JPH02138043A - Electrophotographic double-sided recording device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention can be applied to electrophotographic recording devices that record on paper using an electrophotographic method, such as laser printers and copying machines. . In particular, the present invention relates to a double-sided recording apparatus that first records on one side of a sheet of paper and then records on the other side.

Steal] evil 1e 4 Conventionally, in this type of electrophotographic double-sided recording device.

The image on the photoreceptor is transferred and then passed through a fixing means, and recording is first performed on one side of the paper. Thereafter, the sheet is sent through a double-sided recording sheet discharge path to a sheet reversing means by a set of transport rollers provided therein. Then, the paper is reversed by the paper reversing means and fed again, the image on the photoreceptor is transferred, and then passes through the fixing means, and recording is then performed on the other side of the paper as well.

By the way, a conventional set of conveying rollers provided in a double-sided recording paper discharge path has a configuration as shown in FIG. 5, for example. Reference numeral 1 in the figure indicates one of the conveying rollers, and a plurality of rollers 3 are mounted on a roller shaft 2 at regular intervals. The reference numeral 4 in the figure is the other conveyance roller, and a plurality of rollers are placed on a roller shaft 5 that extends parallel to the roller shaft 2 of the conveyance roller 1 and that press against the roller 3 of the conveyance roller 1. The roller 6... is installed. Both rollers 3 and 6 were made of the same material.

For this reason, the rollers 3 and 6 were evenly pressed against each other as shown in FIG. 6, and the nip position n formed by them was the center position of the double-sided recording sheet discharge path 7.

In other words, one guide plate 8 forming one double-sided recording wandering paper path 7
The distance a between the guide plate 9 and the nip position n is equal to the distance a between the other guide plate 9 and the nip position n.

Problem to be Solved by the Invention However, in the fixing means, a sheet of paper is held between a fixing roller and a pressure roller that presses against the fixing roller, and heat and pressure are applied to fix the transferred image on the sheet of paper. Therefore, at this time, the heat of the fixing roller causes the surface of the paper in contact with it to stretch slightly, causing the paper to curl in the length direction as shown in Figure 7 (A) or in the width direction as shown in Figure 7 (B). I will do it. The degree of this curl varies depending on the paper thickness, paper quality, paper cutting direction, paper moisture content, etc.

For this reason, after refeeding the paper, jams, folded edges, wrinkles, etc. are likely to occur, especially at the registration roller position where the roller pressure is high or at the position between the fixing roller and the pressure roller of the fixing means, which hinders smooth paper transport. There was an issue to be solved. Further, there was a problem in that the paper did not adhere well to the photoreceptor at the transfer position, resulting in poor transfer.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned conventional problems in electrophotographic double-sided recording devices,
The objective is to enable smooth paper conveyance without wrinkles and the like, and to prevent the occurrence of transfer defects.

Means for Solving the Problems Therefore, in the present invention, as shown in the illustrated embodiment below, for example, after transferring the image on the photoreceptor 12, the paper 45 is passed through the fixing means 26 and recorded on one side. A pair of conveyance rollers 48 and
49, the paper is sent to the paper reversing means 38, and the paper is sent to the paper reversing means 3.
8, the image is transferred onto the photoreceptor 12 again, and then transferred to the fixing means 2.
In an electrophotographic double-sided recording device that passes through the paper 45 and then records on the other side of the paper 45, the set of conveyance rollers 4
One of the rollers 53 of 8.49 is made of a material harder than the other roller 55 that presses against it.

Function: Due to the hardness difference between both rollers 53 and 55, a large nip N is formed between the transport rollers 48 and 49, and the nip N
The paper 45 is curled in the opposite direction by the fixing means 26.
Curling of the paper 45 caused by passing through the paper 45 is corrected.

Example Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 4 shows a schematic configuration of a laser printer according to an embodiment of the present invention. In FIG. 4, reference numeral 10 is a device main body;
It is placed on an optional dedicated table 11.

A drum-shaped photoreceptor 12 is provided in the center of the apparatus main body 10 and rotates clockwise in the figure. And the photoreceptor 12
A charging means 13, an optical writing means 14, a developing means 15, a transfer means 16, and a cleaning means 17 are arranged around the rotating direction in this order. Of these, the developing means 15.
The transfer means 16, cleaning means 17, etc. are connected to the photoreceptor 12.
One image forming case 18, which is housed in the image forming case 18, can be pulled out from the apparatus main body 10 toward the front (front side). Due to this.

The photoreceptor 12, each means 15, 16, 17, etc. housed therein can be easily replaced and maintained.

On the other hand, a first paper feed cassette 19 and a second paper feed cassette 20 are vertically and removably loaded on the right side of the apparatus main body 10 in the drawing. And those paper feed cassettes 19.
The mounting portion 20 is provided with a paper feeding means 24 having paper feeding rollers 21, 21, a registration sensor 22, a pair of registration rollers 23, 23, and the like. On the other hand, on the opposite side of the paper feeding means 24 with the aforementioned transfer means 16 in between, a conveying means 25, a fixing means 26, a switching means 27, an ejection conveying means 28, etc. are arranged in this order.

The paper discharge conveying means 28 includes a face-down paper discharge path 29, a face-up paper discharge path 30, and a double-sided recording paper discharge path 31. The face-down paper discharge path 29 communicates with a paper discharge stack section 33 also on the apparatus main body 10 via a discharge means 32 provided on the apparatus main body 10 . The face-up paper discharge path 30 leads to a face-up tray 34 provided on the side of the apparatus main body 10 so as to be openable and closable. The double-sided recording paper path 31 leads to the dedicated table 11.

In addition, in the apparatus main body 10, for example, a main motor 35 is disposed below the transfer means 16, and a power supply unit 36 is disposed below the conveyance means 25 and the fixing means 26. On the other hand, a control means 37 is provided in the upper part of the apparatus main body 10.
It becomes by arranging. In this control means 37, the device main body 10
In addition to controlling the engine itself, it also controls interaction with the host machine.

By the way, the dedicated table 11 is provided with a paper reversing means 38 in communication with the above-mentioned double-sided recording paper discharge path 31, and
A paper refeeding means 39 is provided which communicates from the paper reversing means 38 to the paper feeding means 24 of the apparatus main body 10 described above. Also,
A large quantity paper feed cassette 40 is removably loaded on the right side of the dedicated table 11 in the figure. A large amount of paper feeding means 42 having a paper feeding roller 41 and the like is provided at the mounting portion of the large amount of paper feeding cassette 40.

However, when operating the laser printer now,
The paper feed roller 21 or the paper feed roller 41 is selected and driven as appropriate, and the paper 45 is sent out one by one from the cassettes 19 and 40. Then, the registration sensor 22 detects the leading edge of the paper 45, and the paper 45 is brought into contact with the registration roller 23. Stop and prevent skew from occurring here.

On the other hand, the surface of the photoreceptor 12 is sequentially charged by the charging means 13 while rotating clockwise in the figure, and the surface of the photoreceptor 12 is charged by the next optical writing means 1.
In step 4, a laser beam is irradiated to form an electrostatic latent image on the surface, and then when passing through the developing means 15, the electrostatic latent image is successively visualized. Then, the above-mentioned registration rollers 23, 23 are driven by aligning the image with the resist, and the above-mentioned paper 45, which was in contact with the registration rollers 23, 23, is sent out toward the photoreceptor 12, and the photoreceptor is The image on the paper 45 is transferred by the transfer means 16 to the paper 45.

After the transfer, the surface of the photoreceptor 12 is cleaned by a cleaning means 17.

On the other hand, the paper 45 is transferred to the fixing means 26 by the conveyance means 25.
The image transferred thereto is fixed by the fixing means 26 thereof. The fixing means 26 includes a fixing roller 26a and a pressure roller 26b that presses against the fixing roller 26a. Then, the paper 45 is sandwiched between the rollers 26a and 26b, and heat and pressure are applied to the paper 45 to fix it. And when a large amount of paper 45 is to be discharged.

Alternatively, if you want to stack the pages in order, the conveyance rollers 4
6 and 46, and sent out to the discharged paper stack section 33 via the discharge means 32. When the paper 45 is thick paper such as a postcard, the switching means 27 switches the ejection direction, and the ejection rollers 47 pass through the face-up paper ejection path 30 of the paper ejection conveyance means 28 and send it out to the open face-up tray. Stack face up on top of 34. Furthermore, if you want to record on the back side, you can also switch the ejection direction using the switching means 27, and
A set of transport rollers 48 pass through the double-sided recording paper discharge path 31 of
・The paper is conveyed by the paper reversing means 38 on the dedicated table 11.
lead to. Then, the sheet is reversed and conveyed again to the sheet feeding means 24 of the apparatus main body 10 through the sheet re-feeding means 39, and is again stopped by hitting the registration rollers 23. Then, it is recorded on the back side as well and is discharged onto the discharge stack section 33 or the face-up tray 34.

By the way, in this invention, the above-mentioned set of conveyance rollers 4
8.49, configured as shown in FIGS. 1 to 3, for example. As shown in FIG. 3, one of the conveyance rollers 48 has one roller 53 mounted on a roller shaft 52. As shown in FIG. The other conveyance roller 49 has a roller 55 that presses against the roller 53 attached to a roller axis 54 parallel to the roller axis 52. Both rollers 53 and 55 are wide and are used in the laser printer. The roller width should be larger than the maximum paper width. This eliminates the inconvenience of conventional conveyance rollers, which required rollers to be placed at both the left and right end positions of each paper size, and also eliminates the drawback that the leading edge of the paper tends to wave.

In addition, in the pair of conveying rollers 48 and 49, the roller 53 of one 48 is made of a harder material than the roller 55 of the other 49 that presses against it.

For example, the roller 53 may be a chloroprene rubber roller or a metal roller, and the roller 55 may be a foam roller (sponge roller). Therefore, as shown in FIG. 1, due to the difference in hardness between the two rollers 53 and 55,
Form a large nip N at 9. After the image on the photoreceptor 12 has been transferred and the sheet 45 has passed through the post-fixing means 26, the sheet 45 is sent to the sheet reversing means 38 through the double-sided recording sheet discharge path 31 in a curled state as shown in the figure. A set of transport rollers 48 and 4 provided in the double-sided recording paper discharge path 31
At step 9, a curl is applied in the opposite direction, and the curl caused by passing through the fixing means 26 is corrected. Reference numerals 56 and 57 in the figure are guide plates that form the double-sided recording paper discharge path 31.

In the embodiment shown in FIG.
is composed of one conveyance roller 48 on one side and one conveyance roller 49 on the other side. but.

As shown in FIG. 2, the pair of conveyor rollers 48 and 49 are
It may be configured with one conveyance roller 48 on one side and two conveyance rollers 49, 49 on the other side.

In this case, similarly, the roller 53 of one conveyance roller 48 is pressed against the other two conveyance rollers 49.
・Constructed from a material harder than the rollers 55 and 55 of 49.

Therefore, according to the present invention, in an electrophotographic double-sided recording apparatus, when a single-sided recording support sheet is sent through a double-sided recording discharge path to a paper reversing means, a set of conveying rollers provided therein is used. Curls can be straightened. Therefore, it is possible to eliminate occurrences of jams, folded edges, wrinkles, etc., to enable smooth conveyance of paper, and to improve stackability at the paper discharge section. Furthermore, it is possible to eliminate the occurrence of transfer defects due to curling.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the present invention, and FIG. 4 is a partially enlarged view of the laser printer showing a set of conveyance rollers in the duplex recording paper ejection path, and FIG. 2 shows another embodiment. Similarly, FIG. 3 is a partially enlarged view showing a set of conveyance rollers in the double-sided recording paper ejection path, FIG. 3 is a plan view of a set of conveyance rollers, and FIG. 5 is a plan view of a conventional set of conveyance rollers, FIG. 6 is a layout diagram of the conveyance rollers in the duplex recording paper ejection path, and FIGS. 7(A) and (B) are the curled state of the paper. FIG. 12...Photoreceptor 26...Fixing means 31...Double-sided recording paper ejection path 38...
...Paper reversing means 45... Paper 48, 49... Conveyance rollers 53, 55.
・・・・・・・・・Roller Figure 2

Claims (1)

[Claims] After the image on the photoreceptor is transferred, the paper, which has been recorded on one side after passing through a fixing means, is sent through a double-sided recording paper ejection path to a paper reversing means by a set of transport rollers provided therein. In an electrophotographic double-sided recording device in which the image on the photoreceptor is transferred again, passed through a fixing means, and then recorded on the other side of the paper, one roller of the set of conveyance rollers is , an electrophotographic double-sided recording device made of a material harder than the other roller that presses against it.