This application is based on and claims the benefit of priority from Japanese Patent application No. 2015-122803 filed on Jun. 18, 2015, the entire contents of which are incorporated herein by reference.
The present disclosure relates to a sheet correcting device corrects the curl of the sheet and an image forming apparatus including this.
A sheet of paper on which an image has been formed by an electro-photographic image forming apparatus is often curled (has a curling habit). The sheet curls along a conveyance (discharge) direction (referred to also as a ‘regular curl’ hereinafter) by being nipped by a fixing unit (fixing nip part), a discharge roller pair and the like. The sheet also curls along a width direction orthogonal to the conveyance direction (referred to also as a ‘side curl’ hereinafter) by being heated by the fixing unit in a condition in which environmental humidity is high for example (see
Then, technologies for suppressing the sheet stacking failure are being proposed. For instance, an electro-photographic apparatus includes a plurality of pressing parts at widthwise both sides of a sheet. The plurality of pressing parts presses widthwise both sides of a side-curled sheet against a sheet receiving surface of a sheet discharge tray. This arrangement makes it possible to prevent the sheet stacking failure.
However, because each of the pressing parts of the electro-photographic apparatus described above merely presses the already side-curled sheet against the sheet discharge tray, it is unable to fully correct the side curl of the sheet. That is, each of the pressing parts of the electro-photographic apparatus described above is unable to remove a cause (side curl of sheet) of the stacking failure. Still further, because each of the pressing parts of the electro-photographic apparatus described above forcibly presses the sheet against the sheet discharge tray, there is a problem that a scratch is left on an image formed on the sheet.
In accordance with an embodiment of the present disclosure, a curl correcting device includes a pair of fixed guides and a change-over guide. The pair of fixed guides composes a curved part of a conveyance path through which a sheet is conveyed while being curved. The change-over guide is provided to be contactable with the sheet being conveyed through the conveyance path from a radial outer side of the curved part. An outer guide composing a radial outer side of the curved part among the pair of fixed guides includes a pair of side pressing parts and a bulge part. The pair of side pressing parts is formed at both ends in a width direction orthogonal to the sheet conveyance direction. The bulge part is formed between the pair of side pressing parts so as to bulge toward the radial outer side of the curved part more than the pair of side pressing parts. The change-over guide is configured to move to a first correcting position set within the bulge part when the sheet curled along the conveyance direction is conveyed through the conveyance path and to move to a second correcting position set on the radial outer side of the curved part more than the first correcting position when the sheet curled along the width direction is conveyed through the conveyance path.
In accordance with an embodiment of the present disclosure, an image forming apparatus includes an image forming part, a fixing unit, a discharge tray and a curl correcting device. The image forming part transfers a toner image onto a sheet to form an image. The fixing unit fixes the toner image on the sheet. The discharge tray is composed as a discharge destination of the sheet which the toner image has been fixed. The curl correcting device is provided between the fixing unit and the discharge tray and corrects a curl of the sheet being conveyed toward the discharge tray. The curl correcting device includes a pair of fixed guides and a change-over guide. The pair of fixed guides composes a curved part of a conveyance path through which the sheet is conveyed while being curved. The change-over guide is provided to be contactable with the sheet being conveyed through the conveyance path from a radial outer side of the curved part. An outer guide composing a radial outer side of the curved part among the pair of fixed guides includes a pair of side pressing parts and a bulge part. The pair of side pressing parts is formed at both ends in a width direction orthogonal to the sheet conveyance direction. The bulge part is formed between the pair of side pressing parts so as to bulge toward the radial outer side of the curved part more than the pair of side pressing parts. The change-over guide is configured to move to a first correcting position set within the bulge part when the sheet curled along the conveyance direction is conveyed through the conveyance path and to move to a second correcting position set on the radial outer side of the curved part more than the first correcting position when the sheet curled along the width direction is conveyed through the conveyance path.
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.
A suitable embodiment of the present disclosure will be described below with reference to the attached drawings. It is noted that the following description will be based on directions indicated in each drawing. It is noted that a term ‘conveyance direction’ indicates a conveyance direction of a sheet S and a ‘width direction’ indicates a width direction of the sheet S orthogonal to the conveyance direction. Still further, such terms as ‘upstream’ and ‘downstream’ in the following description represent ‘upstream’, ‘downstream’ or the like in a conveying direction of a sheet S.
With reference to
As shown in
A sheet S (bundle of the sheets S) is stored in the sheet feed cassette 3. It is noted that the sheet S is not limited to be a sheet of paper and may be a resin film, and the like. The discharge tray 4 is formed with rising gradient in a direction from the rear side to the front side. The discharge tray 4 is composed as a discharge destination of the sheet S which the toner image has been fixed.
The color printer 1 includes a sheet feeding part 10, an image forming part 11, a fixing unit 12 and a curl correcting device 13 within the apparatus body 2. The sheet feeding part 10 is provided upstream of a conveying path 14 extended from the sheet feed cassette 3 to the discharge tray 4. The image forming part 11 is provided at an intermediate part of the conveying path 14. The fixing unit 12 is provided downstream of the conveying path 14. The curl correcting device 13 is provided downstream along the conveyance path 14 of the fixing unit 12.
The sheet feeding part 10 is configured to separate the sheet S within the sheet feed cassette 3 one by one and to deliver the sheet S to the conveying path 14. The image forming part 11 transfers a toner image onto the sheet S to form an image. The image forming part 11 includes four toner containers 20, an intermediate transfer belt 21, four drum units 22 and an optical scanning device 23. The four toner containers 20 are arrayed in parallel in a front-rear direction under the discharge tray 4. The intermediate transfer belt 21 is disposed under the respective toner containers 20. The four drum units 22 are arrayed in parallel in the front-rear direction under the intermediate transfer belt 21. The optical scanning unit 23 is disposed under the respective drum units 22.
The four toner containers 20 house toners (developing agents) of four colors (yellow, magenta, cyan, black). The four drum units 22 are provided corresponding to the toners of the respective colors. Each of the drum units 22 includes a photosensitive drum 30, a charging device 31, a development device 32, a primary transferring roller 33 and a cleaning device 34. Each drum unit 22 primarily transfers the toner image on the intermediate transfer belt 21. A secondary transfer roller 35 forming a secondary transfer nip part 35a is disposed on a right side of the intermediate transfer belt 21. The full-color toner image borne on the intermediate transfer belt 21 is transferred onto the sheet S passing through the secondary transfer roller 35.
As shown in
The curl correcting device 13 is provided between the fixing unit 12 and the discharge tray 4. The curl correcting device 13 is provided to de curl the sheet S conveyed toward the discharge tray 4 as described later in detail.
By the way, as shown in
Next, reference to
As shown in
As shown in
The discharge part 40 includes a first discharge roller pair 41 and a second discharge roller pair 42. The first discharge roller pair 41 is disposed vicinity above the fixing unit 12 (upstream of the curved part 14a). The second discharge roller pair 42 is disposed at an inside of the apparatus in a vicinity of the discharge port 2a (downstream of the curved part 14a).
The first discharge roller pair 41 (discharge roller pair) includes a first driving roller 41a and a first driven roller 41b in pressure contact with the first driving roller 41a. The respective rollers 41a and 41b are formed into a cylindrical shape lengthy in the width direction (left-right direction). The first driving roller 41a rotates centering on a shaft by being driven by a driving motor. The first driven roller 41b forms a first nip part 41c (nip part) by pressure contact with the first driving roller 41a. The first driven roller 41b rotates following the first driving roller 41a. The first discharge roller pair 41 nips the sheet S at the first nip part 41c and feeds the sheet S toward the curved part 14a of the conveyance path 14.
Similarly to the first discharge roller pair 41, the second discharge roller pair 42 includes a second driving roller pair 42a and a second driven roller pair 42b being pressure contact with the second driving roller pair 42 a so as to form a second nip part 42c. The second discharge roller pair 42 nips the sheet S at the second nip part 42c and feeds the sheet S toward the discharge tray 4. It is noted that because the second discharge roller pair 42 is configured almost in the same manner with the first discharge roller pair 41, a detailed description thereof will be omitted below. It is noted that the respective driving rollers 41a and 42a to be driven are disposed on radial outer sides of the curved part 14a, and the respective driven rollers 41b and 42b are disposed on radial inner sides of the curved part 14a.
The correcting part 50 includes a pair of upper and lower fixed guides 51 and a change-over guide 52. The pair of upper and lower fixed guides 51 composes the curved part 14a of the conveyance path 14 through which the sheet S is conveyed while being curved. The change-over guide 52 is provided so as to be contactable with the sheet S being conveyed through the conveyance path 14 from the radial outer side of the curved part 14a.
As shown in
As shown in
As shown in
As shown in
As shown in
The rotating shaft 52a is formed into a shape of a bar extending in the front-rear direction and is rotatably supported by the apparatus body 2. The rotating shaft 52a is provided downstream of the conveyance path 14 (the curved part 14a) extending so as to curve from the first nip part 41c of the first discharge roller pair 41 (see
The pair of left and right guide pieces 52b is formed approximately into a shape of a bar extending upstream from the rotating shaft 52a, respectively. The pair of left and right guide pieces 52b is integrally formed with the rotating shaft 52a at a position corresponding to the respective guide holes 55 of the outer guide 51b. The pair of left and right guide pieces 52b penetrates through the corresponding guide holes 55 and extends from the rotating shaft 52a toward the first nip part 41c. More specifically, the respective guide pieces 52b extend to the rear side beyond a vertical line VL passing through the first nip part 41c (see
The respective guide pieces 52b are turnably provided centering on the rotating shaft 52a. The respective guide pieces 52b are configured to move between a first correcting position P1 and a second correcting position P2 (see
The torsion coil spring 52c applies a rotational force to the rotating shaft 52a such that each guide piece 52b is biased toward the first correcting position P1. That is, each guide piece 52b is always biased toward the first correcting position P1. A biasing force of the torsion coil spring 52c is set so as to restrict the turn of each guide piece 52b when the sheet S fed by the first discharge roller pair 41 pushes the rotating shaft 52a side rather than a center in a lengthwise direction of each guide piece 52b.
Next, reference to
As shown in
Here, if the sheet S fed by the first discharge roller pair 41 is curled regularly, the sheet S abuts against the rotating shaft 52a side rather than the center in the lengthwise direction of the respective guide pieces 52b (see a broken line circle in
As shown in
Meanwhile, as shown in
As shown in
As described above, the curl correcting device 13 corrects the curl (regular curl, side curl) of the sheet S generated after passing through the fixing unit 12. The sheet S is decurled while passing through the conveyance path 14 (the curved part 14a). The decurled sheet S passes through the second nip part 42c of the second discharge roller pair 42 and is discharged by the discharge tray 4 (see
As described above, the respective guide pieces 52b displaced to the first correcting position P1 correct the regular curl by acting so as to apply a side curl on the sheet S. Meanwhile, the respective guide pieces 52b displaced to the second correcting position P2 correct the side curl by acting so as to apply a regular curl on the sheet S. Thus, the curl correcting device 13 of the first embodiment described above can perform the curl correction corresponding to the direction of the curl by displacing the change-over guide 52 (the respective guide pieces 52b).
Still further, the curl correcting device 13 of the first embodiment can appropriately correct the regular curl of the sheet S by providing the two guide pieces 52 linear-symmetrically. Still further, because pressure receiving from the sheet S being conveyed is dispersed to the two guide pieces 52b, it is possible to prevent scratches from being left on the sheet S.
Next, reference to
As shown in
A change-over guide 62 of the correcting part 61 includes a rotating shaft 62a, a pair of left and right guide pieces 62b, a torsion coil spring 62c and a pair of left and right guide rollers 63.
The rotating shaft 62a is provided on the radial outer side of the outer guide 51b and vicinity above the first driving roller 41a (see
The pair of left and right guide rollers 63, i.e., rotators, is supported by the guide pieces 62b so as to rotate centering on a shaft extending in the width direction. The respective guide rollers 63 rotate in contact with the sheet S conveyed through the curved part 14a.
The driving part 70 includes a pair of left and right change-over cams 71 and a cam motor 72.
The pair of left and right change-over cams 71 is fixed at both left and right end parts of the cam shaft 71a disposed in parallel with the rotating shaft 62a. The respective change-over cams 71 are so-called eccentric cams and in contact with a cam follower part 64 formed approximately into a shape of a plate and extending downstream from the rotating shaft 62a.
The cam motor 72 is composed of a positioning controllable stepping motor or the like for example. The cam motor 72 is connected to a right end part (or a left end part) of the cam shaft 71a through a gear train not shown. The respective change-over cams 71 rotate by driving the cam motor 72.
The detecting part 80 includes three sheet detecting sensors 81 and a detection control unit 82.
The respective sheet detecting sensors 81 are noncontact type (optical, ultrasonic, or the like) distance sensor for example. The respective sheet detecting sensors 81 are provided above a downstream end part of the outer guide 51b (see
The detection control unit 82 includes an processing unit and others not shown and executing arithmetic processing in accordance to programs and others stored in a memory. The cam motor 72 and the respective sheet detecting sensors 81 are electrically connected with the detection control unit 82. The detection control unit 82 controls the cam motor 72 (more accurately a power supply not shown which supplies electricity power to the cam motor 72) based on detection results of the respective sheet detecting sensors 81.
Next, reference to
In the guide displacing operation, the change-over guide 62 moves to the first correcting position P1 when a regularly curled sheet S passes through the conveyance path 14 (see
For instance, if the regularly curled sheet S is discharged to the discharge tray 4, the respective sheet detecting sensors 81 transmit signals indicating that the sheet S passed through the conveyance path 14 (the curved part 14a) is regularly curled to the detection control unit 82. Receiving detection results of the respective sheet detecting sensors 81, the detection control unit 82 recognizes that the sheet S discharged to the discharge tray 4 is regularly curled.
Under control of the detection control unit 82, the cam motor 72 rotates the respective change-over cams 71 (the cam shaft 71a). At this time, the detection control unit 82 controls a rotation angle of the cam motor 72 such that the respective guide pieces 52b are displaced to the first correcting position P1. The respective turning change-over cams 71 press the cam follower part 64 while sliding on the cam follower part 64. Thereby, the respective guide pieces 62b turn centering on the rotating shaft 62a while resisting against a biasing force of the torsion coil spring 62c and are displaced from the second correcting position P2 to the first correcting position P1 (see
Next, if the sheet S generates a side curl, the respective sheet detecting sensors 81 transmit signals indicating that the sheet S passed through the curved part 14a is side-curled to the detection control unit 82. Receiving detection results of the respective sheet detecting sensors 81, the detection control unit 82 recognizes that the sheet S discharged to the discharge tray 4 is side-curl.
Under control of the detection control unit 82, the cam motor 72 rotates the respective change-over cams 71 so as to displace the respective guide pieces 62b from the first correcting position P1 to the second correcting position P2. The rotating change-over cams 71 release the pressure on the cam follower part 64 while sliding on the cam follower part 64. Thereby, the respective guide pieces 62b are turned centering on the rotating shaft 62a by the biasing force of the torsion coil spring 62c and are displaced from the first correcting position P1 to the second correcting position P2 (see
According to the curl correcting device 60 of the second embodiment described above, the driving part 70 moves the change-over guide 62 (the respective guide pieces 62b) based on the detection results of the respective sheet detecting sensors 81. The driving part 70 can adjust a moving amount of the change-over guide 62 (the respective guide pieces 62b) corresponding to a condition of the curl detected by the respective sheet detecting sensors 81. This arrangement makes it possible to decurl optimally corresponding to size (radius and others) of the curl.
It is noted that in the guide displacing operation described above, while the respective guide pieces 62b are displaced to the two positions (the first and second correcting positions P1 and P2), the present disclosure is not limited to such configuration. For instance, the driving part 70 (the detection control unit 82) may be configured so as to displace the respective guide pieces 62b among three or more positions. It is noted that the sheet detecting sensors 81 may be provided by three or more.
The guide rollers 63 pivotally supported by the respective guide pieces 62b come into contact with the sheet S passing through the conveyance path 14 (the curved part 14a). Because the respective guide rollers 63 rotate on the sheet S, it is possible to assure smooth conveyance of the sheet S and to correct the curl. It is noted that the respective guide rollers 63 may be provided on the respective guide pieces 52b of the curl correcting device 13 of the first embodiment.
It is noted that while the guide displacing operation described above is controlled by the detection control unit 82, the present disclosure is not limited to such configuration and a control unit executing the image forming process may function as the detection control unit 82. Still further, the rotating shaft 62a of the curl correcting device 60 of the second embodiment is provided upstream of the curved part 14a, the present disclosure is not limited such configuration and the rotating shaft 62a may be provided downstream of the curved part 14a.
It is noted that while one rotating shaft 52a (62a) and one torsion coil spring 52c (62c) are commonly used for the two guide pieces 52b (62b) in the curl correcting device 13 (60) of the first embodiment (the second embodiment), the present disclosure is not limited to such configuration. For instance, the rotating shaft 52a (62a) and the torsion coil spring 52c (62c) may be provided per each guide piece 52b (62b). That is, a plurality of change-over guides 52 (62) including one rotating shaft 52a (62a), one guide piece 52b (62b), and one torsion coil spring 52c (62c) may be provided. Still further, one or more change-over guides 52 (62), i.e., guide pieces 52b (62b) may be provided.
Still further, the case in which the present disclosure is applied to the color printer 1 as one example has been described in the present embodiment, the present disclosure is not limited to such case, and the present disclosure is applicable also to a monochrome printer, a facsimile, a multi-function printer, and the like.
While the preferable embodiment and its modified example of the sheet correcting device and the image forming apparatus or the like of the present disclosure have been described above and various technically preferable configurations have been illustrated, a technical range of the disclosure is not to be restricted by the description and illustration of the embodiment. Further, the components in the embodiment of the disclosure may be suitably replaced with other components, or variously combined with the other components. The claims are not restricted by the description of the embodiment of the disclosure as mentioned above.
Number | Date | Country | Kind |
---|---|---|---|
2015-122803 | Jun 2015 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
5202737 | Hollar | Apr 1993 | A |
8862047 | Furushige | Oct 2014 | B2 |
9020412 | Osaki | Apr 2015 | B2 |
20010024013 | Horikoshi | Sep 2001 | A1 |
20050018029 | Takagi | Jan 2005 | A1 |
20090003912 | Nagasaki | Jan 2009 | A1 |
20100086338 | Hara | Apr 2010 | A1 |
20140140746 | Egawa | May 2014 | A1 |
20160355029 | Kondo | Dec 2016 | A1 |
Number | Date | Country |
---|---|---|
2011-133794 | Jul 2011 | JP |
Number | Date | Country | |
---|---|---|---|
20160370749 A1 | Dec 2016 | US |