JPS6252546B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric motor, and more particularly to an electric motor such as that provided in a reel winding mechanism of a magnetic recording/reproducing device.

1 and 2 are plan views of a video tape recorder as an example of a magnetic recording and reproducing device that forms the background of this invention and to which an embodiment of the invention is applied, and FIG. The previous state is shown, and FIG. 2 shows the state after the magnetic tape is pulled out.

Referring to FIGS. 1 and 2, a rotating drum 2 having a rotating magnetic head therein, an inlet guide arm 3, and an outlet guide arm 4 are disposed on a substrate 1, respectively, for recording and reproducing. In this case, the video cassette 5 is placed at a predetermined position. An inlet tape guide 6 is attached to the inlet guide arm 3, and an outlet tape guide 7 is attached to the outlet guide arm 4. In the state shown in FIG.
located in the notches 9, 10 to engage with the second
As shown in the figure, as both guide arms 3 and 4 rotate, the magnetic tape 8 is pulled out, and when this drawing is completed, it is positioned at the entrance side block 11 and the exit side block 12. In this state, the magnetic tape 8 is wound around the rotating drum 2, recording and reproducing audio signals and control signals is performed by the fixed head 13, and is held between the capstan 14 and the pinch roller 15 and pressed. This makes it possible to travel for recording and playback.

In this state, the supply reel 16 and take-up reel 17 in the video cassette 7 are engaged with the reel winding mechanism and rotated. Alternatively, rotation was transmitted to the reel winding mechanism via an idler. Therefore, the devices have generally become large and complex in structure.

In order to eliminate such drawbacks, a device has been proposed in which the motor is provided inside the reel winding mechanism to reduce the size.

FIG. 3 is a central longitudinal cross-sectional view of a reel winding mechanism in a magnetic recording/reproducing apparatus which is the background of the present invention. The reel winding mechanism of this type of device consists of reel 1
It includes a rotatably held reel disk 18 that engages with and rotates the reel disks 6 and 17. A disk-shaped magnet rotor 20 is fixed to the lower surface of the reel disk 18 concentrically with a rotor disk 19 made of electromagnetic soft iron or the like and serving as a path for magnetic flux. The net rotor 20 is magnetized to NS poles at every 45 degrees of mechanical angle. Below the magnetic rotor 20, a flat coil 21 for generating a rotating magnetic field and a stator 22, which is made of electromagnetic soft iron or the like and constitutes a magnetic circuit of the coil 21, are integrally fixed. Although it does not appear in FIG. 3, it is used as a member for attaching the coil 21 to the substrate 1.

In such a configuration, the magnet rotor 20 rotates in synchronization with the rotating magnetic field generated from the flat coil 21, thereby driving the reel disk 18. However, this type of device has the disadvantage that when the magnetized rotor 20 rotates, eddy currents are generated on the stator 22, resulting in torque loss and increased power consumption. It was hot.

Therefore, the main object of the present invention is to provide an electric motor that can reduce torque loss by effectively using eddy current to obtain rotational torque, and thereby reduce power consumption. be.

In summary, the present invention provides a magnet rotor having a coil for generating a rotating magnetic field on an insulating plate, a rotating shaft rotatably held on a substrate with the coil sandwiched therebetween, and a rotating shaft of the magnet rotor. A stator disc is arranged rotatably held by the magnetic rotor and rotates separately from the magnetic rotor.
The magnet rotor is rotated by a rotating magnetic field generated from the coil, and the stator disk is rotated by eddy currents generated by the magnetic field of the magnet rotor.

The above objects and other objects and features of the present invention will become more apparent from the detailed description given below with reference to the drawings.

4 to 7 are diagrams for explaining a reel winding mechanism equipped with a synchronous motor according to an embodiment of the present invention, and FIG. FIG. 5 is a central vertical sectional view of the reel winding mechanism, FIG. 6 is a plan view, and FIG. 7 is a cross-sectional view taken along the line - in FIG. 5. It is a diagram.

The holding plate 23 is made of an insulator such as an epoxy resin plate filled with glass fiber, and on one side of the holding plate, six flat coils 21 are arranged at equal angular intervals as shown in FIG. It will be placed in This holding plate 23 is attached to the substrate 1 with a mounting fitting 24. Note that a circuit pattern made of copper foil is formed on this holding plate 23 to attach and wire the flat coil 21 and the magnetic flux sensor 25. As shown in FIG. 7, three magnetic flux sensors 25 are installed at equal angular intervals to detect the magnetic flux of a first rotor 30, which will be described later.

A bearing 26 is provided on the substrate 1 . A rotor disk 28 is provided between the substrate 1 and the holding plate 23. This rotor disc 28 has a rotating shaft 2 rotatably held at its center by the bearing 26.
7, ring-shaped field magnets 29 magnetized to NS poles at every 45 mechanical angles are installed concentrically, and are made of electromagnetic soft iron or the like to serve as a path for magnetic flux. A first rotor 30 is constituted by the rotor disk 28 and the ring-shaped magnet 29. At the top of the rotation shaft 27 of the first rotor 30,
A disk-shaped second rotor 31 that rotates separately from the first rotor 30 is provided. This second rotor 31 is fixed to the reel disk 18 so as to be integral with it. A metal 32 that rotatably holds the rotating shaft 27 is provided approximately at the center of the second rotor 31 and the reel disk 18. A thrust bearing 33 is arranged above the metal 32 so as to be in contact with the upper end of the rotating shaft 27 . This thrust bearing 33 performs axial positioning of the second rotor rotating body consisting of the second rotor 31, reel disk 18, and metal 32, and
A bearing with low frictional force is configured for the rotating shaft 27. Further, on the upper part of the reel disk 18, a spline 34 and a spring 35 that engage with the reel 17 are provided.
is incorporated.

A pulley 36 is fixed below the rotating shaft 27 that rotates integrally with the first rotor 30,
The rotational force of the first rotor 30 is transmitted to the capstan 14 via the rubber belt 37. This pulley 3
In No. 6, the pulley ratio is set so that the rotational speed during normal running of the magnetic tape during recording or reproduction is approximately 1500 rpm.

With the above configuration, if the magnetic flux of the first rotor 30 is detected by the magnetic flux sensor 25 and the flat coil 21 is driven by the control circuit (not shown), a three-phase eight-pole synchronous motor is configured. be done. Then, when an image is recorded, a synchronization signal separated from the image signal is used, and when an image is reproduced, the fixed head 1 is
3, if a current is applied to the flat coil 21 in synchronization with the control signal reproduced by
0 rotates at a rotational speed of, for example, 1500 rpm by the rotating magnetic field generated from the flat coil 21. A magnetic circuit is constructed by the magnetic flux of the magnet 29 of the first rotor 30 passing through the second rotor 31 made of an electromagnetic soft iron plate, and the first rotor 3
0 rotates, an eddy current is generated in the second rotor 31. Due to this eddy current, an eddy current torque is generated in the second rotor 31 in the same direction as the rotation of the first rotor 30. Due to this ready current torque, the second rotor 3
1 rotates independently from the first rotor 30. Therefore, the rotational force of the first rotor 30 is transferred to the capstan 1 via the pulley 36 and the rubber belt 37.
4 can be transmitted. Further, since the rotational force of the second rotor is transmitted to the reel disk 18, the rotational force of the second rotor 31 can be used for winding the magnetic tape.

In this way, the first rotor 30 and the second rotor 31 rotate individually, and the second rotor 31 is directly connected to the reel disk 18, so the capstan 14 can be rotated with one electric motor structure. It can serve as both a synchronous motor for rotating the reel disk 18 and a torque motor for rotating the reel disk 18.

Note that, as understood from the above configuration, the first
An attractive force due to magnetic force is generated between the rotor 30 and the second rotor 31 (generally, this attractive force is 1 Kgf or more, and in the device shown here, it is approximately
1.5Kgf is generated. ), so reel disk 1
8 and the rotating shaft 27, even if there is no retainer provided,
When the reel disk 18 rotates, it does not come off the rotating shaft 27.

Further, due to the above-mentioned suction force (mainly shown in FIG. 5), the end face of the rotor disk 28 and the end face of the metal 32 come into contact with each other, and a pressing force (a force of 1.5 Kgf as described above) is applied. At this time, while the rotor disk 28 is rotating at a constant speed, the metal 32 is rotating at a low speed integrally with the reel disk 18, so there is a relative rotation between the two. Become. Then, frictional torque is generated between the end face of the rotor disc 28 and the end face of the metal 32, which is added to the aforementioned eddy current torque, that is, the rotational force of the stator disc 31, and exerts a rotational force on the reel disc 18 as a whole. give.

Further, in the above-described embodiment, the present invention is applied to a synchronous motor of a video tape recorder, but the present invention is not limited thereto, and can be applied to other magnetic circuit playback devices such as a reel-to-reel type video tape recorder or a cassette type video tape recorder. Needless to say, the present invention can also be applied to audio tape recorders and open-reel audio tape recorders. It can also be applied to various electronic devices that require constant torque as well as synchronous rotational force.

As described above, according to the present invention, a coil is disposed between the first rotor and the second rotor, and the first rotor is rotated by the rotating magnetic field of the coil, and the first rotor and The electromagnetic torque generated in the second rotor by the friction torque generated by the friction surface that maintains the attractive force generated between it and the second rotor and the eddy current generated by the magnetic flux from the first rotor. By using the present invention in other applications requiring constant torque, it is possible to obtain an electric motor that is highly efficient and consumes little power as a whole.

[Brief explanation of the drawing]

Figures 1 and 2 are plan views of a conventional general magnetic recording and reproducing device, with Figure 1 showing the state before pulling out the tape, and Figure 2 showing the state after pulling out the magnetic tape. It is a figure showing a state. FIG. 3 is a central longitudinal cross-sectional view of a reel winding mechanism included in a magnetic recording/reproducing apparatus which is the background of the present invention. 4 to 6 are diagrams for explaining a reel winding mechanism equipped with an electric motor according to an embodiment of the present invention. In particular, FIG.
FIG. 2 is a side view shown from the right direction of FIG.
FIG. 5 is a central longitudinal section of the reel winding mechanism, and FIG. 6 is a plan view thereof. FIG. 7 is a sectional view taken along line - in FIG. 5. In the figure, 1 is a board, 14 is a capstan,
18 is a reel disk, 21 is a flat coil, 2
3 is a holding plate, 24 is a mounting bracket, 25 is a magnetic flux sensor, 26 is a bearing, 27 is a rotating shaft, 28 is a rotor disc, 29 is a ring-shaped magnet, 30 is a first rotor,
31 is the second rotor.

Claims (1)

[Claims] 1 a substrate, a rotating shaft mounted on the substrate and rotatably held; a first magnet rotor attached to the rotating shaft; a first magnet rotor located above the first magnet rotor; a coil mounted on the substrate facing the magnet rotor; a bearing portion having a friction surface that contacts the upper surface of the first magnet rotor and rotatably held on the rotating shaft; an upper side of the coil; A second magnet rotor is provided, which is located opposite to the first magnet rotor and is attached to the bearing portion to receive the absorption force from the first magnet rotor, and the second magnet rotor receives the absorption force from the first magnet rotor. The first magnet rotor is rotated, and the friction torque generated on the friction surface in response to the rotation of the first magnet rotor and the electromagnetic torque due to the magnetic flux from the first magnet rotor cause the second magnet to rotate. An electric motor that rotates the netrotor.