JPH0619356A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device capable of always and stably obtaining a high quality image under every using circumstances. CONSTITUTION:In the image forming device 1 forming an image on a recording meidum through inputting image information, plural conditions for transferring a developed image on photosensitive body on the recording medium, and separating it therefrom, are set based on the image information, by a means for judging the amount of the image information, a device working state, and the working amount of a cleaning member (web) 5 provided on fixing means 4 and 4A, is changed based on the setting of the conditions and the amount of the image information. Thus, the working amount of the cleaning member 5 of the fixing means 4 is changed according to both of the setting of the conditions changed over according to using environment, etc., and inputted image information, so that a stable final image can be always recorded under various circumstances of using device.

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 obtaining a recorded image based on image information.

[0002]

2. Description of the Related Art Conventionally, various types of image forming apparatuses have been proposed and put to practical use, but especially in image forming apparatuses such as copying machines, an electrophotographic method is often used. Usually, in the electrophotographic system, the final image is obtained through the following five steps.

Latent image formation: Image information is written on a photoreceptor by charging and exposure.

Development: A latent image is visualized by attaching a developer to it.

Transfer / separation: After transferring the developed image on the photoreceptor to the recording material, the recording material is separated from the photoreceptor.

Cleaning: The residual image on the photoconductor after transfer is removed.

Fixing: The developer image transferred on the recording material is fixed on the recording material.

By the way, in recent copying machines and the like, in order to always obtain a stable final image even under various usage conditions, especially in the above-mentioned transfer / separation step, the device usage environment and the device usage status are used. In addition, there are a plurality of setting conditions provided so that the respective operating conditions can be changed according to the recording material used, and it is possible to switch to any setting condition. According to such an image forming apparatus, the image information is recorded on the recording material in a fairly stable and substantially good condition.

[0009]

However, in the above-mentioned conventional example, the transfer development (offset) of the developer from the recording material to the fixing means in the fixing step differs depending on the environment in which the apparatus is used and is provided in a part of the fixing means. In addition, the developer scrapes through a cleaning member (for example, a felt pad or a web) such as a felt pad or a web, so that the next recording material is soiled or the fixing unit is soiled.

Therefore, an object of the first invention is to provide an image forming apparatus which can always stably obtain a high quality image even under various usage conditions.

By the way, when an image is formed in an image forming apparatus such as an electrophotographic copying machine, a web is widely used as a means for cleaning a photoreceptor for forming a latent image thereof, or as an oil applying means and a cleaning means in a fixing device. ing.

As shown in FIG. 25, the web 5 is wound around the web supply roller 6 and the web winding roller 7, and is pressed against the fixing roller 4A by the web roller 26. By rotating one of the rollers 7 (usually the web take-up roller 7), the web 5 is fixed to the fixing roller 4
While moving in contact with A, the surface of the fixing roller 4A is cleaned by applying oil, which is a release agent, to the surface of the fixing roller 4A and removing toner, paper dust, etc. adhering to the fixing roller 4A.

As the driving means for the web 5, a stepping motor or a combination of a solenoid and a one-way clutch is used, and the web 5 is fixed to the fixing roller 4.
The web roller 26 is generally used as a means for contacting A.

However, in the above-mentioned conventional example, the web 5 is used.
The contact width of the fixing roller 4A with the fixing roller 4A is too small to sufficiently clean the offset toner or the like, or the contact width is sufficient, but the toner or the like heated sufficiently during standby is In copying, there was a problem that the web 5 was rubbed through when the roller rotation was started, and the first recording paper and the pressure roller 4B were contaminated.

Therefore, the object of the second aspect of the present invention is to remove foreign matters such as offset toner adhering to the fixing means efficiently and surely without complicating the structure of the apparatus, and to impregnate the web. An object of the present invention is to provide an image forming apparatus capable of constantly obtaining a high-quality image by increasing the coating efficiency of the release agent used.

FIG. 14 shows an image forming apparatus such as a copying machine provided with a double-sided mode for forming images on both sides of a sheet or a multiplex mode for forming a plurality of images on the same side of a sheet.

In the image forming apparatus 1, the image forming section 3,
Sheet feeding section A for feeding the sheet S to the image forming section 3
1, a fixing unit A2 that fixes an image on the sheet S formed by the image forming unit 3, a sheet discharging unit A3 that discharges the sheet S that has completed image formation, and an image is once formed and is fed to the image forming unit 3 again. Intermediate tray 3 for temporarily storing the sheet S to be stored
5, a sheet re-feeding sheet guiding section A4 for guiding the sheet S to be re-fed to the intermediate tray 35 and a sheet re-feeding section A5 for feeding the sheet S stored in the intermediate tray 35 to the image forming section 3 again. It is arranged.

When the double-sided mode or the multiplex mode is selected, the sheet S on which an image has been once formed by the image forming section 3 has the image fixed by the fixing section A2. When the sheets A are stacked and stored on the intermediate tray 35 by A4 and a predetermined number of these sheets S are stored, the sheet re-feeding unit A5 separates and feeds the sheets S one by one, and supplies them to the image forming unit 3 again. Will be sent. Then, when the image is formed for the second time, the image is fixed in the fixing unit A2, and the sheet S on which the image is fixed is discharged to the discharge unit A3.

In such an image forming apparatus 1, the stacked sheets S are separated one by one as follows, for example.

That is, as shown in FIG. 26, the intermediate tray 35
The sheets S stacked on the transport roller 3 are driven to rotate in the transport direction by the meniscus roller 41 from the lowest sheet.
9 and a retard roller 40 that rotates with the conveying roller 39 while receiving a rotational driving force opposite to the conveying direction via a predetermined torque limiter, and is fed to a nip portion n, and a plurality of sheets S are formed. When fed to the nip portion n, the sheet S on the retard roller 40 side is returned in the opposite direction, and only the sheet S on the transport roller 39 side is fed.

However, when a plurality of sheets S are conveyed to the nip portion n, the second lowest sheet S is also nipped in the nip portion n, so the nip of the second lowest sheet S is nipped. The portion corresponding to the portion n is rubbed while being pressed against the lowest sheet S.

Therefore, when the image surface of the sheet S is facing upward (duplex copying), the portion sandwiched in the nip portion n on the back side of the second sheet S becomes dirty. Further, when the image surface of the sheet S is facing downward (lower separation), the portion of the image of the second sheet S sandwiched by the nip portion n disappears.

The generation of dirt due to friction between the sheets S will be described in more detail with reference to the simple model shown in FIGS. 27 and 28.

The model shown in FIG. 27 shows a state at the time of multiplex, and a black dot b shows a developer (toner). When the sheets S1 are sequentially fed while being separated at the nip portion n as described above when re-fed, the shaded portions of the sheet S1 are rubbed against each other at the nip portion n. At this time, the developer on the second lowest sheet S2 is peeled off, and the peeled developer adheres to the non-image surface of the lowest sheet S1.

The model shown in FIG. 28 shows the state of both sides. When the sheet S1 is sequentially fed at the time of re-feeding as in the case of multiple sheets, the shaded portion of the sheet S1 is rubbed,
The developer on the image surface of the lowest sheet S1 adheres to the non-image surface of the second lowest sheet S2.

Therefore, in the conventional image forming apparatus, the pressure roller of the fixing device is brought into contact with the oil coating felt impregnated with oil to supply the oil, and the surface of the sheet opposite to the image forming surface is supplied. By applying the oil, the friction between the sheets stacked on the intermediate tray during the re-feeding separation operation is reduced and the developer is prevented from transferring to another sheet.

However, in the above-mentioned conventional example, as the endurance progresses, the scraps (paper dust) of the sheet gradually passing through the fixing device adhere to the oil-coated felt, and the oil is not efficiently supplied to the pressure roller. was there.

Accordingly, an object of the third invention is to provide an image forming apparatus capable of efficiently supplying a releasing agent to a fixing means and constantly obtaining a high quality image.

By the way, the amount of oil, which is a release agent, applied to each roller in the fixing device is determined by the degree of peeling of the recording material from the roller during normal copying.
The amount of oil applied per sheet is very small.

On the other hand, copying machines often perform double-sided copying, and the number of copying machines having a double-sided function is also increasing. Here, the double-sided function means that the toner image is transferred onto one side of the recording material, the recording material is passed through the fixing device once, and then the toner image is transferred onto the transfer surface of the recording material on which the toner image is not transferred. Then, as in the first case, the function of passing the recording material through the fixing device again to complete the fixing is said.

Further, a plurality of sheets (for example,
In a double-sided copy when obtaining a similar copy (20 sheets), 20 copies of one side are made with the first original document, and the copied 20 sheets are recorded until the second original document is placed. The material is loaded inside the duplex unit. Then, when the second original is placed next and double-sided copying is started, the recording material stacked inside the double-sided unit is re-fed so that its untransferred surface is on the photoconductor. In addition, in the multiple copy, almost the same method as the above is adopted.

However, in the above-mentioned conventional example, since the amount of oil applied to each roller is very small, there are the following problems.

That is, immediately after the power is turned on or when a thick paper or the like is passed, the fixing rate at which the toner is fixed on the paper generally tends to decrease. Further, since the amount of oil applied to each roller is small, the amount of oil applied from the rollers onto the recording material is smaller than that.

When the above two overlap, a small amount of oil is applied on the recording material having a low fixing rate. Therefore, when the recording material is re-fed from the inside of the duplex unit as described above, the toner that should have been fixed on the re-feed roller may be offset, and the roller may be soiled. Contamination is again offset on the recording material, resulting in the occurrence of image contamination.

Therefore, an object of the fourth aspect of the present invention is to provide an image forming apparatus capable of preventing image contamination during re-feeding.

By the way, in order to prevent the heat generated in the fixing device from escaping, the fixing device is provided with heat insulating covers 70 and 71 on the upper and lower portions of the fixing device 4 as shown in FIG. On the other hand, in order to enhance the peelability of the sheet and the toner from the fixing roller 4A, the web 5 impregnated with oil is pressed against the fixing roller 4A by the web roller 26, and the oil is supplied to the fixing roller 4A. Alternatively, as shown in FIG. 30, a leaf spring 75 is attached to the fixing roller 4A.
A method is also adopted in which the oil 72 is supplied to the fixing roller 4A by supplying the oil 72 from the oil filling container 80 arranged apart from the fixing device 4 to the application felt 76 pressed by the pump 77 by the pump 77.

However, in the above-mentioned conventional example, since the web 5 has no thickness, the heat insulation effect due to the oil 72 impregnated in the web 5 cannot be obtained, and the oil filling container 80 is fixed to the fixing device 4.
Since it is arranged away from the oil filling container 80
The heat insulation effect due to the oil 72 filled in was not able to be obtained.

Accordingly, an object of the fifth invention is to provide an image forming apparatus capable of enhancing the heat insulating effect of the heat insulating cover provided in the fixing means.

[0039]

In order to achieve the above object, a first invention is an image forming apparatus for inputting image information to form an image on a recording medium, and means for judging the amount of image information, and an apparatus. Depending on operating conditions, a plurality of condition settings for transferring the developed image on the photoconductor onto the recording medium and separating the recording medium from the photoconductor based on the image information are provided, and the operating amount of the cleaning member provided in the fixing unit is set to The feature is that it is changed based on the condition setting and the image information amount.

A second aspect of the invention is a fixing means for forming an image on a recording medium using an image carrier and fixing a developed image on the recording medium to the recording medium, and a moving body such as the image carrier and the fixing means. An image forming apparatus is configured to include a contacting web and a pressing member for pressing the web on the downstream side in the moving direction of the moving body, and driving the web.

A third aspect of the invention is a sheet re-feeding means for accommodating the recording medium for forming an image again on the recording medium on which an image has been formed, and separating and re-feeding a plurality of the accommodated recording mediums one by one. An image forming apparatus having a fixing means for fixing a developed image on a recording medium, and a release agent supplying means for pressing a coating felt impregnated with a release agent against a roller of the fixing means. A contacting / separating unit for contacting / separating with the roller is provided, and the coating felt is brought into contact with the roller only when the recording medium on which an image is formed / fixed is conveyed to the re-feeding unit.

A fourth aspect of the present invention is for preventing double feeding of a recording medium from one-side fixing on the recording medium to re-feeding when the image is transferred and fixed twice or more on both sides or the same one side of the recording medium. In the image forming apparatus having the separating mechanism, the amount of the releasing agent is applied to the fixing unit in an amount larger than that in the normal single-sided image formation during the period from the fixing until the recording medium reaches the re-feeding roller to the conveyance of the recording medium. It is characterized by

A fifth aspect of the invention is an image forming section for forming a developed image on a recording medium, a fixing means for fixing the developed image on the recording medium, and a releasing agent supplying means for supplying a releasing agent to the fixing means. In the image forming apparatus including the heat insulating cover, a heat insulating cover having a width substantially equal to or larger than a width in a thrust direction of a nip portion formed by the fixing roller and the pressure roller that constitute the fixing unit is provided. Is filled with a release agent.

[0044]

According to the first aspect of the present invention, the operating amount of the cleaning member of the fixing unit is changed in accordance with both the condition setting that is switched according to the usage environment and the image information that is input, so that various device usage conditions can be obtained. Below, stable final image information can always be recorded.

According to the second aspect of the invention, foreign matter such as offset toner adhering to the fixing means can be efficiently and surely removed without inviting a complicated apparatus structure.
The coating efficiency of the release agent with which the web is impregnated can be increased, and a high quality image can always be obtained stably.

According to the third aspect of the invention, it is possible to prevent paper dust or the like from adhering to the coating felt when the recording medium is not conveyed to the re-feeding section, and it is possible to always obtain a high quality image in a stable manner. it can.

According to the fourth aspect of the present invention, the releasing agent is applied to the fixing means in an amount larger than that in the normal single-sided image formation only when the double-sided image formation and the multiplex image formation are performed. You can

According to the fifth aspect of the invention, the release agent such as oil filled in the heat insulating cover performs a heat insulating action, so that the heat insulating effect of the heat insulating cover can be enhanced.

[0049]

【Example】

[First Invention] An embodiment of the first invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a flow chart for explaining the operation of an image forming apparatus (copier) according to the present invention.
2 is a cross-sectional view of the image forming apparatus, FIG. 3 is a perspective view showing the configuration of the fixing unit, and FIG. 4 is a circuit diagram inside the image forming apparatus.

The image forming apparatus 1 according to this embodiment is a copying machine of a type called a laser copier, which is mainly composed of a document image reading device (reader) 2 and a recording device (printer) 3.

In the image forming apparatus 1, the document 8 is read by the linear solid-state image pickup device (CCD) 9 and the read image information is sent to the image processing apparatus 10. The laser beam generated by the laser beam generator 11 based on this is reflected by the polygon mirror 2 on the photosensitive member 3.
By scanning upward, an electrostatic latent image is formed on the photoconductor 13.

The electrostatic latent image is developed as a developed image (toner image) by the developing device 14 containing a developer (toner), and the developed image is recorded on the recording paper fed from the paper cassette 15 by the paper feed roller 16. The image is transferred by the transfer charger 17. Then, the recording paper on which the developed image is transferred is separated from the photoconductor 13 by the separation charging device 18 and is conveyed to the fixing device 4.

At this time, the optimum values of the transfer / separation conditions may be remarkably different depending on the use environment of the apparatus. That is,
In a low-humidity environment, the recording paper has a large resistance, and transfer charges are relatively likely to remain on the recording paper. Further, the rigidity of the recording paper is higher than that in high humidity, and the transfer / separation conditions may be almost the same as those in normal humidity (L setting).

On the other hand, in a high temperature environment, the resistance of the recording paper is reduced, and the transfer charge is less likely to remain on the recording paper. Therefore, it is preferable to set the transfer / separation condition to be slightly stronger than that under normal humidity (H setting).

By the way, in the fixing device 4, the recording paper on which the development image is transferred is nipped and conveyed by the fixing roller 4A and the pressure roller 4B which is pressed by the fixing roller 4A and is conveyed by the fixing roller 4A. As a result, the developed image is fixed on the recording paper, and the recording paper on which the developed image is fixed is discharged to the outside of the machine.

On the other hand, the fixing roller 4A is in contact with the web 5 in order to remove foreign matters such as developer (toner) and paper dust offset at the time of fixing and to supply a releasing agent. This web 5 is driven by a solenoid 19 shown in FIG.
And is wound around the roller 7.

Next, the internal circuit of the image forming apparatus 1 will be described with reference to FIG.

A microcomputer (hereinafter, referred to as CPU) 300 is connected to each peripheral device via a bus, and a random access memory (hereinafter, referred to as RAM) 302 is used to read only memory (ROM).
Each peripheral device is controlled based on the program stored in 301.

The timer circuit 303 measures the reference time,
The serial communication circuit 304 is a circuit for receiving instructions for starting and stopping recording, and for notifying the printer status such as no paper. Further, the A / D converter 305 is a circuit for converting various analog data into a digital signal and informing the CPU 300 of the temperature. The input signal of the A / D converter 305 is the temperature of the fixing device 4 and the integrated value of the image signal integration circuit 310. , A potential measurement value on the photoconductor 13 and the like.

Further, the input control circuit 306 is provided for each drive unit (for example, a conveyance motor or a photoconductor rotation motor) in the printer.
It is a circuit for driving input / output controls such as a paper feed clutch and various high-voltage devices around the photoconductor and input signals of a paper sensor. The solenoid control circuit 307 is a circuit that drives the solenoid 19 that winds the web 5.

The image signal input from the reader 2 is
The image signals for one line in the horizontal direction on the photoconductor 13 are synchronized, and the image portion (the portion to which toner is attached) is input as a positive signal. The input image signal is received by the image signal receiving circuit 309 and input to the laser driver 311 via the image signal integrating circuit 310 to drive the laser 312 to generate laser light, and the photoconductor 13 emits the laser light. Upon irradiation, an electrostatic latent image is formed on it.

The image signal integration circuit 310 is reset by the CPU 300 before the image signal for one page is generated, and if the image signal for one page is integrated, the integrated value is calculated via the A / D converter 305. Notify the CPU 300.

The A / D converter 305 converts the analog information to 0.
To 255 digital signals, the integrated value of the image signal is 0 for all white on one page and 255 for all black, and the interval changes depending on the amount of black image signal. Therefore, the ratio of black information for one page is transmitted to the CPU 300.

Here, the control procedure of the copy operation of the CPU 300 is shown in the flow chart of FIG. 1 and FIG. 5, which will be described below.

When a print start instruction is received from the operation unit through serial communication via the serial communication circuit 304 (STP401), pre-rotation for recording preparation of each part of the printer such as the motor and the high voltage device is started (STP40).
2).

Next, the integrating circuit 310 is reset (S
TP403), when the paper feed possible information is received (STP4)
04), start paper feeding from the paper feeding cassette 15 (STP
405).

On the other hand, when the fed paper reaches a position where it matches the image after the paper feed is started (STP405), an image signal reception start signal is output to the reader 2 (STP406). Then, an image signal is output from the reader 2, the image signal is received (STP407), and image recording is executed as described above. When the image signal for one page is completely received through the image signal receiving circuit 309 (STP408), the integral value is input from the integrating circuit 310 through the A / D converter 305 (STP409). The input value is stored in the RAM 302.

Then, the sheet on which the developed image (toner image) is transferred is conveyed in the machine, and this is fixed by the fixing roller 4 of the fixing device 4.
When A is reached (STP410), condition judgment (STP10)
1) and image information amount judgment (STP102) are performed, and the feed amount of the web 5 is changed as follows.

That is, since the drive of the web 5 is driven by the solenoid 19, the feed amount of the web 5 can be freely changed by changing the number of times the solenoid 9 is driven as follows.

The transfer / separation condition is set to L (STP10
When the image signal integrated value is less than 128 (STP102) in 1) ... 1 time (STP107) in <L1 mode> (STP103).

The transfer / separation condition is set to L (STP10
When the image signal integrated value is 128 or more (STP102) in 1) ... 3 times (STP108) in <L2 mode> (STP104).

The transfer / separation condition is set to H (STP10
When the image signal integrated value is less than 128 (STP102) in 1) ... 2 times (STP109) in <H1 mode> (STP105).

The transfer / separation condition is set to H (STP10
When the image signal integrated value is 128 or more (STP102) in 1) ... 4 times (stp110) in <H2 mode> (STP106).

Then, each part is post-rotated (STP412)
Then, it is confirmed that the paper has been ejected outside the device (ST
P413), the copying operation is stopped because the series of operations has been completed (STP415). When the paper is not discharged to the outside of the machine, JAM is displayed as the paper is jammed inside the machine (STP414). When copying is performed continuously (continuous, double-sided, multiplex, etc.)
(STP411) repeats a series of operations of STP403 to STP411.

As described above, in the present embodiment, the feeding amount of the web 5 of the fixing device 4 is changed in accordance with not only the device usage status but also the image information amount of the original image, and the fixing is performed according to each. Since the roller 4A is properly cleaned, a high-quality image can always be obtained stably without contaminating the paper or the fixing device 4, and the life of the web 5 can be extended.

<Second Embodiment> FIG. 6 is a flow chart for explaining the operation of the image forming apparatus (copier) according to the second embodiment of the present invention.

In this embodiment as well, the image formation is performed in the same manner as in the first embodiment, but in this embodiment,
The transfer / separation condition settings differ between the first and second side of the copy.

That is, in this apparatus, when performing double-sided or multiple copying, the recording paper is subjected to a series of image forming steps,
After passing through the fixing process, the photoconductor 1 is sent to the lower conveyance system 21 shown in FIG.
3 is re-fed. In the copying process for the second and subsequent pages, the recording paper receives heat and pressure in the final step of the first surface to fix the developed image (toner image), so that the resistance value and shape of the recording paper itself (curled paper). ) Is different from the case of the first surface, the transfer / separation condition setting is consciously changed between the setting of the first surface (I setting) and the setting of the second and subsequent surfaces (II setting).

Therefore, the number of times the solenoid 19 is driven is changed in the following manner in accordance with the determination flowchart shown in FIG.

The transfer / separation condition is set to I (STP50
When the image signal integrated value is less than 128 (STP502) in 1) ... 2 times (STP507) in <I1 mode> (STP503).

The transfer / separation condition is set to I (STP50
When the image signal integrated value is 128 or more (STP502) in 1) ... 4 times (STP508) in <I2 mode> (STP504).

The transfer / separation condition is set to II (STP50
When the image signal integral value is less than 128 (STP502) in 1) ... 1 time (STP509) in <II1 mode> (STP505).

The transfer / separation condition is set to II (STP50
When the image signal integral value is 128 or more (STP502) in 1) ... 3 times (STP510) in <II2 mode> (STP606).

<Third Embodiment> FIG. 7 is a flow chart for explaining the operation of the image forming apparatus (copier) according to the third embodiment of the present invention.

In this embodiment, the image formation is performed in the same manner as in the above embodiment, but in this embodiment, the transfer / separation condition is set by manually feeding the recording paper fed from the paper cassette. The recording paper used is different.

That is, in this apparatus, recording paper (for example, OHP paper or 126 g / m ² ) other than recording paper (for example, about 80 g / m ² or less) fed from the paper cassette is used.
^When copying onto thick paper ( ² or more), the resistance and rigidity of the recording paper itself is different from that of the recording paper fed in the cassette. ) And the setting for manual feeding (M setting) are intentionally changed.

Therefore, the number of times the solenoid 19 is driven is changed as follows in accordance with the determination flowchart shown in FIG.

The transfer / separation condition is set to C (STP60
When the image signal integrated value is less than 128 (STP602) in 1) ... 1 time (STP607) in <C1 mode> (STP603).

The transfer / separation condition is set to C (STP60
When the image signal integrated value is 128 or more (STP602) in 1) ... 2 times (STP608) in <C2 mode> (STP604).

Transfer / separation conditions are set to M (STP60
When the image signal integral value is less than 128 (STP602) in 1) ... 3 times (STP609) in <M1 mode> (STP605).

The transfer / separation condition is set to H (STP60
When the image signal integral value is 128 or more (STP602) in 1) ... 4 times (STP610) in <M2 mode> (STP606). [Second Invention] An embodiment of the second invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 8 is a sectional view of a fixing device of an image forming apparatus according to the present invention, FIG. 9 is an enlarged detailed view of a main portion of an identification fixing device, and FIG. 10 is an image forming apparatus according to the present invention. FIG.

In the image forming apparatus shown in FIG. 10, the original 8 on the original table 22 is illuminated by the exposure lamp 23, and a latent image corresponding to the original 8 is formed on the photoconductor 13. This latent image is a developing device 14 containing a developer (toner).
Is developed as a developed image (toner image) by the transfer means 17 and transferred to the recording paper fed from the paper cassette 15, and the recording paper to which the developed image is transferred is conveyed to the fixing device 4.

In the fixing device 4, the recording paper is the fixing roller 4
While being nipped and conveyed by A and a pressure roller 4B that is pressed and driven by A, the development image is fixed by heat, pressure, etc.,
The recording paper on which the developed image has been fixed is discharged to the outside of the machine.

On the other hand, the web 5 is brought into contact with the photoconductor 13 and the fixing roller 4A in order to remove foreign matters such as toner and paper dust that are offset during transfer / separation and fixing and to supply a release agent. There is. This web 5 is sent out from the web supply roller 6 shown in FIG. 8 via a one-way clutch by the drive of a solenoid (not shown), and is wound up by the web winding roller 7. Then, during this time, the web 5 is pressed against the fixing roller 4A by the web pressing member 24.

By the way, in this embodiment, the web 5 is used.
Is widely contacted with the fixing roller 4A by the guide 25. Specifically, the web 5 is in contact with the fixing roller 4A having an outer diameter of 40 mm with a width of 20 mm corresponding to about 16% of the circumferential length.

Further, the pressing member 24 composed of a felt pad is provided in the contact area between the fixing roller 4A and the web 5 and on the downstream side of the rotation of the fixing roller 4A. The pressing width of the pressing member 24 is about 5 mm, which corresponds to about 25% of the contact width of the web 5 to the fixing roller 4A.

Most of the toner or the like offset on the fixing roller 4A is first wiped off by the web 5 in the area a shown in FIG. 9, and the remaining toner is also removed by the web 5 in the area b. Since it is strongly pressed by the fixing roller 4A, b
Just before entering the area, it is blocked and wiped off by the web 5, and even if the sufficiently warmed toner moves in the contact area during rest, the recording paper and the pressure roller 4B are contaminated with the toner. High quality images can always be obtained stably.

<Second Embodiment> A second embodiment of the present invention is shown in FIG.
It will be described based on 1. FIG. 11 is a sectional view of the fixing device according to the second embodiment. In this figure, the same elements as those shown in FIG. 8 are designated by the same reference numerals.

In this embodiment, the web pressing member 24
Is composed of a blade, and the web pressing member 24 also serves as the web guide 25. Also in this case, most of the offset toner is wiped off by the web 5 that is in contact with the upstream side (the upstream side in the rotation direction of the fixing roller 4A) of the contact position of the web pressing member 24, so that the web pressing member is wiped off. There is little offset toner reaching the 24th position,
Further, even if the toner warmed at the contact portion during the rest comes to move at the start of the next copy, this is reliably blocked by the web pressing member 24.

When the web contact member 24 is a fixed member as in the first and second embodiments, the web contact member 24 has a contact surface with the web 5. However, it is preferable to use one that is smooth and has good slipperiness. If you fall down, Teflon coat felt, Poreflon R,
A multilayer structure of felt and fluororesin or fluororubber is suitable.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIGS. 12 is a sectional view of the fixing device according to the third embodiment, and FIG. 13 is an enlarged detailed view of the main part of the identification fixing device. In these drawings, the same elements as those shown in FIGS. 8 and 9 are not shown. The same reference numerals are attached.

In this embodiment, as shown in FIG. 13, the offset toner is reliably dammed by the wide contact of the web 5 and the rubber roller 26 which is a pressing member (region c / d in FIG. 13). At the same time, an e region is provided to enhance the effect of applying the release agent.

With the above-mentioned structure, it is possible to obtain the same effect as that of using both sides of the web 5 as conventionally proposed. That is, most of the offset toner can be removed in the area c shown in FIG. 13, the offset toner can be reliably removed in the area d, and the release agent impregnated in the web 5 is applied to the fixing roller in the area e. 4A
It can be applied to the surface and the functions can be shared by the respective c, d and e regions. [Third Invention] An embodiment of the third invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 14 is a sectional view of an image forming apparatus according to the present invention, and FIG. 15 is a sectional view showing the structure of a fixing device.

As is well known, the sheet S on which an image is formed in the image forming section 3 of the image forming apparatus shown in FIG. 14 has the fixing roller 4A and the pressure roller 4B of the fixing device 4 shown in FIG.
Is conveyed while being nipped under pressure in the nip portion N formed by
Further, the image is fixed on the sheet S by being heated by the heater 27.

By the way, as shown in FIG. 15, a shaft 28 is rotatably provided below the pressure roller 4B, and an arm 29 is connected to the shaft 28. A leaf spring 31 that supports an oil-coated felt 30 impregnated with oil is attached to one end of the arm 29, and a coil spring 32 and a rod 33a of a plunger 33 are connected to the other end of the arm 29. . In addition, the coil spring 32 applies the oil coating felt 30 to the pressure roller 4
The arm 29 is biased in the direction of separating from B.

In the above structure, when the plunger 33 is in the non-operating state, the oil coating felt 30 is separated from the pressure roller 4B by the action of the coil spring 32 as shown by the broken line in FIG.

When the plunger 33 is driven and the rod 33a of the plunger 33 is moved in the direction of the arrow in FIG. 15, the arm 29 is rotated in the direction of the arrow (counterclockwise) shown in FIG. 30 rotates from the broken line position to the solid line position, and the oil coating felt 30 is pressed against the pressure roller 4B by the leaf spring 31.

Next, the operation of the image forming apparatus according to this embodiment when copying on both sides of the sheet S and when making multiple copies on the same side of the sheet S will be described.

When the multiplex mode or the double-sided mode is selected in this image forming apparatus, the plunger 33 is driven and the oil coating felt 30 is pressed against the pressure roller 4B as described above. Then, in the case of the multiplex mode, the sheet S on which the image is fixed as described above is guided to the re-feed sheet guiding section 36, and is stacked on the intermediate tray 35 with the image side facing down.

In the double-sided mode, similarly, the sheet S on which the image is fixed is reversed and guided by the re-feed sheet guiding section 36, and is stacked on the intermediate tray 35 with the image side facing up. During this series of operations, the pressure roller 4B is always coated with oil by the oil coating felt 30.

Therefore, when the sheet S passes through the nip portion N, the surface of the sheet S which is in contact with the pressure roller 4B,
That is, the oil is uniformly applied to the non-image surface. That is, when the sheet S passes through the nip portion N, the non-image surface of the sheet S is in a state in which a thin oil layer is uniformly coated. In this state, the non-image surface of the sheet S is extremely slippery, and foreign matter such as a developer is unlikely to adhere to the non-image surface.

Therefore, as described above, even if the sheet re-feeding means for stacking the sheets S on which the images are formed, separating them, and re-feeding the sheets, that is, rubbing the sheets S together is used. Since the non-image surface of the sheet S has high smoothness and slipperiness, the developer on the sheet S does not peel off and adhere to the non-image surface side of another adjacent sheet S. The conventional problem that the sheet S is stained with the developer is solved.

In addition, when the sheet S on which the image is formed is re-fed and in the mode in which the sheet S is not re-fed (a mode in which an image is formed only once on one side), the sheets S are rubbed with each other. Since there is no matching operation, it is not necessary to apply oil to the sheet S. Therefore, if the plunger 33 is deactivated, the coil spring 32 will cause the oil application felt 3 to move.
Since 0 is separated from the pressure roller 4B, oil is not applied to the pressure roller 4B by the oil application felt 30, foreign matter does not adhere to the oil application felt 30, and oil consumption can be reduced.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, the following structure is added to the first embodiment.

That is, the shaft 42 is rotatably supported, and the arm 42 is connected to the shaft 42. A blade 45 is supported at one end of the arm 44 via a leaf spring 43, and the coil spring 30 is provided at the other end of the arm 44.
And the rod 33a of the plunger 33 is connected.
The coil spring 32 applies an urging force to the arm 44 in a direction of separating the blade 45 from the pressure roller 4B.

In such a structure, when the plunger 33 is driven and the rod 33a moves in the direction of the arrow in the figure, both arms 29 and 44 respectively rotate in the direction of the arrow, and the oil coating felt 30 causes the leaf spring 31 to press the pressure roller. At the same time that the blade 45 is pressed against the pressure roller 4B, the blade 45 is also pressed against the pressure roller 4B by the leaf spring 43. Therefore, when the oil coating felt 30 is pressed against the pressure roller 4B, the blade 45 is also pressed against the pressure roller 4B, so that the foreign matter adhering to the pressure roller 4B is removed by the blade 45, and the oil is removed. It becomes difficult for foreign matter to adhere to the coating felt 30.

Further, as described in the first embodiment, when it is not necessary to apply oil to the pressure roller 4B, the plunger 33 is maintained in the inoperative state, and the coil spring 32 and the blade 45 are both in the pressure roller 4B. Since it is separated from the oil-applied felt 30 and the blade 45, foreign matter does not adhere to
Moreover, the foreign matter removed from the pressure roller 4B can be dropped by the separating operation of the blade 45. That is,
Since the foreign matter on the blade 45 is constantly removed, the foreign matter attached to the pressure roller 44 can be reliably removed by the blade 45.

<Third Embodiment> In the above-described embodiments, the separating means for re-feeding is explained by using the retarding method of lower separation, but the separating means for which the effect of the present invention is useful is not limited to this. Absent.

For example, as shown in FIG. 17, the re-feeding separation system is such that the sheet S stacked on the intermediate tray is conveyed from the uppermost sheet S by the pickup roller 37 in the conveying direction and is rotated by a predetermined distance. The sheet is conveyed to the nip portion n formed by the retard roller 40 that rotates together with the conveying roller 39 while receiving a rotational driving force opposite to the conveying direction via the torque limiter, and a plurality of sheets S are nipped. When the sheet S on the retard roller 40 side is returned in the opposite direction when the sheet S is fed to the sheet, the same effect can be obtained by the upper separation retard system in which only the sheet S on the conveying roller 39 side is fed.

Further, as shown in FIGS. 18 and 19, instead of the retard roller of the upper / lower separation retard system, the separation pad 38 is pressed against the conveying roller 39 to separate the sheet S from the upper / lower separation duplo system. Also in, the same effect can be obtained. [Fourth Invention] An embodiment of the fourth invention will be described below with reference to the accompanying drawings.

<First Embodiment> FIG. 20 is a sectional view of an image forming apparatus 1 according to the present invention.

In the image forming apparatus 1 according to the present invention,
During normal one-sided copying, the recording paper fed by the paper feed roller 16 from the paper feed cassette 15 is conveyed to the transfer charger 17 through the registration roller 53.

On the other hand, the electrostatic latent image formed on the photosensitive drum 13 whose surface is uniformly charged by the primary charging device 58 is developed as a toner image by the developing device 14, and the toner image is transferred by the transfer charging device 17. It is transferred onto the recording paper. Then, the recording paper on which the toner image has been transferred is sent to the fixing device 4 through the conveying portion 56, and in the fixing device 4, the recording paper passes through the nip portion between the fixing roller 4A and the pressure roller 4B, so that heat is generated. The toner image is fixed by the pressure, and the recording paper on which the toner image is fixed is discharged to the outside by the discharge roller 55.

Next, at the time of multiple copy, the recording paper passes through the fixing device 4 and is conveyed by the flapper 49 in the T direction in the figure before reaching the paper discharge roller 55 as in the case of single-sided copy.

The recording papers conveyed in the T direction are stacked one after another on the duplex unit 57 by the number of sets. When the user prepares multiple originals and presses the copy button again, it is necessary to separate the recording sheets stacked inside the duplex unit 57 one by one and re-feed them. This role is fulfilled
The sheet re-feeding roller 50, which has a separating mechanism for preventing double feeding like the sheet feeding roller 16.

Then, the re-fed recording sheet passes through the registration roller 53, the toner is transferred again, the fixing sheet 4, and finally the sheet is ejected to the outside of the apparatus.

Further, during double-sided copying, the flapper 49 advances in the direction in which the paper is discharged by the paper discharge roller 55, as in the case of one side. Therefore, when the trailing edge of the recording paper passes the flapper 49, the paper discharge roller 55 rotates in the reverse direction to convey the recording paper in the reverse direction. At the same time, the flapper 49 directs the recording paper in the R direction with its left end facing upward. After that, it is the same as the previous multiple copy.

In this embodiment, therefore, the oil application roller 51 is not in contact with the fixing roller 4A as shown by the slanted line in FIG. Only when is selected, the oil application roller 51 is brought into contact with the fixing roller 4A as shown by the broken line in FIG. 20, and the amount of oil (release agent) applied to the fixing roller 4A is increased.

The oil application roller 51 is removed from the fixing roller 4A when all of the planned number of recording sheets are accommodated in the double-sided unit 57, and during the re-feeding fixing operation, it is the same as a normal single-sided copy. A small amount of oil is applied to the fixing roller 4A
Applied to.

As described above, in the present embodiment, the amount of oil applied to the fixing roller 4A during normal single-sided copying is increased only during double-sided copying and multiplex copying, so image contamination during re-feeding can be prevented. .

Further, since the oil applying roller 51 is brought into contact with the fixing roller 4A only during double-sided copying and multiplex copying, the oil applying roller 51 is brought into contact with the fixing roller 4A more than when the oil applying roller 51 is always brought into contact with the fixing roller 4A. The life of can be extended.

The oil applying roller 51 is the pressure roller 4
It does not matter if it is brought into contact with B, and there is no problem even if its shape is not a roller but a pad.

In this embodiment, the releasing agent applied to the fixing roller 4A is cut during single-sided copying, double-sided copying or multiplex copying. A member (oil roller) that applies a release agent to the
The same effect can be obtained by providing.

<Second Embodiment> The second embodiment shown in FIG.
The present invention can be applied not only to the fixing device 4 using the book rollers (the fixing roller 4A and the pressure roller 4B) but also to the fixing device 64 using the fixing belt 67 shown in FIG.

As a method of attaching and detaching the oil applying roller 51, the oil applying roller 51 is pivotally supported at one end of an arm 62 which rotates about a shaft 61, and a plunger (electromagnetic coil) 69 is provided at the other end of the arm 62. The rod 69a of the rod 69a is connected to the rod 69a by driving the plunger 69.
Is moved in the direction of the arrow in the figure to detach the oil application roller 51 from the fixing belt 67. [Fifth Invention] An embodiment of the fifth invention will be described below with reference to the accompanying drawings.

FIG. 24 is a sectional view of the image forming apparatus 1 according to the present invention. In the image forming apparatus 1, the sheet S placed on the sheet feeding section 15 is sent to the image forming section 3 and the image forming section 3 is formed. Then, as is well known, an image is formed on the sheet S, and the formed image is fixed on the sheet S by the fixing device 4.

The structure and operation of the fixing device 4 will be described with reference to FIGS. 22 and 23.

The sheet S on which the image is formed is conveyed while being nipped by a nip portion N formed by the fixing roller 4A and the pressure roller 4B which is in pressure contact with the fixing roller 4A while being nipped by the heater 27. The image is fixed on the sheet S by being heated.

The upper heat insulating cover 70 and the lower heat insulating cover 71 prevent the heat generated by the heater 27 from escaping, and the lower heat insulating cover 71 is almost equal to or more than the width A of the nip portion N in the thrust direction. Has an opening width B of. The lower heat insulating cover 71 is filled with oil 72, and the oil 72 is supplied to the pressure roller 4B by the capillary phenomenon of the coating felt 30 pressed against the pressure roller 4B by the backup spring 73, and further applied. It is supplied from the pressure roller 4B to the fixing roller 4A.

Therefore, according to this embodiment, the fixing roller 4
Since oil is applied to the surface of A, the releasability of the sheet S and the toner from the fixing roller 4A is improved, and the oil 72 filled in the lower heat insulating cover 71 enhances the heat insulating effect of the heat insulating cover 71. To be

[0145]

As is apparent from the above description, according to the first aspect of the present invention, the operating amount of the cleaning member of the fixing unit changes according to the condition setting that changes depending on the environment of use and the image information that is input. Because of this, it is possible to obtain the effect that it is possible to always record stable final image information under various device usage conditions.

According to the second invention, foreign matter such as offset toner adhering to the fixing means can be efficiently removed without complicating the structure of the apparatus, and the release agent impregnated in the web can be removed. It is possible to improve the coating efficiency and always obtain a high quality image stably.

According to the third aspect of the invention, when the recording medium is not conveyed to the re-feeding section, it is possible to prevent paper dust or the like from adhering to the coating felt, and it is possible to always obtain a high quality image in a stable manner. .

According to the fourth aspect of the present invention, the amount of the releasing agent applied to the fixing means is larger than that in the normal single-sided image formation only when the double-sided image formation and the multiplex image formation are performed. The effect of being able to do is obtained.

According to the fifth aspect of the present invention, the release agent such as oil filled in the heat insulating cover exerts a heat insulating action, so that the heat insulating effect of the heat insulating cover can be enhanced.

[Brief description of drawings]

FIG. 1 is a flow chart for explaining an operation of an image forming apparatus according to a first embodiment of the first invention.

FIG. 2 is a cross-sectional view of the image forming apparatus according to the first invention.

FIG. 3 is a perspective view of a fixing unit of the image forming apparatus according to the first invention.

FIG. 4 is an internal circuit diagram of the image forming apparatus according to the first invention.

FIG. 5 is a flowchart for explaining the operation of the image forming apparatus according to the first embodiment of the first invention.

FIG. 6 is a flowchart for explaining the operation of the image forming apparatus according to the second embodiment of the first invention.

FIG. 7 is a flow chart for explaining the operation of the image forming apparatus according to the third embodiment of the first invention.

FIG. 8 is a sectional view of a fixing device according to a first embodiment of the second invention.

FIG. 9 is an enlarged detailed view of a main part of the fixing device according to the first embodiment of the second invention.

FIG. 10 is a sectional view of an image forming apparatus according to a second invention.

FIG. 11 is a sectional view of a fixing device according to a second embodiment of the second invention.

FIG. 12 is a sectional view of a fixing device according to a third embodiment of the second invention.

FIG. 13 is an enlarged detailed view of a main part of a fixing device according to a third embodiment of the second invention.

FIG. 14 is a sectional view of an image forming apparatus according to a third invention.

FIG. 15 is a sectional view of the fixing device according to the first embodiment of the third invention.

FIG. 16 is a sectional view of a fixing device according to a second embodiment of the third invention.

FIG. 17 is a diagram illustrating an upper separation retard system.

FIG. 18 is a diagram for explaining the upper separation Duplo system.

FIG. 19 is a diagram for explaining a lower separation Duplo system.

FIG. 20 is a sectional view of an image forming apparatus according to a first embodiment of the fourth invention.

FIG. 21 is a configuration diagram of a belt-type fixing device according to a second embodiment of the fourth invention.

FIG. 22 is a perspective view of a fixing device according to a fifth aspect of the invention.

FIG. 23 is a sectional view of a fixing device according to a fifth aspect of the invention.

FIG. 24 is a sectional view of an image forming apparatus according to a fifth invention.

FIG. 25 is a cross-sectional view of a fixing device according to a conventional example.

FIG. 26 is a diagram for explaining a lower separation retard system.

FIG. 27 is an explanatory diagram showing the occurrence of stains when forming multiple images.

FIG. 28 is an explanatory diagram showing the occurrence of stains when forming multiple images.

FIG. 29 is a sectional view of a fixing device according to a conventional example.

FIG. 30 is a sectional view of a fixing device according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4 Fixing device 4A Fixing roller 4B Pressure roller 5 Web (cleaning member) 19 Plunger 30 Coating felt 51 Oil coating roller 70 Thermal insulation cover 71 Thermal insulation cover

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical indication location H04N 1/29 Z 9186-5C (72) Inventor Mitsuhiro Takeka 3-30-2 Shimomaruko, Ota-ku, Tokyo No. Canon Inc.

Claims (10)

[Claims] 1. An image forming apparatus for inputting image information to form an image on a recording medium, comprising means for determining the amount of image information, and an operating condition of the apparatus, on the photoreceptor based on the image information. Having a plurality of condition settings for transferring the developed image onto the recording medium and separating the recording medium from the photoconductor, and changing the operation amount of the cleaning member provided in the fixing means based on the condition setting and the image information amount. An image forming apparatus characterized by. 2. The image forming apparatus according to claim 1, wherein the transfer and separation conditions in the image forming process are set independently depending on the environment in which the apparatus is used. 3. The image forming apparatus according to claim 1, further comprising a double-sided and multiplex copying function, wherein transfer and separation conditions are set independently for initial image formation and double-sided and multiplex image formation. . 4. The image forming apparatus according to claim 1, further comprising a manual sheet feeding function, wherein transfer and separation conditions are set independently for cassette sheet feeding and manual sheet feeding. 5. A fixing means for forming an image on a recording medium using the image carrier and fixing a developed image on the recording medium to the recording medium, and a web contacting a moving body such as the image carrier and the fixing means. And an urging member for urging the web on the downstream side in the moving direction of the moving body, and driving the web. 6. A re-feeding means for accommodating the recording medium for re-imaging on the recording medium once image-formed, separating and re-feeding a plurality of the accommodated recording media one by one, and developing. In an image forming apparatus having a fixing means for fixing an image on a recording medium and a releasing agent supplying means for pressing a coating felt impregnated with a releasing agent against a roller of the fixing means, the coating felt is in contact with the roller. An image forming apparatus characterized in that a contacting / separating unit for separating the recording medium is provided, and the coating felt is brought into contact with the roller only when the recording medium on which an image has been formed and fixed is conveyed to the re-feeding unit. 7. The image according to claim 6, further comprising: a blade that comes into contact with the roller to remove foreign matter adhering to the roller, and a contacting / separating unit that makes the blade contact / separate from the roller. Forming equipment. 8. A recording medium having an image formed / fixed thereon, comprising a blade for contacting the roller to remove foreign matter adhering to the roller, providing contacting / separating means for contacting / separating the blade with the roller. The image forming apparatus according to claim 7, wherein the coating felt and the blade are brought into contact with the roller only when being conveyed to the re-feeding unit. 9. A separation mechanism for preventing double feeding of recording media from one-side fixing on the recording medium to re-feeding when images are transferred and fixed twice or more on both sides or the same one side of the recording medium. In the image forming apparatus having the above, during the period from the fixing until the recording medium reaches the re-feeding roller to the conveyance of the recording medium, a larger amount of the release agent is applied to the fixing means than in the case of the normal single-sided image formation. Image forming apparatus. 10. An image having an image forming section for forming a developed image on a recording medium, a fixing means for fixing the developed image on the recording medium, and a releasing agent supplying means for supplying a releasing agent to the fixing means. In the forming apparatus, a heat insulating cover having a width substantially equal to or larger than the width in the thrust direction of the nip portion formed by the fixing roller and the pressure roller forming the fixing means is provided, and the mold releasing is performed on the heat insulating cover. An image forming apparatus characterized by being filled with an agent.