JPS6033732Y2 - Direct drive phono motor - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a direct drive phono motor that directly drives a load in audio equipment such as record players and magnetic tape recording devices.

Conventionally, in the audio equipment mentioned above, the speed of the motor itself is reduced and the load is driven linearly without using gears or belt pulleys, in order to improve reliability and reduce speed fluctuations that occur in the load. A so-called direct drive motor is used.

This type of direct drive phono motor is required to have the following characteristics.

It has good uniformity of speed, that is, no uneven rotation, so-called wow and flutter, accurate rotation speed, fast start-up and stop of rotation, and large torque.

Incidentally, AC motors and DC motors are currently used as direct drive phono motors, but since AC motors are inefficient, there is a tendency for DC motors, particularly brushless motors, to be used.

This brushless motor is light! The rotor position is detected using elements, Hall elements, reed switches, etc., and the armature current is controlled.The so-called shaded coil is wound so that the coil side is located between the slots. It has an armature structure.

Because of this structure, for example, the 60-slot 2CsA for record players is currently in practical use.
There is one with 24 slots and 8 poles for tape recorders,
The maximum number of poles is two or so, and increasing the number of poles beyond that is extremely difficult due to reasons such as a decrease in the mechanical strength of the magnetic pole teeth and the complexity of the coil winding.

In this way, conventional direct-drive phono motors have the disadvantage of having large rotational irregularities because it is difficult to make them multipolar, and slow startup and stopping of rotation.Also, since the rotational speed of both AC motors and motors is not accurate, it is difficult to use them for some kind of rotation control. They needed a circuit.

The purpose of this invention is to eliminate the drawbacks of the conventional technology as described above, and to be suitable for a multi-pole number of more than 100 or more poles.Therefore, there is no unevenness in rotation, quick start-up and stop of rotation, and accurate rotation speed. It is an object of the present invention to provide a direct drive phono motor that does not require an external circuit for control and has a large torque.

This invention will be explained in detail below based on the drawings.

Fig. 1 is an exploded perspective view of one embodiment of this invention;
The figure is a sectional view thereof.

The common yoke 1 consists of a yoke cylinder 2 and a central yoke plate 3 fixed to the center of the yoke cylinder 2, and a large number of magnetic pole teeth 4 are protruded at equal angles in the vertical direction of the outer periphery of the central yoke plate 3.

Assuming that the number of magnetic pole teeth protruding from one side of the central yoke plate 3 is m, each magnetic pole tooth is arranged at an angle of 360°/m, and the interlocking angle between the upper and lower magnetic pole teeth is 360°/4m.

The upper yoke 5a and the clove yoke 5b have yoke plates 7a on yoke rings 6a and 6b that fit into the yoke tube 2, respectively.
, 7b are fixed, and one of the yoke plates 7a, 7b has m magnetic pole teeth 4 protruding from each of them at an angle of 360°/m.

An upper yoke 5a and a lower yoke 5b are fitted above and below the central yoke 1 via excitation coils 8a and 8b, respectively, and the bearing portion 9
The stator section 11 is fixed to a lower case 10 having a stator section 11.

At this time, the common yoke 1, the upper yoke 5a and the lower yoke 5
The magnetic pole teeth b are arranged so as to be offset from each other by an angle of 3600/4 m.

Note that in the drawings, each magnetic pole tooth is drawn to protrude straight in the axial direction for the sake of simplicity, but in reality, each magnetic pole tooth is skewed.

That is, each magnetic pole tooth is located within a certain cylindrical surface, and the direction in which each magnetic pole tooth projects is not parallel to the central axis, but rather in a slightly inclined direction.

Adding a skew to each magnetic pole tooth in this way has a great effect in making the rotation even smoother.

The central yoke plate may have a structure in which two yoke plates are bonded together with a non-magnetic material interposed therebetween, which is drip-free.

Next, in the rotor part 12, a rotating shaft 14 is fixed to the center of a cup-shaped upper case 13 made of a magnetic or non-magnetic material, and an inner surface of the cup-shaped upper case 13 has an inner surface multi-pole magnetized. This is an outer rotor structure to which a ferrite annular magnet 15 is fixed.

The rotating shaft 14 of the outer rotor section 12 is rotatably supported by the bearing section 9 of the stator section 11, thereby forming a phono motor 16.

A motor with such a structure is a type of pulse motor.

FIG. 3 shows an example of a drive circuit for this phono motor. The output from a constant frequency oscillator 21 is sent to the driver 22 via a driver 22 and a phase shifter 23, and has a predetermined phase difference and a sine of a predetermined current value. A wave drive current is created and sent to the excitation coils 8a, 8b of the phono motor 16 to drive the phono motor 16.

In this way, by driving with a sine wave current, the phono motor 16, which is a type of pulse motor, rotates uniformly rather than in steps, and the number of rotations per unit time is determined by the oscillation frequency of the oscillator 21. , there is no need for a feedback circuit for stabilizing the rotation speed, which was required in the past.

Furthermore, if it is necessary to change the number of rotations per unit time, this can be easily done by changing the oscillation frequency of the oscillator 21.

Even if the motors are the same, in other words, the number of poles is the same, the rotation speed of the motor is not uniquely determined by the oscillation frequency of the oscillator, but differs depending on the drive method.

If l~2-phase excitation drive is performed, the rotational speed will be ]/2 for the same oscillation frequency, so smoother rotation can be realized.

By configuring this idea as described above, it is possible to easily achieve a multi-pole count of over 100 poles, and even if the number of poles increases, it is sufficient to insert the excitation coil between the yoke plates, so the coil winding can be reduced. It is not complicated at all, the uneven number of rotations (wow and flutter) is reduced, and rotation starts and stops quickly.

In addition, since the phono motor of this invention is a type of pulse motor, as long as the oscillation frequency of the oscillator is stable, the motor will maintain an accurate constant rotation speed as long as the motor rotates. The motor rotation speed can be easily changed by changing the oscillation frequency without the need for external forces, such as the needle on a record player. This can produce various remarkable effects, such as being less affected by the movement of people.

In other words, the outer periphery of the stator has dozens of magnetic pole teeth, each of which is skewed, the rotor has increased inertia as an outer rotor, and the inner magnet is multi-pole magnetized. By adopting a configuration that supplies a sine wave drive current with a constant wave number, these various requirements are intricately intertwined to maintain an accurate rotation speed as a whole.
Moreover, when focusing on a single rotation, rotational irregularities during the rotation can be significantly reduced, and the most important characteristics of a phono motor, such as constant speed, wow/flutter characteristics, and load fluctuation resistance characteristics, have been significantly improved, making it a practical product. The effect is extremely large.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of an embodiment of the direct drive phono motor according to this invention, and FIG. 2 is a cross-sectional view after its assembly.
FIG. 3 is a block diagram of the drive circuit. 1... common yoke, 2... yoke tube,
3... Central yoke plate, 4... Magnetic pole teeth,
5a... Upper yoke, 5b... Lower yoke, 7a, 7b... Yoke plate, 8at8b...
... Excitation coil, 10 ... Lower case, 11.
...Stator part, 12...Mountain-Yube part, 13
・・・・・・Cup-shaped upper case, 15・・・・・・Annular magnet.

Claims (1)

[Scope of utility model registration request] A common yoke has a central yoke plate in which a large number of magnetic pole teeth are equally spaced and skewed in the vertical direction of the outer periphery, respectively, and on both sides of the common yoke, one side of the common yoke has a similar number of magnetic pole teeth. An upper yoke and a lower yoke protruding at equal intervals on one side of the outer periphery of the plate are fitted through excitation coils, and the magnetic pole teeth of the upper yoke, common yoke, and lower yoke are arranged at equal angles. It consists of a stator part which is arranged and fixed to the lower case, and an outer rotor part which has a ferrite annular magnet with internal multipolar magnetization fixed to the inner peripheral surface of the cup-shaped upper case. The outer rotor section is rotatably supported by the stator section, and direct drive is configured to rotate the outer rotor section at a constant speed by supplying sinusoidal drive currents of constant frequencies with different phases to each of the excitation coils. phono motor.