JP2014044558A - Distribution control system, and control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable high-speed communication as necessary by performing communication in a second communication mode faster than serial communication in addition to a first communication mode for performing serial communication with a module connected by a serial communication line.SOLUTION: A distribution control system dispersedly performs processing by a main control module 400 and a first and second sub control modules 410, 420. The main control module 400 switches a communication mode of the first and second sub control modules 410, 420 to a second communication mode faster than serial communication by the serial communication. Also, a communication mode of the main control module itself is switched to the second communication mode so as to enable control of the first sub control module 410 according to data from the second sub control module 420 faster than the serial communication.

Description

  The present invention relates to a distributed control system having a main control module and a plurality of sub-control modules.

  In an image forming apparatus such as a copying machine or a multifunction peripheral, it is necessary to control a number of printer devices such as motors and sensors for image formation. When these controls are performed by one CPU (Central Processing Unit), the load on the CPU increases. A high-performance CPU is required to cope with an increase in load. As the number of loads in the printer increases, the wiring from the board on which the CPU is mounted to the load driver unit becomes longer. Furthermore, a large amount of wiring is required, and the layout of the wiring becomes complicated. Such a high-performance CPU and a long and large amount of wiring affect the manufacturing cost of the image forming apparatus.

  For this purpose, an image forming apparatus that performs image forming processing by distributed control using a plurality of control modules is realized. Each control module has a CPU and an ASIC (Application Specific Integrated Circuit), and executes processing for image formation shared by itself. In distributed control using a plurality of control modules, serial communication is often used for data communication between control modules (between CPUs, between CPUs and ASICs, and between ASICs) in order to reduce the number of wires and to perform high-speed processing.

  When distributed control is performed by one main control module and a plurality of sub control modules, in the configuration in which the main control module and each sub control module are simply connected by a serial communication line, there are as many serial communication lines as the number of sub control modules. I need it. As the number of sub-control modules increases, the number of serial communication lines also increases.

Patent Document 1 discloses a device that transmits and receives communication data between a master station and a plurality of slave stations via a communication line using a multiplex communication method (the multiplex communication method is configured by, for example, an I2C (Inter-Integrated Circuit) method). Is disclosed. The number of communication lines is reduced by the multiplex communication method.
Patent Document 2 discloses a method of reducing the number of interrupt-dedicated control lines and transmitting the presence / absence of interrupt and factor information as serial data via a serial communication line. In Patent Document 2, since interrupt information generated in a slave station is once stacked in the slave station and transferred as serial data via a communication line, the dedicated interrupt line can be reduced.

JP-A-5-122777 JP 2009-141526 A

In a distributed control system, when performing synchronous operation between sub-control modules and optimal control reflecting sensor detection results using a serial communication line, delay due to serial communication time becomes a problem.
For example, in a distributed control system in which two sub control modules are connected to a main control module, data from one sub control module may be used for operation control by the other sub control module. In this case, serial communication is required twice. That is, the main control module receives data from one sub-control module by serial communication, and transmits an instruction based on the received data to the other sub-control module by serial communication. The time required for these two serial communications is a delay time. The delay time due to serial communication is preferably shorter for optimal control reflecting the synchronous operation between the sub-control units and the detection result of the sensor.

  In order to shorten the serial communication time, it is possible to connect the two sub-control modules directly with a serial communication line. However, this causes an increase in wiring and a complicated wiring arrangement. Therefore, the effect of reducing the number of wirings by using a serial communication line is reduced. It is also possible to shorten the serial communication time by increasing the communication speed of serial communication. However, increasing the communication speed generally increases the radiation noise level and weakens the noise resistance of communication.

In the multiplex communication apparatus of Patent Document 1, since a communication line is shared between a plurality of slave stations (sub control modules) and a master station (main control module), arbitration of the right to use the communication lines is necessary. When a timing signal that requires responsiveness is transferred between the master station and the slave station via serial communication, the delay required for arbitration of the serial communication line is added to the delay required for serial communication, and a request for responsiveness is made. It becomes difficult to be satisfied.
In the method of Patent Document 2, the slave station interrupt information is transmitted to the master station as serial data. For this reason, even if the control lines dedicated to interrupts can be reduced, the occurrence of time delay in serial communication cannot be prevented.

  In view of the above-described conventional problems, the present invention can communicate with a module connected by a serial communication line in a second communication mode that is faster than serial communication in addition to the first communication mode that performs serial communication. The purpose is to enable high-speed communication as necessary.

The distributed control system of the present invention that solves the above problems includes a main control module, and first and second sub-control modules each connected to the main control module via a serial communication line. This distributed control system performs distributed processing by transmitting and receiving data via the serial communication line between the main control module and the first and second sub-control modules.
The main control module and the first and second sub-control modules can communicate in a first communication mode for serial communication and in a second communication mode in which data transfer is faster than serial communication, respectively. Have means.
The main control module has switching means and control means. The switching means switches the communication means of the first and second sub control modules from the first communication mode to the second communication mode by serial communication. The communication unit of the main control module is switched from the first communication mode to the second communication mode. The control means transmits control data to the second sub-control module in the second communication mode in accordance with data received from the first sub-control module in the second communication mode.

The control device of the present invention is more effective than the first communication mode and serial communication in which serial communication is performed between the first and second sub-control modules connected by the serial communication line via the serial communication line. Communication is performed in the second communication mode in which data transfer is fast. As a result, the control device can perform distributed processing using the first and second sub-control modules.
This control apparatus has a switching means and a control means.
The switching unit switches the communication mode of the first and second sub-control modules from the first communication mode to the second communication mode by serial communication. The switching means switches the communication mode of the own device from the first communication mode to the second communication mode.
The control means transmits control data to the second sub-control module in the second communication mode in accordance with data received from the first sub-control module in the second communication mode.

  In the present invention, when the two sub-control modules operate in cooperation, the communication mode is switched to the second communication mode in which data transfer is faster than serial communication, thereby enabling high-speed communication as necessary. It becomes.

1 is a configuration diagram of an image forming apparatus. 1 is a configuration example diagram of a distributed control system of a first embodiment. The detailed block diagram of a communication control part. Explanatory drawing of the control flow of the process by the distributed control system of 1st Embodiment. The structural example figure of the distributed control system of 2nd Embodiment. Explanatory drawing of the control flow of the process by the distributed control system of 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Image forming apparatus]
FIG. 1 is a configuration diagram of an image forming apparatus using a distributed control system according to the present embodiment. The image forming apparatus 200 employs an electrophotographic system. In FIG. 1, alphabets Y, M, C, and K at the end of the code represent yellow, magenta, cyan, and black colors, respectively. In the following description, when all colors are represented, the alphabets Y, M, C, and K at the end of the code are omitted.

  A photosensitive drum (hereinafter referred to as “photosensitive member”) 225 which is an image forming body for forming a full-color electrostatic image is provided so as to be rotatable in the direction of arrow A in the drawing by a motor (not shown). Around the photoconductor 225, a primary charging unit 221, an exposure unit 218, a developing unit 223, a transfer unit 220, a cleaner unit 222, and a charge eliminating unit 271 are provided.

A latent image is formed on the photoreceptor 225 by the exposure unit 218. The developing unit 223 develops the latent image formed on the photoconductor 225 with toner. The intermediate transfer belt 226 is transferred with the toner image of each color developed on the photoconductor 225.
The intermediate transfer belt 226 is stretched around rollers 227, 228, and 229. The transfer roller attaching / detaching unit 250 is a drive unit for bringing the secondary transfer unit 231 into contact with and separating from the intermediate transfer belt 226. The residual toner is scraped off from the intermediate transfer belt 226 after passing through the secondary transfer portion 231 by the cleaner blade 232.

  Recording materials such as recording paper are stored in the cassettes 240 and 241 and the manual paper feed unit 253. The cassettes 240 and 241 and the manual paper feed unit 253 include paper detection sensors 243, 244, and 245 for detecting the presence or absence of a recording material. The cassettes 240 and 241 and the manual paper feed unit 253 include paper feed sensors 247, 248, and 249 for detecting a recording material pickup failure.

  The registration roller 255, the paper feed roller pair 235, and the vertical pass roller pairs 236 and 237 are used to contact the recording material stored in the cassettes 240 and 241 with a contact portion (nip portion) between the secondary transfer portion 231 and the intermediate transfer belt 226. To feed. The registration roller 255 and the paper feed roller pair 235 feed the recording material stored in the manual paper feed unit 253 to the nip portion. At that time, the secondary transfer portion 231 is brought into contact with the intermediate transfer belt 226 by the transfer roller attaching / detaching unit 250. The toner image formed on the intermediate transfer belt 226 is transferred onto the recording material at the nip portion. The fixing unit 234 thermally fixes the toner image transferred to the recording material.

[Operation of Image Forming Apparatus]
An image forming operation on a recording material in the image forming apparatus 200 will be described.
The image forming apparatus 200 applies a voltage to the primary charging unit 221 during image formation to uniformly negatively charge the surface of the photoconductor 225 at a predetermined potential. On the charged photoconductor 225, exposure is performed by an exposure unit 218 having a laser scanner to form a latent image. The exposure unit 218 forms a latent image corresponding to the image data by turning on and off the laser beam based on the image data sent from the controller 214 via the printer control interface 215.

  A developing bias preset for each color is applied to the developing roller of the developing unit 223. The latent image on the photoconductor 225 is developed as a toner image by being developed by a developing roller. The toner image is transferred to the intermediate transfer belt 226 by the transfer unit 220, and further transferred to the conveyed recording material by the secondary transfer unit 231. The recording material onto which the toner image has been transferred passes through a conveyance path 268 and is conveyed to the fixing unit 234 via the fixing conveyance belt 230.

  In the fixing unit 234, the pre-fixing chargers 251 and 252 charge the toner image transferred to the recording material in order to compensate for the toner adsorption force and prevent image disturbance. Further, the toner image is thermally fixed on the recording material by the fixing roller 233. After the heat fixing, the recording material is discharged. The toner remaining on the photosensitive member 225 is removed and collected by the cleaner unit 222. Thereafter, the photosensitive member 225 is uniformly discharged to near zero volts by the charge removing device 271 to prepare for the next image forming cycle.

A recording material conveyance operation in the image forming apparatus 200 will be described.
When image formation is started, the recording materials stored in the cassettes 240 and 241 and the manual paper feed unit 253 are picked up one by one by the pick-up rollers 238, 239 and 254, and are registered by the registration rollers 235. It is conveyed to 255. The recording material is detected by the registration sensor 256 disposed upstream of the registration roller 255.

  The image forming apparatus 200 interrupts the conveying operation once when the registration sensor 256 detects the passage of the recording material (or after a predetermined time has elapsed since the detection). Therefore, the recording material comes into contact with the stopped registration roller 255 and stops. At this time, the posture of the recording material is adjusted so that the front end of the recording material is perpendicular to the conveyance path. This process is referred to as “position correction”. The position correction is performed in order to reduce the inclination of the image formed on the recording material in the subsequent processing. After the position correction, the image forming apparatus 200 activates the registration roller 255 to resume the conveyance operation, and conveys the recording material to the secondary transfer unit 231.

  A toner image is transferred to the recording material in the secondary transfer unit 231. After the toner image is transferred, the recording material passes through the conveyance path 268 and is conveyed to the fixing unit 234 via the fixing conveyance belt 230. The recording material on which the toner image is fixed by the fixing unit 234 is discharged to the discharge tray 242 by the discharge roller 270 by switching the transport path to the discharge path 258 side by the discharge flapper 257.

In the case of performing duplex printing, after an image is formed on the surface of the recording material, the recording material is not discharged onto the paper discharge tray 242 but is formed on the back surface of the recording material. When image formation is performed on the back surface of the recording material, when the recording material is detected by the paper discharge sensor 269, the paper discharge flapper 257 switches the transport path to the back surface path 259 side. The reverse roller 260 conveys the recording material that has passed through the double-side reverse path 261 to the double-side reverse path 261. The recording material is conveyed to the double-side reversing path 261 by the amount corresponding to the feed direction width, and then the traveling direction is switched by reverse rotation driving of the reversing roller 260. Then, the double-sided path conveying roller 262 conveys the recording material having the surface facing downward to the double-sided path 263.
The recording material is conveyed through the double-sided path 263 toward the refeed roller 264, and the passage of the recording material is detected by the refeed sensor 265. When the re-feed sensor 265 detects the passage of the recording material, in the present embodiment, the conveyance operation is interrupted after a predetermined time has elapsed. The recording material comes into contact with the refeed roller 264 and stops. At this time, the posture of the recording material is adjusted so that the front end of the recording material is perpendicular to the conveyance path. Hereinafter, this process is referred to as “reposition correction”.

  The reposition correction is performed in order to reduce the inclination of the image formed on the back surface of the recording material. After the reposition correction, the refeed roller 264 is restarted. The re-feed roller 264 transports the recording material in a state where the front and back sides are reversed to the feed path 266 again. Thereafter, the image forming apparatus 200 performs the above-described position correction again, and performs the same processing as the surface of the recording material. The recording material on which images are formed on both the front and back surfaces is discharged from the discharge flapper 257 to the discharge tray 242 by switching the transport path to the discharge path 258 side.

  Note that the image forming apparatus 200 can continuously feed the recording material even during duplex printing. However, since the image forming apparatus 200 has only one system for forming an image on a recording material and fixing a formed toner image, printing on the front surface and printing on the back surface are simultaneously performed. It is not possible. Therefore, at the time of duplex printing, the recording material from the cassettes 240 and 241 and the manual paper feeding unit 253 and the recording material that is reversed and fed again for back side printing are alternately displayed on the image forming apparatus 200. It is formed.

[Distributed control system]
The image forming apparatus 200 is distributed and controlled by a distributed control system including a main control module and a plurality of sub-control modules. The sub control module is, for example, a transport module, an image forming module, a fixing module, or the like. The main control module controls each sub-control module centrally. The main control module and each sub control module are connected by a serial communication bus with good response. The transport module controls operations of various rollers and various motors that perform the above-described transport operation. The image forming module controls operations of the photosensitive member 225, the developing unit 223, the primary charging unit 221, the various rollers, the various motors, and the like that perform the above-described image forming operation. The fixing module controls operations of various rollers and various motors for discharging the recording material from the fixing unit 234 and the fixing unit 234 to the outside of the image forming apparatus 200.

  For example, the transport module picks up the recording material stored in the cassette 240 by the pickup roller 238 and transports the recording material to the secondary transfer unit 231. Therefore, the transport module detects the presence or absence of the recording material in the cassette 240 by the paper detection sensor 243, and detects a pickup failure of the recording material by the paper feed sensor 247. Further, the motor for driving the pickup roller 238 is controlled. Such motor and sensor control performed in each sub-control module is divided into functions so as to be realized in a plurality of functional modules integrated by the sub-control module. That is, the distributed control system of this embodiment has a hierarchical structure of a main control module, a sub control module, and a functional module.

  The transfer time by the serial communication bus is important when there is little time margin from the detection of the recording material by the sensor to the drive control of the roller, such as position correction in the registration roller 255 and reposition correction in the double-sided path 263. Become. If the drive of the roller is not controlled immediately after the recording material is detected, the roller is decelerated and stopped after the recording material hits the roller more than necessary, and as a result, the recording material cannot be used. End up.

  Even in such a control that requires responsiveness depending on timing, optimal function division and division arrangement cannot be performed due to restrictions on the configuration of the device and restrictions on the functions that can be allocated to each sub-control module. There is a case.

[First Embodiment]
FIG. 2 is a configuration example diagram of a distributed control system that performs position correction. Note that the reposition correction can be realized with the same configuration. This distributed control system includes a main control module 400, a first sub control module 410, and a second sub control module 420, and functions are distributed to each. Further, the main control module 400, the first sub control module 410, and the second sub control module 420 are separately arranged.
The first sub control module 410 controls the motor 104 for driving the registration roller 255 to rotate. The second sub control module 420 monitors a registration sensor 256 that detects the leading edge of the recording material. The main control module 400 transfers a motor drive signal for driving the motor 104 to the first sub-control module 410 according to the input timing of the sensor signal that is the detection result of the registration sensor 256. The main control module 400 and the first sub control module 410 can transmit and receive data via the serial communication line 406. The main control module 400 and the second sub control module 420 can transmit and receive data via the serial communication line 405.

The main control module 400 includes a CPU 401 that executes a program stored in a ROM (Read Only Memory) 403 using a RAM (Random Access Memory) 402 as a work area. The communication control unit 404 can communicate with the first sub control module 410 and the second sub control module 420.
A watch dog timer (WDT) 430 monitors the operating state of the CPU 401. An interrupt controller (IRQC: Interrupt ReQuest Controller) 431 requests the CPU 401 to interrupt the process and execute the specified process. The timer 432 generates a high-speed cycle interrupt for generating a motor drive signal. The D / A converter 433 includes a plurality of channels and converts a digital signal into an analog signal. The A / D converter 434 includes a plurality of channels and converts an analog signal into a digital signal.
Each component of the main control module 400 can transmit and receive data via the CPU bus 605.

  The first sub-control module 410 includes a CPU 411 that executes a program stored in the ROM 413 using the RAM 412 as a work area. The communication control unit 414 can communicate with the main control module 400. The PWM (pulse width modulation) generation unit 415 generates a PWM signal using a general-purpose timer. The first sub control module 410 controls the motor 104 by a PWM signal.

  The second sub-control module 420 includes a CPU 421 that executes a program stored in the ROM 423 using the RAM 422 as a work area. The communication control unit 424 can communicate with the main control module 400. GPIO (General Purpose Input / Output) 425 is an input / output terminal having a plurality of general-purpose input / output ports.

FIG. 3 is a detailed configuration diagram of the communication control unit 404.
The communication control unit 404 can perform communication in a plurality of modes. The communication control unit 404 according to the present embodiment can execute switching between serial data transmission / reception (serial communication mode) and simple signal transmission / reception (signal communication mode) via the serial communication lines 405 and 406. The communication mode is switched by a command from the CPU 401, for example. Note that switching of the communication modes of the communication control unit 414 of the first sub control module 410 and the communication control unit 424 of the second sub control module 420 is also performed according to a command from the CPU 401.
When the first sub control module 410 receives a command to switch the communication mode from the main control module 400 by serial communication, the CPU 411 switches the communication mode of the communication control unit 414 according to the command. The same applies to the second sub-control module 420.

  The parallel / serial conversion unit 604 and the serial / parallel conversion unit 606 can individually transmit / receive data and set a data transfer rate. The buffer unit 603 includes a transmission buffer area and a reception buffer area.

Transmission data is stored in the transmission buffer area of the buffer unit 603 from the CPU 401 via the CPU bus 605. The transmission data stored in the transmission buffer area is parallel-serial converted by the parallel-serial conversion unit 604 and then serially transmitted to the first sub-control module 410 or the second sub-control module 420.
Received data sent from the first sub-control module 410 or the second sub-control module 420 is serial-parallel converted by the serial-parallel converter 606 and then stored in the reception buffer area of the buffer 603. The CPU 401 reads the reception data stored in the reception buffer area via the CPU bus 605.

  The data count unit 601 counts the number of data stored in the buffer unit 603. The data count unit 601 counts up the number of transmission data when transmission data is written from the CPU bus 605, and counts down the number of transmission data when the transmission data is read out by the parallel-serial conversion unit 604. Thereby, the data count unit 601 manages the number of transmission data waiting for transmission in the transmission buffer area of the buffer unit 603. Similarly, the data count unit 601 counts up the number of received data when the received data received by the serial / parallel conversion unit 606 is stored in the buffer unit 603, and counts down the number of received data when the CPU 401 reads the received data. . Thus, the number of received data in the reception buffer area of the buffer unit 603 is managed.

The clock generation unit 602 generates a clock based on the number of transmission data waiting for transmission in the buffer unit 603 counted by the data count unit 601. The clock generation unit 602 switches the maximum value of the frequency division counter according to the number of transmission data waiting for transmission. The frequency division counter determines the number of counts necessary to transmit 1 bit width of communication data. That is, when the number of transmission data waiting for transmission is large, the time required for 1-bit transmission is reduced by decreasing the frequency division counter value to increase the communication baud rate. As a result, the number of transmission data waiting in transmission in the buffer unit 601 can be quickly reduced.
Further, the clock generation unit 602 determines the output timing of transmission data from the parallel-serial conversion unit 604 based on the system clock input to the communication control unit 404. The clock generation unit 602 uses a counter that counts up the system clock to count the system clock up to a count value that can generate one bit of transmission data. The timing counted up to this count value is the output timing. The clock generation unit 602 counts up to the count value as the output timing, then clears the count value to zero, and repeats the count operation again.

  When the communication control unit 404 is in the signal communication mode, transmission data from the CPU bus 605 is sent to the parallel / serial conversion unit 604 without going through the buffer 603. Also, data received by the serial / parallel converter 606 is sent to the CPU bus 605. In this case, for example, even if the transmission data is an analog signal, it can be output from the parallel-serial converter 604 to the serial communication line.

  The above is an example of the configuration of the communication control unit 404 of the main control module 400. The communication control unit 414 of the first sub control module 410 and the communication control unit 424 of the second sub control module 420 have the same configuration and operation.

  If it is a normal control method by the distributed control system of FIG. 2, serial communication will be required twice. That is, the serial communication of the sensor signal from the second sub control module 420 to the main control module 400 and the serial communication of the motor drive signal from the main control module 400 to the first sub control module 410. The communication time for these two serial communications becomes a delay time. Serial communication requires communication of a plurality of data (for example, start data, stop data, parity data, etc.) according to a protocol in addition to predetermined data (for example, detection result from a sensor) in one communication. . That is, the serial communication mode requires a lot of data in communication of predetermined data as compared with the signal communication mode, takes a communication time, and increases a delay time.

In the present embodiment, the serial communication lines 405 and 406 are switched between serial communication and control signal communication in order to reduce the delay time without increasing the number of control lines or increasing the serial communication speed.
FIG. 4 is an explanatory diagram of a control flow of processing for correcting the position by switching the serial communication lines 405 and 406 between serial communication and control signal communication.

The main control module 400 instructs the second sub-control module 420 to set a predetermined port of the GPIO 425 as a port to which a detection result is input from the registration sensor 256 by serial communication via the serial communication line 405. . This instruction is performed by serial communication (S301). In response to this instruction, the second sub control module 420 sets a predetermined port of the GPIO 425 as an input port for the detection result.
In addition, the main control module 400 sets the motor speed and rotation direction for controlling the drive of the motor 104 to the PWM signal generation unit 415 of the first sub control module 410 by serial communication via the serial communication line 406. (S302).

  The main control module 400 instructs the second sub-control module 420 to use the serial communication line 405 as a signal line for transmitting a sensor signal by serial communication using the serial communication line 405. As a result, the communication control unit 424 of the second sub-control module 420 stops the function of performing serial communication. The communication control unit 424 transmits the detection result by the registration sensor 256 to the main control module 400 as a sensor signal via the serial communication line 405 (S303).

The main control module 400 instructs the first sub-control module 410 to use the serial communication line 406 as a signal line for transmitting a motor drive signal by serial communication using the serial communication line 406. Accordingly, the communication control unit 414 of the first sub control module 410 stops the function of performing serial communication. The communication control unit 414 receives the motor drive signal from the main control module 400 via the serial communication line 406 (S304).
By steps S303 and S304, the communication control unit 414 of the first sub control module 410 and the communication control unit 424 of the second sub control module 420 are switched from the serial communication mode to the signal communication mode.

  After step S304 is completed, the main control module 400 switches the communication control unit 404 to a general-purpose port. That is, the communication control unit 404 of the main control module 400 also switches from the serial communication mode to the signal communication mode. Thus, the communication control unit 404 determines that the input signal from the second sub control module 420 via the serial communication line 405 is a sensor signal, and sends the motor drive signal to the first sub control module 410 via the serial communication line 406. Forward.

  The second sub-control module 420 transmits a sensor signal representing a detection result by the registration sensor 256 to the main control module 400 via a serial communication line 405 as a signal line. The main control module 400 uses the sensor signal as a timing signal and makes a predetermined setting for the PWM signal generation unit 415 of the first sub-control module 410 when the sensor signal is received. Further, the main control module 400 starts generating a motor drive signal. The motor drive signal is a pulse signal. Note that the communication control unit 424 of the second sub-control module 420 restores the function of performing serial communication after outputting the sensor signal (S305).

  The main control module 400 transmits the generated motor drive signal to the first sub control module 410 via the serial communication line 406 as a signal line. The first sub control module 410 receives a motor drive signal. The first sub control module 410 outputs a drive pulse to the motor 104 without passing through the PWM signal generation unit 415 based on the received motor drive signal. The communication control unit 414 of the first sub-control module 410 restores the function of performing serial communication after receiving the motor drive signal (S306).

The restoration of the serial communication function in steps S305 and S306 may be performed after a predetermined time elapses after the sensor signal is output or the motor drive signal is received.
Alternatively, it may be triggered by reception of a specific serial communication packet. This specific serial communication packet is a unique signal pattern different from normal communication packets, sensor signals, and motor drive signals. In the signal communication mode, the transmission side and the reception side are fixed. Therefore, when the serial communication function is restored using a specific serial communication packet, the CPU 421 of the second sub-control module 420 controls the timing at which the serial communication function is restored. First, a specific serial communication packet is transmitted from the second sub control module 420 to the main control module 400. Then, a specific serial communication packet is transmitted from the main control module 400 to the first sub control module 410. In response to receiving the serial communication packet, the main control module 400 and the first sub control module 410 restore the serial communication function.

  After completing the output of the motor drive signal, the main control module 400 restores the serial communication function of the communication control unit 404 to sequentially perform settings necessary for the next control by serial communication (step S307).

  As described above, a signal for performing control with unimportant timing is performed by serial communication, and a signal for performing control with important timing is embedded in the serial communication lines 405 and 406 in a time division manner and transmitted. By using the serial communication lines 405 and 406 in this way, high-precision control such as position correction and reposition correction of the recording material is performed without using a dedicated control line and speeding up serial communication. be able to. Therefore, the wire cost is reduced, and noise countermeasures due to high-speed communication are not required.

[Second Embodiment]
The primary charging unit 221 and the developing unit 223 need to control a high voltage. High voltage control is generally performed using analog signals.
As shown in FIG. 5, also in the second embodiment, distributed control by the main control module 500, the third sub control module 530, and the fourth sub control module 540 is performed as in the first embodiment. The fourth sub control module 540 detects the analog signal, and the third sub control module 530 adjusts the pulse width of the PWM signal output from the high voltage drive circuit 515 according to the detected analog value. As described above, also in the second embodiment, distributed control is performed in accordance with restrictions on the configuration of the image forming apparatus 200 and restrictions on functions allocated to the third and fourth sub-control modules 530 and 540.

  The main control module 500 includes a CPU 501 that executes a program stored in the ROM 503 using the RAM 502 as a work area. Further, the communication control unit 504 can communicate with the third sub control module 530 and the fourth sub control module 540. Further, the main control module 500 includes an A / D converter 505.

  The third sub-control module 530 includes a CPU 531 that executes a program stored in the ROM 533 using the RAM 532 as a work area. The communication control unit 534 can communicate with the main control module 500. The high voltage drive circuit 515 outputs a PWM signal. The third sub control module 530 controls the transformer 516 by the PWM signal.

The fourth sub control module 540 can communicate with the main control module 500 by the communication control unit 544. The GPIO 545 is an input / output terminal having a plurality of general-purpose input / output ports. The fourth sub control module 540 transmits the analog signal input from the volume 546 to the main control module 500 via the communication control unit 544.
The configuration of the communication control units 504, 534, and 544 is the same as that shown in FIG.

5, the fourth sub-control module 540 A / D converts the analog voltage input from the volume 546 into a digital signal and transfers the digital signal to the main control module 500 by serial communication. To do. The main control module 500 transfers the digital signal to the third sub control module 530 after completing the reception of the digital signal sent from the fourth sub control module 540. The third sub-control module 530 can adjust the pulse width of the PWM signal when the reception of the transferred digital signal is completed. For example, the volume 546 changes a voltage value according to the output voltage of the transformer 516. With the above control, feedback to the high voltage drive circuit 515 can be realized, and the pulse width of the PWM signal is adjusted.
That is, it is necessary to prepare an A / D converter for A / D conversion of an analog signal, and a delay is caused by the time required for A / D conversion and two serial communication times.

In this embodiment, the serial communication lines 505 and 506 are switched between serial communication and analog signal communication in order to reduce the delay time without newly providing an A / D converter.
FIG. 6 is an explanatory diagram of a control flow of processing in which the serial communication lines 505 and 506 are switched between serial communication and analog signal communication.

The main control module 500 instructs the fourth sub-control module 540 to set a predetermined port of the GPIO 545 as a port to which an analog signal is input from the volume 546 by serial communication via the serial communication line 505 ( S701).
The main control unit 500 uses the serial communication line 505 as a sensor signal line for transmitting an analog signal to the communication control unit 544 of the fourth sub-control module 540 by serial communication via the serial communication line 505. An instruction is given (S702). In step S702, the communication control unit 544 of the fourth sub control module 540 switches from the serial communication mode to the signal communication mode.

  After step S702 is completed, the main control module 500 switches the communication control unit 504 to a general-purpose port. That is, the communication control unit 504 of the main control module 500 also switches from the serial communication mode to the signal communication mode. As a result, the main control module 500 can accept an analog signal from the fourth sub control module 540 via the serial communication line 505. When the analog signal is input from the fourth sub control module 540, the main control module 500 converts the analog signal into digital data by the A / D converter 505 (S703). Note that the communication control unit 544 of the fourth sub control module 540 restores the function of performing serial communication after the analog signal is transmitted.

  The main control module 500 transmits the converted digital data to the third sub control module 530 (S704). The high voltage driving circuit 515 of the third sub control module 530 adjusts the pulse width of the PWM signal according to the digital data received from the main control module 500. As a result, the high voltage of the primary charging unit 221 and the developing unit 223 can be controlled. After transmitting the digital data, the main control module 500 performs an operation setting for the next process (S705).

Here, an example in which the A / D converter 505 is provided in the main control module 500 is shown, but a configuration in which the A / D converter 505 is provided in the third sub-control module 530 may be used. In this case, the analog signal sent from the fourth sub control module 540 passes through the main control module 500 and is sent to the third sub control module 530.
As described above, a high voltage can be controlled without increasing the serial communication speed for transmitting an analog signal.

  400, 500 ... main control module, 410 ... first sub control module, 420 ... second sub control module, 530 ... third sub control module, 540 ... fourth sub control module, 405, 406, 505, 506 ... serial communication line. 401,411,421,501,531 ... CPU, 402,412,422,502,532 ... RAM, 403,413,423,503,533 ... ROM, 404,414,424,504,534,544 ... communication control Department. 430 ... WDT, 431 ... IRQC, 432 ... timer, 433 ... D / A converter, 434 ... A / D converter, 415 ... PWM signal generator, 425,545 ... GPIO, 515 ... high voltage drive circuit. 104: Motor, 256: Registration sensor, 516: Transformer, 546: Volume. 601: Data count unit, 602: Clock generation unit, 603: Buffer unit, 604: Parallel / serial conversion unit, 605 ... CPU bus, 606: Serial / parallel conversion unit.

Claims (5)

A main control module, and first and second sub-control modules each connected to the main control module via a serial communication line, between the main control module and the first and second sub-control modules A distributed control system for performing distributed processing by transmitting and receiving data via the serial communication line,
The main control module and the first and second sub-control modules can communicate in a first communication mode for serial communication and in a second communication mode in which data transfer is faster than serial communication, respectively. Having means,
The main control module is
The communication means of the first and second sub-control modules is switched from the first communication mode to the second communication mode by serial communication, and the communication means of the main control module is switched to the first communication mode. Switching means for switching from the second communication mode to the second communication mode;
Control means for transmitting control data to the second sub-control module in the second communication mode according to data received from the first sub-control module in the second communication mode. Features
Distributed control system. Each communication control means of the main control module and the first and second sub control modules terminates communication in the second communication mode after switching from the first communication mode to the second communication mode. Returning to the first communication mode after or after elapse of a predetermined time,
The distributed control system according to claim 1. The first sub-control module transmits data representing a detection result of a predetermined device to the main control module in the second communication mode,
The second sub-control module controls the operation of a device connected to the second sub-control module based on the control data received from the main control module.
The distributed control system according to claim 2. The first sub-control module detects a state caused by the device connected to the second sub-control module;
The control means of the main control module sends the control data for controlling the operation of the device connected to the second sub-control module according to the data representing the detection result to the second communication. Transmitting to the second sub-control module according to a mode,
The distributed control system according to claim 3. Data transfer between the first and second sub-control modules connected by the serial communication line via the serial communication line is faster than the first communication mode in which serial communication is performed and the serial communication. A control device that performs communication in two communication modes and is capable of distributed processing using the first and second sub-control modules,
The communication mode of the first and second sub-control modules is switched from the first communication mode to the second communication mode by serial communication, and the communication mode of the own device is changed from the first communication mode to the second communication mode. Switching means for switching to the second communication mode;
Control means for transmitting control data to the second sub-control module in the second communication mode according to data received from the first sub-control module in the second communication mode. Features
Control device.

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