JP2022184572A - Image forming apparatus - Google Patents

Abstract

To suspend image formation when toner is attached to photoreceptors while preventing motors from exceeding their rated temperatures and increasing the frequency at which a belt cleaner recovers the toner on the photoreceptors.SOLUTION: An image forming apparatus comprises: one or more motors for driving to rotate developing rollers, photoreceptors, and an intermediate transfer body; and control means that supplies coil current to the one or more motors to control the rotation of the one or more motors. When suspending image formation when toner is attached to the photoreceptors during the image formation, the control means determines, based on evaluation values for evaluating the temperatures of the one or more motors, whether to stop the one or more motors after transferring the toner attached to the photoreceptors to the intermediate transfer body or whether to stop the one or more motors without transferring the toner attached to the photoreceptors to the intermediate transfer body.SELECTED DRAWING: Figure 8

Description

The present invention relates to motor control technology in an image forming apparatus.

A brushless motor is used as a drive source for a rotating member of an image forming apparatus. Patent Document 1 discloses a configuration for limiting a coil current supplied to a coil of a motor in order to rotate the motor. By limiting the coil current, it is possible to suppress the temperature rise of the motor.

Japanese Patent Application Laid-Open No. 2001-209276

An electrophotographic image forming apparatus using an intermediate transfer member transfers a toner image formed on a photoreceptor to the intermediate transfer member, and transfers the toner image from the intermediate transfer member onto a sheet to form an image on the sheet. In such an image forming apparatus, the toner remaining on the intermediate transfer member without being transferred onto the sheet is recovered in a recovery container by a cleaning member (hereinafter referred to as a belt cleaner) that removes and recovers the residual toner on the intermediate transfer member. Toner remaining on the photoreceptor without being transferred to the intermediate transfer member is collected in a collection container by a cleaning member (hereinafter referred to as a photoreceptor cleaner) that removes and collects residual toner on the photoreceptor. Here, generally, the capacity of the collection container of the belt cleaner is larger than the capacity of the collection container of the photoreceptor cleaner. In order to prevent the collection container of the photoreceptor cleaner from becoming full early, the image forming apparatus is equipped with an intermediate transfer member that removes the toner adhered to the photoreceptor during image formation when the image forming operation is interrupted due to a jam or the like. Some are transferred and collected by a belt cleaner.

However, in order to collect the toner adhering to the photoreceptor with the belt cleaner, these members must be rotated until the toner on the photoreceptor is transferred to the intermediate transfer member and collected by the belt cleaner. For example, when image formation is interrupted due to an unexpected overload occurring in the motor that rotates these members, if the motor is rotated until the toner on the photoreceptor is collected by the belt cleaner, the temperature of the motor rises. may exceed its rated temperature. On the other hand, if the toner adhering to the photoreceptor is collected by the photoreceptor cleaner, the collection container of the photoreceptor cleaner becomes full early.

The present invention increases the frequency with which a belt cleaner collects the toner on the photoreceptor while preventing the rated temperature of the motor from exceeding when image formation is interrupted when toner adheres to the photoreceptor. It provides technology.

According to one aspect of the present invention, an image forming apparatus includes a photoreceptor, a developing roller that forms a toner image on the photoreceptor by causing toner to adhere to an electrostatic latent image formed on the photoreceptor, and the photoreceptor. an intermediate transfer member to which the toner image on the intermediate transfer member is transferred; image forming means for forming an image by transferring the toner image transferred on the intermediate transfer member to a sheet; the developing roller; one or more motors for rotationally driving the body and the intermediate transfer body; and control means for supplying a coil current to the one or more motors to control rotation of the one or more motors; When the image formation is interrupted while the toner is adhering to the photoreceptor in the image formation, the control means is configured to transfer the toner adhering to the photoreceptor to the intermediate transfer body and then transfer the toner adhering to the photoreceptor to the intermediate transfer body. The temperature of each of the one or more motors determines whether to stop the one or more motors or to stop the one or more motors without transferring the toner adhering to the photoreceptor to the intermediate transfer member. is determined based on an evaluation value for evaluating the

According to the present invention, when image formation is interrupted while toner is adhering to the photoreceptor, the frequency with which the toner on the photoreceptor is collected by the belt cleaner is increased while the rated temperature of the motor is not exceeded. can do.

1 is a configuration diagram of an image forming apparatus according to an embodiment; FIG. The block diagram of the motor control part by one Embodiment. 1 is a configuration diagram of a motor according to one embodiment; FIG. FIG. 4 is a diagram showing the relationship between load torque and coil current, and the relationship between load torque, coil temperature, and switching element temperature; FIG. 5 is a diagram showing coil current fluctuations due to load fluctuations under normal load; FIG. 4 is an explanatory diagram of motor control according to one embodiment; 4 is a flowchart of motor control according to one embodiment. Flowchart of processing executed by a control unit according to an embodiment

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. In addition, the following embodiments do not limit the invention according to the scope of claims. Although multiple features are described in the embodiments, not all of these multiple features are essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant description is omitted.

<First embodiment>
FIG. 1 is a configuration diagram of an image forming apparatus according to this embodiment. The image forming apparatus superimposes toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (K) to form a full-color image. In FIG. 1, Y, M, C and K at the end of the reference numerals indicate that the colors of the toner images involved in the formation of the members indicated by the reference numerals are yellow, magenta, cyan and black, respectively. . In the following description, reference numerals without Y, M, C, and K at the end are used when there is no need to distinguish between colors. The photoreceptor 13 is rotationally driven in the clockwise direction in the figure during image formation. The charging roller 15 charges the surface of the corresponding photoreceptor 13 to a uniform potential. The exposure unit 11 exposes the surface of the corresponding photoreceptor 13 to light to form an electrostatic latent image on the photoreceptor 13 . During image formation, the developing roller 16 of the developing unit 12 is driven to rotate in the counterclockwise direction of the drawing, and outputs a developing voltage to adhere toner to the corresponding electrostatic latent image on the photosensitive member 13 to form a toner image. to form The primary transfer roller 18 transfers the toner image formed on the corresponding photoreceptor 13 to the intermediate transfer belt 19, which is an intermediate transfer member, by the primary transfer voltage. The photoreceptor cleaner 14 (first cleaning member) removes toner remaining on the corresponding photoreceptor 13 without being transferred to the intermediate transfer belt 19 and collects it in the first toner collection container 17 . A full-color image is formed on the intermediate transfer belt 19 by superimposing and transferring the toner images formed on the photoreceptors 13 onto the intermediate transfer belt 19 .

The intermediate transfer belt 19 is rotationally driven counterclockwise in the figure during image formation. As a result, the toner image transferred onto the intermediate transfer belt 19 is conveyed to a position facing the secondary transfer roller 29 . On the other hand, the sheet 21 stored in the cassette 22 is fed from the cassette 22 to the conveying path by the rotation of each roller provided along the conveying path, and conveyed to the position facing the secondary transfer roller 29 . A secondary transfer roller 29 transfers the toner image on the intermediate transfer belt 19 onto the sheet 21 with a secondary transfer voltage. The belt cleaner 33 (second cleaning member) removes toner remaining on the intermediate transfer belt 19 without being transferred onto the sheet 21 and collects it in the second toner collecting container 34 . In this embodiment, the second collection container 34 provided in the belt cleaner 33 has a larger capacity than the first collection container 17 provided in the photoreceptor cleaner 14 . The sheet 21 onto which the toner image has been transferred is conveyed to the fixing section 30 . The fixing unit 30 heats and presses the sheet 21 to fix the toner image on the sheet 21 . After fixing the toner image, the sheet 21 is discharged outside the image forming apparatus.

A control unit 31 that controls the entire image forming apparatus includes a CPU 32 and a volatile and/or nonvolatile memory (not shown). The CPU 32 controls the image forming apparatus by executing programs stored in the memory. The image forming apparatus also includes one or more motors 101 ( FIG. 2 ) for rotating the photoreceptor 13 , developing roller 16 and intermediate transfer belt 19 . As described above, the second collection container 34 provided in the belt cleaner 33 has a larger capacity than the first collection container 17 provided in the photoreceptor cleaner 14 . Therefore, when the control unit 31 suspends or stops image formation without transferring the toner image to the intermediate transfer belt 19 after the toner is adhered to the photoreceptor 13 for forming a toner image, the photoreceptor 13 The toner on 13 is preferentially collected by the belt cleaner 33 rather than by the photoreceptor cleaner 14 . That is, when interrupting image formation, the controller 31 transfers as much toner as possible from the photoreceptor 13 onto the intermediate transfer belt 19 and causes the belt cleaner 33 to collect the toner.

FIG. 2 is a control configuration diagram of the motor 101. As shown in FIG. The motor control unit 120 has a microcomputer (hereinafter referred to as a microcomputer) 121 . A communication port 122 of the microcomputer 121 performs serial communication with the control unit 31 . The control unit 31 controls the rotation of the motor 101 by controlling the motor control unit 120 via serial communication. A reference clock generator 125 generates a reference clock based on the output of the crystal oscillator 126 . The counter 123 measures the cycle of the pulse based on this reference clock. The nonvolatile memory 124 stores various data used for motor control, programs executed by the microcomputer 121, and the like. Microcomputer 121 outputs a pulse width modulation signal (PWM signal) from PWM port 127 . In this embodiment, the microcomputer 121 outputs high-side PWM signals (UH, VH, WH) and low-side PWM signals for each of the three phases (U, V, W) of the motor 101. A total of 6 PWM signals (UL, VL, WL) are output. Thus, PWM port 127 has six terminals UH, VH, WH, UL, VL, and WL.

Each terminal of the PWM port 127 is connected to the gate driver 132, and the gate driver 132 performs ON/OFF control of each switching element of the three-phase inverter 131 based on the PWM signal. The inverter 131 has a total of six switching elements, three high-side and three low-side, for each phase, and the gate driver 132 controls each switching element based on the corresponding PWM signal. A transistor or an FET, for example, can be used as the switching element. In this embodiment, when the PWM signal is high, the corresponding switching element is turned on, and when it is low, the corresponding switching element is turned off. An output 133 of the inverter 131 is connected to coils 135 (U phase), 136 (V phase) and 137 (W phase) of the motor 101 . By controlling the on/off of each switching element of the inverter 131, the excitation current (coil current) of each coil 135, 136, 137 can be controlled. In this way, the microcomputer 121, the gate driver 132 and the inverter 131 function as a current supply unit that supplies coil currents to the plurality of coils 135, 136 and 137 and controls the current values of the coil currents.

The current sensor 130 outputs a detection voltage corresponding to the current value of the coil current flowing through each of the coils 135 , 136 and 137 . The amplifier 134 amplifies the detected voltage of each phase, applies an offset voltage, and outputs the amplified voltage to an analog/digital converter (AD converter) 129 . The AD converter 129 converts the amplified detection voltage into a digital value. The current value calculator 128 determines the coil current of each phase based on the output value (digital value) of the AD converter 129 . For example, the current sensor 130 outputs a voltage of 0.01 V per 1 A, the amplification factor (gain) of the amplification section 134 is 10, and the offset voltage applied by the amplification section 134 is 1.6V. Assuming that the range of the coil current flowing through the motor 101 is -10A to +10A, the voltage range output by the amplifier 134 is 0.6V to 2.6V. For example, if the AD converter 129 converts a voltage of 0 to 3V into a digital value of 0 to 4095 and outputs it, the coil current of -10A to +10A is converted into a digital value of approximately 819 to 3549. be. It should be noted that when the coil current flows in the direction from the inverter 131 to the motor 101, the current value is positive, and the reverse is the negative current value.

A current value calculator 128 subtracts an offset value corresponding to the offset voltage from the digital value and multiplies the result by a predetermined conversion coefficient to obtain the current value of the coil current. In this example, the offset value corresponding to the offset voltage (1.6V) is approximately 2184 (1.6*4095/3). Also, the conversion factor is approximately 0.000733 (3/4095). Thus, the current sensor 130, the amplifier 134, the AD converter 129, and the current value calculator 128 constitute a current detector that detects the current value of the coil current.

FIG. 3 is a configuration diagram of the motor 101. As shown in FIG. The motor 101 comprises a 6-slot stator 140 and a 4-pole rotor 141. The stator 140 is provided with U-phase, V-phase and W-phase coils 135, 136 and 137, respectively. The rotor 141 is made up of permanent magnets and has two pairs of north and south poles.

FIG. 4A shows the relationship between the load torque applied to the rotating shaft of the motor 101 and the coil current for rotating the rotor 141 at a predetermined target speed. As shown in FIG. 4A, the coil current and the load torque are in a proportional relationship and are expressed by the following equation (1).
Ic=(1/Kt)×T (1)
In equation (1), Ic is the coil current, T is the load torque, and Kt is the torque constant of the motor 101 . As is clear from FIG. 4A and equation (1), the coil current increases as the load increases.

4B shows the load torque applied to the rotating shaft of the motor 101 when the rotor 141 is rotated at the same predetermined target speed as in FIG. and the temperature of the switching element (switching element temperature). The relationship between the load torque and the coil temperature can be expressed by the following equation (2), and the relationship between the load torque and the switching element temperature can be expressed by the following equation (3).
Tc=a×T ² (2)
Tf=b×T ² (3)
In equations (2) and (3), Tc is the coil temperature, Tf is the switching element temperature, T is the load torque, a is the temperature rise coefficient of the coil, and b is the temperature rise of the switching element. is the coefficient. As is clear from FIG. 4B and equations (2) and (3), the coil temperature and the switching element temperature increase as the load torque increases.

For example, if the rated temperature of the coil of the motor 101 is 120 degrees, if the coil temperature exceeds 120 degrees, the insulation film of the coil will melt due to the heat, and the motor 101 may break down. From FIG. 4B, the load torque is 80 mNm when the coil temperature is 120 degrees. From FIG. 4A, the coil current value is 3.5 A when the load torque is 80 mNm. Therefore, in order to keep the coil temperature below 120°C, it is basically necessary to make the coil current below 3.5A. Even if the coil current temporarily exceeds 3.5 A for a short period of time, the coil temperature does not reach 120°C. In other words, in order to prevent failure of the motor 101, it is necessary to prevent the coil current exceeding 3.5 A from continuing for a predetermined period or longer.

FIG. 5 shows an example of changes over time in the coil current while the motor 101 is rotating at a predetermined target speed in a normal state in which the load on the motor 101 is normal. Even if the load is normal, momentary load fluctuations can occur. When the load increases due to load fluctuation, the coil current increases in order to prevent speed reduction due to the load increase and maintain the target speed. In FIG. 5, the coil current exceeds 3.5A twice. Here, if the coil current of the motor 101 is limited to 3.5 A or less, the rotational speed of the rotor 141 decreases when the load increases, and image defects such as image blurring and color shift may occur. In order to maintain the rotational speed of the rotor 141 at the target speed against load fluctuations, it is necessary to be able to supply the coil current required to cope with the load fluctuations. That is, it is necessary to supply the coil current so as to prevent the coil temperature from exceeding the rated temperature and suppress the rotation speed fluctuation of the rotor 141 when the load fluctuates.

For this reason, in the present embodiment, a coil current limit value IL associated with each motor 101, and a first threshold value Th1 and a second threshold value Th2 are provided as parameters related to motor control. A coil current limit IL associated with a motor 101 defines the maximum value of the coil current for that motor 101 . That is, the motor control unit 120 keeps the coil current of the motor 101 below the coil current limit value IL associated with the motor 101 . The coil current limit value IL is a variable value, and its initial value is set to a value capable of coping with load fluctuations when the rotor 141 is rotated at a target speed in a steady load state (normal time). Note that the initial value of the coil current limit value IL is also the maximum value of IL, which is a variable value. For example, when the load fluctuation in the normal state is as shown in FIG. 5, the maximum value of the coil current during the load fluctuation is about 4A. Therefore, the initial value of the coil current limit value IL is set to 4A or more. In the following description, the initial value of the coil current limit value IL is assumed to be 5 A, which is 1 A higher than 4 A, which is the maximum value of the coil current during load fluctuation.

The first threshold Th1 associated with the motor 101 is determined based on the current value of the coil current that brings the coil temperature of the motor 101 to the rated temperature. For example, if the characteristics of the motor 101 at the target speed are as shown in FIG. 4 and the rated temperature of the coil is 120° C., the current value of the coil current that brings the coil temperature to the rated temperature is 3.5A. In this case, for example, 3.5 A can be set as the first threshold Th1. Alternatively, a value considering a margin for 3.5A can be set as the first threshold Th1. In the following description, the first threshold Th1 associated with all motors 101 is assumed to be 3.5A. Furthermore, the second threshold Th2 associated with the motor 101 is set to a value smaller than the first threshold Th1 associated with the motor 101 by a predetermined value. In the following description, the second threshold Th2 associated with all motors 101 is set to 2.5 A, which is 1.0 A less than the first threshold Th1.

The control unit 31 obtains the average value of the coil current for each predetermined period. In the example below, this predetermined period is assumed to be 1 second. When the average value of the coil current of the motor 101 for one second is greater than the first threshold value Th1 associated with the motor 101, the control unit 31 decreases the coil current limit value IL associated with the motor 101 by a predetermined value. update to Further, when the average value of the coil current of the motor 101 for one second is smaller than the second threshold value Th2 associated with the motor 101, the control unit 31 increases the coil current limit value IL associated with the motor 101 by a predetermined value. Update as you go. In this example, these predetermined values are set to 0.1A.

FIG. 6A shows temporal changes in the coil current and the coil current limit value IL under normal load conditions. According to FIG. 6A, the coil current momentarily exceeds the first threshold Th1 (fixed at 3.5 A), but the average value for one second is smaller than the first threshold Th1, so the coil current limit value IL is It remains at the initial value (5A). FIG. 6B shows temporal changes in the coil current and the coil current limit value IL in the case of overload. According to FIG. 6(B), the coil current steadily flows at about 4.3 A and momentarily increases, but the maximum value is suppressed by the coil current limit value IL. In FIG. 6B, since the average value of the coil current for one second is greater than the first threshold value Th1, the coil current limit value IL is updated so as to gradually decrease (by 0.1 A) from the initial value (5 A). It is Further, when the coil current limit value IL becomes smaller than 4.3 A, which is the current value of the coil current flowing steadily, the control unit 31 cannot maintain the speed of the motor 101, and the motor 101 stops. be done.

As shown in FIG. 6A, according to the control of this embodiment, it is possible to cope with load fluctuations under normal load conditions. On the other hand, as shown in FIG. 6B, when overloaded, it is possible to prevent the motor from malfunctioning due to an excessive increase in coil temperature. In this embodiment, when the average value of the coil current for one second exceeds the first threshold value Th, the coil current limit value IL is decreased by a predetermined value regardless of the average value. However, it is also possible to configure such that the larger the average value or the larger the difference between the average value and the first threshold value Th1, the larger the decrease value of the coil current limit value IL.

FIG. 7 is a flowchart of processing executed by the control unit 31 according to this embodiment. It should be noted that the control unit 31 executes the processing in FIG. 7 when the rotation of the motor 101 is started due to the start of image formation. When the motor 101 reaches the target speed, the controller 31 sets the coil current limit value IL to an initial value, 5 A in this example, in S10. After that, in S11, the control unit 31 determines the average value Iave of the coil current for a predetermined period, and in S12, compares the average value Iave with the first threshold value Th1. If the average value Iave is greater than the first threshold value Th1, the controller 31 decreases the coil current limit value IL by a predetermined value, 0.1 in this example, in S13. After that, the control unit 31 determines in S14 whether the image formation is finished. If the image formation is completed, the control section 31 ends the processing of FIG. 7, and if the image formation is not completed, the control section 31 repeats the processing from S11.

On the other hand, if the average value Iave is equal to or lower than the temperature rise threshold Th1 in S12, the controller 31 compares the average value Iave with the second threshold Th2 in S15. If the average value Iave is smaller than the second threshold value Th2, the control unit 31 increases the coil current limit value IL by a predetermined value, 0.1 in this example, in S16, and performs the process of S14. On the other hand, if the average value Iave is equal to or greater than the second threshold, the control unit 31 performs the processing of S14 without updating the coil current limit value IL. The predetermined value to be decreased in S13 and the predetermined value to be increased in S16 may be the same value or different values. In S16, the coil current limit value IL is increased by a predetermined value. It can also be configured to increase the value. As described above, 5 A, which is the initial value of the coil current limit value IL, is also the maximum value that the coil current limit value IL can take. Therefore, if the value obtained by increasing the coil current limit value IL by a predetermined value is larger than the initial value of 5A in S16, the control unit 31 sets the coil current limit value IL after the update in S16 to 5A.

As described above, by dynamically controlling the coil current limit value IL based on the threshold value and the average value of the coil current, it is possible to cope with load fluctuations during normal operation, and at the time of overload (abnormal load), the coil temperature remains at the rated value. Exceeding the temperature can be prevented.

Next, when the toner is attached to the electrostatic latent image of the photoreceptor 13 to form a toner image on the photoreceptor 13 and the image formation is interrupted or stopped before the toner image is transferred to the intermediate transfer belt 19. Next, processing executed by the control unit 31 will be described with reference to the flowchart of FIG. The control unit 31 is notified by the motor control unit 120 that the rotation speed of one of the motors 101 that rotate the photoreceptor 13, the developing roller 16, and the intermediate transfer belt 19 has decreased. The process of FIG. 8 is executed at that time. When the rotation speed of the motor 101 becomes slower than the target speed by a predetermined speed or more, the motor control unit 120 notifies the control unit 31 of an abnormality in the speed of the motor 101, that is, a decrease in the rotation speed.

First, the basic concept of the flow chart of FIG. 8 will be described. As described above, the coil current limit value IL becomes smaller as the period during which the coil current whose average value is greater than the first threshold flows becomes longer. Therefore, when the coil current limit value IL is small, it means that a large coil current flows for a long period of time and the coil temperature is high. Therefore, in this embodiment, the coil current limit value IL is used as an evaluation value of the coil temperature. Note that the coil temperature is evaluated to be higher as the coil current limit value IL is smaller.

If the temperatures of all the motors 101 that rotate and drive the photoreceptor 13, the developing roller 16, and the intermediate transfer belt 19 are all equal to or lower than a predetermined temperature, the control unit 31 removes the toner from the photoreceptor 13. It is determined that the image is transferred to the intermediate transfer belt 19 and collected by the belt cleaner 33 . This is because when the temperatures of all the motors 101 are evaluated to be equal to or lower than the predetermined temperature, even if all the motors 101 continue to rotate until the belt cleaner 33 collects the toner on the photoreceptor 13, This is because the possibility that the coil temperature of the motor 101 exceeds the rating is low.

On the other hand, when the coil temperature of at least one of the one or more motors 101 is evaluated to be higher than the predetermined temperature, the control unit 31 quickly restarts all the motors 101 without collecting the toner on the photoreceptor 13 . stop. This is because, if there is a motor 101 whose coil temperature is evaluated to be higher than a predetermined temperature, there is a high possibility that the coil temperature of the motor 101 exceeds the rated temperature during the period until the belt cleaner 33 collects the toner on the photosensitive member 13. It is from. In this case, the uncollected toner on the photoreceptor 13 is collected by the photoreceptor cleaner 14 in the initialization sequence after the abnormality such as overload of the motor 101 is eliminated. The flowchart of FIG. 8 will be described below.

In S<b>20 , the control unit 31 determines whether or not all of the coil current limit values IL associated with each of the one or more motors 101 are equal to or greater than the determination threshold Th3 associated with each motor 101 . The determination threshold Th3 corresponds to the predetermined temperature, and in this example, the determination threshold Th3 associated with each of the one or more motors 101 is 4A. If the coil current limit value IL associated with at least one motor 101 out of the one or more motors 101 is smaller than the determination threshold Th3 associated with that motor 101, the controller 31 performs S23 as described above. , all of the one or more motors 101 are stopped. Therefore, the toner on the photoreceptor 13 is not collected at this time, and is separately collected by the photoreceptor cleaner 14 at a later timing.

On the other hand, if all of the coil current limit values IL associated with each of the one or more motors 101 are equal to or greater than the determination threshold value Th3, the control unit 31, in S21, controls the motor 101 in which the speed abnormality has occurred. The coil current limit value IL is set to the initial value (maximum value) of 5A. The reason why the coil current limit value IL of the motor 101 with the abnormal speed is set to the initial value of 5 A is to prevent the motor 101 from stopping unexpectedly and to ensure that the toner on the photoreceptor 13 is removed by the belt cleaner 33. This is because the In this example, the initial value of 5 A is set so that the coil temperature does not exceed the rated value even if the photosensitive member 13 is rotated until the belt cleaner 33 collects the toner.

In S<b>22 , the controller 31 causes the belt cleaner 33 to collect the toner on the photoreceptor 13 via the intermediate transfer belt 19 . After collecting the toner on the photoreceptor 13, the controller 31 stops the rotation of one or more motors 101 in S23.

In the flowchart of FIG. 8, in S21, the coil current limit value IL of the motor 101 in which the speed abnormality occurs is set to the initial value of 5 A, but it is configured to be set to a predetermined value different from the initial value. can be The predetermined value is greater than the determination threshold Th3 and less than the initial value, and is set so that the coil temperature does not exceed the rated value even if the photoreceptor 13 is rotated until the belt cleaner 33 collects the toner. be. Also, if the coil current limit value IL of the motor 101 causing the speed abnormality is smaller than a predetermined value, it is set to a predetermined value, and if it is equal to or greater than the predetermined value, the coil current limit value IL of the motor 101 is changed. It can also be configured not to. Furthermore, the processing of S21 may be omitted, and the processing of S22 may be performed without changing the coil current limit value IL of one or more motors 101 . Note that the processing of FIG. 7 is not executed during the processing of FIG. That is, after the coil current limit value IL of the motor 101 in which the speed abnormality has occurred is set to, for example, an initial value or a predetermined value in S21, the coil current limit value IL is not changed in the processes of S22 and S23.

In the flowchart of FIG. 8, when S20 is Yes, the belt cleaner 33 collects the toner on the photoreceptor 13 in S22. However, after the toner on the photoreceptor 13 is transferred to the intermediate transfer belt 19, the toner transferred to the intermediate transfer belt 19 is not collected by the belt cleaner 33, and the rotation of one or more motors 101 is stopped in S23. You can also In this case, the toner on the intermediate transfer belt 19 is collected by the belt cleaner 33 in the initialization sequence after the abnormality such as overload of the motor 101 is eliminated. In this case, the value of the coil current limit value IL of the motor 101 causing the speed abnormality after being changed in S21 is the same as that of the coil even if the photoreceptor 13 is rotated for the period until the toner on the intermediate transfer belt 19 is transferred to the intermediate transfer belt 19. It is set so that the temperature does not exceed the rating.

Furthermore, in the process of FIG. 8, the coil current limit value IL is used as the coil temperature evaluation value. However, the coil temperature can also be evaluated/determined by a temperature sensor or the like installed in the motor. Also in this case, if the coil temperatures of all of the one or more motors 101 are below the predetermined temperature, all the motors 101 are stopped after the toner on the photoreceptor 13 is transferred to the intermediate transfer belt 19. Otherwise, all the motors 101 are stopped without transferring the toner on the photoreceptor 13 to the intermediate transfer belt 19 .

As described above, according to the present embodiment, it is possible to increase the frequency with which the belt cleaner 33 collects the toner on the photoreceptor 13 while preventing the coil temperature from exceeding the rated value. With this configuration, it is possible to prevent the collection container of the photoreceptor cleaner 14 from becoming full early.

In the above embodiment, the one or more motors 101 for rotationally driving the photosensitive member 13, the developing roller 16, and the intermediate transfer belt 19 are of the same type. Therefore, the coil current limit value IL, the first threshold value Th1, the second threshold value Th2, and the determination threshold value Th3 associated with each motor 101 are set to the same value. However, the coil current limit IL, first threshold Th1, second threshold Th2 and decision threshold Th3 associated with each motor 101 may be different values.

[Other embodiments]
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by processing to It can also be implemented by a circuit (for example, ASIC) that implements one or more functions.

The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the claims are appended to make public the scope of the invention.

13Y, 13M, 13C, 13K: photoreceptors, 16Y, 16M, 16C, 16K: development rollers, 19: intermediate transfer belt, 31: control section

Claims (13)

a photoreceptor, a developing roller that forms a toner image on the photoreceptor by causing toner to adhere to the electrostatic latent image formed on the photoreceptor, and an intermediate transfer member to which the toner image on the photoreceptor is transferred; and image forming means for forming an image by transferring the toner image transferred to the intermediate transfer member onto a sheet;
one or more motors for rotating the developing roller, the photoreceptor, and the intermediate transfer member;
control means for supplying coil currents to the one or more motors to control rotation of the one or more motors;
with
When the image formation is interrupted while the toner is adhering to the photoreceptor in the image formation, the control means is configured to transfer the toner adhering to the photoreceptor to the intermediate transfer body and then transfer the toner adhering to the photoreceptor to the intermediate transfer body. The temperature of each of the one or more motors determines whether to stop the one or more motors or to stop the one or more motors without transferring the toner adhering to the photoreceptor to the intermediate transfer member. An image forming apparatus characterized in that determination is made based on an evaluation value for evaluating the. When the evaluation values of all of the one or more motors indicate that the temperature is equal to or lower than a predetermined temperature, the control means controls the temperature after transferring the toner adhering to the photoreceptor to the intermediate transfer body. When it is determined to stop the one or more motors, and the evaluation value of at least one of the one or more motors indicates that the temperature is higher than the predetermined temperature, the photoreceptor is adhered. 2. The image forming apparatus according to claim 1, wherein it is determined to stop the one or more motors without transferring the toner onto the intermediate transfer member. 3. The image forming apparatus according to claim 1, wherein the evaluation value of each of the one or more motors is a value based on current values of the coil currents of each of the one or more motors. For each of the one or more motors, the control means updates a limit value associated with the motor based on a current value of the coil current to be supplied to the motor, and adjusts the coil current to be supplied to the motor. controlling not to exceed the limit value associated with the motor;
2. The image forming apparatus according to claim 1, wherein the evaluation value for each of the one or more motors is the limit value associated with each of the one or more motors. The control means is configured to update the limit value associated with the motor to decrease if an average value of the current values of the coil current of the motor over a predetermined period exceeds a first threshold value. 5. The image forming apparatus according to claim 4. The control means increases the limit value associated with the motor if the average value of the current values of the coil currents of the motor over the predetermined period does not exceed a second threshold that is less than the first threshold. 6. The image forming apparatus according to claim 5, wherein the update is performed so that the image forming apparatus is updated. When all of the limit values associated with the one or more motors are equal to or greater than a first predetermined value, the controller controls the control means after transferring the toner adhering to the photoreceptor to the intermediate transfer member. determined to stop the one or more motors, and if the limit value associated with at least one of the one or more motors is less than the first predetermined value, the photoreceptor is adhered 7. The image forming apparatus according to claim 4, wherein it is determined to stop the one or more motors without transferring the toner onto the intermediate transfer member. When the control means interrupts the image formation due to an abnormality occurring in at least one of the one or more motors when the toner adheres to the photoreceptor, the toner adheres to the photoreceptor. stopping the one or more motors after transferring the toner adhering to the photoreceptor to the intermediate transfer member, or stopping the one or more motors without transferring the toner adhering to the photoreceptor to the intermediate transfer member; 8. The image forming apparatus according to claim 7, wherein it is determined whether to stop the operation. When the control means determines to stop the one or more motors after transferring the toner adhering to the photoreceptor to the intermediate transfer body, the control means determines that the one or more motors associated with the at least one motor in which an abnormality has occurred 9. The image forming apparatus according to claim 8, wherein the limit value is updated to the maximum limit value. When the control means determines to stop the one or more motors after transferring the toner adhering to the photoreceptor to the intermediate transfer body, the control means determines that the one or more motors associated with the at least one motor in which an abnormality has occurred comparing the limit value to a second predetermined value greater than the first predetermined value, and if any of the limit values associated with the at least one malfunctioning motor is less than the second predetermined value; 9. The image forming apparatus according to claim 8, wherein the limit value is updated to the second predetermined value. When the controller determines to stop the one or more motors after the toner adhering to the photoreceptor is transferred to the intermediate transfer body, the control means controls until the one or more motors are stopped. 11. The image forming apparatus of claim 4, wherein the limit value associated with each of the one or more motors is not updated based on the current value of the coil current. further comprising cleaning means for removing and collecting toner remaining on the intermediate transfer body;
When the controller determines to stop the one or more motors after transferring the toner adhering to the photoreceptor to the intermediate transfer body, the control means transfers the toner adhering to the photoreceptor to the intermediate transfer body. 12. The method according to any one of claims 1 to 11, wherein the one or more motors are stopped after the toner is transferred onto the transfer member and the toner transferred onto the intermediate transfer member is recovered by the cleaning means. The described image forming apparatus. further comprising cleaning means for removing and collecting toner remaining on the intermediate transfer body;
When the controller determines to stop the one or more motors after transferring the toner adhering to the photoreceptor to the intermediate transfer body, the control means transfers the toner adhering to the photoreceptor to the intermediate transfer body. 12. The one or more motors according to any one of claims 1 to 11, wherein after transferring onto the transfer member, the one or more motors are stopped before the toner transferred onto the intermediate transfer member is recovered by the cleaning means. 10. The image forming apparatus according to claim 1.

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