JP3362085B2 - Refeeding device in image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet refeeding device in an image forming apparatus.

[0002]

2. Description of the Related Art A typical typical double-sided image forming apparatus is shown in FIG.
As shown in FIG. 12, the re-feeding device 1 and the paper feeding section
40, an image forming unit 41, a fixing unit 42, and a pair of guide plates 43.
And a transport unit 44 having a. And the transport unit 44
Is provided with a registration roller 46 in front of the image forming unit 41 and a paper discharge roller 47 downstream of the fixing unit 42, and the transport unit 44 relays a paper discharge transport unit 48 downstream of the paper discharge roller 47. It branches into a transport section 49, and a switching member 51 is provided in this branch section. Further, the re-feeding device 1 includes a relay conveyance section.
49, a transport unit 2 having a pair of guide plates 3 arranged opposite to each other, a main reversing roller 4 for reversing a sheet, and upper and lower first and second sub reversing rollers 5 and 6 7
And a sheet re-feeding section 8 for re-feeding the sheets are sequentially arranged. Reference numeral 9 denotes a carrying roller provided in the carrying section 2, and 11 denotes a re-feeding table.

[0003]

In the above-mentioned configuration, when performing double-sided image formation, the sheet fed from the sheet feeding section 40 passes through the conveying section 44 and the registration roller 46.
After the skew is corrected by the image forming unit 41, the image is formed on the entire surface by the image forming unit 41, and the image is formed on the entire surface by the fixing unit 42. After passing through the plate 3, the sheet is reversed by the main reversing roller 4 and the first and second sub reversing rollers 5 and 6 of the reversing unit 7, and is conveyed to the re-feeding table 11 of the re-feeding unit 8. Then the main reversing roller 4
The second sub-reversing roller 6 rotates in the opposite direction to re-feed the paper, and the paper is fed to the image forming portion 41 via the feeding portion 44 and is image-formed on the other surface, and the paper is fed by the paper feeding and feeding portion 48. Not ejected.

However, in such an image forming apparatus, (1) in double-sided image formation, after the preceding sheet on which one side of the image has been formed is conveyed to the re-feeding section 8 of the re-feeding apparatus 1, The sheet is re-fed by the main reversing roller 4 and the second sub reversing roller 6, and the subsequent sheet cannot be re-fed unless the re-feeding is completed. Therefore, there is a problem that the time interval between the image formation of the preceding sheet and the image formation of the following sheet becomes long, the efficiency of continuous image formation is poor, and the productivity is remarkably reduced. 2) In order to correct the skew of the sheet conveyed to the sheet re-feeding table 11 of the sheet re-feeding unit 8 after the sheet is inverted by the reversing unit 7 via the conveying unit 2 of the sheet re-feeding device 1, A side fence (not shown) that operates according to the paper size is provided in the direction perpendicular to the transport direction, and the side fence pushes the side surface of the paper. So the side fence,
In addition to requiring a drive source such as a motor for driving it, and a side fence position sensor, etc., an extra space for installing these is required, resulting in a large size. There is a problem such as becoming.

Therefore, an object of the present invention is to eliminate the problems of the conventional re-feeding device as described in (1) above, and to form the image of the preceding sheet and the image of the succeeding sheet. It is an object of the present invention to provide a re-feeding device that can shorten the time interval between the formation and continuous image formation efficiently and has high productivity. The object of the invention described in claim 3 is to solve the problem of the conventional re-feeding device as described in the above (2) and to correct the skew of the sheet conveyed to the re-feeding section. There is no need to provide a side fence, a drive source such as a motor for driving this side fence, and a position sensor for the side fence, and in addition, an extra space for installing these is not required. An object of the present invention is to provide an inexpensive re-feeding device which can be downsized.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention according to claim 1 relates to a conveying section having a pair of guide plates arranged to face each other, and a sheet. A re-feeding device in an image forming apparatus in which a reversing unit having a main reversing roller for reversing a sheet and upper and lower first and second sub-reversing rollers and a sheet re-feeding unit for re-feeding a sheet are sequentially arranged. A sheet re-feeding roller that contacts the second sub-reversing roller and a sheet that moves downward during re-feeding to contact the sheet and rotate in synchronization with the main reversing roller to pull the sheet toward the sheet re-feeding roller. A gathering roller is provided. The invention described in claim 2 is characterized in that, in the invention described in claim 1, the shifting roller is attached to a bracket mounted on the rotating shaft of the main reversing roller via a torque limiter. . According to a third aspect of the present invention, in the first aspect of the invention, when the shifting roller is shifting the sheet toward the re-feeding roller, the re-feeding roller is stopped to bend the sheet, The feature is that the skew is corrected.

[0007]

When the sheet is re-fed by the invention described in claim 1, the preceding sheet is reversed by the rotation of the main reversing roller in the reversing section and is re-fed to the re-feeding section in the same manner as in the conventional case. The sheet is conveyed, and during this time, the shifting roller is separated from the preceding sheet, and then the shifting roller comes into contact with the preceding sheet and rotates in synchronization with the main reversing roller, so that the preceding sheet becomes the second sub-reversing roller. The sheet is conveyed to the re-feeding roller, then the shifting roller is moved to a position separated from the preceding sheet, and the preceding sheet is re-oriented toward the image forming unit by the second sub-reversing roller and the re-feeding roller. After being fed, the succeeding sheet is conveyed to the reversing section via the conveying section and is conveyed to the re-feed section in the same manner as the preceding sheet, thus re-feeding the preceding sheet. , And the reverse of the following paper is performed at the same time. Continues the same thing for the paper below the desired number.

When re-feeding paper according to the second and third aspects of the present invention, the preceding sheet is reversed by the rotation of the main reversing roller in the reversing section in the same manner as in the first aspect of the invention. It is conveyed to the sheet re-feeding unit, where the bracket of the shifting roller is moved to the upper position and stopped by the torque limiter that rotates in the same direction as the main reversing roller, and the shifting roller is separated from the preceding sheet, 2 The secondary reversing roller and the re-feeding roller are in contact with the main reversing roller and rotate in synchronization. After that, the main reversing roller rotates in the opposite direction, the bracket of the shifting roller moves to the lower position by the torque limiter and stops, and the shifting roller comes into contact with the preceding sheet and re-feeds the second sub-reversing roller. The roller separates from the main reversing roller and stops. Then, the shifting roller rotates to transfer the preceding sheet toward the second sub-reversing roller and the sheet re-feeding roller. At this time, the leading edge of the preceding sheet is stopped by being blocked by the nip portion between the second secondary reversing roller and the re-feeding roller,
Therefore, the preceding sheet is bent upward to correct the skew. After that, the main reversing roller is again rotated in the forward direction, the shifting roller is moved to the upper moving position separated from the preceding paper and stopped in the same manner as described above, and the second sub reversing roller and the re-feeding roller are moved upward. Restarts with the main reversing roller. In this way, the preceding sheet is re-fed toward the image forming section by the second sub-reversing roller and the sheet re-feeding roller, and at the same time, the following sheet is fed to the conveying section and the reversing section in the same manner as described above. After that, it is conveyed to the re-feeding unit, and the re-feeding of the preceding paper and the reversing of the succeeding paper are performed at the same time, the time interval between them is shortened, and the same continues for the desired number of sheets. To be done.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment of the present invention shown in FIGS. 1 to 5, the same parts as those in the conventional example are designated by the same reference numerals, and the description thereof will be omitted. When the bearing 12 is pressed by the spring 13, the sheet re-feeding roller 14 comes into contact with the second sub-reversing roller 6 of the reversing unit 7, and the second sub-reversing roller 6 also comes into contact with the main reversing roller 4 in synchronization. It is designed to rotate. Further, there is provided a moving roller 15 which is moved between contact and separation positions with respect to the sheet by a supporting means including a drive source such as a motor and a link mechanism (not shown) and is held at those positions. A driven pinion 16 is attached to the rotary shaft of the drive pinion 17 as shown in FIG. 2, and a drive pinion 17 that meshes with the driven pinion 16 is provided. The shifting roller 15 is a rotary shaft of the drive pinion 17 and a rotary shaft of the main reversing roller 4. A first timing belt 18 stretched between the first and second belts rotates in synchronization with the main reversing roller 4. Reference numeral 19 represents an inversion sensor.

When re-feeding paper in the first embodiment,
The supporting roller 15 causes the preceding paper P to move by the supporting means.
As shown in FIG. 3, the preceding sheet P1 which is held at the upper position apart from 1 is reversed by rotation of the main reversing roller 4 in the clockwise direction in the reversing unit 7 as shown in FIG. And is conveyed to the re-feeding table 11 of the re-feeding unit 8.
In this way, after a lapse of a predetermined time after the reversing sensor 19 detects the trailing edge of the preceding sheet P1, the counter pin is synchronized with the main reversing roller 4 via the driven pinion 16, the drive pinion 17, and the first timing belt 18. Shifting roller 15 rotating clockwise
4 is moved downward to contact the preceding sheet P1 as shown in FIG. 4, and the preceding sheet P1 is transported by the shifting roller 15 toward the second sub-reversing roller 6 and the re-feeding roller 14. . Thereafter, the shift roller 15 is moved to an upper position separated from the preceding paper P1 as shown in FIG.
1 is re-fed toward the image forming unit by the second sub-reversing roller 6 and the re-feeding roller 14, and at the same time, the succeeding sheet P2 is conveyed to the reversing unit 7 via the conveying unit 2 and is reversed here. Then, the sheet P1 is conveyed to the sheet re-feeding unit 8 in the same manner as the preceding sheet P1. In this way, the sheet re-feeding of the preceding sheet P1 and the reversal of the succeeding sheet P2 are simultaneously performed, and in between. The time interval is shortened, and the same is continued for the desired number of sheets.

In the second embodiment of the present invention shown in FIGS. 6 to 11, the same parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. The different parts will be mainly described. The first torque limiter is attached to the rotary shaft 21 of the main reversing roller 4.
The bracket 23 is attached via 22 and this bracket 23
The rotating shaft 24 of the pressing roller 15 is rotatably supported. And the pulley 2 attached to both rotary shafts 21 and 24
The second timing belt 27 is stretched between 5 and 26,
A cam is attached to both ends of the rotary shaft 21 via a second torque limiter 28.
29 is mounted, and at a position facing the cam 29, the link 30 is attached to the bearing of the second secondary reversing roller 6.

When re-feeding paper in this second embodiment,
The preceding paper P1 is similar to the invention described in claim 1,
As shown in FIGS. 7 and 9, the main reversing roller 4 is rotated in the forward direction by the reversing unit 7, is reversed, and is conveyed to the re-feeding table 11 of the re-feeding unit 8. At this time, the bracket 23 and the cam 29 of the pulling roller 15 are rotated in the same direction as the main reversing roller 4 into the first and second rollers.
The torque limiters 22, 28 move to the upper movement position to engage a stopper (not shown), and stop when the engaging force becomes larger than the set torque of the first and second torque limiters 22, 28. Here, the shifting roller 15 is separated from the preceding paper P1 and the cam 29 is separated from the link 30, and the second sub-reversing roller 6 and the re-feeding roller 14 are moved upward by the pressing force of the spring 13 to the main reversing roller 4. It comes into contact and rotates with it.

In this way, the main reversing roller 4 rotates in the opposite direction as shown in FIGS. 8 and 10 after a lapse of a certain time after the reversing sensor 19 detects the trailing edge of the preceding sheet P1. The bracket 23 and the cam 29 of the roller 15 are respectively moved to the lower moving positions by the first and second torque limiters 22 and 28 which rotate in the same direction, and are engaged with the stopper (not shown). Stop when the torque exceeds the set torque of the limiter 22. Here, the approach roller 15 comes into contact with the preceding paper P1, and the cam 29 comes into contact with the link 30 and presses it down to separate the second sub-reversing roller 6 from the main reversing roller 4 and the re-feeding roller 14. Stop. Then, the shifting roller 15 rotates in synchronization with the main reversing roller 4 via the pulleys 25 and 26 and the second timing belt 27, and directs the preceding paper P1 toward the second sub reversing roller 6 and the re-feeding roller 14. To transfer. At this time, the second sub-reversing roller 6 and the re-feeding roller 14
Since the leading sheet P1 is stopped, the leading edge of the leading sheet P1 is blocked by the nip portions of the rollers 6 and 14 and stopped, so that the leading sheet P1 bends upward as shown in FIG. To be done.

Thereafter, as shown in FIGS. 7 and 11, the main reversing roller 4 is again rotated in the forward direction, and the bracket is rotated in the same manner as described above.
23 and the cam 29 are rotated in the same direction to move the stopping roller 15 and the cam 29 to the upper moving position separated from the preceding paper P1 and the link 30 and stop. Here roller 15
Is separated from the preceding paper P1 and the cam 29 is separated from the link 30, and the second sub-reversing roller 6 and the re-feeding roller 14 are brought into contact with the main reversing roller 4 to restart the rotation. Then, the preceding paper P1 is re-fed toward the image forming unit by the second sub-reversing roller 6 and the re-feeding roller 14, and at the same time, the succeeding paper P2 is conveyed to the reversing unit 7 via the conveying unit 2. Then, the re-feeding of the preceding paper P1 and the inversion of the succeeding paper P2 are simultaneously performed in this way, and the same is continued for the desired number of paper sheets.

[0015]

The present invention is as described above, and the invention according to claim 1 is such that a conveying unit having a pair of guide plates disposed opposite to each other, a main reversing roller for reversing a sheet, and a vertical direction. In the re-feeding device of the image forming apparatus, the reversing unit having the first and second sub-reversing rollers and the re-feeding unit for re-feeding the paper are sequentially arranged. A re-feeding roller that comes into contact with the re-feeding roller and a moving roller that moves downward when re-feeding to contact the sheet and rotates in synchronization with the main reversing roller to move the sheet toward the re-feeding roller are provided. Therefore, the time interval between the image formation of the preceding sheet and the image formation of the succeeding sheet can be shortened, continuous image formation can be efficiently performed, and the productivity is high. . According to a second aspect of the present invention, in the first aspect of the invention, since the shifting roller is attached to a bracket mounted on the rotation shaft of the main reversing roller via a torque limiter, the shifting roller supports the shifting roller. In addition to not requiring a large bracket, it does not require a driving means such as a solenoid for moving the shifting roller up and down, so a large space for installing these is not required, and it is not large and inexpensive. There is an effect that can be provided in. According to a third aspect of the present invention, in the first aspect of the invention, when the shifting roller is shifting the sheet toward the re-feeding roller, the re-feeding roller is stopped to bend the sheet, Since the skew is corrected, a side fence provided to correct the skew of the sheet conveyed to the refeed unit, a drive source such as a motor for driving the side fence, and a position sensor for the side fence, etc. In addition to the fact that it is not necessary to provide the above, there is an effect that it can be made compact without requiring an extra space for installing these and is inexpensive.

[Brief description of drawings]

FIG. 1 is a partially longitudinal front view of a first embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the above.

FIG. 3 is an explanatory diagram showing a state when the preceding sheet is reversed in the above.

FIG. 4 is an explanatory diagram showing a state at the start of re-feeding of the preceding sheet.

FIG. 5 is an explanatory diagram showing a state of re-feeding the preceding sheet.

FIG. 6 is a plan view of an essential part of a second embodiment of the present invention.

FIG. 7 is an explanatory diagram showing a state in which the above-mentioned shifting roller is in an upward movement position.

FIG. 8 is an explanatory diagram showing a state in which the aligning roller is in a downward movement position.

FIG. 9 is an explanatory diagram showing a state at the time of reversing the preceding sheet of the above.

FIG. 10 is an explanatory diagram showing a state at the start of refeeding the preceding sheet.

FIG. 11 is an explanatory diagram showing a state of re-feeding the preceding sheet.

FIG. 12 is a front view showing the outline of a re-feeding device in an image forming apparatus of the same type as the present invention.

[Explanation of symbols]

1 Re-feeding device 2 Conveying section 3 Guide plate 4 Main reversing roller 5 First sub-reversing roller 6 Second sub-reversing roller 7 Reversing section 8 Re-feeding section 9 Conveying roller 11 Re-feeding table 12 Bearing 13 Spring 14 Re-feeding Paper roller 15 Shifting roller 16 Driven pinion 17 Drive pinion 18 First timing belt 19 Inversion sensor 21 Rotation shaft 22 First torque limiter 23 Bracket 24 Rotation shaft 25 Pulley 26 Pulley 27 Second timing belt 28 Second torque limiter 29 Cam 30 Link

Claims (3)

(57) [Claims] 1. A conveying unit having a pair of guide plates disposed opposite to each other, a reversing unit having a main reversing roller for reversing the sheet, and upper and lower first and second sub-reversing rollers, and re-feeding the sheet. In a sheet re-feeding device in an image forming apparatus in which a sheet re-feeding unit is sequentially arranged, a sheet re-feeding roller that contacts the second sub-reversing roller in the reversing unit, and moves downward to re-feed the sheet. A sheet re-feeding device in an image forming apparatus, comprising: a contact roller that rotates in synchronization with a main reversing roller and that moves a sheet toward a sheet re-feeding roller. 2. The sheet re-feeding device in the image forming apparatus according to claim 1, wherein the shifting roller is attached to a bracket mounted on the rotation shaft of the main reversing roller via a torque limiter. 3. The skew of the sheet is corrected by stopping the sheet re-feeding roller to bend the sheet when the sheet shifting roller is moving the sheet toward the sheet re-feeding roller. A sheet re-feeding device in the image forming apparatus.