CN117657840A - Conveying device - Google Patents

Abstract

The invention provides a conveying device capable of stably sucking and conveying a printing medium and preventing image quality degradation caused by fog. The conveying device is provided with: a carrying belt (11) that adsorbs and carries the printing medium; and a sheet member (30) which is placed on the printing medium (P) conveyed by the conveying belt (11) and has flexibility, wherein the sheet member (30) covers a range corresponding to the periphery of a discharge portion for discharging liquid droplets onto the printing medium (P) on the conveying belt (11).

Description

Conveying device

Technical Field

The present invention relates to a conveying device for conveying a printing medium.

Background

Conventionally, an inkjet printing apparatus has been proposed which performs printing by ejecting ink from an inkjet head onto a printing medium while conveying the printing medium made of paper, film, or the like.

As a transport device for a printing medium in such an inkjet printing device, a transport device using a transport belt has been proposed. Specifically, the following conveying apparatus has been proposed: a suction fan is provided on a surface of the conveyance belt on the back side of the conveyance surface of the print medium, and the print medium is sucked onto the conveyance belt by generating negative pressure in a plurality of suction holes formed in the conveyance belt by rotation of the suction fan (for example, refer to patent document 1).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2009-280321

Disclosure of Invention

Problems to be solved by the invention

Here, in the suction conveying system as described above, the force (suction force) for sucking the printing medium is determined by the output of the suction fan for generating the negative pressure. In order to stably convey the printing medium without being separated from the conveying surface, a high suction force is required, and therefore, it is desirable that the output of the suction fan is as high as possible.

However, when the output of the suction fan is increased, wind (suction wind) due to suction is generated on the upper surface of the conveying belt, and the higher the output of the fan, the greater the speed of the suction wind becomes. In suction conveyance, mist (minute ink droplets other than the main droplet) generated at the time of ejecting ink flows out by the suction wind described above, and a phenomenon in which the droplet falls at a position distant from the main droplet occurs, resulting in image degradation in which an observed image is blurred. Fig. 11 is a view for explaining mist flowing out by suction wind.

Further, when the speed of the suction air increases, the distance from which the mist flows out increases, and the mist drops fall at a position farther from the main liquid drops, so that further deterioration of the image quality occurs.

In view of the above, an object of the present invention is to provide a conveyance device capable of stably sucking and conveying a printing medium and capable of preventing degradation of image quality due to fog.

Means for solving the problems

The carrying device of the present invention comprises: a transport unit that adsorbs and transports a printing medium; and a sheet member which is placed on the printing medium conveyed by the conveying section and has flexibility, wherein the sheet member covers a range of the conveying section corresponding to a periphery of a discharge section for discharging liquid droplets onto the printing medium.

Effects of the invention

According to the conveyance device of the present invention, since the sheet member is provided that is placed on the print medium to be suctioned and conveyed and has flexibility and covers the range of the conveyance section corresponding to the periphery of the ejection section, the print medium can be suctioned and conveyed stably, and deterioration of image quality due to fog can be prevented.

Drawings

Fig. 1 is a schematic view showing the configuration of an inkjet printing apparatus according to an embodiment of the present invention.

Fig. 2 is a diagram showing the conveying unit and the sheet member as viewed from above.

Fig. 3 is a diagram showing the arrangement of six inkjet heads included in one line head.

Fig. 4 is a view showing how ink ejected from the inkjet head drops on the printing medium through the holes formed in the sheet member.

Fig. 5 is a view showing a cross section of the holding mechanism shown in fig. 2 along line A-A.

Fig. 6 is a block diagram showing a schematic configuration of a control system of the inkjet printing apparatus.

Fig. 7 is a view showing another embodiment of the holding mechanism.

Fig. 8 is a view showing a cross section of an opening of the holding mechanism shown in fig. 7 taken along line B-B.

Fig. 9 is a view showing another embodiment of the holding mechanism.

Fig. 10 is a C-C cross-sectional view of the retaining mechanism shown in fig. 9.

Fig. 11 is a diagram for explaining a problem of a conventional inkjet printing apparatus.

Reference numerals illustrate:

1: an inkjet printing device;

10: a carrying unit;

11: carrying a belt;

11a: a suction hole;

12: an embossing roller;

13: a suction fan;

14: a carrying roller;

20: an image forming section;

21: a line head;

21a: an ink jet head;

22: a head holder;

30: a sheet member;

30a: a hole;

31: a holding mechanism;

32: a metal member;

35a: an inclined portion;

35b: a flat portion;

41: a holding mechanism;

43. 44: an opening portion;

50: a control unit;

60: a holding mechanism;

CL: an inclined surface;

p: a print medium;

s: a slit.

Detailed Description

An inkjet printing apparatus according to an embodiment of the present invention using a transport device will be described in detail below with reference to the drawings. Fig. 1 is a schematic configuration diagram of an inkjet printing apparatus 1 according to the present embodiment. Note that, the vertical and horizontal directions indicated by arrows in fig. 1 are the vertical and horizontal directions in the inkjet printing apparatus 1 of the present embodiment. The front side of the paper surface in fig. 1 is referred to as the front direction, and the back side is referred to as the back direction. In the present embodiment, the direction from left to right is the conveyance direction of the printing medium P.

As shown in fig. 1, the inkjet printing apparatus 1 of the present embodiment includes a conveyance unit 10 and an image forming unit 20.

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

The conveyance belt 11 and the platen roller 12 are supported by being directly supported by the housing of the inkjet printing apparatus 1 or by being indirectly suspended by members provided in the housing other than the housing.

The conveying belt 11 is an endless belt, and a plurality of suction holes 11a (white circles shown in fig. 2) for sucking the printing medium P are formed. The platen roller 12 is a roller extending in a direction (front-rear direction) orthogonal to the conveyance direction of the printing medium P. As shown in fig. 1, in the present embodiment, four platen rollers 12 are provided.

The conveying belt 11 is set up on the four platen rollers 12. One of the four embossing rollers is a driving roller, and the other three embossing rollers are driven rollers. The conveying belt 11 is moved by rotating the platen roller 12 as a driving roller, whereby the platen roller 12 as a driven roller rotates together with the conveying belt 11. Thereby, the printing medium P sucked to the conveying belt 11 is conveyed. In the present embodiment, the platen roller 12 rotates clockwise in fig. 1. Thereby, the printing medium P sucked to the conveying belt 11 is conveyed in the left-to-right direction in fig. 1. The left side shown in fig. 1 is the upstream side in the conveying direction, and the right side is the downstream side in the conveying direction.

On the back side of the transport surface of the print medium P in the transport belt 11, two suction fans 13 are provided on the upstream side and the downstream side. By rotating the suction fan 13, a negative pressure is generated in the suction holes 11a of the conveying belt 11, and the printing medium P is sucked to the conveying belt 11.

Seven conveying rollers 14 are provided above the conveying belt 11. The conveying roller 14 is provided above and near the conveying belt 11, and extends in a direction perpendicular to the conveying direction of the printing medium P. The conveying rollers 14 are disposed at predetermined intervals in the conveying direction. Specifically, the two rollers are provided on both sides in the conveyance direction of each line head 21 described later. Each of the conveying rollers 14 rotates counterclockwise in fig. 1, and conveys the printing medium P to the downstream side while pressing the printing medium P conveyed directly below from above.

Here, in order to stably convey the printing medium P without being separated from the conveying surface as described above, a high suction force is required, and therefore, it is desirable that the output of the suction fan 13 is as high as possible. However, when the output of the suction fan 13 is increased, wind (suction wind) due to suction is generated on the upper surface of the conveying belt 11, and ink mist (minute ink droplets other than the main droplet) flows out with the suction wind, which causes a problem of deterioration of image quality.

Therefore, the inkjet printing apparatus 1 of the present embodiment is provided with the sheet member 30 between the line head 21 and the conveying surface of the conveying belt 11. Fig. 2 is a view of the conveyance unit 10 and the sheet member 30 shown in fig. 1 as seen from above.

The sheet member 30 of the present embodiment is a sheet-like member that covers a range on the conveying belt 11 corresponding to the periphery of each inkjet head 21a constituting the line head 21. Specifically, the sheet member 30 has the same width as the conveying belt 11 in a direction (front-rear direction) orthogonal to the conveying direction of the print medium P, and is a rectangular sheet-like member extending to the downstream end portion of the conveying belt 11 in the conveying direction. In the sheet member 30, holes 30a are formed in a range corresponding to the ink discharge range of each inkjet head 21a, and ink discharged from each inkjet head 21a is dropped onto the printing medium P through the holes 30 a.

In the present 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 the present embodiment is configured by arranging six inkjet heads 21a in a staggered manner.

Thus, the holes 30a formed in the sheet member 30 are also formed in the ink ejection ranges of the inkjet heads 21a arranged alternately in the line heads 21.

Fig. 4 is a view showing how ink ejected from the inkjet head 21a is dropped onto the printing medium P through the hole 30a formed in the sheet member 30. As shown in fig. 4, the sheet member 30 is attracted to the suction hole 11a of the conveying belt 11 in a portion other than the range of the printing medium P. As a result, the sheet member 30 is often attracted to the conveying belt 11, and the printing medium P conveyed between the conveying belt 11 and the sheet member 30 is pressed by the sheet member 30, so that the printing medium P can be prevented from coming off the conveying belt 11. This can prevent the printing medium P from coming into contact with the inkjet head 21a due to warpage or the like of the printing medium P.

Further, since the conveyance belt 11, which is opened in the hole 30a of the sheet member 30, is located immediately below the nozzle of the inkjet head 21a and covers the periphery of the ink discharge range of the inkjet head 21a with the sheet member 30, suction air that causes mist to flow out to a position away from the main droplet is not generated under the inkjet head 21a. This can prevent image degradation due to ink mist generated during suction conveyance.

Further, by providing the sheet member 30 on the carrying belt 11, most of the suction holes 11a on the carrying belt 11 are blocked, and thus loss of the generated negative pressure is reduced. This can reduce the output of the suction fan 13 and reduce the power consumption, as compared with a case where the sheet member 30 is not provided.

Since the width of the hole 30a formed in the sheet member 30 in the conveying direction is a small width of the nozzle array of the inkjet head 21a, the print medium P does not come off the conveying surface due to the presence of the hole 30 a.

The sheet member 30 is formed of, for example, PET (polyethylene terephthalate: polyethylene terephthalate) and has a thickness of about 0.2 mm. The material of the sheet member 30 is not limited to PET, and any other material such as resin may be used as long as the sheet member 30 has flexibility to the extent that it can flex by its own weight. As the sheet member 30, for example, a film having irregularities on the surface such as a bead film is preferably used. In particular, the above-described irregularities are preferably formed on the surface of the sheet member 30 that contacts the printing medium P.

By using such a sheet member 30, it is possible to prevent contamination of the printing medium P due to ink being adsorbed to the sheet member 30 by contact of the printing surface of the printing medium P with the surface of the sheet member 30 and then transferred to the printing medium P.

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 absorbing material, a felt-like sheet (cloth-like) impregnated with ink by capillary force, a sponge-like member, or a cotton-like member can be used. This allows the sheet member 30 to absorb ink mist, and the replacement cycle can be prolonged.

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

Fig. 5 is a view showing a section of the holding mechanism 31 shown in fig. 2 along the line A-A. As shown in fig. 5, the holding mechanism 31 of the present embodiment is formed in a v-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 in the vertical direction toward the upstream side in the conveyance direction of the printing medium P, and the lowest portion of the inclined portion 35a is connected to the flat portion 35b. The inclination angle with respect to the conveying surface of the inclined portion 35a is about 20 degrees.

By forming the inclined portion 35a in this manner, the interval in the up-down direction of the insertion opening of the printing medium P formed between the holding mechanism 31 and the conveying surface of the conveying belt 11 can be increased. This can suppress the collision of the printing medium P against the holding mechanism 31.

Further, as shown in fig. 5, the upstream side end portion of the sheet member 30 is attached to the upper surface of the flat portion 35b by, for example, double-sided adhesive, glue, or the like.

The holding mechanism 31 is disposed above a predetermined distance from the conveying surface of the conveying belt 11, and the upper end portion of the sheet member 30 is bonded to the upper surface of the flat portion 35b of the holding mechanism 31 as described above, whereby the portion extending from the upper end portion of the sheet member 30 to the downstream side is configured to flex and tilt. By tilting the sheet member 30 in this manner, the sheet member 30 is biased against the conveying surface of the conveying belt 11, and the printing medium P can be pressed 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 about 30 degrees, 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 made larger. Further, by setting the inclination angle θ to 40 degrees or less, collision of the leading end of the printing medium P against the inclined surface CL of the sheet member 30 can be suppressed, and the leading end of the printing medium P can be smoothly conveyed between the sheet member 30 and the conveying surface.

The printing medium P inserted between the sheet member 30 and the conveying surface is conveyed toward the image forming portion at a predetermined conveying speed.

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

Each line head 21 includes a plurality of inkjet heads 21a, and the plurality of inkjet heads 21a include a plurality of nozzles that eject ink.

Each line head 21 extends in a direction perpendicular to the transport direction of the printing medium P, and ejects ink onto the printing medium P transported by the transport unit 10. As shown in fig. 1, six line heads 21 are arranged at predetermined intervals along the conveyance path of the printing medium P. The six line heads 21 are members that eject different colors (for example, black, cyan, magenta, yellow, gray, and special colors other than the above colors) respectively.

The head holder 22 is a member provided with each row of heads 21. The head holder 22 is composed of a box-shaped support member, and a plurality of mounting holes are formed in the bottom surface of the head holder 22, and the inkjet heads 21a of the respective line heads 21 are fitted into the mounting holes. The installation hole is a through hole 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.

As described above, the printing medium P is conveyed immediately below the image forming unit 20 while being pressed by the sheet member 30. The printing process is performed by ejecting ink from each line head 21 onto the printing medium P, and the ink ejected from each inkjet head 21a drops onto the printing medium P through the hole 30a of the sheet member 30.

Fig. 6 is a block diagram showing a schematic configuration of a control system of the inkjet printing apparatus 1 according to the present embodiment. The control unit 50 includes a CPU (Central Processing Unit: central processing unit), a semiconductor memory, a hard disk, and the like. The control unit 50 executes a program stored in advance in a storage medium such as a semiconductor memory or a hard disk, and operates an electric circuit to control operations of the respective units of the inkjet printing apparatus 1.

Next, another embodiment of the holding mechanism 31 in the inkjet printing apparatus 1 according to the present 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 according to the other embodiment are removed. In fig. 7, the hole 30a in the sheet member 30 is not shown.

The holding mechanism 41 is an elongated rectangular plate-like member extending in a direction orthogonal to the conveying direction. The holding mechanism 41 is formed with openings 43 and 44 for attaching the sheet member 30.

Fig. 8 is a view showing a cross section taken along line B-B of the opening 43 of the holding mechanism 41 shown in fig. 7. In the opening 43 of the holding mechanism 41, a height difference is formed at a position slightly lower than the upper surface 41a of the holding mechanism 41. The lower surface of the level difference of the holding mechanism 41 is a sheet attachment surface 41b, and the end of the sheet member 30 is attached to the sheet attachment surface 41 b. The end of the sheet member 30 is attached to the sheet attachment surface 41b by, for example, double-sided adhesive tape, glue, or the like.

In addition, a slit S extending in a direction orthogonal to the conveying direction is formed in the opening 43 of the holding mechanism 41. A portion extending from an upstream end portion (a portion attached to the sheet attachment surface 41 b) of the sheet member 30 passes through the slit S and is disposed below the holding mechanism 41.

As described above, the holding mechanism 41 passes through the slit S to hold the upstream end portion of the sheet member 30 by the sheet attachment surface 41b, and the portion extending from the upstream end portion of the sheet member 30 is disposed below the holding mechanism 41, and the inclined surface CL is formed by bending the portion extending from the upstream end portion of the sheet member 30 by the difference in height between the sheet attachment surface 41b and the lower surface 41c of the holding mechanism 41. In the present embodiment, the width of the slit S in the conveying direction is about 6mm, and the difference in height between the sheet attachment surface 41b and the lower surface 41c of the holding mechanism 41 is about 2 mm.

The holding mechanism 41 deflects and inclines a portion extending from an upstream end of the sheet member 30, thereby holding the sheet member 30 so that the sheet member 30 is biased against the conveying surface of the conveying belt 11. In this way, the sheet member 30 applies a force to the conveying surface of the conveying belt 11, and the pressing force to the end portions of the printing medium P stacked on the sheet member 30 can be increased.

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

The downstream end of the printing medium P supplied to the conveying belt 11 is inserted between the holding mechanism 41 and the conveying surface of the conveying belt 11. As shown in fig. 7, an inclined surface 41d is formed in the lower surface on the upstream side of the holding mechanism 41. The inclined surface 41d is an inclined surface that rises from the downstream side to the upstream side. The inclination angle of the conveyance surface with respect to the inclined surface 41d is about 20 degrees. By forming the inclined surface 41d in this manner, the interval in the up-down direction of the insertion opening of the printing medium P formed between the holding mechanism 41 and the conveying surface of the conveying belt 11 can be increased. This can suppress the collision of the printing medium P against the holding mechanism 41.

The printing 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 is inserted between the sheet member 30 and the conveying surface. In an upstream end of the lower surface 41c of the holding mechanism 41 below which the sheet member 30 is arranged, an inclined surface 41e connected to the lower surface 41c is formed. The inclined surface 41e is an inclined surface rising from the downstream side to the upstream side, similarly to the inclined surface 41d. The inclination angle of the conveyance surface with respect to the inclined surface 41e is about 45 degrees.

By setting the contact portion between the upper surface of the sheet member 30 and the holding mechanism 41 as an inclined surface instead of a right angle in this manner, the pressure per unit area on the upper surface of the sheet member 30 can be reduced, and thus the load on the sheet member 30 can be reduced, and the durability of the sheet member 30 can be improved.

Fig. 9 is an external perspective view showing a configuration of a holding mechanism 60 in which an inclined surface CL is formed on a sheet member 30 using a plate member having an inclined surface instead of the slit S as in the holding mechanism 41. 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 that are provided to overlap each other with a predetermined interval therebetween in the vertical direction with respect to the conveying surface of the conveying belt 11. The second plate member 52 is disposed on the first plate member 51 at a predetermined interval.

Fig. 10 is a C-C cross-sectional view of the retaining mechanism 60 shown in fig. 9. The interval in the vertical direction 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, and the sheet member 30 can pass between the first plate member 51 and the second plate member 52.

The first plate member 51 is constituted by: a horizontal portion 51b having a sheet mounting surface 51a to which an upstream-side end of the sheet member 30 is mounted; a slope portion 51c extending from the horizontal portion 51b toward the upstream side; a slope portion 51d extending from the horizontal portion 51b toward the downstream side. The slope surface portion 51c and the slope surface portion 51d have slope surfaces inclined in such a manner as to descend from the upstream side to the downstream side.

The second plate member 52 is constituted by: a horizontal portion 52a provided to be opposed to the horizontal portion 51b of the first plate member 51; and a slope portion 52b extending from the horizontal portion 52a toward the downstream side. The inclined surface portion 52b has an inclined surface inclined in such a manner as to descend from the upstream side to the downstream side.

Further, the sheet member 30 passes between the first plate member 51 and the second plate member 52, and an upstream end thereof is attached to the sheet attachment surface 51a of the first plate member 51. The upstream-side end of the sheet member 30 is attached to the sheet attachment surface 51a by, for example, double-sided tape, glue, or the like.

Further, the inclined surface CL is formed by bending a portion extending from the upstream-side end of the sheet member 30 by passing a portion extending from the upstream-side end of the sheet member 30 between the inclined surface portion 51d of the first plate member 51 and the inclined surface portion 52b of the second plate member 52. The inclination angle θ of the conveyance surface with respect to the inclined surface CL is preferably 20 degrees or more and 40 degrees or less.

The present invention is not limited to the above-described embodiments, and can be embodied by changing the constituent elements within a range not departing from the gist of the present invention in the implementation stage. In addition, various inventions can be formed by appropriate combinations of the plurality of constituent elements disclosed in the above embodiments. For example, the entire components shown in the embodiments may be appropriately combined. As described above, various modifications and applications can be made without departing from the gist of the invention.

The present invention relates to a conveying device, and further discloses the following supplementary notes.

(notes)

In the conveying device of the present invention, the sheet member may have a hole through which the droplet discharged from the discharge portion passes.

In the conveying device according to the present invention, the sheet member is held so that the sheet member is biased against the conveying surface of the conveying portion by the holding portion which holds the upstream end portion of the sheet member and deflects and tilts the portion extending from the upstream end portion of the sheet member.

In the conveying device according to the present invention, the printing medium can be passed between the sheet member and the conveying portion, and the surface of the sheet member, which is in contact with the printing medium, can be formed with irregularities.

Claims (4)

1. A carrying device, wherein,

the conveying device is provided with:

a transport unit that adsorbs and transports a printing medium; and

and a sheet member that is placed on the printing medium conveyed by the conveying section and has flexibility, wherein the sheet member covers a range of the conveying section corresponding to a periphery of a discharge section that discharges liquid droplets onto the printing medium.

2. The conveyance device according to claim 1, wherein the sheet member has a hole through which the droplet ejected from the ejection portion passes.

3. Handling device according to claim 1, wherein,

the conveying device has a holding portion that holds an end portion of the sheet member on an upstream side in the conveying direction,

the holding portion deflects and inclines a portion extending from an upstream end of the sheet member, thereby holding the sheet member so that the sheet member is biased against a conveying surface of the conveying portion.

4. Handling device according to claim 1, wherein,

the printing medium passes between the sheet member and the conveying portion,

the sheet member has irregularities on a surface thereof contacting the print medium.