JP5397732B2 - Image forming apparatus, control method, and control program - Google Patents

Description

  The present invention relates to an image forming apparatus, a control method, and a control program, and more particularly, to an image forming apparatus that uses a stepping motor in a medium speed resonance region, a control method for controlling resonance of the stepping motor, and a control program.

  In an electrophotographic image forming apparatus, a photosensitive drum uniformly charged by a charging device is irradiated with light from an exposure device to form an electrostatic latent image, and toner is attached to the electrostatic latent image by a developing device. The toner image is visualized as a toner image, and the toner image is transferred from the photosensitive drum to the paper via the intermediate transfer belt, and then the toner image is fixed on the paper by heating and pressing with a fixing device. ing.

  In such an image forming apparatus, it is necessary to control the sheet so that the image formed on the intermediate transfer belt is transferred to an appropriate position on the sheet. Therefore, a stepping motor is mainly used as a drive source for paper feeding and transport operations.

  In this stepping motor, for example, when a paper transport operation is performed, a set current is determined by a driving IC, and a necessary output torque is applied to the motor based on the set current. Moreover, the motor is rotated at a desired rotation speed by making the drive current into a pulse waveform having a predetermined pulse rate corresponding to the conveyance speed.

  Here, like a stepping motor, a device that repeats operation / stopping at short intervals is likely to vibrate, and this vibration causes unpleasant noise, decreases reliability, and in some cases, the stepping motor A phenomenon (referred to as step-out) occurs in which the rotational speed deviates from the rotational speed defined by the pulse rate.

  Particularly in recent image forming apparatuses, there is a need to rotate the stepping motor at a high speed due to a demand for high speed / wide range, and there are many cases where it is used in a so-called medium speed resonance region. In this region, the motor tends to resonate at the natural frequency of the motor due to variations in manufacturing of the motor, variations in the drive circuit, and the like, and the above-described problem appears remarkably due to this resonance.

  In response to the problem of step-out, Patent Document 1 below proposes a method of detecting the motor current and stepping down the rotational speed of the motor when step-out is detected. However, this method lowers the number of rotations of the motor after detecting the step-out, and the occurrence of the step-out itself cannot be suppressed. Therefore, Patent Document 2 below proposes a method of performing feedback control that detects a current waveform, extracts a natural vibration, and cancels it.

JP-A-2002-199794 JP 11-196598 A

  However, the method of Patent Document 2 extracts torque ripple from the motor current and applies feedback to the motor setting current so that the motor current is always constant. The rising portion and the chopping portion of FIG. 2 are effective, but the portion where the back electromotive force is generated without applying a voltage (the falling portion of the waveform) cannot be controlled and has no effect.

  That is, when the rotation speed of the stepping motor is relatively low, since the ratio of the rising and chopping portions in the current waveform is large, the resonance phenomenon can be suppressed by controlling based on the rising and chopping portions of the waveform. However, in the medium-speed resonance region, the ratio of the falling portion in the current waveform is large, and the disturbance of the waveform at the falling portion greatly affects the vibration. Therefore, the above control cannot sufficiently suppress the resonance phenomenon.

  The present invention has been made in view of the above problems, and a main object thereof is to provide an image forming apparatus, a control method, and a control program capable of avoiding a resonance phenomenon of a stepping motor.

In order to achieve the above object, the present invention provides an image having at least a photoreceptor, means for transferring a latent image formed on the photoreceptor to a sheet, and means for feeding and transporting the sheet by a stepping motor. In the forming apparatus, when the current waveform of the stepping motor is detected and the degree of variation in the area of each period of the current waveform exceeds a predetermined reference value, it is determined that vibration due to a resonance phenomenon has occurred, And a controller that changes the driving condition of the stepping motor to a condition that does not generate vibration due to a resonance phenomenon.

  In the present invention, the driving condition may be a current value and / or a pulse rate of the stepping motor.

Further, in the present invention, the control unit gradually decreases the current value until the degree of variation in the area becomes equal to or less than the reference value, and the current in which the degree of variation in the area becomes equal to or less than the reference value. The stepping motor can be driven with a value to perform a copying operation or a printing operation.

In the present invention, the control unit gradually decreases the pulse rate until the degree of variation in the area becomes equal to or less than the reference value, and the pulse in which the degree of variation in the area becomes equal to or less than the reference value. The stepping motor can be driven at a rate to perform a copy operation or a print operation.

In the present invention, the control unit lowers the current value step by step, and when the step-out occurs before the degree of variation in the area becomes equal to or less than the reference value, the control unit steps out the current value. After returning to a value that does not generate a pulse, the pulse rate is decreased stepwise until the degree of variation in the area becomes less than or equal to the reference value, and the current value and pulse in which the degree of variation in the area becomes less than or equal to the reference value The stepping motor can be driven at a rate to perform a copy operation or a print operation.

In the present invention, the control unit lowers the current value step by step, and when the step-out occurs before the degree of variation in the area becomes equal to or less than the reference value, the control unit steps out the current value. back to the value but does not occur, after lowering the pulse rate by one step, a process of determining whether the degree of variation of the area exceeds the reference value, the degree of variation of the area exceeds the reference value If it is, the repeating the process until the degree of variation of the area without step-out occurs is below the reference value, the current value and the pulse rate the degree of variation of the area is equal to or less than the reference value Thus, the stepping motor can be driven to perform a copy operation or a print operation.

  According to the present invention, the current waveform is detected when the power is turned on, when the temperature detected by the temperature sensor in the image forming apparatus exceeds a predetermined threshold, when returning from sleep, and when supplying or replacing consumables. When a predetermined number of copies are made, when a predetermined time elapses, or when the stepping motor is replaced, one or more cases can be selected.

Further, in the present invention, the detection of the current waveform is performed during a copy operation or a print operation, and when the degree of variation in the area exceeds the reference value, the copy operation or the print operation is temporarily interrupted, The copying operation or the printing operation can be restarted after changing the driving condition of the stepping motor to a condition that does not generate vibration.

  The control program of the present invention is a control program that operates in the image forming apparatus, and causes a computer to function as the control unit described in any one of the above.

The present invention also provides a method for controlling an image forming apparatus, comprising at least a photoconductor, a means for transferring a latent image formed on the photoconductor to paper, and a means for feeding and transporting the paper by a stepping motor. Then, detecting the current waveform of the stepping motor, and determining that the vibration due to the resonance phenomenon has occurred when the degree of variation of the area for each period of the current waveform exceeds a predetermined reference value, The driving condition of the stepping motor is changed to a condition that does not generate vibration due to a resonance phenomenon.

  According to the image forming apparatus, the control method, and the control program of the present invention, the resonance phenomenon of the stepping motor can be avoided.

  The reason is that the control unit (control program) obtains the area of the current waveform, and when the change in the area is large, it is determined that the stepping motor is resonating, and control is performed to lower the set current or lower the pulse rate. Because it does.

  As shown in the background art, in an image forming apparatus, a stepping motor is used as a driving source for paper feeding and conveying operations. However, due to recent demands for higher speeds / wide ranges, stepping motors are motors. In many cases, the resonance frequency is used in a medium-speed resonance region that easily resonates at a natural frequency. This resonance causes problems such as generation of noise, deterioration of reliability, and occurrence of step-out.

  As a method of suppressing the step-out, there is a method of shaping the shape of the rising part and the chopping part in the current waveform, but in the medium-speed resonance region, the falling part in the current waveform accounts for a large proportion and the influence of natural vibrations. Appears also in this portion, the resonance phenomenon cannot be sufficiently suppressed by the above control.

  Therefore, in the present invention, in order to avoid unstable rotation due to the medium-speed resonance region of the stepping motor, the rotation fluctuation is detected from the change in the area of the current waveform acquired at the current detection terminal of the drive IC, and the rotation fluctuation is detected. Is large (when the change in area is large), it is determined that the stepping motor is resonating, and control is performed to change to a condition that does not cause resonance (for example, lower the set current or lower the pulse rate).

  In this way, by driving the stepping motor under conditions where resonance does not occur, unpleasant noise in the image forming apparatus can be suppressed and reliability can be improved.

  In order to describe the above-described embodiment of the present invention in more detail, an image forming apparatus, a control method, and a control program according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view schematically showing the configuration of the image forming apparatus of this embodiment, and FIG. 2 is a block diagram showing the configuration of the control board of the image forming apparatus. 3 to 8 are diagrams showing the current characteristics and control method of the stepping motor of this embodiment, and FIGS. 9 to 15 are flowcharts showing specific procedures of the control method of this embodiment. is there.

  First, the structure of the image forming apparatus of this embodiment will be described. FIG. 1 shows a cross-sectional structure of a main part of a tandem color printer, and an image forming unit and a conveying unit are main components. Note that the suffixes (a to d) of the numbers in the figure correspond to yellow (Y), magenta (M), cyan (C), and black (K), respectively.

  The image forming unit includes a photosensitive drum 3a to 3d, charging units 5a to 5d for charging the photosensitive members 3a to 3d, an exposure unit 6 for exposing an image pattern, and developing units 4a to 4d for developing toner. ˜28d, an intermediate transfer belt 2 that forms an image by superimposing four color toner images formed on the photoreceptors 3a to 3d, and an intermediate transfer belt cleaner 7 that separates transfer residual toner from the intermediate transfer belt 2. Waste toner box 15 for storing the transferred residual toner, toner bottles 25a to 25d for supplying toner to cartridges 28a to 28d by operating stirring blades 26a to 26d, developing motors 21 and 22, toner replenishing motor 23, 24 or the like.

  The conveyance unit also feeds a recording medium from the recording medium storage unit 16, a timing roller 10 for temporarily stopping the fed recording medium, and a toner image formed on the intermediate transfer belt 2. A secondary transfer roller 11 for transferring the toner onto the recording medium, a cleaning unit (not shown) for removing the toner adhering to the secondary transfer roller 11, and a fixing roller 12a for fixing the toner image transferred onto the recording medium. 12b, a discharge roller 13 that discharges the fixed recording medium or transports it to the double-sided transport path 29, double-sided path transport rollers 14a and 14b that transport to the timing roller 10 via the double-sided transport path 29, and a color PC The motor 17 is composed of various motors such as a main motor 18 and a fixing motor 19. A stepping motor is mainly used as a motor for feeding and transporting paper.

  Next, the configuration of the control board of the image forming apparatus of this embodiment will be described. As shown in FIG. 2, the control board includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a data storage unit (for example, HDD: Hard Disk Drive), and a drive. Consists of IC and the like.

  The ROM stores a program for controlling the operation of the entire image forming apparatus and data necessary for the control (for example, a standard value of a driving condition of a stepping motor described later). The RAM and the data storage unit store data necessary for control by the CPU and data that needs to be temporarily stored during the control operation (for example, a voltage value of the stepping motor or a value obtained by multiplying the voltage value and the sampling time). The CPU functions as a control unit that controls the operation of the entire image forming apparatus in cooperation with the ROM, the RAM, and the data storage unit.

  The driving IC is a circuit for driving a stepping motor, receives a driving pulse and an enable signal from a CPU (control unit), generates a signal of a predetermined current value and pulse rate, and generates a stepping motor via a motor drive line. Send to.

  Then, the control unit monitors the voltage of the current detection terminal provided on the control board, calculates the current value, calculates the area of the current waveform (the area including the rising part, the chopping part, and the falling part), When the variation of the area exceeds a predetermined reference value, it is determined that resonance has occurred, and control for suppressing the resonance (for example, control for decreasing the current value or decreasing the pulse rate) is performed. The function of the control unit may be executed as hardware, or may be executed as a control program that causes a computer to function as the control unit.

  Hereinafter, a specific description will be given based on an actual current waveform.

  FIG. 3 shows the variation of the current waveform and its area when the current value is kept constant and the pulse rate is gradually increased. According to FIG. 3, there is no disturbance in the current waveform and the variation in the area is small until the pulse rate is up to 2800 pps. However, it can be seen that the current waveform is disturbed from 3000 pps, and the variation of the area is large. Here, since the output torque of the stepping motor depends on the current, if the variation in the area of the current waveform increases, the fluctuation of the output torque increases, and vibration occurs at the natural frequency of the stepping motor. Therefore, it is possible to detect vibration by monitoring the variation in the area of the current waveform.

  FIG. 4 shows the relationship between the pulse rate and pull-out torque (load torque that rotates without step-out) when the current value is changed, and the current waveform when the pulse rate is 3200 pps. As shown in FIG. 4A, when the initial value of the current value is 1.1 A, the pullout torque decreases at a substantially constant rate as the pulse rate increases in the region where the pulse rate is 2500 pps or less and the region where the pulse rate is 4000 pps or more. However, in the region (vibration region) where the pulse rate is 2500 to 4000 pps, as shown in FIG. 4B, the variation rate (79%) of the area of the current waveform has a predetermined reference value (20%). The pull-out torque is significantly reduced and greatly reduced.

  Here, when the setting of the current value is lowered (for example, from 1.1 A to 0.6 A), the vibration region shifts to the higher pulse rate, so that the current waveform is changed as shown in FIG. The variation rate of the area is as small as 9%, which is equal to or less than a predetermined reference value (20%). As a result, torque fluctuation is reduced, and vibration at the natural frequency of the stepping motor can be suppressed.

  FIG. 5 is a graph showing the characteristics of FIG. 4A in terms of acceleration time and speed of the stepping motor when the current value is initially set (1.1 A). As shown in FIG. 5A, when the pulse rate is high (for example, 3200 pps), the stepping motor operates in the vibration region where the speed greatly changes, and the current waveform at that time is as shown in FIG. The variation rate (79%) of the waveform area greatly exceeds a predetermined reference value (20%).

  In this case, if the pulse rate is lowered (for example, lowered from 3200 pps to 2600 pps), the stepping motor operates in the region before the vibration region, and the current waveform at that time becomes as shown in FIG. The variation rate of the area is as small as 9%, which is not more than a predetermined reference value (20%). As a result, torque fluctuation is reduced, and vibration at the natural frequency of the stepping motor can be suppressed.

  4 and 5, when the variation rate of the current waveform area exceeds the reference value, control is performed to reduce the current or pulse rate setting to a predetermined value at once. When the pulse rate is decreased, the speed of the stepping motor is decreased and the processing capacity is decreased. Therefore, in order to prevent a harmful effect caused by excessively reducing the current and pulse rate values, the current and pulse rate values can be gradually decreased.

  For example, as shown in FIG. 6, when the variation rate of the area of the current waveform exceeds the reference value, the setting of the current value is temporarily reduced from 1.1 A to 0.8 A, and in that state, the variation rate becomes the reference value. If the variation rate exceeds the reference value even in this state, the current value setting may be further controlled to 0.6 A. Similarly, as shown in FIG. 7, when the variation rate of the area of the current waveform exceeds the reference value, the pulse rate is temporarily reduced from 3200 pps to 3000 pps, and it is determined whether the variation rate exceeds the reference value in that state. Even in this state, when the variation rate exceeds the reference value, the pulse rate setting may be further reduced to 2600 pps.

  It should be noted that how many times the current value or pulse rate is lowered and how much the reduction rate is set can be set as appropriate, and the number of times and the reduction rate are changed in accordance with the extent to which the area variation rate exceeds the reference value. It may be. For example, when the variation rate greatly exceeds the reference value, it is possible to perform control such as increasing the number of times and increasing the initial reduction range.

  4 to 7, the control for reducing one of the current value and the pulse rate is performed. However, the control for reducing the current value and the control for reducing the pulse rate can be combined.

  For example, as shown in FIG. 8A, with the current value set to 1.1 A and the pulse rate set to 3200 pps, the variation rate of the current waveform area exceeds the reference value as shown in FIG. 8B. In this case, the current value reduction width can be set (here, 1.1 A → 0.8 A) so that the reduction rate of the pulse rate falls within an allowable range (here, 3200 pps → 2750 pps). Even by such control, the current waveform can be made to have a small variation rate as shown in FIG.

  Although the current value and the pulse rate are controlled simultaneously here, they may be controlled separately. For example, the current value may be lowered within a range where sufficient torque can be secured, and the pulse rate may be controlled after checking the variation rate of the current waveform area in this state, or within a range where sufficient processing speed can be secured. Control may be performed to reduce the current value after reducing the pulse rate and examining the variation rate of the area of the current waveform in this state. In addition, each control may be performed a plurality of times, such as lowering the current value (or pulse rate), lowering the pulse rate (or current value), and further lowering the current value (or pulse rate).

  Hereinafter, the specific procedure of the control method of the present embodiment will be described with reference to the flowcharts of FIGS.

  First, the procedure for determining the presence or absence of vibration of the stepping motor will be described with reference to FIG. 9A and 9B are separated for the convenience of drawing and show a series of operations.

  First, the control unit sets standard conditions as driving conditions for the stepping motor (step S101). This driving condition includes a current value and a pulse rate, and the standard condition is stored in advance in a ROM, a data storage unit, or the like. The standard conditions may be set by the user using a touch panel, buttons, or the like provided in advance in the image forming apparatus.

  Next, the control unit sends a drive pulse and an enable signal to the drive IC, and the drive IC generates a signal having a current value and a pulse rate set as standard conditions, and drives the stepping motor (step S102).

  When the acceleration of the stepping motor is completed and the constant speed operation is started (step S103), the control unit starts observing the current waveform of the signal obtained at the current detection terminal (step S104).

  Next, the control unit determines whether the waveform value of the current waveform is “0” (step S105). If the waveform value is “0”, it determines that the phase is 0 degree and calculates the area of the current waveform. Is started (step S106).

  Next, the control unit resets the numerical value in the first area (memory 1) such as RAM (step S107), and then continues in the second area (memory 2) such as RAM. The numerical value is reset (step S108).

  Next, the control unit replaces the voltage value from the current detection terminal with the current value for each minimum sampling time of the CPU and stores it in the memory 1 (step S109), and a value obtained by multiplying the minimum sampling time by the voltage value. Is added to the memory 2 (step S110), and then the numerical value in the memory 1 is reset (step S112).

  Next, the control unit determines whether the waveform value is “0” (step S112). If it is not “0”, the control unit returns to step S108 and repeats the same processing. The total value added to is stored in a third area (memory 3) such as a RAM (step S113).

  Next, the control unit determines whether the waveform value is “0” (step S114). If the waveform value is “0”, the control unit determines that the phase is 0 degree and starts calculating the area of the next waveform (step S114). In step S115, the processes in steps S116 to S121 are performed in the same manner as described above, and the total value added to the memory 2 is stored in a fourth area (referred to as the memory 4) such as a RAM (step S122).

Next, the control unit determines whether the value stored in the memory 4 exceeds a predetermined reference value (for example, 20%) with respect to the value stored in the memory 3. Specifically, if the value stored in the memory 3 is S1, the value stored in the memory 4 is S2, and the reference value is A,
| (S4-S3) / S3 | × 100> A (1)
Is determined (step S123).

  If the reference value is exceeded, the control unit determines that vibration due to resonance has occurred (step S124). On the other hand, if the reference value is not exceeded, the control unit moves the value in the memory 3 to the memory 4 (step S125), and then determines whether or not the stepping motor is being driven. Return and repeat the same process.

  On the other hand, if not being driven, the signal measurement is terminated with no vibration due to resonance (step S127).

  Next, the procedure for controlling the current value of the stepping motor in steps S123 and S124 will be described with reference to FIG.

  The control unit determines whether the variation rate of the area for each waveform acquired in the same procedure as steps S101 to S122 in the flowchart of FIG. 9 exceeds a predetermined reference value (for example, 20%) (step S201).

  If the area variation rate exceeds the reference value, the control unit determines that vibration due to resonance has occurred, and reduces the current value of the motor to a predetermined value (for example, 0.1 A) ( Step S203) After changing the rotation of the stepping motor (Step S204), the process returns to Step S201 and the same processing is repeated.

  On the other hand, if the variation rate of the area is equal to or less than the reference value, the control unit determines that there is no vibration due to resonance and determines the current setting as the operation condition (step S202).

  Next, the procedure for controlling the pulse rate of the stepping motor in steps S123 and S124 will be described with reference to FIG.

  The control unit determines whether the variation rate of the area for each waveform acquired in the same procedure as steps S101 to S122 in the flowchart of FIG. 9 exceeds a predetermined reference value (for example, 20%) (step S301).

  If the area variation rate exceeds the reference value, the control unit determines that vibration due to resonance has occurred, and lowers the pulse rate of the motor to a predetermined value (for example, 100 pps) (step S303). ) After changing the rotation of the stepping motor (step S304), the process returns to step S301 and the same processing is repeated.

  On the other hand, if the variation rate of the area is equal to or less than the reference value, the control unit determines that there is no vibration due to resonance and determines the current setting as an operation condition (step S302).

  Next, the procedure for controlling the current value and pulse rate of the stepping motor in steps S123 and S124 will be described with reference to FIG. In this flow, the pulse rate is changed after the current value is changed.

  The control unit determines whether the variation rate of the area for each waveform acquired in the same procedure as steps S101 to S122 in the flowchart of FIG. 9 exceeds a predetermined reference value (for example, 20%) (step S401).

  If the area variation rate exceeds the reference value, the control unit determines that vibration due to resonance has occurred, and reduces the current value of the motor to a predetermined value (for example, 0.1 A) ( In step S403, it is determined whether or not the stepping motor is out of step (step S404). If not out of step, the process returns to step S401 and the same processing is repeated.

  On the other hand, if there is a step-out, the control unit returns the current value to the setting before the change, restarts (step S405), and then reduces the motor pulse rate to a predetermined value (for example, 100 pps) (step S405). In step S406, it is determined whether the area variation rate exceeds the reference value (step S407). If the area variation rate exceeds the reference value, the process returns to step S406 to further reduce the pulse rate.

  On the other hand, if the area variation rate is equal to or less than the reference value, the control unit determines that there is no vibration due to resonance, and determines the current setting as the operation condition (step S402).

  Next, another procedure for controlling the current value and pulse rate of the stepping motor in steps S123 and S124 will be described with reference to FIG. In addition, this flow repeats a change of an electric current value and a pulse rate.

  The control unit determines whether or not the variation in the area of each waveform acquired in the same procedure as steps S101 to S122 in the flowchart of FIG. 9 exceeds a predetermined reference value (for example, 20%) (step S501). ).

  If the area variation rate exceeds the reference value, the control unit determines that vibration due to resonance has occurred, and reduces the current value of the motor to a predetermined value (for example, 0.1 A) ( Step S503), it is determined whether or not the stepping motor has stepped out (Step S504). If not out of step, the process returns to step S501 and the same processing is repeated.

  On the other hand, if there is a step-out, the control unit returns the current value to the setting before the change, restarts (step S505), and then lowers the pulse rate of the motor to a predetermined value (for example, 100 pps) (step S505). S506), it is determined whether the area variation rate exceeds the reference value (step S507). If the area variation rate exceeds the reference value, the process returns to step S401 and the same processing is repeated.

  On the other hand, if the area variation rate is equal to or less than the reference value, the control unit determines that there is no vibration due to resonance and determines the current setting as the operation condition (step S502).

  Next, with reference to FIG. 14, the determination of the timing for detecting the vibration of the stepping motor will be described.

  First, the control unit determines whether the current state is a timing for detecting the vibration of the stepping motor (step S601).

  Specifically, since it is necessary to check the operation of the stepping motor when the power is turned on, it is determined whether the power is turned on. Further, since the operation of the stepping motor becomes unstable when the temperature in the apparatus rises, it is determined whether the temperature detected by the temperature sensor provided in the apparatus exceeds a predetermined threshold value. Further, when the operation condition of the stepping motor is changed, vibration is likely to occur, so it is determined whether the sleeve is being returned. Further, since vibration is likely to occur when paper is fed into the paper tray or when the toner is replaced, it is determined whether it is during replenishment / replacement. Further, since the vibration is likely to occur when the stepping motor is operated for a long time, it is determined whether a preset number of copies (for example, 2000 copies) or a preset time (for example, 720 hours) has elapsed. to decide. Further, since it is necessary to check the operation even when the stepping motor is replaced, it is determined whether the motor has been replaced in response to service.

  Then, if the current state is not the timing for detecting the vibration of the stepping motor, the control unit operates in a normal machine sequence (step S602), and if it is the timing for detecting the vibration, the above-described FIGS. The control according to the flowchart is performed.

  Next, a control procedure of the copy operation will be described with reference to FIG.

  The control unit determines whether the variation rate of the area for each waveform acquired in the same procedure as steps S101 to S122 in the flowchart of FIG. 9 exceeds a predetermined reference value (for example, 20%) (step S701).

  If the variation rate of the area exceeds the reference value, the control unit determines that vibration due to resonance has occurred, temporarily stops the copy operation (step S703), and the flowcharts of FIGS. After performing the corresponding control (step S704), the copying operation is resumed (step S705).

  On the other hand, if the area variation rate is equal to or less than the reference value or after the control according to the flowcharts of FIGS. 10 to 13 is performed, the control unit determines that there is no vibration due to resonance and sets the current setting as the operating condition. (Step S702).

  In this way, the control unit (control program) obtains the area of the current waveform, and when the variation rate of the area exceeds the reference value, determines that the stepping motor is resonating and decreases the current value or sets the pulse rate. By performing the lowering control, the resonance phenomenon of the stepping motor can be avoided.

  In the above embodiment, the case where the control of the present invention is applied to the image forming apparatus has been shown. However, the present invention is not limited to the above embodiment, and the same applies to any apparatus using a stepping motor. Can be applied to.

  The present invention can be used for an image forming apparatus such as a multifunction peripheral and a copying machine using a stepping motor, a control method for the image forming apparatus, and a control program.

1 is a diagram schematically illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a block diagram illustrating a configuration of a control board of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows an example of the electric current waveform of the stepping motor which concerns on one Example of this invention, (a), (b) is the state which has not generate | occur | produced resonance, (c), (d) It shows the state. It is a figure explaining an example (method to reduce an electric current value) of the control method of the stepping motor which concerns on one Example of this invention. It is a figure explaining an example (method to reduce a pulse rate) of the control method of the stepping motor which concerns on one Example of this invention. It is a figure explaining an example (method to reduce an electric current value in multiple times) of the control method of the stepping motor which concerns on one Example of this invention. It is a figure explaining an example (method to reduce a pulse rate several times) of the control method of the stepping motor which concerns on one Example of this invention. It is a figure explaining an example (method to reduce an electric current value and a pulse rate) of the control method of the stepping motor which concerns on one Example of this invention. It is a flowchart figure which shows the specific procedure (procedure which determines the presence or absence of the vibration of a stepping motor) of the control method of the stepping motor which concerns on one Example of this invention. It is a flowchart figure which shows the specific procedure (procedure which determines the presence or absence of the vibration of a stepping motor) of the control method which concerns on one Example of this invention. It is a flowchart figure which shows the specific procedure (procedure which controls the electric current value of a stepping motor) of the control method which concerns on one Example of this invention. It is a flowchart figure which shows the specific procedure (procedure which controls the pulse rate of a stepping motor) of the control method which concerns on one Example of this invention. It is a flowchart figure which shows the specific procedure (procedure which controls the electric current value and pulse rate of a stepping motor) of the control method which concerns on one Example of this invention. It is a flowchart figure which shows the specific procedure (procedure which controls the electric current value and pulse rate of a stepping motor) of the control method which concerns on one Example of this invention. It is a flowchart figure which shows the specific procedure (judgment of the timing which detects the vibration of a stepping motor) of the control method which concerns on one Example of this invention. It is a flowchart figure which shows the specific procedure (control procedure of a copy operation) of the control method which concerns on one Example of this invention.

Explanation of symbols

1 Image forming device (tandem color printer)
2 Intermediate transfer belt 3a to 3d photoconductor (yellow, magenta, cyan, black)
4a-4d Developer (yellow, magenta, cyan, black)
5a to 5d charging device (yellow, magenta, cyan, black)
6 Exposure equipment (yellow, magenta, cyan, black)
7 Intermediate transfer belt cleaner 8 Paper feed roller 9 Manual paper feed roller 10 Timing roller 11 Secondary transfer roller 12a Fixing roller (heating roller)
12b Fixing roller (pressure roller)
13 Paper discharge roller 14a, 14b Double-side path conveyance roller 15 Waste toner box 16 Recording medium storage unit 17 Color PC motor 18 Main motor 19 Fixing motor 20 Color development motor 21 Development motor 22 Double-side conveyance motor 23 Toner supply motor (for yellow and magenta) )
24 Toner supply motor (for cyan and black)
25a to 25d toner bottles (yellow, magenta, cyan, black)
26a-26d stirring blades (yellow, magenta, cyan, black)
27 Fixing loop sensor 28a to 28d Cartridge (yellow, magenta, cyan, black)
29 Double-sided transport path

Claims (19)

In an image forming apparatus comprising at least a photosensitive member, means for transferring a latent image formed on the photosensitive member to a sheet, and means for feeding and conveying the sheet by a stepping motor,
The current waveform of the stepping motor is detected, and when the degree of variation in the area of each period of the current waveform exceeds a predetermined reference value, it is determined that vibration due to a resonance phenomenon has occurred, and the stepping motor An image forming apparatus comprising: a control unit that changes a driving condition to a condition that does not generate vibration due to a resonance phenomenon.   The image forming apparatus according to claim 1, wherein the driving condition is a current value and / or a pulse rate of the stepping motor. The control unit gradually decreases the current value until the degree of variation in the area becomes equal to or less than the reference value, and drives the stepping motor with a current value where the degree of variation in the area becomes equal to or less than the reference value. The image forming apparatus according to claim 2, wherein a copying operation or a printing operation is performed. Wherein the control unit, the pulse rate up to the degree of variation of the area is less than the reference value stepped down, driving the stepping motor by pulse rate the degree of variation of the area is equal to or less than the reference value The image forming apparatus according to claim 2, wherein a copying operation or a printing operation is performed. The control unit lowers the current value step by step, and when step out occurs before the area variation rate becomes equal to or less than the reference value, after returning the current value to a value at which step out does not occur. The pulse rate is lowered stepwise until the degree of variation in the area becomes equal to or less than the reference value, and the stepping motor is driven at a current value and pulse rate where the degree of variation in the area becomes equal to or less than the reference value. The image forming apparatus according to claim 2, wherein a copying operation or a printing operation is performed. The control unit lowers the current value stepwise, and when a step-out occurs before the degree of variation in the area becomes equal to or less than the reference value, the current value is returned to a value at which no step-out occurs. after one step down the pulse rate, a process in which the degree of variation of the area to determine whether it exceeds the reference value, if the degree of variation of the area exceeds the reference value, the step-out The above process is repeated until the degree of variation in the area becomes equal to or less than the reference value without causing the occurrence of the occurrence of the problem , and the stepping motor is driven at a current value and pulse rate where the degree of variation in the area becomes equal to or less than the reference value. The image forming apparatus according to claim 2, wherein a copying operation or a printing operation is performed.   The current waveform is detected when the power is turned on, when the temperature detected by the temperature sensor in the image forming apparatus exceeds a predetermined threshold, when returning from sleep, when replenishing or replacing consumables, a predetermined number is used. 7. The method according to claim 1, wherein the copying is performed when one or more selected from a time when a predetermined time elapses, a time when the stepping motor is replaced, and the like are selected. Image forming apparatus. The detection of the current waveform is performed during a copying operation or a printing operation. When the degree of variation in the area exceeds the reference value, the copying operation or the printing operation is temporarily interrupted, and the driving condition of the stepping motor is set. The image forming apparatus according to claim 1, wherein the copying operation or the printing operation is restarted after changing to a condition in which vibration does not occur. The control unit acquires a plurality of areas of each period of the current waveform, and calculates a value obtained by dividing a difference between the plurality of areas by one of the plurality of areas as a degree of variation in the area. The image forming apparatus according to claim 1. A control program that operates in the image forming apparatus,
Computer
A control program that functions as the control unit according to claim 1 . A control method for an image forming apparatus, comprising at least a photoconductor, means for transferring a latent image formed on the photoconductor to paper, and means for feeding and transporting the paper by a stepping motor,
The current waveform of the stepping motor is detected, and when the degree of variation in the area of each period of the current waveform exceeds a predetermined reference value, it is determined that vibration due to a resonance phenomenon has occurred, and the stepping motor A control method, characterized in that the drive condition is changed to a condition in which vibration due to a resonance phenomenon does not occur . The control method according to claim 11, wherein the driving condition is a current value and / or a pulse rate of the stepping motor . The current value stepwise lowered to a degree of variation of the area is less than the reference value, the drives the stepping motor by a current value the degree of variation of the area is equal to or less than the reference value, the copying operation or The control method according to claim 12 , wherein a printing operation is performed. The pulse rate is decreased stepwise until the degree of area variation is equal to or less than the reference value , and the stepping motor is driven at a pulse rate where the degree of area variation is equal to or less than the reference value. The control method according to claim 12 , wherein a printing operation is performed. When the step-down occurs before the current value is lowered stepwise and the degree of variation in the area becomes less than or equal to the reference value, the current value is returned to a value at which step-out does not occur , The pulse rate is decreased stepwise until the degree of variation becomes equal to or less than the reference value, and the stepping motor is driven at a current value and pulse rate where the degree of variation in the area becomes equal to or less than the reference value. The control method according to claim 12 , wherein a printing operation is performed. The current value is decreased stepwise, and when step out occurs before the degree of variation in the area falls below the reference value, the current value is returned to a value at which step out does not occur, and the pulse rate is set to 1. After the step down, a process is performed to determine whether the degree of variation in the area exceeds the reference value. When the degree of variation in the area exceeds the reference value, no step-out occurs. The process is repeated until the degree of area variation is equal to or less than the reference value, and the stepping motor is driven at a current value and pulse rate where the degree of area variation is equal to or less than the reference value. The control method according to claim 12 , wherein an operation is performed . The current waveform is detected when the power is turned on, when the temperature detected by the temperature sensor in the image forming apparatus exceeds a predetermined threshold, when returning from sleep, when replenishing or replacing consumables, a predetermined number is used. The method according to any one of claims 11 to 16 , which is performed in a case where one or more selected from among a time when a predetermined time has elapsed, a time when the stepping motor is replaced, and the like are selected . Control method.   The detection of the current waveform is performed during a copying operation or a printing operation. When the degree of variation in the area exceeds the reference value, the copying operation or the printing operation is temporarily interrupted, and the driving condition of the stepping motor is set. The control method according to any one of claims 11 to 16, wherein the copy operation or the print operation is restarted after changing to a condition in which vibration does not occur.   12. A plurality of areas for each period of the current waveform are acquired, and a value obtained by dividing a difference between the plurality of areas by one of the plurality of areas is calculated as a degree of variation in the areas. Control method.

Images