JPH0772682A - Both-side image forming device - Google Patents

Abstract

PURPOSE:To turn a transfer material upside down immediately after an image is transferred on one surface, in a single feeding process and to transfer the image on the other surface. CONSTITUTION:This both-side image forming device is constituted so that a color toner image on the periphery formed by superimposing by several rotation of a photosensitive belt 10 and image exposing and developing actions taken in accordance with the rotations is transferred on the rear surface of a recording paper P fed by a feeding cassette 50 by a transfer unit 22A, the recording paper P is stuck/wound/held on a transfer holder 6 rotated counterclockwise, by making an image surface outside and a successively formed color toner image on the periphery of the photosensitive belt 10 is transferred on the surface of the recording paper P separated/carried from the transfer holder 60 whose rotation is changed clockwise by a transfer unit 22B, to transfer the images on both surfaces and simultaneously fix/record the images by the press- contacting and heating of the thermal rollers 81 and 82 of a fixing unit 80.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-sided image forming apparatus for recording a color image by superposing a single color toner image on an image forming body to form a color toner image and transferring the color toner image to the front and back sides of a transfer material. Regarding

[0002]

2. Description of the Related Art A transfer material on which a toner image is transferred and fixed by a double-sided paper feeding unit (ADU) is re-fed to form a toner image on the opposite transfer material surface, that is, an image is recorded on both surfaces of the transfer material. Although a double-sided image forming apparatus has already been provided, the ADU requires a large-sized apparatus, a long transfer distance for the transfer material, and two heating and pressure-bonding operations for image fixing. Therefore, it is inevitable that the second copy is apt to cause transfer blanks and wrinkles on the paper and deteriorates the quality of the copy.

In place of this ADU, a transfer holder capable of switching between normal and reverse rotation is built in, and two image transfer areas, a first and a second image transfer area, are provided in front of and behind the transfer holder, and an image is formed on one side in the first transfer area. A method of transferring an image on the back surface of the transfer material by feeding the transferred transfer material to the second transfer area by reversing the front and back by the forward rotation of the transfer holding body and the subsequent reverse rotation, and fixing both surfaces at the same time. In this regard, Japanese Patent Laid-Open No. 60-159
A proposal according to Japanese Patent No. 760 is also disclosed.

[0004]

However, the above-mentioned proposal requires a complicated mechanism and a highly accurate control means for forming and transferring a color toner image, and it is difficult to provide the apparatus at a low price.

As a result of solving and improving this point, the present invention provides
It is an object of the present invention to provide a double-sided image forming apparatus capable of recording a color image at a high speed by superposing a single color image as well as a single color image by an extremely simple mechanism and process.

[0006]

The above object is to provide a double-sided image forming apparatus for transferring a color toner image formed by superposing on the image forming body to the front and back sides of a transfer material by rotating the image forming body a plurality of times. A color toner image corresponding to the images to be recorded on the front and back of the transfer material is continuously formed on the image forming body,
A double-sided image forming apparatus characterized by continuously transferring the color toner image to the front and back of the transfer material by switching forward and reverse of the transfer material of the transfer holding member and attracting the transfer material, and a plurality of times of the image forming body. In a double-sided image forming apparatus that transfers the color toner images formed by superimposing on the image forming body to the front and back sides of the transfer material by rotating the plurality of image forming bodies, a plurality of images corresponding to the images to be recorded on the front and back sides of the transfer material are formed on the image forming body. A double-sided image characterized in that a color toner image is continuously formed, and the color toner image is transferred in parallel to the front and back surfaces of the transfer material by switching the forward / reverse rotation of the transfer holding member and the adsorption action to a plurality of transfer materials. Achieved by the forming device.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a double-sided image forming apparatus according to the present invention will be described with reference to FIGS.

1 and 2 show a first embodiment, in which 10 is a flexible photoconductor belt as an image forming body,
The drive roller 11 and the driven rollers 12 and 13 are stretched, and the tension roller 14 urges the tension roller 14 into a tensioned state, which is circulated clockwise by the power of the drive roller 11 and conveyed.

A laser writing system unit 30 receives a color signal output from a separate image reading apparatus, and a laser beam generated by a semiconductor laser (not shown) is rotated by a drive motor 31 by a polygon mirror 32. It is rotated and scanned, and the optical path is bent by the mirrors 34 and 35 via the fθ lens 33 and projected onto the peripheral surface of the photoreceptor belt 10 to which electric charges have been previously applied by the charger 21 to form a bright line.

A developing unit 40 includes developing units 41, 42, 43 and 44 for containing yellow (Y), magenta (M), cyan (C) and black (BK) developers, respectively. Are sequentially arranged and loaded in series from the upstream side of the conveyance.

When the scanning by the laser writing system unit 30 is started, the laser beam is detected by the index sensor, the modulation of the beam by the first color signal is started, and the modulated beam is moved around the photosensitive belt 10. Scan over the surface. Therefore, a latent image corresponding to the first color is formed on the peripheral surface of the photosensitive belt 10 by the main scanning by the laser beam and the sub-scanning by the conveyance of the photosensitive belt 10.

The latent image is reversely developed in a non-contact state by the developing sleeve 41A of the developing device 41 containing the yellow (Y) developer, and the yellow (Y) toner is applied to the peripheral surface of the photosensitive belt 10. An image is formed. The obtained toner image passes under the blade 71 of the cleaning device 70, which is separated from the peripheral surface of the photoconductor belt 10, and makes one round to enter the next toner image forming cycle.

That is, the photoconductor belt 10 on which the yellow (Y) toner image is formed is recharged by the charger 21 in the second lap, and then is output from the signal processing unit.
Signal is input to the laser writing system unit 30 and writing is performed on the peripheral surface of the photoconductor belt 10 to form a latent image as in the case of the first color signal described above. This latent image is reversal-developed in the same non-contact state by the developing device 42 containing a magenta (M) developer as the second color.

The magenta (M) toner image thus obtained is formed by being superposed on the yellow (Y) toner image, and the third and fourth rotations of the photosensitive belt 10 are performed in the third and fourth rotations. The latent images formed by the color signals are superposed as cyan (C) and black (BK) toner images by the developing device 43 and the developing device 44 which contain cyan (C) and black (BK) developers, respectively. Formed. Each developing sleeve 41A, 42A, 43A of each developing device
And 44A, a DC or further AC bias is applied at the time of development, non-contact development with a one-component or two-component developer is carried out, and the photoreceptor belt 10 whose base is grounded
Is developed so as not to contact the developer layer.

The color toner image thus formed on the photoconductor belt 10 is conveyed to the first transfer area constituted by the transfer device 22A. On the other hand, in parallel with the formation of the color toner image, the carry-out roller 51 of the paper feed cassette 50 is actuated and the recording paper P which is a transfer material.
Is carried out and is fed to the first transfer area in synchronization with the conveyance of the color toner image by the registration action of the paper feed roller 52. The color toner image is transferred to the back side of the recording paper P by the transfer device 22A, and immediately after that, the charge is removed by the charge remover 23A to weaken the adhesion to the peripheral surface of the photosensitive belt 10.

Recording paper P having a color toner image transferred on its back surface
Is further moved together with the photoconductor belt 10 and is conveyed to the peripheral surface portion of the transfer holder 60.

The transfer holder 60 comprises a mesh drum 61 having a large number of fine holes on the outer peripheral surface thereof, a holding member 62 radially partitioned inside the mesh drum 61, and an intake pipe 63 having a large number of intake holes on the peripheral surface. The suction pipe 63 is driven to rotate forward and backward as a unit, and a vacuum device (not shown) connected to the suction pipe 63 is actuated to adsorb and wind the recording paper P on the peripheral surface of the mesh drum 61. It can be held.

The transfer holder 60 has an outer peripheral length slightly longer than the longest recording paper P used, and its outer peripheral surface is biased toward the contact roller 15 side as shown in FIG.
It is possible to switch between a position in contact with the peripheral surface of 10 and a position separated from each other as shown in FIG.

When the double-sided copy mode is selected, the recording paper P
In the process in which the color toner image is transferred to the back surface of the transfer belt 60, the transfer holder 60 is in the position shown in FIG. Is rotating.

Therefore, the recording paper P is separated from the peripheral surface of the photoconductor belt 10 and wound around the outer peripheral surface of the transfer holder 60 with the transfer surface facing outward, and when the transfer holder 60 is in the state shown in FIG. As shown in (1), the position is changed and the photosensitive belt 10 is separated from the peripheral surface of the photoconductor belt 10 and temporarily stands by.

The photosensitive belt 10 from which the recording paper P has been separated from the one peripheral surface is further conveyed and further cleaned by the blade 71 of the cleaning device 70 which is switched to the pressed state to remove the residual toner, and is again charged by the charger 21. The laser writing system unit 30 and the developing unit which have been charged and have been described above.
A new color toner image is formed by the image forming process of 40.

The new color toner image is conveyed to the second transfer area formed by the transfer device 22B by passing through the first transfer area in which the operation is stopped.

On the other hand, in parallel with this, the transfer holder 60 starts to rotate in the reverse direction, that is, to rotate clockwise, and the recording paper P is peeled from the end portion by the movement of the separation claw 53 to the pressure contact position, and the photosensitive belt 10 is moved. And the sheet is fed to the second transfer area in synchronization with the conveyance of the color toner image.

As a result, the recording paper P is transferred to the back side thereof, that is, the side opposite to the transfer surface of the previous color toner image, the color toner image formed subsequently is transferred, and the charge is removed by the subsequent charge eliminator 23B and the driven roller 13 is discharged. Photosensitive belt using curvature 10
Separated from the outer surface of.

In this way, the recording paper P on which the color toner images have been transferred to both the front and back sides is conveyed to the fixing device 80 while being floated by the air conveying device 54, and the toners on both sides are simultaneously conveyed by the nip conveyance of the heat rollers 81 and 82. It is fused and discharged onto the discharge tray 90 via the discharge roller 55, and the double-sided copy cycle is completed.

FIG. 3 is a time chart of the main process of the image forming section in the above-mentioned copy cycle, in which Y, M, and
The color toner image B formed in the order of C and BK is first transferred to the back surface of the recording paper P at once, and the color toner image A formed in the order of Y, M, C, and BK by the next four rotations is reversed. It is transferred to the surface of the recording paper P. Here, A is an image to be recorded on the front surface of the recording paper P, and B is an image to be recorded on the opposite back surface.

When the one-sided copy of only one side is selected, the transfer holder 60 is fixed at the position shown in FIG. 2, and the recording paper P is operated by the transfer device 22A in the first transfer area. To transfer the toner image, and then in the second transfer area, the static eliminator
The charge is removed by 23B, and the recording paper P is separated and conveyed to the fixing device 80.

When single-sided copying on the back side only is selected, the transfer holder 60 is in the position shown in FIG. 1 and rotates counterclockwise to transfer the color toner image to the back side of the recording paper P. Is adsorbed and wound, and is then separated from the position shown in FIG. 2 and is rotated in reverse and conveyed straight forward to be passed through the second transfer area and conveyed to the fixing device 80.

Further, when the screen size of the color toner image is small and a plurality of recording papers P can be held on the transfer holder 60, a plurality of color toner images are formed side by side on both surfaces of the recording paper P and transferred one after another. You can also do it. FIG. 4 shows a time chart in the case where two sheets of recording paper P can be held on the transfer holder 60 and two color toner images and two sheets are formed on both sides. Image exposure of the image formed on each side The transfer is continuously performed on the two images. Here, indicates the order of the recording paper P which is fixed on both sides and outputted.

When the two images are different, the image order is reversed on the front and back sides of the recording paper P. Therefore, as shown in FIG. 4, the order of image reading may be changed or obtained for the front and back sides. Measures such as changing the output order of the image data and outputting the image data will be taken. By doing so, the image recording speed can be substantially doubled.

Further, the images on the front and back of one original are recorded on the recording paper P.
5 in parallel on the back side or the same side of the front side of FIG.
It is also possible to perform double-sided recording as shown in (a).

In this case, as shown in the time chart of FIG. 5B, image exposure is performed for each color on the back of the second document and then the image on the front side, and after transfer, the recording paper P is transferred to the transfer holder 60. And the color toner images A on both sides of the first original and the second sheet on the back of the first original by reversing the transfer holder 60. The color toner images B on both the front and back sides of the document are transferred.

The above-described functions such as double-sided copying or single-sided copying, singular copying or simultaneous copying of plural sheets, and replacement of the copy order are for detecting the image size.
This can be realized by the configuration of the control circuit for controlling the copy process and its switching, and the simultaneous copying of a large number of sheets can be efficiently performed by the proposal disclosed in Japanese Patent Laid-Open No. 1-230074.

Since FIG. 6 shows the second embodiment, members having the same functions as those of the apparatus according to the first embodiment described above are indicated by common reference numerals.

The apparatus of this embodiment is a belt-shaped intermediate transfer member 10.
0 is provided, and a color toner image is formed by superimposing the monochromatic toner image formed on the photoconductor belt 10 on the outer peripheral surface of the intermediate transfer member 100.

The intermediate transfer member 100 is stretched between a driving roller 101 and a driven roller 102, is interposed between the photosensitive belt 10 and the transfer holding member 60, and has an outer peripheral surface in contact with both of them. The power of the driving roller 101 circulates in the clockwise direction in synchronization with the peripheral speed and conveys.

Further, the transfer devices 22A and 22B are both arranged so as to face the outer circumference of the intermediate transfer member 100, and respectively form first and second transfer areas.

Each monochromatic toner image formed on the peripheral surface of the photoconductor belt 10 by image exposure and development is transferred to the peripheral surface of the intermediate transfer member 100 each time it is formed, and formed into a color toner image by superposition. It

This color toner image is transferred to the back surface of the recording paper P which is fed synchronously by the transfer device 22A, and the transferred recording paper P is weakened in adhesion by the static eliminator 23A and transferred to the transfer holder 60. And is separated from the intermediate transfer member 100 by being wrapped around by the adsorption action of.

The intermediate transfer body 100 from which the recording paper P has been separated removes residual toner and is cleaned by the blade 71A of the cleaning device 70A which has turned into a pressure contact state to form the next color toner image.

During this time, the transfer body holder 60 around which the recording paper P is wound is held in a stationary state at a position separated from the intermediate transfer body 100, and in synchronization with the conveyance of the next color toner image on the intermediate transfer body 100. In reverse, the transfer paper P is fed to the second transfer area by pressing the separation claw 53, and the next color toner image is transferred to the surface by the transfer device 22B.

[0042]

According to the present invention, color images corresponding to the front and back sides of a transfer material are continuously transferred to each other without using a double-sided sheet feeding device, and both images are simultaneously fixed by one fixing operation. As a result, it is possible to provide a double-sided image forming apparatus that is excellent in practicability, as a result of which the copy speed is improved and the deformation of the paper surface due to fixing is eliminated.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram (part 1) of a double-sided image forming apparatus according to a first embodiment.

FIG. 2 is a sectional configuration diagram (part 2) of the double-sided image forming apparatus according to the first embodiment.

FIG. 3 is a time chart showing an example (first) of image formation by the apparatus.

FIG. 4 is a time chart showing an image forming example (second) by the apparatus.

FIG. 5A is an explanatory diagram of an example in which images on the front and back sides of a double-sided original are recorded in parallel on one side of a recording sheet. (B) is a time chart showing an image forming example (third) by the apparatus.

FIG. 6 is a sectional configuration diagram of a double-sided image forming apparatus according to a second embodiment.

[Explanation of symbols]

 10 Photoconductor belt 11, 101 Drive roller 15 Contact roller 21 Charger 22A, 22B Transfer device 23A, 23B Static eliminator 30 Laser writing system unit 31 Drive motor 32 Polygon mirror 33 fθ lens 34, 35 Mirror 40 Development unit 41, 42 , 43, 44 Developing device 41A, 42A, 43A, 44A Developing sleeve 50 Paper feeding cassette 52 Paper feeding roller 53 Separation claw 54 Air conveying device 55 Paper discharging roller 60 Transfer holder 61 Mesh drum 62 Holding member 63 Air intake pipe 70, 70A Cleaning device 71 Blade 80 Fixing device 81, 82 Heat roller 100 Intermediate transfer member P Recording paper

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03G 15/01 114 Z

Claims (4)

[Claims] 1. A double-sided image forming apparatus for transferring a color toner image formed by superposing on the image forming body by rotating the image forming body a plurality of times to the front and back sides of the transfer material. Color toner images corresponding to the images to be recorded on the front and back sides of the transfer medium are continuously formed, and the color toner images are continuously transferred to the front and back sides of the transfer material by switching the transfer carrier between forward and reverse and adsorbing the transfer material. A double-sided image forming apparatus characterized by: 2. The double-sided image forming apparatus according to claim 1, wherein each of the color toner images transferred to the front and back of the transfer material is composed of a plurality of color toner images. 3. A double-sided image forming apparatus for transferring a color toner image formed by superimposing on the image forming body by rotating the image forming body a plurality of times on the front and back sides of the transfer material. A plurality of color toner images corresponding to the images to be recorded on the front and back sides of the transfer material are continuously formed, and the color toner images are arranged in parallel on the front and back surfaces of the transfer material by switching the forward and reverse rotations of the transfer holder and the adsorption action on the plurality of transfer materials. A double-sided image forming apparatus, which is characterized in that it is transferred. 4. The double-sided image forming apparatus according to claim 3, wherein the double-sided image formation is performed according to a screen size.