JPS63298255A - Double-sides copy making method - Google Patents

Abstract

PURPOSE:To simply obtain a double-sided copy at a low cost by transferring an image on a photosensitive drum to transfer paper on a transfer carrying belt, and simultaneously, transferring an image on the transfer carrying belt to the reverse side of this transfer paper. CONSTITUTION:Image forming units 16-22 having a photosensitive drum 100 are arranged on the periphery of a transfer carrying belt, and an image of one face is formed on the photosensitive drum 100 so as to become a mirror image when it has been transferred onto the transfer carrying belt 2, transferred onto the transfer carrying belt 2, the polarity of a transfer toner image is inverted by a corona discharge, thereafter, transfer paper is superposed on the transfer image. Subsequently, an image of the other face is formed on the photosensitive drum 100 as an image of a usual transfer type transferred to the transfer paper on the transfer carrying belt 2, and simultaneously, the image on the transfer carrying belt 2 is transferred to the reverse side of the transfer paper, by which the double-sided copy is realized. In such a way, the double-sided copy is obtained by a simple constitution without inverting the transfer paper.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field The present invention relates to a double-sided copy making method applied to fields such as digital copying machines, facsimiles, and printers.

(2) Prior Art The conventional technique known as this type of double-sided copy making method is to copy one side of the original image to be double-sided copied onto one side of transfer paper, then flip the transfer paper, and then This method copies the other side of the image onto one side to make a double-sided copy, which requires a mechanism to reverse the transfer paper, which inevitably complicates the configuration of the copying machine and can lead to accidents such as jams. In addition to being a concern, it also has the disadvantage of being generally expensive.

(3) Purpose An object of the present invention is to eliminate the drawbacks of the conventional methods described above and to provide a method for obtaining double-sided copies with a simple structure without reversing the transfer paper.

(4) Structure In order to achieve the above object, the present invention arranges an image forming unit having a photosensitive drum around a transfer conveyance belt, and transfers an image on one side of an image to be double-sided copied to the transfer belt. The toner image is formed on the photoreceptor drum so that it becomes a mirror image when transferred onto a conveyor belt, the image on this photoreceptor drum is transferred onto the transfer conveyor belt, and the polarity of this transferred toner image is reversed by corona discharge. After that, transfer paper is placed on top of this transferred image, and the image on the other side of the image to be double-sided copied is formed on the photoreceptor drum as a normal transfer type image, and this image is transferred onto the transfer conveyor belt. This is characterized in that a double-sided copy is produced by transferring the image onto a transfer paper and simultaneously transferring the image on the transfer conveyor belt to the back side of the transfer paper.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

This embodiment shows a four-drum type digital color copying machine, and in the drawing, reference numeral 2 indicates a transfer conveyance belt, which is wound between pulleys 4 and 6. A driving force is applied to one of these pulleys, and the transfer conveyance belt 2 is rotated in the direction of the arrow by this driving force. Further, a tension pulley 8 is provided at an intermediate position of the belt 2.

The transfer conveyor belt 2 is made of a dielectric material, and around it is a belt static eliminator 10. Belt cleaning device @12, paper feed section 141 image forming unit 16,, 18.20.22
A paper discharge guide 24 and the like are arranged.

Among the above-mentioned members, the belt cleaning device 12 can be moved toward and away from the transfer conveyance belt 2 by appropriate means as shown by the arrows. In addition, each image forming unit 16.18.
20 and 22 each have a photoreceptor drum 100, and a charging device 102, a developing device 104, and a cleaning device 105 are provided around the photosensitive drum 100. A transfer charger 108 is provided inside the transfer conveyance belt 2 facing each photoreceptor drum 100.
are placed respectively.

Note that the image forming unit 16 is yellow, the image forming unit 18 is magenta, the image forming unit 20 is cyan,
The image forming unit 22 is for exclusively forming images of each color of black, and each developing device 104 accommodates a developer of each color.

Further, NiHA laser optical systems 116, 118, and 120° 122 are respectively disposed above the photosensitive drum 100 between the charger 102 and the developer 104 in correspondence with the image forming units.

Each of these laser optical systems reads an image read by a document image reading device (not shown).

A part of the image processor (not shown) performs image processing such as color correction, gradation correction (UCR) (undercolor removal), and horizontal inversion, and generates a laser beam using each signal component of yellow, magenta, cyan, and black. It outputs and exposes the photoreceptor. The light source is not limited to lasers, but may also be LEDs, LCDs, LCSs, etc.

In such a copying machine, double-sided copying is performed in the following steps.

First, at the same time as the copying operation starts, each image forming unit 16.
The photoreceptor drums 100 on 18.20.22 each begin to rotate, and static electricity removal and cleaning are performed. At the same time, the transfer conveyance belt 2 also starts rotating following the rotation of the photosensitive drum 100, and after being neutralized by the belt static eliminator 10, it is cleaned by the belt cleaning device 12, and one side of the image to be double-sided copied is removed. A process of creating an image of the surface (hereinafter referred to as the first image) begins. Note that in the above-mentioned cleaning position, the belt cleaning device 12 is in contact with the transfer conveyance belt 2.

The first image is read by a document image reading device (not shown), and is processed by an image processor to
Image processing is performed for each magenta, cyan, and black signal component, and the photoreceptor drum 10 of each image forming unit
A toner image of each color component is formed on 0.

Next, as the transfer conveyance belt 2 rotates, the toner images on each photoreceptor drum 100 are sequentially transferred by each transfer charger 108 to the same position on the transfer conveyance belt 2 while being aligned.

Therefore, during transfer, the image forming unit or the transfer conveyance belt is moved by appropriate means so that the transfer conveyance belt 2 of the photosensitive drum 10G approaches.

At this time, the first image on the transfer conveyance belt 2 must be a mirror image, so it is processed by an image processor so that it becomes a normal image on the photoreceptor drum 100 before image exposure is performed. shall be provided.

When the first image is thus transferred onto the transfer conveyance belt 2, the image on the other side of the image to be double-sided copied (hereinafter referred to as the second image) is read and image processed.

Note that this second image reading process is performed following the first image process, and is stored in memory.Following the transfer of the first image onto the transfer conveyance belt 2, the second image reading process is performed as described below. It can also be performed as an image forming process.

Now, when the first image on the transfer conveyance belt 2 passes through the belt static eliminator lO, this belt static eliminator has a function of reversing the toner polarity of the first image by corona discharge.
This causes the first image to have its polarity reversed before passing through the belt cleaning device 12.

However, when passing through this belt cleaning device 12, the cleaning device [12 is set in advance to move away from the belt at a certain timing, so that the first image reaches the paper feed section 14 without being cleaned.

A transfer paper (not shown) is sent out from the paper feed unit 14 in alignment with the first image on the transfer conveyance belt 2, and is superimposed on the first image.

Thereafter, the transfer paper passes sequentially through each image forming unit 16, 18, 20, 22 together with the belt.

At this time, the images of the yellow, magenta, cyan, and black components constituting the second image are sequentially aligned and transferred onto the transfer paper.

Here, the second image must be a normal image on the transfer paper, and therefore the second image must be a normal image on the photosensitive drum 100 before being transferred to the transfer paper.
The image above is formed by image processing so that it becomes a mirror image.

In this way, the second image is transferred onto the top surface of the transfer paper, and at the same time, the first toner image on the transfer conveyance belt 2, whose polarity is reversed, is transferred onto the back surface of the transfer paper. Thereafter, the transfer paper is separated from the belt and passes through the paper ejection guide 24 to the fixing device 2.
It reaches 6.

At this stage, the second image is on the top side of the transfer paper, and the first image is on the back side.
image is formed. Then, the transfer paper is subjected to theorem processing by passing through the fixing device 26, and a double-sided copy is obtained.

On the other hand, the transfer conveyance belt 2 after separating the transfer paper is neutralized by the belt static eliminator lO before cleaning, and residual toner is removed when it passes through the belt cleaning device 12 which moves to a state close to the belt, and the remaining toner is removed during the copying process. The process is completed and preparations are made for the next image formation.

In this way, a double-sided copy can be obtained by simply passing the transfer paper over the transfer conveyance belt 2.

In the above embodiment, a four-drum type digital color copying machine was shown, but the invention is not limited to this, and the present invention can also be applied to a one-drum type black and white digital copying machine, a two-drum type digital copying machine, etc. can.

(5) Effects The present invention is as described above, and has the excellent effect that double-sided copies can be easily obtained at low cost without requiring any complicated structure such as a transfer paper reversing mechanism.

[Brief explanation of the drawing]

The drawing is a schematic diagram of a copying machine showing an embodiment of the present invention. 2... Transfer conveyance belt 16.18, 20.22... Image forming unit 100
...Photoreceptor drum

Claims (1)

[Claims] 1. An image forming unit having a photosensitive drum is disposed around the transfer conveyance belt, and the image on one side of the image to be double-sided copied becomes a mirror image when transferred onto the transfer conveyance belt. The image is formed on a photoreceptor drum, and the image on this photoreceptor drum is transferred onto a transfer conveyor belt.
After reversing the polarity of this transferred toner image by corona discharge, transfer paper is placed on top of this transferred image, and the image on the other side of the image to be double-sided copied is used as a normal transfer type image on the photoreceptor drum. A double-sided copy making method characterized in that a double-sided copy is produced by transferring the image onto a transfer paper on a transfer conveyance belt and simultaneously transferring the image on the transfer conveyance belt to the back side of the transfer paper. .