JPS6315577B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic copying apparatus that forms images on both the front and back sides of transfer paper.

Conventionally, in a double-sided copying method, as shown in FIG. 1, a sheet original or a block original such as a book is placed on an original placing table 1, and an optical image of the original is placed on a photoreceptor drum 3 by scanning with an exposure optical system 2. is projected to form an electrostatic latent image, which is then visualized by the developing device 4, transferred to the first side of transfer paper fed from the paper feeding device 5, and then transferred to the fixing device. After the transfer paper is fixed on the transfer paper in step 6, the transfer paper is loaded on the intermediate paper feeder 7 with its first side facing upward. Next, a new original is placed on the original document mounting table 1 and scanned again by the exposure optical system 2 to similarly form an image on the photosensitive drum 3, and the transfer paper is transferred from the intermediate paper feeder 7 to its second side. The paper is fed so as to come into contact with the photoreceptor drum 3, the toner image is transferred thereon, and then the paper is discharged via the fixing device 6 to the paper discharge tray 8 with the second side facing upward. By the above-described operations, double-sided copying is performed in which images are formed on both the front and back sides of the transfer paper. That is, two copying processes were required to copy both sides.

Further, even in an automatic copying apparatus having a conveyance device exclusively for sheet documents, two copying processes are required to form different images on both the front and back sides of the transfer paper, as in the case described above.

Here, one copying process means that an electrostatic latent image is formed on a photoreceptor drum by one exposure, and this is visualized and transferred onto one sheet of transfer paper. Refers to the copying process from fixing the toner image to ejecting it.

Incidentally, recently there has been a growing demand for completing copying in a short time, and for this reason high-speed copying apparatuses have been actively developed. However, in the field of double-sided copying, the current situation is that nothing fully satisfactory has been developed.

In view of these points, it is an object of the present invention to provide a novel high-speed copying apparatus.

Another object of the present invention is to provide a high-speed copying apparatus that can form images on both the front and back sides of transfer paper with as few copying processes as possible.

Still another object of the present invention is to provide a novel copying apparatus that forms images on both the front and back sides of transfer paper in exactly the same front-back relationship as the original.

Still another object of the present invention is to provide a copying apparatus that can provide a binding margin on two consecutively conveyed transfer sheets when continuously copying a document such as a book in book mode.

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

First, the case of double-sided copying of a book original such as a book will be explained.

FIG. 2 is a schematic diagram of a double-sided copying apparatus applied to the double-sided copying method of the present invention. In FIG. 2, reference numeral 9 indicates an original table, and reference numeral 10 indicates an exposure optical system. The exposure optical system 10 includes a first reflecting mirror 11 and a second reflecting mirror 1 that move in the same direction and parallel to the document table 9 at a speed ratio of 1:1/2 in the direction of the arrow shown in the figure.
2, a fixed in-mirror lens 13, and a third reflecting mirror 14. A book is placed on the manuscript table 9 in an open state. For convenience, the even-numbered pages of the book are set to be on the right half A of the document table 9, and the odd-numbered pages are set to be on the left half B. FIG. 3 shows a plan view of the document mounting table 9 shown in FIG. 2. As shown in FIG.
As for the book, as shown in FIG. 4, the even-numbered page 10 of the book is placed on the A side, and the odd-numbered page 11 is placed on the B side. Next, a case will be explained in which double-sided copying of pages 10 to 15 of a book is performed. If the book is A4 size, use the entire surface of the document table 9 as shown in Figure 3, and if the book is B5 size, use the exposure starting edge 9a.
and the first edge 9b of the document table 9 as a reference. In addition to the above-mentioned method, the book can also be placed with reference to the center line 9c of the document table 9. In the embodiment of the present invention, books are placed according to the former criterion.

Now, input a program to make double-sided copies of an A4 size book into the control device of the copying machine. This input signal causes the reproduction machine to switch each copy element from a single copy mode to a duplex copy mode. After a predetermined period of time has elapsed, a message indicating that copying may be started is displayed. The copying operation starts when the operator places the book at a predetermined position on the document table 9 and closes the print switch. An exposure lamp (not shown) is turned on and the first reflecting mirror 11 and the second reflecting mirror
The reflecting mirror 12 moves in the direction of the arrow and scans the original images of the 10th and 11th pages placed on sides A and B of the document table 9 by the charging device 15. An electrostatic latent image is formed by projecting onto the uniformly charged photoreceptor drum 16. This electrostatic latent image is visualized by a developing device 17 that performs magnetic brush development, for example. After completing the exposure scan, the first and second reflecting mirrors 11 and 12 return to their original positions. On the other hand, the first sheet feeding device 18 stores A4 size transfer paper, and the rotation of the paper feeding roller 19 and the registration roller 20 is controlled by the control device, so that the first sheet feeding device Sheets of transfer paper are successively fed at predetermined intervals from each other. That is, as shown in FIG. 5, the transfer sheets P1 and P2 are conveyed in the direction of the arrow, and the transfer sheet P2 is fed and conveyed while maintaining the distance t from the transfer sheet P1. This interval t is A
It is possible to adjust the distance between the documents placed on the side and B side. This interval t will be explained in detail later. The fed transfer papers P1 and P2 are conveyed to a transfer position and come into close contact with the photosensitive drum 16, and the visualized toner image is electrostatically transferred by a transfer device 21 consisting of a transfer charger. Ru. That is, an image corresponding to the 10th page of the original is formed on the first side of the preceding transfer paper P1, and an image corresponding to the 11th page of the original is formed on the first side of the following transfer paper P2. After the transfer paper has been transferred, the toner image is fixed on it by the heating fixing roller device 22, and the charge is removed by the static eliminator 23. After that, the preceding transfer paper P1 is moved by the switching guide 24, which is initially located at the dotted line position. The paper ejection roller 2 is transported toward the paper ejection tray 25 and rotates at a higher speed than other transport rollers.
6 and is ejected. Since the paper discharge roller 26 is rotating at high speed, the distance t between the transfer paper P1 and the following transfer paper P2 is further expanded, and the transfer paper P
2 to the second sheet feeding device 27 by the switching guide 24. That is, transfer paper P1
After the switch SW1 detects that the leading edge of the transfer paper P2 has passed through the switching guide 24, if the transfer paper P2 is immediately moved to the solid line position, the direction can be easily changed even if the subsequent transfer paper P2 is conveyed at a relatively narrow interval. . The transfer paper P2 is stacked on the second sheet supply device 27 with the first side facing upward. At this time, the paper feed roller 28 needs to be retracted to a position where it does not interfere with proper stacking of the transfer paper P2. Alternatively, the second sheet feeding device 27 can be retracted.

Next, turn over the 11th page of the book, place the 12th page on side A and the 13th page on side B, perform exposure scanning again, and image the 12th and 13th pages on the photoreceptor drum 16. form an electrostatic latent image corresponding to On the other hand, transfer paper P2
is from the second sheet supply device 27 to the paper feed roller 28
The paper is fed by the registration rollers 20 and conveyed to the transfer position in synchronization with the movement of the photosensitive drum 16. At the same time as the transfer paper P2 passes through the switch SW2, a new transfer paper P3 is fed from the first sheet feeding device 18, and the preceding transfer paper P2
and are continuously conveyed while maintaining the interval t. The transfer paper P2 that has passed through the transfer device 21 has an image corresponding to page 12 of the book on its second side (back side).
3, an image corresponding to the 13th page of the book is formed on the first side (front side), and after passing through the fixing device 22, the preceding transfer paper P2 is stacked on the paper output tray 25 with the first side facing downward. . The subsequent transfer paper P3 is stacked on the second sheet supply device 27 with the first side facing upward. Thereafter, the same copying process is repeated, and after the image of the 15th page of the book is formed on the first side of the transfer paper P4, which is the last copy, this is transferred to the second sheet feeding device 27.
The paper is directly ejected to the paper ejection tray 25 without being transported to the paper ejection tray 25. After the above-described copying is completed, the transfer sheets P1 to P4 are stacked on the paper discharge tray 25, having been copied in exactly the same front-to-back relationship as the book and in page order.
That is, the 11th and 12th pages are on the front and back sides of the transfer paper P2.
The 13th page and the 14th page are copied on the front and back sides of the transfer paper P3, respectively.

In addition, when copying starts from an odd numbered page of a book in FIG. 4, the first odd numbered page is placed on side A and copied onto one sheet of transfer paper, or it is placed on side B. The process may be performed at a paper feeding timing that conveys only the succeeding transfer paper in the absence of the preceding transfer paper.

Next, the case of double-sided copying of a double-sided sheet original will be described. FIG. 6 shows a partial sectional view of a double-sided copying apparatus having a sheet document transport device. The sheet document feeding device 29 is a sheet document feeding device 30.
, an intermediate sheet feeding device 31, and a sheet discharge tray 32, and is attached above an exposure window 33 formed on the top surface of the copying apparatus. Now, two double-sided sheet originals S1 and S2 arranged in page order are stacked on the sheet original feeding device 30 with the first page facing downward, and a method for duplex copying of these sheet originals will be described. Since the photoreceptor drum, the processing devices surrounding it, and the transfer paper conveying device shown in FIG. 2 can be used as they are, they will be described using the reference numerals of the devices shown in FIG.

Double-sided sheet originals are fed from a sheet original feeding device 30 in order from the top by a feeding roller 30a. That is, two sheet originals are fed to the exposure window 33 in the order of S2 and S1, and an electrostatic latent image is formed on the photoreceptor drum 16, which is exposed in the order of the third page and the first page.
The first sheet feeding device 18 feeds and conveys two sheets of transfer paper P2 and P1 successively at the same interval as the sheet originals S1 and S2, and the first side of the preceding transfer paper P2. (Front side) is a sheet original S
The image of the third page is formed on the second sheet feeding device 27, and the image of the first page of the sheet document S1 is formed on the first side of the subsequent transfer paper P1.
They are loaded in the order of 1 with the first side facing upward. On the other hand, the sheet originals S1 and S2 after the exposure are also placed on the intermediate paper feeder 31 by the switching guide 34.
The pages are stacked in this order with the odd numbered pages facing up. When the switch SW3 detects that two sheet originals have been conveyed to the intermediate paper feeder 31, the paper feed roller 35 starts feeding the sheets after a certain period of time, and the sheet originals are exposed from the top in the order of S1 and S2. The paper is fed toward the window 33. Electrostatic latent images are formed on the photosensitive drum 16 in the order of the second page and the fourth page. On the other hand, the transfer paper is also fed from the second sheet supply device 27 in the order of P1 and P2, and the image of the second page of the sheet original S1 is on the second side of the preceding transfer paper P1, and the image of the second page of the sheet document S1 is on the second side of the preceding transfer paper P1. Images of the fourth page of the face-sheet original S2 are respectively formed and stacked on the paper discharge tray 25 in the order of S1 and S2 with odd numbered pages facing downward, that is, aligned in page order.
Sheet originals are also stacked on the paper discharge tray 32 in the order of S1 and S2 with the odd numbered pages facing down. Naturally, at this time, the switching guide 34 has been switched to the dotted line position. Although the case of two-sheet originals has been described above, double-sided copying can be performed in exactly the same way even with three or more original sheets.

In addition, when obtaining multiple copies from one original, the originals arranged in page order on the paper output tray 32 are placed directly on the sheet original feeding device 30, and this process is repeated for the desired number of copies. Bye. Alternatively, the intermediate paper feeder 31-- for the desired number of copies.
Exposure window 33 - switching guide 34 - intermediate paper feeding device 31
By circulating between them, it is possible to automatically make double-sided copies without using any manual effort. It should be noted that if sheet originals are stacked on the sheet original feeding device 30 with the odd-numbered pages facing upward, the order of the pages on the paper ejection tray 32 will be out of order.

By the way, the interval between two sheets of transfer paper that are successively conveyed is, for example, as shown in FIG.
When a book is placed on top of the book, the binding part in the center is often raised and no image is formed on the transfer paper in that part. Generally, when copying transfer paper is arranged in page order and bound, if there is no binding margin, even the image portion will be bound, which is inconvenient. Therefore, as shown in FIG. 7a, even if the distance t between the transfer sheets P1 and P2 in FIG. 5 is set to zero, the binding margin may not be sufficient. As shown in FIG. 7b, the preceding transfer paper P1 and the following transfer paper P2 are conveyed while being overlapped by a length of l, so that the part where no image is formed in the central part l is used as the binding margin. Then, sufficient binding margins will be formed on both the transfer sheets P1 and P2. Moreover, according to the copying method of the present invention, the binding margin is formed at the same position on both the front and back sides of the transfer paper, so even if the sheets are bound, the images will not be damaged.

FIG. 8 shows a paper feeding device that feeds the two sheets of transfer paper described above in a superimposed manner.

In FIG. 8, reference numeral 37 indicates a cassette, and reference numeral 38 indicates a cassette.
39 is the paper feed roller, 39 is the conveyance roller,
Reference numeral 40 indicates paper detection means. The conveyance roller 39 is constantly rotating at a speed V, and the paper feed roller 38 has an overrunning clutch (not shown) between it and the rotating shaft 38a.
Transfer paper P1 fed by paper feed roller 38
is held between transport rollers 39 and transported at a speed V. The drive of the paper feed roller 38 is cut off after the transfer paper P1 reaches the conveyance roller 39, but it continues to rotate due to the overrunning clutch.
When the paper detection means 40 detects the leading edge of the transfer paper P1, the paper feed roller 38 is driven to rotate again. Therefore, by appropriately adjusting the distance of the paper detection means 40 from the paper feed roller 38, the overlapping length of the transfer papers can be changed. For example, this can be easily done by interlocking the adjustment means provided outside the machine with the paper detection means depending on the size of the type of book. In addition, as a modification, if the paper feed roller is constantly rotated during one copying process without providing a paper detection means, the transfer paper can be overlapped and fed by the distance from the tip of the cassette to the paper feed roller. is also possible. At this time, the overlapping length can be adjusted by moving the paper feed roller and the cassette relative to each other.

As explained above, according to the copying apparatus of the present invention, when copying from a book original to two sheets of transfer paper that are successively conveyed, a binding margin is formed in advance on the transfer paper obtained after copying. This prevents the image portion from being bound when arranging the copy sheets in page order. Also,
Since different images can be formed on two sheets of transfer paper in one copying process, it is possible to perform high-speed double-sided copying, and one copying process can be omitted, saving power and reducing machine costs. Excellent in improving lifespan, etc. Furthermore, the images are formed on the transfer paper after copying in the same page order as the original, which is extremely convenient. In particular, even for book manuscripts such as books, double-sided copying with the same front-back relationship can be performed at high speed. On the other hand, in the case of double-sided sheet originals, high-speed double-sided copying is possible using a sheet original transport device, and as with transfer paper, the page order of sheet originals does not change at all before and after copying, and subsequent processing is also possible. It's convenient.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a conventional copying apparatus, FIG. 2 is a schematic configuration diagram of a copying apparatus to which an embodiment of the present invention is applied, and FIGS. 3 and 4 are diagrams for explaining processing of a document. FIG. 5 is a diagram for explaining the transfer paper conveyance method in the copying apparatus shown in FIG.
FIG. 6 is a partial sectional view of a copying apparatus having a sheet document conveying device showing an embodiment of the present invention, FIGS. 7a and 7b are diagrams for explaining a transfer paper conveying method in copying a book, FIG. 8 is a sectional view of a sheet feeding device showing an embodiment of the present invention. 9, 36...Document placement table, 10...Exposure optical system, 1
6... Photosensitive drum, 18... First sheet feeding device,
25, 32... Paper discharge tray, 27... Second sheet feeding device, 29... Sheet original feeding device, 30... Sheet original feeding device, 31... Intermediate feeding device, 33... Exposure window, P1, P2... Transfer paper, S... Sheet manuscript.

Claims (1)

[Scope of Claims] 1. A document placement table for placing a book-shaped document having two document surfaces, and an optical scanning device for exposing and scanning the document surface of the document placement table in one scan. means; a rotatable photoreceptor drum on which an electrostatic latent image corresponding to the document is formed on a photosensitive layer on the surface thereof by the optical scanning means; an image forming means comprising disposed charging, developing, transferring, and cleaning devices and a fixing device that fixes the transferred image; and a transfer paper that feeds the transfer paper toward the transfer position of the photoreceptor drum. a supplying means; a paper ejection tray for accommodating the transfer paper fed from the transfer paper supplying means and having the image on the photoreceptor drum transferred thereto; and corresponding to one document scanning by the optical scanning means; In a copying apparatus having a feeding control means for feeding two sheets of transfer paper toward a transfer position on a photoreceptor drum, feeding of a succeeding copy of the transfer paper continuously fed from the transfer paper supply means. A copying apparatus comprising a binding margin setting means that advances the start time, conveys and transfers parts of preceding and succeeding transfer sheets in an overlapping state, and sets the part as a binding margin.