Image forming apparatus

Abstract

To provide an image forming device that can form images on both surfaces, which can suppress a usage mode in which a function, durability, usability and the like of the device may deteriorate.SOLUTION: A control part selectively sets a normal mode in which operation of forming an image on a surface of a back side of a paper is executed after operation of forming an image on a surface of a front side of the paper is completed and a restricting mode in which the operation of forming an image on the surface of the back side of the paper is executed before the operation of forming an image on the surface of the front side of the paper is completed and then the operation of forming an image on the surface of the front side of the paper is completed, for double-sided treatment in which a recording head and a conveying part are controlled so that the operation of forming images on both surfaces of the front side and the back side of the paper. The control part sets the restricting mode when an event in which each treatment is interrupted is repeated at a certain frequency in multiple double-sided treatment.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an image forming apparatus that forms an image on a medium.

Background Art

[0002] There is an image forming apparatus capable of forming images on both sides (front and back) of a medium. In Patent Document 1 related to an example of such an apparatus, a medium (paper) is conveyed to an image forming unit so that the front surface becomes the image forming surface, and an image is formed on the front surface. After the image is formed on the front surface, the medium is conveyed again to the image forming unit so that the back surface becomes the image forming surface. Then, an image is formed on the back surface of the medium.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In double-sided image formation such as in Patent Document 1, image formation on the front surface is once completed, and then image formation on the back surface is executed. In this case, since the situation where the processing for the front surface is completed gives the user an impression that the entire processing is completed, compared to single-sided image formation, there is a high risk that the processing will be interrupted due to accidentally turning off the power or accidentally operating the apparatus. Frequent interruption of the processing tends to burden the apparatus and waste consumables for image formation such as ink. Therefore, such a usage mode that frequently causes interruption of the processing can cause deterioration of the functions, durability, usability, etc. of the apparatus.

[0005] The object of the present invention is to provide an image forming apparatus capable of forming images on both sides, which can suppress usage patterns that may reduce its functionality, durability, usability, etc. [Means for solving the problem]

[0006] The image forming apparatus of the present invention comprises: an image forming unit that performs an image forming operation to form an image on one of the front and back surfaces of a medium capable of forming an image on both its front and back surfaces; a medium transport unit that transports the medium to the image forming unit so that one of the front and back surfaces of the medium becomes the image forming surface, and after the image forming operation has been performed on one of the front and back surfaces of the transported medium, transports the medium to the image forming unit so that the other of the front and back surfaces of the medium becomes the image forming surface; and a control unit, wherein the control unit controls the image forming unit and the medium transport unit for double-sided processing so that the image forming operation is performed on both the front and back surfaces of the medium, and controls the image forming operation to form an image on only one of the front and back surfaces of the medium. It is possible to selectively perform single-sided processing, which controls the image forming unit and the media transport unit so that an image forming operation is performed. With respect to double-sided processing, it is possible to selectively adopt a normal mode in which the image forming operation on the back side of the medium is performed after the image forming operation on the front side of the medium is completed, and a restricted mode which is at least one of a first mode in which the image forming operation on the back side of the medium is performed before the image forming operation on the front side of the medium is completed, and then the image forming operation on the front side of the medium is completed, and a second mode which prohibits the execution of double-sided processing. Multiple double-sided processing operations are performed, and the restricted mode is adopted if the interruption of each operation in the multiple double-sided processing operations occurs repeatedly with a certain frequency.

[0007] The "certain frequency" condition described above may be met when the double-sided processing is interrupted a predetermined number of times consecutively, or when the number of interruptions reaches a predetermined ratio to a predetermined number of double-sided processing cycles, or it may be determined by various other methods. Furthermore, the terms "front side" and "back side" in this invention do not presuppose any difference in characteristics or appearance between the two sides of the medium. Regardless of the medium, either of its two sides may be designated as the front side, and in any case, the remaining side may be designated as the back side. [Effects of the Invention]

[0008] If double-sided processing is interrupted frequently, the device enters a restricted mode. The restricted mode consists of at least one of two modes: a first mode in which the image forming operation on the back side is performed before the image forming operation on the front side is completed, and a second mode in which double-sided processing is prohibited (single-sided processing is not prohibited unless there are other factors). When the restricted mode is the first mode, image forming on the back side is performed before the image forming on the front side is completed. Therefore, double-sided processing in restricted mode is less likely to give the user the impression that the entire process is complete midway through, compared to double-sided processing in normal mode in which image forming on the back side is performed after the image forming on the front side is completed. Thus, actions that could lead to users interrupting the process due to mistakenly believing that the process is complete are suppressed. Furthermore, when the restricted mode is the second mode, the execution of double-sided processing itself, which may cause processing interruptions, is prohibited. Therefore, in either the first or second mode, the restricted mode suppresses usage patterns that would cause frequent interruptions to double-sided processing. In other words, usage patterns that could reduce functionality, durability, usability, etc., are suppressed. Furthermore, even if frequent interruptions occur due to other usage patterns, the user can be made aware of the cause of the frequent interruptions by issuing a restriction mode. This encourages users to avoid usage patterns that could cause frequent interruptions, and as a result, usage patterns that could degrade the functionality, durability, and usability of the device are suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic side view showing the internal structure of a printer according to one embodiment of the present invention. [Figure 2] This block diagram shows the electrical configuration of the printer shown in Figure 1. [Figure 3] Figure 1 is a conceptual diagram illustrating the situation in which the image that should be formed on the front side of the paper is divided when the printer performs double-sided printing in restricted mode. [Figure 4] Figure 1 is a flowchart showing the sequence of processes executed by the control unit. [Figure 5] This flowchart shows the flow of a series of processes performed by a control unit according to another embodiment of the present invention. [Modes for carrying out the invention]

[0010] [First Embodiment] Hereinafter, a printer 10, which is an inkjet printer according to a first embodiment that is a preferred embodiment of the present invention, will be described with reference to the drawings. In the following description, the vertical direction is defined based on the state in which the printer 10 is installed for use (the state in Figure 1), the front-to-back direction is defined with the side of the housing 11 with the opening 13 provided as the front side, and the left-to-right direction is defined when viewing the printer 10 from the front side.

[0011] The printer 10 can selectively perform single-sided printing, which forms an image only on the front side of the paper 9, and double-sided printing, which forms an image on both the front and back sides of the paper 9. As shown in Figure 1, the printer 10 includes a paper feed tray 4, a paper output tray 5, a recording unit 6, a transport unit 7, a control unit 8, and a housing 11. The housing 11 includes an upper cover 11a and a housing body 11b. The housing body 11b (corresponding to the "body" of the present invention) houses the paper feed tray 4, the recording unit 6, the transport unit 7, and the control unit 8. The upper cover 11a (corresponding to the "cover" of the present invention) is supported by the housing body 11b so that it can rotate in the R direction around the hinge 11c. As a result, the upper cover 11a can move between an open position that exposes the components of the recording unit 6 and other components housed in the housing body 11b to the outside, and a closed position that shields these components from the outside. The user can manually open and close the upper cover 11a for purposes such as replacing ink cartridges or maintenance. Whether the upper cover 11a is in the open or closed position is detected by an open / close sensor 41 located near the opening of the upper cover 11a. The detection result from the open / close sensor 41 is output to the control unit 8. This detection result is used for control described later, based on the opening operation of the upper cover 11a (movement from the closed position to the open position).

[0012] The paper feed tray 4 is capable of supporting and storing multiple sheets of paper 9 in a stacked state and is located below the recording unit 6. The paper feed tray 4 can be inserted into and removed from the housing 11 in the front-to-back direction. The paper feed tray 4 has a support surface 4a for supporting the paper 9.

[0013] The output tray 5 holds the paper 9 on which an image has been formed by the recording head 63 of the recording unit 6, which will be described later. The output tray 5 is located above the front side of the feed tray 4 and moves in the front-to-back direction together with the feed tray 4.

[0014] The recording unit 6 has a carriage 61 and a recording head 63 (corresponding to the "image forming unit" of the present invention). The carriage 61 is supported by two guide rails 67a and 67b. The two guide rails 67a and 67b are spaced apart from each other in the front-rear direction and each extends in the left-right direction. The carriage 61 is positioned to straddle the two guide rails 67a and 67b. The carriage 61 is capable of reciprocating along the two guide rails 67a and 67b in the left-right direction, which is the main scanning direction, by the driving force of the carriage drive motor 31 (see Figure 2).

[0015] The recording head 63 is mounted on the carriage 61 and moves back and forth with the carriage 61 in the main scanning direction. The recording head 63 performs an image forming operation in which it forms an image on the image forming surface, which is the surface of the paper 9 that is opposite the nozzle surface 69, by ejecting ink supplied from an ink cartridge (not shown) from nozzles (not shown) provided on the nozzle surface 69 on its lower surface.

[0016] The transport unit 7 (corresponding to the "media transport unit" of the present invention) transports the paper 9 inside the printer 10 and includes a paper feed roller 70, transport roller pairs 71-74, a platen 75, and guide members 16 and 17.

[0017] The paper feed roller 70 is positioned to contact the uppermost sheet of paper 9 supported in the paper feed tray 4. The paper feed roller 70 rotates under the driving force from the paper feed motor 33 (see Figure 2), feeding the paper 9 in the paper feed tray 4 backward. The paper 9 fed out of the paper feed tray 4 by the paper feed roller 70 is then fed into the transport path 14 that extends from the paper feed tray 4 to the recording unit 6.

[0018] The conveying roller pairs 71 to 74 each include two rollers that contact each other, and are configured to convey the sheet 9 while sandwiching it between the two rollers. One of the two rollers constituting each conveying roller pair 71 to 74 is a driving roller, which rotates when the driving force from the conveying motor 34 (see FIG. 2) is applied. The other of the two rollers constituting each conveying roller pair 71 to 74 is a driven roller, which is rotated along with the rotation of the driving roller.

[0019] The conveying roller pairs 71, 72, and 74 are rotatable only in the forward direction (in the conveying roller pairs 71 and 72, the direction in which the sheet 9 is conveyed in the direction D1 indicated by the solid black arrow in FIG. 1; in the conveying roller pair 74, the direction in which the sheet 9 is conveyed in the direction D2 indicated by the white arrow in FIG. 1). The conveying roller pair 73 is rotatable in both the forward and reverse directions (the direction in which the sheet 9 is conveyed in the direction D1 and the direction in which the sheet 9 is conveyed in the direction D2).

[0020] The conveying roller pairs 71 and 72 are arranged sandwiching the recording unit 6 in the front-rear direction. The conveying roller pair 71 is arranged behind the recording unit 6, and the conveying roller pair 72 is arranged in front of the recording unit 6. The conveying roller pair 71 sends the sheet 9 sent out from the paper feed tray 4 by the paper feed roller 70 to the image recording area F facing the nozzle surface 69 of the recording head 63. An image is formed on the image forming surface facing the nozzle surface 69 of the recording head 63 of the sheet 9 sent to the image recording area F by the ink ejected from the recording head 63. The conveying roller pair 72 receives the sheet 9 sent by the conveying roller pair 71 and sends it forward.

[0021] The conveyance roller pair 73 receives the sheet 9 sent by the conveyance roller pair 72. When performing single-sided printing to form an image only on the front side of the sheet 9, and when performing double-sided printing to form images on both sides of the sheet 9, and when image formation on both sides of the sheet 9 has already been completed, the conveyance roller pair 73 rotates in the forward direction to discharge the sheet 9 to the discharge tray 5. When performing double-sided printing and when performing an image formation operation on a surface different from the surface on which the most recent image formation operation by the recording unit 6 was performed, the conveyance roller pair 73 reverses the rotation direction from the forward direction to the reverse direction when the rear end of the sheet 9 in the conveyance direction reaches the vicinity of the conveyance roller pair 73, and feeds the sheet 9 into the reverse conveyance path 15 extending from the vicinity of the conveyance roller pair 73 to below the recording unit 6.

[0022] The conveyance roller pair 74 receives the sheet 9 fed into the reverse conveyance path 15 by the conveyance roller pair 73 and sends it rearward. The sheet 9 fed into the reverse conveyance path 15 is fed into the middle of the conveyance path 14 extending from the paper feed tray 4 to the recording unit 6 at the rear end of the apparatus. The sheet 9 fed from the reverse conveyance path 15 to the conveyance path 14 is conveyed to the image recording area F so that the surface opposite to the surface on which the most recent image formation operation by the recording unit 6 was performed faces the nozzle surface 69 of the recording head 63. Thereby, an image formation operation by the recording unit 6 is executed on the opposite surface.

[0023] The platen 75 is disposed below the recording unit 6 so as to face the nozzle surface 69 of the recording unit 6. The platen 75 supports the sheet 9 conveyed to the image recording area F. The guide member 16 defines the conveyance path 14 that feeds the sheet 9 sent out from the paper feed tray into the image recording area F. The guide member 17 defines the reverse conveyance path 15 extending from the vicinity of the conveyance roller pair 73 to below the recording unit 6.

[0024] The control unit 8 is responsible for controlling the entire printer 10, and as shown in Figure 2, it is electrically connected to the carriage drive motor 31, recording head 63, paper feed motor 33, transport motor 34, etc. The control unit 8 includes a CPU (Central Processing Unit) 81, memory 82, ASIC (Application Specific Integrated Circuit) 83, etc., and these work together to control the operation of the carriage drive motor 31, recording head 63, paper feed motor 33, and transport motor 34.

[0025] Memory 82 is composed of ROM (Read Only Memory), RAM (Random Access Memory), flash memory, etc., and stores the program 82a executed by the CPU 81. The RAM of memory 82 is used as a work area from which various programs are read and as a storage area for temporarily storing image data. Image data is data that the printer 1 receives from external devices such as a PC or reads from a recording medium. The flash memory of memory 82 stores various data that needs to be retained even after the power is turned off. In this embodiment, the number of consecutive error detections (hereinafter represented by the variable "a"), the number of consecutive error-free counts (hereinafter represented by the variable "b"), and the print counter (hereinafter represented by the variable "c") are stored in the flash memory. Of these, the number of consecutive error detections a and the number of consecutive error-free counts b are used to control the mode selection for double-sided printing, as described later. The print counter c is used as a criterion for determining the aging of the printer 10 and for various management based on the cumulative number of printed pages. A printing flag, described below, is stored in flash memory to check whether double-sided printing has been interrupted. The printing flag can selectively take an on or off state, and is off by default. The ASIC83 performs tasks such as rewriting image data.

[0026] The program 82a stored in memory 82 may be pre-stored during the manufacturing of the printer 10. The program 82a may be provided in the form of a CD-ROM or the like, or it may be provided via a communication network such as the Internet. The CPU 81 controls the printer 10 by executing the program 82a.

[0027] The image data stored in memory 82 is image data relating to the image formed on the paper 9 by the ink ejected from the recording head 63. The image data stored in memory 82 is data defined for each nozzle and each pixel, indicating the amount of ink to be ejected from the nozzles of the recording head 63. Pixels are elements that constitute the image formed on the paper 9 and are arranged in a matrix corresponding to the image formation area on the paper 9. Memory 82 can store at least the image data relating to the images formed on both the front and back surfaces of the paper 9 during double-sided printing, all at once.

[0028] In Figure 2, one CPU 81 and one ASIC 83 are shown, but the control unit 8 may include only one CPU 81, which may perform all the necessary processing at once, or it may include multiple CPU 81s, which may share the necessary processing amongst themselves. Similarly, the control unit 8 may include only one ASIC 83, which may perform all the necessary processing at once, or it may include multiple ASIC 83s, which may share the necessary processing amongst themselves.

[0029] The control unit 8 selectively performs a double-sided process that controls the recording unit 6 and the transport unit 7 so that double-sided printing is performed on the paper P, and a single-sided process that controls the recording unit 6 and the transport unit 7 so that single-sided printing is performed on the paper P.

[0030] Furthermore, when performing double-sided processing, the control unit 8 selectively adopts either a normal mode or a restricted mode. The normal mode is a mode in which the image forming operation by the recording unit 6 on the front side of the paper P is completed before the image forming operation by the recording unit 6 on the back side of the paper P is performed. The restricted mode is a mode in which the image forming operation by the recording unit 6 on the back side of the paper P is performed before the image forming operation by the recording unit 6 on the front side of the paper P is completed, and then the image forming operation on the front side of the paper P is completed (corresponding to the "first mode" of the present invention).

[0031] The restriction mode will be explained in more detail. In restriction mode, the control unit 8 controls the recording unit 6 and the transport unit 7 so that only a portion of the image to be formed on the front side of the paper P is formed on the front side, then the entire image to be formed on the back side of the paper P is formed on the back side, and then the remaining portion of the image to be formed on the front side of the paper P is formed on the front side. In other words, the image to be formed on the front side of the paper P is divided into two parts, one part is formed on the front side, then the image formation on the back side is completed, and then the remaining part is formed on the front side. When dividing the image, the control unit 8 determines whether or not there is a blank area in the image to be formed on the front side. A blank area is a blank area (an area where no pixels exist) that extends across the entire horizontal range of the image in the direction perpendicular to the direction in which the paper P is transported by the transport unit 7. If it is determined that there is a blank area, the control unit 8 sets the boundary between the two divided parts to that blank area. If it is determined that there is no blank area, the control unit 8 sets the boundary between the two divided parts to an appropriate position. For example, the position is set so that the first image formation area is a portion corresponding to 90% of the total image size, and the next image formation area is a portion corresponding to the remaining 10% of the total image size.

[0032] As an example of double-sided processing in restricted mode, let's assume that the image IM shown in Figure 3 is formed on the front side of the paper P. The image IM includes three regions: pixel-existing region 1, a blank region, and pixel-existing region 2, which are aligned in the vertical direction corresponding to the transport direction of the paper P. Pixel-existing regions 1 and 2 are regions that do not contain pixels across their entire horizontal range. The blank region is a region sandwiched vertically between pixel-existing region 1 and pixel-existing region 2, and does not contain pixels across its entire horizontal range. When double-sided processing is performed in restricted mode on such an image IM, as described above, the boundary between the two divided parts is set to the blank region. As a result, the area to be image-formed is divided into divided part 1, which includes pixel-existing region 1, and divided part 2, which includes pixel-existing region 2. Divided part 1 is formed on the front side, and only after image formation on the back side is completely finished is divided part 2 formed on the front side.

[0033] The restriction mode is selected based on the number of times duplex printing has been interrupted due to an error. In this embodiment, errors that cause interruption of duplex printing are assumed to be power-off operations during duplex printing and opening operations of the upper cover 11a. Of these, power-off operations are performed by operating the power switch provided on the printer 10 or by unplugging the power cord from the outlet. Opening the upper cover 11a is performed by manually lifting the upper cover 11a. The control unit 8 updates the number of consecutive error detections a stored in the flash memory of memory 82 each time an interruption of duplex printing due to an error occurs. When executing duplex processing, the control unit 8 executes duplex processing in restriction mode if a is equal to or greater than a predetermined threshold X, and executes duplex processing in normal mode otherwise. The control unit 8 also updates the number of consecutive error-free operations b stored in the flash memory of memory 82 each time duplex printing is completed without interruption due to an error. The control unit 8 resets the number of consecutive error detections a to 0 when b becomes equal to or greater than a predetermined threshold Y. In other words, once the number of consecutive error detections a exceeds X and the restriction mode is activated, the restriction mode is deactivated and normal mode is selected when double-sided printing is completed Y times consecutively without interruption due to errors.

[0034] The control flow of the control unit 8 will be explained in more detail below with reference to Figure 4. First, when the printer 1 is started by the user for the first time (S1), the control unit 8 sets the values ​​of the number of consecutive error detections a, the number of consecutive error-free counts b, and the print counter c to 0 (S2). Next, the control unit 8 waits for processing according to this embodiment until the reception of image data from an external device or the reading of image data from a recording medium (hereinafter referred to as reception, etc.) begins (S3, NO). When the reception, etc. of image data begins (S3, YES), the control unit 8 performs the reception, etc. of image data (S4). Once the reception, etc. of image data is completed, the control unit 8 determines whether the image data indicates double-sided printing or not (double-sided printing or single-sided printing) (S5). If it is determined that it is not double-sided printing (S5, NO), the control unit 8 starts single-sided processing (single-sided printing) (S6). Next, the control unit 8 increments the print counter c in the memory 82 by 1 (c = c + 1) (S7). Then, once the processing on one side is complete (S8), the control unit 8 executes the process in S3.

[0035] In S5, if it is determined that double-sided printing is required (S5, YES), the control unit 8 determines whether the number of consecutive error detections a is greater than or equal to the threshold X (S9). If it is determined that a is greater than or equal to X (S9, YES), the control unit 8 starts double-sided processing (double-sided printing) in restricted mode (S10). On the other hand, if it is determined that a is not greater than or equal to X (S9, NO), the control unit 8 starts double-sided processing in normal mode (S11).

[0036] Next, the control unit 8 turns on the printing flag in memory 82 (S12). Next, if the control unit 8 was able to proceed with the duplex processing without interruption due to errors, it completes the process (S13). Next, the control unit 8 turns off the printing flag in memory 82 (S14). Next, the control unit 8 increments the print counter c in memory 82 by 2 (c=c+2) and increments the number of consecutive error-free counts b by 1 (b=b+1) (S15).

[0037] Next, the control unit 8 determines whether the number of consecutive error-free counts b has reached or exceeded the threshold Y (S16). If it determines that the number of consecutive error-free counts b has reached or exceeded the threshold Y (S16, YES), the control unit 8 resets the number of consecutive error detections a to 0 (S17). Then, the control unit 8 executes the process in S3. On the other hand, if it determines that the number of consecutive error-free counts b is not at or below the threshold Y (it is less than Y) (S16, NO), the control unit 8 executes the process in S3.

[0038] In contrast, if the printer is turned on after the execution of S12 and before the completion of double-sided printing in S13 (S18), the processes S21 to S23 are executed as an interrupt. Note that the processes from S18 onwards are executed when the control unit 8 checks the printing flag in memory 82 when the power is turned on, and only if the flag is on. If the printing flag is off after the power is turned on, the processes from S18 onwards are not performed, and other processes (such as normal processes after power-on) are executed.

[0039] In S21, the control unit 8 does not resume the double-sided processing, but interrupts the process and controls the recording unit 6 and the transport unit 7 to discharge the paper P being processed double-sided in the transport path 14 or the inversion transport path 15, the image recording area F, etc., to the output tray 5. Next, the control unit 8 turns off the printing flag (S22). Next, the control unit 8 increases the number of consecutive error detections a in memory 82 by 1 (a=a+1) and resets the number of consecutive error-free counts b in memory 82 to 0 (b=0) (S23). Then, the control unit 8 executes the process in S3.

[0040] Furthermore, if the upper cover 11a is opened after the execution of S12 but before the completion of double-sided printing in S13, the processes of S19 and S20 are executed as interrupt processing. The processes of S19 and S20 are executed when the control unit 8 checks the printing flag in memory 82 based on the detection result of the opening / closing sensor 41 indicating that the upper cover 11a has been opened, and the state is ON. If the printing flag is OFF when the detection result of the opening / closing sensor 41 indicates that the upper cover 11a has been opened, the processes of S19 and S20 are not performed, and other processes are executed.

[0041] In S19, the control unit 8 waits until the upper cover 11a is closed based on the detection result of the opening / closing sensor 41 (S19, NO). Once the upper cover 11a is closed (S19, YES), the control unit 8 determines whether or not duplex processing can be continued (S20). This determination is made based on, for example, whether or not there is a change in the position of the recording head 6 before and after the opening and closing of the upper cover 11a, or whether the paper P being processed duplex remains untouched in the transport path 14 or the inversion transport path 15, the image recording area F, etc. If it is determined that duplex processing can be continued (S20, YES), the control unit 8 executes the process in S13. This restarts duplex processing from the state before the opening of the upper cover 11a, and the processing for that case is executed. On the other hand, if it is determined that duplex processing cannot be continued (S20, NO), the control unit 8 executes the process in S21. This interrupts duplex processing, and the processing for that case is executed.

[0042] According to the first embodiment described above, if the duplex processing is interrupted frequently due to the printer 10 being turned off or the upper cover 11a being opened, the duplex processing will be executed in restricted mode. As a result, in duplex processing, the image formation operation on the back side is executed before the image formation operation on the front side is completed. Therefore, duplex processing in restricted mode is less likely to give the user the impression that the entire process is completed midway through, compared to duplex processing in normal mode, where image formation on the back side is performed only after the image formation on the front side is completed. Thus, actions that lead to interruption of the process by a user who mistakenly believes that the process is complete are suppressed. Consequently, usage patterns that frequently interrupt duplex processing are suppressed. In other words, usage patterns that could reduce functionality, durability, usability, etc. are suppressed. Furthermore, even if interruptions occur frequently due to some other usage pattern, the user can be made aware that the frequent interruptions are due to some cause by issuing the restricted mode. This leads users to avoid usage patterns that could frequently interrupt, and as a result, usage patterns that could reduce the functionality, durability, usability, etc. of the device are suppressed.

[0043] The condition for activating the restriction mode is that the double-sided processing is interrupted at a certain frequency. In this embodiment, this condition is defined as the number of consecutive error detections a being greater than or equal to a threshold X. Alternatively, this condition may be defined as the number of interruptions reaching a predetermined percentage of a predetermined number of double-sided processing cycles, or various other conditions that can evaluate the frequency of interruptions may be adopted.

[0044] Furthermore, in this embodiment, the area on the front surface that is subject to image formation is divided into two parts. After one of the two parts is formed on the front surface, image formation is performed on the back surface, and then the other part is formed on the front surface. Therefore, compared to the case where the entire image is formed on the front surface before image formation on the back surface is performed, it is less likely that the user will get the impression that the entire process is complete when image formation is performed on the front surface. As a result, actions that could lead to users interrupting the process due to mistakenly believing that the process is complete are suppressed.

[0045] Furthermore, in this embodiment, if there is a blank area in the image to be formed on the front surface, the boundary between the two divided parts is set to that blank area. Therefore, continuity between parts of the image is easily ensured.

[0046] Furthermore, in this embodiment, when activating the restriction mode, errors that could cause interruption of double-sided printing are assumed to be power-off operations and opening operations of the upper cover 11a during double-sided printing. Turning off the power in the middle of processing increases the risk of putting a strain on the printer 10. Also, opening the cover in the middle of processing exposes the internal components of the printer 10, increasing the risk of accidental operation. Moreover, interruption of printing can lead to the waste of consumables such as ink and paper P. These can cause a decrease in the functionality, durability, and usability of the printer 10. Therefore, by activating the restriction mode when processing interruptions due to these reasons occur frequently, usage patterns that could degrade the functionality of the printer 10 as described above are suppressed.

[0047] Furthermore, in this embodiment, when the number of consecutive error-free counts b exceeds a threshold Y, the duplex printing mode returns from restricted mode to normal mode. When processing is completed normally without interruption at a certain frequency, it can be considered that usage patterns that may degrade the functionality of the printer 10 tend to be avoided. In this case, normal mode is activated, allowing the user to recognize that the situation has improved. The condition for returning to normal mode may be that the number of times processing is completed appropriately in a predetermined number of duplex processes reaches a predetermined percentage, or various other conditions that can evaluate the frequency of appropriate processing completion may be adopted.

[0048] [Second Embodiment] The following describes a second embodiment according to another embodiment of the present invention. The main differences between this embodiment and the first embodiment are the content of the restriction mode and the use of memory 82' and control unit 8' instead of memory 82 and control unit 8. Other configurations are common to both the first and second embodiments. Therefore, the following will mainly describe the differences from the first embodiment, and the same reference numerals will be used for components common to both embodiments, with their descriptions omitted as appropriate.

[0049] The difference between memory 82' in this embodiment and memory 82 is that it stores two flags as printing flags: a double-sided printing flag to check whether double-sided printing has been interrupted, and a single-sided printing flag to check whether single-sided printing has been interrupted. Both the double-sided printing flag and the single-sided printing flag can selectively take on an on or off state, and are off by default.

[0050] The restriction mode according to this embodiment is a mode that prohibits the execution of duplex printing itself (corresponding to the "second mode" of the present invention). Specifically, each time an interruption of duplex or single-sided printing occurs due to an error, the number of consecutive error detections a stored in the flash memory of memory 82' is updated. Then, if a is greater than or equal to a predetermined threshold X, the control unit 8' takes the restriction mode and prohibits the execution of duplex printing, otherwise it performs duplex printing in normal mode. Errors that cause an interruption of duplex or single-sided printing are assumed to be power-off operations and opening operations of the upper cover 11a during duplex or single-sided printing.

[0051] The difference between the control unit 8' and the control unit 8 in this embodiment is that instead of executing the control shown in Figure 4, it executes the control shown in Figure 5. The control flow of the control unit 8' will be explained in more detail below with reference to the same figure. First, in S51 to S54, the control unit 8' executes the same process as S1 to S4 in Figure 4. Next, in S55, the control unit 8' determines whether the image data received in S54 indicates double-sided printing or not (double-sided or single-sided printing). If it is determined that it is not double-sided printing (S55, NO), the control unit 8' starts single-sided processing (single-sided printing) (S56). Next, the control unit 8' turns on the single-sided printing flag in memory 82' (S57). Next, the control unit 8' determines whether single-sided printing has been completed successfully (S58). This determination is made based on whether or not the processing was interrupted due to an error caused by either the power-off operation or the opening operation of the upper cover 11a during single-sided processing (specifically, whether the single-sided processing flag is on when the power is turned on or when the upper cover 11a is opened). If it is determined that single-sided processing has been completed successfully (S58, YES), the control unit 8' turns off the single-sided printing flag in memory 82' (S59). Next, the control unit 8' increments the print counter c in memory 82' by one (c=c+1) (S60). Then, the control unit 8' executes the process in S68. If it is determined that single-sided processing was interrupted due to an error (S58, NO), the control unit 8' performs appropriate processing such as ejecting any paper P remaining on the transport path, and then executes the process in S75.

[0052] In S55, if it is determined that double-sided printing is required (S55, YES), the control unit 8' determines whether the number of consecutive error detections a is greater than or equal to the threshold X (S61). If it is determined that a is greater than or equal to X (S61, YES), the control unit 8' enters restriction mode and, without starting the double-sided process, notifies the user of a warning that double-sided printing is prohibited (S62). This notification is displayed, for example, on a display provided on the housing 11 of the printer 10 or on a display mounted on a computer connected to the printer 10. Then, the control unit 8' executes the process in S53. On the other hand, if it is determined that a is not greater than or equal to X (S61, NO), the control unit 8' starts double-sided processing in normal mode (S63).

[0053] Next, the control unit 8' turns on the double-sided printing flag in memory 82' (S64). Next, if the control unit 8' was able to proceed with the double-sided processing without interruption due to errors, it completes the process (S65). Next, the control unit 8' turns off the double-sided printing flag in memory 82' (S66). Next, the control unit 8' increments the print counter c in memory 82' by 2 (c=c+2) (S67). Next, the control unit 8' increments the number of consecutive error-free counts b by 1 (b=b+1) (S68).

[0054] Next, the control unit 8' determines whether the number of consecutive error-free counts b has become equal to or greater than the threshold Y (S69). If it determines that the number of consecutive error-free counts b has become equal to or greater than the threshold Y (S69, YES), the control unit 8' resets the number of consecutive error detections a to 0 (S70). Then, the control unit 8' executes the process in S53. On the other hand, if it determines that the number of consecutive error-free counts b is not equal to or greater than the threshold Y (it is less than Y) (S69, NO), the control unit 8' executes the process in S53.

[0055] In contrast, if the printer is turned on after the execution of S64 and before the completion of double-sided printing in S65 (S71), the processes S74 to S76 are executed as an interrupt. Note that the processes from S71 onwards are executed when the control unit 8' checks the printing flag in memory 82' upon power-on, and only if the flag is on. If the printing flag is off after power-on, the processes from S71 onwards are not performed, and other processes (such as normal processes after power-on) are executed.

[0056] In S74, the control unit 8' does not resume the double-sided processing, but interrupts the process and controls the recording unit 6 and the transport unit 7 to discharge the paper P being processed double-sided in the transport path 14 or the inversion transport path 15, the image recording area F, etc., to the output tray 5. Next, the control unit 8' turns off both the double-sided printing flag and the single-sided printing flag (S75). Next, the control unit 8' increases the number of consecutive error detections a in memory 82' by 1 (a=a+1) and resets the number of consecutive no-error detections b in memory 82' to 0 (b=0) (S76). Then, the control unit 8' executes the process in S53.

[0057] Furthermore, if the upper cover 11a is opened after the execution of S64 but before the completion of double-sided printing in S65, the processes S72 and S73 are executed as interrupt processing. The processes S72 and S73 are executed when the control unit 8' checks the printing flag in memory 82' based on the detection result of the opening / closing sensor 41 indicating that the upper cover 11a has been opened, and the flag is turned on. If the printing flag is off when the detection result of the opening / closing sensor 41 indicates that the upper cover 11a has been opened, the processes S72 and S73 are not performed, and other processes are executed.

[0058] In S72, the control unit 8' waits until the upper cover 11a is closed based on the detection result of the opening / closing sensor 41 (S72, NO). Once the upper cover 11a is closed (S72, YES), the control unit 8' determines whether or not duplex processing can be continued (S73). This determination is made based on, for example, whether or not there is a change in the position of the recording head 6 before and after the opening and closing of the upper cover 11a, or whether the paper P being processed for duplex processing remains untouched in the transport path 14 or the inversion transport path 15, the image recording area F, etc. If it is determined that duplex processing can be continued (S73, YES), the control unit 8' executes the process in S65. As a result, duplex processing is resumed from the state before the opening of the upper cover 11a, and the processing for that case is executed. On the other hand, if it is determined that duplex processing cannot be continued (S73, NO), the control unit 8' executes the process in S74. As a result, duplex processing is interrupted, and the processing for that case is executed.

[0059] According to the second embodiment described above, in restricted mode, the execution of double-sided processing, which may cause processing interruptions, is prohibited. Therefore, by adopting restricted mode, usage patterns that frequently cause interruptions to double-sided processing are suppressed. In other words, usage patterns that may degrade functionality, durability, usability, etc., are suppressed. Furthermore, even if interruptions occur frequently due to some other usage pattern, the user can be made aware that the frequent interruptions are due to some cause by activating restricted mode. This leads users to tend to avoid usage patterns that may cause frequent interruptions, and as a result, usage patterns that may degrade the functionality, durability, usability, etc., of the device are suppressed.

[0060] [Third Embodiment] The following describes a third embodiment according to yet another embodiment of the present invention. The main difference in this embodiment from the first and second embodiments lies in the content of the restriction mode, while other configurations are common to the first and second embodiments and the third embodiment. For this reason, the following description will mainly focus on the restriction mode, and the same reference numerals will be used for components common to the first and second embodiments, with their descriptions omitted as appropriate.

[0061] The restriction mode according to the third embodiment includes a stepwise switching between the restriction mode according to the first embodiment (hereinafter referred to as restriction mode A) and the restriction mode according to the second embodiment (hereinafter referred to as restriction mode B). Specifically, when double-sided processing is performed multiple times in normal mode, if the processing is interrupted at a certain frequency due to a power-off operation or an opening operation of the upper cover 11a, the double-sided processing will be performed in restriction mode A (corresponding to the "first mode" of the present invention) instead of normal mode. Next, when double-sided processing in restriction mode A is performed multiple times, if the processing is interrupted at a certain frequency, the double-sided processing will be performed in restriction mode B (corresponding to the "second mode" of the present invention) instead of restriction mode A. On the other hand, if double-sided processing in restriction mode B is completed normally without interruption at a certain frequency, the mode of double-sided processing returns to restriction mode A. Also, if double-sided processing in restriction mode A is completed normally without interruption at a certain frequency, the mode of double-sided processing returns to normal mode. The determination of the above "certain frequency" may be performed in the same manner as in the first embodiment or in the same manner as in the second embodiment, based on the number of consecutive error detections a and the number of consecutive error non-detections b.

[0062] According to the third embodiment described above, if the double-sided processing in restriction mode A is interrupted at a certain frequency, restriction mode B is activated. Therefore, since the mode is switched to restrict double-sided processing in stages, usage patterns in which double-sided processing is frequently interrupted are more effectively suppressed.

[0063] [Fourth Embodiment] The following describes a fourth embodiment according to yet another embodiment of the present invention. The main difference between this embodiment and the first to third embodiments lies in the process of returning from the restricted mode to the normal mode; other configurations are common to the first to third embodiments and the fourth embodiment. For this reason, the following description will mainly focus on the restricted mode, and the same reference numerals will be used for components common to the first to third embodiments, with their descriptions omitted as appropriate.

[0064] In addition to the first to third embodiments, this embodiment includes a control unit that performs a process to return from restricted mode to normal mode in accordance with a predetermined instruction from an external source. The predetermined instruction may be directly input to the printer through an input unit such as a touch panel provided on the printer body, or it may be sent to the printer from an external device such as a computer connected to the printer via various communication interfaces or communication networks. When the control unit receives such a predetermined instruction from an external source while in control mode, it can return to normal mode accordingly.

[0065] <Variation> Although embodiments of the present invention have been described above with reference to the drawings, it should be understood that the specific configurations are not limited to these embodiments. The scope of the present invention is indicated by the claims rather than the above description of embodiments, and all modifications within the meaning and scope equivalent to the claims are included.

[0066] For example, in the restriction mode of the first or fourth embodiment described above, the image to be formed on the front side of the paper P is divided into two parts aligned vertically, with one part formed on the front side, and the other part formed on the front side after the image formation on the back side is completed. Alternatively, the area to be formed may be divided in other ways. For example, the area to be formed may be divided into two parts aligned horizontally. Alternatively, the area to be formed may be divided into a closed area contained within the entire area and other parts. Or, the area to be formed may be divided into a part consisting of pixels of a specific color and a part consisting of pixels of other colors. Furthermore, not only the image on the front side but also the image on the back side may be divided and formed on the paper P. For example, images may be formed on both sides of the paper P in the order of "form a part of the image on the front side → form a part of the image on the back side → form the rest of the image on the front side → form the rest of the image on the back side".

[0067] In addition, although the embodiments described above have described the application of the present invention to a printer 10, the invention is not limited thereto. The present invention may also be applied to other inkjet-type image forming apparatuses that eject ink from a head, such as multifunction printers and copiers. Furthermore, the present invention may be applied to laser-type image forming apparatuses or other image forming apparatuses that perform image recording processing by attaching toner to the paper P instead of ink using an inkjet method. [Explanation of symbols]

[0068] 6. Records Section 7. Conveying section 8 Control Unit P Paper

Claims

1. An image forming unit that performs an image forming operation to form an image on one of the image forming surfaces, which is the front or back surface, of a medium capable of forming images on both the front and back surfaces, A medium transport unit that transports the medium to the image forming unit so that one of the front or back surfaces of the medium becomes the image forming surface, and after the image forming operation is performed on one of the front or back surfaces of the transported medium, transports the medium to the image forming unit so that the other of the front or back surfaces of the medium becomes the image forming surface, It is equipped with a control unit, The control unit, It is possible to selectively perform a double-sided processing that controls the image forming unit and the media transport unit so that the image forming operation is performed on both the front and back surfaces of the medium, and a single-sided processing that controls the image forming unit and the media transport unit so that the image forming operation is performed on only one of the front or back surfaces of the medium. With respect to the double-sided processing, a normal mode is selected in which the image forming operation on the back side of the medium is performed after the image forming operation on the front side of the medium is completed, and a restricted mode is selected in which at least one of a first mode in which the image forming operation on the back side of the medium is performed before the image forming operation on the front side of the medium is completed, and then the image forming operation on the front side of the medium is completed, and a second mode in which the execution of the double-sided processing is prohibited. An image forming apparatus characterized by performing the double-sided processing multiple times, and taking the restriction mode when the interruption of each of the multiple double-sided processing processes occurs repeatedly with a certain frequency.

2. The image forming apparatus according to claim 1, characterized in that the first mode is a mode in which the image forming operation is performed on the back surface of the medium after the image forming operation is performed on the front surface of the medium, and then the image forming operation is performed on the front surface of the medium to form the remaining part of the image.

3. The control unit, The image forming apparatus according to claim 2, characterized in that it determines whether or not there is a blank area in the image over the entire lateral range of the image corresponding to the direction perpendicular to the transport direction of the medium by the medium transport unit, and if it is determined that there is a blank area, it performs the double-sided processing in the first mode such that a part of the image and the rest of the image are divided with the blank area as the boundary.

4. A main body housing the image forming unit and the media transport unit, The device includes a cover that can selectively take an open position that exposes the internal components of the main body to the outside and a closed position that shields the internal components from the outside, and is manually movable between the open position and the closed position. The image forming apparatus according to any one of claims 1 to 3, characterized in that the interruption of the process is caused by at least one of the following: the power being turned off and the cover moving from the closed position to the open position.

5. The control unit, The image forming apparatus according to any one of claims 1 to 4, characterized in that, after performing at least one of the double-sided processing and the single-sided processing multiple times while the restricted mode is in place, the normal mode is taken when a processing that was completed without interruption in those multiple processing sessions is repeated at a certain frequency.

6. The control unit, The image forming apparatus according to any one of claims 1 to 5, characterized in that when the restricted mode is in place, the normal mode is adopted when a predetermined instruction indicating a switch to the normal mode is given from an external source.

7. The control unit, The image forming apparatus according to any one of claims 1 to 6, characterized in that the first mode is adopted as the limiting mode when the interruption of each process in the multiple double-sided processes is repeated with a certain frequency, and further, the second mode is adopted as the limiting mode when the interruption of each process in the multiple double-sided processes in which the first mode is adopted is repeated with a certain frequency.

Images