JPH02221040A - Transfer unit for electrophotography - 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 relates to a transfer conveyance unit for electrophotography, and more specifically, transfer paper is sandwiched between a photoreceptor drum and an endless belt, and the endless belt is charged. The present invention relates to a transfer and conveyance unit for electrophotography that transfers data from a photoreceptor drum to a transfer paper and conveys the transfer paper.

(Prior Art) A transfer conveyance unit for electrophotography is a unit used during a transfer process in a copying machine, printer, facsimile, etc. that employs an electrophotographic method.

Conventionally, as a transfer conveyance unit for electrophotography of this type, there is one described in Japanese Patent Application Laid-Open No. 63-83762.

This is an example applied to a copying machine, as shown in FIG.

In FIG. 5, an endless belt 3 is stretched around an upstream roller 1 and a downstream roller 2, and the endless belt 3 is driven in the direction of arrow A in FIG. 5 by the rotation of the upstream roller 1. A rotationally driven photoreceptor drum 4 is provided above the endless belt 3, and the photoreceptor drum 4 is connected to the endless belt 3.
rotates when it comes into contact with. Toner adheres to the photoreceptor drum 4 in correspondence with the copied image, and the adhered toner develops the copied image on the outer peripheral surface of the photoreceptor drum 4. A charger 5 is provided below the contact portion between the endless belt 3 and the photosensitive drum 4, and the endless belt 3 at the contact portion is charged by the charger 5. During so-called repeat copying of the same image onto a plurality of transfer sheets 6, the endless belt 3 and the photosensitive drum 4
is continuously rotating, and the transfer paper 6 is waiting in contact with a pair of registration rollers 7.8 which are stopped. Then, the transfer paper 6 is sequentially conveyed between the endless belt 3 and the photoreceptor drum 4 by a pair of registration rollers 7.80 rotations in accordance with the image on the rotating photoreceptor drum 4, and is sandwiched between them. The toner adhering to the photoreceptor drum 4 is drawn toward the endless belt 3 by the electrical potential difference of the charged endless belt 3, and adheres to the transfer paper 6 between the photoreceptor drum 4 and the endless belt 3, so that the toner is transferred. It has become.

(Problems to be Solved by the Invention) However, in such a conventional transfer conveyance unit for electrophotography, a separate transfer unit is provided in synchronization with the image on the outer peripheral surface of the rotating photoreceptor drum 4. The transfer paper 6 is conveyed between the photosensitive drum 4 and the endless belt 3 by rotating a pair of registration rollers 7.8. Therefore, providing a pair of registration rollers separately not only complicates the configuration, but also increases the tangential speed error of each of the photosensitive drum 4 and the upstream roller 1, so-called linear speed error, and the pair of registration rollers 7. There is a problem in that the linear velocity error of 8 is added and a magnification error deviation, which will be described later, occurs, making it easy for distortion, blurring, etc. to occur in the transferred image.

Magnification error deviation is the length 100
If you place the scale of the fin and make a copy at the same size, the length of the scale copied on the transfer paper will be 101 cranes, and the actual dimensions at 20+u intervals from one end will be 20°19, 21.19
．． This refers to a state where an error occurs in the magnification, such as 22 mm.

(Purpose of the Invention) Therefore, the present invention provides a pressure roller that presses the upstream roller via the endless belt, and brings the endless belt into contact with the photoreceptor drum at the same time as the upstream roller is driven, so that the transfer paper is kept on standby. To eliminate the registration rollers conventionally used for transferring images, to reduce the causes of linear velocity errors while integrating the conveyance unit, to simplify the configuration of the conveyance unit, and to prevent distortion and blurring of transferred images. It is an object.

(Structure of the Invention) In order to achieve the above-mentioned object, the transfer conveyance unit for electrophotography according to the present invention includes an upstream roller that is appropriately rotated by predetermined tamping, and a predetermined distance from the upstream roller that is parallel to the axis of the upstream roller. A downstream roller spaced apart from each other, an endless belt that spans the upstream roller and the downstream roller, a pressure roller that is located above the upstream roller and presses the upstream roller via the endless belt, and an endless belt. A photoreceptor drum located above and driven to rotate, and a contact/separation roller located between the downstream roller and the photoreceptor drum, which can move in the vertical direction, and which presses into contact with the lower surface of the upper side of the endless belt. and an operating means for moving the contact/separation roller upward to bring the endless belt into contact with the photosensitive drum being rotated when the upstream roller is driven.

Hereinafter, the present invention will be specifically explained based on examples.

1 to 4 are diagrams showing one embodiment of an electrophotographic transfer conveyance unit according to the present invention, and are examples applied to a copying machine.

In FIG. 1, reference numeral 11 denotes an upstream roller, and the upstream roller 11 is appropriately rotated at a predetermined timing in the direction of arrow B in FIG. 1 by a drive device (not shown). The downstream roller 12 has an axis parallel to the axis of the upstream roller 11, and is provided at a predetermined distance from the upstream roller 11. An endless belt 13 made of a semiconductor (electrical resistance = 108 to 109 Ω) is stretched between the upstream roller 11 and the downstream roller 12. It is pressed through the endless bell eye 3. Also, endless belt 1
A photoreceptor drum 15 is located above the photoreceptor drum 3, and the photoreceptor drum 15 is rotationally driven by a drive device (not shown). An image of a copy document is developed on the outer peripheral surface of the photoreceptor drum 15 by a developing device (not shown), and the developed image is formed by toner adhering to the outer peripheral surface of the photoreceptor drum 15.

A contact/separation roller 16 is provided between the downstream roller 12 and the photosensitive drum 15 so as to be movable in the vertical direction (in the upward direction of the arrow in FIG. 1). is in pressure contact with the bottom surface of the 17 is the contact/separation roller 1
6, and 17a is a control device that controls the movement of the moving mechanism 17 and the control device 1.
7a has a function as an operating means that simultaneously drives the upstream roller 11 to rotate and moves the contact/separate roller 16 upward to bring the endless belt 13 into contact with the photoreceptor drum 15 that is being rotated. There is. As the moving mechanism 17,
For example, a moving mechanism consisting of a solenoid plunger as shown in FIG. 8 of JP-A No. 63-85667 may be used. Reference numeral 18 is provided directly below the photoreceptor drum 15 with the upper side of the endless belt 13 in between. The transfer charger 18 charges the endless belt 13 close to the photosensitive drum 15 . 19 is a paper feed cassette that stores the transfer paper 2o, and the transfer paper 20 of the paper feed cassette I9 is
is conveyed between the press roller 14 and the endless bell 3 at a predetermined timing by the paper feed roller 21. The endless belt 13 is grounded by the downstream roller 12, and toner or the like that accidentally adheres to the endless belt 13 is cleaned by a cleaning plate 22 and collected in a collection bottle 23. A fixing device 24 is provided further downstream of the downstream roller 12, and a pair of fixing rollers 24a of the fixing device 24 fixes toner on the transferred transfer paper 20, which is conveyed downstream by the endless belt 13. , Transfer paper 20 after fixing
is discharged onto a paper discharge tray 26 by a pair of paper discharge rollers 25.

Here, the endless bell! -Transfer distance of 13 to 111 transfer paper 2
If the feed interval of 0 is 12, then there is a relationship l, ≦h.

For example, as shown in FIG. 2, when transferring 40 sheets of A4 size transfer paper 20 in the horizontal direction at a feed interval of 22=165, 6. >1. =165 fins, two or more sheets of transfer paper 20 are present on the endless belt 13. Since the endless belt 13 is intermittently driven by the upstream roller 11 and the fixing roller 24a is continuously rotating, if 11>12 as described above, the preceding downstream transfer paper 2o is forced to move onto the fixing roller. 24a, resulting in defects in the image before fixing. Therefore, the conveyance distance 11 and the feed interval 12 of the endless bell H3 are 1
The relationship 1≦12 must be satisfied.

In addition, when conveying the transfer paper 2o as shown in FIG.
The total transport length is calculated as L = (A4 horizontal size 210m + 165 fins)
When the linear feed speed is 250 n/sec, conveyance of 40 sheets of transfer paper is completed in about 1 minute.

Next, the operation when copying the same image onto a plurality of transfer sheets will be explained.

The photosensitive drum 15, the fixing roller 24a, and the paper ejection roller 24 rotate, and the upstream roller 11, the downstream roller I2,
Pressing roller I4, contact/separation roller I6, and paper feed roller 21
While the transfer paper 2o is stopped, first, as shown in FIG. Stop at. Next, as shown in FIG. 3, the upstream roller 11 and the pressure roller 14 rotate in accordance with the copy image on the outer peripheral surface of the photosensitive drum 15, and the transfer paper 2o is conveyed downstream.

At the same time, the contact/separation roller 16 moves upward and the endless belt 13 comes into contact with the photosensitive drum 15. Then, the conveyed transfer paper 2o is transferred to the endless bell 3 and the photoreceptor drum 15.
At the same time, the endless belt 13 is charged by the charger 18. Due to the potential difference between the transfer paper 2o and the endless belt 13, the transfer paper 2o is electrostatically attracted to the endless belt, and the toner on the photoconductor drum 15 is drawn toward the endless bell 3 side due to the potential difference and adheres to the transfer paper 20, and the toner on the photoconductor drum 15 is attracted to the endless belt. The image on the drum is transferred to the transfer paper 2°. After that, transfer paper 2
o is peeled off from the photoreceptor drum 15, and at the same time as the transfer is completed, the contact/separation roller 16 moves downward, and the endless belt 13 separates from the photoreceptor drum 15. Note that since the transfer paper 20 itself is not charged, the transfer paper 20 is
Then, as shown in FIG. 4, the transfer paper 20 is further conveyed downstream by the endless belt 13 and sandwiched between the fixing rollers 24a and 24b of the fixing device 24. At this time, since the endless belt 13 is neutralized by the grounding of the downstream roller 12, it is smoothly separated from the transfer paper 20. Next, the toner attached to the transfer paper 20 is fixed by the fixing roller 24a, and the fixed transfer paper 20 is discharged to the paper discharge tray 26 by the paper discharge roller 25. Thereafter, at the same time that the transfer paper 20 leaves the endless belt 13, the upstream roller 11, the downstream roller 12, and the pressure roller 14 stop, and while they are stopped, the second transfer paper 20 of the paper feed cassette 19 is transferred to the paper feed roller 21. Pressure roller 14
and the endless belt 13. Thereafter, the second sheet of transfer paper 20 is transported and transferred and fixed in the same way as the first sheet, and the above-described operations are repeated until the number of sheets reaches the end, and the repeat is completed.

As described above, in this embodiment, unlike the conventional electrophotographic transfer conveyance unit shown in FIG. 5, there is no need to separately provide a pair of registration rollers, and the conveyance unit can be integrated. Furthermore, by eliminating the registration roller, the factors that cause linear velocity errors are reduced. As a result,
The structure of the conveyance unit is simplified, and it is possible to prevent distortion, blurring, etc. from occurring in the transferred image.

(Effects) According to the present invention, the pressure roller presses the upstream roller via the endless belt, and the endless belt contacts the photoreceptor drum at the same time as the upstream roller is driven. It is possible to eliminate the registration rollers that keep the paper on standby, and to reduce the causes of linear velocity errors without integrating the conveyance unit.

Therefore, it is possible to simplify the configuration of the transport unit and prevent distortion, blurring, etc. of the transferred image.

[Brief explanation of the drawing]

1 to 4 are diagrams showing an embodiment of a transfer conveyance unit for electrophotography according to the present invention, with FIG. 1 being a configuration diagram thereof, and FIG. FIG. 3.4 is a block diagram for explaining its operation, and FIG. 5 is a block diagram of a copying machine including a conventional transfer conveyance unit for electrophotography. 11... Upstream roller, 12... Downstream roller, 13... Endless belt, 14... Press roller, 15... Photosensitive Body drum, I6...Contact/separation roller, Fig. 1 Fig. 2

Claims (1)

[Claims] An upstream roller that is rotated appropriately at a predetermined timing, a downstream roller that is parallel to the axis of the upstream roller and spaced apart from the upstream roller by a predetermined distance, and an endless belt that is stretched around the upstream roller and the downstream roller. , a pressure roller located above the upstream roller and pressing the upstream roller via the endless belt, a photoreceptor drum located above the endless belt and driven to rotate, and a downstream roller and the photoreceptor drum. a contact/separator roller that is located between and can move in the vertical direction and presses into contact with the lower surface of the upper side of the endless belt;
An electrophotographic device, characterized in that it is provided with an operation means for moving the contact/separation roller upward when the upstream roller is driven to bring the endless belt into contact with the photoreceptor drum being rotated. transfer conveyance unit.