JP2006023607A - Fixing method, fixing device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose a fixing device capable of fixing toner most efficiently in terms of energy saving, and an image forming apparatus using the fixing device. <P>SOLUTION: The fixing device 11 is equipped with a fixing belt 12 laid round a heat roller H1 and the like, and a pressure belt 13 laid round rollers R4 to R5 and a pressure roller P1. A pressure fixing plate 14 for pressing the pressure belt 13 against the fixing belt 12 is provided inside the pressure belt 13. In a state where a recording medium P is held between a pair of belts 12 and 13, the recording medium P is heated for the time ≥3 msec and ≤150 msec in a nip between the heat roller H1 and the pressure roller P1 which are positioned at the leading end of a heating part, and the temperature of the recording medium P and the toner T thereon is raised to predetermined temperature. Thereafter, the recording medium P is held, kept, and conveyed in a tight-contact state between the belts 12 and 13 for the time ≥100 msec and ≤500 msec. Thus, the required phase change time of the toner T is maintained, and the toner T whose temperature is raised to the predetermined temperature causes phase change sufficiently enough to attain viscosity required for fixing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device used in an electrostatic recording image forming apparatus such as a copying machine, a facsimile machine, or a printer, and more particularly to a toner image fixing device using an electromagnetic induction heating method.

  In recent years, market demands for energy saving and high speed are increasing for image forming apparatuses such as copying machines. In order to achieve these required performances, it is important to improve the thermal efficiency of the fixing device used in the image forming apparatus.

  In an image forming apparatus such as a copying machine, an unfixed toner image is transferred to a sheet, printing paper, photosensitive paper, electrostatic recording by an image transfer method or a direct method by an image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording. It is formed on a recording medium such as paper. As a fixing device for fixing an unfixed toner image, a contact heating method fixing device such as a heat roller method, a film heating method, and an electromagnetic induction heating method is widely used.

  The heat roller type fixing device basically has a rotating roller pair of a fixing roller having a heat source such as a halogen lamp inside and adjusted to a predetermined temperature and a pressure roller pressed against the fixing roller. A recording material is introduced into a contact portion of the pair of rotating rollers, that is, a so-called fixing nip portion, and conveyed, and an unfixed toner image is melted and fixed on the recording material by heat and pressure from the fixing roller and the pressure roller.

  In addition, a film heating type fixing device, for example, as proposed in Patent Documents 1 and 2 and the like, causes a recording material to adhere to a heating body fixedly supported by a support member via a thin fixing film having heat resistance. The heat of the heating body is supplied to the recording material through the film material while sliding the fixing film relative to the heating body. In this fixing device, for example, a ceramic heater provided with a resistance layer on a ceramic substrate such as alumina or aluminum nitride having characteristics such as heat resistance, insulation, and good thermal conductivity is used as a heating body. In addition, since a thin film with a low heat capacity can be used as the fixing film, the heat transfer efficiency is higher than that of a heat roller type fixing device, the warm-up time can be shortened, and quick start and energy saving can be realized. .

  As an electromagnetic induction heating type fixing device, as disclosed in Patent Document 3, a device that generates Joule heat by an eddy current generated in a magnetic metal member by an alternating magnetic field and causes a heating body including the metal member to generate electromagnetic induction heat is proposed. Has been.

  The configuration of the electromagnetic induction heating type fixing device will be described below.

  FIG. 6 is a schematic view showing a conventional fixing device using an electromagnetic induction heating method. As shown in the figure, the conventional fixing device has a film inner surface guide 21 on which a heating body 20 including an exciting coil unit 18 and a magnetic metal member 19 as a heating unit is mounted, and the magnetic metal member 19 is in contact with the inner wall. In the state, the cylindrical film 17 having heat resistance that wraps the film inner surface guide 21 is pressed against the film 17 at the position of the magnetic metal member 19, and a fixing nip portion N is formed between the film 17 and the film 17. 17 is provided with a pressure roller 22 that rotates 17.

  The film 17 has a film thickness of 100 μm or less, preferably 50 μm or less, 20 μm or more, and a heat resistant single layer film such as PTFE, PFA, FEP or the like, or a film such as polyimide, polyamideimide, PEEK, PES, PPS, etc. A composite layer film in which PTFE, PFA, FEP or the like is coated on the outer peripheral surface of the is used.

  The film inner surface guide 21 is made of a member having rigidity and heat resistance formed of a resin such as PEEK or PPS, and the heating body 20 is fitted in a substantially central portion of the film inner surface guide 21 in the longitudinal direction. .

  The pressure roller 22 includes a core 22a and a heat-resistant rubber layer 22b having good releasability such as silicone rubber provided around the core 22a, and a predetermined pressing force is applied by a bearing and an urging means (both not shown). With the film 17 in between, the magnetic metal member 19 of the heating body 20 is disposed so as to be in pressure contact.

  The pressure roller 22 is driven to rotate counterclockwise by a driving means (not shown), and by the rotation of the pressure roller 22, a frictional force is generated between the pressure roller 22 and the film 17 so that the film 17 A rotational force acts on the film 17, and the film 17 slides and rotates while being in close contact with the magnetic metal member 19 of the heating body 20. Then, in a state where the heating body 20 reaches a predetermined temperature, an unfixed toner image T formed by an image forming unit (not shown) is formed between the film 17 of the fixing nip N and the pressure roller 22. The recording medium P is introduced. The recording medium P is sandwiched between the pressure roller 22 and the film 17 and conveyed through the fixing nip portion N, whereby the heat of the magnetic metal member 19 is applied to the recording medium P via the film 17 and an unfixed toner image. T is melt-fixed on the recording medium P. At the exit of the fixing nip N, the recording medium P that has passed is separated from the surface of the film 17 and conveyed to a paper discharge tray (not shown).

  Thus, in the electromagnetic induction heating type fixing device, the magnetic metal member 19 as the induction heating means is disposed close to the toner image T of the recording medium P via the film 17 by utilizing the generation of eddy current. The heating efficiency is further improved as compared with a film heating type fixing device.

However, these technologies are basically aimed only at high efficiency, and are not technologies that should achieve fundamental energy saving. As a result, the toner on the recording medium is heated and fixed within a predetermined nip time as in the conventional case, and it is desired to construct an essential energy saving principle.
JP-A-63-313182 Japanese Patent Laid-Open No. 1-263679 JP-A-8-22206 Japanese Patent Laid-Open No. 2001-13805

  In the roller fixing device using a halogen lamp and the film heat fixing of the above configuration, since the roller is used to press the recording medium against the fixing member, it is very difficult to take a large nip time. It is necessary to set the heating temperature higher than necessary in order to reliably fix the inside, and wasteful heat energy is consumed. In addition, the repulsive force of the rubber is different between the center and the end of the rubber pressure contact surface, the pressure contact of the end is weak with respect to the center, and when the diameter of the rubber roller to be pressed increases, the mass of the rubber roller increases, and at the nip point The heat required for fixing is greatly deprived, and the temperature of the heating body must be increased more than necessary. In addition, the difference in pressure applied between the center and end of the rubber roller cannot be solved in principle. Therefore, in order to shorten the time for which a sufficient pressing force is applied, the toner particles are deformed and the toner layer is fused and adheres to the surface of the recording medium, the toner temperature is increased more than necessary to lower the toner viscosity, This requires fixing performance.

  Such heating more than necessary is very wasteful from the viewpoint of energy saving, and of course is not preferable. Further, in order to raise the temperature of the toner in a short time, the temperature of the toner in contact with the fixing film surface and the temperature of the toner in contact with the recording medium surface are extremely different, and the temperature of the toner in contact with the recording medium surface However, the temperature of the toner in contact with the surface of the fixing film is extremely high, the viscosity is remarkably reduced, and an offset phenomenon is likely to occur.

  Moreover, when the heating temperature is high, the temperature of the heating body becomes high, the heat radiation amount increases, and heat dissipation to the surroundings of the apparatus is large, which is not preferable.

  In view of the above points, the inventor of the present application uses a method of causing a phase change to a state where the toner can be fixed by applying necessary heat energy to the toner when performing heat fixing. The idea was that there was a limit, and that it was possible to break the limit.

  That is, in the conventional nip system, even if the heat necessary for the phase change of the toner is transferred to the toner side after being nipped by the heating roller, the actual fixing performance is not so improved. On the other hand, in the laboratory level confirmation conducted by the inventor of the present application, the fixing performance actually improved markedly when heated to that temperature statically. As a result of earnest examination about this difference, the following matters became clear.

  First, when the fixing device is used dynamically, that is, in the case of a normal usage mode, the toner is heated to a necessary temperature. For example, when the recording medium is conveyed and the nip state is finished, The toner begins to cool. On the other hand, when tested in a static laboratory environment, the toner is kept at the required temperature for a sufficiently long time from a time point of view. This difference in conditions is considered to cause a large difference in fixing performance. That is, even when the fixing device is used dynamically, it can be seen that the toner fixing performance can be improved if there is a long-time heat retaining action as in the case where the fixing device is used under static conditions.

  The inventor of the present application has found that the difference in the fixing performance of the toner due to the difference in time is caused by a time delay with respect to the phase change of the toner resin. In general, there is always a time delay when a substance undergoes a phase change in response to a temperature change, and immediately after reaching a predetermined temperature, the assumed phase state does not immediately occur. It is. Therefore, in order to be in a predetermined phase state, it is necessary to maintain the predetermined temperature for a certain period of time. In normal roller fixing, the nip time is too short, so that the required phase change time cannot be maintained, and the phase change of the toner resin ends in an intermediate state in the transient phenomenon. This also ends the fixing operation.

  In other words, as a result, the fixing failure occurs because the toner is not in a predetermined phase at the time of fixing. In actual fixing, in order to increase the time constant of the phase change, the fixing is performed at a temperature much higher than the temperature required for the toner phase change. However, this is a wasteful energy consumption even though it is a temperature setting that is not normally necessary.

  In order to avoid this, it is conceivable to increase the nip time at the fixing roller and increase the time required for the phase change, but in order to increase the nip time, the diameter of the heating roller or pressure roller is very large. It must be made and is not realistic.

  As a result of studying these various points, the present invention has an object to propose a method and apparatus capable of fixing as efficiently as possible with respect to energy saving.

  The fixing method according to claim 1 of the present invention is a fixing method in which the supported toner is fixed to the recording medium by at least heating the recording medium carrying the toner, and the heating of the toner is performed. The time required for the resin contained in the toner to change to a predetermined phase necessary for the fixing is longer than a predetermined time.

  According to the second aspect of the present invention, in the fixing method of the first aspect, the recording medium is gradually cooled after the heating of the toner in the fixing method of the first aspect.

  A fixing method according to a third aspect of the present invention is the fixing method according to the first or second aspect, wherein the heating is performed by sandwiching a recording medium carrying toner between a pair of belts. The recording medium is heated for 3 ms or more and 150 ms or less at the leading end of the recording medium in the approach direction, and the recording medium is in close contact with the pair of belts for 100 ms or more and 500 ms or less after the elapse of the time. It is characterized by holding.

  The fixing device according to claim 4 of the present invention is a fixing device that fixes the carried toner to the recording medium by heating and pressurizing the recording medium carrying the toner, and heating the toner. It has a heating means for performing a time required for the resin contained in the toner to change to a predetermined phase required for the fixing to exceed a predetermined time.

  According to a fifth aspect of the present invention, there is provided a fixing device for fixing the carried toner to the recording medium by pressing the recording medium carrying the heated and transferred toner, and heating the toner. It has a heating means for performing a time required for the resin contained in the toner to change to a predetermined phase required for the fixing to exceed a predetermined time.

  According to a sixth aspect of the present invention, in the fixing device according to the fourth or fifth aspect, after the heating of the toner is completed, the recording apparatus further includes a conveying unit that conveys the recording medium while gradually cooling.

  According to a seventh aspect of the present invention, there is provided a fixing device for fixing the carried toner to the recording medium by sandwiching a recording medium carrying the toner between a pair of belts and heating and pressurizing the recording medium. And a heating portion that heats the recording medium in the leading direction of the recording medium for a time of 3 ms to 150 ms, and the pair of belts has a time of 100 ms to 500 ms after the elapse of time. The recording medium has a length capable of maintaining a close contact state.

  According to the eighth aspect of the present invention, there is provided a fixing device for fixing the carried toner onto the recording medium by pressing the recording medium carrying the heated and transferred toner between a pair of belts. And a pair of belts having a heating time of not less than 100 milliseconds and not more than 500 milliseconds after the passage of time. The recording medium has a length that allows the recording medium to be kept in an intimate contact state.

  According to the ninth aspect of the present invention, in the fixing device according to the seventh or eighth aspect, the heating portion is composed of a heating element and a belt that hangs around the heating element and is positioned on the surface side of the recording medium. It is characterized by.

  According to the tenth aspect of the present invention, in the fixing device according to the ninth aspect, the pressurizing portion is configured by pressing a pressure roller around a belt positioned on the back side of the recording medium against the heating element. It is characterized by.

  According to an eleventh aspect of the present invention, in the fixing device according to the tenth aspect, the pressure roller has a diameter of 5 to 100 mm.

  According to a twelfth aspect of the invention, in the fixing device of the tenth or eleventh aspect, the pressure roller is a rubber roller, and the thickness of the rubber layer is 0.5 to 30 mm.

  According to a thirteenth aspect of the present invention, in the fixing device according to any one of the seventh to twelfth aspects, a pressure plate that presses and contacts the pair of belts is provided inside at least one of the pair of belts. And

  According to a fourteenth aspect of the present invention, in the fixing device according to the thirteenth aspect, the pressure-fixing plate is a free-form surface having a perfect circle equivalent surface R of 100 to 100,000 mm.

  According to the fifteenth aspect of the present invention, in the fixing device according to any one of the seventh to fourteenth aspects, the heating temperature of the front end portion is increased, and the outlet temperature of the rear end portion in the recording medium entering direction between the pair of belts. And a temperature difference between the front end and the rear end outlet in the temperature distribution is set to 100 ° C. or less.

  According to a sixteenth aspect of the present invention, in the fixing device according to any one of the seventh to fifteenth aspects, the thickness of the fixing belt and the pressure belt is 1 to 400 μm.

  According to the seventeenth aspect of the present invention, in the fixing device according to any one of the seventh to sixteenth aspects, a temperature difference between the heating element and the surface of the fixing belt is set to 5 to 2000 ° C.

  According to Claim 18, in the fixing device according to any one of Claims 7 to 17, the material of the fixing belt and the pressure belt is a nitrogen-containing heat-resistant resin, and silicon and PFA are partly included in the resin. It is grafted and characterized in that these silicon and PFA are oriented on the surface.

  According to a nineteenth aspect of the present invention, in the fixing device according to the seventh aspect, the heating portion has a belt positioned on the surface side of the recording medium, means for transferring toner to the belt, and the transferred belt on the belt. And a means for directly heating the toner.

  According to Claim 20, in the fixing device according to Claim 8, any one of a halogen heater, induction heating means, and a planar heating element is used as a heating source in the heating portion.

  An image forming apparatus according to claim 21 uses the fixing device according to any one of claims 4 to 20.

  The present invention has good energy saving and can fix toner onto a recording medium very efficiently.

  The best mode for carrying out the present invention will be described below with reference to the embodiments shown in the drawings.

  FIG. 1 is a schematic diagram showing an example of the configuration of an image forming apparatus that is an object of the present invention. In this figure, reference numeral 1 denotes a drum-shaped photoconductive photoconductor as an image carrier. Around the photoconductor 1 is a charging device 2 for uniformly charging the surface of the photoconductor 1, and a charged photoconductor. 1, an optical writing device 3 that forms an electrostatic image by irradiating a writing light LB such as a laser beam, a developing device 4 that develops an electrostatic image on the photosensitive member 1 with toner, and visualizes it, on the photosensitive member 1 Transfer device 5 for transferring the toner image to a recording medium P such as recording paper, a cleaning device 6 for removing residual toner or paper dust or the like on the photoreceptor 1 after transfer, and static elimination for eliminating residual charges on the photoreceptor 1 A device 7 or the like is provided.

  Further, in this image forming apparatus, the recording medium P is transferred to the recording medium P, the paper feeding section 8 that feeds the recording medium P to the transfer section between the photoreceptor 1 and the transfer apparatus 5, the paper feeding roller 9, and the registration roller 10. A fixing device 11 is provided for heating and fixing the toner image. In addition, as the toner used in the developing device 4, a toner in which the main component of the binder is a resin is used.

  As shown in FIG. 2, the fixing device 11 includes a heat roller H1 containing a heating element, an endless fixing belt 12 wound around a guide roller R2 and a tension roller R3, guide rollers R4 and R6, a tension roller R5, The pressure belt 13 is also provided with an endless pressure belt 13 wound around the pressure roller P1. A pressure fixing plate 14 is provided inside the pressure belt 13 so that the pressure belt 13 can be pressed against the fixing belt 12. It is. It should be noted that various known heating elements may be employed for the heat roller H1, and energization, energization control, and the like may be in known forms, and illustration and description thereof are omitted. Further, the pressure fixing plate 14 may be provided inside the fixing belt 12.

  In this embodiment, the heating part is constituted by the heat roller H1 itself, the pressure roller P1 that raises the temperature by the heat generation, and the part around the heat roller H1 of the pair of belts 12 and 13. Then, the recording medium P is sandwiched between the pair of belts 12 and 13, and the recording medium P is heated at a nip between the heat roller H1 and the pressure roller P1 located at the leading end of the heating portion over a time interval of 3 milliseconds to 150 milliseconds. Then, the recording medium P and the toner T on the recording medium P are raised to a predetermined temperature, and thereafter, the recording medium P is held and conveyed while being in close contact between the belts 12 and 13 over a time interval of 100 milliseconds to 500 milliseconds. As a result, the necessary phase change time of the toner T can be maintained, and the toner T that has risen to a predetermined temperature sufficiently undergoes a phase change to the viscosity required for fixing. Unlike conventional systems that do not cause a sufficient phase change by causing them to cool immediately after reaching a predetermined temperature for a moment, unlike the conventional system, which requires fixing for a sufficient time after heating. The phase change of the toner T is caused to a sufficient viscosity, thereby enabling complete fixing.

  Further, slow cooling after heating is performed through belts 12 and 13 wound around rollers. That is, the surface of the fixing belt 12 as the surface of the fixing member and the toner T on the recording medium P remain in contact with each other after heating, and the contacted fixing belt 12 functions as a heat insulating material. Keep warm for more than a certain time above a certain temperature. Further, the pressure fixing plate 14 presses the pressure belt 13 on the back side of the recording medium P, thereby ensuring this close contact.

  The pressure fixing plate 14 is preferably a free-form curved surface whose surface shape is convex toward the recording medium P and whose surface is 100 to 100000 mm in terms of a perfect circle equivalent surface R. That is, if the surface R of the fixed pressure plate 14 is completely flat, it is difficult to stably adhere the surface of the fixing belt 12 and the surface on which the toner T of the recording medium P is placed by pressurization. This is because if the curved surface is bent too suddenly, a peripheral speed difference is generated between the surface of the fixing belt 12 and the surface of the recording medium P, which is not preferable. Therefore, the surface R of the fixed pressure plate 14 is more preferably 200 to 10000, further preferably 500 to 5000, and still more preferably 700 to 2000 mm.

  The pressure roller P1 used in the heating section is preferably not as thick as possible and has a small heat capacity. However, if a roller having a very small diameter is used, the roller vents and uniform pressure cannot be applied. Therefore, the pressure roller P1 can satisfy the necessary conditions in the present invention if the diameter is 5 to 100 mm, but is preferably 10 to 50 mm, more preferably 15 to 40 mm, and still more preferably 20 to 20 mm. 30 mm is recommended.

  Further, if the pressure roller P1 is a rubber roller and the thickness of the rubber layer is 0.5 to 30 mm, the nip width with the heat roller H1 can be easily obtained. In the present invention, the temperature of the toner T on the recording medium P is raised to a required heating temperature or higher only by heating at the tip of the heating portion, and thereafter, the necessary time is required solely due to the contact of the belts 12 and 13 and the heat insulating effect. It is necessary to keep the temperature higher than the temperature. Therefore, in the present invention, the heating temperature at the front end of the heating part is set to be slightly higher and is insulated by the belts 12 and 13 to cause a gradual temperature decrease. It is preferable that the outlet temperature has a temperature distribution lower than that of the tip portion, and the temperature difference is suppressed within 100 ° C. The smaller the temperature difference is, the better the zero desired characteristic. However, theoretically, only the tip is heated, and after that, it is not heated, and only the heat insulating properties of the belts 12 and 13 are used. However, this temperature difference is preferably as small as possible, and this temperature difference is more preferably within 80 ° C, even more preferably within 50 ° C, even more preferably within 30 ° C, and even more preferably within 20 ° C. desirable.

  The thickness of the fixing belt 12 and the pressure belt 13 is preferably thin considering that the toner T is heated in a short time at the tip of the heating portion. The thicker one is better considering the maintenance. In the present invention, if the thickness of the belts 12 and 13 is 1 to 400 μm, the desired requirements in the present invention can be satisfied, preferably 5 to 300 μm, more preferably 10 to 250 μm, and still more preferably 30. To 200 μm, even more preferably 50 to 150 μm, and even more preferably 70 to 100 μm.

  In addition, when heating is performed in the present invention, heat supply is not successful unless there is a difference in surface temperature between the heat roller H1 as a heat generating member and the fixing belt 12. If the temperature difference between the two is too large, the heat transfer is fast but the overshoot becomes intense. Conversely, if the temperature difference is too small, the followability to the temperature change becomes extremely poor. Therefore, in the present invention, the surface temperature difference between the heat roller H1 which is a heating element and the fixing belt 12 may be 5 to 2000 ° C, preferably 50 to 1800 ° C, more preferably 100 to 1500 ° C, and still more preferably. Is preferably 200 to 1000 ° C.

  In general, the lower the fixing temperature, the worse the release performance of the toner. In the case of the present invention, particularly after heating at the tip of the heating unit, the temperature is kept and the temperature is lowered, so that the conditions for mold release become stricter than usual. Therefore, it is preferable that the material of the belts 12 and 13 used in the present invention, particularly the fixing belt 12, is a nitrogen-containing heat-resistant resin. Further, it is preferable that silicon and PFA are grafted on a part of the resin, and that the silicon and PFA are oriented on the surface, because a better release performance can be obtained.

  In the present invention, it is also possible to directly heat the toner by radiant heat or the like, instead of performing heating at the tip of the heating portion via a heat roller or a fixing belt. FIG. 3 shows a second embodiment of the present invention having such a configuration. In this embodiment, the heating body H is used as a heating source, the fixing roller R1 and the fixing belt 12 that are heated by the heating body H, the pressure roller P1 that raises the temperature by heat transfer from them, and the area around the pressure roller P1 of the belt 13 Constitutes the heating part. It is not necessary to heat the transfer roller T1, the fixing roller R1, and the fixing belt 12 more than necessary with the heating member H, and the high-mass roller that is not necessary for the normal roller fixing or the like is not heated.

  Of course, in the present invention, any of a halogen heater, induction heating and a planar heating element can be used as in the conventional method. Therefore, in addition to the present invention, the energy saving property can be further improved by combining these methods for improving the thermal efficiency of the heater.

Various experimental examples will be described.
(Experimental example 1)
After pressing with the heat roller H1 and the pressure roller P1 as shown in FIG. 2, the fixing belt 12 and the recording medium PA were brought into close contact with the pressure fixing plate. At this time, the nip time between the heat roller H1 and the pressure roller P1 constituting the tip of the pressure part was 40 msec, and the contact time with the pressure fixing plate 14 was 200 msec. In this case, since the contact is made with the pressure fixing plate 14, the fixing temperature is lowered by 10 ° C. as compared with the case of normal roller fixing as shown in FIG. 4 (reference numerals are attached corresponding to FIG. 2). Became possible.
(Experimental example 2)
When the surface R of the pressure fixing plate 14 is 50 mm in the state of the above experimental example 1, a significant shift occurred on the image surface (experimental example 3).
When the surface R of the pressure fixing plate 14 was 200 mm in the state of Experimental Example 1, it was not visually recognized, but a displacement of about 18 μm was confirmed on the image surface by microscopic observation.
(Experimental example 4)
When the surface R of the pressure fixing plate 14 was 500 mm in the state of Experimental Example 1, there was also a deviation of about 4 μm.
(Experimental example 5)
When the surface R of the pressure fixing plate 14 was 700 mm in the state of Example 1, no image shift was observed.
(Experimental example 6)
When the surface R of the pressure fixing plate 14 was 1000 mm in the state of Example 1, no image shift was observed.
(Experimental example 7)
In the state of Example 1 above, when the surface R of the pressure fixing plate 14 is 1000000 mm, no image shift is observed, but floating occurs when the paper is passed, and image distortion due to pressure unevenness occurs. (Experimental example 8)
After pressing with the heat roller H1 and the pressure roller P1 as shown in FIG. 2, the fixing belt 12 and the recording medium P were brought into close contact with the pressure fixing plate. At this time, the nip time between the heat roller H1 and the pressure roller P1 constituting the tip of the pressure part was 100 msec, and the contact time with the pressure fixing plate 14 was 500 msec. Under these conditions, the fixing temperature could be lowered by 20 ° C. compared to the conventional fixing device shown in FIG.
(Experimental example 9)
As shown in FIG. 3, when the toner T transferred from the transfer roller T1 is heated by the radiant heating element H, the fixing temperature can be lowered by 20 ° C. as compared with the conventional radiant fixing device shown in FIG.

1 is a schematic diagram illustrating a configuration example of an image forming apparatus that is an object of the present invention. It is a conceptual diagram of 1st Example of this invention. It is a conceptual diagram of 2nd Example of this invention. FIG. 3 is a conceptual diagram of a conventional fixing device shown for comparison with the embodiment of FIG. 2. It is a conceptual diagram of the conventional radiation fixing device shown for the comparison with the Example of FIG. It is a schematic diagram which shows the fixing device by the conventional electromagnetic induction heating system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Photoconductor 2: Charging device 3: Optical writing device 4: Developing device P: Recording medium 5: Transfer device 6: Cleaning device 7: Static eliminating device 8: Paper feed unit 9: Paper feed roller 10: Registration roller 11: Fixing Device 12: Fixing belt 13: Pressure belt 14: Pressure fixing plate H1: Heat roller R2: Guide roller R3: Tension roller R4, R6: Guide roller R5: Tension roller P1: Pressure roller T: Toner H: Heating body

Claims (21)

A fixing method for fixing the supported toner to the recording medium by heating at least by sandwiching the recording medium carrying the toner, wherein the toner is heated by a predetermined resin required for the fixing. A fixing method comprising: performing a time required for changing to a phase exceeding a predetermined time. 2. The fixing method according to claim 1, wherein after the heating of the toner is finished, the recording medium is gradually cooled. 3. The fixing method according to claim 1 or 2, wherein the heating is performed by sandwiching a recording medium carrying toner between a pair of belts, and at least 3 milliseconds at the leading end of the recording medium in the direction of entry of the recording medium. The fixing method is characterized in that heating is performed for a time of 150 milliseconds or less and the recording medium is held in close contact with the pair of belts for a time of 100 milliseconds to 500 milliseconds after the passage of the time. A fixing device for fixing the carried toner to the recording medium by heating and pressurizing the recording medium carrying the toner, wherein the toner is heated by a predetermined resin required for the fixing. A fixing device comprising heating means for performing a time required for changing to the above phase to exceed a predetermined time. A fixing device for fixing the carried toner to the recording medium by pressing the recording medium carrying the heated and transferred toner, and the resin contained in the toner is used for the fixing. A fixing device comprising heating means for performing a time required for changing to a required predetermined phase beyond a predetermined time. 6. The fixing device according to claim 4, further comprising a conveying unit that conveys the recording medium while gradually cooling the toner after heating. A fixing device for fixing the carried toner to the recording medium by sandwiching a recording medium carrying toner between a pair of belts and heating and pressurizing the recording medium, the leading end of the recording medium entering between the pair of belts And a pair of belts that can hold the recording medium in a close contact state for a period of 100 milliseconds to 500 milliseconds after the elapse of time. A fixing device having a long length. A fixing device for fixing the carried toner onto the recording medium by pressing a recording medium carrying the heated and transferred toner between a pair of belts, wherein the recording medium is interposed between the pair of belts. In addition to having a heating part that heats for 3 ms or more and 150 ms or less at the tip in the approach direction, the pair of belts are in close contact with the recording medium for 100 ms to 500 ms after the elapse of the time A fixing device having a length capable of holding 9. The fixing device according to claim 7, wherein the heating portion is composed of a heating element and a belt that is wound around the heating element and positioned on the surface side of the recording medium. 10. The fixing device according to claim 9, wherein the pressing portion is configured by pressing a pressure roller, which is wound around a belt located on the back side of the recording medium, against the heating element. 10. The fixing device according to claim 10, wherein the pressure roller has a diameter of 5 to 100 mm. 12. The fixing device according to claim 10, wherein the pressure roller is a rubber roller, and the rubber layer has a thickness of 0.5 to 30 mm. 13. The fixing device according to claim 7, wherein a pressure plate that presses and contacts the pair of belts is provided inside at least one of the pair of belts. The fixing device according to claim 13, wherein the pressure-fixing plate is a free-form surface having a perfect circle equivalent surface R of 100 to 100,000 mm. 15. The fixing device according to claim 7, wherein a temperature distribution is set such that the heating temperature at the leading end is increased and the outlet temperature at the trailing end of the recording medium between the pair of belts is decreased. The fixing device is characterized in that a temperature difference between the front end portion and the rear end exit in the distribution is set to be within 100 ° C. 16. The fixing device according to claim 7, wherein the fixing belt and the pressure belt have a thickness of 1 to 400 [mu] m. 17. The fixing device according to claim 7, wherein a temperature difference between the heating element and the surface of the fixing belt is set to 5 to 2000 ° C. 17. 18. The fixing device according to claim 7, wherein a material of the fixing belt and the pressure belt is a nitrogen-containing heat-resistant resin, silicon and PFA are grafted on a part of the resin, and the silicon is formed on the surface. , PFA is oriented. 8. The fixing device according to claim 7, wherein the heating portion includes a belt positioned on a surface side of the recording medium, means for transferring toner to the belt, and means for directly heating the toner on the transferred belt. A fixing device characterized by comprising. 9. The fixing device according to claim 8, wherein any one of a halogen heater, induction heating means, and a planar heating element is used as a heating source in the heating portion. An image forming apparatus using the fixing device according to claim 4.