Image forming apparatus and image forming system

Abstract

To provide an image forming apparatus capable of processing a status information reply request command even when print data are resident.SOLUTION: When the printer 2 and PC3 are connected by a USB connection, if the printer 2 receives a status information return request command from PC3 via the control transfer pipe and end point (EP1, for example) while the printer 2 is receiving print information via the print-data communication pipe and end point (EP0, for example), the printer 2 returns its own status information to PC3, which is the request source of the return request command, via the control transfer end point (S17).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and an image forming system equipped with a USB interface. [Background technology]

[0002] Image forming apparatuses for printing images on sheets, which are print targets, have been known for some time. By connecting such image forming apparatuses to an external terminal, such as a host PC, it is possible to perform printing in response to instructions from the external terminal and to check the current status of the image forming apparatus from the external terminal. One method for connecting an image forming apparatus to an external terminal is via a USB (Universal Serial Bus) connection environment.

[0003] Although USB is physically a serial communication system, it has logical channels (communication endpoints) called endpoints, and by providing multiple endpoints, it is possible to form multiple communication paths (pipes) in software within a single cable. In an image forming device connected to an external terminal via USB, as disclosed in Japanese Patent Application Laid-Open No. 2014-106581, for example, when a predetermined operation for executing printing is performed on the external terminal, print data for executing print processing on the image forming device is sent via the pipe from the external terminal on the host side to the image forming device on the device side. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-106581 A (paragraphs 0025-0029, Figure 2) Summary of the Invention [Problem to be solved by the invention]

[0005] On the other hand, in addition to the print data, commands are also sent from the host-side external terminal to the device-side image forming device. However, when print data and commands are sent using the same pipe, if the preceding print data is unable to be processed on the pipe or in the image forming device for some reason and is stuck, the image forming device may not be able to process the command even if it is sent. For example, this type of print data backlog can occur when printing cannot be performed due to a paper jam or a depletion of consumables, or when sending large amounts of print data that take a long time to send.

[0006] The present invention has been made to solve the above-mentioned problems in the conventional art, and aims to provide an image forming device and an image forming system that can process commands even in a situation where print data is backed up as described above. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, a first image forming apparatus according to the present application is an image forming apparatus equipped with a USB interface and a controller, wherein the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for receiving data transmitted from a terminal device connected via a USB connection, and when the controller receives a return request command for status information of the image forming apparatus via the endpoint for control transfer while receiving print data via the endpoint for print data communication, it returns its own status information via the endpoint for control transfer to the terminal device that requested the return request command.

[0008] A second image forming apparatus according to the present application is an image forming apparatus comprising a USB interface, a receive buffer, and a controller, wherein the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for receiving data transmitted from a terminal device connected via a USB connection, and the controller is characterized in that after receiving print data via the endpoint for print data communication, when the controller receives a return request command for status information of the image forming apparatus via the endpoint for control transfer while the received print data is being stored in the receive buffer, the controller returns its own status information via the endpoint for control transfer to the terminal device that requested the return request command.

[0009] Furthermore, a third image forming apparatus according to the present application is an image forming apparatus equipped with a USB interface and a controller, wherein the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for receiving data transmitted from a terminal device connected via a USB connection, and the controller is characterized in that, after receiving print data via the endpoint for print data communication, when the controller receives a command for requesting a return of status information of the image forming apparatus via the endpoint for control transfer while a reason for interruption has occurred in the printing process based on the received print data, the controller returns its own status information via the endpoint for control transfer to the terminal device that has requested the return request command.

[0010] Furthermore, a fourth image forming apparatus according to the present application is an image forming apparatus equipped with a USB interface and a controller, wherein the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for receiving data transmitted from a terminal device connected via a USB connection, and when the controller receives a cancel command instructing to cancel printing via the endpoint for control transfer while receiving print data via the endpoint for print data communication, the controller terminates reception of the print data and controls so as not to perform printing processing based on the received print data.

[0011] A fifth image forming apparatus according to the present application is an image forming apparatus including a USB interface and a controller, wherein the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for receiving data transmitted from a terminal device connected via a USB connection, and the controller controls the printing process based on the received print data so as to stop when, after receiving print data via the endpoint for print data communication and while printing processing based on the received print data is being performed, a cancel command instructing to cancel printing is received via the endpoint for control transfer.

[0012] Further, a first image forming system according to the present application is an image forming system having the first image forming apparatus and a terminal device connected to the first image forming apparatus via a USB interface, wherein the terminal device is capable of sending print data to the image forming apparatus via the endpoint for print data communication, and is capable of sending a return request command for status information of the image forming apparatus via the endpoint for control transfer while sending print data via the endpoint for print data communication.

[0013] In addition, a second image forming system according to the present application is an image forming system having the second image forming device and a terminal device connected to the second image forming device via a USB interface, wherein the terminal device is capable of sending print data to the image forming device via the endpoint for print data communication and is capable of sending a return request command for status information of the image forming device via the endpoint for control transfer.

[0014] Furthermore, a third image forming system according to the present application is an image forming system having the third image forming device and a terminal device connected to the third image forming device via a USB interface, wherein the terminal device is capable of sending print data to the image forming device via the endpoint for print data communication and is capable of sending a return request command for status information of the image forming device via the endpoint for control transfer. [Effects of the Invention]

[0015] The image forming apparatus and image forming system according to the present application having the above configuration transmit and receive commands between the image forming apparatus and an external terminal connected via USB via a pipe connecting a control transfer endpoint that is different from the endpoint for receiving print data. Therefore, even if print data being sent from the host-side external terminal to the device-side image forming apparatus is backed up in the pipe due to, for example, sending large print data that takes a long time to send, or an interruption in the printing process such as a paper jam or depletion of consumables, the image forming apparatus can process various commands via the control transfer endpoint. Furthermore, commands can be sent and received via the existing control transfer endpoint without providing a new endpoint dedicated to sending commands, and further, the pipe connecting the control transfer endpoints allows bidirectional communication, so the USB interface configuration does not become complicated. In particular, when a status information return request command is sent and received as a command, the external terminal can obtain status information from the image forming apparatus at any time. On the other hand, when a cancel command is sent and received as a command, cancellation can be executed from the external terminal at any time. In other words, it is possible to provide the terminal with the same functionality as when a print cancellation command is issued from the image forming apparatus itself. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a diagram showing a schematic configuration of an image forming system according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram illustrating an internal configuration of a printer. [Figure 3] FIG. 1 is a diagram showing endpoints provided in a USB interface and pipes connecting the endpoints. [Figure 4] 10 is a flowchart of a first main process according to the present embodiment. [Figure 5] 10 is a flowchart of a second main process according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of an image forming apparatus and an image forming system according to the present invention will be described below with reference to the drawings. Fig. 1 shows a schematic configuration of an image forming system 1 according to the present embodiment, and Fig. 2 is a simplified diagram showing the internal configuration of a printer 2, which is an image forming apparatus included in the image forming system 1 according to the present embodiment.

[0018] [Overall configuration of image formation system] As shown in FIG. 1, the image forming system 1 according to this embodiment basically includes a printer 2 and a PC (Personal Computer) 3, which is an external terminal connected to the printer 2 via a USB (Universal Serial Bus) connection. As an example, the image forming system 1 can be used as a self-service teller terminal (video teller machine) used in financial institutions and the like. In that case, the PC 3 corresponds to the terminal PC operated by the user at the teller, and the printer 2 and the PC 3 may be housed in the same housing. However, the use is not limited to this, and the external terminal may also be a mobile information terminal such as a smartphone or tablet in addition to the PC 3.

[0019] Regarding the relationship between the printer 2 and PC 3, the printer 2 is on the device side and the PC 3 is on the host side. The printer 2 and PC 3 are equipped with various communication interfaces in addition to a USB interface, and can be connected by various communication methods other than a USB connection, such as a wired LAN, wireless LAN, or Bluetooth, but the following explanation assumes they are connected by a USB connection.

[0020] Here, printer 2 is an example of an image forming device that forms an image on sheet S, such as recording paper or an overhead projector sheet. Printer 2 is a monochrome laser printer that forms a single-color developer image on sheet S, but is not limited to this. For example, printer 2 may be a color laser printer that forms developer images of multiple colors on sheet S. Alternatively, an inkjet printer may be used instead of a laser printer as long as it is capable of printing on sheet S. Sheet S is an example of a recording medium. For convenience of explanation, the up-down direction and the front-rear direction of printer 2 are defined below as shown by the arrows in FIG. 2.

[0021] 1 and 2, the printer 2 includes a main body housing 11, a sheet conveying unit 12, an image forming unit 13, a fixing unit 14, an operation panel unit 15, a display unit 16, a controller 17, a memory 18, and a USB interface 19. The main body housing 11 houses the above-mentioned units. Each unit included in the printer 2 will be described below in order.

[0022] The main body housing 11 is a housing portion that forms the exterior of the printer 2, and its outer wall includes an operation panel unit 15, a display unit 16, and a connector portion 19A of the USB interface 19 for inserting a USB connection cable. The main body housing 11 also includes a front cover 21, a discharge tray 22, and a supply tray 31. The front cover 21 is attached to the front of the main body housing 11 in an openable and closable manner. The discharge tray 22 is provided at the top of the main body housing 11, and sheets P with images formed thereon are placed on the discharge tray 22. The supply tray 31 is detachably attached to the bottom of the main body housing 11. Sheets S are placed on the supply tray 31. The sheets S are standard-sized sheets such as A4 size. The sheets S are paper media such as plain paper or cardboard, but are not limited to these, and may also be transparencies. The printer also includes a sensor SE1 that detects whether the front cover 21 is open or closed, and a sensor SE2 that detects whether the supply tray 31 is open or closed. Furthermore, the supply tray 31 is also provided with a sensor SE3 for detecting the approximate amount of remaining paper.

[0023] The sheet conveying unit 12 is a mechanism for conveying the sheet S within the printer 2. The path for conveying the sheet S in the sheet conveying unit 12 is roughly divided into a conveying path 201 and a re-conveying path 202. The conveying path 201 is a path for conveying the sheet S placed on the supply tray 31 toward the discharge tray 22 via the image forming unit 13. On the other hand, the re-conveying path 202 is a path for conveying the sheet S, with an image formed on one side, in the opposite direction to the conveying direction and conveying it again toward the image forming unit 13 (i.e., for double-sided printing). The re-conveying path 202 branches off from the conveying path 201 at a junction C and merges with the conveying path 201 near the pre-registration sensor SE4.

[0024] The sheet conveying section 12 also includes a pickup roller 33, a separation roller 34, a registration roller 35, a conveying roller 36, a discharge roller 37, re-conveying rollers 38 and 39, and a main motor 40 (see FIG. 1) that serves as a drive source for these rollers.

[0025] The pickup roller 33 picks up the sheets S in the supply tray 31 that have been pushed upward by the sheet pressing plate 32, and transports them toward the transport path 201. The separation roller 34 separates the sheets P picked up by the pickup roller 33 one by one.

[0026] The registration rollers 35 are disposed upstream of the image forming unit 13 on the conveying path 201. The registration rollers 35 align the direction of the leading edge of the sheet S, and then convey the sheet S toward the image forming unit 13. The conveying rollers 36 convey the sheet S to the discharge rollers 37 after it has passed through the fixing unit 14.

[0027] The discharge rollers 37 are disposed downstream of the junction C on the conveying path 201. The discharge rollers 37 are a pair of rollers consisting of a drive roller and a driven roller. The discharge rollers 37 rotate in the forward direction to discharge the sheet S onto the discharge tray 22. The forward rotation is a rotation that conveys the sheet S in the conveying direction, and corresponds to a counterclockwise rotation around the left-right direction of the main body housing 11 as an axis.

[0028] Furthermore, the discharge rollers 37 rotate in a reverse direction, which is the opposite direction to the forward rotation, to transport the sheet S to the re-transport path 202. The reversal is a rotation that transports the sheet S in the opposite direction to the transport direction, and corresponds to a clockwise rotation around the left-right direction of the main body housing 11 as an axis.

[0029] Re-conveying rollers 38 and 39 are arranged on the re-conveying path 202. The re-conveying rollers 38 and 39 convey the sheet S conveyed to the re-conveying path 202 toward the image forming unit 13. The re-conveying rollers 38 and 39 re-convey the sheet S, on one side of which an image has been formed, toward the image forming unit 13 via the re-conveying path 202, thereby making it possible to form images on both sides of the sheet S.

[0030] The sheet conveying unit 12 is also provided with various sensors for detecting the passage of the sheet S. For example, the pre-registration sensor SE4 is disposed upstream of the registration rollers 35 on the conveying path 201 and is a sensor that detects the passage of the sheet S. The post-registration sensor SE5 is disposed upstream of the fuser 14 on the conveying path 201, specifically, between the registration rollers 35 and the transfer roller 53 and is a sensor that detects the passage of the sheet S. The discharge sensor SE6 is disposed between the fuser 14 and the conveying rollers 36 on the conveying path 201 and detects the passage of the sheet S. The printer 2 is capable of detecting a paper jam or running out of paper in the conveying path based on the detection results of these sensors.

[0031] The image forming unit 13 forms an image on the sheet S sent out by the sheet transport unit 12. The image forming unit 13 has a drum cartridge 41 and a laser unit 42. The drum cartridge 41 further has a photosensitive drum 51, a charging roller 52, a transfer roller 53, a pinch roller 54, a developing roller 55, a supply roller 56, and a toner storage unit (toner cartridge) 57. The drum cartridge 41 can be removed from the main body of the apparatus by opening the front cover 21. The pinch roller 54 of the drum cartridge 41 faces the registration roller 35. The pinch roller 54 rotates following the rotation of the registration roller 35, and transports the sheet S together with the registration roller 35.

[0032] The photosensitive drum 51 rotates clockwise by the driving force transmitted from the main motor 40, thereby transporting the sheet S in the transport direction. In the photosensitive drum 51, the forward rotation, which is the rotation that transports the sheet S in the transport direction, is clockwise. Toner is stored in the toner storage section 57. The supply roller 56 supplies the toner in the toner storage section 57 to the developing roller 55. The charging roller 52 uniformly charges the surface of the photosensitive drum 51.

[0033] A transfer roller 53 is disposed at a position facing the photosensitive drum 51. The transfer roller 53 forms a transfer nip TN between itself and the photosensitive drum 51 on the transport path 201. Note that a transfer belt may be used instead of the transfer roller 53.

[0034] The main body housing 11 has a laser unit 42 at its interior upper portion. The laser unit 42 has a polygon mirror, a laser emitting unit, a lens, a reflecting mirror, etc. (not shown). The laser unit 42 exposes the surface of the photosensitive drum 51 by scanning the surface of the photosensitive drum 51 at high speed with laser light based on image data emitted from the laser emitting unit.

[0035] An electrostatic latent image based on image data is formed on the surface of the photosensitive drum 51 by being exposed to light by the laser unit 42. The developing roller 55 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 51, thereby forming a toner image on the surface of the photosensitive drum 51.

[0036] A transfer voltage is applied to the transfer roller 53 by a voltage application unit (not shown). The transfer roller 53 transports the sheet S between itself and the photosensitive drum 51, thereby transferring the toner image formed on the surface of the photosensitive drum 51 onto the sheet S passing through the transfer nip TN. In this way, an image is formed on the sheet S.

[0037] The fixing unit 14 is disposed downstream of the image forming unit 13 on the conveying path 201. The fixing unit 14 has a heating roller 61, a pressure roller 62, a heater 63, and a temperature sensor (not shown). The heating roller 61 heats the sheet S. The pressure roller 62 forms a nip N between itself and the heating roller 61 and applies pressure to the sheet S. The pressure roller 62 rotates counterclockwise by the driving force of the main motor 40. The forward rotation of the pressure roller 62, which conveys the sheet S in the conveying direction, is the counterclockwise direction.

[0038] Heater 63 is, for example, a halogen heater, and heats heating roller 61. A temperature sensor (not shown) is provided near heating roller 61 to detect the temperature of heating roller 61. The temperature sensor outputs a signal corresponding to the detected temperature to the controller.

[0039] The fixing device 14 heats the sheet S with the heating roller 61 and rotates the pressure roller 62, thereby conveying the sheet S while applying pressure with the heating roller 61 and the pressure roller 62, thereby fixing the image formed on the sheet S by the image forming unit 13 to the sheet S.

[0040] Although the fixing device 14 has been described as including the heating roller 61, the pressure roller 62, and the heater 63, the invention is not limited to this. For example, the fixing device 14 may have a heater, a nip plate that receives radiant heat from the heater, a heating belt that rotates around the nip plate, and a pressure roller.

[0041] The fixing device 14 may also have a substrate on which a heat generating pattern is formed, a belt that rotates around the substrate, and a pressure roller, so that the substrate and the belt are in contact with each other. The fixing device 14 may also have a heating roller, a heater, and a pressure belt.

[0042] Next, the control configuration of the printer 2 will be described with reference to FIG. The controller 17 is configured with a CPU, an ASIC (application specific integrated circuit), etc. On the other hand, the memory 18 is an embedded memory, and may be configured by combining ROM, RAM, NVRAM, SSD, HDD, etc. The ROM, RAM, and NVRAM provided in the controller 17 and used when executing various programs may also be considered as part of the memory 18.

[0043] The memory 18 is an example of a storage medium readable by the controller 17. A storage medium readable by the controller 17 is a non-transitory medium. In addition to the above examples, non-transitory media also include recording media such as CD-ROMs and DVD-ROMs. Non-transitory media are also tangible media. On the other hand, an electrical signal carrying a program downloaded from a server on the Internet is a computer-readable signal medium, which is a type of computer-readable medium, but is not included in non-transitory computer-readable storage media.

[0044] The memory 18 stores programs executable by the controller 17. In this embodiment, the term primarily refers to the processing of the controller 17 in accordance with instructions written in the programs. In other words, in the following description, processes such as "judging," "selecting," "calculating," "deciding," "identifying," "acquiring," "receiving," and "controlling" refer to the processing of the controller 17. Note that "acquiring" is used as a concept that does not necessarily require a request. In other words, the process of the controller 17 receiving data without a request is also included in the concept of "the controller 17 acquiring data." Furthermore, "data" in this specification is represented by a bit string that can be read by the controller. Data with essentially the same meaning but different formats will be treated as the same data. The same applies to "information" in this specification.

[0045] In addition to the above programs, memory 18 also stores usage data for consumables. Examples of consumables for which usage data is recorded include the amount of toner remaining in a toner cartridge and the lifespan of the drum cartridge 41 (photosensitive drum 51). The usage data indicates the degree of use of the consumables, such as the number of pages printed since the last time the consumable was replaced, and the percentage of pages that have been printed to reach the recommended number of pages for replacement. Usage time, etc., may also be stored as usage data instead of the number of pages printed. In this embodiment, the usage data stored in memory 18 is transmitted as status information for the printer 2 in response to a request from PC 3.

[0046] The memory 18 also includes a receive buffer 18A. The receive buffer 18A is a storage medium that temporarily stores data received from the PC 3. Examples of data received from the PC 3 include print data, initial commands, status information return request commands, and cancel commands. For example, the print data represents the image formation to be performed by the printer 2. The print data includes PDF data that uses a file format called PDF (Portable Document Format). In PDF data, images are described using a page description language based on PostScript (registered trademark), and multiple operators related to the drawing of character strings, figures, images, etc. are arranged in processing order. Meanwhile, the initial commands, status information return request commands, and cancel commands are data written in Printer Job Language (PJL) and are used to cause the printer 2 to execute a specific process. Details of the commands will be described later. The data stored in the receive buffer 18A is deleted after the corresponding process is completed.

[0047] The display unit 16 is a liquid crystal display installed in the main body housing 11, and the operation panel unit 15 is, for example, a touch panel or operation buttons. They are located between the user who operates the printer 2 and the controller 17, and function as a user interface that provides various information to the user and accepts user operations.

[0048] The USB interface 19 is a type of communication interface. The USB interface 19 is connected to a USB interface 20 of the PC 3 via a USB connection cable, thereby enabling communication via USB. The controller 17 can receive data transmitted from the USB interface 20 of the PC 3 via the USB connection cable. The received data is stored in a receive buffer 18A.

[0049] On the other hand, in addition to the USB interface 20, the PC 3 is equipped with a controller 45 including a CPU, GPU, etc. for executing arithmetic processing, and further equipped with storage media such as ROM, RAM, and HDD, display means such as a display, and operation means such as a keyboard and mouse. When connected to the printer 2, the PC 3 sends print data, status information return request commands, cancel commands, etc. to the printer 2.

[0050] Note that these data and commands may be sent in response to a user operation on PC 3, or at a timing independent of user operation. For example, print data may be sent when a print instruction is received from a user with the printer driver for printer 2 installed on PC 3. A status information return request command may be sent when a certain amount of time has elapsed since connection with printer 2 was established, before the print process is executed (after a print instruction is received but before the print data is sent), or when a predetermined amount of time has elapsed since the print data was sent. Note that the time when a certain amount of time has elapsed since connection with printer 2 may also include the time when a certain amount of time has elapsed since the previous command was sent (i.e., every time a certain amount of time has elapsed). A cancel command may be sent when, after the print instruction has been accepted, a user cancels the print operation.

[0051] [USB interface configuration] Next, we will explain the USB interface 19 provided on the printer 2 and the USB interface 20 provided on the PC 3. USB connects the host side, PC 3, and the device side, printer 2, using a single USB connection cable, but it is possible to create multiple communication paths within the single cable in software terms, making it possible to transmit data multiplexed. Below, each of these virtual multiplex transmission paths will be referred to as a "pipe."

[0052] As shown in FIG. 3, the USB interface 19 of the printer 2 and the USB interface 20 of the PC 3 are provided with logical channels (communication endpoints) called endpoints. For example, the example shown in FIG. 3 will be described with four endpoints, EP0 to EP3, but the number of endpoints is not limited to four and may be three or less, or five or more. When the device (printer 2) and the host (PC 3) are connected via USB, initial commands are exchanged, and the device notifies the host of the interface configuration (what functions it has and how many endpoints it will use to realize those functions). The host then assigns its own endpoints to form pipes and assigns appropriate class drivers. As a result, pipes are formed connecting the endpoints, and data can then be transmitted via the pipes and endpoints.

[0053] A USB interface always has endpoint 0 (EP0), which is a dedicated endpoint for basic information exchange (control transfer) between the host and device. The pipe connecting two endpoints (EP0) (P0 in Figure 3) is called a control transfer pipe. Other pipes (P1 to P3 in Figure 3) include an IN pipe, which inputs data from the device to the host, and an OUT pipe, which outputs data from the host to the device. While the control transfer pipe P0 is a bidirectional pipe that can both send and receive data, the other pipes P1 to P3 are unidirectional pipes, where data flows only in a predetermined direction (an IN pipe inputs data to the host, and an OUT pipe outputs data from the host). While the example in Figure 3 connects EP1 to EP1, EP2 to EP2, and EP3 to EP3, the endpoints connected to the pipes P1 to P3 other than the control transfer pipe P0 are not fixed and can be changed each time a connection is made.

[0054] Furthermore, the control transfer pipe P0 is set to a smaller size (for example, 1024 bytes) as the maximum amount of data that can be sent in one transfer compared to the other pipes P1 to P3. Furthermore, the control transfer pipe P0 is set to process data with higher priority than the data sent through the other pipes P1 to P3, and also performs timeout processing (responding with NACK) if no reply is received within a predetermined time after sending a command. In other words, data does not generally accumulate during data transfer using the control transfer pipe P0.

[0055] As described above, data exchanged between the printer 2 and PC 3 in this embodiment includes print data, initial commands, status information return request commands, and cancel commands. In this embodiment, print data is transmitted using one of the pipes P1 to P3 other than the control transfer pipe P0, while the initial command, status information return request command, and cancel command are transmitted using the control transfer pipe P0. The status information return request command is a command used by PC 3 to request current status information about the printer 2 (such as information about consumables used by the printer 2 and information about the current state of the printer 2 (printing in progress, an error, etc.)). The cancel command is a command used by PC 3 to instruct the printer 2 to stop (cancel) the printing process.

[0056] Here, when transmitting print data, for example, in situations where printing processing cannot be performed due to a paper jam or the depletion of consumables, or when transmitting large print data that takes a long time to transmit, the data may become stuck in the pipe or unable to be processed within the printer (i.e., remaining unprocessed in the receive buffer 18A). Therefore, if the status information return request command or cancel command were transmitted using the same pipe as the print data transmission, under the circumstances where preceding print data is stuck as described above, the printer would not be able to process the status information return request command or cancel command, and PC 3 would not be able to obtain status information from printer 2 or cancel the printing processing. On the other hand, the control transfer pipe has the above characteristics, and data transmission using the control transfer pipe generally does not result in data being stuck. Therefore, in this embodiment, data is transmitted using the control transfer pipe for the initial command, status information return request command, and cancel command. Furthermore, for the status information return request command, the status information returned from printer 2 is also transmitted using the control transfer pipe, just like the status information return request command. As a result, even in situations where print data is being held up (more specifically, while print data is being received, after print data has been received and the received print data is being stored in receive buffer 18A, after print data has been received and a reason for interruption has occurred in the printing process based on the received print data, etc.), printer 2 can immediately process the status information return request command or cancel command sent from PC 3, making it possible to obtain status information or cancel printing at any time.

[0057] [Control processing by the controller] Next, among the various control processes executed by the controller 17 of the printer 2 having the above configuration, the control processes executed based on print data and commands transmitted from the PC 3 will be described together with the processes executed by the PC 3 with reference to FIGS. 4 and 5. Both FIGS. 4 and 5 are flowcharts of the main process of the printer 2. The main process is executed after the printer 2 is turned on. FIG. 4 is a flowchart illustrating the control process of the main process, particularly when print data and a status information return request command are received. FIG. 5 is a flowchart illustrating the control process of the main process, particularly when print data and a cancel command are received. The programs for executing the processes shown in the flowcharts in FIGS. 4 and 5 are stored in the memory of the printer 2 and the memory of the PC 3, and are executed by the controller 17 of the printer 2 and the controller 45 of the PC 3.

[0058] As a first embodiment, the control process when print data and a status information return request command are received from PC 3 will be described below with reference to Fig. 4. Note that the following description is based on the premise that printer 2 and PC 3 are connected via a USB cable, and that the creation of the pipe between the endpoints described above (see Fig. 3) has also been completed.

[0059] First, the processing on the PC 3 side will be described. In step (hereinafter abbreviated as S) 1, the controller 45 sends print data to the printer 2. The print data is data that represents the content of the image formation to be performed by the printer 2, and includes image data such as PDF, for example. The print data may also be referred to as a print job. Furthermore, the trigger for sending the print data in S1 may be when a print instruction is received from a user with the printer driver for the printer 2 installed in the PC 3. However, it is also possible to send the print data when a predetermined condition is met, regardless of user operation.

[0060] In addition, for the transmission of the print data of S1, as shown in Figure 3, among the pipes other than the control transfer pipe P0, the OUT pipe (for example, P1) output from the host side is used as the pipe for transmitting the print data, and the data is transmitted.

[0061] Next, in S2, the controller 45 sends a status information return request command to the printer 2. The status information return request command is data written in printer job language (PJL), and more specifically, is a command in which the PC 3 requests current status information of the printer 2 (information about consumables used by the printer 2, information about the current state of the printer 2 (printing in progress, an error, etc.)). For example, triggers for sending the status information return request command in S2 include when a certain amount of time has elapsed since connection with the printer 2 was established, when before executing a print process (after receiving a print instruction but before sending print data), and when a predetermined amount of time has elapsed since sending print data. However, the timing when a certain amount of time has elapsed since connection with the printer 2 may also include when a certain amount of time has elapsed since the previous command was sent (i.e., every time a certain amount of time has elapsed).

[0062] Furthermore, for the transmission of the status information return request command in S2, data is transmitted using the control transfer pipe P0 as shown in FIG.

[0063] 4, after the print data is sent in S1, the status information return request command is sent in S2, but as mentioned above, the trigger for sending the status information return request command may occur before the print data is sent, or may occur independently of the print data being sent. Therefore, the order in which the steps are performed is not necessarily in ascending order of step number.

[0064] Thereafter, in S4, the controller 45 determines whether or not it has received status information returned from the printer 2 in response to the status information return request command sent in S2. Note that the returned status information is also sent using the same control transfer pipe P0 as the status information return request command.

[0065] If it is determined that status information has not been received from the printer 2 (S3: No), the process waits, and if it is determined that status information has been received from the printer 2 (S3: Yes), the process ends.

[0066] The status information received in S3 is notified to the user as necessary, and is reflected in the processing contents of PC3.

[0067] For example, when information regarding various consumables used in the printer 2 is received as status information, the following processing can be performed. Specifically, when the remaining amount of paper stored in the printer 2 is acquired, the current remaining amount of paper is displayed on the screen of the PC 3. In particular, a warning is given to the user when the remaining amount of paper is low or when the printer runs out of paper. Furthermore, when the remaining amount of toner stored in the toner storage unit 57 (e.g., a toner cartridge) of the printer 2 is acquired as status information, the current remaining amount of toner is displayed on the screen of the PC 3. In particular, a warning is given to the user when the remaining amount of toner is low or when the printer runs out of toner. Furthermore, when the life of the drum cartridge 41 installed in the printer 2 is acquired as status information, the current life of the drum cartridge 41, such as when it will need to be replaced and the approximate number of pages that can be printed, is displayed on the screen of the PC 3. In particular, a warning is given to the user when the replacement time is approaching or when the replacement time has been reached.

[0068] It is not necessary to acquire all of the above information as information relating to consumables used in the printer 2, and only a portion of the information may be acquired.

[0069] Furthermore, in addition to the information about the above consumables, if information about the current state of printer 2 is obtained as status information, and printer 2 is in a normal state, no special processing is required. However, if status information is obtained indicating that a reason for interruption to the printing process has occurred, for example, the fact that a reason for interruption to the printing process has occurred on printer 2 is displayed on the screen of PC 3.

[0070] Next, the processing on the printer 2 side will be described with reference to Fig. 4. Note that each of the following processing steps S11 to S17 starts when the corresponding information is received from the PC 3. Therefore, the order in which the steps are performed is not necessarily the order of the lowest step numbers.

[0071] First, in S11, the controller 17 receives the print data transmitted from the PC 3. The received print data is then temporarily stored in the receive buffer 18A.

[0072] Thereafter, the controller 17 executes a print process for the print data stored in the receive buffer 18A. Specifically, the controller 17 first executes a RIP (Raster Image Processor) process. The RIP process includes, for example, an analysis process for sequentially analyzing multiple operators in the PDF data included in the print data, a construction process for sequentially constructing drawing objects, such as character strings, figures, and images, indicated by the operators through the analysis process, in an image space of one page, and a process for writing the image of one page constructed through the construction process to the memory 18 as raster data. After executing the RIP process and storing the raster data in the memory 18, the controller 17 waits until the preparatory operation of the image forming unit 13 is completed. If it determines that the preparatory operation of the image forming unit 13 is completed, the controller 17 executes an image forming operation for forming an image of the print data on the sheet S using the image forming unit 13. The image forming operation by the image forming unit 13 has already been described using FIG. 2, and therefore further description will be omitted.

[0073] Then, in S12, the controller 17 determines whether or not the print process (including reception, RIP processing, and image formation after analysis) based on the print data received in S11 is currently being executed.

[0074] If it is determined that the printing process based on the print data received in S11 has been completed (S12: No), the process ends; if it is determined that the printing process is currently in progress (S12: Yes), the process proceeds to S13.

[0075] In S13, the controller 17 determines whether a reason for interrupting the printing process has occurred. Possible reasons for interruption include, for example, a paper jam in the transport path or running out of paper. The controller 17 is capable of detecting a paper jam in the transport path or running out of paper based on the detection results of sensors that detect the passage of the sheet S in the transport path, particularly the pre-registration sensor SE4, the post-registration sensor SE5, and the discharge sensor SE6. Possible reasons for interruption include, for example, no free space in the storage area of ​​the receive buffer 18A of the printer 2, an error occurring during RIP processing in the printer 2, for example, in analyzing the print data, the front cover 21 of the printer 2 being open, or the supply tray 31 of the printer 2 being open.

[0076] If it is determined that a reason for interrupting the printing process has occurred (S13: Yes), the printing process is temporarily interrupted. The interrupted printing process will resume if it is later determined that the reason for interruption has been resolved. On the other hand, if it is determined that a reason for interrupting the printing process has not occurred (S13: No), the process returns to S12 and waits until the printing process is completed.

[0077] On the other hand, in S15, the controller 17 receives the status information return request command sent from the PC 3. The received data is stored in the receive buffer 18A.

[0078] Thereafter, the controller 17 executes PJL analysis to analyze the received status information reply request command. Note that in this embodiment, the status information reply request command is transmitted using the control transfer pipe P0, which is different from the pipe that transmits the print data, so the status information reply request command does not generally remain stagnant.

[0079] Then, in S16, the controller 17 determines whether or not the analysis process of the status information return request command received in S15 is currently being executed.

[0080] If it is determined that the analysis process of the status information reply request command is currently being executed (S16: Yes), the process waits until the analysis is completed. On the other hand, if it is determined that the analysis process of the status information reply request command received in S15 has been completed (S16: No), the process returns the status information to the requesting PC 3 (S17).

[0081] The status information returned in S17 is also transmitted using the control transfer pipe P0, just like the status information return request command. Therefore, even if print data is backed up in the pipe, the status information can be returned without delay. In particular, the status information return request command can be received while the print process is being interrupted. It is also possible to return the status information while the print process is being interrupted. While FIG. 4 illustrates an example in which the status information is returned to the requesting PC 3 in S17 between S14 and S13, i.e., while the print process is being interrupted, the timing of returning the status information to the requesting PC 3 is not limited to this. For example, the status information may be returned in S17 between S11 and S12. The status information may be returned in S17 between S12 and S13, or between S13 and S12. The status information may be returned in S17 after S12.

[0082] Here, a case will be described in which the status information is returned, particularly information indicating the current status of the printer 2. When a reason for interruption of the printing process occurs in the printer 2, the controller 17 returns status information indicating that a reason for interruption has occurred in the printing process, i.e., status information including information indicating that a reason for interruption has occurred in the printing process. The controller 17 may include information indicating which reason for interruption has occurred in the status information indicating that a reason for interruption has occurred. Specifically, the controller 17 may include, in the status information indicating that a reason for interruption has occurred, information indicating a paper jam if a paper jam has occurred; information indicating that a paper out state if a paper out state has occurred; information indicating that the receive buffer 18A is full if there is no free space in the storage area of ​​the receive buffer; information indicating that an error has occurred in the RIP process if an error has occurred in the RIP process; information indicating that the front cover 21 is open; and information indicating that the supply tray 31 is open if there is no free space in the receive buffer.

[0083] The above example is one example of status information returned by the controller 17. For example, when another interruption reason occurs, the controller 17 may include information indicating the other interruption reason in the status information. For example, when no interruption reason occurs, the controller 17 may return status information indicating normal operation, printing, preparing to print, printing completed, etc. Note that the controller 17 may return information indicating the current status of the printer 2 in addition to information indicating that an interruption reason has occurred in the printing process. The controller 17 may also send information regarding consumables used in the printer 2 as information indicating the current status of the printer 2, including such information in the status information. The information regarding consumables included in the status information by the controller 17 may include information regarding the remaining amount of paper in the supply tray 31 of the printer 2, information regarding the remaining amount of toner in the toner cartridge, information regarding the life of the drum cartridge, etc. The controller 17 can obtain such information from the memory 18 or from the detection results of each sensor provided in the printer 2.

[0084] Upon receiving the status information returned from the printer 2 in S17, the PC 3 notifies the user of the received status information as necessary, or reflects the information in the processing content of the PC 3. For example, when status information indicating that a reason for interruption has occurred in the printing process is received, the PC 3 displays a screen indicating that a reason for interruption has occurred on the display unit of the PC 3. The PC 3 may also include information indicating what kind of reason for interruption has occurred in the screen indicating that a reason for interruption has occurred, and display this screen on the display unit of the PC 3.

[0085] In addition, in S17, all status information related to the printer 2 may always be returned, or the content of the returned status information may be changed depending on the situation. For example, the PC 3 may send a status information return request command (A) when a certain time has elapsed since connecting to the printer 2, but this may also include when a certain time has elapsed since the previous command was sent (i.e., each time a certain time has elapsed); (B) before executing the print process (after receiving a print instruction but before sending print data); or (C) when a certain time has elapsed since sending print data. Since the information required by the host side differs at each timing, the type of status information returned may be changed for each timing. Specifically, at timing (B), only information related to consumables used by the printer 2 may be returned as status information, and at timings (A) and (C), only information indicating the current state of the printer 2 may be returned as status information. Note that at either timing, if a reason for interruption to the print process has occurred, the controller 17 returns status information including information indicating that a reason for interruption to the print process has occurred.

[0086] Next, as a second embodiment, the control process when print data and a cancel command are received from PC 3 will be explained using Fig. 5. Note that the following explanation is based on the premise that printer 2 and PC 3 are connected by a USB connection cable, and that the formation of the pipe between the endpoints described above (see Fig. 3) has also been completed.

[0087] First, the processing on the PC 3 side will be described. In S21, the controller 45 transmits print data to the printer 2. The processing in S21 is the same as the processing in S1, and therefore a description thereof will be omitted.

[0088] Next, in S22, the controller 45 sends a cancel command to the printer 2. The cancel command is data written in printer job language (PJL), and more specifically, is a command that requests that the printing process being performed by the printer 2 be stopped (cancelled). For example, the trigger for sending the cancel command in S22 may be when an instruction to cancel printing is received from the user after the print data has been sent in S21. However, it is also possible to send the cancel command when a predetermined condition is met, regardless of user operation.

[0089] Furthermore, in regard to the transmission of the cancel command in S22, data is transmitted using the control transfer pipe P0 as shown in FIG.

[0090] Next, the processing on the printer 2 side will be described with reference to Fig. 5. Note that each of the following processing steps S31 to S40 starts when the corresponding information is received from the PC 3. Therefore, the order in which the steps are performed is not necessarily the order of the lowest step numbers.

[0091] The processes in S31 and S32 are the same as those in S11 and S12, and therefore will not be described here.

[0092] If it is determined that printing processing is in progress (S32: Yes), the controller 17 determines in S33 whether a cancel process has been executed. The cancel process is executed when a cancel command is received from the PC 3 in S39 and S40 (described later), and is a process for halting the printing processing currently in progress. Note that the reception of the cancel command in S39 is performed independently of the reception of the print data in S31, so the cancel process may be executed while the print data is being received.

[0093] If it is determined that the cancellation process has been executed (S33: Yes), the analysis process for the print data currently in progress is stopped (S34). Therefore, for example, if the cancellation process is executed after the print data has been received and the print data stored in the receive buffer 18A is being analyzed, image formation for the corresponding print data is not performed. If the cancellation process is executed before the analysis process is performed, analysis (i.e., subsequent image formation) for print data that has already been received or is currently being received is not performed. On the other hand, if the cancellation process is executed after the analysis process is completed and image formation (such as forming a toner image on the surface of the photosensitive drum 51 and transferring it to the sheet S) has already begun, the image formation that has begun is continued, but in the case of printing multiple pages, image formation for a new page is not performed. Alternatively, even if image formation is in progress, subsequent image formation may be stopped once the cancellation process is executed. Note that cancellation may be triggered by events other than receiving a cancel command from PC 3. For example, when a cancel operation is received via the operation panel unit 15, the controller 17 may determine that the cancel process has been executed (S33: Yes).

[0094] On the other hand, if it is determined that the cancellation process has not been executed (S33: No), the process returns to S32 and waits until the printing process is completed.

[0095] Next, in S35, the controller 17 determines whether or not print data is being received at the time the cancellation process is executed.

[0096] If it is determined that print data is being received when the cancellation process is executed (S35: Yes), the reception of the print data is stopped (S36). On the other hand, if it is determined that print data is not being received when the cancellation process is executed (S35: No), the process ends.

[0097] Furthermore, in S37, the controller 17 determines whether or not the received print data exists in the receive buffer 18A at the time the cancellation process is executed.

[0098] If it is determined that received print data exists in the receive buffer 18A at the time the cancellation process is executed (S37: Yes), the print data in the receive buffer 18A is cleared (S38), and the process is then terminated. On the other hand, if it is determined that received print data does not exist in the receive buffer 18A at the time the cancellation process is executed (S37: No), the process is terminated.

[0099] On the other hand, in S39, the controller 17 receives the cancel command sent from the PC 3. The received data is stored in the receive buffer 18A.

[0100] The controller 17 then executes PJL analysis to analyze the received cancel command. In this embodiment, the cancel command is transmitted using the control transfer pipe P0, which is different from the pipe that transmits the print data, so the cancel command does not generally remain.

[0101] Then, in S40, the controller 17 executes a cancel process based on the cancel command received in S39. As a result, the printing process that was in progress in S34 to S38 described above is interrupted. While FIG. 5 illustrates an example in which the cancel command is received in S39 between S31 and S32, i.e., while print data is being received and RIP processing and post-analysis image formation are not yet being performed, the timing for receiving the cancel command is not limited thereto. For example, the cancel command can be received during S32, i.e., while at least one of RIP processing and post-analysis image formation is being performed (either while only one of RIP processing and post-analysis image formation is being performed, or while both RIP processing and post-analysis image formation are being performed, or of course, even after print data reception is complete or while print data is being received). In this case, the cancel process is executed while the print data is being received or while print processing based on the print data that has been received is being performed. It is also possible to execute a cancellation process while a reason for interrupting the printing process has occurred.

[0102] As described above in detail, in the printer 2 according to this embodiment, if a status information reply request command is received from PC 3 via a control transfer pipe and endpoint (e.g., EP0) while the printer 2 is receiving print data via a print data communication pipe and endpoint (e.g., EP1), the printer 2 returns its own status information to PC 3, the source of the reply request command, via the control transfer endpoint (S17). Therefore, even if the print data being sent from PC 3 to printer 2 is backed up in the pipe, for example, by sending large print data that takes a long time to send, the printer 2 can process the status information reply request command via the control transfer endpoint. As a result, PC 3 can obtain status information from printer 2 at any time. Furthermore, the printer 2 can receive the status information reply request command via the existing control transfer endpoint without providing a new endpoint dedicated to sending the status information reply request command. Furthermore, the pipe connecting the control transfer endpoints allows bidirectional communication, so the USB interface configuration is not complicated. Furthermore, if a status information return request command is received via the control transfer endpoint after print data has been received via the print data communication endpoint and while the received print data is being stored in the receive buffer 18A, the printer 10 returns its own status information via the control transfer endpoint to PC3, the source of the return request command (S17). Therefore, even if the print process cannot be executed due to, for example, a paper jam or depletion of consumables, causing a backlog of print data to be sent from PC3 to printer 2, the printer 10 can process the status information return request command via the control transfer endpoint. Furthermore, if a status information return request command is received via the control transfer endpoint after print data has been received via the print data communication endpoint and a reason for interruption has occurred in the printing process based on the received print data, the printer will return its own status information via the control transfer endpoint to PC3, the source of the return request command (S17).This means that even in situations where a reason for interruption of the printing process has occurred, such as a paper jam or the depletion of consumables, the status information return request command can be processed via the control transfer endpoint. Furthermore, if a cancel command instructing the PC 3 to cancel printing is received via the control transfer endpoint while print data is being received via the print data communication endpoint, the PC 3 stops receiving the print data and controls the PC 3 not to perform printing based on the received print data (S34, S36). Therefore, even if the print data being sent from the PC 3 to the printer 2 is backed up in the pipe, for example, due to the transmission of large print data that takes a long time to transmit, the PC 3 can process the cancel command via the control transfer endpoint. As a result, cancellation can be performed from the PC 3 at any time. In other words, the PC 3 can be endowed with the same functionality as when a print cancellation command is issued from the printer itself. Furthermore, because the cancel command can be received via the existing control transfer endpoint without the need for a dedicated endpoint for sending the cancel command, the USB interface configuration is not complicated. Furthermore, if a cancel command instructing to cancel printing is received via the endpoint for control transfer after print data has been received via the endpoint for print data communication while print processing based on the received print data is in progress, control is performed to stop the print processing based on the received print data (S34). Therefore, even in a situation where print processing cannot be executed due to, for example, a paper jam or depletion of consumables, causing a backlog of print data being sent from PC3 to printer 2, it is possible to process the cancel command via the endpoint for control transfer.

[0103] The present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications are possible within the scope of the present invention. For example, in this embodiment, the triggers for sending a status information return request command from PC3 to printer 2 are the timing when a certain amount of time has elapsed since connection with printer 2 has been established, the timing before execution of print processing (after receiving a print instruction but before sending print data), and the timing when a certain amount of time has elapsed since sending print data, but other timings are also possible. Since the status information return request command is processed via control transfer pipe P0 and endpoint 0, PC3 can obtain status information from printer 2 at any timing.

[0104] Furthermore, in the above embodiment, a printer is described as the image forming apparatus, but it may also be a multifunction device that has a fax function, a copy function, and a scanner function in addition to a printer function. Alternatively, an inkjet printer may be used instead of a laser printer as long as it is capable of printing on a sheet S. When an inkjet printer is used, the information about consumables returned as status information will be information about the remaining amount of ink in the ink cartridge instead of the remaining amount of toner in the toner cartridge.

[0105] In addition, in the above embodiment, the status information returned includes information regarding consumables used by printer 2 and information regarding the current state of printer 2 (printing in progress, error in progress, etc.), but it is also possible to return the total number of pages printed by printer 2 as status information. [Explanation of symbols]

[0106] 1...image forming system, 2...printer (image forming apparatus), 3...PC (terminal device), 17...controller, 18...memory, 18A...receiving buffer, 19...(printer side) USB interface, 20...(PC side) USB interface, 31...supply tray (paper tray), EP0 to EP3...endpoints, P1 to P3...pipes

Claims

1. An image forming apparatus including a USB interface and a controller, the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for receiving data transmitted from a terminal device connected via a USB connection; The controller When a command requesting a return of status information of the image forming apparatus is received via the endpoint for control transfer while print data is being received via the endpoint for print data communication, The image forming apparatus is characterized in that it returns its own status information to the terminal device that is the request source of the reply request command via the endpoint for control transfer.

2. An image forming apparatus including a USB interface, a receiving buffer, and a controller, the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for receiving data transmitted from a terminal device connected via a USB connection; The controller After receiving print data via the endpoint for print data communication, if a return request command for status information of the image forming apparatus is received via the endpoint for control transfer while the received print data is being stored in the receive buffer, The image forming apparatus is characterized in that it returns its own status information to the terminal device that is the request source of the reply request command via the endpoint for control transfer.

3. An image forming apparatus including a USB interface and a controller, the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for receiving data transmitted from a terminal device connected via a USB connection; The controller After receiving print data via the endpoint for print data communication, when a return request command for status information of the image forming apparatus is received via the endpoint for control transfer while a reason for interruption occurs in the print processing based on the received print data, The image forming apparatus is characterized in that it returns its own status information to the terminal device that is the request source of the reply request command via the endpoint for control transfer.

4. An image forming apparatus including a USB interface and a controller, the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for receiving data transmitted from a terminal device connected via a USB connection; The controller When a cancel command instructing to cancel printing is received via the endpoint for control transfer while print data is being received via the endpoint for print data communication, The image forming apparatus is characterized in that, when reception of the print data is terminated, control is performed so as not to perform printing processing based on the received print data.

5. An image forming apparatus including a USB interface and a controller, the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for receiving data transmitted from a terminal device connected via a USB connection; The controller After receiving print data via the endpoint for print data communication, when a cancel command instructing to cancel printing is received via the endpoint for control transfer while printing processing based on the received print data is being performed, An image forming apparatus characterized by controlling to stop printing processing based on the received print data.

6. The controller When a cancel command instructing to cancel printing is received via the endpoint for control transfer while print data is being received via the endpoint for print data communication, 4. The image forming apparatus according to claim 1, wherein when reception of the print data is terminated, control is performed so that printing processing based on the received print data is not performed.

7. The controller After receiving print data via the endpoint for print data communication, when a cancel command instructing to cancel printing is received via the endpoint for control transfer while printing processing based on the received print data is being performed, 4. The image forming apparatus according to claim 1, wherein the control is performed so as to stop the printing process based on the received print data.

8. 4. The image forming apparatus according to claim 1, wherein the controller returns information about consumables used in the image forming apparatus as the status information.

9. 9. The image forming apparatus according to claim 8, wherein the controller returns information about the remaining amount of paper stored in the image forming apparatus as the status information.

10. 9. The image forming apparatus according to claim 8, wherein the controller returns information about the remaining amount of a toner cartridge or ink cartridge mounted in the image forming apparatus as the status information.

11. 9. The image forming apparatus according to claim 8, wherein the controller returns information about the life of a drum cartridge mounted in the image forming apparatus as the status information.

12. 4. The image forming apparatus according to claim 1, wherein the controller returns information indicating a current state of the image forming apparatus as the status information.

13. The controller When the reply request command is received while a reason for interruption of the printing process occurs in the image forming device, 13. The image forming apparatus according to claim 12, wherein the image forming apparatus returns status information indicating that a reason for interrupting the printing process has occurred in the image forming apparatus itself to the terminal apparatus that has issued the reply request command.

14. The controller If the reply request command is received when there is no free space in the storage area of ​​the receive buffer provided in the image forming apparatus, 13. The image forming apparatus according to claim 12, wherein the image forming apparatus returns status information indicating that there is no free space in the storage area of ​​its own receiving buffer to the terminal apparatus that is the source of the reply request command.

15. The controller If the reply request command is received while an error occurs in the analysis of the print data received via the endpoint for print data communication, 13. The image forming apparatus according to claim 12, wherein the image forming apparatus returns status information indicating that an error has occurred in the analysis of the print data to the terminal device that has issued the reply request command.

16. The device includes an openable / closable cover and a sensor for detecting whether the cover is open or closed, The controller If the reply request command is received while the cover is open, 13. The image forming apparatus according to claim 12, wherein the image forming apparatus returns status information indicating that its cover is open to the terminal device that has sent the reply request command.

17. a paper tray for storing paper sheets, and a sensor for detecting the open / closed state of the paper tray; The controller If the reply request command is received while the paper tray is open, 13. The image forming apparatus according to claim 12, wherein the image forming apparatus returns status information indicating that its own paper tray is open to the terminal device that has issued the reply request command.

18. An image forming system including an image forming apparatus and a terminal device connected to the image forming apparatus via a USB interface, the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for transmitting and receiving data between the terminal device and the image forming device, The terminal device print data can be transmitted to the image forming device via the print data communication endpoint; a command for requesting a return of status information of the image forming apparatus can be transmitted via the endpoint for control transfer while the print data is being transmitted via the endpoint for print data communication, the image forming apparatus, When the reply request command is received via the endpoint for control transfer while the print data is being received via the endpoint for print data communication, an image forming system that returns its own status information to the terminal device that is the request source of the reply request command via the endpoint for control transfer;

19. An image forming system including an image forming apparatus and a terminal device connected to the image forming apparatus via a USB interface, the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for transmitting and receiving data between the terminal device and the image forming device, The terminal device print data can be transmitted to the image forming device via the print data communication endpoint; A command requesting a return of status information of the image forming apparatus can be transmitted via the endpoint for control transfer, the image forming apparatus, After receiving print data via the endpoint for print data communication, if the reply request command is received via the endpoint for control transfer while the received print data is being stored in a receive buffer, an image forming system that returns its own status information to the terminal device that is the request source of the reply request command via the endpoint for control transfer;

20. An image forming system including an image forming apparatus and a terminal device connected to the image forming apparatus via a USB interface, the USB interface has an endpoint for print data communication and an endpoint for control transfer as endpoints for transmitting and receiving data between the terminal device and the image forming device, The terminal device print data can be transmitted to the image forming device via the print data communication endpoint; A command requesting a return of status information of the image forming apparatus can be transmitted via the endpoint for control transfer, the image forming apparatus, After receiving print data via the endpoint for print data communication, when the reply request command is received via the endpoint for control transfer while a reason for interruption occurs in the print processing based on the received print data, an image forming system that returns its own status information to the terminal device that is the request source of the reply request command via the endpoint for control transfer;

Images