JPS6113228B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sheet document conveying device used in electrophotographic copying machines and the like. The present invention particularly relates to a sheet document conveying device suitable for double-sided copying.

2. Description of the Related Art Conventionally, the following types of document conveyance devices for conveying a sheet document to an exposure section at the top of a copying machine have been known. First, as shown in FIG. 1, there was a type in which sheet originals were fed from a sheet feeding table stacked with sheet originals toward an exposure section, and after exposure, they were ejected to a paper ejection tray. That is, sheet originals stacked on a paper feed tray 1 are fed one by one by a paper feed roller 2 and fed onto an original document tray 3 made of a transparent glass plate on the upper surface of the copying machine. A belt conveying device 4 that covers the entire surface of the document table 3 and rotates intermittently is provided on the document table 3 to stop the received sheet document at an appropriate position on the document table 3. Then, the sheet original is exposed and scanned by the slit exposure optical system 5. After exposure, the belt conveyance device 4 rotates and discharges the sheet document onto the paper discharge tray 6.

The apparatus shown in FIG. 2 is of a type in which a sheet original fed from a paper feed table is returned to the paper feed table after passing through an exposure section. The uppermost original sheet on the paper feed tray 1 is fed by the paper feed roller 2, is stopped on the document tray 3 by the belt conveyance device 4, and after exposure scanning by the slit exposure optical system 5 is transferred to the belt conveyance device 4 again. and is returned to the top of the same paper feed table 1 by the guide device 6.

Now, FIG. 3 shows a schematic diagram of a typical double-sided copying apparatus. The transfer paper fed from the paper feeder 7 is brought into close contact with the photoreceptor drum 8 at the transfer section, and after the first image is transferred onto the surface, it is fixed by the fixing device 9 and transferred to the intermediate paper feeder 10. Switching guide 1
Guided by 1. Next, the intermediate paper feed device 10
The back side of the transfer paper fed from the photosensitive drum 8 is brought into contact with the photosensitive drum 8, and the second image is transferred thereto. After the transfer, the paper passes through the fixing device 9 again and is discharged onto the paper discharge tray 12.

A sheet document conveying device has been attached to such a double-sided copying apparatus to make double-sided copies from a sheet document. However, with the conventional sheet document conveying apparatus shown in FIGS. 1 and 2, efficient double-sided copying cannot be performed.
For example, in an apparatus of the type shown in FIG.
Lead to 0. Next, a second sheet original is sent, and an image corresponding to the second original is formed on the back side of the transfer paper fed from the intermediate paper feeder 10, thereby completing double-sided copying. In other words, two consecutive sheet originals are
This is a method in which double-sided copies are completed one by one as a set. This method has the disadvantage of slow copying speed because double-sided copies are obtained one by one.
Another drawback is that the next copying operation cannot be performed unless the operator transfers the sheet original from the paper discharge tray 6 to the paper feed table 1 after the original copying is completed.

Next, in the device shown in Figure 2, the paper feed tray also serves as the paper output tray, which solves some of the above-mentioned drawbacks, but it is also inefficient because double-sided copying must be performed one sheet at a time. It has the following drawbacks.

Conventionally, there has been no efficient method for obtaining a double-sided copy from a so-called single-sided sheet original having an image on one side.

The present invention has been made in view of this point, and an object of the present invention is to provide a document conveying device for efficiently obtaining a double-sided copy from a single-sided sheet document.

Another object of the present invention is to provide a document conveyance device that conveys a predetermined sheet document out of a continuous sheet document without passing through an exposure section.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a sectional view of a double-sided copying machine showing an embodiment of the present invention. A document conveying device 14 is removably attached to the upper part of the copying machine 13. The document transport device 14 has a document table 15 at the top that accommodates a plurality of single-sided sheet documents O. This document table 15 has a surface inclined downward to the right, and the sheet document O
The originals are stacked with their sides facing upward in page order.
A paper feed roller 16 that rotates clockwise is provided below the document table 15, and forms a sheet document conveyance path 18 with the right support plate 17.
The paper feed roller 16 is composed of a rubber roller, and uses frictional force to feed the sheet documents O one by one starting from the lowest one. Note that the paper feed roller 16
It is also possible to use a suction roller having an air suction port on its surface, and to separate and feed the sheet documents O one by one by the air suction force. On the top surface of the copying machine 13, there is a document table 19 made of a transparent glass plate, and a conveyor belt 20 is stretched between a belt drive roller 21 and a roller 22 so as to cover the top of the document table 19. The conveyor belt 20 is rotated clockwise by a belt drive roller 21. The conveyor belt 20 is made up of a plurality of elongated endless belts stretched at appropriate intervals, and a stop pawl (not shown) is provided in the conveyor belt 20 and protrudes from between the belts to determine the stopping position of the sheet document. Original table 19
come into contact with. Since a conventionally known method can be used to stop the sheet original using such a stop claw, detailed explanation will be omitted. The sheet original transported by the conveyor belt 20 is returned to the original table 15 by a discharge roller 23. Sheet original path 1
A rotatable branch claw 24 is disposed between the roller 22 and the conveyor belt 20, and is operated to switch the moving direction of the sheet document. A waiting tray 25 is formed in a space above the conveyor belt 20 and below the document table 15.
A feed roller 26 that rotates intermittently is arranged on the waiting tray 25. The sheet original transported by the feed roller 26 is sent to the ejection roller 23, and similarly returned to the document table 15. A first detection device 27 that detects the sheet document conveyed by the paper feed roller 16 is connected to the right support plate 1.
A second detection device 28 is attached to the left support plate 29 for detecting the sheet document discharged by the discharge roller 23 . The first and second detection devices 27 and 28 may be of a photoelectric detection type, or may be microswitches. An air detection method can also be adopted as a method for reliably detecting the document without damaging the document or disturbing its conveyance.

Next, the configuration of the copying machine 13 will be explained. A slit exposure device 31 is arranged between the original table 19 and the photosensitive drum 30. The slit exposure device 31 includes an illumination lamp 32, a reflecting mirror 33, and a first movable reflecting mirror 34 that moves in the direction of the arrow at the same speed as the circumferential speed V of the photoreceptor drum 30. a second movable reflecting mirror 35 that moves at a speed of 1/2V in relation to; a fixed lens L;
It is composed of two fixed reflecting mirrors (not shown). The photosensitive drum 30 rotates counterclockwise, and the photosensitive layer is made of selenium, zinc oxide, cadmium sulfide, an organic photoconductor, or the like. Around the photosensitive drum 30, a charging device 36 consisting of a corona discharger, a magnetic brush developing device 37, a corona transfer device 38, a corona separating device 39, a separating claw 40, a cleaning device 41, and a static eliminator 42 are arranged in this order. There is. The paper feeding device 43 is composed of a paper feeding cassette 44 and a paper feeding roller 45, and the paper feeding roller 45 feeds the transfer paper stored in the paper feeding cassette 44 one sheet at a time. In this embodiment, there is only one paper feed cassette, but a plurality of paper feed cassettes may be arranged according to the size so that transfer paper of different sizes can be selectively fed. Paper feeding device 43
A registration roller 4 is provided between the transfer device 38 and the transfer device 38.
6 is placed. An intermediate paper feed device 47 is provided above the paper feed device 43, and the paper feed tray 4
Paper feed roller 49 rotates the transfer paper in 8 below.
The paper is fed one by one starting from the bottom. The fed transfer paper is fed toward the registration roller 46. A guide member 50, a heat fixing device 51, a switching guide plate 52 are provided in the path after the transfer paper is separated from the photosensitive drum 30, and a paper discharge tray 53 is provided at the final position. is,
The double-sided copying operation will be explained. A case where the number of single-sided sheet originals is an even number, for example, four sheets will be explained.
Starting from the first page of the single-sided sheet original O
Let O ₁ , O ₂ , O ₃ , O ₄ . Sheet originals are placed on the original table 15 in page order with the image side facing upward. When the print button is pressed, the paper feed roller 16 rotates and feeds the lowest sheet document _O4 . At this time, the belt drive roller 21 rotates, causing the conveyor belt 20 to rotate. Feed sheet original O ₄
The document mounting table 1 is moved by the branch claw 24 located at the solid line position.
9 and the conveyor belt 20, the first sheet is guided to the document conveyance path. The sheet original O ₄ is moved on the original placing table 19 by the conveyor belt 20,
When it reaches a predetermined position, it is stopped by a mechanism not shown. The conveyor belt 20 also stops rotating. Then, the illumination lamp 32 lights up, and together with the illumination lamp 32, the first movable reflecting mirror 34 and the second movable reflecting mirror 35
starts document scanning and projects the optical image of the sheet document O ₄ onto the photosensitive drum 30 . After the photosensitive drum 30 is uniformly charged by the charging device 36, the above exposure is performed, and an electrostatic latent image corresponding to the sheet original _O4 is formed on the surface thereof. This electrostatic latent image is visualized by a magnetic brush developing device 37. The transfer paper S ₁ fed from the paper feeding device 43 is temporarily stopped by the registration roller 46 and fed again in synchronization with the movement of the photosensitive drum 30 . transfer paper
S ₁ is sent to the transfer device 38 with the leading edge of the image on the photosensitive drum 30 aligned with the leading edge thereof. The toner image on the photosensitive drum 30 is electrostatically transferred onto the transfer paper _S1 by the transfer device 38. After transcription,
The electric charge imparted by the transfer device 38 is removed by reverse polarity corona discharge or AC corona discharge of the corona static eliminator 39, reducing the electrostatic attraction force between the transfer paper _S1 and the photoreceptor drum 30, and removing the charge applied by the transfer paper S1. ₁ to photoreceptor drum 3
The separation claw 40 that separates the corona separation device 39 from the corona separation device 39 serves as an auxiliary action only when the separation action of the corona separation device 39 is incomplete due to changes in environmental conditions or the quality of the transfer paper, and normally does not work much. The separated transfer paper S ₁ is fixed by a heat fixing device 51 and guided to an intermediate paper feeding device 47 by a switching guide plate 52 located at the position of an imaginary line. The transfer paper S ₁ is placed on the paper feed tray 48 with the image side facing upward. That is, the sheet original O ₄ is placed on the first side of the transfer paper S ₁ .
An image corresponding to is formed. Now, the sheet original O ₄ is stopped on the original platen 19, and the paper feed roller 16 starts rotating again in response to a signal to start exposure from the slit exposure device 31.
Feed _O3 . At this time, the branch claw 24 is displaced to the position of the imaginary line. Therefore, the sheet document O ₃ is guided to the second sheet document path on the conveyor belt 20 and is bitten by the rotating feed roller 26 .
When the leading edge of the sheet document O ₃ is bitten by the feed roller 26, the rotation of the feed roller 26 is stopped.
The sheet original O ₃ is temporarily stopped on the waiting tray 25 . When the forward movement of the slit exposure device 31 is completed, the conveyor belt 20 rotates again in response to the signal, conveys the sheet document O ₄ , and transfers the image surface onto the top of the sheet document O onto the document table 15 by the paper ejection roller 23 . is placed facing up. When the second detection device 28 detects the rear end of the sheet original O ₄ , the feed roller 26 starts rotating and discharges the sheet original O ₃ onto the original platen 15 following the sheet original O ₄ . Note that the first detection device 27 is used to switch the branch claws 24 and to control the rotation stop of the conveyor belt 20. Now, the sheet original O ₂ is fed by rotating the paper feed roller 16 in response to an exposure end signal from the slit exposure device 31 . The sheet original O ₂ is conveyed toward the original mounting table 19 for exposure. When the odd-numbered sheet document is fed, the second transfer paper _S2 is fed from the paper feeding device 43. Sheet original O ₂ is fed, followed by sheet original O ₁
The paper is also fed in exactly the same manner as in the case described above, and is conveyed to the waiting tray 25. The sheet original O ₂ is exposed as described above, a corresponding image is formed on the first side of the transfer paper S ₂ , and the sheet original O 2 is stored in the intermediate paper feeder 47 with the image side facing upward in the same manner as the transfer paper S ₁ . Ru. When the exposure of the sheet original O ₂ is completed, the sheet original O 2 is returned to the original table 15 by the discharge roller 23, and the sheet original O ₁ is also returned to the original table 15 in the same manner as the sheet original O ₃ . In this way, the first cycle ends, but the four sheet originals O ₁ to O ₄ are stored in page order on the original table 15 with the image side facing upward, exactly as in the initial state. . On the other hand, the paper feed tray 48 of the intermediate paper feed device has a first paper tray with the image surface facing upward.
A second transfer paper S ₂ is placed on top of the transfer paper S ₁ .
The second cycle then continues. First, the sheet document O ₄ is fed by the paper feed roller 16, and in this cycle, the odd-numbered documents are controlled to be guided to the waiting tray 25, that is, the second sheet document path. Therefore, the sheet original _O4 is sent to the waiting tray 25 by the branch claw 24, and its leading end is bitten by the feed roller 26 and comes to rest. When the sheet original O ₄ is fed, the sheet original O ₃ is fed next, the branch claw 24 is switched to the solid line position, and the sheet original O ₃ is placed on the original table 19.
and the conveyor belt 20. When the exposure of the sheet original O ₃ starts, the rotation of the feed roller 26 is restarted, and the sheet original O ₄ is returned to the original platen 15 . In conjunction with the exposure work of the sheet original O ₃ , the transfer paper S ₁ is transferred from the intermediate paper feed device 47 to the paper feed roller 49.
sent out by. The transfer paper S ₁ is re-fed by the registration roller 46 in synchronization with the photosensitive drum 30 . The back side, that is, the second side of the transfer paper _S1 is brought into close contact with the photosensitive drum 30, and the sheet original is placed on this side.
The image is transferred corresponding to O ₃ . 1st transfer paper S ₁
is fixed by the heat fixing device 51, and is discharged onto the paper discharge tray 53 since the switching guide plate 52 has been displaced to the solid line position. Transfer paper S ₁ is a sheet original
It is ejected with the image side corresponding to O ₃ facing upward. Note that during the second cycle, the switching guide plate 52 is fixed at the solid line position as described above. Then, when the exposure of the sheet original O ₃ is completed, the conveyor belt 20 rotates, and the sheet original O ₃ is transferred to the original platen 1.
5, but the paper feed roller 1 is switched back to the exposure end signal.
6 rotates, and sheet original O ₂ is fed. The sheet original O ₂ is guided to the waiting tray 25 in the same way as the sheet original O ₄ , and the following sheet original O ₁ is guided to be placed on the original placing table 19 for exposure. The sheet originals O ₂ and O ₁ are returned to the original table 15 by repeating the same operation as for the sheet originals O ₄ and O ₃ .
On the other hand, the second transfer paper S ₂ is fed from the intermediate paper feeder 47, an image corresponding to the sheet original O ₁ is formed on the back side, and an image of the back side, that is, the image of the sheet original O ₁ is formed on the paper ejection tray 53. It is ejected with the side facing upward.

In this way, the second cycle ends.
As is clear from the above explanation, at the end of the cycle, sheet originals are placed on the original table 15 in page order from the top, and two sheets of transfer paper are placed on the front and back sides of the paper output tray 53, respectively. Double-sided copying is performed for sheet originals, and the pages are arranged in order from the top.

Now, the overall control method will be explained. First, the number of sheet originals set is inputted into a storage circuit (not shown) of a control device of the copying machine. Each time a sheet original O is fed by the paper feed roller 16, the first detection device 27 detects the number of fed sheet originals O, and when the set number of sheets is reached, the first cycle ends. Notify the control device. Of course, it is also possible to use the second detection device 28. Upon completion of the first cycle, the switching operation cycle of the branch claw 24 is changed, and the paper feeding operation of the paper feeding device 43 is changed to the paper feeding operation of the intermediate paper feeding device 47. This is changed to a so-called reverse side copying operation. At the same time, the position of the switching guide plate 52 is also changed at this time.

Now, in the above case, we have explained the case where one copy is obtained from one original, but if the repeat counter is set to obtain N copies from one original, then the above-mentioned first and second By repeating the set cycle including 2 cycles N times, N sets of double-sided copies are obtained on the paper discharge tray 53. At this time, sheet original O is
The paper will be fed 2N times.

Next, a case where the number of sheet documents is an odd number will be explained. There are five sheet manuscripts, and the pages are numbered O ₁ , O ₂ , O ₃ , O ₄ , and O ₅ from the top. In the first cycle, odd-numbered sheet originals are sent to the waiting tray 25, and even-numbered sheet originals O ₄ and O ₂ are exposed.
Therefore, two sheets of transfer paper are placed on the paper feed tray 48 of the intermediate paper feed device 47, with images corresponding to sheet originals O ₂ and O ₄ formed thereon from the top. Then the second
When entering the cycle, the odd-numbered sheet original O ₅ ,
O ₃ and O ₁ are exposed. 1st sheet original O ₅
The third transfer paper on which the image is copied is fed from the paper feeding device 43 in this second cycle. During the second cycle, the switching guide plate 52 is placed at the solid line position, so the third transfer paper S ₃ is transferred to the intermediate paper feeder 4.
7 and is directly ejected to the paper ejection tray 53 with the image side facing upward. Then the sheet manuscript
During exposure of O ₃ and O ₁ , the first
The transfer paper S ₁ and the second transfer paper S ₂ are fed in this order, and an image O ₃ is formed on the back surface of the first transfer paper S ₁ and an image O ₁ is formed on the back surface of the second transfer paper S ₂ . The second, first, and third transfer sheets are stacked on the paper discharge tray 53 in this order from the top, but the copies are arranged in page order. That is, the image O ₁ is on the upper surface of the second transfer paper S ₂ and the image O ₂ is on the lower surface.
However, an image O ₃ is formed on the top surface of the first transfer paper S ₁ , an image O ₄ is formed on the bottom surface, and an image O ₅ is formed on the top surface of the third transfer paper S ₃ . Of course, the number of originals is not limited to five, and the same applies to any odd number of originals.

By the way, when copying from an even number of sheet originals, the order in which the sheet originals are fed and the order in which they are ejected to the document table are set to be exactly the same, but the copying speed can be further increased by doing the following. can. As shown in FIG. 5a, sheet originals _O1 to _O4 are placed on the original table 15 in page order from the top with the image side facing upward. Then, the sheet document is fed by the paper feed roller 16.
O ₄ is fed and sent to the original platen 19. The sheet original O ₃ is returned to the original table 15 through the second sheet original transport path without stopping on the way. After the exposure, the sheet original O ₄ is returned to the original table 15. Thereafter, sheet originals O ₂ and O ₁ are sent in the same manner. 1st
After the cycle is completed, sheet originals are stacked on the original table 15 in the order of O ₂ , O ₁ , O ₄ , and O ₃ from the top, as shown in FIG. 5b. The intermediate paper feeding device 47 accommodates transfer papers S ₂ and S ₁ . After the first cycle is completed, the second cycle begins, and the sheet originals on the original platen 15 are fed in the order of O ₃ , O ₄ , O ₁ , and O ₂ .
The sheet original O ₃ is exposed, but the sheet original O ₄ passes through the waiting tray 25 and is returned to the original table 15 earlier than the sheet original O ₃ , and then the sheet original O 4 is exposed to light.
O ₃ is returned to the document table 15. Sheet original O ₁ , O ₂
are also transported in the same way. Therefore, after the end of the second cycle, that is, the end of the set cycle, the sheet originals are arranged on the original table 15 in the same page order as in the initial state, as shown in FIG. 5c. The transfer sheets are also discharged onto the paper discharge tray 53 in the order of the pages.

Next, when performing single-sided copying using this apparatus, the double-sided copying mode is switched to the single-sided copying mode. In this case, the branch claw 24 and the switching guide plate 5
2 are each fixed at the solid line position. The sheet originals O are fed one by one by the paper feed roller 16, and the transfer paper S is also fed one by one from the paper feeding device 43, and one-sided copying is performed by a normal copying operation.

When copying thick books, copy machine 13
If the upper document conveying device 14 is removed and the book is placed on the document table 16, a copy can be obtained by a normal copying method.

As described above, according to the present invention, in the automatic sheet document feeding device, the sheet document can be sent to the second sheet document conveyance path that does not pass through the exposure section, so that selective copying is possible. When double-sided copying is performed, it is possible to reliably perform double-sided copying of a continuous single-sided sheet original in page order, and it is also possible to perform efficient copying. Further, since both the sheet original and the copy after copying are arranged in page order, processing after copying can be done in a short time.

[Brief explanation of the drawing]

1 and 2 are diagrams showing a conventional sheet document conveying device, FIG. 3 is a schematic configuration diagram of a conventional copying device that performs double-sided copying, and FIG. 4 is a diagram of a double-sided copying device showing an embodiment of the present invention. The sectional views and FIGS. 5a to 5c are diagrams for explaining the movement of a sheet original and a transfer paper in a modified embodiment of the present invention. 14...Sheet document conveyance device, 15...Document stand, 1
6...Paper feed roller, 19...Document placement table, 20...Transport belt, 24...Branch claw, 25...Waiting tray, 2
6...Feed roller, 30...Photosensitive drum, 43...
Paper feeding device, 47... Intermediate paper feeding device, 52... Switching guide plate.

Claims (1)

[Claims] 1 A document table that stacks a plurality of sheet documents, a paper feeder that feeds sheet documents one by one from the document table, and a sheet document feed device that sends the fed sheet documents to the exposure unit of the copying machine for exposure. and a first conveying device that returns the sheet original to the document table, the sheet document fed from the document table is sent to a second sheet document conveying path without passing through the exposure section.
a switching device that guides the sheet document every other sheet; and a second device that returns the sheet document in the second sheet document conveyance path to the document table.
transporting the same sheet document from the document table.
1. A document conveying device, wherein one cycle is defined as feeding a sheet twice, and a control device conveys a sheet document that was not conveyed to an exposure section during the first feeding to an exposure section in a second time.