JP2007033723A - Belt driving device, image forming apparatus and copying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve the smooth driving of a belt, to prevent abnormality in belt driving caused by the load of the belt and to avoid malfunction in the belt driving caused by the variance of the rising speed of an additional roller coming into contact with the belt. <P>SOLUTION: The belt driving device is equipped with: a driving roller 14 supporting the belt 10; a belt driving motor 14m driving and rotating the driving roller 14; moving signal generating means 5s, 6t and 6tP generating a belt moving synchronizing signal St; first control means 14d and 14p controlling the driving of the belt driving motor so as to attain target speed Vo1 after starting the belt driving motor; the additional roller 22 abutting on the belt; an additional roller driving motor 22m; and second control means 22d and 22p controlling the driving of the motor 22m and increasing the rotating speed of the motor 22m interlocked with the increase of the belt speed based on the moving synchronizing signal St during the starting of the belt driving motor 14m. A current value nearly in proportion to the belt speed is applied to the motor 22m. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to drive control of a belt supported by a belt drive roller, and in particular, belt drive in which an additional roller is in contact with the belt and the belt drive control is likely to be disturbed by fluctuations in the rotation speed of the additional roller. It relates to the improvement of the apparatus. The present invention is not intended to be limited to this, but can be used, for example, in printers, copiers, and facsimile machines.

  2. Description of the Related Art Conventionally, for example, a belt speed control device that controls movement of an intermediate transfer belt of an image forming apparatus has a tape-like scale formed on the intermediate transfer belt at a regular interval along a circumferential direction with a tape-like scale formed on the belt surface. Affixed in the vicinity of the side edge, each scale (mark) on the scale is detected by one sensor (reflective photosensor), and the belt speed is detected from the detection signal so that the belt speed becomes the target speed. Further, the rotational speed of the belt drive motor is feedback controlled (constant speed control), so that the intermediate transfer belt is moved at an ideal speed (constant speed).

JP 2004-191845 A JP 2005-99728 A.

  In Patent Document 1, in order to prevent fluctuation of the belt speed of the feedback control due to discontinuity of the scale mark when the seam of the scale on the endless belt passes through the scale sensor position, per scale seam on the endless belt is disclosed. A home mark sensor for detecting the home mark, and a motor control output of a controller that drives the motor so that the speed represented by the scale mark detection signal of the scale sensor matches the target speed. While the home mark sensor is not detecting the home mark, it is stored in the speed memory, and while the home mark sensor is detecting the home mark, a belt driving device that drives the motor with the motor control output of the speed memory is provided. Are listed. Patent Document 2 describes a belt driving device and an image forming apparatus that generate an alarm when scale mark reading becomes inaccurate due to scale deterioration.

  By the way, the intermediate transfer belt is supported by a driving roller that drives the intermediate transfer belt and a driven roller that stretches and supports the belt, and the belt includes a primary transfer roller that transfers a toner image on the photosensitive member to the belt, and The secondary transfer roller that transfers the toner image transferred to the belt to the paper (transfer paper) comes into contact, but during the start-up period from the start of driving the intermediate transfer belt to near the target speed, a belt drive motor that rotationally drives the drive roller In this period, the most torque is required, and if another roller that contacts the intermediate transfer belt, such as a driven roller or a transfer roller, does not match the speed of the intermediate transfer belt within this period, The start-up speed is unstable due to a large load or the intermediate transfer belt speed becomes higher than the target drive speed of the belt speed controller. Now, the transition to the feedback control becomes unstable from the rising.

  That is, when shifting from an unstable rising speed to feedback control, when the rising speed of the roller contacting the intermediate transfer belt is slower than that of the intermediate transfer belt, the load is large and an overcurrent flows to the belt drive motor, and the motor drive stops. End up. Further, when the speed of the roller contacting the intermediate transfer belt is high, the load is reduced, so that the current to the belt driving motor is controlled to be lowered. Since the intermediate transfer belt is actually driven not by a belt drive motor but by a driving roller that is in contact with the intermediate transfer belt, the intermediate transfer belt speeds up due to irregularities in which feedback control does not work normally. The belt drive motor will be stopped.

  For example, FIG. 12 is a graph showing the trajectory until the motor drive at the time of startup is stabilized. Specifically, as shown in FIG. 12, when the rise of the peripheral speed of the secondary transfer roller is slower than the peripheral speed (belt speed) of the drive roller, the friction load of the intermediate transfer belt is correspondingly increased. The load torque of the belt drive motor that rotates the belt increases more than necessary, and an excessive current flows through the motor. The belt drive control device determines that there is an abnormality and stops the belt drive motor. In addition, the transfer belt is slack between the upstream drive roller and the downstream secondary transfer roller in the belt moving direction. As a result, problems such as scratches on the transfer belt may occur, leading to image distortion. Conversely, when the speed of the secondary transfer roller is faster than that of the drive roller, the load torque of the motor rotating the drive roller becomes unnecessarily small, and the drive current value decreases and the feedback controller or motor driver becomes It is judged as an abnormal situation, and control becomes impossible or the belt drive motor is stopped.

  The first object of the present invention is to smoothly drive the belt, and the second object is to prevent an abnormality in the belt driving due to the belt load, and the belt driving due to the variation in the rising speed of the additional roller contacting the belt. The third object is to avoid the malfunction.

(1) A driving roller (14) for supporting and driving the belt (10);
A belt drive motor (14 m) for rotationally driving the drive roller;
Movement signal generating means (5s, 6t, 6tP) for generating a movement synchronization signal (St) indicating movement of a predetermined short distance in synchronization with movement of the belt by the transfer drive;
First control means (14d, 14p) for controlling the driving of the belt driving motor so that the moving speed of the belt (10) becomes the target speed (Vo1) after starting the belt driving motor;
An additional roller (22) contacting the belt;
An additional roller drive motor (22m) for rotationally driving the additional roller; and
Based on the movement synchronization signal (St) during the start of the belt drive motor (14m), the drive of the additional roller drive motor (22m) is controlled, and the additional roller drive is interlocked with the increase in the belt moving speed. Second control means (22d, 22p) for increasing the rotational speed of the motor (22m);
A belt drive device comprising:

  In addition, in order to facilitate understanding, in parentheses, reference numerals or equivalent matters of corresponding elements of the embodiments shown in the drawings and described later, or corresponding elements, or corresponding matters are added for reference. The same applies to the following.

  During the start of the belt drive motor (14m), the second control means (22d, 22p) is connected to the additional roller drive motor (in accordance with the increase in the belt speed based on the movement synchronization signal (St) of the belt (10). Since the rotational speed of 22m) is increased, the peripheral speed of the additional roller (22) does not become too low or too high. That is, the additional roller (22) does not become an excessive load with respect to the belt movement and does not become an abnormal speed increaser. The speed difference between the rollers during the start-up period in which the two motors (14 m, 22 m) are started up can be minimized. Stable start-up control can be performed.

  (2) The second control means (22d, 22p) energizes the additional roller drive motor (22m) with a current value corresponding to the belt moving speed during the activation of the belt drive motor (14m); The belt driving device according to 1).

  (2a) The second control means (22d, 22p) includes a memory (startup table) that holds target current value data addressed to each region of the belt movement speed in a plurality of regions, The belt drive device according to (2), wherein the target current value data is read and the drive current of the additional roller drive motor (22m) is controlled to a value represented by the target current value data.

  (3) The belt drive device further includes rotation signal generating means (6e, 6eP) for generating a rotation synchronization signal (Se) having a frequency proportional to the peripheral speed in synchronization with the rotation of the additional roller. 2. The control means (22d, 22p) adjusts the peripheral speed of the additional roller to the moving speed of the belt during the activation of the belt drive motor (14m) based on the rotation synchronization signal (Se). The belt drive device according to (1) above, wherein the drive current of the additional roller drive motor (22 m) is controlled.

  (3a) When the first control means ends the activation, the first control means gives a signal (Ssw = “1”) indicating the completion of the activation to the second control means; any one of (1) to (3) above Belt drive device.

  (4) After the start of the belt drive motor (14m), the first and second control means drive the belt so that the moving speed of the belt matches the target speed (Vo1, Vo2) assigned to each. The belt drive device according to any one of (1) to (3), wherein the drive current of the motor (14m) and the additional roller drive motor (22m) is controlled.

  (4a) The first and second control means respectively start decelerating the belt drive motor (14m) and the additional roller drive motor (22m) in response to the belt drive stop instruction; (1) to (4) above The belt driving device according to any one of the above.

  (4b) The second control means (22d, 22p) energizes the additional roller drive motor (22m) with a current value corresponding to the moving speed of the belt while the belt drive motor (14m) is decelerated; The belt driving device according to any one of (4a) to (4a).

  (4c) The second control means (22d, 22p) includes a memory (deceleration table) that holds target current value data addressed to each region of the plurality of belt movement speed regions, and the belt movement speed belongs to the area to which the belt movement speed belongs. Read the target current value data, and control the drive current of the additional roller drive motor (22m) to the value represented by the target current value data; the belt drive device according to (4b) above.

  (4d) The belt drive device further includes rotation signal generation means (6e, 6eP) for generating a rotation synchronization signal (Se) having a frequency proportional to the peripheral speed in synchronization with the rotation of the additional roller. 2. The control means (22d, 22p) is configured to add the additional roller so as to match the peripheral speed of the additional roller with the moving speed of the belt during the deceleration of the belt drive motor (14m) based on the rotation synchronization signal (Se). The belt drive device according to any one of (1) to (4a) above, wherein the drive current of the drive motor (22m) is controlled.

  (4e) The movement signal generating means (5s, 6t, 6tP) includes a plurality of marks (5s) distributed at a predetermined pitch in the movement direction (y) of the belt, and a tape (11) attached to the belt And a timing mark sensor (6t) that detects the passage of each mark and generates a timing mark detection signal (St); the belt drive device further includes a home formed next to the joint of the tape (11) A home position mark sensor (6h) for detecting the passage of the position mark (5h) and the home position mark (5h) and generating a home position mark detection signal (Sh); at least one of the first and second control means The home position mark sensor (6h) calculates and holds the moving speed of the belt based on the movement synchronization signal (St) while the home position mark (5h) is not detected. (6 While the h) detects the home position mark (5h), the movement speed calculated during the previous non-detection is maintained; any one of (1) to (4d) above Belt drive device.

(5) The belt driving device according to any one of (1) to (4d) above;
Imaging means for generating a visible image on the belt (10) of the belt drive;
Means (510) for transferring a visible image of the belt (10) onto a sheet using the additional roller (22) of the belt driving device; and
Fixing means (25) for fixing the visible image on a sheet onto which the visible image is transferred;
An image forming apparatus (100) comprising:

(6) The image forming apparatus (100) according to (5) above;
A document scanner (300) for reading an image of a document and generating image data representing the image; and
Image data processing means (IPP) for converting the image data into image data suitable for the image forming apparatus (100) and outputting the image data to the image forming apparatus;
A copying apparatus comprising:

  Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

  FIG. 1 shows an outline of a mechanism part of a multifunction full color digital copying machine according to a first embodiment of the present invention. This full-color copying machine is roughly constituted by units of an automatic document feeder (ADF) 400, an operation board 500 (FIG. 2), a color scanner 300, a color printer 100, and a paper feed table 200. . A LAN (Local Area Network) connected to a personal computer PC is connected to the system controller 501 (FIG. 2) in the apparatus. The system controller 501 (FIG. 2) of the copying machine can be connected to a communication network (Internet). The facsimile controller FCU 506 (FIG. 2) in the machine can perform facsimile communication via the exchange PBX and the public communication network PN.

  In the center of the main body of the color printer 100, four image forming units 18 (Y, C, M, Bk) of Bk (black), Y (yellow), M (magenta), and C (cyan) are arranged side by side. Thus, the tandem image forming apparatus 20 is configured. Each image forming unit of the tandem image forming apparatus has a photoreceptor 40 (Y, C, M, Bk) on which toner images of respective colors Y, C, M, and Bk are formed.

  A laser exposure device 21 is provided above the tandem image forming apparatus 20. The exposure apparatus 21 includes four light sources 71 (Y, C, M, Bk) equipped with laser diodes prepared for each color, a set of polygon scanners composed of six polygon mirrors and a polygon motor, The lens includes an fθ lens, a long WTL lens, and a mirror arranged in the optical path of each light source. The laser light emitted from the laser diode in accordance with the image information of each color is deflected and scanned by the polygon scanner and applied to the photoconductor 40 of each color.

  Below the tandem image forming apparatus 20, an endless belt-like translucent intermediate transfer belt 10 is installed. In the illustrated example, the intermediate transfer belt 10 is wound around three support rollers 14, 15, 16 and can be rotated and conveyed in the clockwise direction in the figure. The support roller 14 is a drive roller that drives the intermediate transfer belt 10 to rotate. Further, a primary transfer roller 62 (Y, C, M, Bk) is provided between the first support roller 14 and the second support roller 15 as primary transfer means for transferring the toner image from the photosensitive member of each color to the intermediate transfer belt 10. ) Is provided so as to face each photoconductor 40 with the intermediate transfer belt 10 interposed therebetween. An intermediate transfer belt cleaning device 17 that removes residual toner remaining on the intermediate transfer belt 10 after image transfer is provided downstream of the third support roller 16.

  Below the intermediate transfer belt 10, there is a secondary transfer roller 22 that faces the support roller 16 through the belt 10 and contacts the belt 10. The secondary transfer roller 22 transfers an image on the intermediate transfer belt 10 to a sheet. Transcript to. The conveyance belt 24 sends the sheet on which the image has been transferred to the fixing device 25. The fixing device 25 presses a pressure roller 27 against a fixing belt 26 that is an endless belt. In the illustrated example, the paper is reversed and discharged under the secondary transfer roller 22 and the fixing device 25 in parallel with the tandem image forming apparatus 20 described above, or to form an image on both sides of the paper. And a reversing device 28 for re-feeding.

  When copying using this full-color copying machine, a document is set on the document table 30 of the ADF 400. Alternatively, the ADF 400 is opened and an original is set on the contact glass 32 of the scanner 300, and the ADF 400 is closed and the original is pressed. When the start switch on the operation board 500 (FIG. 2) is pressed, when the document is set on the ADF 400, the document is transported and moved onto the contact glass 32, and then the document is set on the contact glass 32. Immediately after that, the scanner 300 is driven and the first traveling body 33 and the second traveling body 34 travel. Then, the first traveling body emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body, reflects by the mirror of the second traveling body, and passes through the imaging lens 35 with the reading sensor. The image is projected onto a certain CCD 36, and the document image is converted into an image signal. Thereafter, when the mode setting on the operation board 500 or the automatic mode selection is set on the operation board 500, the printer 100 starts the image forming operation in the full color mode or the monochrome mode according to the reading result of the original.

  When the full color mode is selected, each photoconductor rotates in the counterclockwise direction in FIG. Then, the surface of each photoconductor is uniformly charged by the charging roller in the image forming apparatus 18 which is a charging device. Each color photoconductor is irradiated with laser light corresponding to the image of each color from the exposure device, and a latent image corresponding to the image data of each color is formed. As each latent image is rotated, the toner of each color is developed by the developing device in the image forming related device 18 as the photoconductor 40 rotates. The toner images of the respective colors are sequentially transferred onto the intermediate transfer belt 10 along with the conveyance of the intermediate transfer belt 10 to form a full color image on the intermediate transfer belt 10.

  On the other hand, one of the paper feed rollers 42 of the paper feed table 43 is selectively rotated to feed the paper from one of the paper feed cassettes 44 provided in multiple stages to the paper feed table 43 and separated and fed one by one by the separation roller 45. The paper is put into the paper path 46, transported by the transport roller 47, guided to the paper feed path 48 in the main body, and abutted against the registration roller 49 and stopped. Alternatively, the paper feed roller 50 is rotated to feed the paper on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller to stop. Then, the registration roller 49 is rotationally driven in synchronization with the full-color image on the intermediate transfer belt 10, the sheet is fed between the intermediate transfer belt 10 and the secondary transfer roller 22, and the toner image is formed by the secondary transfer roller 22. Transfer on paper.

  The sheet on which the toner image has been transferred is conveyed by the conveying belt 24 and sent to the fixing device 25. After fixing the sheet by applying heat and pressure by the fixing device 25, the sheet is switched by the switching claw 55 and discharged. The paper is discharged at 56 and stacked on the paper discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and fed again to the transfer position 22. Is done. Thereafter, when the formation of two or more images is instructed, the above-described image forming process is repeated.

  When the monochrome mode is selected, the support roller 15 moves downward to separate the intermediate transfer belt 10 from the Y, C, and M photoconductors 40. Only the Bk photoconductor rotates in the counterclockwise direction of FIG. 1, and the surface of the Bk photoconductor is uniformly charged by the charging roller in the image forming device 18, and the laser beam corresponding to the Bk image is emitted. The Bk photoconductor 40 is irradiated to form a latent image, which is developed with Bk toner to form a toner image. This toner image is transferred onto the intermediate transfer belt 10. At this time, the three color photoconductors other than Bk and the image forming related device 18 (transfer roller, developing device) are stopped, and unnecessary consumption of the photoconductor and the developer is prevented.

  On the other hand, a sheet is fed from a sheet feeding cassette and conveyed to the transfer roller 22 by the registration roller 49 at a timing that coincides with the toner image formed on the intermediate transfer belt 10. The sheet on which the toner image has been transferred is fixed by the fixing device 25 as in the case of a full-color image, and processed through a paper discharge system corresponding to a designated mode. Thereafter, when the formation of two or more images is instructed, the above-described image forming process is repeated.

  FIG. 2 shows a system configuration of the electrical system of the multifunction copying machine MF1 shown in FIG. The electrical system communicates with the outside using a system controller 501 that performs overall control of the image forming apparatus, an operation board 500 of the image forming apparatus connected to the controller 501, an HDD 503 that stores image data, and an analog line. Communication control device interface board 504, LAN interface board 505, FAX control unit 506, IEEE1394 board, wireless LAN board, USB board, etc. 507 connected to a general-purpose PIC bus, and engine control 510 connected to the controller by PCI bus An I / O board 513 for controlling I / O of the image forming apparatus, a scanner board (SBU: Sensor Board Unit) 511 for reading a copy original (image), and image data connected to the engine control 510 Express Projects image light on a photosensitive drum (light writing) LDB composed (laser diode board) 512 and the like. The communication control device interface board 504 immediately informs an external remote diagnosis device when a failure occurs in the device, and allows the service person to recognize the contents and situation of the failure part and repair them immediately. . In addition, it is also used for sending out the usage status of the device.

  A scanner 300 that optically reads an original scans the original with an original illumination light source, and forms an original image on the CCD 36. The original image, that is, the reflected light of light irradiation on the original is photoelectrically converted by the CCD 36 to generate R, G, B image signals. The CCD 36 is a three-line color CCD that generates R, G, and B image signals of EVENch (even pixel channel) / ODDch (odd pixel channel) and uses it as an analog ASIC (Application Specific IC) of SBU (sensor board unit). input. The SBU 511 includes an analog ASIC and a circuit for generating drive timings for the CCD and analog ASIC. The output of the CCD 36 is sampled and held by a sample and hold circuit inside the analog ASIC, then A / D converted, converted into R, G and B image data, shading corrected, and output I / F (interface) At 520, the data is sent to an image data processor IPP (Image Processing Processor; hereinafter simply referred to as IPP) via an image data bus.

  IPP is a programmable arithmetic processing means that performs image processing, separation generation (determination of whether an image is a character area or a photographic area: image area separation), background removal, scanner gamma conversion, filter, color correction, scaling, and image processing. , Perform printer gamma conversion and gradation processing. The image data transferred from the SBU 511 to the IPP is corrected for signal degradation (signal degradation of the scanner system) accompanying quantization into an optical system and a digital signal by the IPP, and is written in the frame memory 521.

  The system controller 501 includes a ROM that controls the CPU and the system controller board, a RAM that is a working memory used by the CPU, a lithium battery, an NV-RAM that includes an SRAM backup and a clock, and a system controller board. The system bus control, frame memory control, FIFO, and other ASICs for controlling the CPU periphery and their interface circuits are mounted.

  A system controller 501 has functions of a plurality of applications such as a scanner application, a facsimile application, a printer application, and a copy application, and controls the entire system. The input of the operation board 500 is decoded, and the setting of the system and the contents of the state are displayed on the display unit of the operation board 500.

  Many units are connected to the PCI bus, and image data and control commands are transferred in a time division manner by the image data bus / control command bus.

  The communication control device interface board 504 is a communication interface board between the communication control device and the controller 501. Communication with the controller 501 is connected by full-duplex asynchronous serial communication. The communication control device 522 is multi-drop connected according to the RS-485 interface standard. Communication with the remote management system is performed via the communication controller device interface board 504.

  The LAN interface board 505 is connected to an in-house LAN. It is a communication interface board between the in-house LAN and the controller 501, and is equipped with a PHY chip. The LAN interface board 505 and the controller 501 are connected by standard communication interfaces of a PHY chip I / F and an I2C bus I / F. Communication with an external device is performed via the LAN interface board 505.

  The HDD 503 is used as an application database that stores system application programs and device activation information of printers and image forming process devices, and an image database that stores image data of read images and written images, that is, image data and document data. . Both the physical interface and the electrical interface are connected to the controller through an interface conforming to ATA / ATAPI-4.

  The operation board 500 is equipped with a CPU, ROM, RAM, LCD, and ASIC (LCDC) for controlling key input. In the ROM, a control program for the operation board 500 that controls input reading and display output of the operation board 500 is written. The RAM is a working memory used by the CPU. Through communication with the system controller 501, the panel is operated to perform input for the user to input system settings, and display and input control for displaying the setting contents and status of the system to the user.

  The black (Bk), yellow (Y), cyan (C), and magenta (M) write signals output from the work memory of the system controller 501 are the LDB (Laser Diode control Board) Bk, Y, M, Input to a C LD (Laser Diode) writing circuit. The LD write circuit performs LD current control (modulation control) and outputs the result to each LD.

  The engine control 510 is a process controller that mainly controls image formation for image formation, and includes a CPU, an IPP that performs image processing, a ROM that contains programs necessary to control copying and printout, and control of the CPU. Necessary RAM and NV-RAM are installed. The NV-RAM is equipped with an SRAM and a memory that detects power-off and stores it in the EEPROM. In addition, an I / O ASIC that also has a serial interface that transmits and receives signals to and from other CPUs that perform control is a nearby I / O (counter, fan, solenoid, motor, etc.) on which an engine control board is mounted. ASIC for controlling the). The I / O control board 513 and the engine control board 510 are connected via a synchronous serial interface.

  A sub CPU 517 is mounted on the I / O control board 513. The temperature sensor, potential sensor, density sensor (P sensor) that is a toner amount sensor, and reading of detection signals of various other sensors, analog control, paper I / O control of the image forming apparatus including jam detection referring to the detection signal of the sensor and paper conveyance control is performed. The interface circuit 515 is an interface circuit with various sensors and actuators (motors, clutches, solenoids).

  The power supply unit PSU 514 is a unit that supplies power to control the image forming apparatus. When the main SW is turned on (closed), commercial power is supplied. The commercial AC is supplied from the commercial power source to the AC control circuit 540, and the AC control output controlled so as to be rectified and smoothed by the AC control circuit 540 is used to allow the power supply unit PSU 514 to generate a DC voltage necessary for each control board. Supply. The CPU of each control unit operates using a constant voltage generated by the power supply unit PSU.

  FIG. 3 shows an enlarged view of the intermediate transfer belt 10 shown in FIG. 1 and members around it. One belt support roller 14 is a belt drive roller, and is rotationally driven by an electric motor 14m via a power transmission mechanism (not shown). The secondary transfer roller 22 that contacts the belt 10 while facing the other support roller 16 is rotationally driven by an electric motor 22m via a power transmission mechanism (not shown). A timing mark sensor 6t and a home position mark sensor 6h, which are reflection type photo sensors that respectively detect a timing mark and a home position mark on the intermediate transfer belt 10, are provided on the surface of the side edge of the intermediate transfer belt 10. Opposite.

  FIG. 4 shows timing marks 5s and home position marks 5h on the surface of the side edge of the intermediate transfer belt 10. A tape 11 in which a large number of timing marks 5s having a high light reflectance are formed at a short distance and constant pitch on the low light reflectance surface is attached to the surface of the side edge of the intermediate transfer belt 10, and next to the seam 11se. In addition, a home position mark (seal) 5h having a low light reflectance is affixed with the seam 11se substantially in the center in the length direction (y). The timing mark sensor 6t detects the timing mark 5s, and the home mark sensor 6h detects the home position mark 5h.

  FIG. 5 shows an outline of a control system that drives the electric motors 14m and 22m and controls the rotational speed. A motor driver 14d is energized to the electric motor 14m that drives the intermediate transfer belt 10 via the drive roller 14, and a microcomputer 14p (hereinafter referred to as MPU1) gives a drive control signal to the motor driver 14d. The MPU 1 is a microcomputer (MPU) that includes a central processing unit (CPU), a ROM that stores operation programs and fixed data, a RAM that is a data memory that stores processing data, and an input / output circuit (I / O). It is. A motor driver 22d is energized to the electric motor 22m that drives the secondary transfer roller 22, and a microcomputer 22p (hereinafter referred to as MPU2) gives a drive control signal to the motor driver 22d. The MPU 2 is also a microcomputer (MPU) comprising a central processing unit (CPU), a ROM that stores operation programs and fixed data, a RAM that is a data memory for storing processing data, and an input / output circuit (I / O). It is.

  The timing mark sensor 6t is connected to the timing mark detection circuit 6tP. The timing mark detection circuit 6tP supplies power to the sensor 6t, and a timing mark detection signal whose level oscillates as the timing mark 5s crosses the sensor visual field of the sensor 6t in the y direction is a constant level pulse (timing pulse). It is shaped to St and output to the external pulse interrupt input 1 of MPU1 and MPU2 (each CPU). The home mark sensor 6h is connected to the home mark detection circuit 6hP. A home mark detection circuit 6hP feeds power to the sensor 6h, and a home position mark detection signal that changes from a high level to a low level when the home position mark 5h crosses the sensor visual field in the y direction is supplied with a constant level pulse. Shaping into Sh and outputting to MPU1 and MPU2. Both the detection pulses St and Sh have a high level H (also expressed as “1”) when the high light reflecting surface faces the sensor, and a low level L (“0” when the low light reflecting surface faces the sensor. Is also expressed).

  In this embodiment, the CPU of the engine control (process controller) 510 shown in FIG. 2 gives a drive / stop signal Sc to MPU1 and MPU2, and the target speed (data) Vo1 of the intermediate transfer belt 10 is sent to MPU1 to MPU2. Gives the target speed Vo2. Vo2 is the same value as Vo1, or slightly higher or lower than Vo1, and the sheet (transfer paper) that contacts the intermediate transfer belt 10 between the support roller 16 and the secondary transfer roller 22 is equal to the surface speed of the intermediate transfer belt 10. The value is finely adjusted to drive at the same speed. The control system shown in FIG. 5 is in the I / O control 517 shown in FIG.

  FIG. 6 shows an outline of the motor drive control of the MPU 1. When an operating voltage is applied to itself, the MPU 1 (the CPU thereof; the same applies to the following) sets the input / output port to a standby level waiting for a drive instruction by initialization (step 1), and based on the ROM operation program, Various registers defined in a predetermined memory area of the RAM in the MPU 1 are initialized (data clear or initial value setting), and motor drive control in step 2 and subsequent steps is started.

  In the following, the word “step” is omitted in parentheses, and step no. Write numbers only.

  When the drive command (Sc = “1”) arrives after waiting for the drive command (2-13-2), the MPU 1 sets “1” indicating that there is a drive command to one command area of the RAM in the MPU 1. Write to register Rsc (2-4), read target speed data Vo1 given by engine control 510, write to target speed register RVo1 defined in one area of RAM in MPU1 (5), pulse interrupt in response to external pulse St (6) and the switching instruction signal Ssw to the MPU 2 is set to “0” instructing synchronous acceleration (7). Then, “motor 14m start” (8) is executed.

  In “motor 14m start” (8), the MPU 1 sets the short-time pitches in the order set to sequentially read out the target current data group of the start-up table stored in its internal ROM. Are sequentially read out, and are sequentially switched and output to the motor driver 14d as current command values. The motor driver 14d feeds back the motor current value and controls the energization current value of the motor so that it matches the current command value. As a result, the rotational speed of the electric motor 14m increases with the rising characteristic (speed change with time) depending on the target current data group of the startup table, and the moving speed of the intermediate transfer belt 10 also increases. . Note that the target current data group in the start-up table provides, for example, a rotational speed (correctly peripheral speed) rising characteristic shown as “drive roller” in FIG. 9, and is read last in the target current data group in time. The target current data is a value that sets the rotation speed of the drive roller 14 (value converted to the moving speed of the belt 10 driven thereby) to a set value Vf near the target speed Vo1 and lower than Vo1.

  When the last target current data is output to the motor driver 14d, that is, when the "motor 14m start" (8) is finished, the MPU1 instructs the feedback control with the switching instruction signal Ssw to the MPU2 as the target speed Vo2. Set to “1” (9). Then, a timer Tw having a Tw time limit for determining a feedback control cycle is started (10), and "feedback control" (11) is executed.

  In “feedback control” (11), the MPU 1 calculates an error compensation current value for making the deviation of the belt speed Dvb of the belt speed register RDvb zero with respect to the target speed Vo1 of the target speed register RVo1 to be the current motor driver 14d. Is added to the current command value applied to the motor driver 14d, and the added value is switched and output to the motor driver 14d as the current command value. If the error compensation current value is a negative value, the added value is substantially a subtracted value. When the current command value is output to the motor driver 14d, the MPU 1 returns to reading the instruction content of the drive / stop signal Sc in step 2.

  Here, with reference to FIG. 7, an external pulse interrupt process executed by the MPU 1 for detecting the speed of the intermediate transfer belt 10 will be described. Each time the timing pulse St that the timing detection circuit 6tP gives to the external pulse interrupt input terminal 1 of the MPU 1 switches from “1” to “0”, the MPU 1 proceeds to the interrupt StINT shown in FIG. When proceeding to the interrupt StINT, the CPU 1 first writes the clock pulse count value (count data) of the count register to the register RCc (31), clears the count register, and starts counting up the clock pulses (32). Counting up the clock pulse increments (counts up) the data in the count register every time a predetermined number of clock pulses are generated. When the count-up is started, the home position mark detection signal Sh is referred to (33), and if it is "0" (home position mark non-detection), the data in the register RCc (one period data of the timing mark detection signal St) ) Is converted into data representing the speed Dvb of the intermediate transfer belt 10 (34), written to the belt speed register RDvb (35), and the process returns to the step immediately before proceeding to the above-described interrupt StINT in the main routine (FIG. 6). . When the home position mark detection signal Sh is “1” (home position mark detection), the joint of the timing mark tape 11 in which the timing mark 5s is missing or discontinuous is passing through the visual field of the timing mark sensor 6t. Since the count value may not be the correct mark pitch, the above-mentioned interrupt StINT of the main routine (FIG. 6) is executed without executing the speed value calculation based on the count value and the update writing to the belt speed register RDvb. Return to the step just before proceeding to (32-33 return).

  The above-described interrupt StINT permits the interrupt in step 6 shown in FIG. 6 and starts energization of the electric motor 14m in the “start motor 14m” (8). Since the mark detection signal St is oscillated after the pulse is oscillated, the current belt speed is calculated and updated and written in the belt speed register RDvb at the cycle of the timing mark detection signal St. That is, the belt speed register RDvb always has data Dvb representing the latest belt speed. In the feedback control (11) described above, the MPU 1 converts the deviation of the data in the belt speed register RDvb from the data in the target speed register RVo1 into the error compensation current value described above.

  Refer to FIG. 6 again. While the engine control 510 gives the motor drive instruction (Sc = “1”), the MPU 1 waits for the timer Tw to be over in the loop of step 2-3-12-2. In the restart (10) and "feedback control" (11), an error compensation current value is calculated to make the deviation of the belt speed Dvb of the belt speed register RDvb from the target speed Vo1 of the register RVo1 zero. The current command value currently given to the motor driver 14d is added, and the added value is switched and output to the motor driver 14d as the current command value. Then, the process returns to step 2. Since this processing loop is repeated, “feedback control” (11) is executed in a cycle of Tw, and the belt speed Vdb becomes substantially the target speed Vo1.

  When the engine control 510 instructs the motor to stop, that is, when the drive / stop instruction signal Sc is switched from “1” (drive instruction) to “0” (stop instruction), the MPU 1 performs Sc = “ "0" (stop instruction) is recognized, the data in the command register RSc is updated to "0" (14), and the "motor 14m is decelerated" (15), the belt speed Dvb is set to the low speed for stopping (setting value) ) Sequentially decelerate until In this “decelerate the motor 14m” (15), the MPU 1 sets each data of the target current data group of the deceleration table stored in the internal ROM in the order set to read sequentially in time series. The data are sequentially read at a time pitch, and are sequentially switched and output as a current command value to the motor driver 14d. The motor driver 14d feeds back the motor current value and controls the energization current value of the motor so that it matches the current command value. As a result, the rotation speed of the electric motor 14m is lowered and the moving speed of the intermediate transfer belt 10 is also lowered due to the falling characteristic (speed change with time) depending on the target current data group of the deceleration table. To do. Note that the target current data group of the deceleration table provides a predetermined rotational speed falling characteristic, and the target current data read last in the target current data group is the rotational speed of the drive roller 14 (this (The value converted into the moving speed of the belt 10 driven by the above) is a value for setting the low speed for stopping (set value).

  When the last target current data is output to the motor driver 14d, that is, when the “motor 14m deceleration” (15) is finished, the MPU 1 changes the home position mark detection signal Sh from the mark detection level “0” to the mark non-detection level “ Wait until it changes to "1" (16-19). If so, “1” representing mark non-detection is written in the register RSh (20), and the drive of the motor 14m is stopped (21). Then, the pulse St interrupt is prohibited (22), and the engine control 510 waits for a drive instruction (Sc = "1") again (2-13-2).

  FIG. 8 shows an outline of motor drive control of the MPU 2. This motor drive control has a part similar to that of the MPU 1. Therefore, the step number in FIG. 8 indicates a value obtained by adding 40 to the step number of the same process or the corresponding process in FIG.

  When an operating voltage is applied to the MPU 2, the MPU 2 sets the input / output port to a standby level waiting for a drive instruction by initialization (41), and a predetermined memory area of the RAM in the MPU 2 based on the ROM operating program. , The motor drive control starting from step 50 is started, the Tw timer Tw is started (50), the drive command is waited (42-53-42), and the drive command ( When Sc = “1”) arrives, the MPU 2 writes “1” indicating that there is a drive command to the command register Rsc in the MPU 2 (42 to 44), reads the target speed data Vo2 given by the engine control 510, and reads the target Write to the speed register RVo2 (45), enable a pulse interrupt in response to the external pulse St (46), and send an instruction signal Ssw given by MPU1 To irradiation. If the instruction signal Ssw is “0” instructing synchronous acceleration, “motor 22m activation” (48) is executed.

  In “motor 22m start” (48), the MPU 2 converts the speed data Dvb of the belt speed register RDvb into speed region data, and among the target current data group of the start table stored in the ROM inside the MPU 2, The target current data (substantially proportional to the speed value) applied to the speed area data is read and output to the motor driver 22d as a current command value. The motor driver 22d feeds back the motor current value and controls the energization current value of the motor so that it matches the current command value. As a result, a current corresponding to the target current value assigned to the speed region to which the speed data Dvb of the belt speed register RDvb belongs is supplied to the electric motor 22m. Then, the timer Tw waits for the timer Tw to expire (52), and when the timer expires, the timer Tw is started again (50), and Steps 42-43-49-48 and “motor 22m start” (48) are performed at a cycle of Tw. Therefore, as the speed Dvb of the intermediate transfer belt 10 increases, the rotational speed of the electric motor 22m increases. That is, the rotational speed of the secondary transfer roller 22 increases in conjunction with the increase in the speed of the intermediate transfer belt 10.

  It should be noted that the target current data group of the startup table in the MPU 2 is intended to provide the secondary transfer roller 22 with a rising characteristic similar to the speed rising characteristic shown as “drive roller” in FIG. The speed 0 to Vo1 of the transfer belt 10 is divided into a number of speed regions, and the energization current value (region) of the motor 22m required to rotate the secondary transfer roller 22 at each speed region (peripheral speed). (Almost proportional to the speed value) is assigned and written in correspondence with the speed area (address in the table).

  After the instruction signal Ssw given by the MPU 1 is switched to “1” for instructing feedback control using Vo2 as a target speed, the MPU 2 replaces “motor 22m start” (48) with “feedback control” (51). ).

  In “feedback control” (51), the MPU 2 calculates an error compensation current value for making the deviation of the belt speed Dvb of the belt speed register RDvb with respect to the target speed Vo2 of the target speed register RVo2 in the MPU 2 zero. This is added to the current command value given to the motor driver 22d, and the added value is switched and output to the motor driver 22d as the current command value. When the current command value is output to the motor driver 22d, the MPU 2 waits for the timer Tw to expire (52), and when it expires, the MPU 2 starts the timer Tw again (50). In step 42, the drive / stop signal Sc Read the instructions.

  Since the external pulse interrupt processing executed by the MPU 2 for detecting the speed of the intermediate transfer belt 10 is the same as that shown in FIG. 7, the description thereof is omitted here. Similar to MPU1, the belt speed register RDvb of MP2 always has data Dvb representing the latest belt speed. In the above feedback control (51), the MPU 2 converts the deviation of the data in the belt speed register RDvb from the data in the target speed register RVo2 into the above error compensation current value.

  Refer to FIG. 8 again. While the engine control 510 gives the motor drive instruction (Sc = “1”), the MPU 2 performs “feedback control” (51) in the loop of steps 50-42-49-51-52-50 in the cycle of Tw. Thus, an error compensation current value for calculating the deviation of the belt speed Dvb of the belt speed register RDvb from the target speed Vo2 of the target speed register RVo2 to zero is calculated, and the current command value currently given to the motor driver 22d is calculated. The added value is switched and output to the motor driver 22d as the current command value. That is, “feedback control” (51) is executed in a cycle of Tw, and the secondary transfer roller 22 is rotationally driven so that the belt speed Vdb becomes the target speed Vo2. Note that when Vo2 <Vo1, the secondary transfer roller 22 becomes a load on the belt 10 and the secondary transfer roller 22 slips at a speed lag with respect to the belt 10. When Vo2> Vo1, the secondary transfer roller 22 Becomes a speed increaser of the belt 10, and the secondary transfer roller 22 slips forward with respect to the belt 10. However, since Vo2 is substantially equal to Vo1, the moving speed of the belt 10 by the MPU 1 is set to the target speed Vo1. The feedback control is not disturbed. In other words, the peripheral speed is set so that the paper fed in close contact with the visible image on the belt 1 does not disturb the feedback speed control of the belt 10 by the MPU 1 and is exactly the same speed as the visible image (belt surface). A target speed Vo2 for driving the secondary transfer roller 22 is determined.

  When the engine control 510 instructs the motor to stop, the MPU 2 recognizes this through the route of steps 50-42 to 53, updates the data in the command register RSc to “0” (54), and “decelerates the motor 22m”. In (55), the speed (circumferential speed) of the secondary transfer roller 22 is sequentially decelerated to the low speed for stopping (set value). In this “decelerate the motor 22m” (55), the MPU 2 converts the speed data Dvb of the belt speed register RDvb into speed area data, and stores the target current data group of the deceleration table stored in the ROM inside the MPU 2. The target current data addressed to the speed region data in the medium is read out and switched to the motor driver 22d as a current command value. The motor driver 22d feeds back the motor current value and controls the energization current value of the motor so that it matches the current command value. As a result, the rotational speed of the electric motor 22m is lowered and the rotational speed of the secondary transfer roller 22 is also lowered with a descent characteristic that depends on the target current data group of the deceleration table and that is synchronized or interlocked with the reduction of the belt speed. To do. Note that the target current data group of the deceleration table is intended to reduce the speed of the secondary transfer roller 22 to the same peripheral speed as the speed at the time of deceleration of the belt 10 by the deceleration control of the MPU 1.

  While performing the deceleration control, the MPU 2 waits for the home position mark detection signal Sh to change from the mark detection level “0” to the mark non-detection level “1” (56 to 59). If so, “1” representing mark non-detection is written in the register RSh (60), and the drive of the motor 22m is stopped (61). Then, the pulse St interrupt is prohibited (62), and the engine control 510 waits for a drive instruction (Sc = "1") again (52-50-42-53-52).

  FIG. 9 shows the peripheral speed rising characteristics of the drive roller 14 and the secondary transfer roller 22 controlled by the control system shown in FIG. 5 and described above. As shown in FIG. 12, the rotational speed of the rising of the driving roller 9 and the secondary transfer roller 22 of the conventional control is very different, causing a problem. The peripheral speed difference between the drive roller 14 and the secondary transfer roller 22 by the control of this embodiment is very small as shown in FIG. For this reason, the electric motor 14m does not have a load torque that is just below the motor output torque, and the intermediate transfer belt 10 is not bent, and speed control turbulence due to an abnormal reduction of the load torque does not occur.

  The switching from the start (48) of the electric motor 22m to the constant speed control (51) is performed when the set time (sequential reading period of the target current data from the start table) has elapsed, but the belt speed Dvb. May be switched on the condition that has reached a set value (for example, Vf).

  FIG. 10 shows the configuration of the hardware part of the second embodiment different from that of the first embodiment. In the second embodiment, a rotary encoder 62 is coupled to a power transmission mechanism between the electric motor 22m and the secondary transfer roller 22 to generate a two-transfer roller rotation synchronization signal, and an encoder pulse generation circuit 6eP performs the synchronization. The signal is shaped and the rotation synchronization pulse Se is output to the external pulse interrupt terminal 2 of the MPU 2. The MPU 2 measures the period of the rotation synchronization pulse Se by interrupt processing similar to the timing pulse St interrupt StINT described above, calculates the peripheral speed data Dvr of the secondary transfer roller 22 based on the period data, and calculates the roller speed register RDvr. Write to. However, there is no step 33 (FIG. 7) in which the speed data calculation is suspended while the home position mark detection signal Sh is “0”. Other hardware is the same as that of the first embodiment shown in FIGS.

The processing function of the MPU 1 of the second embodiment is the same as that of the first embodiment. That is, the MPU 1 of the second embodiment executes the motor control shown in FIG. 6 and the belt speed calculation shown in FIG. FIG. 11 shows motor control of the MPU 2 of the second embodiment.
Referring to FIG. 11, the motor control of the MPU 2 is different from that of the first embodiment (FIG. 8) in that “motor 22m activation” (48) is changed to “feedback control of target speed Dvd” (48a), The difference is that “decelerate motor 22m” (55) is changed to “feedback control of target speed Dvd” (55a). In “feedback control of the target speed Dvd” (48a), the MPU 2 of the second embodiment calculates the deviation of the speed value Dvr of the roller speed register RDvr from the speed value Dvb of the belt speed register RDvb, and sets the deviation to zero. Therefore, the error compensation current value is calculated and added to the current command value currently given to the motor driver 22d, and the added value is output to the motor driver 22d as the current command value. As a result, the rotational speed of the secondary transfer roller 22 increases following the increase in the speed of the intermediate transfer belt 10 due to the start of the motor 14m. After the instruction signal Ssw given by the MPU 1 is switched to “1” for instructing feedback control using Vo 2 as a target speed, the MPU 2 replaces “feedback control of the target speed Dvd” (48a) for starting the motor 22m. Then, “feedback control” (51) is executed. The contents of the “feedback control” (51) are the same as those described above in the first embodiment.

  In the “feedback control of the target speed Dvd” (55a), the MPU 2 of the second embodiment, like the “feedback control of the target speed Dvd” (48a), the roller speed register RDvr with respect to the speed value Dvb of the belt speed register RDvb. An error compensation current value for calculating the deviation of the speed value Dvr of the motor and calculating the error compensation current value for making the deviation zero is added to the current command value currently given to the motor driver 22d. The current command value is output to the motor driver 22d. As a result, the rotational speed of the secondary transfer roller 22 decreases following the speed drop of the intermediate transfer belt 10 due to the deceleration of the motor 14m. Other processes are the same as those in the first embodiment.

  Note that feedback control (11) for setting the speed Dvb of the intermediate transfer belt 10 to the target speed Vo1 and feedback control (51) for setting the peripheral speed of the secondary transfer roller 22 to the target speed Vo2 are PLL control (Phase Locked Loop) may be used instead. In this case, a reference pulse generator for generating a pulse having a cycle corresponding to the target speeds Vo1 and Vo2 is provided, and the timing pulse St and the synchronization pulse Se are phase-synchronized with the pulse generated by the reference pulse generator. Increase or decrease the speed of the electric motors 14m and 22m.

1 is a longitudinal sectional view showing an outline of a mechanism of a color copying machine having a composite function according to a first embodiment of the present invention. FIG. 2 is a block diagram showing an outline of an image processing system of the copying machine shown in FIG. 1. FIG. 2 is an enlarged longitudinal sectional view showing an intermediate transfer belt 10 shown in FIG. 1 and mechanical elements around the intermediate transfer belt 10. FIG. 4 is a plan view of the intermediate transfer belt 10 shown in FIG. 3. It is a block diagram of the motor control system which performs the rotational speed control of the electric motors 14m and 22m shown in FIG. It is a flowchart which shows the outline | summary of the motor control of MPU1 shown in FIG. 6 is a flowchart showing the contents of an interrupt process for calculating speed data of the intermediate transfer belt 10 in the MPU 1 shown in FIG. 5. It is a flowchart which shows the outline | summary of the motor control of MPU2 shown in FIG. 6 is a graph showing rises in rotational peripheral speeds of the drive roller 14 and the secondary transfer roller 22 shown in FIG. 3 driven by the motor control system shown in FIG. 5. It is a block diagram of the motor control system of 2nd Example. It is a flowchart which shows the outline | summary of the motor control of MPU2 of 2nd Example. It is a graph which shows the rise of the rotational peripheral speed of the conventional drive roller and secondary transfer roller.

Explanation of symbols

10: Intermediate transfer belt 14-16: Support roller 17: Intermediate transfer member cleaning device 18: Image forming device 20: Image forming device 21: Laser exposure device 22: Secondary transfer roller 23: Roller 24: Conveyor belt 25: Fixing Device 26: Fixing belt 27: Pressure roller 28: Sheet reversing device 32: Contact glass 33: First carriage 34: Second carriage 35: Imaging lens 36: CCD
40: photosensitive drum 42: paper feed roller 43: paper bank 44: paper feed cassette 45: separation roller 46: paper feed path 47: transport roller 48: paper feed path 49: registration roller 50: paper feed roller 51: manual feed tray 55: Switching claw 56: Discharge roller 57: Discharge tray

Claims (6)

A driving roller for supporting and driving the belt;
A belt drive motor for rotationally driving the drive roller;
A movement signal generating means for generating a movement synchronization signal representing movement of a predetermined short distance in synchronization with movement of the belt by the transfer drive;
First control means for controlling the driving of the belt driving motor so that the moving speed of the belt becomes a target speed after the belt driving motor is started;
An additional roller in contact with the belt;
An additional roller drive motor that rotationally drives the additional roller; and
Second control for controlling the driving of the additional roller driving motor and increasing the rotational speed of the additional roller driving motor in conjunction with the increase in the moving speed of the belt based on the movement synchronization signal during the start-up of the belt driving motor. means;
A belt drive device comprising:   2. The belt drive device according to claim 1, wherein the second control unit energizes the additional roller drive motor with a current value corresponding to a moving speed of the belt during the start-up of the belt drive motor.   The belt driving device further includes a rotation signal generating means for generating a rotation synchronization signal having a frequency proportional to the peripheral speed in synchronization with the rotation of the additional roller, and the second control means is based on the rotation synchronization signal. The belt driving device according to claim 1, wherein during the start-up of the belt driving motor, the driving current of the additional roller driving motor is controlled so that the peripheral speed of the additional roller matches the moving speed of the belt.   After the start-up of the belt drive motor, the first and second control means control the drive currents of the belt drive motor and the additional roller drive motor so that the moving speed of the belt matches the target speed assigned to each. The belt driving device according to any one of claims 1 to 3. The belt drive device according to any one of claims 1 to 4;
Imaging means for generating a visible image on the belt of the belt drive;
Means for transferring a visible image of the belt onto a sheet using the additional roller of the belt driving device; and
Fixing means for fixing the visible image on a sheet onto which the visible image is transferred;
An image forming apparatus comprising: The image forming apparatus according to claim 5;
A document scanner that reads an image of a document and generates image data representing the image; and
Image data processing means for converting the image data into image data suitable for the image forming apparatus and outputting the image data to the image forming apparatus;
A copying apparatus comprising:

Images