CONVEYANCE APPARATUS

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2024-093381 filed on Jun. 10, 2024, the entire contents of which are incorporated herein by reference.

FIELD

Embodiments discussed herein are related to a conveyance apparatus that conveys a medium.

BACKGROUND

In the related art, methods of guiding sheets toward pairs of rollers that convey the sheets while nipping the sheets are known. For example, a method of guiding the leading end of a sheet to a driven roller side having a smaller frictional force of a pair of rollers is known (see, for example, JP 05-032350 A). A method of guiding a sheet by rib-shaped guides disposed on one side, the other side, and the like in an axial direction of a driven roller is also known (see, for example, JP 2020-040819 A).

SUMMARY

According to one aspect, a conveyance apparatus includes a pair of rollers configured to convey a medium while nipping the medium; a nip guide configured to hold one roller between the pair of rollers and guide the medium toward the pair of rollers; and an elastic body configured to bias the nip guide and the one roller such that the one roller is pressed against the other roller between the pair of rollers. The nip guide includes a guide plate that expands in a width direction of the medium and a conveyance direction of the medium and guides the medium toward the pair of rollers.

An object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view illustrating an internal structure of an inkjet printing apparatus according to an embodiment;

FIG. 2 is a block diagram illustrating a control configuration of the inkjet printing apparatus according to the embodiment;

FIG. 3 is a cross-sectional view illustrating a curved conveyance path according to the embodiment;

FIG. 4 is a perspective view illustrating a nip guide and a driven roller according to the embodiment;

FIG. 5 is a perspective view illustrating the driven roller according to the embodiment;

FIG. 6 is a perspective view illustrating the nip guide according to the embodiment;

FIG. 7 is an enlarged view illustrating a portion VII in FIG. 3; and

FIG. 8 is a perspective view illustrating the driven roller with the nip guide and a bearing according to the embodiment.

DETAILED DESCRIPTION

Incidentally, when a medium such as a sheet is conveyed after formation of an image, a coating roller coated with fine particles such as ceramic particles or a mesh roller covered with knitting is generally used in order to bring the roller into point contact with the medium in order to cope with re-transfer by the roller. In order to prevent accumulation of paper dust or the like on the roller, it is important for the unevenness of the roller to be large, and the mesh roller is particularly excellent. However, when the unevenness of the roller becomes large, a medium tip comes into contact with not a nip point of the pair of rollers but the antinode of the roller due to curvature of a conveyance path and the protrusion amount of the roller, and the medium tip tends to be easily damaged.

As described above, in the method of guiding the leading end of a sheet to the driven roller side on which a frictional force is small in the pair of rollers, the leading end of the sheet is required to be guided significantly closer to the driven roller side in consideration of variations in components, and thus there is concern of rear-end collision noise occurring due to hitting of the leading end of the sheet against the roller. This collision noise is generated particularly in a mesh roller or a curved conveyance path, but may also be generated in a roller or a straight conveyance path with no unevenness on the surface.

When a medium is guided by the rib-shaped guide, the guide easily becomes worn and the durability and strength are low because a contact surface between the medium and the guide is small. If the thickness of the rib-shaped guide in the thickness direction of a medium is increased in order to enhance durability and strength, the medium may not be guided near a nip area where the pair of rollers nips the medium when a position of the guide in the axial direction of the pair of rollers is set to the same as the position of the pair of rollers. Accordingly, as described above, it is not possible to prevent occurrence of rear-end collision noise or damage to a medium due to hitting of the medium against rollers.

Hereinafter, a conveyance apparatus according to an embodiment of the present invention will be described with reference to the drawings, with an example of the conveyance apparatus being an inkjet printing apparatus.

FIGS. 1 and 2 are a front view illustrating an internal structure of an inkjet printing apparatus 1 and a block diagram illustrating a control configuration thereof.

Each of up-down, front-rear, and left-right directions illustrated in FIGS. 1 and 3 to 8 to be described below is an example for convenience of description. For example, the up-down direction is a vertical direction, and the front-rear direction and the left-right direction are horizontal directions.

As illustrated in FIG. 1, the inkjet printing apparatus 1 includes an apparatus housing 2, an external sheet feeder 10, an internal sheet feeder 20, an inkjet head 40, a print conveyor 50, and a sheet ejector 60. As illustrated in FIG. 2, the inkjet printing apparatus 1 further includes a control unit 81, a storage unit 82, an interface unit 83, and a conveyance drive unit 84.

In FIG. 1, a conveyance path of a sheet P from the external sheet feeder 10 or the internal sheet feeder 20 to the sheet ejector 60 is indicated by a solid line, and a switchback path 34 for double-side printing is indicated by a broken line. The sheet P in the embodiment is an example of a medium. The medium may be a sheet-like medium made of a material other than paper, a medium having a folded portion such as an envelope, or the like. Therefore, in the present specification, sheet feeding is an example of supply, and sheet ejection is an example of discharge. Accordingly, sheet feeding can be replaced with supply, sheet ejection can be replaced with discharge, and a sheet can be replaced with a medium.

In the embodiment, the inkjet printing apparatus 1 will be described as an example of a conveyance apparatus, but the conveyance apparatus may be any apparatus that conveys the sheet P (medium). Therefore, the conveyance apparatus according to the embodiment may be a processing apparatus including a processing unit that performs processing other than image formation such as inspection on the sheet P, a conveyance apparatus not including such a processing unit, or the like.

The external sheet feeder 10 includes a sheet feeding tray 11, a sheet feeding roller 12, and a separating plate 13. The external sheet feeder 10 is an example of a feeder and is disposed to be exposed to, for example, the outside of the apparatus housing 2 and feeds the sheet P into the apparatus housing 2. The sheet P before image formation is piled on the sheet feeding tray 11. For example, two sheet feed rollers 12 are disposed side by side in a conveyance direction D of the sheet P, and feed and convey the uppermost sheet P among the plurality of sheets P piled on the sheet feeding tray 11. The separating plate 13 sandwiches the sheet P with the sheet feeding roller 12 and separates the sheet P one by one.

The internal sheet feeder 20 includes a first sheet feeder 21, a second sheet feeder 22, and a third sheet feeder 23. The first sheet feeder 21, the second sheet feeder 22, and the third sheet feeder 23 are arrayed in this order from above inside the apparatus housing 2. Each of the first sheet feeder 21, the second sheet feeder 22, and the third sheet feeder 23 includes sheet feeding trays 21a, 22a, and 23a on which the sheets P before image formation are piled, and sheet feeding rollers 21b, 22b, and 23b that feed and convey the uppermost sheet P among the plurality of sheets P piled on the sheet feeding trays 21a, 22a, and 23a.

The inkjet printing apparatus 1 further includes a plurality of pairs of rollers 31, a path switching unit 32, a pair of switchback rollers 33, a switchback path 34, and conveyance paths 35 and 36 illustrated in FIG. 3.

For example, the pair of rollers 31 conveys the sheet P while nipping the sheet P along the conveyance path of the sheet P inside the apparatus housing 2.

The path switching unit 32 switches the conveyance path of the sheet P on which the image has been formed by the inkjet head 40 between a path leading to the sheet ejector 60 and the switchback path 34. The path switching unit 32 is, for example, a flapper. The pair of switchback rollers 33 switches back and conveys the sheet P along the switchback path 34 to reverse the front and back sides of the sheet P. The switchback path 34 is used to circulate the sheet P for double-side printing and re-feed the sheet P to the inkjet head 40.

The inkjet head 40 is, for example, a line type inkjet head that includes one or more head modules having a plurality of nozzles for ejecting ink, and ejects ink to the sheet P conveyed by the pair of rollers 31, the print conveyor 50 to be described below, or the like. Thus, the inkjet head 40 forms an image on the sheet P. The inkjet head 40 is an example of an image forming unit. An image forming method is not limited to inkjet printing.

The print conveyor 50 is disposed to face the inkjet head 40 and conveys the sheet P. The print conveyor 50 includes a plurality of pulleys 51, a belt 52 stretched around the pulleys 51, and a suction fan 53 that sucks air through a plurality of holes formed in the belt 52 to cause the belt 52 to adsorb the sheet P. The print conveyor 50 may include a conveyance member other than the belt 52 such as a roller or may not adsorb the sheet P. The print conveyor 50 functions as an example of a conveyance unit that conveys the sheet P together with the pair of rollers 31 and the like. The conveyance unit may include a conveyance member such as a roller or a belt.

The sheet ejector 60 includes a sheet ejection tray 61 and a sheet ejection roller 62. The sheet ejector 60 is an example of an ejector and is disposed, for example, to be exposed to the outside of the apparatus housing 2 and ejects the sheet P to the outside of the apparatus housing 2. The sheet P on which an image has been formed is piled on the sheet ejection tray 61. For example, a pair of upper and lower sheet ejection rollers 62 is disposed and conveys the sheet P toward the sheet ejection tray 61.

The inkjet printing apparatus 1 further includes a nip guide 70 illustrated in FIGS. 3, 4, 6, and 7. The nip guide 70 is made of, for example, a plastic material and includes a guide plate 71, a pair of support portions 72 and 73, a base portion 74, and a plurality of reinforcement ribs 75 as illustrated in FIG. 6.

The nip guide 70 holds the driven roller 31a of the pair of rollers 31. The driven roller 31a held by the nip guide 70 is provided along a conveyance path (see FIG. 3) curved upward for conveying the sheet P on which the image has been formed by the inkjet head 40. The nip guide 70 holds the driven roller 31a, so that a relative position of the nip guide 70 to the driven roller 31a (such as the protrusion amount of the driven roller 31a from the guide plate 71) can be made constant. The pair of rollers 31 may include, for example, a coating roller coated with fine particles such as ceramic particles and a mesh roller covered with knitting.

The pair of rollers 31 illustrated in FIG. 3 is disposed in the vicinity between the conveyance paths 35 and 36, each of which is formed of a pair of curved plate-like members. The pair of rollers 31 includes the driven roller 31a and a driving roller 31b. Two nip guides 70 and two pairs of rollers 31 each having the driven roller 31a held by the nip guides 70 are disposed side by side in a width direction W of the sheet P. However, the number of sets of the nip guides 70 and the pairs of rollers 31 may be any number of one or more. The nip guide 70 and the pair of rollers 31 may be disposed at a plurality of positions different in the conveyance direction D.

As illustrated in FIG. 4, the guide plate 71 spreads in the width direction W of the sheet P and the conveyance direction D of the sheet P, and guides the sheet P toward the pair of rollers 31. The guide plate 71 may have a thin flat plate shape. The guide plate 71 may spread by a length that is half or more of the length of the driven roller 31a in the width direction W of the sheet P, and preferably spreads over the entire region of the driven roller 31a.

As illustrated in FIG. 7, the guide plate 71 enters a space S (as illustrated by a two-dot chain line, the space S sandwiched between the driven roller 31a and the driving roller 31b) between the pair of rollers 31. Preferably, the guide plate 71 spreads in the conveyance direction D in the space S by a length L2 that is half or more of a length L1 in the conveyance direction D in the space S up to a nip area N (an area where the pair of rollers 31 nips the sheet P). The guide plate 71 may be disposed such that the nip area N is located on an extension line of a contact surface with the sheet P in the conveyance direction D. The guide plate 71 spreads to cross the conveyance path of the sheet P continuing from the conveyance path 35, so that the sheet P can be guided while coming in contact with the sheet P. Since the pair of rollers 31 has elasticity, the nip area N is not a linear shape spreading only in the width direction W of the sheet P but an area spreading in the width direction W and the conveyance direction D. It is desirable that the upper end (the downstream end in the conveyance direction D) of the guide plate 71 has a tapered shape along the outer peripheral surface of the driven roller 31a together with the upper ends of the plurality of reinforcement ribs 75 to be described below.

As illustrated in FIG. 4, one pair of support portions 72 and 73 supports both ends in the width direction W of the roller shaft A (see FIG. 5) that supports the driven roller 31a. It is preferable that the pair of support portions 72 and 73 bends away from each other in the width direction W of the sheet P when the roller shaft A (the driven roller 31a) is inserted, and support the roller shaft A by snap-fitting.

As illustrated in FIG. 6, the pair of support portions 72 and 73 is provided with shaft accommodation recesses 72a and 73a that accommodate the end of the roller shaft A, and bearing accommodation recesses 72b and 73b that accommodate a part of a bearing B attached to the roller shaft A as illustrated in FIG. 8. The roller shaft A is inserted into the shaft accommodation recesses 72a and 73a in a direction (downward) opposite to the conveyance direction D. Similarly, the bearing B is inserted into the bearing accommodation recesses 72b and 73b in a direction (downward) opposite to the conveyance direction D. Therefore, grooves 73a-1 and 73b-1 (only the support portion 73 side is illustrated) spreading in the conveyance direction D from the shaft accommodation recesses 72a and 73a and the bearing accommodation recesses 72b and 73b may be provided. That is, the roller shaft A and the bearing B are guided by the shaft accommodation recesses 72a and 73a and the bearing accommodation recesses 72b and 73b in the direction opposite to the conveyance direction D along the grooves 73a-1 and 73b-1 when the roller shaft A and the bearing B are fixed by the snap-fit described above.

Here, since the pair of support portions 72 and 73 has the shaft accommodation recesses 72a and 73a and the bearing accommodation recesses 72b and 73b, the support portions 72 and 73 can be held using the roller shaft A with no bearing B (see FIG. 4) or the roller shaft A with the bearing B capable of coping with high load and high rotation (see FIG. 8). The roller shaft A does not rotate integrally with the driven roller 32a when the bearing B is not provided as illustrated in FIG. 4, and rotates integrally with the driven roller 32a when the bearing B is provided as illustrated in FIG. 8.

As illustrated in FIG. 4, the nip guide 70 is biased to the left such that the driven roller 31a is pressed against the driving roller 31b by a pair of compression springs C (illustrated by two-dot chain lines) disposed between the pair of support portions 72 and 73 and the conveyance path 36 illustrated in FIG. 3 described above. Since the nip guide 70 holds the driven roller 31a via the roller shaft A in the pair of support portions 72 and 73 as described above, it can be said that the nip guide 70 is biased together with the driven roller 31a by the pair of compression springs C. The compression spring C is an example of a biasing member.

As illustrated in FIG. 6, the base portion 74 has a flat plate shape spreading to be orthogonal to the conveyance direction D (the guide plate 71). The base portion 74 is integrated with the guide plate 71 and the pair of support portions 72 and 73.

The plurality of reinforcement ribs 75 are integrated with the base portion 74 to rise from the base portion 74 in the conveyance direction D. The upper end of the reinforcement rib 75 may have a shape along the outer peripheral surface of the driven roller 31a as described above.

The control unit 81 illustrated in FIG. 2 includes a processor (for example, a central processing unit (CPU)) that functions as an arithmetic processing device that controls an operation of the entire inkjet printing apparatus 1. This processor controls each unit of the inkjet printing apparatus 1, for example, by reading and executing a predetermined program from the storage unit 82 or a storage medium (non-transitory computer-readable recording medium) that is detachable from the inkjet printing apparatus 1. In this way, the control unit 81 or the inkjet printing apparatus 1 (the control unit 81 and the storage unit 82) functions as a computer that executes a program.

The storage unit 82 includes, for example, a memory such as a read only memory (ROM), which is a read-only semiconductor memory in which a predetermined control program is recorded in advance, and a random access memory (RAM), which is a semiconductor memory that can be written and read at any time and is used as a working storage area as necessary when the processor executes various control programs.

The interface unit 83 exchanges various types of information with an external apparatus. For example, the interface unit 83 receives a print job including print data from a print control apparatus or a user terminal.

The conveyance drive unit 84 is a plurality of actuators such as a plurality of motors that drive the plurality of pairs of rollers 31 (driving rollers 31b), the path switching unit 32, the pair of switchback rollers 33, or the switchback path 34, illustrated in FIG. 1.

Here, an overview of an operation of the inkjet printing apparatus 1 will be described.

First, the external sheet feeder 10 or the internal sheet feeder 20 feeds the sheet P toward the inkjet head 40. The sheet P on which an image has been formed by the inkjet head 40 is conveyed along a conveyance path formed by conveyance paths 35 and 36 or the like by a plurality of pairs of rollers 31 such as the pair of rollers 31 illustrated in FIG. 3.

When the sheet P is conveyed toward the pair of rollers 31 illustrated in FIG. 7, the guide plate 71 guides the sheet P to the vicinity of the nip area N in the conveyance direction D. Therefore, the sheet P is conveyed toward the nip area N, and is less likely to be conveyed unevenly to one of the driven roller 31a and the driving roller 31b.

Then, the path switching unit 32 switches the conveyance path of the sheet P on which image formation has been performed on one side by single-side printing and the sheet P on which image formation has been performed on both sides to a path leading to the sheet ejector 60, and switches the conveyance path of the sheet P on which image formation has been performed on only one side by double-side printing to the switchback path 34. The pair of switchback rollers 33 switches back and conveys the sheet P along the switchback path 34 to reverse the front and back sides of the sheet P. The sheet P of which the front and back are reversed along the switchback path 34 is conveyed to the inkjet head 40 again.

In the above description, the nip guide 70 holds the driven roller 31a of the pair of rollers 31 that conveys the sheet P after the image formation, but may hold the driven roller 31a of the pair of rollers 31 that conveys the sheet P before the image formation. The pair of rollers 31 may include two driven rollers 31a. Further, the nip guide 70 desirably holds the driven roller 31a provided in the curved conveyance path, but may hold the driven roller 31a provided in the straight conveyance path.

In the above description, the pair of compression springs C is used as a biasing member that biases the nip guide 70 and the driven roller 31a in the pair of support portions 72 and 73 of the nip guide 70. However, the biasing member may be another spring such as a tension spring or an elastic body other than a spring such as rubber. The number of compression springs C (biasing members) is not limited to two and may be one or more. The compression spring C (biasing member) may press the roller shaft A of the driven roller 31a instead of the nip guide 70.

In the above-described embodiment, the inkjet printing apparatus 1, which is an example of a conveyance apparatus, includes the pair of rollers 31, the nip guide 70, and the compression spring C which is an example of a biasing member. The pair of rollers 31 conveys the sheet P which is an example of a medium while nipping the sheet P. The nip guide 70 holds a driven roller 31a which is an example of one roller between the pair of rollers 31, and guides the sheet P toward the pair of rollers 31. The compression spring C biases the nip guide 70 and the driven roller 31a such that the driven roller 31a is pressed against the driving roller 31b. The nip guide 70 includes the guide plate 71 that spreads in the width direction W of the sheet P and the conveyance direction D of the sheet P, and guides the sheet P toward the pair of rollers 31.

In this way, the guide plate 71 spreads in the width direction W and the conveyance direction D of the sheet P, and thus the contact surface with the sheet P can increase, compared with an aspect in which the sheet P is guided by a rib-shaped guide. Therefore, the guide plate 71 is hardly worn, and the durability and strength of the guide plate 71 are enhanced, and thus the thickness of the guide plate 71 can be reduced. By holding the driven roller 31a by the nip guide 70, it is possible to curb a variation in a relative position of the nip guide 70 to the driven roller 31a due to variations in components or the like. Accordingly, by guiding the sheet P to the vicinity of the nip area N in the pair of rollers 31, it is possible to prevent the sheet P from being unevenly conveyed to one of the driven roller 31a and the driving roller 31b rather than the nip area N and coming into contact with the driven roller 31a or the driving roller 31b. Therefore, according to the embodiment, it is possible to prevent occurrence of rear-end collision noise and damage to the sheet P due to rear-end collision of the sheet P against the pair of rollers 31. For the rear-end collision noise, it was confirmed that a noise value of the inkjet printing apparatus 1 was reduced by 0.4 dB, compared with an aspect in which a guide that does not hold the driven roller 31a and does not enter the space S between the pair of rollers 31 is provided instead of the nip guide 70.

Incidentally, as the pair of rollers 31 that conveys the sheet P conveyed after image formation, a roller such as a mesh roller that has irregularities is used. In this case, when the sheet P comes into contact with the antinode of the pair of rollers 31, rear-end collision noise is likely to increase or the sheet P is likely to be damaged. In the pair of rollers 31 that conveys the sheet P along a curved conveyance path, the sheet P is likely to hit the pair of rollers 31. However, by using the nip guide 70 according to the embodiment, even if the pair of rollers 31 is mesh rollers or the pair of rollers 31 is provided along a curved conveyance path, the nip guide 70 can guide the sheet P to the vicinity of the nip area N. Therefore, it is possible to effectively prevent an increase in collision noise and damage to the sheet P.

According to the embodiment, the guide plate 71 enters the space S between the pair of rollers 31.

Therefore, the sheet P can be guided to the vicinity of the nip area N, and thus it is possible to effectively prevent occurrence of rear-end collision noise and damage to the sheet P.

According to the embodiment, the guide plate 71 spreads in the conveyance direction D in the space S by the length L2 that is half or more of the length L1 in the conveyance direction D in the space S up to the nip area N where the pair of rollers 31 nips the sheet P.

Thus, the sheet P can be guided to the vicinity of the nip area N, and thus it is possible to further prevent occurrence of rear-end collision noise and damage to the sheet P.

According to the embodiment, the guide plate 71 spreads over the entire region of the driven roller 31a in the width direction W of the sheet P.

Thus, since the contact surface with the sheet P can be increased, the nip guide 70 is less likely to be worn, and the durability and strength are further enhanced. Therefore, the thickness of the guide plate 71 can be further reduced, and the sheet P can be guided to the vicinity of the nip area N. Accordingly, it is possible to further prevent the occurrence of the rear-end collision noise and the damage to the sheet P.

According to the embodiment, the inkjet printing apparatus 1 further includes the roller shaft A that supports the driven roller 31a. The nip guide 70 includes one pair of support portions 72 and 73 in which both ends of the roller shaft A in the width direction W are inserted in a direction opposite to the conveyance direction D to support both ends of the roller shaft A.

In this way, when the roller shaft A (the driven roller 31a) is inserted into the pair of support portions 72 and 73 in the opposite direction of the conveyance direction D, the roller shaft A and the driven roller 31a hardly interfere with the pair of support portions 72 and 73, compared with an aspect in which the roller shaft A (the driven roller 31a) is inserted into the pair of support portions 72 and 73 in the other direction, and the guide plate 71 can be disposed close to the nip area N.

The present invention is not limited to the above-described embodiments as they are, and constituents can be modified and embodied without departing from the gist of the present invention at an implementation stage. Various inventions can be embodied by appropriately combining a plurality of constituents disclosed in the above-described embodiments. For example, all the constituents described in the embodiments may be appropriately combined. It is a matter of course that various modifications and applications can be made without departing from the gist of the invention. Hereinafter, some inventions described in the specification of the present application will be additionally described.

According to an aspect, a conveyance apparatus including: a pair of rollers configured to convey a medium while nipping the medium; a nip guide configured to hold one roller between the pair of rollers and guide the medium toward the pair of rollers; and an elastic body (a biasing member) configured to bias the nip guide and the one roller such that the one roller is pressed against the other roller between the pair of rollers, wherein the nip guide includes a guide plate that spreads in a width direction of the medium and a conveyance direction of the medium and guides the medium toward the pair of rollers.

In the conveyance apparatus, the guide plate enters a space between the pair of rollers.

In the conveyance apparatus, the guide plate spreads in the conveyance direction in the space by a length equal to or longer than a half of a length in the conveyance direction in the space to a nip area where the pair of rollers nips the medium.

In the conveyance apparatus, the guide plate spreads over an entire region of the one roller in the width direction.

In conveyance apparatus, the one roller is a driven roller, the conveyance apparatus further includes a roller shaft that supports the driven roller, and the nip guide includes a pair of support portions in which both ends of the roller shaft in the width direction are inserted in a direction opposite to the conveyance direction and which support the both ends.