JPS60151658A - Apparatus for copying both sides of paper - Google Patents

Abstract

PURPOSE:To prevent ejection of a wrong both-side copy by installing the first and second double feed detectors, and changing over a mobile guide plate or stopping a machine in accordance with their outputs. CONSTITUTION:A paper having been fed from a surface paper feeder 1 without being doubly fed, transferred, fixed, and inverted is ejected with releasing rollers 11 to a both-side tray 10. When the transfer paper is doubly fed from the feeder 1, the double papers are detected with the first double feed detector 20, accordingly a mobile guide plate 21 is displaced downward to guide one of the doubly fed papers to a doubly fed paper container 22. When the double papers are not separated with a doubly fed paper separator 14, such as a friction roller paper separation feeder, and sent forth, they are detected with the second double feed detector 24, and at that point of time, the machine is stopped.

Description

[Detailed description of the invention] Technical field The present invention relates to a double-sided copying device.

As shown in FIG. 1, the configuration of the conventional double-sided duplex machine is as shown in FIG. After the toner images are transferred by feeding the paper, the fixing device 6 fixes the toner image, and once the single-sided copying has been completed, the gate is reversed from front to back by, for example, a three-roller type reversing device Tvc, and the gate 8 is placed above the front paper feed section l. A preset number of copies is loaded onto the duplex tray lO of the duplex paper feed section 9 provided f' by the ejection roller 11, and then the duplex tray lO is loaded in order to copy the second side.
The single-sided copied sheets stacked in O are transferred one by one to the transfer unit 5.
It is well known that the sheet is fed to the printer, the back side is transferred, and the sheet after double-sided copying is discharged from the paper discharge roller 12 to the paper discharge tray 131C by switching the gate 8.

However, in the conventional apparatus, even transfer paper that is double-fed from the front paper feed section l and transfers only one sheet in contact with the photoreceptor 4,
Transfer paper that was fed only one sheet without double feeding was also indiscriminately ejected and stacked in the double-sided tray IO, and then fed as is for copying the back side, so one side was not copied. Occasionally, poor duplex copies would occur.

In order to prevent this, a blank page detection means is installed in the conveyance path that refeeds paper from the duplex tray, and it detects whether or not a copy is made on the side that is cold after copying is performed first. It is proposed to detect blank paper that has not been transferred due to storage and guide it to the paper output tray or front paper feed section, or to stop the machine and take it out.
When the leading edges of the double-fed sheets are transported to the transfer unit with their leading edges shifted by about 10 positions from each other, the leading edge of the image is missing on the side of the transfer paper that contacts the photoreceptor, and only the leading edge of the image is transferred on the other sheet of paper. If the paper is stored in the double-sided tray after storage and is re-fed, the blank paper detection means cannot eliminate such transfer defects.

Purpose The present invention has been made in view of the occurrence of double-sided defective copy paper caused by double feeding of transfer paper in conventional double-sided copying devices, and an object of the present invention is to provide a double-sided copying machine that prevents the discharge of double-sided defective copy paper. .

Hereinafter, the present invention will be explained in detail based on embodiments shown in the drawings.

FIG. 2 is a diagram showing an embodiment in which the present invention is applied to the apparatus shown in FIG. 1, and the same members as those in the apparatus shown in FIG. 1 are given the same reference numerals and will be described. In the embodiment of the present invention shown in FIG. 2, a multi-feed detection device 20 and a movable guide plate 21 are sequentially arranged between the gate 8 and the discharge roller 11, and a double-feed paper is placed below the double-sided tray 10. A storage section 22 is provided. The movable guide plate 21 is normally at position V? where it guides the paper toward the discharge roller 11. - Yes, but the first double feed detection device 20
When the double feeding of the transfer paper is fully detected, the transfer paper is controlled to be displaced to the position shown by the chain line in the figure, where the transfer paper is guided to the double feeding paper storage section 22. Note that a discharge twin 23 is provided on the conveyance path of the discharge roller 11 to detect the discharge of paper.

Further, a second double feed detection device 24 is provided at the exit of the double-sided sheet feeding section 9. The double-sided paper feed section 9 is equipped with a double-feed separation device, for example, a friction roller separation paper feed device 14, as is customary for paper feed sections. It is detected by the feed detection device 24 and the machine is controlled to stop.

As the above two double feed detection devices, various known devices that utilize changes in the amount of transmitted light, changes in paper thickness, changes in capacitance, etc. can be used.

Since this device is constructed as described above, the paper that has been transferred, fixed, and reversed is ejected from the front paper feed section 1 to the duplex tray 10 from the paper feed section 1 without being double fed. . Transfer paper is double fed from the front paper feed section l21. In this case, the first double-feed detection device 20 detects an error, and as a result, the movable guide plate 21 is displaced downward, and the double-feed paper is removed from the double-feed storage section 22.
Guided to. Since the discharge tween 23 counts only the transfer paper that has passed the discharge roller 11, the transfer paper that has been multi-fed and stored in the multi-feed storage section 22 is not counted. Then, feed paper from the front paper feed section until the count number of the ejection twin 23 reaches the preset number of copies. If the double-sided tray 10 contains the set number of single-sided copies 7-
After the paper is loaded, double-sided paper feeding becomes possible, and the copy button changes from red to blue to notify the operator. Therefore, when the original is replaced with a new one for back side paper feeding and the copy button is pressed again, paper feeding is started from the double-sided paper feeding section 10. If the double feed is not separated by the double feed separation device 14 such as a friction roller separation and feeding device, the @2M feed detection device 24
The machine will stop at that point. Then, remove the double-feed paper, reset the duplex tray IOK, press the print button again, and resume copying the back side.

As a result of the above effects, not only defective copies where one side is blank and only the other side is transferred, but also defective copies where the leading edge is missing, some images are missing, or only a portion of the image is transferred are eliminated. This prevents defective copies from being ejected onto a paper tray, and particularly when a printer is used for collation, defective copies are prevented from being collated.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a conventional structure of a double-sided copying apparatus, and FIG. 2 is a sectional view showing an embodiment of the present invention. 9...Double-sided paper feed unit 10...Double-sided tray (intermediate tray) 20"...First double feed detection device @21...Temporary movable guide 2
2... Double feed storage section 24... Second double feed detection device

Claims (1)

[Claims] In a double-sided copying machine, sheets of one side of which have been copied are stored and stacked in one intermediate tray, and sheets are fed one by one from the intermediate tray for copying the other side. A feed detection device is provided, and a double feed storage section is provided in parallel with the intermediate tray, and the sheet tray can be switched and guided between the intermediate tray V and the double feed storage section on the downstream side of the $1 double feed detection device. A movable guide plate is provided, and a second double feed detection device is provided near the exit of the intermediate tray, and when the first double feed detection device detects all double feeds, the double feed sheets are guided to the double feed storage section. A double-sided copying apparatus characterized in that the movable guide plate is switched as shown in FIG.