JP6798271B2 - Rotating body control device, transport device, image forming device, rotating body control method, rotating body control program - Google Patents

Description

The present invention relates to a rotating body control device, a transport device, an image forming device, a rotating body control method, and a rotating body control program.

In a conventional image forming apparatus, a mechanism for driving a secondary transfer roller or an intermediate transfer belt by a motor that rotates at a constant speed is known.

In this mechanism, when the surface speed of the intermediate transfer belt and the surface speed of the secondary transfer roller are different, torque interference occurs between the intermediate transfer belt and the secondary transfer roller in order to keep the speeds constant. Since this torque interference affects the driving of the intermediate transfer belt, it can be a factor such as color shift in image formation performed on the intermediate transfer belt.

Therefore, conventionally, for example, the rotation of the secondary transfer roller is such that the fluctuation of the torque of the intermediate transfer drive motor that drives the intermediate transfer belt becomes zero due to the change in the rotation speed of the secondary transfer roller that comes into contact with the intermediate transfer belt. The technique of adjusting the speed is known.

In the above-mentioned conventional technique, one secondary transfer roller is brought into contact with the intermediate transfer belt by one contact / separation mechanism, so that the torque fluctuation of the intermediate transfer drive motor becomes zero. The rotation speed of the transfer roller may be adjusted.

On the other hand, for example, when a plurality of photoconductors are brought into contact with the intermediate transfer belt by one contact / separation mechanism, in order to stabilize the driving of the intermediate transfer belt (rotating body), the plurality of photoconductors It is desirable to adjust the rotation speed independently for each. However, the plurality of photoconductors abut and separate from the intermediate transfer belt at the same time. For this reason, conventionally, it is difficult to adjust the rotation speed of each photoconductor so that the fluctuation of the torque of the intermediate transfer drive motor becomes 0, and it is difficult to sufficiently stabilize the drive of the intermediate transfer belt. there were.

The disclosed technique has been made in view of the above circumstances, and aims to stabilize the driving of the rotating body.

The disclosed technique is a rotating body that controls a first rotating body that is rotationally driven by a first driving source and a plurality of second rotating bodies that are rotationally driven by a plurality of independent second driving sources. A control device in which an operation control unit that simultaneously brings the plurality of second rotating bodies into contact with the first rotating body and the first rotating body and the plurality of second rotating bodies come into contact with each other. In this state, the speed modulation control unit that modulates the rotation speed of each of the plurality of second rotating bodies with different modulation cycles, and the value of the drive torque of the first drive source according to the modulation of the rotation speed. Alternatively, a torque data acquisition unit that acquires fluctuation torque data indicating a fluctuation amount of a value having a proportional relationship with the drive torque value, and a torque data acquisition unit that demolishes the fluctuation torque data for each modulation cycle and a demodulation torque for each modulation cycle. The rotation speed of the second rotating body corresponding to the modulation cycle is calculated by the demodulator for acquiring the data and the rotation speed of the second rotating body when the fluctuation amount becomes the reference value in the demodulation torque data for each modulation cycle. It has a speed calculation unit that sets a target value of the rotation speed in the second drive source corresponding to the rotating body.

The drive of the rotating body can be stabilized.

It is a figure explaining the transport device of 1st Embodiment. It is a figure explaining the interference torque by the contact between a photoconductor and an intermediate transfer belt, and the fluctuation of a surface speed. It is a figure explaining the interference torque by the contact between a secondary transfer motor and an intermediate transfer belt, and the fluctuation of a surface speed. It is a figure explaining the outline of the structure of the image forming apparatus of 1st Embodiment. It is a figure explaining the motor control part of the 1st Embodiment. It is a figure explaining the function of the rotating body control part of 1st Embodiment. It is a figure explaining the demodulation part of 1st Embodiment. It is a flowchart explaining the process of the speed adjustment part of 1st Embodiment. It is a figure explaining the process of the speed adjustment part of the 1st Embodiment. It is a figure explaining the function of the rotating body control part of the 2nd Embodiment. It is a flowchart explaining the process of the speed adjustment part of the 2nd Embodiment. It is a figure explaining the motor control part when the current command value is used. It is a figure explaining the motor control part when the measured current value is used. It is a figure explaining the motor control part when the PWM measured value is used. It is a figure explaining the motor control part when the measured torque value is used.

In the following embodiment, in a configuration in which a plurality of independently driven rotating bodies are simultaneously separated / contacted with one rotating body by one common separation mechanism, each of the plurality of rotating bodies and one rotating body are used. Interference torque generated between and is generated to stabilize the drive of one rotating body. In the following description, a photoconductor is shown as an example of a plurality of rotating bodies, and an intermediate transfer belt is shown as an example of one rotating body.
(First Embodiment)
The first embodiment will be described below with reference to the drawings. FIG. 1 is a diagram illustrating a transfer device according to the first embodiment.

The transport device 100 shown in FIG. 1 transports, for example, a sheet-shaped recording medium, and is mounted on an image forming device or the like described later. FIG. 1 (A) shows an outline of the configuration of the transport device, FIG. 1 (B) shows the configuration around the secondary transfer unit, and FIG. 1 (C) shows the periphery of the primary transfer unit. The configuration of is shown.

The transfer device 100 of the present embodiment includes an intermediate transfer belt 10, an intermediate transfer roller 11, a secondary transfer opposed roller 12, a driven roller 13, a tension roller 14, a belt cleaning device 15, and a scale sensor 16. An encoder pattern 17 is formed on the intermediate transfer belt 10.

Further, the transfer device 100 of the present embodiment includes an intermediate transfer motor 21, roller encoders 22, 33, 44, motor encoders 34, 45, secondary transfer rollers 31, secondary transfer motor 32, photoconductors 19C, 19M, 19Y, and the like. It has 19K, photoconductor drive motors 42C, 42M, 42Y, 42K, transfer rollers 20C, 20M, 20Y, 20K. In the following description, when each of the photoconductors 19C, 19M, 19Y, and 19K is not distinguished, it is referred to as the photoconductor 19. Further, in the following description, when the transfer rollers 20C, 20M, 20Y, and 20K are not distinguished from each other, they are referred to as transfer rollers 20. Further, in the following description, when the photoconductor drive motors 42C, 42M, 42Y, and 42K are not distinguished from each other, they are referred to as a photoconductor drive motor 42.

Further, the transfer device 100 of the present embodiment has a motor control unit 200 that controls to keep the surface speed of the intermediate transfer belt 10 constant.

In the present embodiment, the intermediate transfer belt 10 is the first rotating body, and the photoconductor 19 is the second rotating body.

In the transfer device 100 of the present embodiment, the intermediate transfer belt 10 is stretched by a plurality of tension rollers arranged in the belt loop, and is driven by rotation of the intermediate transfer roller 11 which is one of the tension rollers. It can be moved endlessly. The intermediate transfer roller 11 is connected to the intermediate transfer motor 21 as a drive source via a reduction mechanism. This speed reduction mechanism has a configuration in which a small-diameter gear on the rotating shaft of the intermediate transfer motor 21 and a large-diameter gear on the rotating shaft of the intermediate transfer roller 11 are meshed with each other.

In the present embodiment, there is a belt encoder method as a speed detecting means for detecting the surface speed of the intermediate transfer belt 10. An encoder pattern 17 is engraved on the front surface or the back surface of the intermediate transfer belt 10 of the present embodiment, and the surface speed of the intermediate transfer belt 10 is detected by reading the encoder pattern 17 with the scale sensor 16.

In the example of FIG. 1, the scale sensor 16 is installed at the center of the driven roller 13 and the intermediate transfer roller 11, but the present invention is not limited to this. If the scale sensor 16 is installed on a flat portion, the surface velocity of the intermediate transfer belt 10 can be measured correctly. For example, when the scale sensor 16 is installed on an uneven rotating shaft or the like, the curvature of the shaft has an effect, and the spacing between the encoder patterns 17 is increased due to changes in the manufacturing thickness of the intermediate transfer belt 10 and changes in the environment. It will change and the surface speed will not be correct and should be avoided.

The encoder pattern 17 may be manufactured by any method, such as attaching a sheet-shaped encoder pattern, processing the pattern directly on the intermediate transfer belt 10, or integrally processing the encoder pattern 10 in the manufacturing process.

In the present embodiment, the scale sensor 16 assumes a reflection type optical sensor having slits at equal intervals, but the scale sensor 16 is not limited to this. The sensor may be any sensor that can accurately detect the surface position of the intermediate transfer belt 10 from the encoder pattern 17, and may detect the surface position by image processing using, for example, a CCD camera or the like. Further, if it is a Doppler method or a sensor method that can detect the surface position by image processing from the unevenness of the belt surface, the encoder pattern 17 can be eliminated.

Further, as another speed detecting means for detecting the surface speed of the intermediate transfer belt 10, there is a rotary encoder system. This method is a rotation detector provided on the rotation shaft of the driven roller 13. The driven roller 13 is a roller that rotates driven by the endless movement of the intermediate transfer belt 10, and can detect the surface speed of the intermediate transfer belt 10.

In the transfer device 100, of the entire area of the intermediate transfer belt 10 in the circumferential direction, the portions after passing through the hanging position with respect to the driven roller 13 and before entering the hanging position with respect to the intermediate transfer roller 11 are M, C. , Y, K photoconductors 19 to form primary transfer nip for M, C, Y, K. The transfer rollers are in contact with the positions where the primary transfer nips for M, C, Y, and K are formed in the intermediate transfer belt 10 from the back surface side of the intermediate transfer belt 10. In the transfer device 100, a transfer bias is applied to each transfer roller by a power source, and a transfer electric field is formed between the intermediate transfer belt 10 and the photoconductor 19 at the primary transfer nip of each color.

In the transfer device 100, since a color image is formed at the primary transfer portion, it is preferable to detect and control the surface velocity of the intermediate transfer belt 10 at this portion. Therefore, it is desirable to install a rotary encoder on the driven roller 13 or to install a scale sensor 16 between the driven roller 13 and the intermediate transfer roller 11.

The tension roller 14 of the present embodiment is pressed against the belt from the outside of the belt loop to generate a constant belt tension. Due to the belt tension generated by the tension roller 14, the intermediate transfer belt 10 comes into contact with the surface of each tension roller, and the intermediate transfer belt 10 is conveyed in the circumferential direction. In particular, the contact force between the surface of the driven roller 13 and the intermediate transfer belt 10 is important because it correlates with the belt transport friction force of the driven roller 13, and the transport friction force required to transport the intermediate transfer belt 10 is The pressing force of the tension roller 14 is set so as to be secured.

Further, in the transfer device 100, a secondary transfer roller 31 that comes into contact with the surface of the intermediate transfer belt 10 at a position facing the secondary transfer opposed roller 12 is arranged, and the secondary transfer roller 31 and the intermediate transfer belt 10 are arranged. By applying an electric charge to the surface of the surface, the recording paper is adsorbed on the surface.

Further, in the transfer device 100, the belt cleaning device 15 arranged on the outside of the belt loop and downstream of the secondary transfer roller 31 in the belt transfer direction is in contact with the intermediate transfer belt 10. The belt cleaning device 15 collects foreign matter such as toner adhering to the surface of the intermediate transfer belt 10 from the surface of the intermediate transfer belt 10 by the potential difference between the toner and itself.
The motor control unit 200 of the present embodiment feedback-controls the intermediate transfer motor 21 in order to keep the surface speed of the intermediate transfer belt 10 constant.

Specifically, the motor control unit 200 is based on the output signal S1 of the scale sensor 16 indicating the surface speed of the intermediate transfer belt 10 and the output signal S2 of the roller encoder 22 indicating the rotation speed of the intermediate transfer roller 11. The drive control signal S3 of the intermediate transfer motor 21 is output.

Further, the motor control unit 200 feedback-controls the secondary transfer motor 32 in order to suppress fluctuations in the surface speed of the intermediate transfer belt 10 due to the influence of the recording medium passing through the secondary transfer unit 50. Specifically, the motor control unit 200 outputs the drive control signal S4 of the secondary transfer motor 32 based on the output signal S1 of the scale sensor 16 and the output signal S2 of the roller encoder 22.

Further, the motor control unit 200 controls contact and separation between the secondary transfer roller 31 and the secondary transfer opposed roller 12.

Next, the mechanism around the secondary transfer roller 31 will be described (see FIG. 1 (B)). In the transfer device 100, a secondary transfer motor 32 is installed separately from the intermediate transfer motor 21. The secondary transfer motor 32 is rotated by the drive control signal S4 transmitted from the motor control unit 200.

The secondary transfer motor 32 employs the same brushed DC motor or brushless DC motor as the intermediate transfer motor 21. The rotation speed of the secondary transfer motor 32 is reduced by a reduction mechanism (motor gear and reduction gear on the secondary transfer roller 31 side). Further, the secondary transfer roller 31 conveys the recording medium conveyed to the secondary transfer unit 50 by its rotation.

On the opposite side of the secondary transfer roller 31, there is a secondary transfer opposed roller 12 that supports the intermediate transfer belt 10, and the secondary transfer roller 31 is placed on the secondary transfer opposed roller 12 with the intermediate transfer belt 10 interposed therebetween. Abut / separate.

The contact between the two rollers is done by a spring. Further, the secondary transfer roller 31 also has a cam mechanism that can move in the direction of the arrow Y in the drawing for separating from the secondary transfer opposed roller 12, and causes contact between the two rollers in the secondary transfer unit 50. The separation is switched.

In the transfer device 100 of the present embodiment, an elastic layer is provided on the surface portion of the secondary transfer roller 31 in order to improve the transferability of the secondary transfer unit 50. As an example of the secondary transfer roller 31, a low-hardness rubber material roller portion (elastic rubber layer) such as silicon rubber is provided around a low-inertity thin-walled metal pipe, and the secondary transfer roller 31 is composed of a urethane coating layer applied to the surface layer thereof. ..

In the secondary transfer roller 31 of the present embodiment, the conductive rubber roller portion is composed of vulcanized rubber or silicon-based rubber having a rubber hardness of 40 ° (rubber hardness A scale) or less as a lower layer, and the surface layer thereof has no viscosity. The urethane coating layer to be used may be provided as a thin layer. In the present embodiment, this makes it possible to expand the nip region by abutment deformation of the conductive rubber roller portion and to secure an appropriate transfer pressure.

Generally, when trying to achieve a low hardness of 40 ° or less by a method other than the foam rubber structure, in the case of vulcanized rubber, the viscosity increases due to the addition of a plasticizer. In addition, silicon rubber also has high viscosity. As a result, poor movement of both moving bodies occurs due to adhesion at the pressure contact portion 51 where the intermediate transfer belt 10 and the secondary transfer roller 31 are in contact with each other, or adhesion with the portion in contact with the recording medium. In order to avoid this, the urethane coating applied to the surface layer described above is effective.

The intermediate transfer motor 21 is controlled by the motor control unit 200 so that the surface speed of the intermediate transfer belt 10 is constant.

Next, the driving mechanism of the photoconductor 19 will be described (see FIG. 1C). The peripheral configurations of the photoconductors 19C, 19M, 19Y, and 19K are the same.

In FIG. 1C, taking the drive system of the photoconductor 19K for K as an example, this has the following configuration.

In the transfer device 100, a photoconductor drive motor 44K is installed separately from the intermediate transfer motor 21. The photoconductor drive motor 44K is rotated by the photoconductor drive motor signal S5 transmitted from the motor control unit 200. The photoconductor drive motor 44K employs the same brushed DC motor and brushless DC motor as the intermediate transfer motor 21. The rotation speed of the photoconductor drive motor 44K is decelerated by the reduction mechanism (motor gear and reduction gear on the photoconductor drive roller side), and the toner image is transferred onto the intermediate transfer belt 10 by the rotation of the photoconductor 19K connected to the reduction mechanism. I do.

The drive mechanism of the photoconductor 19 has a separation mechanism for separating the transfer roller 20 from the photoconductor 19 for each of C, M, Y, and K, so that the photoconductor 19 and the transfer roller 20 are in contact with each other and in a separated state. Can be switched.

The transfer roller 20 follows the rotation of the intermediate transfer belt 10 and the photoconductor 19. In the present embodiment, by separating the photoconductor 19 and the transfer roller 20, the intermediate transfer belt 10 can be taken out and the deterioration of the photoconductor 19 can be suppressed.

The separation mechanism is one mechanism shared by the transfer rollers 20C, 20M, 20Y, and 20K. The photoconductors 19C, 19M, 19Y, and 19K are brought into contact with the intermediate transfer belt 10 when the separating mechanism brings the transfer rollers 20C, 20M, 20Y, and 20K into contact with the intermediate transfer belt 10 at the same time. Further, the photoconductors 19C, 19M, 19Y and 19K are separated from the intermediate transfer belt 10 when the separation mechanism simultaneously separates the transfer rollers 20C, 20M, 20Y and 20K from the intermediate transfer belt 10.

That is, the separation mechanism of the present embodiment is commonly used when abutting / separating the photoconductors 19C, 19M, 19Y, 19K and the intermediate transfer belt 10.

The recording medium conveyed by the transfer device 100 of the present embodiment may be, for example, paper, a sheet-like film, or the like. The recording medium of the present embodiment transfers an image. Anything can be used as long as it can be transported by the transport device 100.

The interference torque generated between the secondary transfer motor 32 and the intermediate transfer motor 21 will be described below with reference to FIGS. 2 and 3.

FIG. 2 is a diagram for explaining the interference torque due to the contact between the photoconductor and the intermediate transfer belt and the fluctuation of the surface speed. FIG. 2A shows a case where each of the photoconductor 19 and the intermediate transfer belt 10 is driven at a constant rotation speed with the photoconductor 19 and the intermediate transfer belt 10 separated from each other. FIG. 2B shows a case where the photoconductor 19 is driven at a constant rotation speed while being in contact with the intermediate transfer belt 10.

The rotation speed of the intermediate transfer motor 21 is feedback-controlled based on the surface speed V1 of the intermediate transfer belt 10 obtained from the scale sensor 16 so that the surface speed V1 becomes a target value. Therefore, the surface velocity V1 of the intermediate transfer belt 10 is always constant.

Further, since the photoconductor 19 is feedback-controlled based on the rotation speed obtained from the motor encoder 45, the rotation speed Vs of the rotation axis of the photoconductor 19 is always constant. At this time, the rotation speed Vs is controlled so as to match the surface speed V1 of the intermediate transfer belt 10.

However, the surface speed of the photoconductor 19 does not match that of the intermediate transfer belt 10 due to the roller diameter tolerance. Further, when the photoconductor 19 and the intermediate transfer belt 10 are in contact with each other, the surface speed changes greatly depending on the amount of deformation, so that there is a speed difference between the surface speed of the photoconductor 19 and the surface speed V1 of the intermediate transfer belt 10.

For example, as shown in FIG. 2A, when the photoconductor 19 is separated from the intermediate transfer belt 10 and each is controlled to a specified speed, the intermediate transfer motor 21 and the photoconductor drive motor 42 are subjected to, respectively. Torque to drive by itself is generated.

At this time, the drive torque generated in the intermediate transfer motor 21 is Ta, and the drive torque generated in the photoconductor drive motor 42 is Tb.

Here, as shown in FIG. 2B, when the photoconductor 19 comes into contact with the intermediate transfer belt 10, if the rotation speed of the photoconductor 19 is constant, the surface speed of the photoconductor 19 is affected by a tolerance or the like. V2 changes.

Here, since feedback control is performed to maintain a constant speed between the photoconductor 19 and the intermediate transfer belt 10, if there is a difference between the surface speed V2 of the photoconductor 19 and the surface speed V1 of the intermediate transfer belt 10, Interference torque is generated.

The interference torque of the present embodiment is a torque component that the photoconductor drive motor 42 bears to rotate the intermediate transfer belt 10. Alternatively, the interference torque of the present embodiment is a torque component that the intermediate transfer motor 21 bears to rotate the photoconductor 19.

FIG. 2B shows a state in which the photoconductor 19 side maintains a surface speed V2 faster than the intermediate transfer belt 10, and the intermediate transfer belt 10 side maintains a surface speed V1 slower than the photoconductor 19.

In this state, the drive torque Ta of the intermediate transfer motor 21 increases due to the interference torque on the intermediate transfer belt 10 side, and the drive torque Tb of the photoconductor drive motor 42 decreases due to the interference torque on the photoconductor 19 side.

The above-mentioned interference torque caused by the difference between the surface velocities of the rotating bodies is a phenomenon that occurs in a pair of two rotating bodies having different drive sources.

That is, this phenomenon is a phenomenon that occurs between each of the photoconductors 19C, 19M, 19Y, and 19K and the intermediate transfer belt 10.

Therefore, in the present embodiment, the rotation speeds of the photoconductor drive motors 44C, 44M, 44Y, and 44K are set so that the surface speeds of the photoconductors 19C, 19M, 19Y, and 19K match the surface speeds of the intermediate transfer belt 10. Control.

FIG. 3 is a diagram for explaining the interference torque due to the contact between the secondary transfer motor and the intermediate transfer belt and the fluctuation of the surface speed.

FIG. 3 shows the relationship between the surface speed and the interference torque of the two rotating bodies as an example of the pair of the intermediate transfer belt 10 and the secondary transfer roller 31 of the two rotating bodies having different drive sources.

In FIG. 3, the horizontal axis represents the fluctuation of the speed of the secondary transfer roller 31, and the vertical axis represents the carrying force.

In FIG. 3, the fluctuation of the speed of the secondary transfer roller 31 is shown as a percentage [%] of the fluctuation of the speed with respect to the set speed of the secondary transfer roller 31. The set speed is a value assumed that the surface speed of the secondary transfer roller 31 matches the surface speed of the intermediate transfer belt 10. Actually, the surface speed of the secondary transfer roller 31 does not reach the set speed due to the paper type, roller tolerance, contact pressure fluctuation, environment, aging, and the like.

The transfer force is the drive torque Ta [Nm] of the intermediate transfer motor 21 estimated in consideration of the design values such as the roller diameter of the secondary transfer roller 31 and the intermediate transfer motor 21, and the transfer force [N] of the intermediate transfer motor 21. ] Is a numerical value converted to. The drive torque Ta of the intermediate transfer motor 21 is the drive torque of the intermediate transfer belt 10, and the transfer force of the intermediate transfer motor 21 is the transfer force of the intermediate transfer belt 10.

The transfer force of the secondary transfer motor 32 is a value obtained by converting the drive torque Ta of the secondary transfer motor 32 estimated in consideration of the reduction ratio, the diameter of the secondary transfer roller 31, and the like into a transfer force.

In the present embodiment, in order to express the drive torque of the intermediate transfer belt 10 and the drive torque of the secondary transfer motor 32 on the same axis, they are converted into transfer force for convenience.

The estimated drive torque value in this embodiment is a torque value calculated based on the PWM command value to the motor and the actual rotation speed. In a state where each motor is accurately controlled to a constant speed or a predetermined speed, the torque value can be calculated only from the current value or the PWM command value.

The interference torque shown in FIG. 3 will be described below. The line L1 shown in FIG. 3 shows the relationship between the rotational speed of the secondary transfer roller 31 and the transport force of the secondary transfer roller 31. The line L2 shown in FIG. 3 shows the relationship between the rotational speed of the secondary transfer roller 31 and the transfer force of the intermediate transfer motor 21.

In the present embodiment, the transfer force of the intermediate transfer motor 21 and the transfer force of the secondary transfer motor 32 in a state where no interference torque is generated (see FIG. 2A) are set to “0” (reference), respectively.

Here, consider a state in which the intermediate transfer belt 10 and the secondary transfer roller 31 are passed through with their respective feedback controlled to a constant rotation speed. At this time, the surface speed V2 of the secondary transfer roller 31 does not match the surface speed V1 of the intermediate transfer belt 10 due to factors such as paper thickness. For example, when the paper passed through the secondary transfer roller 31 is thick and the value of the surface speed V2 of the secondary transfer roller 31 becomes large, the torque Tb of the secondary transfer motor 32 increases, and the intermediate transfer motor 21 Drive torque Ta is reduced.

As described above, it can be seen that the transfer force L1 of the secondary transfer roller 31 and the transfer force L2 of the intermediate transfer motor 21 have an inverse correlation.

In the present embodiment, the rotation speed of the secondary transfer roller 31 is controlled so that the drive torque Ta of the intermediate transfer motor 21 always becomes the reference value T0 when the intermediate transfer motor 21 is driven alone. Therefore, in the example of FIG. 3, the rotation speed Vs of the secondary transfer roller 31 when the value of the transport force L2 of the intermediate transfer motor 21 becomes 0 is set as the target value of the rotation speed of the secondary transfer roller 31. It is the optimum value.

In other words, in the present embodiment, the rotation speed of the secondary transfer motor 32 when the value of the transport force L2 of the intermediate transfer motor 21 becomes 0 is set as the optimum value of the rotation speed of the secondary transfer motor 32. Is the value of. For example, in the example of FIG. 3, the speed at which the rotation speed of the secondary transfer roller 31 is changed by about 0.2% from the set speed is the target value of the rotation speed of the secondary transfer roller 31.

This relationship of interference torque due to the difference in surface speed can also be applied between the photoconductors 19C, 19M, 19Y, and 19K and the intermediate transfer belt 10.

Next, each device of this embodiment will be described. FIG. 4 is a diagram illustrating an outline of the configuration of the image forming apparatus of the first embodiment.

The image forming apparatus 300 of the present embodiment is an electrophotographic system, preferably includes a digital multifunction device, and has a copying function, a printer function, a facsimile function, and the like. However, the image forming apparatus 300 may be an inkjet method, a sublimation type thermal transfer method, or a dot impact type image forming apparatus 300 that ejects ink droplets to form an image. The image forming apparatus 300 of this embodiment includes a conveying apparatus 100.

The image forming apparatus 300 of the present embodiment includes an image reading unit 301, an image writing unit 302, a photoconductor unit 303, a photoconductor 19, a developing unit 305, an intermediate transfer unit 306, an intermediate transfer belt 10, a secondary transfer unit 50, and a resist. It has a unit 60, a tray 307, a transport unit 308, and a fixing unit 309.

The image forming apparatus 300 scans the document while irradiating the document with a light source by the image reading unit 301, and reads the image by the 3-line CCD (Charge Coupled Device) sensor for the reflected light from the document. The read image is sent to the image writing unit 302 after being subjected to image processing such as scanner γ correction, color conversion, image separation, and gradation correction processing by the image processing unit.

The image writing unit 302 modulates the drive of the LD (Laser Diode) according to the image data. In the photoconductor unit 303, an electrostatic latent image is written on a uniformly charged rotating photoconductor 19 by a laser beam from an LD, and toner is adhered by the developing unit 305 to visualize the photoconductor unit 303.

The image formed on the photoconductor 19 is transferred onto the intermediate transfer belt 10 of the intermediate transfer unit of the intermediate transfer unit 306. When full-color copying is executed in the image forming apparatus 300, toner images of four colors (black, cyan, magenta, and yellow) are sequentially superimposed on the intermediate transfer belt 10. When the image formation and transfer of all colors are completed, the registration unit 60 supplies the recording medium from the tray 307 at the same timing as the intermediate transfer belt 10, and the secondary transfer unit 50 transfers the recording medium from the intermediate transfer belt 10 to the recording medium. The toner image is secondarily transferred. The recording medium on which the toner image is transferred is sent to the fixing unit 309 via the conveying unit 308, and is discharged after the toner image is fixed on the recording medium by the fixing roller and the pressure roller.

FIG. 5 is a diagram illustrating a motor control unit of the first embodiment.

The motor control unit 200 of the present embodiment is included in the transfer device 100, and controls the drive of a plurality of rotating bodies (intermediate transfer roller 11, secondary transfer roller 31, photoconductor 19) shown in FIG. .. Further, in the present embodiment, in particular, the motor control unit 200 determines a target value of the rotation speeds of the photoconductors 19C, 19M, 19Y, and 19K capable of suppressing torque interference with the intermediate transfer motor 21.

In the image forming apparatus 300 of the present embodiment, the motor control unit 200 is connected to the main control unit 310 that controls the entire image forming apparatus 300, and is exposed to the rotational speed of the intermediate transfer motor 21 and the secondary transfer motor 32. It controls the rotation speed of the body drive motor 42.

When an image data output instruction or the like is operated from the operation unit 320 of the image forming apparatus 300, the main control unit 310 gives a drive instruction for each motor to the motor control unit 200. Specifically, when the main control unit 310 receives an image data output instruction or the like, the main control unit 310 instructs the motor control unit 200 of a command value for each motor, a start / stop instruction, a target value of the rotation speed, a rotation direction, and the like. The motor control unit 200 controls the drive of each motor in response to this instruction. In addition, the main control unit 310 exchanges information about each motor with the motor control unit 200. Further, the main control unit 310 has a memory 330 for storing information (motor information) about each motor. The information about the motor includes, for example, the rotation speed (set speed) of each motor, the PWM value according to the command value, the drive current, the encoder value, and the like.

The motor control unit 200 of the present embodiment includes a rotating body control unit 210, drivers 221, 222, 223, and FETs 231 and 232, 233.

Although the details will be described later, the rotating body control unit 210 adjusts the target value of the rotation speed of the secondary transfer motor 32 and the target value of the rotation speed of the photoconductor drive motor 42, and stores each target value after the adjustment. Store in 330. The rotation speed of the secondary transfer motor 32 is synonymous with the rotation speed of the secondary transfer roller 31, and the rotation speed of the photoconductor drive motor 42 is synonymous with the rotation speed of the photoconductor 19.

The driver 221 and the FET 231 have a function of supplying a constant drive current to the intermediate transfer motor 21. The driver 222 and the FET 232 have a function of supplying a constant drive current to the secondary transfer motor 32. The driver 223 and the FET 233 have a function of supplying a constant drive current to the photoconductor drive motor 42.

The rotating body control unit 210 acquires the surface speed of the intermediate transfer belt 10 and the rotation speed of the intermediate transfer motor 21 from the roller encoder 22 and the scale sensor 16 of the intermediate transfer roller 11. Further, the rotating body control unit 210 acquires the rotation speeds of the secondary transfer motor 32 and the secondary transfer roller 31 from the motor encoder 34 and the roller encoder 33. Further, the rotating body control unit 210 acquires the rotation speeds of the photoconductor drive motor 42 and the photoconductor 19 from the motor encoder 45 and the roller encoder 44.

Further, the rotating body control unit 210 acquires the drive currents of the intermediate transfer motor 21, the secondary transfer motor 32, and the photoconductor drive motor 42, calculates the control output to each motor, and calculates the control output to each motor, and the PWM command value corresponding to the control output. Is output to each driver.

Specifically, the rotating body control unit 210 calculates the drive current of each motor based on the PWM command value. However, an error may occur due to the influence of fluctuations and responsiveness of the motor drive circuit including the driver. Therefore, in order to grasp the drive current of the motor with higher accuracy, the rotating body control unit 210 may measure the current of the FET and grasp the drive current. Specifically, the rotating body control unit 210 may grasp the drive current from the combined current value flowing through the shunt resistors connected to the FETs 231 to 233.

The PWM command value output at this time is for bringing the surface speed of the intermediate transfer belt 10 acquired by the rotating body control unit 210 and the rotation speeds of the secondary transfer roller 31 and the photoconductor 19 closer to the target values. Is the value of.

When the PWM command value is input, the drivers 221, 222, and 223 recognize the rotation angles of each motor (21, 32, 42) by the Hall element signal. Then, each driver converts the PWM signal generated according to the PWM command value into a motor three-phase output signal, and drives each motor via the FETs 231 and 232, 233.

By the above operation, the rotating body control unit 210 of the present embodiment brings the rotation speeds of the intermediate transfer motor 21, the secondary transfer motor 32, and the photoconductor drive motor 42 closer to the target values based on the command values of each motor. Can be controlled.

Further, the rotating body control unit 210 calculates the drive torque from the acquired drive current. Specifically, the rotating body control unit 210 acquires the rotational speed and drive current of each of the motors 21, 32, 42 (or each of the rollers 11, 31, 41), and shows the relationship between the torque multiplier and the speed. Convert the drive current into torque using a conversion table or the like.

Further, the rotating body control unit 210 stores the data acquired by the rotating body control unit 210, the calculated data, and the like in the memory 330, and notifies the main control unit 310 of information such as an abnormality notification, if necessary. To do. Incidentally, the memory 330 may be configured to be included in the rotating body control unit 210 as well.

As described above, in the present embodiment, the rotating body control unit 210 functions as a part of the rotating body control device that controls the driving of three or more rotating bodies.

Next, the function of the rotating body control unit 210 will be described with reference to FIG. FIG. 6 is a diagram illustrating the function of the rotating body control unit of the first embodiment.

The rotating body control unit 210 of the present embodiment is, for example, an arithmetic processing unit containing a memory or the like, and each unit of the rotating body control unit 210 described later executes a rotating body control program in which the arithmetic processing unit is stored in the memory. It is realized by doing.

The rotating body control unit 210 of the present embodiment includes an operation control unit 240, a paper passing detection unit 245, an intermediate transfer control unit 250, a secondary transfer control unit 260, a photoconductor control unit 270C, 270M, 270Y, 270K, and a speed adjustment unit. It has 280C, 280M, 280Y and 280K.

The operation control unit 240 controls the operation of separation and pressure welding between the secondary transfer roller 31 and the secondary transfer opposed roller 12. Further, the operation control unit 240 of the present embodiment controls the operation of separation and pressure welding between the photoconductor 19 and the transfer roller 20.

The paper passing detection unit 245 detects that the recording medium has reached or passed through the secondary transfer unit 50.

The intermediate transfer control unit 250 has a speed control unit 251, and the speed control unit 251 controls the surface speed of the intermediate transfer belt 10 as a target value. Specifically, the speed control unit 251 acquires the rotation speed of the intermediate transfer motor 21, and performs feedback control so that this rotation speed becomes a target value of the surface speed of the intermediate transfer belt 10 included in the motor information. ..

The secondary transfer control unit 260 has a speed control unit 261, and the speed control unit 261 controls the rotation speed of the secondary transfer motor 32 as a target value. Specifically, the speed control unit 261 acquires the rotation speed of the secondary transfer motor 32, and feeds back the rotation speed so that it becomes the target value of the rotation speed of the secondary transfer motor 32 included in the motor information. Take control.

Each of the photoconductor control units 270C, 270M, 270Y, and 270K has speed control units 271C, 271M, 271Y, and 271K, and each speed control unit 271 causes the rotation speeds of the photoconductor drive motors 42C, 42M, 42Y, and 42K. Is controlled with the target value. Specifically, each speed control unit 271 acquires the rotation speed of each photoconductor drive motor 42, and the rotation speed becomes a target value of the rotation speed of each photoconductor drive motor 42 included in the motor information. In addition, feedback control is performed. Further, each speed control unit 271 controls the rotation speed of each photoconductor drive motor 42 in response to a speed change instruction from the speed adjustment units 280C, 280M, 280Y, and 280K. In the following description, when the photoconductor control unit 270C, 270M, 270Y, 270K and the speed control unit 271C, 271M, 271Y, and 271K are not distinguished, they are referred to as a photoconductor control unit 270 and a speed control unit 271.

The speed adjusting units 280C, 280M, 280Y, and 280K each adjust the target value of the rotation speed of each photoconductor drive motor 42 so that the intermediate transfer belt 10 does not interfere with each photoconductor 19. ..

The speed adjusting units 280C, 280M, and 280Y will be described below. The speed adjusting units 280C, 280M, and 280Y have the same configuration, and when they are not distinguished, they are referred to as speed adjusting units 280. In this embodiment, the photoconductor 19K and the speed adjusting unit 280K corresponding to the photoconductor 19K are not provided, but the present embodiment is not limited to this. The speed adjusting unit 280 may be provided on all the photoconductors in contact with the intermediate transfer belt 10.

The speed adjustment unit 280 of the present embodiment includes a reference value setting unit 281, a speed modulation control unit 282, a torque data acquisition unit 283, a demodulation unit 284, and a speed calculation unit 285.

The speed adjusting unit 280 of the present embodiment changes the speed of each photoconductor 19 in a predetermined cycle in a state where each photoconductor 19 is in contact with the intermediate transfer belt 10, and drives torque of the intermediate transfer motor 21 at that time. Acquire data showing the fluctuation of Ta. Then, the speed adjustment unit 280 demodulates the data indicating the fluctuation of the drive torque for each frequency component of the speed modulation for each photoconductor 19, and based on the demodulated frequency component and the reference value T0 of the drive torque Ta, the photosensitivity is exhibited. The target value of the rotation speed for each body drive motor 42 is calculated.

The reference value setting unit 281 of the present embodiment sets the reference value T0 of the drive torque Ta of the intermediate transfer motor 21. The reference value T0 of the drive torque Ta is a value of the drive torque Ta that is a reference when calculating the rotation speed of each photoconductor drive motor 42 from the data indicating the fluctuation of the drive torque Ta. In the following description, the data indicating the fluctuation of the drive torque Ta is referred to as the fluctuation torque data.

The speed modulation control unit 282 abuts each transfer roller 20 with the intermediate transfer belt 10 to bring each photoconductor 19 into contact with the intermediate transfer belt 10, and in this state, sets the rotation speed (rotation frequency) of each photoconductor 19. Modulate periodically. At this time, the speed modulation control unit 282 of the present embodiment changes the rotation speed of each photoconductor 19 in different modulation cycles so that the speed modulation component of each photoconductor 19 can be separated in the orthogonal detection approximation.

Further, the speed modulation control unit 282 of the present embodiment starts changing the rotation speed of each photoconductor 19 at the same timing.

For example, when the rotation frequency of each photoconductor 19 is 1.5 [Hz], the speed modulation control unit 282 sets the rotation frequency of the photoconductor 19C to 3.0 [Hz] and sets the rotation frequency of the photoconductor 19M. It is set to 6.0 [Hz], and the rotation frequency of the photoconductor 19Y is set to 12.0 [Hz]. In the present embodiment, the rotation frequency of the photoconductor 19K is not changed, but the rotation frequency is not limited to this, and the rotation frequency of the photoconductor 19K may be changed.

Orthogonal detection approximation is a calculation by cumulative addition. Therefore, by setting the modulation cycle of the rotation speed to an integral multiple of one cycle of the rotation frequency of the photoconductor 19, it is possible to remove the speed fluctuation component due to the eccentricity of one rotation of the photoconductor 19. Further, in the present embodiment, the modulation period is set to a value of 2 to the nth power (n ≧ 1).

That is, in the speed modulation control unit 282 of the present embodiment, the modulation cycle of the rotation speed of the photoconductor 19 is an integral multiple of one cycle of the rotation frequency of the photoconductor 19, and 2 to the nth power (n ≧ 1). The value of. In the present embodiment, by doing so, when the torque data acquisition unit 283, which will be described later, acquires the variable torque data, the sampling time can be made uniform in each cycle, and the accuracy is improved.

The sampling time is a common multiple of the modulation period of the rotation speed of each photoconductor 19. In the present embodiment, by sampling in this way, highly accurate fluctuation torque data can be obtained by removing the speed fluctuation component due to the eccentricity of one rotation of each photoconductor 19.

Further, the speed modulation control unit 282 of the present embodiment has a smaller rotation frequency and a larger amplitude as the photoconductor 19 is farther from the intermediate transfer roller 11. Specifically, the rotation frequency was set to be photoconductor 19Y <photoreceptor 19M <photoreceptor 19C, and the amplitude was set to photoconductor 19Y ≥ photoconductor 19M ≥ photoconductor 19C.

In the present embodiment, by setting the rotation frequency and the amplitude in this way, the difference in the method of transmitting the driving force of the intermediate transfer motor 21 to each photoconductor 19 has an effect on the driving torque Ta of the intermediate transfer motor 21. The effect is suppressed.

In the present embodiment, the fluctuation of the rotation speed of the photoconductor 19C located closest to the intermediate transfer motor 21 is more interference torque than the fluctuation of the rotation speed of the photoconductor 19Y located farthest from the intermediate transfer motor 21. Is likely to occur. That is, the interference torque due to the fluctuation of the rotation speed of the photoconductor 19Y is less likely to appear and is more difficult to detect than the interference torque due to the fluctuation of the rotation speed of the photoconductor 19C.

In this embodiment, in consideration of these matters, the rotation frequency is set to the photoconductor 19Y <photoreceptor 19M <photoreceptor 19C, and the amplitude is set to the photoconductor 19Y ≥ photoconductor 19M ≥ photoconductor 19C. It is possible to detect the generation of interference torque due to fluctuations in each rotation speed.

The torque data acquisition unit 283 acquires the value of the drive torque Ta of the intermediate transfer motor 21 when the rotation speed of the photoconductor 19 is fluctuating (modulating) by the speed modulation control unit 282. In other words, the torque data acquisition unit 283 acquires fluctuation torque data, which is data indicating fluctuations in the drive torque Ta according to the modulation of the rotation speed of the photoconductor 19.

Specifically, the drive torque Ta of the present embodiment is calculated based on the PWM command value output from the intermediate transfer control unit 250 to the driver 221 and the rotation speed of the intermediate transfer motor 21 obtained from the scale sensor 16. Load torque value. The drive torque Ta can be calculated from the current value supplied to the motor, the PWM command value, and the like when each motor is accurately controlled to a constant speed or a predetermined speed.

The demodulation unit 284 demodulates the variable torque data acquired by the torque data acquisition unit 283 for each frequency of the modulation cycle of the speed of each photoconductor 19. In the present embodiment, by demodulating the fluctuation torque data in this way, when a plurality of photoconductors 19 are brought into contact with the intermediate transfer belt 10 at the same time and rotated, the speed fluctuations of each photoconductor 19 are met. The change in the driving torque Ta can be individually extracted for each photoconductor 19. Details of the demodulation unit 284 will be described later.

The speed calculation unit 285 calculates a target value of the rotation speed of each photoconductor 19 based on the change of the drive torque Ta according to the speed fluctuation of each photoconductor 19 extracted by the demodulation unit 284. Details of the calculation of the target value by the speed calculation unit 285 will be described later.

Next, the demodulation unit 284 of the present embodiment will be described with reference to FIG. 7. FIG. 7 is a diagram illustrating a demodulation unit of the first embodiment.

The demodulation unit 284 of the present embodiment includes an oscillator 291 and a 90 ° phase shifter 292, a multiplier 293a and 293b, an LPF (Low-pass filter) 294a and 294b, an amplitude calculation unit 295, and a phase calculation unit 296.

In the demodulation unit 284, the variable torque data Tr acquired by the torque data acquisition unit 283 is input.

The oscillator 291 outputs the frequency component to be detected to the 90 ° phase shifter 292 and the multiplier 293a. The frequency component to be detected is the frequency of the speed fluctuation of the photoconductor 19. For example, when the speed adjusting unit 280 is the speed adjusting unit 280C corresponding to the photoconductor 19C, the oscillator 291 outputs a signal of the frequency component of the speed modulation cycle of the photoconductor 19C as the frequency component to be detected.

The multiplier 293a multiplies the fluctuation torque data Tr with the signal of the oscillation frequency output from the oscillator 291 and outputs the result to the LPF294a. The multiplier 293b multiplies the fluctuation torque data Tr with the signal output from the 90 ° phase shifter 292, and outputs the result to the LPF294b.

In the multipliers 293a and 293b, the variable torque data Tr is separated into a signal of the in-phase component (I component) and a signal of the orthogonal component (Q component) of the photoconductor 19. The output from the multiplier 293a is the I component, and the output from the multiplier 293b is the Q component.

The LPF294a allows only the low frequency band signal to pass through the signal output from the multiplier 293a. In the present embodiment, a low-pass filter that smoothes data for an integral multiple of the oscillation period, that is, velocity data for one rotation of the photoconductor 19, may be used as the LPF294a. The same applies to LPF294b. The outputs of LPF294a and 294b are supplied to the amplitude calculation unit 295 and the phase calculation unit 296, respectively.

The amplitude calculation unit 295 calculates the amplitude a (t) corresponding to the two inputs (I component and Q component) supplied from the LPF 294a and 294b. Further, the phase calculation unit 296 calculates the phase b (t) corresponding to the two inputs supplied from the LPF294a and 294b. In addition, t indicates a time.

The amplitude a (t) and the phase b (t) are the amplitude of the velocity fluctuation component of the photoconductor 19 and the phase angle from an arbitrary reference timing. The demodulation unit 284 of the present embodiment outputs the amplitude a (t) and the phase b (t) to the speed calculation unit 285.

In the following description, the waveform indicated by the amplitude a (t) and the phase b (t) demodulated by the demodulation unit 284 is referred to as demodulation torque data.

If it is desired to detect the amplitude and phase of the secondary fluctuation component for one rotation of the photoconductor 19 and the fluctuation component of the rotation cycle of the photoconductor drive motor 42, the oscillation cycle is set to the secondary component or the photoconductor drive motor 42. The same processing may be performed by setting the rotation cycle of.

As described above, in the present embodiment, the amplitude and phase of the fluctuation component of the velocity data are calculated by orthogonal detection processing, so that the amplitude and phase can be made more accurate than the method by zero crossing or peak detection of the fluctuation value. It is possible to calculate. In the present embodiment, by using the orthogonal detection process, it is possible to significantly reduce the calculation load as compared with the case where the calculation is performed using, for example, the Fourier transform analysis (FFT analysis).

Next, the operation of the speed adjusting unit 280 of the present embodiment will be described with reference to FIG. FIG. 8 is a flowchart illustrating the processing of the speed adjusting unit of the first embodiment.

The speed adjusting unit 280 of the present embodiment sets the reference value T0 by the reference value setting unit 281 (step S801).

Specifically, for example, when the drive torque Ta when the intermediate transfer motor 21 is driven alone is set to the reference value T0, the intermediate transfer motor 21 is driven with the transfer roller 20 separated from the intermediate transfer belt 10. , The drive torque Ta at that time is acquired and set to the reference value T0. If the drive torque Ta when the intermediate transfer motor 21 is driven alone is set to the reference value T0, it is possible to suppress the generation of interference torque between the photoconductor 19 and the intermediate transfer belt 10.

Further, for example, when the drive torque Ta in the state where the photoconductor 19 and the intermediate transfer belt 10 are in contact with each other is set to the reference value T0, the intermediate transfer motor 21 is moved in a state where the transfer roller 20 is in contact with the intermediate transfer belt 10. It is driven, the drive torque Ta is acquired, and the reference value is set to T0.

When the drive torque Ta in the state where the photoconductor 19 and the intermediate transfer belt 10 are in contact with each other is set to the reference value T0, the state immediately before the toner image formed on the photoconductor 19 is transferred to the recording medium is maintained. Therefore, the target value of the rotation speed of the photoconductor 19 is calculated. Therefore, in this case, the interference torque between the photoconductor 19 and the intermediate transfer belt 10 is maintained in a state of being generated, but the transfer rate of the toner image to the recording medium can be improved.

Subsequently, the speed adjusting unit 280 starts the printing operation by the image forming apparatus 300 (step S802). Specifically, the speed adjusting unit 280 brings the transfer roller 20 into contact with the intermediate transfer belt 10 by the motion control unit 240. At this time, the plurality of transfer rollers 20 are simultaneously brought into contact with the intermediate transfer belt 10 by one common separation mechanism. When the transfer roller 20 comes into contact with the intermediate transfer belt 10 in step S801, the speed adjusting unit 280 may proceed to step S803.

Subsequently, the speed adjusting unit 280 starts the speed modulation of the rotation speed of the photoconductor 19 by the speed modulation control unit 282 (step S803). In this embodiment, the frequency of the speed modulation cycle may be preset for each photoconductor 19. The speed modulation control unit 282 instructs the speed control unit 271 of the photoconductor control unit 270 corresponding to each photoconductor 19 to change the rotation speed at a preset frequency.

Next, the speed adjustment unit 280 samples the drive torque Ta of the intermediate transfer motor 21 at a predetermined timing by the torque data acquisition unit 283, and acquires the fluctuation torque data Tr (step S804). The timing of sampling the drive torque Ta is as described above.

Next, the speed adjusting unit 280 demodulates the variable torque data Tr to the frequency component of the speed modulation of the rotation speed of the photoconductor 19 by the demodulating unit 284 (step S805). Subsequently, the speed adjustment unit 280 calculates the target value of the rotation speed of the photoconductor 19 from the demodulated frequency component and the reference value T0 by the speed calculation unit 285 (step S806).

Subsequently, the speed adjusting unit 280 sets the calculated target value of the rotation speed in the photoconductor control unit 270 of the corresponding photoconductor 19 (step S807), and ends the process. In the present embodiment, the target value of the rotation speed of the photoconductor 19 may be stored in the memory 330 of the main control unit 310.

The calculation of the target value of the rotation speed of the photoconductor 19 by the speed adjusting unit 280 of the present embodiment will be described below with reference to FIG.

FIG. 9 is a diagram illustrating the processing of the speed adjusting unit of the first embodiment. FIG. 9A shows the modulation waveforms of the rotational speeds of the photoconductors 19C, 19M, and 19Y. In FIG. 9A, the vertical axis represents the ratio of the rotational speed to the preset rotational speed of the photoconductor, and the horizontal axis represents time.

FIG. 9B shows the waveform of the fluctuation torque data Tr according to the modulation of the rotation speed shown in FIG. 9A. FIG. 9C shows demodulated torque data obtained by demodulating the variable torque data Tr for each frequency of the modulation cycle of the rotation speed. In FIGS. 9B and 9C, the vertical axis represents the torque fluctuation amount indicating the fluctuation amount of the drive torque Ta, and the horizontal axis represents time.

Further, in the example of FIG. 9, the drive torque Ta when the intermediate transfer motor 21 is driven as a single unit by the reference value setting unit 281 is set to the reference value T0.

The effects of each of the photoconductors 19C, 19M, and 19Y on the surface speed of the intermediate transfer belt 10 are independent because each of the photoconductors 19 is driven by individual photoconductor drive motors 42C, 42M, and 42Y. ..

Therefore, when the photoconductors 19C, 19M, and 19Y are brought into contact with the intermediate transfer belt 10 and driven, the interference torques of the photoconductor drive motors 42C, 42M, and 42Y and the intermediate transfer motor 21 are combined and appear. ..

That is, by modulating the rotation speed of each photoconductor 19, the interference torque between the photoconductor drive motors 42C, 42M, and 42Y and the intermediate transfer motor 21 is combined with the drive torque Ta and appears. In other words, the change in the drive torque Ta according to the fluctuation of the rotation speed of each photoconductor 19 is a change due to the generation of the interference torque between each photoconductor drive motor 42 and the intermediate transfer motor 21.

Further, by periodically modulation the rotation speed of the photoconductor 19, the frequency component by the orthogonal detection process can be separated, and demodulation can be performed by changing the modulation cycle of the speed of each photoconductor and inputting the frequency component.

In the present embodiment, as shown by each waveform shown in FIG. 9A, the rotation speeds of the photoconductors 19C, 19M, and 19Y are periodically changed. As a result, the drive torque Ta changes as shown in the waveform shown in FIG. 9B. From FIG. 9B, it can be seen that the waveform of the drive torque Ta is an inversely correlated waveform with respect to the modulation of the rotation speed of the photoconductor 19, and the speed influence of each photoconductor 19 is reflected.

When the fluctuating torque data shown in FIG. 9B is demodulated for each frequency of the modulation cycle of the rotation speed of each photoconductor 19, the result is as shown in FIG. 9C. The waveform of each demodulation torque data shown in FIG. 9C is a waveform in which the interference torque generated by the fluctuation of the rotation speed of each photoconductor 19 is independently reflected in the drive torque Ta.

For example, the demodulation torque data 91C corresponding to the photoconductor 19C shows a waveform in which the interference torque generated by the fluctuation of the rotation speed of the photoconductor 19C is reflected in the drive torque Ta. Similarly, the demodulation torque data corresponding to the photoconductor 19M shows a waveform in which the interference torque generated by the fluctuation of the rotation speed of the photoconductor 19M is reflected in the drive torque Ta, and the demodulation torque data corresponding to the photoconductor 19Y is , The interference torque generated by the fluctuation of the rotation speed of the photoconductor 19Y shows a waveform reflected in the drive torque Ta.

As a result of demodulation, the demodulation unit 284 of the present embodiment outputs the amplitude a (t) and the phase b (t) of the demodulation torque data shown in FIG. 9C to the speed calculation unit 285.

Therefore, the velocity calculation unit 285 acquires the waveform shown in FIG. 9C as a function from the amplitude a (t) and the phase b (t). Then, the speed calculation unit 285 calculates the rotation speed of the photoconductor 19 when the drive torque Ta reaches the reference value T0, and sets the calculated rotation speed as the target value of the photoconductor 19.

In FIG. 9, the reference value T0 is the drive torque Ta when the intermediate transfer motor 21 is driven as a single unit. In other words, in FIG. 9, the driving torque Ta in the state where the interference torque due to the fluctuation of the rotation speed of the photoconductor 19 is not generated is set as the reference value T0.

The speed calculation unit 285C of the speed adjustment unit 280C obtains the time t1 in which the torque fluctuation amount becomes the reference value T0 in the demodulation torque data 91C corresponding to the photoconductor 19C in FIG. 9C. Then, the speed calculation unit 285C acquires a value indicating the rate of change in the rotation speed of the photoconductor 19C at time t1. In the example of FIG. 9, the value indicating the rate of change in the rotation speed of the photoconductor 19C at time t1 is 0.1.

Therefore, the speed calculation unit 285C sets a value obtained by multiplying the rotation speed of the photoconductor 19C by 1.1 as a target value of the rotation speed of the photoconductor 19C in the photoconductor control unit 270C.

The speed adjusting units 280M and 280Y of the present embodiment also similarly set the target value of the rotation speed of each photoconductor 19 from the waveform 91M corresponding to the photoconductor 19M and the waveform 91Y corresponding to the photoconductor 19Y, respectively. Calculate and set.

As described above, according to the present embodiment, a plurality of independently driven rotating bodies (photoreceptors) are separated from one rotating body (intermediate transfer belt) at the same time by one common separation mechanism. In the contacting configuration, the rotation speeds of the plurality of rotating bodies can be individually adjusted.

Therefore, according to the present embodiment, it is possible to stabilize the drive of one rotating body paired with the plurality of rotating bodies even when they are in contact with a plurality of rotating bodies at the same time.

In the present embodiment, the transport device 100 is provided in the image forming device 300 that forms an electrostatic latent image on the photoconductor 19 and transfers it to a recording medium, but the present invention is not limited to this. The transport device 100 may be mounted on, for example, an inkjet image forming device. Further, the transport device 100 may be applied to a device for transporting a sheet-shaped recording medium by rotating a rotating body, in addition to the image forming device. In the device to which the present embodiment is applied, in a pair of a plurality of rotating bodies having independent drive sources and one rotating body, the plurality of rotating bodies are opposed to one rotating body by a common separation mechanism. Any device may be used as long as it has a structure of contact / separation.

(Second embodiment)
The second embodiment will be described below with reference to the drawings. In the second embodiment, the speed adjusting unit 280 is not provided for each photoconductor, and has a point of switching for each photoconductor to adjust the speed and a function of performing phase matching with respect to the waveform after demodulation. And are different from the first embodiment. Therefore, in the following description of the second embodiment, only the differences from the first embodiment will be described, and the one having the same functional configuration as the first embodiment will be described in the description of the first embodiment. A code similar to the code used will be assigned, and the description thereof will be omitted.

FIG. 10 is a diagram illustrating the function of the rotating body control unit of the second embodiment. The rotating body control unit 210A of this embodiment includes an operation control unit 240, a paper passing detection unit 245, an intermediate transfer control unit 250, a secondary transfer control unit 260, a photoconductor control unit 270C, 270M, 270Y, 270K, and a speed adjustment unit. It has 280A.

The 280A of the present embodiment includes a reference value setting unit 281, a speed modulation control unit 282, a torque data acquisition unit 283, a demodulation unit 284, a speed calculation unit 285, a frequency switching unit 286, and a phase correction unit 287.

The frequency switching unit 286 of the present embodiment switches the frequency set in the oscillator 291 of the demodulation unit 284.

The phase correction unit 287 of the present embodiment sets the target value by the speed calculation unit 285 when the phase of the demodulation torque data is deviated from the phase of the waveform indicating the modulation cycle of the rotation speed of the photoconductor 19 by the demodulation unit 284. Before the calculation, the phase of the demodulated torque data is corrected.

The operation of the speed adjusting unit 280A of the present embodiment will be described below with reference to FIG. FIG. 11 is a flowchart illustrating the processing of the speed adjusting unit of the second embodiment.

Since the processing from step S1101 to step S1104 in FIG. 11 is the same as the processing from step S801 to step S804 in FIG. 8, the description thereof will be omitted.

When the fluctuation torque data Tr is acquired in step S1104, the speed adjustment unit 280A sets the frequency indicating the modulation cycle of the rotation speed of the photoconductor 19C to the oscillator 291 of the demodulation unit 284 by the frequency switching unit 286, and changes The torque data Tr is demodulated (step S1105). In this embodiment, the demodulated torque data 91C shown in FIG. 9C is obtained here.

Here, the frequency is first demodulated from the frequency indicating the modulation period corresponding to the photoconductor 19C, but the present invention is not limited to this. The order of demodulation may be arbitrary.

Subsequently, in the speed adjustment unit 280A, whether the phase b (t) output from the demodulation unit 284 by the phase correction unit 287 is deviated by a predetermined value or more from the phase of the waveform indicating the modulation cycle of the rotation speed of the photoconductor 19C. It is determined whether or not (step S1106). The predetermined value at this time is predetermined and may be set in the phase correction unit 287.

In step S1106, when the phase shift between the phase b (t) and the phase of the waveform indicating the modulation period is less than a predetermined value, the speed adjusting unit 280A proceeds to step S1108 described later.
In step S1106, when the deviation between the phase b (t) and the phase of the waveform indicating the modulation period is equal to or greater than a predetermined value, the phase correction unit 287 corrects the value of the phase b (t) (step S1107). The process proceeds to step S1108 described later. The corrected phase b (t) is output to the velocity calculation unit 285 together with the amplitude a (t).

Specifically, the phase correction unit 287 may correct the value of the phase b (t) by rewriting the value of the phase b (t) to the phase of the waveform indicating the modulation period, or may modulate the value of the phase b (t). Rewriting may be performed so that the deviation from the phase of the waveform indicating the period is less than a predetermined value.

The reason why the phase b (t) and the phase of the waveform indicating the modulation period are out of phase will be described below. This phase shift is caused, for example, after the torque followability of the intermediate transfer motor 21 to the rotation speed modulation by the photoconductor drive motor 42C of the photoconductor 19C is low and the rotation speed is changed by the photoconductor control unit 270. This is the case where a time lag occurs before the fluctuation torque data Tr of the intermediate transfer motor 21 is reflected. The cause of the time lag is the deformation of parts such as the inertia of the system driven and transmitted by the intermediate transfer motor 21 and the intermediate transfer belt 10, and the delay due to the filter processing in the signal processing of torque information.

Subsequently, the speed adjusting unit 280A calculates the target value of the rotation speed of the photoconductor 19C by the speed calculation unit 285 (step S1108), and sets the calculated target value of the rotation speed in the photoconductor control unit 270C (step). S1109).

Next, the speed adjusting unit 280A determines whether or not a target value has been set for all the photoconductors 19 that are simultaneously abutted / separated from the intermediate transfer belt 10 (step S1110).

If the target values have not been set for all the photoconductors 19 in step S1110, the speed adjusting unit 280A selects the next photoconductor 19M. Then, the speed adjusting unit 280A sets a frequency indicating the modulation cycle of the rotation speed of the photoconductor 19M for the oscillator 291 of the demodulating unit 284 by the frequency switching unit 286, and demodulates the variable torque data Tr (step S1111). , Step S1106.

When the target values are set for all the photoconductors 19 in step S1110, the speed adjusting unit 280A ends the process.

As described above, according to the present embodiment, the target value of the rotation speed of each photoconductor 19 can be adjusted without providing the speed adjusting unit 280A for each photoconductor 19.

Further, according to the present embodiment, when the phase of the demodulated torque data and the phase of the waveform of the modulation cycle of the rotation speed of the photoconductor 19 are deviated by the demodulation unit 284, this is performed before the calculation of the target value. The deviation can be corrected.

In the present embodiment, the target value of the rotation speed of the photoconductor 19 is calculated based on the fluctuation amount of the rotation speed corresponding to the time when the torque fluctuation amount becomes the reference value in the demodulated torque data. Therefore, if there is a large deviation between the phase of the demodulated torque data and the phase of the waveform of the modulation cycle of the rotation speed of the photoconductor 19, the accuracy of calculating the target value may decrease.

In the present embodiment, since this phase shift is corrected, the accuracy of calculating the target value can be improved.

(Third embodiment)
The third embodiment will be described below with reference to the drawings. The third embodiment differs from the first embodiment in that the drive torque Ta is substituted with a value other than the load torque value calculated based on the PWM command value and the rotation speed of the intermediate transfer motor 21. .. Therefore, in the following description of the third embodiment, only the differences from the first embodiment will be described, and the description of the first embodiment will be described for those having the same functional configuration as the first embodiment. A code similar to the code used in 1 is assigned, and the description thereof will be omitted.

In the image forming apparatus, when the intermediate transfer motor 21, the secondary transfer motor 32, and the photoconductor drive motor 42 are controlled to a constant rotation speed, a value other than the load torque value is set as the drive torque Ta of the intermediate transfer motor 21. It can be used instead. The load torque value is an estimation of the drive torque Ta calculated based on the PWM command value output from the intermediate transfer control unit 250 to the driver 221 and the rotation speed of the intermediate transfer motor 21 obtained from the scale sensor 16. The value.

The reason is that the fluctuation of the interference torque due to the difference in surface speed between the intermediate transfer belt 10, the secondary transfer roller 31, and the photoconductor 19 is the fluctuation in the frequency band included in the control band in the feedback control.

If feedback control is performed for each motor, the rotation speed of each motor is reflected in the rotating body control unit. That is, the fluctuation of the drive torque of each motor is also reflected in each signal upstream of each motor.

Therefore, in the present embodiment, the case where the current command value, the drive current, the PWM actual measurement value, the torque actual measurement value, and the like supplied to the intermediate transfer motor 21 are used instead of the drive torque Ta of the intermediate transfer motor 21 will be described. In other words, the current command value, drive current, PWM actual measurement value, torque actual measurement value, etc. supplied to the intermediate transfer motor 21 are used as the transport force of the intermediate transfer motor 21.

In the present embodiment, each value used as the transport force of the intermediate transfer motor 21 is a value having a proportional relationship with the drive torque Ta.

Since each of the above values is used as the conveying force of the intermediate transfer motor 21, the rotation speed of the photoconductor drive motor 42 by the rotating body control unit in the present embodiment is controlled by the same method as in the first embodiment. Will be.

FIG. 12 is a diagram illustrating a motor control unit when a current command value is used. The motor control unit 200A of the image forming apparatus 300A of FIG. 12 includes a rotating body control unit 210B, drivers 221A, 222A, 223A, and FETs 231 and 232, 233.

The rotating body control unit 210B outputs a current command value indicating the current supplied to each motor to each driver.

The rotating body control unit 210B of the present embodiment has an acquisition unit that acquires this current command value, and uses the current command value acquired by the acquisition unit instead of the drive torque Ta of the intermediate transfer motor 21.

FIG. 13 is a diagram illustrating a motor control unit when a measured current value is used.

The motor control unit 200B of the image forming apparatus 300B of FIG. 13 includes a rotating body control unit 210C, drivers 221, 222, 223, and FETs 231, 232, and 233.

The rotating body control unit 210C has an acquisition unit that acquires an actual measurement value of the current flowing through the intermediate transfer motor 21 from a current detection sensor that detects the current flowing through the intermediate transfer motor 21, and the actual measurement value of the current acquired by the acquisition unit. Is used instead of the drive torque Ta of the intermediate transfer motor 21.

FIG. 14 is a diagram illustrating a motor control unit when the drive torque is estimated from the PWM actual measurement value.

The motor control unit 200C of the image forming apparatus 300C of FIG. 14 includes a rotating body control unit 210D, drivers 221B, 222, 223, and FETs 231 and 232, 233.

The driver 221B of the present embodiment outputs the duty of the PWM signal generated according to the PWM command value supplied from the rotating body control unit 210D to the rotating body control unit 210D as the PWM actual measurement value. More specifically, the driver 221B has, for example, a clock counter or the like, and outputs the duty of the PWM signal generated by the driver 221B obtained from the number of counted clocks to the rotating body control unit 210D. ..

The rotating body control unit 210D has an acquisition unit that acquires the PWM actual measurement value, and uses the PWM actual measurement value acquired by the acquisition unit instead of the drive torque Ta of the intermediate transfer motor 21.

FIG. 15 is a diagram illustrating a motor control unit when a measured torque value is used.

The motor control unit 200D of the image forming apparatus 300D of FIG. 15 includes a rotating body control unit 210E, drivers 221, 222, 223, and FETs 231 and 232, 233.

In the image forming apparatus 300D, the intermediate transfer motor 21 is provided with a torque meter 90 for measuring the drive torque Ta of the intermediate transfer motor 21. The torque meter 90 outputs the measured drive torque Ta to the rotating body control unit 210D.

The rotating body control unit 210D has an acquisition unit that acquires the drive torque Ta measured by the torque meter 90, and the drive torque Ta acquired by this acquisition unit is used instead of the estimated value of the drive torque Ta of the intermediate transfer motor 21. Use.

As described above, according to the present embodiment, since another value can be used instead of the drive torque Ta of the intermediate transfer motor 21, it is not necessary to calculate the estimated value of the drive torque Ta.

Although the present invention has been described above based on each embodiment, the present invention is not limited to the requirements shown in the above embodiments. With respect to these points, the gist of the present invention can be changed without impairing the gist of the present invention, and can be appropriately determined according to the application form thereof.

11 Intermediate transfer roller 19 Photoreceptor 20 Transfer roller 21 Intermediate transfer motor 31 Secondary transfer roller 32 Secondary transfer motor 42 Photoreceptor drive motor 100, 100A Transfer device 200, 200A to 200D Motor control unit 210, 210A to 210E Rotating body control Unit 240 Operation control unit 245 Paper transmission detection unit 250 Intermediate transfer control unit 260 Secondary transfer control unit 270 Photoreceptor control unit 280 Speed adjustment unit 281 Reference value setting unit 282 Speed modulation control unit 283 Torque data acquisition unit 284 Demodulation unit 285 Calculation unit 286 Frequency switching unit 287 Phase correction unit 300, 300A to 300D Image forming device 310 Main control unit 320 Operation unit 330 Memory

Japanese Unexamined Patent Publication No. 2016-114947

Claims (14)

A rotating body control device that controls a first rotating body that is rotationally driven by a first driving source and a plurality of second rotating bodies that are rotationally driven by a plurality of independent second driving sources. ,
An operation control unit that brings the plurality of second rotating bodies into contact with and separated from the first rotating body at the same time.
A speed modulation control unit that modulates the rotation speeds of the plurality of second rotating bodies at different modulation cycles in a state where the first rotating body and the plurality of second rotating bodies are in contact with each other.
A torque data acquisition unit that acquires fluctuation torque data indicating a fluctuation amount of a value of the drive torque of the first drive source or a value having a proportional relationship with the value of the drive torque according to the modulation of the rotation speed.
A demodulation unit that demodulates the fluctuation torque data for each modulation cycle and acquires demodulation torque data for each modulation cycle.
The rotation speed of the second rotating body corresponding to the modulation cycle is calculated when the fluctuation amount becomes a reference value in the demodulation torque data for each modulation cycle, and the second rotating body corresponding to the second rotating body is calculated. A rotating body control device having a speed calculation unit for setting a target value of the rotation speed as a drive source of the above. The speed modulation control unit
Modulation of the rotation speed of the plurality of second rotating bodies is started at the same timing,
The rotating body control device according to claim 1, wherein the modulation period is an integral multiple of a period for rotating the second rotating body before modulation. The rotating body control device according to claim 1 or 2, wherein the modulation period is 2 to the nth power (n ≧ 1). The torque data acquisition unit
The rotating body control device according to any one of claims 1 to 3, wherein the fluctuation amount is sampled for each common multiple of the modulation period of each of the second rotating bodies. The demodulation unit
The rotating body control device according to any one of claims 1 to 4, wherein the fluctuation torque data is demodulated from the amplitude and phase obtained by the synchronous detection approximation for each modulation cycle. The reference value is a value proportional to the value of the driving torque or the driving torque in a state where the plurality of second rotating bodies are separated from the first rotating body, according to claims 1 to 5. The rotating body control device according to any one item. A phase correction unit that corrects the phase of the demodulated torque data when the deviation between the phase of the demodulated torque data and the phase of the waveform indicating the rotational speed of the second rotating body after modulation is equal to or greater than a predetermined value. The rotating body control device according to any one of claims 1 to 6. The speed modulation control unit
Any one of claims 1 to 7, wherein the plurality of second rotating bodies having the shortest distance from the first rotating body to the contact portion are modulated so that the amplitude becomes larger and the period becomes longer. The rotating body control device according to. The values having a proportional relationship with the drive torque are the drive current of the first drive source, the current command value supplied to the first drive source, and the PWM command value supplied to the first drive source. The rotating body control device according to any one of claims 1 to 8, which is at least one of them. Any of claims 1 to 9, wherein the first rotating body is an endless intermediate transfer belt, and the plurality of second rotating bodies are photoconductors that transfer a toner image onto the intermediate transfer belt. The rotating body control device according to item 1. A transport device that controls a first rotating body that is rotationally driven by a first drive source and a plurality of second rotating bodies that are rotationally driven by a plurality of independent second drive sources.
With the first rotating body
With the plurality of second rotating bodies,
Has a rotating body control device,
The rotating body control device is
An operation control unit that brings the plurality of second rotating bodies into contact with and separated from the first rotating body at the same time.
A speed modulation control unit that modulates the rotation speeds of the plurality of second rotating bodies at different modulation cycles in a state where the first rotating body and the plurality of second rotating bodies are in contact with each other.
A torque data acquisition unit that acquires fluctuation torque data indicating a fluctuation amount of the drive torque value of the first drive source or a value having a proportional relationship with the drive torque value according to the fluctuation of the rotation speed.
A demodulation unit that demodulates the fluctuation torque data for each modulation cycle and acquires demodulation torque data for each modulation cycle.
The rotation speed of the second rotating body corresponding to the modulation cycle is calculated when the fluctuation amount becomes a reference value in the demodulation torque data for each modulation cycle, and the second rotating body corresponding to the second rotating body is calculated. A transport device having a speed calculation unit for setting a target value of the rotation speed as a drive source of the above. An image forming apparatus having a transport device for controlling a first rotating body that is rotationally driven by a first driving source and a plurality of second rotating bodies that are rotationally driven by a plurality of independent second driving sources. And
The transport device is
With the first rotating body
With the plurality of second rotating bodies,
Has a rotating body control device,
The rotating body control device is
An operation control unit that brings the plurality of second rotating bodies into contact with and separated from the first rotating body at the same time.
A speed modulation control unit that modulates the rotation speeds of the plurality of second rotating bodies at different modulation cycles in a state where the first rotating body and the plurality of second rotating bodies are in contact with each other.
A torque data acquisition unit that acquires fluctuation torque data indicating a fluctuation amount of the drive torque value of the first drive source or a value having a proportional relationship with the drive torque value according to the fluctuation of the rotation speed.
A demodulation unit that demodulates the fluctuation torque data for each modulation cycle and acquires demodulation torque data for each modulation cycle.
The rotation speed of the second rotating body corresponding to the modulation cycle is calculated when the fluctuation amount becomes a reference value in the demodulation torque data for each modulation cycle, and the second rotating body corresponding to the second rotating body is calculated. An image forming apparatus having a speed calculation unit for setting a target value of the rotation speed as a drive source of the above. A rotating body by a rotating body control device that controls a first rotating body that is rotationally driven by a first driving source and a plurality of second rotating bodies that are rotationally driven by a plurality of independent second driving sources. It ’s a control method,
The plurality of second rotating bodies are simultaneously brought into contact with and separated from the first rotating body.
In a state where the first rotating body and the plurality of second rotating bodies are in contact with each other, the rotation speeds of the plurality of second rotating bodies are modulated by different modulation cycles.
Fluctuation torque data indicating the fluctuation amount of the drive torque value of the first drive source or the value proportional to the drive torque value according to the modulation of the rotation speed is acquired.
The fluctuation torque data is demodulated for each modulation cycle, and the demodulated torque data for each modulation cycle is acquired.
The rotation speed of the second rotating body corresponding to the modulation cycle is calculated when the fluctuation amount becomes a reference value in the demodulation torque data for each modulation cycle, and the second rotating body corresponding to the second rotating body is calculated. A method for controlling a rotating body, which is set as a target value of the rotation speed in the drive source of the above. It is executed by a rotating body control device that controls a first rotating body that is rotationally driven by a first driving source and a plurality of second rotating bodies that are rotationally driven by a plurality of independent second driving sources. It is a rotating body control program, and the rotating body control device
The plurality of second rotating bodies are simultaneously brought into contact with and separated from the first rotating body.
In a state where the first rotating body and the plurality of second rotating bodies are in contact with each other, the rotation speeds of the plurality of second rotating bodies are modulated by different modulation cycles.
Fluctuation torque data indicating the fluctuation amount of the drive torque value of the first drive source or the value proportional to the drive torque value according to the modulation of the rotation speed is acquired.
The fluctuation torque data is demodulated for each modulation cycle, and the demodulated torque data for each modulation cycle is acquired.
The rotation speed of the second rotating body corresponding to the modulation cycle is calculated when the fluctuation amount becomes a reference value in the demodulation torque data for each modulation cycle, and the second rotating body corresponding to the second rotating body is calculated. A rotating body control program for executing processing, which is set as a target value of the rotational speed in the driving source of the above.

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