JP2009297905A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which removes a terminal device from the need of resending printing data after resetting from an error. <P>SOLUTION: The printer 1 stops transmission of an ACK packet 42 to a received TCP packet 41 when the error occurs during receiving of printing data 30. A PC 2 transmits a keep alive packet 45 in place of the TCP packet 41 because the ACK packet 42 cannot be detected. The printer 1 transmits the ACK packet 42 to the PC 2 if the error is not solved even after a predetermined time passes from a time when the first keep alive packet 45 is received. The PC 2 receives the ACK packet 42, thereby transmitting a next TCP packet 41. The printer 1 repeats the above processing until the error is corrected, thereby limiting reception of the TCP packet 41. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that executes print processing based on print data transmitted from a terminal device via a network.

  Conventionally, a PC (Personal Computer) and a printer are connected via a LAN (Local Area Network), and print data is transmitted from the PC to the printer, thereby causing the printer to execute print processing.

  For transmission of print data, Port 9100, lpr (Line Printer) protocol, or the like is used. These protocols use TCP / IP (Transmission Control Protocol / Internet Protocol). That is, the print data is transmitted to the printer via a TCP connection established between the PC and the printer.

  In addition, the printer may not be able to continue the printing process due to an error such as out of paper or paper jam while receiving print data. In this case, the printer disconnects the TCP connection as error processing. The PC that is the transmission source of the print data determines that an error has occurred in the printer by detecting the disconnection of the TCP connection, and notifies the user of the occurrence of the error.

  The PC periodically retransmits the print data even after the TCP connection is disconnected. After returning from the error, the printer can restart the printing process using the retransmitted print data. Accordingly, the user can obtain output from the printer without performing a reprint operation.

JP 2001-92604 A

  However, when retransmitting print data, the PC transmits print data for all pages. The printer restarts the printing process from the beginning even though there are pages printed before the occurrence of the error. As a result, there has been a problem that multiple pages are printed in duplicate due to the occurrence of an error.

  Japanese Patent Application Laid-Open No. 2005-228561 discloses a technique for preventing the occurrence of redundantly printed pages after returning from an error. In Patent Document 1, when the printer recovers from an error that occurred during reception of print data, the printer clears the print data remaining in the memory and notifies the PC of the number of printed pages. The PC spools the print data in units of pages until the printing is completed, and retransmits the print data on and after the next page of the printed page based on the notification from the printer.

  In view of the above problems, an object of the present invention is to provide an image forming apparatus in which a terminal device does not need to retransmit print data after returning from an error.

  In order to solve the above-described problem, an invention according to claim 1 is an image forming apparatus connected to a terminal device via a network, and is transmitted from the terminal device using a communication connection based on a first protocol. A communication unit that receives the print data, and a print unit that executes a printing process using the received print data, and the communication unit has an error in the print unit during reception of the print data. A reception limiting unit that stops reception of the print data while maintaining the communication connection, and resumes reception of the print data using the communication connection when the error is resolved. To do.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the reception restriction unit is configured to print the print data when the print data reception stop time has elapsed during a continuation of the error. Data is temporarily received.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, a message requesting notification of an operating state of the printing unit is further transmitted from the terminal device based on a second protocol. A notification unit that notifies the terminal device of the operation state of the printing unit based on the second protocol, the reception restriction unit receives the message during reception of the print data, In addition, when the error occurs after receiving the message, the reception of the print data is stopped.

  According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the printing unit analyzes the received print data, and the operation state of the printing unit has changed. An analysis unit that confirms whether the received print data includes a command that requests notification of the operation state after the change, and the reception restriction unit includes the received print data When the command is detected and an error occurs in the printing unit after the command is detected, reception of the print data is stopped.

  The image forming apparatus according to the present invention stops the reception of the print data while maintaining the communication connection when an error occurs in the printing unit during the reception of the print data, and maintains the communication connection when the error is resolved Is used to resume receiving print data. As a result, the image forming apparatus according to the present invention can continue to receive the print data without establishing a new communication connection after the error is resolved, and can continue the printing process without using the retransmitted print data. be able to.

  Also, if a message requesting notification of the operating status of the printing unit has been received before the error occurred, or a command requesting notification of a change in operating status has been detected from the received print data In addition, the image forming apparatus according to the present invention stops receiving print data. As a result, the image forming apparatus according to the present invention can notify the terminal device of the operation state of the printing unit even when the reception of the print data is stopped.

{First embodiment}
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a network system according to the present embodiment. The network system shown in FIG. 1 has a configuration in which a printer 1 and a PC 2 are connected to a LAN 3.

  The printer 1 is a network printer that prints the print data 30 transmitted from the PC 2. The PC 2 is a terminal device used by the user. The LAN 3 is provided with a router (not shown) for connecting to the Internet or another LAN.

  First, the configuration of the printer 1 will be described. The printer 1 includes a control unit 11, a printer controller 12, a printer main body unit 13, and a communication unit 14.

  The control unit 11 includes a reception restriction unit 111, a transmission source information storage unit 112, a printer information management unit 113, and an ACK transmission timer 114. The control unit 11 performs overall control of the printer 1 and has a function of an SNMP (Simple Network Management Protocol) agent.

  The reception restriction unit 111 performs reception restriction processing for temporarily stopping reception of the print data 30 when an error occurs in the printer 1 during reception of the print data 30. The transmission source information storage unit 112 stores the transmission source IP address of the print data 30 and the transmission source IP address of the SNMP request 43. The printer information management unit 113 monitors the operation status of the printer controller 12 and the printer main body unit 13 and stores the status information of the printer 1. The ACK transmission timer 114 is a timer that designates the transmission timing of the ACK packet 42 during the reception restriction process.

  The printer controller 12 includes a command analysis unit 121 and a memory 122. The command analysis unit 121 analyzes a print command described in the print data 30. The memory 122 is a storage unit that stores the print data 30 transmitted from the PC 2. Raster data is generated from the print data 30 based on the print command analyzed by the command analysis unit 121.

  The printer main body 13 includes a developing device, a transfer device, and the like, and prints raster data generated by the printer controller 12 on printing paper.

  The communication unit 14 transmits / receives data to / from each computer connected via the LAN 3 using TCP / IP or the like.

  Next, the configuration of the PC 2 will be described. The PC 2 includes a printer driver 21 and a port monitor 22.

  The printer driver 21 generates print data 30 described in a page description language from document data or the like that the user has instructed to print. The port monitor 22 transmits the print data 30 to the printer 1 and functions as an SNMP manager. Note that the print data 30 is transmitted using Port 9100, lpr protocol, or the like.

  In the network system configured as described above, the printer 1 temporarily stops receiving the print data 30 when an error such as out of paper or paper jam occurs during reception of the print data 30. For this reason, it is possible to prevent an overflow of the memory 122 or the like that occurs in order to continue receiving the print data 30 during an error. Accordingly, the printer 1 can prevent the received print data 30 from being lost, so that the PC 2 can print all pages without retransmitting the print data 30.

  Hereinafter, a data flow between the printer 1 and the PC 2 when the printer 1 receives the print data 30 will be described. FIG. 2 is a diagram illustrating a data flow between the printer 1 and the PC 2.

  First, the user instructs printing of document data created using an application program installed in the PC 2. The printer driver 21 generates print data described in a page description language from document data, and spools the print data in a spooler (not shown).

  The port monitor 22 establishes a TCP connection with the printer 1 (step S11), and transmits a TCP packet 41 using the TCP connection (step S12). Specifically, the port monitor 22 transmits a TCP packet 41 in which the divided print data 30 is stored to the printer 1. The printer 1 transmits an ACK packet 42 to the PC 2 as a reception response of the TCP packet 41. By repeating the process shown in step S12, the print data 30 is transmitted from the PC 2 to the printer 1. When the transmission of the print data 30 is completed, the TCP connection is disconnected (step S14).

  In the printer 1, the print data 30 is extracted from the TCP packet 41 and stored in the memory 122. Raster data for each page is generated from the print data 30 stored in the memory 122. The printer main body 13 prints raster data on printing paper.

  Further, the port monitor 22 acquires status information of the printer 1 using SNMP in parallel with the transmission of the TCP packet 41 (step S12) (step S13). Specifically, the port monitor 22 periodically transmits an SNMP request 43 to the printer 1. As a response to the SNMP request 43, the printer 1 transmits an SNMP response 44 including the status information of the printer 1 to the PC 2. Accordingly, the port monitor 22 can display the status of the printer 1 (standby, printing, error occurrence, etc.) on the monitor of the PC 2 or the like.

  Normally, the print data 30 is transmitted to the printer 1 as described above. However, when an error occurs in the printer 1 while the print data 30 is being received, the data shown in FIG. 3 is exchanged between the printer 1 and the PC 2.

  FIG. 3 is a diagram showing a data flow between the printer 1 and the PC 2 when an error occurs in the printer 1. In FIG. 3, the display of establishment (step S11) and disconnection (step S14) of the TCP connection is omitted.

  It is assumed that an error has occurred in the printer 1 during reception of the TCP packet 41 (step S12). However, the port monitor 22 transmits the TCP packet 41 to the printer 1 regardless of the error of the printer 1 (step S21). The printer 1 stops transmitting the ACK packet 42 when an error occurs.

  The port monitor 22 cannot detect the ACK packet 42 corresponding to the transmitted TCP packet 41. For this reason, the port monitor 22 performs so-called keep alive in order to maintain the TCP connection. That is, the port monitor 22 transmits keep-alive packets 45 to the printer 1 at preset intervals (step S22). The printer 1 does not respond to the keep alive packet 45. As described above, when an error occurs, the printer 1 temporarily stops receiving the print data 30 by not responding to the packet received via the TCP connection.

  However, the PC 2 can acquire the status information of the printer 1 using SNMP (step S13). This is because SNMP presupposes the use of UDP (User Datagram Protocol). Note that the occurrence of an error in the printer 1 is notified to the PC 2 by the process of step S13 executed first after the error has occurred. As a result, the port monitor 22 displays a message indicating that an error has occurred in the printer 1 on the monitor of the PC 2.

  The printer 1 transmits an ACK packet 42 to the PC 2 when a predetermined time has elapsed since the first receipt of the keep-alive packet 45 (step S23). The PC 2 that has received the ACK packet 42 transmits a new TCP packet 41 (step S21). The printer 1 does not transmit the ACK packet 42 for the received TCP packet 41 because the error state continues. As a result, the port monitor 22 resumes transmission of the keep alive packet 45 (step S22). In this way, the processes of steps S21 to S23 are repeated until the error of the printer 1 is canceled. That is, the printer 1 temporarily stops receiving the TCP packet 41 while the error continues. However, in order to maintain the TCP connection, the TCP packet 41 and the ACK packet 42 are transmitted and received between the printer 1 and the PC 2 at a predetermined time interval.

  When the error of the printer 1 is resolved, the printer 1 transmits an ACK packet 42 to the PC 2. Thereby, the reception process (step S12) of the TCP packet 41 is resumed.

  Hereinafter, the operation of the printer 1 during the reception process of the print data 30 will be described. FIG. 4 is a flowchart showing an operation flow of the printer 1 when receiving the print data 30. In the flowchart shown in FIG. 4, it is assumed that a TCP connection has already been established between the printer 1 and the PC 2.

  Note that the processes in steps S101 and S102 and the processes in steps S109 and S110 shown in FIG. 4 correspond to step S12 shown in FIGS. The processing in steps S103 to S105 corresponds to step S13 shown in FIGS. The process of step S108 corresponds to steps S21 to S23 shown in FIG.

  When the printer 1 receives the first TCP packet 41 (Yes in step S101), the printer 1 transmits an ACK packet 42 to the PC 2 and acquires the IP address of the transmission source of the TCP packet 41 (step S102). The acquired IP address is stored in the transmission source information storage unit 112.

  Next, the printer 1 receives the SNMP request 43 (Yes in step S103), acquires the IP address of the transmission source of the SNMP request 43 (step S104), and transmits the SNMP response 44 (step S105). The source IP address of the SNMP request 43 is stored in the source information storage unit 112.

  If no error has occurred in the printer 1 (No in step S106), the printer 1 receives the TCP packet 41 (Yes in step S109), and transmits the ACK packet 42 to the PC 2 (step S110). When the reception of the TCP packet 41 is completed (Yes in step S111), the printer 1 ends the process shown in FIG. On the other hand, if the reception of the TCP packet 41 is not completed (No in step S111), the printer 1 returns to the process shown in step S103 in order to receive the TCP packet 41 and the SNMP request 43.

  If an error occurs in the printer 1 (Yes in step S106), the control unit 11 determines whether the transmission source of the TCP packet 41 stored in the transmission source information storage unit 112 matches the transmission source of the SNMP request 43. Confirm. (Step S107). If the source IP addresses match (Yes in step S107), the reception restriction unit 111 executes a reception restriction process (step S108). Then, the printer 1 executes the processes shown in steps S109 to S111.

  On the other hand, if the source IP addresses do not match (No in step S107), the printer 1 receives the TCP packet 41 (Yes in step S109), and transmits the ACK packet 42 to the PC 2 (step S110). That is, if the printer 1 has not received the SNMP request 43, the printer 1 continues to receive the print data 30 regardless of the error.

  Next, the operation of the printer 1 in the reception restriction process (step S108) will be described. FIG. 5 is a flowchart showing an operation flow of the reception restriction unit 111 in the reception restriction process.

  First, the reception restriction unit 111 instructs the communication unit 14 to stop transmission of the ACK packet 42 (step S121). When the first keep-alive packet 45 is received (Yes in step S122), the reception restriction unit 111 turns on the ACK transmission timer 114 (step S123). The ACK transmission timer 114 generates a timer event at the predetermined time interval described above. The predetermined time is a time that does not exceed the time from when the PC 2 starts transmitting the keep-alive packet 45 to when the TCP connection is disconnected, and is set in the ACK transmission timer 114 in advance.

  When the error of the printer 1 is resolved (Yes in step S124), the reception restriction unit 111 instructs the communication unit 14 to transmit the ACK packet 42 (step S126). Then, the reception restriction unit 111 turns off the ACK transmission timer 114 (step S127), and ends the reception restriction process shown in FIG.

  On the other hand, if the error of the printer 1 has not been resolved (No in step S124), the reception restriction unit 111 checks whether a timer event has occurred in the ACK transmission timer 114 (step S125). If a timer event has occurred (Yes in step S125), reception restriction unit 111 instructs transmission of ACK packet 42 (step S126). That is, the printer 1 maintains the TCP connection by transmitting the ACK packet 42 before the TCP connection is disconnected due to a keep-alive timeout. The reception restriction unit 111 turns off the ACK transmission timer 114 (step S127), and ends the reception restriction process shown in FIG.

  As described above, the printer 1 according to the present embodiment temporarily receives the print data 30 while maintaining the TCP connection by controlling the transmission timing of the ACK packet 42 while the error continues. Stop. Since the printer 1 continues to receive the print data 30 using the maintained TCP connection after the error is resolved, the PC 1 omits the retransmission processing of the print data 30 due to the error of the printer 1. Can do.

  In addition, the printer 1 temporarily stops receiving the print data 30 during the occurrence of an error, thereby preventing the print data 30 accumulated in the memory 122 from being lost. Therefore, the printer 1 can complete the print processing of the print data 30 without using the print data 30 retransmitted from the PC 2.

  The printer 1 stops receiving the print data 30 for a certain period when the SNMP request 43 is transmitted from the PC 2 and an error occurs. As a result, the printer 1 can reliably notify the PC 2 of the occurrence of an error even if the reception of the print data 30 has not been completed.

{Second Embodiment}
Hereinafter, a second embodiment of the present invention will be described. The printer 1 according to the first embodiment provides status information in response to the SNMP request 43. On the other hand, the printer according to the present embodiment provides status information based on a PJL (Printer Job Language) command described in the print data 30.

  Note that the configuration of the printer according to the present embodiment is the same as the configuration of the printer 1 shown in FIG. Below, it demonstrates centering on a different point from the said 1st Embodiment.

  First, a data flow when the printer 1 according to the present embodiment receives the print data 30 will be described. FIG. 6 is a diagram showing a data flow between the printer 1 and the PC 2 according to the present embodiment.

  After the TCP connection is established (step S31), the printer 1 performs a reception process for the TCP packet 41 (step S32). The command analysis unit 121 analyzes the print data 30 stored in the first received TCP packet (step S33), and checks whether there is a PJL command 46 that requests notification of the status of the printer 1.

  FIG. 7 is a diagram illustrating an example of the PJL command 46. The character string “.%-12345” shown in FIG. 7 is an escape sequence for inserting a PJL command between print commands described in the print data 30. When the PJL command 46 is detected from the first received TCP packet 41, the printer controller 12 transmits a PJL command 47 for notifying the status of the printer 1 to the PC 2 using the TCP connection (step S34). For example, when the printer 1 is on standby, the PJL command 47 shown in FIG. 8 is transmitted, and when the printer 1 is printing, the PJL command 47 shown in FIG. 9 is transmitted.

  After these processes, the print data 30 is transmitted to the printer 1 by repeating the process shown in step S32. Each time the status of the printer 1 changes, a PJL command 47 is transmitted to the PC 2 (step S34). When reception of the print data 30 is completed, the TCP connection is disconnected (step S35).

  Further, in the present embodiment, when an error occurs in the printer 1, data exchange shown in FIG. 3 is performed between the printer 1 and the PC 2. However, the process of step S13 shown in FIG. 3 is not performed, and the printer controller 12 transmits a PJL command 47 to the PC 2 every time the status of the printer 1 changes.

  Next, the reception process of the print data 30 in the printer 1 according to this embodiment will be described. FIG. 10 is a flowchart showing an operation flow of the printer 1 according to the present embodiment when the print data 30 is received. In the flowchart shown in FIG. 10, it is assumed that a TCP connection has already been established between the printer 1 and the PC 2.

  Note that the processing in steps S201 to S202 shown in FIG. 10 corresponds to the processing in steps S32 to S33 shown in FIG. The processing in steps S206 to S207 shown in FIG. 10 corresponds to the processing in step S34 shown in FIG. The processing in steps S210 to S211 illustrated in FIG. 10 corresponds to the processing in step S32 illustrated in FIG.

  When the printer 1 receives the first TCP packet 41 (Yes in step S201), the printer 1 transmits an ACK packet 42 and analyzes the print data 30 included in the first TCP packet 41 (step S202). If the PJL command 46 is described in the analyzed print data 30 (Yes in step S203), the printer 1 turns on the notification flag and transmits the PJL command 47 to the PC 2 (step S204). The notification flag is information indicating whether or not to send the PJL command 47 when the status of the printer 1 changes, and is set to OFF in the initial state.

  When the notification flag is OFF (No in Step S205), the printer 1 receives the TCP packet 41 (Yes in Step S210), and transmits the ACK packet 42 to the PC 2 (Step S211). That is, when the PJL command 46 is not described in the TCP packet 41 received first, the printer 1 transmits the ACK packet 42 to the PC 2 regardless of the error. When the reception of the TCP packet 41 is completed (Yes in step S212), the printer 1 ends the process shown in FIG. On the other hand, if the reception of the TCP packet 41 is not completed (No in step S212), the printer 1 returns to the process shown in step S206 in order to receive the next TCP packet 41.

  On the other hand, if the notification flag is ON (Yes in step S205), the printer 1 checks whether the status has changed (step S206). If the status of the printer 1 has changed (Yes in step S206), the printer controller 12 transmits a PJL command 47 to the PC 2 (step S207).

  Next, the printer 1 checks whether an error has occurred (step S208). If no error has occurred (No in step S208), the printer 1 executes the processes shown in steps S210 and S211.

  On the other hand, if an error has occurred (Yes in step S208), the reception restriction unit 111 executes a reception restriction process (step S209). The reception restriction process in step S209 is the same as the process shown in FIG. That is, the printer 1 according to the present embodiment maintains the TCP connection by transmitting the ACK packet 42 before the TCP connection is disconnected due to a keep-alive timeout. The printer 1 executes the processes shown in steps S210 and S211 and continues the process of receiving the TCP packet 41.

  The printer 1 executes the process shown in step S212 after executing the process according to whether or not an error has occurred. That is, when the reception of the TCP packet 41 is completed (Yes in step S212), the printer 1 ends the process shown in FIG. On the other hand, if the reception of the TCP packet 41 is not completed (No in step S212), the printer 1 returns to the process shown in step S206 in order to receive the next TCP packet 41.

  As described above, similarly to the first embodiment, the printer 1 according to the present embodiment temporarily receives the print data 30 while maintaining the TCP connection until the error is resolved. Stop. Since the printer 1 according to the present embodiment continues to receive the print data 30 using the TCP connection that has been maintained after the error is resolved, the PC 1 does not receive the print data 30 associated with the printer 1 error. The retransmission process can be omitted.

  In addition, the printer 1 according to the present embodiment prevents the loss of the print data 30 accumulated in the memory 122 by temporarily stopping the reception of the print data 30 during the occurrence of an error. Therefore, the printer 1 according to the present embodiment can complete the printing process of the print data 30 without using the print data 30 retransmitted from the PC 2.

  Also, the printer 1 according to the present embodiment detects the PJL command 46 from the first received TCP packet 41, and stops receiving the TCP packet 41 for a certain period when an error occurs. As a result, the printer 1 according to the present embodiment can notify the PC 2 of the status without using SNMP.

  The printer 1 according to the present embodiment has been described with respect to the example in which the first received TCP packet is analyzed to confirm the presence or absence of the PJL command 46, but is not limited thereto. For example, the printer 1 may confirm the presence / absence of the PJL command 46 in all received TCP packets. In this case, if the PJL command 46 is detected before an error occurs, the printer 1 can execute the reception restriction process.

1 is a configuration diagram of a network system according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a data flow between a PC and the printer according to the first embodiment. It is a figure which shows the flow of the data between a printer and PC at the time of reception restriction of a TCP packet. 4 is a flowchart showing a flow of operations of the printer according to the first embodiment. It is a flowchart which shows the flow of a reception restriction process. It is a figure which shows the flow of the data between PC and the printer which concerns on 2nd Embodiment. It is a figure which shows the PJL command which requests | requires notification of the status of a printer. It is a figure which shows the PJL command which notifies the change of the status of a printer. It is a figure which shows the PJL command which notifies the change of the status of a printer. 6 is a flowchart illustrating an operation flow of a printer according to a second embodiment.

Explanation of symbols

1 Printer 2 PC (Personal Computer)
DESCRIPTION OF SYMBOLS 11 Control part 12 Printer controller 13 Printer main body part 14 Communication part 21 Printer driver 22 Port monitor 111 Reception restriction part 112 Transmission source information storage part 113 Printer information management part 114 ACK transmission timer

Claims (4)

An image forming apparatus connected to a terminal device via a network,
A communication unit that receives print data transmitted from the terminal device using a communication connection based on a first protocol;
A printing unit that executes a printing process using the received print data;
With
The communication unit is
If an error occurs in the printing unit during reception of the print data, the print data reception is stopped while maintaining the communication connection, and the print connection is used by using the communication connection when the error is resolved. Receiving restriction unit that resumes receiving,
An image forming apparatus comprising: The image forming apparatus according to claim 1.
The image forming apparatus according to claim 1, wherein the reception restricting unit temporarily receives the print data when a stop time of reception of the print data elapses during a continuation of the error. The image forming apparatus according to claim 1, further comprising:
When a message requesting notification of the operating state of the printing unit is transmitted from the terminal device based on the second protocol, the operating state of the printing unit is notified to the terminal device based on the second protocol. Notification section,
With
The image forming apparatus, wherein the reception restriction unit receives the message while the print data is being received, and stops receiving the print data when the error occurs after the message is received. The image forming apparatus according to any one of claims 1 to 3,
The printing unit
Analyzing the received print data, and confirming whether or not the received print data includes a command for requesting notification of the changed operation state when the operation state of the printing unit changes Analysis department,
Including
The reception restriction unit stops receiving the print data when the command is detected from the received print data and an error occurs in the printing unit after the command is detected. Image forming apparatus.

Images