Conveyor

Abstract

To reduce a possibility of contact of a medium suctioned and transported with an image formation part in a transport device.SOLUTION: A transport device 1 is disposed so as to face an inkjet head 110 (one example of an image formation part) for forming an image on a medium M and transports the medium M while suctioning the medium M. The transport device 1 includes a transport surface S having a suction area A1 where the medium M is suctioned and a non-suction area A2 where the medium M is not suctioned. The non-suction area A2 is provided at a position which is located at an end part S1 as seen in a width direction W of the medium M which is orthogonal to a transport direction D of the medium M of the transport surface S and does not face the inkjet head 110.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a transport device for transporting a medium. [Background technology]

[0002] Conventionally, an image forming apparatus uses a suction fan to draw air below the inkjet head to generate pressure, which adheres the paper to the belt for transport. In this type of suction transport, a platen is installed below the belt, and pressure chambers called cells, surrounded by ribs, are installed on the sliding surface of the platen that contacts the belt to generate negative pressure, thereby achieving paper adsorption. Specifically, the negative pressure generated within the cells is applied to the paper through holes in the belt, adsorbing the paper to the belt transport surface.

[0003] In such suction conveyance, a method is generally known in which negative pressure is generated over the entire conveyance surface to attract the paper (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-280321 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the paper is attracted to the belt by generating negative pressure across the entire conveying surface as described above, the widthwise edge (edge) of the paper may float above the belt surface, resulting in a head attack where the paper comes into contact with the inkjet head.

[0006] For example, if paper is left in a humid environment, variations in the amount of moisture within the paper can cause the paper fibers to stretch, resulting in multiple galvanized iron curls at the edges of the paper. When paper with such galvanized iron curls is transported on a belt conveyance surface that generates negative pressure across the entire conveyance surface, slack occurs in the paper that cannot be fully absorbed at the edges. This slack can come into contact with the inkjet head during transport, causing damage to the inkjet head or a media transport jam. Note that slack can also occur at both ends of the width of not only paper but also other sheet-like media, and can come into contact with the image forming unit, such as the inkjet head, during transport.

[0007] An object of the present invention is to provide a conveying device that can reduce the possibility of a medium being attracted and conveyed coming into contact with an image forming unit. [Means for solving the problem]

[0008] In one aspect, the conveying device is arranged opposite an image forming unit that forms an image on a medium, and conveys the medium while adsorbing it, and is provided with a conveying surface having an adsorption area that adsorbs the medium and a non-adsorption area that does not adsorb the medium, and the non-adsorption area is provided at an end of the conveying surface in the width direction of the medium that is perpendicular to the conveying direction of the medium, and at a position that does not face the image forming unit. [Effects of the Invention]

[0009] According to this aspect, it is possible to reduce the possibility that the medium being attracted and transported will come into contact with the image forming unit. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a front view showing an image forming apparatus including a conveying device according to an embodiment; [Figure 2] FIG. 2 is a plan view showing a platen for explaining an adsorption region and a non-adsorption region according to an embodiment. [Figure 3]FIG. 2 is an enlarged plan view showing a part of a conveyor belt and a platen for explaining an adsorption region and a non-adsorption region according to an embodiment. [Figure 4] FIG. 2 is an enlarged cross-sectional view showing a platen and the like for explaining an adsorption region and a non-adsorption region in one embodiment. [Figure 5] 10A and 10B are diagrams illustrating the height of a medium at each transport position according to an embodiment. [Figure 6] 10A and 10B are diagrams for explaining the height of a medium at each transport position in a comparative example. [Figure 7] 10A and 10B are diagrams showing experimental results of the number of contacts of the inkjet head with each type and position of the medium in an embodiment and a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A conveying device according to an embodiment of the present invention will now be described with reference to the drawings.

[0012] FIG. 1 is a front view showing an image forming apparatus 100 including a conveying device 1 according to the present embodiment.

[0013] The up-down direction, left-right direction, and front-rear direction shown in FIG. 1 and later-described FIGS. 2 to 4 are merely examples in which the right direction is the transport direction D of the medium M, but for example, the up-down direction is the vertical direction, and the left-right direction and front-rear direction are horizontal directions. The medium M is, for example, paper. However, the medium M may also be a sheet-like medium other than paper.

[0014] As shown in FIG. 1, the image forming apparatus 100 includes a plurality of inkjet heads 110, which are an example of an image forming section, a plurality of pressure rollers 120, and a conveying device 1.

[0015] The inkjet heads 110 form an image on the medium M by ejecting ink. For example, as shown in FIG. 2, a total of 18 inkjet heads 110 are arranged in six rows in the transport direction D of the medium M, with three inkjet heads in each row in the width direction W of the medium M perpendicular to the transport direction D. Note that the inkjet heads 110 in two rows adjacent to each other in the transport direction D are arranged so as to be offset by half a pitch in the width direction W. In other words, the inkjet heads 110 are arranged in a staggered pattern.

[0016] Here, just as the inkjet heads 110 are arranged in six rows in the transport direction D as described above, it is desirable that the image forming units, such as inkjet heads 110, are arranged in multiple rows at intervals in the transport direction D. However, only one image forming unit may be arranged, and the number and arrangement are not particularly limited. Furthermore, the image forming unit is not limited to the inkjet head 110, and may be another image forming head such as a thermal head, a transfer body such as a photosensitive drum, or the like. Note that in FIG. 2, the transport belt 11, which will be described later, is omitted, and the multiple inkjet heads 110 are indicated by thick solid lines, and the non-adsorption area A2, which will be described later, is indicated by thick dashed lines.

[0017] The pressure roller 120 is disposed above the conveyor belt 11 at a height where it contacts the conveyor belt 11 so as to press the medium M conveyed by the conveyor belt 11 toward the conveying surface S of the conveyor belt 11. As a result, the pressure roller 120 rotates in accordance with the rotation of the conveyor belt 11.

[0018] For example, a total of seven pressure rollers 120 are arranged, including five between each row of inkjet heads 110, one upstream of the inkjet head 110 on the most upstream side in the conveyance direction D, and one downstream of the inkjet head 110 on the most downstream side in the conveyance direction D. Two pressure rollers 120 may be provided between each row of inkjet heads 110. The pressure rollers 120 are provided across the entire width direction W of the conveyor belt 11.

[0019] The conveying device 1 includes a conveying belt 11, a plurality of pulleys 12 to 15, a platen 21, a platen plate 22, a chamber 23, and a fan 24.

[0020] The conveyor belt 11 is an endless belt that rotates while being stretched over a plurality of pulleys 12 to 15, and conveys the medium M while adsorbing it.

[0021] 3 and 4, the conveyor belt 11 is provided with a plurality of belt holes 11a. The belt holes 11a are arranged, for example, at intervals in the width direction W that are the same as the intervals at which recesses 21a of a platen 21, which will be described later, are formed, and at intervals that are twice the intervals at which recesses 21a of a platen 21, which will be described later, are formed in the conveyance direction D, and two rows of belt holes 11a adjacent to each other in the width direction W are offset by half a pitch in the conveyance direction D. In other words, the belt holes 11a are arranged in a staggered pattern. However, the arrangement of the belt holes 11a is not particularly limited.

[0022] Of the plurality of pulleys 12 to 15, one (for example, pulley 13) is a drive pulley to which power is transmitted from a driving means such as a motor (not shown), and the rest are driven pulleys.

[0023] The platen 21 is an example of a support member that supports the conveyor belt 11 on the surface (lower surface) opposite to the conveying surface S (upper surface) of the conveyor belt 11. The platen 21 has, for example, a flat plate shape. The conveyor belt 11, which rotates as described above, slides on the platen 21.

[0024] 2, the platen 21 has a plurality of recesses 21a (see FIGS. 3 and 4) that are arranged in the conveyance direction D and the width direction W and can communicate with the belt holes 11a. The recesses 21a are square in plan view (as viewed from the inkjet head 110 side).

[0025] 3 and 4, the platen 21 has a plurality of suction holes 21b that are connected to only some of the recesses 21a and that suck air from the recesses 21a. These suction holes 21b penetrate the platen 21 in the up-down direction. The suction holes 21b have a diameter smaller than the width of the recesses 21a in the front-rear direction and the left-right direction, and are preferably connected to the center of the recesses 21a in a plan view.

[0026] The multiple recesses 21a connected to the suction holes 21b form pressure chambers called cells, and thus form suction regions A1 that suction the medium M on the conveying surface S of the conveyor belt 11. The multiple recesses 21a that are not connected to the suction holes 21b form non-suction regions A2 that do not suction the medium M on the conveying surface S of the conveyor belt 11. Note that the non-suction regions A2 may be, for example, regions where the air suction path is blocked by a shutter, and the non-suction regions A2 are not limited to recesses 21a that are not connected to the suction holes 21b and are formed on the conveying surface S of the conveyor belt 11.

[0027] As shown in FIG. 2, the non-suction region A2 is provided at an end S1 (preferably both ends) of the conveying surface S in the width direction W, at a position that does not face the inkjet heads 110. The suction region A1 is provided over the entire central portion S2 of the conveying surface S in the width direction W and at a position of the end S1 that faces the inkjet heads 110. In the example of FIG. 2, which is merely an example, the end S1 of the conveying surface S is two ends when the conveying surface S is divided into approximately four equal parts in the width direction W, and the central portion S2 of the conveying surface S is the portion excluding the end S1. The end S1 where the non-suction region A2 is provided is preferably a position where both ends in the width direction W of the medium M conveyed in the conveying device 1 pass. In addition, in cases where the medium M is conveyed while being shifted to one side in the width direction W and multiple media M of different sizes in the width direction W are conveyed, the non-suction region A2 may be provided only at the end S1 on one side in the width direction W where the media M are shifted.

[0028] It is desirable that the suction region A1 be provided over the entire central portion S2 of the conveying surface S, but a non-suction region A2 (as an example, several recesses 21a that are not connected to the suction holes 21b) that does not affect suction may be provided in part of the central portion S2 of the conveying surface S in the width direction W. In other words, the non-suction region A2 does not need to be provided only at the end portion S1 of the conveying surface S and at a position that does not face the multiple inkjet heads 110. In other words, it is desirable to provide non-suction regions only at the end portions in the width direction W as described above, but non-suction regions may also be provided in places other than the end portions in the width direction W.

[0029] 2, in the range (area) in which a plurality of inkjet heads 110 (18 in total) are arranged in the transport direction D, non-suction areas A2 are provided in areas that do not face the inkjet heads 110. On the other hand, in the range in the transport direction D in which a plurality of inkjet heads 110 are not arranged (upstream and downstream of the range in which a plurality of inkjet heads 110 are arranged), no non-suction areas A2 are provided.

[0030] Ribs 21c are provided to protrude upward in the areas where recesses 21a are not formed on the platen 21. In other words, recesses 21a are separated by the ribs 21c.

[0031] The platen 21 is provided with a plurality of bosses 21d that protrude downward.

[0032] The platen plate 22 is disposed below the platen 21 and supports the platen 21 at the lower ends of the plurality of bosses 21d of the platen 21. The platen plate 22 has, for example, a flat plate shape.

[0033] The platen plate 22 is provided with a plurality of through holes 22a that communicate with the negative pressure chamber inside the chamber .

[0034] The chamber 23 is disposed below the platen plate 22 and has a negative pressure chamber therein.

[0035] The fan 24 exhausts air from the negative pressure chamber of the chamber 23. This causes a negative pressure in the chamber 23, and this negative pressure generates an attraction force at the belt holes 11a via the through holes 22a in the platen plate 22, the gap between the platen plate 22 and the platen 21 (around the bosses 21d), the suction holes 21b and the recesses 21a in the platen 21, and causes the medium M to be attracted to the conveyor belt 11. Note that if electrostatic attraction or the like is used instead of air suction to attract the medium M to the conveyor belt 11, the fan 24 can be omitted. Also, in this embodiment, the conveyor device 1 is disposed below the inkjet head 110, but the conveyor device 1 may also be disposed above the inkjet head 110. In that case, a configuration that is upside down from the above description may be adopted.

[0036] As described above, the conveyance device 1 has a non-adsorption area A2 at an end S1 in the width direction W of the conveyance surface S of the conveyance belt 11, at a position that does not face the inkjet head 110. Therefore, as shown in Fig. 5, the height of the medium M is higher in the non-adsorption area A2 where the inkjet head 110 is not located directly above, and is in a state of height 0 when the medium M is in contact with the conveyance belt 11 while being pressed down by the pressure roller 120. Furthermore, the height of the medium M is lower in the adsorption area A1 where the inkjet head 110 is located directly above than in the non-adsorption area A2 due to the above-mentioned adsorption force.

[0037] In contrast, in a comparative example in which the non-adsorption region A2 is not provided and only the adsorption region A1 is provided, as shown in Fig. 6, the height of the medium M is high in both the adsorption region A1 where the inkjet head 110 is not located directly above and the adsorption region A1 where the inkjet head 110 is located directly above. This is because, for example, when the grain of the paper, which is the medium M, extends in the width direction W, sagging that occurs in the medium M, particularly at the ends in the width direction W, makes it impossible to adsorb the paper sufficiently with the above-mentioned adsorption force. Note that in this embodiment, the non-adsorption region A2 is provided at the end S1 in the width direction W of the conveyance surface S, in a position that does not face the inkjet head 110, and therefore it is possible to control the position where sagging (floating) of the medium M occurs in this position that does not face the inkjet head 110.

[0038] Therefore, as shown in Figure 7, in an experiment in which 1,000 sheets of medium M were transported, the number of times the right (downstream end in the transport direction D), left (upstream end in the transport direction D), rear (end in the width direction W), or front (end in the width direction W) of the medium M came into contact with the inkjet head 110 was less than in the comparative example, regardless of whether the medium M was all landscape (longitudinal direction was width direction W) and was A4 size (210 mm x 297 mm) single-sided coated paper (thick paper), A4 size plain paper, B5 size (182 mm x 257 mm) plain paper, or A4 size thin paper.

[0039] Since the medium M is prone to the above-mentioned sagging at its front-to-back ends (both ends in the width direction W), in the comparative example, the number of times the medium M comes into contact with the inkjet head 110 is large both at the front and back of the medium M, whereas in this embodiment, the number of times the medium M comes into contact with the inkjet head 110 is small both at the front and back of the medium M.

[0040] In the present embodiment described above, the conveying device 1 is disposed opposite the inkjet head 110, which is an example of an image forming unit that forms an image on the medium M, and conveys the medium M while adsorbing it. The conveying device 1 also includes a conveying surface S having an adsorption area A1 that adsorbs the medium M and a non-adsorption area A2 that does not adsorb the medium M, and the non-adsorption area A2 is provided at an end S1 of the conveying surface S in the width direction W of the medium M that is perpendicular to the conveying direction D of the medium M, and at a position that does not face the inkjet head 110.

[0041] This makes it possible to control the position of sagging (floating) of the medium M, which tends to occur at the ends of the medium M in the width direction W, so that it is dispersed to positions on the transport surface S that do not face the inkjet head 110, which are the non-suction areas A2. Therefore, in a comparative example in which the entire transport surface S is made into the suction area A1, sagging of the medium M cannot be suppressed completely, and sagging of the medium M occurs even in positions facing the inkjet head 110, whereas in this embodiment, sagging of the medium M is caused in the non-suction areas A2 that do not face the inkjet head 110, and sagging can be suppressed in positions facing the inkjet head 110. Furthermore, in an embodiment (another comparative example not shown) in which a non-suction region A2 is also provided in a position of the central portion S2 of the transport surface S that does not face the inkjet head 110, sagging of the medium M in the central portion S2 encourages unnecessary sagging at the ends of the medium M in the width direction W, whereas in this embodiment, the non-suction region A2 is provided only at the ends in the width direction W, so that sagging of the medium M can be dispersed to areas that do not face the inkjet head 110 at the ends of the medium M in the width direction W, where sagging of the medium M is unavoidable. Therefore, according to this embodiment, it is possible to reduce the possibility of the medium M being adsorbed and transported coming into contact with the inkjet head 110.

[0042] In addition, in this embodiment, an adsorption area A1 is provided in the portion of the central portion S2 of the conveying surface S in the width direction W that faces the inkjet head 110 and in the portion that does not face the inkjet head 110, and an adsorption area A1 is provided in the portion of both end portions S1 of the conveying surface S that are located on either side of the central portion S2 in the width direction W that faces the inkjet head 110, and a non-adsorption area A2 is provided in the portion of both end portions S1 of the conveying surface S that does not face the inkjet head 110.

[0043] This makes it possible to control the position of slack in the medium M that occurs at both ends in the width direction W of the medium M to a position that does not face the inkjet head 110, which is the non-suction area A2 of the transport surface S. This further reduces the possibility that the medium M being transported by suction will come into contact with the inkjet head 110.

[0044] In this embodiment, the conveying device 1 further includes a conveying belt 11 having a plurality of belt holes 11a and conveying the medium M on a conveying surface S, and a platen 21, which is an example of a support member that supports the conveying belt 11 on the surface of the conveying belt 11 opposite the conveying surface S. The platen 21 has a plurality of recesses 21a arranged in both the conveying direction D and the width direction W and capable of communicating with the belt holes 11a, and a plurality of suction holes 21b connected to only some of the recesses 21a for sucking air from the recesses 21a. The recesses 21a connected to the suction holes 21b form an adsorption region A1 on the conveying surface S, and the recesses 21a not connected to the suction holes 21b form a non-adsorption region A2 on the conveying surface S.

[0045] This makes it possible to reduce the possibility of the medium M being sucked and transported coming into contact with the inkjet head 110 with a simple configuration in which the suction holes 21b of the platen 21 are connected to only some of the recesses 21a.

[0046] The present invention is not limited to the above-described embodiments, and the components can be modified and embodied without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above-described embodiments. For example, all of the components shown in the embodiments can be appropriately combined. Naturally, various modifications and applications are possible without departing from the spirit of the invention. The invention as originally claimed in the present application is described below.

[0047] [Appendix 1] A conveying device that is disposed opposite an image forming unit that forms an image on a medium and conveys the medium while suctioning the medium, a conveyance surface having an adsorption area that adsorbs the medium and a non-adsorption area that does not adsorb the medium; The non-adsorption area is provided at an end of the conveying surface in a width direction of the medium that is perpendicular to the conveying direction of the medium and at a position that does not face the image forming unit. A conveying device characterized by:

[0048] [Appendix 2] the suction area is provided in a portion of the conveying surface facing the image forming unit at a central portion in the width direction and in a portion not facing the image forming unit, the suction areas are provided at both ends of the conveying surface facing the image forming unit across the central portion in the width direction, The non-adsorption areas are provided at the portions of the conveying surface that do not face the image forming units at both ends. 2. The conveying device according to claim 1.

[0049] [Appendix 3] a conveyor belt having a plurality of belt holes and configured to convey the medium on the conveyance surface; a support member that supports the conveyor belt on a surface of the conveyor belt opposite to the conveying surface, the support member has a plurality of recesses that are arranged in the conveyance direction and the width direction and can communicate with the belt holes, and a plurality of suction holes that are connected to only some of the plurality of recesses and that suck air from the recesses, the plurality of recesses connected to the suction holes form the suction areas on the conveying surface; The recesses that are not connected to the suction holes form the non-adsorption areas on the conveying surface. 3. The conveying device according to claim 1 or 2. [Explanation of symbols]

[0050] 1. Conveyor device 11 Conveyor belt 11a Belt hole 12~15 pulleys 21 Platen 21a Recess 21b Suction hole 21c Rib 21d Boss 22 Plastic Plate 22a Through hole 23 Chamber 24 Fans 100 Image forming device 110 Inkjet head 120 pressure roller A1 Adsorption area A2 Non-adsorption area D Conveying direction M medium S conveying surface S1 end S2 central part W width direction

Claims

1. A conveying device that is disposed opposite a plurality of image forming units that form images on a medium and conveys the medium while suctioning the medium, a conveyance surface having an adsorption area that adsorbs the medium and a non-adsorption area that does not adsorb the medium; In a range in which the plurality of image forming units are arranged in a transport direction of the medium, the non-suction areas are provided only in portions of the transport surface that do not face the image forming units at both ends positioned across a center portion in a width direction of the medium that is perpendicular to the transport direction, In the range in the conveying direction where the plurality of image forming units are arranged, the suction areas are provided in the central portion of the conveying surface facing the image forming units and in the portion not facing the image forming units, and in the end portions of the conveying surface facing the image forming units. A conveying device characterized by:

2. a conveyor belt having a plurality of belt holes and configured to convey the medium on the conveyance surface; a support member that supports the conveyor belt on a surface of the conveyor belt opposite to the conveying surface, the support member has a plurality of recesses that are arranged in the conveyance direction and the width direction and can communicate with the belt holes, and a plurality of suction holes that are connected to only some of the plurality of recesses and that suck air from the recesses, the plurality of recesses connected to the suction holes form the suction areas on the conveying surface; The recesses that are not connected to the suction holes form the non-adsorption areas on the conveying surface.

2. The conveying device according to claim 1.

Images