JP2015145957A - Belt conveyance apparatus, image forming apparatus, and image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the reduction in accuracy of controlling belt surface speed.SOLUTION: A belt conveyance apparatus includes: a drive roller for driving a belt; a first detection section for detecting a belt surface speed of the belt; a second detection section for detecting rotation speed of the drive roller; a first calculation section 201 which calculates first deviation from a belt target speed, on the basis of the belt target speed and the belt surface speed; a storage section 22 for storing a control value corresponding to the first deviation; a second calculation section 205 which calculates a second deviation from the target speed, on the basis of the target speed, the first deviation, and the rotation speed; control sections 206, 207 for controlling the rotation speed of the drive roller, on the basis of the second deviation; a mode determination section which determines a control mode for controlling the rotation speed of the drive roller, between a mode which uses the first detection section and the second detection section and a mode which does not use the first detection section; and a switching section 204 which, when the mode determination section determines the mode that does not use the first detection section, switches the first deviation in calculating the second deviation by means of the second calculation section, to the control value.

Description

  The present invention relates to a belt conveyance device, an image forming apparatus, and an image forming system.

For example, in a transfer belt driving unit of a copying machine, a belt surface speed is controlled with high accuracy using a sensor for detecting a surface speed of a transfer belt (hereinafter simply referred to as a belt) and a sensor for detecting a speed of a driving roller. It has been known.
In the conventional belt drive unit, the belt surface speed detection sensor may not be used depending on the operation mode such as color, monochrome, etc., depending on the machine layout (mechanical layout) problem depending on the machine (equipment). . In such a case, control may be performed using only a drive roller speed detection encoder (hereinafter simply referred to as an encoder) without using a belt surface speed sensor (hereinafter referred to as a belt scale sensor). However, this control can be realized only when a certain degree of accuracy of the belt surface speed is maintained without feeding back the detection result of the belt surface speed.

  That is, when the belt surface speed is controlled only by the encoder, the belt surface speed may fluctuate due to, for example, expansion of the driving roller due to a temperature rise or the like. If the fluctuation range is large, fluctuations in the detection result of the encoder and the actual roller surface speed of the driving roller become large, and the accuracy of the belt surface speed cannot be maintained. For this reason, it is essential to use the belt surface speed sensor regardless of the operation mode, and there is a problem that the mechanical layout is restricted.

Here, looking at the prior art in the belt conveyance device, Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-220006) describes that the belt scale is normal due to dirt or the like for the purpose of reducing downtime when the belt scale malfunctions. A belt surface speed correction method for switching to encoder control when an output cannot be obtained is disclosed.
Patent Document 2 (Japanese Patent Laid-Open No. 2009-222112) discloses a belt drive control device that measures a belt surface speed with a belt scale and controls the belt surface speed with a double loop with a drive shaft encoder. ing.

  However, in either case, when the belt surface speed is controlled only by the encoder by mode switching or the like, the point of maintaining the accuracy of the belt surface speed control cannot be solved.

  The present invention has been made to solve the above-described conventional problems in the belt conveyance device, and the object thereof is a first detection unit that detects the speed of the surface of the belt and a first detection unit that detects the rotation speed of the drive roller. In the belt conveyance device that controls the belt surface speed using the two detection units, in the control mode of the belt surface speed that does not use the first detection unit, a decrease in the accuracy of the control is minimized.

  The present invention includes a driving roller that rotates to drive a belt, a first detection unit that detects a speed of a surface of the driven belt, a second detection unit that detects a rotation speed of the driving roller, and the belt On the basis of the target speed of the belt and the speed of the surface of the belt, a first calculation unit that calculates a first deviation with respect to the target speed, a storage unit that stores a control value corresponding to the first deviation, the target speed, A second calculation unit that calculates a second deviation with respect to the target speed based on the first deviation and the rotation speed; a control unit that controls the rotation speed of the drive roller based on the second deviation; and a drive roller A mode determining unit that determines any one of a mode in which the first detection unit and the second detection unit are used, and a mode in which the first detection unit is not used. 1 detector is used As determined without mode, a belt conveying apparatus characterized by having a switching unit for switching said first deviation in the calculation of the second deviation by the second calculating section to the control value.

  According to the present invention, in the belt conveyance device that controls the belt surface speed using the first detection unit that detects the speed of the surface of the belt and the second detection unit that detects the rotational speed of the driving roller, In the belt surface speed control mode that does not use the detection unit, it is possible to suppress a decrease in the accuracy of the control.

1 is a front view illustrating an image forming apparatus as an example of an apparatus on which a belt conveyance device according to an embodiment of the present invention is mounted. FIG. 3 is an enlarged view of a main part near an intermediate transfer unit of the image forming apparatus. FIG. 2 is a block diagram schematically showing a belt drive control unit and a main control unit of a belt conveyance device mounted on an image forming apparatus. It is a block diagram which shows the structure of the control controller used as the premise technique of this invention, and its periphery. It is the figure which illustrated about the influence in the case of not performing belt surface speed detection, ie, the case of control only by an encoder. FIG. 2 is a block diagram schematically illustrating a configuration of a control controller and its peripheral portion in the belt conveyance device of the first embodiment. FIG. 2 is a block diagram schematically illustrating a configuration of a control controller and its peripheral portion in the belt conveyance device of the first embodiment. It is a flowchart explaining the process sequence for preservation | save of the average value of the data A in the belt conveying apparatus of Embodiment 1. FIG. 5 is a flowchart showing a mode selection processing procedure at the time of start-up in the belt conveyance device of the first embodiment. It is a block diagram which shows roughly the structure of the control controller of the belt conveying apparatus of Embodiment 2, and its peripheral part. It is a block diagram which shows roughly the structure of the control controller of the belt conveying apparatus of Embodiment 2, and its peripheral part. FIG. 10 is a flowchart illustrating a processing procedure for storing an average value of data B in the belt conveyance device of the second embodiment. FIG. 10 is a flowchart illustrating a mode selection processing procedure at the time of activation in the belt conveyance device of the second embodiment. It is a figure which shows the example of a setting of the storage area of the data for every temperature in memory. FIG. 10 is a flowchart illustrating a processing procedure for storing an average value of data A in the belt conveyance device of the third embodiment. FIG. 10 is a flowchart showing a mode selection processing procedure at the time of activation in the belt conveyance device of the third embodiment. FIG. 10 is a flowchart illustrating a processing procedure for storing an average value of data B in the belt conveyance device of the fourth embodiment. FIG. 10 is a flowchart showing a mode selection processing procedure at the time of activation in the belt conveyance device of the fourth embodiment.

The present invention generally controls a belt surface speed with high accuracy by using a sensor (referred to as a belt scale sensor) that detects the surface speed of the belt and a sensor (encoder) that detects the rotational speed of the drive roller. In the belt conveyance device, the average value of the control amount calculated by the controller is stored based on the position deviation obtained from the detection result of the belt surface speed detected in the normal time. When the control mode is switched when the belt scale sensor that detects the belt surface speed is abnormal, that is, when the speed control using only the encoder is switched without using the belt scale sensor, the stored control amount is used. To control the motor that drives the belt. Thereby, a decrease in accuracy in controlling the belt surface speed is minimized.
Next, an embodiment of the belt conveyance device of the present invention will be described with reference to the drawings.

FIG. 1 is a front view illustrating an image forming apparatus as an example of an apparatus on which a belt conveying apparatus according to an embodiment of the present invention is mounted.
As shown, the image forming apparatus includes a paper feeding unit 1, an intermediate transfer unit 2, a photosensitive unit 3, a developing unit 4, a scanner unit 5, an image writing unit 6, a fixing unit 7, a secondary transfer roller 9, and a counter roller. 10, a transport unit 11, and a belt (intermediate transfer belt) 12.
The scanner unit 5 scans while irradiating a document with a light source, and reads image data from reflected light from the document by, for example, a 3-line CCD (Charge Coupled Device) sensor. The read image data is sent to the image writing unit 6 after performing image processing such as scanner γ correction, color conversion, image separation, and gradation correction processing in an image processing unit (not shown) as in the conventional case.

  The image writing unit 6 modulates an LD (laser diode) drive signal in accordance with the image data. The photosensitive unit 3 writes a latent image on a rotating photosensitive drum that is uniformly charged by a laser beam from the LD. The latent image written on the photosensitive drum is visualized by the toner attached by the developing unit 4. The toner image formed on the photosensitive drum is transferred to the surface of the belt 12 of the intermediate transfer unit 2.

  In the case of full color, that is, four color copies of black (Bk), cyan (C), magenta (M), and yellow (Y), image formation and transfer of toner images of four colors Bk, C, M, and Y When the process is completed, the transfer paper is fed from the paper feeding unit 1 in synchronism with the driving of the belt 12. A four-color toner image is secondarily transferred simultaneously from the belt 12 between the secondary transfer roller 9 and the opposing roller 10 of the paper transfer unit on the transfer paper. The transfer paper onto which the toner image has been transferred is sent to the fixing unit 7 through the conveying unit 11, and is thermally fixed by the fixing roller and the pressure roller and discharged.

FIG. 2 is an enlarged view of a main part near the intermediate transfer unit of the image forming apparatus.
The belt 12 is driven by an intermediate transfer motor (hereinafter simply referred to as a motor) 14. A gear reduction mechanism is provided between the motor 14 and the intermediate transfer belt drive roller (drive roller) 16a, and the motor drive shaft is transmitted to the drive roller 16a at a speed reduced by the gear ratio. It is configured.
The speed of the belt 12 is controlled so that the belt surface has a target speed and a constant speed based on the detection results of the encoder 15 provided on the belt driving roller shaft 15a and the belt scale sensor 13 which is a belt surface speed sensor. The In the figure, 16b is a driven roller, and 16c is a tension roller.

FIG. 3 is a block diagram schematically showing the belt drive control unit 17 and the main control unit 23 of the belt conveyance device mounted on the image forming apparatus of FIG.
The belt drive control unit 17 includes a driver 18 that drives the motor 14, a memory (also referred to as a storage unit or intermediate transfer (middle transfer) scale FB (feedback) memory) 22, and a CPU (Central Processing Unit) 19. The CPU 19 includes a control controller 20 and an average value calculation unit 21, and controls each unit constituting the belt drive control unit 17. The memory 22 stores a control amount such as an average value calculated by the average value calculator 21. The main control unit 23 includes a mode determination unit 25.

When a start signal, a rotation direction instruction signal, a linear speed (belt surface speed) instruction signal, etc. from the main control unit 23 are sent to the controller 20 of the belt drive control unit 17, the belt drive control unit 17 is driven by the driver 18 with the motor 14. Drive.
The controller 20 calculates the speed of the motor 14 based on the detection result of the encoder 15 of the belt driving roller shaft 15a and the belt scale sensor 13, that is, the speed signal, and sends an output corresponding to the calculation result to the driver 18. That is, the controller 20 controls the belt surface speed to be a target speed and constant by feedback control.

  The mode determination unit 25 performs control (belt scale FB) that performs feedback control using both the belt scale sensor 13 and the encoder 15 with respect to the control mode of the belt conveying device, that is, control of the belt surface speed, in accordance with a user instruction or automatically. (Feedback) control) or a control mode (also referred to as alternative control) performed using only the encoder 15 without using the belt scale sensor 13 is determined.

That is, in the belt conveyance device according to the embodiment of the present invention, the belt scale sensor 13 and the second detection corresponding to the first detection unit of the present invention are indicated by the mode instruction determined by the mode determination unit 25 of the main control unit 23. It is determined whether to perform feedback control using the encoder 15 corresponding to the unit or control of the rotational speed of the drive roller 16a by the motor 14 using only the encoder 15.
The thermistor 24 is not provided in the belt conveyance devices of the first and second embodiments, but is provided in the belt conveyance devices of the third and fourth embodiments, and measures the temperature around the belt or around the belt driving roller.

Here, prior to the description of the embodiment of the present invention, a configuration for controlling the rotational speed of the drive roller 16a including the belt scale sensor 13 and the encoder 15 will be described as a prerequisite technology.
FIG. 4 is a block diagram showing the configuration of the controller 20 and its surroundings, which are the prerequisite technology of the present invention.
In accordance with the processing flow, the controller 20 includes a first calculation unit 201, an integrator 1 / S202, a position controller 203, a major loop output switching unit 204, a second calculation unit 205, a speed controller 206, and a PWM (Pulse Width Modulation) conversion unit 207 is provided.
In the figure, the major loop is a loop that feeds back the detection result of the belt scale sensor 13, and the minor loop is a loop that feeds back the detection result of the encoder 15.

  The first calculation unit 201 calculates a speed deviation with respect to the first target speed from the target speed (first target speed) of the surface of the belt 12 from the main control unit 23 or the CPU 19 and the detection result (belt scale speed) of the belt scale sensor 13. (First deviation) is calculated, and the calculated speed deviation is output to the integrator 1 / S202. The integrator 1 / S202 integrates the calculation result of the first calculation unit 201 to calculate (convert) the position deviation. Next, the position deviation calculated by the integrator 1 / S202 is input to the position controller 203.

The output of the position controller 203 (referred to herein as data A) is sent to the second calculation unit 205 via the switching unit 204 that switches the major loop output (signal) from the contact X to the contact Y side.
The second calculation unit 205 adds the output (data A) of the position controller 203 and the first target speed. The value added here becomes the target speed of the driving roller 16a. Next, a speed deviation (first target speed) obtained from the target speed of the drive roller 16a and the detected speed of the encoder 15 (the speed obtained by converting the rotational speed of the belt drive roller shaft 15a detected by the encoder into the rotational speed of the drive roller 16a). + Data A−encoder detection speed; here, data B) is input to the speed controller 206.

  The speed controller 206 changes the control output voltage for the motor 14 so that the rotational speed of the drive roller 16a approaches the target speed in accordance with the data B (speed deviation: second deviation) received from the second calculation unit 205. Control. That is, the output obtained by the speed controller 206 becomes the control output voltage instruction value to the motor 14. Next, the obtained voltage instruction value is converted into a PWM output (pulse) by the PWM conversion unit 207 and output to the driver 18 to drive the motor 14.

Here, the controller 20 including the speed controller 206 and the PWM converter 207 corresponds to the controller of the present invention.
The position controller 203 and the speed controller 206 are general control controllers designed based on the frequency response results with the input voltage of the motor 14 as an input and the encoder signal and the belt scale signal as outputs.

The switching unit 204 switches the contacts X and Y by an input signal from the main control unit 23 or the CPU 19, and uses only the speed control (belt scale FB control) using both the belt scale sensor 13 and the encoder 15 and the encoder 15. Switch speed control (alternative control).
Here, the reason why the switching unit 204 is switched to the contact Y side is that, for example, the belt scale sensor 13 that detects the surface speed of the belt cannot be used or is not used because of an abnormality in the belt scale sensor 13 or the like. This is because the surface speed of the belt 12 may be controlled based only on the detected speed of the encoder 15.

However, if the switching unit 204 is switched to the contact Y side and the rotational speed control of the driving roller 16a is performed only by the encoder 15 without using the belt scale sensor 13, the influence is generally generated.
As an influence when the belt surface speed detection is not performed, for example, the surface speed of the driving roller 16a may become higher than usual (speed that is originally desired to be controlled) due to the expansion of the driving roller 16a due to a temperature change. Conceivable.
That is, the rotational speed (surface speed) of the driving roller 16a is represented by V = rω (where V: surface speed, r: radius of the driving roller 16a, ω: angular speed). Even if the angular velocity ω is constant, the surface velocity V changes. That is, even if the encoder 15 detects the angular velocity and performs control to keep the value constant, the rotational speed of the drive roller 16a cannot be kept constant.

FIG. 5 is a diagram illustrating the influence when the belt surface speed is not detected, that is, when the control is performed only by the encoder 15.
FIG. 5A (1) is a diagram extracted from FIG. 1 in the vicinity of the intermediate transfer portion of the image forming apparatus at a normal temperature (for example, a predetermined room temperature), and FIG. 5A (2) is the same as when the temperature is higher than the normal temperature. FIG. 5B is a graph showing the temperature difference in that case, with the belt surface speed on the vertical axis and time on the horizontal axis.
As shown in FIG. 5B, when the drive roller 16a expands, the rotational speed of the drive roller 16a, and hence the belt surface speed, becomes higher than usual.
Next, Embodiments 1 to 4 of the present invention that solve such problems of the prerequisite technology will be described.

(Embodiment 1)
FIG. 6 is a block diagram schematically showing the configuration of the controller 20 and its peripheral part in the belt conveying apparatus of the first embodiment.
6A shows a state in which the switching unit 204 is switched to the contact X side to perform speed control (belt scale FB control) using the belt scale sensor 13 and the encoder 15, and FIG. 6B shows the switching unit 204 to the contact Y side. It is a block diagram in the case of switching and performing speed control (alternative control) only with the encoder 15.
This block diagram corresponds to the block diagram of FIG. 4 with the addition of the average value calculation unit 21 and the memory 22 corresponding to the storage unit of the present invention. Therefore, the same parts as those in FIG. This block diagram is common to the third embodiment described later.

In the belt conveying apparatus of the first embodiment, the average value of the output (data A) of the position controller 203 over a certain period in the state of FIG. 6A is calculated by the average value calculation unit 21 and stored in the memory 22.
When the speed control (alternative control) using only the encoder 15 is instructed as the mode, the switching unit 204 is switched to the contact Y side, and the position controller 203 stored in the memory 22 in the state of the block diagram of FIG. The average value of the output (data A) is read and the rotation speed of the drive roller 16a is controlled.
That is, when the mode determination unit 25 of the main control unit 23 shown in FIG. 3 instructs control using only the encoder 15, the CPU 19 switches the major loop output switching unit 204 from the normal contact X to the contact Y. The position is switched to (position controller output = 0), and the average value of the data A stored in the memory 22 is used as the target speed of the driving roller 16a.

  In this case, the second calculating unit 205 calculates a speed deviation (second deviation; data B) between the target speed of the driving roller 16a and the rotational speed of the driving roller 16a detected by the encoder. In accordance with data B received from the calculation unit 205, control is performed to change the control output voltage for the motor 14 so that the rotational speed of the drive roller 16a approaches the target speed of the drive roller 16a. That is, the output obtained by the speed controller 206 becomes the control output voltage instruction value to the motor 14. Next, the obtained voltage instruction value is converted into a PWM output (pulse) by the PWM conversion unit 207 and output to the driver 18 to drive the motor 14.

Next, a processing procedure for storing the average value of the data A in the belt conveyance device of the first embodiment will be described with reference to FIG.
FIG. 7 is a flowchart illustrating a processing procedure for storing an average value of data A in the belt conveyance device of the first embodiment.
This processing procedure is executed by the CPU 19 in FIG. That is, (i) the state of the motor 14 is not a period from stop to start (S101, no), (ii) the state of the motor 14 is not a period from start to stop (S102, no), and (iii) the motor 14 is active (S103, yes), and (iv) is a mode in which the belt conveyance device performs FB control (belt scale FB control) using the belt scale sensor 13 (S104, yes), and (v) data acquisition. When the count value of a timer (hereinafter simply referred to as a timer) exceeds a certain period X from the start (S105, yes), that is, data A is acquired every certain period of the timer (S106).

  When data A is acquired, the timer is cleared (S107). That is, the data A is acquired every fixed period of the timer, and the timer is cleared each time. If the number of data A acquired is equal to or greater than the predetermined value N (S108, yes), the average value calculation unit 21 calculates an average value of N pieces of data A (S109). Next, the calculated average value of the N pieces of data A is stored in the memory 22 (S110), the number of acquired data A is cleared (S111), and the process returns to the start.

In the above processing procedure, if the state of the motor 14 is in the period from stop to start in step S101 (S101, yes), the timer is started (S112) and the process returns to the start.
If the state of the motor 14 is in the period from start to stop in step S102 (S102, yes), the timer is cleared and stopped (S113), the data A acquisition number is cleared (S114), and the process returns to the start.
In step S103, if the motor 14 is not in the activated state (S103, no), that is, since it is not operating at all, the process returns to the start.
In step S104, if the belt conveyance device is not in the mode for performing the belt scale FB control (S104, no), the process returns to the start.

In step S105, if the count value of the timer is before the lapse of a certain period X (S105, no), the timer is counted up (S115) and the process returns to the start.
If the data A acquisition number is less than the predetermined value N in step S108 (S108, no), the data A acquisition number is counted up (S116), and the process returns to the start.
The timer count value X and the predetermined value N of the data A acquisition number can be arbitrarily set according to the state of the belt conveyance device.

  As described above, in the belt conveyance device of the present embodiment, the state of the motor is not starting up or ending operation, the timer count value has elapsed for a certain period X, and the start-up is stable, and Only when the mode is performing the belt scale FB control, a predetermined number of data A are acquired and the average value is obtained. That is, when the number of acquisitions of data A reaches a certain number N, the average value calculation unit 21 calculates the average value of N pieces of data A and stores the calculation result in the data A average value storage area of the memory 22. . Thereafter, the number of data A acquired is cleared, N pieces of data A are acquired again, and the process of overwriting the calculation result of the average value in the data A average value storage area of the memory 22 is repeated.

Next, the mode selection process at the start-up in the belt conveyance device of the first embodiment will be described.
FIG. 8 is a flowchart showing a mode selection processing procedure at the time of start-up in the belt conveyance device of the first embodiment.
In the belt conveyance device of the first embodiment, the motor 14 is activated (S201, yes), and when the belt conveyance device performs belt scale FB control (S202, yes), the major loop output of FIG. Is set (switched) to the normal contact X side. As a result, the data A is used as the feedback value (S203), and this process ends.

If it is not the belt scale FB control in step S202 (S202, no), the switching unit 204 is set (switched) to the contact Y side as shown in FIG. 6B, and the average of the data A stored in the memory 22 is set. The value is used instead of the major loop output (S204), and the process is terminated.
Since the average value of data A reflects the belt scale speed during normal (or normal) operation, it is possible to minimize the influence of fluctuations in the surface speed due to expansion of the drive roller, etc. that occurs in the case of alternative control. it can.

(Embodiment 2)
FIG. 9 is a block diagram schematically illustrating the configuration of the controller 20 of the belt conveyance device according to the second embodiment and its peripheral portion.
FIG. 9 is different from the controller 20 of the belt conveyance device of Embodiment 1 shown in FIG. 6 in that the position of the switching unit 204 is replaced with the second calculation unit 205, and the other configurations are the same. Therefore, the same parts as those in FIG. 3 are denoted by the same reference numerals, and the description thereof is omitted here.
9A and 9B correspond to FIGS. 6A and 6B, and show different contact setting (switching) states of the switching unit 204, respectively. Also, these block diagrams are the same as those in Embodiment 4 described later.

  In the controller 20 of the belt conveyance device of the second embodiment, the average value of the detection output values (output of the position controller 203 (data A) + first target speed−encoder detection speed; data B) for a certain period is stored in the memory 22. When the alternative control (substitute control of the belt scale FB control) is instructed by the mode determination unit 25 shown in FIG. 3, the speed control of the belt surface speed (or the belt conveyance speed) is performed using the average value of the data B. I do.

When performing alternative control, as shown in FIG. 9B, the switching unit 204 of the controller 20 is switched from the normal contact X to the contact Y, and the average value of the data B stored in the memory 22 is changed to the speed controller 206. Use as input value.
In the second embodiment, when the switching unit 204 is switched from the normal contact X to the contact Y, constant voltage control is performed and feedback control is not performed. Therefore, it is generally considered that Embodiments 1 and 3 can maintain the accuracy of the belt surface speed. However, for example, when the primary transfer belt and the secondary transfer belt overlap each other and interfere with each other to prevent major loop control (belt scale FB control) on one side, the belt can be controlled by encoder control (alternative control). Rather than performing drive roller shaft speed control, the belt speed itself is a constant voltage control that generates a constant speed with a stored value, and a control that makes the belt surface speed follow the other belt speed that interferes to some extent. May maintain accuracy. That is, it can be considered not to actively control the rotational speed of the drive shaft on which the belt scale FB control cannot be performed.

FIG. 10 is a flowchart illustrating a processing procedure for storing an average value of data B in the belt conveyance device according to the second embodiment.
The processing procedure for storing the average value of data B in the second embodiment is basically the same as the processing procedure shown in FIG. 7, but in the processing procedure shown in FIG. 7, the data to be acquired is data A (position controller). In the second embodiment, the acquired data is the data B (velocity deviation) shown in FIGS. 4A and 4B.

  This processing procedure is also executed by the CPU 19 in FIG. That is, (i) the state of the motor 14 is not a period from stop to start (S301, no), (ii) the state of the motor 14 is not a period from start to stop (S302, no), (iii) the motor 14 is in operation (S303, yes), (iv) is a mode in which the belt conveying device performs belt scale FB control (S304, yes), and (v) counts a data B acquisition timer (hereinafter simply referred to as a timer). When the value exceeds a certain period X from the start (S305, yes), data B is acquired every certain period of the timer (S306).

  After acquiring data B in this way, the timer is cleared (S307). Here, if the acquisition number of the data B is equal to or greater than the predetermined value N (S308, yes), the average value calculation unit 21 calculates the average value of the N pieces of data B (S309). Next, when the average value of the calculated N pieces of data B is stored in the memory 22 (S310), the data B acquisition number is cleared (S311), and the process returns to the start.

In the above processing procedure, if the state of the motor 14 is the period from the stop to the start in step S301 (S301, yes), the timer is started (S312) and the process returns to the start.
In step S302, if the state of the motor 14 is a period from start to stop (S302, yes), the timer is cleared and stopped (S313), the data B acquisition number is cleared (S314), and the process returns to the start. .
In step S303, if the state of the motor 14 is not the activated state (S303, no), that is, it is not operating at all, so the process returns to the start.
In step S304, if the belt conveying device is not in the mode for performing the belt scale FB control (S304, no), the process returns to the start.

In step S305, if the count value of the timer is before the lapse of the predetermined period X (S305, no), the timer is increased (S315) and the process returns to the start.
In step S308, if the data B acquisition number is less than the predetermined value N (S308, no), the data B acquisition number is counted up (S316), and the process returns to the start.
Note that the timer count value X and the predetermined value N of the number of data acquisition can be arbitrarily set according to the state of the belt conveyance device.

FIG. 11 is a flowchart illustrating a mode selection processing procedure at the time of start-up in the belt conveyance device of the second embodiment.
The basic processing procedure is the same as the processing procedure for mode selection at the time of activation in the first embodiment shown in FIG.
In the belt conveyance device of the second embodiment, the motor 14 is being activated (S401, yes). At that time, when performing the belt scale FB control (S402, yes), as shown in FIG. Is set (switched) to the normal contact X side. As a result, the data B as the feedback value is used as the control amount for this feedback control (S403), and this process is terminated.

  If the belt scale FB control is not performed in step S402 (S402, no), the average value of the data B stored in the memory 22 is used as the control amount data (S404), and this process ends. . Thereby, the fluctuation | variation of the surface speed by expansion | swelling of the driving roller etc. which generate | occur | produce at the time of alternative control can be suppressed.

  That is, it is determined whether or not the control using the memory 22 (alternative control) is performed when the motor 14 is started, and when performing the belt scale FB control, the switching unit 204 is set to the normal contact X side as shown in FIG. 9A. Data B is used. When the belt scale FB control is not performed, the switching unit 204 is switched to the contact Y side as shown in FIG. 9B and the average value of the data B stored in the memory 22 is used.

FIG. 12 is a diagram showing an example of setting a data storage area for each temperature in the memory.
12A and 12B are examples of the memory 22 in the third and fourth embodiments, respectively.
In the third and fourth embodiments, it is necessary to store data A (third embodiment) and data B (fourth embodiment) in the memory 22 according to the temperature measured by the thermistor 24. Therefore, the data A or B is stored for each temperature. An area to save is prepared.
That is, in FIGS. 12A and 12B, the temperature range is divided and set (in this case, ˜20 ° C., 20-30 ° C., 30-40 ° C., 40 ° C., etc.). Are stored in different memory areas (addresses).

(Embodiment 3)
FIG. 13 is a flowchart illustrating a processing procedure for storing an average value of data A in the belt conveyance device of the third embodiment.
In the present embodiment, the processing procedure up to the calculation of the average value of data A in step S509 is the same as the processing procedure in FIG. 7 of the first embodiment, but the calculated average value depends on the temperature of the thermistor 24 at the time of calculation. Thus, the processing procedure of the first embodiment is different in that any one of the memory areas E to H is selected and stored.
This processing procedure is executed by the CPU 19 in FIG. That is, (i) the state of the motor 14 is not a period from stop to start (S501, no), (ii) the state of the motor 14 is not a period from start to stop (S502, no), (iii) the motor 14 is in operation (S503, yes), (iv) is a mode in which the belt conveying device performs belt scale FB control (S504, yes), and (v) the count value of the timer has exceeded a certain period X from the start. If so (S505, yes), data A is acquired at regular intervals of the timer (S506).

  After acquiring data A in this way, the timer is cleared (S507). Here, if the number of data A acquired is equal to or greater than the predetermined value N (S508, yes), the average value calculation unit 21 calculates the average value of the N pieces of data A (S509). Next, when the results are stored in the memory areas E to H according to the temperature at the time of calculation (S510), the data A acquisition number is cleared (S511), and the process returns to the start.

In the above processing procedure, if the state of the motor 14 is a period from stop to start in step S501 (S501, yes), the timer is started (S512) and the process returns to the start.
In step S502, if the state of the motor 14 is a period from start to stop (S502, yes), the timer is cleared and stopped (S513), the number of data A acquisitions is further cleared (S514), and the process returns to the start. .
In step S503, if the motor 14 is not in the activated state (S503, no), that is, since it is not operating at all, the process returns to the start.
In step S504, if the belt conveying apparatus is not in the mode for performing the belt scale FB control (S504, no), the process returns to the start.

In step S505, if the count value of the timer is before the lapse of the predetermined period X (S505, no), the timer is counted up (S515), and the process returns to the start.
If the number of acquisitions of data A is less than the predetermined value N in step S508 (S508, no), the number of acquisitions of data A is counted up (S516), and the process returns to the start.
Note that the timer count value X and the predetermined value N of the number of data acquisition can be arbitrarily set according to the state of the belt conveyance device.

  That is, when the number of data acquisition reaches a certain number N, the average value calculation unit 21 calculates an average value of N data and stores the calculation result in the data A average value storage area of the memory 22. Thereafter, the acquisition number of data A is cleared, N pieces of data A are acquired again, and the process of overwriting the calculation result of the average value in the data A average value storage area of the memory 22 is repeated.

FIG. 14 is a flowchart illustrating a mode selection processing procedure at the time of start-up in the belt conveyance device of the third embodiment.
In the belt conveyance device of the third embodiment, the motor is being activated (S601, yes), and when the belt conveyance device performs belt scale FB control (S602, yes), as shown in FIG. 6A. Then, the output of the major loop is set to the normal contact X side by the switching unit 204, and the data uses the data A which is a feedback value (S603), and this processing is terminated.
If the belt scale FB control is not performed in step S602 (S602, no), the current temperature is detected (S604), and the data A average value stored in the memory 22 is switched according to the temperature (S605). finish.

That is, in the present embodiment, when the motor 22 is activated, it is determined whether or not the control is to use the memory 22, and when the belt scale FB control is performed, as shown in FIG. Set to contact X side and use data A. When the belt scale FB control is not performed, the data A average value stored in the memory 22 is used in place of the major loop output. This data A average value depends on the temperature of the thermistor 24 when an abnormality occurs. The stored value is used as a controlled variable according to the current temperature.
In this way, by using the data A average value corresponding to the temperature, for example, an average value corresponding to the degree of expansion of the drive roller can be used, and fluctuations in the belt surface speed can be minimized.

(Embodiment 4)
FIG. 15 is a flowchart illustrating a processing procedure for storing an average value of data B in the belt conveyance device of the fourth embodiment.
The processing procedure up to the calculation of the average value of data B in step S709 of this processing procedure is the same as that of the second embodiment shown in FIG. 10, but the calculated average value is stored in the memory area according to the temperature of the thermistor 24 at the time of calculation. The second embodiment is different from the second embodiment in that any one of I to L is selected and stored.

  This processing procedure is executed by the CPU 19 in FIG. That is, (i) the state of the motor 14 is not a period from stop to start (S701, no), (ii) the state of the motor 14 is not a period from start to stop (S702, no), (iii) the motor 14 is in operation (S703, yes), (iv) the belt conveyance device is in a mode in which the belt scale FB control is performed (S704, yes), and (v) the count value of the timer has exceeded a certain period X from the start. If so (S705, yes), the data B is acquired at regular intervals of the timer (S706).

  After acquiring the data B in this way, the timer is cleared (S707). Here, if the acquisition number of the data B is equal to or greater than the predetermined value N (S708, yes), the average value calculation unit 21 calculates the average value of the N pieces of data B (S709). Next, when the results are stored in the memory areas I to L according to the temperature at the time of calculation (S710), the data B acquisition number is cleared (S711), and the process returns to the start.

In the above processing procedure, if the state of the motor 14 is the period from the stop to the start in step S701 (S701, yes), the timer is started (S712) and the process returns to the start.
In step S702, if the state of the motor 14 is a period from start to stop (S702, yes), the timer is cleared and stopped (S713), the data B acquisition number is cleared (S714), and the process returns to the start. .
In step S703, if the motor 14 is not in the activated state (S703, no), that is, since it is not operating at all, the process returns to the start.
In step S704, if the belt conveyance device is not in the mode for performing the belt scale FB control (S704, no), the process returns to the start.

In step S705, if the timer count value is before the lapse of the predetermined period X (S705, no), the timer is counted up (S716) and the process returns to the start.
In step S708, if the number of acquisitions of data B is less than the predetermined value N (S708, no), the number of acquisitions of data B is counted up (S716), and the process returns to the start.
Note that the timer count value X and the predetermined value N of the number of data B acquisitions can be arbitrarily set according to the state of the belt conveyance device.

FIG. 16 is a flowchart illustrating a mode selection processing procedure at the time of activation in the belt conveyance device of the fourth embodiment.
In the belt conveyance device of the fourth embodiment, when the motor is activated (S801, yes), and when the belt scale FB control is performed (S802, yes), the switching unit 204 is connected to the normal contact point as shown in FIG. 9A. The data is set (switched) to the X side, and the data uses the data B that is a feedback value (S803), and the process is terminated.
If the belt scale FB control is not performed in step S802 (S802, no), the current temperature is detected (S804), the data B average value stored according to the temperature is switched to use (S805), and the process is terminated.

  In other words, in this embodiment, when the motor 22 is activated and it is determined whether or not the control is to use the memory 22, and the belt scale FB control is performed, the minor loop output is set to the normal contact X side as shown in FIG. 9A. Set and use. When the belt scale FB control is not performed, the data B average value stored in the memory 22 is used instead of the minor loop output. In this case, for the data B average value, the value stored according to the temperature of the thermistor 24 at the time of occurrence of an abnormality or the like is used according to the current temperature.

Thus, by using the data B average value corresponding to the temperature, for example, an average value corresponding to the degree of expansion of the drive roller can be used, and fluctuations in the belt surface speed can be minimized.
As described above, according to the embodiment of the present invention, the average value of the control amount calculated by the control controller (average value calculation unit) based on the detection result of the normal position deviation is stored, and the mode is switched. By controlling the motor using the control amount stored when performing control using only the encoder sometimes, a decrease in accuracy of the belt surface speed can be minimized.

  In the above description, the control value corresponding to data A or data B is an average value, but is not necessarily limited to this. For example, another control value such as an intermediate value may be used. Further, although the belt conveying device has been described as having an intermediate transfer belt for conveying a toner image, the belt conveying device is not necessarily limited thereto. For example, it may have a photosensitive belt that conveys at least one of a latent image and a toner image, or a conveyance belt that conveys a sheet-like medium such as paper or a document.

  Further, the image forming apparatus may be connected to a DFE (Digital Front End) via a dedicated line so as to be communicable. The DFE may have a function as a raster image processor, for example, and may generate a raster image based on an image received from a PC (Personal Computer). A raster image or the like may be transmitted to the image forming apparatus. The image forming apparatus and the DFE may be connected via a network. Further, the image forming apparatus may have a function as a raster image processor and generate raster image data.

The memory and the average value calculation unit may be provided individually in the image forming apparatus. When the image forming apparatus is connected to the DFE, the memory and the average value calculation unit may be provided in the DFE, and a part thereof is provided in the DFE and the remaining part is provided in the image forming apparatus. Also good. In this case, an image forming system is configured together with the image forming apparatus.
In addition, the components constituting the control controller may be configured by software or hardware.

  DESCRIPTION OF SYMBOLS 1 ... Paper feed part, 2 ... Intermediate transfer part, 3 ... Photoconductor unit, 4 ... Development unit, 5 ... Scanner part, 6 ... Image writing unit, 7 ... Fixing unit, 9 ... secondary transfer roller, 10 ... opposite roller, 11 ... conveying unit, 12 ... (intermediate transfer) belt, 13 ... belt scale sensor, 14 ... (intermediate) Transfer) motor, 15 ... encoder, 15a ... belt drive roller shaft, 16a ... drive roller, 16b ... driven roller, 16c ... tension roller, 17 ... belt drive controller, 18・ ・ ・ Driver, 19 ... CPU, 20 ... Control controller, 21 ... Average value calculation unit, 22 ... Memory, 23 ... Main control unit, 24 ... Thermistor, 25 ... A mode determination unit, 201 ... a first calculation unit, 02 ... integrator 1 / S, 203 ... position controller, 204 ... switching unit, 205 ... second calculation unit, 206 ... rate controller, 207 ... PWM conversion unit.

JP 2004-220006 A JP 2009-222112 A

Claims (7)

A driving roller that rotates to drive the belt;
A first detector for detecting the speed of the surface of the belt to be driven;
A second detector for detecting the rotational speed of the drive roller;
A first calculation unit that calculates a first deviation with respect to the target speed based on the target speed of the belt and the speed of the surface of the belt;
A storage unit for storing a control value corresponding to the first deviation;
A second calculation unit that calculates a second deviation with respect to the target speed based on the target speed, the first deviation, and the rotation speed;
A control unit for controlling the rotational speed of the drive roller based on the second deviation;
A mode determination unit for determining a control mode of the rotational speed of the drive roller, a mode using the first detection unit and the second detection unit, and a mode not using the first detection unit;
A switching unit that switches the first deviation in the calculation of the second deviation by the second calculation unit to the control value when the mode determination unit determines a mode that does not use the first detection unit;
A belt conveyance device comprising: A driving roller that rotates to drive the belt;
A first detector for detecting the speed of the surface of the belt to be driven;
A second detector for detecting the rotational speed of the drive roller;
A first calculation unit that calculates a first deviation with respect to the target speed based on the target speed of the belt and the speed of the surface of the belt;
A second calculation unit that calculates a second deviation with respect to the target speed based on the target speed, the first deviation, and the rotation speed;
A storage unit for storing a control value corresponding to the second deviation;
A control unit for controlling the rotational speed of the drive roller based on the second deviation;
A mode determination unit for determining a control mode of the rotational speed of the driving roller, one of a mode using the first detection unit and the second detection unit and a mode not using the first detection unit;
A switching unit that switches the second deviation in the calculation of the second deviation by the second calculation unit to the control value when the mode determination unit determines a mode that does not use the first detection unit;
A belt conveyance device comprising: In the belt conveyance device according to claim 1,
A temperature detection unit that stores a control value corresponding to the first deviation in a storage area corresponding to a detection result of the temperature detection unit; in a mode not using the first detection unit, the control value is stored according to the temperature; A belt conveyance device using a control value corresponding to the first deviation. In the belt conveyance device according to claim 2,
A temperature detection unit that stores a control value corresponding to the second deviation in a storage area corresponding to a detection result of the temperature detection unit; in a mode not using the first detection unit, the control value is stored according to the temperature; In addition, a belt conveyance device using a control value corresponding to the second deviation. It has the belt conveyance device according to any one of claims 1 to 4,
The image forming apparatus, wherein the belt conveys at least one of a toner image, a latent image, and a sheet-like medium. An image forming system including an image forming apparatus and a storage unit,
The image forming apparatus includes:
A driving roller that rotates to drive the belt;
A first detector for detecting the speed of the surface of the belt to be driven;
A second detector for detecting the rotational speed of the drive roller;
A first calculation unit that calculates a first deviation with respect to the target speed based on the target speed of the belt and the speed of the surface of the belt;
A second calculation unit that calculates a second deviation with respect to the target speed based on the target speed, the first deviation, and the rotation speed;
A control unit for controlling the rotational speed of the drive roller based on the second deviation;
A mode determination unit for determining a control mode of the rotational speed of the drive roller, a mode using the first detection unit and the second detection unit, and a mode not using the first detection unit;
A switching unit that switches the first deviation in the calculation of the second deviation by the second calculation unit to the control value when the mode determination unit determines a mode that does not use the first detection unit;
Have
The image forming system, wherein the storage unit stores a control value corresponding to the first deviation. An image forming system including an image forming apparatus and a storage unit,
The image forming apparatus includes:
A driving roller that rotates to drive the belt;
A first detector for detecting the speed of the surface of the belt to be driven;
A second detector for detecting the rotational speed of the drive roller;
A first calculation unit that calculates a first deviation with respect to the target speed based on the target speed of the belt and the speed of the surface of the belt;
A second calculation unit that calculates a second deviation with respect to the target speed based on the target speed, the first deviation, and the rotation speed;
A control unit for controlling the rotational speed of the drive roller based on the second deviation;
A mode determination unit for determining a control mode of the rotational speed of the drive roller, a mode using the first detection unit and the second detection unit, and a mode not using the first detection unit;
A switching unit that switches the second deviation in the calculation of the second deviation by the second calculation unit to the control value when the mode determination unit determines a mode that does not use the first detection unit;
Have
The image forming system, wherein the storage unit stores a control value corresponding to the second deviation.

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