JP2003212397A - Reversal carrier device and picture image formation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reversal carrier device to solve a problem that a conventional reversal carrier device is low in durability, low in stability at the time of high speed carriage, hard to stably carry thin paper to thick paper, etc., and especially in the case of high speed carriage. <P>SOLUTION: The sheet after reversed is directed to a third carrier passage by providing a movable guide member energized to a connecting part of a first carrier passage to deposit the sheet, a second carrier passage to reversely carry the sheet and the third carrier passage to deliver the sheet. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversing / conveying device for reversing and conveying a sheet, and an image forming apparatus having the reversing / conveying device.

[0002]

2. Description of the Related Art Copiers, scanners, facsimile machines,
In a printer or the like, the front and back of a sheet are reversed in the process of conveying a document or recording material. That is, the reversal conveyance device is used for a sheet conveyance unit for performing double-sided reading and double-sided image formation, and a reversal sheet ejection unit for reversing the front and back of a sheet having an image formed face up and ejecting the sheet face down.

Conventionally, there is the following one as such an inversion conveying device. The reversal conveyance unit is provided with a first conveyance path for carrying in a sheet, a second conveyance path for reversing the conveyance direction of the sheet, and a third conveyance path for conveying the sheet after reversal. 2, a switching guide means for guiding the sheet from the first transport path to the second transport path at the time of loading and at the connecting portion of the third transport path, and for guiding the sheet from the second transport path to the third transport path at the time of unloading. . The switching guide means is driven by the drive means to switch the guide function.

An elastic guide member such as PET is provided at the connecting portion of the first, second, and third conveying paths, and at the time of carrying in, the sheet pushes and deforms the elastic guiding member so that the sheet moves from the first conveying path to the second conveying path. The sheet advances to the conveyance path, and at the time of unloading, the sheet is guided by the elastic guide member and advances from the second conveyance path to the third conveyance path.

The first conveying path and the second conveying path are connected so as to form a curved conveying path, and the second conveying path and the carry-in section of the third conveying path are connected so as to form a straight conveying path. It With this configuration, when the sheet is carried in, the sheet enters the second transportation path while being bent between the first transportation path and the second transportation path.
Proceed to the third transport path instead of the transport path.

[0006]

The above-mentioned reversing conveyance device has a problem that it lacks stability and is liable to malfunction due to its complicated mechanism. Particularly, in a high-speed machine, the switching guide member is switched in a short time, so that the stability of the operation is deteriorated. Further, although the switching guide member is often formed of resin, there is a problem that its life is short because it is worn by a sheet conveyed at high speed.

The above-described reversing conveyance device has a problem that the service life is short because the elastic guide member is worn and the guide function thereof is deteriorated.

FIG. 1 shows the problem in the above-mentioned reverse conveyance device.
Will be described. 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 guided. It is formed by the front portion of the member G3 and the guide member G4.

The sheet SH is conveyed by the conveying rollers R1 provided in the first conveying path H1 and advances along the first conveying path H1 to the right in the figure as indicated by the solid arrow X1, and the second conveying path H1.
2 and is conveyed by the reverse conveyance roller R2 to the second
Proceed to the right on the transport path H2. At the position of the point P1 where the rear end of the sheet SH has passed the front end of the guide member G2, the reversal conveyance roller R2 reverses the rotation direction, and conveys the sheet SH leftward as indicated by a dotted arrow X2. Due to the straightness of the sheet, the leading edge of the sheet SH whose direction of travel is reversed is the first transport path H.
Instead of 1, proceed to the third transport path H3. In this way, the sheet SH is reversed and conveyed, and when the reversed sheet is conveyed in the same direction as the direction before the reverse, the front and back are reversed.

As shown, 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 direction d3 of the rear end portion of the third transport path H3 connected to the second transport path H2. And are in the same direction.

By setting the directions of the first, second, and third transport paths as described above, the sheet SH is bent by the first and second transport paths when it is carried into the reversal transport apparatus, and advances. At the time of unloading, the sheet SH automatically advances from the second transport path to the third transport path due to its straightness.

In the above-described mechanism for reversing and conveying the sheet SH by setting the angular relationship of the first, second, and third conveying paths, the sheet is guided in the connecting portion RK of the first, second, and third conveying paths. In order to ensure that the conveyance interval w is as narrow as possible.

In the case of a sheet thinner than plain paper, the reversing / conveying device shown in FIG. 1 performs smooth and stable conveyance, but in the case of thick paper, the leading end of the sheet is a guide member G.
There is a problem in that a collision occurs at the position of the point P2 of 3 and an impact is generated. Due to this impact, a stepping motor used as a drive source of the reversing conveyance device is liable to be out of order.

In order to avoid this problem, if the width of the conveying path in the connecting portion RK is widened, there arises a problem that the thin paper cannot be stably conveyed, and various sheets are stably reversed and conveyed. Becomes difficult.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in a conventional reversing / conveying device and to provide a reversing / conveying device capable of stably conveying various sheets and an image forming apparatus having the reversing / conveying device. And

[0016]

The above-mentioned objects of the present invention are achieved by the following inventions.

1. In a reversing conveyance device that conveys a sheet in one direction from the first conveyance path and carries it into the second conveyance path, and then reverses the conveyance direction in the second conveyance path to convey the sheet to the third conveyance path. In the connecting portion that connects the first transport path and the second transport path and that connects the second transport path and the third transport path, the first transport path is separated when the transport direction is reversed. The first conveyance path, the second conveyance path, and the third conveyance path are connected to each other so that the sheet is automatically directed to the third conveyance path, and the second portion is connected to the connection portion. A reversing conveyance device comprising a movable guide member that is biased to direct the leading edge of the sheet toward the third conveyance path when the sheet is reversed on the conveyance path.

2. In the connecting portion, the transport directions of the first transport path and the second transport path intersect so as to bend the sheet, and the transport directions of the second transport path and the third transport path are substantially parallel. 2. The reversing conveyance device described in 1 above.

3. 3. The reversing / conveying device as described in 1 or 2, wherein the movable guide member is made of a metal plate urged by a spring.

4. 3. The reversing / conveying device as described in 1 or 2, wherein the movable guide member is made of a metal plate urged by gravity.

5. The reversing conveyance device according to any one of the above 1 to 4, wherein a plurality of the movable guide members are provided in the conveyance width direction.

6. An image forming apparatus, wherein the reversing / conveying device according to any one of 1 to 5 is provided in a reversing unit of a sheet discharging unit.

7. An image forming apparatus, wherein the reverse conveyance device according to any one of 1 to 5 is provided in a back side image forming paper feeding section.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An example in which the reversal conveying device according to the embodiment of the present invention is applied to a recording material conveying portion of an image forming apparatus will be described below. Therefore, the reverse conveyance of the recording material, which is an example of the sheet, will be described below. FIG. 2 shows an image forming apparatus according to an embodiment of the present invention.

In the image forming apparatus of this embodiment, the automatic document feeder 1 is provided on the upper part of the main body of the apparatus, and the image reading apparatus 2, the image forming section 3, the storage section 4, the conveying path 5 are provided in the main body of the copying machine. It also has a paper discharge / refeed unit 6.

The automatic document feeder 1 is a device which is provided on the upper part of the main body of the copying machine, sends out the originals one by one, conveys them to the image reading position of the originals, and discharges the originals after the image reading. The automatic document feeder 1 includes a document placing table 11 on which a document is placed, a document separating section 12 that separates the documents placed on the document placing table 11 one by one, and a document separated by the document separating section 12 is conveyed. A document transport unit 13, a document discharge unit 14 that discharges the document transported by the document transport unit 13, a document discharge tray 15 that receives and places the document discharged by the document discharge unit 14, and It has a document reversing unit 16 for reversing the front and back of a document when reading images on both sides of the document.

A plurality of originals placed on the original placing table 11 are separated by the original separating section 12 and conveyed one by one. The document separated and conveyed by the document separation unit 12 is conveyed by the document conveyance unit 13, and the image of the document is read by the image reading device 2 provided below through the slit 21. The original from which the image was read is
Documents are discharged onto the document discharge tray 15 by the document discharge unit 14. When reading images on both sides of a document, the document whose front side image has been read is reversed by the document reversing unit 16 so that the document is 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 document from which the image on the back side is read is discharged onto the document discharge tray 15 by the document discharge unit 14. Such steps are repeated for the number of originals placed on the original placing table 11, and the image of the original is read.

Further, the automatic document feeder 1 is constructed so as to be integrally foldable. When the automatic document feeder 1 is raised to open the platen glass 22, the document is directly placed on the platen glass 22. It is configured so that it can be placed. In the present embodiment, while the original document is conveyed by the original document conveyance section 13 and the image of the original document is read, the original document conveyed by the original document conveyance section 13 is kept stationary on the platen glass 22. It may be configured to read the image above.

The image reading device 2 is a means for reading an image of a document and obtaining image data, and is provided on the upper part of the image forming device. 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 the document. A platen glass 22 and a lamp 2 which is a light source for irradiating a document with light
31 and a first mirror 232 for reflecting the reflected light from the document
And a second mirror 241 and a second mirror 241 for reflecting light from the first mirror 232.
A V mirror unit 24 in which a mirror 242 is integrated,
An image forming lens 25 which is an image forming unit for forming an image of reflected light from a document on the slit 21 or the platen glass 22 on a CCD 26 described later, and an optical image formed by the image forming lens 25 is photoelectrically converted. It has a linear CCD 26 which is an image reading unit for obtaining image data.

When the image reading device 2 reads a document sent by the automatic document feeding device 1, the first mirror unit 23 and the V mirror unit 24 are positioned so that the first mirror unit 23 is located below the slit 21. There is. Then, the original document conveyed on the slit 21 by the original document conveyance unit 13 is irradiated with light by the lamp 231, and the light reflected from the original document is reflected by the first mirror 232, the second mirror 241, and the third mirror 232.
The light enters the CCD 26 via the mirror 242 and the imaging lens 25. The CCD 26 photoelectrically converts the incident light to read the image of the original in the main scanning direction. On the other hand, since the original is moved in the sub scanning direction by the original conveying unit 13, the image of the entire original can be read. The image data read by the CCD 26 is appropriately subjected to image processing and supplied to a laser writing system 33 which is an exposure unit described later.

When the original is placed directly on the platen glass 22, the image of the original is displayed while moving the first mirror unit 23 and the V mirror unit 24 to the right along the platen glass 22. Can be read.

The image forming section 3 is means for forming an image on a recording material being conveyed at a predetermined preset process speed based on the image data obtained by the image reading section 2. The image forming unit 3 of the present embodiment forms an image using an electrophotographic process. The image forming unit 3
Based on the photoconductor drum 31 (photoconductor) having a photoconductive photosensitive layer and carrying a toner image, the charger 32 (charging unit) for uniformly charging the photoconductor drum 31, and the image data read by the CCD 26, A laser writing system 33 (exposure unit) that exposes the photosensitive drum 31 to form a latent image, and a developing unit 34 that develops the latent image on the photosensitive drum 31 to form a toner image.
(Developing unit), transfer device 35 (transfer unit) for transferring the toner image formed on photoconductor drum 31 onto the conveyed recording material, and the recording material on which the toner image is transferred to photoconductor drum 3
1 has a separator 36 for separating from above, 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. The charger 3 is provided around the photosensitive drum 31.
2. A laser writing system 33, a developing device 34, a transfer device 35, a separator 36, and a cleaning unit 37 are arranged.

The photosensitive drum 31 is rotated in the direction of the arrow by a driving unit (not shown), is uniformly charged by the charger 32, and is exposed in synchronism with the leading end of the recording material conveyed from the registration roller 56 described later. The latent image formation by the laser writing system 33 started and the development by the developing device 34 are performed, 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 on which the toner image is transferred is separated from the photoconductor drum 31 by the separator 36 and is conveyed to the fixing unit 38, where the toner image is fixed on the recording material by the action of heating and pressing. On the other hand, the photoconductor drum 31 on which the toner image has been transferred to the recording material continues to rotate, and the cleaning unit 37 removes the toner remaining on the photoconductor drum 31 to be used for the next image formation.

In the present embodiment, the photosensitive drum 31
In the vicinity of the photoconductor drum 31 between the registration roller 56 and the registration roller 56, a drum front conveyance roller 39 that conveys the recording material sent from the registration roller 56 is provided, and contributes to increase the recording material conveyance force. There is. Also, the separator 3
In order to convey the recording material separated by the separator 36, a conveyance roller (no reference numeral) and a belt (no reference numeral) for supporting and conveying the back surface of the recording material are provided between the fixing roller 6 and the fixing section 38. It is provided.

The storage section 4 is a storage section for storing a plurality of recording materials in a stacked state. In the present embodiment, a plurality of storage units 4, that is, the first storage unit 4A and the second storage unit 4 are used.
B, the third storage portion 4C, and these storage portions 4A ~
4C are arranged in multiple stages below the image forming unit 3. As recording materials stored in these storage units 4A to 4C, there are various media such as OHT in addition to recording materials such as plain paper and recycled paper.

The transport path 5 is a part of the transport section for transporting the recording material from the storage section 4 to the image forming section 3, and each storage section 4A.
The recording material stored in each of 4C to 4C can be conveyed to the image forming unit 3.

The paper discharge / refeed unit 6 discharges or reverses the recording material image-formed by the image forming unit 3 on the recording material conveyed by the conveying path 5 and re-reproduces it on the photosensitive drum 31. It is a means for feeding paper. The paper discharge / refeed unit 6 discharges the recording material on which the toner image is fixed from the fixing unit 38, and the recording material discharged by the fixing discharge roller 61 to the outside of the apparatus. A switching member 62 for switching the conveyance path between when the sheet is reversed and discharged, or when the sheet is re-fed for forming an image on the back side, a discharge roller 63 for discharging the recording material to the outside of the machine, and a side surface of the copying machine. A paper discharge tray 64 provided with the recording material discharged by the paper discharge roller 63, a reversing unit 65 for reversing the recording material having the upper image surface so that the image surface is lower, and the front and back sides being reversed to the registration roller 56. Back side image forming paper feeding section 66 for carrying and feeding
Have.

When the recording material on which the image is formed by the image forming section 3 is discharged as it is, that is, when the surface on which the image is formed is discharged, the switching member 62 is set to the straight guide position, and the fixing discharge roller 61 and the discharge roller 61 are discharged. The paper rollers 63 discharge the paper to a paper discharge tray 64 outside the machine. When the recording material on which an image has been formed is reversed and discharged, that is, when the recording material is discharged with the surface on which the image is formed facing downward, the angle of the switching member 62 is switched and the recording material is conveyed by the fixing discharge roller 61. The recording material is once conveyed in the direction of the reversing unit 65, and after the recording material has passed through the switching member 62, the conveyance direction of the reversing unit 65 is reversed, and the paper is discharged to the discharge tray 64 outside the machine by the discharge rollers 63. And discharge. On the other hand, when forming an image on the back surface of the recording material,
The switching member 62 is switched and discharged similarly to the above case, the recording material conveyed by the fixing discharge roller 61 is conveyed in the direction of the reversing unit 65, and is switched back by the back side image forming paper feeding unit 66. Then, the front and back are reversed and the sheet is conveyed to the registration roller 56.

FIG. 3 is a partial cross-sectional view of the reverse conveying device 100 of the back side image forming paper feeding 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 in front of the guide member G1A when it is loaded. G
The third transport path H3 is formed by the unloading rear portion of the lower guide member G3, and the third transport path H3 is the unloading front portion of the lower guide member G3 and the upper guide member G.
4 is formed. In the above description, the front,
The rear side is based on the traveling direction of the recording material RP. Therefore, when the recording material RP is carried in, the right side in the figure is the front side and the left side is the rear side, and when carrying out, the left side is the front side and the right side is the rear side. Guide member G1
A bent portion G1A bent so that the position of the guide member G1B is aligned with the rear portion G1BK of the guiding member G1B at the time of loading.
K is provided. Due to the bent portion G1AK, as shown in the drawing, the transport path distance W in the connecting portion RK is wider than the transport path distance w in the connecting portion RK of the conventional reversing transport device shown in FIG. R1 is a conveying roller that conveys the recording material RP in the right direction in the figure, and R2 is a reverse conveying roller that conveys the recording material RP in the right direction in the figure and then reverses the rotation direction and conveys the recording material RP in the left direction in the figure. Yes, each driven by a stepping motor.

The connecting portion RK is provided with a movable guide member KG which is axially supported by the shaft AX and is urged clockwise by a coil spring CB as an urging means. Movable guide member K
G is supported by a stopper (not shown) and forms a narrow transport path as shown.

The recording material RP is conveyed by the conveying rollers R1 provided in the first conveying path H1 and advances to the right in the figure along the first conveying path H1, and is conveyed into the second conveying path H2 and the reverse conveying rollers R2. Is conveyed to the right on the second conveyance path H2. When the trailing end of the recording material RP passes the leading end of the guide member G2 and reaches the position of the point P1 guided by the movable guide member KG, the reversing conveyance roller R2 reverses the rotation direction, and the recording material RP is left. Transport in the direction. Due to its straightness, the front end of the recording material RP whose traveling direction is reversed advances to the third conveyance path H3 instead of the first conveyance path H1. In this way, the recording material RP is inverted and conveyed, and when the recording material RP after being inverted is conveyed in the same direction as the direction before being inverted, the front and back are inverted.

As shown, the direction d1 of the first transport path H1.
And the direction d2 of the second transport path H2 intersect at an angle θ, while the direction d2 of the second transport path and the third transport path H3.
Is substantially parallel to the direction d3 of the rear end portion connected to the second transport path H2.

By setting the directions of the first, second and third conveying paths as described above, the recording material RP is bent by the first and second conveying paths and advances when being conveyed into the reversing conveying device. At the time of unloading, the recording material RP automatically advances from the second transport path to the third transport path due to its straightness. Then, when the recording material RP is unloaded, the leading end is regulated by the movable guide member KG and enters the third transport path H3. Therefore, the transport path is reliably switched in the reverse transport, 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 if the transport path interval in the connecting portion RK is widened as indicated by W.

The thin paper is guided by the movable guide member KG and advances from the first transport path H1 to the second transport path H2. However, in the case of thick paper, the stiffness of the thin paper causes the movable guide member KG to be evacuated to the second position. Proceed to the transport path H2. 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 at the connecting portion. Therefore, even in high-speed conveyance with a large linear velocity, thin paper to thick paper can be stably conveyed.

As shown in FIG. 4, which is a partial plan view of the back side image forming paper feed unit 66, a plurality of movable guide members KG are arranged around the center line L of the conveying 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.
Are provided respectively. These movable guide members KG1,
Each of KG2 and KG3 is biased by a coil spring CB. A plurality of such movable guide members KG1, KG2,
With KG3, recording materials of various sizes can be stably reversed and conveyed.

As the movable guide members KG, KG1 to KG3, it is desirable to use metal plates which are not worn by the recording material RP to be conveyed. Movable guide members KG, KG1 to K
Gravity can be used in addition to the coil spring CB to urge the leading end of G3 in the direction of narrowing the width of the transport path.

The reversing and conveying device described above can be used not only for the back side image forming sheet feeding section 66 but also for the reversing section 65 in the sheet discharging section.

[0048]

According to the first or second aspect of the present invention, various kinds of sheets can be stably reversed and conveyed, and the durability is high, and obstacles such as driving stop which are likely to occur when conveying thick paper are prevented. The inverted transport device is realized. In particular, the stability of the reversing conveyance device that conveys at a high conveyance linear velocity at high speed is improved.

According to the third or fourth aspect of the present invention, a reversal conveyance device having extremely high durability is realized.

According to the fifth aspect of the present invention, sheets of various sizes are stably reversed and conveyed. According to the invention of claim 6, it is possible to realize a highly durable image forming apparatus having a stable reverse sheet discharging function.

According to the seventh aspect of the present invention, it is possible to realize a double-sided image forming apparatus having a stable recording material transporting property at the time of image formation on the back surface and having high durability.

[Brief description of drawings]

FIG. 1 is a diagram showing a conventional reversing conveyance device.

FIG. 2 is a diagram showing an image forming apparatus according to an embodiment of the present invention.

FIG. 3 is a diagram showing a reversal conveyance device according to an embodiment of the present invention.

FIG. 4 is a partial plan view of a back side image forming paper feeding unit.

[Explanation of symbols]

CB coil spring G1A, G1B, G2, G3, G4 Guide member H1 first transport path H2 second transport path H3 Third transport path KG, KG1-KD3 movable guide member

Claims (7)

[Claims] 1. A reversal conveyance in which a sheet is conveyed in one direction from a first conveyance path and is conveyed to a second conveyance path, and then the conveyance direction is reversed in the second conveyance path to convey a sheet to a third conveyance path. In the apparatus, in the connection part that connects the first transfer path and the second transfer path and connects the second transfer path and the third transfer path, the first part when the transfer direction is reversed. So that the sheet leaving the transport path is automatically directed to the third transport path,
The first transport path, the second transport path, and the third transport path are coupled to each other, and the leading end of the sheet is moved to the third transport path when the sheet is turned over in the second transport path. An inversion conveyance device, characterized in that a movable guide member biased so as to be directed to is provided. 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 intersect. The reversing conveyance device according to claim 1, wherein the reversing conveyance device is substantially parallel. 3. The movable guide member is made of a metal plate urged by a spring.
The reversal conveyance device according to 1. 4. The movable guide member is made of a metal plate biased by gravity, and the movable guide member is made of metal.
The reversal conveyance device according to 1. 5. The reversing conveyance device according to claim 1, wherein a plurality of the movable guide members are provided in a conveyance width direction. 6. An image forming apparatus, comprising the reversing / conveying device according to claim 1 provided in a reversing unit of a sheet discharging unit. 7. An image forming apparatus, wherein the reverse conveying device according to any one of claims 1 to 5 is provided in a back side image forming sheet feeding section.