Image forming apparatus

Abstract

To provide an image forming apparatus capable of improving the entire working efficiency of an image forming job by reducing the number of times of replacement of a holding sheet even when the number of image forming media of the same size per unit time is reduced.SOLUTION: The image forming apparatus 1 includes the rotating image forming cylinder 17, the first to fourth inkjet heads 23 to 26 arranged around the image forming cylinder 17 and configured to form an image on the image forming medium 4 on the peripheral surface of the image forming cylinder 17, and the support units respectively arranged at a plurality of positions on the peripheral surface of the image forming cylinder 17 and each configured to support the holding sheet configured to hold the image forming medium 4 on the peripheral surface of the image forming cylinder 17.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] The image forming apparatus disclosed in Patent Document 1 includes an image forming cylinder that adsorbs and transports a sheet serving as an image forming medium. The image forming apparatus also includes an inking device that transfers ink to a sheet adsorbed to the image forming cylinder. The image forming cylinder has multiple suction chambers that open radially outward and numerous through-holes. The image forming cylinder also includes a masking sheet that covers the openings of the multiple suction chambers. The suction chambers are formed in shapes that conform to the outlines of multiple types of sheets of different sizes and are separated from each other by partitions. Each suction chamber is connected to an air suction device that selectively sucks air from the suction chamber. The masking sheet extends along the partitions. The masking sheet has non-adsorption sections that narrow the opening width of the suction chambers surrounded by the partitions. The numerous through-holes are provided in the masking sheet except for the non-adsorption sections. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-1198 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, with the technology of Patent Document 1, users can only arbitrarily set three or four different sizes of image formation media (paper, etc.), and to form images on image formation media of other sizes, a service technician must replace the holding sheet (also called a "masking sheet" or similar). Even if the holding sheet is replaced, the user can still only arbitrarily set three or four different sizes of image formation media, making it difficult to form images on multiple sizes of image formation media. This means that it is difficult to respond to requests for a wide variety of media in a short period of time.

[0005] The reason why the user's settings could only accommodate three or four different sizes of image forming media was that in order to achieve an image forming capacity of 3,000 sheets per hour, it was necessary to attach a holding sheet of the same size to all surfaces of the image forming cylinder.

[0006] However, in reality in the market, there are almost no print jobs that print 3,000 sheets per hour, and most print jobs print 1,000 sheets or less, in which case the image forming apparatus can operate continuously for about 20 minutes.

[0007] In addition, the market demands more than 20 different sizes of image forming media, and the trend is toward small-lot printing of multiple sizes rather than large-volume printing of a few sizes. Therefore, there is a need to reduce the number of times service personnel need to be called in to replace the holding sheet and improve the operating efficiency of image forming devices.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image forming apparatus that can reduce the number of times the holding sheet needs to be replaced and improve the operating efficiency of the image forming apparatus. [Means for solving the problem]

[0009] (1) Therefore, the present invention is an image forming apparatus comprising a rotating image forming drum, an image forming unit arranged around the image forming drum to form an image on an image forming medium on the peripheral surface of the image forming drum, and support units arranged at multiple locations on the peripheral surface of the image forming drum, each supporting a holding sheet that holds the image forming medium on the peripheral surface of the image forming drum, wherein the holding sheets with different masking areas are supported on the surface of the image forming drum, and a supply unit supplies the image forming medium so that it can be sucked onto the holding sheet.

[0010] (2) The image forming apparatus may be as described in (1), in which each of the holding sheets corresponds to a plurality of sizes of the image forming medium, and the image forming drum is provided with a suction section that holds the image forming medium on the holding sheet by sucking the image forming medium through each of the holding sheets.

[0011] (3) The image forming apparatus may be the one described in (1), which includes a heating section that heats the surface side of the image forming cylinder, a determination section that determines the type of the holding sheet on the surface of the image forming cylinder, and a cooling section that cools the image forming cylinder other than the part that holds and transports the image forming medium based on the determination of the determination section.

[0012] (4) The image forming apparatus may be as described in (3), further comprising a detection unit for detecting a position on the surface of the image forming drum, and each holding sheet has an identification mark indicating the type of the holding sheet, and the determination unit detects the position using the detection unit and determines the type of the holding sheet at the position by reading the identification mark.

[0013] (5) The image forming apparatus may be one or more holes formed through the holding sheet, and the determination unit may determine the type of the holding sheet by a reading unit that reads the number of the holes.

[0014] (6) The image forming apparatus according to (1) may further include a receiving unit that receives input of the position of the holding sheet on the surface of the image forming drum and the type of the holding sheet.

[0015] (7) The image forming apparatus may be as described in (2), in which the suction section does not perform the suction when each of the holding sheets is in a position where it can be supported by the support section but does not hold the image forming medium via the holding sheet.

[0016] (8) The image forming apparatus described in (1) may be provided with an inversion operation unit that inverts the image forming medium so as to enable the image forming unit to form an image on both sides of the image forming medium, and the inversion operation unit inverts the image forming medium after image formation on one side by the image forming unit, supplies the image forming medium to the same holding sheet as used to form the image on that one side, and enables image formation on the other side of the image forming medium by holding the image forming medium on the same holding sheet. [Effects of the Invention]

[0017] According to the present invention, it is possible to provide an image forming apparatus that can reduce the number of times the holding sheet needs to be replaced and improve the operating efficiency of the image forming apparatus. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a side view showing the overall configuration of an image forming apparatus according to an embodiment of the present invention; [Figure 2] FIG. 2 is an enlarged cross-sectional view showing the outer peripheral cutout portion of the barrel. [Figure 3] FIG. 2 is an enlarged cross-sectional view showing a main part. [Figure 4] FIG. 2 is a cross-sectional view showing a part of an image forming cylinder. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 4. [Figure 7] FIG. 2 is a plan view of a perforated resin sheet. [Figure 8] FIG. 2 is an enlarged plan view showing a portion of the perforated resin sheet. [Figure 9] FIG. 2 is a side view showing a portion of the axial end of the image forming cylinder. [Figure 10] FIG. 2 is a perspective view of a cooling unit provided in an image forming cylinder. [Figure 11] FIG. 2 is a perspective view of a holding sheet and a detection unit. [Figure 12] 2 is a block diagram showing the electrical connections of a control system of the image forming apparatus. [Figure 13] 1A to 1C are diagrams illustrating examples of various types of holding sheets. [Figure 14] 10 is a timing chart illustrating an intermittent operation performed by the image forming apparatus. [Figure 15] FIG. 10 is a side view of the image forming drum with four holding sheets attached to the peripheral surface thereof. DETAILED DESCRIPTION OF THE INVENTION

[0019] An embodiment of an image forming apparatus of the present invention will be described below with reference to the drawings. Fig. 1 is a side view showing the overall configuration of an image forming apparatus according to this embodiment. Image forming apparatus 1 supplies paper or other image forming media from a supply section 2 located at the far right in Fig. 1 to an image forming unit 3. This image forming unit 3 is a device that forms an image on one or both sides of image forming media 4. After image formation in image forming unit 3, image forming media 4 is sent to a discharge section 5 and discharged in a stack onto a delivery pile.

[0020] The supply unit 2 is configured to transfer the image forming medium 4 from the feeder pile 11 to the feeder board 13 by means of suckers 12. The suckers 12 are connected to an intermittent supply valve 14, which allows the image forming medium 4 to be continuously fed to the image forming unit 3. The supply control unit 151 (FIG. 12) can also control the image forming medium 4 to be intermittently fed to the image forming unit 3 (details will be described later). When an image is formed only on the front side of the image forming medium 4, the suckers 12 continuously feed the image forming medium 4 to the feeder board 13. On the other hand, when an image is formed on both the front and back sides of the image forming medium 4, the suckers 12 intermittently feed the image forming medium 4 to the feeder board 13.

[0021] The image forming unit 3 includes a supply-side transfer cylinder 16 to which the image forming medium 4 supplied from the supply section 2 is transported by a sheet supply-side swing device 15. The image forming unit 3 includes an image forming cylinder 17 to which the image forming medium 4 is fed from the supply-side transfer cylinder 16. The image forming unit 3 includes a first discharge-side transfer cylinder 18, a second discharge-side transfer cylinder 19, a third discharge-side transfer cylinder 20, and a pre-reversal double cylinder 21 that feed the image forming medium 4 after image formation.

[0022] The image forming cylinder 17 is provided with a heating section 101 that heats the image forming medium 4 to a predetermined temperature.

[0023] The cylinder 17 rotates to transport the image forming medium 4 while adsorbing it, and is equipped with an adsorption device 22 (see FIG. 2), which will be described later. The image forming unit 3 also includes first to fourth ink jet heads 23 to 26, which are positioned downstream of the supply-side transfer cylinder 16 in the transport direction of the image forming medium 4. In other words, the first to fourth ink jet heads 23 to 26 form an image forming section. While the image forming method in this example is an ink jet method, the present invention is not limited to this. Other image forming methods that can be used in the present invention include dye-sublimation thermal transfer, silver halide photography, direct thermal recording, and melting thermal transfer. An ink drying lamp 27 is provided downstream of the fourth ink jet head 26 in the transport direction of the image forming medium 4 (counterclockwise in FIG. 1).

[0024] The first to fourth ink jet heads 23 to 26 form images by ejecting ink droplets onto the image forming medium 4 using predetermined actuators. The ink drying lamp 27 hardens the ink ejected onto the image forming medium 4 by the first to fourth ink jet heads 23 to 26.

[0025] One of the multiple conveying drums is a first discharge-side transfer drum 18 that receives the image-forming medium 4 from the image-forming drum 17. Another of the multiple conveying drums is a second discharge-side transfer drum 19 that receives the image-forming medium 4 from the first discharge-side transfer drum 18. The other two of the multiple conveying drums are a third discharge-side transfer drum 20 and a pre-reversal double cylinder 21 that receive the image-forming medium 4 from the second discharge-side transfer drum 19. The image-forming medium 4 that will have an image formed on its back side is conveyed from the second discharge-side transfer drum 19 to the pre-reversal double cylinder 21. The image-forming medium 4 that has an image formed on only its front side or that has an image formed on both its front and back sides is sent from the second discharge-side transfer drum 19 to the third discharge-side transfer drum 20. These image-forming media 4 are then sent to the delivery pile 6 via a delivery belt 28.

[0026] The supply-side transfer cylinder 16, the image forming cylinder 17, the first discharge-side transfer cylinder 18, the second discharge-side transfer cylinder 19, the third discharge-side transfer cylinder 20, and the pre-reversal double cylinder 21 are each equipped with gripper devices 31 to 36. These are devices for transferring the image forming medium 4. These gripper devices 31 to 36 have a conventionally well-known structure for gripping and holding the downstream end of the image forming medium 4 in the transport direction.

[0027] A reversing operation unit (reversing swing device) 37 is disposed between the pre-reversing doubler cylinder 21 and the supply-side transfer cylinder 16. This reversing operation unit 37 is a device for sending the image forming medium 4 from the pre-reversing doubler cylinder 21 to the image forming cylinder 17. The reversing operation unit 37 grips the upstream end in the transport direction of the image forming medium 4 sent by the pre-reversing doubler cylinder 21. The reversing operation unit 37 then sends the image forming medium 4 to the image forming cylinder 17 with its front side facing the image forming cylinder 17. In other words, after an image is formed on the front side, the reversing operation unit 37 turns the image forming medium 4 over and returns it to the image forming cylinder 17.

[0028] The outer periphery of the image forming cylinder 17 is provided with outer periphery cutouts 41 that accommodate the gripper device 32, and sheet support portions 42 that adsorb and hold the image forming medium 4. The image forming cylinder 17 is provided with a plurality of outer periphery cutouts 41 at positions that divide the outer periphery into four equal parts, for example. The sheet support portions 42, which will be described in detail later, are provided between these outer periphery cutouts 41, 41. In other words, the image forming cylinder 17 is a quadruple cylinder that is provided with, for example, four pairs (not limited to four, as long as there is more than one) of outer periphery cutouts 41 and sheet support portions 42.

[0029] 2 is an enlarged cross-sectional view of the outer peripheral cutout portion of the cylinder. Gripper device 32 of image forming cylinder 17 has a claw shaft 43 provided in outer peripheral cutout portion 41. Gripper device 32 has a claw member 44 provided on claw shaft 43. Gripper device 32 has a claw base 45 that cooperates with claw member 44 to hold holding sheet 102 (FIG. 11), which will be described later. In other words, the support portion of the present invention is realized by devices such as gripper device 32, claw member 44, and claw base 45.

[0030] The claw shaft 43 extends parallel to the axis of the image forming cylinder 17 from one end to the other end in the axial direction of the cylinder 17. The claw shaft 43 is rotatably supported by support plates 46a of support plates 46 (FIG. 9) attached to both ends of the image forming cylinder 17.

[0031] The support plate 46a is formed so that a portion of the outer periphery of the support plate 46 partially protrudes radially outward. In this example, the support plate 46a is provided at four locations in the circumferential direction corresponding to the outer peripheral cutouts 41. The support plate 46a is formed so as to cover the outer peripheral cutouts 41 from the outside in the linear direction of the image forming cylinder 17. The claw shaft 43 is driven by a conventionally known cam mechanism (not shown) and rotates at predetermined intervals. The claw members 44 are provided at multiple positions in the axial direction of the claw shaft 43. As the claw shaft 43 rotates, the claw members 44 move between a gripping position shown by a solid line in FIG. 2 and an open position shown by a two-dot chain line in FIG. 2.

[0032] The claw base 45 is placed on the tip of a claw base shaft 47 attached to the outer peripheral cutout portion 41 and fixed by a fixing bolt 48.

[0033] The claw base shaft 47 is provided with a support member 51 that protrudes from the bottom of the outer peripheral cutout 41 toward the outside in the radial direction of the image forming cylinder 17. The claw base shaft 47 is provided with a retaining member 53 that is secured by a fixing bolt 52 while overlapping the protruding end 51a of the support member 51. The support member 51 and retaining member 53 extend parallel to the axis of the image forming cylinder 17 from one end to the other in the axial direction of the image forming cylinder 17. The support member 51 is secured to the bottom of the outer peripheral cutout 41 by a fixing bolt 54. A mating surface 55 between the protruding end 51a of the support member 51 and the retaining member 53 extends in the axial and radial directions of the image forming cylinder 17.

[0034] As shown in Fig. 2, suction chambers 56 that form part of the suction device 22 are formed in, for example, three sheet support portions 42 (Fig. 1) of the body 17. The suction device 22 includes the suction chambers 56. The suction device 22 includes a suction section 58 that is connected to the suction chambers 56 via an on-off valve 57.

[0035] Suction chamber 56 is formed in a box-shaped member 59 provided on the outer periphery of image forming cylinder 17. Box-shaped member 59 opens radially outward of image forming cylinder 17. The opening of box-shaped member 59 is covered with a metal sheet 61 and a perforated resin sheet 62 (these two sheets are collectively referred to as holding sheets 102 (FIG. 11)).

[0036] The metal sheet 61 is made of stainless steel or the like and has many ventilation holes 63 formed therethrough. The metal sheet 61 is formed in a shape that covers the entire sheet support section 42. Both ends of the metal sheet 61 are fixed to the image forming cylinder 17. The both ends here refer to the upstream end and downstream end in the transport direction of the image forming medium 4.

[0037] As shown in FIG. 2, the downstream end of the metal sheet 61 in the sheet conveyance direction is bent radially inward of the image forming cylinder 17 along the end 59a of the box-shaped member 59. The bent portion is clamped between the protruding end 51a of the support member 51 and the holding member 53. The other end of the metal sheet 61 is fixed to a sheet holding shaft 64 provided in the outer peripheral cutout 41 (FIG. 1). Note that the sheet holding shaft 64 shown in FIG. 2 does not support the metal sheet 61 covering the sheet support portion 42 located on the right side in FIG. 2. The sheet holding shaft 64 shown in FIG. 2 supports the end of the metal sheet 61 covering the other sheet support portion 42 adjacent to it across the outer peripheral cutout 41.

[0038] As shown in FIGS. 7 and 8, the perforated resin sheet 62 includes a main body 65 formed in a sheet shape from synthetic resin. The perforated resin sheet 62 includes numerous ventilation holes 66 that allow air to pass through in the thickness direction of the main body 65. The main body 65 has excellent heat resistance, UV resistance, and solvent resistance. The main body 65 is formed from a material that is strong enough not to stretch due to heat and has appropriate tensile strength. The material forming the main body 65 is, for example, PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer). The thickness of the main body 65 is preferably 0.07 mm or more and 0.5 mm or less. The thickness is more preferably 0.1 mm to 0.3 mm.

[0039] A first nozzle 67 and a second nozzle 68 are provided at both ends of the main body 65. The ends here refer to the upstream end and downstream end in the transport direction of the image forming medium 4 (both left and right ends in FIG. 7). The first nozzle 67 is located at one of the downstream ends of the main body 65 in the transport direction of the image forming medium 4. The second nozzle 68 is located at the other downstream end of the main body 65 in the transport direction of the image forming medium 4. Hereinafter, the nozzle 67 located at the downstream end of the main body 65 in the conveying direction of the image forming medium 4 will be referred to as the first nozzle 67, and the other nozzle 68 will be referred to as the second nozzle 68.

[0040] 3, the first nozzle 67 and the second nozzle 68 are formed to be thicker than the main body 65 of the perforated resin sheet 62. As shown in FIG. 7, the first nozzle 67 is provided with a handle 69 that protrudes to one side in the axial direction of the image forming cylinder 17.

[0041] The ventilation sections 66 are formed by through-holes that penetrate the main body 65 in the thickness direction. The opening shape of the ventilation sections 66 is circular, as shown in FIG. 8 . Adjacent ventilation sections 66 are not connected to each other. The ventilation sections 66 are arranged in the main body 65 at predetermined intervals in the axial direction of the image forming cylinder 17 and the conveyance direction of the image forming medium 4. As shown by the two-dot chain line in FIG. 7 , the ventilation sections 66 are provided over substantially the entire area of ​​the main body 65. The hole diameter of the ventilation sections 66 is preferably 0.2 mm or more and 1 mm or less. This is more preferably 0.3 mm to 0.9 mm. The formation pitch of the ventilation sections 66 is preferably 1.3 mm or less. This is more preferably 0.5 mm to 1.1 mm. Furthermore, the opening ratio is preferably 50% or more and 70% or less. This opening ratio is the ratio of the opening area of ​​all ventilation sections 66 to the total area of ​​the main body 65.

[0042] The perforated resin sheet 62 thus formed is attached to the image forming cylinder 17 by using first and second nozzles 67, 68, with the sheet laid on top of the metal sheet 61. The first nozzle 67 is held by a first holding portion 71 provided between the end 59a of the box-shaped member 59 and the holding member 53 (FIG. 3). The end 59a of the box-shaped member 59 forms a side wall extending in the radial direction of the image forming cylinder 17, downstream of the outer peripheral cutout 41 in the conveying direction of the image forming medium 4 (FIG. 2).

[0043] The first holding portion 71 has a space S that accommodates one end of the perforated resin sheet 62 extending radially inward from the outer peripheral surface of the image forming cylinder 17 (FIG. 3). The first holding portion 71 has a protruding wall 72 that faces the first mouthpiece 67 inserted into the space S from the radially outer side of the image forming cylinder 17 (upper side in FIG. 3). The protruding wall 72 is formed on the holding member 53 of the claw base shaft 47. The first mouthpiece 67 located within the first holding portion 71 faces the protruding wall 72. Therefore, the first mouthpiece 67 cannot move radially outward from the image forming cylinder 17. In other words, the protruding wall 72 restricts movement of the first mouthpiece 67 radially outward from the image forming cylinder 17.

[0044] Figure 9 is a side view showing a portion of the axial end of the image forming cylinder 17. As shown in Figure 9, the space S is in communication with an open portion 73 formed at the axial end of the image forming cylinder 17. The open portion 73 is formed upstream of the support plate 46a of the support plate 46 in the conveyance direction of the image forming medium 4 (to the right in Figure 9). The open portion 73 is open in the axial direction of the image forming cylinder 17. Therefore, the space S can be seen by viewing the image forming cylinder 17 from the axial direction.

[0045] 2, the other end of the perforated resin sheet 62 is held by a second holding portion 81 provided in the outer peripheral cutout 41. The second holding portion 81 has a guide member 82 that extends in the axial direction of the image forming cylinder 17 within the outer peripheral cutout 41. The second holding portion 81 has a slider 83 that is movably supported by the guide member 82. The second holding portion 81 has a cover plate 84 that cooperates with the slider 83 to hold the second nozzle 68.

[0046] Guide member 82 extends from one end to the other end in the axial direction of image forming cylinder 17. Guide member 82 is formed in a groove-like cross section having a pair of ribs 82a, 82b. Guide member 82 is fixed to support plates 46 provided on both axial ends of image forming cylinder 17 by support brackets 85 and fixing bolts 86 (FIG. 4).

[0047] The slider 83 is formed in a plate shape extending in the axial direction of the image forming cylinder 17 along the guide member 82. The slider 83 is attached to the guide member 82 with two types of bolts: an adjustment bolt 87 extending in the transport direction of the image forming medium 4, and a fixing bolt 88 extending in the radial direction of the image forming cylinder 17. The adjustment bolt 87 rotatably passes through a rib 82a of the guide member 82 and is screwed into the slider 83. A stopper 89 (see FIG. 2) is provided opposite the head 87a of the adjustment bolt 87. The stopper 89 extends in the axial direction of the image forming cylinder 17 along the guide member 82 and is fixed to the support bracket 85 with a fixing bolt 90. Therefore, the adjustment bolt 87 can be loosened until the head 87a hits the stopper 89. After the head 87a hits the stopper 89, the adjustment bolt 87 cannot be loosened any further.

[0048] Figure 5 is a cross-sectional view taken along line VV in Figure 4. As shown in Figure 5, the fixing bolt 88 passes through the elongated hole 83a of the slider 83 and is attached to the guide member 82 by a screw action. The fixing bolts 88 are disposed at both ends and the center of the slider 83. In addition, a retaining pin 91 that extends across the fixing bolt 88 is provided at the tip of the fixing bolt 88.

[0049] Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 4. A recessed groove 92 for accommodating the first nozzle 67 is formed at the downstream end of the slider 83 in the conveying direction of the image recording medium 4 (Fig. 6). 4, the cover plate 84 is formed in the shape of a strip extending in the axial direction of the image forming cylinder 17. The cover plate 84 is provided with a plurality of pressing portions 84a for pressing the second mouthpiece 68. In this embodiment, the image forming cylinder 17 is provided with a plurality of cover plates 84 aligned in the axial direction.

[0050] The cover plate 84 is placed on the slider 83 and fixed to the slider 83 at both longitudinal ends by fixing bolts 93. As shown in Fig. 6, the fixing bolts 93 pass through elongated holes 84b in the cover plate 84 and are screwed into the slider 83. The tip of the fixing bolt 93 is inserted into the elongated hole 82c in the guide member 82. The tip of this fixing bolt 93 is also provided with a retaining pin 91 that extends across the fixing bolt 93.

[0051] Here, the procedure for attaching the perforated resin sheet 62 to the image forming cylinder 17 will be described. The following procedure is followed to attach the perforated resin sheet 62 to the image forming cylinder 17. First, one longitudinal end of the first mouthpiece 67 is inserted from the outside in the axial direction of the image forming cylinder 17 into an opening 73 formed at one axial end of the image forming cylinder 17. This attachment operation and the operation of removing the perforated resin sheet 62 from the image forming cylinder 17 can be easily performed by gripping the handle portion 69. Then, the first mouthpiece 67 is further advanced in the axial direction and inserted into the space S of the first holding portion 71.

[0052] When the perforated resin sheet 62 is pulled toward the other end with one end inserted into the space S, the first mouthpiece 67 comes into contact with the protruding wall 72. This prevents the first mouthpiece 67 from moving any further. Therefore, by inserting one end of the effective resin sheet 62 into the space S, the one end of the effective resin sheet 62 is held by the first holding portion 71 (image forming cylinder 17) in a state where it is prevented from coming out.

[0053] Thereafter, the main body 65 of the perforated resin sheet 62 is placed on the sheet support portion 42 of the image forming cylinder 17. Then, the second mouthpiece 68 is sandwiched between the slider 83 and the cover plate 84 of the second holding portion 81. Then, the cover plate 84 is fixed to the slider 83 with the fixing bolts 93.

[0054] Next, the adjustment bolts 87 are tightened, and the perforated resin sheet 62 is pulled together with the slider 83. By pulling the perforated resin sheet 62 in this manner, the perforated resin sheet 62 comes into close contact with the metal sheet 61 (the outer peripheral surface of the image forming cylinder 17). Thereafter, the slider 83 is fixed to the guide member 82 with the fixing bolts 88 while a predetermined tension is applied to the perforated resin sheet 62. By fixing the slider 83 to the guide member 82, the work of attaching the perforated resin sheet 62 to the image forming cylinder 17 is completed.

[0055] When the suction device 22 operates with the perforated resin sheet 62 attached to the image forming cylinder 17, air passes through the perforated resin sheet 62, the ventilation section 66, and the ventilation holes 63 of the metal sheet 61, and is sucked into the suction chamber 56. This allows the image forming medium 4 to be sucked onto the perforated resin sheet 62.

[0056] The image forming apparatus 1 performs the image forming operation with the suction device 22 operating in this manner. Therefore, the image forming medium 4 is transported while being sucked onto the image forming cylinder 17. Then, ink is ejected from the first to fourth ink jet heads 23 to 26 to form an image. The ink adhering to the image-forming medium 4 is sent to a position where the image-forming medium 4 faces the ink drying lamp 27. Then, the ink on the image-forming medium 4 is dried (cured) by being irradiated with ultraviolet or infrared rays by the ink drying lamp 27. At this time, the surface of the image-forming medium 4 is heated, and the heat is transferred from the image-forming medium 4 to the perforated resin sheet 62.

[0057] As shown in FIG. 1, a heating section (heater or the like) 103 for heating the surface side (of the image forming medium 4) of the image forming cylinder 17 is provided inside the image forming cylinder 17 (or outside the image forming cylinder 17).

[0058] FIG. 10 is a perspective view of a cooling unit provided within the image forming drum. The cooling unit 104 is a device that cools the portions of the image forming drum 17 other than the portion that holds and transports the image forming medium 4. The cooling unit 104 in FIG. 10 has a water flow path 111 formed on the back side of the image forming drum 17 through which water flows. The cooling unit 104 cools the portions of the image forming drum 17 other than the portion that holds and transports the image forming medium 4 by circulating water through the water flow path 111. In other words, the cooling unit 104 in this example is a water-cooled type. However, the present invention is not limited to this, and the cooling unit 104 may be cooled by a blower or by using heat pump technology. In other words, the cooling unit 104 may use any cooling means.

[0059] FIG. 11 is a perspective view of the holding sheet and the detection unit. Each holding sheet 102 has an identification mark 121 provided, for example, on an edge portion thereof. The identification mark 121 is used to identify the type of holding sheet 102 on which the identification mark 121 is formed. The identification mark 121 is read by a reading unit 122, allowing the type of holding sheet 102 on which the identification mark 121 is formed to be identified. In the example of FIG. 11, the identification mark 121 is one or more holes penetrating the holding sheet 102, and the number of holes is read by the reading unit 122, such as a microlaser sensor, to determine the type of the corresponding holding sheet 102. Note that the identification mark 121 and the reading unit 122 are not limited thereto. For example, the identification mark 121 may be formed as a barcode or QR code (registered trademark), which may be read by the reading unit 122, such as a barcode reader or camera. Various other methods may also be used for the identification mark 121 and the reading unit 122.

[0060] Image formation on both sides of the image forming medium 4 is performed as follows. The supply section 2 supplies the image forming medium 4 without an image formed thereon to the image forming unit 3. Then, an image is formed on only one side of the image forming medium 4 by the image forming section (in this example, the first to fourth ink jet heads 23 to 26). The image forming medium 4 after image formation on only one side is turned over by the above-mentioned reversal operation section 37. The image forming medium 4 is then supplied to the same holding sheet 102 that was used to form the image on one side. Then, image formation on the other side of the image forming medium 4 is performed by holding the image forming medium 4 on the same holding sheet 102.

[0061] FIG. 12 is a block diagram showing the electrical connections of the control system of the image forming apparatus. This control system is centered around a control unit 141, which is comprised primarily of a microcomputer, an ASIC (Application Specific Integrated Circuit), and the like. Various sensors and actuators (most of which are not shown) are connected to the control unit 141 via predetermined interfaces. In particular, an identification unit 152, which is comprised of a rotation sensor that detects the rotation of the image forming cylinder 17 and identifies the position on the surface of the image forming cylinder 17, is connected to the control unit 141. One of the functions of the control unit 141 is a determination unit 142 that determines the type of the holding sheet 102 on the surface of the image forming cylinder 17. The control unit 141 may be connected to a reception unit 143 that receives input of the position of the holding sheet 102 on the surface of the image forming cylinder 17 and the type of the holding sheet 102. That is, the reception unit 143 is an input device such as a keyboard or a touch panel. The reception unit 143 receives input from a user, and an input reception control unit 144 of the control unit 141 executes processing. That is, the input reception control unit 144 receives input of the position of the holding sheet 102 on the surface of the image forming cylinder 17 and the type of the holding sheet 102. Then, the input reception control unit 144 performs settings corresponding to the input.

[0062] The control unit 141 also executes the functions of the reading control unit 145. The reading control unit 145 controls the reading unit 122 to read the identification mark 121. Then, the reading control unit 145 performs necessary settings based on the result of the reading.

[0063] In this way, the identification of the holding sheet 102 and the corresponding settings can be performed by the reading control unit 145 reading the identification mark 121 with the reading unit 122. Alternatively, the identification of the holding sheet 102 and the corresponding settings can be performed by the input reception control unit 144 receiving user input with the reception unit 143. The image forming apparatus 1 may be equipped with both or only one of these two methods.

[0064] Furthermore, the control unit 141 also performs the functions of an intermittent operation control unit 147. The processing performed by the intermittent operation control unit 147 will be described in detail in the section on effects to be described later. As described above, the holding sheet 102 is held on the circumferential surface of the image forming cylinder 17. In this state, tension is applied to the holding sheet 102 by a predetermined biasing member or the like (not shown as it has a well-known structure). As a result, the holding sheet 102 is stretched over the circumferential surface of the image forming cylinder 17.

[0065] FIG. 13 is a diagram illustrating various types of holding sheets. In this example, types M, N, P, etc. are given as examples of holding sheets 102. In this diagram, four different vertical and horizontal sizes of image forming media 4 are listed corresponding to each type of holding sheet 102. These four sizes are the sizes of image forming media 4 that can be held by the corresponding holding sheet 102 and on which an image can be formed by rotating the image forming cylinder 17. That is, in this example, each holding sheet 102 corresponds to, for example, four types of image forming media 4. This number may be three or fewer, or five or more.

[0066] The suction unit 58 can suck the image-forming medium 4 and hold the image-forming medium 4 on the holding sheet 102 using the mechanism described above. FIG. 15 is a side view of four holding sheets attached to the circumferential surface of the image-forming cylinder 17. In this example, as described above, four holding sheets 102 are attached to the circumferential surface of the image-forming cylinder 17. These multiple holding sheets 102 (four in this example) are multiple types of holding sheets 102. This may be, for example, two types or four types. Each type of holding sheet 102 has a different masking area. In other words, the image-forming medium 4 supplied from the image-forming medium supply unit 2 is different for each type of holding sheet 102. The type of each holding sheet 102 is identified by the means described above with reference to FIG. 11, and the image-forming medium 4 corresponding to the holding sheet 102 is supplied at a timing that allows it to be properly adsorbed and held by the holding sheet 102. It is preferable that these multiple types of holding sheets 102 do not overlap with each other in the sizes of image forming media 4 that they are compatible with. Therefore, suppose that different types of holding sheets 102 are compatible with completely different sizes of image forming media 4. Furthermore, suppose that all four holding sheets 102 are different types. In this case, one holding sheet 102 is compatible with four different sizes of image forming media 4. Four types of such holding sheets 102 are attached to the circumferential surface of image forming drum 17. Therefore, image forming apparatus 1 can accommodate 16 different sizes of image forming media 4 without replacing the holding sheets 102. In contrast, if all four holding sheets 102 were the same type, image forming apparatus 1 could only accommodate four different sizes of image forming media 4. It is sufficient that multiple types of holding sheets 102 are attached to image forming drum 17. That is, only two or three holding sheets 102 may be attached to image forming drum 17.

[0067] As described above, the numerous ventilation sections 66 that allow air to pass through are formed only in a portion of the plane of each holding sheet 102. That is, in the example described above, the holding sheet 102 is compatible with only four different sizes of image-forming media 4. These four types are similar in size. It is sufficient if only the four types of image-forming media 4 of similar sizes can be accurately sucked in and held on the holding sheet 102. Therefore, the holding sheet 102 has ventilation sections 66 formed only in those sufficient positions.

[0068] Next, the effects of this embodiment will be described. First, multiple types of holding sheets 102 are mounted on the image forming cylinder 17. In this example, four holding sheets 102 are mounted. These multiple holding sheets 102 include holding sheets 102 of multiple sizes. If all four holding sheets 102 are the same type, the image forming apparatus 1 can only accommodate image forming media 4 of four different sizes. In contrast, if all four holding sheets 102 are different types, the image forming apparatus 1 can accommodate image forming media 4 of up to 16 different sizes. In other words, one holding sheet 102 can accommodate image forming media 4 of four different sizes, and there are four such holding sheets 102. Therefore, the image forming apparatus 1 can accommodate image forming media 4 of up to 16 different sizes.

[0069] Therefore, an image forming apparatus 1 that can accommodate up to 16 different sizes of image forming media 4 has the following advantages. The holding sheet 102 needs to be replaced only when forming an image on a type of image forming media 4 other than the 16 types. In other words, the holding sheet 102 rarely needs to be replaced in the image forming apparatus 1. A specialized service technician must be called to replace the holding sheet 102. Therefore, new jobs cannot be performed on the image forming apparatus 1 until the service technician is called and the replacement of the holding sheet 102 is completed. This reduces the productivity of the image forming apparatus 1. In other words, multiple types of holding sheets 102 are attached to the image forming drum 17. This reduces the number of times the holding sheet 102 needs to be replaced compared to when all holding sheets 102 are the same type. Therefore, an image forming apparatus 1 that can improve the overall work efficiency of image formation jobs can be provided.

[0070] In this case, let's assume that the image forming drum 17 of the image forming apparatus 1 rotates 1,000 times per hour to form images. In this case, if all four holding sheets 102 are the same type, image formation on 4,000 sheets per hour would be possible, which may seem like high productivity. However, today, typical users only require a productivity of around 1,000 sheets per hour. In reality, many users only require image formation on around 500 sheets per job on the image forming apparatus 1. Therefore, for most users, the aforementioned productivity of 1,000 sheets per hour is sufficient performance. However, for typical users, the need to frequently replace the holding sheets 102 is a bigger problem that leads to reduced productivity.

[0071] In other words, according to the image forming apparatus 1, even if the number of images formed on image forming media 4 of the same size per unit time is reduced, the number of times the holding sheet 102 needs to be replaced can be reduced, thereby improving the overall work efficiency of the image forming job. In this example, each holding sheet 102 is compatible with only four different sizes of image-forming media 4. These four types are similar in size. It is sufficient if only the four types of image-forming media 4 with similar sizes can be accurately sucked in and held on the holding sheet 102. Therefore, the holding sheet 102 has ventilation sections 66 formed only in the sufficient positions.

[0072] Problems arise if ventilation sections 66 are formed on holding sheet 102 in locations other than those corresponding to the four sizes of image-forming media 4. If ventilation sections 66 are present in an area of ​​holding sheet 102 that is wider than the area where the four sizes of image-forming media 4 are located, the following occurs: The image-forming media 4 cannot be sufficiently sucked through ventilation sections 6. In other words, if the above-mentioned suction occurs outside the position of the image-forming media 4, the adhesion of the image-forming media 4 to holding sheet 102 decreases. Furthermore, the ink ejected by the first to fourth inkjet heads 23 to 26, which form the image forming section, is disturbed by the air flow, which could result in poor images.

[0073] Furthermore, when attempting to form an image on an image forming medium 4 that is larger than the image forming medium 4 that the holding sheet 102 is designed to accommodate, the following problem occurs. In this case, the leading and trailing edges of the large-sized image forming medium 4 cannot be sucked through the ventilation section 6. As a result, the leading and trailing edges may lift up from the holding sheet 102 and come into contact with the first to fourth ink jet heads 23 to 26. Naturally, this contact results in poor image quality.

[0074] To prevent this situation, the holding sheet 102 is designed to accommodate only the four sizes of image-forming media 4 that are similar to each other, as described above. The ventilation sections 6 are also provided on the holding sheet 102 only at positions that correspond to these four sizes. This makes it possible to prevent problems such as poor image quality.

[0075] Each holding sheet 102 corresponds to a plurality of sizes of image forming media 4. A suction unit 58 is provided inside the image forming cylinder 17 to suck the image forming media 4 through the holding sheet 102 and hold the image forming media 4 on the holding sheet 102. This allows the image formation medium 4 to be stably held on the circumferential surface of the image formation cylinder 17. Therefore, the image forming apparatus 1 can form an image on the image formation medium 4 stably.

[0076] Image forming apparatus 1 is provided with heating unit 101 (FIG. 1) that heats the surface side of image forming cylinder 17. Control unit 141 executes the function of determination unit 147 that determines the type of holding sheet 102 on the surface of image forming cylinder 17. Based on the determination of determination unit 147, cooling unit 104 cools the image forming cylinder 17 except for the portion that holds and transports image forming medium 4 under the control of determination unit 147.

[0077] As a condition for image formation, ink for image formation requires that the image-forming medium 4 be heated to a predetermined temperature. Therefore, a heating unit 101 is provided to heat the image-forming medium 4 (in FIG. 1, it is shown inside the image-forming cylinder 17, but it may be located anywhere outside). However, when the image-forming medium 4 is held on the holding sheet 102, heat is absorbed by the image-forming medium 4. Meanwhile, heating unit 101 is still heating. Therefore, the temperature in the areas of the image-forming cylinder 17 where the image-forming medium 4 is not held becomes too high. This may cause the image-forming cylinder 17 to thermally expand and deform in the areas where the image-forming medium 4 is not held. This deformation may result in image defects. Therefore, the areas of the image-forming cylinder 17 where thermal expansion may occur are cooled by a cooling unit 104. This prevents deformation of the image-forming cylinder 17 due to thermal expansion, thereby preventing image defects.

[0078] 11, each holding sheet 102 has an identification mark 121 formed thereon that indicates the type of the holding sheet 102. The determination unit 142 determines the type of the holding sheet by reading the identification mark 121. The determination unit 142 also determines the position of the main surface of the image forming cylinder 17 using the identification unit 151. Therefore, the image forming apparatus 1 can accurately determine the type of the holding sheet 102 at each position on the image forming cylinder 17 and determine the type of image forming medium 4 on which an image can be formed using the holding sheet 102.

[0079] In this embodiment, the identification mark 121 is one or more holes formed through the holding sheet 102. The determination unit 142 determines the type of holding sheet 102 using the reading unit 122, which reads the number of holes. Therefore, the formation of the identification mark 121 can be achieved by simple means, and the reading unit 122 can be read by simple means such as an optical sensor. Therefore, the type of holding sheet 102 can be identified by simple means.

[0080] The image forming apparatus 1 is provided with a receiving unit 143 that receives input of the position of the holding sheet 102 on the surface of the image forming cylinder 17 and the type of the holding sheet 102. That is, the user can input this information to cause the image forming apparatus 1 to recognize the type of the holding sheet 102, etc.

[0081] In this case, the image forming apparatus 1 includes both a means using the identification mark 121, the reading unit 122, and the determination unit 142, and a means using the reception unit 143. The image forming apparatus 1 may include both of these means, or only one of them. However, the means using the identification mark 121, the reading unit 122, and the determination unit 142 can recognize the type of the holding sheet 102 without requiring input from the user, thereby reducing the burden on the user. On the other hand, when the reception unit 143 is used, the identification mark 121 and the reading unit 122 are unnecessary. This eliminates the need for a process of forming the identification mark 121 on the holding sheet 102 and the installation of the reading unit 122, thereby reducing the manufacturing cost of the image forming apparatus 1.

[0082] The supply unit 2 supplies the image forming medium 4 to the image forming cylinder 17 side. The support unit of the present invention is implemented by devices such as the gripper device 32, the gripper member 44, and the gripper base 45. Among these multiple support units, there may be one that does not support the holding sheet 102. In such a case, during the image forming operation, the image forming unit does not perform image formation on the surface of the image forming cylinder 17 that does not support the holding sheet 102. The supply control unit 151 then causes the supply unit 2 to intermittently supply the image forming medium 4 so that the image forming operation is performed only on the surface of the image forming cylinder 17 that supports the holding sheet 102.

[0083] 14 is a timing chart illustrating the intermittent operation performed by the image forming apparatus. In this example, unlike the four sheets described above, only three holding sheets 102 can be held on the image forming cylinder 17, and a maximum of three images can be formed on one rotation of the image forming cylinder 17. This example is an example of double-sided printing, and "feed" refers to the period during which the image forming medium 4 is supplied from the supply unit 2 to the image forming cylinder 17 for image formation on the front side. "Return" refers to the period during which the image forming medium 4 after image formation on the front side is inverted as described above and returned to the image forming cylinder 17, and an image is formed on the back side of the image forming medium 4. In this case, the image forming medium 4 is not supplied from the supply unit 2.

[0084] In FIG. 14, "Normal" refers to the case where all the holding sheets 102 are used to form images on three sheets of image forming media 4 per rotation of the image forming cylinder 17. "Two-sheet intermittent" refers to the case where only two holding sheets 102 are attached to the image forming cylinder 17 and two images are formed on two sheets per rotation of the image forming cylinder 17. In this case, one holding sheet 102 is missing from the image forming cylinder 17. Therefore, when the front side of the image forming cylinder 17 where the holding sheet 102 is not present approaches the image forming unit, the supply unit 2 does not supply image forming media 4 to the position where the holding sheet 102 is not present. The supply control unit 151 also stops ink ejection in the image forming unit at that position. This is "stop for one sheet after return." Furthermore, since the supply of image forming media 4 from the supply unit 2 is stopped at this time, "stop this feed" is displayed.

[0085] "One sheet intermittent" refers to the case where only one holding sheet 102 is mounted on the image forming cylinder 17 and one image is formed per rotation of the image forming cylinder 17. There are two holding sheets 102 missing on the image forming cylinder 17. Therefore, when the front side of the image forming cylinder 17 where the holding sheet 102 is not present approaches the image forming unit, the supply unit 2 does not supply the image forming medium 4 to the position where the holding sheet 102 is not present. The supply control unit 151 also stops the ejection of ink in the image forming unit at that position. This is the "two-minute stop after return."

[0086] Even if the image forming cylinder 17 is loaded with a full number of holding sheets 102 (three sheets), some of the holding sheets may not correspond to the image forming medium 4 on which an image is to be formed. In this case, the supply control unit 51 will not supply the image forming medium 4 to the holding sheet 102 that does not correspond to the image forming medium 4 on which an image is to be formed. The supply control unit 51 also stops the ejection of ink from the image forming unit at the position of the holding sheet 102.

[0087] These measures prevent image formation from being performed at a position on the holding sheet 102 where the holding sheet 102 is not present or where the holding sheet 102 does not correspond to the image forming medium 4. This prevents the image forming apparatus 1 from performing unnecessary image formation operations.

[0088] At positions where each holding sheet 102 can be supported by the support section but where the image forming medium 4 is not held via the holding sheet 102, the suction section 58 does not perform the suction. This suppresses the operation of suctioning the image forming medium 4 via the holding sheet 102 at unnecessary positions, and prevents unnecessary operation of the suction section 58.

[0089] The image forming apparatus 1 is provided with a reversing operation unit (reversing swing device) 37 that turns over the image forming medium 4. This allows the image forming apparatus 1 to form images on both sides of the image forming medium 4 by the image forming unit, as described above.

[0090] The reversing operation unit 37 reverses the image forming medium 4 after the image has been formed on one side in the image forming unit. This makes it possible to supply the image forming medium 4 to the same holding sheet 102 that was used to form the image on that one side, and to form an image on the other side of the image forming medium 4 by holding the image forming medium 4 on the same holding sheet 102. This makes it possible to prevent the occurrence of a situation where double-sided image formation is performed using another holding sheet 102 that is not compatible with the image forming medium 4.

[0091] The image forming apparatus 1 of the present embodiment described above is merely one embodiment of the present invention. Therefore, the present invention can be embodied in various forms different from the image forming apparatus 1 within the scope of the present invention. [Explanation of symbols]

[0092] 1. Image forming device 2 Supply section 17 Image forming cylinder 23-26 1st to 4th ink jet heads (image forming units) 32 Grip jaw device (support part) 37 Reversing operation unit 44 Claw member (support part) 45 Claw stand (support part) 58 Suction part 101 Heating section 104 Cooling section 121 Identification signs 122 Reading unit 142 Judgment section 143 Reception Department 151 Supply control section 152 Identification unit

Claims

1. a rotating imaging cylinder; an image forming unit disposed around the image forming cylinder and configured to form an image on an image forming medium on a circumferential surface of the image forming cylinder; and support portions arranged at a plurality of locations on the peripheral surface of the image forming cylinder, each supporting a holding sheet that holds the image forming medium on the peripheral surface of the image forming cylinder, An image forming apparatus, wherein the holding sheet having different masking areas is supported on the surface of the image forming cylinder, and a supply unit supplies the image forming medium so that it can be sucked onto the holding sheet.

2. Each of the holding sheets corresponds to a plurality of sizes of the image forming media, The image forming apparatus according to claim 1 , wherein the image forming cylinder is provided with a suction section that holds the image forming medium on the holding sheet by sucking the image forming medium through each of the holding sheets.

3. a heating section for heating the front surface side of the image forming cylinder; a determination unit for determining the type of the holding sheet on the surface of the image forming cylinder; 2. The image forming apparatus according to claim 1, further comprising a cooling section that cools a portion of the image forming drum other than a portion that holds and transports the image forming medium based on the determination of the determination section.

4. a detection unit for detecting a position on the surface of the image forming cylinder; An identification mark indicating the type of the holding sheet is formed on each of the holding sheets, The image forming apparatus according to claim 3 , wherein the determining unit detects the position using the detecting unit and determines the type of the holding sheet at the position by reading the identification mark.

5. the identification mark is one or more holes formed through the holding sheet, The image forming apparatus according to claim 4 , wherein the determining unit determines the type of the holding sheet by a reading unit that reads the number of holes.

6. The image forming apparatus according to claim 1 , further comprising a receiving unit that receives input of the position of the holding sheet on the surface of the image forming drum and the type of the holding sheet.

7. 3. The image forming apparatus according to claim 2, wherein the suction section does not perform the suction at a position where each of the holding sheets can be supported by the support section but the image forming medium is not held via the holding sheet.

8. a reversing operation unit that reverses the image forming medium so that the image forming unit can form an image on both sides of the image forming medium, 2. The image forming apparatus according to claim 1, wherein the inversion operation unit inverts the image forming medium after image formation on one side in the image forming unit, supplies the image to the same holding sheet used to form the image on that side, and enables image formation on the other side of the image forming medium by holding the image forming medium on the same holding sheet.

Images