JPH0428207Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field This invention is an optical rotation speed detection device used in tape drive sources such as cassette tape recorders and video tape recorders, and other various household appliances and industrial equipment. The present invention relates to a small DC motor equipped with a motor.

Conventional technology In recent years, small DC motors are required to have a stable rotation speed as equipment becomes more precise and highly accurate. It is required to be stable.

An example of the conventional small DC motor mentioned above will be described below with reference to the drawings.

FIG. 3 shows a sectional view of a small DC motor incorporating a conventional optical rotation speed detector. In FIG. 3, reference numeral 1 denotes a rotor shaft, which is rotatably supported by a bearing 3 provided on a frame 2. 4 is a ring-shaped magnet, and 5 is a rotor formed by integrally molding a plurality of coils 6 from synthetic resin 7 into a flat plate shape, and is provided opposite to the magnet 4.

8 is a protection element held between the segments of the commutator 9, and 10 is a rotary disk attached to the rotor shaft 1 via a holder 11, which is provided with a plurality of slits 12 as shown in FIG.

Reference numeral 13 denotes an optical rotation speed detector having a light emitting element and a light receiving element, and is provided facing the rotating disk 10. 14 is a preload rubber, and 15 is a ring for increasing the strength of holding the rotor shaft 1 and the resin 7. Reference numeral 16 denotes antireflection paper, which is interposed between the coil 6 and the rotating disk 10.

The operation of the small DC motor incorporating the optical rotation speed detector configured as described above will be described above.

As shown in FIG. 4, the rotating disk 10 has a slit 12, so when the rotor 5 rotates,
The light emitted from the optical rotation speed detector 13 is reflected by the rotating disk 10 and passes through the slit 12 of the rotating disk 10 and is not reflected, which are alternately repeated. Since the light generates an output to the optical rotation speed detector 13, the rotor 5
While rotating, the optical rotation speed detector 13 generates outputs equal to the number of slits provided in the rotating disk 10. In addition, the light that has passed through the slit 12 of the rotating disk 10 is reflected between the rotating disk 10 and the coil 6 to prevent it from being diffusely reflected by the coil 6 and disturbing the output of the optical rotation speed detector 13. A prevention paper 16 is inserted.

Problems to be Solved by the Invention However, in the above configuration, a special anti-reflection paper 16 is inserted between the rotating disk 10 and the coil 6, which requires many man-hours to set up the anti-reflection paper. However, there was a problem in that the cost of parts and processing increased.

In view of the above-mentioned problems, the present invention eliminates the antireflection paper and provides a small-sized DC motor with fewer parts and fewer processing steps than conventional motors.

Means for solving the problems In order to solve the above problems, the rotor of the present invention has the following features:
The rotor surface or coil surface that faces the rotating disk is covered with a synthetic resin that fixes the coil to the rotor shaft.

Function: With the above-described configuration, the light emitted from the optical rotation speed detector and passed through the slit of the rotating disk is absorbed by the resin covering the coil (hereinafter referred to as the cover section). Since there is no diffuse reflection, a stable output can be obtained from the optical rotation speed detector without the need to insert anti-reflection paper between the rotating disk and the coil. Furthermore, since the cover portion can be integrally molded from synthetic resin when fixing the coil to the rotor shaft, the number of steps required to attach antireflection paper, which was conventionally necessary, can be eliminated.

Embodiment A small DC motor according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a rotor in one embodiment of the present invention, and FIG. 2 shows a motor incorporating the same rotor. In the figure, numerals 1 to 15 are the same as the conventional structure, and the explanation thereof will be omitted. 17 is a synthetic resin 7 for fixing the coil 6 to the rotor shaft 1
A cover portion integrally formed with the same resin as the coil covers the surface of the coil in the axial direction relative to the rotating disk 10.

The operation of the rotor configured as described above will be explained below with reference to FIGS. 1 and 2.

From the optical rotation speed detector 13, the rotating disk 1
The light passing through the slit 12 of 0 is absorbed by the cover part 17 covering the coil 6,
Even without inserting antireflection paper between the coil 6 and the rotating disk 10, it is possible to obtain the output of the optical rotation speed detector without disturbance due to diffused reflection.

Effects of the invention As described above, in this invention, the resin that fixes the coil to the rotor shaft covers the coil surface facing the rotating disk, and anti-reflection paper is placed between the coil and the rotating disk. It becomes possible to obtain a stable output from the optical rotation speed detector without any problems, and it is possible to provide a small DC motor with a small number of parts and a small number of processing steps.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a rotor according to an embodiment of the present invention, Fig. 2 is a sectional view of a small DC motor using the rotor with a built-in optical rotation speed detector, and Fig. 3 is a conventional optical FIG. 4 is a cross-sectional view of a small DC motor with a built-in type rotation speed detector, and FIG. 4 is a front view of a rotating disk. 1... Rotor shaft, 5... Rotor, 7... Synthetic resin, 6... Coil, 10... Rotating disk, 13...
Optical rotation speed detector, 17...Cover part.

Claims (1)

[Scope of utility model registration request] A rotor formed by integrally molding a plurality of coils from synthetic resin into a flat plate shape, a rotating disk having a plurality of slits attached to the rotor shaft together with the rotor, and a rotating disk facing the rotating disk. an optical rotation speed detector provided in the rotor, and a small DC current sensor having a cover portion integrally molded from the synthetic resin on the coil surface of the rotor facing the rotating disk to cover the coil surface. motor.