JPS60244196A - Pickup cartridge - Google Patents

Abstract

PURPOSE:To remove magnetic distortions of a generated eddy current and an inductive skin current and so on by forming a non-magnetic metallic coating on a surface of a metallic armature. CONSTITUTION:A surface of an armature 5C is plated with non-magnetic metal Au, and a coating is formed in such condition where the periphery thereof is enveloped. By this metallic plating an eddy current and an inductive skin current on the coating are shorted and eliminated. Accordingly the reproduction tone quality can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a pickup/cartridge metal and a coil bobbin.

[Conventional technology] Pick-ups that apply magnetic force currently occupy the market.
Cartridges come in a wide variety of types, including the electrodynamic moving coil type, the moving magnet type, which is collectively known as the electromagnetic type, the industrial magnet type, the moving iron type, etc., depending on the way the magnetic force is applied. There is a product.

The magnetic circuit of a moving coil type pickup cartridge is shown in FIG. Front yoke 2 and rear yoke are attached to both poles of magnet 1.
The yoke 3 is connected, and the pole piece 4 is further connected to the rear yoke 3. With this configuration, a strong DC magnetic field is formed in the gap formed by the opposing surfaces of the front yoke 2 and the pole piece 4, and the armature 5 is placed within the magnetic field. The armature 5 also constitutes a part of the vibrator, and serves as a winding frame for the generating coil 6, and a cantilever 7 is fixed in the vertical direction from the center thereof. Front yoke small hole 8
A reproducing meter 9 is connected to the other end of the cantilever 7 passing through the cantilever 7, thereby forming a record reproducing vibrator. This vibrator is held by a damper 10 and a suspension wire 11 arranged on the back side of the armature 5, using the pole piece 4 as a base.

With this configuration, when the playback meter 9 follows the sound groove of the record, the transverse waveform of the record causes rotational movement in the armature 5, and a sound current proportional to the angular velocity of this rotation is generated in the generator coil 6 wound around the armature. will occur.

Figure 3 is a schematic diagram of the wound state of the generator coil 6 seen from the front yaw side.The audio output current is IL in the generator coil 6 on the left channel side, and IL on the right channel side. In the generating coil 6-R, each is expressed as IR.

Generally, the armature 5 is made of a magnetic material with high magnetic permeability such as permalloy, but in an electrodynamic type called an air-core coil, a non-magnetic lightweight metal such as aluminum is used.

In either method, since alternating currents rL and IR flow on the surface of the armature 5, eddy currents 114. are generated on the skin surface of the armature 5 as shown in FIG. and ilR will occur, respectively. In general, it can be said that armatures made of magnetic materials generate stronger eddy currents than armatures made of non-magnetic materials.

[Problems to be solved by the invention] These eddy currents i1 and iIB are the audio output currents IL, respectively.
Since it is generated in a direction that obstructs the flow of IR and IR, it acts as a magnetostrictive force on the output signal, increasing the distortion of the reproduced sound quality, and exhibiting transient characteristics with a slow response, which significantly impairs the auditory balance.

Furthermore, when an armature made of magnetic material is used, as shown in FIG.
Due to the change in the rotational direction of the armature 5, the distance between the front yoke 2 and the pole piece 4 changes, and the magnetic flux density within the DC magnetic field partially increases or decreases.

This is because the permeance of the magnetic circuit that is constructed around the magnet 1 changes, and the magnetic flux in the magnetic circuit changes due to the rotational movement of the armature 5. This causes an induced skin current IM on the surface of the armature 5.
occurs, the magnetic resistance of the magnetic circuit increases, and dynamic distortion as magnetostriction occurs in the reproduced output, which also significantly impairs transient characteristics and auditory balance.

[Object of the Invention] An object of the present invention is to eliminate magnetostriction such as eddy currents and induced skin currents generated in the metal armature.

[Embodiment] FIG. 1 shows a moving coil type pickup cartridge having a metal coil bobbin according to the present invention. Each part corresponds to FIG. 2, but the surface of the armature 5C is plated with Au, which is a non-magnetic metal, and a film is formed surrounding it. Due to this metal plating, the eddy current and induced skin current are short-circuited and dissipated on the coating surface. Other non-magnetic metals include AI, Cr, Cu, In, A(],
Examples include Sn.

[Effects of the invention] Since the electrodynamic pickup cartridge uses the induced electromotive current of the generator coil generated in a strong DC magnetic field as its audio output, it eliminates harmful eddy currents and skin damage generated in the metal armature. By eliminating the current, it directly affects the sound quality of the cartridge, creating a natural sound quality with no distortion, a deep lingering sound, and a wide dynamic range, while also flattening the auditory balance and making it clearer. This results in an effect of unprecedented high fidelity reproduction, such as high-fidelity reproduction sound.

As described above, the present invention improves reproduced sound quality by eliminating eddy currents and conductive skin currents generated in the metal armature of an electrodynamic pickup cartridge.

[Brief explanation of drawings]

1 is a schematic side view of a magnetic circuit according to the invention, FIG. 2 is a schematic side view showing a moving coil type magnetic circuit, FIG. 3 is a schematic front view showing the armature and the generating coil, and FIG. The figure is a schematic diagram showing eddy currents generated in the armature, and FIG. 5 is a schematic side view showing changes in the amount of magnetic flux in the magnetic circuit. 1: Magnet 2: Front yoke 3: Rear yoke 4: Ball piece 5 near-mature 6: Generating coil 7: Cantilever 8: Front yoke small hole 9: Regeneration needle 10: Damper 11: Suspension wire 6-shi = left Channel side power generation coil 6-1? : Right channel side generating coil IL: Left channel side audio output current IR: Right channel side audio output current lrL: Eddy current 1, R generated by the left channel side generating coil: Eddy current IH generated by the right channel side generating coil: Induced skin current 5C: Armature with non-magnetic metal. Patent applicant Namiki Precision Jewel Co., Ltd.

Claims (1)

[Claims] An electrodynamic pickup cartridge characterized in that a non-magnetic metal coating is formed on the surface of a metal armature.