JP4111353B2 - Double-sided image forming device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophotographic apparatus such as a copying machine, a printer, or a fax machine, in which a charging unit, an image exposure unit, and a developing unit are arranged around an image carrier to transfer and fix a toner image formed on the image carrier on a recording paper. The present invention relates to a type image forming apparatus.
[0002]
[Prior art]
Conventionally, in the case of single-sided printing in an electrophotographic image forming apparatus such as a copying machine, a printer, or a fax machine, a toner image formed on an image carrier is transferred and fixed onto a recording sheet as a transfer material, and then discharged. At this time, the toner image surface on the recording paper is discharged (face-up discharge where the recording paper surface is discharged upward), or the toner image surface on the transfer material is discharged downward (the recording paper surface is facing downward). The face down discharge method is used.
[0003]
In the case of duplex printing, the image on one side formed on the image carrier is transferred and fixed on a transfer material, which is once stored in a double-sided reversing paper feeder, and again on the image carrier. A method is used in which a transfer material is fed from a double-sided reversing paper feeding device in synchronism with the image formed on the image, and the image on the other surface is transferred and fixed on the transfer material.
[0004]
In the double-sided printing apparatus, as described above, the transfer material is transported to the double-sided reversing paper feeding device or the fixing device is passed twice, so that the transfer material transport is unreliable and causes a jam or the like. It was the cause. On the other hand, after forming on both sides of the transfer material according to Japanese Patent Publication No. 49-37538, Japanese Patent Publication No. 54-28740, Japanese Unexamined Patent Publication No. 1-444457, Japanese Unexamined Patent Publication No. Hei 4-214576, etc., fixing is performed once. What to do is proposed.
[0005]
[Problems to be solved by the invention]
However, if one image forming apparatus discharges with the surface on the recording paper facing up (face-up discharging) or discharges with the surface on the recording paper facing down (face-down discharging), the page order is not aligned. Also, page alignment can be performed when it is desired to change the transfer order of image data, or when the transfer order of either the previous page or the subsequent page is defined by the relationship of the transfer order of image data by ADF or the like. There was a problem of disappearing.
[0006]
Also, in an image forming apparatus that has both face-up discharge and face-down discharge, regardless of which is selected, the page order of double-sided copying (double-sided printing) will be discharged correctly, especially automatically. A device that can be used has been desired.
[0007]
In addition, if you have two paper discharge trays, one of the paper discharge trays will be filled with the discharged copy (print), and if it exceeds that, it will be automatically However, there is a problem that the page order is not aligned when switching to another paper discharge tray, and a solution has been desired.
[0008]
The present invention solves the above problems, and in an apparatus having two or more discharge trays arranged in page order in both face-up discharge and face-down discharge, when one is full, the other discharge tray An object of the present invention is to provide a double-sided image forming apparatus capable of printing a large amount of paper and printing at a high speed.
[0009]
[Means for Solving the Problems]
  An object of the present invention is to form an image memory that stores image data of a plurality of pages, a mirror processing circuit that changes image data output from the image memory into a mirror image, a photoconductor that forms a toner image, and a photoconductor. A toner image receiver for transferring and holding the toner image, and a toner image sequentially formed on the basis of the image data output from the image memory, and the photoreceptor on both the front and back sides of the recording paper in one pass. The recording means for transferring the toner image on the top and the toner image receiver, fixing the front and back toner images on the recording paper at one time to perform double-sided print recording, and transferring the double-sided print output by the recording means A first paper discharge unit that sequentially stacks and discharges the paper in a rear and back state; a second paper discharge unit that reverses the front and back state after transferring the double-sided print output by the recording unit and sequentially stacks and discharges; Said first and Whether to select the second paper discharge means via the paper discharge selection means, the switching of the even / odd page order of the image data output from the image memory according to the selection operation of the paper discharge selection means, and the mirror processing circuit In a double-sided image forming apparatus having a control means for controlling whether
It has an operation panel for specifying single-sided printing or double-sided printing and face-up discharge or face-down discharge,
A mode as an image forming method to be executed when double-sided printing and face-up paper discharge are designated on the operation panel, and B as an image forming method to be executed when double-sided printing and face-down paper discharge are designated. Mode, C mode as an image forming method to be executed when single-sided printing and face-up paper discharge are specified, and D mode as an image forming method to be executed when single-sided printing and face-down paper discharge are specified Have
In the A mode, when printing n pages (n is an even number), the control means reads the image data from the image memory in order from the first page to the nth page, and even-numbered toner. An image is formed on the photoconductor, an odd-numbered toner image is formed on the toner image receiver, and the toner images formed on the photoconductor and the toner image receiver are transferred to the front and back of the recording paper. The image is formed by double-sided printing of the odd-numbered page with the toner image of the odd-numbered page down and the even-numbered page next to the odd-numbered page, and the recording paper on which the double-sided image is formed is discharged face-up. Then, the second recording paper is placed on the first recording paper, and is discharged to the first tray so that the toner image surface of the even page of the last recording paper is the uppermost surface. In the B mode, page n (n is an even number) When printing, image data is sequentially read from the image memory as the second page, the first page, the nth page, and the n-1 page, and a toner image of odd pages is formed on the photosensitive member. A toner image of even pages is formed on the body and transferred to the front and back of the recording paper to form a double-sided image. Control is performed so that the even pages are turned upside down and discharged face down to the second tray. In the C mode, when printing n pages, the image data is output from the image memory sequentially from the nth page to the first page, and the toner image is not formed on the toner image receiver. It is formed only on the photoconductor, and the toner image on the photoconductor is transferred to the recording paper. First, the nth page of recording paper is discharged so that the toner image is on top, and finally the first page of recording paper is removed. Face up and discharge the toner image to the first tray. In the D mode, when printing n pages, image data is output from the image memory in order from the first page to the nth page, and a toner image is not formed on the toner image receiver. The toner image formed on the photoconductor is transferred to the recording paper, and the front and back are reversed, and the toner image surface is faced down and discharged face down to the second tray.Control
And detecting means for detecting the amount of paper discharged to the first and second paper discharge means. The detection means counts the number of paper discharged to the first and second paper discharge means, and the count is predetermined. When the count of the first paper discharge means is invalidated, and the selection of the paper discharge selection means is the first paper discharge means, the first paper discharge means to the second paper discharge means. Or when the selection of the paper discharge selecting means is the second paper discharge means, the second paper discharge means is switched to the first paper discharge means and the mode as the image forming method is switched. ,
  Achieved by a double-sided image forming apparatus characterized byThe
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below. The description in this column does not limit the technical scope of the claims or the meaning of terms. In addition, the following assertive description in the embodiment of the present invention shows the best mode, and does not limit the meaning or technical scope of the terms of the present invention.
[0012]
(Embodiment 1)
The basics and each mechanism of the image forming process of the first embodiment of the double-sided image forming apparatus of the present invention will be described using the color double-sided image forming apparatus shown in FIGS. FIG. 1 is a cross-sectional view of a color double-sided image forming apparatus according to a first embodiment of the double-sided image forming apparatus of the present invention, FIG. 2 is a side cross-sectional view of the image carrier of FIG. 1, and FIG. FIG. 4 is a diagram showing a face-up (FU) double-sided image formation state in A mode, FIG. 4 is a diagram showing a face-down (FD) double-sided image formation state in B mode, and FIG. 5 is a diagram showing C mode and D mode. FIG. 5A is a diagram showing an example of face-up (FU) single-sided image formation, and FIG. 5B is a diagram showing face-down (FD) single-sided image formation. 6 is a block diagram showing an example of a control system in the color double-sided image forming apparatus of the first embodiment. FIG. 7 is a color double-sided image forming apparatus of the first embodiment. Showing the image forming process in various modes It is a chart.
[0013]
In FIG. 6, 70 is a control unit comprising, for example, an MPU, 71 is an image memory, 72 is a switching circuit for switching the output destination of image data read from the image memory 71, and 73 is a change of image data to form a mirror image. Mirror processing circuit 74, ROM for storing the program of the image forming process of each mode, 75, RAM built in the control unit 70, 76, a key for inputting a set number, a key for designating a mode, and a print An operation panel 100 including a start button, a display unit, and the like is a printer that is a mechanism part of the image forming apparatus according to the first embodiment. The printer includes a FU paper discharge unit 120A, an FD paper discharge unit 120B, and a face-up (FU) / A face-down (FD) switching unit 30 is provided.
[0014]
The double-sided image forming apparatus of this embodiment includes a photosensitive drum 10, a scorotron charger 11, an exposure unit 12, a developing unit 13, a toner image receiving means 14, a paper feed cassette 15, a fixing device 17 and a cleaning device 19 shown in FIG. A recording means comprising:
Sending rollers 180 and 18A and a first tray 22A, which are first paper discharge means for sequentially stacking and discharging the double-sided prints output by the recording means to the first tray 22A in a face-up state with the front and back surfaces after transfer. A FU paper discharge unit 120A including a paper discharge sensor 23A, a paper discharge amount sensor 24A, and the like;
The two-sided print output by the recording means is a second paper discharge means that reverses the front and back states after transfer and sequentially stacks and discharges the paper onto the second tray 22B. The delivery rollers 180 and 18B, the second tray 22B, and the paper discharge An FD paper discharge unit 120B including a detection sensor 23B, a paper discharge amount detection sensor 24B, and the like;
A FU / FD switching unit 30 including a paper discharge switching unit 30a which is a paper discharge selection unit that selectively switches between the first and second paper discharge units;
The page order of the image data output from the image memory 71 is controlled in accordance with the selection operation of the paper discharge selecting means, and the input destination of the output image data is switched by the switching circuit 72 via the mirror processing circuit 73. The control unit 70 is a control unit that controls whether to input to the printer 100 or input directly to the printer 100 without going through the mirror processing circuit 73, and performs control of switching control and image forming process.
[0015]
Both the first and second paper discharge units have a shift tray function (not shown) that can distinguish each part when a plurality of output prints are continuously printed.
[0016]
The paper discharge detection sensors 23A and 23B include, for example, a photocoupler, a micro switch, and the like, and send a paper discharge signal to the control unit 70 every time the recording paper P (print) on which an image is recorded passes through the paper discharge passage. The discharge amount detection sensors 24A and 24B are composed of, for example, a micro switch having an actuator, and send a signal to the control unit 70 when the prints discharged and stacked on the first or second trays 22A and 22B are full.
[0017]
As shown in FIG. 6, when a set number or selection mode signal is input to the control unit 70 of the color double-sided image forming apparatus in accordance with the number of prints and mode selection, which is a set number input by the operator on the operation panel 76. One mode selected from the program P11 corresponding to the A mode, the program P12 corresponding to the B mode, the program P13 corresponding to the C mode, and the program P14 corresponding to the D mode stored in the ROM 74 through the control unit 70 is controlled. Called by the RAM 75 built in the unit 70, the process control and execution of the color double-sided image forming apparatus are performed.
[0018]
First, a color image forming method in A mode for face-up double-sided image formation will be described with reference to FIGS.
[0019]
Here, face-up image formation refers to image formation in which the recording paper P as a transfer material is sequentially stacked and discharged from the face-up discharge port 21A in FIG. 1 represents image formation in which the recording paper P is sequentially stacked and discharged from the face-down paper discharge port 21B of FIG.
[0020]
A toner image receiver 14a, which will be described later, is rotated in the direction indicated by the dotted arrow a in FIG. 1 about the axis of the driving roller 14d, and the following image formation is performed while being separated from the photosensitive drum 10. It is also possible to form an image with the toner image receiver 14a in contact therewith.
[0021]
The photosensitive drum 10 that is an image carrier is provided with a cylindrical base formed of, for example, a transparent member made of glass or transparent acrylic resin on the inside, and a transparent conductive layer, α-Si layer, or organic photosensitive layer (OPC). Or the like is formed on the outer periphery of the substrate.
[0022]
The photosensitive drum 10 is sandwiched between a front flange 10a and a rear flange 10b. The front flange 10a is supported by a guide pin provided on a cover attached to the front side plate of the apparatus main body, and is provided on the outer periphery of the rear flange 10b. The photoconductor drum 10 is rotated in the clockwise direction indicated by the arrow in FIG. 1 with the gear 10G engaged with the drive gear and the transparent conductive layer grounded by the power.
[0023]
In the present embodiment, it is only necessary to have an exposure light amount that can provide an appropriate contrast in the photoconductor layer of the photosensitive drum. Therefore, the light transmittance of the transparent substrate of the photosensitive drum in the present embodiment need not be 100%, and may have a characteristic that a certain amount of light is absorbed when the exposure light is transmitted. As a material for the translucent substrate, an acrylic resin, particularly polymerized using a methacrylic acid methyl ester monomer, is excellent in transparency, strength, accuracy, surface properties, etc., and is preferably used. Various translucent resins such as acrylic, fluorine, polyester, polycarbonate, and polyethylene terephthalate used can be used. Moreover, as long as it has translucency with respect to exposure light, you may color. As the translucent conductive layer, a metal thin film made of indium, tin, oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, Au, Ag, Ni, Al, etc. that maintains translucency As a film forming method, a vacuum deposition method, an active reaction deposition method, various sputtering methods, various CVD methods, a dip coating method, a spray coating method, or the like is used. As the photoconductor layer, an amorphous silicon (α-Si) alloy photosensitive layer, an amorphous selenium alloy photosensitive layer, and various organic photosensitive layers (OPC) can be used.
[0024]
A scorotron charger 11 as a charging means is used in an image forming process of each color of yellow (Y), magenta (M), cyan (C), and black (K), and the moving direction of the photosensitive drum 10 as an image carrier. A control grid that is mounted opposite to the photosensitive drum 10 in a direction orthogonal to the above and is held at a predetermined potential with respect to the aforementioned organic photosensitive layer of the photosensitive drum 10, and a discharge electrode 11a, for example, in a sawtooth shape. A charging action (negative charging in the present embodiment) is performed by corona discharge having the same polarity as the toner using electrodes, and a uniform potential is applied to the photosensitive drum 10. Other wire electrodes can be used as the discharge electrode 11a.
[0025]
An exposure unit 12 serving as an image exposure unit for each color has an exposure position on the photosensitive drum 10 between the discharge electrode 11a of the scorotron charger 11 and the development position of the developing unit 13 with respect to the developing sleeve 131. The photoconductor drum 10 is arranged in a state provided upstream in the rotation direction.
[0026]
The exposure unit 12 includes 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 parallel to the axis of the photosensitive drum 10 are arranged in an array, and the like. The SELFOC lens 12b as a double imaging element is configured as an exposure unit attached to the holder 12c. An exposure unit 12, a uniform exposure device 12d, and a simultaneous transfer exposure device 12e for each color are attached to a cylindrical holding member 20 fixed to the apparatus main body, and are accommodated inside the substrate of the photosensitive drum 10. .
[0027]
As the exposure element, a linear element in which a plurality of light emitting elements such as FL (phosphor light emission), EL (electroluminescence), and PL (plasma discharge) are arranged in an array is used. The emission wavelength of the light emitting element used in this embodiment is usually in the range of 680 to 900 nm where the Y, M, and C toners are highly transmissive. However, since the image exposure is performed from the back side, the color toner is used. However, the wavelength may be shorter than that which does not have sufficient transparency.
[0028]
In the present embodiment, the color order in which images are formed and the developing device provided on the rotated photosensitive drum 10 in accordance with the color order are based on the rotation direction of the photosensitive drum 10 indicated by the arrows in FIG. The Y and M developing units 13 are arranged on the left side of the photosensitive drum 10 and the C and K developing units 13 are arranged on the right side of the photosensitive drum 10, and below the developing casing 138 of the Y and M developing units 13 ( The Y and M scorotron chargers 11 are disposed on the upstream side, and the C and K scorotron chargers 11 are disposed above (upstream) the developing casing 138 of the C and K developing units 13.
[0029]
A developing unit 13 which is a developing unit for each color accommodates a one-component or two-component developer of yellow (Y), magenta (M), cyan (C), and black (K), respectively. A cylindrical non-magnetic stainless steel having a thickness of 0.5 mm to 1 mm and an outer diameter of 15 to 25 mm, for example, rotating in the same direction as the rotation direction of the photosensitive drum 10 at a developing position while maintaining a predetermined gap with respect to the peripheral surface of Alternatively, a developing sleeve 131 made of an aluminum material is provided.
[0030]
The developing unit 13 is kept in contact with the photosensitive drum 10 by a not-shown abutting roller with a predetermined value, for example, 100 μm to 1000 μm, and is kept in non-contact. A negatively charged photosensitive member that is applied with a developing bias voltage to which a direct current or a further alternating voltage is applied, is subjected to jumping development with a one-component or two-component developer contained in a developing device, and a transparent conductive layer is grounded A non-contact reversal development is performed in which a DC bias voltage having the same polarity as the toner (negative polarity in the present embodiment) is applied to the drum 10 to attach the toner to the exposed portion.
[0031]
The developing device 13 for each color described above performs non-contact development by applying 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 described above. In the non-contact state, reversal development is performed with toner having the same polarity as the charged polarity (in this embodiment, the photosensitive drum 10 is negatively charged and negative polarity toner).
[0032]
In an image reading apparatus separate from the present apparatus, Y, M, and C, in which image information read from an original image by an image sensor or image information edited by a computer is subjected to γ correction and other image processing. The image data for each color of K and K is temporarily stored in the image memory 71. When the image recording is started, the image data of each color is sequentially read out from the image memory 71 and input as an electrical signal to the exposure unit 12 for each color.
[0033]
Printing (image recording) is started by pressing the start button on the operation panel 76. A toner image receiver 14a, which will be described later, is rotated about the axis of the drive roller 14d in the direction indicated by the dotted arrow a in FIG. A gear 10G provided on the rear flange 10b of the photosensitive drum 10 is rotated through the driving gear G1 to rotate the photosensitive drum 10 in the clockwise direction indicated by an arrow in FIG. 1, and at the same time on the left side of the photosensitive drum 10. Application of a potential to the photosensitive drum 10 is started by the charging action of the Y scorotron charger 11 disposed on the upstream side of the developing casing 138 of the yellow (Y) developer 13.
[0034]
After the photosensitive drum 10 is applied with a potential, exposure by an electric signal corresponding to the first color signal, that is, the Y image data is started in the Y exposure unit 12, and the surface of the photosensitive drum 10 is copied to the photosensitive layer by rotational scanning of the drum. An electrostatic latent image corresponding to the Y image of the image is formed.
[0035]
The latent image is reversed and developed by the Y developing unit 13 with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed as the photosensitive drum 10 rotates.
[0036]
Next, the photosensitive drum 10 is placed on the yellow (Y) toner image, further to the left of the photosensitive drum 10, on the downstream side of yellow (Y), on the upstream side of the developing casing 138 of the developing unit 13 of magenta (M). A potential is applied by the charging action of the magenta (M) scorotron charger 11 arranged in the M, and exposure is performed by the second color signal of the M exposure unit 12, that is, M image data. By non-contact reversal development, a magenta (M) toner image is sequentially superimposed on the yellow (Y) toner image.
[0037]
By the same process, a cyan (C) scorotron charger 11, a C exposure unit 12 and a C developer arranged on the right side of the photosensitive drum 10 and above the developing casing 138 of the cyan (C) developer 13 13, a cyan (C) toner image corresponding to the third color signal is disposed on the right side of the photosensitive drum 10 and on the downstream side of C above the developing casing 138 of the black (K) developing device 13. The black (K) scorotron charger 11, the exposure unit 12 and the developing unit 13 sequentially form a black (K) toner image corresponding to the fourth color signal and rotate the photosensitive drum 10 once. Within this range, a color toner image is formed on the peripheral surface.
[0038]
The exposure of the organic photosensitive layer of the photosensitive drum 10 by the Y, M, C, and K exposure units 12 is performed from the inside of the drum through the above-described transparent substrate. Therefore, the exposure of the image corresponding to the second, third, and fourth color signals is performed without any influence of the previously formed toner image, and is equivalent to the image corresponding to the first color signal. An electrostatic latent image can be formed. In order to stabilize the temperature in the photosensitive drum 10 due to the heat generated by each exposure optical system 12 and to prevent the temperature from rising, a material having good thermal conductivity is used for the holding member 20, and a heater and a heat pipe are used in the holding member 20. In the case of a low temperature, a heater is used, and in the case of a high temperature, the heat can be radiated to the outside through a heat pipe.
[0039]
Next, the toner image receiver 14a is rotated about the axis of the drive roller 14d in the direction indicated by the dotted arrow b in FIG.
[0040]
A superimposed color toner image to be a back image (first page image) is formed on the photoconductive drum 10 (first image carrying means), and the color toner image of the back image on the photoconductive drum 10 is transferred. In the region 14b, the toner image is transferred onto the toner image receiver 14a (second image carrier) by the transfer device 14c to which a voltage having a polarity opposite to that of the toner (plus polarity in the present embodiment) is applied. At this time, uniform exposure is performed by the simultaneous transfer exposure device 12e using, for example, a light emitting diode so that good transfer is performed.
[0041]
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 a cleaning blade made of a rubber material in contact with the photosensitive drum 10. It is scraped off into the cleaning device 19 by 19a and is collected in a waste toner container (not shown) by a screw 19b. The photosensitive drum 10 from which the residual toner has been removed by the cleaning device 19 is further subjected to exposure by the uniform exposure device 12d before charging using, for example, a light emitting diode, in order to eliminate the history of the photosensitive body up to the previous printing. The charge on the peripheral surface is removed and the charge at the previous printing is removed.
[0042]
The toner image receiver 14a is again formed on the toner image receiver 14a while being rotated about the axis of the drive roller 14d in the direction indicated by the dotted arrow a in FIG. The back surface image and the transfer area 14b are synchronized, and the surface image (second page image) of the superimposed color toner image is formed again on the photosensitive drum 10 by the toner image forming means. It is necessary to change the image data so that the front surface image formed at this time becomes a mirror image with the back surface image formation on the image carrier.
[0043]
When the front image is formed, the toner image receiver 14a is again rotated around the axis of the drive roller 14d in the direction indicated by the dotted arrow b in FIG.
[0044]
The recording paper P, which is a transfer material, is fed from a paper feed cassette 15, which is a transfer material storage means, by a feed roller 15a, is fed by a feed roller 15b, and is conveyed to a timing roller 15c.
[0045]
The recording paper P is synchronized with the color toner image of the front image carried on the photosensitive drum 10 and the color toner image of the back image carried on the toner image receiver 14a by driving the timing roller 15c. And fed to the transfer area 14b. At this time, the recording paper P is charged to the same polarity as the toner by the paper charger 14f, adsorbed to the toner image receiver 14a, and fed to the transfer area 14b. By charging the paper with the same polarity as the toner, the toner image is prevented from being attracted by being attracted to the toner image on the toner image receiver 14a or the toner image on the photosensitive drum 10, thereby preventing the toner image from being disturbed.
[0046]
The surface image on the peripheral surface of the photosensitive drum 10 is collectively transferred to the upper surface side of the recording paper P by the transfer device 14c to which a voltage having a polarity opposite to that of the toner (plus polarity in the present embodiment) is applied (first). 1 transfer means). At this time, the back image on the peripheral surface of the toner image receiver 14a is not transferred to the recording paper P and exists on the toner image receiver 14a. Next, the back surface image on the peripheral surface of the toner image receiver 14a is collectively transferred onto the lower surface side of the recording paper P by the back surface transfer device 14g to which a voltage having a polarity opposite to that of the toner (plus polarity in the present embodiment) is applied. (Second transfer means). Uniform exposure by a transfer simultaneous exposure unit 12e using a light emitting diode, for example, provided inside the photosensitive drum 10 so as to face the transfer unit 14c so that a good transfer can be performed at the time of transfer by the transfer unit 14c. Is done.
[0047]
Since the toner images of the respective colors overlap with each other, it is preferable that the upper layer toner and the lower layer toner are charged to the same polarity with the same charge amount in order to enable batch transfer. Therefore, in the double-sided image formation in which the polarity of the color toner image formed on the toner image receiver 14a is reversed by corona charging, or the color toner image formed on the image carrier is reversed by corona charging, This toner is not preferable because the toner is not sufficiently charged with the same polarity, resulting in poor transfer.
[0048]
By repeating reversal development on the image carrier, color toner images of the same polarity formed by superimposing them are collectively transferred to the toner image receiver 14a without changing the polarity, and then collectively onto the recording paper P without changing the polarity. Transferring is preferable because it contributes to improvement in transferability of backside image formation. For surface image formation, the reversal development is repeated on the image carrier, and the color toner images of the same polarity formed by superimposing can be collectively transferred onto the recording paper P without changing the polarity. It is preferable because it contributes to improvement of the property.
[0049]
From the above, in color image formation, the first and second transfer means are operated to form a color toner image on the surface of the transfer material using the above-described image forming method on the front and back surfaces, and then the second image is formed. A double-sided image forming method in which a transfer unit is operated to form a color toner image on the back surface of the transfer material is preferably employed.
[0050]
The toner image receiver 14a is an endless rubber belt having a thickness of 0.5 to 2.0 mm, and is made of silicon rubber or urethane rubber 10.⁸-10¹²A semiconductive substrate having a resistance value of Ω · cm and a two-layer structure in which a fluorine coating having a thickness of 5 μm to 50 μm as a toner filming prevention layer is formed on the outside of the rubber substrate. This layer is also preferably semi-conductive. Semiconductive polyester, polystyrene, polyethylene, polyethylene terephthalate, etc. having a thickness of 0.1 to 0.5 mm can be used instead of the rubber belt substrate.
[0051]
The recording paper P on which the color toner images are formed on both sides is neutralized by a paper separation AC neutralizer 14h for transfer separation, separated from the toner image receiver 14a, and two rollers having heaters inside both rollers. The toner is conveyed to a fixing device 17 as a fixing unit composed of rollers. The recording paper P (print) on which the front and back adhering toners on the recording paper P are fixed by applying heat and pressure between the fixing roller 17a and the pressure roller 17b and the double-sided image recording is performed is provided on the control unit. The sheet is fed by the sheet discharge roller 18A so as to pass through the sheet discharge port 21A by the sheet discharge switch 20a switched to discharge the print to the first tray 22A by the control of 70, and face-up discharge outside the apparatus is performed. To the first tray 22A.
[0052]
The toner remaining on the peripheral surface of the toner image receiver 14a after the transfer is cleaned by the toner image receiver cleaning device 14i. Further, 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 is made of a rubber material that is in contact with the photosensitive drum 10. It is scraped off into the cleaning device 19 by the cleaning blade 19a, and is collected in a waste toner container (not shown) by the screw 19b. The photosensitive drum 10 from which residual toner has been removed by the cleaning device 19 is uniformly charged by the scorotron charger 11, and the toner image receiver 14a is centered on the axis of the drive roller 14d in the direction indicated by the dotted arrow a in FIG. The next image forming cycle is started in a state of being rotated and separated from the photosensitive drum 10.
[0053]
The above is an A-mode print image forming method. When a large number of sheets, for example, n pages (n is an even number) is printed in the A mode, as shown in FIG. The even-page color toner image formed and the odd-page color toner image formed on the toner image receiver 14a are transferred to the front and back of the recording paper P to form a double-sided image. Images are formed and ejected by double-sided printing of the first and second pages, and the second print is above the first print, and the last print is above the n-th page toner image surface. And discharged to the top surface.
[0054]
In this A mode print, since image formation and print discharge are performed as described above, the image data read from the image memory 71 is the first page → second page → third page →... → n−1 page. The control unit 70 controls to read in the order of the eye → nth page.
[0055]
In the image formation in the B mode, a recording sheet P (print) on which double-sided image recording is performed in the same process except that the page order is different from the image formation in the A mode is sent by the paper discharge roller 180, and is controlled by the control unit 70. The recording paper P is fed by the paper discharge roller 18B so as to pass through the paper discharge port 21B by the paper discharge switch 30a switched to discharge the print to the second tray 22B, and the recording paper P is turned upside down. The paper is discharged to the second tray 22B. As a result, image formation and discharge are performed in the same page order.
[0056]
In B-mode printing, the recording paper P that has been printed is turned upside down and discharged onto the second tray 22B, and therefore, for example, n pages (n is an even number) are printed as shown in FIG. In this case, an odd-page color toner image is formed on the photosensitive drum 10 and an even-page color toner image is formed on the toner image receiver 14a and transferred to the front and back of the recording paper P to form a double-sided image. Image formation of the first double-sided print of the first and second pages with the color toner image of the second page down and reversal discharge are performed, and the final print is the color toner of the (n-1) th page. The image is reversed so that the color toner image surface of the nth page faces up and is discharged to the uppermost surface.
[0057]
In this B-mode printing, a toner image of an even number of pages is formed on the toner image receiver 14a. Therefore, the control unit 70 changes the order of image data read from the image memory 71 from the second page → the first page → the fourth page → The control unit 70 controls the order of the third page →... → n page → n−1 page. As a result, image formation and discharge are performed in the same page order.
[0058]
As described above, color image formation in A and B modes for double-sided image formation is performed. The toner image carried on the photosensitive drum 10 (first image carrying means) by the toner image forming means is recorded on the recording paper P. C-mode of single-sided image formation in which the toner image surface is discharged to the first tray 22A outside the apparatus with the toner image surface facing up (face up), and the toner image carried on the photosensitive drum 10 are recorded on the recording paper P. The single-sided image forming D mode in which the toner image surface is transferred to the second tray 22B with the toner image surface facing down (face down) and discharged onto the second tray 22B can be performed in the color image forming process described above. it can. In the C and D modes, a simple method is used in which the toner image is formed only on the photosensitive drum 10 and is not formed on the toner image receiver 14a.
[0059]
When a large number of sheets, for example, n sheets are printed in the C mode, as shown in FIG. 5A, the n-th page print is formed and discharged with the color toner image on top, and the first page Are printed on the uppermost surface with the color toner image surface facing up. Therefore, the control unit 70 controls the image data output from the image memory 71 so as to be performed in the order of the nth page → the (n−1) th page →... → the second page → the first page. As a result, image formation and discharge are performed in the same page order.
[0060]
When a large number of prints, for example, n sheets are printed in the D mode, as shown in FIG. 5B, image formation and discharge are performed from the first print, and the nth print is a color toner. The image is discharged on the top side with the image side down. Accordingly, the control unit 70 controls so that the image data output from the image memory 71 is processed in the order of the first page → second page →... → n−1 page → n page. As a result, image formation and discharge are performed in the same page order.
[0061]
As described above, printing in the A, B, C, and D modes is performed, and a large number of sheets are quickly printed under the control of the control unit 70.
[0062]
A large number of prints will be described with reference to the block diagram of FIG. 6 and the flowchart of FIG.
[0063]
An operator designates a mode and sets a set number of prints on the operation panel 76, and presses a start button to start printing. Based on the signal from the operation panel 76, the control unit 70 determines whether the printing is duplex printing or simplex printing (step 10). If the printing is duplex printing, then face-up ejection (FU ejection) or face-down ejection (FD) It is determined whether the paper is discharged (step 11). For FU paper discharge, the image data is read from the image memory 71 and the switching circuit 72 is controlled to correspond to the A mode to read the image data, and the odd page image data passes through the mirror circuit 73 every other page. Then, the mirror image is changed and controlled so as to be sent to the exposure unit 12 of the printer 100 (step 12), and the discharge switch 30a is switched to the FU discharge side by the action of the FU / FD switching unit 30. Confirm and perform A mode recording (step 13). The control unit 70 determines whether or not the first tray 22A is full based on a signal from the discharge amount detection sensor 24A from the FU paper discharge unit 120A (step 16). If not, the process proceeds to step 17 and reaches the set number. (Step 17), if the set number of sheets has not been reached, the process returns to step 10 to repeat the above operations of steps 10 to 17, and if the set number of sheets has been reached, the printing operation is terminated.
[0064]
In this case, full means that a set of a predetermined number of pages has been printed by an integer number of copies. If a full detection is made during a set of print outputs, it is determined that the print is complete when a (good) set of print outputs is completed. That is, it means that m sets of 1 to n pages are printed. (M, n: integer)
If it is determined in step 11 that the FD is ejected, the process proceeds to step 14 where the control unit 70 reads out the image data from the image memory 71 in the second page of page B → first page → fourth page → third page. The B mode is recorded in step 15, and the process proceeds to step 16 to determine whether the second tray 22B is full as in the case of the A mode. If the second tray 22B is not full, step 17 is executed. Then, the control unit 70 counts the paper discharge signal from the paper discharge detection sensor 23B and determines whether or not the set number has been reached based on the counted number, and returns to step 10 if the set number has not been reached. The above operations of Steps 10 to 17 after Steps 14 and 15 are repeated, and when the set number of sheets is reached, the printing operation is terminated.
[0065]
In both the A and B modes, if it is determined in step 16 that the designated tray is full based on the signal from the discharge amount detection sensor 24, the process proceeds to step 18 and the designated tray is full on the display unit of the operation panel 76. And proceeds to step 19 to stop the printing operation.
[0066]
If it is determined in step 10 that single-sided printing is performed instead of double-sided printing, the process proceeds to step 20. If it is determined in step 20 whether FU paper discharge or FD paper discharge is set and FU paper discharge is set, the image memory 71 The image data is sequentially read out from the nth page of the C mode to the (n-1) th page, one page at a time (step 21). After the C mode recording is performed (step 22), the process proceeds to step 16 and proceeds to step 16. In the same manner as described above, after step 16, step 17, and step 10, the process returns to step 20, and after step 21 and step 22, the process proceeds to step 16. If FD paper discharge is set in step 20, the image data is read sequentially from the first page to the second page in the D mode, one page at a time (step 23), and the D mode recording is performed. After (step 24), the process proceeds to step 16, and after passing through steps 17 and 10, the process returns to step 20, passes through steps 23 and 24, and proceeds to step 16. If it is determined in step 16 that the designated tray is full in both the C and D modes, the process proceeds to step 18 to display that the designated tray is full on the display unit of the operation panel 76, and then proceeds to step 19 to stop the printing operation. . If it is determined in step 16 that the designated tray is not full, it is determined in step 17 whether or not the set number has been reached. If it is determined that the set number has not been reached, the process returns to step 10 to perform image formation in the designated mode. If it is determined again in step 10 that the set number of sheets has been reached, printing ends.
[0067]
(Embodiment 2)
The image forming process and each mechanism of the second embodiment of the double-sided image forming apparatus of the present invention will be described with reference to FIGS. FIG. 8 is a sectional view of a color double-sided image forming apparatus according to the second embodiment of the double-sided image forming apparatus of the present invention, and FIG. 9 is a sectional view showing an example of the structure of the reading device 50 in FIG. FIG. 10 is a block diagram showing various mode selection and control systems in the color double-sided image forming apparatus of the second embodiment, and FIG. 11 is a flowchart showing image forming operations relating to the respective modes of the second embodiment. .
[0068]
The double-sided image forming apparatus of the second embodiment is a copying apparatus having an image reading device at the top of the apparatus, and has the same function and structure as the first embodiment except that a semiconductor laser light emitting element is used for the exposure unit. The members having the same functions and structures as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
[0069]
The image data for each color of the original of the double-sided image forming apparatus of the second embodiment is read by, for example, the image reading device 50 provided in the upper part of the apparatus main body in FIG.
[0070]
FIG. 9 is a cross-sectional view showing an example of the image reading apparatus. In FIG. 9, 50A is a document conveying device, and 50B is a scanning optical system as document reading means.
[0071]
In the case of the image reading device 50, the document D is stacked on the document placing table 60A in the page order from the bottom with the surface facing downward, and the lowermost document is operated by the operation of the carry-out roller 51 and the separating roller 52 of the document conveying device 50A. D is sequentially conveyed toward the conveyance path 53 one by one.
[0072]
The unloaded document D is removed from the guide plate G urged to the position indicated by the solid line and retracted to the position indicated by the dotted line, and is fed onto the transparent platen glass 55 via the conveyor belt 54. Thus, the document is temporarily stopped at the document reading position with the surface facing downward.
[0073]
The surface image of the document D on the platen glass 55 includes a first mirror unit 56 including an illumination lamp 56a and a first mirror 56b constituting the scanning optical system 50B, a second mirror 57a and a third mirror positioned in a V shape. The second mirror unit 57 comprising 57b is optically scanned by the illumination reading operation at the speed V of the first mirror unit 56 and the movement at the speed V / 2 in the same direction by the second mirror unit 57, and the imaging lens L Thus, an image is formed on the three image pickup devices CCD through the dichroic prism H. The blue (B), green (G), and red (R) surface image data color-separated by the dichroic prism H and imaged on the image sensor CCD is subjected to image processing by the image data processing circuit 77 in FIG. Thereafter, the image data is converted into image data of each color of yellow (Y), magenta (M), cyan (C), and black (K), and this image data is directly output to the printer 10 of FIG. 10 or the image data of FIG. Stored in the memory 71. The image data stored in the image memory 71 is output as an electrical signal to each exposure unit 121 under the control of the control unit 70, and the surface on the photosensitive drum 10 is the same as the double-sided image forming apparatus of the first embodiment described above. An image is formed.
[0074]
When the image reading device 50 finishes reading the front surface image, the document D is reversed by the control of the control unit 70 in the document conveying device 50A through the reverse feeding path 58 by the reverse rotation of the conveying belt 54. Then, the sheet is again fed onto the platen glass 55 through the conveyance path 53 via the conveyance belt 54, and temporarily stopped at the document reading position with the back surface facing downward.
[0075]
The document D on the platen glass 55 is scanned on the back image by the scanning optical system 50B and subjected to image processing by the image data processing circuit 77 in FIG. 10, and then each color (Y, M, C, K) is the same as described above. Each image data is directly output to the printer 100 or temporarily stored in the image memory 71 in the page order or reading order. The read image data is output as an electrical signal to each exposure unit 121 and is a front image or back image on the photosensitive drum 10 or on the toner receiver 14a in the same manner as the double-sided image forming apparatus of the first embodiment described above. Is transferred to the front and back of the first recording sheet P fed from the sheet feeding cassette 15, and the first copy cycle is completed. The recording paper P carrying the front toner image and the back toner image is fixed by the fixing device 17 and discharged onto the first tray 22A outside the device or the second toilet 22B outside the device according to each mode.
[0076]
The first and second trays can discharge a plurality of (n) page originals (m copies) and have a tray shift function for easily distinguishing each n page. At the end of copying every n pages, the tray moves back and forth or back and forth so that the discharged copies can be distinguished in units of n sheets (not shown).
[0077]
When copying a plurality of copies, the image of the original D is not read during the second and subsequent copies, and an image is formed by outputting the image data from the image memory. The front image and the back image are transferred to the front and back of each of the second and subsequent recording sheets P to be fed. The recording paper P holding the front toner image and the back toner image is fixed by the fixing device 17 and then laminated in the page order on the previously discharged recording paper.
[0078]
On the other hand, in the image reading device 50, the document D for which image reading has been completed is discharged onto the toilet 60 </ b> B via the discharge roller 59 by the operation of the conveyance belt 54.
[0079]
According to the mode designated and set on the operation panel 76 of FIG. 10 and the set number of sheets, the image is stored in the ROM 74 through the control unit 70 by selecting the A mode to D mode of the image forming method of the color double-sided image forming apparatus of this embodiment. One mode selected from the program P21 corresponding to the A mode, the program P22 corresponding to the B mode, the program P23 corresponding to the C mode, and the program P24 corresponding to the D mode is called up in the RAM 75 and the color double-sided image forming apparatus Process control and execution are performed.
[0080]
A color image forming method using the A mode will be described.
[0081]
A toner image receiver 14a stretched between the driving roller 14d and the driven roller 14e is rotated about the axis of the driving roller 14d in the direction indicated by a dotted arrow a in FIG. In the state, the following image formation is performed.
[0082]
The photosensitive drum 10 as an image forming body is provided with a cylindrical base on the inside and a photosensitive layer such as a conductive layer, an α-Si layer or an organic photosensitive layer (OPC) formed on the outer periphery of the base. In this state, it is rotated clockwise as indicated by an arrow in FIG.
[0083]
In order to eliminate the history of the photosensitive drum 10 until the previous printing by driving and rotating the photosensitive drum 10 as an image forming body, uniform exposure by a uniform exposure device 121a made of, for example, a light emitting diode as a charge eliminating means before charging. Exposure is performed, the charge on the peripheral surface of the photosensitive member is removed, and the charge during the previous printing is removed.
[0084]
A scorotron charger 11 as a charging means is charged by a control grid held at a predetermined potential with respect to the above-described organic photoreceptor layer of the photoreceptor drum 10 and corona discharge by the discharge electrode 11a (in this embodiment, a negative charge). ) To apply a uniform potential to the photosensitive drum 10.
[0085]
The photosensitive drum 10 is uniformly charged on the peripheral surface by the scorotron charger 11 and then subjected to image exposure based on the image signal by an exposure unit 121 as image exposure means, and a latent image is formed on the photosensitive drum 10. Is formed.
[0086]
The exposure unit 121 as an image exposure unit includes a semiconductor laser as a light emitting element (not shown), a rotating polygon mirror 121b that rotates and scans laser light emitted from the semiconductor laser, an fθ lens 121c, a reflection mirror 121d, and the like. The laser light emitted from the semiconductor laser is rotated and scanned by the rotating polygon mirror 121b, and the image exposure based on the image signal is performed in the main scanning direction of the rotating photosensitive drum 10 through the fθ lens 121c and the reflecting mirror 121d. In other words, a latent image is formed on the photosensitive drum 10 by sub-scanning by the rotation of the photosensitive drum 10.
[0087]
The peripheral edge of the photoconductive drum 10 is a developing unit filled with a developer composed of toner such as yellow (Y), magenta (M), cyan (C), and black (K) and a carrier, for each color. A developing device 13 is provided, and first development (for example, yellow) of the first color is performed by the developing sleeve 131.
[0088]
Next, as in the first embodiment, the photosensitive drum 10 corresponds to the yellow (Y) toner image, the magenta (M) toner image corresponding to the second color signal, and the third color signal. Then, a cyan (C) toner image and a black (K) toner image corresponding to the fourth color signal are sequentially superimposed.
[0089]
Also in this embodiment, the A and B modes for double-sided image formation described in Embodiment 1 and the C and D modes for single-sided image formation are selected, and FIGS. 3 to 5 of Embodiment 1 are selected according to each mode. Each of the image formation / discharge methods similar to those described in the above is adopted.
[0090]
A large number of copies of an n-page original such that m copies are made (that is, n × m copies are made) will be described with reference to the block diagram of FIG. 10 and the flowchart of FIG.
[0091]
The operator designates a mode and sets a set number of copies (m) on the operation panel 76, and presses a start button to start copying. Based on the signal from the operation panel 76, the control unit 70 determines whether the copy is a double-sided copy or a single-sided copy (step 30), and if it is a double-sided copy, then face-up discharge (FU discharge) or face-down discharge (FD) It is determined whether the sheet is discharged (step 31). For FU paper discharge, the image data is read from the image memory 71 and the switching circuit 72 is controlled to correspond to the A mode to read the image data, and the odd page image data passes through the mirror circuit 73 every other page. Then, the mirror image is changed and controlled to be sent to the exposure unit 121 of the printer 100, and the discharge switch 30a is switched to the FU discharge side by the action of the FU / FD switching unit 30 (step 32), and A mode recording is performed. Perform (step 34). In step 35, the control unit 70 determines that the signal count of the paper discharge detection sensor 23A is a predetermined number when the first tray 22A is full.₀(N₀Is an integer that changes according to the number of pages n of the document, and is a multiple of n), or whether a signal that has reached a predetermined value, which is a full signal from the discharge amount detection sensor 24A, is determined. If the value has not been reached, the process returns to step 33 to continue A mode recording. If the discharge count number or the discharge amount has reached a predetermined value in step 35, the process proceeds to step 36, where the control unit 70 switches the FU / FD switching unit 30 for FD discharge, and in step 37 reads out the image data. The B mode recording is performed in the order of the second page of the B mode → the first page → the fourth page → the third page. After the copying of the plurality of copies is completed, if both the first and second trays 22A and 22B are not full in step 44, the process proceeds to step 45, where it is determined whether or not the set number has been reached. Returning to the above, the above operations in steps 30 to 45 are repeated, and when the set number is reached, the copying operation is terminated.
[0092]
If it is determined in step 44 that both the first and second trays 22A and 22B are full, the process proceeds to step 46, where both trays are displayed on the display section of the operation panel 76, and the process proceeds to step 47 to stop the copying operation. To do.
[0093]
If it is determined in step 31 that the FD sheet is ejected, the process proceeds to step 38 to switch to FD sheet ejection, and the operation according to steps 39 to 43 in which the A mode in steps 32 to 37 is changed to the B mode and the B mode is changed to the A mode. The process proceeds to step 44 where the copy operation is completed through the same process as described above, or the copy operation is stopped.
[0094]
If it is determined in step 30 that single-sided copying is performed, the process proceeds to step 50, and the same operations of steps 51 to 56 or steps 57 to 62 in which single-sided copying operation is performed instead of the double-sided copying are performed to reach step 44. Similarly, the process returns to step 30 or proceeds to step 46 to display that the tray is full on the display unit of the operation panel 76 and stops the copy operation in step 47. If it is determined in step 44 that both trays are not full, the process proceeds to step 45, and if it is determined that the copy has reached the set number of sheets and the copying is finished, the copying operation is terminated.
[0095]
Needless to say, the operations in steps 30 to 47 can also be applied to the image forming apparatus of the first embodiment.
[0096]
In the A-mode copy, as described in the first embodiment, as shown in FIG. 3, for example, when copying of n pages (n is an even number) is performed on the photosensitive drum 10. The even-numbered page color toner image and the odd-page color toner image formed on the toner image receiver 14a are transferred to the front and back of the recording paper P to form a double-sided image. The control unit 70 controls the image data read from the image memory 71 to be read in the order of the first page → second page → third page →... → n−1 page → n page. As a result, image formation and discharge are performed in the same page order. Further, this cycle is repeated for the set number of copies.
[0097]
In the B mode copy, the recording paper P is turned over and discharged to the second tray 22B outside the apparatus. As a result, as shown in FIG. 4, for example, when copying of n pages (n is an even number), a color toner image of odd pages is formed on the photosensitive drum 10, and the toner image receiver 14a is formed. Is formed with an even page color toner image and transferred to the front and back of the recording paper P to form a double-sided image. The control unit 70 controls the order of image data read from the image memory 71 in order of the second page → first page → fourth page → third page →... → n page → n−1 page. 70 controls. As a result, image formation and discharge are performed in the same page order. Further, this cycle is repeated for the set number of copies.
[0098]
C mode for single-sided image formation, where the copy is ejected to the first tray 22A with the toner image surface facing up (face up), and the copy is reversed and the toner image surface is placed down (face down) to the second tray 22B In the D mode of single-sided image formation for discharging, a simple method is used in which the toner image is formed only on the photosensitive drum 10 and is not formed on the toner image receiver 14a.
[0099]
When m copies are made on a large number of sheets, for example, n pages, in the C mode, as shown in FIG. 5 (a), the nth page copy forms and discharges a color toner image. A copy of the first page is discharged to the top with the color toner image surface facing up. Therefore, the control unit 70 must control the image data output from the image memory 71 so as to be performed in the order of page n → page n−1 →→→ page 2 → page 1. However, since the second embodiment has the document reading device 50, the document D is stacked on the document placing table 60A in the page order from the upper side with the document D stacked in the page order facing upward. It is read from the nth page as a document. Thus, when image formation is performed according to the reading order, image formation and discharge are performed in the same page order, and control becomes easy. However, when n is an odd number, the first page to be read is completely white (no image), so image formation is performed from page n-1.
[0100]
Further, when m copies are made on a large number of sheets, for example, n pages, in the D mode, as shown in FIG. Are ejected to the top with the color toner image surface facing up. Therefore, the control unit 70 controls so that the image data output from the image memory 71 is processed in the order of the first page → second page →... → n−1 page → n page. As a result, image formation and discharge are performed in the same page order.
[0101]
Although the present invention has been described using a color double-sided image forming apparatus, it is of course applicable to a monochrome double-sided image forming apparatus. Further, the present invention is not limited to this method, and includes a modified example in which a double-sided image is formed. For example, after reversing the toner polarity corresponding to the back side image disclosed in Japanese Patent Publication No. 54-28740, the transfer material is simultaneously used. The face-up and face-down paper discharge sections are also used for tandem systems such as those that are transferred to both sides of the above, and tandem methods such as JP-A 63-180969, JP-A 63-298255, and JP-A 1-444457. By using the control means that is provided and the process conditions and the image data processing conditions described above are changed between the front surface and the back surface, it is possible to form a double-sided image that does not require page alignment as post-processing.
[0102]
【The invention's effect】
  Claim 12According to the image data transfer order, output order, and discharge mode, there is no need for a conventional double-sided reversing paper feed device or intermediate stacker, and both face-up paper discharge and face-down paper discharge are used. A double-sided image with alignment can be output. In addition, the fixing device only needs to be passed once, and the transfer material is transported with high reliability. In particular, in the case of color image formation, high-speed formation of a good double-sided color image with little color misregistration and image deterioration is achieved. . Further, the first and second paper discharge means are provided, and when one of the paper discharge trays becomes full, it is automatically switched to the other paper discharge tray, so that a large amount of printing can be performed quickly.At the same time, face-up discharge or face-down discharge can be performed with the page aligned in the same manner as the discharge tray before switching.There is an excellent effect.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram of a color double-sided image forming apparatus according to a first embodiment of a double-sided image forming apparatus of the present invention.
2 is a side sectional view of the image carrier in FIG. 1. FIG.
FIG. 3 is a diagram illustrating a double-sided image forming state in A mode.
FIG. 4 is a diagram illustrating a double-sided image formation state in a B mode.
FIG. 5 is a diagram illustrating a single-sided image formation state related to a C mode and a D mode.
FIG. 6 is a block diagram showing various mode selection and control systems in the color double-sided image forming apparatus of the first embodiment.
FIG. 7 is a flowchart showing a copying process in each mode of the color image forming apparatus of the first embodiment.
FIG. 8 is a cross-sectional configuration diagram of a color double-sided image forming apparatus according to a second embodiment of the double-sided image forming apparatus of the present invention.
9 is a cross-sectional view showing an example of the configuration of the image reading apparatus in FIG.
FIG. 10 is a block diagram showing various mode selection and control systems in the color double-sided image forming apparatus of the second embodiment.
FIG. 11 is a flowchart illustrating a copying process in each mode of the color image forming apparatus according to the second embodiment.
[Explanation of symbols]
10 Photosensitive drum
11 Scorotron charger
12,121 Exposure unit
13 Developer
14a Toner image receiver
14c Transfer device
14g Back transfer device
17 Fixing device
21A Face-up exit
21B Face-down exit
22A First tray
22B Second tray
23A, 23B Paper discharge detection sensor
24A, 24B Paper discharge amount detection sensor
30 FU / FD switching part
30a Paper discharge switch
50 Image reader
50A Document feeder
50B Document reader
P Recording paper

Claims (2)

An image memory for storing image data of a plurality of pages, a mirror processing circuit for changing the image data output from the image memory to a mirror image, a photoconductor for forming a toner image, and a toner image formed on the photoconductor A toner image receiver to be transferred and held and a toner image are sequentially formed on the basis of image data output from the image memory, and the toner and the toner are formed on both the front and back sides of the recording paper in one pass. Recording means for transferring the toner image on the image receiver, fixing the toner images on the front and back sides of the recording paper at a time to perform double-sided printing recording, and the front and back states after transferring the double-sided print output by the recording means A first sheet discharge unit that sequentially stacks and discharges the sheet as it is; a second sheet discharge unit that sequentially stacks and discharges the two-sided print output by the recording unit after inverting the front and back states; Second delivery hand Paper discharge selection means for selecting and switching the order of even / odd pages of the image data output from the image memory in accordance with the selection operation of the paper discharge selection means, and control for controlling whether or not to pass through a mirror processing circuit A double-sided image forming apparatus comprising:
It has an operation panel for specifying single-sided printing or double-sided printing and face-up discharge or face-down discharge,
A mode as an image forming method to be executed when double-sided printing and face-up paper discharge are designated on the operation panel, and B as an image forming method to be executed when double-sided printing and face-down paper discharge are designated. Mode, C mode as an image forming method to be executed when single-sided printing and face-up paper discharge are specified, and D mode as an image forming method to be executed when single-sided printing and face-down paper discharge are specified Have
In the A mode, when printing n pages (n is an even number), the control means reads the image data from the image memory in order from the first page to the nth page, and even-numbered toner. An image is formed on the photoconductor, an odd-numbered toner image is formed on the toner image receiver, and the toner images formed on the photoconductor and the toner image receiver are transferred to the front and back of the recording paper. The image is formed by double-sided printing of the odd-numbered page with the odd-numbered toner image down and the even-numbered page next to the odd-numbered page. Then, the second recording paper is placed on the first recording paper, and is discharged to the first tray so that the toner image surface of the even page of the last recording paper is the uppermost surface. To control and
In the B mode, when printing n pages (n is an even number), image data is sequentially read from the image memory as the second page, the first page, the nth page, and the n-1 page, An odd-numbered toner image is formed on the body, and an even-page toner image is formed on the toner image receiver and transferred to the front and back of the recording paper to form a double-sided image. Control to reverse the front and back and discharge the face down to the second tray.
In the C mode, when printing n pages, image data is output from the image memory sequentially from the nth page to the first page, and a toner image is not formed on the toner image receiver. The toner image on the photosensitive member is transferred to the recording paper, the nth recording paper is first ejected with the toner image facing upward, and finally the first recording paper is transferred to the toner image. Is controlled to discharge face up to the first tray so that
In the D mode, when printing n pages, the image data is output from the image memory in order from the first page to the nth page, and the toner image is not formed on the toner image receiver. The toner image on the photosensitive member is transferred to the recording paper, and is reversed so that the toner image surface faces down and is discharged face down to the second tray .
And detecting means for detecting the amount of paper discharged to the first and second paper discharge means. The detection means counts the number of paper discharged to the first and second paper discharge means, and the count is predetermined. When the count of the first paper discharge means is invalidated, and the selection of the paper discharge selection means is the first paper discharge means, the first paper discharge means to the second paper discharge means. Or when the selection of the paper discharge selecting means is the second paper discharge means, the second paper discharge means is switched to the first paper discharge means and the mode as the image forming method is switched. ,
A double-sided image forming apparatus. The mode is switched from the A mode to the B mode, from the B mode to the A mode, from the C mode to the D mode, or from the D mode to the C mode. The double-sided image forming apparatus according to claim 1.

Images