JPS6059800B2 - Electromagnetic pick-up cartridge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the material structure of a magnetic circuit in a so-called electromagnetic pickup such as a moving magnet type, moving coil type, or moving iron type that utilizes electromagnetic action in a power generation mechanism, and particularly relates to the material structure of a magnetic circuit in a so-called electromagnetic pickup such as a moving magnet type, moving coil type, or moving iron type that uses electromagnetic action in a power generating mechanism. This invention relates to an electromagnetic pickup cartridge that uses a laminate of materials and has a magnetic circuit mainly consisting of a yoke and a ball piece.

Permalloy, which has relatively good magnetic properties and is easy to process and form, has been widely used as a material for magnetic circuits, but recently ferrite has been used because permalloy has a large overcurrent loss. It became.

However, while ferrite as this type of material has excellent electromagnetic properties, it has extremely poor workability, and as the shapes of the parts used become more complex and fine, the defect rate is high and the price is high. It was only used in high-end products, with a relatively simple-shaped yoke made of ferrite, and a complex-shaped pole piece made of a laminate of permalloy thin sheets. In addition, pole pieces using permalloy laminates are made by press-molding thin plates and then gluing and laminating them with varnish, epoxy resin, etc., and the manufacturing process involves managing the thickness of the adhesive layer and handling the fine thin plates. The process was becoming complicated.

In particular, when attempting to insert plastic into a pole piece made of a laminated board bonded with varnish, epoxy resin, or the like, it would peel off due to heat or mechanical adhesion, resulting in an inconvenience.
The present invention has been made in view of the above points, and an object thereof is to provide an electromagnetic pickup cartridge that is easy to mold and has a magnetic circuit using a laminated plate with excellent magnetic properties. be. The present invention will be explained in detail below with reference to the drawings showing one embodiment thereof. FIG. 1 is a cross-sectional view of a permalloy laminated plate that will become a laminated yoke and a laminated ball piece, showing an embodiment of the present invention. It is a permalloy laminate that is closely welded by forming.

As shown in FIG. 2, the method for producing this permalloy laminate p is to first apply boron powder to both or one side of the permalloy thin plates 1A, 1B, and 1C, or deposit a boron material by chemical vapor deposition (CVD). ), etc. After forming the boron layer 3, the permalloy thin plates 1A, 1B, and 1C are stacked and brought into close contact with each other, and while applying light pressure, the boron layer 3 is heated to a heat treatment temperature of 6.
By performing heat treatment at 00 to 1000°C for a treatment time of 30 to 6 minutes, the boron material of the formed boron layer 3 diffuses into the permalloy thin plates 1A, 1B, and 1C, and close welding is performed. You can get it.

Note that in this heat treatment, it is preferable that the atmosphere be hydrogen or vacuum.

The heat treatment step can also be performed simultaneously with the annealing of the permalloy material. That is, a boron layer 3 is formed on the surfaces of the rolled permalloy thin plates 1A, 1B, and 1C, and after being heated to a temperature of 1000 to 1200°C, it is heated at a rate of about 100°C/Hr from that temperature to 500°C. If the temperature is lowered, diffusion welding can be performed simultaneously with annealing. In addition, the boron diffusion region diffused into the permalloy laminate Ω does not need to be formed over the entire thickness direction of the permalloy thin plates 1A, 1B, and 1C, but from several μm to the permalloy thin plate surface.
The thickness may be about several tens of microns, and if necessary, it may be applied only to a part of the surface of the permalloy thin plate. The permalloy laminate thus obtained is processed and formed into the desired shape of each member such as the laminate yoke and ball piece that constitute the magnetic circuit of the pickup cartridge by means such as pressing or etching.

The laminated magnetic material in which the boron diffusion region is formed is
Since the specific resistance of diffused boron is high, it has a sufficiently high resistance value, making it difficult for eddy current loss to occur, and since a diffusion region is formed on the bonding surface, mechanical strength and
Thermal strength is very high, which makes it easier to mold into a desired shape, and it is also convenient to insert into plastics etc. if necessary.

As explained above, by using the laminated magnetic material according to the present invention in the magnetic circuit of a pickup cartridge such as a yoke or a ball piece, the following effects can be obtained.

First, since there is little eddy current loss, the frequency characteristics (especially high frequency characteristics) and output sensitivity of the pickup cartridge are greatly improved.

Next, since it has excellent mechanical strength and heat resistance, it can be formed into a laminated magnetic material and then molded by pressing or etching, which simplifies the process and allows for highly accurate manufacturing.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the laminated magnetic material constituting the magnetic circuit of the pick-up cartridge according to the present invention, and FIG.
It is a figure for explaining the manufacturing method of the laminated magnetic material shown in a figure. 1A, 1B, 1C... Gumalloy thin plate, 2A, 2B
...Boron diffusion region, 3...Boron layer.

Claims (1)

[Claims] 1. In an electromagnetic pickup cartridge using a laminated magnetic material made of permalloy as the magnetic material constituting the magnetic circuit, each laminated magnetic material has a continuous boron diffusion region on the laminated surface, An electromagnetic pickup cartridge characterized in that each laminated magnetic material is tightly coupled by the diffusion layer. 2. The electromagnetic pickup cartridge according to claim 1, wherein a laminated magnetic material constituting a magnetic circuit is used for the pole piece. 3. The electromagnetic pickup cartridge according to claim 1 or 2, wherein the yoke is made of a laminated magnetic material constituting the magnetic circuit.