JP2009271434A - Heating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating device, capable of attaining both reduction in energy consumption and reduction in temperature rise of a non-passing area in which a narrow heating object material is not passed. <P>SOLUTION: In the heating device configured to impart thermal energy to a heating object material by passing the material through a pressure nip part between a heating means and a pressure roller 30, the pressure roller 30 includes a cylindrical core shaft part 31, an elastic part 32 laminated on the outer surface of the core shaft part 31, and a radiation part 33 bonded to a shaft end portion of the core shaft part 31. The radiation part 33 has an overlap area A partially overlapping with the inside part of a maximum width size passing area NO where a heating object material of maximum width size is passed through the pressure nip part N from an end portion in a direction orthogonal to the passing direction of the maximum width size passing area NO; and an end exposing area B exposed to the space outside the elastic part 32. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is suitable for a fixing device that heats and fixes an unfixed image formed on a recording material such as a copying machine or a laser beam printer, or a glossing device that gives gloss to a recording material on which an image is recorded. Relates to the device.

  As a conventional heating device, for example, in an image heating device for heat fixing of an image, a recording material as a material to be heated by a heating roller maintained at a predetermined temperature and a pressure roller pressed against the heating roller A heat roller system that heats while sandwiching and transporting is widely used. In addition, various systems and configurations such as a flash heating system, an open heating system, and a hot plate heating system are known and put into practical use.

  Recently, in place of such a system, a heater, a heater support, a heat-resistant fixing film that slides in contact with the heater, and a pressure member that causes the recording material to adhere to the heater via the fixing film Has been devised. This is to heat-fix an unfixed image formed and supported on a recording material surface by applying the heat energy of a heater to the recording material through a fixing film (for example, Patent Document 1, Patent Document 1). 2).

  As a heater of this image heating apparatus, generally, a heating element is formed on a ceramic substrate, the heating element is heated by power feeding, and the recording material is heated. The temperature of the heating member is detected by a temperature measuring element such as a thermistor in contact with or bonded to the heating member, and the temperature is controlled by the CPU based on the detected temperature so as to be a predetermined temperature.

In such a film heating type image heating apparatus, a low heat capacity heater can be used as a heating member. For this reason, it is possible to save power and shorten the wait time (quick start) as compared with conventional devices such as a heat roller method and a belt heating method.
JP-A-4-44075 JP-A-4-204980

  However, recent image heating apparatuses have increased processing speed, so that the image heating apparatus needs to heat a large number of recording materials in a fixed time, and the thermal energy applied to the recording materials is increasing. As the speed increases, the size of the image heating device increases, and the energy required to maintain the constant temperature is increased while the temperature of the image heating device is increased to the required temperature. In view of such a situation, it is necessary to reduce energy consumed in the image heating apparatus.

  On the other hand, with the increase in speed, the problem that the temperature of the non-passage area of the recording material rises becomes more prominent. The heating area of the heater is set to correspond to the maximum width size passing area of the maximum width recording material, but the maximum width recording material is not always used, and the recording width is smaller than the maximum width. The material is used frequently. When a recording material having a small width is used, a recording material non-passing region is generated at the end of the heat generation region of the heater. In the recording material passage area, the thermal energy generated from the heater is consumed by the recording material, but in the non-passing area, there is no consumption of thermal energy by the recording material.

Therefore, the heat energy generated from the heater is gradually accumulated, and the temperature of the member in the non-passage area of the recording material in the press nip portion is generated. Due to the recent increase in the speed of image heating devices, the supply of recording material in a certain period of time will increase, so the temperature rise in the heat generation area of the heater that faces the pressure nip and the area that faces the non-passing area of the narrow recording material Tend to grow.

  Such a temperature rise in the non-passing area of the recording material requires the improvement of the heat resistance of the member used in that area, and the need to improve the stability of the performance of the member in a high temperature state. There is. For this reason, a countermeasure for reducing the temperature of the non-passing area of the recording material is desired.

  The present invention has been made in view of such circumstances, and the object of the present invention is to achieve both reduction in energy consumption and reduction in temperature rise in a non-passing region of a material to be heated having a width smaller than that of the material to be heated having a maximum width size. It is in providing the heating apparatus which can do.

  In order to achieve the above object, the invention according to the present application includes a heating unit and a pressurizing unit that forms a press-contact nip portion between the heating unit and passing the material to be heated through the press-contact nip portion. In the heating device for applying thermal energy, the pressurizing means includes a cylindrical core shaft portion, an elastic portion having rubber-like elasticity laminated on an outer surface of the core shaft portion, and a shaft end portion of the core shaft portion. The heat radiating part joined to the core shaft part has a direction perpendicular to the passing direction of the maximum width size passing region through which the heated material of the maximum width size passes through the pressure nip part. It has the structure which has the area | region which overlaps with the inner part of the maximum width size passage area | region from an edge part, and the edge part exposure area | region exposed to the space outside an elastic part, It is characterized by the above-mentioned.

  According to the present invention, it is possible to reduce energy consumption by reducing the heat capacity of the pressurizing means, and to reduce the temperature rise in the non-passing region of the heated material in the maximum width size passing region. it can.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described in detail below based on the illustrated embodiment. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

  FIG. 2 is a schematic configuration diagram showing a basic configuration of a heat fixing device as a heating device according to the first embodiment of the present invention.

<Basic configuration>
That is, the heat fixing apparatus 1 includes a film heating mechanism 20 as a heating unit, and a pressure roller 30 as a pressure unit that forms a pressure nip N with the film heating mechanism 20. Then, the recording material as the material to be heated is passed through the pressure nip N between the film heating mechanism 20 and the pressure roller 30 to give thermal energy.

  The film heating mechanism 20 and the pressure roller 30 extend parallel to each other in a direction orthogonal to the passing direction of the recording material passing through the press nip portion N, and are longer in the orthogonal direction than the passing direction of the recording material. Hereinafter, the longitudinal direction of the heat fixing device 1 in this specification is synonymous with the direction orthogonal to the passing direction of the recording material P.

The film heating mechanism 20 includes a fixing film 21 as a flexible sleeve and a heater 22 that comes into contact with the fixing film 21, and the pressure roller 30 is pressed against the heater 22 via the fixing film 21. N is formed. The fixing film 21 rotates with the pressure roller 30 and slides with the heater 22.

  The heat fixing device 1 is a tensionless film heating method, and an endless belt-shaped or cylindrical heat-resistant film is used for the fixing film 21. The circumferential length of the fixing film 21 is set so that at least a part thereof is always in a tension-free state (a state in which no tension is applied), and is configured to be rotationally driven by the rotational driving force of the pressure roller 30.

  The fixing film 21 is fitted on a stay 23 as a heater holding member / film guide member. The inner peripheral length of the endless fixing film 21 and the outer peripheral length of the stay 23 including the heater 22 are larger in the fixing film 21 by, for example, about 3 mm. The fixing film 21 is externally fitted to the stay 23 with a margin in circumference.

  The fixing film 21 can be a single layer film such as PTFE, PFA or FEP having a heat resistance of 100 μm or less, preferably 80 μm or less and 40 μm or more in order to reduce the heat capacity and improve the quick start property. . Moreover, the composite layer film which coat | covered PTFE, PFA, FEP etc. on the outer peripheral surface of films, such as a polyimide, a polyamideimide, PEEK, PES, PPS, can be used.

  This film is preferably a laminated film in which a fluororesin layer is laminated on a polyimide sleeve in a monochrome machine, and a laminated film in which a fluororesin layer is coated on a polyimide sleeve via a rubber layer in a color machine.

  A stainless steel sleeve may be used instead of the film. In a monochrome machine, a laminate in which a fluororesin layer is laminated on a stainless steel sleeve, and in a color machine, a laminate in which a fluororesin layer is laminated on a stainless steel sleeve via a rubber layer can be used.

  In this example, a polyimide film having a film thickness of about 50 μm coated with PTFE on the outer peripheral surface was used. The outer diameter of the fixing film 21 was 18 mm.

  The heater 22 is a ceramic heater and is disposed on the lower surface of the stay 23 along the longitudinal direction of the stay 23 and is held by the stay 23.

  The stay 23 is a heat resistant and rigid member. The material of the stay 23 can be composed of a high heat resistant resin such as polyimide, polyamideimide, PEEK, PPS, or liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass, or the like. In this embodiment, a liquid crystal polymer is used.

  The pressure roller 30 forms a pressure nip N with the fixing film 21 sandwiched between the heater 22 and the outer surface of the fixing film 21 so as to rotate the fixing film 21. The configuration of the pressure roller 30 includes a hollow cylindrical metal core shaft portion 31 having a predetermined thickness and an elastic portion 32 including a rubber-like elastic body formed on the outer surface of the core shaft portion 31. Have.

  A release layer such as a fluororesin is provided on the outermost layer of the elastic portion 32, and is pressed against the surface of the heater 22 with a predetermined pressing force by a bearing means, a biasing means, etc. (not shown) with the fixing film 21 interposed therebetween. Configured to be

In the present embodiment, a cylindrical SUS sleeve having a predetermined thickness was used for the core shaft portion 31, silicone rubber was used for the elastic portion 32, and a PFA tube having a thickness of about 50 μm was used for the release layer. The outer diameter of the pressure roller 30 was 20 mm, and the thickness of the elastic layer was 3 mm.

  The pressure roller 30 is rotationally driven at a predetermined peripheral speed in the direction of the arrow by a drive system (not shown). Due to the rotational drive of the pressure roller 30, a rotational force acts on the fixing film 21 by the frictional force between the pressure roller 30 and the film outer surface of the fixing film 21 in the pressure nip N. The inner surface of the fixing film 21 is in close contact with the surface of the heater 22 at the pressure nip portion N, and the outer peripheral speed of the stay 23 while sliding is approximately the same as the peripheral speed of the pressure roller 30 as indicated by the arrow. It becomes a driven rotation state.

<Heater configuration>
Next, the configuration of the heater 22 will be described in more detail with reference to FIG.
FIG. 1 is a longitudinal arrangement view of the pressure roller 30 and the heater 22. The heater 22 shows the configuration of the surface on which the heating element 24 of the film sliding surface is formed, and the pressure roller 30 shows the cross-sectional configuration in the longitudinal direction.
The heater 22 has an elongated heat-resistant, insulating, and heat-conductive substrate 25 whose longitudinal direction is perpendicular to the passing direction of the pressure nip N of the recording material P. A heating element 24 formed along the length of the substrate 2 is provided on the surface (film sliding surface) side of the substrate 25. The heating element 24 is a resistance heating element, and the longitudinal region of the heating element 24 becomes the heating region of the heater 22. In addition, a heat-resistant overcoat layer that protects the surface of the heater 22 on which the heat generating element 24 is formed, power supply electrodes 27 and 28 disposed at the longitudinal ends of the heat generating element 24, and the like have a low heat capacity as a whole. It is a heater.

  The heater 22 of this example was obtained by forming a paste prepared by kneading silver, palladium, glass powder (inorganic binder), and organic binder on the substrate 25 by screen printing to form a line band. Is.

  As a material for the heating element 24, an electric resistance material such as RuO 2 or Ta 2 N may be used in addition to silver palladium (Ag / Pd). The resistance value of the heating element 24 was 18Ω at room temperature.

  The substrate 25 has heat resistance and insulating properties, and for example, a ceramic material such as alumina or aluminum nitride is used. In this embodiment, an alumina substrate having a width of 7 mm, a length of 270 mm, and a thickness of 1 mm is used. The power feeding electrodes 27 and 28 used a screen printing pattern of silver palladium.

  In FIG. 2, reference numeral 26 denotes a temperature measuring element provided for detecting the temperature of the heater 22. In this embodiment, an external contact type thermistor separated from the heater 22 is used as the temperature measuring element 26. For example, the temperature measuring element 26 is provided with a heat insulating layer on a support, and a chip thermistor element is fixed thereon, and the element is directed downward (on the back side of the heater 22) with a predetermined pressure to contact the back surface of the heater 22. The structure that touches. In this example, a highly heat-resistant liquid crystal polymer was used as the support, and ceramic paper was laminated as the heat insulating layer. A temperature measuring element 26 made of an external contact type thermistor is provided in the minimum passage region of the recording material and communicates with a CPU (not shown).

  The surface of the heater 22 on which the overcoat layer is formed is exposed downward, and is held and fixed on the lower surface side of the stay 23. By adopting the above configuration, the entire heater 22 can have a lower heat capacity than that of the heat roller system, and a quick start is possible.

  The heater 22 rises in temperature when the heating element 24 generates heat over the entire length by feeding power to the feeding electrodes 27 and 28 at the longitudinal ends of the heating element 24. The temperature rise is detected by the temperature sensing element 26, and the output of the temperature sensing element 26 is A / D converted and taken into the CPU. Based on the acquired information, the electric power supplied to the heating element 24 by the triac is controlled by phase control or wave number control, and the temperature control of the heater 22 is performed.

  That is, the heater 22 is controlled by controlling energization so that the heater 22 is heated when the temperature detected by the temperature detecting element 26 composed of an external contact type thermistor is lower than a predetermined set temperature, and is lowered when the temperature is higher than the set temperature. Is kept at a constant temperature during fixing. In this embodiment, the output is changed in 21 steps from 5 to 100% from 0 to 100% by phase control.

  The pressure contact formed by the heater 22 and the pressure roller 30 with the fixing film 21 sandwiched in a state where the temperature of the heater 22 rises to a predetermined level and the rotational peripheral speed of the fixing film 21 is steady due to the rotation of the pressure roller 30. The recording material P is introduced into the nip portion N. On the recording material P, an unfixed image of toner is formed at the transfer portion.

  Then, the recording material P is nipped and conveyed together with the fixing film 21 through the pressure nip portion N, so that the heat energy of the heater 22 is applied to the recording material P through the fixing film 21 and unfixed on the recording material P. A visible image (toner image) is heat-fixed on the recording material P surface. The recording material P that has passed through the pressure nip N is separated from the surface of the fixing film 21 and conveyed.

Subsequently, characteristic portions of the present embodiment will be described with reference to FIG.
<Configuration of the pressure roller 30>
The pressure roller 30 used in the first embodiment includes a cylindrical core shaft portion 31, an elastic portion 32 having a rubber-like elastic body laminated on the outer surface of the core shaft portion 31, and a shaft end of the core shaft portion 31. It is the structure provided with the edge part flange member 33 as a thermal radiation part joined to the part. The end flange member 33 is described as a solid cylindrical shaft in the illustrated example, but it is not necessary to be such a shaft member.

  As a specific example, for example, a sponge silicone rubber elastic body is used for the elastic portion 32, and a hollow cylindrical SUS material having an outer diameter of 14 mm, a thickness of 2 mm, and an inner diameter of 10 mm is used for the core shaft portion 31. The end flange member 33 that is a heat radiating portion is made of, for example, an aluminum material having an outer diameter of 10 mm.

<Position relationship in the longitudinal direction of the heat fixing device>
FIG. 3 is a cross-sectional view in the longitudinal direction of the heat fixing apparatus of this embodiment. FIG. 9 is a diagram schematically showing the characteristic part of the present invention.
In the heater 22, a heating element 24 is formed on an alumina substrate 25 having a longitudinal width L1 (270 mm) over a longitudinal width L2 (216 mm). The longitudinal width L2 of the heating element 24 is the same as the range of the maximum width size passage region N0 through which the maximum width recording material P0 used in the heat fixing apparatus of this embodiment passes the press nip portion N. The entire lengthwise direction of the heating element 24 is a heating area 24A, and the range of the maximum width size passing area N0 of the recording material P0 having the maximum width (W0) is the heating area 24A.

  That is, the width and position of the maximum width size passage region N0 and the heat generation region 24A in the apparatus longitudinal direction, which is a direction orthogonal to the recording material passage direction, are the same. In this example, the maximum width recording material P0 is the LTR size, and the maximum width size passage region N0 is equivalent to the width 216 mm of the LTR size.

The pressure roller 30 is formed of an elastic portion 32 having the same longitudinal width as the cylindrical core shaft portion 31 having a longitudinal width L3 (240 mm). The heating element 24 and the pressure roller 30 of the heater 22 are illustrated in the drawing. Are equally arranged in the longitudinal direction with respect to the central reference line X. Therefore, both end portions of the elastic portion 32 of the pressure roller 30 are disposed so as to be 10 mm longer on both the left and right with respect to the longitudinal end portion of the heating element 24 of the heater 22.

  The end flange member 33 that is a heat radiating portion has a cylindrical shape, and one end thereof is closely fitted to the inner periphery of the core shaft portion 31. This fitting portion has an overlap region A that partially overlaps the heat generating body longitudinal region 24 </ b> A beyond the longitudinal end of the heat generating member 24. This overlap area A is an area shared with the heating element 24 in the longitudinal direction.

  Further, the end flange member 33 protrudes by a predetermined amount with respect to the longitudinal end 32 e of the elastic portion 32, and has an end exposed region B exposed to the space outside the elastic portion 32. In the first embodiment, for example, the overlap area A is set to a width of 3 mm, and the end exposed area B is set to a width of 15 mm.

Next, the relationship with the sheet passing position of the recording material P will be further described with reference to FIGS.
FIG. 1 is a view showing the positional relationship in the longitudinal direction of the passage positions of the heater 22, the pressure roller 30 as a pressure body, the recording material P0 having the maximum width and the recording material P1 having the small width (W1). As a recording material having the maximum width and the small width, for example, a combination of LTR size and A4 size is typical.

  The recording material conveyance position, the heating element 24 of the heater 22, and the elastic portion 32 of the pressure roller are equally arranged in the left-right direction with respect to the center reference line X in the drawing. Therefore, when the recording material P0 having the maximum width of the heat fixing device (for example, a recording material of LTR size having a longitudinal width of 216 mm) is passed, the entire range of the longitudinal width region of the heating element 24 passes through the maximum width size of the recording material P0. Region N0 is entered.

  The end flange member 33 extends from the end in the direction orthogonal to the maximum width size passage region N0 of the maximum width recording material P0 passing through the press-contact nip portion N to the inner portion and part of the maximum width size passage region N0. It has overlapping areas. The width and position in the apparatus longitudinal direction of the maximum width size passage area N0 and the heat generation area 24A are the same. Therefore, a region that partially overlaps the inner portion of the maximum width size passage region N0 is the same as the overlap region A of the heater 22 with the heating element 24.

  However, the maximum width size passage region N0 and the longitudinal width L2 of the heating element 24 of the heater 22 do not have to coincide with each other. For example, the longitudinal width L2 of the heating element 24 may be larger than the maximum width size passage region N0. .

On the other hand, when a small width recording material P1 (for example, an A4 size recording material having a longitudinal width of 210 mm) is passed, the result is as shown in FIG. That is, a non-passage area N2 that does not pass through the maximum width size passage area N0 is generated at both ends in the direction orthogonal to the passage direction of the narrow width passage area N1 of the narrow recording material P1 that passes through the pressure nip portion N. In the case of the LTR size and the A4 size, the left and right 3 mm regions are non-passing regions N2.
In this embodiment, when the overlap region A of the end flange member 33 of the pressure roller 30 passes a small width recording material P1, the small width recording material P1 passes through the maximum width size passage region N0. It is arranged so as to correspond to the non-passing area N2.

<Measurement of pressure roller surface temperature of non-sheet passing part>
As described above, when the recording material P1 of A4 size or the like having a width smaller than the recording material P0 of the maximum width LTR size or the like is passed, the longitudinal end of the heating element 24 of the heater 22 becomes the non-passing region N2 and is pressurized. The surface temperature of the roller 30 rises.

  Next, in the heat fixing device using the pressure roller 30 having the configuration of the first embodiment and the heat fixing device using the pressure roller shown in FIG. The comparison of the pressure roller surface temperature in the non-passing area | region in the case of doing is shown.

The configuration of the pressure roller of FIG. 7 shown as Comparative Example 1 will be described below.
In this comparative example 1, the pressure roller 400 has the same material and configuration as the pressure roller 30 shown in FIG.
The end flange member 403 is joined to the core shaft portion 401 at a position outside the longitudinal width L2 of the heating element 24 of the heater 22, and the core shaft portion 401 of the pressure roller 400 corresponding to the longitudinal width region of the heating element 24. Is a hollow structure throughout the entire area.

FIG. 4 shows the temperature measurement result of the non-sheet passing portion. The measurement conditions are as follows.
The process speed was 150 mm / s, the temperature of the heater was controlled at 195 ° C., and 100 sheets of A4 size (width 210 mm) basis weight 128 g were continuously fed as recording materials at intervals of 25 ppm. The temperature measurement in the non-sheet passing area is the temperature of the pressure roller 30 surface corresponding to the longitudinal intermediate position A0 of the overlap area A in FIG.

As shown in FIG. 7, in the pressure roller 400 of Comparative Example 1, the pressure roller surface temperature reaches 227 ° C.
On the other hand, in the pressure roller 30 of the first embodiment, the pressure roller surface temperature is 216 ° C., and the pressure roller surface temperature in the non-passing region is lower than that of the pressure roller of the first comparative example. That is, in the configuration of the pressure roller 30 according to the first embodiment, it is possible to suppress the temperature rise in the non-passing region.
As described above, when an A4 size recording material is passed, the heat generated from the heating element 24 in the non-passing area is accumulated in the heater 22 and the pressure roller 30 so as not to be taken away by the recording material.

  In the pressure roller 30 of this embodiment, the accumulated heat is transmitted from the overlap region A to the end flange member 33 through the elastic shaft 32 and the core shaft portion 31. The heat transmitted to the end flange member 33 is transmitted in the longitudinal end direction, and is radiated from the end exposed region B exposed from the elastic portion 32 to the outside air.

  In the pressure roller 400 of Comparative Example 1, the heat generated in the non-sheet passing portion is transmitted from the elastic portion 402 to the core shaft portion 401. However, since the core shaft portion 401 is thin, the heat capacity is small and is interrupted. Less heat is transferred in the longitudinal direction due to the small area. Therefore, the heat of the elastic part 402 of the pressure roller 400 in the non-passing area N2 is accumulated, and the temperature of the pressure roller 400 rises.

  As described above, according to the pressure roller 30 of the first embodiment, it is possible to reduce the heat energy accumulated in the non-passing region N2 and to reduce the pressure roller 30 temperature.

  <Power consumption>

  Next, the heat fixing device using the pressure roller 30 shown in FIG. 1 which is the configuration of the first embodiment, the pressure roller 400 of the comparative example 1, and the addition according to the comparative example 2 shown in FIG. A comparison of power consumption when an LTR size recording material is continuously fed using the pressure roller 500 is shown.

First, the configuration of the pressure roller 500 shown in FIG.
Regarding the pressure roller 500, the elastic portion 502 has the same material and configuration as the elastic portion 32 of the pressure roller 30 shown in FIG. 1, but the core shaft portion 401 has a solid configuration. The core shaft portion 401 is made of aluminum and has an outer diameter of 14 mm.

Table 1 shows the power consumption measurement results.
The measurement conditions are as follows. The process speed was 150 mm / s, the temperature of the heater was controlled at 195 ° C., and the average power consumption was measured when 100 sheets of LTR size (width 216 mm) basis weight 75 g paper was continuously fed at 25 ppm intervals. .

  In the pressure roller 30 according to the first exemplary embodiment, the power consumption at the time of paper feeding is reduced by making the core shaft portion 31 have a lower heat capacity compared to the pressure roller 500 using the solid core shaft portion 501 in FIG. Can be reduced. Further, the power consumption was almost the same as that of the pressure roller 400 having the entire heating element longitudinal width shown in FIG.

  As described above, in the heat fixing device of the first embodiment, the core shaft portion 31 of the pressure roller 30 has a cylindrical hollow structure, so that the heat capacity is reduced and the power consumption of the heat fixing device can be reduced. did it.

Next, a second embodiment of the present invention will be described with reference to FIG.
The second embodiment is different from the first embodiment only in the configuration of the pressure roller, and the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
<Configuration of pressure roller 230>

  FIG. 5 is a diagram illustrating a longitudinal positional relationship between the heater 22 of the film heating mechanism 20 and the pressure roller 230 as a pressure member in the second embodiment. The heater 22 has a configuration of a surface on which a heating element 24 of a film sliding surface is formed, and the pressure roller 230 is a diagram showing a cross-sectional configuration in the longitudinal direction.

  The pressure roller 230 of the second embodiment also has a cylindrical core shaft portion 31, an elastic portion 32 having a rubber-like elastic body laminated on the outer surface of the core shaft portion 31, and a shaft end portion of the core shaft portion 31. It is the structure provided with the edge part flange member 233 as a joined thermal radiation part. In the second embodiment, the end flange member 233 is provided with a heat dissipating collar portion 235 having an enlarged cross-sectional area in the middle portion of the cylindrical portion 234.

The core shaft portion 31 and the elastic portion 32 are exactly the same as those in the first embodiment, the end flange member 233 that is a heat radiating portion is made of aluminum, and the outer diameter of the cylindrical portion 234 is 10 mm. The width C of the heat dissipating collar portion 235 has a larger cross-sectional area than the joint portion of the end flange member 233 with the core shaft portion 31, and the heat dissipating collar portion 235 has an outer diameter of 18 mm and a width C of 5 mm.
The end flange member 233 has an end exposed region B that protrudes outward with respect to the longitudinal end 32 e of the elastic portion 32 and is exposed to a space outside the elastic portion 32. Also in the second embodiment, the overlap area A is set to a width of 3 mm, and the end exposed area B is set to a width of 15 mm. The heat-dissipating collar 235 is provided in the end-exposed region B as a portion having a larger cross-sectional area than the joining region.

<Measurement of pressure roller surface temperature of non-sheet passing part>
As described above, when an A4 size recording material is passed, the longitudinal region end 24e of the heating element 24 of the heater 22 becomes a non-passing region, and the surface temperature of the pressure roller 230 increases.

  Next, a heat-fixing device using the pressure roller 230 having the configuration of the second embodiment, the pressure roller 400 of the first comparative example shown in FIG. 7, and the pressure roller 30 of the first embodiment shown in FIG. A comparison of the pressure roller surface temperature in the non-passing region is shown for the heat fixing device using the. As the recording material, A4 size recording material was passed.

FIG. 6 shows the temperature measurement result in the non-passing region. The measurement conditions are as follows.
The process speed was 150 mm / s, the heater 22 was temperature controlled at 195 ° C., and the recording material P was 100 sheets of A4 size (width 210 mm) and basis weight 128 g continuously fed at 25 ppm intervals. The temperature measurement in the non-passing area is the temperature of the surface of the pressure roller 230 corresponding to the longitudinal intermediate position A0 of the overlapping area A in FIG.

  As shown in FIG. 6, in the pressure roller 400 of Comparative Example 1, the pressure roller surface temperature reaches 227 ° C. On the other hand, in the pressure roller 30 of the first embodiment, the pressure roller surface temperature is 216 ° C. Further, in the pressure roller 230 of the second embodiment, the pressure roller surface temperature is 203 ° C.

  As described above, the pressure roller 230 of the second embodiment has a lower pressure roller surface temperature in the non-passing region than the pressure roller 400 of the first comparative example and the pressure roller 30 of the first embodiment. That is, in the configuration of the pressure roller 230 of the second embodiment, it is possible to suppress the temperature rise in the non-passing region.

  Also in the pressure roller 230 of the second embodiment, the accumulated heat is transmitted from the elastic portion 32 through the core shaft portion 31 to the end flange member 233 in the overlap region A. The heat transmitted to the end flange member 233 is transmitted in the longitudinal end direction, and is radiated from the end portion exposed region B of the end flange member 33 exposed from the elastic portion 32 to the outside air.

  In the pressure roller 230 according to the second embodiment, the heat dissipating collar 235 has a larger cross-sectional area than the joining region of the end flange member 233 and the core shaft portion 31. Therefore, the heat dissipation in the heat dissipation collar 235 is large, and the temperature drop in the non-passing region can be further increased.

As described above, in the heat fixing apparatus having the configuration of the second embodiment, the core shaft portion 31 of the pressure roller 230 has a cylindrical hollow structure to reduce the heat capacity, and the power consumption of the heat fixing apparatus. Can be reduced.
Further, the end flange member 233 that is a heat radiating portion has an overlap region A that is a region shared in the longitudinal direction with the heating element 24 of the heater 22, and an end exposed region that is exposed to the outside of the elastic portion 32. B. Therefore, the thermal energy of the non-passing area when the A4 size recording material is passed is transmitted to the end flange member 233, and from the end exposed area B of the end flange member 233 exposed from the elastic portion 32 to the outside. It can dissipate heat to the air.

  In particular, the heat dissipating collar 235 has a larger cross-sectional area than the overlap region A of the end flange member 233, so that the heat dissipating efficiency in the heat dissipating collar 235 is high and the temperature drop in the non-passing region is further increased. Can do. Therefore, the temperature rise in the non-passing region can be reduced.

In this embodiment, the shape of the heat dissipating collar portion 235 of the end flange member 233 is a disc shape. However, it is needless to say that a fin shape or the like is effective as long as the heat dissipating area can be increased. Nor.

<Other examples>
In the first and second embodiments, the position and width of the overlap region in the apparatus longitudinal direction and the non-passing region N2 are made to coincide with each other. In some cases, the overlap region may be larger than the non-passing region N2.

  Further, the case where two types of recording materials of the maximum width size and the small width size are heated has been described as an example, but the present invention can also be applied to the case where recording materials having three or more width sizes are heated. In that case, among the recording materials having a size smaller than the maximum width size, the recording material may be matched with the non-passing area of the recording material that is most frequently used, or may be matched with the minimum width size. In some cases, it may be adjusted to an intermediate position between the maximum width size and the minimum width size.

  In each of the above embodiments, the case where the recording material is conveyed with the center reference has been described. However, in the present invention, the recording material is passed with reference to one end portion in the direction orthogonal to the passing direction of the press-contact nip portion. Of course, the present invention can also be applied to a case where the paper is conveyed on a one-side basis such as paper. In that case, the non-passing area through which the recording material of a small width does not pass is only on one side, so the overlap area of the heat radiating part joined to the core shaft part of the pressure roller need only be provided on one side.

  Further, in each of the above-described embodiments, the case where the film heating mechanism of the ceramic heater is applied as the heat source has been described. However, the present invention is not limited to this. For example, a halogen heater type heat fixing device or an induction heating type heat fixing device can also be applied as a heat source.

  In addition, the heating device of the present invention is not limited to the heat fixing device described in the first and second embodiments, but is a gloss applicator that heats a recording material on which an image is formed to give gloss, or an image. Regardless, the present invention can be widely applied to an apparatus that heats a material to be heated through a pressure nip portion.

FIG. 3 is a longitudinal arrangement diagram of pressure rollers of a heat fixing device according to a first embodiment of the present invention. 1 is a schematic configuration diagram of a heat fixing apparatus according to Embodiment 1 of the present invention. 1 is a longitudinal sectional view of a heat fixing device according to Embodiment 1 of the present invention. FIG. 6 is a diagram illustrating a relationship between the number of sheets passing through the pressure roller and the temperature according to the first embodiment of the invention. (A) is a longitudinal view of a pressure roller according to a second embodiment of the present invention, (B) is a front view of an end flange member, and (C) is a side view of (B). The figure which shows the relationship between the number of sheets of the pressure roller which concerns on Example 2 of this invention, and temperature. FIG. 6 is a longitudinal arrangement diagram of pressure rollers of a heat fixing device according to Comparative Example 1; FIG. 6 is a longitudinal arrangement diagram of pressure rollers of a heat fixing device according to Comparative Example 2; The figure which showed the characteristic part of this invention typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 20 Film heating mechanism 21 Fixing film 22 Heater 23 Stay 24 Heat generating body 24A Heat generating area 24A Heat generating body longitudinal area 24e Long area end 25 Substrate 26 Temperature measuring element 27, 28 Feeding electrode 30 Pressure roller 31 Core shaft part 32 Elastic part 32e Longitudinal end 33 End flange member (heat dissipation part)

230 Pressure roller 233 End flange member 234 Cylindrical portion 235 Radiating collar portion

400 Pressure roller 401 Core shaft portion 402 Elastic portion 403 End flange member

500 Pressure roller 501 Core shaft portion 502 Elastic portion

A Bonding area A0 Longitudinal position B End exposed area C Width L1 Longitudinal width (substrate 25)
L2 Longitudinal width (heating element 24)
L3 Longitudinal width (elastic body)
N Pressure nip N0 Maximum width size passing area N1 Small width passing area N2 Non-passing area P Recording material P0 Recording material (maximum width)
P1 recording material (small width)
R0 Maximum width size passage area X Center reference line

Claims (5)

In a heating apparatus that includes a heating unit and a pressurizing unit that forms a pressure nip between the heating unit and applies a heat energy by passing the material to be heated through the pressure nip.
The pressurizing means includes a cylindrical core shaft portion, an elastic portion having rubber-like elasticity laminated on an outer surface of the core shaft portion, and a heat radiating portion joined to a shaft end portion of the core shaft portion. ,
The heat dissipating part joined to the core shaft part is inside the maximum width size passage region from the end in the direction orthogonal to the passage direction of the maximum width size passage region through which the heated material of the maximum width size passes through the pressure nip portion. A heating apparatus comprising: a region partially overlapping a portion; and an end exposed region exposed to a space outside the elastic portion.   The heating apparatus according to claim 1, wherein a heat generation area in a direction orthogonal to a passing direction of the material to be heated of the heating means corresponds to the maximum width size passing area. The heating means has a flexible sleeve and a heater that contacts the flexible sleeve, and the pressurizing means forms a pressure nip portion with the heater via the flexible sleeve. ,
The heater includes a substrate and a heating element provided on the substrate along the pressure nip portion,
The heating area of the heating means is a heating element longitudinal area in a direction perpendicular to the passing direction of the heating target material of the heating element, and the area partially overlapping with the inner part of the maximum width size passing area of the heat radiating portion of the pressing member is The heating device according to claim 2, wherein the heating device is a region located inside the heating element longitudinal region.   The heating device according to any one of claims 1 to 3, wherein the end exposed region of the heat radiating portion has a portion having a large cross-sectional area with respect to a bonding region with the core shaft portion.   The region partially overlapping with the inner part of the maximum width size passage region of the heat radiating portion of the pressure member corresponds to a non-passage region through which a material to be heated smaller than the maximum width does not pass among the maximum width size passage region. The heating device according to any one of claims 1 to 4.

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