JP2002062754A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an adverse influence on transferring performance due to sticking of a release agent to the backside of a recording sheet, when both sides printing is performed while securing releasing performance. SOLUTION: In a fixing device for an image forming apparatus, control is carried out by a control means 18, so that release agent coating by driving of a web motor 85 for printing a back side is started earlier than the coating for printing a front side, when a both sides passing mode is set by a paper- passing mode setting means 81.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device suitable for use in an electrophotographic or other image forming apparatus, for example, a printer, a facsimile or a copying machine, and more particularly to a fixing belt type fixing device.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile, a latent image corresponding to an image is formed by irradiating a charged photoconductive material with light corresponding to the image. . The development is performed by electrostatically adsorbing toner to the latent image, and the developed toner image is directly transferred and adsorbed on the recording sheet. Alternatively, the image is temporarily transferred to an intermediate transfer member and then transferred to a recording sheet.

When a recording sheet on which a toner image is electrostatically carried in this way passes through a fixing device, heat and pressure are usually applied to fix the toner image to the recording sheet. In a monochrome image forming apparatus, a single color toner is used.
In a color image forming apparatus, normally, three primary colors (yellow, cyan, and magenta) for reproducing a color image and black toner are used so as to overlap each other. The principle of these techniques is well known.

The above-mentioned fixing device is provided with a release agent applying means, and when the heat and pressure are applied to the fixing device, the toner adsorbed on the recording sheet is transferred to the fixing means side. A release agent is applied to this to prevent sticking.

[0005] The release agent application means includes a pumping system for pumping the release agent from a release agent tank, an impregnating roller system using an impregnated roller impregnated with the release agent, and a release agent impregnated with the core. 2. Description of the Related Art A web system in which a web wound around gold is wound while directly or indirectly contacting the fixing device side has been put into practical use.

An example of such a fixing technique is disclosed in Japanese Patent Application Laid-Open No. H06-110351.
Change the release agent application conditions such as the amount or type of application. ), JP-A-10-307503 (the feed amount is changed according to the driving torque of the web), and JP-A-9-2.
Japanese Patent Application Laid-Open No. 81838 (in which the web drive interval is changed and controlled in accordance with the durability state) and other techniques for changing and controlling the release agent application amount in accordance with the type of recording sheet and image density are known. Further, a fuse is provided inside the release agent applying means, and when it is new, it is determined whether or not it is new by a conductive fuse, and when it is new, after detecting this, the fuse is electrically cut off. Things are known.

[0007]

SUMMARY OF THE INVENTION The purpose of these techniques is to secure the separation of a recording sheet from a fixing device by changing a release agent application amount according to a paper passing mode or a type of recording paper. However, it is an object of the present invention to prevent a negative effect on transferability due to a release agent adhering to the back surface of a recording sheet during double-sided printing while ensuring release properties.

Further, conventionally, when a recording sheet is jammed, it is possible to prevent the toner from adhering to the fixing means due to no special control of the release agent applying means and to prevent the formed image from being stained due to the toner adhesion to the fixing means. Make it an issue.

Further, since the state of the release agent applying means is not conventionally controlled when the state of the release agent applying means is detected, especially when it is detected that the article is new, the adhesive is attached before the release agent applying means is replaced. An object of the present invention is to prevent the generated toner stains from being formed on the formed image without being cleaned, or in particular, in the case of the web system, to prevent the occurrence of a trouble such as a slack portion of the web generated at the time of replacement.

[0010]

The above object is achieved by the following means. That is, a first aspect of the present invention provides a fixing device for an image forming apparatus and a release agent for preventing the toner adsorbed on a recording sheet from adhering to the fixing device. And a release agent applying means for applying the fixing agent, wherein the fixing device further comprises the release agent applying means according to a paper passing mode set in the image forming apparatus. Is provided with an application control means for controlling the timing of starting the application of the release agent.

According to a second aspect of the present invention, in the fixing device according to the first aspect, the coating control means includes a step of: The timing of starting the application of the release agent by the release agent applying means is set earlier than when the first side of the recording sheet is printed than when the first side of the recording sheet is printed. Is controlled.

According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the release agent applying means includes a release agent supply roll wound around a web impregnated with the release agent. And a web take-up reel for taking up the web of the release agent supply roll, wherein the application control means controls driving of the web take-up reel to take up the web. It is something that is.

According to a fourth aspect of the present invention, there is provided a fixing unit for an image forming apparatus, and a mold release unit for preventing toner adsorbed on a recording sheet from adhering to the fixing unit. And a release agent applying means for applying an agent, the fixing device further comprising: a control unit configured to control whether the image forming apparatus is in a post-processing control mode after removing a jam of the recording sheet. And an application control means for controlling the operation start timing of the release agent applying means.

According to a fifth aspect of the present invention, there is provided a fixing device according to the fourth aspect, wherein the release agent applying means includes a release agent supply roll around which a web impregnated with the release agent is wound. A web take-up reel for winding up the web of the release agent supply roll, wherein the fixing unit sets the fixing unit to 1 when the image forming apparatus is in the post-processing control mode. This is a fixing driving means for driving the rotation more than the rotation.

According to a sixth aspect of the present invention, in the fixing device of the fourth aspect, the release agent applying means includes a release agent supply roll around which a web impregnated with the release agent is wound; A web take-up reel for winding up the web of the release agent supply roll, wherein the application control means is web drive control means for controlling the driving of the web take-up reel to wind up the web, Further, when the image forming apparatus is in the post-processing control mode, the release agent applying unit is driven by a predetermined amount before the fixing unit is driven.

According to a seventh aspect of the present invention, there is provided a fixing device for an image forming apparatus, and a mold release device for preventing toner adsorbed on a recording sheet from adhering to the fixing device. A release agent applying unit for applying an agent, the fixing device further comprising: a state detecting unit for detecting a state of the release agent applying unit; and a state detecting unit. Coating control means for controlling the operation start timing of the release agent applying means according to the detected state of the release agent applying means.

According to an eighth aspect of the present invention, in the fixing device according to the seventh aspect, the state detecting means is a new article detecting means for detecting replacement of the release agent applying means or detection of newness. There is something.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus to which the present invention is applied and a fixing device thereof will be described below with reference to FIGS.

FIG. 1 is a sectional view showing a schematic configuration of a tandem process type image forming apparatus to which the present invention is applied, more specifically, a color printer. This example is of an intermediate transfer belt type.

The image forming units 1 for forming the toner images of black (BK), yellow (Y), magenta (M), and cyan (C) are arranged along the intermediate transfer belt 11 circulating in the direction indicated by the large arrow. BK → Y → M from upstream
→ C is arranged in order. Photoconductor 2 of image forming unit 1 (photoconductor drum, hereinafter simply referred to simply as photoconductor)
The toner image developed above is transferred onto the intermediate transfer belt 11 by a primary transfer unit 12 described below at a contact position with the intermediate transfer belt 11.

Each time the toner image transferred onto the intermediate transfer belt 11 passes through each of the image forming units 1, each color is superimposed thereon, and a full-color toner image is finally formed on the intermediate transfer belt 11. Is done. afterwards,
Further downstream, the image is collectively transferred to a recording sheet 14 such as paper by a so-called secondary transfer unit 13, and the recording sheet 14 passes through an upper fixing device 30, where the toner image is fixed and is placed on a discharge tray 16. The paper is usually discharged.

This image forming apparatus is provided with a switchback mechanism 20 for enabling double-sided printing. When the sheet passing mode is the duplex mode, after the first side is printed, the recording sheet 14 is once conveyed to the switchback mechanism 20 without being discharged. Here, the data is switched back and sent to the secondary transfer means 13 again to perform the transfer to the second surface. The recording sheets 14 are stored in the lowermost recording sheet cassette 17 and are conveyed one by one from there to the transfer means 13.

The toner remaining on the intermediate transfer belt 11 after the secondary transfer is removed from the intermediate transfer belt 11 by the cleaning blade 15, conveyed by a conveying screw (not shown), and collected in a waste toner container (not shown).

The control unit 18 controls the entire image forming apparatus (in this case, a color printer).
From this, a signal corresponding to the image is sent to the exposure control device 19. The exposure control device 19 controls an exposure unit 9 described later according to each color.
To drive each.

The image forming unit 1 includes a charging unit 3 for uniformly charging the photosensitive member 2, an exposure unit 9 for exposing the charged photosensitive member to an image, and an electrostatic latent image formed by the exposure. Developing means 4 for developing with toner is provided. The developed toner image is transferred to a primary transfer unit 1
2 is primarily transferred to the intermediate transfer belt 11.

After the primary transfer, the toner remaining on the photoreceptor 2 is removed by the cleaning means 5 disposed downstream, and is collected from below the cleaning means 5.

FIG. 2 is an enlarged sectional view of the fixing device 30 described above. The fixing device 30 includes a fixing main unit 31 and a web unit 32. The fixing main unit 31 includes a first roller 33, a second roller 34, a third roller 35, a driving source 36, a fixing belt 37, a heater 38, a donor roller 39, a lower guide 40L, and an upper guide 40U.

A fixing belt 37 is stretched between the first roller 33 and the second roller 34, and the third roller 35
Since the urging force in the direction of the first roller 33 (urging means is not shown) is applied, the fixing belt 37 is in a state of being sandwiched between them. A driving source 36 is connected to the first roller 33. When the driving source 36 is rotated by the driving force of the driving source 36, the fixing belt 37 circulates in the direction of arrow C. At this time, in this example, the second roller 34
And the third roller 35 is also driven to rotate. Note that the third roller 35 can be actively driven.

The interior of the second roller 34 is hollow, and a heater 38 is provided in the hollow. Heater 3
8 is transferred to the second roller 34 outside the second roller 34.
From the fixing belt 37 to the fixing belt 37.
7, the first roller 33 and the third roller 3
Transported between 5

When the recording sheet on which the toner is adsorbed by the transfer means 13 is conveyed to the lower guide 40L, it is introduced between the fixing belt 37 and the third roller 35 (nip portion) as shown by an arrow A, where it is introduced. The fixing is performed by receiving the heat of the fixing belt 37 and the pressure from the third roller 35. The fixed recording sheet is conveyed upward along arrow B, and is further conveyed to the discharge tray 16 or the switchback mechanism 20 for backside printing while being guided by the upper guide 40U. .

The fixing belt 37 includes a donor roller 3
9 is in contact engagement with the fixing belt 3 when viewed from the contact portion.
7 rotates in the same direction (arrow D). The donor roller 39 is for applying a release agent to the surface of the fixing belt 37. This will be described later.

When heat and pressure are applied in the fixing device 30, the toner that has been electrostatically adsorbed is firmly fixed to the recording sheet so that the toner is not separated from the recording sheet even if the static electricity is lost. However, a part of the toner may adhere to the side of the fixing belt. This is called a toner offset phenomenon. The adhering toner is returned to the nip portion by the circulation of the fixing belt 37, so that the adhering toner adheres to a new recording sheet or another place on the same recording sheet and causes image noise such as dirt.
The release agent is applied to the fixing belt 37 in order to prevent such a toner offset phenomenon. For example, silicone oil is often used as the release agent.

A connector 90 is provided below the fixing main unit 31. Through the connector 90, power for the heater 38 and others is supplied, and various signals are transmitted and received. This signal includes the second roller 3
4 is also included.

The web unit 32 includes a web supply roll 41, a web take-up reel 42, a backup roller 43, and a fuse 86 (see FIG. 3). The web supply roll 41 is formed by winding a web 44 impregnated with a release agent around a cored bar, and a web take-up reel 42 is used to wind up the web 44. The web 44 is wound around a backup roller 43 and then wound around a web take-up reel 42.

The web unit 32 is used as the fixing main unit 3
When the web unit 32 is loaded, the web 44 hung on the backup roller 43 comes into contact with the donor roller 39, and the web drive 32 is loaded on the web take-up reel 42 with the web unit 32 loaded. Power is supplied from a motor Mw (see FIG. 3).

It should be noted that the web supply roll 41 is lightly braked, and an appropriate tension is applied to the web 44 to be applied, so that the web supply roll 41 may rotate excessively or be caught by the web 44. Prevents sagging that can cause.

The winding speed of the web 44 is very slow, and the impregnated release agent is gradually applied to the donor roller 39 which comes into contact with the web 44. The direction in which the web 44 is fed from the web supply roll 41 is clockwise, while the direction in which the web take-up reel 42 winds the web 44 is counterclockwise. That is,
In this example, the side on which the web 44 is fed and the side on which the web is wound are both on the same side of the axis (the right side in this figure).

The web unit 32 is replaceable,
When all the webs 44 in the web unit 32 are used up, that is, when all the webs 44 are wound around the web take-up reel 42, the web unit 32 is replaced with a new web unit 32.

FIG. 3 is a block diagram of the main part of the web unit 32, the control device 18 and its peripheral devices. Note that the control device 18 controls the entire image forming apparatus, but only the portion according to the present invention is shown here. The control device 18 includes a paper passing mode setting means 81, a paper sensor 8
2. A new article detector 83 and a web motor driver (Mw motor) 84 are connected, and a web motor 85 is connected to the web motor driver 84.

The paper passing mode setting means 81 is provided for the recording sheet 1
An operator inputs a mode to be printed in the control unit 4 and sets it in the control device 18 (image forming apparatus). Specifically, only the front side (first side) of the recording sheet is printed, or the back side (second side) is printed together with the front side.
Side) is set.

The paper sensor 82 detects the position of the leading or trailing edge of the recording sheet 14 in the image forming apparatus, and includes a plurality of sensors. Within a predetermined period of time after each sheet sensor 82 detects the leading or trailing edge of the recording sheet 14, the next sheet sensor 82
When the leading end or the trailing end of No. 4 is not detected, it can be determined that a jam (paper jam) has occurred. Some of the paper sensors 82 are provided immediately before the fixing device 30 and detect that the recording sheet 14 is about to enter the fixing device 30.

The new article detector 83 is a detector for detecting that the web unit 32 is new, that is, detecting that the web unit 32 has never been used or has been used once. . The new detector 83 is
When it is connected to the fuse 86 attached to the web unit 32 and it is detected that the fuse 86 is not blown, it is determined that the web unit 32 is new. Therefore, if the fuse 86 is blown,
This indicates that it is not new.

The new detector 83 has another function. That is, when it is detected that the web unit 32 is new (that is, when the fuse 86 is not blown), a large current is applied to the fuse 86 to cut it, and thereafter, the web unit is not new. Performs the function of indicating that

The web motor driver 84 supplies power to the web motor 85 for the web take-up reel 42 to wind up the web 44.
Controls the power or drive pulse.
The web motor 85 may be provided on the web unit 32 or provided outside, so that only the driving force is transmitted to the web take-up reel 42.

The control device 18 includes a paper passing mode setting means 81
Allows the paper passing mode to be duplex mode (front and back print mode)
Is set, the function to store and determine whether the printing to be executed is on the front side or the back side of the recording sheet. The timing at which the release agent is started to be applied by driving the web motor 85 is such that the second surface (back surface) of the recording sheet is printed more than when the first surface (front surface) of the recording sheet is printed. The timing is controlled so as to be earlier. That is, in the present invention, the timing at which the web unit 32 starts applying the release agent to the fixing belt 37 is controlled in accordance with the paper passing mode set in the image forming apparatus.

Thus, in the duplex mode, the amount of the release agent adhering to the back surface of the recording sheet is reduced, and the fixing belt 3
In addition to preventing the release agent from adhering to the recording medium 7, the occurrence of image noise such as image disturbance and hollowing out can be prevented, and the releasability and the separation property of the recording sheet in the fixing device can be kept good.

When the recording sheet 14 is jammed, the jam is detected by the paper sensor 82, the occurrence of the jam is displayed on a display means (not shown), and the jam is manually removed. Control device 18
Monitors the mode of the image forming apparatus, and after processing this jam, enters the post-processing mode. Then, it is determined whether or not the apparatus is in the post-processing control mode. In response to this, the timing at which the web unit 32 starts to apply the release agent to the fixing belt 37 is such that one or more rotations of the fixing belt 37 are secured. Is controlled. That is, the web take-up reel 42 is driven by a predetermined amount before the fixing device is driven.

As a result, it is possible to clean toner stains adhered to a fixing belt or the like in the fixing device at the time of jam processing or the like, so that toner stains or the like in print output after jam processing can be reduced.

Further, the controller 18 detects the state of the web unit, that is, whether or not the web unit 32 is new, using the new article detector 83, and
If 2 is new, the timing at which the web unit 32 starts applying the release agent is controlled so that one or more rotations of the fixing belt 37 are secured. As a result, when the web unit 32 is replaced, dirt such as toner adhered to a fixing belt or the like in the fixing device is cleaned in advance, and it is possible to prevent the web from being entangled due to slack at this time.

[0050]

As described above, the present invention reduces the amount of the release agent adhering to the back surface of the recording sheet in the double-sided mode, prevents the release agent from adhering to the fixing means, and improves the image quality. It is possible to prevent the occurrence of image noise such as turbulence, hollow spots, and the like, and to maintain good releasability in the fixing device and good separability of the recording sheet.

Further, since the toner stains adhering to the inside of the fixing device at the time of the jam processing can be cleaned, it is possible to reduce the toner stains in the print output after the jam processing. Further, there is an effect that dirt such as toner adhered to the fixing device at the time of replacement of the release agent applying means is cleaned in advance, and it is possible to prevent the web from being entangled due to the slack at this time. .

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of a tandem process type color printer to which the present invention is applied.

FIG. 2 is an enlarged sectional view of a fixing device 30 according to the present invention.

FIG. 3 is a block diagram of a main part of a web unit 32, a control device 18, and peripheral devices thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming unit 2 Photoreceptor 3 Charging means 4 Developing means 5 Cleaning means 9 Exposure means 11 Intermediate transfer belt 12 Primary transfer means 13 Secondary transfer means 14 Recording sheet 15 Cleaning blade 16 Discharge tray 17 Recording sheet cassette 18 Controller DESCRIPTION OF SYMBOLS 19 Exposure control apparatus 20 Switchback mechanism 30 Fixing device 31 Fixing main unit 32 Web unit 33 First roller 34 Second roller 35 Third roller 36 Drive source 37 Fixing belt 38 Heater 39 Donor roller 41 Web supply roll 42 Web take-up reel 43 Backup roller 44 Web 81 Paper passing mode setting means 82 Paper sensor 83 New article detector 84 Web motor driver 85 Web motor 86 Fuse 90 Connector Mw Web drive motor 40L Lower guide 0U on the guide

Continued on the front page F-term (reference) 2H028 BA12 BB04 2H033 AA46 BA11 BA12 BA43 BA44 BA46 CA22 CA26

Claims (8)

[Claims] A fixing unit for the image forming apparatus; and a mold release agent for applying a release agent to the fixing unit to prevent the toner adsorbed on the recording sheet from adhering to the fixing unit. Wherein the release agent applying means further applies a release agent to the fixing means in accordance with a paper passing mode set in the image forming apparatus. A fixing device comprising a coating control unit for controlling a start timing. 2. The fixing device according to claim 1, wherein the application control unit is configured to execute the release agent applying unit when a sheet passing mode set in the image forming apparatus is a mode for performing duplex printing. The timing of starting the application of the release agent is controlled so that the timing of printing the second surface of the recording sheet is earlier than the timing of printing the first surface of the recording sheet. A fixing device. 3. The fixing device according to claim 1, wherein the release agent applying unit includes: a release agent supply roll around which a web impregnated with the release agent is wound; A web take-up reel that winds up the web of the agent supply roll, wherein the application control unit is a web drive control unit that controls driving of the web take-up reel to wind up the web. Fixing device. 4. A fixing means for an image forming apparatus, and a release for applying a release agent to said fixing means in order to prevent toner adsorbed on a recording sheet from adhering to said fixing means. And a coating agent applying unit. The fixing device further includes a release agent applying unit that determines whether the image forming apparatus is in a post-processing control mode after removing a jam of the recording sheet. A fixing device comprising a coating control unit for controlling operation start timing. 5. The fixing device according to claim 4, wherein the release agent applying unit includes: a release agent supply roll around which a web impregnated with the release agent is wound; A web take-up reel for winding up the web, and a release agent applying unit, wherein the fixing unit drives the fixing unit one or more rotations when the image forming apparatus is in the post-processing control mode. A fixing device comprising: 6. The fixing device according to claim 4, wherein the release agent applying unit includes: a release agent supply roll around which a web impregnated with the release agent is wound; A web take-up reel for taking up the web, wherein the application control means is web drive control means for controlling the driving of the web take-up reel to take up the web, and the image forming apparatus further comprises: A fixing device according to claim 1, wherein, in the post-processing control mode, the release agent applying unit is driven by a predetermined amount prior to driving of the fixing unit. 7. A fixing unit for an image forming apparatus, and a release for applying a release agent to the fixing unit in order to prevent toner adsorbed on a recording sheet from adhering to the fixing unit. Wherein the fixing device further comprises: a state detecting means for detecting a state of the release agent applying means; and a release agent applying means detected by the state detecting means. A coating control means for controlling the operation start timing of the release agent applying means in accordance with the state of the fixing device. 8. The fixing device according to claim 7, wherein the state detecting unit is a new unit detecting unit that detects replacement of the release agent applying unit or that the unit is new. apparatus.