This application is based on and claims the benefit of priority from Japanese patent application No. 2022-121497 filed on Jul. 29, 2022, which is incorporated by reference in its entirety.
The present disclosure relates to a medium conveying device which conveys a medium and an image forming apparatus.
A conveying device is known which conveys a sheet while holding it between a discharge roller made of high-rigidity material and multiple spur rollers. The discharge roller has a discharge roller part coming into contact with the sheet and a roller groove part provided at positions facing the spur rollers, and the surface of the discharge roller part is processed to increase friction force.
In the conveying device described above, the spur roller sometimes receives a reaction force from the sheet (medium) being conveyed, resulting in a posture inclined with respect to the proper conveyance direction. In this case, the sheet would be conveyed obliquely along the inclination of the spur roller, and the sheet would sometimes jam in the conveyance path. In addition, when the obliquely conveyed sheets will be discharged on the discharge tray, various failure may occur, for example, the sheet could not be stacked in an aligned state.
A medium conveying apparatus according to the present disclosure includes a driving roller, a plurality of driven rollers, a support part, a plurality of upstream restriction parts and a plurality of downstream restriction parts. The driving roller is driven to be rotated around an axis. The driven rollers are provided at intervals, and driven by the driving roller to be rotated around an axis and to convey a medium held between the driving roller and the driven rollers. The support part supports the driven rollers so as to be rotatable around the axis. The upstream restriction parts are provided in the support part between the adjacent driven rollers. The downstream restriction parts are provided in the support part between the adjacent driven rollers. The upstream restriction parts and the downstream restriction parts are arranged on an upstream side and a downstream side in a conveyance direction of the medium across a rotational center of the driven rollers respectively. When the driven rollers are tilted with respect to the conveyance direction, the upstream restriction parts and the downstream restriction parts comes into contact with side surfaces of the driven rollers to restrict tilting of the driven rollers.
An image forming apparatus according to the present disclosure includes the medium conveying apparatus.
The above and other objects, features, and advantages of the present disclosure will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present disclosure is shown by way of illustrative example.
Hereafter, with reference to the attached drawings, an embodiment of the present disclosure will be described with reference to the drawings. Fr, Rr, L, R, U, and D in the drawings refer to the front, rear, left, right, upper and lower. The terms indicating the direction and position are used herein for illustrative convenience and are not intended to limit the technical scope of the disclosure.
[Image forming apparatus] With reference to
The image forming apparatus 1 is an inkjet printer which ejects ink droplet to forms an image on a sheet P (paper). The image forming apparatus 1 includes a box-shaped housing 2 in which various devices are housed. In the lower portion in the housing 2, a sheet feeding cassette 3 in which the sheets P are set is housed, and a sheet discharge tray 4 on which the printed sheet S is stacked is provided on the upper portion of the right side surface of the housing 2. In this specification, the direction in which the sheet P as an example of a medium is conveyed is referred to as the “conveyance direction”, and the “upstream”, “downstream” and similar terms refer to the “upstream”, “downstream” and similar concept in the conveyance direction. The medium is not limited to the sheet P, but may be, for example, a sheet (film) made of resin.
In the left side portion in the housing 2, a first conveyance path 5 is formed, along which the sheet P is conveyed from the sheet feeding cassette 3 toward a head unit 12. A sheet feeding part 10 is provided at the upstream end of the first conveyance path 5, and a registration roller 11 is provided at the downstream end of the first conveyance path 5.
The head unit 12 has four line heads 13 corresponding to four inks of black, cyan, magenta and yellow. A plurality of recording heads 14 are mounted on each line head 13. The ink is supplied to each recording head 14 from each color ink pack (not shown) via a tube (not shown). Below the head unit 12, a conveyance belt 15 wound around a plurality of tensioning rollers 15A is provided. A large number of through-holes (not shown) are formed in the conveyance belt 15, and a suction part 15B for sucking air through the through-holes is provided inside the conveyance belt 15.
In the right side portion in the housing 2, a second conveyance path 7 is formed, along which the sheet P is conveyed from the head unit 12 toward the sheet discharge tray 4. A medium conveying device 18 is provided on the upstream side of the second conveyance path 7, a decurl device 16 is provided at the midstream of the second conveyance path 7, and a sheet discharge part 17 is provided at the downstream end of the second conveyance path 7. In the upper portion in the housing 2, a third conveyance path 8 is formed, along which the sheet P is reconveyed from the middle of the second conveyance path 7 to the registration roller 11.
[Image Forming Processing] An image forming processing will be described here. A control part (not shown) of the image forming apparatus 1 controls the various controlled devices as appropriate and executes the image forming processing as follows.
The sheet feeding part 10 feeds the sheet P picked up from the sheet feeding cassette 3 to the first conveyance path 5. The registration roller 11 temporarily blocks the sheet P and corrects the skew of the sheet P, and feeds the sheet P to the conveyance belt 15 in accordance with the ejection timing of ink droplets from the line head 13. The sheet P is conveyed while being attracted to the conveyance belt 15, and each recording head 14 mounted on the head unit 12 ejects the ink droplets from the nozzles (not shown) toward the sheet P on the conveyance belt 15 to form a full-color image. The medium conveying device 18 (a conveyance rollers pair 20) conveys the printed sheet P downstream in the conveyance direction, and the decurl device 16 corrects the curl of the sheet P.
The one-side printed sheet S is discharged to the sheet discharge tray 4 through the second conveyance path 7. When performing a double-sided printing, the one-side printed sheet P is conveyed to the third conveyance path 8, is inverted upside down and then conveyed again toward the registration roller 11. Then, an image is formed on the back side of the sheet P in the same order as in the one-side printing described above, and the both-side printed sheet P is discharged on the discharge tray 4.
[Medium Conveying Device] With reference to
The medium conveying device 18 includes a plurality of (for example, four) conveying rollers pairs and a plurality of (for example, four) support parts 40. The conveying rollers pairs 20 and the support parts 40 are arranged in a line with spaces in the front-and-rear-direction (the width direction), and since they have the same structure, one conveying rollers pair 20 and one support part 40 are described in this specification.
<Conveying Rollers Pair> As shown in
<Driving Roller> The driving roller 21 has a driving shaft 22 extending in the front-and-rear direction (in the width direction perpendicular to the conveyance direction) and a driving body part 23 fixed to the circumferential surface of the driving shaft 22. Both the end portions of the driving shaft 22 are rotatably supported by a frame (not shown) provided inside the housing 2. The driving shaft 22 is connected to a driving source (not shown) such as an electric motor, and is rotated around the axis by a driving force from the driving source. The driving body part 23 is formed of an elastic body made of synthetic rubber, for example.
(Driven Roller) The seven driven rollers 31 and 32 are supported by the support part 40 so as to be rotatable around the axis. The four first driven rollers 31 and the three second driven rollers 32 are alternately provided with approximately equal spaces in the front-and-rear direction (width direction).
The driven rollers 31, 32 have driven body parts 33, 34 formed in an approximately disk shape, and a plurality of protrusions 35, 36 protruding outwards in the radial direction from the outer circumferential surface of the driven body parts 33, 34, and arranged at intervals in the circumferential direction. The driven body parts 33 and 34 are composed of a pair of discs (not shown), and the driven rollers 31, 32 are formed in such a manner that a gear shaped (spur shaped) thin piece (not shown) having a plurality of protrusions 35, 36 is held between the discs. For example, the driven body parts 33 and 34 are made of the same material as the driving body part 23, and the protrusions 35, 36 are made of synthetic resin or the like in a needle-like shape. In
As shown in
<Support Part> As shown in
(Roller Holder, Swinging Shaft) The roller holder 41 has a pair of end surface parts 50 spaced apart in the front-and-rear direction and a side surface part 51 provided between the left end portions of the end surface parts 50, and is formed in a frame shape opened from the upper side to the right side. The roller holder 41 houses the seven driven rollers 31, 32 (the swinging arms 43, 44). On the right side surface of each end surface part 50, a shaft groove 52 inclined leftward and downward from the upper end is cut out (see
(Swinging Arm) As shown in
The driven rollers 31, 32 are arranged so as to face the rear side surfaces of the swinging arms 43, 44, and are supported by the support shafts 54, 55 in a cantilevered manner. The first swinging arm 43 (the axial distance from the swinging shaft 42 to the first shaft 54) is longer than the second swinging arm 44 (the axial distance from the swinging shaft 42 to the second shaft 55) (see
(Biasing Member) As shown in
(Upstream Restriction Part) As shown in
(Downstream Restriction Part) The downstream restriction parts 47 are provided on the swinging arms 43, 44. Specifically, the downstream restriction parts 47 protrude forward from the front side surfaces of the swinging arms 43, 44. The downstream restriction parts 47 are formed in a curved arm shape with approximately the same curvature as the driven rollers 31, 32. The six downstream restriction parts 47, except for the downstream restriction part 47 located at the frontmost position, are arranged between adjacent driven rollers 31, 32 on the downstream side of the rotational centers of the driven rollers 31, 32 in the conveyance direction. The downstream restriction parts 47 faces the rear side surfaces of the adjacent driven body parts 33, 34 with a small gap. The downstream restriction parts 47 are provided at a position intersecting the horizontal line H passing through the rotational centers (supporting shafts 54, 55) of the driven rollers 31, 32 (see
[Operation of Medium Conveying Device] Next, the operation of the medium conveying device 18 will be described.
When the sheet P is not being conveyed, the swinging arms 43, 44 are biased by the biasing members 45 and swung upward, and the protrusions 35, 36 of the driven rollers 31, 32 come into contact with the driving roller 21 (the driving body part 23) at a prescribed pressure (see
Next, when the sheet P is being conveyed, the swinging arms 43, 44 are swung downward by the sheet P conveyed between the driving roller 21 and the driven rollers 31, 32, and the driven rollers 31, 32 are separated from the driving roller 21. The protrusions 36 come into contact with the surface (the printed surface) of the sheet P, and the driving body part 23 comes into contact with the back surface of the sheet P. Thus, since only the protrusions 35, 36 come into contact with the surface of the sheet P, the ink on the sheet P is prevented from adhering to the driven rollers 31, 32 (the driven body parts 33, 34). In addition, since the driven rollers 31, 32 are provided at intervals in the axial direction, it is possible to properly convey the sheet P of various sizes (widths).
Incidentally, for example, the driven rollers 31, 32 may receive a reaction force from the sheet P being conveyed and tilt slightly with respect to the proper conveyance direction. Then, the sheet P may be conveyed obliquely along the tilt of the driven rollers 31, 32, and there is a possibility that the sheet P is jammed in the second conveyance path 7. In addition, when the obliquely conveyed sheet P is discharged onto the sheet discharge tray 4, the sheet P cannot be stacked in an aligned state and may be dropped from the sheet discharge tray 4.
In response to the above problem, in the medium conveying device 18 according to the present embodiment, the upstream restriction parts 46 and the downstream restriction parts 47 are arranged between the adjacent driven rollers 31, 32 on the upstream and downstream sides in the conveyance direction across the rotational centers of the driven rollers 31, 32 (see
Incidentally, in the medium conveying device 18 according to the present embodiment, the first driven rollers 31 and the second driven rollers 32 come into contact with the driving roller 21 while shifted in the conveyance direction (see
In response to the above problem, in the medium conveying device 18 according to the present embodiment, the second driven rollers 32 are in contact with the driving roller 21 on the downstream side of the first driven rollers 31, and the second nip area N2 is formed on the downstream side of the first nip area N1 (see
Now consider the procedure (method) for assembling the driven rollers 31 and 32 into the roller holder 41. If both the restriction parts 46, 47 may be provided in the roller holder 41, after all the driven rollers 31, 32 are arranged between the adjacent upstream restriction parts 46 and the adjacent downstream restriction parts 47, the driven rollers 31, 32 are attached to the swinging arms 43, 44, the swinging shaft 42 is passed through the swinging arms 43, 44, and then the swinging shaft 42 is fitted into the pair of shaft grooves 52 of the roller holder 41. This procedure (method) makes it very difficult to assemble the driven rollers 31, 32 into the roller holder 41, and requires long time.
In response to the above problem, in the medium conveying device 18 according to the present embodiment, the upstream restriction parts 46 are provided in the roller holder 41, and the downstream restriction parts 47 are provided in the swinging arms 43, 44 (see
In the medium conveying device 18 according to the present embodiment, the upstream restriction parts 46 are provided in the roller holder 41 and the downstream restriction parts 47 are provided in the swinging arms 43, 44, but the present disclosure is not limited to these. For example, on the contrary, the upstream restriction parts 46 may be provided in the swinging arms 43, 44 and the downstream restriction parts 47 may be provided in the roller holder 41 (not shown). Both the restriction parts 46, 47 may be provided in the swinging arms 43, 44 (not shown). In addition, although the assembly work becomes difficult, both the restriction parts 46, 47 may be provided in the roller holder 41 (not shown). In addition, although the downstream restriction parts 47 protrude from the front side surface of the swinging arms 43, 44, it is not limited to this. The downstream restriction parts 47 may protrude from the rear side surface of the swinging arms 43, 44 (not shown).
Also, in the medium conveying device 18 according to the present embodiment, the upstream restriction parts 46 and the downstream restriction parts 47 face each other on both sides of the conveyance direction across the rotational centers of the driven rollers 31, 32 at positions intersecting the horizontal line H, but the present disclosure is not limited to this. The upstream restriction parts 46 and the downstream restriction parts 47 may be arranged on both sides of the conveyance direction across the rotational centers of the driven rollers 31 and 32, and may not necessarily face each other at the positions intersecting the horizontal line H (not shown). In addition, at least one of the upstream restriction parts 46 and the downstream restriction parts 47 may be provided. For example, two upstream restriction parts 46 and one downstream restriction part 47 may be provided in the circumferential direction at approximately 120 degrees (not shown). In addition, for example, the two upstream restriction parts 46 and the two downstream restriction parts 47 may be provided in the circumferential direction at approximately 90 degrees (not shown). In addition, although the upstream restriction parts 46 are formed longer in the upper-and-lower direction (the circumferential direction) than the downstream restriction parts 47, the upstream restriction parts 46 may be formed shorter in the circumferential direction than the downstream restriction parts 47 or may be formed to the same length as the downstream restriction parts 47 (not shown).
In addition, according to the medium conveying device 18 according to the present embodiment, the seven driven rollers 31, 32 are provided, but the present disclosure is not limited to this. The two or more driven rollers 31, 32 may be provided. Although the first driven rollers 31 are in contact with the driving roller 21 on the upstream side of the second driven rollers 32, it is not limited to this. The second driven rollers 32 may be in contact with the driving roller 21 on the upstream side of the first driven rollers 31 (not shown). In addition, although the impact reduction effect when the sheet P enters the nip areas N1, N2 is eliminated, all the driven rollers 31, 32 (the nip areas N1, N2) may be arranged in a row horizontally (not shown). In addition, the driven rollers 31, 32 are formed in a spur shape with the plurality of protrusions 35 and 36, but the present disclosure is not limited to this. They may be formed in a disk shape omitting the plurality of protrusions 35, 36 (not shown). That is, the driven rollers 31 and 32 may consist of only the driven body parts 33, 34 (not shown).
In the image forming apparatus 1 described above, the recording head 14 ejects the ink droplets from the nozzles, but the droplets ejected from the nozzles are not limited to the ink droplets, and may be water, liquid adhesive or liquid synthetic resin, for example.
The image forming apparatus 1 described above is a color printer, but it is not limited to this, and may be a monochrome printer, a copying machine, a facsimile machine, or the like. In addition, the image forming method of the image forming apparatus 1 is not limited to the inkjet type, but may be an electrophotographic type.
The description of the above embodiment shows one aspect of the media conveyance device and the image forming device according to the present disclosure, and the technical scope of the present disclosure is not limited to the above embodiment. The disclosure may be variously modified, replaced, or modified to the extent that it does not deviate from the purport of the technical idea, and the scope of the patent claims includes all of the implementations that may be included within the technical idea.
Number | Date | Country | Kind |
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2022-121497 | Jul 2022 | JP | national |