JPH0792614B2 - Double-sided image forming device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided image forming apparatus that forms images on both sides of recording paper. More specifically, when performing image formation on the second side after completing image formation on the first side, double-sided image formation with an improved reversal refeed path for reversing the recording paper and refeeding it to the image forming unit Regarding the device.

2. Description of the Related Art In the above-mentioned double-sided image forming apparatus, an image forming unit with a rear end as a leading end is arranged below an image forming unit where an image forming process is performed on a recording paper so as to reverse the recording paper on which the image formation on the first surface is completed. It has been conventionally known to provide a reverse re-feeding passage for re-feeding paper, but since the reverse re-feeding passage is large in the vertical and front-back directions, it is difficult to downsize the double-sided image forming apparatus. However, there are various problems such that the reversing and refeeding path is long and jamming is likely to occur, and that the reversing and refeeding path needs to be provided with sufficient static electricity removal measures.

For example, a double-sided copying machine schematically shown in FIG. 2 will be described. In FIG. 2, reference numeral 1 is a photosensitive drum, which is charged, exposed, developed, transferred, separated, and controlled by a copy process control.
It is well known in the art that each processing such as cleaning is sequentially performed. Reference numeral 2 is a transfer / separation device, 3 is a paper feed cassette for storing recording paper, 4 is a paper feed roller, and 5 is a paper feed passage. Reference numeral 6 denotes a timing roller, which is controlled in copy process so as to feed the recording paper to the transfer / separation device 2 in synchronization with the photoconductor drum 1. Reference numeral 7 is a conveyor belt, 8 is a fixing roller, 9 is a paper discharge path, 10 is a paper discharge roller, and 11 is a paper discharge tray. Reference numeral 12 denotes a paper discharge-introduction guide plate, which is arranged at a position indicated by a dotted line when performing a normal single-sided copy and when copying the second side of a double-sided copy, and a position indicated by a solid line when copying the first side of a double-sided copy. It is controlled so as to be placed in. 13 is an introduction passage, 14 'is an introduction roller, 1
5'is for accommodating recording paper with the first side, which has been copied by the stacker, facing upward. 16 'is a re-feed roller,
It is controlled so as to be swung to the position shown by the dotted line at the time of re-feeding and to be driven to rotate counterclockwise. 18
Is a sheet re-feeding path, which is joined to the sheet feeding path 5 upstream of the timing roller 6. Each of the passages is composed of a guide drive roller and a guide plate, and is appropriately provided with static electricity removal measures. When performing a normal single-sided copy, the recording paper in the paper feed cassette 3 includes a paper feed roller 4, a paper feed passage 5, a timing roller 6, a transfer / separation device 2, a conveyance belt 7, a fixing roller 8, and a paper ejection-introduction. The toner image on the photoconductor drum 1 is transferred and fixed during copying while being accommodated in the discharge tray 11 through the guide plate 12 and the discharge passage 9 (hereinafter, the recording paper is The feed path is called the copy forming path). When performing double-sided copying, the recording paper in the paper feed cassette 3 is fed to the fixing roller 8 through the copy forming passage and copied on the first side. After passing through the fixing roller 8, the sheet is introduced into the introduction passage 13 by the sheet discharge-introduction guide plate 12 shown by the solid line, the leading end is directed to the downstream direction of the copy forming passage, and the first surface after copying is directed upward. It is stored in the stacker 15 '. A certain amount of recording paper is stacker 15 '
Copying of the second side is started after it is stored in, but is rotated counterclockwise and is moved to the position indicated by the dotted line by the re-feeding roller 16 ', with the trailing edge of the recording paper as the leading end. The sheet is fed to the timing roller 6 via the sheet re-feeding path 18. At that time, the recording paper is fed with the rear end facing the downstream direction of the copy forming passage and the second surface facing upward (hereinafter, the recording paper on which the copying of the first surface is completed is the timing roller 6). The path through which the paper is fed is called the re-feeding path).
After that, as with the first surface, the second surface is subjected to the transfer and fixing processes, and after exiting the fixing roller 8, the paper discharge-introduction guide plate 12 and the paper discharge passage arranged at the position indicated by the dotted line. 9. After passing through the sheet discharge roller 10, the sheet is stored in the sheet discharge tray 11, and the double-sided copy is completed.

The double-sided copying machine shown in FIG. 2 can smoothly perform normal single-sided copying and double-sided copying as described above. However, since the introduction path 13 is inverted twice before being connected to the stacker, the recording paper immediately after fixing is inverted twice before being stored in the stacker. Furthermore, if the recording paper just after normal fixing is bent too sharply, curling occurs,
Since it causes jamming, the introduction passage 13 is formed gently, so that the length of the introduction passage 13 also becomes long. Usually, the recording paper immediately after fixing is likely to be curled, and the recording paper frequently jams in the conveying path. Therefore, when the recording paper immediately after fixing is stored in the stacker, it is desired that the recording paper is not inverted and the length of the introduction passage 13 is short. Further, the double-sided copying machine shown in FIG. 2 is provided with a re-feeding roller 16 'which swings up and down in front of the end of the re-feeding path 18.
Since there is a gap between the end of the introduction passage 13 and the end of the re-feeding passage 18, it is difficult to downsize the introduction passage 13 and the re-feeding passage 18 in the vertical and front-back directions. Therefore, it is difficult to reduce the size of the double-sided copying machine and shorten the total length of the introduction passage and the re-feeding passage. Further, since the total length of the introduction passage and the re-feeding passage is long, jamming is likely to occur, and it is necessary to sufficiently take measures against static electricity.

As described above, the conventional double-sided copying machine has various problems, and it is difficult to say that it is practically sufficient.

An object of the present invention is to solve the above-mentioned problems of the related art. Specifically, the number of reversals of the introduction passage is reduced, and further, the ends of the introduction passage and the re-feed passage connected to the stacker are reduced. It is an object of the present invention to provide a small-sized image forming apparatus with small jamming by arranging the units close to each other.

The present invention has an image forming unit for forming an image on one side of a recording paper, and supplies the recording paper to the image forming unit to supply the first recording paper.
In a double-sided image forming apparatus that forms an image on a surface, then reverses the recording paper, feeds it again to the image forming unit, and forms an image on the second surface of the recording paper, the image forming unit is disposed below the image forming unit. The stacker for temporarily storing the recording paper on which the image formation is completed on the first side substantially horizontally, and the recording paper which is conveyed from the image forming unit and on which the image formation is completed on the first side are reversed to record. With the first side of the paper facing downward, an introduction passage for introducing and storing the recording paper into the stacker from the front end of the recording paper, and the stored recording paper is fed from the stacker with the rear end of the recording paper as the front. A double-sided image forming apparatus, comprising: a sheet re-feeding path that passes through the upper side of the stacker and supplies the image forming unit with the first surface facing downward and the second surface facing upward. By achieving the above-mentioned object, Theft could be.

EXAMPLE The present invention will be described in detail with reference to the example shown in FIG.

FIG. 1 is a schematic explanatory view of a main part of a double-sided copying machine according to an embodiment of the present invention. In FIG. 1, the same reference numerals as those in FIG. 2 indicate the same functional members. 14 is the introduction-refeed roller,
It is controlled so that it is rotated counterclockwise at the time of introduction and is rotated clockwise at the time of re-feeding.
Reference numeral 15 denotes a stacker for storing the recording paper on which the first side has been copied, with the copy side facing downward. 16
Is a sheet re-feeding roller, which is controlled so as to be swung to a position indicated by a dotted line at the time of sheet re-feeding and to be driven to rotate clockwise. Reference numeral 17 denotes an introduction-refeed guide plate, which is controlled to be arranged at a position shown by a solid line at the time of introduction and at a position shown by a dotted line at the time of re-feed.

The double-sided copying apparatus shown in FIG. 1 is configured as described above, and a normal single-sided copying is performed in the same manner as the conventional double-sided copying apparatus shown on the second side, but the double-sided copying is partially different. Is done like. The recording paper on which the copying of the first side is completed is introduced into the introduction path 13 and the introduction-refeed guide plate 17 arranged at the position shown by the solid line and the introduction-refeed rotated and driven in the counterclockwise direction. It is stored in the stacker 15 via the roller 14. At that time, the recording paper is stored in the stacker 15 with its front end facing upstream of the copy forming passage and its first surface facing downward. After a predetermined amount of recording paper is stored,
Copying on the second side starts, but introduction-refeed roller 14
Since the re-feed roller 16 is driven to rotate in the clockwise direction, and the re-feed roller 16 swings downward as shown by the dotted line to come into contact with the recording paper, the recording paper is introduced with its rear end at the beginning. -Refeeding roller 14, introduction-Refeeding sheet is fed to the timing roller 6 through the refeeding guide plate 17 and the refeeding path 18. Since the recording paper is fed with the second side facing upward,
After that, the second side is copied in the same manner as the conventional one, and the double-sided copy is completed.

In this embodiment, the recording paper on which the copying of the first side has been completed as described above can be smoothly reversed to perform double-sided copying as in the conventional case. Further, in the present embodiment, since the number of times of reversal of the recording paper in the introduction path is one, compared with the conventional example in which the number of times of reversal of the recording paper is two,
The number of inversions was small, and the length of the introduction passage was shortened. As a result, the frequency of jamming can be reduced. Further, by adopting the structure of the present invention, the introduction passage is formed to have a gentle bend to some extent, and the re-feeding passage is provided in the space formed by the introduction passage, whereby space saving is achieved and further jamming is achieved. It has become possible to provide a device with less power consumption. In addition, the introduction passage of the reversing re-feeding passage in this embodiment
Since 13 and the re-feeding passage 18 are integrated so that the ends connected to the stacker 15 are parallel to each other and are switched by the introduction-re-feeding guide plate 17, both ends are vertically and forward and backward. Compared with the conventional one, which is provided with a space in the direction of, the size is much smaller in the up-down direction and the front-back direction, and the total passage length of both is shortened. Further, since the introduction passage 13 and the re-feeding passage 18 are connected at one end of the stacker 15, compared to the conventional one in which the introduction passage 13 is connected to the stacker 15 in front of the upper portion of the re-feeding roller 16. The stacker 15 has become much shorter and smaller in the front-rear direction. As described above, since the number of times of reversal of the recording paper in the introduction passage 13 is one, the frequency of jamming is smaller than that in the conventional one in which the number of reversals of the recording paper is two. Further, the introduction passage 13 which constitutes the re-feeding passage
Since the re-feeding path 18 and stacker 15 are smaller and shorter in the vertical and front-back directions than the conventional ones, and are shorter, the reversing re-feeding path is smaller in the vertical and front-back directions, and the total length of the path is longer. Became shorter. In addition, since the total length of the reversing sheet re-feeding path is short, the number of places where static electricity removing measures are taken is smaller than that of the conventional one, and the probability of jamming is low. Further, in the double-sided copying machine, since the reversing re-feeding passage is downsized in the vertical and front-back directions, the gantry or the machine housing the reversing re-feeding passage is also downsized, and the entire apparatus is downsized.

EFFECTS OF THE INVENTION The present invention has an image forming unit that forms an image on one side of a recording paper, and supplies the recording paper to the image forming unit to supply the first recording paper.
In a double-sided image forming apparatus that forms an image on a surface, then reverses the recording paper, feeds it again to the image forming unit, and forms an image on the second surface of the recording paper, the image forming unit is disposed below the image forming unit. The stacker for temporarily storing the recording paper on which the image formation is completed on the first side substantially horizontally, and the recording paper which is conveyed from the image forming unit and on which the image formation is completed on the first side are reversed to record. With the first side of the paper facing downward, an introduction passage for introducing and storing the recording paper into the stacker from the front end of the recording paper, and the stored recording paper is fed from the stacker with the rear end of the recording paper as the front. A sheet re-feeding path that passes through the upper side of the stacker and supplies the image forming unit with the first surface facing downward and the second surface facing upward. The number of reversals of the recording paper in the introduction passage is once. , Number of reversals of the recording paper as compared to that reversal number of the recording paper of the prior art is two times is low. Furthermore, the length of the introduction passage is also shortened. This made it possible to reduce the probability of jamming. The introduction passage and the refeed passage are selectively connected to the stacker to form a recording paper passage extending from the introduction passage to the stacker and a recording paper passage extending from the stacker to the refeed passage. Since it has a recording paper path switching means, it is much smaller in the vertical and front-rear directions than the conventional one in which both ends are provided with a space in the vertical and front-rear directions. And the total length of the passage between the two became shorter. As a result, it is possible to reduce the size of the reversing and re-feeding path, and it is also possible to reduce the size of the entire apparatus.

Further, since the re-feeding passage passes above the stacker, the introduction passage is configured with a moderate bend, and the re-feeding passage is provided in the space formed by the introduction passage to save space. It has become possible to provide a device with less jamming.

Further, the stored recording paper is fed from the stacker with the rear end of the recording paper as the leading end, passes through the upper side of the stacker, and the first surface faces downward and the second surface faces upward. Since it has a sheet re-feeding path for feeding to the image forming unit, the recording sheet conveyed from the stacker to the sheet re-feeding path first bends to the right with respect to the traveling direction, and further above it with respect to the traveling direction. It is bent to the left and transported to the image forming unit. As a result, the re-feeding path is bent in the opposite directions, so that the recording paper conveyed from the stacker is conveyed straight to the image forming section with the curls cancelled, and there is no risk of jamming. It has also become possible to provide an apparatus capable of forming stable images.

As described above, the present invention can achieve the above object by the above configuration.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an embodiment of the present invention, and FIG. 2 is a schematic explanatory view of a conventional double-sided copying machine. 1 ... Photosensitive drum, 2 ... Transfer / separation device 3 ... Paper feeding device, 6 ... Timing roller 8 ... Fixing roller, 11 ... Paper ejection tray 12 ... Paper ejection-introduction guide plate, 13 ... … Introduction path 14 …… Introduction-refeed roller, 15 …… Stacker 16 …… Refeed roller, 17 …… Introduction-refeed guide plate 18 …… Refeed path

Claims (2)

[Claims] 1. An image forming section for forming an image on one side of a recording sheet, the recording sheet is supplied to the image forming section to form an image on the first side of the recording sheet, and then the recording sheet is turned upside down. In the double-sided image forming apparatus that feeds the image to the image forming unit again to form an image on the second surface of the recording paper, the recording is completed below the image forming unit and the image formation is completed on the first surface. A stacker that temporarily stores the paper substantially horizontally, and the recording paper that has been conveyed from the image forming unit and that has completed image formation on the first surface is turned upside down so that the first surface of the recording paper faces downward. An introduction path for introducing and storing the recording paper into the stacker from the front end, and the stored recording paper is fed from the stacker with the rear end of the recording paper as the leading end and passes above the stacker,
A double-sided image forming apparatus, comprising: a sheet re-feeding path for supplying the sheet to the image forming unit with the first surface facing downward and the second surface facing upward. 2. A recording paper path from the introduction path to the stacker and a recording paper from the stacker to the refeed path by selectively connecting the introduction path and the refeed path to the stacker. Claim 1 characterized in that it has a recording paper path switching means for forming the path of the recording paper.
Double-sided image forming apparatus according to item.