JP2018202769A - Image forming system - Google Patents

Abstract

To provide an image forming system having an image forming device and an option device, which can reduce deviations of timing for starting carrying speed control between the respective devices.SOLUTION: The image forming system comprises: an image forming device including first control means; an option device including second control means; a first serial signal line for transmitting a clock signal; a second serial signal line for transmitting a command signal; and a third serial signal line for transmitting an interruption signal. When speed at which a recording member is carried is changed to a target speed while the same recording member is carried by both first carrying means and second carrying means, the first control means and the second control means start control for changing the speed at which the recording member is carried by the first carrying means and the second carrying means to the target speed on the basis of timing at which the interruption signal is transmitted.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an image forming apparatus having an image forming apparatus such as a copying machine and a printer, and an optional device connected to the image forming apparatus.

  Conventionally, as an optional device connected to an image forming apparatus such as a copying machine or a printer, a paper feed option device that feeds paper to the image forming device or a paper on which an image is formed by the image forming device is received and post-processed. For example, a paper discharge option device. In order for these optional devices and the main body of the image forming apparatus to perform processing synchronously, it is necessary to communicate and exchange information with each other.

  Patent Document 1 discloses that serial communication can be synchronized between the CPU of the image forming apparatus and the CPU of the optional apparatus without adding a dedicated signal line other than the clock signal line and the data signal line. A configuration is disclosed. In the configuration of Patent Document 1, a command signal line as a data signal line branches in the middle, and the branched signal line is connected to the interrupt port of the CPU of the option device. As a result, the CPU of the option device can determine that communication from the CPU of the image forming apparatus has started in response to a change in the level of the command signal.

JP 2011-187079 A

  As an example in which an image forming apparatus and an optional apparatus perform processing in synchronization, there is sheet conveyance control. The image forming apparatus performs sheet acceleration / deceleration control based on the timing when the leading edge of the sheet is detected by a sensor arranged in the conveyance path in order to cope with sheet take-out or slip in the main body sheet cassette. Yes. At this time, when the roller pairs of the image forming apparatus and the paper feed option apparatus hold the same sheet, it is necessary to perform acceleration / deceleration control by aligning the movements of both roller pairs. Therefore, the CPU of the image forming apparatus transmits the obtained acceleration / deceleration amount (target speed) to the CPU of the paper feed option device via the serial signal line. The CPU of the paper feed option device controls the roller pair of the paper feed option device according to the received acceleration / deceleration amount, and performs acceleration / deceleration control so as to align with the movement of the roller pair of the image forming device.

  However, in the conventional clock-synchronized communication method, since communication is performed at a predetermined control cycle, the acceleration / deceleration amount is transmitted to the CPU of the sheet feeding option device after the CPU of the image forming apparatus obtains the acceleration / deceleration amount. Time lag may occur. The CPU of the image forming apparatus starts the acceleration / deceleration control immediately after obtaining the acceleration / deceleration amount, but the CPU of the paper feed option device starts the acceleration / deceleration control after receiving the acceleration / deceleration amount via the serial signal line. . As a result, there may be a difference between the start timing of acceleration / deceleration control by the image forming apparatus and the start timing of acceleration / deceleration control by the paper feed option device. When a deviation occurs in the acceleration / deceleration control start timing, a period in which the movement of the roller pair of the image forming apparatus and the roller pair of the paper feed option apparatus is not aligned occurs. As a result, a phenomenon occurs in which the paper is pushed into the image forming apparatus from the paper feeding option device or the paper is pulled between the paper feeding option device and the image forming apparatus, and the paper is wrinkled or creased. End up. Such a phenomenon may occur not only between the image forming apparatus and the paper feed option apparatus but also between the image forming apparatus and the paper discharge option apparatus.

  An object of the present invention is to reduce a shift in the start timing of conveyance speed control in each apparatus in an image forming system having an image forming apparatus and an optional apparatus.

  In order to achieve the above object, an image forming system of the present invention includes an image forming unit that forms an image on a recording material, a first conveying unit that conveys the recording material, a detection unit that detects the recording material, An image forming apparatus including a first control unit that obtains a target speed based on the timing at which the recording material is detected by the detection unit, and changes the conveyance speed of the recording material by the first conveyance unit to the target speed; A second conveying unit that conveys the material; a second control unit that changes a conveying speed of the recording material by the second conveying unit; A first serial signal line for transmitting a clock signal from the first control means to the second control means in a state in which the optional device is attached to the forming apparatus; and First A second serial signal line for transmitting a command signal from the control means to the second control means, a branch from the second serial signal line, and communication from the first control means to the second control means In the image forming system having a third serial signal line for transmitting an interrupt signal indicating that the recording material is started, a period during which the same recording material is conveyed by both the first conveying unit and the second conveying unit In addition, when the recording material conveyance speed by the first conveyance means and the second conveyance means is changed to the target speed, the first control means controls the third control means with respect to the third control means. After transmitting the interrupt signal via the serial signal line, the command signal relating to the target speed is transmitted via the second serial signal line, and the first control means and the second control means are , Said discount The timing at which the write signal is transmitted on the basis, characterized in that each conveying speed of the recording material by the first conveying means and said second conveying means starts the control for changing to the target speed.

  An image forming system of the present invention for achieving the above object includes an image forming unit that forms an image on a recording material, a first conveying unit that conveys the recording material, and a detecting unit that detects the recording material. An image forming apparatus including a first control unit that obtains a target speed based on the timing at which the recording unit is detected by the detection unit and changes the conveyance speed of the recording material by the first conveyance unit to the target speed; An optional device that includes a second transport unit that transports the recording material, and a second control unit that changes a transport speed of the recording material by the second transport unit, and is detachable from the image forming apparatus; A first serial signal line for transmitting a clock signal from the first control means to the second control means in a state where the optional device is attached to the image forming apparatus, and in synchronization with the clock signal. The A second serial signal line for transmitting a command signal from the first control means to the second control means, and the command from the second control means to the first control means in synchronization with the clock signal. A third serial signal line for transmitting a status signal corresponding to the signal and a branch from the third serial signal line, and receiving the command signal from the second control means to the first control means. In the image forming system having the fourth serial signal line for transmitting the interrupt signal, the first conveying unit and the second conveying unit both convey the same recording material during the first conveying unit. When changing the conveyance speed of the recording material by the conveyance means and the second conveyance means to the target speed, the first control means passes the second serial signal line to the second control means. After transmitting the command signal related to the target speed, the second control unit transmits the interrupt signal to the first control unit via the fourth serial signal line, and the first control unit And the second control means change the recording material conveying speed by the first conveying means and the second conveying means to the target speed, respectively, based on the timing at which the interrupt signal is transmitted. The control to start is characterized by starting.

  According to the present invention, in an image forming system having an image forming apparatus and an optional apparatus, it is possible to reduce a shift in the start timing of the conveyance speed control in each apparatus.

Schematic diagram showing the configuration of the image forming system Control block diagram of image forming system Timing chart showing in-flight communication system Flow chart representing conventional synchronous acceleration / deceleration control Timing chart showing problems of the present invention Graph of paper feed motor speed showing the subject of the present invention Timing chart showing synchronous acceleration / deceleration control of embodiment 1 Processing flow of printer main body in embodiment 1 Processing flow of optional device in embodiment 1 Timing chart showing synchronous acceleration / deceleration control of embodiment 2 FIG. 6 is a diagram illustrating wiring of an image forming system in Embodiment 2. Processing flow of printer main body in embodiment 2 Processing flow of optional device in embodiment 2

Example 1
In this embodiment, an electrophotographic color laser beam printer 10 (hereinafter referred to as a printer main body 10) is shown as an image forming apparatus for forming an image on a recording material. In addition, as an optional device that can be attached to and detached from the image forming apparatus, a feeding option device 100 that feeds a recording material to the image forming apparatus (hereinafter referred to as an optional device 100) is shown. FIG. 1 is an overall configuration diagram of an image forming system in which an optional device 100 is attached to a printer main body 10. The functions of the respective members constituting the printer main body 10 and the optional device 100 will be described sequentially. In the following description, the first, second, third, and fourth stations are used as toner image forming stations for yellow (Y), magenta (M), cyan (C), and black (K), respectively. .

(Image forming part)
First, the first station will be described among the four stations. Reference numeral 1a denotes an OPC photosensitive drum as an image carrier. The photosensitive drum 1a is formed by laminating a plurality of functional organic materials including a carrier generation layer that generates a charge by exposure on a metal cylinder, a charge transport layer that transports the generated charge, and the outermost layer is electrically conductive. It is low and almost insulated. Both ends of the photosensitive drum 1a are rotatably supported by flanges, and are driven to rotate in the direction of the arrow in FIG. 1 when a driving force is transmitted to one end from a driving motor (not shown).

  Next, as a charging unit, the charging roller 2a is brought into contact with the photosensitive drum 1a, and the surface of the photosensitive drum 1a is uniformly charged while being driven to rotate as the photosensitive drum 1a rotates. The charging roller 2a is conductive, and a DC voltage or a voltage on which an AC voltage is superimposed is applied. As a result, discharge occurs in a minute air gap near the contact nip between the surface of the charging roller 2a and the photosensitive drum 1a, and the photosensitive drum 1a is charged. The scanner unit 11a as an exposure unit irradiates the photosensitive drum 1a with a scanning beam 12a modulated based on an image signal. Thereby, an electrostatic latent image is formed on the photosensitive drum 1a. The exposure means may be constituted by an LED array. The developing unit 8a as a developing unit includes a developing roller 4a that is in contact with the photosensitive drum 1a, a nonmagnetic one-component developer 5a (toner), and a developer coating blade 7a. The developing roller 4a is rotated by a driving force transmitted from a driving motor (not shown), and further, a developing bias voltage is applied to develop the electrostatic latent image on the photosensitive drum 1a with toner. The toner image on the photosensitive drum 1a formed in this way is primarily transferred to the intermediate transfer belt 80 by the primary transfer roller 81a. The cleaning unit 3a cleans the toner remaining on the photosensitive drum 1a without being transferred.

  The charging roller 2a, the developing roller 4a, and the primary transfer roller 81a are respectively connected to a charging bias power source 20a, a developing bias power source 21a, and a primary transfer bias power source 84a that are voltage supply means. The photosensitive drum 1a, the charging roller 2a, the developing unit 8a, and the cleaning unit 3a are combined as an integrated process cartridge 9a that can be detached from the printer main body 10. The above is the configuration of the first station, and the second, third, and fourth stations have the same configuration. The members of the second, third, and fourth stations are represented by the symbols b, c, and d, respectively, instead of the symbol a.

  The intermediate transfer belt 80 is supported by three rollers, that is, a secondary transfer counter roller 86, a driving roller 14, and a tension roller 15, so that an appropriate tension is maintained. When the drive roller 14 is rotationally driven, the intermediate transfer belt 80 moves in the forward direction at substantially the same speed with respect to the photosensitive drums 1a to 1d. That is, the intermediate transfer belt 80 rotates in the direction of the arrow in FIG. The primary transfer rollers 81a to 81d are disposed inside the intermediate transfer belt 80 at positions facing the photosensitive drums 1a to 1d, respectively. Further, neutralization members 23a to 23d are arranged on the downstream side of the primary transfer rollers 81a to 81d in the rotation direction of the intermediate transfer belt 80, respectively. The driving roller 14, the tension roller 15, the neutralizing members 23a to 23d, and the secondary transfer counter roller 86 are electrically grounded. The primary transfer rollers 81 a to 81 d are charged to a positive polarity, and attract the negative polarity toner through the intermediate transfer belt 80. As a result, the toner images of the respective colors on the photosensitive drums 1 a to 1 d are sequentially transferred to the intermediate transfer belt 80, and a multicolor image is formed on the intermediate transfer belt 80.

(Paper feed section)
The printer main body 10 has a main body cassette 16 for storing paper P. When the paper P is fed from the main body cassette 16, the main body pickup roller 17 is driven to rotate. By rotating the main body pickup roller 17, the sheets P installed in the main body cassette 16 are separated and fed one by one and conveyed to the registration roller 18.

  The option device 100 has an option cassette 101 that stores paper P. When the paper P is fed from the option cassette 101, the option pickup roller 105 is driven to rotate. As a result, the paper P is transported from the option cassette 101 to the paper feed roller 102 and the transport roller 103. The transport roller 103 is a roller for transporting the paper P fed from the option cassette 101 to the printer main body 10. The conveyance path sensor 104 is a sensor that detects the paper P fed from the option cassette 101. Note that the image forming system of this embodiment shows a configuration in which one optional device 100 is connected to the lower portion of the printer main body 10, but a plurality of optional devices 100 are sequentially connected to the lower portion of the optional device 100. It is also possible to continue.

  The registration sensor 35 detects the leading edge of the paper P fed from the main cassette 16 and the option cassette 101. The printer main body 10 of the present embodiment accelerates or decelerates the transport speed without stopping the paper P based on the timing at which the registration sensor 35 detects the leading edge of the paper P. As a result, the position of the paper P is adjusted so that the timing coincides with the toner image formed on the intermediate transfer belt 80. Before the leading edge of the paper P reaches the merge point 36, the printer main body 10 returns the transport speed of the paper P to the speed before the change, and transports the paper P to the secondary transfer unit. Hereinafter, this control is referred to as acceleration / deceleration control.

(Secondary transfer part)
The intermediate transfer belt 80 constituting the secondary transfer unit is circulated and moved by the driving roller 14 and electrostatically adsorbs toner to the outer peripheral surface facing the photosensitive drums 1a to 1d. As a result, a multicolor toner image is formed on the outer periphery of the intermediate transfer belt 80, and the toner image formed on the intermediate transfer belt 80 reaches the contact nip portion between the secondary transfer roller 82 and the intermediate transfer belt 80 which is the secondary transfer position. Be transported. When transporting the paper P, the secondary transfer bias power supply 85 applies a voltage to the secondary transfer roller 82 to form an electric field between the secondary transfer roller 82 and the secondary transfer counter roller 86. Then, dielectric polarization is generated between the intermediate transfer belt 80 and the paper P, and an electrostatic attracting force is generated between them. The toner image formed on the intermediate transfer belt 80 is secondarily transferred to the paper P at the secondary transfer position.

(Fixing part)
The fixing unit 19 applies heat and pressure to the toner image secondarily transferred onto the paper P to fix the toner image on the paper P. The fixing unit 19 has a fixing belt (not shown) and an elastic pressure roller (not shown). The elastic pressure roller sandwiches the fixing belt and forms a fixing nip portion with a predetermined width with a predetermined pressure contact force with a belt guide member (not shown). In a state where the fixing nip portion rises to a predetermined temperature and is adjusted in temperature, the paper P on which an unfixed toner image is formed is conveyed from the secondary transfer portion. The sheet P is conveyed between the fixing belt as the fixing nip portion and the elastic pressure roller in such a manner that the surface (image surface) on which the unfixed toner image is formed faces the fixing belt. Then, the sheet P is nipped and conveyed while the image surface is in close contact with the outer surface of the fixing belt at the fixing nip portion. In this process, the unfixed toner image on the paper P is heated and fixed on the paper P.

(Control part of image forming system)
FIG. 2 is a control block diagram of the image forming system according to the present invention. The host computer 200 is an external device such as a PC. The printer main body 10 has a controller unit 201 and an engine control unit 202, and the option device 100 has an option control unit 230.

  The controller unit 201 can communicate with the host computer 200 and the engine control unit 202. The controller unit 201 receives image information and a print command from the host computer 200, analyzes the received image information, and converts it into bit data. Then, a print reservation command, a print start command, and a video signal are transmitted to the CPU 211 and the image processing unit 212 for each sheet P via the video interface unit 210.

  The CPU 211 prepares for execution of printing in the order of print reservation commands from the controller unit 201 and waits for a print start command from the controller unit 201. When receiving the print instruction, the CPU 211 instructs each control unit (the image formation control unit 213, the fixing control unit 214, and the feeding control unit 215) to start the printing operation according to the information of the print reservation command.

  When receiving the start of the printing operation, the image formation control unit 213 starts preparation for image formation. When the CPU 211 receives from the image formation control unit 213 a signal notifying that preparation for image formation has been completed, the CPU 211 outputs to the controller unit 201 a / TOP signal that serves as a reference timing for video signal output. When the controller unit 201 receives the / TOP signal from the CPU 211, the controller unit 201 outputs a video signal based on the / TOP signal. When receiving a video signal from the controller unit 201, the image processing unit 212 transmits image formation data to the image formation control unit 213. The image formation control unit 213 performs image formation based on the image formation data received from the image processing unit 212.

  When the feeding control unit 215 receives the start of the printing operation, the feeding control unit 215 starts the paper feeding operation. The feed control unit 215 rotates the stepping motor 223 to instruct the pickup solenoid 224 to start driving at the pickup timing of the paper P. As a result, the main body pickup roller 17 is rotationally driven, and the paper P is fed from the main body cassette 16. When the registration sensor 35 detects the leading edge of the paper P, the feeding control unit 215 starts acceleration / deceleration control by the registration roller 18 in order to eliminate variations in timing when the paper P reaches the registration sensor 35. . That is, the feeding control unit 215 obtains the target speed of the paper P based on the timing when the leading edge of the paper P is detected by the registration sensor 35, and accelerates or decelerates the transport speed of the paper P toward the target speed. . The feeding control unit 215 changes the speed of the stepping motor 223 so that the leading edge of the paper P and the leading edge of the image are aligned at the merge point 36. After reaching the merge point 36, the speed of the stepping motor 223 is returned to the speed before execution of acceleration / deceleration control, and the paper P is conveyed to the secondary transfer position. In this embodiment, the stepping motor 223 is configured to drive at least the main body pickup roller 17 and the registration roller 18.

  The fixing control unit 214 starts fixing preparation when it receives the printing operation start. The fixing control unit 214 starts temperature adjustment according to the information of the print reservation command in accordance with the timing when the paper P is conveyed from the feeding control unit 215. The fixing control unit 214 fixes the image on the paper P and conveys the paper P to the outside of the apparatus.

  The option control unit 230 has a microcomputer incorporating a CPU 231 and the like. The CPU 231 performs data communication processing using serial communication with the engine control unit 202 and controls each unit of the option device 100 in accordance with instructions from the engine control unit 202. The communication will be described in detail later. When feeding from the option device 100, the engine control unit 202 instructs the option control unit 230 to feed paper. The option control unit 230 that has received a paper feed instruction from the engine control unit 202 instructs the option feed control unit 232 to perform a paper feed operation. Receiving the instruction for the sheet feeding operation, the option feeding control unit 232 rotates the stepping motor 234 at the instructed speed and drives the pickup solenoid 235. As a result, the option pickup roller 105 is rotationally driven, and the paper P is fed from the option cassette 101. In this embodiment, the stepping motor 234 is configured to drive the option pickup roller 105 and the conveyance roller 103.

(Communication interface)
In-flight communication interface signals between the CPU 211 of the engine control unit 202 and the CPU 231 of the option control unit 230 in FIG. 2 are transmitted using the following three serial signal lines. The transmitted signals are a clock signal (hereinafter referred to as “CLK signal”), a command signal (hereinafter referred to as “CMD signal”), and a status signal (hereinafter referred to as “STS signal”). A signal line to which the CLK signal is transmitted is referred to as a clock signal line, a signal line to which the CMD signal is transmitted is referred to as a command signal line, and a signal line to which the STS signal is transmitted is referred to as a status signal line.

  In the image forming system of this embodiment, the command signal line is branched in the option device 100. The branched signal line is connected to the interrupt port of the CPU 231 of the option device 100. A CMD interrupt signal is transmitted to the CPU 231 via the branched signal line. The interrupt port of the CPU 231 is a level interrupt, and an interrupt is generated when the signal becomes a low level (depending on the setting).

(Communication method)
A serial communication method between the printer main body 10 and the optional device 100 in the image forming system according to the present invention will be described with reference to FIG. FIG. 3 is a timing chart showing a serial communication method. In the communication, a plurality of processes are performed for each communication unit, and continuous communication is performed between devices by continuously repeating each communication unit.

  In the figure, 301 indicates the communication start timing of one communication unit, 302 indicates the communication end timing (also the start timing of the next communication), and the time required between them is the time required to perform one communication (= communication cycle). ). The printer main body 10 holds the level of the CMD signal at the high level before starting communication, and sets it to the low level at the start of communication (301) (310).

  On the other hand, in the option device 100, the interrupt port is set to permit interrupt before the start of communication (301). This interrupt port is a level interrupt, and is set so that an interrupt is generated when the signal goes low. Therefore, when the printer main body 10 changes the signal level of the CMD signal (= CMD interrupt signal) from the high level to the low level (310) at the start of communication, an interrupt is generated in the option device 100. Hereinafter, the interruption by the CMD interruption signal is referred to as “CMD interruption”. When the CMD interrupt occurs, the option device 100 determines the start of communication, disables the setting of the interrupt port to which the CMD interrupt signal 228 is connected, and prepares for CMD reception.

  The printer main body 10 transmits a CMD transmission CLK signal 307 and a CMD signal 311. When the transmission of the CMD signal 311 is completed, the level of the CMD signal is set to a high level (312) and the next communication start (302). Hold that state. After setting the level of the CMD signal to High level, the printer main body 10 outputs the STS reception CLK signal 308 and receives the STS signal 315 from the option device 100. Upon receiving the CMD signal 311, the option device 100 analyzes the received command and prepares an STS to be transmitted to the printer main body 10. Thereafter, the STS signal 315 is transmitted in synchronization with the STS transmission CLK signal 308, and at the same time as the transmission is completed, the interrupt port is set to the interrupt-permitted state to prepare for the start of the next communication.

(Problems arising during communication)
A problem that occurs when performing communication control between the printer main body 10 and the option device 100 will be described. Here, the synchronous acceleration / deceleration control of the paper P between the printer main body 10 and the optional device 100 will be described as an example. That is, an example will be described in which acceleration / deceleration control is performed in a state where the registration roller 18 of the printer main body 10 and the transport roller 103 of the option device 100 hold the same sheet P after feeding the sheet P from the option cassette 101. .

  First, the conventional synchronous acceleration / deceleration control of the paper P will be described with reference to the flowchart of FIG. This flowchart includes steps from accelerating (decelerating) the paper P to returning to the original speed again. The CPU 211 determines whether or not the leading edge of the paper P being conveyed by the printer main body 10 has reached the registration sensor 35 (at this time, the registration sensor 35 is On) (S401). When it is determined that it has arrived, the CPU 211 starts preparations for shifting to acceleration / deceleration control. Specifically, a necessary acceleration / deceleration amount is obtained from the current conveyance speed of the paper P and the timing of the TOP signal, and a target speed v and a time t for maintaining the speed are calculated (S402). Thereafter, the CPU 211 starts acceleration / deceleration control of the paper P on the printer body side (S403), and controls the stepping motor 223. Then, the CPU 211 instructs the option device 100 to start acceleration / deceleration using in-flight communication (S404). Then, the CPU 211 sets a timer for returning the accelerated / decelerated speed to the original speed (S405), waits for the elapse of the speed maintenance time t (S406), and then performs the speed return operation of the printer body 10 (S407). . Immediately thereafter, the CPU 211 instructs the option device 100 to execute the speed return operation (S408).

  Next, the problem of the conventional example will be described with reference to FIG. FIG. 5 is a timing chart for explaining a problem about the synchronous acceleration / deceleration control of the printer main body 10 and the optional device 100 using in-machine communication according to the present invention.

  First, it is assumed that the leading edge of the paper P reaches the registration sensor 35 at the timing A in the figure during communication. At this time, the CPU 211 of the printer main body 10 starts acceleration / deceleration control of the printer main body 10 immediately after timing A. The option device 100 is instructed to execute acceleration / deceleration control using the CMD signal 514. This is because the CMD signal transmitted from the printer main body 10 to the option device 100 is determined at the start of paper feeding. That is, when a CMD signal to be transmitted is determined at any timing between 501 and 502, the CMD signal 514 of the next communication cycle (control cycle) is transmitted. After analyzing the CMD signal 514, the CPU 231 of the option device 100 starts acceleration / deceleration control of the option device 100 at timing C. Therefore, at this time, the start timing of the acceleration / deceleration control of the option device 100 is delayed by a with respect to the printer body 10. When the leading edge of the paper P reaches the registration sensor 35 at the timing B in the figure, the acceleration / deceleration control start timing of the printer body 10 is B, and the acceleration / deceleration control start timing of the option device 100 is C. . Accordingly, at this time, the start timing of the acceleration / deceleration control of the option device 100 is delayed by b with respect to the printer body 10.

  In the synchronous control, ideally, it is desirable that the acceleration / deceleration control of the printer body 10 and the option device 100 is started at the same timing. However, as described above, the start timing of acceleration / deceleration control in the option device 100 is deviated due to delays (a, b) caused by communication between the printer main body 10 and the option device 100. Further, the delay varies depending on the timing when the leading edge of the paper P reaches the registration sensor 35 (a ≠ b). Therefore, in the conventional control method, there is a problem that the start timing of the conveyance control in the printer main body 10 and the option device 100 is shifted, and it varies every time.

  FIG. 6 schematically shows how the delay caused in this way affects the conveyance speed of the paper P of the printer main body 10 and the optional device 100.

  FIG. 6 shows changes in the speeds of the paper feed motors (stepping motor 223 and stepping motor 234) of the printer body 10 and the optional device 100 from when the paper P is conveyed and the registration sensor 35 is turned on until the merge point 36 is reached. Represents. As described above, the paper feed motor decelerates simultaneously with the registration sensor 35 On, and reduces the speed to the target speed v. Then, after maintaining the speed as it is for the speed maintenance time t, control is performed to restore the speed until the leading edge of the paper P reaches the merge point 36. v and t are values calculated by the CPU 211 of the printer body 10 after the registration sensor 35 is turned on as described above. Here, the motor speed in the optional device 100 represented by the broken line is the same as the motor speed in the printer main body 10 represented by the solid line, and the timing of the acceleration / deceleration control is entirely due to the delay caused by the communication described above. You can see that it is late. When such a delay occurs, a situation occurs in which the speeds of the two motors are always different during acceleration / deceleration, and there is a risk that both ends of the paper P will be pushed in and bend.

  Considering FIG. 6, since the motor speed on the option device side is high at the time of deceleration of 601, the paper P is pushed into the roller (registration roller 18) of the printer main body 10. Since the motor speed on the option device side is slow at the time of acceleration 602, the paper P is pulled by the roller (registration roller 18) of the printer main body 10. In FIG. 6, the delay occurring at the time of deceleration 601 and the delay occurring at the time of acceleration 602 are drawn to the same extent. However, since the delay due to normal communication is different once each time, there is a high possibility that both delays are different. In FIG. 6, the case of deceleration control has been described, but the above phenomenon also occurs in the acceleration / deceleration section in the case of acceleration control (however, the magnitude relationship between the motor speeds of the printer body 10 and the optional device 100 is reversed). Become). In this case, tension is applied by pulling both ends of the paper P, and a phenomenon occurs such that one end or both ends of the paper P is deviated from the rollers being sandwiched.

(Acceleration / deceleration control of this embodiment)
The synchronous acceleration / deceleration control of the printer main body 10 and the optional device 100 in this embodiment will be described.

  FIG. 7 is a timing chart showing the movement from the registration sensor 35 to On until acceleration / deceleration control is started in this embodiment. When the paper P is conveyed and the registration sensor 35 is turned on, the CPU 211 of the printer main body 10 calculates the acceleration / deceleration amount of the paper P as described above. The registration sensor 35 is turned on at an arbitrary timing between 701 and 702. Here, the CPU 211 in this embodiment does not immediately start the acceleration / deceleration control after calculating the acceleration / deceleration amount. Then, the CPU 211 waits for the next communication start 702 and sets a timer. The starting signal at this time is a timing at which the CMD signal changes from High to Low at the start of communication, and a timer for the printer main body is set based on the timing. The actual acceleration / deceleration control start timing is after the printer body 10 transmits a CMD signal 718 including information such as a target speed to the option device 100. The option device 100 sets a timer for the option device using 717 as a trigger. The timer is set by interrupt control using a signal line branched from the CMD signal line and connected to the interrupt port of the CPU 231. The CPU 211 of the printer main body 10 turns on the acceleration / deceleration command at the timing when the time counted by the timer for the printer main body reaches a certain time, and starts the acceleration / deceleration control. The CPU 231 of the option device 100 turns on the acceleration / deceleration command at the timing when the time counted by the timer for the option device reaches the same fixed time as the printer body 10 and starts the acceleration / deceleration control. In this way, the printer main body 10 and the optional device 100 can start acceleration / deceleration control ideally at the same timing (practically a slight deviation occurs). In this embodiment, in order to confirm that the option device 100 has received the CMD signal 718 normally, the timer time is set so that the acceleration / deceleration control is started after the STS signal 721 is returned from the option device 100 to the printer body 10. Is set.

  Next, the processing flow of the printer main body 10 and the optional device 100 in this embodiment will be described with reference to FIGS.

  First, FIG. 8 will be described. The control based on FIG. 8 is executed by the CPU 211 of the printer main body 10 based on a program stored in a ROM or the like. First, after the leading edge of the paper P reaches the registration sensor 35 and the CPU 211 calculates the acceleration / deceleration amount, the printer body 10 waits for the start of the next communication cycle. Then, at the start timing of the next communication cycle, the CPU 211 sets the CMD signal from High to Low (S801), and sets the timer for the printer main body based on the change (S802). Thereafter, the CPU 211 transmits a CMD signal 718 to the option device 100 (S803), and transmits information on the target speed of acceleration / deceleration control and the like to the CPU 231 of the option device 100. Next, the printer body 10 moves to preparation for receiving an STS signal. When a return STS signal 721 is sent from the CPU 231, the CPU 211 receives it (S804). Information indicating whether the CMD signal 718 transmitted from the printer body 10 to the option device 100 has been normally received is added to this signal. When the reception operation of the STS signal 721 is completed, the CPU 211 performs analysis (S805) and checks whether the signal content is appropriate (S806). When this signal is not appropriate, the printer main body 10 determines that the communication has failed, the CPU 211 cancels the acceleration / deceleration timer (S807), waits for the next communication, and tries the same operation again. If the communication is successful, after waiting for the timer time T to elapse (S808), the CPU 211 starts the acceleration / deceleration control of the printer body 10 (S809). When the CPU 211 determines that the conveyance speed has reached the target speed v (S810), the CPU 211 stops the acceleration / deceleration on the main body side (S811). Then, as described with reference to FIG. 4, the process proceeds to the step of returning to the speed before the acceleration / deceleration control is started.

  Next, FIG. 9 will be described. The control based on FIG. 9 is executed by the CPU 231 of the option device 100 based on a program stored in a ROM or the like. In the option device 100, first, the interrupt of the interrupt port for setting the acceleration / deceleration start timer is permitted (S901). This permission is an interrupt permission performed when the CPU 231 finishes transmitting an STS signal (for example, 720) for each communication. The interrupt control is activated by detecting a change 717 of the CMD signal from High to Low (S902). When the interrupt is activated, the acceleration / deceleration start timer of the option device 100 is set (S903). Immediately thereafter, the option device 100 prohibits the interrupt of the acceleration / deceleration timer interrupt port (S904). Thereafter, the CPU 231 receives the CMD signal 718 transmitted from the printer main body 10 (S905), analyzes the signal content (S906), and determines whether the content is appropriate (S907). This signal also functions as an instruction to determine whether to perform acceleration / deceleration control in addition to the target value for acceleration / deceleration. When acceleration / deceleration is not performed, the printer body 10 does not transmit the target value. As a result of the determination, if there is a problem such that the target value for acceleration / deceleration is not appropriate (including the case where the target value is not transmitted) or communication is not successful, the CPU 231 issues an acceleration / deceleration start command. Release is performed (S908). Then, the next communication cycle is awaited, and the process is restarted from the interrupt permitting step (S901) of the acceleration / deceleration timer interrupt port. If the contents are appropriate, the CPU 231 transmits an STS signal 721 to the printer body 10 (S909). Then, after waiting for the timer time T to elapse (S910), the CPU 231 starts acceleration / deceleration on the option device side (S911) (Although after the transmission of the STS signal, the acceleration / deceleration timer interrupt port is also permitted, Since it is the same operation as S901, it is omitted here). When it is determined that the conveyance speed has reached v as in the printer main body 10 (S912), the CPU 231 stops acceleration / deceleration on the option side (S913).

  As described above, in this embodiment, a series of synchronous acceleration / deceleration control that has been started at the timing when the leading edge of the paper P has reached the registration sensor 35 is started from the change of the communication signal during communication. To do. The timer time T set at the starting point needs to be set so that acceleration / deceleration is started after the transmission of the CMD signal 718 in which the control information is transmitted from the printer body 10 to the option device 100. By performing control that satisfies the above points, timing delay due to communication is improved during synchronous control between the printer main body 10 and the optional device 100 (ideally, it is eliminated, but in reality, errors occur due to various processes. )can do.

  In this embodiment, the CPU 211 receives the STS signal 721, and after confirming that the CPU 231 has received the CMD signal 718 normally, the acceleration / deceleration control of both the printer body 10 and the option device 100 is started. However, it is not limited to this. It is also possible to perform acceleration / deceleration control after the CPU 231 receives the CMD signal 718 and before the CPU 211 receives the STS signal 721. At this time, the CPU 211 cannot perform the above confirmation, but since the acceleration / deceleration control can be started earlier, the distance of the paper P that can be adjusted by the acceleration / deceleration control can be increased.

  In this embodiment, the acceleration / deceleration control is performed starting from the change of the communication CMD signal. However, it is also possible to use the CLK signal or the STS signal as shown in the next embodiment. In addition, the signal change that is the starting point is the signal change 717 that first occurs in one communication cycle, but other signal changes can be used as shown in the following embodiment. However, since the communication itself usually starts with the first signal change in the communication cycle as the starting point, it is better to use this position as the starting point in terms of synchronization with the communication.

(Example 2)
A second embodiment of the present invention will be described. In the present embodiment, with respect to the device configuration and the control method, the same portions as those in the first embodiment are omitted, and only different portions will be described.

  FIG. 10 is a timing chart showing the state of the synchronous acceleration / deceleration control in the present embodiment. This embodiment is different from the first embodiment in that the starting point of acceleration / deceleration is the STS signal, and the starting point of acceleration / deceleration is not the start part of the communication cycle. In this embodiment, after the leading edge of the paper P turns the registration sensor 35 on, the CMD signal of the next communication is changed from High to Low, and at the same time, the interrupt control of the acceleration / deceleration start command on the main body side is permitted. I do. Thereafter, the acceleration / deceleration control on the option device side is started from the timing 1021 when the STS signal is set from High to Low. This change of the STS signal is not performed unless the registration sensor 35 is turned on (the arrival of the paper P can be known from the content of the CMD signal 1018 from the printer main body 10). Unlike the first embodiment, the timer is not used for the acceleration / deceleration command at this time. At the same time, also on the printer body side, the acceleration / deceleration start command on the printer body side is set by interrupt processing, using the change in the STS signal as a trigger, and acceleration / deceleration control is started without using a timer.

  This interrupt processing is performed using a signal line branched from the STS signal line as shown in FIG. 11 and connected to the interrupt port of the CPU 211 on the printer body side. FIG. 11 is a diagram showing only the in-machine communication interface between the printer main body 10 and the optional device 100, and all elements other than those related to in-machine communication are omitted. After the interruption is completed, the printer main body 10 prohibits interruption processing of the interruption port. In FIG. 11, an interrupt signal line branched from the CMD signal line is provided in the same manner as in the first embodiment. However, instead of this, a dedicated signal line for informing the start of communication from the CPU 211 to the CPU 231 may be provided. Good. That is, the interrupt signal line branched from the CMD signal line in the second embodiment may not be provided.

  Next, the processing flow of the printer main body 10 and the optional device 100 in this embodiment will be described with reference to FIGS.

  First, FIG. 12 will be described. The control based on FIG. 12 is executed by the CPU 211 of the printer main body 10 based on a program stored in a ROM or the like. After the registration sensor 35 is turned on, the CPU 211 permits interrupt of the interrupt port on the main body side at the same time as the occurrence of the first CMD signal High → Low event (S1201) (S1202). After transmitting the CMD signal related to acceleration / deceleration to the option device 100 (S1203), the CPU 211 detects that the STS signal changes from High to Low (S1204), and sets the acceleration / deceleration start command on the printer body side by interrupt processing. (S1208). Unlike the first embodiment, this acceleration / deceleration start command is started simultaneously with interrupt processing without using a timer. After the interrupt process, the printer main body 10 prohibits the interrupt of the used interrupt port (S1209). Thereafter, the CPU 211 receives the STS signal from the option device 100, but for the reason described below, the notification of whether the option device 100 has received the CMD signal normally ends in S1204 and is not an STS related to control. Therefore, it is omitted. Steps after S1210 are the same as those after step 810 in the first embodiment. If the STS signal does not change from High to Low in S1204, the CPU 211 waits for a change in the STS signal for a predetermined time (referred to as an STS interrupt enable period) (S1205). If no change is observed, the CPU 211 prohibits interrupts at the interrupt port so that no interrupt is performed at the next STS reception. After receiving the STS signal from the option, the CPU 211 again waits for the next communication cycle. In the present embodiment, it can be seen that the CMD signal 1018 is properly transmitted to the option device 100 when the option device 100 changes the STS signal from High to Low. Therefore, the acceleration / deceleration control can be started without waiting for the reception of the STS signal 1022 from the option device 100, and the subsequent analysis of the STS signal is not necessary for the purpose of the acceleration / deceleration control in this embodiment.

  Next, FIG. 13 will be described. The control based on FIG. 13 is executed by the CPU 231 of the option device 100 based on a program stored in a ROM or the like. The CPU 231 receives the CMD signal 1018 including information on the target speed of acceleration / deceleration control transmitted from the printer body 10 (S1301), and then analyzes the CMD signal (S1302). Then, it is determined whether or not the content of the CMD signal is appropriate (S1303), and if it is appropriate, the CPU 231 sets the STS signal from High to Low (S1304). This operation serves as a starting point for starting acceleration / deceleration to the printer body 10 and also plays a role of notifying that the CMD signal has been normally received. Immediately after the STS signal is set, an instruction to start acceleration / deceleration on the option side is set (S1305). The subsequent steps are the same as those in the first embodiment. If the content of the CMD signal is not appropriate, the CPU 231 waits for the next communication cycle, receives the CMD signal again, and repeats the steps after S1301.

  As described above, in this embodiment, the printer main body 10 receives the STS signal while confirming that the CMD signal 1018 has been properly transmitted to the option device 100, starting from the change 1021 of the STS signal. It is possible to start acceleration / deceleration control. Further, it is not necessary to use a timer or the like, and the processing process can be simplified.

  In the first and second embodiments, the feeding option device 100 that feeds the recording material to the image forming apparatus is described as an example of the option device that can be attached to and detached from the image forming apparatus. However, it is not limited to this. The optional device may be a discharge optional device that receives a recording material from the image forming apparatus and performs post-processing (stack processing, stapling processing, etc.) on the received recording material. The present invention can be applied when the same recording material is conveyed by both the conveying means provided in the image forming apparatus and the conveying means provided in the discharge option device.

  In the first and second embodiments, the synchronous acceleration / deceleration control in the image forming apparatus and the optional apparatus has been described. However, it is not limited to this. For example, synchronous stop control, that is, conveyance control for temporarily stopping conveyance of the recording material when the same recording material is conveyed by both the conveyance means provided in the image forming apparatus and the conveyance means provided in the optional device. The present invention can also be applied. When performing the synchronous stop control, the timing at which the leading edge of the recording material reaches the registration sensor 35 is regarded as a trigger for starting the synchronous stop control, and the same control is applied.

  In the first and second embodiments, S403 and S404 in FIG. 4, that is, forward acceleration / deceleration control are mainly described. However, in S407 and S408 in FIG. 4, that is, the acceleration / deceleration speed is returned to the original state. The present invention can also be applied to acceleration / deceleration control. That is, the same control can be applied by using the speed return timer set timing (S405) as a trigger instead of the timing when the leading edge of the paper P reaches the registration sensor 35.

DESCRIPTION OF SYMBOLS 10 Laser beam printer 18 Registration roller 35 Registration sensor 100 Feeding option apparatus 103 Conveyance roller 202 Engine control part 230 Option control part

Claims (14)

An image forming means for forming an image on the recording material, a first conveying means for conveying the recording material, a detecting means for detecting the recording material, and a target speed is obtained based on the timing at which the recording material is detected by the detecting means. An image forming apparatus including a first control unit that changes a conveyance speed of the recording material by the first conveyance unit to the target speed;
An optional device that includes a second transport unit that transports the recording material, and a second control unit that changes a transport speed of the recording material by the second transport unit, and is detachable from the image forming apparatus;
A first serial signal line for transmitting a clock signal from the first control means to the second control means in a state where the optional device is attached to the image forming apparatus, and in synchronization with the clock signal. A second serial signal line for transmitting a command signal from the first control means to the second control means, a branch from the second serial signal line, and the second control signal from the first control means. An image forming system having a third serial signal line for transmitting an interrupt signal indicating that communication has started to the control means;
During a period in which the same recording material is transported by both the first transport device and the second transport device, the transport speed of the recording material by the first transport device and the second transport device is set to the target speed. In the case of changing, the first control unit transmits the interrupt signal to the second control unit via the third serial signal line, and then transmits the target signal via the second serial signal line. The command signal related to speed is transmitted, and the first control unit and the second control unit are respectively configured to reference the timing at which the interrupt signal is transmitted as a reference. An image forming system, wherein control for changing the conveying speed of the recording material by the means to the target speed is started.   The second control means sets the interrupt port to which the third serial signal line is connected to the interrupt enabled state, and changes the interrupt port setting to interrupt disabled at the timing when the interrupt signal is received. The image forming system according to claim 1. A fourth serial signal line for transmitting a status signal corresponding to the command signal from the second control means to the first control means in synchronization with the clock signal;
The image forming system according to claim 2, wherein the second control unit changes the setting of the interrupt port to interrupt permission at a timing when transmission of the status signal is completed.   4. The image forming system according to claim 1, wherein the interrupt signal is a signal obtained by changing a level of the command signal. Each of the first control means and the second control means has a timer,
Based on the timing at which the interrupt signal is transmitted, the first control unit starts the timer, and sets the conveyance speed of the recording material by the first conveyance unit at the timing when a predetermined time has elapsed. The second control means starts the timer on the basis of the timing at which the interrupt signal is transmitted as a reference, and the second transport means at the timing when the predetermined time has elapsed. 5. The image forming system according to claim 1, wherein control for changing a recording material conveyance speed by the recording medium to the target speed is started.   6. The image forming system according to claim 5, wherein the timing at which the predetermined time has passed is at least a timing after the transmission of the command signal is completed. An image forming means for forming an image on the recording material, a first conveying means for conveying the recording material, a detecting means for detecting the recording material, and a target speed is obtained based on the timing at which the recording material is detected by the detecting means. An image forming apparatus including a first control unit that changes a conveyance speed of the recording material by the first conveyance unit to the target speed;
An optional device that includes a second transport unit that transports the recording material, and a second control unit that changes a transport speed of the recording material by the second transport unit, and is detachable from the image forming apparatus;
A first serial signal line for transmitting a clock signal from the first control means to the second control means in a state where the optional device is attached to the image forming apparatus, and in synchronization with the clock signal. A second serial signal line for transmitting a command signal from the first control means to the second control means, and from the second control means to the first control means in synchronization with the clock signal. A third serial signal line for transmitting a status signal corresponding to the command signal, and a branch from the third serial signal line, and the command signal is received from the second control means to the first control means. An image forming system having a fourth serial signal line for transmitting an interrupt signal indicating
During a period in which the same recording material is transported by both the first transport device and the second transport device, the transport speed of the recording material by the first transport device and the second transport device is set to the target speed. In the case of changing, after the first control means transmits the command signal related to the target speed to the second control means via the second serial signal line, the second control means The interrupt signal is transmitted to the first control unit via the fourth serial signal line, and the first control unit and the second control unit use the timing at which the interrupt signal is transmitted as a reference. Then, control for changing the recording material conveyance speed by the first conveyance unit and the second conveyance unit to the target speed is started.   The first control means disables the setting of the interrupt port connected to the fourth serial signal line, detects the recording material by the detection means, and then detects the recording material. The image forming system according to claim 7, wherein the setting of the interrupt port is changed to interrupt permission at a timing when communication is started.   3. The image forming system according to claim 2, wherein the first control unit changes the setting of the interrupt port to disable interrupt at a timing when the interrupt signal is received.   The image forming system according to claim 7, wherein the interrupt signal is a signal obtained by changing a level of the status signal.   At the timing when the interrupt signal is transmitted, the first control unit and the second control unit change the recording material conveyance speed by the first conveyance unit and the second conveyance unit to the target speed, respectively. The image forming system according to any one of claims 7 to 10, wherein the control to change is started.   The image forming system according to claim 1, wherein the first control unit and the second control unit communicate with each other at a constant control cycle. The image forming unit includes an image carrier and a transfer unit that transfers a toner image formed on the image carrier to a recording material,
The first control unit obtains the target speed so that the timing coincides with the toner image formed on the image carrier, and accelerates the recording material conveyance speed by the first conveyance unit toward the target speed. The image forming system according to claim 1, wherein the image forming system is decelerated.   The image forming system according to claim 1, wherein the optional device is a feeding option device that feeds a recording material to the image forming apparatus.

Images