JP2007058249A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the rise time of a fixing device in a belt fixing system. <P>SOLUTION: A fixing belt 508 is stretched around between a fixing roller 502 and a heat roller 506, and a pressure roller 510 is pressed to the fixing roller 502 through the fixing belt 508 to form a nip N. A cleaning roller 518 for cleaning the fixing belt 508 is provided approximately in opposition to the pressure roller 510 through the fixing roller 508 and has a halogen heater 520 as a heat source for rise, provided therein. When the fixing device is started, a halogen heater 504 as a heat source for fixing in the heat roller 506 and the halogen heater 520 are simultaneously fed to start the fixing device in an instant by a high output allowed for an image forming apparatus. During print, only the halogen heater 504 having an output capable of fixing is fed to perform fixing with a low power. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device that is used in an image forming apparatus such as a copying machine, a printer, and a facsimile machine, and performs fixing by heat and pressure while conveying a recording material, and more particularly to a belt fixing type fixing device.

Conventionally, as a fixing device used in an image forming apparatus, a fixing nip portion is formed by pressing a pressure roller against a fixing roller having a heat source, and a recording material is sandwiched and conveyed by the fixing nip portion. A heat roller fixing method in which fixing is performed by pressure is known.
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, as described in Patent Document 1, for example, an endless fixing belt is driven to rotate between a fixing roller and a heating roller having a heat source such as a halogen heater inside, and the fixing roller. On the side, a pressure roller is pressed from the outside of the fixing belt 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 at the fixing nip portion located downstream of the heating roller in the recording material conveyance direction, and the toner is cooled. .

Patent Document 2 describes a configuration in which a heating roller is pressed against an outer peripheral surface of a fixing belt inward to heat the fixing belt.
In Patent Document 3, 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 provided separately, and the temperature rise at the start-up and the fixing at the time of printing are based on the total heat amount of these heat sources. A configuration for obtaining temperature is described.

JP-A-6-31801 JP-A-9-138600 JP-A-9-138597

  In the configuration described in Japanese Patent Application Laid-Open No. H10-228707, the heating roller has only a heat source. Therefore, when the fixing belt rotates after rising, a part of the heat of the heated fixing belt comes into contact with the fixing roller. In addition, the temperature of the fixing belt is greatly reduced because it is transferred to the inside of the pressure roller and escapes. For this reason, it takes time to recover to a predetermined fixing temperature, and in the end, a satisfactory start-up time cannot be obtained from the viewpoint of quick start.

In the configuration described in Patent Document 2, 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 is likely to be insufficient. Therefore, fixing is performed as in the configuration described in Patent Document 1. There is a problem that the fixing property is poor as compared with the general configuration in which heating is performed from the inner peripheral surface side of the belt.
In addition, there is a problem that the temperature rise in the non-sheet-passing area when a small-size sheet is passed is extremely large, and fixing failure due to temperature unevenness is likely to occur.
Further, the surface (outer peripheral surface) of the fixing belt is easily affected by temperature ripple due to on / off control of the heater (heat source), and in the case of a color image, there is a problem that uneven gloss due to temperature unevenness is likely to occur.

  In the configuration described in Patent Document 3, the fixing temperature at the time of printing is also obtained by the total amount of heat of the two heat sources. Therefore, the heat source that heats the outer peripheral surface of the fixing belt has the same reason as the configuration described in Patent Document 2. As a result, the heat supply tends to be insufficient, so that there is a problem in that the amount of heat as a whole is likely to be insufficient and fixing defects are likely to occur.

  Accordingly, the present invention provides a fixing device capable of supplying a large amount of heat when starting up the apparatus to shorten the start-up time and supplying only the amount of heat necessary for printing to eliminate waste of energy consumption. Is the main purpose.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided a fixing roller, a heating roller having a fixing heat source, an endless fixing belt wound between the fixing roller and the heating roller, and the fixing roller. In a fixing device having a pressure roller provided opposite to the fixing roller via a belt and fixing the image by holding and conveying a recording material carrying an image between the fixing belt and the pressure roller. A configuration is adopted in which a startup heat source that is energized only at the time of startup of the apparatus and contributes to temperature rise at startup is provided together with the fixing heat source.

  According to a second aspect of the present invention, in the configuration according to the first aspect, a cleaning roller is provided in contact with at least one of the fixing belt and the pressure roller, and the heating heat source is provided on the cleaning roller. The structure is taken.

  According to a third aspect of the present invention, in the configuration according to the first aspect, the start-up heat source is provided so as to heat the inner peripheral surface of the fixing belt.

  According to a fourth aspect of the present invention, in the configuration according to the first aspect, the start-up heat source is provided on the heating roller.

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

  According to a sixth aspect of the present invention, in the configuration according to any one of the first to fifth aspects, the energization start timing for the fixing heat source and the start-up heat source is made different.

  According to the present invention, at the time of start-up, the fixing heat source and the start-up heat source are used to instantly start up at a high output, and after the start of printing, the fixing belt is heated only by the fixing heat source having a fixable output. With this configuration, it is possible to shorten the start-up time and to obtain a stable fixing performance without uneven gloss even in the case of color image formation. Since only the heat source for fixing is energized after the start of printing, the temperature ripple due to heater on / off is small, and stable temperature control can be performed, thereby preventing noise and uneven gloss.

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

  In particular, according to the invention described in claim 6, since the energization start timings for the fixing heat source and the start-up heat source are made different, it is possible to prevent problems due to excessive inrush current during energization. it can.

Hereinafter, embodiments of the present invention (corresponding to claims 1 and 2) will be described with reference to the drawings.
First, the 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. 8), 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 development operation of the black latent image area is continued, but when the trailing edge of the latent image passes the black development position, the rotary development is quickly performed from the development position for black to the development position for the next color. The 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. 8, 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.
As shown in FIG. 1, the fixing device 500 includes a fixing roller 502, a heating roller 506 having a halogen heater 504 as a heat source for fixing therein, and an endless shape wound around the fixing roller 502 and the heating roller 506. The image forming apparatus includes a fixing belt 508 and a pressure roller 510 provided to face the fixing roller 502 with the fixing belt 508 interposed therebetween.
The pressure roller 510 is pressed against the fixing roller 502 by a not-shown pressing mechanism, and a nip portion N is formed between the fixing roller 502 and the pressure roller 510 by this pressure contact. A sheet 514 as a recording material carrying the toner image 512 is guided by the sheet conveyance guide plate 516 and enters the nip portion N, where the toner image 512 is fixed to the sheet 514 by heat and pressure.

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 at a position substantially opposite to the pressure roller 510 of the fixing roller 502. The cleaning roller 518 is a cylindrical thin roller made of metal such as aluminum, carbon steel, and stainless steel, and a halogen heater 520 serving as a heat source for startup is provided therein. A scraper 522 is in contact with the outer peripheral surface of the cleaning roller 518, and the offset toner transferred from the fixing belt 508 onto the cleaning roller 518 is scraped off in the counter direction.
Although not shown, the cleaning roller 518 has a heat-resistant release layer such as a fluororesin on its surface layer so that deposits such as offset toner and paper dust can be easily removed.
Since the cleaning roller 518 is heated by the internal halogen heater 520, the offset toner adhering to the outer peripheral surface of the cleaning roller 518 is heated to the toner softening point temperature or higher. Therefore, the problem that the cleaning roller 518 and the fixing belt 508 are fixed through the toner can be solved, and the problem that the surface of the fixing belt 508 is damaged by the toner can be solved.

  The cleaning roller 518 may be driven to rotate in a direction that rotates with the fixing belt 508 by a driving source (not shown). In that case, the rotational speed of the cleaning roller 518 is set to be the same as or faster than the peripheral speed of the fixing belt 508. Cleaning performance can be improved by providing a linear velocity difference with the fixing belt 508.

In the vicinity of the cleaning roller 518, a release agent application roller 524 that applies a release agent such as silicone oil to the outer peripheral surface of the fixing belt 508 is in contact with the fixing belt 508 and rotates.
A thermistor 526 is provided on the outer peripheral surface of the fixing belt 508 on the heating roller 506 side as a means for detecting the temperature of the fixing belt 508. A detection signal from the thermistor 526 is input to a control means (not shown). It is like that. Based on a detection signal from the thermistor 526, the control unit performs energization stop (described later) of the halogen heater 520 as a start-up heat source, on / off control of the halogen heater 504 as a fixing heat source, and the like.

The fixing belt 508 is a thin endless belt formed 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 silicon rubber. In order to obtain good fixability and thermal responsiveness, for example, in the case of a silicon rubber layer, a rubber hardness of 25 to 65 degrees (JISA hardness meter) and a thickness of 100 to 300 μm are desirable.
The endless belt referred to here is a method using a nickel electroforming method without a belt joint, or a processing method using a precision butting technique (for example, welding) of an ultra-thin plate (thickness of 100 μm or less) made of stainless steel or iron-based material. Means a seam made by In this case, the level difference due to the matching is desirably 20 μm or less, preferably 10 μm or less, as a level in which the image after fixing does not become a horizontal stripe.

  The fixing roller 502 has a core metal 502a at the center, and a heat insulating elastic member 502b for making the nip width sufficiently wide on the outer periphery thereof. As the heat insulating elastic member 502b, a soft heat resistant material, for example, foamed silicon rubber can be used. The heat insulating elastic member 502b has a sufficient thickness. In this embodiment, the heat insulating elastic member 502b has a thickness of 15% to 20% of the diameter of the fixing roller 502. The fixing roller 502 is rotationally driven in the direction of the arrow by a driving source (not shown), and the pressure roller 510 is driven to rotate in the direction of the arrow. The pressure roller 510 may be rotationally driven by a drive source, and the fixing roller 502 may be driven to rotate.

The pressure roller 510 has a cored bar 510a at the center and a heat-resistant release layer 510b on the surface layer. The core metal 510a is made of aluminum, stainless steel, carbon steel, or the like, and the release layer 510b is made of fluorine resin, silicon rubber, or the like.
In this embodiment, in order to improve the peelability of the paper 514 from the fixing belt 508, the nip portion N has a downward arc shape, which is achieved by increasing the hardness of the pressure roller 510. Specifically, the thickness of 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, the fixing operation of the fixing device 500 according to the above configuration will be described based on the flowchart of FIG.
When the main switch of the image forming apparatus (color copying machine) is turned on, the halogen heater 504 as a fixing heat source and the halogen heater 520 as a start-up heat source are turned on, and energization is started (S1). The fixing belt 508 is heated by the halogen heater 504 from the inner peripheral surface side without rotating, and simultaneously heated from the outer peripheral surface side by the halogen heater 520. 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 simultaneous heating of the halogen heater 504 and the halogen heater 520, the temperature of the fixing belt 508 rises in a short time.

A control unit (not shown) determines whether the temperature T of the fixing belt 508 is equal to or higher than a predetermined fixing temperature To stored in advance in a ROM (not shown) based on the detection signal from the thermistor 526 (S2). . When the temperature T of the fixing belt 508 becomes equal to or higher than the predetermined fixing temperature To, 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 and the like, so the temperature of the fixing belt 508 decreases. However, since the simultaneous heating by the halogen heater 504 and the halogen heater 520 continues, this temperature decrease is early. To recover.

After the rotation of the fixing belt 508, the control unit determines again whether the temperature T of the fixing belt 508 is equal to or higher than the predetermined fixing temperature To (S4). When the temperature T of the fixing belt 508 becomes equal to or higher than the predetermined fixing temperature To, 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 a printable signal or a printable message is output to an operation panel (not shown) of the image forming apparatus (S7). During the start of printing, the entire fixing belt 508 is uniformly heated by the halogen heater 504 provided in the heating roller 506 and having a fixable output, and the toner image 512 is fixed on the paper 514 by the stored heat amount.
The halogen heater 520 is not energized until the next startup (when the image forming apparatus is turned on or started from standby).

As shown in FIG. 3, a control method may be used in which the fixing belt 508 is rotated when the energization of the halogen heaters 504 and 520 is started.
When the main switch of the image forming apparatus (color copying machine) is turned on, the halogen heater 504 as a fixing heat source and the halogen heater 520 as a startup heat source are turned on, and energization is started. At the same time, the fixing belt 508 is rotated (S1). Based on the detection signal from the thermistor 526, the control unit determines whether the temperature T of the fixing belt 508 is equal to or higher than a predetermined fixing temperature To stored in advance in a ROM (not shown) (S2). When the temperature T of the fixing belt 508 is equal to or higher than the predetermined fixing temperature To, the control unit stops energizing the halogen heater 504 and the halogen heater 520 (S3). Then, the process proceeds to normal fixing control by turning on / off only the halogen heater 504 (S4), and a printable signal or a printable message is output to an operation panel (not shown) of the image forming apparatus (S5).

In the present embodiment, means for maintaining and controlling the cleaning roller 518 at a predetermined temperature is not provided from the viewpoint of simplification of configuration and cost reduction.
For this reason, in the method of starting up with the rotation of the fixing belt 508 stopped, the cleaning roller 518 must not be excessively heated to thermally deteriorate the roller surface layer or the surface layer of the fixing belt 508 that is in contact with the cleaning roller 518. . For this purpose, the cleaning roller 518 needs to have a heat capacity configuration so as not to be heated excessively. For example, even when a heat-resistant release layer such as silicon rubber or fluorine resin 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 lower. It is desirable to determine the configuration.
In such a configuration, it is not necessary to provide a temperature detection sensor, a temperature control circuit, and an ON / OFF switch circuit for controlling the cleaning roller 518 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-described embodiment, the halogen heater 520 serving as a heat source for startup is provided in the cleaning roller 518. However, a heat conductive member having no cleaning function, for example, a metal cylindrical roller, is similarly used for the fixing belt 508. It is good also as a structure which contacts the outer peripheral surface and provides the halogen heater 520 in this heat conductive member.
Alternatively, the halogen heater 520 may be provided near the outer peripheral surface of the fixing belt 508 separately from the cleaning roller 518 and heated by radiant heat.

Next, a modification of the embodiment corresponding to claims 1 and 2 will be described with reference to FIG.
In addition, the same part as the said embodiment is shown with the same code | symbol, and duplication description is abbreviate | omitted unless there is particular need (it is the same in the following other embodiment).
In the fixing device 500 according to the present embodiment, the cleaning roller 518 is provided in the vicinity of the lower surface of the sheet conveyance guide plate 516 so as to contact the outer peripheral surface of the fixing belt 508 and be driven to rotate. Is provided with a halogen heater 520 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 above 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 in contact with the outer peripheral surface of the fixing belt 508. The driving method of the cleaning roller 528 is the same as that of the cleaning roller 518.

In the conventional configuration, when the fixing belt 508 is rotated after the start-up, it takes a long time to recover to a predetermined fixing temperature at the same time as the temperature drops greatly.
This is because part of the heat from the heated fixing belt 508 is transmitted to the inside of the pressure roller 510 that contacts the fixing belt 508, and the fixing belt 508 is cooled, and the pre-rotation time is increased.
On the other hand, in this embodiment, since the outer periphery of the pressure roller 510 is quickly heated by the halogen heater 520 at the time of rising, the heat transfer from the fixing belt 508 to the pressure roller 510 is suppressed, and the rising time is shortened.
In addition, since the halogen heater 520 is positioned in the vicinity of the paper transport guide plate 516, the paper transport guide plate 516 is also heated by the halogen heater 520, and the toner image 512 on the paper 514 is also preheated. For this reason, there is an advantage that the fixing property is improved.
It is good also as a structure which added the heating structure of the pressure roller 510 shown in FIG. 4 to the structure shown in FIG. In other words, both the fixing belt 508 and the pressure roller 510 may be provided with a halogen heater 520 as a starting heat source. In this case, the halogen heater 520 may be provided in 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, energization of the halogen heaters 504 and 520 is performed 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.
In the fixing device 500 according to the present embodiment, a halogen heater 520 as a heat source for rising is provided inside the fixing belt 508 so as to heat the inner peripheral surface of the fixing belt 508. 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 reflecting plate 530 is provided between the halogen heater 520 and the fixing roller 502 so that the fixing roller 502 is not heated by the radiant heat and the heating efficiency of the halogen heater 520 is increased.
According to the present embodiment, since the heat source is located inside the fixing belt 508, the heat efficiency is good, and there is little risk of smoking and firing on jam paper.

In the present embodiment, the fixing belt 508 is rotated simultaneously with the start of energization of the halogen heaters 504 and 520 in the same manner as shown in FIG. 3 so that a part of the fixing belt 508 is not excessively heated and damaged. It is desirable to use the method
Of course, if the temperature detection sensor is provided in the vicinity of the halogen heater 520, for example, the heat reflection plate 530, and independent temperature control is performed, the fixing belt 508 need not be rotated.
The energization of the halogen heaters 504 and 520 is performed 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.
In the fixing device 500 according to the present embodiment, a halogen heater 520 as a start-up heat source is provided in the heating roller 506 together with a halogen heater 504 as a heat source for fixing. The control is the same as in the first embodiment. That is, energization of the halogen heaters 504 and 520 is performed 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 5 will be described with reference to FIG.
In the fixing device 500 in the present embodiment, a halogen heater 520 as a heat source for startup is provided inside the pressure roller 510. The control is the same as in the first embodiment. That is, energization of the halogen heaters 504 and 520 is performed 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.
The shaft end portion 506a of the heating roller 506 in FIG. 6 has a small diameter due to the belt deviation control means not shown. Therefore, when two halogen heaters 504 and 520 are provided in the heating roller 506, the assembly of the heaters becomes a problem. However, in this embodiment, the halogen heater 520 is different from the heating roller 506 inside the pressure roller 510. Therefore, there is an advantage that it is possible to solve the problem of assembly of the heater.

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 start-up is used. However, a control method in which each energization start time is different may be used.
In each of the above embodiments, energization is started with a high-power halogen heater as a whole in order to shorten the start-up time. In this case, the inrush current at the start of energization is extremely large, such as flickering of a fluorescent lamp due to a voltage drop, etc. , Noise is generated in peripheral devices.
By making the energization start time different, it is possible to avoid an excessive inrush current when the heater is turned on, and to prevent the above problems.

1 is a schematic front view of a fixing device according to an embodiment of the present invention. 6 is a flowchart showing a fixing operation. 10 is a flowchart showing another fixing operation. FIG. 4 is a schematic front view of a fixing device according to a second embodiment. FIG. 10 is a schematic front view of a fixing device according to a third embodiment. FIG. 10 is a schematic front view of a fixing device according to a fourth embodiment. FIG. 10 is a schematic front view of a fixing device according to a fifth embodiment. 1 is a schematic front view of an image forming apparatus including a fixing device according to the present invention.

Explanation of symbols

502 Fixing roller 504 Halogen heater as heat source for fixing 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)

A fixing roller, a heating roller having a fixing heat source, an endless fixing belt wound between the fixing roller and the heating roller, and a pressure provided to face the fixing roller via the fixing belt In a fixing device that has a roller and holds and fixes a recording material carrying an image between the fixing belt and a pressure roller,
A fixing device characterized in that a startup heat source that is energized only when the device starts up and contributes to temperature rise at the time of startup together with the fixing heat source is provided. The fixing device according to claim 1.
A fixing device, wherein a cleaning roller is provided in contact with at least one of the fixing belt and the pressure roller, and the cleaning heat source is provided on the cleaning roller. The fixing device according to claim 1.
The fixing device, wherein the startup heat source is provided so as to heat an inner peripheral surface of the fixing belt. The fixing device according to claim 1.
The fixing device, wherein the heating heat source is provided on the heating roller. The fixing device according to claim 1.
The fixing device, wherein the startup heat source is provided in the pressure roller. The fixing device according to any one of claims 1 to 5,
A fixing device characterized in that energization start timings for the fixing heat source and the startup heat source are different.

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