JPS6362822B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary body driving device for rotationally driving a turntable or the like while floating and guiding it by the attraction force of an electromagnet.

Conventionally, there is a direct drive type record player in which a turntable is directly connected to the rotor of an electric motor and driven directly.

However, with this system, the weight of the turntable and motor rotor must be supported by a bearing that guides and supports the shaft around the shaft, and something with frictional resistance such as a pivot bearing, which causes noise or rumbling noise caused by rotation. This is not desirable for audio equipment.

In this invention, a rotating body equipped with a rotating device such as a turntable is levitated and supported by the magnetomotive force of an electromagnet, and the rotating part is completely contactless by being guided and supported by an electromagnet placed opposite to the side of the rotating body. It is an object of the present invention to provide a turntable drive device which eliminates the above-mentioned disadvantages and can strongly maintain the center position of the rotating body by means of an electromagnet installed on the side surface of the rotating body.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a record player to which the present invention is applied. In the figure, 1 is the box of a record player. The top surface of this box body 1 has an opening 1a.
is formed. Further, a flat armature core 2 is provided as a stator inside the upper surface of the box 1 and near the opening 1a. A three-phase armature winding 3 is wound around this armature core 2. U-shaped DC electromagnets 4 divided into at least three parts are arranged at equal intervals outside the armature core 2 and on a concentric circle. These DC electromagnets 4 each independently generate an electromagnetic attractive force to the rotating body 5. A disc-shaped rotating body 5 faces the armature core 2 and the DC electromagnet 4.
will be established. This rotating body 5 has a rotor 6 made of a permanent magnet on the surface facing the armature core 2, and forms a flat synchronous motor. 5b. Further, a turntable 9 is attached to the rotating body 5 via a shaft 8 at the center of the plate surface. 7 is pick up. Thick part 5 on the outer periphery of the rotating body 5
DC electromagnet 11 divided into four parts facing the side surface of b
Place them at equal intervals. This electromagnet 11 has the same function as the electromagnet 4 on the side surface of the rotating body, and always holds the rotating body at the center position.

A displacement meter 10 is connected to an electromagnet 4 facing the rotating body 5.
Provided on the outside of the surface facing the This displacement meter 10
A total of three are provided for each electromagnet 4, and in order to control the attractive force of each electromagnet 4 so that the gap length between each electromagnet 4 and the rotating body 5 becomes a preset value,
It is designed to generate an output voltage proportional to the length. Displacement gauges 12 are provided opposite the thick portion 5b of the rotating body 5 at two electromagnets located at right angles to the electromagnet 11 divided into four parts. The arrangement of the electromagnet 11 and displacement meter 12 in this case is shown in FIG. DC electromagnets 11a and 11b, DC electromagnets 11c and 11d
are arranged symmetrically and provided with displacement meters 12a and 12b for detecting the empty length of the side surface of the rotating body 5. This displacement meter 12a is connected to the DC electromagnet 11a and the thick part 5 of the rotating body 5.
The displacement meter 12b detects the air length between the DC electromagnet 11c and the thick portion 5b of the rotating body 5.

Therefore, DC electromagnets 11a, 11b, 11c, 11
The empty length between d and the thick part 5b of the rotating body 5 is Xa,
In the case of Xb, Xc, and Xd, since the DC electromagnets 11a and 11b are in symmetrical positions, Xa+Xb=Zo, and similarly, Xc+Xd=Zo. Therefore,
By detecting Xa, we know that Xb=Zo−Xa, and by detecting Xc, we know that Xd=Zo−Xc
is required.

In order to guide and support the rotating body 5 to the center position, the empty length may be controlled so that Xa=Xb=Xc=Xd=Zo/2.

Next, a control circuit for the DC electromagnet 4 will be explained with reference to FIG. In the figure, 4 ₁ , 4 ₂ , 4 ₃ represent DC electromagnets 4 divided into three parts, and 10 ₁ , 10 ₂ , 10 ₃ represent displacement meters 10 provided for each of these electromagnets 4 ₁ , 4 ₂ , 4 ₃ .

Electromagnets 4 ₁ , 4 ₂ , 4 ₃ are each connected to a power converter 112
It is connected to the output terminals of ₁ , 112 ₂ and 112 ₃ .
These power converters 112 ₁ , 112 ₂ , 112 ₃ are connected to empty length control circuits 13 ₁ , 13 ₂ , 13 ₃ , respectively. This empty length control circuit 13 ₁ , 13 ₂ , 13
₃ are connected to the displacement meters 10 ₁ , 10 ₂ , 10 ₃ and a common empty length setting device 14, respectively.

In this case, the empty length control circuits 13 ₁ , 13 ₂ , 13
₃ is specifically constructed as shown in FIG.
For convenience of explanation, FIG. 4 shows the empty length control circuit 13 ₁ corresponding to the DC electromagnet 4 ₁ . First, the output terminals of the displacement meter 10 ₁ and empty length setting device 14 are connected to the comparator 15 . This comparator 15 compares the outputs of both and outputs the deviation ε ₁ . Also, comparator 15
is connected to the comparator 17 together with the parallel compensation circuit 16. In this case, the parallel compensation circuit 16 is the displacement meter 10 ₁
It consists of circuits for the first derivative (velocity) and second derivative (acceleration) of displacement, and serves to stabilize the control system. Further, the comparator 17 generates a deviation ε ₂ which is obtained by adding the output of the parallel compensation circuit 16 to the deviation ε ₁ described above.

Comparator 17 is connected to comparator 19 via series compensation circuit 18 . This series compensation circuit 18 functions to increase the loop gain and reduce the steady-state deviation. (In order to make the steady-state deviation zero, integral control may be performed.) Also, the comparator 19 generates an output that is the sum of the deviation ε ₂ passed through the series compensation circuit 18 and the output of the sawtooth wave oscillator 20. I have to. In this case, the oscillator 20 generates a negative waveform output with a maximum value of zero as shown in the figure. Therefore, the comparator 19 generates as an output a waveform component that is lifted in the positive direction when ε ₂ is added.

The output terminal of the comparator 19 is connected to a power converter 112, such as a chopper circuit 22, via a Schmitt circuit 21. A DC electromagnet 4 ₁ is connected in series to this chopper circuit 22 .

According to such a configuration, if the set value x ₀ is now set in the empty length setter 14 and x ₁ is generated from the displacement meter 10 ₁ , then the comparator 15 indicates that ε ₁ = x ₁ − A deviation output of x ₀ is generated. This deviation output ε ₁ is given the output from the parallel compensation circuit 16 and becomes a deviation ε ₂ and enters the series compensation circuit 18 . After passing through this series compensation circuit 18, the sawtooth wave oscillator 20
is added to the output of
The proportion of the on period is controlled, and the current supplied to the DC electromagnet 4 ₁ is determined by this on period.

Here, in the case of proportional control (the series compensation circuit 18 is a simple amplifier), ε ₁ =x ₁ −x ₀ is a positive value in a steady state. If there is no change in the empty length, the output of the parallel compensation circuit 16 is zero and ε ₁ =ε ₂ . Then, when the amplification factor of the series compensation circuit 18 is K, K×ε ₂ is added to the sawtooth waveform of the oscillator 20. This waveform is a negative waveform with a maximum value of zero. Therefore, K×
When the voltage is lifted in the positive direction by ε ₂ , the Schmitt circuit 21 turns on the chopper circuit 22 for only the positive period. As a result, a current corresponding to this ON period is supplied to the DC electromagnet 4 ₁ , so that the electromagnet 4 ₁ generates an attractive force proportional to the current at this time as a levitation force for the rotating body 5 .

Here, for some reason, _the output of displacement meter 10 x ₁
When becomes smaller, the on-period becomes smaller and the levitation force is attenuated, and as a result, x ₁ returns to its original value. Conversely, when the output x ₁ of the displacement meter 10 ₁ increases, the on-period increases, the levitation force increases, and x ₁ returns to its original value. The parallel compensation circuit 16 operates against the transient response during this time. That is, the first-order differential has a phase that is 90 degrees ahead of the displacement due to velocity compensation, and the second-order differential has a phase that is 180 degrees ahead of the displacement due to acceleration compensation. Therefore, the control system is kept stable against sudden changes in displacement.

In this way, the empty length control circuit 13 ₁ controls the attraction force of the DC electromagnet 4 ₁ so that the rotating body 5 is floated and supported with a constant empty length. Of course, the same applies to the other empty length control circuits 13 ₂ and 13 ₃ . Therefore, the rotating body 5 is a DC electromagnet 4 ₁ , 4
It will be balanced and supported floating at three points corresponding to ₂ and 4 ₃ so that the sky length will be constant.

Next, the control circuit for the DC electromagnet 11 will be explained with reference to FIG. In the figure, 12a and 12b are electromagnets 1
The displacement gauges 12 provided at 1a and 11c are shown. Electromagnets 11a, 11b, 11c, 11d are power converters 202a, 202b, 202c, respectively.
The output terminal of 202d is connected. These power converters 202a, 202b, 202c, 202d
are empty length control circuits 201a, 201b, 2, respectively.
Connect 01c and 201d. The displacement gauge 12a is connected to the empty length control circuits 201a and 201b, and the displacement gauge 12b is connected to the empty length control circuits 201c and 201d. Further, a common empty length setting device 203 is connected to the empty length control circuits 201a, 201b, 201c, and 201d.

In this case, the empty length control circuits 201a, 201
b, 201c, 201d and power converter 202a,
A concrete circuit of 202b, 202c, and 202d is shown in FIG. For convenience of explanation, FIG. 6 shows an empty length control circuit and a power converter corresponding to the DC electromagnets 11a and 11b.

Initially, the control circuit of the DC electromagnet 11a provided with the displacement meter 12a includes comparators 301, 302a,
303a, empty length setting device 203, parallel compensation circuit 3
07a, a series compensation circuit 303a, a Schmitt circuit 305a, a power converter 306a, a sawtooth wave oscillator 309, and a displacement meter 12a. This configuration is completely the same as that of the control circuit of the DC electromagnet ₄₁ in FIG. 4, and the operation of each circuit is also the same, so a detailed explanation will be omitted. The gap length setting device 203 generates only a fixed voltage corresponding to the gap length when the DC electromagnet 11a is arranged with a predetermined gap distance between the rotating body 5 and the DC electromagnet 11a. Only when the rotating body 5 changes in the direction in which the length becomes larger than a predetermined empty length, the DC electromagnet 1
A voltage is supplied to 1a. To explain this according to the diagram, when the rotating body 5 is stationary (floating at the center position and rotating), the empty length setting device 2
Since the output of 03 and the detected value of the displacement meter 12a are the same, the deviation ε ₁₁ a generated by the comparator 301 becomes zero, and the voltage supplied to the DC electromagnet 11a becomes zero. Next, if the rotating body changes due to disturbance etc. and the detected value of the displacement meter 12a becomes larger than the output of the empty length setting 203,
Comparator 301 generates a positive deviation ε ₁₁ a and comparator 3
A positive deviation ε ₁₂ a is also outputted to 02a, and this deviation ε ₁₂ a passes through the series compensation circuit 303a and is output to the comparator 30.
4a. This comparator 304a generates as an output a waveform component that can lift the output of the sawtooth wave oscillator 309 in the positive direction by the deviation ε ₁₂ a. The waveform of the output of the comparator 304a is corrected by a Schmitt circuit 305a, and the chopper circuit is turned on. Therefore, voltage is supplied to the DC electromagnet 11a.

Next, the detected value of the displacement meter 12a is empty = length setting 203
When _the rotating body 5 changes in a direction in which _the output becomes smaller than the output of The Schmitt circuit 305a which receives this output waveform as an input has zero output, the chopper circuit is off, and the voltage supplied to the DC electromagnet 11a becomes zero.

A control circuit for the DC electromagnet 11a arranged symmetrically to the DC electromagnet 11a will be described with reference to FIG. In the figure, 308 and 307b indicate inverting circuits. The inversion circuit 308 inverts the deviation ε ₁₁ a to generate a deviation ε ₁₁ b. The inverting circuit 307b inverts the output of the parallel compensation circuit 307a. Inversion circuit 3
Each output of 08, 307b is added by a comparator 302b to generate a deviation ε ₁₂ b, and a series compensation circuit 30
3b. This series compensation circuit output is compared with the output of a sawtooth wave oscillator 309 by a comparator 304b, and is connected to a Schmitt circuit 305b. The output of the Schmitt circuit 305b is connected to a chopper circuit power converter 306b. The DC electromagnet 1 is
The empty length corresponding to 1b and the output of the parallel compensation circuit are generated. Therefore, it performs the same operation as the control circuit for the DC electromagnet 11a and controls the voltage supplied to the DC electromagnet 11a.

Next, DC electromagnets 11a placed in symmetrical positions
The relationship between the voltages supplied to 11b and 11b will be explained according to the diagram.

Initially, when the rotating body 5 maintains the center position, the deviation ε ₁₁ a of the comparator 301 is zero, and the voltage supplied to the DC electromagnets 11a and 11b is zero. Next, when the comparator 301 generates a positive deviation ε ₁₁ a, the deviation ε ₁₁ b becomes negative by the inverting circuit 308, so a voltage is supplied to the DC electromagnet 11a, but the voltage supplied to the DC electromagnet 11b is zero. becomes. Next, comparator 30
1 causes a negative deviation ε ₁₁ a, then a positive deviation ε ₁₁ b
occurs, so the operation is opposite to that when a positive deviation ε ₁₁ a occurs. Therefore, if the free lengths of the symmetrically arranged DC electromagnets 11a and 11b are controlled as described above, the rotating body 5 can always be held at the center position. Of course, other empty length control circuits 301
The same applies to c and 301d.

Next, a control circuit for a contactless motor consisting of the armature core 2 and rotor 6 will be explained with reference to FIG. In the figure, 3 ₁ , 3 ₂ , 3 ₃ are three-phase armature windings, and 6 is a rotor made of permanent magnets.
Transistors 23, 24, and 25 are connected in series to the armature windings 3 ₁ , 3 ₂ , and 3 ₃ , respectively. These series circuits are then connected to a DC power supply 26. This power supply 2
A series circuit of a resistor 27 and a constant voltage diode 28 is connected to both ends of the resistor 6. This resistor 27 and diode 2
The emitter of the transistor 29 is connected to the connection point 8. This transistor 29 has a base connected to a resistor 30
It is connected to the negative side terminal of the power source 26 via the power source 26.

The rotor 6 is equipped with rotor position detectors 31 and 3.
2,33 are connected. This detector 31,3
2 and 33 are connected between the collector of the transistor 29 and the ground of the power supply 26. Further, these detectors 31, 32, and 33 turn on the transistors 23, 24, and 25 in order according to the rotation of the rotor 6.

On the other hand, the armature windings 3 ₁ , 3 ₂ , 3 ₃ are commonly connected via diodes 34 , 35 , 36 , and a series circuit of a capacitor 37 and a resistor 38 is connected between this connection point and the positive terminal of the power source 26 . Connect.

At both ends of the capacitor 37 are 39, 40, 41,
A bridge circuit consisting of 42 is connected. In this case, a thermistor 43 is connected in parallel to the resistor 41.

A transistor 4 is connected to the connection point between the resistors 39 and 40.
Connect the emitter of 4. This transistor 44
has its base connected to the connection point of the resistors 41 and 42, and its collector connected to the transistor 4 via the resistor 45.
Connect to the base of 6. The emitter of this transistor 46 is connected to the connection point between the capacitor 37 and the resistor 38, and the collector is connected to the base of the transistor 29 via the resistor 47.

In such a configuration, when the transistors 23, 24, and 25 are turned on in order by the outputs of the rotor position detectors ₃₁ , 32, and _{33, the armature windings 31, 32} , and ₃₃ are sequentially energized. , this winding 3
The rotor 6 is rotationally driven by the rotating magnetic fields of ₁ , 3 ₂ and 3 ₃ .

At this time, a speed voltage E proportional to the rotational speed is generated in the armature windings 3 ₁ , 3 ₂ , 3 ₃ , and the capacitor 37
given at both ends. Then, voltages Va and Vb are generated at the connection points a and b of the bridge circuit, respectively. When the voltage E corresponds to a predetermined speed or higher, the transistor 44 is activated by the difference voltage V _BE between the voltages Va and Vb. This turns on transistor 29.
is turned off and the power supply 2 of the position detection circuits 31, 32, 33 is turned off.
6 and decelerate the motor.

Further, when the speed decreases and the voltage E becomes a value corresponding to a predetermined speed or less, the voltage difference V _BE between the voltages Va and Vb becomes smaller, turning off the transistor 44 and turning on the transistor 29 to accelerate the motor.

Therefore, the electric motor is controlled so as to always approach the predetermined speed, so that the rotating body 5 is rotated at the predetermined speed.

With the above configuration, the rotating body with the turntable attached is floated and supported by the attractive force of the DC electromagnets divided into at least three parts, and guided and supported around the rotating body by the attractive force of the DC electromagnets divided into four parts, and the non-contact electric motor is used. Since it is rotatably driven, it has the following effects compared to conventional bearings. (1) Since the turntable is rotationally driven without contact, noise that accompanies rotation, that is, rumbling noise, can be eliminated. (2) Since there is no frictional resistance, the rotational torque can be reduced and it can be driven with small electric power. (3) By using a flat electric motor for rotational drive and utilizing the attractive force between the armature core and the rotor, the DC electromagnet for floating and supporting the rotating body can be made as small as possible. (4) The rotating body can always be held at the center position by the DC electromagnets placed around the rotating body.

The present invention is not limited to the above-mentioned embodiments, but can be implemented with appropriate modifications without changing the gist. For example, when the current applied to a DC electromagnet is subjected to chopper control, the current flowing at this time becomes a current containing ripples, which may generate electromagnetic noise or vibration in the DC electromagnet. Therefore, the above-mentioned electromagnetic noise or vibration may be removed by using a DC current amplifier instead of the chopper. The guide support empty length control circuit in this case is shown in FIG. DC current amplifiers 310a and 31
The input terminal 0b is connected to the series compensation circuit 303a and the inversion circuit 309.

Therefore, the guide support air length control circuit can be very simplified. Further, in the embodiment, a synchronous motor using a permanent magnet in the rotor has been described as a non-contact motor, but other types of motors can also be used as long as they are non-contact.

[Brief explanation of drawings]

1 to 8 are diagrams showing embodiments of the present invention, in which FIG. 1 is a longitudinal sectional view of a turntable device;
FIG. 2 is a top view illustrating the main parts, FIGS. 3 to 7 are block diagrams showing a control circuit, and FIG. 8 is a block diagram of a control circuit showing another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Housing, 2... Armature core, 3... Winding, 4... DC electromagnet for levitation, 5... Rotating body, 6... Rotor, 9...
Turntable, 10... Displacement meter for levitation, 11... DC electromagnet for guidance, 12... Displacement meter for guidance.

Claims (1)

[Claims] 1. A disc-shaped rotating body provided in a housing and having a turntable, a levitation electromagnet device that levitates and supports the rotating body without contact using magnetic force, an electric motor that rotates the rotating body using magnetic force, and a guide electromagnet device provided around the rotary body to maintain a space between the outer periphery of the rotating body and the inner wall of the casing; and a guide electromagnet device near the outer periphery of the disc-shaped rotary body for detecting the floating air length of the rotary body. At least three levitation displacement meters are installed in the levitation displacement meter, and the supply voltage to the levitation electromagnet device is controlled according to the detected value of the levitation displacement meter, and the rotating body is levitated without contact while maintaining a predetermined levitation length. a first control means for supporting the rotating body; a guide displacement meter for detecting the empty length between the outer periphery of the rotating body and the inner wall of the casing; A turntable driving device comprising: a second control means for controlling a supply voltage of the rotating body and guiding and supporting the rotating body while maintaining a predetermined empty length.