Motor control device and image forming apparatus

Abstract

The present invention provides a motor control device that can achieve the same motor drive performance as a configuration with a position detection sensor, even without the position detection sensor provided for the motor, thereby reducing costs, and an image forming apparatus equipped with the motor control device. [Solution] A motor control device having a motor, a drive target driven by the motor, a position information detection unit for detecting the operating position information of the drive target, and a drive control means for generating electrical angle information of the motor and controlling the drive of the motor based on the position information detected by the position information detection unit when the motor is moved to a specific electrical angle position and the information of the specific electrical angle position, and an image forming apparatus equipped with the motor control device.

Description

Technical Field

[0001] The present invention relates to a motor control device in an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having a plurality of these functions, and an image forming apparatus equipped with the motor control device.

Background Art

[0002] In recent years, image forming apparatuses have been required to improve print speed and extend the life of service parts. Along with this, higher output of motors used in image forming apparatuses has been demanded.

[0003] In order to cope with the higher output of this motor, Patent Document 1 proposes a method of driving a load to be driven using a plurality of small motors. By using a plurality of inexpensive small motors in this way, it becomes possible to obtain high output with an inexpensive configuration without using a large and expensive high-output motor.

[0004] FIG. 9 is an explanatory diagram showing a conventional configuration for precisely controlling one rotating body with a plurality of motors as proposed in Patent Document 1.

[0005] In FIG. 9, a first motor 4021, a second motor 4031, and a speed reducer 4041 are connected, and the speed reducer 4041 is connected to a rotating body 4091 which is a load. With this configuration, the rotating body 4091 can be rotated by the two motors 4021 and 4031. <UNK>

[0006] In this configuration, a first rotation position sensor 4051 and a second rotation position sensor 4052, which are sensors for detecting the respective rotation positions, are provided for the first motor 4021 and the second motor 4031. Based on the rotation position information of the motors from these first rotation position sensor 4051 and second rotation position sensor 4052, by applying voltages from a first drive voltage generation circuit 4061 and a second drive voltage generation circuit 4062 to the rotation positions where the motors can rotate efficiently, the responsiveness of the motors is increased and high-precision driving becomes possible.

[0007] Furthermore, the rotating body 4091 is equipped with a third rotational position sensor 4053 to detect speed or position. By controlling the drive voltage from the first drive voltage generation circuit 4061 and the second drive voltage generation circuit 4062 according to the speed or position information from the third rotational position sensor 4053, it is possible to drive the rotating body 4091 with high precision.

[0008] In this conventional configuration, in order to control a single rotating body 4091 with high precision using multiple motors 4021 and 4031, a rotational position detection sensor was provided on each motor, and furthermore, a rotational position detection sensor was provided on the rotating body 4091, which is the load. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2021-22979 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, equipping each motor with a position sensor, and the rotating load with a position sensor as well, led to an increase in the overall cost of the device.

[0011] The present invention has been made in view of the above circumstances, and aims to provide a motor control device and an image forming apparatus equipped with the motor control device that can achieve motor drive performance equivalent to that of a configuration in which a position detection sensor is provided, even without the position detection sensor provided for the motor, thereby reducing costs. [Means for solving the problem]

[0012] To achieve the above objective, the present invention provides a motor control device having a motor, a drive target driven by the motor, a position information detection unit for detecting the operating position information of the drive target, and a drive control means for generating electrical angle information of the motor based on the position information detected by the position information detection unit when the motor is moved to a specific electrical angle position and the information of the specific electrical angle position, and for controlling the driving of the motor, and an image forming apparatus equipped with the motor control device. [Effects of the Invention]

[0013] According to the present invention, even without a position detection sensor provided for the motor, motor drive performance equivalent to that of a configuration in which a position detection sensor is provided can be obtained, thereby reducing costs. This provides a motor control device and an image forming apparatus equipped with the motor control device. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic front cross-sectional view of an image forming apparatus according to an embodiment of the present invention. [Figure 2] This is a circuit block diagram showing the control circuit configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 3] This is a block diagram of a motor control device and a control target of the motor control device according to an embodiment of the present invention. [Figure 4] This is a detailed block diagram of the first drive voltage generation circuit according to an embodiment of the present invention. [Figure 5] This is a detailed block diagram of a drive voltage command generation circuit according to an embodiment of the present invention. [Figure 6] This is a detailed block diagram of an electrical angle calculation circuit according to an embodiment of the present invention. [Figure 7] This is a flowchart showing the control of a motor control device in a CPU according to an embodiment of the present invention. [Figure 8] This is an explanatory diagram of a method for obtaining correction values ​​for the electrical angles of two motors according to an embodiment of the present invention. [Figure 9]It is an explanatory diagram of a conventional configuration for controlling one rotating body with a plurality of motors.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Note that the components described in the following embodiments are merely examples, and various conditions such as the configuration, function, dimensions, material, shape, relative arrangement, etc. of the apparatus to which the present invention is applied can be appropriately modified or changed without departing from the spirit of the present invention, and are not limited to the following embodiments.

[0016] FIG. 1 is a schematic front cross-sectional view of an image forming apparatus according to an embodiment of the present invention.

[0017] In FIG. 1, the image forming apparatus 100 includes a paper feeding device 140, a printer 150, and a finisher 160.

[0018] The paper feeding device 140 is a device that feeds the recording paper as the loaded recording material to the printer 150. The recording paper is loaded on the paper feeding stages 140a, 140b, 140c, 140d, 140e. The loaded recording paper is fed and conveyed by a motor described later rotating various rollers, and is sent to the printer 150. Note that the paper feeding stages 140a and 140b are built in the printer 150.

[0019] The printer 150 as an image forming means includes four image forming units PY, PM, PC, and PK. The four image forming units PY, PM, PC, and PK are composed of an image forming unit PY that forms a yellow (Y) image, an image forming unit PM that forms a magenta (M) image, an image forming unit PC that forms a cyan (C) image, and an image forming unit PK that forms a black (K) image. Since the configurations of the image forming units PY, PM, PC, and PK are substantially the same except for the different developing colors, the details of the yellow image forming unit PY will be described below, and for the descriptions of the other image forming units PM, PC, and PK, the same numbers as the corresponding configurations and the symbols M, C, and K will be attached, and the descriptions will be omitted.

[0020] The image forming unit PY includes a photosensitive drum 153Y, a charger 220Y, an exposure device 223Y, a developing unit 152Y, and a cleaner 222Y. The photosensitive drum 153 rotates in the direction of arrow R1Y by a motor described later. The charger 220Y charges the surface of the photosensitive drum 153Y. The exposure device 223Y exposes the photosensitive drum 153Y. As a result, an electrostatic latent image is formed on the photosensitive drum 153Y. The developing unit 152Y develops the electrostatic latent image using a developer (toner). As a result, the electrostatic latent image on the photosensitive drum 153Y is visualized, and a toner image is formed on the photosensitive drum 153Y. Then, the toner image formed on the photosensitive drum 153Y is transferred to the intermediate transfer belt 154. Note that the toner remaining on the photosensitive drum 153Y after being transferred to the intermediate transfer belt 154 is removed by the cleaner 222Y.

[0021] Images of yellow, magenta, cyan, and black formed by the image forming units PY, PM, PC, and PK are transferred to the intermediate transfer belt 154 so as to overlap. As a result, a full-color image is formed on the intermediate transfer belt 154. The image on the intermediate transfer belt 154 is conveyed in the direction of arrow R2. Then, the image formed on the intermediate transfer belt 154 is transferred to a recording paper conveyed from the paper feeding device 140 at the nip portion between the intermediate transfer belt 154 and the transfer roller 221. The intermediate transfer belt 154 is conveyed in the direction of arrow R2 by a motor described later rotating a driving roller.

[0022] The printer 150 has a first fuser 155 and a second fuser 156 that heat and pressurize the image transferred to the recording paper to fix the image to the recording paper. The first fuser 155 includes a fuser roller with an internal heater and a pressure belt for pressing the recording paper against the fuser roller. This fuser roller is driven by a motor, which will be described later, to transport the recording paper. The second fuser 156 is located downstream of the first fuser in the direction of transport of the recording paper. The second fuser 156 increases the gloss of the image on the recording paper that has passed through the first fuser 155, ensuring fixation. The second fuser 156 includes a fuser roller with an internal heater and a pressure roller with an internal heater. Depending on the type of recording paper, it may not be necessary to use the second fuser 156. In this case, the recording paper is transported to the transport path 130 without passing through the second fuser 156. The flapper 131 switches between guiding the recording paper to the transport path 130 or to the second fuser 156.

[0023] The flapper 132 switches between guiding the recording paper to the transport path 135 or to the discharge path 139. In duplex printing mode, the flapper 132 guides the recording paper with an image formed on the first side to the transport path 135. In face-up discharge mode, the flapper 132 guides the recording paper with an image formed on the first side to the discharge path 139. In face-down discharge mode, the flapper 132 guides the recording paper with an image formed on the first side to the transport path 135. After the adjustment chart is printed on the first side of the recording paper, the flapper 132 guides the recording paper to the transport path 135 in order to print the adjustment chart on the second side of the recording paper.

[0024] The recording paper transported to the transport path 135 is transported to the reversal unit 136. After the transport operation of the recording paper transported to the reversal unit 136 stops, it switches back to reverse the transport direction of the recording paper. Next, the flapper 133 switches whether to guide the recording paper to the transport path 138 or to the transport path 135. In the duplex printing mode, the flapper 133 guides the switched-back recording paper to the transport path 138. Also, in the face-down output mode, the flapper 133 guides the switched-back recording paper to the transport path 135. Furthermore, the recording paper transported to the transport path 135 by the flapper 133 is guided to the output path 139 by the flapper 134. Also, the flapper 133 guides the switched-back recording paper to the transport path 138 in order to print an adjustment chart on the second side of the recording paper.

[0025] The recording paper, transported to the transport path 138 by the flapper 133, is then transported towards the nip section between the intermediate transfer belt 154 and the transfer roller 221. This reverses the front and back sides of the recording paper as it passes through the nip section.

[0026] The transport of recording paper within the printer 150 is performed by a motor, described later, which rotates a drive roller.

[0027] The finisher 160 is a post-processing device that performs post-processing on the recording paper from the printer 150. For example, the finisher 160 can perform stapling or sorting on multiple sheets of recording paper.

[0028] Figure 2 is a circuit block diagram showing the control circuit configuration of the image forming apparatus 100.

[0029] In Figure 2, the system controller 301 includes a CPU 301a, a ROM 301b, and a RAM 301c. The system controller 301 is also connected to an image processing unit 112, an operation unit 302, an analog-to-digital (A / D) converter 303, a high-voltage control unit 305, a motor control device 401, sensors 307, and an AC driver 308. The system controller 301 is capable of sending and receiving data and commands to and from each of the connected units.

[0030] The CPU 301a executes various sequences related to a predetermined image formation sequence by reading and executing various programs stored in the ROM 301b. The RAM 301c is a storage device. The RAM 301c stores various data, such as setting values ​​for the high-voltage control unit 305, command values ​​for the motor control device 401, and information received from the operation unit 302.

[0031] The system controller 301 transmits setting data for various devices located inside the printer 150, which are necessary for image processing in the image processing unit 112, to the image processing unit 112. The system controller 301 further receives signals from the sensors 307 and sets the setting value of the high-voltage control unit 305 based on the received signals. The high-voltage control unit 305 supplies the necessary voltage to the high-voltage unit 306 (charger 220, developer 152, etc.) according to the setting value set by the system controller 301. The sensors 307 include sensors that detect the recording paper being transported by the transport rollers.

[0032] The motor control device 401 controls the first motor 402, which acts as the first motor for driving the load, and the second motor 403, which acts as the second motor, in response to commands output from the CPU 301a. Although only one motor control device 401 is shown in Figure 2, in reality, multiple motor control devices are provided in the image forming apparatus 100.

[0033] The A / D converter 303 receives a detection signal from the thermistor 304, which detects the temperature of the fuser heater 309, converts the detection signal from an analog signal to a digital signal, and transmits it to the system controller 301. The system controller 301 controls the AC driver 308 based on the digital signal received from the A / D converter 303. The AC driver 308 controls the fuser heater 309 so that its temperature reaches the temperature required for the fuser process. The fuser heater 309 is a heater used for the fuser process and is provided in the first fuser unit 155 and the second fuser unit 156.

[0034] The system controller 301 controls the operation unit 302 to display an operation screen on the display unit provided on the operation unit 302, which allows the user to set the type of recording paper to be used (hereinafter referred to as "paper type"). The system controller 301 receives the information set by the user from the operation unit 302 and controls the operation sequence of the image forming apparatus 100 based on the information set by the user. The system controller 301 also transmits information indicating the status of the image forming apparatus 100 to the operation unit 302. This information includes, for example, the number of images to be formed, the progress of the image forming operation, and information regarding paper jams or double feeds. The operation unit 302 displays the information received from the system controller 301 on its display unit.

[0035] As described above, the system controller 301 controls the operation sequence of the image forming apparatus 100.

[0036] Next, the motor control device 401 will be explained using Figure 3. Figure 3 is a block diagram of the motor control device 401 and the devices controlled by the motor control device 401.

[0037] In Figure 3, the CPU 301a controls the motor control device 401 by outputting control signals related to motor control to the motor control device 401. In these control signals, 0 indicates no control, 1 indicates position control of the first motor 402, 2 indicates position control of the second motor 403, and 3 indicates rotation control of both the first motor 402 and the second motor 403.

[0038] The above control signal outputs 0 when the first motor 402 and the second motor 403 are not rotating. When the CPU 301a receives a command to start controlling the first motor 402 and the second motor 403, the above control signal transitions in the order of 1 → 2 → 3. During the periods of control signals 1 and 2, correction values ​​necessary for controlling the first motor 402 and the second motor 403 are acquired. Without these correction values, the motor control performance will be reduced or control will not be possible.

[0039] The motor control device 401 generates drive voltages to be applied to the first motor 402 and the second motor 403 based on control signals from the CPU 301a and pulse signals from the rotation position sensor 405, which are rotation position information indicating the rotation position of the rotating body 409, and controls these two motors. The motor control device 401 consists of a first drive voltage generation circuit 4011 that generates the drive voltage to be applied to the first motor 402 and a second drive voltage generation circuit 4012 that generates the drive voltage to be applied to the second motor 403, and the first drive voltage generation circuit 4011 and the second drive voltage generation circuit 4012 have the same function.

[0040] The first motor 402 and the second motor 403 are three-phase DC brushless motors. In this embodiment, the first motor 402 and the second motor 403 are described as three-phase DC brushless motors, but the present invention is not limited to DC brushless motors. Furthermore, the present invention is not limited to the use of the same type of motor.

[0041] The reduction gear 404, acting as a drive force transmission unit, combines the torque (driving force) generated by the first motor 402 and the second motor 403 and transmits it to the rotating body 409, which is the load to be driven. In this embodiment, the explanation is given using an example where the reduction ratios of the two motors and the reduction gear are the same, but the reduction ratios may be different.

[0042] The rotating body 409 rotates due to the torque transmitted by the reduction gear 404. This rotating body includes the photosensitive drum 153, the fixing roller, the drive roller for the intermediate transfer belt, and the transport drive roller for the recording paper in the image forming apparatus 100.

[0043] The rotational position sensor 405, acting as a position information detection unit, detects the rotational position, which is the operating position information of the rotating body 409. A rotary encoder is used to detect the rotational position. The rotary encoder comprises a light-emitting unit that emits light, a light-receiving unit that receives the light emitted from the light-emitting unit, and a disc with slits provided at predetermined rotational positions through which the light emitted from the light-emitting unit passes. Each time the light-receiving unit receives light, it outputs a pulse signal as the detection result.

[0044] The above describes the motor control device 401 shown in Figure 3, the rotating body 409 to be controlled, the first motor 402 and second motor 403 that provide driving force to the rotating body 409, the reduction gear 404, and the rotational position sensor 405 that detects the rotational position of the rotating body 409. As shown in Figure 3, in this embodiment, the first motor 402 and the second motor 403 do not have the first rotational position sensor 4051 and second rotational position sensor 4052 as shown in the conventional example in Figure 9.

[0045] Next, we will describe the first drive voltage generation circuit 4011 and the second drive voltage generation circuit 4012, which generate the voltages applied to the first motor 402 and the second motor 403 in the motor control device 401, respectively. Since the second drive voltage generation circuit 4012 has the same configuration as the first drive voltage generation circuit 4011, we will only explain the differences between them. Figure 4 is a detailed block diagram of the first drive voltage generation circuit 4011.

[0046] In Figure 4, the first drive voltage generation circuit 4011 consists of a voltage command generation circuit 40111, a PWM generation circuit 40112, a driver 40113, and a current detection circuit 40114.

[0047] The voltage command generation circuit 40111, which serves as a drive control means, outputs a command value for the voltage to be applied to the first motor 402. Details of the voltage command generation circuit 40111 will be explained later.

[0048] The PWM generation circuit 40112 and driver 40113 generate the drive voltage based on the voltage command value from the voltage command generation circuit 40111.

[0049] The PWM generation circuit 40112 outputs a PWM signal based on the control signal from the CPU 301a and the voltage command output by the switch 40118. It turns off if the control signal from the CPU 301a is 0, and on if it is any other value.

[0050] The driver 40113 outputs a PWM voltage to be applied to the first motor 402 based on the PWM signal from the PWM generation circuit 40112.

[0051] The current detection circuit 40114 detects the three-phase current flowing through the first motor 402. The detected current value is used by the voltage command generation circuit 40111. The current detection circuit 40114 generally detects the current value by providing a current detection resistor and detecting the voltage across the current detection resistor with the AD converter 303.

[0052] The above is an overview of the configuration of the first drive voltage generation circuit 4011.

[0053] Next, we will explain in detail the voltage command generation circuit 40111, which generates the command value for the voltage applied to the first motor 402.

[0054] The voltage command generation circuit 40111 has the function of outputting two types of voltage commands. The two types of voltage commands are generated by the voltage commands of the drive voltage command generation circuit 40115 and the positioning voltage command generation circuit 40119.

[0055] The drive voltage command generation circuit 40115, acting as a drive voltage generation unit, generates a voltage command value for the drive voltage applied to the first motor 402, and has a configuration that combines speed control and vector control. Speed ​​control is used to determine the required torque of the first motor 402 based on the speed information of the rotating body 409, and vector control is used to achieve highly torque-controllable control that can instantaneously generate the required torque.

[0056] The positioning voltage command generation circuit 40119 generates voltage commands for positioning control of the first motor 402.

[0057] The drive voltage command generation circuit 40115 will be explained using Figure 5. Figure 5 is a detailed block diagram of the drive voltage command generation circuit 40115.

[0058] The drive voltage command generation circuit 40115 starts operation based on the control signal from the CPU 301a. It operates if the control signal from the CPU 301a is 3, and does not operate otherwise.

[0059] When the control signal from the CPU 301a becomes 3 and the target speed generation circuit 40115a starts operating, it determines and outputs a target speed signal based on the pre-set initial speed, target speed, and acceleration. When the control signal from the CPU 301a switches back to 0 and the motor control device 401 stops operating, the target speed generation circuit 40115a decelerates the target speed signal based on the pre-set deceleration, and finally sets it to 0.

[0060] The speed detection circuit 40115f detects the speed of the rotating body 409 from the pulse signal of the rotational position sensor 405. It measures the period of the pulse signal and calculates the speed from that period.

[0061] The speed control circuit 40115b outputs a d-axis current command and a q-axis current command. The d-axis current command is output as a fixed value of 0. The value of the q-axis current command is determined so that the target speed signal and the detected speed of the rotating body 409 match. Specifically, the deviation, which is the difference between the target speed and the detected speed, is calculated, and the q-axis current command is determined by PI control of this deviation.

[0062] The dq conversion circuit 40115c calculates and outputs the d-axis detected current and q-axis detected current from the detected current and electrical angle from the current detection circuit 40114. The calculation formula is given by the following equation [Equation 1].

number

[0063] The dq inverse transform circuit 40115e calculates and outputs the U-phase voltage command, V-phase voltage command, and W-phase voltage command from the d-axis voltage command, q-axis voltage command, and electrical angle. The calculation formula is given by the following equation [Equation 2].

number

[0064] If the control signal from CPU301a is anything other than 3, the U-phase voltage command, V-phase voltage command, and W-phase voltage command will all output 0.

[0065] In this embodiment, the drive voltage command generation circuit 40115 employs a configuration of speed control and vector control, but the drive voltage command generation 40115 is not limited to this control configuration. Any other configuration is acceptable as long as it controls the speed or position of the rotating body 409 and generates a drive voltage command using the electric angle of the motor.

[0066] Next, let's return to the explanation of the first drive voltage generation circuit 4011 in Figure 4.

[0067] In the above description of the drive voltage command generation circuit 40115, it was shown that the current flowing through the first motor 402, the rotational speed of the rotating body 409, and the electrical angle of the first motor 402 are necessary. Below, the method for detecting the electrical angle of the first motor 402 will be explained.

[0068] The electrical angle detection circuit 40116 outputs the electrical angle of the first motor 402 based on the pulse signal from the rotational position sensor 405. The electrical angle detection circuit 40116 of the first motor 402 will be explained using Figure 6. Figure 6 is a detailed block diagram of the electrical angle detection circuit 40116.

[0069] In Figure 6, the electrical angle detection circuit 40116 consists of an electrical angle counter 40116a, an adder 40116b, and a correction value acquisition circuit 40116c.

[0070] The electrical angle counter 40116a generates a signal indicating the rotational position of the motor after one revolution from the pulse signal output by the rotational position sensor 405. An example is a motor with 10 poles, a reduction ratio of 10 for the gearbox 404, and a rotary encoder with 4000 ppr used in the rotational position sensor 405. When the first motor 402 completes one rotation, the rotational position sensor 405 outputs 400 pulse signals. Since the first motor 402 has 10 poles, there are 80 pulses per electrical angle. The electrical angle of the first motor 402 per pulse is 4.5 degrees. Therefore, an electrical angle can be generated by creating a counter that counts up 4.5 degrees per pulse and resets to 0 at 360 degrees. Note that the configuration of the electrical angle counter 40116a varies depending on the type of motor and reduction ratio.

[0071] The electrical angle output by the electrical angle counter 40116a is set to 0 degrees when the device starts up, and does not match the actual electrical angle of the first motor 402, meaning the stopping position differs each time the device starts up.

[0072] The adder 40116b adds a correction value to the electrical angle of the first motor 402 output by the electrical angle counter 40116a and outputs the result. The correction value is the angle value required to make the electrical angle match the actual electrical angle of the first motor 402.

[0073] The correction value acquisition circuit 40116c acquires a correction value to make the electrical angle output by the electrical angle counter 40116a the correct electrical angle.

[0074] This section describes how the correction value acquisition circuit 40116c obtains the correction value for the electrical angle.

[0075] The positioning voltage command generation circuit 40119 and switch 40118 shown in Figure 4 are used to obtain the correction value for the electrical angle.

[0076] The positioning voltage command generation circuit 40119 generates a voltage command for a positioning operation that moves the first motor 402 to a specific electrical angle position. This voltage command is a DC voltage value. For example, (U-phase voltage command, V-phase voltage command, W-phase voltage command) = (0V, 12V, -12V). When switch 40118 selects and outputs the output of the positioning voltage command generation circuit 40119, this voltage is applied to the motor, and the first motor 402 moves to an electrical angle of 90 degrees.

[0077] The correction value acquisition circuit 40116c applies the voltage from the positioning voltage command circuit 40119 to the first motor 402. After the first motor 402 moves to the position of the specified electrical angle, the correction value is obtained from the difference between the electrical angle output by the electrical angle counter 40116a and the specified electrical angle. The timing for obtaining the correction value is when the first motor 402 has moved to the position of the specified electrical angle and has come to a complete stop. This timing is determined based on the control signal from the CPU 301a. This timing is when the control signal from the CPU 301a applies the positioning voltage and a predetermined time has elapsed.

[0078] The following explains the process for obtaining the correction value, using the example of the first motor 402 being stopped at an electrical angle of 30 degrees.

[0079] First, the positioning voltage command generator 40119 applies (U-phase voltage command, V-phase voltage command, W-phase voltage command) = (0V, 12V, -12V) to the first motor 402. When the voltage is applied, the first motor 402 moves to the position of 90 degrees electrical angle, which is the specific electrical angle position mentioned above, and stops. At that time, the electrical angle detection circuit 40116 counts up the electrical angle based on the pulse signal, starting from 0 degrees electrical angle, by the amount of movement of the first motor 402.

[0080] Since the electrical angle before voltage is applied by the positioning voltage command generator 40119 is 30 degrees, the amount of movement of the first motor 402 will be 60 degrees. Therefore, the output of the electrical angle detection circuit 40116 will be 60 degrees.

[0081] Here, we can see that the difference between the actual electrical angle of the first motor 402 (90 degrees) and the output of the electrical angle detection circuit 40116 is 30 degrees. Therefore, the correction value in this case is 30 degrees.

[0082] By inputting a correction value of 30 degrees to the electrical angle detection circuit 40116, the electrical angle detection circuit 40116 will be able to output the correct electrical angle.

[0083] In this way, by applying a fixed DC voltage, which is the positioning voltage of the first motor 402, and moving the first motor 402 to the specific electrical angle position, a correction value, which is the difference between the output electrical angle of the electrical angle detection circuit 40116 and the actual electrical angle, can be obtained.

[0084] By using the positioning voltage command generation circuit 40119, the electrical angle detection circuit 40116 can detect the correct electrical angle. As a result, the drive voltage command generation circuit 40115 can use this electrical angle information to control the motor with high precision.

[0085] Next, we will explain the differences between the second drive voltage generation circuit 4012 and the first drive voltage generation circuit 4011.

[0086] The difference between the second drive voltage generation circuit 4012 and the first drive voltage generation circuit 4011 lies in the operation of switch 40118 in Figure 4. Otherwise, the second drive voltage generation circuit 4012 has the same configuration as the first drive voltage generation circuit 4011, so corresponding components will be denoted by the same reference numerals in the following description.

[0087] Switch 40118 selects an input and outputs an output based on a control signal from CPU 301a. The control signal from CPU 301a transitions in the order of 0, 1, 2, and 3.

[0088] The first drive voltage generation circuit 4011 selects the positioning voltage command generation circuit 40119 if the control signal from the CPU 301a is 1, and selects the output of the drive voltage command generation circuit 40115 otherwise.

[0089] The second drive voltage generation circuit 4012 selects the positioning voltage command generation circuit 40119 if the control signal from the CPU 301a is 2, and selects the output of the drive voltage command generation circuit 40115 otherwise.

[0090] The reason why the timing of applying the positioning voltage in the first drive voltage generation circuit 4011 and the second drive voltage generation circuit 4012 is shifted by the control signal from the CPU 301a will be explained.

[0091] As mentioned above, the first drive voltage generation circuit 4011 applies a positioning voltage to the first motor 402, moving the first motor 402 to the specific electrical angle position, thereby obtaining a correction value for obtaining an accurate electrical angle.

[0092] The second drive voltage generation circuit 4012 also needs to obtain a correction value for the second motor 403 in a similar manner.

[0093] However, when the first drive voltage generation circuit 4011 and the second drive voltage generation circuit 4012 simultaneously apply positioning voltages to the first motor 402 and the second motor 403, the correct correction value cannot be obtained.

[0094] This is because, when a positioning voltage is applied simultaneously to the first motor 402 and the second motor 403, if the rotation directions of the first motor 402 and the second motor 403 are opposite, or if the rotation directions are the same but the amount of rotation is different, the driving forces of the two motors will repel each other, causing them to stop at a position different from the specific electrical angle position mentioned above. This is because the first motor 402 and the second motor 403 are connected by a reduction gear 404.

[0095] Therefore, the positioning voltage must be applied to the first motor 402 and the second motor 403 at different timings, not simultaneously. By applying the voltage at different timings, both motors can obtain the correct correction value.

[0096] As explained above, the motor control device 401 operates based on control signals from the CPU 301a. The control of the motor control device 401 by the CPU 301a will be explained using Figure 7. Figure 7 is a flowchart showing the control of the motor control device 401 by the CPU 301a.

[0097] When the power to the image forming apparatus 100 is turned on, in step S101, the CPU 301a outputs a control signal = 0. In this state, no voltage is applied to the first motor 402 and the second motor 403, and they are not controlled.

[0098] Then, when the image formation job starts, the process transitions from step S102 to step S103.

[0099] In step S103, the CPU 301a outputs a control signal = 1. As a result, a positioning voltage is applied to the first motor 402, causing it to rotate to the specified electrical angle and stop. Since no voltage is applied to the second motor 403 and it is uncontrolled, it rotates by the same amount as the rotation of the first motor 402.

[0100] After transitioning to step S103, the process transitions from step S104 to step S105 after a time T1 has elapsed. Time T1 is set to be at least the maximum time required for the first motor 402 to move to the specific electrical angle position and come to a complete stop when a predetermined fixed voltage is applied to the first motor 402. Although not shown in Figure 7, at this timing, the correction value for the first motor 402 is obtained, and the correct electrical angle can be detected.

[0101] Next, in step S105, the CPU 301a outputs a control signal = 2. As a result, a positioning voltage is applied to the second motor 403, causing it to rotate to the rotation position of the specified electrical angle and then stop. Since no voltage is applied to the first motor 402 and it is uncontrolled, it rotates by the same amount as the rotation of the second motor 403.

[0102] After transitioning to step S105, the process transitions from step S106 to step S107 after a time T1 has elapsed. Time T1 is set to be at least the maximum time required for the second motor 403 to move to the specific electrical angle position and come to a complete stop when a predetermined fixed voltage is applied to the second motor 403, similar to step S104. Although not shown in Figure 7, at this timing, the correction value for the second motor 403 is obtained, and the correct electrical angle can be detected.

[0103] By performing the flow from step S103 to step S106 before starting motor control, it becomes possible to detect the correct electrical angles of the first motor 402 and the second motor 403 using the pulse signal from the rotational position sensor 405.

[0104] Next, rotational control of the first motor 402 and the second motor 403 is started. In step S107, a control signal of 3 is output. As a result, a voltage based on the voltage command output by the drive voltage command generation circuit 40115 is applied to both the first motor 402 and the second motor 403, and the motors are rotated according to a pre-set speed profile, and an image is output by the printer 150.

[0105] In step S108, the completion of the image formation job is notified, and after a predetermined time T2 has elapsed, the process transitions from step S109 to step S110. The predetermined time T2 is the time it takes for the motor to decelerate from the target speed and come to a stop.

[0106] In step S110, the control signal is set to 0 to terminate motor control.

[0107] In step S111, if there is a command to turn off the printer 150, the power is turned off. If there is no command, the process returns to step S102 and waits for the next image forming job.

[0108] The CPU 301a outputs control signals as shown in the flowchart in Figure 7. The motor control device 401 has a first drive voltage generation circuit 4011 and a second drive voltage generation circuit 4012. The timing of the application of the positioning voltage is determined according to the control signal from the CPU 301a, and the timing is shifted in order to obtain the correct electrical angle correction value.

[0109] Finally, using Figure 8, we will explain the process from when the CPU 301a and motor control device 401 start up, to when they acquire the correction values ​​for the electrical angles of the first motor 402 and the second motor 403, and when control of both motors begins. Figure 8 is an explanatory diagram of the method for acquiring the correction values ​​for the electrical angles of the first motor 402 and the second motor 403 in this embodiment.

[0110] As mentioned above, the switch 40118 of the first motor 402 outputs a positioning voltage when the control signal from the CPU 301a is 1, and a drive voltage command when the control signal from the CPU 301a is 0, 2, or 3. When the control signal from the CPU 301a is 0 or 2, the drive voltage command generation circuit 40115 is in the off state, and therefore no control is performed.

[0111] Similarly, the switch 40118 of the second motor 403 outputs a positioning voltage when the control signal from the CPU 301a is 2, and a drive voltage command when the control signal from the CPU 301a is 0, 1, or 3. When the control signal from the CPU 301a is 0 or 1, the drive voltage command generation circuit 40115 is in the off state, and therefore no control is performed.

[0112] The control signals from CPU301a output values ​​of 0, 1, 2, and 3, and transition in the order of 0, 1, 2, and 3.

[0113] In Figure 8, when the motor control device 401 is powered on, the control signal from the CPU 301a is 0. At this time, the drive voltage applied to both motors is 0, and the electrical angle is also 0.

[0114] Next, when the control signal from the CPU 301a becomes 1, (U-phase voltage command, V-phase voltage command, W-phase voltage command) = (0V, 12V, -12V) is applied to the first motor 402. As a result, the first motor 402 rotates until it reaches 90 degrees from its stopping electrical angle position and then stops. The electrical angle detection circuit 40116 in the first drive voltage generation circuit 4011 does not know the stopping electrical angle as shown in Figure 8, and starts with an electrical angle of 0, so the output electrical angle is not 90 degrees.

[0115] Since the first motor 402 stops at a rotational position of 90 degrees, the difference between the output of the electrical angle of the first motor 402 at this time and 90 degrees becomes the correction value. By setting this correction value, the electrical angle of the first motor 402 becomes the correct value, and the actual electrical angle of the motor matches the output of the electrical angle detection circuit 40116 of the first motor 402.

[0116] At this time, no voltage is applied to the second motor 403, and since it is connected to the first motor 402 via the reduction gear 404, it rotates at the same rate as the first motor 402 and then stops.

[0117] When the control signal from CPU 301a becomes 2, (U-phase voltage command, V-phase voltage command, W-phase voltage command) = (0V, 12V, -12V) is applied to the second motor 403. As a result, the second motor 403 rotates until it reaches 90 degrees from its stopping electrical angle position and then stops. The electrical angle detection circuit 40116 in the second drive voltage generation circuit 4012 does not know the stopping electrical angle, as shown in Figure 8, and starts with an electrical angle of 0, so the output electrical angle is not 90 degrees.

[0118] Since the second motor 403 stops at a rotational position of 90 degrees, the difference between the output of the electrical angle of the second motor 403 at this time and 90 degrees becomes the correction value. By setting this correction value, the electrical angle of the second motor 403 becomes the correct value, and the actual electrical angle of the motor matches the output of the electrical angle detection circuit 40116 of the second motor 403.

[0119] At this time, the first motor 402 has no voltage applied to it and is connected to the second motor 403 via the reduction gear 404, so it rotates the same amount as the second motor 403 and then stops. During this time, the electrical angle detection circuit 40116 needs to continue detecting.

[0120] By passing through states 1 and 2 of the control signal from CPU 301a, the correction values ​​for the electrical angles of the first motor 402 and the second motor 403 can be obtained. Finally, by setting the control signal from CPU 301a to 3, the voltage output by the drive voltage command generator 40115 is applied to both motors, and control of both motors begins.

[0121] As explained above, by performing the step of acquiring correction values ​​for the electrical angles of the two motors before starting motor control, it becomes possible to generate rotational position information for the two motors from the position detection information of the load in a configuration in which two motors control one load. This makes it possible to control the applied voltage based on the rotational position of the two motors in an inexpensive configuration without providing position detectors (rotary encoders, Hall elements, etc.) to the two motors.

[0122] In the above embodiment, the specific electrical angle is set to be the same for the first motor 402 and the second motor 403, but it may be set to a different electrical angle.

[0123] Furthermore, although the above embodiments show a configuration in which two motors control one load, the present invention can be similarly applied to configurations in which one motor controls one load or in which three or more motors control one load. [Explanation of Symbols]

[0124] 100…Image forming apparatus 140... Paper feed device 150... Printer 160... Finisher 301... System Controller 301a...CPU 401...Motor control device 4011...First drive voltage generation circuit 4012...Second drive voltage generation circuit 402... First Motor 403... Second motor 404...Reducer 405... Rotational position sensor 40111...Voltage command generation circuit 40114...Current detection circuit 40115...Drive voltage command generation circuit 40116... Electrical angle detection circuit 40118…Switch 40119...Positioning voltage command generation circuit

Claims

1. Motor and, The drive target is driven by the motor, A position information detection unit for detecting the operating position information of the driven object, A drive control means generates electrical angle information for the motor based on the position information detected by the position information detection unit when the motor is moved to a specific electrical angle position and the information of the specific electrical angle position, and controls the driving of the motor. A motor control device characterized by having the following features.

2. The motor control device according to claim 1, characterized in that the drive control means corrects the electrical angle information obtained from the position information detected by the position information detection unit with the information of the specific electrical angle position to generate the electrical angle information of the motor.

3. The motor control device according to claim 1, characterized in that the drive control means corrects the electrical angle information obtained from the position information detected by the position information detection unit using the difference between the electrical angle information obtained from the position information detected by the position information detection unit and the information of the specific electrical angle position, thereby generating the electrical angle information of the motor.

4. The motor control device according to claim 1, characterized in that the object to be driven is a rotating body.

5. The motor control device according to claim 1, characterized in that the target to be driven is a photosensitive drum or a fixing roller.

6. The motor control device according to claim 1, characterized in that the drive control means controls the speed of the drive target according to the position information detected by the position information detection unit and controls the drive current of the motor according to the electrical angle information of the motor.

7. The drive control means further includes a drive voltage generation unit that generates a drive voltage to be applied to the motor, The motor control device according to claim 1, characterized in that the drive voltage generation unit generates a drive voltage to be applied to the motor based on the electrical angle information of the motor.

8. The motor includes a first motor and a second motor, The motor control device according to claim 1, further comprising a drive force transmission unit connected to the first motor and the second motor, which combines the driving force of the first motor and the driving force of the second motor and transmits it to the object to be driven.

9. The motor control device according to claim 8, characterized in that the drive force transmission unit is a reduction gear.

10. The motor control device according to claim 8, characterized in that the drive control means connects the first motor to the drive force transmission unit and disconnects the second motor from the drive force transmission unit, moves the first motor to the specific electrical angle position and generates electrical angle information of the first motor based on the position information detected by the position information detection unit and the information of the specific electrical angle position, and also connects the second motor to the drive force transmission unit and disconnects the first motor from the drive force transmission unit, moves the second motor to the specific electrical angle position and generates electrical angle information of the second motor based on the position information detected by the position information detection unit and the information of the specific electrical angle position.

11. The motor control device according to claim 10, characterized in that the drive force transmission unit is a reduction gear.

12. A motor control device according to any one of claims 1 to 11, Image forming means that forms an image using the motor control device, An image forming apparatus characterized by having the following features.

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