JPH0412462Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

The present invention relates to a motor device, and more particularly to a motor device having a rotation detector that detects rotation speed using magnetic resistance change.

[Conventional technology]

2. Description of the Related Art In devices such as video tape recorders and record players, various types of information are recorded and reproduced while moving or rotating an information recording medium such as a magnetic tape or a record at low speed. In this case, low-speed stability is particularly important when driving the information recording medium. For example, in a video tape recorder, a capstan is rotated at a low speed by a capstan motor. Then, the capstan, which is rotating at a constant speed,
By pressing the magnetic tape using a pinch roller, the magnetic tape as an information recording medium is made to run at a constant speed. Here, a motor device equipped with a rotational speed detector is used for the capstan motor, and a motor control circuit controls the rotation of the capstan motor in accordance with the output of this rotational speed detector. It rotates at a specified low speed. Here, as a rotational speed detector for detecting the rotational speed of the capstan motor, one that utilizes a change in magnetic resistance is used. In these devices, an internal gear is attached to the rotating shaft of the capstan motor, and an external gear is placed close to the inner circumference of the capstan motor and fixed to the base. Further, the side part of the external gear has a yoke that extends laterally in a cylindrical shape concentrically with respect to the rotation center of the internal gear, and then spreads out in a disc shape in the radial direction. A detection coil wound around a bobbin is attached to the U-shaped cross section formed by the yoke and the external gear. Further, a magnet extending toward the outer circumference of the yoke is provided on the outer circumference of the internal gear fixed to the rotating shaft of the capstan motor. Therefore, in the motor device configured in this way, a closed magnetic path is formed of the magnet, the internal gear, the gear between the internal gear and the external gear, the external gear, the yoke, the gear between the yoke and the magnet, and the magnet. It will be configured. When the internal gear rotates with the rotation of the capstan motor, the peaks and troughs of the internal gear and external gear alternately face each other, so the magnetic resistance at these parts changes, causing detection. An output change will occur in the coil in accordance with this change in magnetic resistance. Therefore, the frequency of the output signal generated from this detection coil corresponds to the rotational speed of the capstan motor.

[Problem that the idea aims to solve]

However, the conventional motor device having the above configuration has a complicated structure and has a large number of parts, resulting in high cost. Further, since the motor device having the above configuration has a configuration in which the rotational speed detectors are arranged in parallel in the axial direction of the motor, the dimension in the direction along the rotational axis becomes large. As a result, when the motor shaft is installed in the height direction of the device, such as in a capstan motor used in a video tape recorder, there are various problems such as the inability to make the device thinner. Therefore, the motor device according to the present invention has been made to solve the above problems, and has a simple structure and reduces the number of parts, thereby reducing costs, and reducing the dimension in the direction of the rotation axis. The purpose is to provide a motor device that can.

[Means to solve the problem]

In the motor device according to the present invention, a detection coil, a magnet, and a yoke constituting a rotation speed detector are arranged on the outer circumference of the motor section, and a magnetic material portion on the outer circumference of the motor section is used as a magnetic path for the rotation speed detector. It is something to do.

[Effect]

In the motor device configured in this way,
Since the circumferential magnetic material portion of the motor section is used as the magnetic path of the rotational speed detector, the structure is simplified and the number of parts is reduced. Further, since the detection coil, magnet, and yoke constituting the rotational speed detector are arranged on the outer peripheral portion of the motor section, the axial dimension of the motor device can be shortened.

[Example of idea]

FIG. 1 is a sectional view of essential parts showing an embodiment of a motor device according to the present invention. In the figure, reference numeral 1 denotes a motor section in a motor device equipped with a rotational speed detector used as a capstan motor or the like, and its peripheral surface is made of a magnetic material such as a yoke or a metal case. The motor section 1 is attached to a frame of a mounting device (not shown) by a mounting plate 3 fixed to one end surface portion in a direction along the rotating shaft 2. Reference numeral 4 denotes an external gear fixed to the other end surface of the motor section 1 with screws 5, and has teeth 4a provided over the entire outer circumference thereof. And this motor part 1
A ring-shaped bobbin 6 made of synthetic resin is attached to the outer periphery of the bobbin 6, and the end surface of the bobbin 6 is fixed by a screw 7 pressed against the external gear 4. Note that 8 is a detection coil wound around a recess provided in the bobbin 6. Further, a donut-shaped disk 9 that also serves as a yoke is fixed to the other end surface of the bobbin 6 by screws 10. Further, a magnet 11 and a yoke 12 are arranged on the outer circumference of the bobbin 6, and both are held by being held between the protrusion 6a of the bobbin 6 and the disc 9. Reference numeral 13 denotes a disc fixed to the rotating shaft 2 of the motor section 1, and a donut-shaped internal gear 15 is fixed to the side surface of the outer peripheral portion of the disc with a spacer 14 interposed therebetween and a screw 16. A tooth portion 15a is provided on the inner peripheral portion of the internal gear 15, and a tooth portion 4a of the external gear 4 is provided with a tooth portion 15a.
The dimensional relationship between the two is determined so that a gap is always formed between them, and the external gear 4 and the internal gear 15 are positioned on the same plane. These external gear 4, detection coil 8, disk 9, magnet 11, yoke 12, internal gear 1
5 and the circumferential magnetic material portion of the motor section 1 constitute a rotational speed detector. In the motor device configured in this manner, the magnetic flux generated from the magnet 11 constituting the rotational speed detector is transmitted between the yoke 12 and the internal gear 15.
- Gearp formed between internal gear 15 - Gearp formed between internal gear 15 and external gear 4 - Circumferential magnetic material portion of motor section 1 - Disk 9 - Magnet 11 It flows through a closed magnetic path. Here, when the rotating shaft 2 of the motor section 1 rotates, the disc 13 and the internal gear 15 fixed to the rotating shaft 2 are also rotated. In this case, since the external gear 4 and the internal gear 15 are arranged so that the tooth portions 4a and 15a provided on each of them face each other on the same plane, and the external gear 4 is fixed, When the internal gear 15 rotates with the rotation of the rotating shaft 2, the teeth 4a, 15
Magnetic resistance changes between a. As a result, the magnetic flux density flowing through the closed magnetic path in the rotational speed detector described above changes in accordance with the rotation of the internal gear 15, that is, the rotation of the rotating shaft 2 in the motor section 1. The magnetic flux change within this closed magnetic path induces a voltage change in the detection coil 8. Therefore, a rotational speed detection signal having a frequency corresponding to the rotational speed of the rotating shaft 2 in the motor section 1 is obtained from the detection coil 8. In the above embodiment, the case where the invention is applied to a capstan motor has been explained, but the present invention is not limited to this, and may be applied to a capstan motor as long as the peripheral surface is made of a magnetic material. It is also possible to apply it to a motor device.

[Effect of the idea]

As explained above, the motor device according to the present invention includes a detection coil, a magnet, and a yoke constituting a rotational speed detector arranged on the outer circumferential portion of the motor portion, and a magnetic material portion on the outer circumferential portion of the motor portion for detecting the rotational speed. Since it is used as the magnetic path of the device, the structure is simplified and the number of parts is reduced, resulting in a significant cost reduction. Furthermore, in the motor device according to the present invention,
Since most of the components that make up the rotational speed detector are arranged around the outer periphery of the motor section, it is possible to significantly reduce the dimension of the motor section in the direction of the rotational axis, and this allows for a reduction in the size of the equipment. It has various effects such as greatly contributing to miniaturization.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts showing an embodiment of a motor device according to the present invention. 1 is a motor, 2 is a rotating shaft, 4 is an external gear, 6 is a bobbin, 8 is a detection coil, 9 is a disk, 11 is a magnet, 12 is a yoke, 13 is a disk, 14 is a spacer, 15 is an internal tooth gear.

Claims (1)

[Scope of utility model registration request] In a motor device constituted by a motor section and a rotation speed detector that detects the rotation speed of the motor section, the outer peripheral portion of the first half of the motor section is made of a magnetic material, and the rotation speed detector is connected to the motor section. A ring-shaped external gear fixed to an end face portion in the extending direction of the rotating shaft and having teeth at a portion located outside the outer peripheral portion of the motor portion; a ring-shaped internal gear that is fixed to and rotates on the rotating shaft of the motor section and has teeth at a portion facing the teeth of the external gear; a detection coil that is attached to an outer peripheral portion of the motor section; A motor comprising a magnet and a yoke disposed on the outer periphery of the motor section to form a closed magnetic path passing through the magnet, the outer periphery of the motor section, an external gear, and the external gear. Device.