CN1790189A - Fixing device - Google Patents

Abstract

There is provided a fixing device including a pressing member pressing and contacting a supporter on an upstream side or a downstream side of an endless belt. The two bridging portions of the endless belt extending between the supports, since one end of the bridging portion is compressed between the supporting means and the pressing element, one bridging portion is tensioned and the other is not. The contact between the pressing member and the outer surface of the bridge portion being tensioned forms a fixing nip.

Description

Fixing device

technical field

The present invention relates to a fixing device. More specifically, the present invention relates to a fixing device provided in a photolithographic image forming apparatus such as a laser printer, a laser facsimile or a digital copier.

Background technique

In a photolithographic image forming apparatus, the surface of a photosensitive drum is charged and then scanned by a laser scanning unit or the like to form an electrostatic latent image according to an image signal. Thereafter, the charged toner is adsorbed onto the photosensitive drum and developed with a developer to form a toner image. Then, the toner image is transferred to paper (recording medium). The toner image transferred to the paper adheres to the paper, that is, is not fixed thereon, and the toner image is melted with heat and pressure to be fixed on the paper by a fixing device.

A conventional fixing device basically includes a cylindrical metal heat roller (electric heating element), a pressure roller (pressing element) that presses and contacts the heat roller, and a halogen lamp installed in the heat roller to heat the heat roller with radiant heat (heat source). In the fixing device (2-roller type), paper on which a toner image is formed passes through a fixing nip formed between a heat roller and a pressure roller, which contact each other with pressure so that the toner image is heated by the heat roller , and through the pressure contact of the hot roller and the pressure roller, it is pressed and fixed to the page.

However, with conventional fixing devices, it takes a considerable period of time to heat the heat roller at room temperature to reach a fixing temperature of about 160-200°C at which the toner melts. Therefore, the conventional fixing device takes a very long heating time after power is applied but before actual printing. Also, the fixing device maintains its high temperature, because this shortens the time interval between the stop of printing and the start of printing. The fusing unit needs to be heated with a halogen lamp to keep it hot. This results in increased power consumption.

In order to overcome these disadvantages of conventional 2-roll type fixing devices, fixing devices capable of reducing heating time and power consumption have recently been proposed.

One of the proposed fixing devices is an induction heating (IH) fixing device that realizes heat generation by an induced current using magnetic flux. The IH fixing device basically includes a cylindrical or semi-cylindrical seat, a cylindrical thin film including a stack of conductive layers and a resistive layer installed in the seat, a magnetic field generating unit installed in the seat and composed of an excitation coil and a magnetic core, and a pressure roller that presses and contacts the outer peripheral surface of the film to form a fixing nip. In the IH fixing device, an Eddy current is generated by a magnetic flux generated by a magnetic field generating unit. As a result, Joule heat is generated by Eddie current on the conductive layer, and the temperature of the fixing nip is raised by Joule heat. Due to the IH, the temperature of the fixing nip can be raised to the fixing temperature in a short period of time, and the heating time period can be shortened. Also, as described in Japanese Patent Laid-Open No. 2004-126274, the entire disclosure of which is incorporated herein by reference, since a cylindrical film has a low heat capacity compared with a heat roller, power consumption can be reduced. However, since the IH fixing device requires a magnetic field generating unit, it requires high component costs compared with a 2-roller type fixing device. Also, because the inner surface of the film slides on a member such as a seat, the durability of the film is limited due to wear of the seat portion on which the film slides. Therefore, the choice of film materials is rather narrow.

There is also a pressure belt pinch type fixing device, which includes a tubular pressure belt instead of the pressure roller included in the 2-roller type fixing device. The fixing nip is formed by pressing a portion of the inner surface of the pressure belt toward the heat roller so that the outer surface of the pressure belt corresponding to the pressed inner surface portion contacts the heat roller. A pressure belt pressing type fixing device basically includes a heat roller that is heated by a heat source such as a halogen lamp and rotates axially, an endless pressure belt that contacts the heat roller and is moved by movement of the heat roller, and presses the inside of the pressure belt toward the surface of the heat roller. The pressing element of the surface, so that the outer surface of the pressure belt corresponding to the inner surface being pressed contacts the thermal roller. As described in Japanese Patent Laid-Open No. 2004-12682, the entire disclosure of which is hereby incorporated by reference, since the fixing nip is formed by pressing a pressure belt on a heat roller, the fixing nip is wide so that they contact each other . Therefore, heating time and power consumption can be reduced, and component costs can be reduced from those required for the IH fixing device. However, since the inner surface of the pressure belt is pressed by the pressing member and slides on the heat roller, the durability of the pressure belt or the pressing member is still limited due to wear of the heat roller on which the pressure belt slides. Or the choice of compression element material is still very narrow.

In addition, the heat belt type fixing device includes a cylindrical heat belt unit including an endless heat belt freely movable in the main direction instead of the heat roller included in the 2-roller type fixing device. The fixing nip is formed by contacting the heat belt with pressure with a cylindrical pressure roller. The heat belt type fixing device basically includes a heat belt unit made by winding an endless heat belt around a backup roller and a cylindrical heat roller. A cylindrical pressure roller presses the bridge portion of the heat tape extending between the backup roller and the heat roller to contact the bridge portion. Halogen lamps are installed in heat rollers or pressure rollers. In the tropical type fixing device, a wide fixing nip is formed so that heating time and power consumption can be reduced. Also, since no sliding occurs, no wear occurs. Therefore, many materials used for heat strips can be used. Furthermore, as described in Japanese Patent Laid-Open No. 2004-205877, the entire disclosure of which is incorporated herein by reference, the component cost is lower than that of the IH fixing device.

However, since the heat belt in the heat belt type fixing device is supported by the support roller and the heat roller and is tensioned, when the heat belt rotates, it moves toward the axis of the support roller. Alternatively, the heat rolls may tilt due to dimensional accuracy, mounting accuracy of each roll, or lateral deviation around the belt.

Therefore, there is a need for a fixing device capable of reducing heating time, power consumption, and belt tilt to reliably fix a toner image to a sheet.

Contents of the invention

Aspects of the present invention are to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a fixing device that can reduce heating time, power consumption, and inclination of an endless belt to reliably fix a toner image to a sheet, and to provide a fixing device including the fixing device. imaging equipment.

According to an aspect of the present invention, there is provided a fixing device including at least two supporters, an endless belt movably supported by the supporters in a main direction and including two bridging portions, a heat source for heating the endless belt, pressing the endless belt When the recording medium on which the toner image is electrostatically adhered passes through the fixing nip formed between the belt and the pressing member, the toner image is melted and fixed on the recording medium. The pressing element presses against and contacts one of the supports on the upstream or downstream side of the endless belt. Two bridging portions of the belt extend between the supports. Since one end of one of the bridging parts is compressed between the support and the pressing element, the bridging part is tensioned and the other bridging part is loosened. The fixing nip is formed by the contact of the pressing member with the outer surface of the bridged portion being stretched, and extends from a position where the fixing belt is pressed between the supporter and the pressing member to a predetermined position on the upstream side.

A clamping member is mounted on the lateral side of the upstream side supporter to press and contact the supporter, and the belt is pressed between the supporter and the clamping member.

According to another aspect of the present invention, there is provided an image forming apparatus including an image forming unit that electrostatically transfers a toner image onto a recording medium, and the above-mentioned fixing device.

Other objects, advantages and salient features of the present invention will become apparent to those skilled in the art from the following detailed description, which discloses exemplary embodiments of the present invention when taken in conjunction with the accompanying drawings.

Description of drawings

The above and other objects, features and advantages of some exemplary embodiments of the present invention will be more apparent from the following description in conjunction with the accompanying drawings, in which:

1 is a schematic diagram of a fixing device and an image forming apparatus including the fixing device according to an embodiment of the present invention; and

2 is a schematic diagram of a fixing device;

Throughout the drawings, it should be understood that like reference numerals refer to like elements, features, and structures.

Detailed ways

Matters defined in the description, such as detailed structures and elements, are provided to help understanding of the embodiments of the present invention. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope and spirit of the invention. Also, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

As shown in FIG. 1 , an image forming apparatus 1 includes a transfer unit 2 on which a plurality of image forming units 3M, 3Y, 3C, and 3BK are mounted to electrostatically transfer a toner image to a sheet (recording medium) X, such as paper, also includes a fixing device 4 for melting and fixing the toner image to the sheet X when the sheet X on which the toner image is formed is conveyed.

The image forming units 3M, 3Y, 3C, and 3BK charge the photosensitive drum (image carrier) 6, expose to light by scanning the surface of the charged photosensitive drum 6 with laser light 11 to form a latent image, develop the latent image into a toner image, and The toner image is transferred onto the sheet X conveyed by the transfer belt 10 . The image forming units 3M, 3Y, 3C, and 3BK are arranged in sequence along the transfer belt 10 in the direction in which the sheet X is conveyed by the transfer belt 10 to form magenta, yellow, cyan, and black toner images, respectively. Each image forming unit 3M, 3Y, 3C, and 3BK includes a photosensitive drum 6 , an exposure device 7 , a developer 8 , a charging roller 9 , and a cleaning unit 19 .

The photosensitive drum 6, which is an image carrier, is axially rotated in the direction indicated by the arrow shown in FIG. 1, and is scanned with laser light 11 emitted from an exposure device 7 to form an electrostatic latent image. The exposure device 7 scans the surface of the photosensitive drum 6 with laser light 11 in a direction parallel to the rotation axis of the photosensitive drum 6 .

The developer 8 develops the latent image to form a toner image. More specifically, the developer 8 rubs powdery toner having a predetermined color against each other, charges the same negative charge, and supplies and absorbs the charged toner to the exposed portion of the photosensitive drum 6, which is not connected to the same portion. The potential of the exposed portion has a positive potential compared to that. The developer 8 includes toner, an agitator 12d for agitating the toner to charge the same charge, and a supply roller 12c for transferring the charged toner to the developing roller 12a. The developing roller 12a has toner supplied from the supply roller 12c, adsorbed to its surface by Coulomb force generated by the charge of the toner, for transferring the toner onto the photosensitive drum 6 to form a toner layer. The developing blade 12b restricts the thickness of the toner layer to a predetermined thickness.

The cleaning unit 19 includes a drum cleaning roller 19a and a housing (not shown). The cleaning roller 19 a contacts the photosensitive drum 6 to remove toner from the surface of the photosensitive drum 6 . The housing is installed near the cleaning roller 19a to collect the toner removed by the cleaning roller 19a.

The charging roller 9 changes the surface potential of the photosensitive drum 6 to a predetermined potential during image formation. The charging roller 9 includes a metal shaft and a roller portion formed of a conductive elastomer on the metal shaft, and contacts the photosensitive drum 6 at a charging position on the downstream side of the photosensitive drum cleaning roller 19 a. By pressing a bearing (not shown) using an elastic biasing unit such as a spring, the charging roller 9 contacts the photosensitive drum 6 from a predetermined width in the main direction, thereby forming a nip corresponding to the predetermined width. When receiving a DC voltage, the charging roller 9 charges the surface of the photosensitive drum 6 to a predetermined potential. The charging roller cleaning roller 20 is in contact with the charging roller 9 to prevent contamination of the surface of the charging roller 9 .

The transfer unit 2 includes an endless transfer belt 10 , a driving roller 13 a , a transfer roller 16 a and a belt cleaning unit 17 . The endless transfer belt 10 circulates in one direction by drive rollers 13 b and 13 c and a tension roller 14 installed on the inner peripheral surface of the transfer unit 2 . The transfer roller 16 a keeps the transfer belt 10 in contact with the photosensitive drum 6 at the transfer position. The belt cleaning unit 17 includes a cleaning blade (not shown) for scraping off foreign matter on the surface of the transfer belt 10 and a space for collecting the removed foreign matter.

The transfer belt 10 is, for example, a dielectric sheet, and when the page X is between the transfer belt 10 and the photosensitive drum 6, the toner on the photosensitive drum 6 can be adsorbed by a transfer voltage applied to the transfer roller 16a. The transfer belt 10 has optical reflectivity, that is, reflects light.

The transfer roller 16a is made by forming a roller unit which may be formed of conductive and semiconductive synthetic rubber on a metal rotating shaft. A transfer high-voltage power supply (not shown) is connected to the rotation shaft to control the surface potential of the roller unit.

The transfer roller 16a and the controller 16 for controlling the roller unit surface potential of the transfer roller 16a constitute a transfer portion 18 for electrostatically transferring the toner images formed by the image forming units 3M, 3Y, 3C, and 3BK to the on the page X conveyed by the transfer belt 10.

The fixing device 4 will now be described in more detail with reference to FIG. 2 . As shown in FIG. 2, the fixing device 4 includes two supporters 21, and an endless (cylindrical) fixing belt 22 movably supported by the supporters 21 in the main direction is installed inside the fixing belt 22 together with the supporters 21 for heating. The heat source 23 of the fixing belt presses a supporter 21 on the downstream side in the sheet conveyance direction to contact the pressing member 24 of a part of the fixing belt extending from the downstream side supporter 21 to a position toward its upstream side, and is installed upstream The clamping element 25 on the lateral side of the other support 21 .

Two holders 21 are mounted inside the cylindrical fixing belt 22 , each having a cylinder capable of axial rotation in one direction. The supporter 21 on the downstream side (left side in FIG. 2 ) in the sheet X transfer direction (rotation direction of the pressing member 24 ) contacts the pressing member 24 via the fixing belt 22 . On the other hand, the supporter 21 on the upstream side in the conveying direction of the sheet X is separated from the pressing member 24 . The outer peripheral surface of the upstream support 21 is partially covered by the fixing belt 22 . The downstream side support 21 corresponds to a drive roller 26 which is axially rotated by a drive mechanism (not shown). The upstream side supporter corresponds to the guide roller 27 which prevents the movement of the fixing belt 22 in the main direction with rotational resistance.

The fixing belt 22 is a thin member whose length is greater than the width of the page X, and when no external force is applied, the shape of the fixing belt 22 is substantially cylindrical. Also, the fixing belt 22 is formed by sequentially laminating an elastic layer formed of heat-resistant rubber having a thickness of, for example, approximately It is made of a toner release layer formed of a highly heat-resistant fluororesin or a fluororesin-modified material such as polytetrafluoroethylene, which is about several tens of micrometers.

The fixing belt 22 is supported by a drive roller 26 and a guide roller 27 inside the fixing belt 22 . The driving roller 26 supports the fixing belt 22 by interposing the fixing belt 22 between the driving roller 26 and the pressing member 24 in contact with each other and pressing the fixing belt 22 therebetween. The guide roller 27 supports the fixing belt 22 wrapped around a part of its outer peripheral surface by pressing the fixing belt 22 against the pinch member 25 . Therefore, the inner surface of the fixing belt 22 is pressed against the drive roller 26 and the guide roller 27 , and rubs and contacts the drive roller 26 and the guide roller 27 . The fixing belt 22 is movable in the main direction via an axially rotating drive roller 26 .

By rotating the driving roller 26, the bridge portion 28 of the fixing belt 22 extending between the driving roller 26 and the guide roller 27 and close to the pressing member 24 is tensioned because both ends thereof are pressed against the driving roller 26 and the pressing member 24, respectively. Between and between the guide roller 27 and the clamping element 25. At the same time, the bridge portion 29 of the fixing belt 22 also extending between the drive roller 26 and the guide roller 27 and away from the pressing member 24 is not tensioned.

The heat source 23 may be a halogen lamp. The heat source 23 includes a main body installed in the fixing belt 22, and heats the fixing belt 22 using radiant heat emitted from the main body. The heat source 23 is installed such that the main body is disposed near the fixing nip 30 formed by the contact of the outer surface of the bridge portion 28 of the fixing belt 22 tensioned with the pressing member 24 .

The pressing member 24 is cylindrical and axially rotatable in one direction. The pressing member 24 is made by winding a heat-resistant elastic layer 24b such as a silicone rubber layer around a metal core base 24a. The pressing member 24 presses and contacts a partially tensioned bridge portion 28 extending from the end pressed between the pressing member 24 and the drive roller 26 to a predetermined position in the direction of the guide roller 27 . The contact portion is the fixing nip 30 . Tangential pressure is applied to the fuser nip 30 through the tension of the tensioned bridge portion 28 . The pressure on the fixing nip 30 increases from the upstream end of the fixing nip 30 to its downstream end (towards the driving roller 26), because the downstream end is pressed by the driving roller 26 and the bridge portion 28 is pressed against the driving roller 26 and the pressing roller. Between tight elements 24. Therefore, as the toner image on the page X travels toward the drive roller 26 , it is compressed with increasing force as it passes through the fixing nip 30 . The pressing member 24 is axially rotated and moved in the main direction by the fixing belt 22 because it presses and directly contacts the outer peripheral surface of the fixing belt 22 .

The clamping member 25 is cylindrical and axially rotatable in one direction. The pinch member 25 is installed such that the circular portion 31 of the fixing belt 22 is wound around the upstream side supporter 21 and inserted between the pinch member 25 and the supporter 21 to be pressed therebetween. The clamp member 25 is also axially rotated by the moving fixing belt 22 because it directly contacts the outer peripheral surface of the fixing belt 22 .

The operation of the image forming apparatus 1 having the above-described structure will now be described in detail. Since the entire operation of the image forming apparatus 1 is basically the same as that of a conventional color printer, many parts are omitted except for the operation of the fixing device 4 for clarity and conciseness.

First, when the image forming apparatus 1 is manipulated, the heat source 23 is driven to perform a heating process, starting heating. More specifically, the heating is continued until the temperature of the fixing device 4 reaches a predetermined fixing temperature. At this time, the driving roller 26 is axially rotated by a driving mechanism (not shown), while the fixing belt 22 is moved in the main direction by rotating the driving roller 26 . When the fixing belt 22 moves, the guide roller 27 , the pinch member 25 , and the pressing member 24 rotate axially by moving the fixing belt 22 . The temperature of the image forming apparatus 1 rises due to heat radiation from the fixing device 4 , and a fan (not shown) generates forced convection around the fixing device 4 to cool the inside of the image forming apparatus 1 .

Next, when the temperature of the fixing device 4 reaches a predetermined fixing temperature, the image forming units 3M, 3Y, 3C, and 3BK start forming an image on the sheet X conveyed by the transfer belt 10 . More specifically, the surface of the photosensitive drum 6 charged by the charging roller 9 is scanned with laser light 11 to form a latent image. The latent image is developed by the developer 8 to form a toner image. The toner image formed on the surface of the photosensitive drum 6 is transferred onto the sheet X conveyed by the transfer belt 10 .

Thereafter, the sheet X on which the toner image is attached is conveyed to the fixing device 4 , and the toner image is fused and fixed to the sheet X as the sheet X passes between the fixing belt 22 and the pressing member 24 . More specifically, when the fixing belt 22 moves in the main direction, the sheet X on which the toner image is attached passes through the upstream end (ie, the right side of the nip 30 in FIG. 2 ) between the fixing belt 22 and the pressing member. 24 between the fixing nip 30 transport. The toner image on the sheet X in the fixing nip 30 is slowly melted by the heated fixing belt 22 and fixed to the sheet X by the pressing member 24 . The sheet X on which the toner image is fixed is sent out of the fixing nip 30 through the downstream end (ie, the left side of the fixing nip 30 in FIG. 2 ).

In this process, because the downstream end of the fixing nip 30 is in close contact with the pressing member 24 through the driving roller 26, the bridging portion 28 is pressed between the driving roller 26 and the pressing member 27, and the fixing nip 30 on the fixing nip The pressure increases from the upstream end of the fixing nip 30 to its downstream end near the drive roller 26 . Therefore, when the toner conveyed in the fixing nip 30 travels toward the drive roller 26 , it is compressed with increased pressure and pressed against the drive roller 26 . Therefore, the toner image is sufficiently fused, and then fixed to the sheet X.

In the fixing device 4, the pressing member 24 is pressed down on one of the two supporters 21 on the upstream side and the downstream side of the fixing belt 22, and by pressing the pressing member 24 between the two supporters 21, On the bridging portion 28 where the fixing belt 22 is stretched, a wide fixing nip 30 is formed. Therefore, a considerably long period of fixing time can be secured, and sufficient fixing is possible. Also, since the heated fixing belt 22 has a low heat capacity, heating time and power consumption can be reduced. Also, by the pressing member 24 pressing and contacting the supporter 21 on the upstream side or the downstream side, the bridging portion 28 near the pressing member 24 can be strained, and a pressure gradient can be applied to the fixing nip 30 . Therefore, the toner image can be fixed to the page X more reliably. In addition, because the bridge portion 29 that does not contact the pressing member 24 is loose, the bridge portion 29 can absorb deformation of the fixing belt 22 or movement of the fixing belt 22 due to deformation of the cross-sectional shape of the supporter 21 or other problems. Therefore, the bridging portion 29 can prevent the fixing belt 22 from moving in the axial direction of the supporter 21 . In addition, since the fixing device 4 is not composed of expensive components, it is also economical.

In the fixing device 4 , the pinch member 25 presses and contacts the fixing belt 22 inserted between the pinch member 25 and the supporter 21 on the upstream side of the fixing belt 22 . The pressing member 24 presses and contacts the fixing belt 22 inserted between the pressing member 24 and the downstream side supporter 21 . Therefore, a wide fixing nip 30 is formed, and a pressure gradient from upstream to downstream can be applied to the fixing nip 30 so that the end of the fixing nip 30 near the upstream side is pressed further. Therefore, a long fixing time can be ensured, and sufficient fixing is possible. Also, since the heated fixing belt 22 has a low heat capacity, heating time and power consumption can be reduced. Also, since fusing of the toner image produced while moving within the fixing nip 30 increases from the upstream side to the downstream side, the toner image on the downstream side can be fixed to the sheet X with high pressure. The toner image can be completed by the fuser nip 30 and fused to the sheet X more reliably.

In addition, since the fixing belt 22 is pressed between the downstream side supporter 21 and the pressing member 24, and between the upstream side supporter 21 and the pinching member 25, the bridge portion 28 in the vicinity of the pressing member 24 can be reliably tension. Furthermore, the bridging portion 29 remote from the pressing element 24 may not be tensioned.

The fixing device 4 reduces heating time, power consumption, inclination of the fixing belt 22, and includes low-cost components. As a result, the image forming apparatus 1 can provide shortened heating time and reduced power consumption without causing mechanical defects even at low cost.

Each of the two supports 21 for supporting the fixing belt 22 includes an axially rotatable driving roller 26 and a guide roller 27 , and a pressing member 24 pressing and contacting a bridge portion 28 of the fixing belt 22 . The two supports have the shape of axially rotatable rollers, substantially cylindrical. Therefore, no slippage occurs on the fixing belt 22, and the fixing belt 22 is not worn.

Although the invention has been particularly shown and described with reference to the embodiment shown in Figures 1 and 2, it will be understood by those skilled in the art that various changes in form and content may be made without departing from the spirit and scope of the invention as defined in the following claims . For example, in the above-described embodiment, the downstream side supporter 21 is pressed by the pressing member 24 , and the upstream side supporter 21 is pressed by the clamping member 25 . However, the downstream side supporter 21 may be pressed by the clamping member 25 , and the upstream side supporter 21 may be pressed by the pressing member 24 . In addition, the heat source 23 is installed inside the endless fixing belt 22 without contacting the inner peripheral surface thereof. But the heat source 23 may be installed in the upstream side supporter 21 and heat the supporter with radiant heat so that the fixing belt 22 is heated by the heated supporter. In addition, the heat source 23 can be installed outside the endless belt 22 to contact the electric heating element to directly heat the endless belt 22 .

Although two supporters 21 are installed on the upstream and downstream sides of the endless belt in the above-described embodiment, more than two supporters may be installed. If three supports 21 are installed, the supports on the upstream and downstream sides may be guide rollers, and the other support may be a driving roller.

The guide roller 27 , ie, the supporter 21 on the upstream side, has rotation resistance and prevents the main direction movement of the fixing belt 22 to tension the bridge portion 28 and the slack bridge portion 29 . However, by axially rotating the upstream supporter 21 at a higher linear speed than the downstream side supporter 21 by the driving mechanism, the bridge portion 28 can be tightened and the bridge portion 29 can be loosened, and the mutual friction of the fixing belt 22 and the drive roller 26 It is worse than the mutual friction between the fixing belt 22 and the guide roller 27 .

In the above-described embodiments, the image forming apparatus 1 includes a plurality of image forming units 3M, 3Y, 3C, and 3BK to realize color printing. However, an image forming apparatus according to an exemplary embodiment of the present invention may include only one image forming unit for monochrome printing. Also, since the fixing nip 30 is wide enough to prolong the heating and fusing time, it is particularly effective for a color printing apparatus in which color toner images are difficult to fuse and fix to a recording medium.

The recording medium is not limited to a sheet, and may be a sheet-shaped recording medium. The shape and material of the recording medium can be appropriately changed.

While the present invention has been shown and described with reference to certain embodiments, it will be understood by those skilled in the art that various changes in form and content may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

This application claims priority to Japanese Patent Application No. P2004-319699 filed on Nov. 2, 2004 and Korean Patent Application No. 10-2005-0072011 filed on Aug. 6, 2005, the entire contents of which are incorporated herein as refer to.

Claims (16)

1. fixing device comprises:

At least two eyelid retractors;

The endless belt, it by the removable support of described eyelid retractor, and is included in two bridging parts that extend between the eyelid retractor along a principal direction;

The thermal source of heating endless belt;

Compress the clamping element of endless belt, when photographic fixing clamping-extruding region by between described band and clamping element, forming of the recording medium of electrostatic adhesion toner on it, clamping element with toner image fusing and photographic fixing to recording medium;

Wherein, described clamping element compresses and the eyelid retractor that contacts in one of the upstream side that transmits recording medium and downstream, because an end of one of bridging part is crushed between eyelid retractor and the clamping element, then this bridging part tension, another not tensioning of bridging part, and contact with the bridging part outside surface of tension by clamping element, form the photographic fixing clamping-extruding region, and the photographic fixing clamping-extruding region extends to the upstream side precalculated position from the position that the photographic fixing band is crushed between eyelid retractor and the clamping element.

2. fixing device as claimed in claim 1, wherein clamping element is installed in the cross side of upstream side eyelid retractor, and to compress and to contact eyelid retractor, band is crushed between eyelid retractor and the clamping element.

3. fixing device as claimed in claim 1, wherein eyelid retractor lays respectively at the upstream side and the downstream of endless belt, and clamping element compresses one of the eyelid retractor in upstream side and downstream.

4. fixing device as claimed in claim 3, wherein, this clamping element compresses and contacts the upstream side eyelid retractor, and clamping element compresses and the cross side that contacts the downstream support component.

5. fixing device as claimed in claim 3, wherein, this clamping element compresses and contacts the downstream eyelid retractor, and clamping element compresses and the cross side that contacts the upstream side eyelid retractor.

6. fixing device as claimed in claim 3, the wherein inside surface and the rotating band of downstream eyelid retractor friction and contact zones, the upstream side eyelid retractor brings rotation by mobile.

7. fixing device as claimed in claim 1, wherein, described photographic fixing band is the lamination that forms the elastic layer of photographic fixing clamping-extruding region by compression at least and comprise the toner releasing layer of photographic fixing band outmost surface.

8. fixing device as claimed in claim 1, wherein the pressure on the photographic fixing clamping-extruding region increases along the recording medium direction of transfer.

9. fixing device comprises:

At least two eyelid retractors;

The endless belt, it is along the removable support of the supported device of principal direction, and is included in two bridging parts that extend between the eyelid retractor;

Compress the clamping element of endless belt, its with toner image fusing and photographic fixing to recording medium;

Wherein clamping element compresses and the eyelid retractor that contacts in one of the upstream side that transmits recording medium and downstream, because an end of one of bridging part is crushed between eyelid retractor and the clamping element, then this bridging part tension, another not tensioning of bridging part, and contact with the bridging part outside surface of tension by clamping element, form the photographic fixing clamping-extruding region.

10. fixing device as claimed in claim 9, wherein clamping element is installed in the cross side of upstream side eyelid retractor, and to compress and to contact eyelid retractor, band is crushed between eyelid retractor and the clamping element.

11. fixing device as claimed in claim 9, wherein said eyelid retractor are positioned at the upstream side and the downstream of endless belt, clamping element compresses one of the eyelid retractor in upstream side and downstream.

12. fixing device as claimed in claim 11, wherein, described clamping element compresses and contacts the upstream side eyelid retractor, and clamping element compresses and the cross side that contacts the downstream support component.

13. fixing device as claimed in claim 11, wherein, described clamping element compresses and contacts the downstream eyelid retractor, and clamping element compresses and the cross side that contacts the upstream side eyelid retractor.

14. fixing device as claimed in claim 11, the wherein inside surface and the rotating band of downstream eyelid retractor friction and contact zones, the upstream side eyelid retractor brings rotation by mobile.

15. fixing device as claimed in claim 9, wherein the photographic fixing band is the lamination that forms the elastic layer of photographic fixing clamping-extruding region by compression at least and comprise the toner releasing layer of photographic fixing band outmost surface.

16. fixing device as claimed in claim 9, wherein the pressure on the photographic fixing clamping-extruding region increases along the recording medium direction of transfer.

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