JP2006194930A - Fixing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing apparatus capable of reducing the loss of heat energy and reducing the temperature drop of the fixing apparatus at the time of continuous printing. <P>SOLUTION: An external heating member coming in contact with a heating member is arranged, and the rotating direction of the heating member and the rotating direction of the external heating member are opposite to each other at the contact part of the heating member with the external heating member, and the apparatus includes a control means for controlling the velocity ratio V<SB>1</SB>/V<SB>2</SB>of the linear velocity V<SB>1</SB>of the external heating member to the rotating linear velocity V<SB>2</SB>of the heating member to be 0.5 to 1.5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

    The present invention relates to a fixing device used in an electrophotographic image forming apparatus such as a printer or a copying machine.

  A fixing device, which is a type of typical heating device used in electrophotographic equipment such as copying machines and printers, generally has a halogen heater or the like inside a fixing roller (also referred to as a heating member) made of a hollow core metal such as aluminum. The heating means is arranged, the halogen heater generates heat, the fixing roller is set to a predetermined temperature (fixing temperature), and the transfer material (also referred to as recording paper) such as paper on which unfixed toner is transferred, OHP, etc. With the unfixed toner transfer surface facing the fixing roller, the unfixed toner is passed through a pressure contact portion (hereinafter also referred to as a nip portion) with a pressure roller (also referred to as a pressure member) disposed in pressure contact with the fixing roller. A structure for thermocompression bonding (hereinafter referred to as an internal heating method) has been frequently used.

  However, with this internal heating method, after the start of heating, the so-called warm-up time, which is the time until the fixing roller reaches the fixing temperature, is long, and preheating is performed so as not to lower the temperature of the fixing roller even during standby from the viewpoint of ease of use. Therefore, there is a problem in terms of electric energy saving because power consumption during standby is large.

  Further, when the printing speed is increased, a large amount of heat energy is taken away from the fixing temperature by the transfer paper, so that it becomes difficult to keep the fixing temperature constant.

  In order to solve the above problem, Patent Document 1 includes an external heating type fixing device that heats the surface of the fixing roller by a heating roller disposed in contact with the surface of the fixing roller, and a heat source is brought into contact with the surface of the fixing roller, A configuration is disclosed in which the warm-up time is greatly shortened and the power consumption during standby is reduced by improving the thermal efficiency.

Patent Document 2 proposes a method for compensating for the temperature decrease by providing an external heating roller driven by the heating roller and providing a plurality of heat sources on the heating roller as a countermeasure for increasing the temperature decrease amount due to the increase in printing speed. Yes.
JP-A-10-133505 JP 2004-22249 A

  However, in the fixing device of the external heating method of Patent Document 1, since the heating means such as the external heating roller is disposed in contact with the outside of the heating member, the amount of heat transferred from the external heating roller to the heating member is large. The heat transfer efficiency for transmitting the entire amount of heat of the roller to the heating member is lower than that of the internal heating type fixing device.

  Furthermore, since the heat resistance temperature of the external heating means is determined by the material such as 200 ° C. in the case of fluororesin, there is a limit to the power input to the heat source. As a result, the heat energy transferred to the heating member is as low as about ¼ of the internal heating method, resulting in insufficient heat supply performance to the heating member. Therefore, when fixing toner or the like on the recording medium continuously at a high speed, the recording medium loses more heat than the external heating means supplies to the heating member, and the temperature of the heating member decreases, and the toner is removed. Low temperature offset that does not melt and fix properly may occur, and fixing performance could not be secured.

  Patent Document 2 proposes a means having a plurality of heat sources for the external heating roller and further the pressure roller in order to solve the problem of Patent Document 1, but it is the best because it leads to an increase in the size of the fixing device and an increase in power consumption. It's not a method.

  An object of the present invention is to provide a fixing device that reduces thermal energy loss and reduces the temperature drop of the fixing device during continuous printing.

The above object can be achieved by the following configuration.
(Claim 1)
The transfer material carrying the unfixed toner image is nipped and conveyed to a nip formed by a heating member that contacts and heats the unfixed toner image while moving endlessly, and a pressure member that presses the heating member. In the fixing device for fixing,
An external heating member that contacts the contact surface of the heating member with the unfixed toner image while moving endlessly and that heats the heating member;
An endless movement direction of the external heating member is a direction opposite to the endless movement direction of the heating member at a contact portion between the heating member and the external heating member.
(Claim 2)
The fixing device according to claim 1, wherein the heating member and the pressure member are rollers having an elastic layer.
(Claim 3)
The heating member includes a fixing roller, a heating roller having a heat source, the fixing roller and a fixing belt stretched around the heating roller,
The fixing device according to claim 1, wherein the pressure member is in pressure contact with the fixing roller via an outer peripheral surface of the fixing belt.
(Claim 4)
The fixing device according to claim 1, wherein the external heating member is a roller.
(Claim 5)
The external heating member includes an external heating roller having a heat source, an external support roller, and an external belt stretched between the external heating roller and the external support roller,
The fixing device according to claim 1, wherein the heating member is in contact with an external belt heating unit via an outer peripheral surface of the external belt.
(Claim 6)
Claim, characterized in that it comprises a control means for the speed ratio V ₁ / V ₂ between the rotational linear velocity V ₂ of the heating member and the linear velocity V ₁ of the said external heating member is controlled to 0.5 to 1.5 The fixing device according to any one of 1 to 5.

  According to the first aspect of the present invention, there is provided a fixing device that forms a nip portion by pressing a pressure member against a heating member, and fixes the transfer material holding an unfixed toner image by nipping and conveying the transfer material. An external heating member that contacts the member is provided, and the temperature of the external heating member is not deprived because the rotation direction of the heating member is opposite to the rotation direction of the external heating member at the contact portion between the heating member and the external heating member. Since the portions come into contact with the heating member one after another, thermal energy loss can be reduced, and the temperature drop of the fixing device during continuous printing can be reduced.

  According to the second aspect of the present invention, since the heating member and the pressure member are rollers having an elastic layer, it is possible to provide a fixing device required for a high-quality color image forming apparatus that does not cause image collapse.

According to the invention of claim 3, the heating member includes a fixing roller, a heating roller having a heat source, the fixing roller and a fixing belt stretched around the heating roller,
Since the pressure member is a belt fixing system in which the fixing member is pressed against the fixing roller via the outer peripheral surface of the fixing belt, heat is accumulated on the belt having a small heat capacity, and the rise time of the warm-up is fast. Since a wider nip width can be formed, a fixing device capable of fixing at a lower temperature than a roller fixing device can be provided.

  According to the invention of claim 4, since the external heating member is a roller, a small fixing device can be provided.

According to the invention of claim 5, the external heating member includes an external heating roller having a heat source, an external support roller, and an external belt stretched between the external heating roller and the external support roller,
Since the heating member is in contact with the external belt heating means via the outer peripheral surface of the external belt, the nip width is wider than the roller shape, the heat from the external heating means is sufficiently supplied, and the temperature decreases. It is possible to provide a fixing device with a small amount.

The speed ratio V ₁ / V ₂ of the linear velocity V ₁ of the outer heating member and the rotation linear velocity V ₂ of the heating member has a control means for controlling the 0.5-1.5 According to the invention of claim 7 Thus, it is possible to provide a fixing device that can reduce a decrease in fixing temperature during continuous printing.

  An embodiment of the present invention will be described. The description in this column does not limit the technical scope of the claims or the meaning of terms. In addition, the following assertive description in the embodiment of the present invention shows the best mode, and does not limit the meaning or technical scope of the terms of the present invention.

  An image forming apparatus including the fixing device according to the present invention will be described below with reference to FIG.

  In FIG. 1, the image forming apparatus GS includes an image forming apparatus main body GH and an image reading apparatus YS.

  The image forming apparatus main body GH is called a tandem type color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, a belt-like intermediate transfer member 6, a sheet feeding and conveying unit, and a fixing unit to be described later. Device 17.

  An image reading device YS including an automatic document feeder 301 and a document image scanning exposure device 302 is installed on the upper part of the image forming apparatus main body GH. The document D placed on the document table of the automatic document feeder 301 is transported by a transport unit, and an image on one or both sides of the document is scanned and exposed by the optical system of the document image scanning exposure device 302, and the line image sensor CCD is scanned. Is read. At this time, the document D conveyed from the document table is subjected to glossiness level detection sensor PKa used as a gloss level selection unit to determine the glossiness of the document image, monochrome and color of the document image, and double-sided image discrimination. Done.

  The analog signal photoelectrically converted by the line image sensor CCD is subjected to analog processing, A / D conversion, shading correction, image compression processing, etc. in the image processing unit, and once stored in the memory, the image writing unit (exposure means) ) Send signals to 3Y, 3M, 3C, 3K.

  The image forming unit 10Y that forms a yellow (Y) image includes a charging unit 2Y, an exposure unit 3Y, a developing device 4Y, and a cleaning unit 8Y disposed around a photosensitive drum 1Y as an image carrier. The image forming unit 10M that forms a magenta (M) color image includes a photosensitive drum 1M as an image carrier, a charging unit 2M, an exposure unit 3M, a developing device 4M, and a cleaning unit 8M. The image forming unit 10C that forms a cyan (C) image includes a photosensitive drum 1C as an image carrier, a charging unit 2C, an exposure unit 3C, a developing device 4C, and a cleaning unit 8C. The image forming unit 10K that forms a black (K) image includes a photosensitive drum 1K as an image carrier, a charging unit 2K, an exposure unit 3K, a developing device 4K, and a cleaning unit 8K. The charging unit 2Y and the exposure unit 3Y, the charging unit 2M and the exposure unit 3M, the charging unit 2C and the exposure unit 3C, and the charging unit 2K and the exposure unit 3K constitute a latent image forming unit.

  4Y, 4M, 4C, and 4K are developing devices that contain a two-component developer composed of a toner and a carrier having a small particle diameter for yellow (Y), magenta (M), cyan (C), and black (K).

  The intermediate transfer body 6 is wound around a plurality of rollers and is rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred (primary transfer) by the transfer means 7Y, 7M, 7C, and 7K onto the rotating intermediate transfer body 6 and synthesized. A color image is formed. The recording paper P as a transfer material accommodated in the paper feed cassette 20 is fed by the paper feed means 21 and is conveyed to the transfer means 7A via the paper feed rollers 22A, 22B, 22C, the registration rollers 23, etc. A color image is transferred onto the recording paper P (secondary transfer). The recording paper P to which the color image has been transferred is sandwiched by the fixing device 17, and the color toner image (or toner image) on the recording paper P is fixed by applying heat and pressure to the recording paper P. The sheet is fixed on the upper side, is sandwiched between the sheet discharge rollers 24 on the sheet discharge path side, and is placed on the sheet discharge tray 25 outside the apparatus.

  At the time of double-sided image formation, a color image (color toner image) is formed on one side (front surface), and the recording paper P discharged from the fixing device 17 is branched from the sheet discharge path by the branching unit 26 and is fed respectively. Through the lower circulating paper path 27A constituting the conveying means, the front and back are reversed by the reverse conveying path 27B which is a refeeding mechanism (ADU mechanism), and passes through the refeeding conveying section 27C to be fed by the feed roller. Merge at 22D. The recording paper P that has been reversely conveyed (circulated and reversed) is conveyed again to the secondary transfer roller 7A via the timing roller 23, and a color image (color toner image) is formed on the other side (back surface) of the recording paper P. Batch transfer. The recording paper P onto which the color image has been transferred is fixed by the fixing device 17 and is sandwiched between the paper discharge rollers 24 on the paper discharge path side and placed on a paper discharge tray 25 outside the apparatus.

  On the other hand, after the color image is transferred to the recording paper P by the transfer means 7A, the residual toner is removed by the cleaning means 8A from the intermediate transfer body 6 from which the recording paper P is separated by curvature.

  The fixing device according to the present invention will be described in detail with reference to FIGS. In addition, the same code | symbol is attached | subjected to the structure same as FIG. 1, and the description is abbreviate | omitted.

  A first embodiment will be described with reference to FIG.

  2A shows a toner image on the recording paper P while forming a fixing nip Na between the heating member 17a having an elastic layer and the pressure member 17b that pressurizes the heating member and has an elastic layer. 1 is a diagram showing an outline of a fixing device configured to fix and fix a toner. Further, an external heating member 17c is disposed in contact with the heating member 17a, and the heating member 17a, the pressure member 17b, and the external heating member 17c each have a roller shape. Arrows indicate the direction of rotation of each member.

  The heating member 17a is rotated by a fixing device driving unit supplied from a main motor 176a (not shown) of the main body of the image forming apparatus, and the pressure member 17b in pressure contact is driven to rotate.

  The external heating member 17c is driven by a driving source such as an external heating rotary motor (not shown) 176c, such as a pulse motor that controls the rotational speed by an independent transmission pulse number. A nip portion Nb is formed at the contact portion of the external heating member 17c and is rotated in the opposite direction.

  Here, an independent drive source such as a pulse motor is used to rotate the external heating member 17c. However, a mechanism that rotationally drives the fixing device drive unit using a gear train or a timing belt may be used.

  Here, the heating member 17a is provided with a cylindrical metal pipe 171a having a thickness of about 1 to 2 mm using, for example, an aluminum material as a base, and a silicon rubber layer 172a having a thickness of 1 to 3 mm on the outer peripheral surface of the metal pipe 171a. Further, it is configured as a roller member having an outer diameter of about 40 to 80 mm, in which a PFA (perfluoroalkoxy) coating 173a having a thickness of about 10 to 30 μm is formed on the outer peripheral surface of the silicon rubber layer 172a. It has a roller heater 174a. The silicon rubber layer has a rubber hardness of 5 to 15 degrees (JIS-A hardness meter), and a heating member temperature sensor 175a is provided in contact with or non-contact with the heating member 17a, thereby enabling temperature control of the heating member 17a. Yes.

  The pressure member 17b has a cylindrical metal pipe 171b having a thickness of about 2 to 5 mm using a steel material such as STKM (carbon steel pipe for mechanical structure) or an aluminum material, and a thickness on the outer peripheral surface of the metal pipe 171b. A silicon rubber layer 172b of 1 to 3 mm is provided, and a release layer 173b using a PFA (perfluoroalkoxy) tube having a thickness of about 20 to 50 μm outside the silicon rubber layer 172b. And a pressure roller heater 174b made of a halogen heater. The silicon rubber layer has a rubber hardness of 5 to 15 degrees (JIS-A hardness meter), and a pressure member temperature sensor 175b is provided in contact with or not in contact with the pressure member 17b to control the temperature of the pressure member 17b. It has become.

  The external heating member 17c includes a cylindrical metal pipe 171c having a thickness of about 1 to 2 mm using, for example, an aluminum material as a base, and PTFE (polytetrafluoroethylene) having a thickness of about 10 to 30 μm on the outer peripheral surface of the metal pipe 171c. ) It is configured as a roller portion having an outer diameter of about 25 to 40 mm and formed with a coating 173c, and has an external heating member heater 174c made of a halogen heater inside. In addition, an external heating member temperature sensor 175c is provided so as to be in contact with or non-contact with the external heating member 17c, and temperature control of the external heating member 17c is possible.

  The fixing device having such a configuration rotates in the reverse direction at the contact portion between the external heating member 17c and the heating member 17a, so that the high temperature portions on the external heating member 17c always come into contact with the heating member 17a one after another. In addition, since the heat can be efficiently supplied without depriving the temperature, the temperature drop can be reduced. By the way, in the follower type (the rotation direction of the external heating member 17c and the rotation direction of the heating member 17a rotate in the same direction), the contact portion of the heating member and the external heating member moves while contacting at the same place. Since heat continues to decrease during movement, heat supply is not efficiently performed.

  The control system of the image forming apparatus according to the present invention will be described below with reference to the block diagram of FIG.

  The image forming apparatus is controlled based on a control program stored in a ROM (not shown) by a CPU (not shown) which is a control means of the present invention. This is realized by cooperating with each configuration shown in FIG. The control system of the image forming apparatus according to the present invention includes a system control unit 101, a reading control unit 102, an image processing unit 103, a conveyance drive control unit 104, an image formation control unit 105, a display operation control unit 106, a memory 107, and a fixing control. Part 108.

  The system control unit 101 manages the entire control units of the image forming apparatus and performs requested image formation scheduling and the like.

  The reading control unit 102 controls the operation of the image reading device YS, the image processing unit 103 performs image processing, the transport driving control unit 104 controls the operation of the paper feeding / conveying means, and the image formation control unit 105 is an image forming unit. 10Y, 10M, 10C, and 10K and the operation of the intermediate transfer body 6 are controlled. The display operation control unit 106 controls display on the operation panel and reception of operation input, and the memory 107 stores image data and the like.

The fixing control unit 108 receives signals transmitted from various temperature sensors such as the pressure roller temperature sensor 175b, the heating roller temperature sensor 175a, and the external heating member temperature sensor 175c, and receives the pressure roller heater 174b, the heating roller heater 174a, and the external heating. The energization to various heaters such as the roller heater 174c is controlled. Further performing the speed ratio control as the external heating member 17c speed ratio V ₁ / V ₂ between the rotational linear velocity V ₁ and the rotation linear velocity V ₂ of the heating member 17a of the is 0.5 to 1.5.

The speed ratio controller 178 determines the linear velocity of the external heating member when the linear velocity v ₂ of the heating member 17a and the linear velocity V ₁ of the external heating member 17c are V ₁ / v ₂ ≦ 0.5. Advance V ₁ / v ₂ ≧ 1.5 Control is performed by changing the number of pulses transmitted by the external heating rotary motor 176c using a pulse motor so as to reduce the linear velocity of the external heating member.

  A second embodiment is shown in FIG.

  In the second embodiment, the fixing roller 17e, a heating member 17d having a heat source, a fixing belt 27 stretched between the fixing roller 17e and the heating member 17d, and the fixing roller 17e via the outer peripheral surface of the fixing belt 27 are used. A belt fixing device having a pressure member 17b that is pressed against the belt, and fixing the toner through a transfer material P carrying an unfixed toner image in a nip portion Nb formed by the fixing roller 17e and the pressure member 17b. This is a mechanism in which the member 17 c is disposed in pressure contact with the fixing belt 27.

  The fixing roller 17e is provided with a fixing device driving unit (not shown), and the fixing belt 27, the heating member 17d, and the pressure member 17b are driven to rotate by the rotation of the fixing device driving unit. The external heating member 17c is a fixing device supplied from an external heating rotation motor (not shown) 176c formed of a pulse motor or the like that controls the rotation speed by an independent number of transmitted pulses, or a main motor 176a (not shown) of the image forming apparatus main body. A nip portion Nb is formed between the rotation direction of the fixing belt 27 and the contact portion of the external heating member 17c by a gear train or a timing belt using the power of the drive unit, and is rotated in the opposite direction.

  Here, the fixing belt 27 uses a nickel electroformed belt having an inner diameter of about 100 to 150 mm and a thickness of about 20 to 80 μm as a base, or a heat resistant resin belt such as polyimide having a thickness of about 50 to 200 μm as a base. The outer surface (outer peripheral surface) of the substrate is coated with silicon rubber having a thickness of about 100 to 500 μm, and PFA (perfluoroalkoxy) or fluorine resin having a thickness of about 30 to 50 μm is applied to the surface as a release layer. Alternatively, the PFA tube is covered. The silicon rubber layer is preferable as a condition for obtaining good fixability and thermal responsiveness in a rubber hardness range of 20 to 40 degrees (JIS-A hardness meter).

  The fixing roller 17e includes a cylindrical metal pipe 171e having a thickness of about 2 to 5 mm using a steel material such as STKM (carbon steel pipe for mechanical structure), and a thickness of 5 to 15 mm on the outer peripheral surface of the metal pipe 171e. A silicon sponge layer 172e having a hardness of 25 to 35 degrees (Asker-C hardness meter) is provided, and is configured as a soft roller having an outer diameter of about 20 to 50 mm.

  In addition, since the control system and the external heating member 17c, the heating member 17a, and the pressurizing member 17b according to the second embodiment have substantially the same configuration as that of the first embodiment, description thereof is omitted.

  According to the second embodiment, in the belt fixing method, the heat source of the heating member can be provided at a position away from the pressure member. In addition, since the rubber thickness of the fixing roller can be increased, it is advantageous for image forming devices that print on both sides at high speed, and heat can be accumulated on a belt with a small heat capacity to increase the warm-up rise time. In addition, since a nip width wider than that of the roller fixing device can be formed, fixing can be performed at a temperature of about 160 ° C.

  The second embodiment in which the external heating member 17c is provided in such a belt fixing device can provide a fixing device that is particularly advantageous for a color image forming apparatus that requires high image quality at high speed.

A third embodiment will be described with reference to FIG.
In the third embodiment, the external heating means includes an external heating roller 17f having a heat source, an external support roller 17g, and an external belt 271 stretched between the external heating roller 17f and the external support roller 17g. The belt 271 is in contact with the roller-shaped heating member 17a. The rotation direction of the external belt 271 rotates in a direction opposite to the rotation direction of the heating member 17a at the contact portion between the heating member 17a and the external belt 271.

  The external support roller is composed of a cylindrical metal pipe having a thickness of about 2 to 5 mm using a steel material such as STKM (carbon steel pipe for mechanical structure) as the base, and the base has a thickness as a release layer on the surface. It has a configuration in which PFA (perfluoroalkoxy) of about 30 to 50 μm, fluorine resin, or the like is applied, or a PFA tube is covered.

  The external belt 271 has the same configuration as that of the fixing belt used in the second embodiment except that the inner diameter of the belt is 60 to 100 mm, and a description thereof will be omitted.

  The configuration of each member and the control means in the third embodiment are substantially the same as those in the first embodiment and the second embodiment, and thus description thereof is omitted.

  According to the third embodiment, since the nip width Nf between the external belt 271 and the heating unit 17a is wider than the roller shape, the heating member 17a is sufficiently supplied with heat from the external heating unit. It is possible to provide a fixing device in which the decrease is even smaller than in the first embodiment.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

The fixing device according to the first embodiment shown in FIG. 2A is mounted on the image forming apparatus shown in FIG. 1, and the control shown in FIG. 3 is performed to determine the linear velocity V ₁ of the heating member and the external heating member. the linear velocity ratio V ₁ / V ₂ of V ₂ measured the temperature drop when the continuously printed.
The measurement conditions are as follows.
Print test chart Konica Minolta standard color chart (printing rate 4%)
Paper passing test paper Konica Minolta copy paper NR-A80 A4 size Number of paper passes 100 paper passing direction The short side of the paper is parallel to the transfer material conveyance direction The linear velocity of the heating member 220 mm / second The linear velocity of the external heating member 110, 220, 260, 300 mm / sec level The configuration of the fixing device is as follows.
Heating member: outer diameter 65 mm
Base material Carbon steel pipe for machine structure
Base thickness 2mm
Outer diameter of substrate 62mm
Elastic layer thickness 1.5mm
Elastic layer material Silicon rubber (hardness JIS-A 10 degrees)
0.03mm PFA tube coated external heating member: outer diameter 30mm
Base material Aluminum pipe PTFE coating thickness 10μm
Base thickness 2mm
Pressure member: outer diameter 55mm
Base material Carbon steel pipe for machine structure
Base thickness 2mm
Outer diameter of base 53mm
Elastic layer thickness 1mm
Elastic layer material Silicon rubber (hardness JIS-A 10 degrees)
0.03 mm PFA tube coating system speed: 300 mm / second Nip pressure contact force between heating member and pressure member: 1000 N
Nip pressure contact force between heating member and external heating member: 50N
Setting temperature: Heating member 200 ° C
Pressure member 180 ° C
External heating member 210 ° C
The results of the above examples are shown in Table 1.

In the table, the driven type indicates that the rotation of the external heating member is driven by the rotation of the heating member.

From the measurement results, the temperature drop when the linear velocity ratio V ₁ / V ₂ is 0.5 or less and the paper is continuously passed is equal to that of the driven type.
When the linear speed ratio is in the range of 1.0 to 1.5, the temperature drop is small.
Almost no change when the linear speed ratio is 1.5 or more.

As described above, in the contact portion between the external heating member and the heating member, the rotational directions of both members are opposite to each other, and the linear speed ratio V ₁ / of the rotational linear velocity V ₁ of the external heating member and the rotational linear velocity V ₂ of the heating member. It has been clarified that the decrease in fixing temperature can be reduced when V ₂ is in the range of 0.5 to 1.5.

1 is a schematic cross-sectional configuration diagram of an image forming apparatus including a fixing device according to the present invention. FIG. 2A is a schematic cross-sectional view of the fixing device according to the present invention in which the heating member, the pressure member, and the external heating member are rollers, and FIG. 2B is the belt fixing device, and the external heating member is a roller shape. FIG. 2C is a schematic cross-sectional view of the fixing device when the external heating member uses belt means in the roller fixing device. 2 is a block diagram illustrating a control system of the image forming apparatus according to the present invention. FIG.

Explanation of symbols

1Y, 1M, 1C, 1K Photosensitive drum 2Y, 2M, 2C, 2K Charging unit 3Y, 3M, 3C, 3K Exposure unit 4Y, 4M, 4C, 4K Developing device 101 System control unit 102 Reading control unit 103 Image processing unit 104 Conveyance drive control unit 105 Image formation control unit 106 Display operation control unit 107 Memory 108 Fixing control unit 17 Fixing device 17a Fixing roller 17b Pressure roller 17C Heating roller 174a Heating heater 174b Pressure roller heater 174c External heating roller heater 175a Heating member temperature sensor 175b Pressure member temperature sensor 175c External heating member temperature sensor 178 Speed ratio control unit

Claims (6)

The transfer material carrying the unfixed toner image is nipped and conveyed to a nip formed by a heating member that contacts and heats the unfixed toner image while moving endlessly, and a pressure member that presses the heating member. In the fixing device for fixing,
An external heating member that contacts the contact surface of the heating member with the unfixed toner image while moving endlessly and that heats the heating member;
An endless movement direction of the external heating member is a direction opposite to the endless movement direction of the heating member at a contact portion between the heating member and the external heating member. The fixing device according to claim 1, wherein the heating member and the pressure member are rollers having an elastic layer. The heating member includes a fixing roller, a heating roller having a heat source, the fixing roller and a fixing belt stretched around the heating roller,
The fixing device according to claim 1, wherein the pressure member is in pressure contact with the fixing roller via an outer peripheral surface of the fixing belt. The fixing device according to claim 1, wherein the external heating member is a roller. The external heating member includes an external heating roller having a heat source, an external support roller, and an external belt stretched between the external heating roller and the external support roller,
The fixing device according to claim 1, wherein the heating member is in contact with an external belt heating unit via an outer peripheral surface of the external belt. Claim, characterized in that it comprises a control means for the speed ratio V ₁ / V ₂ between the rotational linear velocity V ₂ of the heating member and the linear velocity V ₁ of the said external heating member is controlled to 0.5 to 1.5 The fixing device according to any one of 1 to 5.

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