Liquid ejection device and image forming device

Abstract

To reduce occurrence of liquid discharge failure.SOLUTION: A liquid discharge device includes liquid discharge parts 14Y, 14M, 14C and 14Bk for discharging a liquid to a sheet P, wherein the liquid discharge parts 14Y, 14M, 14C and 14Bk discharge the liquid to the sheet P when operation of the device stops due to abnormality.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a liquid ejection apparatus and an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art As an image forming apparatus such as a copying machine or a printer, there is known an inkjet type image forming apparatus that ejects liquid ink to form an image on a sheet.

[0003] In such an image forming apparatus, when an abnormality such as a sheet jam occurs, the operation of the image forming apparatus is generally stopped until the abnormality is resolved. If a sheet jam occurs, the user must remove the jammed sheet after the operation of the image forming apparatus is stopped. However, if the sheet comes into contact with a liquid ejection unit that ejects ink during the removal operation, the liquid ejection unit may become dirty or damaged.

[0004] To address this issue, Patent Document 1 (JP Patent Publication 2005-199606 A) proposes a method of moving the liquid ejection unit from the printing position to a retreated position when an abnormal stop of the image forming apparatus causes the sheet to stop at a position facing the liquid ejection unit (printing position). This makes it difficult for the sheet to come into contact with the liquid ejection unit during the removal process, thereby preventing the liquid ejection unit from becoming dirty or damaged. Summary of the Invention [Problem to be solved by the invention]

[0005] However, as described above, if the liquid ejection unit is left in that state for a long period of time after being moved to the retracted position, the liquid ejection port of the liquid ejection unit will dry out, which may result in poor liquid ejection when the liquid ejection unit is subsequently restarted. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a liquid ejection unit that ejects liquid onto a sheet.a cap member that covers the liquid ejection unit; and a conveying path along which the sheet is conveyed between the liquid ejection unit and the cap member. The liquid ejection device is characterized in that the liquid ejection section ejects liquid onto the sheet when operation of the device is stopped due to an abnormality. Effect of the Invention

[0007] According to the present invention, the occurrence of liquid ejection defects can be reduced. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] 1 is a schematic configuration diagram of a liquid ejection device according to an embodiment of the present invention. [Diagram 3] FIG. 4 is a diagram showing a state in which the cap member is separated from the liquid ejection head. [Figure 4] FIG. 4 is a diagram showing a state in which the cap member covers the liquid ejection head. [Diagram 5] FIG. 13 is a diagram showing a state in which a sheet of paper is interposed between the cap member and the liquid ejection head and is stationary. [Figure 6] FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention. [Figure 7] 5A and 5B are diagrams illustrating an example of a state in which a paper sheet is detected by a paper sensor. [Figure 8] 13A and 13B are diagrams illustrating another example of a state in which a sheet is detected by the sheet sensor. [Figure 9] 13 is a diagram showing yet another example of a state in which a sheet is detected by the sheet sensor; FIG. [Figure 10] 13A and 13B are diagrams illustrating another example of a state in which a sheet is detected by the sheet sensor. [Figure 11] 13 is a diagram showing yet another example of a state in which a sheet is detected by the sheet sensor; FIG. [Figure 12] FIG. 2 is a block diagram of a control system in the first embodiment of the present invention. [Figure 13] FIG. 2 is a diagram showing an openable and closable cover provided on the image forming apparatus main body. [Figure 14]4 is a flowchart showing a control method in the first embodiment of the present invention. [Figure 15] 10 is a flowchart showing a control method in a second embodiment of the present invention. [Figure 16] 10A and 10B are diagrams illustrating an example of an operation for retracting a sheet from between a cap member and a liquid ejection head. [Figure 17] 10A and 10B are diagrams illustrating another example of the operation of retracting the paper from between the cap member and the liquid ejection head. [Figure 18] FIG. 13 is a diagram showing a configuration of a third embodiment of the present invention. [Figure 19] 10 is a flowchart showing a control method according to a third embodiment of the present invention. [Figure 20] FIG. 13 is a diagram illustrating the configuration and operation of a fourth embodiment of the present invention. [Figure 21] FIG. 13 is a diagram illustrating the configuration and operation of a fourth embodiment of the present invention. [Figure 22] FIG. 13 is a diagram illustrating the configuration and operation of a fifth embodiment of the present invention. [Figure 23] FIG. 13 is a diagram illustrating the configuration and operation of a fifth embodiment of the present invention. [Figure 24] 13 is a flowchart showing a control method in the sixth embodiment of the present invention. [Diagram 25] FIG. 13 is a diagram showing another example of a line-type liquid ejection head. [Figure 26] 13 is a flowchart showing a control method in a seventh embodiment of the present invention. [Figure 27] FIG. 13 is a diagram showing a configuration of an eighth embodiment of the present invention. [Figure 28] FIG. 13 is a diagram showing a configuration of an eighth embodiment of the present invention. [Figure 29] FIG. 13 is a diagram showing a configuration of a ninth embodiment of the present invention. [Diagram 30] FIG. 1 is a plan view of a liquid ejection device including a serial type liquid ejection head. [Diagram 31] FIG. 13 is a diagram showing an example of another image forming apparatus to which the present invention can be applied. [Diagram 32]FIG. 13 is a diagram showing an example of still another image forming apparatus to which the present invention can be applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described below with reference to the accompanying drawings. In each drawing for explaining the present invention, components such as members and components having the same function or shape are given the same reference numerals as far as they can be distinguished, and the description thereof will be omitted after the first description.

[0010] FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention.

[0011] 1, an image forming apparatus 100 according to this embodiment includes a document transport device 1, an image reading device 2, an image forming section 3, a sheet supply device 4, a cartridge mounting section 5, a sheet discharge section 6, and a sheet placement section 7. In addition, a sheet alignment device 200 is disposed next to the image forming apparatus 100.

[0012] The document transport device 1 is a device that separates documents one by one from a document tray 11 and transports them toward a contact glass 13 of an image reading device 2. The document transport device 1 includes a plurality of transport rollers and the like as a document transport means for transporting the documents.

[0013] The image reading device 2 is a device that reads an image of an original placed on the contact glass 13 or an image of an original passing over the contact glass 13. The image reading device 2 includes an optical scanning unit 12 as an image reading section. The optical scanning unit 12 includes a light source that irradiates light onto the original placed on the contact glass 13, and a CCD (charge-coupled device) or the like as an image reading means that reads an image from the light reflected from the original. A contact image sensor (CIS) or the like may also be used as the image reading means.

[0014] The image forming unit 3 is a liquid ejection device that ejects liquid ink onto a sheet to form an image. The liquid ejection device has a liquid ejection head 14 as a liquid ejection unit. The liquid ejection head 14 ejects ink onto a sheet fed from the sheet supply device 4, thereby forming an image on the paper.

[0015] A plurality of ink cartridges 15Y, 15M, 15C, and 15Bk are removably mounted in the cartridge mounting section 5. Each of the ink cartridges 15Y, 15M, 15C, and 15Bk is filled with ink of a different color, such as yellow, magenta, cyan, and black. The ink in each ink cartridge is supplied to the liquid ejection head 14 by a supply pump.

[0016] The sheet supply device 4 includes a paper feed cassette 16 as a sheet storage section, a paper feed roller 17 as a sheet feeding means, and a separation pad 18 as a sheet separating means. Each paper feed cassette 16 stores a plurality of sheets of paper P, so-called cut paper, that have been cut to a predetermined size in the paper conveying direction (sheet conveying direction), such as A4 size or B4 size. The paper feed roller 17 cooperates with the separation pad 18 to separate and send out the paper P in the paper feed cassette 16 one sheet at a time.

[0017] The sheet discharge section 6 has a pair of discharge rollers 19 as a sheet transport means for transporting paper. The pair of discharge rollers 19 transports paper while nipping it by rotating.

[0018] The sheet placement section 7 has a paper discharge tray 20 on which paper discharged outside the apparatus is placed. In this embodiment, the paper discharge tray 20 is provided between the image reading device 2 and the image forming section 3, and a so-called internal paper discharge configuration is adopted. The paper discharge tray 20 may also be provided in an external space, such as on the top surface of the image forming apparatus main body.

[0019] The sheet alignment device 200 is a post-processing device that aligns the paper sheets sent from the image forming device 100. In addition to the sheet alignment device 200, other post-processing devices such as a staple processing device that staples the paper sheets or a punch processing device that punches holes in the paper sheets may be provided.

[0020] The operation of the image forming apparatus according to this embodiment will be described with reference to FIG.

[0021] When an instruction to start a printing operation is given, a sheet P is fed from one of the multiple sheet feed cassettes 16. More specifically, as the sheet feed roller 17 rotates, the topmost sheet P stored in the sheet feed cassette 16 is separated from the other sheets (sheet stack) by the sheet feed roller 17 and the separation pad 18 and sent out.

[0022] When the paper P is transported to a horizontal transport path 80 facing the image forming unit 3, an image is formed on the paper P by the image forming unit 3. In detail, the ejection operation of the liquid ejection head 14 is controlled according to image information of the original read by the image reading device 2 or print information instructed to be printed from a terminal, and ink is ejected onto the image forming surface (upper surface) of the paper P to form an image. Note that the image formed on the paper P may be a meaningful image such as a character or a figure, or may be a pattern that does not have any meaning in itself.

[0023] When double-sided printing is performed, the paper P is guided to the reversing conveying path 81 by conveying the paper P in the opposite direction downstream of the image forming unit 3 in the paper conveying direction. More specifically, after the rear end of the paper P passes through the first path switching means 74 arranged downstream of the image forming unit 3 in the paper conveying direction, the first path switching means 74 switches the conveying path to the reversing conveying path 81 and the paper P is conveyed in the opposite direction. As a result, the paper P is guided to the reversing conveying path 81. Then, as the paper P passes through the reversing conveying path 81, the paper P is conveyed again to the image forming unit 3 in an inverted state, and an image is formed on the back side of the paper P by the same operation of the image forming unit 3 as described above.

[0024] The paper P on which the image has been formed is selectively guided from a conveyance path 82 leading to the sheet discharge section 6 to a conveyance path 83 leading to the sheet alignment device 200 by a second path switching means 75 located downstream of the first path switching means 74 in the paper conveyance direction. When the paper P is guided to the conveyance path 82 leading to the sheet discharge section 6, the paper P is discharged to the paper discharge tray 20 by a pair of paper discharge rollers 19. On the other hand, when the paper P is guided to the conveyance path 83 leading to the sheet alignment device 200, the paper P is conveyed to the sheet alignment device 200, where the paper P is aligned and placed. This completes a series of printing operations.

[0025] In the image forming apparatus 100 according to the present embodiment, in order to prevent ejection defects of the liquid ejection head 14 caused by drying of ink and to protect the liquid ejection head 14, as shown in Fig. 1, a plurality of cap members 55 are provided below the liquid ejection head 14. The configuration of the cap members 55 will be described below.

[0026] 2, the liquid ejection device (image forming unit 3) according to this embodiment includes four types of liquid ejection heads 14Y, 14M, 14C, and 14Bk that eject ink of different colors, namely, yellow, magenta, cyan, and black. The liquid ejection heads 14Y, 14M, 14C, and 14Bk are so-called line-type liquid ejection heads that are arranged alternately in a paper transport direction (sheet transport direction) A and a paper width direction (sheet width direction) B that intersects with the paper transport direction A. The liquid ejection heads 14Y, 14M, 14C, and 14Bk constitute head arrays 24Y, 24M, 24C, and 24Bk that are integrated for each color of ink to be ejected. The head arrays 24Y, 24M, 24C, and 24Bk each include a base member 44Y, 44M, 44C, and 44Bk, and a plurality of liquid ejection heads 14Y, 14M, 14C, and 14Bk provided on the base members 44Y, 44M, 44C, and 44Bk.

[0027] The cap members 55Y, 55M, 55C, and 55Bk are arranged alternately in the paper transport direction A and the paper width direction B in correspondence with the liquid ejection heads 14Y, 14M, 14C, and 14Bk. The cap members 55Y, 55M, 55C, and 55Bk constitute cap units 56Y, 56M, 56C, and 56Bk that are integrally provided for the respective colors of the corresponding liquid ejection heads 14Y, 14M, 14C, and 14Bk. The cap units 56Y, 56M, 56C, and 56Bk can be raised and lowered individually. Therefore, the cap members 55Y, 55M, 55C, and 55Bk can approach and move away from the respective liquid ejection heads 14Y, 14M, 14C, and 14Bk independently for the respective colors.

[0028] A transport guide 30 for guiding the paper P is disposed between each of the cap members 55Y, 55M, 55C, and 55Bk and each of the liquid ejection heads 14Y, 14M, 14C, and 14Bk. The transport guide 30 is provided with a plurality of insertion holes 31 through which each of the cap members 55Y, 55M, 55C, and 55Bk is inserted. Each of the cap members 55Y, 55M, 55C, and 55Bk rises to pass through the corresponding insertion hole 31 and approach each of the liquid ejection heads 14Y, 14M, 14C, and 14Bk.

[0029] The operation of each cap member 55Y, 55M, 55C, and 55Bk will be described below with reference to Figures 3 and 4. Note that in Figures 3 and 4, the liquid ejection heads 14Y, 14M, 14C, and 14Bk and the cap members 55Y, 55M, 55C, and 55Bk are simplified and illustrated one for each color. The conveying guide 30 is also omitted from the illustration.

[0030] 3 shows a state where the cap members 55Y, 55M, 55C, and 55Bk are spaced apart from the liquid ejection heads 14Y, 14M, 14C, and 14Bk. In this state, the liquid ejection heads 14Y, 14M, 14C, and 14Bk are not covered by the cap members 55Y, 55M, 55C, and 55Bk, and the liquid ejection ports (nozzles) of the liquid ejection heads 14Y, 14M, 14C, and 14Bk are open. Therefore, in this state, when the paper P is transported below the liquid ejection heads 14Y, 14M, 14C, and 14Bk, the liquid ejection heads 14Y, 14M, 14C, and 14Bk can eject ink onto the transported paper P to form an image.

[0031] 4 shows a state in which the cap members 55Y, 55M, 55C, and 55Bk are close to the liquid ejection heads 14Y, 14M, 14C, and 14Bk, and the liquid ejection heads 14Y, 14M, 14C, and 14Bk are covered by the cap members 55Y, 55M, 55C, and 55Bk. When printing is not performed, the liquid ejection heads 14Y, 14M, 14C, and 14Bk are covered by the cap members 55Y, 55M, 55C, and 55Bk. This protects the liquid ejection heads 14Y, 14M, 14C, and 14Bk, and prevents the liquid ejection heads 14Y, 14M, 14C, and 14Bk from drying out, thereby reducing the occurrence of liquid ejection defects that make it difficult to eject ink during subsequent printing.

[0032] However, when the normal operation of the image forming apparatus such as the image forming operation is temporarily stopped (interrupted) due to an abnormality such as a paper jam, a paper shortage, or the cover of the image forming apparatus body being opened during printing (meaning a state in which the operation based on the print instruction from the user cannot be continued), the cap members 55Y, 55M, 55C, and 55Bk may not be able to cover the liquid ejection heads 14Y, 14M, 14C, and 14Bk. In other words, when the image forming operation of the image forming apparatus is temporarily stopped, the transportation of the paper also stops, so that the paper P may remain stationary between the cap members 55Y, 55M, 55C, and 55Bk and the liquid ejection heads 14Y, 14M, 14C, and 14Bk as shown in FIG. 5. In this case, the cap members 55Y, 55M, 55C, and 55Bk cannot approach the liquid ejection heads 14Y, 14M, 14C, and 14Bk. If the image forming apparatus is left in this state, the liquid ejection heads 14Y, 14M, 14C, and 14Bk cannot be covered by the cap members 55Y, 55M, 55C, and 55Bk, and therefore there is a risk of liquid ejection problems occurring when the apparatus is subsequently restarted.

[0033] Therefore, in the image forming apparatus according to this embodiment, the following measures are taken to reduce the occurrence of such liquid ejection defects.

[0034] A first embodiment of the present invention will be described with reference to Figures 6 to 14. In the following description, the reference characters Y, M, C, and Bk indicating the colors of ink corresponding to the liquid ejection heads 14Y, 14M, 14C, and 14Bk and the cap members 55Y, 55M, 55C, and 55Bk will be omitted unless necessary.

[0035] 6, in the first embodiment of the present invention, two paper sensors 64, 65 are disposed upstream and downstream in the paper transport direction A of each cap member 55 and each liquid ejection head 14 as paper detection means for detecting the presence or absence of paper. Each paper sensor 64, 65 is, for example, a reflective or transmissive optical sensor. When paper is present at the detection position of each paper sensor 64, 65, the light receiving portion detects that light irradiated from the light projecting portion of each paper sensor 64, 65 has been reflected or blocked by the paper, and thus the presence of paper is detected by each paper sensor 64, 65.

[0036] Specifically, there are five cases in which the presence of paper is detected, as shown in each of FIGS.

[0037] 7 shows a case where the paper P is entirely interposed between each cap member 55 and each liquid ejection head 14. In this case, the paper P is stationary at the detection positions of both the paper sensors 64, 65, so that the presence of the paper P is detected by both the paper sensors 64, 65.

[0038] 8 shows a case where at least a portion of the paper P on the front end Pa side is interposed between a part of each cap member 55 and a part of each liquid ejection head 14. In this case, only the upstream paper sensor 64 (hereinafter referred to as the "first paper sensor") detects the presence of the paper P.

[0039] 9 shows a case where at least a portion of the paper P on the rear end Pb side is interposed between a part of each cap member 55 and a part of each liquid ejection head 14. In this case, only the downstream paper sensor 65 (hereinafter referred to as the "second paper sensor") detects the presence of the paper P.

[0040] 10 shows a case where the front end Pa of the paper P is located downstream of the detection position of the first paper sensor 64 and upstream of the gap between each cap member 55 and each liquid ejection head 14. In this case, the presence of the paper P is detected only by the first paper sensor 64, but the paper P is not interposed between each cap member 55 and each liquid ejection head 14.

[0041] 11 shows a case where the rear end Pb of the paper P is located upstream of the detection position of the second paper sensor 65 and downstream of the gap between each cap member 55 and each liquid ejection head 14. In this case, the presence of the paper P is detected only by the second paper sensor 65, but the paper P is not interposed between each cap member 55 and each liquid ejection head 14.

[0042] FIG. 12 is a block diagram of a control system in this embodiment.

[0043] 12, the image forming apparatus according to this embodiment includes a control unit 40 that controls the driving of each liquid ejection head 14 and each cap member 55. The control unit 40 is, for example, a microcomputer having a RAM (Random Access Memory) and a ROM (Read Only Memory). The control unit 40 controls the driving of each liquid ejection head 14 and each cap member 55 based on the detection results of a first paper sensor 64 and a second paper sensor 65.

[0044] The image forming apparatus according to the present embodiment also includes a notification unit 41 that notifies a user or an operator such as a serviceman of a request to remove the jammed paper. When the control unit 40 determines that a paper jam has occurred based on the detection results of the paper sensors 64, 65, the notification unit 41 notifies a request to remove the jammed paper. The notification unit 41 is, for example, a display unit of an operation panel provided on the image forming apparatus main body. The notification to the user may be by means of a screen display, sound, light, or the like. Furthermore, the notification unit 41 may output to a device (an external device such as a PC or a tablet) used by the user or an operator such as a serviceman.

[0045] The image forming apparatus according to this embodiment also includes a cover 50 (see FIG. 13) that is provided on the image forming apparatus body in an openable and closable manner. This cover 50 is opened when an operator performs recovery work such as removing jammed paper, thereby making it possible to expose the inside of the image forming apparatus. In this embodiment, the control unit 40 controls the driving of each liquid ejection head 14 and each cap member 55 based on the opening and closing operation of the cover 50.

[0046] Next, a method for controlling the cap member and the liquid ejection head according to the present embodiment will be described with reference to the flowchart shown in FIG.

[0047] 14, when a printing operation is interrupted due to an abnormality such as a paper jam after an image creation request is made, first, each paper sensor 64, 65 detects the presence or absence of paper (Step 1 in FIG. 14). As a result, when at least one of each paper sensor 64, 65 detects the presence of paper ("YES" in Step 1 in FIG. 14), the control unit 40 determines that paper is present between the cap member 55 and the liquid ejection head 14.

[0048] Specifically, the control unit 40 confirms the presence of a sheet of paper in the five cases shown in the above-mentioned FIGS. 7, 8, 9, 10, and 11. That is, when both the first sheet sensor 64 and the second sheet sensor 65 detect the presence of the sheet of paper P, the control unit 40 determines that the sheet of paper P is entirely interposed between each cap member 55 and each liquid ejection head 14 (the state shown in FIG. 7). When only the first sheet sensor 64 detects the presence of the sheet of paper P, the control unit 40 determines that at least a portion of the sheet of paper P on the front end Pa side is interposed between some of the cap members 55 and some of the liquid ejection heads 14 (the state shown in FIG. 8). In this embodiment, even if the state shown in FIG. 10 is reached, it is determined to be the same as that shown in FIG. When only the second sheet sensor 65 detects the presence of the sheet of paper P, the control unit 40 determines that at least a portion of the sheet of paper P on the rear end Pb side is interposed between some of the cap members 55 and some of the liquid ejection heads 14 (the state shown in FIG. 9). In this embodiment, even if the state shown in FIG. 11 exists, it is determined to be the same state as that in FIG.

[0049] Then, if the control unit 40 determines that paper is interposed between the cap member 55 and at least a portion of the liquid ejection head 14 ("YES" in Step 1 of Figure 14), the notification unit 41 notifies the operator of a request to remove the paper (Step 2 of Figure 14).

[0050] On the other hand, when the control unit 40 determines that no paper is interposed between each cap member 55 and each liquid ejection head 14 ("NO" in Step 1 of FIG. 14), the control unit 40 moves each cap member 55 (Step 3 of FIG. 14). That is, when no paper is interposed between each cap member 55 and each liquid ejection head 14, each cap member 55 can be moved toward each liquid ejection head 14, so that each cap member 55 is moved toward each liquid ejection head 14 and each liquid ejection head 14 is covered by each cap member 55.

[0051] Furthermore, in this case, in addition to the operation of covering each liquid ejection head 14 with each cap member 55, a paper removal request is also issued by the notification unit 41 (Step 4 in FIG. 14). That is, when the image formation operation is interrupted due to an abnormality, even if there is no paper between each cap member 55 and each liquid ejection head 14, there is a possibility that the paper is jammed in another location, so a paper removal request is issued by the notification unit 41.

[0052] On the other hand, as described above, if the control unit 40 determines that paper is interposed between the cap member 55 and at least a part of the liquid ejection head 14 (if "YES" in Step 1 of Figure 14), and further, the notification unit 41 notifies a request to remove the paper (Step 2 of Figure 14), the control unit 40 checks whether the cover 50 of the device main body has been opened within a specified time T after the abnormal stop (Step 5 of Figure 14).

[0053] If the cover 50 is opened within the predetermined time T (Step 5 in FIG. 14: YES), the control unit 40 further checks whether the cover 50 is closed (Step 6 in FIG. 14). As a result, if the cover 50 is closed (Step 6 in FIG. 14: YES), the paper sensors 64, 65 again detect the presence or absence of paper (Step 7 in FIG. 14).

[0054] Then, if the presence of paper is not detected by each paper sensor 64, 65 ("NO" in Step 7 of Figure 14), it is assumed that the operator has removed the paper from between each cap member 55 and each liquid ejection head 14, and each cap member 55 is moved toward each liquid ejection head 14, covering each liquid ejection head 14 with each cap member 55 (Step 8 of Figure 14).

[0055] On the other hand, if at least one of the paper sensors 64, 65 detects the presence of paper even after the cover 50 is closed ("YES" in Step 7 of FIG. 14), the paper is deemed not to have been removed and the notification unit 41 again notifies the user of a request to remove the paper (Step 2 of FIG. 14).

[0056] Furthermore, if the cover 50 has not been opened even after the predetermined time T has elapsed (if "NO" in Step 5 of FIG. 14), each liquid ejection head 14 ejects ink (Step 9 of FIG. 14). That is, in this case, it is considered that the cover 50 has not yet been opened even after the predetermined time T has elapsed, and the paper has not been removed from between each cap member 55 and each liquid ejection head 14. In this case, since each cap member 55 cannot be moved toward each liquid ejection head 14, ink is ejected from each liquid ejection head 14 to prevent each liquid ejection head 14 from drying out.

[0057] At this time, the ejected ink adheres to the paper or the cap member. For example, as shown in Fig. 7, when the paper P is entirely interposed between each cap member 55 and each liquid ejection head 14, the ink ejected from all the liquid ejection heads 14Y, 14M, 14C, and 14Bk adheres to the paper P interposed.

[0058] 8, when the paper P is interposed between each of the cap members 55Bk, 55C, 55M and the liquid ejection heads 14Bk, 14C, 14M, the ink ejected from the first three liquid ejection heads 14Bk, 14C, 14M adheres to the paper P. In this case, the ink ejected from the fourth liquid ejection head 14Y from the upstream in the paper transport direction adheres to the fourth cap member 55Y from the upstream in the paper transport direction (passing through the insertion hole 31 of the transport guide 30) since there is no paper P between them.

[0059] 9, when a sheet of paper P is interposed between the third and fourth cap members 55M, 55Y from the upstream in the paper transport direction and the liquid ejection heads 14M, 14Y, the ink ejected from the third and fourth liquid ejection heads 14M, 14Y adheres to the sheet of paper P. In this case, the ink ejected from the first and second liquid ejection heads 14Bk, 14C from the upstream in the paper transport direction adheres to the first and second cap members 55Bk, 55C from the upstream in the paper transport direction (passing through the insertion hole 31 of the transport guide 30) since there is no paper P between them.

[0060] Also, as shown in Figures 10 and 11, when paper P is not interposed between each cap member 55 and each liquid ejection head 14, ink ejected from all of the liquid ejection heads 14Bk, 14C, 14M, and 14Y passes through the insertion hole 31 of the transport guide 30 and adheres to each of the cap members 55Bk, 55C, 55M, and 55Y.

[0061] In this way, after each liquid ejection head 14 ejects a predetermined amount of ink or for a predetermined time, the ejection of ink stops (Step 10 in FIG. 14), and the control unit again checks whether the cover 50 is open (Step 5 in FIG. 14). If the cover 50 is not opened after that, the ejection of ink from each liquid ejection head 14 is repeated every time the predetermined time T has elapsed.

[0062] As described above, in this embodiment, even if paper is left between the cap members 55 and the liquid ejection heads 14, ink is ejected from each liquid ejection head 14 at predetermined time intervals T, thereby preventing each liquid ejection head 14 from drying out. This reduces the occurrence of liquid ejection defects thereafter. Furthermore, even if paper is not present between each cap member 55 and each liquid ejection head 14 (as shown in FIG. 10 or 11) when the image forming apparatus is stopped due to an abnormality, ink is ejected from each liquid ejection head 14 at predetermined time intervals T after the image forming apparatus is stopped, thereby preventing each liquid ejection head 14 from drying out.

[0063] In addition, when at least one of the paper sensors 64, 65 detects the presence of paper, it may be possible to determine whether paper is interposed between each cap member 55 and each liquid ejection head 14 (the state of FIG. 7, FIG. 8, or FIG. 9) or not (the state of FIG. 10 or FIG. 11). For example, if the transport roller upstream of the first paper sensor 64 has an encoder that detects the number of rotations, it is possible to obtain the transport distance of the paper from the number of rotations detected by the encoder. In this case, the stop position of the paper can be specified by grasping the transport distance of the paper after the front end of the paper is detected by the first paper sensor 64. Therefore, in a configuration including such an encoder, it is possible to determine whether paper is interposed between each cap member 55 and each liquid ejection head 14, so that when it is determined that paper is not interposed between each cap member 55 and each liquid ejection head 14 (the state of FIG. 10 or FIG. 11), the cap member 55 may be moved to cover the liquid ejection head 14 with the cap member 55 (Step 3 of FIG. 14).

[0064] The amount of ink ejected from the liquid ejection head 14 should be sufficient to prevent the liquid ejection ports (nozzles) from drying out, and is preferably less than the amount of ink ejected during image formation. The predetermined time T is not limited to the time after the image forming apparatus has stopped due to an abnormality (this also applies to each of the following embodiments). For example, it may be the time after the execution flow from Step 1 onwards in Fig. 14 is started after the image forming apparatus has stopped due to an abnormality, or the time after a paper removal request is notified (Step 2 in Fig. 14).

[0065] Hereinafter, an embodiment of the present invention different from the above-mentioned embodiment (first embodiment) will be described. In the following description, the differences from the above-mentioned embodiment will be mainly described, and the other parts will be omitted as they are basically the same in configuration.

[0066] FIG. 15 is a flowchart showing a method for controlling a cap member and a liquid ejection head according to the second embodiment of the present invention.

[0067] The control method shown in FIG. 15 differs from the first embodiment described above in that there is control for moving the paper interposed between the cap member 55 and the liquid ejection head 14.

[0068] In the second embodiment, when the image forming operation is temporarily stopped (interrupted) due to an abnormality, the paper is detected by the paper sensors 64, 65 as in the first embodiment (Step 1 in FIG. 15). At this time, if only the first paper sensor 64 detects the paper P (if "YES" is selected in Step 2 in FIG. 15), the control unit 40 determines that at least the portion of the paper P on the front end Pa side is interposed between the cap member 55 and the liquid ejection head 14 (the state shown in FIG. 8) (even if the state shown in FIG. 10 is selected, the state is determined to be the same as that shown in FIG. 8). In this case, in order to move the paper P away from between the cap member 55 and the liquid ejection head 14, the paper P is moved in the opposite direction to the paper transport direction A as shown in FIG. 16 (Step 3 in FIG. 15). Here, the reason why the paper P is moved in the opposite direction rather than the paper transport direction A is that the distance for moving the paper P away is often shorter in this case. However, the present invention is not limited to this, and the paper P may be moved in the paper transport direction A.

[0069] Furthermore, when the detection result of the paper sensors 64, 65 indicates that only the second paper sensor 65 detects a paper (when "YES" is selected in Step 4 of FIG. 15), the control unit 40 determines that at least the rear end Pb side of the paper P is interposed between the cap member 55 and the liquid ejection head 14 (the state shown in FIG. 9) (even if the state shown in FIG. 11 is selected, the state is determined to be the same as that shown in FIG. 9). In this case, in order to move the paper P away from between the cap member 55 and the liquid ejection head 14, the paper P is moved in the paper transport direction A as shown in FIG. 17 (Step 5 of FIG. 15). Here, the paper P is moved in the paper transport direction A because the distance by which the paper P is moved away is often shorter in this case. However, this is not limited to the above, and the paper P may be moved in the opposite direction to the paper transport direction A when the front end of the paper P is caught in the transport path.

[0070] Furthermore, when the detection results of the paper sensors 64, 65 show that both the first paper sensor 64 and the second paper sensor 65 detect paper ("NO" in Step 4 of FIG. 15), the control unit 40 determines that the paper P is entirely interposed between each cap member 55 and each liquid ejection head 14 (the state shown in FIG. 7). In this case, the paper P may be moved in the paper transport direction A, or may be moved in the opposite direction to the paper transport direction A (Step 6 of FIG. 15).

[0071] Furthermore, if the result of detection by the paper sensors 64, 65 shows that neither the first paper sensor 64 nor the second paper sensor 65 detects a paper sheet ("NO" in Step 1 of FIG. 15), the control unit 40 determines that the paper sheet P is not interposed between the cap members 55 and the liquid ejection heads 14. In this case, as in the first embodiment, the cap members 55 can move toward the liquid ejection heads 14, so that the cap members 55 move toward the liquid ejection heads 14 and cover the liquid ejection heads 14 (Step 7 of FIG. 15). Furthermore, in this case, the notification unit 41 also notifies a paper removal request (Step 8 of FIG. 15).

[0072] On the other hand, as described above, when the paper P is moved to evacuate the paper interposed between the cap member 55 and the liquid ejection head 14, the control unit 40 checks whether the paper has been evacuated from between the cap member 55 and the liquid ejection head 14, and the paper is detected by the first paper sensor 64 and the second paper sensor 65 (Step 9 in Figure 15).

[0073] As a result, when neither of the paper sensors 64, 65 detects the presence of paper (when "NO" is determined in Step 9 of FIG. 15), the control unit 40 determines that the paper has been retracted from between the capping members 55 and the liquid ejection heads 14. In this case, since each of the capping members 55 can be moved toward each of the liquid ejection heads 14, each of the capping members 55 is moved toward each of the liquid ejection heads 14, and each of the liquid ejection heads 14 is covered by each of the capping members 55 (Step 10 of FIG. 15).

[0074] On the other hand, if at least one of the paper sensors 64, 65 detects paper (if "YES" in Step 9 of Figure 15), it is determined that the paper has not been removed from between the cap member 55 and the liquid ejection head 14, and the notification unit 41 notifies a request to remove the paper (Step 11 of Figure 15).

[0075] Thereafter, the control unit 40 checks whether the cover 50 is opened within a predetermined time T after the abnormal stop (Step 12 in FIG. 15).

[0076] If the cover 50 is opened within the predetermined time T ("YES" in Step 12 of FIG. 15), the control unit 40 further checks whether the cover 50 is closed (Step 13 of FIG. 15). If the cover 50 is closed ("YES" in Step 13 of FIG. 15), the paper sensors 64, 65 again detect the presence or absence of paper (Step 9 of FIG. 15).

[0077] As a result, if the presence of paper is not detected by each paper sensor 64, 65 ("NO" in Step 9 of Figure 15), it is assumed that the operator has removed the paper from between each cap member 55 and each liquid ejection head 14, and each cap member 55 is moved toward each liquid ejection head 14, covering each liquid ejection head 14 with each cap member 55 (Step 10 of Figure 15).

[0078] On the other hand, if at least one of the paper sensors 64, 65 detects the presence of paper even after the cover 50 is closed (if "NO" in Step 9 of FIG. 15), it is determined that the paper has not been removed, and the notification unit 41 repeatedly notifies the user of a request to remove the paper until the paper is removed (Step 11 of FIG. 15).

[0079] Furthermore, if the cover 50 is not opened after the predetermined time T has elapsed (if "NO" in Step 12 in FIG. 15), ink is ejected from each liquid ejection head 14 in the same manner as in the first embodiment (Step 14 in FIG. 15) to prevent each liquid ejection head 14 from drying out. At this time, ink is ejected from the liquid ejection head 14 onto the paper in areas where paper is interposed between the cap member 55 and the liquid ejection head 14, and ink is ejected from the liquid ejection head 14 onto the cap member 55 in areas where paper is not interposed.

[0080] Thereafter, the ejection of ink is stopped (Step 15 in FIG. 15), and the control unit 40 checks again whether the cover 50 is open (Step 12 in FIG. 15). If the cover 50 is not opened, the ejection of ink from each liquid ejection head 14 is repeated every time a predetermined time T has elapsed.

[0081] As described above, in this embodiment, even if the cap member 55 and the liquid ejection head 14 are stopped with paper between them, the paper can be moved and automatically evacuated. This reduces the labor of the worker to remove the paper, and the worker's hands are less likely to get dirty from the paper removal work. In addition, if the paper cannot be automatically evacuated, a paper removal request is notified to the worker. In that case, even if the paper is left between the cap member 55 and the liquid ejection head 14, the ink is ejected from each liquid ejection head 14 at predetermined time intervals T, as in the first embodiment, to prevent each liquid ejection head 14 from drying out.

[0082] In this embodiment, the operations of Step 3, Step 5, and Step 6 shown in Fig. 15 are not limited to retracting the paper from between the cap member 55 and the liquid ejection head 14. For example, the paper P may be moved in the transport direction A from the state shown in Fig. 16, or moved in the opposite direction to the transport direction A from the state shown in Fig. 17, so that the paper P can be detected by the two paper sensors 64, 65 (the state shown in Fig. 7). As a result, the liquid ejected from the liquid ejection head 14 adheres to the paper P after the predetermined time T, so that it is possible to prevent the ejected liquid from adhering to the transport guide 30 or floating liquid droplets from adhering to the transport guide 30 for some reason.

[0083] Incidentally, some image forming apparatuses are provided with a locking mechanism for the purpose of safety and the like, which prevents the user from freely opening a cover provided on the image forming apparatus body. Such a locking mechanism locks the cover so that it cannot be opened except in specific circumstances, such as when a serviceman replaces or performs maintenance on an ink cartridge. However, with such a locking mechanism, even if the paper is moved from between the cap member 55 and the liquid ejection head 14 so that the cap member 55 can be moved toward the liquid ejection head 14, the user cannot remove the paper jammed in another location in the image forming apparatus, which creates a problem in that the image forming operation cannot be resumed.

[0084] Therefore, when the cap member 55 becomes movable toward the liquid ejection head 14, the locked state of the locking mechanism may be released so that the user can open the cover of the device body and perform other operations to remove jammed paper. The lock may be released, for example, based on a detection signal from a paper sensor that detects that paper has been removed from between the cap member 55 and the liquid ejection head 14. Alternatively, the user may manually release the lock upon receiving a notification based on the detection signal from the paper sensor. This allows the user to remove the jammed paper and resume the printing operation.

[0085] Next, a third embodiment of the present invention will be described with reference to FIGS.

[0086] As shown in FIG. 18, this embodiment differs from the above-described embodiments in that paper sensors 64A to 64E are disposed upstream and downstream in the paper transport direction A of each of the liquid ejection heads 14Y, 14M, 14C, and 14Bk, respectively.

[0087] In this manner, in this embodiment, the paper sensors 64A-64E are disposed on the upstream and downstream sides of the liquid ejection heads 14Y, 14M, 14C, and 14Bk in the paper transport direction A, respectively, so that the stationary position of the paper can be detected in more detail. For example, as shown in the example of Fig. 18, when only the fourth and fifth paper sensors 64D and 64E from the upstream side in the paper transport direction detect the paper P, the first and second cap members 55Bk and 55C from the upstream side in the paper transport direction, where the paper P is not present, can be moved toward the liquid ejection heads 14Bk and 14C, so that the liquid ejection heads 14Bk and 14C can be covered by the cap members 55Bk and 55C (Step 2 in Fig. 19).

[0088] On the other hand, since paper P is interposed between the third and fourth cap members 55M, 55Y from the upstream side in the paper transport direction and the liquid ejection heads 14M, 14Y, the notification unit 41 notifies a paper removal request (Step 3 in FIG. 19). After that, when the cover 50 is opened and the paper P is removed from between the cap members 55M, 55Y and the liquid ejection heads 14M, 14Y ("NO" in Step 8 in FIG. 19), the remaining cap members 55M, 55Y are moved toward the liquid ejection heads 14M, 14Y, and the liquid ejection heads 14M, 14Y are covered by the cap members 55M, 55Y (Step 9 in FIG. 19).

[0089] Furthermore, if the cover 50 is not opened even after the predetermined time T has elapsed (if "NO" in Step 6 in FIG. 19), ink is ejected from each of the liquid ejection heads 14M, 14Y in order to prevent drying of each of the liquid ejection heads 14M, 14Y that are not covered by each of the cap members 55M, 55Y (Step 10 in FIG. 19). At this time, the ejected ink adheres to the paper P interposed between each of the cap members 55M, 55Y and each of the liquid ejection heads 14M, 14Y. Furthermore, each of the liquid ejection heads 14Bk, 14C that are already covered by each of the cap members 55Bk, 55C may or may not eject ink.

[0090] As described above, in this embodiment, when no paper is interposed between some of the cap members 55 and some of the liquid ejection heads 14, the cap members 55 at the locations where no paper is interposed can be moved to cover the liquid ejection heads 14 with the cap members 55. This makes it possible to increase the number of liquid ejection heads 14 covered by the cap members 55, and more reliably reduce the occurrence of liquid ejection defects. Furthermore, since drying is suppressed in the liquid ejection heads 14 covered by the cap members 55, ink consumption can also be reduced by preventing ink ejection from the liquid ejection heads 14.

[0091] 15, the present embodiment may be configured to automatically retract paper interposed between the cap member 55 and the liquid ejection head 14. In this case, the risk of paper being left interposed between the cap member 55 and the liquid ejection head 14 can be reduced, so that the occurrence of liquid ejection defects can be more reliably reduced.

[0092] 20 and 21 are diagrams showing the configuration and operation of the fourth embodiment of the present invention.

[0093] 20, in this embodiment, the conveying guide 30 is composed of a plurality of divided guide members 32A to 32D. Each divided guide member 32A to 32D is disposed between each of the liquid ejection heads 14Y, 14M, 14C, and 14Bk and each of the cap members 55Y, 55M, 55C, and 55Bk. Each divided guide member 32A to 32D can move independently of one another and can be individually retracted from between the cap member 55 and the liquid ejection head 14.

[0094] For example, as shown in Fig. 20, when the paper P is only between some of the cap members 55Y, 55M and some of the liquid ejection heads 14Y, 14M, the division guide members 32A, 32B are retracted in the area where the paper P is not present, as shown in Fig. 21. This allows the cap members 55C, 55Bk to move toward the liquid ejection heads 14C, 14Bk in the area where the paper P is not present, and the liquid ejection heads 14C, 14Bk can be covered by the cap members 55C, 55Bk. Note that in this embodiment, the other configurations and the control in the event of an abnormal stop are basically the same as in the above-mentioned embodiment, so detailed description will be omitted.

[0095] 22 and 23 are diagrams showing the configuration and operation of the fifth embodiment of the present invention.

[0096] 22, in this embodiment, the conveying guide 30 has a plurality of lid members 33A-33D that close each insertion hole 31. The lid members 33A-33D move independently of one another and can be individually switched between an open state and a closed state of each insertion hole 31.

[0097] For example, as shown in Fig. 22, when paper P is present only between some of the cap members 55Y, 55M and some of the liquid ejection heads 14Y, 14M, the cover members 33A, 33B are retracted from the positions facing the insertion holes 31 in the areas where paper P is not present, and the insertion holes 31 are opened, as shown in Fig. 23. This allows the cap members 55C, 55Bk to move toward the liquid ejection heads 14C, 14Bk in the areas where paper P is not present, so that the liquid ejection heads 14C, 14Bk can be covered by the cap members 55C, 55Bk. In this embodiment, the other configurations and the control during abnormal stop are basically the same as those of the above-mentioned embodiment.

[0098] FIG. 24 is a flowchart showing a control method according to the sixth embodiment of the present invention.

[0099] As shown in FIG. 24, in this embodiment, when ink is discharged from the liquid discharge heads 14 after interruption of image formation, ink is discharged in order from the liquid discharge head 14 that has had the longest elapsed time since the last ink discharge among the multiple liquid discharge heads 14. For example, in the case of monochrome printing, the elapsed time since the black ink liquid discharge head 14Bk last discharged ink is short, and the color ink liquid discharge heads 14Y, 14M, and 14C last discharged ink is long. Therefore, in this case, ink is discharged from the color ink liquid discharge heads 14Y, 14M, and 14C, and then ink is discharged from the black ink liquid discharge head 14Bk. In this case, ink is discharged in order from the liquid discharge head 14 that dries easily, so that drying of the liquid discharge heads 14 can be efficiently suppressed. Note that the elapsed time that is the basis for the timing of ink discharge is not limited to the time from the last ink discharge by the liquid discharge head 14 until the normal operation of the image forming apparatus is stopped due to an abnormality, but may be the time until a predetermined time has elapsed after the last ink discharge.

[0100] Furthermore, the liquid ejection head 14 may have a plurality of ejection holes (nozzles) 101 for ejecting ink, as shown in Fig. 25. In this case, the ejection holes 101 can be efficiently prevented from drying by ejecting ink in order from the ejection hole 101 that has ejected ink the longest since it was last ejected.

[0101] FIG. 26 is a flowchart showing a control method according to the seventh embodiment of the present invention.

[0102] 26, in this embodiment, when ink is ejected from each liquid ejection head 14 after the image formation operation is interrupted, the control unit 40 calculates and stores the total amount of ink ejected from each liquid ejection head 14. Then, when ink is ejected from each liquid ejection head 14 again, the control unit 40 checks whether the total amount of ink ejected from each liquid ejection head 14 exceeds a preset maximum total amount of ink ejection.

[0103] As a result, if the total ejection amount does not exceed the maximum total ejection amount, ink is ejected from the liquid ejection head 14. On the other hand, if the total ejection amount exceeds the maximum total ejection amount, the subsequent ejection of ink from the liquid ejection head 14 is restricted. Note that the restriction here includes not only reducing the amount of ink ejected, but also preventing ink ejection altogether. This makes it possible to avoid unlimited ink ejection, reduce the amount of ink consumed, and suppress stains inside the image forming apparatus caused by ink.

[0104] Furthermore, instead of the total ejection amount, the ink ejection operation may be controlled based on the total ejection time of ink or the total number of ejections of ink. That is, if at least one of the total ejection amount, the total ejection time, and the total number of ejections of ink after interruption of image formation exceeds the maximum total ejection amount, the maximum total ejection time, or the maximum total number of ejections, the subsequent ejection of ink may be restricted. Furthermore, the maximum total ejection amount, the maximum total ejection time, and the maximum total ejection number may be set for each liquid ejection head 14 that ejects ink of a different color.

[0105] 27 and 28 are diagrams showing the configuration of an eighth embodiment of the present invention.

[0106] As shown in FIG. 27 and FIG. 28, in this embodiment, two liquid recovery units 60 for recovering ink are provided on both sides of the width direction (paper width direction B) of the paper passing area (sheet passing area) H through which the paper passes, below the paper passing area H. As a result, when ink is repeatedly discharged from the liquid ejection head 14 onto the paper, even if the paper cannot absorb all the ink and the ink overflows from the paper, the ink dripping from the paper can be recovered by the liquid recovery unit 60. Therefore, in this embodiment, it is possible to prevent the inside of the image forming apparatus from being soiled by the ink dripping from the paper. In addition, it is preferable that the liquid recovery unit 60 is disposed at least at a position where the liquid ejection head 14 is disposed in the paper conveying direction A so that the ink can be reliably recovered. Note that the liquid recovery unit 60 is not limited to being disposed on both sides of the paper passing area H, and may be disposed on only one side of the paper passing area H.

[0107] FIG. 29 is a diagram showing the configuration of a ninth embodiment of the present invention.

[0108] 29, the paper sensor 67 may be provided on the cap member 55 instead of on the liquid ejection head 14 side. In this case, the paper sensor 67 can more reliably detect the presence or absence of paper between each cap member 55 and each liquid ejection head 14, and therefore the cap member 55 can be more reliably prevented from coming into contact with the intervening paper. Also, the paper sensor 67 may be a contact type sensor that detects paper by contact, or a non-contact type sensor that detects paper without contact.

[0109] Although each embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the gist of the invention.

[0110] For example, the present invention is not limited to the line-type liquid ejection device in which ink is ejected without moving the liquid ejection head described above, but can also be applied to a serial-type liquid ejection device in which the liquid ejection head ejects ink while moving in the main scanning direction.

[0111] FIG. 30 is a plan view of a liquid ejection device equipped with a serial type liquid ejection head 14. As shown in FIG.

[0112] As shown in Figure 30, the serial type liquid ejection device includes a carriage 25 on which the liquid ejection head 14 is mounted, a guide member (guide rod) 26 for guiding the carriage 25 in the main scanning direction, which is the paper width direction B, and a drive device 27 for moving the carriage 25.

[0113] In this embodiment, a black liquid ejection head 14A having an ejection port array for ejecting black ink droplets, and a color liquid ejection head 14B having an ejection port array for ejecting cyan, magenta, and yellow ink droplets are provided on the carriage 25. Each of the liquid ejection heads 14A and 14B is mounted with the ink ejection direction facing downward so that each ejection port array is disposed in a direction intersecting the main scanning direction (paper transport direction A). Also, separate liquid ejection heads may be provided for each different color. Note that the colors of ink used are not limited to those mentioned above.

[0114] The energy generating means for ejecting ink provided in each of the liquid ejection heads 14A and 14B may be a piezoelectric actuator such as a piezoelectric element, a thermal actuator using an electrothermal conversion element such as a heating resistor to utilize film boiling of liquid, a shape memory alloy actuator using a metal phase change due to a temperature change, or an electrostatic actuator using electrostatic force. In addition, the carriage 25 is equipped with a plurality of sub-tanks for supplying ink of each color to each of the liquid ejection heads 14A and 14B. Each of the sub-tanks is connected to ink cartridges 15Y, 15M, 15C, and 15Bk (see FIG. 1) mounted on the image forming apparatus main body via an ink supply tube.

[0115] The drive device 27 includes a motor 34 as a drive source, and a timing belt 37 wound around a drive pulley 35 and a driven pulley 36. When the motor 34 is driven and the drive pulley 35 rotates, the timing belt 37 moves in an orbit, and the carriage 25 connected to the timing belt 37 moves in the main scanning direction along the guide member 26. By switching the rotation direction of the motor 34 between one direction and the opposite direction, the carriage 25 can move back and forth in the main scanning direction.

[0116] In a liquid ejection device equipped with a serial type liquid ejection head 14, ink is ejected from each of the liquid ejection heads 14A, 14B in response to an image signal while the carriage 25 moves in the main scanning direction, thereby forming an image for one line on the stationary paper P. Then, after the paper P is transported a predetermined distance in the direction of arrow A in Fig. 30, the next line of image is formed. Similarly, the paper P is transported and stopped, and the carriage 25 moves back and forth repeatedly, and ink is ejected onto the paper P to form an image. After the printing operation is completed, the carriage 25 moves to the initial position (the rightmost position in Fig. 30), and the liquid ejection heads 14A, 14B are covered by the cap members.

[0117] In an image forming apparatus equipped with such a serial type liquid ejection device, if the normal operation of the image forming apparatus stops due to an abnormality, the movement of the liquid ejection heads 14A, 14B also stops midway. Therefore, depending on the position where the liquid ejection heads 14A, 14B stop, it may not be possible to cover the liquid ejection heads 14A, 14B with the cap member. In such a case, as in each of the above-mentioned embodiments, by ejecting ink from the liquid ejection heads 14A, 14B every time a predetermined time has elapsed after the driving of the image forming apparatus is stopped, it is possible to suppress drying of the liquid ejection heads 14A, 14B and reduce the occurrence of ink ejection defects.

[0118] Further, the drying device (heating device) according to the present invention is not limited to the image forming apparatus as shown in FIG. 1, but can also be applied to, for example, the image forming apparatus as shown in FIG. 31 or FIG.

[0119] The configuration of another image forming apparatus to which the present invention can be applied will be described below. Note that in the following description, the differences from the above embodiment will be mainly described, and the other parts will be omitted since they are the same as the above embodiment.

[0120] Similar to the above-described embodiment, the image forming apparatus 100 shown in Fig. 31 includes an original transport device 1, an image reading device 2, an image forming unit 3, a sheet supply device 4, a cartridge mounting unit 5, a sheet discharge unit 6, and a sheet placement unit 7. The image forming apparatus 100 shown in Fig. 31 also includes a manual sheet supply device 8. Unlike the embodiment shown in Fig. 1, the image forming unit 3 is disposed to face a transport path 84 along which paper P is transported obliquely relative to the horizontal direction.

[0121] Manual sheet feeder 8 has manual tray 51 as a loading section for loading paper, and paper feed roller 52 as a feeding means for feeding paper from manual tray 51. When manual tray 51 is in an open state (as shown in FIG. 31 ) relative to the image forming apparatus main body, paper can be placed on manual tray 51 and fed.

[0122] 31, when an instruction to start a printing operation is given, paper P is supplied from the sheet supply device 4 or the manual sheet supply device 8, and the paper P is transported to the image forming unit 3. Then, when the paper P is transported to the image forming unit 3, ink is ejected from the liquid ejection head 14 onto the paper P to form an image.

[0123] When performing double-sided printing, after the paper P passes through the image forming unit 3, the paper P is transported in the opposite direction, and the paper P is guided to the reversing transport path 85 by the first path switching means 71. By passing through the reversing transport path 85, the paper P is transported again to the image forming unit 3 in an inverted state, and an image is formed on the back surface of the paper P.

[0124] The paper P on which the image has been formed is selectively guided by the second path switching means 72, which is located downstream of the first path switching means 71 in the paper transport direction, to either a transport path 86 leading to the upper sheet discharge section 6 or a transport path 87 leading to the lower sheet discharge section 6. When the paper P is guided to the transport path 86 leading to the upper sheet discharge section 6, the paper P is discharged to the upper paper discharge tray 20. On the other hand, when the paper P is guided to the transport path 87 leading to the lower sheet discharge section 6, the paper P is further selectively guided by the third path switching means 73 to either a transport path 88 leading to the lower sheet discharge section 6 or a transport path 89 leading to the sheet alignment device 200.

[0125] When the paper P is guided to the conveying path 88 toward the lower sheet discharge unit 6, the paper P is discharged to the lower sheet discharge tray 20. On the other hand, when the paper P is guided to the conveying path 89 toward the sheet alignment device 200, the paper P is conveyed to the sheet alignment device 200, where the paper P is aligned and placed.

[0126] 32 includes a document transport device 1, an image reading device 2, an image forming unit 3, a sheet supply device 4, a cartridge mounting unit 5, a sheet discharge unit 6, a sheet placement unit 7, and a manual sheet supply device 8, similar to the image forming apparatus 100 shown in FIG. 31. In this case, the image forming unit 3 is disposed to face a transport path 90 along which paper P is transported horizontally, similar to the embodiment shown in FIG.

[0127] 32, when an instruction to start a printing operation is given, paper P is supplied from the sheet supply device 4 or the manual sheet supply device 8, and the paper P is transported to the image forming unit 3. Then, when the paper P is transported to the image forming unit 3, ink is ejected from the liquid ejection head 14 onto the paper P to form an image.

[0128] When performing double-sided printing, after the paper P passes through the image forming unit 3, the paper P is transported in the opposite direction, and the first path switching means 69 guides the paper P to the reversing transport path 91. By passing through the reversing transport path 91, the paper P is transported again to the image forming unit 3 in an inverted state, and an image is formed on the back surface of the paper P.

[0129] The paper P with images formed on one or both sides is selectively guided by the second path switching means 70 to either the conveying path 92 leading to the sheet discharge section 6 or the conveying path 93 leading to the sheet alignment device 200. When the paper P is guided to the conveying path 92 leading to the sheet discharge section 6, the paper P is discharged to the paper output tray 20. On the other hand, when the paper P is guided to the conveying path 93 leading to the sheet alignment device 200, the paper P is conveyed to the sheet alignment device 200, where the paper P is aligned and placed.

[0130] By applying the present invention to the image forming apparatus 100 shown in Fig. 31 or 32, it is possible to obtain the same effects as those of the above-mentioned embodiment. That is, even if the liquid ejection head is left in a state where it is not covered with a cap member, ink is ejected from the liquid ejection head at predetermined time intervals, thereby making it possible to prevent the liquid ejection head from drying out and reduce the occurrence of ink ejection defects.

[0131] The liquid ejection device according to the present invention can also be applied to an image forming device that forms an image on a sheet other than paper. The sheet on which the image is formed can be, in addition to paper, for example, resin, metal, cloth, leather, etc. The sheet can be so-called cut paper that is cut to a predetermined size in the sheet transport direction in advance, or so-called roll paper that is long and wound in a roll.

[0132] Furthermore, the present invention is not limited to liquid ejection devices that eject liquid (ink) onto a sheet to form an image, but is also applicable to liquid ejection devices that eject a treatment liquid to modify the surface of a sheet (without forming an image). [Explanation of symbols]

[0133] 3 Image forming section (liquid ejection device) 14 Liquid ejection head (liquid ejection section) 55 Cap member 59 Liquid recovery section 100 Image forming device H Paper passing area (sheet passing area) P Paper (sheet) [Prior art documents] [Patent documents]

[0134] [Patent Document 1] JP 2005-199606 A

Claims

1. A liquid ejection unit that ejects liquid onto a sheet; a cap member for covering the liquid ejection unit; a conveying path along which the sheet is conveyed between the liquid ejection unit and the cap member; A liquid ejection device comprising: The liquid ejection section ejects liquid onto the sheet when the operation of the liquid ejection device is stopped due to an abnormality.

2. A liquid ejection unit that ejects liquid onto a sheet; a cap member for covering the liquid ejection unit; a conveying path along which the sheet is conveyed between the liquid ejection unit and the cap member; A liquid ejection device comprising: The liquid ejection section ejects liquid onto the cap member when the operation of the liquid ejection device is stopped due to an abnormality.

3. A liquid ejection device comprising: a plurality of liquid ejection units that eject liquid onto a sheet; and a plurality of cap members that cover the respective liquid ejection units, A liquid ejection device in which, when the operation of the device is stopped due to an abnormality, the cap member covers the liquid ejection section at a location where the sheet is not interposed between the liquid ejection section and the cap member, and the liquid ejection section ejects liquid onto the sheet.

4. 4. A liquid ejection device as described in claim 3, wherein the liquid ejection section ejects liquid onto the sheet at a location where the sheet is interposed between the liquid ejection section and the cap member, and the liquid ejection section does not eject liquid at a location where the cap member covers the liquid ejection section.

5. A liquid ejection device as described in claim 2 or 3, wherein the liquid ejection section ejects liquid onto the sheet at a location where the sheet is interposed between the liquid ejection section and the cap member, and the liquid ejection section ejects liquid onto the cap member at a location where the cap member covers the liquid ejection section.

6. The liquid ejection device according to claim 1 , wherein, when the operation of the device is stopped due to an abnormality, the sheet facing the liquid ejection portion is retracted to a position not facing the liquid ejection portion.

7. A liquid ejection unit including a plurality of the liquid ejection units, 7. A liquid ejection device according to claim 1, wherein when operation of the device is stopped due to an abnormality, liquid is ejected in order from among the plurality of liquid ejection units, starting with the liquid ejection unit that has had the longest elapsed time since it last ejected liquid.

8. A liquid ejection device as described in any one of claims 1 to 7, wherein if at least one of the total ejection amount, total ejection time, and total number of ejections of liquid ejected by the liquid ejection unit after the operation of the device has stopped due to an abnormality exceeds a maximum total ejection amount, a maximum total ejection time, or a maximum total number of ejections, thereafter liquid ejection from the liquid ejection unit is restricted.

9. A liquid ejection device comprising a plurality of the liquid ejection units, The liquid ejection device according to claim 8 , wherein at least one of the maximum total ejection amount, the maximum total ejection time, and the maximum total number of ejections is set for each of the plurality of liquid ejection sections.

10. The liquid ejection apparatus according to claim 1 , wherein the liquid ejection section ejects liquid at a predetermined timing after the operation of the apparatus is stopped and a sheet removal request is notified.

11. a cover that can be opened to expose the inside of the device; The liquid ejection device according to claim 1 , wherein the liquid ejection section ejects liquid when the cover is not opened for a predetermined time.

12. The liquid ejection apparatus according to claim 1 , further comprising a liquid recovery section that recovers the liquid ejected from the liquid ejection section onto the sheet.

13. The liquid ejection device according to claim 12 , wherein the liquid recovery section is disposed below one or both widthwise sides of a sheet passing area through which the sheet passes.

14. An image forming apparatus comprising the liquid ejection device according to claim 1 .

Images