Patent Application
20150290953
The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2014-81063, filed Apr. 10, 2014. The contents of this application are incorporated herein by reference in their entirety.
The present disclosure relates to a conveyor device and an inkjet recording apparatus.
A conveyor device that conveys a recording medium using a conveyor belt has been offered as a conveyor device to be mounted in an inkjet recording apparatus. A recording head ejects ink onto a recording medium, and thus an image is formed. The conveyor device uses negative pressure created by a fan in order to convey the recording medium on the conveyor belt in a stable manner.
Some conveyor mechanisms (conveyor devices) include a platen belt (conveyor belt) and a platen plate (guide member) that supports the conveyor belt. Negative pressure is created and applied to a recording medium through conveyor belt holes (suction holes) and guide member suction holes (through holes) to suck the recording medium onto the conveyor belt. Thus, the recording medium is prevented from coming off the conveyor belt and being deformed to have a wrinkle or a wave in a surface thereof during conveyance. As a result, the conveyor devices can ensure that the recording medium is flat right under a recording head.
According to a first aspect of the present disclosure, a conveyor device includes a conveyor belt and a suction section. The conveyor belt conveys a recording medium. The suction section sucks on the recording medium through the conveyor belt. The suction section has a plurality of through holes. The suction section includes an air flow chamber. The air flow chamber has an air outlet in a bottom thereof. The bottom has a plurality of first regions and a second region. The first regions are each located at a position opposite to a corresponding one of the through holes. The first regions are each located adjacent to the second region. The air outlet is located within the second region.
An inkjet recording apparatus according to a second aspect of the present disclosure includes the conveyor device according to the first aspect of the present disclosure and the recording head. The recording head is disposed opposite to the conveyor device.
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the figures of the accompanying drawings, the like reference numerals refer to similar elements, and explanation thereof is not repeated.
(Configuration of Inkjet Recording Apparatus 1)
The inkjet recording apparatus 1 will be described with reference to
The paper feed section 20 includes a paper feed cassette 200. The paper feed cassette 200 is detachably mounted in the housing 10. A plurality of sheets of recording medium P are stacked and loaded in the paper feed cassette 200. The recording medium P is paper such as plain paper, recycled paper, thin paper, or thick paper, for example.
The image forming section 30 includes the conveyor device 300 and a recording head 390. The conveyor device 300 includes a first paper conveyance section 310 and a second paper conveyance section 350 disposed opposite to the recording head 390. The second paper conveyance section 350 is located between the first paper conveyance section 310 and the paper ejecting section 40. The image forming section 30 may include a drier (not shown). The drier dries ink droplets ejected onto the recording medium P.
The first paper conveyance section 310 has a substantially C-shaped paper conveyance path 311. The first paper conveyance section 310 includes a paper feed roller 312 disposed above one end of the paper feed cassette 200, a pair of first conveyance rollers 313 disposed at an inlet of the paper conveyance path 311, a pair of second conveyance rollers 314 disposed at a midway portion of the paper conveyance path 311, a pair of registration rollers 315 disposed at an outlet of the paper conveyance path 311, and guide plates 316.
An X axis in
The guide plates 316 are disposed between the paper feed roller 312 and the pair of first conveyance rollers 313. The paper feed roller 312 takes out the recording medium P in the paper feed cassette 200 sheet by sheet. The guide plates 316 guide the recording medium P taken out by the paper feed roller 312 to the pair of first conveyance rollers 313.
The pair of first conveyance rollers 313 catches and conveys the recording medium P guided thereto by the guide plates 316 toward the paper conveyance path 311. Specifically, the pair of first conveyance rollers 313 includes a feed roller 313a and a retard roller 313b. The feed roller 313a and the retard roller 313b are opposed to each other and pressed against each other. The feed roller 313a rotates to convey the recording medium Pin the conveyance direction D. The retard roller 313b is driven by the feed roller 313a to rotate when receiving one sheet of recording medium P. Upon receiving a plurality of sheets of recording medium P at the same time, on the other hand, the retard roller 313b stops or rotates in a direction opposite to a direction for conveying the recording medium P to separate a sheet(s) of recording medium P from a sheet of recording medium P in contact with the feed roller 313a. As a result, one sheet of recording medium P is fed by the feed roller 313a.
The pair of second conveyance rollers 314 catches and conveys the recording medium P conveyed thereto by the pair of first conveyance rollers 313 toward the pair of registration rollers 315. The pair of registration rollers 315 performs skew correction on the recording medium P that has arrived and stopped at the pair of registration rollers 315. The pair of registration rollers 315 temporarily holds the recording medium P to synchronize the conveyance of the paper P and printing, and then conveys the recording medium P to the second paper conveyance section 350 in a timed relationship with the printing.
The second paper conveyance section 350 includes a speed sensing roller 351, a placing roller 352, a drive roller 353, a tension roller 354, a pair of guide rollers 356, an endless conveyor belt 355, and a suction section 360. The conveyor belt 355 is wound around the speed sensing roller 351, the drive roller 353, the tension roller 354, and the pair of guide rollers 356 in a tensioned manner. The conveyor belt 355 has a conveyance surface on which the recording medium P is placed and a conveyance back surface opposite to the conveyance surface. Rotation axes of the rollers such as the drive roller 353 are parallel to the X axis. The conveyor belt 355 has a plurality of suction holes (not shown). Each of the suction holes penetrates the conveyor belt 355 from the conveyance surface through to the conveyance back surface.
The speed sensing roller 351 is located upstream of the guide member 361 in terms of the conveyance direction D of the recording medium P. The speed sensing roller 351 includes a pulse plate (not shown). The speed sensing roller 351 rotates in contact with the conveyor belt 355. The rotational speed of the conveyor belt 355 is sensed by measuring the rotational speed of the pulse plate rotating integrally with the speed sensing roller 351. The speed sensing roller 351 restricts influence of meandering correction on the conveyor belt 355 under the recording head 390.
The placing roller 352 is located at an upstream end of the guide member 361 in terms of the conveyance direction D with the conveyor belt 355 therebetween. The placing roller 352 conveys the recording medium P in the conveyance direction D while pressing the recording medium P against the conveyor belt 355 and the guide member 361. The placing roller 352 reduces curl of the recording medium P so that the suction section 360 can suck on the recording medium P entirely and uniformly. As a result, the contact between the recording medium P and the conveyor belt 355 is made closer.
It is preferable that the moment of inertia of the placing roller 352 is low and the placing roller 352 is light in order to reduce impact vibrations on the placing roller 352 when the recording medium P comes under the placing roller 352. For example, the placing roller 352 is formed from an aluminum hollow pipe or a hollow pipe including a plurality of ribs. Where the surface of the placing roller 352 is formed from aluminum, the surface is preferably subjected to alumite treatment in order to reduce abrasion of the surface of the placing roller 352. The alumite treatment herein refers to a treatment involving electrochemically anodizing the aluminum surface in an acid treatment bath through electrolysis and thereby forming an aluminum oxide coating. The alumite treatment imparts electrical insulation to the placing roller 352. However, the surface of the placing roller 352 does not need to be subjected to the alumite treatment where the placing roller 352 needs to be electrically conductive.
The speed of conveyance of the recording medium P by the pair of registration rollers 315 may be different from the speed of conveyance of the recording medium P by the conveyor belt 355. The conveyance speed difference can be overcome by applying pressing force from the placing roller 352 to the recording medium P on the conveyor belt 355 and thus causing flexing of the recording medium P between the pair of registration rollers 315 and the placing roller 352.
The drive roller 353 is disposed in a spaced relationship to the speed sensing roller 351 in terms of the conveyance direction D of the recording medium P. The speed sensing roller 351 and the drive roller 353 maintain the conveyor belt 355 flat on the guide member 361. The drive roller 353 is in close contact with the conveyor belt 355 because of frictional force. In a configuration in which the conveyor belt 355 is made from a resin such as polyimide (PI), polyamide-imide (PAI), polyvinylidene fluoride (PVDF), or polycarbonate (PC), for example, it is preferable to wind a rubbery material such as ethylene propylene diene monomer (EPDM) rubber, polyurethane resin, or nitrile rubber (NBR) around the surface of the drive roller 353. In a configuration in which the image forming section 30 forms an image on the recording medium P using an aqueous ink, in particular, it is preferable to wind ethylene propylene diene monomer (EPDM) rubber around the drive roller 353 in order to prevent swelling of the rubbery material around the drive roller 353.
In a configuration in which the conveyor belt 355 includes a rubbery material such as ethylene propylene diene monomer (EPDM) rubber, the surface of the drive roller 353 may be made from a metal. In a configuration in which the surface of the drive roller 353 is made from aluminum, the surface of the drive roller 353 is preferably subjected to alumite treatment in order to reduce abrasion of the surface of the drive roller 353. The alumite treatment imparts electrical insulation to the drive roller 353. However, the surface of the drive roller 353 is not subjected to the alumite treatment where the drive roller 353 needs to be electrically conductive. In a configuration in which the drive roller 353 is in electrical communication with the conveyor belt 355, reduction in the accuracy of ink landing is restricted by electrically grounding the conveyor belt 355. In this case, the rubbery material included in the conveyor belt 355 is given electrical conductivity.
The drive roller 353 is driven by a motor (not shown) to rotate and cause the conveyor belt 355 to rotate counterclockwise. If the speed of the conveyor belt 355 is non-constant, non-constant speed correction control is exercised on the conveyor belt 355. The non-constant speed correction control is exercised to correct the non-constant rotation speed of the conveyor belt 355 so that the rotation speed of the conveyor belt 355 is constant. It is preferable that the moment of inertia of the drive roller 353 is low and the drive roller 353 is light for the non-constant speed correction control. For example, the drive roller 353 is made from an aluminum hollow pipe or a hollow pipe including a plurality of ribs. In the absence of the non-constant speed correction control, on the other hand, it is preferable that the drive roller 353 is heavy in order to stabilize the rotation of the drive roller 353 by the flywheel effect due to the inertia of the drive roller 353. In this case, the drive roller 353 is made from a solid metal.
The tension roller 354 is disposed at a section of the conveyor belt 355 that is located upstream of the guide member 361. The tension roller 354 tensions the conveyor belt 355 in order to prevent flexing of the conveyor belt 355. Shifting one end of the tension roller 354 enables automatic correction of meandering of the conveyor belt 355.
The conveyor belt 355 conveys the recording medium P sucked on the conveyor belt 355. The conveyor belt 355 is preferably made from polyamide-imide (PAI) or polyimide (PI), for example. Such materials prevent the conveyor belt 355 from having uneven thickness.
The pair of guide rollers 356 is disposed under the suction section 360. The pair of guide rollers 356 is fixed, maintaining a space defined by the internal peripheral surface (conveyance back surface) of the conveyor belt 355. Of the pair of guide rollers 356, a guide roller 356 that is closer to the drive roller 353 maintains the degree to which the conveyor belt 355 is wound around the drive roller 353. Of the pair of guide rollers 356, the other guide roller 356 that is closer to the tension roller 354 maintains the degree to which the conveyor belt 355 is wound around the tension roller 354 for stable correction of meandering of the conveyor belt 355.
The suction section 360 is disposed at the conveyance back surface of the conveyor belt 355 and opposite to the recording head 390 with the conveyor belt 355 therebetween. The suction section 360 includes a guide member 361, an air flow chamber 362, and one or more sucking devices 363.
The air flow chamber 362 has a hollow box-like shape opened at the top. That is, an opening is formed in the top of the air flow chamber 362. The guide member 361 covers (blocks) the top opening of the air flow chamber 362. The guide member 361 supports the recording medium P via the conveyor belt 355.
The sucking device 363 is disposed in communication with the air flow chamber 362 and draws air in the air flow chamber 362 to create negative pressure in the air flow chamber 362. As a result, the recording medium P is sucked toward the top of the air flow chamber 362 through the conveyor belt 355 and the guide member 361. It should be noted here that negative pressure refers to pressure lower than reference pressure. The reference pressure referred to in the present specification is atmospheric pressure. Negative pressure “PN” is an absolute value of (PA−PR), wherein “PA” represents the absolute pressure and “PR” represents the reference pressure (PN=|PA−PR|). The absolute pressure is pressure based on the absolute vacuum of 0. The air flow chamber 362 functions as a decompression chamber.
The recording head 390 includes one or more inkjet heads 390k, one or more inkjet heads 390c, one or more inkjet heads 390m, and one or more inkjet heads 390y. Each of the inkjet heads 390k, 390c, 390m, and 390y ejects ink.
The paper ejecting section 40 includes a conveyance guide 400, a pair of ejection rollers 410, and an exit tray 420. The conveyance guide 400 is located downstream of the second paper conveyance section 350 in terms of the conveyance direction D of the recording medium P. The exit tray 420 is fixed to the housing 10 and projected outward from an exit port 430 formed in the housing 10.
The conveyance guide 400 guides the recording medium P being conveyed from the conveyor belt 355 to the pair of ejection rollers 410. The recording medium P that has passed through the conveyance guide 400 is conveyed by the pair of ejection rollers 410 to the exit port 430 and ejected onto the exit tray 420 through the exit port 430.
The basic configuration of the conveyor device 300 according to a first embodiment of the present disclosure will be described with reference to
The suction section 360 sucks on the recording medium P through the conveyor belt 355. A plurality of grooves 364a are formed in the guide member 361 in the suction section 360. Each of the grooves 364a has an oval shape and extends along the conveyance direction D of the recording medium P. Each of the grooves 364a has a length along the conveyance direction D of 54 mm Each of the grooves 364a has a length along a direction perpendicular to the conveyance direction D of 6 mm. The grooves 364a are in a staggered arrangement along the conveyance direction D and the direction perpendicular to the conveyance direction D. Each of the grooves 364a has a through hole 365a. Each of the through holes 365a has a diameter of 6 mm Each of the through holes 365a is located at one end, at the other end, or in the center of the corresponding groove 364a. For example, the through holes 365a are in a staggered arrangement along the direction perpendicular to the conveyance direction D.
The bottom 362a of the air flow chamber 362 has an air outlet 362b. The air outlet 362b has a diameter of 50 mm. The sucking device 363 is in communication with the air flow chamber 362 via the air outlet 362b. The bottom 362a has first regions A1 and a second region A2. The first regions A1 overlap with the respective through holes 365a. The first regions A1 are each located adjacent to the second region A2. The air outlet 362b is formed in the second region A2.
Upon actuation of the sucking device 363 with the recording medium P on the conveyance surface of the conveyor belt 355, negative pressure is created in the air flow chamber 362. The sucking device 363 includes a fan 363a, a fan shaft 363b, and a fan air outlet 363c. The negative pressure acts on the recording medium P through the air outlet 362b, the through holes 365a, the grooves 364a, and the suction holes of the conveyor belt 355. Air is drawn by the sucking device 363 and discharged to the outside of the suction section 360 through the fan air outlet 363c. The conveyor belt 355 conveys the recording medium P in the conveyance direction D as it rotates. The conveyor belt 355 has a thickness of 100 μm. Each of the suction holes of the conveyor belt 355 has a diameter of 2 mm.
Since the air outlet 362b is formed in the second region A2 in the conveyor device 300 as described with reference to
The positions of the through holes 365a formed in the respective grooves 364a may be changed according to the position of the air outlet 362b and the shape of a peripheral edge 362c of the air outlet 362b. Thus, it is possible to reduce contamination of the fan 363a without changing the positions of the sucking device 363 and the air outlet 362b.
[Variation of Air Outlet 362b]
A variation of the air outlet 362b according to the first embodiment will be described with reference to
The fan 363a in the variation is smaller-sized. The smaller-sized fan 363a allows reduction of the diameter of the air outlets 362b. The size of the fan 363a is determined according to the distance among the plurality of through holes 365a. Accordingly, the through holes 365a do not overlap with the air outlets 362b. Thus, it is possible to reduce contamination of the fan 363a without changing the positions of the through holes 365a.
The basic configuration of the conveyor device 300 according to a second embodiment of the present disclosure will be described with reference to
The air flow chamber 362 in the conveyor device 300 according to the second embodiment has the projection 362d in the second region A2. The projection 362d is formed along the peripheral edge 362c of the air outlet 362b. Specifically, the projection 362b is a rib or a bank, for example. The height of the projection 362d based on the horizontal level of the bottom 362a is 1 to 2 mm. However, the height of the projection 362d may be increased or decreased according to a depth Dr of the air flow chamber 362. A top edge 362e of the projection 362d is at a higher level than the horizontal level of the second region A2 in the bottom 362a. Thus, the projection 362d can hold back ink that has been abnormally ejected and that has flowed into the air flow chamber 362.
[Variation of Projection 362d]
A variation of the projection 362d according to the second embodiment will be described with reference to
As illustrated in
The projection 362d illustrated in
In a configuration in which the projection 362d is projected in an oblique manner, it is preferable that the region defined by the top edge 362e of the projection 362d does not overlap with the first regions A1 in a plan view from the direction of the Z axis. Thus, ink flowing through the through holes 365a is prevented from falling directly on the projection 362d in the case of abnormal ink ejection.
The projection 362d may have an inverted L shape in a cross-section along the Z axis as illustrated in
Alternatively, the projection 362d may include a section having a curved shape as illustrated in
Alternatively, the projection 362d may have a shape including a section standing upright and a section projected in an oblique manner in a cross-section along the Z axis as illustrated in
The basic configuration of the conveyor device 300 according to a third embodiment of the present disclosure will be described with reference to
In the third embodiment, the air flow chamber 362 has the connection section 362f. The connection section 362f is connected with the bottom 362a at the air outlet 362b. A lower end of the connection section 362f is connected with the sucking device 363. Specifically, the connection section 362f is a duct, for example. The connection section 362f has a straight cylindrical shape in parallel to the Z axis. The cross-section of the connection section 362f along the Y axis has a circular, oval, rectangular, or polygonal shape, for example. The connection section 362f includes an opening end facing the air flow chamber 362 and an opening end 362g facing the sucking device 363. The opening end of the connection section 362f that faces the air flow chamber 362 is connected with the peripheral edge 362c of the air outlet 362b. The opening end 362g facing the sucking device 363 is connected with the sucking device 363.
Negative pressure acts on the recording medium P through the opening end 362g of the connection section 362f, the air outlet 362b, the through holes 365a, the grooves 364a, and the suction holes of the conveyor belt 355. The sucking device 363 is disposed inside of the second paper conveyance section 350 as illustrated in
The air flow chamber 362 has the connection section 362f as described with reference to
The connection section 362f illustrated in
A flow channel in the connection section 362f illustrated in
So far, the embodiments of the present disclosure have been described with reference to the drawings (
(1) The sucking device 363 is a fan according to the description made with reference to
(2) The guide member 361 has the through holes 365a in communication with the grooves 364a according to the description made with reference to
(3) The peripheral edge 362c of the air outlet 362b has a circular shape according to the description made with reference to
(4) One groove 364a has one through hole 365a according to the description made with reference to
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-081063 | Apr 2014 | JP | national |
