JP2008035643A - Motor control apparatus, motor control method, and image forming apparatus to which the same is applied - Google Patents

Abstract

An object of the present invention is to reduce unevenness in the rotational speed of a motor caused by uneven magnetization related to a magnetized pattern, deviation between the center of a rotor and the center of an FG pattern, and the like.
A plurality of frequency generating means are respectively arranged opposite to a magnetized pattern provided on a rotor constituting a motor, and generate a signal having a frequency corresponding to the rotation of the motor. The rectangular wave generator generates a rectangular wave corresponding to the signal output from the corresponding frequency generator. The obtaining means obtains a parameter related to the rotational speed of the motor according to the corresponding rectangular wave. The calculation means performs a calculation for determining a parameter for controlling the rotation speed of the motor based on the parameters acquired by the plurality of acquisition means. The control means controls the rotation speed of the motor using a parameter for controlling the rotation speed of the motor.
[Selection] Figure 4

Description

  The present invention relates to a technique for controlling the rotational speed of a motor and an image forming apparatus to which the technique is applied.

  Conventionally, as a means for detecting the rotational speed of a motor, an all-round integral type FG (FG: frequency generator) is known. According to the all-round integration type FG, a multipolar magnetized pattern is formed on the rotating part of the motor, and a zigzag comb-shaped coil pattern (FG pattern) is annular on the substrate surface facing the magnetized pattern. Formed. Then, when the magnetized pattern crosses the FG pattern, an alternating current having a frequency corresponding to the rotation speed is output from the FG pattern.

A motor using such an all-round integral type FG is used to drive a rotating drum head of a video tape recorder (Patent Document 1). In recent years, it is also used for a conveying device of an image forming apparatus (Patent Document 2).
JP-A-7-213036 Japanese Patent Laid-Open No. 2001-282046

  However, in the above technique, if the magnetized pattern of the rotor is uneven or the center of the rotor is shifted from the center of the FG pattern, the FG pattern cannot accurately detect the rotational speed of the rotor. Of course, if the motor is controlled using a rotational speed with insufficient accuracy, the rotational speed will be uneven. Similarly, even if the flatness (parallelism) of the magnetized surface of the magnetized pattern with respect to the substrate surface on which the FG pattern is provided is insufficient, rotational speed unevenness occurs in the motor. Furthermore, if such uneven rotation speed occurs in the motor used to drive the photoconductor of the image forming apparatus, it is not preferable because it causes uneven image.

  Therefore, the present invention is caused by uneven magnetization related to the magnetized pattern, deviation between the center of the rotor and the center of the FG pattern, or insufficient flatness of the magnetized surface of the magnetized pattern with respect to the substrate surface provided with the FG pattern. The object is to suppress uneven rotation speed of the motor.

The present invention is realized in a motor control device, a motor control method, and an image forming apparatus. For example, the motor control device includes a plurality of frequency generation means, a plurality of rectangular wave generation means, a plurality of acquisition means, a calculation means, and a control means. Each frequency generating means is disposed opposite to the magnetized pattern provided on the rotor constituting the motor, and generates a signal having a frequency corresponding to the rotation of the motor. The rectangular wave generator generates a rectangular wave corresponding to the signal output from the corresponding frequency generator. The obtaining means obtains a parameter related to the rotational speed of the motor according to the corresponding rectangular wave. The calculation means performs a calculation for determining a parameter for controlling the rotation speed of the motor based on the parameters acquired by the plurality of acquisition means. The control means controls the rotation speed of the motor using a parameter for controlling the rotation speed of the motor.
The calculating means reduces the influence of the magnetization unevenness on the magnetization pattern and the influence of the deviation between the center of the rotor and the centers of the plurality of frequency generating means, based on the parameters respectively acquired by the plurality of acquisition means. It may be a means to do. Further, the control means may control the rotation speed of the motor using the parameter with the reduced influence.

  According to the present invention, it is caused by uneven magnetization related to the magnetization pattern, deviation between the center of the rotor and the center of the FG pattern, or insufficient flatness of the magnetization surface of the magnetization pattern with respect to the substrate surface on which the FG pattern is provided. Unevenness in the rotation speed of the motor can be reduced.

  An embodiment of the present invention is shown below. Of course, the individual embodiments described below will be helpful in understanding various concepts such as the superordinate concept, intermediate concept and subordinate concept of the present invention. Further, the technical scope of the present invention is determined by the scope of the claims, and is not limited by the following individual embodiments.

[Related technologies]
FIG. 1 is a diagram showing a drive control circuit for a DC brushless motor using an all-round integral type FG according to the related art of the present invention. The DC brushless motor 40 includes a coil 43 and a rotor 44 in which three phases of U, V, and W are star-connected.

  Magnetic poles S and N are alternately magnetized on the inner side (mainly magnetized surface) of the rotor 44. The rotor 44 is rotated by the magnetic field generated by the coil 43. Further, as a means for detecting the position of the rotor, three Hall elements 42 for detecting the magnetic poles of the rotor are provided.

  A frequency generator (hereinafter referred to as FG pattern) 45 is used to detect the rotational speed of the rotor. The FG pattern 45 is a comb coil pattern formed in an annular shape on the substrate. In addition to the main magnetized surface, the magnetic poles S and N are alternately magnetized at equal intervals on the surface facing the FG pattern (FG magnetized surface). As the rotor 44 rotates, a minute alternating current is generated in the FG pattern 45 by electromagnetic induction.

  The FG pulse generator 13 generates a rectangular wave corresponding to the signal output from the FG pattern 45. The FG pulse generator 13 includes an FG amplifier 14, a hysteresis amplifier 15, resistors 16 and 19, capacitors 17 and 20, and a reference power supply 18.

  The ASIC (application specific integrated circuit) 10 includes a speed detection unit 51 and a speed control unit 52. Reference numeral 12 denotes a CPU. 21 is a charge pump circuit. 22 and 23 are capacitors. Reference numeral 24 denotes a resistor. Reference numeral 25 denotes a PWM generator. Reference numeral 26 denotes a pre-driver circuit. Reference numeral 27 denotes a motor drive circuit. The motor drive circuit 27 includes upper stage transistors 28U, 28V, 28W for driving each phase of the coil 43, and lower stage transistors 29U, 29V, 29W.

  Next, these operations will be described in detail. The CPU 12 outputs a target speed signal indicating the target speed of the motor to the ASIC 10. When the target speed signal is input to the speed control unit 52, the speed control unit 52 compares the motor rotation speed detected by the speed detection unit 51 with the target speed. When the motor rotation speed is slower than the target speed, the speed control unit 52 outputs an acceleration signal (ACC) to the charge pump circuit 21 that outputs the acceleration signal (ACC) to the charge pump circuit 21. On the other hand, when the motor rotation speed is faster than the target speed, the speed control unit 52 outputs a deceleration signal (DEC) to the charge pump circuit 21.

  When ACC is input, the charge pump circuit 21 charges the capacitor 22 and the series connection circuit of the capacitor 23 and the resistor 24. On the other hand, when DEC is input, the charge pump circuit 21 discharges the charges charged therein.

  The PWM generator 25 generates a PWM signal in which ON-DUTY is changed according to the voltage value of the capacitor 22 and outputs the PWM signal to the pre-driver 26. ON-DUTY means the width of the section that is ON and the width of the section that is OFF. The pre-driver 26 controls the switching timing of the motor drive signals (UU, UV, UW, LU, LV, LW) output to the motor drive circuit 27 based on the output signals HU, HV, HW from the respective hall elements 42. As a result, the rotor 44 is rotated. The pre-driver 26 controls the ON-DUTY of the motor drive signal according to the PWM signal output from the PWM generator 25. Thereby, the output torque of the motor 40 is controlled.

  When the rotor 44 rotates, a minute alternating current is generated in the FG pattern 45. The alternating current generates an alternating voltage based on the voltage of the reference power supply 18 at the differential input terminal of the FG amplifier 14 through the capacitors 17 and 20 and the resistors 16 and 19. The FG amplifier 14 compares the AC voltage with the voltage of the reference power supply 18 and outputs a rectangular wave (FG pulse) corresponding to the frequency of the AC voltage. The hysteresis amplifier 15 removes noise superimposed on the FG pulse. An FG pulse having a frequency proportional to the rotational speed of the rotor 44 is output to the speed detector 51 in the ASIC 10.

  For example, the speed detection unit 51 calculates a parameter related to the motor rotation speed (here, the motor rotation speed itself) by counting the intervals of the falling edges of the output pulses of the FG pulse generator 13. The speed detection unit 51 outputs the calculated rotation speed value to the speed control unit 52. As described above, the speed control unit 52 compares the motor rotation speed with the target speed input from the CPU 12. By operating the motor control device as described above, the motor 40 can be rotated at a constant speed even if the load torque of the motor 40 varies.

  FIG. 2 is a diagram for explaining the rotational speed unevenness in the case where the magnetic unevenness occurs on the FG magnetized surface of the rotor and the center of the rotor and the center of the FG pattern are displaced. Specifically, the rotor 44 and the FG pattern 45 are shown enlarged.

  Reference numeral 61 denotes the center position of the FG pattern 45. Reference numeral 62 denotes the rotation center of the rotor 44. The rotation center may be the rotation axis or the center of the magnetized pattern. According to FIG. 2, the center of the FG pattern 45 and the rotation center of the rotor 44 are shifted. Therefore, there are a region where the intersection area between the FG pattern 45 and the FG magnetized surface of the rotor 44 is large and a region where the intersection area is small. Further, the FG magnetized surface of the rotor 44 has a portion having a narrow magnetization interval (dense) and a portion having a wide magnetization interval (coarse) due to uneven magnetization.

  FIG. 3 is a diagram illustrating an example of an alternating current waveform and an FG pulse waveform according to the related art. More specifically, each of the FG pulse waveform when the state shown in FIG. 2 is 0 ° and the rotor is rotated once in the direction of the arrow, and when the FG pattern 45 is divided into three regions A, B, and C. The alternating current waveform in the region is shown.

The peak value of the alternating current waveform increases as the crossing area between the FG pattern 45 and the FG magnetized surface of the rotor 44 increases. Therefore, the peak value of the region A having a large intersection area is relatively high. On the other hand, the peak values of the regions B and C having a small intersection area are relatively low. Next, an alternating current waveform in each region will be described. In the region A, a portion where the magnetization interval of the FG magnetized surface is dense passes from 0 ° to 90 °, and a rough portion passes from 180 ° to 270 °. On the other hand, in the region B, a portion where the magnetizing interval of the FG magnetized surface is dense passes from 120 ° to 210 °, and a rough portion passes from 300 ° to 30 °. However, the peak value of region B is lower than that of region A. The same applies to the region C. A portion where the magnetization interval of the FG magnetized surface is dense passes from 240 ° to 330 °, and a rough portion passes from 60 ° to 150 °. However, the peak value of region C is lower than that of region A.

  The alternating current waveform of the entire FG pattern 45 is a composite waveform of the alternating current waveforms of the regions A, B, and C. However, since the peak values of regions B and C are lower than the peak value of region A, the combined waveform is almost similar to the waveform of region A. As a result, although the motor 40 rotates at a constant speed, the FG pulse generated by the FG pulse generator 13 has a coarse and dense pulse waveform as shown in FIG.

  When such a rough pulse waveform is input to the ASIC 10, the ASIC 10 controls the speed of the motor so as to cancel the coarseness, and thus the rotational speed unevenness occurs in the motor 40.

  Usually, in order to reduce such rotation unevenness, high-precision production processes such as prevention of uneven magnetization of the FG magnetized surface during manufacture of the motor and prevention of center misalignment between the rotor and the FG pattern are possible. Is required. However, increasing the accuracy of the production process is not preferable because it reduces the manufacturing efficiency of the motor.

[Embodiment 1]
FIG. 4 is a block diagram illustrating a circuit configuration of the motor control device according to the first embodiment. The motor control apparatus according to this embodiment will be applied as a drive circuit for a DC brushless motor used for driving a photosensitive member, for example. Note that parts that are the same as or similar to the configuration of the related art are denoted by the same reference numerals to simplify the description.

  As can be seen from comparison with the related art, three FG patterns 45A, B and C are provided as a plurality of frequency generating means for generating a signal having a frequency corresponding to the rotation of the motor. The three FG patterns 45A, B, and C are arranged in each circumferential region obtained by dividing the circumference along the rotation direction of the rotor into a plurality of pieces. According to FIG. 4, each circumferential area is equally divided. Further, three FG pulse generators 13A, B, and C are provided corresponding to the three FG patterns 45A, B, and C, respectively. The FG pulse generators 13A, B, and C generate rectangular waves corresponding to signals output from the corresponding FG patterns 45A, B, and C, respectively. Note that the subscripts A, B, and C are omitted when common items are described.

  Similarly, three speed detectors 51A, B, and C are provided. The speed detectors 51A, B, and C detect or acquire parameters (eg, pulse width, angular velocity, etc.) related to the rotational speed of the motor, respectively, according to the corresponding rectangular wave (FG pulses A, B, C). .

  Based on some or all of the above parameters, the average value calculation unit 65 reduces the influence of magnetization unevenness on the magnetization pattern and the influence of deviation between the center of the rotor 44 and the centers of the plurality of FG patterns 45. The operation for is performed. For example, the average value calculation unit 65 acquires an average value of parameters to be calculated, and outputs the acquired average value to the speed control unit 52.

  FIG. 5 is a diagram illustrating a part of the three-phase DC brushless motor according to the embodiment. With reference to FIG. 5, the motor rotation speed detection operation in the case where magnetization unevenness occurs on the FG magnetized surface and the center of the rotor and the center of the FG pattern are displaced will be described in more detail.

  As can be seen from FIG. 5, the rotation center 62 of the rotor 44 is disposed so as to be relatively shifted from the centers 61 of the FG patterns 45 </ b> A, B and C. As a result, the crossing area with the FG magnetized surface of the rotor 44 is relatively large for the FG pattern 45A, but the crossing area with the FG magnetized surface is relatively small for the FG patterns 45B and 45C. . Further, the FG magnetized surface of the rotor 44 has a portion having a narrow magnetization interval (dense) and a portion having a wide magnetization interval (coarse) due to uneven magnetization. Note that it can be understood that the FG pattern 45 is changed from one to three as compared with the related technique shown in FIG.

  FIG. 6 is a diagram illustrating an example of an alternating current waveform and an FG pulse waveform according to the embodiment. Specifically, the AC current waveform of each FG pattern 45 when the rotor 44 is rotated once in the arrow direction with the state shown in FIG. 3 being 0 °, the FG pulse waveform output from each FG pulse generator 13, And the pulse waveform which averaged the pulse width of each FG pulse is shown.

  As already described with reference to FIG. 3, the peak value of the alternating current waveform increases as the crossing area between the FG pattern 45 and the FG magnetized surface of the rotor 44 increases. Therefore, the peak value of the alternating current waveform generated in the FG pattern 45A having a large intersection area is high, and the peak values of the FG patterns 45B and 45C having a small intersection area are low.

  Next, an alternating current waveform and an FG pulse waveform in each FG pattern will be described. As for the FG pattern 45A, a portion where the magnetizing interval of the FG magnetized surface is dense passes from 0 ° to 90 °, and a rough portion passes from 180 ° to 270 °. The alternating current generated by the FG pattern 45A is converted into an alternating voltage input to the FG pulse generator 13A. The FG amplifier 14 of the FG pulse generator 13A compares the AC voltage with the voltage of the reference power source 18 and outputs a pulse signal corresponding to the frequency of the AC voltage. Then, the pulse signal (FG pulse A) from which noise has been removed by the hysteresis amplifier 15 is output to the speed detector 51A in the ASIC 10.

  On the other hand, with respect to the FG pattern B, a portion where the magnetization interval of the FG magnetized surface is dense passes from 120 ° to 210 °, and a rough portion passes from 300 ° to 30 °. The FG pulse generator 13B outputs the FG pulse B to the speed detector 51B. The same applies to the FG pattern C. A portion with a dense FG magnetization surface passes from 240 ° to 330 °, and a rough portion passes from 60 ° to 150 °. The FG pulse generator 13C outputs the FG pulse C to the speed detector 51C.

  Each speed detector 51A, 51B, 51C measures, for example, the interval of the falling edges of the input FG pulses A, B, C using a counter or the like. This measured interval is a parameter related to the motor rotation speed. The value of the motor rotation speed output from each speed detection unit 51A, 51B, 51C is input to the average value calculation unit 65. The average value calculation unit 65 calculates an average value from the values of the respective motor rotation speeds as a reduction process, and outputs the calculated average value to the speed control unit 52.

  As shown in FIG. 6, the waveform of the pulse obtained by averaging the pulse widths of the FG pulses (averaged FG pulse) is relatively smaller than the original FG pulses A, B, and C. You can understand that it is stable. That is, even when magnetization unevenness occurs on the FG magnetized surface and a deviation occurs between the center of the rotor and the center of the FG pattern, the information on the motor rotation speed input to the speed control unit 52 is not dense. Stable speed information. If stable speed information with no density can be used, the speed controller 52 can stabilize the motor rotation speed.

  As described above, according to the present embodiment, the unevenness of the rotation speed of the motor is suppressed by executing the process of reducing the influence of the uneven magnetization related to the magnetization pattern and the deviation between the center of the rotor and the center of the FG pattern. it can.

  In particular, by arranging a plurality of FG patterns for generating a frequency in each circumferential region obtained by dividing the circumference along the rotation direction of the rotor into a plurality, the influence of the size of the crossing area of each circumferential region Etc. can be suitably detected. Of course, if each circumferential area is divided equally, the influence in each circumferential area will be detected more suitably.

  Further, as a reduction means, if an arithmetic unit that averages motor rotation speeds (pulse widths) respectively acquired by a plurality of FG patterns, a plurality of pulse generators, and a plurality of speed detection units is employed, it is relatively easy. With such a configuration, the above-described adverse effects can be suitably reduced. Note that it is desirable to provide three or more FG patterns, pulse generators, and speed detectors physically or logically. However, as long as the pulse waveform in each circumferential region can be obtained independently as a result, the number of these units may be any number. For example, only one FG pattern may be physically provided, and only one pulse generator and velocity detection unit may be provided physically.

[Embodiment 2]
In the first embodiment, a case has been described in which uneven magnetization occurs on the FG magnetized surface and a deviation occurs between the center of the rotor and the center of the FG pattern. Therefore, in the second embodiment, a case will be described in which magnetization unevenness occurs on the FG magnetized surface and the FG magnetized surface cannot maintain flatness with respect to the FG pattern (substrate surface). The flatness may be called parallelism.

  FIG. 7 is a diagram illustrating an example of a three-phase DC brushless motor according to the embodiment. Parts already described are given the same reference numerals.

  According to FIG. 7, the rotation center of the rotor 44 coincides with the centers of the FG patterns 45A, B, and C. However, the FG magnetized surface and the substrate surface on which the FG pattern is provided are not completely parallel. Therefore, there are a place where the distance between the FG magnetized surface and the FG pattern is short (near) and a place where the distance is far (far). Further, the FG magnetized surface of the rotor 44 has a portion having a narrow magnetization interval (dense) and a portion having a wide magnetization interval (coarse) due to uneven magnetization. As a result, there are places where the distance between the FG magnetized surface and the FG pattern is close and the magnetizing interval is close, and where the distance between the FG magnetized surface and the FG pattern is far and the magnetizing interval is coarse.

  FIG. 8 is a diagram illustrating an example of an alternating current waveform, an FG pulse waveform, and an averaged FG pulse waveform according to the embodiment. Each waveform is a waveform obtained when the state shown in FIG. 7 is 0 ° and the rotor is rotated once in the arrow direction.

  The peak value of the alternating current waveform becomes higher as the distance between the FG pattern 45 and the FG magnetized surface of the rotor 44 is closer. Therefore, in the case of FIG. 7, the peak value of the alternating current waveform at a close distance and a close magnetization interval is relatively high. On the other hand, the crest value at a long distance and a coarse magnetization interval is relatively low.

  Next, an alternating current waveform and an FG pulse waveform in each FG pattern will be described. As for the FG pattern 45A, a portion where the distance between the FG magnetized surface and the FG pattern is close and the magnetizing interval is close passes from 0 ° to 90 °. Further, a portion where the distance between the FG magnetized surface and the FG pattern is long and the magnetizing interval is coarse passes from 180 ° to 270 °. As can be seen from FIGS. 7 and 8, the FG patterns 45B and 45C are out of phase with the FG pattern 45A.

  If an alternating current waveform is detected by a related technique, an FG pulse depending on the magnetization interval where the distance between the FG magnetized surface and the FG pattern is short will be output. Therefore, in the related technique in which only one FG pattern is provided, there is a possibility that it is erroneously detected that the rotation is faster than the actual rotation speed.

  On the other hand, in the present embodiment, by using the motor control device shown in FIG. 4, an FG pulse in which the pulse widths of the FG pulses A, B, and C are averaged is obtained. FIG. 8 also shows an averaged FG pulse waveform output from the average value calculation unit 65.

  As can be seen from FIG. 8, the averaged FG pulse waveform is caused by the occurrence of uneven magnetization on the FG magnetized surface and the flatness of the FG magnetized surface being not maintained with respect to the FG pattern (substrate surface). The impact has been reduced. That is, the information on the motor rotation speed input to the speed control unit 52 is speed information that is not dense and is very close to the actual motor rotation speed. Therefore, the motor control device according to the second embodiment can rotate the motor 40 with a more accurate and stable rotation speed.

[Embodiment 3]
In general, an image forming apparatus such as a laser beam printer changes the image forming speed depending on the material and thickness of the paper. For example, when an image is formed on an OHT (overhead transparency) sheet having a large heat capacity, the image forming speed is changed to half (1/2 speed). As a result, sufficient heat is applied to the sheet and the developer in the heat fixing device, and the occurrence of fixing failure is suppressed. Note that the sheet may be called a sheet, a recording material, a recording medium, a transfer material, a transfer medium, or the like.

  By the way, the average value calculation unit of the motor control device described above is required to have a higher processing capability when the rotation speed of the motor is high. However, the inertial force of the motor increases as the rotational speed increases. As a result, at the normal speed (1 / 1st speed), even if the speed control of the motor is performed so as to cancel the density generated in the FG pulse, the motor speed cannot follow due to the large inertial force. The motor will continue to rotate at a constant speed.

  Therefore, in the present embodiment, the processing capability of the average value calculation unit is reduced by changing the reference number of FG pulses used when acquiring parameters related to the motor rotation speed in accordance with the motor rotation speed. The configuration will be described.

  FIG. 9 is a diagram illustrating an example of a circuit configuration of the motor control device according to the embodiment. Parts that are the same as or similar to those already described are given the same reference numerals to simplify the description.

  As can be seen from comparison with FIG. 4, the CPU 12 inputs a switching signal of the FG pulse reference number to the average value calculation unit 65. The CPU 12 changes the switching signal according to the target speed of the motor. The CPU 12 determines the target speed of the motor according to the image forming speed.

  FIG. 10 is a flowchart illustrating an example of a motor control method according to the embodiment. In step S <b> 1001, the CPU 12 determines whether or not the image forming speed, that is, the target speed designated for the motor is equal to or less than a threshold value (for example, 1/2 speed).

  If it is equal to or smaller than the threshold value, the process proceeds to step S1002, and the CPU 12 instructs the average value calculator 65 to calculate the rotational speed of the motor with reference to all the FG pulses. On the other hand, when the threshold value is exceeded (for example, when the target speed is 1/1 speed), the process proceeds to step S1003 and the CPU 12 refers to only the FG pulse A to calculate the rotation speed of the motor. 65 is instructed.

  According to the present embodiment, the motor control device calculates the rotation speed of the motor with reference to more FG patterns than the reference number at the time of high-speed rotation during low-speed rotation at which uneven rotation of the motor is likely to occur. Therefore, it is possible to prevent motor rotation unevenness that is likely to occur during low-speed rotation.

  Further, during normal speed (high speed) rotation at which uneven rotation of the motor is unlikely to occur, the processing capability required for the average value calculation unit can be reduced by omitting or stopping the average value calculation.

[Embodiment 4]
An image forming apparatus will be described as an application example of the motor control apparatus according to the present invention. Note that the image forming apparatus is merely an example.

  FIG. 11 is a schematic cross-sectional view of the electrophotographic image forming apparatus according to the embodiment. The image forming apparatus 101 includes the following components.

  When the motor 40 drives the paper feed roller 104 and the pair of transport rollers 105 and 106, the paper P is transported in the direction of the arrow. Further, an electrostatic latent image is formed on the photosensitive drum 110 while the photosensitive drum 110 is rotated by the motor 40. The surface of the photosensitive drum is charged in advance by a charger 111. The electrostatic latent image formed on the photosensitive drum 110 is developed by the developing device 112. Further, a developer (eg, toner) image is transferred to the paper P by the transfer unit 113. The developer image on the paper P is fixed on the paper P by the thermal fixing device 114.

  The paper P output from the heat fixing device 114 is conveyed by a pair of paper discharge rollers 117 driven by the motor 40. Finally, the paper P is discharged out of the apparatus by the face-down paper discharge roller pair 118 driven by the motor 40.

  Here, at least one of the photosensitive drum 110, the charger 111, the developing device 112, and the transfer unit 113 is driven by a motor 40 that is a driving device. Of course, it goes without saying that the rotation speed of the motor 40 is controlled by the motor control device according to the present invention. Since the rotation speed of the motor 40 is stabilized, the quality of the formed image is also improved.

[Other Embodiments]
In the above-described embodiment, the FG pattern is described as being arranged in each circumferential region obtained by dividing the rotor into three equal parts on the circumference of the rotor, but the present invention is not limited to this. That is, the greater the number of divisions, the better the accuracy of detecting the rotational speed.

  In the above-described embodiment, the motor rotation control is executed by calculating the average value of the motor rotation speed detected in each FG pattern. However, the calculation method for reduction is not limited only to the calculation of the average value. For example, the motor control device may execute the rotation control of the motor 40 using the sum of the rotation speeds detected by the FG patterns. In any case, any arithmetic processing may be employed as long as the above-described adverse effects can be reduced.

It is a figure which shows the drive control circuit of the DC brushless motor using the circumference integration type FG based on the related technology of this invention. It is a figure for demonstrating the rotational speed nonuniformity in case the magnetization nonuniformity generate | occur | produces in the FG magnetizing surface of a rotor, and the shift | offset | difference arises in the center of a rotor and the center of FG pattern. It is a figure which shows an example of the alternating current waveform and FG pulse waveform which concern on related technology. It is a block diagram which shows the circuit structure of the motor control apparatus which concerns on 1st Embodiment. It is the figure which illustrated a part of three-phase DC brushless motor concerning an embodiment. It is a figure which shows an example of the alternating current waveform and FG pulse waveform which concern on embodiment. It is a figure which shows an example of the three-phase DC brushless motor which concerns on embodiment. It is a figure which shows an example of the alternating current waveform, FG pulse waveform, and averaged FG pulse waveform which concern on embodiment. It is a figure which shows an example of the circuit structure of the motor control apparatus which concerns on embodiment. It is a flowchart which shows an example of the motor control method which concerns on embodiment. 1 is a schematic cross-sectional view of an electrophotographic image forming apparatus according to an embodiment.

Explanation of symbols

10: ASIC
12: CPU
13: FG pulse generator 14: FG amplifier 15: hysteresis amplifier 16, 19: resistor 17, 20: capacitor 18: reference power supply 21: charge pump circuit 22, 23: capacitor 24: resistor 25: PWM generator 26: pre-driver Circuit 27: Motor drive circuit 28, 29: Transistor 40: DC brushless motor 42: Hall element 43: Coil 44: Rotor 45: Frequency generator (FG pattern)
51: Speed detection unit 52: Speed control unit 65: Average value calculation unit

Claims (9)

A plurality of frequency generating means, each of which is arranged opposite to a magnetized pattern provided on a rotor constituting the motor and generates a signal having a frequency corresponding to the rotation of the motor;
A plurality of rectangular wave generating means that respectively generate rectangular waves according to signals output from the corresponding frequency generating means;
A plurality of acquisition means for acquiring parameters related to the rotational speed of the motor according to the corresponding rectangular wave;
Calculation means for executing a calculation for determining a parameter for controlling the rotation speed of the motor based on the parameters respectively acquired by the plurality of acquisition means;
Control means for controlling the rotational speed of the motor using the determined parameter. The computing means is
Reduces the influence of uneven magnetization on the magnetized pattern and the influence caused by insufficient flatness of the magnetized surface of the magnetized pattern with respect to the substrate surface on which the plurality of frequency generating means are provided. The motor control device according to claim 1, wherein a reduction process is performed.   3. The motor control device according to claim 1, wherein each frequency generation unit is arranged in each circumferential region formed by dividing a circumference along a rotation direction of the rotor into a plurality of parts.   The motor control device according to claim 3, wherein each circumferential region is equally divided. The reduction process is:
5. The motor control device according to claim 1, further comprising an averaging process for acquiring an average value of the plurality of parameters acquired by the plurality of acquisition means.   6. The apparatus according to claim 1, further comprising a changing unit that changes the number of the parameters used by the calculation unit or the control unit in accordance with a target speed designated for the motor. The motor control apparatus described.   7. The motor control device according to claim 1, wherein three or more frequency generating means are provided. An image forming apparatus for forming an image,
A motor control device according to any one of claims 1 to 7;
An image forming apparatus comprising: a motor controlled by the motor control device. A method for controlling a motor,
A step of generating a signal having a frequency corresponding to the rotation of the motor by a plurality of frequency generating means respectively disposed opposite to the magnetization pattern provided in the rotor constituting the motor;
Generating a rectangular wave corresponding to a signal output from the corresponding frequency generation means;
Obtaining a parameter related to the rotational speed of the motor according to the corresponding rectangular wave;
Performing an operation for determining a parameter for controlling the rotational speed of the motor based on the acquired parameters;
And controlling the rotational speed of the motor using the determined parameter.

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