JP2024038627A - Conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conveying device that can stably suck and convey a printing medium and prevent image quality from degrading due to mist.

SOLUTION: A conveying device includes: a conveyor belt 11 for conveying a printing medium P while sucking the printing medium; and a sheet member 30 having flexibility and placed on a printing medium P that is conveyed by the conveyor belt 11, the sheet member 30 covering a range over the conveyor belt 11 which corresponds to a periphery of a discharge part that discharges a liquid droplet to the printing medium P.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a conveyance device that conveys print media.

2. Description of the Related Art Conventionally, an inkjet printing apparatus has been proposed that prints by discharging ink onto a print medium from an inkjet head while conveying a print medium made of paper, film, or the like.

As a conveyance device for print media in such an inkjet printing apparatus, a conveyance device using a conveyance belt has been proposed. Specifically, a suction fan is installed on the back side of the print media conveying surface of the conveyor belt, and as the suction fan rotates, negative pressure is generated in the numerous suction holes formed in the conveyor belt. A conveyance device that adsorbs a print medium has been proposed (for example, see Patent Document 1).

JP2009-280321A

Here, in the suction conveyance method as described above, the force for suctioning the printing medium (suction force) is determined by the output of the suction fan for generating negative pressure. In order to stably transport the print medium so that the print medium does not separate from the transport surface, a high suction force is required, so it is desirable that the output of the suction fan be as high as possible.

However, when the output of the suction fan is increased, wind due to suction (suction wind) is generated on the upper surface of the conveyor belt, and the higher the output of the fan, the higher the speed of the suction air. In suction conveyance, the mist (small ink droplets other than the main droplet) generated when ink is ejected is swept away by the suction wind described above, and a phenomenon occurs where it lands at a position away from the main droplet, causing the image to appear blurry. Deterioration occurs. FIG. 11 is a diagram for explaining mist that is blown away by suction wind.

Furthermore, as the speed of the suction air increases, the distance over which the mist is swept increases, and the mist lands at a position further away from the main droplet, resulting in further deterioration of image quality.

SUMMARY OF THE INVENTION In view of the above circumstances, it is an object of the present invention to provide a conveyance device that can stably suction convey a print medium and prevent deterioration of image quality due to mist.

The conveyance device of the present invention includes a conveyance section that attracts and conveys a print medium, and a flexible sheet member that is placed on the print medium conveyed by the conveyance section, and the conveyance device includes a conveyance section that attracts and conveys a print medium, and a flexible sheet member that is placed on the print medium that is conveyed by the conveyance section. and a sheet member that covers an area on the conveying section corresponding to the periphery of the discharging section.

According to the conveyance device of the present invention, a flexible sheet member is provided that is placed on the print medium to be sucked and conveyed and covers an area on the conveyance section corresponding to the periphery of the discharge section. This makes it possible to stably suction and convey the print medium, and to prevent image quality from deteriorating due to mist.

A diagram showing a schematic configuration of an inkjet printing device using an embodiment of a conveyance device of the present invention Top view of the transport unit and sheet member Diagram showing the arrangement of six inkjet heads included in one line head A diagram showing how ink ejected from an inkjet head passes through holes formed in a sheet member and lands on a print medium. A diagram showing a cross-sectional view taken along line AA of the holding mechanism shown in FIG. Block diagram showing a schematic configuration of a control system of an inkjet printing device Diagrams showing other embodiments of the retention mechanism A diagram showing a cross-sectional view taken along line BB of the opening of the holding mechanism shown in FIG. Diagrams showing other embodiments of the retention mechanism A sectional view taken along the line CC of the holding mechanism shown in FIG. Diagram to explain issues with conventional inkjet printing devices

DESCRIPTION OF THE PREFERRED EMBODIMENTS An inkjet printing apparatus using an embodiment of a conveyance apparatus of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an inkjet printing apparatus 1 of this embodiment. Note that 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. Further, with respect to the paper surface of FIG. 1, the front side is the front direction, and the back side is the rear direction. Further, in this embodiment, the direction from left to right is the conveyance direction of the print medium P.

The inkjet printing apparatus 1 of this embodiment includes a transport unit 10 and an image forming section 20, as shown in FIG.

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

The conveyor belt 11 and the platen roller 12 are suspended and supported directly from the casing of the inkjet printing apparatus 1 or indirectly from a member other than the casing provided in the casing.

The conveyance belt 11 is an annular belt, and has a large number of suction holes 11a (white circles shown in FIG. 2) formed therein for suctioning the print medium P. The platen roller 12 is a roller that extends in a direction (front-back direction) orthogonal to the conveyance direction of the print medium P. In this embodiment, as shown in FIG. 1, four platen rollers 12 are provided.

The conveyor belt 11 is stretched around the four platen rollers 12 described above. One of the four platen rollers is a driving roller, and the remaining three platen rollers are driven rollers. As the platen roller 12, which is a driving roller, rotates, the conveyor belt 11 moves, and the platen roller 12, which is a driven roller, rotates together with the conveyor belt 11. As a result, the print medium P attracted to the conveyor belt 11 is conveyed. In this embodiment, the platen roller 12 rotates clockwise in FIG. 1 . As a result, the print medium P attracted to the conveyor belt 11 is conveyed from left to right in FIG. 1 . The left side shown in FIG. 1 is the upstream side in the conveyance direction, and the right side is the downstream side in the conveyance direction.

Two suction fans 13 are provided on the back side of the conveyance surface of the print medium P on the conveyance belt 11, one on the upstream side and the other on the downstream side. As the suction fan 13 rotates, negative pressure is generated in the suction holes 11a of the conveyor belt 11, and the print medium P is thereby attracted to the conveyor belt 11.

Seven conveyance rollers 14 are provided above the conveyance belt 11. The conveyance roller 14 is a roller that is provided near the upper side of the conveyance belt 11 and extends in a direction perpendicular to the conveyance direction of the print medium P. The conveyance rollers 14 are arranged at predetermined intervals in the conveyance direction. Specifically, they are provided on both sides of each line head 21 in the transport direction, which will be described later. Each conveyance roller 14 is a roller that rotates clockwise in FIG. 1 and sends out the print medium P conveyed directly below it downstream while pressing it from above.

Here, as described above, in order to stably transport the print medium P so that the print medium P does not separate from the transport surface, a high suction force is required, so the output of the suction fan 13 should be as high as possible. is desirable. However, when the output of the suction fan 13 is increased, suction wind (suction wind) is generated on the upper surface of the conveyor belt 11, and ink mist (fine ink droplets other than the main droplets) is swept away by the suction wind, resulting in poor image quality. There is a problem of deterioration.

Therefore, in the inkjet printing apparatus 1 of this embodiment, the sheet member 30 is provided between the line head 21 and the conveying surface of the conveying belt 11. FIG. 2 is a diagram of the transport unit 10 and sheet member 30 shown in FIG. 1 viewed from above.

The sheet member 30 of this embodiment is a sheet-like member that covers an area on the conveyor belt 11 corresponding to the periphery of each inkjet head 21 a that constitutes the line head 21 . Specifically, the sheet member 30 has the same width as the conveyor belt 11 in the direction (front-back direction) perpendicular to the conveyance direction of the print medium P, and extends to the downstream end of the conveyor belt 11 in the conveyance direction. It is a rectangular sheet-like member. A hole 30a is formed in the sheet member 30 in a range corresponding to the ink ejection range of each inkjet head 21a, and the ink ejected from each inkjet head 21a passes through the hole 30a and is transferred to the print medium. The bullet lands on.

In this embodiment, each line head 21 includes six inkjet heads 21a. FIG. 3 is a diagram showing the arrangement of six inkjet heads 21a included in one line head 21. As shown in FIG. 3, the line head 21 of this embodiment includes six inkjet heads 21a arranged in a staggered manner.

Therefore, the holes 30a formed in the sheet member 30 are also formed in the ink ejection range of each inkjet head 21a of each line head 21 arranged in a staggered manner.

FIG. 4 is a diagram showing how ink ejected from the inkjet head 21a passes through holes 30a formed in the sheet member 30 and lands on the printing medium P. As shown in FIG. 4, the sheet member 30 is attracted to the suction hole 11a of the conveyor belt 11 in a portion other than the print medium P. As a result, since the sheet member 30 is always attracted to the conveyor belt 11, the print medium P conveyed between the conveyor belt 11 and the sheet member 30 is held down by the sheet member 30, and is prevented from separating from the conveyor belt 11. It can be prevented. This can prevent the print medium P from coming into contact with the inkjet head 21a due to warpage of the print medium P or the like.

Further, the holes 30a made in the sheet member 30 are located directly below the nozzles of the inkjet head 21a, and the sheet member 30 covers the conveyor belt 11 around the ink ejection range of the inkjet head 21a. Suction wind that causes the mist to flow away from the main droplet is no longer generated under the inkjet head 21a. This makes it possible to prevent image deterioration due to ink mist generated during suction conveyance.

Furthermore, by providing the sheet member 30 on the conveyor belt 11, most of the suction holes 11a on the conveyor belt 11 are closed, so that the loss of generated negative pressure is reduced. Thereby, the output of the suction fan 13 can be lowered and the power consumption can be lowered than in the case of a configuration in which the sheet member 30 is not provided.

Note that the width of the hole 30a formed in the sheet member 30 in the conveyance direction is a small width corresponding to the nozzle row of the inkjet head 21a, so the presence of the hole 30a prevents the print medium P from separating from the conveyance surface.

The sheet member 30 is made of, for example, PET (polyethylene terephthalate) and has a thickness of about 0.2 mm. The material for the sheet member 30 is not limited to PET, but other materials such as resin may be used as long as the sheet member 30 has flexibility to the extent that it bends under its own weight. Further, as the sheet member 30, it is preferable to use a film having an uneven surface, such as a bead film. In particular, it is preferable to form the above-mentioned irregularities on the surface where the sheet member 30 and the printing medium P come into contact.

By using such a sheet member 30, the printed surface of the print medium P comes into contact with the surface of the sheet member 30, so that ink adheres to the sheet member 30, and this is retransferred to the print medium P. Contamination can be prevented.

Further, the surface of the sheet member 30 on the line head 21 side may be made of a material such as an absorbent material. As the absorbent material, a felt-like (cloth-like) member, a sponge-like member, or a cotton-like member into which the ink permeates by capillary force can be used. Thereby, the ink mist can be absorbed by the sheet member 30, and the replacement cycle can be lengthened.

Further, the upstream end of the sheet member 30 is held by a holding mechanism 31. The holding mechanism 31 is an elongated rectangular plate member extending in a direction (front-back direction) orthogonal to the conveyance direction. The holding mechanism 31 is screwed to metal members 32 provided on both sides of the conveyor belt 11 in a direction orthogonal to the conveyance direction.

FIG. 5 is a cross-sectional view taken along line AA around the holding mechanism 31 shown in FIG. As shown in FIG. 5, the holding mechanism 31 of this embodiment is formed into a dogleg shape in cross section and has an inclined portion 35a and a flat portion 35b. The inclined portion 35a of the holding mechanism 31 is formed to rise vertically upward toward the upstream side in the conveyance direction of the print medium P, and the lowest portion of the inclined portion 35a is connected to the flat portion 35b. The angle of inclination of the inclined portion 35a with respect to the conveying surface is about 20 degrees.

By forming the inclined portion 35a in this manner, it is possible to increase the distance in the vertical direction between the insertion opening for the print medium P formed between the holding mechanism 31 and the conveying surface of the conveying belt 11. Thereby, collision of the print medium P with the holding mechanism 31 can be suppressed.

As shown in FIG. 5, the upstream end of the sheet member 30 is attached to the upper surface of the flat portion 35b using, for example, double-sided tape or glue.

The holding mechanism 31 is installed a predetermined distance above the conveying surface of the conveying belt 11, and as described above, by bonding the upper end of the sheet member 30 to the upper surface of the flat part 35b of the holding mechanism 31, The sheet member 30 is configured to bend and tilt a portion extending from the upper end toward the downstream side. By inclining the sheet member 30 in this manner, the sheet member 30 is urged toward the conveying surface of the conveying belt 11, thereby making it possible to press the print medium P against the conveying surface.

The inclination angle θ of the inclined surface CL of the sheet member 30 with respect to the conveying surface is approximately 30 degrees, but is preferably 20 degrees or more and 40 degrees or less. 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 end of the printing medium P with the inclined surface CL of the sheet member 30 can be suppressed, and the leading end of the printing medium P can be moved between the sheet member 30 and the conveying surface. can be sent smoothly between

Then, the print medium P inserted between the sheet member 30 and the conveyance surface is conveyed toward the image forming section 20 at a predetermined conveyance speed.

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

Each line head 21 includes a plurality of inkjet heads 21a each having a plurality of nozzles that eject ink.

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

The head holder 22 is a member on which each line head 21 is installed. The head holder 22 is composed of a box-shaped support member, and the bottom surface of the head holder 22 is formed with a plurality of installation holes into which each inkjet head 21a of each line head 21 is fitted and installed. . The installation hole is a through hole, and is formed so that the ink ejection surface of each inkjet head 21a is exposed to the outside of the bottom surface of the head holder 22.

Then, as described above, the print medium P is conveyed directly below the image forming section 20 while being pressed by the sheet member 30 . Ink is ejected from each line head 21 onto the printing medium P, and the ink ejected from each inkjet head 21a passes through the hole 30a of the sheet member 30 and lands on the printing medium P, thereby performing printing processing. be done.

FIG. 6 is a block diagram showing a schematic configuration of the 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, and the like. The control section 50 controls the operation of each section of the inkjet printing apparatus 1 by executing a program stored in advance in a storage medium such as a semiconductor memory or a hard disk and operating an electric circuit.

Next, other embodiments of the holding mechanism 31 in the inkjet printing apparatus 1 of this embodiment will be described. FIG. 7 is an external perspective view showing a state in which the holding mechanism 41 and the sheet member 30 of another embodiment are removed. Note that in FIG. 7, the hole 30a in the sheet member 30 is not shown.

The holding mechanism 41 is an elongated rectangular plate member extending in a direction perpendicular to the conveying direction. The holding mechanism 31 has openings 43 and 44 for attaching the sheet member 30.

FIG. 8 is a cross-sectional view taken along line BB of the opening 43 of the holding mechanism 41 shown in FIG. A step is formed in the opening 43 of the holding mechanism 41 at a position slightly lower than the upper surface 41a of the holding mechanism 41. The surface below the step of this holding mechanism 41 is a seat attachment surface 41b, and the end portion of the sheet member 30 is attached onto the seat attachment surface 41b. The end portion of the sheet member 30 is attached onto the sheet attachment surface 41b using, for example, double-sided tape or glue.

Further, a slit S extending in a direction perpendicular to the conveyance direction is formed in the opening 43 of the holding mechanism 41. A portion of the sheet member 30 extending from the upstream end (the portion attached to the sheet attachment surface 41b) is passed through the slit S and placed below the holding mechanism 41.

As described above, the holding mechanism 41 holds the upstream end of the sheet member 30 through the slit S on the sheet attachment surface 41b, and the portion extending from the upstream end of the sheet member 30 is held on the lower side of the holding mechanism 41. By arranging the seat member 30, the portion extending from the upstream end of the seat member 30 is bent due to the difference in level between the seat attachment surface 41b and the lower surface 41c of the holding mechanism 41, thereby 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 difference between the sheet attachment surface 41b and the lower surface 41c of the holding mechanism 41 is about 2 mm.

The holding mechanism 41 holds the sheet member 30 so that the sheet member 30 is biased toward the conveyance surface of the conveyor belt 11 by bending and tilting a portion extending from the upstream end of the sheet member 30. . In this way, by urging the sheet member 30 toward the conveyance surface of the conveyor belt 11, it is possible to further increase the pressing force against the end portion of the print medium P overlapping with the sheet member 30.

The inclination angle θ of the inclined surface CL with respect to the conveying surface is approximately 30 degrees, as in the above embodiment, but is preferably 20 degrees or more and 40 degrees or less.

The downstream end of the print medium P supplied to the conveyor belt 11 is inserted between the holding mechanism 41 and the conveyance surface of the conveyor belt 11 . An inclined surface 41d is formed on the lower surface of the upstream side of the holding mechanism 41, as shown in FIG. The inclined surface 41d is an inclined surface that rises from the downstream side toward the upstream side. The angle of inclination of the inclined surface 41d with respect to the conveying surface is about 20 degrees. By forming the inclined surface 41d in this manner, it is possible to increase the distance in the vertical direction between the insertion opening for the print medium P formed between the holding mechanism 41 and the conveying surface of the conveying belt 11. Thereby, collision of the print medium P with the holding mechanism 41 can be suppressed.

The print medium P inserted between the holding mechanism 41 and the conveying surface of the conveying belt 11 is conveyed downstream by the conveying belt 11 and inserted between the sheet member 30 and the conveying surface. An inclined surface 41e continuous to the lower surface 41c is formed at the upstream end of the lower surface 41c of the holding mechanism 41 below which the sheet member 30 is disposed. The inclined surface 41e, like the inclined surface 41d, is an inclined surface that rises from the downstream side toward the upstream side. The angle of inclination of the inclined surface 41e with respect to the conveying surface is about 45 degrees.

By making the contact portion between the upper surface of the sheet member 30 and the holding mechanism 41 not at right angles but at an inclined surface in this way, the pressure per unit area against the upper surface of the sheet member 30 can be reduced. The load can be reduced and the durability of the sheet member 30 can be improved.

FIG. 9 is an external perspective view showing the configuration of a holding mechanism 60 that forms an inclined surface CL on the sheet member 30 using two plate members having inclined surfaces instead of the slit S as in the holding mechanism 41 described above. be. Note that in FIG. 9, the hole 30a in the sheet member 30 is not shown.

Specifically, the holding mechanism 60 includes a first plate member 51 and a second plate member 52, which are placed one on top of the other at a predetermined interval in the vertical direction with respect to the conveying surface of the conveying belt 11. A second plate member 52 is arranged on the first plate member 51 at a predetermined interval.

FIG. 10 is a sectional view taken along line CC of the holding mechanism 60 shown in FIG. The vertical distance between the first plate member 51 and the second plate member 52 is set to be wider than the thickness of the sheet member 30. The sheet member 30 is configured to be able to pass between them.

The first plate member 51 includes a horizontal portion 51b having a sheet attachment surface 51a to which the upstream end of the sheet member 30 is attached, and a sloped portion 51c extending from the horizontal portion 51b toward the upstream side. It is composed of a slope portion 51d extending from the horizontal portion 51b toward the downstream side. The slope portion 51c and the slope portion 51d have slopes that slope downward from the upstream side to the downstream side.

The second plate member 52 includes a horizontal portion 52a provided opposite to the horizontal portion 51b of the first plate member 51, and a sloped portion 52b extending downstream from the horizontal portion 52a. has been done. The slope portion 52b has a slope that slopes downward from the upstream side to the downstream side.

Then, the sheet member 30 is passed between the first plate member 51 and the second plate member 52, and the upstream end thereof is attached onto the sheet attachment surface 51a of the first plate member 51. The upstream end of the sheet member 30 is attached onto the sheet attachment surface 51a using, for example, double-sided tape or glue.

Then, the portion extending from the upstream end of the sheet member 30 is passed between the slope portion 51d of the first plate member 51 and the slope portion 52b of the second plate member 52. A portion of the sheet member 30 extending from the upstream end is bent, forming an inclined surface CL. 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.

It should be noted that the present invention is not limited to the above-described embodiments, and can be embodied by modifying the constituent elements within the scope of the invention at the implementation stage. Moreover, various inventions can be formed by appropriately combining the plurality of components disclosed in the above embodiments. For example, all the components shown in the embodiments may be combined as appropriate. It goes without saying that various modifications and applications can be made without departing from the spirit of the invention.

Regarding the conveyance device of the present invention, the following additional notes are further disclosed.
(Additional note)

In the conveying device of the present invention, the sheet member can have holes through which droplets discharged from the discharge section pass.

The conveying device of the present invention has a holding part that holds the upstream end of the sheet member in the conveying direction, and the holding part bends and tilts a portion extending from the upstream end of the sheet member. Accordingly, the sheet member can be held so as to be biased toward the conveying surface of the conveying section.

In the conveyance device of the present invention, the print medium can be passed between the sheet member and the conveyance section, and unevenness can be formed on the surface of the sheet member that comes into contact with the print medium.

1 Inkjet printing device 10 Conveyance unit 11 Conveyance belt 11a Suction hole 12 Platen roller 13 Suction fan 14 Conveyance roller 20 Image forming section 21 Line head 21a Inkjet head 22 Head holder 30 Sheet member 30a Hole 31 Holding mechanism 32 Metal member 35a Inclined portion 35b Flat part 41 Holding mechanisms 43, 44 Opening part 50 Control part 60 Holding mechanism CL Inclined surface P Print medium S Slit

Claims (4)

A transport unit that absorbs and transports the print medium;
A flexible sheet member placed on a print medium conveyed by the conveyance section, the sheet member covering an area on the conveyance section corresponding to a periphery of a discharge section that discharges droplets onto the print medium. A conveying device equipped with a sheet member. The conveying device according to claim 1, wherein the sheet member has holes through which droplets discharged from the discharge section pass. a holding part that holds an upstream end of the sheet member in the conveying direction;
The holding section holds the sheet member so that the sheet member is biased toward the conveyance surface of the conveyance section by bending and tilting a portion extending from the upstream end of the sheet member. The conveying device according to claim 1. The printing medium passes between the sheet member and the conveyance section,
The conveying device according to claim 1, wherein unevenness is formed on a surface of the sheet member that comes into contact with the printing medium.