JP2006018316A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the reproducibility of linear velocity and the stability of the linear velocity in fixing. <P>SOLUTION: A fixing belt unit constituted of a fixing roller 506 having an elastic layer, a heating roller 510, an auxiliary roller 508 and a fixing belt 504 trained about them is turned with the rotary shaft of the auxiliary roller 508 as a support point, and pressured on a receiving roller 502 positionally fixed to form a fixing nip part N. The receiving roller 502 has hard structure which is more unlikely to be deformed than that of the fixing roller 506, and is driven to be rotated by a driving source, then the fixing roller 506 is submissively rotated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device that performs fixing by heat and pressure while conveying a recording material, a fixing method, and an image forming apparatus such as a copying machine, a printer, and a facsimile using the fixing device.

As this type of fixing device, there is known a heat roller fixing method in which a fixing nip portion is formed by pressing a pressure roller against a fixing roller having a heat source, and fixing is performed while conveying a recording material at the fixing nip portion. Yes.
In the heat roller fixing method, generally, only a pressure roller with which a non-image surface of a recording material abuts has an elastic layer on the surface for forming a fixing nip portion, and a fixing roller with which an image surface of the recording material abuts Has a hard structure that is hard to be deformed as compared with the pressure roller. Specifically, the fixing roller has a configuration in which a thin release layer is coated on the surface of a rigid metal core.
In the drive configuration, the fixing roller is driven to rotate by a drive source, and the pressure roller is driven to rotate.

In the heat roller fixing method, because of its configuration, it is inevitable that the melted toner is separated from the fixing roller before it is sufficiently cooled and solidified, so that a so-called offset phenomenon in which the toner adheres to the surface of the fixing roller is likely to occur. There's a problem.
Therefore, in recent years, a belt fixing method capable of sufficiently obtaining a toner cooling process has been attracting attention because of its configuration, and various proposals have been made.
In the belt fixing method, for example, as described in JP-A-9-90787, an endless fixing belt is supported and rotated between a heating roller having a heat source and a fixing roller having an elastic layer on the surface. A fixing nip portion is formed between the pressure roller and the fixing belt by pressing a pressure roller having a hard structure from the outside of the fixing belt on the fixing roller side.

The toner is melted by the heat of the fixing belt heated by the heating roller, and fixing is performed at the fixing nip portion located downstream of the heating roller in the conveyance direction of the recording material, and the toner is cooled.
The elastic layer of the fixing roller has a function as a heat insulating layer for preventing the heat of the fixing belt from being taken away more than necessary by the fixing roller, together with an elastic deformation function for forming the fixing nip portion widely. It is formed to be at least 2 mm thick.

Incidentally, as can be seen from the configuration described in Japanese Patent Application Laid-Open No. 9-90787, most of the belt fixing system uses a fixing roller having an elastic layer as a driving roller as a main body for conveying a recording material. Also, because the drive transmission from the image forming apparatus main body is easy to perform, the position of the fixing roller is often fixed in the belt fixing apparatus.
However, when a fixing roller having a thick elastic layer is used as a driving roller, the radius from the rotation center of the fixing roller to the fixing nip portion is between the start end and the end of the fixing nip portion due to deformation of the elastic layer. Therefore, the reproducibility of the linear velocity of the fixing roller is difficult, and the heat insulating and elastic layer wears and deteriorates over time, so that the linear velocity stability is also poor. In other words, the actual line speed cannot be grasped unless the paper is passed through the actual machine, and the specification cannot be determined at the design stage because the line speed cannot be predicted.
Further, when the fixing roller located inside the fixing belt is used as a driving roller, there is a concern that slip occurs between the fixing roller and the inner surface of the fixing belt. If slip occurs, the linear velocity stability is hindered.

In Japanese Patent Laid-Open No. 11-24486, a fixing nip portion is formed between a fixing belt and a pressure roller by pressing a hard pressure roller with a spring toward a fixing roller having an elastic layer and fixed in position. And the structure which uses a pressure roller as a drive roller is disclosed. That is, a roller outside the fixing belt is used as a pressure / drive roller.
According to this configuration, the fixing nip is formed by the deformation of the elastic layer of the fixing roller. However, since the main body for transporting the recording material is the pressure roller having a hard structure, the linear velocity stability is improved. The security is high, and even if a slip occurs between the fixing roller and the inner surface of the fixing belt, it is not affected.
Therefore, according to the configuration described in Japanese Patent Application Laid-Open No. 11-24486, the above problems in the configuration described in Japanese Patent Application Laid-Open No. 9-90787 can be solved.

JP-A-9-90787 Japanese Patent Laid-Open No. 11-24486

In the configuration described in Japanese Patent Application Laid-Open No. 11-24486, the pressure / drive roller is movable in the thickness direction of the recording material orthogonal to the recording material conveyance direction, and one of the rotation shafts of the pressure / drive roller is rotated. Since the rotational force of the drive source is input from the side, a difference in the applied pressure is generated in the axial direction of the pressure and drive roller by the drive torque.
For this reason, there are problems that wrinkles of the recording material, uneven glossiness, poor fixing, offset, and the like occur.

Further, as shown in FIG. 14, in the belt fixing method, usually, a recording material 700 carrying an image is guided by a guide plate 702 and the leading end thereof is brought into contact with the surface of the pressure roller 704 to guide the fixing nip. Part N is entered.
As in the configuration described in Japanese Patent Application Laid-Open No. 11-24486, in the configuration in which the pressure roller 704 having a hard structure is moved by an urging force such as a spring and pressed against the fixing roller 706, the fixing nip portion N is formed over time. In particular, there is a concern that the center C ₀ of the pressure roller 704 may be displaced to C ₁ due to wear of the elastic layer 708 of the fixing roller 706. In this case, the approach angle θ ₀ to the fixing nip portion N becomes θ ₁ . It becomes large and cannot easily enter the fixing nip portion N, and is likely to jam. In FIG. 14, reference numeral 710 denotes a fixing belt.

  The problem due to the change in the angle of approach to the fixing nip portion can also occur in the heat roller fixing method. When the configuration of the heat roller fixing system is considered corresponding to FIG. 14, generally, in monochrome image fixing, a pressure roller having an elastic layer is disposed below, and a fixing roller having a hard structure is disposed above. When the leading edge of the recording material is guided by the pressure roller to enter the fixing nip portion, the same problem may occur because the center of the pressure roller is displaced toward the fixing roller with time due to wear of the elastic layer. .

  Accordingly, the present invention provides a fixing device, a fixing method, and an image forming apparatus using the fixing device that can solve the above problems individually or at once, regardless of the heat roller fixing method or the belt fixing method. And its purpose.

  In order to achieve the above object, according to the first aspect of the present invention, a fixing roller is formed between the receiving roller fixed in position and an elastic layer that is pressed against the receiving roller. A fixing roller; a heat source for heating the recording material carrying the image; and a driving source for rotationally driving at least one of the fixing roller and the receiving roller, and an image is formed on one side of the recording material. In this case, the recording material is made to enter the fixing nip so that the image surface comes into contact with the fixing roller.

  According to a second aspect of the present invention, in the fixing device according to the first aspect, the receiving roller has a hard structure that is less likely to be deformed than the fixing roller, and the leading end of the recording material guides the surface of the receiving roller. In this case, a configuration is adopted in which the toner enters the fixing nip portion.

  According to a third aspect of the present invention, in the fixing device according to the second aspect, the hard structure of the receiving roller has a rigid cored bar and a highly releasable elastic layer coated on the surface of the cored bar. The composition is taken.

  According to a fourth aspect of the present invention, in the fixing device according to the second or third aspect, the receiving roller is rotationally driven by the driving source, and the fixing roller is driven to rotate.

  According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects of the present invention, the fixing device includes a pressing unit that urges the fixing roller toward the receiving roller. A configuration is adopted in which the pressurization is performed by an urging force.

  According to a sixth aspect of the present invention, there is provided the fixing device according to the fifth aspect, wherein the fixing device includes a stopper that restricts the pressure movement of the fixing roller toward the receiving roller by the pressure unit at a predetermined position. ing.

  According to the seventh aspect of the present invention, the receiving roller fixed in position, the fixing roller having an elastic layer, and the fixing roller wound around the fixing roller and pressed against the receiving roller together with the fixing roller are fixed between the receiving roller and the fixing roller. A fixing belt that forms a nip portion; a heat source that heats the fixing belt; and a driving source that rotationally drives the receiving roller. The receiving roller has a hard structure that is less likely to be deformed than the fixing roller. When an image is formed on one side of the recording material, the recording material is made to enter the fixing nip so that the image surface comes into contact with the fixing belt.

  According to the eighth aspect of the present invention, the receiving roller fixed in position, the fixing roller having a hard elastic layer having good thermal conductivity, and the receiving roller is wound around the fixing roller and pressurized together with the fixing roller. A fixing belt that forms a fixing nip portion with the roller; a heat source that heats the fixing belt; and a drive source that rotationally drives the receiving roller. The receiving roller is less likely to be deformed than the fixing roller. The fixing roller has a second heat source, and when the image is formed on one side of the recording material, the recording material is placed in the fixing nip so that the image surface comes into contact with the fixing belt. The structure is adopted to enter.

  According to a ninth aspect of the present invention, in the fixing device according to the seventh or eighth aspect, the rigid structure of the receiving roller has a rigid cored bar and a high release elastic layer coated on the surface of the cored bar. , Is adopted.

  According to a tenth aspect of the present invention, in the fixing device according to any one of the seventh to ninth aspects, the fixing belt is supported by a plurality of belt inward support rollers including the fixing roller, and A belt inner support roller and a fixing belt are unitized as a unit, and the rotation shaft of one belt inner support roller other than the fixing roller located upstream of the fixing nip portion in the recording material conveyance direction is used as a fulcrum. The unit is provided so as to be rotatable, and the unit is brought into contact with the pressure by the rotation of the unit.

  According to an eleventh aspect of the present invention, in the fixing device according to the tenth aspect, the other belt inner support roller located further upstream of the belt inner support roller serving as the rotation fulcrum in the recording material conveyance direction is the heat source. A belt inner support roller having the heat source, a linear portion of the fixing belt stretched over the belt inner support roller serving as the rotation fulcrum, and a tangent of the receiving roller at the entrance of the fixing nip portion The angle θ formed by the above is 15 ° to 70 °.

  According to a twelfth aspect of the present invention, in the fixing device according to the tenth or eleventh aspect of the present invention, the fixing device further includes a release material application unit that applies a release material to the fixing belt, and the release material application unit is integrated with the unit. , Is adopted.

  According to a thirteenth aspect of the present invention, in the fixing device according to any one of the seventh to eleventh aspects, the fixing device includes a pressing unit that urges the fixing belt and the fixing roller toward the receiving roller. The above-described pressurization is performed by the urging force of the pressure means.

  According to a fourteenth aspect of the present invention, in the fixing device according to the thirteenth aspect, the fixing device has a stopper for restricting the pressure belt to the receiving roller side of the fixing belt and the fixing roller by the pressing means at a predetermined position. The composition is taken.

  According to a fifteenth aspect of the present invention, the fixing device according to any one of the first to fourteenth aspects includes a pressure releasing unit capable of releasing the pressure.

  According to a sixteenth aspect of the present invention, in the fixing device according to one of the first to fifteenth aspects, a release material applying means for applying a release material to the receiving roller is provided so as to be able to contact with and separate from the receiving roller. When an image is formed only on one side of the recording material, the release material applying means is separated from the receiving roller.

  According to the seventeenth aspect of the present invention, a fixing roller having an elastic layer is pressed to a receiving roller having a hard structure that is not easily deformed to form a fixing nip portion. When the roller is driven to rotate and an image is formed on one side of the recording material, the recording material enters the fixing nip so that the image surface comes into contact with the fixing roller, and fixing is performed by heat and pressure. The procedure is taken.

  In the invention of claim 18, a fixing nip portion is formed by pressurizing a fixing roller having an elastic layer and a fixing belt wound around the fixing roller to a receiving roller fixed in position having a hard structure that is hard to deform, When the receiving roller is driven to rotate and the fixing roller is driven to rotate, when an image is formed on one side of the recording material, the recording material enters the fixing nip so that the image surface comes into contact with the fixing belt. The procedure is to fix by heat and pressure.

  According to a nineteenth aspect of the present invention, in the fixing method according to the eighteenth aspect, the fixing belt is supported by a plurality of belt inner support rollers including the fixing roller, and the belt inner support rollers and the fixing belt are supported. The unit is integrally formed, and the unit is rotatably provided with the rotation shaft of one belt inner support roller other than the fixing roller positioned upstream of the fixing nip portion in the conveyance direction of the recording material as a fulcrum, The procedure is such that the pressure is applied by rotating the unit.

  According to a twenty-second aspect of the present invention, in the image forming apparatus in which the recording material carrying the image is passed through the fixing device and fixed by heat and pressure, the fixing device has a receiving roller fixed in position and an elastic layer. A fixing roller that is pressed against the receiving roller to form a fixing nip portion with the receiving roller; a heat source for heating the recording material carrying the image; and at least one of the fixing roller and the receiving roller A drive source for rotating one of the recording materials, and when an image is formed on one side of the recording material, the recording material is caused to enter the fixing nip so that the image surface contacts the fixing roller. Is adopted.

  According to a twenty-first aspect of the present invention, in the image forming apparatus according to the twentieth aspect, the receiving roller has a hard structure that is less likely to be deformed than the fixing roller, and the leading end of the recording material is on the surface of the receiving roller. The structure is such that it is guided and enters the fixing nip portion.

  According to a twenty-second aspect of the present invention, in the configuration according to the twenty-first aspect, the rigid structure of the receiving roller includes a rigid cored bar and a highly releasable elastic layer coated on the surface of the cored bar. Is adopted.

  According to a twenty-third aspect, in the image forming apparatus according to the twenty-first or twenty-second aspect, the receiving roller is rotationally driven by the driving source, and the fixing roller is driven to rotate.

  According to a twenty-fourth aspect of the present invention, in the image forming apparatus according to any one of the twentieth to twenty-third aspects, the pressurizing unit has a pressing unit that urges the fixing roller toward the receiving roller. The above pressurization is performed by the urging force.

  According to a twenty-fifth aspect of the present invention, in the image forming apparatus according to the twenty-fourth aspect, the image forming apparatus further includes a stopper that restricts the pressing movement of the fixing roller toward the receiving roller by the pressing unit at a predetermined position. Adopted.

  According to a twenty-sixth aspect of the present invention, there is provided an image forming apparatus in which a recording material carrying an image is passed through a fixing device and fixed by heat and pressure. The fixing device includes a receiving roller fixed in position and a fixing roller having an elastic layer. A fixing belt that is wound around the fixing roller and is pressed against the receiving roller together with the fixing roller to form a fixing nip portion with the receiving roller, a heat source that heats the fixing belt, and the receiving roller The receiving roller has a hard structure that is harder to be deformed than the fixing roller, and when an image is formed on one side of the recording material, the image surface is in contact with the fixing belt. Thus, the recording material is made to enter the fixing nip portion.

  According to a twenty-seventh aspect of the present invention, in the image forming apparatus in which a recording material carrying an image is passed through a fixing device and fixed by heat and pressure, the fixing device has a receiving roller fixed in position and good thermal conductivity. A fixing roller having a hard elastic layer; a fixing belt that is wound around the fixing roller and is pressed against the receiving roller together with the fixing roller to form a fixing nip portion with the receiving roller; and the fixing belt is heated A heat source, and a drive source for rotationally driving the receiving roller. The receiving roller has a hard structure that is less likely to be deformed than the fixing roller. The fixing roller has a second heat source. When an image is formed on one side, the recording material is made to enter the fixing nip so that the image surface comes into contact with the fixing belt.

  According to a twenty-eighth aspect of the present invention, in the image forming apparatus according to the twenty-sixth or twenty-seventh aspect, the rigid structure of the receiving roller includes a rigid cored bar and a high release elastic layer coated on the surface of the cored bar. It has a configuration of having.

  According to a twenty-ninth aspect of the present invention, in the image forming apparatus according to any one of the twenty-sixth to twenty-eighth aspects, the fixing belt is supported by a plurality of belt inward support rollers including the fixing roller. The belt inner support roller and the fixing belt are integrated into a unit, and the rotation shaft of one belt inner support roller other than the fixing roller positioned upstream of the fixing nip portion in the recording material conveyance direction is used as a fulcrum. The unit is provided so as to be rotatable, and the unit is brought into contact with the pressure by the rotation of the unit.

  In the image forming apparatus according to a thirty-third aspect, in the image forming apparatus according to the twenty-ninth aspect, the other belt inner support roller located further upstream in the recording material conveyance direction than the belt inner support roller serving as the rotation fulcrum. A belt inner support roller having the heat source, a linear portion of the fixing belt stretched over the belt inner support roller serving as the rotation fulcrum, and the receiving roller at the entrance of the fixing nip portion. The angle θ formed with the tangent is 15 ° to 70 °.

  According to a thirty-first aspect of the present invention, in the image forming apparatus according to the thirty-ninth or thirty-third aspect, the image forming apparatus further comprises a release material application unit that applies a release material to the fixing belt, and the release material application unit is integrated with the unit. It has the structure of being.

  According to a thirty-second aspect of the invention, in the image forming apparatus according to any one of the twenty-sixth to thirty-third aspects, the image forming apparatus further includes a pressing unit that urges the fixing belt and the fixing roller toward the receiving roller. A configuration is adopted in which the above pressurization is performed by the urging force of the pressurizing means.

  According to a thirty-third aspect of the present invention, in the image forming apparatus according to the thirty-second aspect, the image forming apparatus further includes a stopper that restricts the pressing movement of the fixing belt and the fixing roller toward the receiving roller by the pressing unit at a predetermined position. The structure is adopted.

  According to a thirty-fourth aspect of the present invention, the image forming apparatus according to any one of the twentieth to thirty-fourth aspects includes a pressure releasing means capable of releasing the pressure.

  According to a thirty-fifth aspect of the present invention, in the image forming apparatus according to one of the twentieth to thirty-fourth aspects, a release material applying means for applying a release material to the receiving roller is provided so as to be able to contact and separate from the receiving roller. When the image is formed only on one side of the recording material, the release material applying means is separated from the receiving roller.

  According to the invention described in claim 1 or 20, when a fixing roller having an elastic layer is pressed on a receiving roller fixed in position to form a fixing nip portion, and an image is formed on one side of a recording material, the image is formed. Since the recording material is made to enter the fixing nip portion so that the surface comes into contact with the fixing roller, even in the case of a color image, good fixing can be performed without hindering glossiness or the like.

  According to the invention of claim 2 or 21, the receiving roller has a hard structure that is hard to be deformed as compared with the fixing roller, and the recording material is guided by the front surface of the receiving roller and enters the fixing nip portion. Therefore, the angle of entry of the recording material into the fixing nip portion can be made constant over time, and the occurrence of jam at the fixing nip portion can be suppressed.

  According to the invention described in claim 3 or 22, since the receiving roller has a hard structure in which the surface of the core metal having rigidity is covered with the high release elastic layer, high external accuracy can be obtained, and However, since the outer shape does not change, the reproducibility of the target linear velocity can be obtained in the conveyance of the recording material, and the linear velocity stability over time can be obtained.

  According to the invention described in claim 4 or 23, since the receiving roller is driven to rotate and the fixing roller is driven to rotate, the fixing nip portion is not affected by the driving torque, and is aimed at conveying the recording material. The reproducibility of the linear velocity can be obtained, and the linear velocity stability over time can be obtained.

  According to the invention described in claim 5 or 24, since the fixing roller is pressed against the roller by the urging force of the pressing means, it is possible to obtain pressure by a simple operation.

  According to the sixth or twenty-fifth aspect of the present invention, since the stopper for restricting the pressure movement of the fixing roller to the receiving roller side is provided at a predetermined position, the applied pressure can be adjusted easily and accurately. And an optimum fixing pressure can be obtained.

  According to the invention of claim 7 or 26, a fixing roller having an elastic layer and a fixing belt are pressed on a receiving roller having a hard structure fixed in position to form a fixing nip portion, and the receiving roller is used as a driving roller. When an image is formed on one side of the recording material, the recording material is made to enter the fixing nip so that the image surface is in contact with the fixing belt. Good fixing can be performed. In addition, the reproducibility of the target linear velocity can be obtained in the conveyance of the recording material, and the linear velocity stability with time can be obtained.

  According to the invention described in claim 8 or 27, since the fixing roller having the hard elastic layer having good thermal conductivity is pressed against the receiving roller, and the fixing roller has the second heat source, the heat generated by the fixing roller While avoiding loss, problems such as rattling during driving due to temporal deformation of the elastic layer of the fixing roller can be solved.

  According to invention of Claim 9 or 28, since the receiving roller was made into the hard structure which coat | covers a highly releasable elastic layer on the metal core surface which has rigidity, a high external precision can be obtained, and also over time Since the outer shape does not change, the reproducibility of the target linear velocity can be obtained in the conveyance of the recording material, and the linear velocity stability over time can be obtained.

  According to the invention described in claim 10 or 30, since the fixing belt unit is rotated and pressurized with the rotation shaft of one belt inner support roller other than the fixing roller as a fulcrum, In addition to the reproducibility of the target linear velocity in conveyance, the linear velocity stability over time can be obtained.

  According to the invention of claim 11 or 30, the belt inner support roller having the heat source, the linear portion of the fixing belt stretched over the belt inner support roller serving as a rotation fulcrum, and the receiving at the entrance of the fixing nip portion. Since the angle θ formed with the tangent line of the roller is 15 ° to 70 °, it is possible to suppress image rubbing and to reduce heat loss due to the presence of the belt inward support roller serving as a rotation fulcrum. .

  According to the twelfth or thirty-first aspect of the present invention, the fixing belt has the release material applying means for applying the release material, and the release material applying means is integrated with the fixing belt unit. The release property of the recording material can be improved, and the adjustment of the release material application means for the fixing belt accompanying the pressurizing operation can be made unnecessary.

  According to the thirteenth or thirty-second aspect of the present invention, the pressure can be obtained by a simple operation because the pressure is applied by the urging force of the pressure means.

  According to the fourteenth or thirty-third aspect of the present invention, since the stopper is provided for restricting the pressure belt and the fixing roller to the receiving roller side at a predetermined position, the pressing force is easily and accurately adjusted. And an optimum fixing pressure can be obtained.

  According to the fifteenth or thirty-fourth aspect of the present invention, since the pressure release means is provided, it is possible to prevent the fixing roller from being deformed with time when not in use, and to obtain good fixability over a long period of time. it can.

  According to the sixteenth or thirty-fifth aspect of the present invention, since the release material applying means for applying the release material to the receiving roller is provided, it is possible to prevent the recording material from being wound around the receiving roller and being separated.

  According to the seventeenth aspect of the present invention, the fixing roller having the elastic layer is pressed on the receiving roller having a hard structure that is not easily deformed to form the fixing nip portion, and the receiving roller is rotated and fixed. When the roller is driven to rotate and an image is formed on one side of the recording material, the recording material enters the fixing nip so that the image surface comes into contact with the fixing roller, and fixing is performed by heat and pressure. Therefore, the reproducibility of the target linear velocity can be obtained in the conveyance of the recording material, and the linear velocity stability with time can be obtained.

  According to the invention described in claim 18, the fixing nip portion is formed by pressurizing the fixing roller having the elastic layer and the fixing belt wound around the fixing roller to the position-fixed receiving roller having a hard structure which is not easily deformed. Then, the receiving roller is driven to rotate and the fixing roller is driven to rotate. When an image is formed on one side of the recording material, the recording material is placed in the fixing nip so that the image surface comes into contact with the fixing belt. Since the fixing is performed by heat and pressure by entering the recording medium, the reproducibility of the target linear velocity in conveying the recording material can be obtained, and the linear velocity stability with time can be obtained.

  According to the nineteenth aspect of the present invention, the pressure is applied by rotating the fixing belt unit around the rotation shaft of one belt inner support roller other than the fixing roller as a fulcrum. In addition to the reproducibility of the target linear velocity, the linear velocity stability over time can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, an overall configuration and function of a color copying machine as an image forming apparatus will be schematically described with reference to FIG.
A writing optical unit 400 serving as an exposure unit converts the color image data from the color scanner 200 into an optical signal, performs optical writing corresponding to the original image, and forms an electrostatic latent image on the photosensitive member 402 serving as an image carrier. Form. The writing optical unit 400 includes a laser diode 404, a polygon mirror 406, a rotation motor 408 thereof, an f / θ lens 410, a reflection mirror 412, and the like.
The photoconductor 402 is rotated in the counterclockwise direction as indicated by an arrow, and around the photoconductor cleaning unit 414, the charge eliminating lamp 416, the potential sensor 420, and the rotary developing device 422, there is selected development. A developing device (developing device 438 in FIG. 1), a developing density pattern detector 424, an intermediate transfer belt 426, and the like are arranged.

The rotary developing device 422 includes a black developing unit 428, a cyan developing unit 430, a magenta developing unit 432, a yellow developing unit 434, and a rotation driving unit (not shown) that rotates the corner developing unit. Each developer develops a developing sleeve that rotates by bringing the ears of the developer into contact with the surface of the photosensitive member 402 in order to visualize the electrostatic latent image, and a developing that rotates to pump up and stir the developer. Has paddles, etc.
In the standby state, the rotary developing device 422 is set at the black development position. When the copying operation is started, the color scanner 200 starts reading the black image data at a predetermined timing. Based on the above, optical writing with a laser beam and formation of an electrostatic latent image (black latent image) are started.

In order to develop from the leading edge of the black latent image, before the leading edge of the latent image reaches the developing position of the black developing device 428, the developing sleeve is started to rotate and the black latent image is developed with black toner.
Thereafter, the developing operation of the black latent image area is continued, but when the trailing edge of the latent image has passed the black developing position, it is quickly rotated from the developing position for black to the next color developing position. The developing device 422 rotates. This operation is completed at least before the leading edge of the latent image by the next image data arrives.
When the image forming cycle is started, first, the photosensitive member 402 is rotated counterclockwise as indicated by an arrow, and the intermediate transfer belt 426 is rotated clockwise by a drive motor (not shown). As the intermediate transfer belt 426 rotates, black toner image formation, cyan toner image formation, magenta toner image formation, and yellow toner image formation are performed. Finally, black (Bk), cyan (C), and magenta (M) are formed. And yellow (Y) in this order, the toner images are formed on the intermediate transfer belt 426.

The intermediate transfer belt 426 is stretched around a drive roller 444, transfer counter rollers 446a and 446b, a cleaning counter roller 448, and a driven roller group, and is driven and controlled by a drive motor (not shown).
The black, cyan, magenta, and yellow toner images sequentially formed on the photosensitive member 402 are accurately and sequentially aligned on the intermediate transfer belt 426, thereby forming a four-color superimposed belt transfer image. This belt transfer image is collectively transferred to a recording material (paper) by a transfer corona discharger 454.

Each of the recording paper cassettes 458, 460, and 462 in the paper supply bank 456 contains various sizes of paper different from the size of the paper stored in the cassette 464 in the apparatus body. The designated paper is fed and conveyed in the direction of the registration roller pair 470 by the paper feed roller 466 from the size paper storage cassette. In FIG. 1, reference numeral 468 denotes a manual paper feed tray for OHP paper, thick paper, and the like.
At the time when image formation is started, the paper is fed from the paper feed port of one of the above cassettes and waits at the nip portion of the registration roller pair 470. When the leading edge of the toner image on the intermediate transfer belt 426 reaches the corona discharger 454, the registration roller pair 470 is driven so that the leading edge of the sheet exactly coincides with the leading edge of the image, and registration of the sheet and the image is performed. Is called.

In this way, the sheet is overlapped with the intermediate transfer belt 426 and passes over the corona discharger 454 connected to a positive potential. At this time, the paper is charged with a positive charge by the corona discharge current, and the toner image is transferred to the paper. Subsequently, the sheet is neutralized when passing through a portion of a neutralizing brush (not shown) disposed on the left side of the corona discharger 454 in the drawing, and the sheet is peeled off from the intermediate transfer belt 426 and transferred to the sheet conveying belt 472.
The sheet onto which the four-color superimposed toner images have been collectively transferred from the intermediate transfer belt 426 is conveyed to the belt fixing type fixing device 500 by the paper conveying belt 472, and the toner image is fixed by the fixing device 500 by heat and pressure. The sheet that has been fixed is discharged out of the apparatus by the discharge roller pair 480 and stacked on a tray (not shown). Thereby, a full color copy is obtained.

Next, the belt fixing type fixing device 500 will be described in detail.
First, the concept of the fixing device 500 in the present embodiment will be described with reference to FIG. The fixing device 500 includes a receiving roller 502 as a driving roller fixed at a fixed position of a fixing device main body (not shown), a fixing belt 504, and a fixing roller 506 as a plurality of inward support rollers for supporting the fixing belt 504, An auxiliary roller 508, a heating roller 510, an oil application roller 512 for applying a release material to the fixing belt 504, a belt cleaning roller 514 for cleaning the surface of the fixing belt 504, a cleaning roller 516 for cleaning the oil application roller 512, and the like. Have.

The heating roller 510 includes a halogen heater 518 as a heat source for heating the fixing belt 504 inside, and feedback of the fixing temperature by a control unit (not shown) based on a detection value of the thermistor 520 that contacts the surface of the heating roller 510. Control is performed.
In order to speed up the start-up of the fixing device 500, a halogen heater 522 is also provided in the receiving roller 502. Based on the detected value of the thermistor 524 that contacts the surface of the receiving roller 502, the fixing temperature is controlled by a control means (not shown). Feedback control is performed.

The fixing belt 504 is formed by coating a silicon rubber layer having a thickness of about 200 μm on the surface of a base made of nickel electroforming or polyimide and having a thickness of 40 to 90 μm.
The fixing roller 506 as a driven roller has a metal core 506a made of metal such as aluminum or iron, and a thick elastic layer 506b made of a silicon foam coated on the surface of the metal core 506a. The receiving roller 502 has a hard structure that is less likely to be deformed than the fixing roller 506. In other words, as shown in FIG. 3, the surface of a rigid hollow steel cored bar 502a having a thickness of 1 mm is covered with a high release elastic layer 502b with a thickness of 200 μm or less (claims 9, 22, 28). In the present embodiment, the thickness of the high release elastic layer 502b is 70 μm, and high release silicon rubber is used as the material thereof.

  The fixing belt unit is configured by the fixing belt 504, the fixing roller 506, the auxiliary roller 508, the heating roller 510, and the like, and the oil unit is configured by the oil application roller 512, the belt cleaning roller 514, the cleaning roller 516, and the like. The fixing belt unit and the oil unit are mechanically coupled together. The rotational axis of the auxiliary roller 508 of the fixing belt unit is fixed in the same manner as the receiving roller 502, and as shown in FIG. 4, the fixing belt unit and the oil unit rotate integrally with the rotational axis of the auxiliary roller 508 as a fulcrum. Then, pressure is applied to form a fixing nip portion N shown in FIG. 2 (claims 10, 12, 19, 29, 31). Since the oil unit rotates integrally with the fixing belt unit, it is not necessary to separately adjust the oil application roller 512 with respect to the fixing belt 504 after pressurization, so that the assembling work is facilitated.

The fixing nip portion N includes a nip portion between rollers formed when the fixing roller 506 and the fixing belt 504 are pressed against the receiving roller 502, and an auxiliary located on the upstream side in the conveyance direction of the paper P with respect to the fixing roller 506. A nip portion is formed by the fixing belt 504 being wound around the receiving roller 502 by a roller 508 (one belt inner support roller other than the fixing roller 506). In the configuration without the auxiliary roller 508, the fixing nip portion N is only the inter-roller nip portion.
As shown in FIG. 2, the sheet P as a recording material carrying an image is guided by a guide plate 526 and guided by the surface of the receiving roller 502, and when the image surface is one side, the image surface becomes the fixing roller 506. It enters the fixing nip portion N so as to come into contact.
Therefore, even in the case of a color image on one side, it can be fixed without impairing glossiness or the like.

Next, a specific configuration such as pressurization in the fixing device 500 will be described with reference to FIGS.
The receiving roller 502 is supported via a support hole 530a between a pair of brackets 530 and 530 fixed to a device side plate (not shown) with screws 528. A driving gear 532 to which a driving force of a driving source (not shown) is input is fixed to one end of the receiving roller 502 (Claims 7, 17, 23, and 26). The bracket 530 is formed with a locking projection 530b for locking one end of a pressure spring 534 as a pressure means, and a support hole 530c for supporting the auxiliary roller 508. 13, 24, 32).

The fixing roller 506 is supported between a pair of brackets 536 and 536 through a support hole 536a. The bracket 536 is formed with a locking projection 536 b for locking the other end of the pressure spring 534 and a support hole 536 c for supporting the auxiliary roller 508.
The bracket 536 is formed with a support recess 536d for supporting the oil application roller 512 and a support recess 536e for supporting the heating roller 510.
The end portion of the auxiliary roller 508 is inserted in a state where the support hole 530c of the bracket 530 and the support hole 536c of the bracket 536 are overlapped, and the fixing belt unit with the rotating shaft of the auxiliary roller 508 as a fulcrum with respect to the bracket 530 fixed thereby. Is rotatable.
Collars 538 are provided at both ends of the heating roller 510, and the collars 538 are guided by both side surfaces of the support recess 536e, so that the heating roller 510 is displaced without shaking according to the tension of the fixing belt 504. It is like that. A spring locking projection 536f is formed on the bottom surface side of the support recess 536e, and a spring 540 for applying tension to the fixing belt 504 is provided between the spring locking projection 536f and the collar 538. .

  As shown in FIG. 5, the oil unit is based on a bracket 542, and a support hole 542 a of the belt cleaning roller 514, a support hole 542 b of the cleaning roller 516, and the like are formed in the bracket 542. The oil application roller 512 is supported by the bracket 542 and supported by the support recess 536d of the bracket 536 as described above. As a result, the fixing belt unit and the oil unit can be rotated together with the rotation shaft of the auxiliary roller 508 as a fulcrum. In FIG. 5, the oil unit is omitted.

A stopper 544 that restricts the pressing movement of the fixing roller 506 toward the receiving roller 502 by the pressing spring 534 at a predetermined position is provided in the vicinity of the locking projection 536 b that locks the pressing spring 534 of the bracket 536. (Claims 14, 25 and 33).
The stopper 544 includes a bracket 546 that is fixed to a device side plate (not shown), a screw shaft 548 that is screwed into a screw hole of the bracket 546 and whose tip abuts against the locking protrusion 536b, and a locking stopper that prevents the screw shaft 548 from loosening. A nut 550 is provided. By adjusting the screw shaft 548, the position of the fixing roller 506 relative to the receiving roller 502 can be adjusted regardless of the urging force of the pressure spring 534, and the pressure and fixing nip portion N can be changed without changing the pressure spring 534. Can be fine-tuned. The stopper 544 may not be provided.

Note that as a pressing means for pressing the fixing roller 506 against the receiving roller 502, the position of the shaft of the fixing roller 506 is adjusted by using elastic deformation of the elastic layer 506b, in addition to the method of providing the pressing spring 534. Then, a fixing method can also be adopted.
However, if the pressure spring 534 and the stopper 544 are provided, the applied pressure can be adjusted easily and accurately, and an optimum fixing pressure can be obtained.

As shown in FIG. 2, the paper P carrying the toner image is conveyed on the guide plate 526 toward the fixing nip N. During this conveyance, the toner begins to soften due to the radiant heat of the fixing belt 504 heated by the heating roller 510, and the leading edge of the sheet P is guided by the surface of the receiving roller 502 and enters the fixing nip portion N.
Since the receiving roller 502 is fixed in position, the approach angle of the paper P to the fixing nip N is constant, and there is no problem such as jam due to the change in the approach angle shown in FIG.
When the toner enters the fixing nip portion N, first, the toner is heated and melted and pressed in the nip portion formed by being wound around the receiving roller 502 by the auxiliary roller 508, and the fixing proceeds.
Next, fixing is finally completed at the original nip portion between the rollers, and cooling is performed without causing an offset. By this action, the release temperature range in the good fixing region is widened, and the fixing property is improved.

In addition, the receiving roller 502 is fixed in position and used as a driving roller, and the fixing roller 506 as a driven roller is pressed against the receiving roller 502 to form the fixing nip portion N. 502 is easily connected to the drive, and the fixing nip N is not affected by the drive torque, which is a problem in the configuration described in Japanese Patent Application Laid-Open No. 11-24486.
Therefore, the reproducibility of the target linear velocity in fixing conveyance can be obtained, the linear velocity stability over time is excellent, and the fixing property is not impaired.
In addition, since the fixing belt unit is configured to press the receiving roller 502 around the auxiliary roller 508 positioned upstream of the fixing roller 506 to form the fixing nip portion N, the nip shape variation due to the applied pressure, particularly the fixing nip, is determined. The change in the shape of the entrance portion of the portion N is small, and the occurrence of wrinkles on the paper P can be suppressed.

Further, in this embodiment, as shown in FIG. 2, a linear portion of the fixing belt 504 stretched over a heating roller 510 as a belt inner supporting roller having a heat source and an auxiliary roller 508 serving as a rotation fulcrum, and fixing. The angle θ formed with the tangent to the receiving roller 502 at the entrance of the belt 504 is set to 15 ° to 70 ° (claims 11 and 30).
By setting θ to 15 ° or more, even when the paper P is wrinkled, image rubbing due to the image surface touching the fixing belt 504 before entering the fixing nip portion N does not occur.
Further, by setting θ to 70 ° or less, heat transfer from the fixing belt 504 to the auxiliary roller 508 due to an increase in the contact area between the fixing belt 504 and the auxiliary roller 508 can be suppressed, and heat due to the presence of the auxiliary roller 508 can be suppressed. Loss can be reduced.

  Further, since the high release elastic layer on the surface of the receiving roller 502 is as thin as 200 μm or less, its outer shape accuracy is high, and the outer shape does not change over time. Therefore, the reproducibility of the target linear velocity and the linear velocity stability over time. Is excellent. Further, since the high-release elastic layer is provided, there is no problem such as occurrence of a difference in offset or glossiness in fixing a color image or in a double-sided image.

Next, another embodiment will be described based on FIG. Since the basic configuration is the same as that of the above embodiment, the overall configuration is omitted, and only different essential parts will be described.
The fixing roller 552 in the present embodiment includes a metal core 552a made of metal such as aluminum or iron, and an elastic layer 552b made of solid silicon rubber as a hard elastic layer having good thermal conductivity and coated on the surface of the core metal 552a. And a halogen heater 554 as a second heat source is provided therein (claims 8 and 27).
The fixing roller 506 in the above embodiment has a thick elastic layer 506b made of a silicon foam material. Due to the low thermal conductivity of the elastic layer 506b, the fixing roller 506 heats more than necessary by the fixing roller 506. It is intended to avoid poor fixing due to being robbed. However, according to this configuration, when the elastic layer 506b is deteriorated with time due to its material characteristics, there is a concern that the driving may be unstable and a fixing defect may be caused.

  The present embodiment is intended to solve this concern, and the above-described concern about deterioration over time is eliminated by the hardness of the solid silicon rubber, and heat absorption by the fixing roller 552 due to good thermal conductivity is achieved. The problem is solved by the temperature equilibrium due to the heating of the halogen heater 554. Accordingly, the temperature of the halogen heater 554 is controlled by a control means (not shown) so that a cooling process that does not cause an offset phenomenon, which is an advantage of the belt fixing method, can be obtained without taking heat more than necessary by the fixing roller 552. Be controlled.

Next, another embodiment will be described based on FIGS. 9 and 10. Since the basic configuration is the same as that of the first embodiment, the entire configuration is omitted, and only different main parts will be described.
The present embodiment is characterized by having a solenoid 556 as pressure release means for releasing the pressure applied to the receiving roller 502 of the fixing roller 506 by the pressure spring 534 (claims 15 and 34).
If the pressurized state is always maintained even when the image forming apparatus is stopped, the elastic layer 506b of the fixing roller 506 is permanently deformed depending on the degree of the stop time (non-use time), which may cause fixing failure. There are concerns.
The present embodiment aims to eliminate this concern, and releases the pressure when the fixing device 500 or the image forming apparatus is not used.

A locking projection 536b that locks one end of the pressure spring 534 of the bracket 536 is elongated, and the movable rod 556a of the solenoid 556 is in contact with the extended portion.
The solenoid 556 is electrically connected to the main switch 558 of the fixing device 500 or the image forming apparatus via a control unit (not shown). When the main switch 558 is turned on, as shown in FIG. evacuate. In this case, the retracted position of the movable rod 556a is set so as not to affect the function of the stopper 544.

When the main switch 558 is turned off at the end of the copying operation or the like, the movable rod 556a protrudes, and the fixing roller 506 is separated from the roller 502 against the urging force of the pressure spring 534 as shown in FIG. The release of pressure in this case does not necessarily mean that the fixing roller 506 is completely separated from the receiving roller 502, but is intended to release the elastic layer 506b of the fixing roller 506 to such an extent that no permanent distortion occurs.
The solenoid 556 may be used in such a manner that when the main switch 558 is turned off, the movable rod 556a is retracted to release the pressurization.

This pressure release may be performed by manually operating an eccentric roller or the like by an operator. However, if the configuration is interlocked with the main switch 558 as described above, not only the release operation becomes unnecessary, The operator never forgets the release operation.
In addition to the solenoid 556, various devices such as a cam-driven device, an air cylinder, and a hydraulic cylinder can be used as the pressure release means.

Next, another embodiment will be described based on FIG. Since the basic configuration is the same as that of the first embodiment, the entire configuration is omitted, and only different main parts will be described.
The present embodiment is characterized by having an oil application roller 560 as a release material application means for applying a release material to the receiving roller 502 (Claim 35).
Since the fixing nip portion N has a wide width including the winding by the auxiliary roller 508, the curling action on the paper P by the curved surface of the receiving roller 502 is large. Especially in the case of double-sided image formation, the paper is fixed after fixing. There is a concern that P is not separated from the receiving roller 502 and causes a discharge failure.
The present embodiment aims to eliminate this concern and improves the releasability of the receiving roller 502.

  The oil application roller 560 is provided so as to be able to contact and separate from the receiving roller 502 by a contact / separation mechanism (not shown). The contact / separation mechanism is controlled by a control unit (not shown), and in the case of double-sided image formation, the oil application roller 560 contacts the receiving roller 502 to apply the release material. When image formation is on one side, the oil application roller 560 is separated from the receiving roller 502.

Next, another embodiment will be described based on FIG.
The fixing device 562 in the present embodiment is a heat roller fixing method, and a fixing roller that forms a fixing nip portion between the receiving roller 564 that is fixed in position and the receiving roller 564 that is pressed against the receiving roller 564. 566, a halogen heater 568 as a heat source for heating the sheet P as a recording material provided inside the fixing roller 566 and carrying an image, and a motor 570 as a drive source for driving the receiving roller 564. (Claims 1 and 4).

Similar to the first embodiment, the fixing roller 566 as a driven roller includes a metal core 566a made of metal such as aluminum or iron, and a thick elastic layer made of a silicon foam material coated on the surface of the core 566a. 566b.
The receiving roller 564 has a hard structure that is less likely to be deformed than the fixing roller 566. That is, as shown in FIG. 3, a highly release elastic layer is coated on the surface of a rigid hollow steel cored bar 564 a having a thickness of 1 mm with a thickness of 200 μm or less. In the present embodiment, the thickness of the high release elastic layer is 70 μm, and high release silicone rubber is used as the material thereof (Claim 3).
The pressurizing configuration of the fixing roller 566 against the receiving roller 564, the driving configuration of the receiving roller 564, and the like can be the same as in the first embodiment. The same applies to the configuration in which the stopper 544 and the like are provided (claims 5, 6, 16, 18).

When the sheet P is guided by the guide plate 572 and guided by the surface of the receiving roller 564 and the image surface is one side, the sheet P enters the fixing nip portion N so that the image surface contacts the fixing roller 566. 20).
For this reason, even in the case of a color image on one side, it can be fixed without impairing glossiness or the like.
Also in this embodiment, since the receiving roller 564 that guides the paper P to the fixing nip portion N is fixed in position, problems such as jamming due to the change in the approach angle shown in FIG. 14 do not occur. Further, the fixing nip N is not affected by the driving torque, which is a problem in the configuration described in Japanese Patent Application Laid-Open No. 11-24486.
For this reason, the reproducibility of the target linear velocity in fixing conveyance and the linear velocity stability over time are excellent, and the fixing property is not impaired.
The fixing device 562 in this embodiment can also be installed in an image forming apparatus such as a color copying machine, like the belt fixing type fixing device 500 in the first embodiment.

In the embodiment of the belt fixing method, the receiving roller 502 is rotationally driven by a driving source and the fixing roller 506 is driven to rotate by friction. However, as shown in FIG. A drive system that provides both a receiving gear 502 and a fixing roller 506 by engaging a transmission gear 537 that transmits a rotational force of a motor 535 serving as a driving source to the driving gear 532 is provided. Good.
However, in both of these drive systems, it is necessary to make the roller diameters of the fixing roller 506 and the receiving roller 502 substantially the same. In this case, the transmission gear 537 may be engaged with the gear 533 of the fixing roller 506. Both the drive systems can be similarly implemented in the heat roller fixing system shown in FIG. 12 (claims 1 and 20).

1 is a schematic front view of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a schematic diagram focusing on the position of each roller of the fixing device. It is a schematic sectional drawing of a receiving roller. FIG. 5 is a schematic diagram illustrating an operation of rotating and fixing a fixing belt unit to a receiving roller. FIG. 2 is a specific configuration diagram of a fixing device. FIG. 3 is an exploded perspective view of a main part of the fixing device. FIG. 4 is a perspective view illustrating a relationship between each roller of the fixing device and a fixing belt. It is principal part sectional drawing in other embodiment. It is principal part sectional drawing which shows the non-release state of a pressurization cancellation | release means. It is principal part sectional drawing which shows the cancellation | release state of a pressurization cancellation | release means. It is principal part sectional drawing in other embodiment. It is principal part sectional drawing in embodiment of a heat roller fixing system. It is a principal part perspective view which shows other embodiment of a roller drive structure. FIG. 10 is a cross-sectional view of a main part showing a change in an approach angle to a fixing nip portion in the past.

Explanation of symbols

502, 564 Receiving roller 502a Core metal 502b Silicon rubber layer as a high-release elastic layer 504 Fixing belt 506b, 566b Elastic layer 506, 566 Fixing roller 508 Auxiliary roller 518, 568 Heating the recording material Halogen heater as heat source 534 Pressure spring as pressure means 544 Stopper 552b Solid silicon rubber layer as hard elastic layer 556 Solenoid as pressure release means 560 Oil application roller as release material application means N Fixing nip P Paper as recording material

Claims (35)

  A receiving roller fixed in position, a fixing roller having an elastic layer and being pressed against the receiving roller to form a fixing nip portion between the receiving roller, and a heat source for heating the recording material carrying the image And a driving source that rotationally drives at least one of the fixing roller and the receiving roller, and when an image is formed on one surface of the recording material, the image surface is in contact with the fixing roller. A fixing device characterized by causing the recording material to enter a fixing nip portion. The fixing device according to claim 1.
A fixing device, wherein the receiving roller has a hard structure that is less likely to be deformed than the fixing roller, and the recording material is guided at the front end of the receiving roller and enters the fixing nip portion. The fixing device according to claim 2.
A fixing device in which the hard structure of the receiving roller has a rigid cored bar and a high release elastic layer coated on the surface of the cored bar. The fixing device according to claim 2 or 3,
The fixing device, wherein the receiving roller is rotationally driven by the driving source, and the fixing roller is driven to rotate. The fixing device according to any one of claims 1 to 4, wherein:
A fixing device comprising pressure means for urging the fixing roller toward the receiving roller, wherein the pressure is applied by the urging force of the pressure means. The fixing device according to claim 5.
A fixing device, comprising: a stopper for restricting the pressing movement of the fixing roller toward the receiving roller by the pressing means at a predetermined position.   A receiving roller fixed in position, a fixing roller having an elastic layer, a fixing belt wound around the fixing roller and pressed against the receiving roller together with the fixing roller to form a fixing nip portion with the receiving roller And a heat source for heating the fixing belt and a driving source for rotating the receiving roller. The receiving roller has a hard structure that is less likely to be deformed than the fixing roller, and forms an image on one side of the recording material. And a fixing device for causing the recording material to enter the fixing nip so that the image surface contacts the fixing belt.   A fixing nip portion between the receiving roller fixed in position, a fixing roller having a hard elastic layer having good heat conductivity, and being wound around the fixing roller and pressed against the receiving roller together with the fixing roller. And a heat source for heating the fixing belt, and a driving source for rotationally driving the receiving roller. The receiving roller has a hard structure that is less likely to be deformed than the fixing roller. The roller has a second heat source, and when the image is formed on one side of the recording material, the recording material enters the fixing nip so that the image surface comes into contact with the fixing belt. Fixing device. The fixing device according to claim 7 or 8,
A fixing device in which the hard structure of the receiving roller has a rigid cored bar and a high release elastic layer coated on the surface of the cored bar. The fixing device according to any one of claims 7 to 9,
The fixing belt is supported by a plurality of belt inner support rollers including the fixing roller, and these belt inner support rollers and the fixing belt are integrated as a unit, and the recording material is conveyed more than the fixing nip portion. The unit is rotatably provided with the rotation shaft of one belt inner support roller other than the fixing roller located upstream in the direction as a fulcrum, and the unit is in contact with the pressure by the rotation of the unit. A fixing device characterized by being made. The fixing device according to claim 10.
Another belt inner support roller located further upstream of the recording medium conveyance direction of the belt inner support roller serving as the rotation fulcrum has the heat source, and the belt inner support roller having the heat source and the rotation An angle θ formed by a straight line portion of the fixing belt stretched over a belt inner support roller serving as a fulcrum and a tangent line of the receiving roller at the entrance of the fixing nip portion is 15 ° to 70 °. A fixing device. The fixing device according to claim 10 or 11,
A fixing device comprising release material application means for applying a release material to the fixing belt, wherein the release material application means is integrated with the unit. The fixing device according to any one of claims 7 to 11, wherein:
A fixing device comprising pressure means for urging the fixing belt and the fixing roller toward the receiving roller, wherein the pressure is applied by the urging force of the pressure means. The fixing device according to claim 13.
A fixing device comprising: a stopper for restricting the pressing movement of the fixing belt and the fixing roller toward the receiving roller by the pressing means at a predetermined position. The fixing device according to any one of claims 1 to 14,
A fixing device comprising pressure release means capable of releasing the pressure. The fixing device according to any one of claims 1 to 15, wherein:
A release material applying means for applying a release material to the receiving roller is provided so as to be able to come into contact with and separate from the receiving roller. When an image is formed only on one side of the recording material, the release material applying means is separated from the receiving roller. A fixing device.   A fixing roller having an elastic layer is pressed on a receiving roller having a hard structure that is not easily deformed to form a fixing nip portion. The receiving roller is driven to rotate and the fixing roller is driven to rotate. A fixing method in which, when an image is formed on one side of the recording medium, the recording material enters the fixing nip portion so that the image surface comes into contact with the fixing roller, and fixing is performed by heat and pressure.   A fixing roller having an elastic layer and a fixing belt wound around the fixing roller are pressed against a receiving roller having a hard structure that is hard to be deformed to form a fixing nip portion, and the receiving roller is driven to rotate. When the fixing roller is driven to rotate and an image is formed on one side of the recording material, the recording material enters the fixing nip so that the image surface comes into contact with the fixing belt and is fixed by heat and pressure. A fixing method characterized in that it is performed. The fixing method according to claim 18.
The fixing belt is supported by a plurality of belt inner support rollers including the fixing roller, and the belt inner support roller and the fixing belt are integrated into a unit, and the recording material is conveyed in the direction of the fixing nip portion. The unit is rotatably provided with a rotation shaft of one belt inner support roller other than the fixing roller positioned upstream as a fulcrum, and the unit is rotated to perform the pressurization. Fixing method. In an image forming apparatus in which a recording material carrying an image is passed through a fixing device and fixed by heat and pressure.
The fixing device includes: a receiving roller whose position is fixed; a fixing roller that has an elastic layer and is pressed against the receiving roller to form a fixing nip portion; and a recording material carrying an image. A heat source for heating, and a drive source for rotationally driving at least one of the fixing roller and the receiving roller. When an image is formed on one surface of the recording material, the image surface is the fixing roller. An image forming apparatus, wherein the recording material is caused to enter the fixing nip portion so as to come into contact. The image forming apparatus according to claim 20, wherein
An image forming apparatus characterized in that the receiving roller has a hard structure that is less likely to be deformed than the fixing roller, and the recording material is guided by the front surface of the receiving roller and enters the fixing nip portion. . The image forming apparatus according to claim 21, wherein
An image forming apparatus, wherein the rigid structure of the receiving roller has a rigid cored bar and a high release elastic layer coated on the surface of the cored bar. The image forming apparatus according to claim 21 or 22,
An image forming apparatus, wherein the receiving roller is rotationally driven by the driving source, and the fixing roller is driven to rotate. 24. The image forming apparatus according to claim 20, wherein:
An image forming apparatus comprising pressure means for urging the fixing roller toward the receiving roller, wherein the pressure is applied by the urging force of the pressure means. 25. The image forming apparatus according to claim 24.
An image forming apparatus, comprising: a stopper for restricting the pressing movement of the fixing roller toward the receiving roller by the pressing unit at a predetermined position. In an image forming apparatus in which a recording material carrying an image is passed through a fixing device and fixed by heat and pressure.
The fixing device includes a receiving roller fixed in position, a fixing roller having an elastic layer, and a fixing nip portion that is wound around the fixing roller and is pressed against the receiving roller together with the fixing roller. A fixing belt to be formed; a heat source that heats the fixing belt; and a driving source that rotationally drives the receiving roller. The receiving roller has a hard structure that is less likely to be deformed than the fixing roller. An image forming apparatus, wherein, when an image is formed on one side, the recording material is caused to enter the fixing nip so that the image surface comes into contact with the fixing belt. In an image forming apparatus in which a recording material carrying an image is passed through a fixing device and fixed by heat and pressure.
The fixing device includes a receiving roller whose position is fixed, a fixing roller having a hard elastic layer having good thermal conductivity, and a winding roller wound around the fixing roller and pressed against the receiving roller together with the fixing roller. A fixing belt that forms a fixing nip portion therebetween, a heat source that heats the fixing belt, and a driving source that rotationally drives the receiving roller, and the receiving roller has a hard structure that is less likely to deform than the fixing roller. And the fixing roller has a second heat source, and when an image is formed on one side of the recording material, the recording material enters the fixing nip so that the image surface comes into contact with the fixing belt. An image forming apparatus. The image forming apparatus according to claim 26 or 27.
An image forming apparatus, wherein the rigid structure of the receiving roller has a rigid cored bar and a high release elastic layer coated on the surface of the cored bar. 29. The image forming apparatus according to claim 26, wherein:
The fixing belt is supported by a plurality of belt inner support rollers including the fixing roller, and these belt inner support rollers and the fixing belt are integrated as a unit, and the recording material is conveyed more than the fixing nip portion. The unit is rotatably provided with the rotation shaft of one belt inner support roller other than the fixing roller located upstream in the direction as a fulcrum, and the unit is in contact with the pressure by the rotation of the unit. An image forming apparatus characterized by being made. 30. The image forming apparatus according to claim 29.
Another belt inner support roller located further upstream of the recording medium conveyance direction of the belt inner support roller serving as the rotation fulcrum has the heat source, and the belt inner support roller having the heat source and the rotation An angle θ formed by a straight line portion of the fixing belt stretched over a belt inner support roller serving as a fulcrum and a tangent line of the receiving roller at the entrance of the fixing nip portion is 15 ° to 70 °. An image forming apparatus. The image forming apparatus according to claim 29 or 30,
An image forming apparatus comprising: a release material applying means for applying a release material to the fixing belt, wherein the release material applying means is integrated with the unit. 31. The image forming apparatus according to claim 26, wherein:
An image forming apparatus comprising pressure means for urging the fixing belt and the fixing roller toward the receiving roller, wherein the pressure is applied by the urging force of the pressure means. The image forming apparatus according to claim 32.
An image forming apparatus comprising: a stopper for restricting the pressing movement of the fixing belt and the fixing roller toward the receiving roller by the pressing unit at a predetermined position. 35. The image forming apparatus according to claim 20, wherein:
An image forming apparatus comprising pressure release means capable of releasing the pressure. 35. The image forming apparatus according to claim 20, wherein:
A release material applying means for applying a release material to the receiving roller is provided so as to be able to contact and separate from the receiving roller, and when forming an image only on one side of the recording material, the release material applying means is separated from the receiving roller. An image forming apparatus.

Images