JPS63136998A - Drum driving system - Google Patents

Abstract

PURPOSE:To smoothly rotate a drum in a low rotating range without irregular rotation by driving a pulse motor in a sinusoidal state. CONSTITUTION:An outer rotor type pulse motor 2 in which the intervals of teeth formed on a stator and a rotor are so suitably set that a magnetic flux crossing a coil wound on the poles of the stator is varied in a sinusoidal state upon rotation of the rotor is associated in a drum 1. A pole position detecting sensor 3 outputs a sinusoidal polyphase pole position detection signal corresponding to the relative position change of the poles of the stator with respect to the rotor. A driving current of the phase corresponding to the pole position detection signal is supplied to coils 31, 32.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drum drive device suitable for use in rotationally driving, for example, the drum of a full-color copying machine or the drum of a line printer.

"Prior Art" Conventionally, attempts have been made to integrate a cylindrical drum and a motor that rotates the drum.

For example, in JP-A-49-115429, an outer rotor type pulse motor (stepping motor) is built into the drum of a line printer, and the outer rotor of this pulse motor is directly connected to the drum to drive the drum. The entire mechanism has been made smaller. On the other hand, in JP-A-51-137317, an outer rotor type synchronous motor is built into the drum, and the outer rotor of this synchronous motor is directly connected to the drum, so that the torque generated by the motor is directly applied to the drum. The aim is to reduce energy loss and noise.

``Problems to be Solved by the Invention'' By the way, in order to obtain high-quality prints, the drums of full-color copiers and line printers must rotate smoothly and without unevenness in the low-speed rotation range of about 20 rpm. rotation is required. However, although pulse motors are generally small and have the characteristics of being able to obtain high torque even in low-speed rotation regions, they have large torque ripple and are sometimes used in open loops, making it difficult to obtain smooth rotation. do not have. Therefore, when such a pulse motor is incorporated into a drum of a copying machine or a printer, deterioration in the image quality of printed matter is unavoidable. On the other hand, a synchronous motor that operates in a low-speed rotation region generally has a large external dimension.

Therefore, when such a synchronous motor is incorporated into the drum, the external dimensions of the drum drive mechanism as a whole become large, and as a result, it is not possible to downsize the drum drive mechanism.

This invention has been made in view of the above-mentioned circumstances, and even when the drum has a structure in which an outer rotor type pulse motor is incorporated, the drum can be rotated smoothly without uneven rotation in the low rotation range. It is an object of the present invention to provide a drum drive device that can produce high-quality printed matter when applied to copiers, printers, and the like.

``Means for Solving the Problems'' This invention is designed so that the magnetic flux linking the coils built into the drum and wound around each magnetic pole of the stator changes sinusoidally as the rotor rotates. An outer rotor type pulse motor in which the spacing between teeth formed on the stator and rotor is appropriately set, and a sinusoidal multiphase magnetic pole position detection signal corresponding to a relative position change of each magnetic pole of the stator with respect to the rotor. a magnetic pole position detection means for outputting;
Detecting the rotational speed of the rotor based on the magnetic pole position detection signal, calculating a speed difference between this detection result and a preset rotational speed, and outputting a current amplitude command signal according to this calculation result. The present invention is characterized by comprising a speed command means, and a current control means for supplying each coil with a drive current having an amplitude corresponding to the current amplitude command signal and a phase corresponding to the magnetic pole position detection signal.

"Operation" The pulse motor having the above configuration has the characteristics of being able to obtain a large torque despite its small size and having little torque ripple. By incorporating such a pulse motor inside the drum, the entire drive mechanism can be downsized and sufficient torque can be obtained. In addition, by supplying a drive current to each coil with a phase that corresponds to the relative position change of each magnetic pole of the stator with respect to the rotor and an amplitude that corresponds to the current amplitude command signal, high precision equivalent to servo control of a DC motor is achieved. It is possible to control the speed of the drum, and the drum can be rotated smoothly without unevenness in the low rotation range.Therefore, when applied to copying machines, printers, etc., it is possible to obtain high-quality printed matter.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the overall configuration of a drum drive device according to an embodiment of the present invention. In this figure, ■ is a drum, and inside this drum 1, an outer rotor type pulse motor 2 and a magnetic pole position sensor 3 are incorporated.

Here, first, the mechanical configuration of the pulse motor 2 and the magnetic pole position sensor 3 incorporated in the drum 1 will be explained with reference to FIG. 2. In FIG. 2, 5 is a hollow shaft fixedly attached to a base (not shown), and a motor cover 8 and a casing 9 are rotatably attached to this shaft 5 via bearings 6 and 7. There is.

The motor cover 8 and the casing 9 accommodate the pulse motor 2 and the magnetic pole position sensor 3 inside, and are inserted into the cylindrical drum l from one end thereof. They are integrally connected to each other by to, to, . . . and are rotatable about the axis of the shaft 5.

The pulse motor 2 includes a rotor It attached to the inner peripheral surface of the casing 9, and a stator 12 attached to the shaft 5 so as to face the rotor 11. The rotor 11 is a pair of motor outer cores 1
3.13, and a permanent magnet 14 sandwiched between these motor outer cores 13.13. On the other hand, the stator 12 includes a motor inner core 15 and a coil 16a.
~16h. These coils 16a=
Electric power is supplied to the motor 16h from the outside via a motor lead wire 17 arranged in the hollow part of the shaft 5. The pulse motor 2 having such a structure is classified as an outer rotor type because the rotor 11 is arranged on the outer circumferential side and the stator 12 is arranged on the inner circumferential side.
4, it is classified as a hybrid type.

This pulse motor 2 has rotor teeth T formed on the motor outer core 13 in order to reduce torque ripple. The pitch of the stator teeth T1 formed on the motor inner core 15 is determined to have a specific relationship. Such a pulse motor 2 has already been proposed by the present applicant in Japanese Patent Application No. 60-286574. That is, the pulse motor 2 has a pitch P in the motor outer core 13, as shown in FIG. 3(A). A rotor @T6 is formed, and stator teeth T with a pitch P1 are formed on eight magnetic poles 15a=15h of the motor inner core 15, and this pitch P1 is a reference pitch P.

It is set to 1.125 (9/8) times that of . As a result, as shown in FIG. 4(a), the center of the magnetic pole 15a is aligned with a certain rotor tooth T. When aligned with the center of the same magnetic pole 15
Five stator teeth T of a.

is the rotor tooth T. , respectively -90°, -45°,
These rotor teeth T0 and stator teeth T have phase differences of ±0°, +45°, and +90°.

The opposing area decreases toward both ends of the magnetic pole 15a, as shown by diagonal lines in FIG. 4(b). With this configuration, as the rotor ``l'' rotates, the magnetic flux interlinking the coils 16a to 16h of each magnetic pole 15a = 15h changes in a sinusoidal manner, and the winding induced voltage also changes in a sinusoidal manner. , the torque ripple is reduced. On the other hand, each magnetic pole 1
To explain the relative positional relationship of 5a to 15h, the fourth
As shown in the figure (a), the center of the magnetic pole 15a is aligned with a certain rotor tooth T.

When aligned with the center of the rotor tooth T, the center of the magnetic pole 15b is aligned with the center of the rotor tooth T.
0 and the phase is 90° out of phase, and the center of the magnetic pole 15c is the rotor tooth T.
0 and the phase is 180° out of phase, and the center of magnetic pole 15d is rotor T.
. The phase is shifted by 270°, and furthermore,
Magnetic poles 15a, 15b, 15c.

15d and each magnetic pole 1 located on the opposite side shifted by 180 degrees.
The centers of 5e, 15r, 15g, and 15h are rotor teeth T0
The phases are shifted by 0°, 90°, 180°, and 270°. In other words, the magnetic pole 15a located on the opposite side shifted by 180 degrees
and 15e, 15b and 15r115c and 15g% 15d
and 15h, the stator teeth T located at the center are the rotor teeth T. The phase is the same for . In addition, each magnetic pole 15a
Among the coils 16a to 16h each wound with =15h,
Coils 16a, 16e.

By connecting 16c and 16g in series, the first phase motor coil 31 shown in FIG.
b, 16f, 16d, and 16h are connected in series to configure the second phase motor coil 32 shown in FIG. For example, as shown in FIG. 3 (b), two-phase drive currents whose phases are shifted by 90 degrees, which repeatedly reverse positive and negative, are supplied to the motor coils 31 and 32 to perform so-called bipolar operation. , motor outer core 1
3 rotates in the direction of the arrow shown in FIG. 3(A). In this case, the rotor 11 has rotor teeth T per period T of the power supply frequency. It will rotate by one pitch P0.

Next, in FIG. 2, the magnetic pole position sensor 3 is composed of a sensor rotor 21 attached to the inner peripheral surface of the casing 9, and a sensor stator 22 attached to the shaft 5 so as to face the sensor rotor 21. has been done.

The sensor rotor 21 is composed of a motor outer core 23, and the sensor stator 22 is composed of a sensor inner core 25.
and sensor coils 26a to 26h.These sensor coils 26a to 26h are connected to the outside via a sensor lead wire 27 arranged in the hollow part of the shaft 5. Furthermore, a shield plate 24 is provided between the stator 12 of the shaft 5 and the sensor stator 22 to shield magnetic flux.
is installed.

This magnetic pole position sensor 3 has a pitch P of sensor rotor teeth ST formed on the sensor outer core 23 so that accurate magnetic pole position detection can be performed.

and the pitch P of the sensor stator teeth ST formed in the sensor inner core 25 are determined to have exactly the same relationship as in the pulse motor 2 described above. Such a magnetic pole position detection sensor 3 was developed by the present applicant in a patent application filed in 1986-28.
This was already proposed in No. 5126. That is, the magnetic pole position sensor 3 has a pitch P in the sensor outer core 23, as shown in FIG. 3(A). sensor rotor teeth S T,
is formed, and the eight sensor magnetic poles 25a to 25h of the sensor inner core 25 have a pitch P, (=1.125-
P o) sensor stator teeth ST are formed. As a result, when the center of the sensor magnetic pole 25a is aligned with the center of a certain sensor rotor tooth ST0, the five sensor stator teeth ST are the sensor rotor teeth T. , respectively -90°, -45°, ±θ°, +45°, +9
There is a phase difference of 0°, and the opposing area of these sensor rotor teeth ST and sensor stator teeth ST + is exactly the same as that shown by diagonal lines in FIG.
It decreases toward both ends of 5a. With such a configuration, as the sensor rotor 21 rotates, there is a gap between the sensor rotor tooth ST0 and the sensor stator tooth ST.
A substantially sinusoidal change in magnetic resistance is obtained, thereby making it possible to accurately detect the magnetic pole position. Moreover, the relative positional relationship of each sensor magnetic pole 25a to 25h is exactly the same as that of the pulse motor 2 described above. A coil 26 is wound around each sensor magnetic pole 25a to 25h.
Among a to 26h, coils 26a and 26e, 26b and 26
Excitation coils 33 to 36 shown in FIG. 1 are constructed by connecting f, 26c and 26g, and 26d and 26h in series, respectively.

This completes the explanation of the mechanical configuration of this embodiment, and next, the electrical configuration of this embodiment will be explained.

In FIG. 1, 40 is a magnetic pole position detection circuit, and this magnetic pole position detection circuit 40 was developed by the present applicant in Japanese Patent Laid-Open No. 60-28
It was already proposed in No. 5125, and its structure is in No. 5.
As shown in the figure and FIG. In FIG. 5, four shunt resistors R are connected in series to each of the excitation coils 33 to 36, each end of the four series-connected circuits are connected in common, and a carrier signal Sc is supplied to one common connection end. The other common connection end is grounded. This carrier signal Sc is, for example, an AC rectangular wave with a frequency f=5 kHz, and is supplied from the signal generator 4I.

Further, voltages (shunt voltages) 1 to V4 proportional to the currents flowing through the excitation coils 33 to 36 are taken out from the connection portions between the excitation coils 33 to 36 and the shunt resistor R. The shunt voltages ■1 to v4 are applied to the sensor rotor teeth STo and the sensor stator I when the sensor rotor 21 rotates.
This is caused by the change in magnetoresistance between sT and sT.

That is, due to this magnetic resistance change, the excitation coils 33 to
The impedance of 36 changes, thereby modulating the carrier signal Sc. Therefore, the shunt resistor R has a pitch P. The frequency F changes in response to 1001
A carrier signal modulated by a modulated wave of about -1z is obtained, and this is output as a shunt voltage Vt~4. Among these shunt voltages 1-V4, a pair of opposite-phase shunt voltages v1 and V34 are supplied to absolute value circuits 42 and 43, as shown in FIG. 6, and are full-wave rectified. Here, the output of the absolute value circuits 42 and 43 becomes a full-wave rectified waveform whose frequency is twice that of the modulated wave, that is, twice that of the carrier signal Sc. The output of the absolute value circuit 42.43 is supplied to a low-pass filter 44.45, where high frequency components contained in the output, such as the carrier signal Sc, are removed, and the pitch P is set. A signal in which the fundamental wave (frequency F) corresponding to the DC component is superimposed is output.

Then, the output of the low-pass filters 44 and 45 is output to the subtracter 4.
6, the DC component is removed by subtraction, and a fundamental wave of opposite phase is added to output a sine wave detection signal Ea having a frequency of F.

In addition, shunt voltage V2. Similar processing is performed for V4 using a similar circuit configuration, and the detection signal Ea
A detection signal Eb whose phase is shifted by 90° is output. In this case, if the relative movement amount of the sensor rotor 21 with respect to the sensor stator 22 is defined as X, then Ea=COS(2πx/Po) +・++++
(f) Eb=STN(2; rx/Po) --
It can be expressed as (2). That is, the l pitch P of the sensor rotor teeth STo with respect to the sensor stator teeth ST.

Each time the detection signals Ea and Eb move relative to each other by a distance corresponding to , the detection signals Ea and Eb repeat the cycle .

Next, in FIG. 1, 51 and 52 are multipliers that receive two-phase detection signals Ea and Eb output from the magnetic pole position detection circuit 40 and a current amplitude command output from a speed control circuit 60, which will be described later. There is one that multiplies the signals Irer and outputs them as current command signals 1a and Ib, respectively. Here, in the above equations (1) and (2), 2
By replacing yr X/ P o = θm, the multiplier 51
The signals 1a and Ib output from 52 are as follows.

I a= I rer・cosθm ・・・・・・
・ (3) Ib=Iref-sinθm
・・・・・・ (4) Multiplier 5! The current command signal 1a outputted from the subtracter 53 is supplied to the subtracter 53, and after the current feedback signal 1af is subtracted by the subtracter 53, the current command signal 1a is supplied to the current control circuit 55. Here, the current value supplied to the motor coil 3I of the pulse motor 2 is determined by the electric detector 5.
6, and the detection signal of this current detector 56 is supplied to the subtracter 53 as the current feedback signal Iaf. Then, the current control circuit 55 amplifies the difference between the current command signal 1a and the current feedback signal 1af,
The voltage applied to the motor coil 31 is changed based on this amplified signal, thereby controlling the drive current supplied to the motor coil 3I so that it always has a value corresponding to the current command signal Ia. In other words, the current control circuit 55 uses the current amplitude command signal I re output from the speed control circuit 60
The amplitude corresponds to r, and the magnetic pole position detection circuit 40
An alternating current having the same phase as the detection signal Ea (·cos θm) output from the motor coil 31 is supplied to the motor coil 31.

Similarly, the current command signal tb output from the multiplier 52 is supplied to a subtracter 54, and after being subtracted by the current feedback signal 1bf, the current command signal tb is supplied to the current control circuit 57. Here, the current value supplied to the motor coil 32 is detected by a current detector 58, and a detection signal of this current detector 58 is a current feedback signal fb.
It is supplied to the subtracter 54 as f. Then, the current detection circuit 58 amplifies the difference between the current command signal rb and the current feedback signal Ibr, changes the voltage applied to the motor coil 32 based on this amplified signal, and thereby,
Control is performed so that the drive current supplied to the motor coil 32 always has a value corresponding to the current command signal 1b. In other words,
The current control circuit 57 has an amplitude corresponding to the current amplitude command signal 1 ref output from the speed control circuit 60,
and the detection signal Eb output from the magnetic pole position detection circuit 40
An alternating current having the same phase as (-sin θm) is supplied to the motor coil 32.

As a result, the motor coil 31 receives the current command signal 1 a
(=I'ref - cosθm) is supplied, and the motor coil 32 receives a current command signal rb(
A drive current corresponding to (= r rer-sin θm) is supplied, and as a result, bipolar operation is performed using a two-phase sine wave instead of the two-phase rectangular wave shown in FIG. 3(b). In this case, the rotor l1 rotates extremely smoothly, with extremely little torque ripple.

Further, the rotor 11 has rotor teeth T for one period of the current command signal Ia or Ib. l pitch P. rotate only,
As a result, the sensor rotor teeth ST and the sensor stator teeth S
For T, its l pitch P. The rotor tooth T of the pulse motor 2 synchronizes with the relative movement by a distance corresponding to
. is l pitch P. You will only have to move. Furthermore, the torque generated in the rotor 11 is determined by the current amplitude command signal I re
It changes according to r, and the larger the current amplitude command signal 1 ref is, the larger the torque generated by the rotor 11 is.

That is, of the magnetic flux generated by the permanent magnet 14, a component φ that interlinks the motor coils 31 and 32.

and φb, φa=φ・sinθm... (
5) φb=-φ・cosθm ・・・・・・
In the case of (6), the velocity electromotive voltages Va and vb generated in the coils 31 and 32, respectively, are set as θm=ωm4 (t is time), then Va-0m・φ・cosθm...
(7) vb=ωm・φ・sinθm...
...(8). Therefore, the torque Tm generated by the motor coils 31 and 32 is as follows. Therefore, if the magnetic flux φ is constant, the torque Tm is proportional to the current amplitude command signal 1 ref, and as a result, the advantage of a DC machine that the rotation speed can be controlled only by the current amplitude command signal I ref can be applied to a pulse motor. can.

The method of controlling the rotational speed of the motor as described above is already known, for example, in "Transvector Control of AC Machine" published in Fuji Jiho, Vol. 53, No. 9.

However, the feature of the present application is that the above-mentioned method of transvector control of an AC machine is applied to the servo control of the pulse motor 2, and as a result, the pulse motor 2 can be controlled with the same smoothness as a DC machine. It is possible to rotate and achieve highly accurate speed control.

Next, in FIG. 1, 61 is a rotational position detection circuit, which generates a high-resolution pulse train corresponding to the rotational position of the drum l based on the two-phase detection signals Ea and Eb output from the magnetic pole position detection circuit 40. This rotational position detection circuit 61 outputs a position pulse train signal P'' that is
is the l pitch P of the sensor rotor teeth ST of the sensor rotor 21. The drum 1 moves by a distance corresponding to the rotation of the drum 1, and every time the detection signals Ea and Eb repeat one cycle, a position pulse train signal Pf of several hundred pulses is output. The pulse frequency corresponds to the rotational speed of the drum l.

Next, the configuration of this rotational position detection circuit 61 will be explained with reference to FIG. In FIG. 7, 70 is an oscillator that generates a reference clock pulse of a predetermined frequency, and the reference clock pulse output from this oscillator 70 is supplied to a counter 71. The counter 71 is the oscillator 7
The reference phase data θ, which is digital data, is obtained by counting the reference clock pulses supplied from 0. R for function generation
OM72,73 and latch circuit 80 are supplied.

ROM72 contains reference phase data θ. Based on the sine data sinθ. This is the sine data sinθ output from this ROM 72. is converted into an analog signal by a D/A converter 74 and supplied to a multiplier 76. On the other hand, the ROM 73 generates cosine data cos θ0 based on the reference phase data θ0, and the cosine data cos θ output from this ROM 73. is converted into an analog signal by the D/A converter 75 and supplied to the multiplier 77. Here, the reference phase data θ. The relationship between sine data sin θ0 and cosine data cos θ0 is shown in FIGS. 8(a) and 8(b). Sine data sinθ0 and cosine data cosθ converted into analog signals. In the multipliers 76 and 77, the detection signal Ea(・cosθm
) and E b (=sinθm), respectively. Then, the multiplication result sin θ of the multiplier 76 is obtained. The subtracter 78 subtracts the multiplication result cos θo-5in θm from the multiplier 77 from cos θm, and as is clear from the following relational expression %), the subtraction result 5in(θ.-θm) is obtained. The subtraction result in the subtractor 78 is 5in(θ.

-θm) is supplied to the comparator 79. As shown in FIGS. 9(a) and 9(b), this comparator 79 outputs "H
A "level signal is supplied to the latch circuit 80, and during a negative period, an "L" level signal is supplied to the latch circuit 80. The latch circuit 80 is connected to a comparator 79 as shown in FIG. 9(C) and (D). The reference phase data θ is determined at the timing when the output of the output rises to “H” level.

This latched data is regarded as data corresponding to θm, and is supplied to the digital subtracter 81 as sampling data θmt. Here, since the sampling data θmt increases stepwise by several bits as shown in FIG. 1O (a), the subtractor 8! is interpolated by a digital-order lag filter constituted by a rate multiplier 82 and a counter 83;
The count value θm' of 3 becomes the interpolated value. That is, the sampling data θmt and the count value θm' of the counter 83 are subtracted by the subtracter 81, and the difference data is supplied to the rate multiplier 82. The rate multiplier 82 thins out the reference clock pulses supplied from the oscillator 70 at a ratio according to the difference data supplied from the subtracter 81 and supplies the thinned out pulse train to the counter 83. In this case, the rate multiplier 82 supplies a pulse train of higher frequency to the counter 83 as the difference data is larger. As a result, the count value θm' of the counter 83 increases smoothly following the sampling data θmt, as shown in FIG. 10(A). Then, by taking out the least significant bit 2° of the count value θm' of the counter 83, as shown in FIG.
As shown in FIG.
A position pulse train signal Pf corresponding to the rotational position of the drum l during a period in which the sensor rotor 211) moves by a distance corresponding to 1 pitch P0 is output.

Next, returning to FIG. 1 again, 85 is an F/V (frequency/voltage) converter, which converts the frequency of the position pulse train signal Pf output from the rotational position detection circuit 61 into a voltage signal.
This voltage signal is supplied to the subtracter 86 as a speed feedback signal Vf corresponding to the rotational speed of the drum 1. On the other hand, 87 is a device command pulse train signal P configured from the outside.
In addition to up-counting the number of pulses of ref, the device pulse train signal Pf composed of the circuit position detection circuit 61
This is an up/down counter that counts down the number of pulses. The count value of this up/down counter 87,
That is, the difference data between the number of pulses of the position command pulse train signal P rer and the number of pulses of the position pulse train signal Pf is as follows.
The signal is supplied to a D/A converter 89, where it is converted into an analog signal and output as a speed reference signal Pe. The speed reference signal Pe outputted from the D/A converter 89 is supplied to a subtracter 86, and after subtracting the aforementioned speed feedback signal Vf from the subtracter 86, it is supplied to the speed control circuit 60.

The speed control circuit 60 controls the current amplitude command signal I so that the speed reference signal Pe and the speed feedback signal Vf are equal to each other.
Determine ref. In other words, the rotational speed of the pulse motor 2 (drum 1) decreases due to changes in load torque, etc.
(Speed reference signal Pe)>(Speed feedback signal vr
), the speed control circuit 60 increases the value of the current amplitude command signal 1 ref to instruct acceleration. Also, the rotational speed of the pulse motor 2 increases (speed reference signal Pe)
<(speed feedback signal vr), the speed control circuit 60 sends the current amplitude command signal 1 to instruct deceleration.
re' value is lowered.Then, the speed control circuit 60 lowers the value of (
Speed reference signal Pe) = (speed feedback signal f)
When the current amplitude command signal 1 ref
maintain the value of This causes the pulse motor 2 to always rotate at a constant rotational speed. In this case, the rotation speed of the pulse motor 2 is determined by the pulse frequency of the position command pulse train signal P ref mentioned above, and the higher the pulse frequency is set, the higher the rotation speed of the pulse motor 2 is set.

In the above configuration, the rotor of the pulse motor 2! A case will be explained in which rotation of l is avoided at a specific rotation speed. Here, in the initial state, the rotor 11 of the pulse motor 2
is assumed to have stopped at a predetermined detent point.

First, the pulse frequency of the position command pulse train signal Pref is set to a value corresponding to a specific rotational speed and is supplied to the counter 87. Since the drum 1 is currently stopped, the device pulse train signal P composed of the rotational position detection circuit 61
The pulse frequency of f is O, so the up/down counter 87 counts only the number of pulses of the position command pulse train signal P ref, and the count value becomes large transiently. As a result, (speed reference signal Pe)>(
speed feedback signal Vf), and the speed control circuit 6
0 increases the value of the current amplitude command signal 1 ref to instruct acceleration. Next, the current control circuit 55 outputs an amplitude corresponding to the current amplitude command signal I ref output from the speed control circuit 60 and has the same phase as the detection signal E a (= cos θm) output from the magnetic pole position detection circuit 40. At the same time, the current control circuit 57 supplies an alternating current of A phase alternating current is supplied to the motor coil 32. As a result, bipolar operation of the pulse motor 2 is started by the two-phase drive current, and the rotor 11 starts rotating extremely smoothly. Here, since the current amplitude command signal I ref has a high value, the rotor II is accelerated and its rotational speed gradually increases.

Next, when the rotational speed of the rotor 11 gradually increases, a position command pulse train signal Pf having a pulse frequency corresponding to the rotational speed of the rotor 11 is output from the rotational position detection circuit 61.
The up/down counter 87 receives the position command pulse train signal Pf.
count down the number of pulses. Therefore, the count value of this up/down counter 87 gradually becomes smaller. Then, the difference between the speed reference signal Pe and the speed feedback signal Vf gradually becomes smaller, and the speed control circuit 60 gradually lowers the value of the current amplitude command signal 1 ref. As a result, although the rotational speed of rotor II continues to increase, the acceleration gradually decreases.

' Next, when the rotational speed of the rotor 11 reaches a specific rotational speed, (speed reference signal Pe) = (speed feedback signal ■r), and the speed control circuit 60 adjusts the current amplitude command signal I ref' at that point. Keeping the value, from now on,
The rotor 11 continues to rotate at a specific rotational speed.

According to the embodiment described above, current control circuits 55 and 57
The voltages applied to the coils 31 and 32 are respectively controlled so that the current command signal [a and the current feedback signal 1[a, and the current command signal Ib and the N-flow feedback signal Ifb] match each other, and , coil 3
1 and 32, the speed control circuit 6
The pulse motor 2 It is now possible to rotate with the same smoothness as a DC machine, and to control the speed with high precision.

"Effects of the Invention" As explained above, according to the present invention, in the drum,
An auxiliary rotor in which the spacing between the teeth formed on the stator and rotor is appropriately set so that the magnetic flux linking the coils wound around each magnetic pole of the stator changes in a sinusoidal manner as the rotor rotates. a magnetic pole position detection means that incorporates a pulse motor and outputs a sinusoidal multiphase magnetic pole position detection signal corresponding to a relative position change of each magnetic pole of the stator with respect to the a-vertical; speed command means for detecting the rotation speed of the rotor based on the rotation speed, calculating a speed difference between this detection result and a preset rotation speed, and outputting a current amplitude command signal having a value according to the calculation result; 74. Supplying each coil with a drive current having an amplitude corresponding to the current amplitude command signal and a phase corresponding to the magnetic pole position detection signal. Since the drive mechanism is equipped with a current control means, it is possible to obtain a large torque despite the small size of the entire drive mechanism, and the current amplitude command is adjusted according to the relative position change of each magnetic pole of the stator with respect to the rotor. Since a drive current with an amplitude corresponding to the signal is supplied to each coil, highly accurate speed control equivalent to servo control of a DC motor is possible, and the drum can be rotated smoothly and evenly in the low rotation range. , which results in
When applied to copying machines, printers, etc., it is possible to obtain high-quality printed matter.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the overall electrical configuration of an embodiment of the present invention, Figure 2 is a partially cutaway front view showing the overall mechanical configuration of the embodiment, and Figure 3 (a) is the same. FIG. 3 (B) is a side view showing the internal configuration of the pulse motor 2 and magnetic pole position sensor 3 of the embodiment, and FIG. ), (
B) is a diagram for explaining the tooth arrangement of the pulse motor 2 and the magnetic pole position sensor 3; FIGS. 5 and 6 are block diagrams showing the configuration of the magnetic pole position detection circuit 40 shown in FIG. 1;
FIG. 7 is a block diagram showing the configuration of the rotational position detection circuit 61 shown in FIG. It is. ■・・・Drum, 2・・・Pulse motor,
3...Magnetic pole position sensor, 5...Shaft, 11...Rotor, 12...Stator, 15a=[5h...Magnetic pole, I6a-16h
......Coil, 31.32...Motor coil, T...Stator tooth, To...Rotor tooth, 40...Magnetic pole position detection circuit, 51.5
2... Multiplier, 53.54... Subtractor, 55.57... Current control circuit, 56.58.
...Current detector, 60... Speed control circuit,
61... Rotational position detection circuit, 85...
F/■ converter, 86...subtractor, 87...
...Up-down counter, 89...D/A converter.

Claims (1)

[Claims] The spacing between the teeth formed on the stator and rotor is appropriately set so that the magnetic flux linking the coils incorporated in the drum and wound around each magnetic pole of the stator changes in a sinusoidal manner as the rotor rotates. a magnetic pole position detection means for outputting a sinusoidal multiphase magnetic pole position detection signal corresponding to a relative position change of each magnetic pole of the stator with respect to the rotor; speed command means for detecting the rotation speed of the rotor based on the rotation speed, calculating a speed difference between this detection result and a preset rotation speed, and outputting a current amplitude command signal according to the calculation result; A drum drive device comprising current control means for supplying each coil with a drive current having an amplitude corresponding to a current amplitude command signal and a phase corresponding to the magnetic pole position detection signal.