JPH07306620A - Image forming device - Google Patents

Abstract

PURPOSE:To improve the cleaning failure of a moving body and the instability of image quality in double-side printing by eliminating a mold lubricant adhering to the image face of a transfer sheet so as to be shifted to the moving body. CONSTITUTION:An oil eliminator 50 is disposed opposedly to a driving roller 9 for driving a moving body 7 holding and moving a toner image or a sheet to which the toner image is transferred. The oil eliminator 50 is provided with oil eliminating members (silicon roll, web, brush, and the like) so as to eliminate the mold lubricant, adhering to the surface of the transfer sheet, at the time of coming in contact with the transfer belt 7. The oil eliminator 50 can be connected to the stepping motor of an image forming device, and an approaching/separating rotary shaft 54 and a cam 56 are rotated according to image forming operation so as to rotate the oil eliminator 50, thus putting the oil eliminator in operating state. As to operation timing. the oil eliminating member comes in contact before the position of the transfer belt 7 with a first second-face printing sheet placed thereon reaches the position of the oil eliminator 50 and is kept in contact until at least the end of a double-side printing job. Toner remaining without receiving the cleaning action of a cleaning device is eliminated, and mold lubricant is also eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for transferring a toner image formed on a photoconductor, and in particular, a release agent is applied to prevent toner offset on a fixing roll or a pressure roll. The present invention relates to an image forming apparatus that includes a fixing device described above and that uses a moving body for attracting and conveying a transfer image or a transfer sheet.

[0002]

2. Description of the Related Art A transfer sheet is electrostatically adsorbed on an insulating transfer belt or the like which runs in synchronization with an image forming means, conveyed to a transfer position of the image forming means, and an image is formed by an electric field from the back surface of the insulating transfer belt. An image forming apparatus that transfers the transfer toner formed on the forming means onto a transfer sheet is disclosed in US Pat. No. 25768.
82 and US Pat. No. 3,357,325. Further, in an image forming apparatus that forms a color image using a plurality of photoconductors, an insulating transfer belt is used as a transfer paper conveying unit, and the toner images are superposed as a merit of the method of sequentially transferring the transfer images to the transfer paper. In this case, since the weight of the toner becomes large, a large amount of transfer charge is required, and therefore, it is possible to have a large transfer charge holding capacity corresponding to this.

In this type of image forming apparatus, a corona discharger for electrostatically adsorbing a transfer sheet to an insulating transfer belt and a corona discharge from the back surface of the insulating transfer belt to generate a transfer electric field to transfer a transfer toner image. A corona discharger,
An AC corona discharger that removes static electricity from the transfer paper after the transfer from the belt is removed, and an AC corona discharger that removes static electricity from the belt are provided.

On the other hand, it is known that a part of the release agent (silicon oil or the like) supplied to the fixing roll or the pressure roll is transferred to the transfer sheet fixed by such a fixing device. The oil transferred to the transfer paper diffuses into the paper fibers between the toner particles or through the pinholes in a relatively short time. In addition, the oil transferred to the surface of the paper without the toner image, that is, the oil transferred directly to the surface of the paper, also diffuses into the paper fibers and has almost no effect on the operation of the image forming apparatus or the image quality. there were. However, a color image forming apparatus, particularly a color image forming apparatus that reproduces a large number of colors by superposing toners of three or four colors, is greatly different from the conventional single color image forming apparatus in the following points. 1. The toner layer to be fixed is thick in order to reproduce a large number of colors by superposing toners. 2. In order to mix toners of different colors by fixing and to develop a color, they must be sufficiently heated and fluidized. The above point has become a condition that an offset phenomenon easily occurs in the fixing device.

In order to prevent such an offset phenomenon, a fixing device having a high releasability is required in the color image forming apparatus. For this purpose, a fixing device is used in which a large amount of a release agent, that is, silicon oil or the like is applied as a release layer to a fixing roll coated with a rubber-like elastic body such as silicon rubber. Further, as the printing speed of the full-color image forming apparatus becomes faster, it is necessary to stably supply a large amount of oil to the rolls in order to improve the reliability of the fixing device. Further, it has been clarified by measurement that the amount of silicone oil supplied to the transfer paper also depends on the image density. For example, when a blank print with no image is taken and the amount of oil supplied to the transfer paper is about 15 μl per sheet, the amount of silicon oil supplied to the transfer paper increases as the image density increases. As the image density reaches 80%, about 20 μl of silicon oil is supplied per sheet. This is considered to be an increase due to the silicone oil permeating the toner or adhering to the toner surface in addition to the silicone oil supplied to the transfer sheet itself.

From the above, when a large amount of silicone oil is supplied to the fixing device, especially when an image having a high image density such as a photograph or a chart is printed, a large amount of silicone oil exists on the toner in the image portion. become. Since toner particles are sufficiently melted and coalesced in the portion where the image density is high, silicon oil remains on the toner surface for a relatively long time without diffusing into the paper fibers through the toner particles. . When a single-side printed sheet in such a state is circulated in the image forming apparatus for double-sided printing, the silicone oil adhering to the sheet adheres to the conveyance roll, transfer belt, photoconductor, etc. of the sheet conveyance path. I will end up.

On the other hand, on the surface of the belt which conveys the transfer paper, when the transfer paper is jammed or when the transfer image on the photosensitive member is out of the transfer paper, the toner of the portion protruding to the surface of the belt Therefore, a cleaning means for cleaning the front surface of the belt is generally provided because the back surface of the subsequent transfer paper may be contaminated and adhered to the rear surface. Also,
In an image forming apparatus that forms a color image using a plurality of photoconductors, positional deviation of the transfer paper in the feed direction is likely to occur. As means for avoiding this, JP-A-63-30
As disclosed in Japanese Patent No. 0263, etc., a registration mark for registration correction is transferred onto a transfer belt, a mark position is read by a CCD sensor or the like, and each color is automatically aligned. , JP-A-63
In JP-A-279275, JP-A-63-279276 and JP-A-61-53756, after a registration mark for registration correction is transferred, the position of the registration mark is read by a photo sensor or the like, and at the same time, a photo sensor is used. A method of providing a batch image in which the toner density of each color is controlled according to the output of the sensor is disclosed, and these marks were finally cleaned.

As a means for cleaning the toner transferred onto the transfer belt as described above, various blades, fur brushes, webs, and combinations of these have been proposed, but considering cleaning efficiency and the like. The blade method was the most suitable. When automatic double-sided printing is created with a full-color image forming device, silicon oil attached to the image side (first side) of the transfer sheet is transferred to the transfer belt, and silicon oil attached to the back side (second side) is transferred to the photoconductor. . As a result, the coefficient of friction between the cleaning blade and the transfer belt varies greatly between the area where the silicone oil is attached on the transfer belt and the other areas. That is, the friction coefficient between the cleaning blade and the transfer belt in the area (portion) where the silicone oil adheres is extremely small, but the friction coefficient between the cleaning blade and the transfer belt in the area where the silicone oil does not adhere is extremely small. Due to this large variation in the friction coefficient, a stick-slip phenomenon of the cleaning blade occurred. As described above, the registration mark for registration correction, the patch image for density control, and the untransferred toner when a paper jam occurs on the transfer belt are cleaned with the cleaning blade of the transfer belt cleaner. When the cleaning blade is vibrating due to such an extreme stick-slip phenomenon, the cleaning blade does not contact the transfer belt, and the toner on the belt passes through the cleaning blade. With the toner remaining on the belt, the next job is performed. Residual toner due to poor cleaning on the transfer belt
Was transferred to the back side of the transfer paper in the adsorption area and transfer area, and became the dirt on the back side of the paper.

[0009]

The poor cleaning of the transfer belt due to the double-sided printing often appears more notably during the double-sided printing job, but after the double-sided printing is completed and after shifting to the normal single-sided printing. . Therefore, the cleaning that causes the cleaning failure of the transfer belt
The strain of the Ning blade, especially the change of the strain depending on the printing condition such as single-sided printing and double-sided printing was measured by a gauge. The measurement result is shown in FIG. The operation area for double-sided printing is DA, and the operation area for single-sided printing is SA. As shown by this result, when the one-sided printing is continued for a while after the double-sided printing area DA is transferred to the one-sided printing area SA, the variation of the distortion of the cleaning blade is further increased. This is because the stick-slip phenomenon is accelerating. This phenomenon is considered to be the result of the silicone oil adhering to the transfer belt being reversely transferred to the sheet at the time of single-sided printing after shifting to single-sided printing, and the silicone oil on the transfer belt gradually decreasing. In this way, the amount of silicon oil on the transfer belt causes fluctuations in the distortion of the cleaning blade.

Further, when the one-sided printing is further continued, the fluctuation of the distortion of the cleaning blade is gradually reduced and returns to the original state. In this way, when the degree of occurrence of cleaning failure is slight, the cleaning failure may disappear by continuing single-sided printing. However, when double-sided printing is resumed, the above phenomenon is repeated. Also, while repeating double-sided printing,
It was also confirmed that the silicone oil adheres to the entire area on the transfer belt, so that the fluctuation of the distortion of the cleaning blade is reduced, and the cleaning failure hardly occurs. This is the fact that the variation of the amount of the release agent deposited on the surface of the moving body (transfer belt) due to the area of the release agent causes the variation of the distortion of the cleaning blade to cause the cleaning failure.

The present invention has been made on the basis of such a background, and by removing the release agent that causes the cleaning failure transferred from the image side (first side) of the transfer sheet, the transfer is performed during double-sided printing. It is intended to eliminate the fluctuation of the distortion of the cleaning blade due to the release agent on the body surface, improve the cleaning accuracy of the surface of the moving body, and maintain stable image quality.

[0012]

Cleaning means for cleaning a transfer image on a moving body for holding and moving a toner image or a transfer sheet on which the toner image is transferred,
The image forming apparatus of the present invention, which has a fixing unit that fixes the toner transferred to the transfer sheet while applying the release agent, includes a removing unit that removes the release agent remaining on the surface of the moving body via the transfer sheet. The releasing agent removing means is provided so as to be capable of coming into contact with and separating from the surface of the moving body and removing the releasing agent on the surface of the moving body when it comes into contact with the surface of the moving body.

Further, the removing means for removing the release agent has a structure in which when the double-sided printing is selected, it is brought into contact with the moving body during the double-sided printing operation and for a fixed time after the operation.

Further, the detection means has a detection means for detecting the frictional state between the cleaning means and the moving body, and a control means for outputting a drive signal to each drive section in response to a detection signal from the detection means, and the detection means is a predetermined one. The control means outputs a drive signal to the release agent removing means when the change more than the change in the frictional state is detected, and the release agent removing means is brought into contact with the surface of the moving body for a certain period of time.

[0015]

In the double-sided print mode, the transfer sheet printed on the first side and passing through the fixing device and coated with silicone oil transfers the release agent to the surface of the moving body when copying the second side. To do. The residual toner on the transfer sheet is removed by the cleaning means, and the release agent adhering to the surface of the transfer sheet is removed by the removing means. Means clear
The training action is uniformly performed on the entire surface of the moving body. As a result, a stable image is obtained, and stains on the transfer paper are avoided.

[0016]

Embodiments of the present invention will be described with reference to the drawings. Embodiment 1 FIG. 8 is a full-color image forming apparatus to which a transfer device according to an embodiment of the present invention is applied. The full-color image forming apparatus includes image carriers (photosensitive drums) 2Y, 2M, 2C and 2K rotatably supported by a rotation shaft, and image forming means is arranged on the outer peripheral portion of each image carrier. The image forming means may be any means, but the image forming means shown in this embodiment is color-separated with primary chargers 3Y, 3M, 3C and 3K that uniformly charge the surface of the photosensitive drum to −500 to 800V, for example. Exposure means for irradiating a light image or a light image corresponding thereto to form an electrostatic latent image on the photosensitive drums 2Y, 2M, 2C, 2K, for example, exposure means including a laser beam exposure device (not shown) And the photosensitive drums 2Y, 2M, 2C,
Developing devices 5Y, 5M, which visualize the electrostatic latent image on 2K,
It is equipped with 5C and 5K. Developing devices 5Y, 5M, 5C,
5K contains developer such as four color toners of yellow, cyan, magenta and black, and each toner is irradiated with a laser beam on the portion of the uniformly charged photosensitive drum where the electrostatic latent image is formed. The developing conditions such as the developing bias are selected so that the toner adheres.

The visible image (toner image) developed on the photosensitive drum is a drive shaft 9 and shafts 10 to 1 which are driven together with the drive shaft 9.
The image is transferred onto the transfer sheet 70 conveyed by the transfer belt conveying device which moves in the direction of arrow A by 2. Paper feeder 3
The transfer paper 70 supplied from 00, 305, 310 is
The transfer belt 7 is attracted to the transfer belt 7 by the suction corona discharger 14 and is sequentially transported to the transfer position provided facing each image carrier. There is a paper suction roll installed on the opposite side of the transfer belt 7, and charges the transfer paper 70 to attract the transfer material (paper) to the transfer belt. In the transfer device, different voltages (for example, a voltage of + 4.2KV to 12.0KV) are applied to the suction corona discharger 14 and the transfer corona dischargers 8Y, 8M, 8C, and 8K, and the transfer current is +50 μA to +2000 μA. ing. The transfer sheet 70 after the transfer is completed by a corona discharger 29 to which a DC bias of AC oscillation for weakening an electrostatic attraction force with the transfer belt 7 can be applied, and a peeling claw 21 made of an insulating member such as resin. It is separated from the transfer belt 7 and guided to the fixing device 100.

The transfer belt 7 has a corona discharger 23 for removing the inner belt and an outer belt for removing the charge, which is provided so as to sandwich the transfer belt between the most downstream of the transfer process and the most upstream transfer process after the transfer paper 70 is peeled off. Corona discharger 2
The charge is removed by 4. The corona discharger for belt neutralization is an AC corona discharger to which a DC bias of AC oscillation can be applied, like the peeling means 29. The surface of the transfer belt 7 from which the charge has been removed is cleaned by the cleaning means (device) 20 of the transfer belt, and the adhering silicon oil is removed by the oil removing device 50 to start a new circulation.

The cleaning device 20 for the transfer belt is provided on the downstream side of the charge-eliminating corona dischargers 23, 24. From the surface of the transfer belt which has been subjected to the discharge, registration marks for registration correction and toner image patches for density control are provided. , Remove untransferred toner and the like when paper is jammed. Transfer belt clear
The cleaning device 20 mainly includes a cleaning brush 25 as an auxiliary means for cleaning, a cleaning blade 26, a recovery toner box 28 for storing the cleaned toner, and the like.

The transfer belt oil removing device 50 is a clear
The release agent is disposed on the downstream side of the cleaning device 20 and removes the release agent transferred to the surface of the belt 7 via the transfer paper 70. The oil removing device 50 is disposed on the surface of the transfer belt 7 so as to be able to come into contact with and separate from it, and is provided with an oil removing member 55, a tracking roll 53 for positioning the oil removing member, and the like. As shown in FIG. 14, the transfer belt 7 uses a material having a high insulating property such as a polyethylene terephthalate (PET) film, a polyvinylidene fluoride resin film, a polyester film, a polycarbonate film, and a polyether ether ketone film. It is an endless belt body having both ends thereof, for example, ultrasonically welded after being cut to a predetermined size, and a transfer sheet is placed and conveyed. Further, a mark 75 for position detection is provided.

Next, the flow of the transfer sheet 70 in the double-sided print mode in the image forming apparatus having the above configuration will be described.
The paper transport system for transporting the paper 70 includes a double-sided dedicated transport unit 210 for transporting paper during double-sided printing, and a paper feed tray 30.
A feed side conveyance path 220 for guiding the paper 70 from 0 to the transfer belt 7, a paper reversing conveyance path 230 for guiding the paper 70 passing through the fixing device 100 to the double-sided exclusive conveyance section 210, and a paper for which double-sided printing has been completed. And a carry-out side transport path 240 that leads to the discharge tray. According to this transport path system, the paper 70
Is sent out from the paper feed trays 300, 305, 310 of various sizes to the supply side conveyance path 220 by the feed roll 301, the conveyance roll 302 and the like. The paper 70 that advances along the supply conveyance path 220 by the conveyance roll 221 is a registration gate 225.
After being once positioned, the sheet is supplied onto the transfer belt 7 at a predetermined timing. The sheet 70 is electrostatically attracted to the transfer belt 7, moves as the transfer belt 7 advances, and toner images of respective colors are sequentially transferred from the four photoconductors 2Y, 2M, 2C, and 2K to the surface thereof. On the sheet 70 separated from the transfer belt 7 by the separation claw 21, the toner image is heated and fixed by the fixing device 100. At that time, in order to prevent the toner image from being offset to the fixing roll 105 or the pressure roll 110, a large amount of a release agent such as silicon oil is applied to the surface of the paper. In the case of single-sided printing, the sheet 70 is provided at the intersection of the carry-out side transport path 240 and the paper reversing transport path 230, and the switching gate 235 for selecting one of the transport paths is switched to the carry-out side transport path 240, and the transport roll 241 is selected. Is discharged through the carry-out side transport path 240.
In the case of double-sided printing, the switching gate 235 is switched in the direction of the sheet inversion conveyance path 230. Then, the sheet 70 is sent to the sheet reversing conveyance path 230, the front and back sides of the sheet are reversed on the way through the conveyance path, and the sheet 70 is sent to the double-sided conveyance section 210. This sheet advances to the upstream side of the image forming apparatus by the conveyance roll 221, is fed again to the transfer belt 7, and the toner image is transferred to the back surface (second side) of the sheet. This full-color image forming apparatus has an image memory for a maximum of two sheets of paper size. The image reading apparatus first stores the image of the first side of the original, then the image of the second side of the original, and then the image forming operation. Enter

The supply of paper onto the transfer belt 7 will now be described. In the single-sided print mode, the transfer paper 70 is continuously supplied in the belt traveling direction on the transfer belt 7. In the double-sided print mode, after the first transfer sheet 70 is supplied, the second sheet is supplied at an interval of one sheet (dimension). After the transfer belt 7 is intermittently supplied for one rotation of the transfer belt 7, the transfer paper for the first surface is intermittently supplied for the second lap, and the first surface is printed at the provided intervals. Then, the paper is circulated in the apparatus and the reversed paper is supplied to print the second side of the original. With this configuration, the image forming apparatus according to this embodiment can continuously perform automatic double-sided printing without having a dedicated double-sided stack tray. Hereinafter, this type of device is referred to as a trayless device.

In addition, as an image forming apparatus having a double-sided printing function, as shown in FIG.
On the downstream side of 0, a double-sided stack tray 350 that temporarily stores the paper on which the first side has been printed is provided, and
There is an image forming apparatus provided with a so-called double-sided stack tray 350, which is provided with a feed roll 351 and the like that feeds the paper from the double-sided stack tray 350 to the double-sided transport unit 210. In this case, all the sheets for which printing on the first side has been completed are temporarily stored in the intermediate tray 350, and when the preparation for the second side is completed, the sheets are continuously fed from the double-sided stack tray 350 and the second side is transferred. . Hereinafter, this type of device is referred to as a stack tray equipped device. This image forming apparatus does not need to have an image memory for a maximum paper size of two sheets. Further, other configurations are similar to those of the trayless device.

In the present embodiment, in addition to the above-mentioned structure, a reflection type optical sensor 40 including a light emitting portion and a light detecting portion is provided as a position detecting means of the joint 71 of the transfer belt 7.
Since the joint 71 formed on the transfer belt 7 is ultrasonically welded, the permittivity of this joint portion is different from that of the other portions of the belt. Since the amount of electric charge applied to the transfer sheet at the time of transfer is different from that of the other portions due to the different amounts of the inductivity, there is a problem that the density of the transferred image changes only at the joint portion. In order to avoid this problem, JP-A-62-269160 discloses that a hole or mark 75 is provided at a fixed position from the seam of the transfer belt, and the hole or mark 75 is detected by an optical sensor 40 to connect the transfer belt. 71. A method of recognizing the position, a pulse generator that generates a pulse signal each time the transfer belt moves by a predetermined amount, and a counter that counts the pulse signal, There is proposed a method (called a panel division method) in which the number of image areas is equally distributed and the image areas are determined. Therefore, the image forming apparatus of this embodiment forms a plurality of image areas (panels) by dividing the transfer belt at equal intervals while avoiding joints for each size of transfer sheets by this panel division method, and forming one area (hereinafter referred to as “area”). Place one copy sheet on the panel),
An integral number of transfer sheets are always arranged around the transfer belt, and the joint 71 of the transfer belt 7 is connected to the transfer belt 7.
So that it is located approximately in the center of the gap between the upper sheets,
The optical sensor-40 detects the joint 71, and the joint 71
The transfer paper is sent out at a timing that avoids the above, and the gap between the papers is controlled to be constant. The panel partitioning method configured as described above maximizes productivity without causing a problem in image quality. Further, in the image forming apparatus, when the number of divided panels is determined according to the panel division of the transfer belt 7,
A pitch reset signal is generated according to the number of panels. The pitch reset signal is a signal that is synchronized with the number of divided panels that occurs periodically while the same size of paper is being conveyed. The pitch reset signal detects the stop position of the transfer belt 7 at the end of the job, and the joint 7 of the transfer belt 7 is detected.
Whatever the position of 1 is, the next image forming operation is started with the rising time with the least loss. For example, when the length of the transfer belt is 1920 mm and the number of divided panels is 8, if the process speed is 160 mm / sec, a pitch reset signal for each panel is generated every 1.5 seconds (1920/8 160).

Here, the transfer belt 7 is divided into panels, and the transfer paper 7 is transferred onto the transfer belt 7 during double-sided printing.
The supply of 0 will be described with reference to the drawings. The transfer belt 7 shown in FIGS. 10 to 13 has a plate shape in which the transfer belt 7 which has an endless shape by the joint 71 is expanded one round for convenience,
It is shown with the joint 71 at both ends. In the case of even-numbered panel division, the total length of the transfer belt 7 is evenly divided into, for example, 8 equal parts, and in the case of odd-numbered division, the total length of the transfer belt is divided into odd parts and divided into, for example, 7 equal parts. Panel 8 Then, the pulse signal 45 is transmitted for each panel. Transfer paper is supplied onto the transfer belt 7 configured as described above. 1 of the paper here
A sheet printed on the first side (front side) is represented by S, and a sheet printed on the second side (rear side) is represented by D.

Supply of transfer paper in the case of a trayless device (1) Dividing even-numbered panels. See FIGS. 10 and 11. FIG. 10 shows division into 8 panels during double-sided printing in an image forming apparatus having a double-sided printing mechanism by a trayless device. The state of supplying the first and second sheets of paper onto the transfer belt 7 is shown. Printing conditions, used paper; A4 size, orientation; horizontal placement, number of prints; 10 sheets.
On the first lap, the sheets S1, S2, S of the first side are placed at the positions of the odd-numbered panels of panel 1, panel 3, panel 5, and panel 7.
3 and S4 are supplied from the paper feed tray to copy the first side of the original. At this time, panel 2, panel 4, panel 6 and panel 8, which are even panels, are skipped. On lap two,
Sheets S1, S2, S3, S4 printed on the first side of the paper in the first lap circulate in the apparatus at the positions of panel 2, panel 4, panel 6, and panel 8, which are even panels skipped in the first lap. And flip it over to print the second side D1
D2, D3, and D4 are supplied from the double-sided dedicated transport path 210. The second side of the document is transferred onto the sheets D1, D2, D3 and D4. On the other hand, at the positions of panel 1, panel 3, panel 5, and panel 7, which are odd-numbered panels, new paper S
5, S6, S7 and S8 are supplied from the paper tray 300, and the first side of the original is printed. In this way
In the next round, the paper for the second side is supplied to the panel position skipped in the previous round. By supplying the paper in this manner, the double-sided printing of 10 papers is completed after the transfer belt 7 makes four turns. In this embodiment, the sheet is supplied from the panel 1 position of the belt 7, but the first sheet supply panel may be any position from the panel 1 to the panel 8. That is, if the first-side sheet S is supplied from the odd panel (or even panel), the second-side sheet D is always supplied to the even panel (or odd panel). Then, the silicone oil applied while the paper is passing through the fixing device 100 is transferred from the paper to the transfer belt or the photoconductor during the image formation. At this time, since the printed paper to which oil has been attached and which has passed through the fixing device supplied onto the belt 7 is supplied every other panel, the silicon oil applied to the paper is always supplied to the belt 7 every other panel. Will be supplied to.

As described above, in the example in which the belt 7 is divided into the even-numbered panels, the panel on which the silicon oil is always adhered and the panel which is not adhered are determined on the transfer belt 7, and therefore, the even-numbered panel is used in the next double-sided print job. The first sheet S1 is supplied from the position of a certain panel 2 (see FIG. 1).
1). In this way, in the first double-sided print job, the new paper S is always supplied to the positions of the panel 2, panel 4, panel 6, and panel 8, which are the even-numbered panels to which the silicone oil is always attached. In a cycle, in the first double-sided print job, the paper that has always been printed on the first side at the positions of odd-numbered panels that were not always coated with silicone oil, that is, panel 1, panel 3, panel 5, and panel 7. D is supplied. Further, in the next double-sided print job, the first sheet S is supplied again from the position of the odd-numbered panel 1. In this way, the first sheet S of the job start
By changing the supply panel for each job and repeating the double-sided print job, 2
The surface paper D is supplied, so that the silicone oil adheres to all the panels of the transfer belt. As a result, the coefficient of friction of the cleaning blade 26 with respect to the transfer belt 7 is relatively low and stable, and cleaning failure is less likely to occur. In the embodiment in which the transfer belt 7 is divided into even-numbered panels as described above, when the paper S is supplied from any odd-numbered panel (even-numbered panel) in the first double-sided print job, one of the subsequent double-sided print jobs is determined. The paper S may be supplied from the even-numbered panel (odd-numbered panel). At this time, the pitch reset signal 45 is used to recognize the position of each panel.

(2) In case of odd panel division ... FIG.
The figure shows the joint 7 during double-sided printing in an image forming apparatus with a double-sided printing mechanism using a trayless device.
7 shows a state in which the first and second sheets of paper are supplied onto the transfer belt 7 divided into seven panels each having No. 1. Printing conditions Paper used: A4 size, orientation: Horizontal placement, number of prints: 10 sheets. On the first lap, the sheet S of the first surface is placed at the positions of the even-numbered panels, panel 2, panel 4, and panel 6.
1, S2, S3 are supplied from the paper tray 300. At this time, panel 1, panel 3, panel 5, and panel 7, which are odd panels, are skipped. On the second lap, new sheets S4, S5, S are placed at the positions of panel 1, panel 3, panel 5, and panel 7, which are the odd-numbered panels skipped on the first lap.
6 and S7 are supplied from the paper tray 300, and the first side of the original is copied. At the same time, the sheets S1, S2, S3 printed on the first side of the sheet in the first lap circulate in the apparatus and are reversed,
Sheets D1, D2, and D3 are supplied from the double-sided dedicated transport path 210 to the panels 2, 4, and 6. Paper D
The second surface of the document is transferred to 1, D2 and D3. This paper is continuously supplied, and double-sided printing on 10 sheets is 4
It ends in a lap. As described above, the paper feeding operation is the same as in the case of even-numbered panel division, but the number of panel divisions of the belt 7 is odd, and the first side and the second side of the transfer sheet are alternately arranged in all the panel positions in the double-sided print job. Since the first paper S1 on the first side is supplied to any panel position, the supply position of the new paper is sequentially displaced as the belt 7 goes around, and the silicon oil is automatically attached to all the panels.

Equipment for stack tray equipped on both sides .
See 3 The transfer belt 7 is divided into 8 panels. The A4 size transfer sheet is placed horizontally, and the number of prints is set to 5, for example, and the supply state of the first and second side sheets onto the transfer belt 7 during double-sided printing will be described. On the first lap, the transfer sheets S1, S2, S3, S4 from the paper feed tray are transferred onto the transfer belt 7.
S5 5 sheets in succession, Panel 1, Panel 2,
Supply to panel 3, panel 4 and panel 5. The first side of the manuscript is printed and stacked on the double-sided stack tray 350. On the (N + 1) th round, when the preparation for the second side is completed, the sheet is inverted and sent out from the double-sided stack tray 350, and is supplied to panel 1, panel 2, panel 3, panel 4, panel 5, and the original document Transfer the second side of paper 2
Do it face to face. For example, if the number of prints is 5 on the 8-division transfer belt, the second side is printed on the second lap of the transfer belt 7, and if the number of prints is 20, then 3
The copy of the first side is completed in the circumference, and the printing of the second side is started from the fourth cycle. In this case, it is not necessary to change the panel division of the transfer belt between the single-sided print mode and the double-sided print mode, and the panel used for the first side print and the panel used for the second side print are necessarily the same. No need. In this case, when two-sided print jobs are continuous, it is possible to appropriately shift the supply panel position of the first sheet of the second side print for each job, or to select the panel position to be shifted according to the number of prints per job. is there. As described above, in the transfer belt 7 of the image forming apparatus for double-sided printing that supplies paper, the printed paper on the first surface, that is, the transfer paper on the second surface is supplied to many areas and adheres to the paper surface. The silicon oil present is transferred to many surfaces of the transfer belt 7.

Next, in this image forming apparatus, the silicone oil adhering to the surface of the transfer belt 7 is removed by an oil removing device 50 provided on the downstream side of the cleaning device 20. Next, the oil removing device 50 in this embodiment will be described.

Oil Removal Device Using Silicon Roller FIGS. 1 to 3 are enlarged views of the portion where the oil removal device 50 is arranged in FIG. The oil removing device 50 is arranged so as to face the drive shaft 9 and is formed on the downstream side of the cleaning device 20 so as to be in pressure contact with the drive shaft 9 via the transfer belt 7. The oil removing device 50 has a tracking roll 53 attached to a roll shaft 52 whose both ends are supported by a frame 51, and a silicon roll pivotally supported by the roll shaft 52 and interlocking with the tracking roll 53. (Oil removal member)
55, and a contact / separation cam 56 that presses the oil removing member 55 toward the transfer belt 7 side. The frame 51 is biased toward the housing 60 via a spring 57. The frame 51 is attached to a contact / separation rotation shaft 54 supported by a housing 60 of the image forming apparatus, and rotates with the rotation of the contact / separation rotation shaft 54. The contact / separation rotary shaft 54 is an idler gear 8
2. The driving stepping motor 80 is connected via a driving roll gear 81.

The oil removing device 50 configured as described above
The operation of will be described. 1 and 3 show an oil removing device 50.
Shows the state of contacting the transfer belt 7 and performing the oil removal operation. A drive roll 9 for rotating the transfer belt 7 of the image forming apparatus is driven by a stepping motor 80 via a drive roll gear 81. Oil remover 50
The contact / separation rotation shaft 54 receives the driving force of the stepping motor 80 from the driving roll gear 81 via the idler gear 82. Furthermore, the driving force of the stepping motor 80 is transmitted to the fixed shaft 58 fixing the contact / separation cam 56 via the electromagnetic clutch 83. The idler gear 82 is connected to the gear 81, the electromagnetic clutch 83 is turned on, and power is transmitted to the contact / separation rotation shaft 54 and the fixed shaft 58, whereby the contact / separation rotation shaft 54 and the contact / separation cam 5 are connected.
Rotate 6. The oil removing device 50 has a contact / separation rotary shaft 54.
Is rotated about the rotation axis in the direction of the belt 7, and the contact / separation cam 56 presses the frame 51 against the urging force of the spring 57 by the rotation of the contact / separation cam 56, and the tracking roll 53. And the oil removing member 55 is pressed to the drive roll 9 side. The tracking roll 53 comes into contact with the driving roll 9 via the belt 7 and is driven thereby, and the oil removing member 55
Position and adjust the pressing force. The drive roll
When a larger pressing force on the roller 9 is required, the rotation of the contact / separation cam 56 is strengthened by providing the torque limiter 85, and the pressing force of the silicon roll 55 in the transfer belt direction is increased. can do. Silicon Roll 55
Touches the surface of the transfer belt 7 and removes the silicone oil adhering to the surface of the transfer belt 7. Further, when separating the oil removing device 50 from the transfer belt 7, the contact / separation rotary shaft 5 is disconnected by disconnecting the idler gear 82.
4 is released from the driving force of the motor. Along with this, the oil removing device 50 rotates the contact / separation rotation shaft 54 by the urging force of the spring 57, separates the oil removing member 55 from the transfer belt 7, and returns it to the initial position.

Next, the operation timing of the oil removing device will be described. In the case of the trayless device (when the double-sided print mode is set) Operation start When the double-sided print mode is set in the oil removing device 50, the sheet on the first side is supplied every other panel. Then, in the second round, the printed sheet is reversed on the first side of the transfer sheet in the apparatus and the second side is supplied as the front side, but the oil removing device 50 transfers from the double-sided print mode setting. The position of the transfer belt 7 corresponding to the head of the one-side printed sheet supplied to the first sheet on the second round of the belt 7 is the oil removing member 5 of the oil removing device 50.
The oil removing device 50 is rotated to bring the oil removing member 55 into pressure contact with the drive roll 9 via the transfer belt 7 until the position where the oil 5 comes into contact with the oil 5 is reached.

End of Operation Basically, the position of the transfer belt 7 corresponding to the trailing edge of the last sheet of the transfer sheet to be printed on the second side is set at the position where the oil removing member 55 of the oil removing device 50 contacts. When passing, stepping mode
The connection with the rotor 70 is disconnected, the oil removing device 50 is returned to the initial position, and the oil removing operation is completed. However, the oil removing device 50 should be finished when the release agent (silicon oil or the like) on the transfer belt 7 is removed. However, the time required for oil removal differs depending on the amount of oil attached to the transfer belt and the oil removal performance of the oil removal member. Experimentally, when a silicone roll is used as the oil removing member 55, after the set number of double-sided prints are completed, the transfer belt 7 of the oil removing device 50 is continuously rotated two to three times, during which the oil removing member is used. When the silicone roll 55 is in contact with the transfer belt 7, almost all the oil is removed.

A device equipped with a double-sided stack tray (when the double-sided print mode is set) Operation start The second side of the sheets stored in the double-sided stack tray after the printing of the first side of the set number of sheets is completed. The first sheet of paper to start printing on is fed onto the belt, and the position of the transfer belt corresponding to the leading edge of the first sheet is set such that the oil removing member 55 of the oil removing device 50 contacts the transfer belt 7. The oil removing device 50 is moved until the contact position is reached, and the oil removing member 55 is pressed against the drive shaft 9 via the transfer belt 7.

At the end of the operation, at least the position of the transfer belt 7 corresponding to the trailing edge of the last print sheet of the second side reaches the position where the oil removing member 55 of the oil removing device is in contact with the transfer belt 7. Operate until
finish. In this case as well, as with the trayless device, the silicone oil is normally removed by rotating the transfer belt 7 a few times after the set number of double-sided prints are completed, depending on the oil adhesion state. Ends with. In the oil removing device having this structure, the silicon roller is used as the oil removing member, but a brush, a scraper or the like may be used.

Embodiment 2 This embodiment shows an example in which a web is used as an oil removing member in an oil removing device (see FIGS. 4 and 5). The oil removing device 500 has a web supply roll 520 supported by a frame 510, a winding roll 525, and a removal roll 530 for pressing the web 550 against the transfer belt 7. The take-up roll 525 is configured to be able to communicate with the stepping motor 800 by a driving roll gear 540. When the oil removing device 500 is brought into contact with the transfer belt 7 by the rotation of the cam 560 and the contact / separation rotation shaft 540, the web 550 as an oil removing member installed in a state of being wound around the supply roll 520 is provided. , The supply roll 520 is pulled out, and the removal roll 530 is swirled to make a stepping mode.
Fine speed drive (for example, about 0.5 mm / min)
The film is wound on the winding roll 525. During this time, the web 550 is pressed by the removal roll 530 to come into contact with the transfer belt 7 and absorb and remove the oil adhering to the transfer belt 7. The operation timing of this oil removing device is also the same as that of the device using the silicon roll shown in the first embodiment.

Embodiment 3 This embodiment shows an example of a device having a mechanism for setting an accurate operation timing of the oil removing device. This embodiment is constructed by utilizing the fact that the friction coefficient between the transfer belt and the cleaning means (blade) changes depending on the adhesion state of the silicone oil to the transfer belt 7 (see FIG. 1). A cleaning device 20 is arranged upstream of the oil removing device 50 of the image forming apparatus. The cleaning device 20 includes a rotary brush 25 that contacts the surface of the transfer belt 7 to remove the transfer toner, and a cleaning blade 26 that contacts the surface of the transfer belt 7 to remove the transfer toner. And a toner recovery box 28 for recovering the removed toner. The strain gauge 2 is attached to the cleaning blade 26 of the cleaning device 20 of this embodiment.
66 is attached. The strain gauge 266 is attached to an appropriate portion of one surface of the cleaning blade 26 fixed to the housing via a blade holder 27 by means of sticking or the like, and is connected to the amplifier.

The cleaning blade 26 contacting the surface of the transfer belt 7 has little vibration (distortion) when the frictional resistance with the contact surface of the transfer belt 7 is low, and vibrates (distortion) when the frictional resistance becomes large. growing. This strain value (friction coefficient) is monitored for each revolution of the transfer belt 7. And
When the fluctuation of the value is within a predetermined value range, the oil removing device 5
0 is inactive. When the value sharply rises and exceeds a certain value, the oil removing device 50 is rotated to move the oil removing member to a position where it contacts the transfer belt.

As another embodiment, a belt drive motor
It is also possible to control the operation and non-operation of the oil removing device by the inflow current of the motor 80. Here, when the speed of the transfer belt 7 is kept constant by the stepping motor 80, when the friction coefficient between the cleaning blade 26 and the transfer belt 7 is examined, the relationship shown in FIG. 15 is found. That is, the current flowing into the motor 80 changes substantially in proportion to the friction coefficient between the cleaning blade 26 and the transfer belt 7. Therefore, this value is constantly monitored, and when the inflow current exceeds a certain value, the oil removing device 50 is moved so as to contact the belt.

As described above, in the image forming apparatus having this mechanism, the operation timing of the oil removing device is determined according to the oil adhesion state of the transfer belt 7 regardless of the double-sided print mode or the single-sided print mode. can do. Further, FIG. 6 shows the relationship between the web transport speed and the amount of oil removed from the transfer belt when a web is used as the oil removing member of the oil removing device 50. According to this graph, the amount of oil removed from the transfer belt increases as the web transport speed increases. That is, in the oil removing device using the web as the oil removing member, when the variation amount of the strain value between the transfer belt and the cleaning blade shows a large value, the web conveying speed is set to be higher, Good oil removal performance is obtained.

On the other hand, by removing the oil from the transfer belt 7, the cleaning property by the cleaning blade 26 can be maintained, but the toner slips through the cleaning blade 26 and is cleaned. Even if a cleaning failure occurs, the toner remaining after removal has a cleaning operation of 1
Since the toner is the residual toner after being picked up, the amount and the state of adhesion are not so severe. Therefore, the oil removing member, the web, the brush, etc. of the oil removing device 50 also perform the removing action of the toner. -The transfer belt that has passed through the cleaning device and the oil removal device becomes a belt in which toner and oil have been reliably removed, and it is possible to prevent fluctuations in the friction coefficient of the cleaning blade as much as possible and prevent problems in image quality. it can.

Although the embodiment has been described above in which the movable body is an endless transfer belt made of an insulating film that attracts and conveys the transfer sheet, the movable body is an intermediate transfer body that holds and transfers the transferred image. However, the action and effect can be applied.

FIG. 16 shows an embodiment in which the moving body is an endless photoconductor belt holding a transferred image. When the moving body is the photoconductor belt 600, the sheet 700 on which the toner image is once transferred for double-sided printing is circulated in the image forming apparatus along the sheet conveying path, and is applied to the sheet by the fixing device 1000. Silicon oil is the photoconductor 6
It adheres to 00. When the belt 600 is divided into panels and is repeatedly printed at the same size position, a difference occurs depending on whether or not silicon oil adheres between the image forming panel position and the image non-creating panel position. As a result, poor cleaning of the photoreceptor and uneven image density have occurred. Even in this case, the same problem can be solved by disposing the oil removing device 950 so as to be contactable and separable on the downstream side of the cleaning device 900 so as to face the drive roller 90.

[0045]

As described above, the image forming apparatus of the present invention is provided with the release agent (oil) removing means to remove the release agent (silicon oil) adhering to the surface of the transfer belt. Fluctuations in the frictional state between the transfer belt and the cleaning means due to the adhesion of the release agent can be minimized, stable image quality can be maintained, and toner contamination on the back surface of the transfer sheet can be prevented. Further, the release agent removing means is disposed on the downstream side of the cleaning means, and can remove the residual toner which could not be cleaned by the cleaning means.

[Brief description of drawings]

FIG. 1 is an enlarged view of an oil removing device.

FIG. 2 is an operation explanatory view of the oil removing device.

FIG. 3 is a partial top view of the oil removing device.

FIG. 4 is an explanatory view showing another embodiment of the oil removing device.

FIG. 5 is an explanatory view of a drive mechanism of the oil removing device.

FIG. 6 is a graph showing the relationship between the web transport speed and the oil removal amount.

FIG. 7 is an enlarged view of a cleaning blade.

FIG. 8 is a structural explanatory view of a trayless image forming apparatus.

FIG. 9 is an explanatory diagram of a configuration of an image forming apparatus equipped with a stack tray equipped for exclusive use of both sides.

FIG. 10 is a schematic diagram of a transfer belt.

FIG. 11 is a schematic diagram of a transfer belt.

FIG. 12 is a schematic diagram of a transfer belt.

FIG. 13 is a schematic diagram of a transfer belt.

FIG. 14 is a perspective view of a moving body (transfer belt).

FIG. 15 is a graph showing the relationship between the current flowing into the stepping motor and the friction coefficient between the blade and the belt.

FIG. 16 is a structural explanatory view of an image forming apparatus including an endless photosensitive belt.

FIG. 17 is a result of measuring a strain gauge with a conventional device.

[Explanation of symbols]

2 (Y, M, C, K) image carrier, 3 (Y, M, C,
K) charger, 5 (Y, M, C, K) developing device,
7 moving body (transfer belt), 9 drive shaft, 20 cleaning device, 26 cleaning blade, 26
6 strain gauge, 50, 500 oil removing device, 5
1,510 frames, 53 tracking rolls,
54,540 contact / separation rotary shaft, 55,550 oil removing member, 56,560 cam, 57 spring, 70 transfer paper, 71 joint, 100
Fixing device, 210 double-sided dedicated transport section, 220 supply transport path, 230 sheet reverse transport path, 240 discharge side transport path, 300 paper feed tray, 520 web supply roll, 525 take-up roll, 530 removal roll
80,800 Stepping motor, S 1st side of transfer sheet, 2nd side of D transfer sheet.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G03G 15/20 105 21/00 370 538 (72) Inventor Yukio Hayashi 2274 Hongo, Ebina, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (16)

[Claims] 1. A fixing member for fixing the toner transferred to the transfer paper, comprising a moving body for holding and moving the toner image or the transfer paper on which the toner image is transferred, a releasing agent applying means, and a fixing means for fixing the toner transferred on the transfer paper. The moving body is provided with a cleaning means for cleaning the surface of the moving body and a removing means for removing the release agent remaining on the surface of the moving body via the transfer paper. An image forming apparatus having a release agent removing member that is provided and that removes the release agent on the surface of the moving body when abutting on the surface of the moving body. 2. A moving member for holding and moving a toner image or a transfer sheet onto which the toner image is transferred, a fixing unit having a release agent applying unit, and fixing the toner transferred to the transfer sheet. Cleaning means for cleaning the surface of the moving body, removing means for removing the release agent remaining on the surface of the moving body via the transfer sheet, and detecting means for detecting the frictional state between the cleaning means and the moving body. And a control unit that outputs a drive signal to each drive unit in response to a detection signal from the detection unit, the release agent removal unit is disposed so as to come in contact with and separate from the surface of the moving body, and the detection unit has a predetermined friction. An image forming apparatus configured to output a drive signal to the release agent removing means so that the release agent removing means is brought into contact with the surface of the moving body for a certain period of time when a change more than the state change is detected. 3. The release agent removing means is configured to perform a double-sided printing operation,
3. The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to contact the moving body for a certain period of time after the double-sided printing operation. 4. The image forming apparatus according to claim 1, wherein the release agent removing means is arranged downstream of the cleaning means. 5. The image forming apparatus according to claim 1, wherein the release agent removing means is arranged so as to face a drive roll for conveying and driving the moving body with the moving body interposed therebetween. 6. The image forming apparatus according to claim 1, wherein the release agent removing member of the release agent removing means is a silicon roll. 7. The image forming apparatus according to claim 1, wherein the release agent removing member of the release agent removing means is a web. 8. The image forming apparatus according to claim 1, wherein the release agent removing member of the release agent removing means is a brush. 9. The image forming apparatus according to claim 1, wherein the release agent removing member of the release agent removing means is a scraper. 10. The releasing agent removing means has a structure in which the releasing agent removing web is brought into contact with the moving body while the releasing agent removing web is supplied from the supply roll and wound on the winding roll. The winding speed is variable, and when the detecting means of the moving body detects a change in the frictional state which is equal to or larger than a predetermined change, the control means causes the release agent removing means to control the winding speed of the web winding roll. The image forming apparatus according to claim 7, wherein the image forming apparatus outputs a drive signal for increasing the speed. 11. The endless transfer belt made of an insulating film for adsorbing and conveying a transfer sheet as the moving body.
Alternatively, the image forming apparatus described in 2. 12. The moving body is a cylindrical transfer drum made of an insulating film that attracts and conveys a transfer sheet.
Alternatively, the image forming apparatus described in 2. 13. The image forming apparatus according to claim 1, wherein the moving body is an intermediate transfer body that holds and moves the transferred image. 14. The image forming apparatus according to claim 1, wherein the cleaning unit has a cleaning blade that cleans at least the transfer image transferred onto the moving body. 15. The image forming apparatus according to claim 2, wherein the frictional state detecting means is provided on a cleaning blade of the cleaning means. 16. The friction state detecting means is a drive mode for a moving body.
The image forming apparatus according to claim 2, wherein the image forming apparatus is a means for detecting a current flowing into the printer.