacement of the electromagnetic cartridge according to the present invention, where A shows the change in the second magnetic circuit, and B shows the change in the second magnetic circuit. The change C represents the relationship between the change inside the intermediate pole piece of the first and second magnetic circuits and the resultant magnetic flux change.

FIG. 5 shows an embodiment of the electromagnetic cartridge according to the present invention, in which A shows a partially sectional perspective view and B shows a front view.

FIG. 6 shows a front view of a flat vibrator that can be used in an electromagnetic cartridge according to the present invention, and FIG. 7 shows a side view of a cylindrical vibrator.

(Hereinafter, the electromagnetic car according to the present invention)
Figure B will be explained in detail.

In FIG. 1B, reference numeral 2 denotes a cantilever with a positioning needle 1 fixed at its tip, and a vibrator 3 made of a flat (or cylindrical) soft magnetic material, etc., which has a vibration fulcrum position 4 approximately at its rear end. are fitted and fixed.

5a, 5b, 5c, and 6ct are permanent magnets made of hard magnetic materials with the same size and magnetic properties,
Permanent magnet 5a.

One end of the pole piece 7b made of a soft magnetic material or the like is connected to the permanent magnet 6c by the opposing surfaces of the different magnetic poles of the magnet 6b.
, 6d are sandwiched and pressed against one end of a pole piece 7e made of a soft magnetic material or the like by the opposing surfaces of the different magnetic poles.

The other ends of the pole pieces 7b and 7e are on a line that is perpendicular to the axial direction of the cantilever 2 and passes through the vibration fulcrum position 4, and are arranged adjacent to the vibrator 3.

Permanent magnets 6a, 6 with which the pole piece 7b is sandwiched and pressed together
A pole piece 7 made of soft magnetic material is attached to the magnetic poles at both ends of b.
One ends of a and γC are pressed together, and the other ends are arranged at symmetrical positions in the figure with the pole piece 7b as the center, and 7a is at one end of the vibrator 3 on the position needle 1 side, and 7c is at the rear end of the vibrator 3. are arranged adjacent to each other.

On the other hand, the permanent magnet 5 with which the pole piece 7e is held and pressed together
c.

One end of pole pieces 7d and 7f made of a soft magnetic material or the like is pressed into contact with the magnetic poles at both ends of 6d, and the other end is placed at a symmetrical position in the figure with pole piece γe as the center, and is located on the holder 1 side of the vibrator 3. 7d is arranged adjacent to one end, and 7f is arranged adjacent to the rear end of the vibrator 3.

The two permanent magnets 6a, 6b and the three pole pieces 7
a, 7b, and 7c, the two permanent magnets 6c, 6d, and three pole pieces 7d, 7e.
.

The second magnetic circuit composed of 7f is placed at a symmetrical position with respect to the central axis of the cantilever 2.

8a. 8b is a coil wound around the pole pieces 7b and 7e, and is connected to effectively generate electricity.

FIG. 5 shows a stereo structure in which two sets of magnetic circuits having the above structure are arranged with the tips of the pole pieces deviating from each other in 49 directions with respect to the vertical axis.

In addition, as shown in FIGS. 6 and 7, the transducer 31/'i is symmetrical to the central axis of the cantilever 2, and as shown in FIGS.
Any device that can realize the operation shown in the figure can be adopted.

Next, the operation of the electromagnetic cartridge according to the present invention will be explained in detail with reference to FIGS. 2 and 3.

When the needle tip is not displaced in FIG. 2B, the vibrator 3 is on the line connecting the pole pieces 7b and 7e, and therefore there are four gaps between the pole pieces 7a and γb, γb and γC, 97d and γe, and γe and 7f. The permanent magnets 5a must have the same magnetic resistance.

As shown in the figure, an equal constant DC magnetic flux Φ flows from 6b, 6c, and 6d into each magnetic path. At this time, inside the pole piece 7b, an upward magnetic flux Φ from the permanent magnet 6a and an upward magnetic flux Φ from the permanent magnet 6b are flowing. Since the downward magnetic fluxes Φ cancel each other out, no magnetic flux flows through the coil 8a.

No electricity is generated.

The magnetic fluxes Φ from the permanent magnets 6c and 6d still cancel each other inside the pole piece 7e, so no magnetic flux flows and the coil 8b does not generate electricity.

In FIG. 2A, the needle tip is displaced downward, and the vibrator 3 is moved between the pole pieces 7a and γb1 and the pole pieces γe and 1.
When approaching the gap f, the gap magnetic resistance decreases, and a magnetic path from the permanent magnet 6a of the first magnetic circuit to the pole piece 7a-air gap vibration-7-3-air gap-ball piece 7b is Φ.
A magnetic flux of +△Φ flows and straddles the permanent magnet 6 of the second magnetic circuit.
From d, a magnetic flux of Φ10ΔΦ flows in a magnetic path from pole piece 7e to air gap, vibrator 3, air gap, and pole piece 7f.

- On the other hand, the magnetic resistance in the gap between pole pieces 7d and 7e increases as the vibrator moves away from the permanent magnets 6b and 6.
The magnetic flux flowing from c to the pole piece decreases to Φ-ΔΦ.

Therefore, an upward magnetic flux of composite magnetic flux = (Φ + △Φ) - (Φ - △Φ) = 2 △Φ flows inside the pole piece 7b located in the middle, and the composite magnetic flux = ( Since an upward magnetic flux of Φ1△Φ)−(Φ−ΔΦ)=2ΔΦ flows, power is generated in the coils 8a and 8b.

When the needle tip is displaced upward in FIG. 2C, the amount of magnetic flux flowing in each magnetic path changes as in FIG. A downward magnetic flux of 2ΔΦ flows also in the pole piece 7e of the dual magnetic circuit, and a voltage in the opposite direction to that in case A is induced in the coils 8a and 8b.

FIG. 3A shows changes in the magnetic flux flowing inside the pole pieces 7a, 7b, and 7e in the first magnetic circuit shown in FIG.
This is twice as much as in a and 7c, improving the linearity of the magnetic flux change with respect to the needle tip displacement, and improving the conversion efficiency.

FIG. 3B shows changes in magnetic flux inside each pole piece for the second magnetic circuit.

Figure 3C shows the change in magnetic flux with respect to the displacement of the tips of the pole pieces 7b and 7e, and also shows the amount of change in the combined magnetic flux obtained by combining the changes in the magnetic flux inside the two pole pieces by connecting the coils 8a and 8b. This corresponds to the magnitude of the voltage induced in the coil.

That is, in this structure, the voltage induced in the coil is the pole pieces 7a, 7c, and 7d.

It is possible to obtain about four times the amount of change in magnetic flux within 7f, and still obtain about twice that of pole pieces 7b and 7e, so prevention of distortion and improvement in output voltage can be expected.

That is, according to the present invention, first, a soft magnetic material can be used for the vibrator, and the equivalent mass of the vibrating system can be reduced and the characteristics can be improved.

Second, the electrical impedance can be kept low due to the structure, and the electrical transmission characteristics can be improved.

Thirdly, since the structure is such that direct current magnetic flux does not flow through the pole piece around which the coil is wound, deterioration of linearity and decrease in output voltage due to magnetic saturation can be prevented.

Furthermore, since the conversion efficiency is structurally good, reduction in magnetostriction and improvement in output voltage can be expected.

Fourth, by adopting a structure like the embodiment shown in Fig. 5, even if induced magnetic flux is applied in the vertical direction in the figure, the generated current can be canceled out by connecting the coils, so that the induced S /N ratio can be improved.

Fifth, the components of the magnetic circuit can be simplified and the processing of the parts
Assembly accuracy can be improved.

[Brief explanation of the drawing]

FIG. 1 shows a structural diagram of an electromagnetic cartridge according to the present invention, showing three types of structures A, B, and B with different arrangements of permanent magnets.
It is expressed in C. FIG. 2 shows the principle of operation in a flat type vibrator of the electromagnetic cartridge according to the present invention shown in FIG. 1B. FIG. 3 shows the relationship between the change in the magnetic flux direction inside the intervening pole piece and the displacement of the needle tip for the electromagnetic cartridge according to the present invention in FIG. The change in the circuit, C, shows the relationship between the change inside the intermediate pole piece of the first and second magnetic circuits and the resultant magnetic flux change. FIG. 4 shows the principle of operation in a cylindrical vibrator of the electromagnetic cartridge according to the present invention shown in FIG. 1B. FIG. 5 shows the principle of operation of the cylindrical vibrator with respect to FIG. 1B of the electromagnetic car according to the present invention. FIG. 5 shows an embodiment of the electromagnetic cartridge according to the present invention, in which A shows a partially sectional perspective view and B shows a front view. FIG. 6 shows a front view of a flat vibrator that can be used in an electromagnetic cartridge according to the present invention. FIG. 7 shows side views of a cylindrical vibrator that can be used in the electromagnetic cartridge according to the present invention. 1...Original needle, 2...Cantilever, 3
...Curved oscillator, 4...Vibration fulcrum position, 5...
...Viscoelastic support, 6 =...Permanent magnet, (6
a, 6b, 6c, 6d), 7... tune pole piece (7a
, 7b, 7c, 7d. 7e, 7f), 8... Coil (8a, 8b).

Claims (1)

[Scope of Claims] 1. A vibrator composed of a cantilever 2 to which a positioning needle is fixed at one end and a vibrator 3 made of a soft magnetic material having a vibration fulcrum position 4 approximately at its center end is fitted and fixed to the other end. It has two permanent magnets 6a and 6b and is pressed against different magnetic pole surfaces of the permanent magnets 6a and 6b, and the end thereof is perpendicular to the two axial directions of the cantilever and on a line passing through the vibration fulcrum position 4. A first pole piece 7b made of a soft magnetic material and arranged adjacent to the vibrator 3, and the permanent magnet 6.
The first pole piece 7 is pressed against the magnetic poles at both ends of a and 6b.
Second and third pole pieces 7a and 7c are arranged symmetrically front and rear with respect to b and adjacent to both ends of the vibrator 3, respectively.
a first magnetic circuit consisting of a first magnetic circuit, two permanent magnets 6c,
6d and three fourth, fifth, and sixth pole pieces 7e, 7d, and 7f made of soft magnetic material form a second magnetic circuit having the same structure as the first magnetic circuit, and a second magnetic circuit having the same structure as the first magnetic circuit; 4
It has two coils 8a and 8b which are wound around pole pieces 7b and 7e of which are wound in different winding directions and connected in series, and which are connected to the first, second and third poles of the first magnetic circuit. The ends of the pieces 7b, 7a, 7c and the fourth, fifth, and sixth pole pieces 7e of the second magnetic circuit. 7d and 7f are arranged at symmetrical positions with respect to the central axis of the vibrator 3, and the vibrator 3 of the vibrating system
is displaced, magnetic flux flows through the first and fourth pole pieces 7b and 7e, and the coils 8a and 8b
An electromagnetic cartridge that generates electricity.