Conveyance Apparatus

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.

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

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).

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.

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.

are a front view illustrating an internal structure of an inkjet printing apparatusand a block diagram illustrating a control configuration thereof.

Each of up-down, front-rear, and left-right directions illustrated into 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, the inkjet printing apparatusincludes an apparatus housing, an external sheet feeder, an internal sheet feeder, an inkjet head, a print conveyor, and a sheet ejector. As illustrated in, the inkjet printing apparatusfurther includes a control unit, a storage unit, an interface unit, and a conveyance drive unit.

In, a conveyance path of a sheet P from the external sheet feederor the internal sheet feederto the sheet ejectoris indicated by a solid line, and a switchback pathfor 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 apparatuswill 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 feederincludes a sheet feeding tray, a sheet feeding roller, and a separating plate. The external sheet feederis an example of a feeder and is disposed to be exposed to, for example, the outside of the apparatus housingand feeds the sheet P into the apparatus housing. The sheet P before image formation is piled on the sheet feeding tray. For example, two sheet feed rollersare 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. The separating platesandwiches the sheet P with the sheet feeding rollerand separates the sheet P one by one.

The internal sheet feederincludes a first sheet feeder, a second sheet feeder, and a third sheet feeder. The first sheet feeder, the second sheet feeder, and the third sheet feederare arrayed in this order from above inside the apparatus housing. Each of the first sheet feeder, the second sheet feeder, and the third sheet feederincludes sheet feeding trays,, andon which the sheets P before image formation are piled, and sheet feeding rollers,, andthat feed and convey the uppermost sheet P among the plurality of sheets P piled on the sheet feeding trays,, and

The inkjet printing apparatusfurther includes a plurality of pairs of rollers, a path switching unit, a pair of switchback rollers, a switchback path, and conveyance pathsandillustrated in.

For example, the pair of rollersconveys the sheet P while nipping the sheet P along the conveyance path of the sheet P inside the apparatus housing.

The path switching unitswitches the conveyance path of the sheet P on which the image has been formed by the inkjet headbetween a path leading to the sheet ejectorand the switchback path. The path switching unitis, for example, a flapper. The pair of switchback rollersswitches back and conveys the sheet P along the switchback pathto reverse the front and back sides of the sheet P. The switchback pathis used to circulate the sheet P for double-side printing and re-feed the sheet P to the inkjet head.

The inkjet headis, 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, the print conveyorto be described below, or the like. Thus, the inkjet headforms an image on the sheet P. The inkjet headis an example of an image forming unit. An image forming method is not limited to inkjet printing.

The print conveyoris disposed to face the inkjet headand conveys the sheet P. The print conveyorincludes a plurality of pulleys, a beltstretched around the pulleys, and a suction fanthat sucks air through a plurality of holes formed in the beltto cause the beltto adsorb the sheet P. The print conveyormay include a conveyance member other than the beltsuch as a roller or may not adsorb the sheet P. The print conveyorfunctions as an example of a conveyance unit that conveys the sheet P together with the pair of rollersand the like. The conveyance unit may include a conveyance member such as a roller or a belt.

The sheet ejectorincludes a sheet ejection trayand a sheet ejection roller. The sheet ejectoris an example of an ejector and is disposed, for example, to be exposed to the outside of the apparatus housingand ejects the sheet P to the outside of the apparatus housing. The sheet P on which an image has been formed is piled on the sheet ejection tray. For example, a pair of upper and lower sheet ejection rollersis disposed and conveys the sheet P toward the sheet ejection tray.

The inkjet printing apparatusfurther includes a nip guideillustrated in. The nip guideis made of, for example, a plastic material and includes a guide plate, a pair of support portionsand, a base portion, and a plurality of reinforcement ribsas illustrated in.

The nip guideholds the driven rollerof the pair of rollers. The driven rollerheld by the nip guideis provided along a conveyance path (see) curved upward for conveying the sheet P on which the image has been formed by the inkjet head. The nip guideholds the driven roller, so that a relative position of the nip guideto the driven roller(such as the protrusion amount of the driven rollerfrom the guide plate) can be made constant. The pair of rollersmay include, for example, a coating roller coated with fine particles such as ceramic particles and a mesh roller covered with knitting.

The pair of rollersillustrated inis disposed in the vicinity between the conveyance pathsand, each of which is formed of a pair of curved plate-like members. The pair of rollersincludes the driven rollerand a driving roller. Two nip guidesand two pairs of rollerseach having the driven rollerheld by the nip guidesare disposed side by side in a width direction W of the sheet P. However, the number of sets of the nip guidesand the pairs of rollersmay be any number of one or more. The nip guideand the pair of rollersmay be disposed at a plurality of positions different in the conveyance direction D.

As illustrated in, the guide platespreads 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. The guide platemay have a thin flat plate shape. The guide platemay spread by a length that is half or more of the length of the driven rollerin the width direction W of the sheet P, and preferably spreads over the entire region of the driven roller

As illustrated in, the guide plateenters a space S (as illustrated by a two-dot chain line, the space S sandwiched between the driven rollerand the driving roller) between the pair of rollers. Preferably, the guide platespreads in the conveyance direction D in the space S by a length Lthat is half or more of a length Lin the conveyance direction D in the space S up to a nip area N (an area where the pair of rollersnips the sheet P). The guide platemay 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 platespreads to cross the conveyance path of the sheet P continuing from the conveyance path, so that the sheet P can be guided while coming in contact with the sheet P. Since the pair of rollershas 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 platehas a tapered shape along the outer peripheral surface of the driven rollertogether with the upper ends of the plurality of reinforcement ribsto be described below.

As illustrated in, one pair of support portionsandsupports both ends in the width direction W of the roller shaft A (see) that supports the driven roller. It is preferable that the pair of support portionsandbends away from each other in the width direction W of the sheet P when the roller shaft A (the driven roller) is inserted, and support the roller shaft A by snap-fitting.

As illustrated in, the pair of support portionsandis provided with shaft accommodation recessesandthat accommodate the end of the roller shaft A, and bearing accommodation recessesandthat accommodate a part of a bearing B attached to the roller shaft A as illustrated in. The roller shaft A is inserted into the shaft accommodation recessesandin a direction (downward) opposite to the conveyance direction D. Similarly, the bearing B is inserted into the bearing accommodation recessesandin a direction (downward) opposite to the conveyance direction D. Therefore, grooves-and-(only the support portionside is illustrated) spreading in the conveyance direction D from the shaft accommodation recessesandand the bearing accommodation recessesandmay be provided. That is, the roller shaft A and the bearing B are guided by the shaft accommodation recessesandand the bearing accommodation recessesandin the direction opposite to the conveyance direction D along the grooves-and-when the roller shaft A and the bearing B are fixed by the snap-fit described above.

Here, since the pair of support portionsandhas the shaft accommodation recessesandand the bearing accommodation recessesand, the support portionsandcan be held using the roller shaft A with no bearing B (see) or the roller shaft A with the bearing B capable of coping with high load and high rotation (see). The roller shaft A does not rotate integrally with the driven rollerwhen the bearing B is not provided as illustrated in, and rotates integrally with the driven rollerwhen the bearing B is provided as illustrated in.

As illustrated in, the nip guideis biased to the left such that the driven rolleris pressed against the driving rollerby a pair of compression springs C (illustrated by two-dot chain lines) disposed between the pair of support portionsandand the conveyance pathillustrated indescribed above. Since the nip guideholds the driven rollervia the roller shaft A in the pair of support portionsandas described above, it can be said that the nip guideis biased together with the driven rollerby the pair of compression springs C. The compression spring C is an example of a biasing member.

As illustrated in, the base portionhas a flat plate shape spreading to be orthogonal to the conveyance direction D (the guide plate). The base portionis integrated with the guide plateand the pair of support portionsand.

The plurality of reinforcement ribsare integrated with the base portionto rise from the base portionin the conveyance direction D. The upper end of the reinforcement ribmay have a shape along the outer peripheral surface of the driven rolleras described above.

The control unitillustrated inincludes 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. This processor controls each unit of the inkjet printing apparatus, for example, by reading and executing a predetermined program from the storage unitor a storage medium (non-transitory computer-readable recording medium) that is detachable from the inkjet printing apparatus. In this way, the control unitor the inkjet printing apparatus(the control unitand the storage unit) functions as a computer that executes a program.

The storage unitincludes, 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 unitexchanges various types of information with an external apparatus. For example, the interface unitreceives a print job including print data from a print control apparatus or a user terminal.

The conveyance drive unitis a plurality of actuators such as a plurality of motors that drive the plurality of pairs of rollers(driving rollers), the path switching unit, the pair of switchback rollers, or the switchback path, illustrated in.

Here, an overview of an operation of the inkjet printing apparatuswill be described.

First, the external sheet feederor the internal sheet feederfeeds the sheet P toward the inkjet head. The sheet P on which an image has been formed by the inkjet headis conveyed along a conveyance path formed by conveyance pathsandor the like by a plurality of pairs of rollerssuch as the pair of rollersillustrated in.

When the sheet P is conveyed toward the pair of rollersillustrated in, the guide plateguides 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 rollerand the driving roller

Then, the path switching unitswitches 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, 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. The pair of switchback rollersswitches back and conveys the sheet P along the switchback pathto reverse the front and back sides of the sheet P. The sheet P of which the front and back are reversed along the switchback pathis conveyed to the inkjet headagain.

In the above description, the nip guideholds the driven rollerof the pair of rollersthat conveys the sheet P after the image formation, but may hold the driven rollerof the pair of rollersthat conveys the sheet P before the image formation. The pair of rollersmay include two driven rollers. Further, the nip guidedesirably holds the driven rollerprovided in the curved conveyance path, but may hold the driven rollerprovided 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 guideand the driven rollerin the pair of support portionsandof the nip guide. 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 rollerinstead of the nip guide.

In the above-described embodiment, the inkjet printing apparatus, which is an example of a conveyance apparatus, includes the pair of rollers, the nip guide, and the compression spring C which is an example of a biasing member. The pair of rollersconveys the sheet P which is an example of a medium while nipping the sheet P. The nip guideholds a driven rollerwhich is an example of one roller between the pair of rollers, and guides the sheet P toward the pair of rollers. The compression spring C biases the nip guideand the driven rollersuch that the driven rolleris pressed against the driving roller. The nip guideincludes the guide platethat 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.

In this way, the guide platespreads 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 plateis hardly worn, and the durability and strength of the guide plateare enhanced, and thus the thickness of the guide platecan be reduced. By holding the driven rollerby the nip guide, it is possible to curb a variation in a relative position of the nip guideto the driven rollerdue 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, it is possible to prevent the sheet P from being unevenly conveyed to one of the driven rollerand the driving rollerrather than the nip area N and coming into contact with the driven rolleror the driving roller. 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. For the rear-end collision noise, it was confirmed that a noise value of the inkjet printing apparatuswas reduced by 0.4 dB, compared with an aspect in which a guide that does not hold the driven rollerand does not enter the space S between the pair of rollersis provided instead of the nip guide.

Incidentally, as the pair of rollersthat 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, rear-end collision noise is likely to increase or the sheet P is likely to be damaged. In the pair of rollersthat conveys the sheet P along a curved conveyance path, the sheet P is likely to hit the pair of rollers. However, by using the nip guideaccording to the embodiment, even if the pair of rollersis mesh rollers or the pair of rollersis provided along a curved conveyance path, the nip guidecan 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 plateenters the space S between the pair of rollers.

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 platespreads in the conveyance direction D in the space S by the length Lthat is half or more of the length Lin the conveyance direction D in the space S up to the nip area N where the pair of rollersnips 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.