JPS63110465A - Automatic both sides copying machine - Google Patents

Abstract

PURPOSE:To reduce the number of rollers to be used for refeeding transfer paper and to reduce the cost of an automatic both sides copying machine, by providing a returning roller which is brought into contact with a lower fixing roller and rotated in the direction opposite to that of the lower fixing roller at a location facing the bottom side of the lower fixing roller provided in a returning path. CONSTITUTION:This copying machine is provided with paper discharging rollers 3 which can be rotated in both normal and reverse directions, paper coming-out path 4 provided between fixing rollers 2a and 2b and the paper discharging rollers 3, and returning path 5 which is formed in an extended state between the rollers 3 and the paper coming-in side D3 of a photosensitive body 1. The lower fixing roller 2b is set in the returning path 5 and a returning roller 10 which is brought into contact with the roller 2b and rotated in the direction opposite to that of the roller 2b is provided at a location facing the bottom side of the roller 2b. Transfer paper, to which a toner image is transferred from the photosensitive body 1, is sent to the returning path 5 by the returning roller 10 on the bottom side and lower fixing roller 2b on the top side after the paper reaches the paper discharging rollers 3 from the paper coming-out path 4 and again fed to the paper coming-in side D2 of the photosensitive body 1, by which toner transfer is performed to the untransferred surface of the transfer paper. Therefore, the number of rollers is reduced and the cost of this copying machine can be reduced.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an automatic double-sided copying machine having a return path for feeding transfer paper to a photoreceptor again after one-sided transfer and transferring toner to an untransferred surface. Regarding.

<Prior Art> As shown in FIG. 2, a conventional automatic double-sided copying machine with a return path includes a photoreceptor 1, a pair of upper and lower fixing rollers 2a and 2b arranged on the paper output side D1 of the photoreceptor 1. , a forward-reversible paper discharge roller 3 disposed on the paper output side D2 of the fixing rollers 2 a, 2 b, and a paper discharge path 4 disposed between the fixing rollers 2 a, 2 b and the paper discharge roller 3; , and a return path 5 extending from the paper ejection roller 3 to the paper input side D3 of the photoreceptor 1, so that the transfer paper P is returned to the photoreceptor 1 by reversing the paper ejection roller 3. The paper is fed to the side D3 and toner is transferred to the non-transferred surface of the transfer paper P. and,
This is achieved by driving the paper ejection tray T and the paper ejection roller 3 located upstream thereof in forward and reverse directions, and detecting the trailing edge of the transfer paper P just before it passes through the paper ejection roller 3, without using an intermediate tray. Double-sided copying is performed by a control circuit that controls forward and reverse rotation of the paper ejection roller based on the output signal of the detection device.

In this case, as shown in the figure, the transfer paper P after the switchback is moved through the route change guide 7 and the reverse direction in order to reach the registration roller 6 disposed on the paper input side D3 of the photoreceptor 1 from the paper discharge roller 3. An intermediate conveyance roller 8 is used to change the route.

Then, the return path 5 curves significantly downward from the paper discharge roller 3 and reaches the paper input side D3 of the photoreceptor 1.

Problems to be Solved by the Invention In the automatic double-sided copying machine having the configuration described above, the return path 5 includes the fixing roller 2a.
, 21t and curves downward, the distance between the paper ejection roller 3 and the registration roller 6 inevitably increases, occupying extra space inside the main body A, and requiring a large number of intermediate conveyance rollers 8. At the same time, this becomes an unforeseen factor that hinders the miniaturization, simplification, and cost reduction of the main body A. Further, there is a problem that stable conveyance performance is hindered due to the necessity of transferring the transfer paper P along the curved return path 5.

In view of the above problems, the present invention aims to reduce the number of rollers for refeeding transfer paper and to reduce costs.
Our goal is to provide automatic double-sided copying machines.

<Means for solving the problem> As shown in the side view of FIG. Fixing rollers 2a, 2b, a paper discharge roller 3 disposed on the paper output side D2 of the fixing rollers 2a, 2b, which is capable of forward and reverse rotation, and a paper discharging roller 3 disposed between the fixing rollers 2a, 2b and the elementary roller 3. It includes a paper output path 4 and a return path 5 extending from the paper discharge roller 3 to the paper input side [ ) 3 of the photoreceptor 1. In an automatic double-sided copying machine that feeds paper again to the paper input side D3 of the photoreceptor 1 and transfers toner to the non-transferred surface of the transfer paper P, the lower fixing roller 21 is disposed in the return path 5, and A return roller 10 is disposed in contact with the lower fixing roller 21 and rotates in the opposite direction to the lower fixing roller 21 on the lower side facing the lower fixing roller 21 of the path 5.

<Function> In the above-mentioned means for solving the problem, the transfer paper on which the toner has been transferred by the photoreceptor 1 is fixed with the toner by the fixing rollers 2a and 2b, and is guided to the paper output path 4 and reaches the paper discharge roller 3. Thereafter, the transfer paper is fed by the reverse rotation of the paper roller 3. Then, the transfer paper is sent to the return path 5 by the lower return roller 10 and the lower fixing roller 2b above it.
The paper is again fed to the paper input side D2 of the photoreceptor 1, and the toner is transferred to the non-transferred surface.

Then, when refeeding the paper to the photoreceptor 1, the lower fixing roller 21]
Since the number of rollers is reduced, costs can be reduced.

<Embodiment> Hereinafter, an embodiment of the automatic double-sided copying machine of the present invention will be described based on FIG. FIG. 1 is a longitudinal sectional side view of an automatic double-sided copying machine showing an embodiment of the present invention.

As shown in the figure, the automatic double-sided copying machine according to the present invention includes:
A photoreceptor 1 and -1- arranged on the paper output side D1 of the photoreceptor 1
A lower pair of fixing rollers 2a and 2b, and the fixing roller 2
a paper ejecting roller 3 disposed on the paper ejecting side 1) 2 of a and 2b capable of forward/reverse rotation; A return path 5 is formed extending from the paper discharge roller 3 to the paper input side D3 of the photoreceptor 1, and the transfer paper 1 is returned to the paper input side of the photoreceptor 1 by reversing the 11 paper rollers 3. In an automatic double-sided copying machine that transfers toner to the non-transferred surface of transfer paper P by feeding paper to D3, a page fixing roller 2b (driving roller) is disposed in the return path 5, and a fixing roller 2b (driving roller) is provided under the return path 5. Roller-2
A return roller 10 (non-driving roller) that contacts the lower fixing roller 21 and rotates in the opposite direction to the lower fixing roller 21 is disposed at a lower opposing position of b.

On the paper input side D3 of the image forming section A1 including the photoreceptor 1, there is a registration roller 6 for feeding the transfer paper P fed from the main body At: a removable paper feed cassette 11 to the photoreceptor 1.
are arranged.

A paper ejection tray T is formed by protruding outside the main body A on the paper ejection side D4 of the paper ejection roller 3, and the paper ejection tray T is formed with a protruding side tip 1.2a facing in the elevation direction.

A pair of upper and lower first intermediate conveyance rollers 13 is disposed on the paper output side D5 of the return roller 10, and a second intermediate conveyance roller 14 is disposed on the paper output side D6 of the roller 13, and the roller 14 is connected to the registration roller 6. It is located almost directly below. The return path 5 is formed continuously between the straight first path 5a and the straight path 5a located on the extension connecting the front end 12a and the rear end 12b of the paper output tray T, and is connected to the second intermediate conveyance roller 14. and a U-shaped second path 5b extending from to the registration roller 6.

Reference numeral 15 denotes a conveyor belt disposed between the photoreceptor 1 and fixing rollers 2a and 2b.

Next, the operation will be described. The transfer paper P fed from the cassette 11 is developed on one side by the image forming section A1, is transported to the fixing rollers 2a, 21) by the transport belt 15, and is fixed with toner. [This fixing roller 2a,
The paper is sent to the paper discharge roller 3 through the paper output path 4 by the rotation of the paper 2b. In the case of double-sided copying, the transfer paper P passes through the paper output path 4, and immediately before the transfer paper passes the paper discharge roller 3, an output signal is sent to a control device such as a detection device that detects the trailing edge of the paper output roller 3. 3 starts reverse rotation.

As a result, the rear end of the transfer paper enters the return path 5 from the paper output path 4 due to its weight, and then passes through the mating portion 16 of the lower fixing roller 21) and the return roller 10, and passes through the second path 5a. Due to the rotational conveyance of the first intermediate conveyance roller 13 and the second intermediate conveyance roller 14, the sheet passes through the second path 5b and reaches the registration rollers 6. In this state, the untransferred surface of the transfer paper P comes into contact with the photosensitive surface of the photoreceptor 1, and toner transfer is performed here. Thereafter, the paper is output onto a paper output tray by the conveyor belt 15, fixing rollers 2a, 2b, and paper discharge roller 3.

Note that the transfer paper P enters the return path 5 and is transferred to the lower fixing roller 21.
) and the return roller 10, the transfer paper P is heated again by the lower fixing roller 21], but the pressing force of the transfer paper by the fixing rollers 2a and 2b is 40
-50kg, nip rl 15~4+nm, the pressure here is kept to the minimum pressure necessary for transportation,
If the pressure is kept to a minimum while grasping, there will be no problems such as curling or wrinkling of the transfer paper (1°) Also, when refeeding the transfer paper, the lower fixing roller 2b is used to transport it, so the roller Since the return path 5 is formed of a linear first path 5a and a U-shaped second path 5b, the transfer paper can be moved from the paper discharge roller 3 to the registration roller 6 at the minimum distance. Since the first path 5a is linear, the conveyance of the transfer paper is good, and the lower fixing roller 2b is fixed by the transfer paper when refeeding the paper.
The cleaning performance of the fixing rollers 2a and 2b can be improved by removing dirt from the fixing rollers 2a and 2b.

It should be noted that the present invention is not limited to the above embodiments, and it goes without saying that many modifications and changes can be made to the above embodiments within the scope of the present invention.

<Effects of the Invention> As is clear from the above description, according to the present invention, the transfer paper on which the toner has been transferred by the photoreceptor has the toner fixedly fixed on it by the fixing roller, is guided to the paper output path, reaches the paper ejection roller, and transfers the toner. The paper is fed by the reverse rotation of the paper discharge roller, and the transfer paper is sent to the return path by the lower return roller and the lower fixing roller above it, and is fed again to the paper input side of the photoconductor, where it is untransferred. Since the toner is transferred to the surface and the lower fixing roller is used when refeeding the paper to the photoreceptor, the number of rollers can be reduced, which has the excellent effect of reducing costs.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional side view of an automatic double-sided copying machine showing an embodiment of the present invention, and FIG. 2 is a vertical sectional side view of an automatic double-sided copying machine showing a conventional example. 1: Photoreceptor, 2a, 2b: Fixing roller, 3: Paper ejection roller, 4: Paper output path, 5: Return path, 5a: No. 1 path,
5b: second path, 6: registration roller, 10: return roller, 11: cassette, 13: first opening conveyance roller,
14: Second opening conveyor roller, 15: Conveyor belt, 16
: Combined part, A1-image forming part.

Claims (1)

[Claims] A photoreceptor, a pair of upper and lower fixing rollers arranged on the paper output side of the photoreceptor, a forward-reversible paper ejection roller arranged on the paper ejection side of the fixing roller, and a pair of fixing rollers and paper ejection rollers. and a return path extending from the paper ejection roller to the paper input side of the photoreceptor,
In the automatic double-sided copying machine that feeds the transfer paper to the paper input side of the photoreceptor again by reversing the paper ejection roller and transfers toner to the non-transferred surface of the transfer paper, the lower fixing roller is disposed on the return path. 2. An automatic double-sided copying machine, characterized in that a return roller that contacts the lower fixing roller and rotates in the opposite direction to the lower fixing roller is disposed at a position below the lower fixing roller in the return path and facing the lower fixing roller.