Conveyor

Abstract

To provide a conveyance device capable of sufficiently suppressing warpage of a print medium and preventing contamination of the print medium and damage to an inkjet head.SOLUTION: A conveyance device includes: a conveyance belt 11 that attracts and conveys a print medium P; and a flexible sheet member 30 that extends in a conveyance direction of the conveyance belt 11, and is placed on the conveyance belt 11 such that a part of a range overlaps an end part of the print medium P extending in the conveyance direction, so that a range other than the part of the range is attracted to the conveyance belt 11.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] 2. Description of the Related Art Conventionally, inkjet printing devices have been proposed that print by ejecting ink from an inkjet head onto a print medium made of paper, film, or the like while the print medium is transported.

[0003] A conveyance device using a conveyor belt has been proposed as a conveyance device for conveying print media in such inkjet printing devices. Specifically, a suction fan is provided facing the back side of the conveyor belt that conveys the print media, and negative pressure is generated in multiple suction holes formed in the conveyor belt by rotation of the suction fan, thereby adsorbing the print media to the conveyor belt.

[0004] Here, when the print medium is transported by the transport device, if the print medium is warped (curled), the print medium may come into contact with the inkjet head, causing the print medium to become soiled or the ink ejection surface to be damaged.

[0005] Therefore, for example, Patent Document 1 proposes a conveying device that suppresses side warping of the print medium by increasing negative pressure toward the edge of the print medium.

[0006] Furthermore, Patent Document 2 proposes a transport device that suppresses the lifting of the printing medium, in which a rotating roller extending in a direction perpendicular to the transport direction of the printing medium is provided between inkjet heads arranged side by side in the transport direction of the printing medium, and this rotating roller suppresses the lifting of the printing medium. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-228262 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-28132 Summary of the Invention [Problem to be solved by the invention]

[0008] However, while it is possible to suppress side warping of the print medium by increasing the negative pressure at the edge of the print medium as in Patent Document 1, there are cases where controlling the negative pressure alone is not enough to reliably suppress the strong warping that occurs in envelopes, etc. Furthermore, even if the negative pressure is increased, if suction holes are not positioned at the edge of the print medium, the very edge of the print medium cannot be sucked, and therefore warping may not be sufficiently suppressed.

[0009] Furthermore, in the configuration of Patent Document 2, the floating of the printing medium cannot be prevented in areas where there are no rotating rollers, so there is a risk that the printing medium may come into contact with the inkjet head.

[0010] SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a conveying device that can sufficiently suppress warping of a printing medium and prevent contamination of the printing medium and damage to an inkjet head. [Means for solving the problem]

[0011] The conveying device of the present invention comprises a conveying section that adsorbs and conveys a printing medium, and a flexible sheet member that extends in the conveying direction of the conveying section, and is placed on the conveying section so that a portion of the sheet member overlaps with an end of the printing medium extending in the conveying direction, thereby causing the portion of the sheet member other than the portion to be adsorbed to the conveying section. [Effects of the Invention]

[0012] According to the conveying device of the present invention, a flexible sheet member is provided that extends in the conveying direction and is placed on the conveying section so that a portion of the sheet member overlaps with the edge of the printing medium, and the remaining portion of the sheet member is adsorbed to the conveying section.As a result, by adsorbing the sheet member to the conveying section, the edge of the printing medium can be pressed by the sheet member, which can sufficiently suppress warping of the printing medium and prevent contamination of the printing medium and damage to the inkjet head. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing a schematic configuration of an inkjet printing apparatus using an embodiment of a conveying device of the present invention; [Figure 2] A top view of the transport unit and the sheet member. [Figure 3] FIG. 10 is an external perspective view showing a state in which the sheet member and the holding mechanism are removed. [Figure 4] FIG. 4 is a cross-sectional view of the holding mechanism shown in FIG. 3 taken along line AA. [Figure 5] A block diagram showing the schematic configuration of a control system of an inkjet printing device. [Figure 6] 10A and 10B are diagrams showing other embodiments of the sheet member; [Figure 7] 10A and 10B are diagrams showing other embodiments of the holding mechanism; [Figure 8] 8 is a cross-sectional view of the holding mechanism 40 taken along line BB in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0014] An inkjet printing apparatus using an embodiment of the transport device of the present invention will be described in detail below with reference to the drawings. Fig. 1 is a schematic diagram of an inkjet printing apparatus 1 of this embodiment. The up, down, left, and right directions indicated by arrows in Fig. 1 are the up, down, left, and right directions of the inkjet printing apparatus 1 of this embodiment. The front side of the paper on which Fig. 1 is drawn is the forward direction, and the back side is the rear direction.

[0015] As shown in FIG. 1, the inkjet printing apparatus 1 of this embodiment includes a transport unit 10 and an image forming section 20.

[0016] The transport unit 10 includes a transport belt 11, a platen roller 12, a suction fan 13, and transport rollers 14. In this embodiment, the transport unit 10 corresponds to the transport section of the present invention.

[0017] The conveyor belt 11 and the platen roller 12 are supported by being suspended directly from the housing of the inkjet printing apparatus 1 or indirectly from a member other than the housing that is provided on the housing.

[0018] The conveyor belt 11 is a circular belt and has a large number of suction holes 11a (white circles shown in FIG. 2) formed therein for adsorbing the print medium P. The platen rollers 12 are rollers that extend in a direction perpendicular to the conveyance direction of the print medium P. In this embodiment, as shown in FIG. 1, four platen rollers 12 are provided.

[0019] The conveyor belt 11 is stretched over the four platen rollers 12 described above, and as the four platen rollers 12 rotate, the conveyor belt 11 moves and the print medium P attracted to the conveyor belt 11 is conveyed. In this embodiment, the platen roller 12 rotates clockwise in FIG. 1. This causes the print medium P attracted to the conveyor belt 11 to be conveyed from left to right in FIG. 1. The left side in FIG. 1 is the upstream side in the conveyance direction, and the right side is the downstream side in the conveyance direction.

[0020] Two suction fans 13 are provided on the upstream and downstream sides of the conveyor belt 11 behind the conveying surface of the print medium P. When the suction fans 13 rotate, negative pressure is generated in the suction holes 11a of the conveyor belt 11, causing the print medium P to be adsorbed to the conveyor belt 11.

[0021] Seven transport rollers 14 are provided above the transport belt 11. The transport rollers 14 are provided near the top of the transport belt 11 and extend in a direction perpendicular to the transport direction of the printing medium P. The transport rollers 14 are arranged at predetermined intervals in the transport direction. Specifically, they are provided on both sides of each line head 21 (described later) in the transport direction. Each transport roller 14 rotates clockwise in FIG. 1 and sends the printing medium P transported directly below it downstream while pressing from above.

[0022] The printing medium P is pressed by each conveying roller 14, thereby preventing the printing medium P from warping. However, as mentioned above, the warping of the printing medium P cannot be prevented between the conveying rollers 14, i.e., directly below the line head 21, and therefore the printing medium P may come into contact with the inkjet head, which may result in contamination of the printing medium P or damage to the ink ejection surface.

[0023] Therefore, in the inkjet printing apparatus 1 of this embodiment, a sheet member 30 is provided between the transport roller 14 and the line head 21 and the transport surface of the transport belt 11.

[0024] The sheet member 30 is a flexible sheet-like member that extends in the transport direction of the print medium P. The sheet member 30 is formed, for example, from PET (polyethylene terephthalate). The material of the sheet member 30 is not limited to PET, and other materials such as resins may be used as long as the material is flexible enough to allow the sheet member 30 to bend under its own weight.

[0025] The sheet member 30 is placed on the conveying surface of the conveyor belt 11 so that a portion of the sheet member 30 overlaps with the edge of the print medium P extending in the conveying direction. Figure 2 is a top view of the conveying unit 10 and the sheet member 30 shown in Figure 1. Figure 2 shows an example in which a No. 3 long envelope is conveyed as the print medium P by the conveyor belt 11.

[0026] 2, the sheet members 30 extend in the conveying direction, and are installed so that a portion of the sheet members 30 overlaps the edge of the envelope extending in the conveying direction. In this embodiment, two sheet members 30 are installed so that they overlap both ends of the envelope. The width of the area W1 where the sheet members 30 overlap with the edge of the envelope is about 10 mm, and the width of the area W2 of the sheet members 30 that does not overlap with the envelope is about 50 mm.

[0027] The area W2 where sheet member 30 and the envelope do not overlap is adsorbed to the conveying surface of conveyor belt 11 by the suction of conveyor belt 11. The adsorption of non-overlapping area W2 on sheet member 30 applies a downward force to area W1 where sheet member 30 and the envelope overlap, and this force presses downward the edge of the envelope where sheet member 30 overlaps. This pressing of the edge of the envelope by sheet member 30 sufficiently suppresses warping of the envelope directly below line head 21, and prevents the envelope from coming into contact with the inkjet head, which could result in contamination of the envelope or damage to the ink ejection surface.

[0028] The width of the range W1 where the sheet member 30 overlaps with the edge of the envelope and the width of the range W2 where it does not overlap are not limited to the above example, and are set appropriately taking into consideration the printing range of the printing medium P, the degree of curvature of the printing medium P, the suction force of the suction fan 13, and the pressing force required for the sheet member 30, etc.

[0029] The upstream end of the sheet member 30 is held by a holding mechanism 31. The holding mechanism 31 is screwed to metal members 32 provided on both sides of the conveyor belt 11 in a direction perpendicular to the conveying direction, but is configured to be detachable. For example, when performing printing processing on a print medium P with little warping, the sheet member 30 is configured to be detachable together with the holding mechanism 31.

[0030] FIG. 3 is an external perspective view showing a state in which the sheet member 30 and the holding mechanism 31 are removed.

[0031] The holding mechanism 31 is made of, for example, metal or plastic, and is a long, narrow rectangular plate-like member extending in a direction perpendicular to the conveying direction as shown in Figures 2 and 3. Openings 33 and 34 for attaching the sheet member 30 are formed in the holding mechanism 31.

[0032] Fig. 4 is a diagram showing a cross section of the opening 33 of the holding mechanism 31 shown in Fig. 3 taken along line AA. A step is formed in the opening 33 of the holding mechanism 31 at a position slightly lower than the upper surface 31a of the holding mechanism 31. The surface below the step of the holding mechanism 31 is the sheet attachment surface 31b, and the end of the sheet member 30 is attached to the sheet attachment surface 31b. The end of the sheet member 30 is attached to the sheet attachment surface 31b using, for example, double-sided tape or glue.

[0033] Furthermore, a slit S extending in a direction perpendicular to the conveying direction is formed in the opening 33 of the holding mechanism 31. A portion of the sheet member 30 extending from the upstream end (the portion attached to the sheet attachment surface 31b) passes through the slit S and is disposed below the holding mechanism 31.

[0034] As described above, the holding mechanism 31 holds the upstream end of the sheet member 30 on the sheet attachment surface 31b through the slit S, and by arranging the portion extending from the upstream end of the sheet member 30 below the holding mechanism 31, the portion extending from the upstream end of the sheet member 30 is bent by the step between the sheet attachment surface 31b and the bottom surface 31c of the holding mechanism 31, forming an inclined surface CL. In this embodiment, the width of the slit S in the conveying direction is about 6 mm, and the step between the sheet attachment surface 31b and the bottom surface 31c of the holding mechanism 31 is about 2 mm.

[0035] As described above, the holding mechanism 31 bends and tilts the portion extending from the upstream end of the sheet member 30, thereby holding the sheet member 30 so that the sheet member 30 is biased toward the conveying surface of the conveyor belt 11. By biasing the sheet member 30 toward the conveying surface of the conveyor belt 11 in this way, the pressing force of the sheet member 30 against the end of the printing medium P on which it overlaps can be increased. Furthermore, the holding mechanism 31 forms the inclined surface CL by passing the sheet member 30 through the slit S, so the sheet member 30 can be tilted with a space-saving configuration without increasing the number of parts.

[0036] The inclination angle θ of the inclined surface CL relative to the conveying surface is approximately 30 degrees, but is preferably between 20 and 40 degrees. By setting the inclination angle θ to 20 degrees or more, the pressing force of the sheet member 30 can be increased. Furthermore, by setting the inclination angle θ to 40 degrees or less, collision of the leading edge of the printing medium P with the inclined surface CL of the sheet member 30 can be suppressed, and the leading edge of the printing medium P can be smoothly fed between the sheet member 30 and the conveying surface.

[0037] The downstream end of the printing medium P supplied to the conveyor belt 11 is inserted between the holding mechanism 31 and the conveying surface of the conveyor belt 11. As shown in FIG. 4, an inclined surface 31d is formed on the underside of the upstream side of the holding mechanism 31. The inclined surface 31d is an inclined surface that slopes upward from the downstream side toward the upstream side. The inclination angle of the inclined surface 31d relative to the conveying surface is approximately 20 degrees. By forming the inclined surface 31d in this manner, the vertical distance of the insertion opening for the printing medium P formed between the holding mechanism 31 and the conveying surface of the conveyor belt 11 can be increased. This makes it possible to prevent the printing medium P from colliding with the holding mechanism 31.

[0038] The print medium P inserted between the holding mechanism 31 and the conveying surface of the conveyor belt 11 is then conveyed downstream by the conveyor belt 11 and inserted between the sheet member 30 and the conveying surface. An inclined surface 31e continuing from the lower surface 31c is formed at the upstream end of the lower surface 31c of the holding mechanism 31, below which the sheet member 30 is disposed. Similar to inclined surface 31d, inclined surface 31e is an inclined surface that rises from the downstream side to the upstream side. The inclination angle of inclined surface 31e with respect to the conveying surface is approximately 45 degrees.

[0039] By making the contact area between the upper surface of the sheet member 30 and the holding mechanism 31 an inclined surface rather than a right angle in this way, the pressure per unit area on the upper surface of the sheet member 30 can be reduced, thereby reducing the load on the sheet member 30 and improving the durability of the sheet member 30.

[0040] Then, the print medium P inserted between the sheet member 30 and the transport surface is transported toward the image forming unit 20 at a predetermined transport speed.

[0041] As shown in FIG. 1, the image forming section 20 is provided at a position facing the conveyor belt 11 of the conveyor unit 10, and includes six line heads 21 and a head holder 22.

[0042] Each line head 21 includes a plurality of inkjet heads each having a plurality of nozzles for ejecting ink.

[0043] Each line head 21 extends in a direction perpendicular to the transport direction of the print medium P and ejects ink onto the print medium P transported by the transport unit 10. As shown in FIG. 1, the six line heads 21 are arranged at predetermined intervals along the transport path of the print medium P. Each of the six line heads 21 ejects ink of a different color (for example, black, cyan, magenta, yellow, gray, and a special color other than the above colors).

[0044] The head holder 22 is a member on which each line head 21 is installed. The head holder 22 is made up of a box-shaped support member, and a plurality of installation holes are formed in the bottom surface of the head holder 22, into which each inkjet head of each line head 21 is fitted and installed. The installation holes are through-holes, and are formed so that the ink ejection surface of each inkjet head is exposed and arranged on the outside of the bottom surface of the head holder 22.

[0045] Then, as described above, the end of the printing medium P extending in the transport direction is pressed by the sheet member 30, while the printing medium P is transported directly below the image forming unit 20, and ink is ejected from each line head 21 onto the printing medium P, thereby performing a printing process on the printing medium P.

[0046] 5 is a block diagram showing a schematic configuration of a control system of the inkjet printing apparatus 1 of this embodiment. The control unit 50 includes a CPU (Central Processing Unit), a semiconductor memory, a hard disk, etc. The control unit 50 controls the operation of each unit of the inkjet printing apparatus 1 by executing a program stored in advance in a storage medium such as the semiconductor memory or the hard disk, and by operating electric circuits.

[0047] In particular, the control unit 50 of this embodiment controls the rotation speed of the drive motor of the suction fan 13 by changing the duty ratio of the drive voltage applied to the drive motor.

[0048] Here, the relationship between the combination of the width of the area where the sheet member 30 and the printing medium P do not overlap (W2 shown in FIG. 2) and the duty ratio of the drive voltage applied to the drive motor of the suction fan 13, and the pressing force (low, medium, high) that the sheet member 30 exerts on the end of the printing medium P extending in the transport direction, is shown in Table 1 below. As shown in Table 1 below, when the duty ratio of the drive voltage is the same, the pressing force increases as the width of the area where the sheet member 30 and the printing medium P do not overlap increases. Also, when the width of the area where the sheet member 30 and the printing medium P do not overlap is the same, the pressing force increases as the duty ratio increases.

[0049] [Table 1]

[0050] Therefore, in this embodiment, when the installation position of the sheet member 30 in the direction perpendicular to the transport direction is fixed, the control unit 50 controls the duty ratio of the drive voltage so that the greater the width of the print medium P in the direction perpendicular to the transport direction, the greater the duty ratio of the drive voltage. In other words, the control unit 50 controls the duty ratio of the drive voltage so that the smaller the width of the area where the sheet member 30 and the print medium P do not overlap, the greater the duty ratio of the drive voltage. This makes it possible to maintain the pressing force of the sheet member 30 against the edge of the print medium P regardless of the size of the print medium P, and to appropriately suppress warping of the print medium P.

[0051] In the present embodiment, as described above, the installation position of the sheet member 30 in the direction perpendicular to the transport direction is fixed, and the duty ratio of the drive voltage of the suction fan 13 is changed depending on the width of the print medium P. However, this control is not limited to this. For example, the duty ratio of the drive voltage of the suction fan 13 may be fixed, and the installation position of the sheet member 30 in the direction perpendicular to the transport direction may be changed depending on the width of the print medium P. Specifically, the installation position of the sheet member 30 may be changed depending on the width of the print medium P so that the area of ​​the range where the sheet member 30 and the print medium P do not overlap is constant. Even with this configuration, the pressing force of the sheet member 30 against the edge of the print medium P can be maintained regardless of the size of the print medium P, and warping of the print medium P can be appropriately suppressed.

[0052] To change the installation position of the sheet member 30 in the direction perpendicular to the conveying direction, a movement mechanism that moves the sheet member 30 in the direction perpendicular to the conveying direction may be provided in the holding mechanism 31. The movement of the sheet member 30 may be performed manually or automatically according to the width of the printing medium P.

[0053] Furthermore, in the above embodiment, the sheet member 30 is formed in a rectangular shape. However, this is not limited to this, and it may be formed in an L-shape as shown in FIG. 6 . That is, the sheet member 30 may be composed of a portion extending in the conveyance direction and a portion extending in a direction perpendicular to the conveyance direction. When the print medium P is inserted into the insertion opening between the sheet member 30 and the conveyance surface of the conveyor belt 11, if the print medium P is warped, for example, at the center of the downstream end, it may collide with the holding mechanism 31 and prevent smooth conveyance. Therefore, by forming the sheet member 30 in an L-shape as shown in FIG. 6 , it is possible to suppress the warping at the center of the downstream end of the print medium P and prevent it from colliding with the holding mechanism 31.

[0054] Furthermore, in the above embodiment, the inclined surface CL is formed on the sheet member 30 by passing the sheet member 30 through the slit S of the holding mechanism 31, but the configuration for forming the inclined surface CL is not limited to this and any other configuration may be used.

[0055] 7 is an external perspective view showing the configuration of a holding mechanism 40 that uses two plate members with inclined surfaces to form an inclined surface CL on a sheet member 30, instead of a slit S. Specifically, the holding mechanism 40 has a first plate member 41 and a second plate member 42 that are placed one on top of the other with a predetermined gap between them in the vertical direction relative to the conveying surface of the conveyor belt 11. The second plate member 42 is placed on top of the first plate member 41 with a predetermined gap between them.

[0056] Fig. 8 is a cross-sectional view of the holding mechanism 40 taken along line BB shown in Fig. 7. The vertical distance between the first plate member 41 and the second plate member 42 is set to be wider than the thickness of the sheet member 30, and the sheet member 30 is configured to be able to pass between the first plate member 41 and the second plate member 42.

[0057] The first plate member 41 is composed of a horizontal portion 41b having a sheet mounting surface 41a to which the upstream end of the sheet member 30 is attached, an inclined surface 41c extending from the horizontal portion 41b toward the upstream side, and an inclined surface 41d extending from the horizontal portion 41b toward the downstream side. The inclined surface 41c and the inclined surface 41d have inclined surfaces that slope downward from the upstream side toward the downstream side.

[0058] The second plate member 42 is composed of a horizontal portion 42a provided opposite the horizontal portion 41b of the first plate member 41, and an inclined portion 42b extending downstream from the horizontal portion 42a. The inclined portion 42b has an inclined surface that slopes downward from the upstream side to the downstream side.

[0059] Then, the sheet member 30 is passed between the first plate member 41 and the second plate member 42, and its upstream end is attached to the sheet attachment surface 41a of the first plate member 41. The upstream end of the sheet member 30 is attached to the sheet attachment surface 41a with, for example, double-sided tape or glue.

[0060] Then, when the portion extending from the upstream end of the sheet member 30 passes between the inclined portion 41d of the first plate member 41 and the inclined portion 42b of the second plate member 42, the portion extending from the upstream end of the sheet member 30 is bent, and an inclined surface CL is formed. The inclination angle θ of the inclined surface CL with respect to the conveying surface is preferably 20 degrees or more and 40 degrees or less.

[0061] As described above, the holding mechanism 40 holds the sheet member 30 so that the sheet member 30 is biased toward the conveying surface of the conveyor belt 11 by bending and tilting the portion extending from the upstream end of the sheet member 30. By biasing the sheet member 30 toward the conveying surface of the conveyor belt 11 in this way, the pressing force of the sheet member 30 against the end of the printing medium P on which it overlaps can be increased. Furthermore, the holding mechanism 40 forms the inclined surface CL by passing the sheet member 30 between the first plate member 41 and the second plate member 42, so it can be produced using a simpler method without requiring processing such as a slit.

[0062] The following additional notes are further disclosed regarding the conveying device of the present invention. (Addendum)

[0063] The conveying device of the present invention has a holding portion that holds the upstream end of the sheet member in the conveying direction, and the holding portion can hold the sheet member so that the sheet member is forced toward the conveying surface of the conveying portion by bending and tilting the portion extending from the upstream end of the sheet member.

[0064] In the conveying device of the present invention, the holding portion has a slit extending in a direction perpendicular to the conveying direction, and a slope can be formed by holding the upstream end of the sheet material through the slit from the vertical lower surface of the holding portion.

[0065] In the conveying device of the present invention, the holding section is two plate members that are stacked at a predetermined distance in the vertical direction relative to the conveying surface of the conveying section, and has two plate members with inclined surfaces that slope downward from the upstream side to the downstream side, and the inclination can be formed by holding the upstream end of the sheet member between the two plate members.

[0066] The transport device of the present invention has a control unit that controls the suction force of the transport unit, and the control unit can change the suction force depending on the width of the print medium in the direction perpendicular to the transport direction. [Explanation of symbols]

[0067] 1. Inkjet printing device 10 Transport unit 11 Conveyor belt 11a Suction hole 12 Platen roller 13 Suction fan 14 Conveyor roller 20 Image forming unit 21 Line Head 22 Head holder 30 Sheet material 31 Retention mechanism 31b Seat mounting surface 32 Metallic parts 33,34 Opening 40 Retention mechanism 41 First plate member 41a Seat mounting surface 41b Horizontal part 41c,41d slope part 42 Second plate member 42a Horizontal part 42b Slope section 50 control section CL inclined plane P Print media S slit

Claims

1. a conveying unit that adsorbs and conveys the print medium; a flexible sheet member extending in the transport direction of the transport unit, the sheet member being placed on the transport unit such that a portion of the sheet member overlaps an edge of the print medium extending in the transport direction, such that the remaining portion of the sheet member is attracted to the transport unit; a holding portion that holds an upstream end of the sheet member in the conveying direction, The holding portion has a slit extending in a direction perpendicular to the conveying direction, and holds the upstream end of the sheet material from the vertical underside of the holding portion through the slit, and holds the sheet material so that the sheet material is forced toward the conveying surface of the conveying portion by bending and tilting the portion extending from the upstream end of the sheet material.

2. a control unit for controlling the suction force of the conveying unit, The transport device according to claim 1 , wherein the control unit changes the suction force in accordance with the width of the print medium in a direction perpendicular to the transport direction.

Images