JP2020162199A - Twin-driving apparatus and motor control method - Google Patents

Abstract

To prevent a stepping motor from getting out of step by appropriately adjusting an assisting amount of a brushless motor according to twin-driving of the stepping motor and the brushless motor.SOLUTION: A twin-driving apparatus comprises a stepping motor, a brushless motor, a drive mechanism for rotationally moving the same load using the stepping motor and the brushless motor, and a control part for controlling operations of the stepping motor and the brushless motor. A rotation axis in the brushless motor or a rotation axis in the drive mechanism is provided with an encoder. The control part calculates an angle deviation amount of the stepping motor by comparing a pulse signal that drives the stepping motor with a pulse signal output from the encoder to increase/decrease an output of the brushless motor according to the angle deviation amount.SELECTED DRAWING: Figure 4

Description

The present invention relates to a twin drive device and a motor control method, and more particularly to a twin drive device for rotating the same load by using a stepping motor and a brushless motor, and a motor control method in the twin drive device.

In recent years, with the increase in speed of image forming devices such as MFPs (Multi-Functional Peripherals), it has been required to shorten the acceleration time of a transfer roller that conveys a recording medium and increase the target speed. However, since the output torque of the general-purpose stepping motor used in the image forming apparatus is insufficient, step-out is likely to occur, and the transfer roller cannot be accelerated in a short time. Further, when an expensive stepping motor having a large output torque is used, it is necessary to constantly flow an excessive current in order to secure a torque margin, which causes a problem that power consumption increases.

In response to this problem, Patent Document 1 below describes a stepping motor, a brushless motor, and a first power transmission unit that transmits the power of the stepping motor to the drive shaft, and is a connection for transmitting power to the drive shaft. A first power transmission unit that can switch between a state and a release state that releases transmission, a second power transmission unit that transmits the power of the brushless motor to the drive shaft, the stepping motor, the brushless motor, and the first. 1 The control unit includes a control unit that controls a power transmission unit and controls the transmission of power to the drive shaft, and the control unit accelerates the rotation of the drive shaft to a predetermined speed in the first operation phase. In the second operation phase in which the power of both the motor and the brushless motor is transmitted to drive the drive shaft, and after the first operation phase, the drive shaft is rotated at a constant speed at the predetermined speed, the first power is generated. A drive device that releases the power transmission of the stepping motor by the transmission unit and drives the drive shaft only by the brushless motor is disclosed.

JP-A-2018-161003

In Patent Document 1, one roller shaft is driven by using both a stepping motor and a brushless motor including an encoder (referred to as twin drive), and the brushless motor is operated according to the driving condition of the stepping motor. The connection and disconnection to the drive shaft are switched. However, in the above technology, the rotation of the stepping motor is controlled by the drive pulse signal, and the rotation of the brushless motor is controlled by the pulse signal output from the encoder. Therefore, when a sudden load torque is generated, the brushless motor can be operated. There is a problem that the stepping motor cannot be properly assisted and step-out of the stepping motor cannot be prevented.

The present invention has been made in view of the above problems, and a main object thereof is to appropriately adjust the assist amount of the brushless motor in the twin drive of the stepping motor and the brushless motor to detun the stepping motor. It is an object of the present invention to provide a twin drive device and a motor control method which can be prevented.

One aspect of the present invention is a stepping motor, a brushless motor, a drive mechanism for rotating the same load using the stepping motor and the brushless motor, and control for controlling the operation of the stepping motor and the brushless motor. The control unit has an encoder on the rotation shaft of the brushless motor or the rotation shaft of the drive mechanism, and the control unit compares a pulse signal for driving the stepping motor with a pulse signal output from the encoder. Then, the amount of angular deviation of the stepping motor is calculated, and the output of the brushless motor is increased or decreased according to the amount of angular deviation.

One aspect of the present invention includes a stepping motor, a brushless motor, and a drive mechanism for rotating the same load using the stepping motor and the brushless motor, and the rotating shaft of the brushless motor or the drive mechanism. This is a motor control method in a twin drive device having an encoder on the rotation axis of the above, and the amount of angular deviation of the stepping motor is calculated by comparing the pulse signal for driving the stepping motor with the pulse signal output from the encoder. It is characterized in that the calculation step and the control step of increasing / decreasing the output of the brushless motor according to the amount of the angle deviation are executed.

According to the twin drive device and the motor control method of the present invention, in the twin drive of the stepping motor and the brushless motor, the assist amount of the brushless motor can be appropriately adjusted to prevent the stepping motor from stepping out.

The reason is that the twin drive device includes a stepping motor, a brushless motor, a drive mechanism that rotates the same load using the stepping motor and the brushless motor, and a control unit that controls the operation of the stepping motor and the brushless motor. The control unit has an encoder on the rotation axis of the brushless motor or the rotation axis of the drive mechanism, and the control unit compares the pulse signal for driving the stepping motor with the pulse signal output from the encoder to shift the angle of the stepping motor. This is because the amount is calculated and the output of the brushless motor is increased or decreased according to the amount of angular deviation.

It is a schematic diagram which shows the structure of the image forming apparatus which concerns on one Example of this invention. It is a block diagram which shows the structure of the image forming apparatus which concerns on one Example of this invention. It is a schematic diagram which shows the structure of the twin drive device which concerns on one Example of this invention. It is a block diagram explaining the twin drive which concerns on one Example of this invention. It is a waveform diagram which shows the pulse signal of a stepping motor and the pulse signal of an encoder in the twin drive device which concerns on one Example of this invention (when the frequency of the pulse signal of a stepping motor is an integral multiple of the frequency of the pulse signal of an encoder). .. It is a waveform diagram which shows the pulse signal of a stepping motor and the pulse signal of an encoder in the twin drive device which concerns on one Example of this invention (when the frequency of the pulse signal of a stepping motor is not an integral multiple of the frequency of the pulse signal of an encoder). .. It is a figure which shows the phase calibration of the pulse signal of a stepping motor and the pulse signal of an encoder in the twin drive device which concerns on one Example of this invention. It is a figure which shows the relationship between the deviation of the pulse signal of a stepping motor and the pulse signal of an encoder, and the speed of a motor in the twin drive device which concerns on one Example of this invention. It is a flowchart which shows the operation of the twin drive device which concerns on one Embodiment of this invention. It is a flowchart which shows the operation of the twin drive device which concerns on one Embodiment of this invention.

As shown in the background technology, the general-purpose stepping motor used in the image forming apparatus has insufficient output torque, so that step-out is likely to occur, and the transfer roller cannot be accelerated in a short time. Further, when an expensive stepping motor having a large output torque is used, it is necessary to constantly flow an excessive current in order to secure a torque margin, which increases power consumption.

To solve this problem, Patent Document 1 proposes twin drive in which one roller shaft is driven by using both a stepping motor and a brushless motor provided with an encoder. In the above technique, the stepping motor has a drive pulse signal. The rotation is controlled by the brushless motor, and the rotation of the brushless motor is controlled by the pulse signal output from the encoder. Therefore, when a sudden load torque is generated, the brushless motor cannot properly assist the stepping motor. There is a problem that step-out of the stepping motor cannot be prevented.

Therefore, in one embodiment of the present invention, in the twin drive configuration, the amount of angular deviation of the stepping motor is increased by using the pulse signal output from the encoder provided on the rotary shaft (or the rotary shaft of the drive mechanism) of the brushless motor. (The amount of deviation between the angle estimated from the pulse signal that drives the stepping motor and the angle specified based on the pulse signal output from the encoder) is monitored, and the amount of angle deviation is large due to sudden fluctuations in load torque. In that case, the output of the brushless motor is increased to increase the assist amount and prevent the stepping motor from stepping out.

Specifically, the twin drive device includes a stepping motor, a brushless motor, a drive mechanism that rotates the same load using the stepping motor and the brushless motor, and a control unit that controls the operation of the stepping motor and the brushless motor. The control unit has an encoder on the rotation axis of the brushless motor or the rotation axis of the drive mechanism, and the control unit compares the pulse signal for driving the stepping motor with the pulse signal output from the encoder to compare the angle of the stepping motor. The amount of deviation is calculated, and the output of the brushless motor is controlled to be increased or decreased according to the amount of angular deviation.

As a result, step-out of the stepping motor can be prevented without providing a separate encoder for the stepping motor. Further, by controlling the brushless motor driven by current control instead of the stepping motor, the operation of the twin drive device can be controlled more accurately and easily.

In order to explain one embodiment of the present invention in more detail, the twin drive device and the motor control method according to one embodiment of the present invention will be described with reference to FIGS. 1 to 10. FIG. 1 is a schematic diagram showing the configuration of the image forming apparatus of this embodiment, and FIG. 2 is a block diagram showing the configuration of the image forming apparatus of this embodiment. Further, FIG. 3 is a schematic diagram showing the configuration of the twin drive device of the present embodiment, and FIG. 4 is a block diagram illustrating the twin drive of the present embodiment. 5 to 8 are views for explaining the angular deviation of the stepping motor in the twin drive device of the present embodiment, and FIGS. 9 and 10 are flowcharts showing the operation of the twin drive device of the present embodiment. is there.

The twin drive device of this embodiment can be used for various devices provided with a drive mechanism, but in this embodiment, an image forming device for driving a transfer roller using the twin drive device will be described.

As shown in FIG. 1, the image forming apparatus 10 of this embodiment is based on the image data acquired by reading the original or the image data input from an external information device (for example, a client device) via a communication network. It is a device that forms an image by superimposing colors on paper, and is, for example, photosensitive as a photoconductor corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K). The body drums 83Y, 83M, 83C, and 83K are tandem image forming devices arranged in series in the traveling direction of the transferred body (intermediate transfer belt).

As shown in FIG. 2A, the image forming apparatus 10 includes a control unit 20, a high-voltage power supply unit 30, a display operation unit 40, an image reading unit 50, an image processing unit 60, a transport unit 70, an image forming unit 80, and the like. Consists of.

The control unit 20 stores a CPU (Central Processing Unit) 21, a memory such as a ROM (Read Only Memory) 22 and a RAM (Random Access Memory) 23, and a storage such as an HDD (Hard Disk Drive) and an SSD (Solid State Drive). It is composed of a unit 24 and a network I / F unit 25 such as a NIC (Network Interface Card) or a modem. The CPU 21 reads a program according to the processing content from the ROM 22 or the storage unit 24, expands the program into the RAM 23, and executes the program to centrally control the operation of each unit of the image forming apparatus 10. The storage unit 24 stores a program for the CPU 21 to control each unit, information on the processing function of the own device, image data read by the image reading unit 50, image data input from a client device (not shown), and the like. The network I / F unit 25 connects the image forming apparatus 10 to a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network), and connects various data to and from an external information device (for example, a client device). Send and receive.

The high-voltage power supply unit 30 is a circuit that generates high voltage used for charging, developing, and transferring, and applies a high voltage of alternating waveform to the charging device 84, the developing device 82, the primary transfer roller 86, and the intermediate transfer unit 87, which will be described later. Output. For example, secondary transfer is executed by converting a DC voltage of 24 V into a transfer voltage and outputting the converted transfer voltage to a secondary transfer roller.

The display operation unit 40 is a pressure-sensitive or capacitive operation unit (touch sensor) in which transparent electrodes are arranged in a grid pattern on a display unit such as an LCD (Liquid Crystal Display) or an organic EL (Electro Luminescence) display. ) Is provided, and functions as a display unit and an operation unit. The display unit displays various operation screens, an image status display, an operation status of each function, and the like according to a display control signal input from the control unit 20. The operation unit receives various input operations by the user and outputs an operation signal to the control unit 20.

The image reading unit 50 includes an automatic document feeding device 51 called an ADF (Auto Document Feeder), a document image scanning device (scanner) 52, and the like. The automatic document feeding device 51 conveys the documents placed on the document tray by the conveying mechanism and sends them out to the document image scanning device 52. The document image scanning device 52 optically scans the document conveyed on the contact glass from the automatic document feeding device 51 or the document placed on the contact glass, and the reflected light from the document is CCD (Charge Coupled Device). ) The original image is read by forming an image on the light receiving surface of the sensor. The image (analog image signal) read by the image reading unit 50 is subjected to predetermined image processing by the image processing unit 60.

The image processing unit 60 includes a circuit that performs analog-to-digital (A / D) conversion processing, a circuit that performs digital image processing, and the like. The image processing unit 60 generates digital image data by performing A / D conversion processing on the analog image signal from the image reading unit 50. Further, the image processing unit 60 analyzes a print job acquired from an external information device (for example, a client device), rasterizes each page of the document, and generates digital image data. Then, the image processing unit 60 performs image processing such as color conversion processing, correction processing (shading correction, etc.), and compression processing on the image data as necessary, and forms the image data after the image processing. Output to unit 80.

As shown in FIGS. 1 and 2B, the transport unit 70 includes a transport roller 71 and a twin drive device for driving the transport roller 71. The twin drive device includes a stepping motor 72 and a brushless motor. It is composed of a 73, a drive mechanism 74, and a control unit such as a CPU 75 that controls the operation of the stepping motor 72 and the brushless motor 73. The transport roller 71 is arranged at a predetermined position on the paper transport path, transports the paper stored in the paper feed tray to the image forming unit 80, and transports the paper after image formation to the paper ejection tray. The stepping motor 72 is a motor that operates in synchronization with the drive pulse signal. The brushless motor 73 is a motor that does not have a brush and a commutator (a DC brushless motor in which the brush function of the DC motor is replaced with an electronic circuit). The brushless motor 73 of this embodiment includes an encoder 73a for detecting a phase and an angle, and feedback control is performed by a pulse signal output from the encoder 73a. The drive mechanism 74 is a gear, a drive shaft, or the like for rotationally driving the transport roller 71, and is rotationally driven by the stepping motor 72 and the brushless motor 73. The drive mechanism 74 may include an encoder 74b for detecting the phase and angle of the drive shaft instead of the encoder 73a of the brushless motor 73. The CPU 75 is a CPU used for twin drive control, and includes a stepping motor control unit 76 that controls the stepping motor 72, a brushless motor control unit 77 that controls the brushless motor 73, and the like. The detailed configuration of the twin drive device will be described later.

As shown in FIGS. 1 and 2 (c), the image forming unit 80 includes an exposure apparatus 81 (81Y, 81M, 81C, 81K), which is provided corresponding to different color components Y, M, C, and K. Developing device 82 (82Y, 82M, 82C, 82K), photoconductor drum 83 (83Y, 83M, 83C, 83K), charging device 84 (84Y, 84M, 84C, 84K), cleaning device 85 (85Y, 85M, 85C, 85K), a primary transfer roller 86 (86Y, 86M, 86C, 86K), an intermediate transfer unit 87, a fixing device 88, and the like. In the following description, symbols excluding Y, M, C, and K are used as necessary.

In the photoconductor drum 83 of each color component Y, M, C, K, an organic photoconductor layer (OPC) provided with an overcoat layer as a protective layer is formed on the outer peripheral surface of a cylindrical metal substrate made of an aluminum material. It is an image carrier. The photoconductor drum 83 is rotated in the counterclockwise direction in FIG. 1 in a state of being grounded by being driven by an intermediate transfer belt described later.

The charging device 84 for each of the color components Y, M, C, and K is, for example, a charging roller type, in a state where the charging member (charging roller) has its longitudinal direction along the rotation axis direction of the photoconductor drum 83. It is arranged close to the corresponding photoconductor drum 83, and a uniform potential is applied to the surface of the photoconductor drum 83 by applying a high voltage to the charging member. At the time of this charging, a high voltage of an alternating waveform is output from the output terminal of the high voltage power supply unit 30 as needed.

The exposure apparatus 81 for each color component Y, M, C, K scans in parallel with the rotation axis of the photoconductor drum 83 by, for example, a polygon mirror, and is uniformly charged on the surface of the corresponding photoconductor drum 83. An electrostatic latent image is formed by performing image exposure based on the image data.

The developing device 82 for each of the color components Y, M, C, and K contains a two-component developer composed of a toner having a small particle size of the corresponding color component and a magnetic material, and the toner is applied to the surface of the photoconductor drum 83. It is conveyed and the electrostatic latent image carried on the photoconductor drum 83 is visualized with toner. At the time of this development, a high voltage of an alternating waveform is output from the output terminal of the high voltage power supply unit 30 as needed.

The primary transfer roller 86 of each color component Y, M, C, K presses the intermediate transfer belt against the photoconductor drum 83, and sequentially superimposes the toner images of each color formed on the corresponding photoconductor drum 83 on the intermediate transfer belt. Transcribe. At the time of this primary transfer, a high voltage of the alternating waveform is output from the output terminal of the high voltage power supply unit 30 as needed.

The cleaning device 85 for each of the color components Y, M, C, and K recovers the residual toner remaining on the corresponding photoconductor drum 83 after the primary transfer. Further, a lubricant application mechanism (not shown) is provided adjacent to the photoconductor drum 83 of the cleaning device 85 in the rotation direction, and the lubricant is applied to the photosensitive surface of the corresponding photoconductor drum 83. There is.

The intermediate transfer unit 87 includes an endless intermediate transfer belt 87a to be transferred, a support roller 87b, a secondary transfer roller 87c, an intermediate transfer cleaning unit 87d, and the like, and the intermediate transfer belt 87a is stretched on the plurality of support rollers 87b. It is constructed by being hung. When the intermediate transfer belt 87a on which the toner images of each color are first transferred by the primary transfer rollers 86Y, 86M, 86C, and 86K is pressed against the paper by the secondary transfer roller 87c, the toner image is secondarily transferred to the paper and the fixing device. Sent to 88. The intermediate transfer cleaning unit 87d has a belt cleaning blade (BCL blade) that is slidably contacted with the surface of the intermediate transfer belt 87a. The transfer residual toner remaining on the surface of the intermediate transfer belt 87a after the secondary transfer is scraped off by the BCL blade and removed. At the time of this secondary transfer, a high voltage of the alternating waveform is output from the output terminal of the high voltage power supply unit 30 as needed.

The fixing device 88 includes a heating roller 88a and a fixing roller 88b as heat sources, a fixing belt 88c and a pressure roller 88d hung on the fixing roller 88b, and the pressure roller 88d is pressed against the fixing roller 88b via the fixing belt 88c. The pressure contact portion constitutes the nip portion. Then, the fixing belt 88c heated by the heating roller 88a and each roller heat and pressurize the paper passing through the nip portion to fix the unfixed toner image formed on the paper.

Next, the twin drive of the transfer roller 71 in the twin drive device will be described. FIG. 3 is a schematic view showing the configuration of the twin drive device. The stepping motor 72 (abbreviated as STPM) controlled by the stepping motor control unit 76 and the brushless motor 73 (abbreviated as DCBLM) controlled by the brushless motor control unit 77 have the same drive shaft via a gear or the like. A transport roller (not shown) connected to the drive shaft 74a is rotated by rotating the drive shaft 74a connected to the 74a (rotation shaft). Note that FIG. 3 is an example of a twin drive device, and as long as the same drive shaft 74a can be rotationally moved by using the stepping motor 72 and the brushless motor 73, the arrangement of each component, the configuration and shape of the gears are , Gear ratio, etc. can be changed as appropriate.

FIG. 4 is a block diagram illustrating the twin drive of this embodiment. The stepping motor control unit 76 of the CPU 75 drives the stepping motor 72 by open loop control. Specifically, the stepping motor control unit 76 controls the rotation speed and torque of the stepping motor 72 by transmitting pulse signals such as a clock signal (CLK) and an enable signal (ENABLE) to the stepping motor 72.

Further, the brushless motor control unit 77 of the CPU 75 drives the brushless motor 73 by PWM control (particularly, PWM current control that is not easily affected by fluctuations in the resistance component of the motor due to changes in load torque). Specifically, the brushless motor control unit 77 controls the rotation speed and torque of the brushless motor 73 by transmitting a PWM signal to the brushless motor 73. Further, the brushless motor control unit 77 executes feedback control based on the current (shunt current) detected by the current detection unit (not shown) and the pulse signal output from the encoder 73a.

Then, the CPU 75 receives a pulse signal for driving the stepping motor 72 acquired from the stepping motor control unit 76 (hereinafter, abbreviated as a pulse of the stepping motor 72) and a pulse output from the encoder 73a acquired from the brushless motor control unit 77. By comparing the signal (hereinafter, abbreviated as the pulse of the encoder 73a), the angle deviation amount of the stepping motor 72 (the angle estimated from the pulse signal driving the stepping motor 72 and the pulse signal output from the encoder 73a) The amount of deviation from the angle specified based on this) is calculated. Hereinafter, a specific example will be described.

FIG. 5 shows an example in which the pulse frequency of the stepping motor 72 is an integral multiple (here, twice) of the pulse frequency of the encoder 73a. In this case, the amount of angular deviation of the stepping motor 72 is calculated by comparing the rising edge and the falling edge of the pulse of the encoder 73a with the pulse of the stepping motor 72.

For example, as a stepping motor 72, one rotation is performed with 200 pulses (when the rotation angle per step is 1.8 °, the rotation angle per pulse is 1.8 in the full step mode, and the number of pulses per rotation is 1.8. Is 360 ° / 1.8 ° = 200.) When the encoder 73a is selected to output 100 pulses in one rotation, the pulse frequency of the stepping motor 72 is that of the pulse of the encoder 73a. Since the frequency is doubled, the rising edge or falling edge of each pulse of the stepping motor 72 is compared with the rising edge or falling edge of each pulse of the encoder 73a, and the stepping motor 72 is compared. Calculate the amount of angular deviation.

FIG. 6 is an example in which the pulse frequency of the stepping motor 72 is not an integral multiple of the pulse frequency of the encoder 73a. In this case, the greatest common divisor of the two pulses is obtained, and the rising edge or falling edge of the pulse is compared for each multiple of the greatest common divisor of each pulse to calculate the amount of angular deviation of the stepping motor 72.

For example, the stepping motor 72 makes one rotation with 200 pulses in the same manner as above (when the rotation angle per step is 1.8 °, the rotation angle per pulse is 1.8 in the full step mode, which is 1). The number of pulses per rotation is 360 ° / 1.8 ° = 200.) When the encoder 73a is selected to output 80 pulses in one rotation, the frequency of the pulse of the stepping motor 72 is Since it is not an integral multiple (2.5 times) the frequency of the pulse of the encoder 73a, the maximum pledge (40) of 200 and 80 is obtained. Since 200 is 5 times 40 and 80 is 2 times 40, the rising edge or falling edge of each pulse of the stepping motor 72 and the rising edge of each pulse of the encoder 73a are rising. The amount of angular deviation of the stepping motor 72 is calculated by comparing the edge or the falling edge.

FIG. 7 shows the relative phases of the pulse of the stepping motor 72 and the pulse of the encoder 73a when the stepping motor 72 and the brushless motor 73 are driven and the assist torque of the brushless motor 73 is changed. The stepping motor 72 is shown. When the phase of the pulse of the encoder 73a and the phase of the pulse of the encoder 73a change by a predetermined angle or more (when the angle deviation amount becomes a predetermined value or more), the angle deviation amount is calculated with reference to the phase immediately before the change. To do.

For example, at the time of starting, the backlash of the gear of the drive shaft 74a is packed and the load becomes large, so that the assist torque of the brushless motor 73 is increased to rotate the drive shaft 74a. At that time, the pulse of the encoder 73a is detected with the phase difference between the pulse of the encoder 73a and the pulse of the stepping motor 72 as a reference of 0 ° when the torque of the brushless motor 73 becomes equal to the load torque, and the stepping motor 72 The amount of angular deviation of the stepping motor 72 is calculated by comparing with the pulse.

When assembling the twin drive mechanism, a jig is used to excite the stepping motor 72 to reduce the backlash of the gear of the drive shaft 74a, and the phase difference between the pulse of the encoder 73a and the pulse of the stepping motor 72. Is preferably adjusted to a predetermined specific angle.

FIG. 8 shows the relationship between the speeds of the stepping motor 72 and the brushless motor 73 and the amount of angular deviation of the stepping motor 72. When the amount of angular deviation of the stepping motor 72 exceeds a predetermined constant value, the output of the brushless motor 73 is changed. For example, as shown in the upper side of FIG. 8, when the pulse of the encoder 73a is delayed (the speed of the brushless motor 73 is smaller than the speed of the stepping motor 72), the output of the brushless motor 73 is increased and the lower side of FIG. As shown in the above, when the pulse of the encoder 73a advances (the speed of the brushless motor 73 is larger than the speed of the stepping motor 72), the output of the brushless motor 73 is reduced, depending on the amount of angular deviation of the stepping motor 72. , The output of the brushless motor 73 is changed.

Specifically, when a load is suddenly applied, the phase of the pulse of the encoder 73a is delayed from the phase of the stepping motor 72 (plus phase). On the other hand, when the actual load is reduced, the phase of the pulse of the encoder 73a advances from the phase of the pulse of the stepping motor 72 (minus phase). Depending on the amount of deviation (±) of this angle, the PWM Duty of the current that drives the brushless motor 73 is changed, for example, as shown in Table 1 below.

Further, when the amount of angular deviation of the stepping motor 72 exceeds a predetermined limited value, the current for driving the brushless motor 73 is not increased (the output is not changed). For example, if the angle deviation amount of the stepping motor 72 exceeds 90 ° in the full step mode, step-out occurs. Therefore, when the angle deviation amount becomes ± 45 °, the current of the brushless motor 73 is not increased.

Hereinafter, the operation of the twin drive device of this embodiment will be described with reference to the flowcharts of FIGS. 9 and 10.

As shown in FIG. 9, when the power of the image forming apparatus 10 is turned on (S101) and the axis rotation command is issued from the control unit 20 (Yes in S102), the CPU 75 (stepping motor control unit 76) sends a clock signal. And the enable signal is transmitted to start the stepping motor 72, and the CPU 75 (brushless motor control unit 77) transmits a PWM signal to start the brushless motor 73 (S103).

Next, as shown in FIG. 7, the CPU 75 increases the assist torque of the brushless motor 73 to perform phase matching (S104). Then, when the CPU 75 detects the pulse of the encoder 73a (S105), the pulse of the stepping motor 72 is compared with the pulse of the encoder 73a to calculate the amount of angular deviation of the stepping motor 72 (S106).

Next, the CPU 75 determines whether the angle deviation amount of the stepping motor 72 exceeds a predetermined constant value (S107), and if the angle deviation amount of the stepping motor 72 does not exceed the constant value (No in S107). , S113, and when the angle deviation amount of the stepping motor 72 exceeds a certain value (Yes in S107), it is determined whether the angle deviation amount of the stepping motor 72 exceeds a predetermined limit value (S108).

When the amount of angular deviation of the stepping motor 72 exceeds the limit value (Yes in S108), the CPU 75 determines that the stepping motor 72 has stepped out (S109), and the CPU 75 (brushless motor control unit 77) determines that the stepping motor 72 has stepped out. 73 is stopped (S110). On the other hand, when the amount of angular deviation of the stepping motor 72 does not exceed the limit value (No in S108), the CPU 75 (brushless motor control unit 77) controls the brushless motor 73 as shown in FIGS. 8 and 1. (S111).

FIG. 10 shows the details of this step, and the CPU 75 (brushless motor control unit 77) calculates the current increase amount of the brushless motor 73 from the angle deviation amount of the stepping motor 72 with reference to Table 1 and the like (see Table 1 and the like). S201), the target current of the brushless motor 73 is corrected (S202). Specifically, it is corrected to the post-FB current value due to the shunt current + the STPM angle deviation amount correction value. Then, the CPU 75 (brushless motor control unit 77) corrects the PWM Duty of the current of the brushless motor 73 to increase the assist torque (S203).

Returning to FIG. 9, by controlling the brushless motor 73 of S111, the output of the brushless motor 73 changes, the stepping motor 72 can be rotated normally, and the drive shaft 74a can be rotated normally (S112). .. After that, or when the amount of angular deviation of the stepping motor 72 does not exceed a certain value (No in S107), it is determined whether the shaft stop command has been issued from the control unit 20 (S113), and the shaft stop command is issued. If not (No in S113), the process returns to S105 and the same process is repeated. When a shaft stop command is issued (Yes in S113), the CPU 75 (stepping motor control unit 76) stops the stepping motor 72 and the CPU 75 (No). The brushless motor control unit 77) stops the brushless motor 73 (S114).

As described above, in the mechanism for rotating the same load by using the stepping motor 72 and the brushless motor 73, the pulse signal of the stepping motor 72 and the encoder 73a (or the drive mechanism 74) provided in the brushless motor 73 The amount of angular deviation of the stepping motor 72 is calculated by comparing with the pulse signal of the provided encoder 74b), and the output of the brushless motor 73 is increased or decreased according to the amount of angular deviation of the stepping motor 72 (for example, suddenly). When the amount of angular deviation of the stepping motor 72 becomes large due to torque fluctuation, the output of the brushless motor 73 is increased to increase the amount of assist), so that the stepping motor 72 can be prevented from stepping out.

The present invention is not limited to the above embodiment, and its configuration and control can be appropriately changed as long as the gist of the present invention is not deviated.

For example, in the above embodiment, the case where the motor control method of the present invention is applied to the image forming apparatus 10 has been described, but the motor control method of the present invention is similarly applied to any device provided with a drive mechanism. Can be applied.

The present invention can be used for a twin drive device that rotationally moves the same load using a stepping motor and a brushless motor, and a motor control method for the twin drive device.

10 Image forming device 20 Control unit 21 CPU
22 ROM
23 RAM
24 Storage unit 25 Network I / F unit 30 High-voltage power supply unit 40 Display operation unit 50 Image reading unit 51 Automatic document feeding device 52 Original image scanning device 60 Image processing unit 70 Transport unit 71 Transport roller 72 Stepping motor 73 Brushless motor 73a Encoder 74 Drive mechanism 74a Drive shaft 74b Encoder 75 CPU
76 Stepping motor control unit 77 Brushless motor control unit 80 Image forming unit 81, 81Y, 81M, 81C, 81K Exposure device 82, 82Y, 82M, 82C, 82K Developer 83, 83Y, 83M, 83C, 83K Photoreceptor drum 84, 84Y, 84M, 84C, 84K Charging device 85, 85Y, 85M, 85C, 85K Cleaning device 86, 86Y, 86M, 86C, 86K Primary transfer roller 87 Intermediate transfer unit 87a Intermediate transfer belt 87b Support roller 87c Secondary transfer roller 87d Intermediate Transfer cleaning unit 88 Fixing device 88a Heating roller 88b Fixing roller 88c Fixing belt 88d Pressurizing roller

Claims (17)

It is provided with a stepping motor, a brushless motor, a drive mechanism for rotating the same load using the stepping motor and the brushless motor, and a control unit for controlling the operation of the stepping motor and the brushless motor.
An encoder is provided on the rotation shaft of the brushless motor or the rotation shaft of the drive mechanism.
The control unit compares the pulse signal for driving the stepping motor with the pulse signal output from the encoder to calculate the amount of angular deviation of the stepping motor, and outputs the brushless motor according to the amount of angular deviation. Increase or decrease,
A twin drive device that features that. When the frequency of the pulse signal for driving the stepping motor is an integral multiple of the frequency of the pulse signal output from the encoder, the control unit has the rising edge and falling edge of the pulse signal output from the encoder. The amount of angular deviation of the stepping motor is calculated by comparing the pulse signal for driving the stepping motor with the pulse signal output from the encoder.
The twin drive device according to claim 1. When the first frequency of the pulse signal for driving the stepping motor is not an integral multiple of the second frequency of the pulse signal output from the encoder, the control unit has the first frequency and the second frequency. The rising edge or falling edge of the pulse signal for which the greatest common divisor is calculated and driving the stepping motor, the first frequency divided by the greatest common divisor, and the pulse signal output from the encoder , The amount of angular deviation of the stepping motor is calculated by comparing the rising edge or falling edge for each number obtained by dividing the second frequency by the greatest common divisor.
The twin drive device according to claim 1. When the control unit drives the stepping motor and the brushless motor and changes the assist torque of the brushless motor, the phase of the pulse signal for driving the stepping motor and the phase of the pulse signal output from the encoder When and is changed to a predetermined angle or more, the amount of angular deviation of the stepping motor is calculated with reference to the phase immediately before the change.
The twin drive device according to any one of claims 1 to 3, wherein the twin drive device is characterized. The stepping motor and the brushless motor are assembled by adjusting the phase difference between the pulse signal for driving the stepping motor and the pulse signal output from the encoder to a predetermined specific angle.
The twin drive device according to claim 4, wherein the twin drive device is characterized. The control unit changes the output of the brushless motor when the amount of angular deviation of the stepping motor exceeds a predetermined constant value.
The twin drive device according to any one of claims 1 to 5, wherein the twin drive device is characterized. When the pulse signal output from the encoder is delayed from the pulse signal for driving the stepping motor, the control unit increases the output of the brushless motor, and the pulse signal output from the encoder drives the stepping motor. When the pulse signal is exceeded, the output of the brushless motor is reduced.
The twin drive device according to claim 6, wherein the twin drive device is characterized. The control unit does not change the output of the brushless motor when the amount of angular deviation of the stepping motor exceeds a predetermined limit value.
The twin drive device according to any one of claims 1 to 7, wherein the twin drive device is characterized. The transport roller is driven by using the twin drive device according to any one of claims 1 to 8.
An image forming apparatus characterized in that. A stepping motor, a brushless motor, and a drive mechanism for rotating the same load by using the stepping motor and the brushless motor are provided, and an encoder is provided on the rotation shaft of the brushless motor or the rotation shaft of the drive mechanism. This is a motor control method for twin drive devices.
A calculation step of comparing the pulse signal for driving the stepping motor with the pulse signal output from the encoder to calculate the amount of angular deviation of the stepping motor, and
A control step of increasing or decreasing the output of the brushless motor according to the amount of angular deviation is executed.
A motor control method characterized by that. In the calculation step, when the frequency of the pulse signal for driving the stepping motor is an integral multiple of the frequency of the pulse signal output from the encoder, the rising edge and falling edge of the pulse signal output from the encoder are described. The amount of angular deviation of the stepping motor is calculated by comparing the pulse signal for driving the stepping motor with the pulse signal output from the encoder.
The motor control method according to claim 10. In the calculation step, when the first frequency of the pulse signal for driving the stepping motor is not an integral multiple of the second frequency of the pulse signal output from the encoder, the first frequency and the second frequency are used. The rising edge or falling edge of the pulse signal for which the greatest common divisor is calculated and driving the stepping motor, the first frequency divided by the greatest common divisor, and the pulse signal output from the encoder , The amount of angular deviation of the stepping motor is calculated by comparing the rising edge or falling edge for each number obtained by dividing the second frequency by the greatest common divisor.
The motor control method according to claim 10. In the calculation step, when the stepping motor and the brushless motor are driven and the assist torque of the brushless motor is changed, the phase of the pulse signal for driving the stepping motor and the phase of the pulse signal output from the encoder are used. When and is changed to a predetermined angle or more, the amount of angular deviation of the stepping motor is calculated with reference to the phase immediately before the change.
The motor control method according to any one of claims 10 to 12, wherein the motor control method is characterized. The stepping motor and the brushless motor are assembled by adjusting the phase difference between the pulse signal for driving the stepping motor and the pulse signal output from the encoder to a predetermined specific angle.
13. The motor control method according to claim 13. In the control step, when the amount of angular deviation of the stepping motor exceeds a predetermined constant value, the output of the brushless motor is changed.
The motor control method according to any one of claims 10 to 14, wherein the motor control method is characterized. In the control step, when the pulse signal output from the encoder is delayed from the pulse signal for driving the stepping motor, the output of the brushless motor is increased, and the pulse signal output from the encoder drives the stepping motor. When the pulse signal is exceeded, the output of the brushless motor is reduced.
The motor control method according to claim 15, characterized in that. In the control step, when the amount of angular deviation of the stepping motor exceeds a predetermined limit value, the output of the brushless motor is not changed.
The motor control method according to any one of claims 10 to 16, wherein the motor control method is characterized.

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