JP2001209266A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the start up time in a fixing device of a belt fixing system. SOLUTION: In this fixing device, a fixing belt 508 is stretched between a fixing roller 502 and a heating roller 506, and a nip part N is formed by a pressing roller 510 being held in press contact with the fixing roller 502 through the fixing roller 508. The device is provided with a cleaning roller 518 for cleaning the fixing belt 508 on a position for the fixing roller 502 roughly to face the pressure roller 510, and a halogen heater 520 inside as a heat source for starting. At the time of starting, the halogen heater 504 as the heat source for fixing in the heating roller 506 and the halogen heater 520 are simultaneously energized and the image forming device is started instantly by the maximum output permissible as the image forming device. At the time of printing, the low power fixation is performed by energizing only the halogen heater 504 provided with the output for fixing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device which is used in an image forming apparatus such as a copying machine, a printer, a facsimile, etc. and performs fixing by heat and pressure while conveying a recording material. It relates to a fixing device.

[0002]

2. Description of the Related Art Conventionally, as a fixing device used in an image forming apparatus, a fixing nip portion is formed by pressing a pressing roller against a fixing roller having a heat source, and a recording material is nipped by the fixing nip portion. 2. Description of the Related Art A heat roller fixing method in which fixing is performed by heat and pressure while being conveyed is known. In the heat roller fixing method, it is unavoidable that the melted toner is separated from the fixing roller before the toner is sufficiently cooled and solidified, so that the so-called offset phenomenon in which the toner adheres to the surface of the fixing roller easily occurs. There's a problem. Therefore, in recent years, attention has been paid to a belt fixing system capable of sufficiently obtaining a toner cooling step due to its configuration, and various proposals have been made.

In the belt fixing method, for example, Japanese Patent Application Laid-Open
As described in Japanese Patent No. 18001, an endless fixing belt is rotated between a heating roller having a heat source such as a halogen heater and a fixing roller, and is driven to rotate. Then, a pressure roller is pressed to form a fixing nip portion between the pressure roller and the fixing belt. The toner is melted by the holding heat of the fixing belt heated by the heating roller, and is fixed in a fixing nip portion located downstream of the heating roller in the conveying direction of the recording material, and the toner is cooled. .

Japanese Patent Application Laid-Open No. 9-138600 describes a configuration in which a heating roller is pressed against the outer peripheral surface of a fixing belt toward the inside thereof to heat the fixing belt. Japanese Patent Application Laid-Open No. Hei 9-138597 discloses that a heat source for heating the inner peripheral surface of the fixing belt and a heat source for heating the outer peripheral surface of the fixing belt are separately provided. A configuration for obtaining a fixing temperature during printing is described.

[0005]

Problems to be Solved by the Invention
In the configuration described in Japanese Patent Application Laid-Open Publication No. H11-146, since the fixing roller only has a heat source inside the heating roller, when the fixing belt rotates after startup, a part of the heat of the heated fixing belt contacts the fixing roller. And the inside of the pressure roller escapes, and the temperature of the fixing belt drops significantly. Therefore, it takes time to recover to the predetermined fixing temperature,
In the end, from a quick start point of view, we couldn't get a satisfactory start-up time.

In the configuration described in Japanese Patent Application Laid-Open No. Hei 9-138600, since the outer peripheral surface of the fixing belt is heated, the amount of heat stored in the entire fixing belt is small and heat supply tends to be insufficient. There is a problem that the fixability is weaker than a general configuration in which the fixing belt is heated from the inner peripheral surface side as in the configuration described in JP-A-318001. Also,
There is also a problem that the temperature rise in the non-sheet passing area when a small-size sheet is passed is extremely large, and fixing defects due to temperature unevenness easily occur. Further, the surface (outer peripheral surface) of the fixing belt is easily affected by temperature ripple due to on / off control of a heater (heat source), and in the case of a color image, gloss unevenness due to temperature unevenness is apt to occur.

In the configuration described in Japanese Patent Application Laid-Open No. Hei 9-138597, since the fixing temperature at the time of printing is also obtained by the total amount of heat of the two heat sources, the heat source for heating the outer peripheral surface of the fixing belt is used. Since the heat supply tends to be insufficient due to the same reason as the configuration described in JP-A-138600, there is a problem that the amount of heat as a whole is likely to be insufficient and a fixing failure is likely to occur.

Accordingly, the present invention is to supply a large amount of heat during the start-up of the apparatus to shorten the start-up time, and to supply only the necessary amount of heat during printing to eliminate waste of energy consumption. The main purpose is to provide a fixing device that can be used.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, a fixing roller, a heating roller having a heat source for fixing, and a fixing roller are wound around the heating roller. It has an endless fixing belt and a pressure roller provided opposite to the fixing roller via the fixing belt, and nips and conveys a recording material carrying an image between the fixing belt and the pressure roller. In the fixing device that performs fixing by using a heat source, a configuration is adopted in which a heating heat source is provided only when the device is started up and contributes to a temperature rise at the time of startup together with the fixing heat source.

According to a second aspect of the present invention, in the configuration of the first aspect, a cleaning roller is provided in contact with at least one of the fixing belt and the pressure roller,
The cleaning roller is provided with the heat source for starting up.

According to a third aspect of the present invention, in the configuration of the first aspect, the rising heat source is provided so as to be able to heat the inner peripheral surface of the fixing belt.

According to a fourth aspect of the present invention, in the configuration of the first aspect, the heat source for startup is provided on the heating roller.

According to a fifth aspect of the present invention, in the configuration of the first aspect, the heat source for startup is provided on the pressure roller.

According to the sixth aspect of the present invention, the first to fifth aspects are provided.
In the configuration according to any one of the above, a configuration is adopted in which energization start timings of the fixing heat source and the start-up heat source are made different.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention (corresponding to claims 1 and 2) will be described below with reference to the drawings. First, FIG.
, The overall configuration and functions of a color copying machine as an image forming apparatus will be schematically described. The writing optical unit 400 as an exposure unit includes the color scanner 2
The color image data from 00 is converted into an optical signal and optical writing corresponding to the original image is performed to form an electrostatic latent image on the photoconductor 402 as an image carrier. The writing optical unit 400 includes a laser diode 404, a polygon mirror 406, a rotation motor 408, and an f / θ lens 41.
0, a reflection mirror 412, and the like. The photoconductor 402 is rotated counterclockwise as indicated by the arrow, and the photoconductor cleaning unit 41 is
4, a developing device (a developing device 438 in FIG. 8) selected from the static elimination lamp 416, the potential sensor 420, and the rotary developing device 422, a developing density pattern detector 424, an intermediate transfer belt 426, and the like.

The rotary developing device 422 includes a developing device 428 for black, a developing device 430 for cyan, and a developing device 4 for magenta.
32, a developing unit 434 for yellow, and a rotation drive unit (not shown) for rotating the square developing unit. In order to visualize the electrostatic latent image, each developing device uses
The developing sleeve includes a developing sleeve that rotates in contact with the surface of the developing device 2 and a developing paddle that rotates to pump and agitate the developer. In the standby state, the rotary developing device 422 is set at the position of black development, and when a copying operation is started, reading of black image data is started at a predetermined timing by the color scanner 200, and this image data is read. , The formation of the optical writing / electrostatic latent image (black latent image) by the laser beam starts.

In order to develop from the leading end of the black latent image, before the leading end of the latent image reaches the developing position of the black developing device 428, the rotation of the developing sleeve is started to develop the black latent image with black toner. I do. Thereafter, the developing operation of the black latent image area is continued, but when the rear end of the latent image passes the black developing position, the rotary developing operation is immediately performed from the black developing position to the next color developing position. The device 422 rotates. This operation is completed at least before the leading end of the latent image based on the next image data arrives.
When the image forming cycle is started, first, the photosensitive member 402 is rotated in a counterclockwise direction as indicated by an arrow, and the intermediate transfer belt 426 is rotated in a clockwise direction by a drive motor (not shown). With the rotation of the intermediate transfer belt 426, black toner image formation, cyan toner image formation, magenta toner image formation, and yellow toner image formation are performed.
Finally, the intermediate transfer belt 426 is arranged in the order of black (Bk), cyan (C), magenta (M), and yellow (Y).
The toner image is formed on the upper surface.

The intermediate transfer belt 426 is connected to the drive roller 44
4. The transfer opposed rollers 446a, 446b, the cleaning opposed roller 448, and the driven roller group
The drive is controlled by a drive motor (not shown). The black, cyan, magenta, and yellow toner images sequentially formed on the photoreceptor 402 are accurately and sequentially aligned on the intermediate transfer belt 426.
A belt transfer image of color superposition is formed. This belt transfer image is collectively transferred to a recording material (paper) by a transfer corona discharger 454.

Each recording paper cassette 4 in the paper supply bank 456
58, 460, and 462 include cassettes 464 in the apparatus main body.
Paper of various sizes different from the size of the paper stored in the paper feeding cassette 46.
6, the paper is fed and conveyed in the direction of the registration roller pair 470. In FIG. 8, reference numeral 468 denotes a manual paper feed tray for OHP paper, thick paper, and the like. At the time when the image formation is started, the paper is fed from the paper feed port of any one of the above-mentioned cassettes, and waits at the nip portion of the registration roller pair 470. Then, the intermediate transfer belt 42 is supplied to the corona discharger 454.
When the leading edge of the toner image on the sheet 6 is approaching, the registration roller pair 47 is adjusted so that the leading edge of the sheet just coincides with the leading edge of the image.
0 is driven, and registration of the image with the sheet is performed.

In this way, the paper is transferred to the intermediate transfer belt 4
Corona discharger 4 superimposed on 26 and connected to positive potential
Pass over 54. 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 paper is discharged when passing a portion of a not-shown discharging brush arranged on the left side of the corona discharger 454 in the drawing, and is separated from the intermediate transfer belt 426 and moved to the paper transport belt 472. The sheet on which the four-color superimposed toner image is collectively transferred from the intermediate transfer belt 426 is conveyed by a paper conveying belt 472 to a fixing device 500 of a belt fixing system, and the fixing device 500 fixes the toner image by heat and pressure.
The sheet on which the fixing has been completed is discharged out of the apparatus by a discharge roller pair 480 and stacked on a tray (not shown). This allows
A full color copy is obtained.

Next, the fixing device 500 of the belt fixing type will be described in detail. As shown in FIG.
00 denotes a fixing roller 502, a heating roller 506 having a halogen heater 504 as a fixing heat source therein,
An endless fixing belt 508 looped between the fixing roller 502 and the heating roller 506, and a pressure roller 5 provided to face the fixing roller 502 via the fixing belt 508.
It has ten. The pressing roller 510 is pressed against the fixing roller 502 by a pressing mechanism (not shown), and a nip portion N is formed between the fixing roller 502 and the pressing roller 510 by the pressing. The sheet 514 as a recording material carrying the toner image 512 is
The toner image 512 is guided to the nip portion N by the guide 16 and the toner image 512 is fixed on the sheet 514 by heat and pressure.

At a position of the fixing roller 502 substantially opposed to the pressure roller 510, a cleaning roller 518 for cleaning the offset toner on the fixing belt 508 is in contact with the outer peripheral surface of the fixing belt 508 and is driven to rotate. I have. The cleaning roller 518 is formed of a cylindrical thin roller made of metal such as aluminum, carbon steel, and stainless steel, and has a halogen heater 520 as a startup heat source provided therein. A scraper 522 is in contact with the outer peripheral surface of the cleaning roller 518, and the cleaning roller 518 is moved from the fixing belt 508.
The offset toner that has moved upward is scraped off in the counter direction. Although not shown, the cleaning roller 518 has a heat-resistant release layer such as a fluorine-based resin on its surface layer, so that it is easy to remove extraneous matters such as offset toner and paper powder. Cleaning roller 5
Since the toner 18 is heated by the internal halogen heater 520, the offset toner adhered to the outer peripheral surface of the cleaning roller 518 is heated to a temperature equal to or higher than the toner softening point temperature.
For this reason, the cleaning roller 518 and the fixing belt 50
8 can be eliminated, and the surface of the fixing belt 508 can be prevented from being damaged by the toner.

The cleaning roller 518 may be rotationally driven by a driving source (not shown) in a direction that rotates with the fixing belt 508. In that case, the rotation speed of the cleaning roller 518 is set to be equal to or higher than the peripheral speed of the fixing belt 508. If a linear speed difference is provided between the fixing belt 508 and the fixing belt 508, the cleaning performance can be improved.

In the vicinity of the cleaning roller 518, a release agent applying roller 524 for applying a release agent such as silicone oil to the outer peripheral surface of the fixing belt 508 is configured to rotate while being in contact with the fixing belt 508. A thermistor 526 as a means for detecting the temperature of the fixing belt 508 is provided on the outer peripheral surface of the fixing belt 508 on the side of the heating roller 506, and a detection signal from the thermistor 526 is input to a control unit (not shown). It has become. Based on the detection signal from the thermistor 526, the control means stops the energization of the halogen heater 520 (to be described later) as a heat source for startup, and controls on / off of the halogen heater 504 as a heat source for fixing.

The fixing belt 508 is a thin endless belt made of a heat-resistant resin such as nickel or polyimide, carbon steel, stainless steel, or the like. The surface layer of the fixing belt 508 is configured to be covered with a heat-resistant release layer such as a fluorine-based resin or silicone rubber. In order to obtain good fixability and thermal responsiveness, for example, in the case of a silicon rubber layer, the rubber hardness is preferably in the range of 25 to 65 degrees (JISA hardness meter) and the thickness is in the range of 100 to 300 μm. The endless belt referred to here is a beltless seamless belt formed by nickel electroforming, or a processing method (for example, welding) of an ultra-thin thick plate (thickness of 100 μm or less) of stainless steel or an iron-based material with a thickness of 100 μm or less. Means a seam made by In this case, the step due to the abutting is desirably 20 μm or less, preferably 10 μm or less, so that the image after fixing does not generate horizontal streaks.

The fixing roller 502 has a core bar 502a at the center, and a heat insulating elastic member 502b on the outer periphery thereof to make the nip width sufficiently large. Heat insulating elastic member 5
As 02b, a soft heat-resistant material, for example, foamed silicone rubber can be adopted. Heat insulating elastic member 5
02b has a sufficient thickness, and in this embodiment,
The fixing roller 502 has a thickness of about 15% to 20% of the diameter. The fixing roller 502 is driven to rotate in a direction indicated by an arrow by a driving source (not shown).
10 is driven to rotate in the direction of the arrow. The pressure roller 510 may be driven to rotate by a driving source, and the fixing roller 502 may be driven to rotate.

The pressure roller 510 has a metal core 510a at the center, and has a heat-resistant release layer 510b on its surface. The core metal 510a is made of an aluminum material, stainless steel, carbon steel, or the like, and the release layer 510b is made of a fluorine-based resin, silicon rubber, or the like. In the present embodiment, the shape of the nip portion N is a downward arc shape in order to improve the releasability of the sheet 514 from the fixing belt 508, and this is achieved by increasing the hardness of the pressure roller 510. Specifically, the release layer 510b
Is less than 7% of the diameter of the pressure roller 510, and its hardness is 20 Hs or more according to JISA. The heating roller 506 is formed of a cylindrical thin roller made of metal such as aluminum, carbon steel, and stainless steel.

Next, based on the flowchart of FIG.
The fixing operation of the fixing device 500 according to the above configuration will be described.
When a main switch of the image forming apparatus (color copying machine) is turned on, a halogen heater 504 as a heat source for fixing is used.
Then, the halogen heater 520 as the heat source for startup is turned on, and energization is started (S1). Halogen heater 5
04, the fixing belt 508 is heated from the inner peripheral surface side thereof in a non-rotating state, and the halogen heater 520 is heated.
Thus, the outer peripheral surface is also heated at the same time. The halogen heater 504 has an output that can be fixed by itself, and the total output of the halogen heater 504 and the halogen heater 520 is set to a high output that is allowed as an image forming apparatus.
By the simultaneous heating of the halogen heater 504 and the halogen heater 520, the temperature of the fixing belt 508 rises in a short time.

The control means (not shown) includes a thermistor 526
Of the fixing belt 508 based on the detection signal from the
Is a predetermined fixing temperature T stored in advance in a ROM (not shown).
It is determined whether the _value is equal to or greater than ₀ (S2). When the temperature T of the fixing belt 508 becomes equal to or higher than the predetermined fixing temperature T ₀ , the control unit controls a driving source (not shown) to rotate the fixing belt 508 (S3). When the fixing belt 508 rotates, the heat is transferred to the pressure roller 510.
As a result, the temperature of the fixing belt 508 drops, but since the simultaneous heating by the halogen heater 504 and the halogen heater 520 continues, this temperature drop recovers quickly.

The control means after rotation of the fixing belt 508, the temperature T of the fixing belt 508 it is determined whether becomes equal to or greater than the predetermined fixing temperature T ₀ again (S4). When the temperature T of the fixing belt 508 becomes equal to or higher than the predetermined fixing temperature T ₀ , the control unit stops energizing the halogen heater 504 and the halogen heater 520 (S5). Then, the process proceeds to normal fixing control by turning on / off only the halogen heater 504 (S6), and outputs a print enable signal or a print enable message to an operation panel of an image forming apparatus (not shown) (S7). During the start of printing, the entire fixing belt 508 is uniformly heated by a halogen heater 504 provided in the heating roller 506 and having a fixable output, and the accumulated heat amount is used to transfer the toner image 512 to the paper 5.
14 is fixed. The halogen heater 520 is not energized until the next startup (when the image forming apparatus is turned on or when it is started from standby).

As shown in FIG.
The control system may be such that the fixing belt 508 is rotated at the same time as the energization of 4, 520 is started. When the main switch of the image forming apparatus (color copying machine) is turned on, the halogen heater 504 as a heat source for fixing and the halogen heater 520 as a heat source for starting up are turned on, and energization is started. At the same time, the fixing belt 508 is rotated (S1). Control means, based on the detection signal from the thermistor 526, the temperature T of the fixing belt 508 it is determined whether becomes equal to or greater than the predetermined fixing temperature T ₀ which is previously stored in a ROM (not shown) (S2). Temperature T of fixing belt 508
Is equal to or higher than the predetermined fixing temperature T ₀ ,
The control means includes a halogen heater 504 and a halogen heater 52.
The energization to 0 is stopped (S3). Then, the process proceeds to normal fixing control by turning on / off only the halogen heater 504 (S4), and outputs a print enable signal or a print enable message to an operation panel (not shown) of the image forming apparatus (S5).

In this embodiment, the cleaning roller 518 is used.
There is no means for maintaining and controlling the temperature at a predetermined temperature from the viewpoint of simplification of the configuration and cost reduction. For this reason, in the method of starting up while the rotation of the fixing belt 508 is stopped, it is necessary to prevent the cleaning roller 518 from being excessively heated and thermally deteriorating the surface layer of the roller and the surface layer of the fixing belt 508 that is a contact partner. . For this purpose, the cleaning roller 518 needs to have a heat capacity configuration so as not to be excessively heated. For example, even when a heat-resistant release layer made of silicon rubber, fluororesin, or the like is provided on the surface layer of the cleaning roller 518, if the roller surface layer is excessively heated, the temperature of the cleaning roller 518 is set to 250 ° C. or less. It is desirable to determine the configuration. In such a configuration, the cleaning roller 518
It is not necessary to particularly provide a temperature detection sensor, a temperature control circuit, and an ON / OFF switch circuit for controlling the temperature of the device to a predetermined temperature, so that the configuration can be simplified and the cost can be reduced. Of course, the cleaning roller 518 may be independently controlled to a predetermined temperature.

In the above embodiment, the cleaning roller 5
Halogen heater 520 as a heat source for start-up
However, a heat conductive member having no cleaning function, for example, a metal cylindrical roller is similarly brought into contact with the outer peripheral surface of the fixing belt 508, and the halogen heater 520 is provided in the heat conductive member. Is also good. Further, the halogen heater 520 is connected to the cleaning roller 518.
Alternatively, the fixing belt 508 may be provided in the vicinity of the outer peripheral surface and heated by radiant heat.

Next, a modification of the first embodiment will be described with reference to FIG. Note that the same parts as those in the above-described embodiment are denoted by the same reference numerals, and repeated description is omitted unless otherwise required (the same applies to other embodiments described below).
In the fixing device 500 according to the present exemplary embodiment, the cleaning roller 518 is provided near the lower surface of the sheet conveyance guide plate 516 so as to be in contact with the outer peripheral surface of the fixing belt 508 and to be driven to rotate. A halogen heater 520 is provided as a heat source for startup. The cleaning roller 518 is for cleaning paper dust and the like on the pressure roller 510, and its configuration, function, and the like are as described in the first embodiment. Further, at the position where the cleaning roller 518 is provided in the first embodiment, a cleaning roller 528 having only a cleaning function and having no heat source therein is provided with a fixing belt 5.
08 is provided in contact with the outer peripheral surface. The driving method of the cleaning roller 528 is the same as that of the cleaning roller 518.
Is the same as

In the conventional configuration, when the fixing belt 508 rotates after rising, the temperature of the fixing belt 508 drops significantly and at the same time, it takes a long time to recover to a predetermined fixing temperature. This is because a part of the heat from the heated fixing belt 508 is transmitted to the inside of the pressure roller 510 in contact with the fixing belt 508, and the fixing belt 508 is cooled and the pre-rotation time becomes longer. On the other hand, in the present embodiment, at the time of rising, the outer periphery of the pressure roller 510 is quickly heated by the halogen heater 520, so that heat transfer from the fixing belt 508 to the pressure roller 510 is suppressed, and the rising time is shortened. Also, the halogen heater 520
Is located near the paper transport guide plate 516,
The sheet transport guide plate 516 is driven by the halogen heater 520.
Is also heated, which also serves as preliminary heating of the toner image 512 on the sheet 514. Therefore, there is an advantage that the fixing property is improved. The pressure roller 51 shown in FIG.
A configuration in which a heating configuration of 0 is added may be adopted. That is, the halogen heater 520 as a heat source for startup may be provided on both the fixing belt 508 and the pressure roller 510. In this case, the halogen heater 520 may be provided inside the cleaning roller 518, or the halogen heater 520 may be provided separately from the cleaning roller 518. The control is the same as in the first embodiment. That is, power is supplied to the halogen heaters 504 and 520 until the fixing belt 508 rises to a predetermined temperature, and the fixing belt 508 is heated only by the halogen heater 504 during printing.

Next, an embodiment corresponding to claim 3 will be described with reference to FIG. Fixing device 50 in this embodiment
At 0, a halogen heater 520 as a heat source for rising is provided inside the fixing belt 508 so that the inner peripheral surface of the fixing belt 508 can be heated. Specifically, the halogen heater 520 is provided between the fixing roller 502 and the heating roller 506 inside the fixing belt 508, and the inner peripheral surface of the fixing roller 502 is directly heated by the radiant heat of the halogen heater 520. A heat reflection plate 530 is provided between the halogen heater 520 and the fixing roller 502 to prevent the fixing roller 502 from being heated by the radiant heat and to increase the heating efficiency of the halogen heater 520. According to the present embodiment, since the heat source is located inside the fixing belt 508, the heat efficiency is good, and the risk of smoke or ignition of jammed paper is small.

The control in this embodiment is performed by the fixing belt 5
08 to prevent it from being overheated and damaged.
Similarly to the above, it is desirable that the fixing belt 508 be rotated at the same time when the current supply to the halogen heaters 504 and 520 is started. Of course, if a temperature detection sensor is provided near the halogen heater 520, for example, the heat reflection plate 530 to perform independent temperature control, the fixing belt 508 does not need to be rotated. Power is supplied to the halogen heaters 504 and 520 until the fixing belt 508 rises to a predetermined temperature, and the fixing belt 508 is heated only by the halogen heater 504 during printing.

Next, an embodiment corresponding to claim 4 will be described with reference to FIG. Fixing device 50 in this embodiment
In the case of 0, a halogen heater 504 as a starting heat source is provided in the heating roller 506 together with a halogen heater 504 as a fixing heat source. The control is the same as in the first embodiment. That is, until the fixing belt 508 rises to a predetermined temperature, the halogen heater 504
Electric power is supplied to the fixing belt 520 and the fixing belt 508 is heated only by the halogen heater 504 during printing.

Next, an embodiment corresponding to claim 5 will be described with reference to FIG. Fixing device 50 in this embodiment
At 0, a halogen heater 520 is provided inside the pressure roller 510 as a heat source for startup. The control is the same as in the first embodiment. That is, the fixing belt 50
Electric power is supplied to the halogen heaters 504 and 520 until the temperature of the fixing belt 8 reaches a predetermined temperature, and the fixing belt 508 is heated only by the halogen heater 504 during printing. The shaft end 506a of the heating roller 506 in FIG.
Is smaller in diameter due to the belt deviation control means shown in the figure. Therefore, when two halogen heaters 504 and 520 are provided in the heating roller 506, the assemblability of the heaters becomes a problem, but in the present embodiment, the halogen heater 520 is replaced by a pressing roller 51 different from the heating roller 506.
Since the configuration is provided inside the heater, there is an advantage that the problem of the assemblability of the heater can be solved.

In each of the above-described embodiments, the control method in which the halogen heater 504 and the halogen heater 520 are simultaneously turned on at the time of startup is adopted, but a control method in which the energization start timing is made different may be adopted. In each of the above embodiments, energization is started by a high-power halogen heater as a whole in order to shorten the start-up time. In this case, an inrush current at the start of energization is extremely large, such as flickering of a fluorescent lamp due to a voltage drop. , Noise is generated in peripheral devices. By making the energization start timing different, it is possible to avoid an inrush current when the heater is turned on,
The above problem can be prevented.

[0041]

According to the present invention, at the time of start-up, two heat sources, a fixing heat source and a start-up heat source, instantaneously start up with a high output, and after the start of printing, only the fixing heat source having an output capable of fixing is used. Since the fixing belt is heated, the start-up time can be reduced, and stable fixing performance without gloss unevenness can be obtained even when forming a color image. After the start of printing, only the fixing heat source is energized, so that the temperature ripple due to the ON / OFF of the heater is small, stable temperature control can be performed, and noise generation and uneven gloss can be prevented.

In particular, according to the second aspect of the present invention, since the cleaning roller is provided with a heat source for startup, the cleaning function and the quick startup function can be obtained in a compact configuration.

In particular, according to the sixth aspect of the present invention, since the start of energization to the fixing heat source and the start-up heat source are made different, problems caused by an excessive rush current during energization are prevented. can do.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a fixing device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a fixing operation.

FIG. 3 is a flowchart illustrating another fixing operation.

FIG. 4 is a schematic front view of a fixing device according to a second embodiment.

FIG. 5 is a schematic front view of a fixing device according to a third embodiment.

FIG. 6 is a schematic front view of a fixing device according to a fourth embodiment.

FIG. 7 is a schematic front view of a fixing device according to a fifth embodiment.

FIG. 8 is a schematic front view of an image forming apparatus provided with a fixing device according to the present invention.

[Explanation of symbols]

 502 Fixing roller 504 Halogen heater as fixing heat source 506 Heating roller 508 Fixing belt 510 Pressure roller 514 Paper as recording material 518 Cleaning roller 520 Halogen heater as start-up heat source

Claims (6)

[Claims] A fixing roller, a heating roller having a heat source for fixing, an endless fixing belt wound between the fixing roller and the heating roller, and an endless fixing belt facing the fixing roller via the fixing belt. A fixing device having a pressure roller provided and fixing the image by holding and transporting a recording material carrying an image between the fixing belt and the pressure roller. A fixing device, comprising a heat source for start-up that contributes to a temperature rise at the time of start-up together with the heat source. 2. The fixing device according to claim 1, wherein a cleaning roller is provided in contact with at least one of the fixing belt and the pressure roller, and the cleaning roller is provided with the heat source for startup. A fixing device characterized by the above-mentioned. 3. The fixing device according to claim 1, wherein the heat source for rising is provided so as to heat an inner peripheral surface of the fixing belt. 4. The fixing device according to claim 1, wherein said heat-up source is provided on said heating roller. 5. The fixing device according to claim 1, wherein the heat source for rising is provided on the pressure roller. 6. The fixing device according to claim 1, wherein the energization start timings of the fixing heat source and the start-up heat source are made different.