JPH0138751Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure for attaching a magnet plate for detecting completion of winding and rewinding of a tape in a magnetic recording/reproducing device.

In a magnetic recording/reproducing device, a magnet plate with N poles and S poles alternately magnetized in the circumferential direction is attached to the bottom surface of a reel stand or a rotary table that rotates in synchronization with the reel stand. A detector such as a Hall element is placed close to the detector, and the detector detects one magnetic pole of the rotating magnetic plate to generate a pulse accompanying the rotation of the reel stand, and this pulse is used to complete winding or rewinding of the tape. Sometimes it is a control pulse for cutting off the rotational force applied to the reel stand.

Conventionally, the magnet plate is attached to the rotating table by forming three or more receiving pieces on the lower surface of the rotating table on the same circumference and at substantially equal angular intervals, and inserting the receiving pieces into the magnetic plate. A guide hole or a guide notch is formed for the rotation, and each receiving piece is inserted into the guide hole or notch, and the magnet plate is supported by each receiving piece. It was connected with.

The above structure was devised by the inventor of the present invention (Japanese Patent Application No. 55-25718), and since the magnet plate and rotary table can be disassembled and assembled separately, there is no possibility that one of the parts is defective. In this case, only the defective parts can be easily replaced, and when the magnet plate is attached to the rotary table, there is no deformation of the magnet plate or the rotary table, which is superior to the previous model. However, as a means to rotate the magnet plate and the rotary table together, the two were connected with pins, so assembly was time-consuming in this part, and the diameter of the pin hole and pin The problem was that the relationship had to be strictly adjusted, and even a slight molding defect in the pin hole portion caused a defect in the entire rotary table, often rendering it unusable.

An object of the present invention is to provide a mounting structure that eliminates the above-mentioned problems.

Hereinafter, preferred embodiments will be described in detail with reference to the drawings.

The figure shows an example in which the rotary table and the pulley of the reel stand are used as both. At approximately equal angular intervals of 120 degrees, the receiving pieces 11, 11,
11 protrudes, and an L-shaped magnet plate support portion 12 is formed at the tip of each receiving piece 11 when viewed from the axial direction.

The circular magnet plate 2 is magnetized with N poles and S poles alternately in the circumferential direction as shown in FIG.
Guide holes 21, 21, 21 are formed through which the guide holes 21 are inserted, and a fitting part 22 is formed in which the magnet plate support part 12 of the receiving piece 11 is fitted to the lower surface of the magnet plate 2 that is continuous with each guide hole 21. are doing.

On the upper surface of the magnet plate support portion 12 of each receiving piece 11, there is a slight convex portion 13 as shown in FIGS.
A recess 23 is formed in each of the fitting portions 22 that are continuous with each guide hole 21 in correspondence with the convex portion 13 .

In order to attach the magnet plate 2 to the rotary table 1, it is preferable to interpose a gasket 3 between both 1 and 2, insert each receiving piece 11 of the rotary table 1 into each guide hole 21 of the magnet plate 2, and then Magnet plate 2
The magnet plate 2 is locked to the rotary table 1 in the rotational direction by slightly rotating the magnet plate 2 in a certain direction and engaging the convex portions 13 with the respective concave portions 23 as shown in FIG. As a result, the table 1 and the magnet plate 2 rotate integrally, but unlike the conventional technology in which the table 1 and the magnet plate 2 are connected with a pin,
Since the convex portion 13 is only engaged with the concave portion 23,
The assembly work is extremely simple, and unlike molding pin holes, the unevenness can be easily and precisely molded, so the rate of defective products is extremely low.

1 and 6, 14 is a reel collar that engages with a reel hub (not shown);
It is squarely fitted into the sleeve portion 15 of the table 1 and is prevented from coming off by a stopper 16. 17 is a spring for back tension, and 18 is a shaft hole. still,
It is desirable to form a hole 19 (FIG. 4) in the rotary table 1 so that the magnet plate support part 12 at the tip of the receiving piece 11 can be seen from above the rotary table 1. In addition, when each receiving piece 11 is formed closer to the outer peripheral edge of the rotary table 1 or closer to the axis, the guide hole 21 of the magnet plate 2 is formed in the shape of a notch on the outer peripheral edge or the inner peripheral edge of the magnet plate 2. It will be done.

As described above, according to the present invention, the rotary table 1
Since the magnet plate 2 and the magnetic plate 2 are locked in the rotational direction by engagement of the projections and depressions 23 and 13, assembly is simple, and small projections and depressions can be formed with high precision, so that the rate of defective products is extremely low.

[Brief explanation of the drawing]

Fig. 1 is an exploded half-sectional view showing an embodiment of the present invention, Fig. 2 is a bottom view of the rotary table, Fig. 3 is a bottom view of the magnet plate, and Fig. 4 is a sectional view taken along line A-A in Fig. 1. ,
FIG. 5 is an enlarged view taken along the line B--B in FIG. 1, FIG. 6 is a half-cut cross-sectional view of the assembled state, and FIG. 7 is a partially enlarged cross-sectional view taken along the line CC. Explanation of main symbols in the figure, 1 is a rotary table, 11
1 is a receiving piece, 12 is a magnet plate support part, 13 is a convex part, 2
2 is a magnet plate, 21 is a guide hole (guide notch), and 23 is a recess.

Claims (1)

[Claims for Utility Model Registration] (1) On the lower surface of the rotary table made of non-magnetic material, at least three
At the same time, each receiving piece is formed with a magnet plate supporting part, and the magnet plate, which is alternately magnetized with N poles and S poles in the circumferential direction, is provided with a magnet plate supporting part at a position corresponding to the receiving piece. A guide hole or a guide notch is formed through which the receiving piece is inserted, and the magnetic plate is supported by the magnetic plate supporting portion of each receiving piece while each receiving piece is inserted into the respective guide hole or guide notch. In this structure, a recess is formed on one of the lower surface of the magnet plate and the upper surface of the magnet plate support, and a protrusion corresponding to the recess is formed on the other, and the protrusion is engaged with the recess. A mounting structure for a control pulse generating magnet plate in a magnetic recording/reproducing device, wherein the magnet plate is locked to the rotary table in the rotational direction by fitting together. (2) A mounting structure for a control pulse generating magnet plate in a magnetic recording/reproducing device according to claim (1), wherein the rotary table is a pulley of a reel stand.