JP3932911B2 - Reverse conveying apparatus and image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reverse conveyance device that reverses and conveys a sheet, and an image forming apparatus having the reverse conveyance device.
[0002]
[Prior art]
In a copying machine, a scanner, a facsimile machine, a printer, and the like, the front and back of a sheet are reversed in the course of conveying a document or a recording material. That is, the reversal conveying device is used for a sheet conveying unit for performing double-sided reading and double-sided image formation, and a reverse sheet discharging unit for reversing the front and back of a sheet on which an image is formed face-up and discharging the sheet face-down.
[0003]
Conventionally, there are the following reverse transfer apparatuses.
(1) The reversal conveyance unit is provided with a first conveyance path for carrying a sheet, a second conveyance path for reversing the conveyance direction of the sheet, and a third conveyance path for conveying the reversed sheet. In the connecting portion of the first, second, and third conveyance paths, a switching guide that guides the sheet from the first conveyance path to the second conveyance path during carry-in and guides the sheet from the second conveyance path to the third conveyance path during unloading. Means are provided. The switching guide means is driven by driving means to switch the guide function.
[0004]
(2) An elastic guide member such as PET is provided at the connecting portion of the first, second, and third conveyance paths, and when carrying in, the sheet pushes and deforms the elastic guide member to make the second from the first conveyance path. The sheet advances to the conveyance path, and when unloaded, the sheet is guided by the elastic guide member and proceeds from the second conveyance path to the third conveyance path.
[0005]
(3) The first transport path and the second transport path are connected to form a bent transport path, and the second transport path and the carry-in portion of the third transport path are connected to form a straight transport path. The With this configuration, when the sheet is carried in, the sheet enters the second conveyance path while being bent between the first conveyance path and the second conveyance path. However, when the sheet is unloaded, the sheet is not the first conveyance path but the first conveyance path. Proceed to 3 transport paths.
[0006]
[Problems to be solved by the invention]
The reversing and conveying apparatus of (1) has a problem that the mechanism is complicated and lacks stability and easily breaks down. In particular, in a high-speed machine, the switching guide member performs switching operation in a short time, so that the operation stability is lowered. Further, the switching guide member is often formed of a resin, but has a problem that its life is short because it is worn by a sheet conveyed at high speed.
[0007]
The reversing and conveying apparatus of (2) has a problem that its life is short because the elastic guide member is worn and its guiding function is lowered.
[0008]
The problem in the reversing and conveying apparatus (3) will be described with reference to FIG.
The first transport path H1 is formed by the rear part of the guide member G1 and the guide member G2, the second transport path H2 is formed by the front part of the guide member G1 and the rear part of the guide member G3, and the third transport path H3 is a guide. It is formed by the front part of the member G3 and the guide member G4.
[0009]
The sheet SH is conveyed by a conveyance roller R1 provided in the first conveyance path H1, travels to the right in the drawing as indicated by a solid arrow X1 in the first conveyance path H1, is conveyed into the second conveyance path H2, and is reversely conveyed. It is transported by the roller R2 and proceeds to the right along the second transport path H2. The reverse conveying roller R2 reverses the rotation direction at the point P1 where the trailing end of the sheet SH has passed the leading end of the guide member G2, and conveys the sheet SH to the left as indicated by the dotted arrow X2. The leading end of the sheet SH whose direction of travel has been reversed proceeds not to the first transport path H1 but to the third transport path H3 due to the straightness of the sheet. Thus, the sheet SH is reversed and conveyed, and the front and back are reversed when the sheet after reversal is conveyed in the same direction as the direction before reversal.
[0010]
As shown in the figure, the direction d1 of the first transport path H1 and the direction d2 of the second transport path H2 intersect at an angle θ, whereas the direction d2 of the second transport path H2 and the third transport path H3 The direction d3 of the rear end connected to the second transport path H2 is the same direction.
[0011]
By such setting of the directions of the first, second, and third conveyance paths, the sheet SH advances while being bent by the first and second conveyance paths when it is carried into the reverse conveyance apparatus, The sheet SH automatically advances from the second conveyance path to the third conveyance path due to its straightness.
[0012]
In the mechanism that reversely conveys the sheet SH by setting the angular relationship between the first, second, and third conveyance paths described above, the sheet is reliably guided at the connecting portion RK of the first, second, and third conveyance paths. In order to achieve this, the conveyance interval w is reduced as much as possible.
[0013]
In the case of a sheet thinner than plain paper, smooth and stable conveyance is performed by the reverse conveyance device shown in FIG. 1, but in the case of thick paper, the leading edge of the sheet collides with the position of the point P2 of the guide member G3. There is a problem of causing an impact. Due to this impact, problems such as step-out of the stepping motor used as the drive source of the reversing transport device are likely to occur.
[0014]
In order to avoid this problem, if the conveyance path width in the connecting portion RK is widened, there arises a problem that the conveyance of thin paper becomes unstable, and it is difficult to configure so as to perform stable reverse conveyance for various sheets. become.
[0015]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems in a conventional reverse conveying apparatus, and to provide a reverse conveying apparatus capable of stably conveying various sheets and an image forming apparatus having such a reverse conveying apparatus.
[0016]
[Means for Solving the Problems]
The object of the present invention is achieved by the following invention.
[0017]
1. In a reversing conveyance device that conveys a sheet from the first conveyance path in one direction and carries it into the second conveyance path, then reverses the conveyance direction in the second conveyance path and conveys the sheet to the third conveyance path.
A bent conveyance path is formed by the first conveyance path and the second conveyance path so that a sheet that has left the first conveyance path is automatically directed to the third conveyance path when the conveyance direction is reversed. And a connecting portion that is connected so as to form a straight conveying path between the second conveying path and the carry-in portion of the third conveying path , and the second conveying path is connected to the connecting portion. A reversing / conveying apparatus, comprising: a movable guide member urged so that a front end portion of the sheet is directed toward the third conveying path when the sheet is reversed.
[0018]
2. In the connecting portion, the conveyance directions of the first conveyance path and the second conveyance path intersect so as to bend the sheet, and the conveyance directions of the second conveyance path and the third conveyance path are substantially parallel. 2. The reversing and conveying apparatus according to 1 above.
[0019]
3. 3. The reverse conveying apparatus according to 1 or 2, wherein the movable guide member is made of a metal plate biased by a spring.
[0020]
4). 3. The reversing and conveying apparatus according to 1 or 2, wherein the movable guide member is made of a metal plate biased by gravity.
[0021]
5). 5. The reverse conveying apparatus according to any one of 1 to 4, wherein a plurality of the movable guide members are provided in a conveying width direction.
[0022]
6). An image forming apparatus comprising the reversing and conveying device according to any one of 1 to 5 provided in a reversing unit of a paper discharge unit.
[0023]
7). 6. An image forming apparatus comprising the reverse conveying device according to any one of 1 to 5 in a back surface image forming sheet feeding unit.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example in which the reverse conveying device according to the embodiment of the present invention is applied to the recording material conveying unit of the image forming apparatus will be described. Therefore, in the following, the reverse conveyance of the recording material, which is an example of the sheet, will be described. FIG. 2 shows an image forming apparatus according to an embodiment of the present invention.
[0025]
The image forming apparatus according to the present embodiment is provided with an automatic document feeder 1 at the upper part of the apparatus main body, and the image reading apparatus 2, the image forming unit 3, the storage unit 4, the conveyance path 5, and the discharge unit in the copier main body. A paper / refeed unit 6 is provided.
[0026]
The automatic document feeder 1 is an apparatus that is provided on the upper part of the copying machine main body, feeds documents one by one, conveys them to the image reading position, and discharges the document after image reading. The automatic document feeder 1 transports a document placed on the document placing table 11 on which the document is placed, a document separating unit 12 that separates the documents placed on the document placing table 11 one by one, and a document separated by the document separating unit 12. An original document transport unit 13, a document discharge unit 14 that discharges the document transported by the document transport unit 13, a document discharge table 15 that receives and places the document discharged by the document discharge unit 14, and A document reversing unit 16 is provided for reversing the front and back of the document when reading images on both sides of the document.
[0027]
A plurality of documents placed on the document placement table 11 are separated by the document separation unit 12 and conveyed one by one. The document separated and transported by the document separation unit 12 is transported by the document transport unit 13, and the image of the document is read through the slit 21 by the image reading device 2 provided below. The document whose image has been read is discharged onto the document discharge table 15 by the document discharge unit 14. When reading images on both sides of a document, the document on which the image on the front side has been read is reversed by the document reversing unit 16 and conveyed again by the document conveying unit 13, and is slit by the image reading unit. Through 21, the image on the back side of the document is read. Then, the original on which the image on the back side is read is discharged onto the original discharge table 15 by the original discharge unit 14. Such a process is repeated for the number of documents placed on the document placing table 11, and an image of the document is read.
[0028]
Further, the automatic document feeder 1 is configured to be integrally retractable, and the document is directly placed on the platen glass 22 by raising the automatic document feeder 1 and opening the platen glass 22. It is configured to be able to. In the present embodiment, the original image is read while the original is conveyed by the original conveying unit 13. However, the original conveyed by the original conveying unit 13 is stopped on the platen glass 22. You may comprise so that an image may be read above.
[0029]
The image reading device 2 is a unit that reads an image of a document and obtains image data, and is provided in an upper portion of the image forming apparatus. The image reading device 2 is a slit 21 that is a slit-shaped opening for reading an image of a document conveyed by the document conveying unit 13 of the automatic document feeder 1, and a document table for directly placing a document. A platen glass 22, a lamp 231 that is a light source for irradiating light on a document, and a first mirror 232 that integrates a first mirror 232 that reflects reflected light from the document, and reflects light from the first mirror 232. The V mirror unit 24 in which the second mirror 241 and the third mirror 242 are integrated, and an imaging lens that is an imaging unit that forms an image on the CCD 26 described later on the reflected light from the original on the slit 21 or the platen glass 22. 25 and a linear CCD 26 which is an image reading unit that photoelectrically converts the optical image formed by the imaging lens 25 to obtain image data. .
[0030]
When the image reading device 2 reads a document fed by the automatic document feeder 1, the first mirror unit 23 and the V mirror unit 24 have the first mirror unit 23 positioned below the slit 21. Then, the document conveyed on the slit 21 by the document conveying unit 13 is irradiated with light by the lamp 231, and the light reflected from the document is a first mirror 232, a second mirror 241, a third mirror 242, an imaging lens. Then, the light enters the CCD 26 via 25. The CCD 26 photoelectrically converts the incident light and reads an image of the document in the main scanning direction. On the other hand, since the document is moved in the sub-scanning direction by the document transport unit 13, the image on the entire surface of the document can be read. Image data read by the CCD 26 is appropriately subjected to image processing, and provided to a laser writing system 33 which is an exposure unit described later.
[0031]
Further, when the document is directly placed on the platen glass 22, it is possible to read the image of the document while moving the first mirror unit 23 and the V mirror unit 24 along the platen glass 22 in the right direction. it can.
[0032]
The image forming unit 3 is a unit that forms an image on a recording material that is conveyed at a predetermined process speed based on the image data obtained by the image reading unit 2. The image forming unit 3 of the present embodiment forms an image using an electrophotographic process. The image forming section 3 is read by a CCD 26 having a photoconductive drum 31 (photosensitive body) having a photoconductive photosensitive layer and carrying a toner image, a charger 32 (charging section) for uniformly charging the photosensitive drum 31. Based on the image data, a laser writing system 33 (exposure unit) that exposes the photosensitive drum 31 to form a latent image, and a developer 34 that develops the latent image on the photosensitive drum 31 to form a toner image. (Developing unit), a transfer unit 35 (transfer unit) for transferring the toner image formed on the photosensitive drum 31 onto the recording material being conveyed, and the recording material on which the toner image has been transferred onto the photosensitive drum 31 A separator 36 for separating the toner from the toner, a cleaning unit 37 for removing the toner remaining on the photosensitive drum 31 after the transfer, and a fixing unit 38 for fixing the toner image on the recording material. Around the photosensitive drum 31, a charger 32, a laser writing system 33, a developing unit 34, a transfer unit 35, a separator 36, and a cleaning unit 37 are arranged.
[0033]
The photosensitive drum 31 is rotated in the direction of the arrow by a driving unit (not shown), and the exposure is started in synchronism with the uniform charging by the charger 32 and the leading edge of the recording material conveyed from the registration roller 56 described later. A latent image is formed by the laser writing system 33 and developed by the developing device 34, and a toner image based on the image data read by the CCD 26 is formed. The formed toner image is transferred onto the recording material by the transfer device 35. The recording material to which the toner image has been transferred is separated from the photosensitive drum 31 by the separator 36 and conveyed to the fixing unit 38, where the toner image is fixed to the recording material by heating and pressing. On the other hand, the photosensitive drum 31 on which the toner image has been transferred to the recording material continues to rotate, and the toner remaining on the photosensitive drum 31 is removed by the cleaning unit 37 to be used for the next image formation.
[0034]
In the present embodiment, a pre-drum transport roller 39 for transporting the recording material fed from the registration roller 56 is provided in the vicinity of the photosensitive drum 31 between the photosensitive drum 31 and the registration roller 56. This contributes to an increase in conveying power of the recording material. Further, between the separator 36 and the fixing unit 38, in order to transport the recording material separated by the separator 36, a transport roller (not indicated) and a belt (supporting and supporting the back side of the recording material and transporting it) Unsigned).
[0035]
The storage unit 4 is a storage unit that stores a plurality of recording materials in a stacked state. In the present embodiment, the storage unit 4 includes a plurality of storage units 4, that is, a first storage unit 4 </ b> A, a second storage unit 4 </ b> B, and a third storage unit 4 </ b> C, and these storage units 4 </ b> A to 4 </ b> C are connected to the image forming unit 3. Multi-stage arrangement below. As recording materials stored in the storage units 4A to 4C, there are various media such as OHT in addition to recording materials such as plain paper and recycled paper.
[0036]
The conveyance path 5 is a part of the conveyance unit that conveys the recording material from the storage unit 4 to the image forming unit 3, and the recording material stored in each of the storage units 4 </ b> A to 4 </ b> C can be conveyed to the image forming unit 3. It is configured as follows.
[0037]
The paper discharge / refeed unit 6 discharges or reverses the recording material on which the image is formed by the image forming unit 3 onto the recording material conveyed by the conveyance path 5, and refeeds the recording material to the photosensitive drum 31. Means. The paper discharge / refeed unit 6 discharges the recording material on which the toner image is fixed from the fixing unit 38, and discharges the recording material discharged by the fixing discharge roller 61 to the outside as it is. A switching member 62 that switches the conveyance path when discharging after reversing the front and back or when re-feeding to form an image on the back, a discharge roller 63 for discharging the recording material to the outside, and a side surface of the copying machine A paper discharge tray 64 on which the recording material provided and discharged by the paper discharge roller 63 is stacked, a reversing unit 65 for reversing the recording material with the image surface on top and the image surface on the bottom, and reversing the front and back to the registration roller 56. A back surface image forming paper feed section 66 for carrying and feeding paper is provided.
[0038]
When the recording material on which the image is formed by the image forming unit 3 is discharged as it is, that is, with the surface on which the image is formed facing upward, the switching member 62 is set to the straight guide position, and the fixing discharge roller 61 and the discharge roller 63 are set. As a result, the sheet is discharged to a discharge tray 64 outside the apparatus. In addition, when the image-formed recording material is turned upside down and discharged, that is, when the image-formed surface is discharged downward, the angle of the switching member 62 is switched and conveyed by the fixing discharge roller 61. The recording material is once transported in the direction of the reversing unit 65, and after the recording material has passed through the switching member 62, the transporting direction of the reversing unit 65 is reversed and discharged by the paper discharge roller 63 to the paper discharge tray 64 outside the apparatus. And discharge. On the other hand, when forming an image on the back surface of the recording material, the switching member 62 is reversed and switched in the same manner as described above, and the recording material conveyed by the fixing discharge roller 61 is conveyed in the direction of the reversing unit 65. Then, the reverse image is reversed by causing the back surface image forming paper feed section 66 to perform the switchback, and the paper is conveyed to the registration roller 56.
[0039]
FIG. 3 is a partial cross-sectional view of the reverse conveying device 100 of the back surface image forming paper feed section 66. The first transport path H1 is formed by an upper guide member G1A and a lower guide member G2, and the second transport path H2 is an upper guide member G1B and a lower guide member that are arranged forward when the guide member G1A is loaded. The third transport path H3 is formed by the front part of the lower guide member G3 and the upper guide member G4. In the above description, “front” and “rear” are based on the traveling direction of the recording material RP. Accordingly, when the recording material RP is carried in, the right side in the drawing is the front and the left side is the rear, and when the recording material RP is carried out, the left is the front and the right is the rear. At the front end of the guide member G1A when it is carried in, a bent portion G1AK that is bent so that the position coincides with the rear part G1BK when the guide member G1B is carried in is provided. As shown in the figure, the bent portion G1AK makes the conveyance path interval W in the connecting portion RK wider than the conveyance path interval w in the connecting portion RK of the conventional reverse conveying apparatus shown in FIG. R1 is a conveyance roller that conveys the recording material RP in one direction to the right in the figure, and R2 is a reverse conveyance roller that reverses the rotation direction after conveying the recording material RP in the right direction in the figure and conveys the recording material RP in the left direction in the figure. Yes, each driven by a stepping motor.
[0040]
The connecting portion RK is provided with a movable guide member KG that is pivotally supported by the shaft AX and is urged clockwise by a coil spring CB as urging means. The movable guide member KG is supported by a stopper (not shown) and forms a narrow conveyance path as shown.
[0041]
The recording material RP is transported by a transport roller R1 provided in the first transport path H1, travels to the right in the first transport path H1, is transported to the second transport path H2, and is transported by the reverse transport roller R2. To the right along the second transport path H2. When the rear end of the recording material RP passes the front end of the guide member G2 and reaches the position of the point P1 guided by the movable guide member KG, the reverse conveying roller R2 reverses the rotation direction, and the recording material RP is moved to the left. Transport in the direction. The leading end of the recording material RP whose direction of travel has been reversed proceeds not to the first transport path H1 but to the third transport path H3 due to its straight advanceability. In this way, the recording material RP is reversed and conveyed, and the front and back are reversed when the reversed recording material RP is conveyed in the same direction as the direction before the reversal.
[0042]
As shown in the figure, the direction d1 of the first transport path H1 and the direction d2 of the second transport path H2 intersect with each other at an angle θ, whereas the direction d2 of the second transport path and the second of the third transport path H3. The direction d3 of the rear end connected to the transport path H2 is substantially parallel.
[0043]
Due to the setting of the directions of the first, second, and third transport paths, the recording material RP advances while being bent by the first and second transport paths when it is carried into the reversing transport apparatus, but when it is unloaded. The recording material RP automatically advances from the second conveyance path to the third conveyance path due to its straightness. Since the leading end of the recording material RP when being unloaded is regulated by the movable guide member KG and enters the third transport path H3, the transport path in the reverse transport is reliably switched, and the reverse transport is stably performed. . Further, by providing the movable guide member KG, the recording material RP is reliably guided to the third transport path H3 even in the configuration in which the transport path interval in the connecting portion RK is widened as indicated by W.
[0044]
The thin paper is guided by the movable guide member KG and proceeds from the first transport path H1 to the second transport path H2, but in the case of thick paper, the second transport path H2 is pushed and retracted by the stiffness. Proceed to. As a result, even when transporting thick paper, the front end of the recording material RP does not collide with the guide member G3 due to a strong impact at the bent portion of the transport path formed in the connecting portion. Therefore, even from high speed conveyance with a high linear velocity, it is stably conveyed from thin paper to thick paper.
[0045]
FIG. 4 is a partial plan view of the back surface image forming paper feed section 66. As shown in the figure, a plurality of movable guide members KG are arranged around the center line L of the transport path. That is, the movable guide member KG1 is provided at the center of the transport path, the two movable guide members KG2 are provided at one end, and the two movable guide members KG3 are provided at the other end. These movable guide members KG1, KG2, and KG3 are each biased by a coil spring CB. With such a plurality of movable guide members KG1, KG2, and KG3, recording materials of various sizes can be stably reversed and conveyed.
[0046]
As the movable guide members KG and KG1 to KG3, it is desirable to use a metal plate that is not subjected to wear by the recording material RP to be conveyed. In addition to the coil spring CB, gravity can also be used to urge the movable guide members KG, KG1 to KG3 at the time of unloading in the direction of narrowing the conveyance path width.
[0047]
The reversing and conveying apparatus described above can be used for the reversing unit 65 in the paper discharge unit in addition to the back surface image forming paper feeding unit 66.
[0048]
【The invention's effect】
According to the invention of claim 1 or 2, a reversal conveying apparatus that can stably reversely convey various types of sheets, has high durability, and prevents troubles such as a drive stop that easily occur during cardboard conveyance. Is realized. In particular, the stability of the reversing transport apparatus that transports at a high speed with a high transport linear speed is improved.
[0049]
According to the third or fourth aspect of the invention, a reversing and conveying apparatus with extremely high durability is realized.
[0050]
According to the invention of claim 5, sheets of various sizes are stably reversed and conveyed.
According to the sixth aspect of the present invention, it is possible to realize a highly durable image forming apparatus having a stable reverse paper discharge function.
[0051]
According to the seventh aspect of the present invention, it is possible to realize a highly durable double-sided image forming apparatus having stable recording material transportability at the time of backside image formation.
[Brief description of the drawings]
FIG. 1 is a diagram showing a conventional reverse conveying apparatus.
FIG. 2 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating a reverse conveyance device according to an embodiment of the present invention.
FIG. 4 is a partial plan view of a back surface image forming sheet feeding unit.
[Explanation of symbols]
CB Coil springs G1A, G1B, G2, G3, G4 Guide member H1 First transport path H2 Second transport path H3 Third transport path KG, KG1 to KD3 Movable guide members

Claims (7)

In a reversing conveyance device that conveys a sheet from the first conveyance path in one direction and carries it into the second conveyance path, then reverses the conveyance direction in the second conveyance path and conveys the sheet to the third conveyance path.
A bent conveyance path is formed by the first conveyance path and the second conveyance path so that a sheet that has left the first conveyance path is automatically directed to the third conveyance path when the conveyance direction is reversed. And a connecting portion that is connected so as to form a straight conveyance path with the second conveyance path and the carry-in portion of the third conveyance path,
A reversing and conveying apparatus, wherein the connecting portion is provided with a movable guide member biased so that a sheet leading end is directed to the third conveying path when the sheet is reversed in the second conveying path.   In the connecting portion, the conveyance directions of the first conveyance path and the second conveyance path intersect so as to bend the sheet, and the conveyance directions of the second conveyance path and the third conveyance path are substantially parallel. The reverse conveying device according to claim 1.   The reverse conveying device according to claim 1, wherein the movable guide member is made of a metal plate biased by a spring.   The reverse conveying device according to claim 1, wherein the movable guide member is made of a metal plate biased by gravity.   The reversal conveyance apparatus according to claim 1, wherein a plurality of the movable guide members are provided in a conveyance width direction.   An image forming apparatus comprising: the reversing conveyance device according to claim 1 provided in a reversing unit of a paper discharge unit.   An image forming apparatus comprising the reverse conveying device according to claim 1 in a back surface image forming sheet feeding unit.

Images