JPH1048893A - Both-side image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize bookbinding by recording the respective image of the front and rear sides of plural originals on both sides of recording paper in page order. SOLUTION: Each image data of the front and rear of the plural originals is compressed and is stored in an image memory 82, and in accordance with bookbinding form, for instance, in the case of half-folded format, each image data is restored 83 to a size equivalent to the half page portion of the recording paper by designation 88, and furthermore is sorted into a front output memory 85A and a rear output memory 85B by a selector (I) 84 and is stored. Each image data of the front and rear is alternately outputted to a printer part in a specified order by the selector (II) 86 at the time of image-forming, so that the images of the front and rear of an original are recorded on each page of the recording paper in a state of being immediately bound in the same page order as the original at the time of image-reading.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to copying in which a charging means, an image exposing means and a developing means are arranged around an image carrier to transfer and fix a toner image formed on the image carrier to both sides of a transfer material. The present invention relates to an electrophotographic double-sided image forming apparatus such as a machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art Conventionally, in double-sided copying, an image on one side formed on an image carrier is transferred and fixed on a transfer material, and this is temporarily stored in a two-sided reversing paper feeder, and the image bearing is again performed. A method has been adopted in which a transfer material is fed from a double-sided reversing sheet feeder in synchronization with an image formed on the body, and an image on the other surface is transferred and fixed onto the transfer material.

In this double-sided copying apparatus, as described above, the transfer of the transfer material, such as feeding to the two-sided reversing paper feeder and passing through the fixing device twice, is performed, so that the reliability of transfer of the transfer material is low. And so on. In contrast, JP-B-49-37538 and JP-B-54-28740.
JP, JP-A-1-44457, JP-A-4-21
Japanese Patent Application Laid-Open No. 4576/1999 proposes a method in which toner images are formed on both surfaces of a transfer material and then fixed once.

[0004]

As is well known, an image forming apparatus for forming a two-sided image using the above-described two-sided reversing sheet feeder requires a long processing distance for transferring a transfer material, so that it takes much processing time for copying. Further, since the transfer material is heated twice for fixing the image, there is a problem that paper quality is damaged.

The inventor of the present invention has previously provided two image bearing means and two transfer means to transfer a toner image to both sides of a transfer material and to simultaneously fix the transfer material having toner images on both sides. A study was made on an apparatus that performs double-sided copying, and a double-sided image forming apparatus capable of significantly increasing the processing speed of double-sided copying was realized.

According to the present invention, in binding a transfer material on which an image is recorded, a double-sided image forming apparatus capable of recording an image corresponding to the bookbinding mode on both front and back sides of the transfer material in the order of pages of the original image. The purpose is to provide.

[0007]

An object of the present invention is to provide a first image carrying means for carrying a toner image formed by a toner image forming means, and a transfer of the toner image carried by the first image carrying means. A second image holding means for holding the transferred toner image on the surface, a first transfer means for transferring the toner image carried on the first image holding means to a surface of a transfer material, A two-sided image having a second transfer unit for transferring the toner image carried by the second image holding unit to the back surface of the transfer material, and a fixing unit for fixing the toner images transferred to both surfaces of the transfer material In the forming apparatus, a control system for forming a plurality of images on the same surface of the transfer material and allocating images to both corresponding front and back surfaces of each page of the transfer material according to the specification of the bookbinding mode. Double-sided image type characterized by having An apparatus (an invention according to claim 1), a first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried by the first image carrying means is transferred and transferred. A second image carrying means for carrying the toner image formed on the surface thereof, a first transferring means for transferring the toner image carried on the first image carrying means to a surface of a transfer material, Double-sided image forming apparatus, comprising: a second transfer unit that transfers a toner image carried by the image carrying unit to the back surface of the transfer material; and a fixing unit that fixes the toner images transferred to both surfaces of the transfer material. In the above, it is possible to form a plurality of images on the same surface of the transfer material, specify the transfer material, and feed the transfer material according to the specification, corresponding to the front and back surfaces of each page of the transfer material A control system for assigning images to both sides is provided. It is achieved by a double-sided image forming apparatus according to claim (invention according to claim 4).

[0008]

Embodiments of the present invention will be described below. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope. In the following description of the embodiment, when a color toner image is transferred to a transfer material, an image to be transferred to a surface of the transfer material facing the image carrier in the transfer area (referred to as a surface of the transfer material) will be described. The front image and the image transferred to the other surface of the transfer material (called the back surface of the transfer material) are called the back surface image.

An image forming process and each mechanism of an embodiment of the image forming apparatus according to the present invention will be described with reference to the color image forming apparatus shown in FIGS. FIG. 1 is a sectional configuration diagram of a color image forming apparatus showing one embodiment of the present invention, FIG. 2 is a side sectional view of the image carrier of FIG.
FIG. 3 is a diagram illustrating a state where toner images are formed on both surfaces.

The photosensitive drum 10 serving as an image carrier has a cylindrical base formed of, for example, a transparent member such as optical glass or transparent acrylic resin provided inside, and a transparent conductive layer,
A photosensitive layer such as an a-Si layer or an organic photosensitive layer (OPC) is formed on the outer periphery of the substrate, and is rotated clockwise as shown by an arrow in FIG. 1 in a grounded state.

As shown in FIG. 2, the photosensitive drum 10 has flange members 10a and 10b at both ends for engaging and fixing it.
Is rotatably supported by bearings 110a and 110b fitted into flange members 10a and 10b at both ends on a drum shaft 110 erected and fixed to the apparatus main body, and a gear G integrated with the flange member 10b is rotatably supported. The apparatus is driven at a constant speed in a predetermined direction by being driven by meshing with a drive gear on the apparatus body side.

Scorotron charger 11 as charging means
Is used in an image forming process of each color of yellow (Y), magenta (M), cyan (C) and black (K), and is exposed in a direction orthogonal to a moving direction of the photosensitive drum 10 as an image carrier. It is installed facing the body drum 10,
A charging operation is performed by a control grid maintained at a predetermined potential with respect to the above-described organic photoconductor layer of the photoconductor drum 10 and a corona discharge having the same polarity as the toner using, for example, a sawtooth electrode as the discharge electrode 11a (this embodiment). , A uniform potential is applied to the photosensitive drum 10. Other wire electrodes can be used as the discharge electrode 11a.

The exposure unit 12 as an image exposure means for each color moves an exposure position on the photosensitive drum 10 between a discharge electrode 11a of the scorotron charger 11 and a development position of the developing device 13 by a developing sleeve 131. Is provided on the upstream side in the rotation direction of the photosensitive drum.

The exposure unit 12 is a linear exposure element 12a in which a plurality of LEDs (light emitting diodes) as image exposure light emitting elements arranged in the main scanning direction in parallel with the axis of the photosensitive drum 10 are arranged in an array. And a SELFOC lens 12b as an equal-magnification imaging element are configured as an exposure unit attached to a holder (not shown). Holding member 20
The exposure unit 12, the uniform exposure unit 12c, and the simultaneous transfer exposure unit 12d for each color are attached to the
Of the substrate. Image data of each color read by a separate image reading device and stored in the memory are sequentially read from the memory, subjected to image processing according to the present invention, newly edited, and images of the back surface and the front surface suitable for bookbinding. The data is input to the exposure unit 12 for each color as an electric signal.

As the exposure element, a plurality of light-emitting elements such as FL (phosphor light emission), EL (electroluminescence), PL (plasma discharge), and LED (light-emitting diode) are arranged in an array. The light emission wavelength of the light emitting element used in this embodiment is generally high when the image exposure is performed from the outside.
A range of 0 to 900 nm is used. However, since the image is exposed from the back side, the color toner does not have sufficient translucency.
The wavelength may be m.

A developing unit 13 provided in accordance with the color sequence in which an image is formed and the rotating photosensitive drum is provided in accordance with the color sequence.
In the present embodiment, the developing units 13 of Y and M are on the left side of the photosensitive drum 10 and the developing units 13 of C and K are on the right side of the photosensitive drum 10 with respect to the photosensitive drum 10 of FIG. And the developing casing 1 of the Y and M developing units 13
The scorotron chargers 11 for Y and M are disposed below 38, and the scorotron chargers 11 for C and K are disposed above the developing casing 138 of the C and K developing devices 13.

The developing device 13 as a developing means for each color includes
One-component or two-component developers of yellow (Y), magenta (M), cyan (C) and black (K) are accommodated, respectively, and a predetermined gap is maintained with respect to the peripheral surface of the photosensitive drum 10, respectively. At the developing position, the photosensitive drum 10 rotates in the same direction as the rotating direction of the photosensitive drum 10.
m, a cylindrical developing sleeve 131 made of nonmagnetic stainless steel or aluminum having an outer diameter of 15 to 25 mm.

The developing unit 13 is moved to a predetermined distance from the photosensitive drum 10 by an abutting roller (not shown), for example, 100 μm.
In the developing operation of the developing device 13 for each color, the developing sleeve 131 is used.
A developing bias to which a DC voltage or an AC voltage AC is further applied is applied to the photosensitive drum, a jumping development is performed with a one-component or two-component developer contained in the developing device, and a negatively charged photosensitive member grounds the transparent conductive layer. The same polarity as the toner for the drum 10 (minus polarity in this embodiment)
Is applied, and non-contact reversal development is performed in which toner is adhered to an exposed portion. At this time, the precision of the development interval needs to be about 20 μm or less in order to prevent image unevenness.

The developing device 13 for each color applies a developing bias voltage to the electrostatic latent image on the photosensitive drum 10 formed by the charging by the scorotron charger 11 and the image exposure by the exposure unit 12. (In the present embodiment, the photosensitive drum is negatively charged,
Reversal development is carried out with a negative polarity toner).

The image of the back and front surfaces is read as an original image by an image sensor of an image reading device separate from the present device, and is edited by a computer, and is temporarily converted into image data for each of Y, M, C and K colors. Stored and stored in memory.

When image recording is started, a gear 10G provided on the rear flange 10b of the photosensitive drum 10 is rotated through a driving gear by driving of a photosensitive member driving motor (not shown), and the photosensitive drum 10 is moved in the direction indicated by an arrow in FIG. , And at the same time, the photosensitive drum 10 is charged by the charging action of the Y scorotron charger 11 disposed below the developing casing 138 of the yellow (Y) developing device 13 to the left of the photosensitive drum 10. The application of the potential is started.

After a potential is applied to the photosensitive drum 10, exposure is started by a first color signal, that is, an electric signal corresponding to the Y image data in the Y exposure unit 12, and the surface of the photosensitive drum 10 is exposed by rotational scanning of the drum. An electrostatic latent image corresponding to the Y image of the back side image edited on the layer is formed.

The latent image is reversal-developed by the Y developing device 13 in a state where the developer on the developing sleeve is not in contact with the developer, and a yellow (Y) toner image is formed in accordance with the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is placed on the magenta (M) developing unit 1 on the yellow (Y) toner image and further on the left of the photosensitive drum 10 and above the yellow (Y).
An electric signal corresponding to the second color signal of the M exposure unit 12, that is, the M image data, is applied by the charging action of the magenta (M) scorotron charger 11 disposed below the third developing casing 138. Is performed, and magenta (M) is formed on the yellow (Y) toner image by non-contact reversal development by the M developing unit 13.
Are sequentially superimposed and formed.

By the same process, the developing casing 13 of the developing device 13 for cyan (C) is located on the right side of the photosensitive drum 10.
The cyan (C) toner image corresponding to the third color signal is further obtained by the cyan (C) scorotron charger 11, the exposure unit 12 of C, and the developing unit 13 of C, which are arranged above the photoconductor 8 The black (K) scorotron charger 11, the exposure unit 12, and the developing device 13 are arranged on the right side of the drum 10 and below the developing casing 138 of the black (K) developing device 13 at the lower part of the fourth color by the fourth unit. A black (K) toner image corresponding to the signal is sequentially superposed, and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10 (toner image forming means).

Exposure unit 1 for Y, M, C and K
Exposure of the organic photosensitive layer of the photosensitive drum 10 by 2 is performed from the inside of the drum through the transparent substrate described above. Therefore, the exposure of the images corresponding to the second, third, and fourth color signals is performed without any influence from the previously formed toner image, and the same exposure as the image corresponding to the first color signal is performed. It is possible to form an electrostatic latent image.

By the above-described image forming process, a superimposed color toner image serving as a back surface image is formed on the photosensitive drum 10 (first image carrying means) serving as an image carrier. The transfer roller 14c to which a DC voltage having the opposite polarity (positive polarity in the present embodiment) is applied to the superposed color toner image in the transfer area 14b by the driving roller 14d and the driven roller 1
4e, and is collectively transferred onto a toner image receiving member 14a (second image carrying means) provided in proximity to or in contact with the photosensitive drum 10. At this time, for example, uniform exposure is performed by the simultaneous transfer exposure device 12d using a light emitting diode so that good transfer is performed.

The toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is subjected to static elimination by the image carrier AC static eliminator 16 and then enters the cleaning device 19 or the photosensitive drum 10.
Cleaning blade 19a made of rubber material in contact with
In order to eliminate the history of the photoreceptor up to the previous print, the peripheral surface of the photoreceptor is removed by, for example, exposure by a uniform exposure unit 12c before charging using a light emitting diode, and the charge at the previous print is removed. Is removed and the next color image formation of the front surface image is performed.

The back side image formed on the toner image receiving body 14a is synchronized with the transfer area 14b, and the surface image of the superimposed color toner image is transferred to the photosensitive drum in the same manner as in the above-described color image forming process. 10 is formed. It is necessary to change the image data so that the front side image formed at this time is a mirror image of the back side image formation on the image carrier. Further, since the backside image is once transferred to the second image carrier and then transferred onto the transfer material, the image density of the backside image on the transfer material is lower than that of the frontside image. Therefore, in forming an image, by changing image forming process conditions such as charging, image exposure, and development, the amount of adhesion on the image forming body is increased, and no difference is observed in the final image density on the transfer material. It is performed under the condition setting.

Recording paper P, which is a transfer material, is sent out by a feed roller 15a from a paper feed cassette 15 which is a transfer material storage means, fed by a feed roller 15b, and conveyed to a timing roller 15c.

The recording paper P is driven by the timing roller 15c to form a color toner image of a front surface image carried on the photosensitive drum 10 and a color toner image of a rear surface image carried on the toner image receiver 14a. Are fed to the transfer area 14b in synchronization with the above. At this time, the recording paper P is charged to the same polarity as the toner by a paper charger 14f as a transfer material charging means, is attracted to the toner image receiver 14a, and is fed to the transfer area 14b. By charging the paper with the same polarity as the toner, it is possible to prevent the recording paper P from attracting the toner image on the toner image receiver or the toner image on the image carrier outside the transfer section, thereby preventing the toner image from being disturbed. doing. Further, as the transfer material charging unit, a conductive roller, a brush charger, or the like, which can be brought into contact with and released from the toner image receiver, can be used.

A surface image on the peripheral surface of the photosensitive drum 10 is collectively recorded on a recording paper by a transfer unit 14c as a first transfer unit to which a voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied. It is transferred to the upper surface side (front side) of P. At this time, the back surface image on the peripheral surface of the toner image receiver 14a is not transferred to the recording paper P but exists on the toner image receiver 14a. Next, a backside image on the peripheral surface of the toner image receiving body 14a is collectively recorded by a backside transfer unit 14g as a second transfer unit to which a voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied. The image is transferred to the lower surface (back surface) of the paper P. At the time of transfer by the transfer device 14c, uniform exposure is performed by a simultaneous transfer exposure device 12d using, for example, a light emitting diode, provided inside the photosensitive drum 10 so as to perform good transfer so as to face the transfer device 14c. Is performed.

Since the toner images of the respective colors overlap with each other, it is preferable that the toner in the upper layer and the toner in the lower layer of the toner layer are charged with the same charge amount and the same polarity in order to enable batch transfer. Therefore, in a double-sided image formation in which the polarity of the color toner image formed on the toner image receiving member 14a is inverted by corona charging or the polarity of the color toner image formed on the image carrier is inverted by corona charging, the lower layer is formed. The toner is not sufficiently charged to the same polarity, so that the transfer becomes unfavorable.

The reversal development is repeated on the image carrier, and the color toner images of the same polarity formed by superimposition are collectively transferred to the toner image receiver 14a without changing the polarity, and then the recording paper is changed without changing the polarity. The batch transfer to P is preferable because it contributes to the improvement of the transferability of the backside image formation. Also for the surface image formation, reversal development is repeatedly performed on the image carrier, and the color toner images of the same polarity formed by superimposition are collectively transferred to the recording paper P without changing the polarity. It is preferable because it contributes to improvement of the property.

As described above, in the color image formation, the first transfer means is operated to form a color toner image on the surface of the transfer material by using the above-described front and back surface image forming method. A two-sided image forming method of forming a color toner image on the back surface of the transfer material by operating the second transfer means is preferably employed.

The toner image receiver 14a has a thickness of 0.5-2.
An endless rubber belt of 0 mm, a semiconductive substrate of silicon rubber or urethane rubber having a resistance value of 10 ⁸ to 10 ¹² Ω · cm, and a thickness of 5 to 50 μm as a toner filming prevention layer outside the rubber substrate. And a two-layer structure with fluorine coating. This layer also preferably has a similar semiconductivity. 0.1-0.5 thickness instead of rubber belt base
mm semiconductive polyester, polystyrene, polyethylene, polyethylene terephthalate, or the like can also be used.

The recording paper P on which the color toner images are formed on both sides is discharged by a paper separation AC discharger 14h for separating the transfer material, separated from the toner image receiver 14a, and a heater is provided inside both rollers. The sheet is conveyed to a fixing device 17 as a fixing unit including two rollers.
By applying heat and pressure between the fixing roller 17a and the pressure roller 17b, the toner adhered to the front and back of the recording paper P is fixed, and the recording paper P on which double-sided image recording has been performed is sent by the paper discharge roller 18. And discharged to a tray outside the apparatus.

The toner remaining on the peripheral surface of the toner image receiver 14a after the transfer is brought into contact with and abuts on the toner image receiver 14a provided in a toner image receiver cleaning device 14i as cleaning means for the toner image receiver. It is cleaned by a blade that can be released. The toner remaining on the peripheral surface of the photoconductor drum 10 after the transfer is subjected to static elimination by the image carrier AC static eliminator 16, and then enters a cleaning device 19 or is made of a rubber material that abuts on the photoconductor drum 10. Cleaning device 1 by cleaning blade 19a
9 and is collected by a screw 19b into a waste toner container (not shown). The photosensitive drum 10 from which the residual toner has been removed by the cleaning device 19 is uniformly charged by the Y scorotron charger 11, and enters the next image forming cycle.

By using the above-described method, since the superimposed color toner images are transferred collectively, color shift of the color image on the toner image receiving member, scattering or rubbing of the toner, and the like are less likely to occur, and the image is less deteriorated. A double-sided color image is formed.

The image data of each color of the document input to the color image forming apparatus is read by, for example, an image reading device 50 provided separately from the main body of the apparatus shown in FIG.

In the case of the image reading apparatus 50 described above, the originals D are stacked in page order from the lower side with the front surface facing downward, and the lowermost original D is directed to the transport path 53 by the operation of the discharge belt 51 and the separating roller 52. It is carried out.

The conveyed original document D is retracted to the position shown by the broken line without the guide plate G biased to the position shown by the solid line, and is placed on the transparent platen glass 55 via the transport belt 54. The document is fed, and is temporarily stopped at the document reading position with the back face down.

The back side image of the original D on the platen glass 55, that is, page 2 of the first original, is positioned in a V-shape with a first mirror unit 56 comprising an illumination lamp and a first mirror constituting a scanning optical system. The second mirror unit 57 composed of the second mirror and the third mirror is read by the reading operation at the speed V of the first mirror unit 56 and the moving exposure by the second mirror unit at the speed V / 2 in the same direction. The image is formed on the image sensor CCD by the projection lens L. The back side image formed on the image sensor CCD is stored in the image memory as image data for each color.

When the reading of the back side image is completed in the image reading device 50, the original D is turned upside down through the reversing sheet feeding path 58 by the temporary reverse rotation of the conveying belt 54, and again passed through the conveying path 53 to the conveying belt 54. Through the platen glass 5
5, and is temporarily stopped at the document reading position with the front surface facing downward.

The original D on the platen glass 55 is read from the front side image, that is, page 1 of the first original by the scanning optical system, and stored in the image memory as image data for each color.

Subsequently, in the same manner, each original D
Are read in the order of page 4, page 3, page 6, page 5,..., And the image data is compressed and arranged in the image memory in the order of page 1, page 2, page 3, and page 3. .. Are sequentially stored.

In general double-sided image formation, each image data stored in the image memory is input to a printer unit as an image forming unit of the apparatus through a data output control process shown in FIG.

That is, each image data stored in the image memory 82 is called in the order of page 1, page 2, page 3, page 4, page 5,..., And the compressed image data is restored and the selector ( .. 84), the odd page image data of page 1, page 3, page 5... Is output to the front side output memory 85A, while the even page image data of page 2, page 4, page 6. And divided and sequentially stored in the memory 85B.

Each image data stored in each of the output memories is alternately sent to the exposure unit 12 by the selector (II) 86 in such a manner that the image data on the front and back of each document D precedes the back image data. Is output. In forming the front and back images, image forming conditions such as charging, exposure, and development or transfer conditions are switched.

The back side image formed on the toner image receiver 14a and the front side image formed on the photosensitive drum 10 are the front and back of the first recording paper P fed from the paper feed cassette 15. And the first copy cycle is completed. The recording paper P holding the front side toner image and the back side toner image is fixed by the fixing device 17 and is turned upside down and discharged onto a tray outside the apparatus with the front side down.

For the second and subsequent copies as well, the image data from the back side output memory (85B) is output by outputting the back side image and the image data from the front side output memory (85A). As a result, a front image is formed, and the front image and the back image are respectively transferred to the front and back of each of the second and subsequent recording sheets P fed from the sheet cassette 15. The recording paper P holding the front toner image and the rear toner image is fixed by the fixing device 17, and is stacked in a page order on the recording paper discharged first with the front side down.

On the other hand, in the image reading device 50, the originals D for which the image reading has been completed are stacked on the tray 60 via the discharge rollers 59 by the operation of the transport belt 54, with the front surface facing down, in the order of pages from below. Paper is discharged as follows.

This double-sided image forming apparatus is different from the conventional double-sided image forming method which requires a bent paper feeding system in which fixing is repeated twice. It has the advantage of being able to print on both sides.

(Embodiment 1) The invention according to claims 1 to 3 will be described with reference to FIGS.

The double-sided image forming apparatus of the present invention enables a plurality of images to be formed on the same side of a transfer material, and also corresponds to both sides of the front and back sides of each page of the transfer material according to the specification of the bookbinding mode. Is provided with a control system for allocating images. For example, there is a bookbinding mode such as a half-folding format or a single-binding format, and therefore, a description will be given using an example.

A half-folded bookbinding form as shown in FIG. 6A is employed, and for example, eight originals D are printed on each of the front and back pages of four half-folded sheets S1 to S4 of the recording paper P. When the front and back images are formed in page order, the binding mode of the four half-fold sheets to be created is designated as the binding mode.
When designated by 8, the control unit 80 calls a program corresponding to the above-described bookbinding mode from the memory 89, and the control unit 80 performs data processing according to the program. That is, the control unit 80 reads the sheet S1 from the image memory 82.
1st page, 2nd page and original 8 required for original
The image data of the fifteenth and sixteenth pages of the sheet is called, and each image data is restored to a size that fits within a half page of the recording paper P in consideration of a preset binding margin (image data restoration). 83), and the selector (I) 84 inputs the image data of the second and fifteenth pages to the back surface output memory 85B in a layout in which the binding margin is narrowed. Further, the image data of pages 1 and 16 is input to the front surface output memory 85A in a layout state with the binding margin therebetween. In this way, the image data on the front and back of the sheet S1 is stored in the respective buffer memories on the front and back.
The selector (II) 86 retrieves image data for the back surface from the back surface output memory 85B, performs image processing in the image processing unit 87, and then performs photoprocessing on the photosensitive drum 10 by the printer unit.
A record is made above. Subsequently, the selector (II) 86 calls up image data for the front side from the front side output memory 85A, performs image processing in the image processing section 87, and records on the photosensitive drum 10 by the printer section. The sheet S1 on which the image is recorded is discharged onto the tray with the front side facing down. The image processing unit 87 provides a difference in the amount of color correction and the amount of γ correction between the front image and the back image,
Correction is performed so that the image quality of the front and back sides on the sheet is the same. The increase / decrease of the toner adhesion amount between the front side image and the back side image is determined by the image processing section 87 or the printing section (12).
Done in

Similarly, for the second sheet S2, the control unit 80 stores the image data of pages 3 and 4 of the second original and pages 13 and 14 of the seventh original from the image memory 82. Then, each image data is restored to a predetermined size by the image data restoration 83, and the image data of pages 4 and 13 are allocated by the selector (I) 84 and input to the back surface output memory 85B. The image data of pages 3 and 14 are allocated and input to the front surface output memory 85A. In the selector (II), first, the back side image data is called from the back side output memory 85B to form an image, and subsequently, the front side image data is called from the front side output memory 85A to form an image. The sheet S2 is discharged onto the sheet S1 with the front side facing down.

Similarly, with respect to the third sheet S3, page 5 and page 12 of the original on the front side, page 6 and
An image is formed in a form in which the pages 11 are allocated, and the sheet S3 on which images are recorded on the front and back sides is discharged onto the sheet S2 with the front side down. Further, on the fourth sheet S4, images of pages 7 and 10 of the document, and pages 8 and 9 are recorded on the back side, and are discharged onto the sheet S3 with the front side down.

When the work set in advance by the bookbinding state designation 88 is completed, the sheets S1 to S4 have been discharged onto the tray in the correct order. The bookbinding is completed by bending the sheet inward at the central portion (binding portion) and, if necessary, by gluing the central portion between the sheets with glue or stapling. Of course, it is also possible to adopt a configuration in which these operations are automatically performed.

In the above example, four half-fold type sheets have been described. In the case of n-fold type half-fold sheets, the first and fourth pages of the original are placed on the front side of the sheet S1, and 2 pages are placed on the reverse side. Page and (4n-1) page image data, and the original page 3 and (4n-1)
By providing the memory 89 with a program for allocating (n-2) pages and 4 pages and (4n-3) pages... on the back surface, it is possible to easily carry out any number of sheets.

The bookbinding mode is a one-sided binding type as shown in FIG.
In the case where the number of pages is set to 8 in S4, the binding mode of four sheets in the single binding format is designated by the binding mode designation 88, and the control unit 80 calls the program corresponding to the binding mode from the memory 89. And the control unit 8
For 0, data processing according to this program is performed. In other words, the control unit 80 calls the original page 1 and page 2 required for the sheet S1 from the image memory 82, and sets each image data to fit within one page of the recording paper P in consideration of the binding margin. (Image data restoration 83),
Two pages of image data are allocated by the selector (I) 84 and input to the back surface output memory 85B. The image data of one page is input to the front surface output memory 85A. The selector (II) 86 first calls back surface image data from the back surface output memory 85B to perform image processing (image processing unit 87), and image formation is performed. Next, the selector (II) 86 calls up the surface image data from the surface output memory 85A and performs image processing (image processing unit 87).
Image formation is performed. The sheet S1 on which one page image is recorded on the front side and two page images are recorded on the back side is discharged to the tray with the front side down. In the image processing section 87, a difference is made in the amount of color correction and the amount of γ correction between the front image and the back image, and correction is performed so that the image quality of the front and back surfaces on the sheet is the same. The increase / decrease of the toner adhesion amount between the front side image and the back side image is performed by the image processing section 87 or the printer section (12). In the same manner, the control unit 80 calls up the original 3 pages and 4 pages required for the sheet S2 from the image memory 82,
On the sheet S2, a three-page image is recorded on the front side and a four-page image is recorded on the back side, and the sheet S2 is discharged onto the sheet S1 with the front side down. In this manner, the originals are output alternately in the order of the back side and the front side, and the sheets S1 to S
4 are ejected in the correct order. Thus, by binding the binding side together with glue or stapling, bookbinding arranged in page order is completed. In the case where staples that are bound or punched together by a stapler or the like are provided in the tray portion, a sheet detecting means is provided at the entrance of the tray portion, and staples are activated upon detection of discharge of the expected number of sheets onto the tray. Be taken.

(Embodiment 2) The invention according to claims 4 and 5 will be described with reference to FIGS.

The double-sided image forming apparatus of the present invention, in addition to the first embodiment, can use a transfer material such as a thick paper or a colored recording paper for the cover, and can use each page of the specified transfer material. The screen can be allocated to both sides corresponding to the front side and the back side. A major feature is that thick paper can be used.

The double-sided image forming apparatus of the present invention is, for example, shown in FIG.
Disposed in the lower portion of the sheet cassette 15 to the apparatus main body as shown in, established a paper feed cassette 150 for accommodating the thick recording sheet P ₀ on the extension of the sheet feed path, recording paper was further fix the image Is provided with a reversing paper discharge path 180 for reversing the front and back and discharging the paper.

In the normal copy mode, thin recording paper P, which is thin general paper, is discharged from the paper feed cassette 15 and images are recorded on both sides thereof. Thereafter, the originals are sequentially discharged via the discharge rollers 18 with the front surface image of the original facing downward.

When the bookbinding mode is designated by the bookbinding mode designation 88, and especially when the use of thick paper is designated for the cover,
When forming an image of the first document, the sheet cassette 1
Is unloaded the thick recording sheet P ₀ 50 to record an image on both sides, the said reverse discharge path 180 is discharged paper not down the surface image through the sheet discharge roller 18, the second and subsequent sheets is when the image forming of the document is discharged to the sequential page order in the downward the same surface image recording sheet P of the general paper feed cassette 15 of the is carried out to an upper layer of the recording paper P _0.

Therefore, by binding the recording papers in a stacked state in a binding form, the original images can be recorded in the order of pages with the front cover being thick paper, and the image data of each original is compressed. If the image forming process in the half-fold format is controlled so as to change the output order, the book can be bound in a half-fold format in which the front and back surfaces are thick paper.

When feeding the thick recording paper P ₀ ,
Wherein the recording sheet thickness P ₀ from the current value at the time of charging by the paper charger 14f is detected, the transfer of the image by the signal,
It is switched setting conditions of separation and fixing processing, and the like, it generally of the recording paper with respect to thick recording paper P ₀ by P
, A high quality image is recorded.

[0069]

According to the present invention, according to the first aspect, the images on the front and back sides of the original are formed in such a form that they can be freely allocated to the front and back sides of each recording sheet according to the bookbinding form and bookbinding can be performed immediately. According to No. 4, the images on the front and back of the document are freely allocated to the front and back of each recording paper, including the selection of the recording paper, in accordance with the bookbinding mode, and are formed in a form that enables bookbinding immediately.

Further, according to the third and fifth aspects, the image forming conditions are automatically corrected for the front and back images irrespective of the difference in the transfer process and the change in the thickness of the recording paper, so that the same high quality image is always recorded. , A high-performance double-sided image forming apparatus capable of performing the above-mentioned is provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a two-sided image forming apparatus of the present invention.

FIG. 2 is a side sectional view of a photosensitive drum and an exposure unit.

FIG. 3 is an explanatory diagram showing an image transfer method.

FIG. 4 is a cross-sectional configuration diagram of a document image reading apparatus.

FIG. 5 is an input / output control circuit diagram of image data.

FIG. 6 is an explanatory diagram showing image allocation according to each bookbinding mode.

FIG. 7 is a cross-sectional configuration diagram of an apparatus capable of feeding thick recording paper.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 photoconductor drum 11 scorotron charger 12 exposure unit 13 developing device 14a toner image receiver 14c transfer device 14f paper charger 14g backside transfer device 15, 150 paper cassette 17 fixing device 18 discharge roller 19 cleaning device 50 document image reading Device 80 Control unit 82 Image memory 84 Selector (I) 85A Front side output memory 85B Back side output memory 86 Selector (II) D Original P, P ₀ Recording paper

Claims (5)

[Claims] A first image carrying means for carrying the toner image formed by the toner image forming means; and a toner image carried by the first image carrying means is transferred. A second image carrying means carried on the surface; a first transferring means for transferring the toner image carried on the first image carrying means onto a surface of the transfer material; and a carrying means carried on the second image carrying means. A two-sided image forming apparatus, comprising: a second transfer unit for transferring the transferred toner image to the back surface of the transfer material; and a fixing unit for fixing the toner image transferred to both surfaces of the transfer material. A plurality of images can be formed on the front side, and a control system for allocating images to both sides corresponding to the front side and the back side of each page of the transfer material according to the specification of the bookbinding mode is provided. Double-sided image forming device. 2. An image memory for a front side and an image memory for a back side, wherein image data is selectively transferred to each of the memories and output from each of the memories to a printer unit is performed alternately. Item 2. A double-sided image forming apparatus according to Item 1. 3. The double-sided image forming apparatus according to claim 1, wherein image forming conditions are different between the front side image and the back side image. 4. A first image carrying means for carrying a toner image formed by a toner image forming means, and a toner image carried by the first image carrying means is transferred. A second image carrying means carried on the surface; a first transferring means for transferring the toner image carried on the first image carrying means onto a surface of the transfer material; and a carrying means carried on the second image carrying means. A two-sided image forming apparatus, comprising: a second transfer unit for transferring the transferred toner image to the back surface of the transfer material; and a fixing unit for fixing the toner image transferred to both surfaces of the transfer material. A plurality of images can be formed on the surface, and the transfer material is specified, and the transfer material is fed in accordance with the specification, and the images are allocated to both corresponding front and back surfaces of each page of the transfer material. Control system that performs Surface image forming apparatus. 5. The double-sided image forming apparatus according to claim 4, wherein image forming conditions are changed according to designation of a transfer material.