JPH0119576Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a device intended to prevent a motor belt from falling off.

Conventionally, as this type of device, those shown in FIGS. 1 and 2 have been used in tape recorders. 1
is attached to the rotor 2 of the motor with a belt.
A plurality of ring-shaped magnets 3 are provided on one surface of the rotor 2, and a plurality of annular magnets 3 are magnetized on the circumference, and a drive coil 4 is provided on a substrate 5 to face the magnets 3. 6
is an FG coil for rotation detection, which is attached to a magnetic circuit consisting of a magnet 7, a plate 8, and a shield plate 9. This rotation detection method has been used conventionally, and as shown in FIG.
The magnetic circuit is inserted into the concave groove of the rotor 2 so that the tip of the plate 8 faces the other surface perpendicular to the rotation axis 12 of the rotor 2, and the tip of the plate 8 faces the inner circumference of the rotor. It's on. Reference numeral 10 denotes a support plate that supports the magnetic circuit, and is integrated with a bearing 11 that holds the rotating shaft 12 of the rotor 2. Rotating shaft 12
One end is supported by a bearing 13 of the base plate 5, and the other end projects from the chassis 14 and serves as a capstan for running the tape. The belt 1 transmits rotation to a rotating body 1 (not shown) in order to drive a reel stand of a tape recorder (not shown).

In the above structure, the shield plate of the magnetic circuit for detecting rotation has the function of transmitting magnetic lines of force between the rotor 2 and the magnets 7, and is also used for external magnetic shielding.
It is approximately the same size as the diameter of. Therefore,
A rotating body (not shown) and the rotor 2 are mounted on a chassis 14.
The belt fell off when it was assembled into the shield plate 9.
In some cases, it may get stuck between the chassis 14 and the chassis 14, causing a deterioration in the efficiency of assembly work. Also, the belt 2 is connected to the rotor 2 during transportation and use.
shield plate 9 and chassis 1.
Since the interval between the belts 4 and 4 is narrow, it is a very troublesome task to reattach the belt 2.

This invention was made in order to eliminate the above-mentioned drawbacks, and prevents the belt from slipping off without changing the conventional structure.

This invention will be explained below with reference to FIGS. 3 and 4. Note that the same components as those in the prior art are given the same reference numerals and explanations are omitted.

The characteristic structure of this invention resides in the shield plate 9. As shown in FIG. 4, projections 9a, 9a larger than the diameter of the rotor 2 are provided on the outer periphery of a disk-shaped shield plate 9 having a diameter substantially equal to the diameter of the rotor 2. Therefore, the magnetic circuit for rotation detection is installed on the chassis 1.
4, the rotating shaft 12 of the rotor 2 around which the belt 1 is wound is inserted into the bearing 11, the substrate 5 having the drive coil 4 is attached, and the rotating body (not shown) around which the belt 1 is wound is inserted. Even if the belt 1 deviates from the rotor 2 during work such as attaching it to the chassis 11, it is retained by the protrusion 9a of the shield plate 9 and does not fall off. Further, since the protrusion 9a exists even when the rotor 2 is rotating, there is no fear that the belt 1 will fall off. The protrusion 9a has almost no effect on the operation of the motor.

This idea eliminates the need to increase the number of parts as described above by simply providing a portion larger than the rotor diameter on the outer periphery of the shield plate to effectively perform magnetic action. It can also be used to prevent falling off, and is extremely effective. In particular, the processing and assembly of the shield plate is completely unchanged from the conventional method, there is almost no difference in cost, and the magnetic effect can be practically equivalent to that of the conventional method.

Note that the shape of the shield plate is not limited to the embodiment, and may be any shape that prevents the belt from falling off without affecting the practical magnetic effect, and may include a disc larger than the diameter of the rotor, or a protrusion. It is also possible to use a disc or the like provided with a large number of. Furthermore, the belt that transmits the rotation of the rotor is not limited to the embodiments, and may be wound around a flywheel that drives the other capstan of a tape recorder's dual capstan, for example. Needless to say, the present invention can also be used in other fields using motors using rotation detection means.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional rotation transmission device, Fig. 2 is an enlarged view of the main part of Fig. 1, Fig. 3 is a sectional view of a rotation transmission device according to an embodiment of this invention, and Fig. 4 is a sectional view of this invention. FIG. 2 is a front view showing a shield plate according to an embodiment. 1... Belt, 2... Rotor, 4... Drive coil, 6... Rotation detection coil, 9... Shield plate.

Claims (1)

[Scope of utility model registration request] A protruding portion larger than the diameter of the rotor is provided on the outer diameter of a shield plate of a magnetic circuit for rotation speed detection, which is provided close to a surface perpendicular to the rotation axis of the rotor that is integral with the rotation axis of the motor. A rotation transmission device using a motor, characterized in that a belt for rotation transmission is placed around the outer circumference of a rotor.