JP2019124800A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device that enables both elimination of a temperature drop in an end part inside a paper passing area and suppression of a temperature rise in an end part outside the paper passing area without deteriorating productivity.SOLUTION: A fixing device comprises: a rotatable fixing member; a pressure member that is disposed outside the fixing member and faces the fixing member; a heat source that is disposed in the interior of the fixing member and heats the fixing member; a nip-forming member that is disposed inside the fixing member and forms a fixing nip between the fixing member and the pressure member; and holding members that are disposed opposite ends in the longitudinal direction of the fixing member and guide rotation of the fixing member. The nip-forming member is composed of a plurality of material members having different heat conductivities. In a passing area through which a recording material passes, the nip-forming member has a substrate and a first high-heat conductive member positioned on the fixing nip side of the substrate. In a non-passing area through which a recording material does not pass, the nip-forming member has a second high-heat conductive member. The second high-heat conductive member projects in its longitudinal direction outside the holding member.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a fixing device and an image forming apparatus.

  In recent years, market demands for energy saving and speeding up of image forming apparatuses such as printers, copiers and facsimiles have become strong. In the above image forming apparatus, a toner image (unfixed toner image) formed by an image forming process such as electrophotographic recording, electrostatic recording, magnetic recording, etc. is directly or through an intermediate transfer member, recording material sheet, printing paper, photosensitive Transfer to a recording material such as paper or electrostatic recording paper. Then, the recording material carrying the toner image is passed through a fixing device to fix the toner image on the recording material.

  As a fixing device, a fixing device of a contact heating method such as a heat roller method, a film heating method, or an electromagnetic induction heating method is widely adopted. For example, in a configuration using an endless belt, Patent Document 1 proposes a fixing device capable of warming the entire belt and shortening the first print time from the heating standby time. This fixing device responds to the recent demand for reduction in power consumption (energy saving) and shortening of warm-up time (speeding up) by reducing the heat capacity of fixing members such as a fixing belt and a fixing film.

  However, due to the low heat capacity of the fixing member, the temperature of the fixing member tends to fluctuate. Therefore, when a sheet (small-sized sheet) having a width narrower than the heating width of the heat source for heating the fixing member is passed, the temperature rise of the region out of the sheet passing range becomes remarkable in the axial direction of the fixing member. (The temperature rise at the outer end of the sheet passing area) has occurred. That is, when small size paper is continuously passed, there is a possibility that members constituting the fixing device, such as a fixing member and a pressing member, may reach the heat-resistant temperature or more. Therefore, in order to protect these members, it is necessary to suppress the temperature of the area outside the sheet passing range, and there is a problem that the productivity of sheet passing must be lowered (CPM down).

  In order to solve this problem, Patent Document 2 discloses that a rotatable fixing member, a heating source for heating the fixing member, a nip forming member disposed inside the fixing member, and nip formation via the fixing member. A fixing device is disclosed which includes a pressing member which forms a predetermined nip with the fixing member by abutting on the member, and the nip forming member is formed of a plurality of members having different thermal conductivities. . The nip forming member is disposed on the base, the first high thermal conductivity member disposed on the nip side of the base and having a thermal conductivity greater than that of the base, and disposed on the non-nip side of the substrate. A connection member which has a second high heat conduction member having a thermal conductivity higher than that of the first heat conduction member, and is disposed at both ends in the longitudinal direction of the substrate to connect the first high heat conduction member and the second high heat conduction member It is characterized by having.

  Since the heat of the first high thermal conductivity member is transferred to the second high thermal conductivity member through the connection member, the fixing device of Patent Document 2 effectively suppresses the temperature rise of the outer end portion of the sheet passing area. Can.

  SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device capable of achieving both the elimination of temperature sag at the end of the sheet passing area and the suppression of the temperature rise at the outer end of the sheet passing area without reducing the productivity.

  The above object is achieved by a rotatable fixing member, a pressure member provided on the outer side of the fixing member and facing the fixing member, a heat source provided in the fixing member and heating the fixing member, and A nip forming member provided inside the fixing member and forming a fixing nip between the fixing member and the pressing member, and provided at both longitudinal ends of the fixing member to guide rotation of the fixing member In the fixing device, the nip forming member is composed of a plurality of members having different thermal conductivities, and the nip forming member in the passage area through which the recording material passes is a base material and the base material. The nip forming member in the non-passing area having the first high heat conducting member disposed on the fixing nip side and not passing the recording material has the second high heat conducting member, and the second high heat conducting member But, It is solved by a fixing device, characterized in that in the longitudinal direction protrudes to the outside of the holding member.

  Further, the above-mentioned subject includes a rotatable fixing member, a pressure member provided outside the fixing member and facing the fixing member, a heat source provided inside the fixing member, and heating the fixing member, A nip forming member provided inside the fixing member and forming a fixing nip between the fixing member and the pressing member, and provided at both ends in the longitudinal direction of the fixing member to guide the rotation of the fixing member In the fixing device including the holding member, the thermal conductivity of the nip forming member in the passage area through which the recording material passes is 0.6 W / (m · K) or less, and in the non-passage region through which the recording material does not pass The thermal conductivity of the nip-forming member is 200 W / (m · K) or more, and the nip-forming member in the non-passing area protrudes outward of the holding member in its longitudinal direction. Also solved by a fixing device.

  In the fixing device of the present invention, the nip forming member in the passage area has the first high thermal conductivity member disposed on the fixing nip side, and the nip forming member in the non-passage region (second high thermal conduction member) Is projecting outward of the holding member in its longitudinal direction. Therefore, it is possible to achieve both the elimination of the temperature sag at the end of the sheet passing area and the suppression of the temperature rise at the outer end of the sheet passing area without lowering the productivity.

FIG. 1 is a schematic cross-sectional view showing a fixing device according to an embodiment of the present invention. It is a schematic sectional drawing of the nip formation member which concerns on one Embodiment of this invention. FIG. 2 is a schematic cross-sectional view around a fixing nip of a fixing device according to an embodiment of the present invention. It is a schematic sectional drawing (the 1) which shows the modification of a nip formation member. It is a schematic sectional drawing (the 2) which shows the modification of a nip formation member. It is a schematic sectional drawing (the 3) which shows the modification of a nip formation member. FIG. 1 is a schematic view showing an image forming apparatus according to an embodiment of the present invention.

  Hereinafter, before describing the embodiments, preliminary matters for facilitating the understanding of the embodiments will be described.

  In addition to the temperature rise at the outer end of the sheet passing area, the present inventors pay attention to "temperature drop at the end within the sheet passing area" and "problem when using a single heater".

  Generally, a halogen heater is used as a heat source of the fixing device. This halogen heater reduces the heating output at the longitudinal end of the heat generating portion (the portion where the filament is spirally wound). In the low heat capacity fixing device, the heat quantity distribution of the heat source appears remarkably as the surface temperature of the fixing member.

  In particular, when the fixing device is cold (for example, at the time of start of the morning, etc.), there is a significant temperature difference between the central portion and the end portion of the sheet than in the conventional case. This problem is called temperature sag at the end of the paper.

  In the past, this problem has been addressed by raising the set temperature of the heat source. However, in the above-described low heat capacity fixing device, a significant temperature rise (temperature rise at the outer end of the sheet passing area) may occur at the end outside the sheet passing area. Therefore, in order to achieve both the elimination of the temperature sag at the end of the sheet passing area and the suppression of the temperature rise at the outer end of the sheet passing area, it is necessary to lower the productivity of the sheet passing.

  Further, in a fixing device (image forming apparatus) intended for low cost, a single heater configuration with one heat source is selected. In the case of this single heater, as described above, since the heating output is reduced at the longitudinal end of the heat generating portion, both the elimination of the temperature drop at the end of the sheet passing area and the suppression of the temperature rise at the outer end of the sheet passing area Problem has become more difficult.

  In the following embodiments, a fixing device capable of achieving both the elimination of temperature sag at the end in the sheet passing area and the suppression of the temperature rise at the outer end in the sheet passing area without reducing the productivity will be described.

(Embodiment)
FIG. 1 is a schematic sectional view showing a fixing device according to an embodiment of the present invention. The fixing device 200 is provided with a fixing belt 201 which is a rotatable fixing member, a halogen heater 202 which is provided inside the fixing belt 201 and is a heat source which heats the fixing belt 201, and provided outside the fixing belt 201 And a pressure roller 203, which is a pressure member facing the belt 201. The fixing device 200 is provided inside the fixing belt 201, and is provided at both ends in the longitudinal direction of the fixing belt 201, and a nip forming member 206 for forming the fixing nip N between the fixing belt 201 and the pressure roller 203. And a flange 209 which is a holding member for guiding the rotation of the fixing belt 201.

  The fixing belt 201 is an endless belt (or film) using a metal belt such as nickel or SUS, or a resin material such as polyimide. A release layer such as a PFA layer or a PTFE layer is provided on the surface layer of the belt, and has a release property so that the toner does not adhere.

  It is desirable to provide an elastic layer formed of a silicone rubber layer or the like between the base material of the belt (or film) and the releasing layer. When the silicone rubber layer is not provided, the heat capacity is reduced and the fixability is improved. However, when the unfixed image is crushed and fixed, the minute unevenness on the belt surface may be transferred to the image, and the uneven glossiness (yuzu skin image) may be left on the solid portion of the image.

  Therefore, it is desirable to provide the silicone rubber layer with a thickness of 100 (μm) or more, and the fine unevenness can be absorbed by the deformation of the silicone rubber layer to improve the dull skin image.

  In the pressure roller 203, an elastic rubber layer 205 is provided on a core metal 204, and a release layer (PFA or PTFE layer) for obtaining releasability is provided on the surface of the elastic rubber layer 205. The pressure roller 203 is rotated by transmitting a driving force from a driving source such as a motor provided in the image forming apparatus via a gear. The pressure roller 203 is pressed against the fixing belt 201 by a spring or the like, and the elastic rubber layer 205 is crushed and deformed to generate a predetermined nip width.

  The pressure roller 203 may be a hollow roller, and may have a heat source such as a halogen heater inside the hollow. The elastic rubber layer 205 may be solid rubber, but if there is no heat source inside the pressure roller 203, sponge rubber may be used. Sponge rubber is more desirable because it has high thermal insulation and the heat of fixing belt 201 is less likely to be taken away.

  Although the halogen heater 202 as a heat source is shown by FIG. 1, it may replace with this and may use an induction heating apparatus (IH), a resistance heating element, or a carbon heater.

  The fixing nip N of the nip forming member 206 has a flat shape, but is not limited to this, and may have a concave shape or another shape. For example, when the shape of the fixing nip N is a concave shape, the discharge direction of the leading end of the recording material is closer to the pressure roller 203, and the separability is improved. Therefore, there is an effect that the occurrence of jamming is suppressed.

  Further, as shown in FIG. 1, a sliding sheet 207 which is a sliding member may be wound around the surface of the nip forming member 206 and may slide on the inner surface of the fixing belt 201. Alternatively, the nip forming member 206 may slide directly on the inner surface of the fixing belt 201.

  Inside the fixing belt 201, a stay 208 which is a support member for supporting the fixing nip N is provided. Since the stay 208 prevents the deflection of the nip forming member 206 that is subjected to pressure by the pressure roller 203, an axially uniform nip width can be obtained. Both ends of the stay 208 are held and positioned by a flange 209 which is a holding member. The flange 209 encloses the above components except the pressure roller 203.

  A reflective member 210 is provided between the halogen heater 202 and the stay 208. The reflection member 210 reflects radiant heat and the like from the halogen heater 202, and suppresses wasteful energy consumption due to the stay 208 being heated. The same effect can be obtained even if the surface of the stay 208 is heat-insulated or mirror-polished instead of including the reflection member 210.

  In the fixing device 200 having such a configuration, the pressing roller 203 is rotated by the driving source, and the driving force is transmitted to the fixing belt 201 at the fixing nip N, whereby the fixing belt 201 is also rotated. The fixing belt 201 is nipped and rotated by the fixing nip N, and is guided by the flanges 209 at both ends except for the fixing nip N and travels.

  With the above-described configuration, it is possible to realize a fixing device that is inexpensive and has a fast warm-up.

  Subsequently, the characteristic configuration of the present invention will be described.

  FIG. 2 is a schematic cross-sectional view of a nip forming member according to an embodiment of the present invention. The lower side of the drawing is the fixing nip side (the surface that slides on the fixing belt). As shown in FIG. 2, in the longitudinal direction, the nip forming member 206 is divided into two areas of a passing area through which the recording material passes and a non-passing area through which the recording material does not pass. Further, the full width of the passing area is the same as the maximum width of the recording material defined in the fixing device.

  In the passage area, the nip forming member 206 is composed of a base 220 and a first high heat conducting member 222 disposed on the fixing nip side of the base 220. On the other hand, in the non-passing area, the nip forming member 206 is constituted only by the second high heat conduction member 224.

  As a specific material, a general heat-resistant resin such as polyphenylene sulfide (PPS) or liquid crystal polymer (LCP) can be used as the substrate 220. Moreover, copper, aluminum etc. can be used as a 1st, 2nd highly heat-conductive member, for example. The first high thermal conductivity member 222 and the second high thermal conductivity member 224 may not necessarily be the same material.

  Further, the thermal conductivity of the nip forming member in the passage area through which the recording material passes is 0.6 W / (m · K) or less, and the thermal conductivity of the nip forming member in the non-passing region through which the recording material does not pass is It is desirable to set it as 200 W / (m * K) or more.

  As described above, in the present embodiment, the nip forming member 206 is formed of a plurality of members having different thermal conductivity.

  FIG. 3 is a schematic cross-sectional view around a fixing nip of a fixing device according to an embodiment of the present invention. As shown in FIG. 3, the second high thermal conductivity member 224 is characterized by protruding to the outside of the flange 209 holding the fixing belt 201. Since the temperature outside the flange 209 is lower than the inside of the flange 209 (the space formed by the flange 209 and the fixing belt 201), the heat of the second high thermal conductivity member 224 can be dissipated more efficiently.

  The second high thermal conductivity member 224 may be a heat dissipating fin shape, as well as protruding to the outside of the flange 209 in order to increase the surface exposed to the outside air.

  The operation and effects of the fixing device 200 configured as described above will be described. It is assumed that the output (set temperature) of the heat source (halogen heater 202) is increased so that a significant temperature difference does not occur between the central portion and the end portion of the recording material passing area. Since the nip forming member 206 has the first high thermal conductivity member 222 in the passage area (see FIG. 2), the heat from the heat source travels across the passage area in a short time. Therefore, a significant temperature difference can be eliminated in the passage area.

  Also, the non-passing area of the nip forming member 206 starts to rise in temperature at its both ends. On the other hand, the nip forming member 206 can dissipate heat to the outside because the second high thermal conductivity member 224 projects outside the flange 209 in the non-passing area (see FIG. 3). Therefore, the temperature rise at the end of the non-passing area can be suppressed.

  As described above, the fixing device according to the present embodiment raises the temperature rise of the non-passing area (outside end of the paper passing area) while increasing the output of the heat source to eliminate the temperature sag of the passing area (end of the paper inside area). It can be suppressed. That is, without lowering the productivity, it is possible to achieve both the elimination of the temperature sag at the end of the sheet passing area and the suppression of the temperature rise at the outer end of the sheet passing area.

  Moreover, this configuration is particularly useful for a single heater (one heat source configuration) in which it is necessary to increase the output of the heat source to eliminate temperature sag.

(Modification)
FIG. 4 is a schematic cross-sectional view (part 1) showing a modified example of the nip forming member. As shown in FIG. 4, the nip forming member 206 is provided with a sliding sheet 230 which is a low friction sliding member in the passage area. The sliding sheet 230 is formed by, for example, weaving fibers of PTFE or PFA into a sheet, and can improve the sliding property with the fixing belt 201.

  Here, the nip forming member 206 in the passing area slides with the fixing belt 201 via the sliding sheet 230, and the nip forming member 206 in the non-passing area slides directly with the fixing belt 201. The reason is that the sliding sheet 230 generally has a heat insulating effect. It is desirable that the nip forming member 206 (second high thermal conductivity member 224) in the non-passing area slide directly on the fixing belt 201 in order to ensure heat dissipation.

  Further, it is desirable that a lubricant such as silicone oil, silicone grease or fluorine-based grease be applied to the second high thermal conductivity member 224 in order to improve the slidability with the fixing belt 201.

  If the height of the surface of the sliding sheet 230 and the surface height of the second high heat transfer member 224 differ in the surface facing the fixing nip, the fixing belt 201 facing the other at the switching point can not contact uniformly over the entire surface. . Therefore, these dimensions and thickness are defined in advance so that the height of the surface of the sliding sheet 230 and the surface height of the second high thermal conductivity member 224 become the same.

  FIG. 5 is a schematic cross-sectional view (part 2) showing a modified example of the nip forming member. As shown in FIG. 5, the first high thermal conductivity member 222 and the second high thermal conductivity member 224 are connected via a low thermal conductivity member 232 having a thermal conductivity lower than that of the high thermal conductivity members.

  The reason for this configuration is as follows. First, it is because heat at the end in the passing area is less likely to escape to the non-passing area (elimination of temperature sag). Further, even during continuous passage of the recording material, the movement of heat from the passing region to the non-passing region is reduced (suppression of temperature rise). As a result, it is possible to achieve both the elimination of temperature sag at the end of the sheet passing area and the suppression of the temperature rise at the outer end of the sheet passing area without further reducing the productivity.

  FIG. 6 is a schematic cross-sectional view (part 3) showing a modified example of the nip forming member. In this variation, instead of separately providing the low thermal conductivity member 232, the low thermal conductivity member 232 is integrally formed of the base member 220. In this case, it is advantageous because the number of parts can be reduced and the assemblability can be improved.

  FIG. 7 is a schematic view showing an image forming apparatus according to an embodiment of the present invention, including the above-described fixing device. The image forming apparatus 100 is a color printer that uses a tandem system in which image forming units that form a plurality of color images are juxtaposed along the belt stretching direction, but the present invention is not limited to this system. It is also possible to target not only printers but also copiers and facsimiles.

  The image forming apparatus 100 includes photosensitive drums 20Y, 20C, 20M, and 20Bk as image carriers capable of forming an image as an image corresponding to a color separated into each color of yellow, cyan, magenta, and black. A tandem structure arranged in parallel is adopted.

  In the image forming apparatus 100, the visible image formed on each photosensitive drum 20 is an intermediate belt using an endless belt movable in the direction of arrow A1 while facing the respective photosensitive drum 20 by execution of the primary transfer step. It is superimposed and transferred onto a transfer body (hereinafter referred to as a transfer belt) 11. Thereafter, the image on the intermediate transfer member is collectively transferred to the recording material S on which a recording sheet or the like is used by execution of the secondary transfer step.

  A device for forming an image according to the rotation of the photosensitive drum 20 is disposed around each photosensitive drum 20. Taking the photosensitive drum 20Bk for forming a black image as an example, the charging device 30Bk, the developing device 40Bk, the primary transfer roller 12Bk, and the cleaning device 50Bk for performing an image forming process are arranged along the rotational direction of the photosensitive drum 20Bk. It is done. The optical writing device 8 is used for writing performed after charging of each photosensitive drum 20.

  In the superimposed transfer on the transfer belt 11, visible images formed on the respective photosensitive drums 20Y, 20C, 20M, and 20Bk are transferred to the same position of the transfer belt 11 while the transfer belt 11 moves in the A1 direction. To be done. That is, voltage application by the primary transfer rollers 12Y, 12C, 12M, and 12Bk disposed opposite to the photosensitive drums 20Y, 20C, 20M, and 20Bk across the transfer belt 11 causes the A1 direction from the upstream side to the downstream side. It is done with an offset in time.

  The photosensitive drums 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the A1 direction. The photosensitive drums 20Y, 20C, 20M, and 20Bk are provided in image stations for forming yellow, cyan, magenta, and black images, respectively.

  The image forming apparatus 100 is disposed to face the upper side of each photosensitive drum 20 with four image stations for performing image forming processing for each color, and the transfer belt 11 and primary transfer rollers 12Y, 12C, 12M, 12Bk. And a transfer belt unit 10 provided with Further, the image forming apparatus 100 is disposed opposite to the transfer belt 11 and is driven by the transfer belt 11 so as to face the transfer belt 11 as a secondary transfer roller 5 which is a transfer roller as a transfer member rotating with it. And a cleaning device 13 for cleaning the transfer belt 11. And it has the optical writing device 8 as an optical writing device disposed opposite to the lower side of these four image stations.

  The optical writing device 8 is equipped with a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror as a deflecting means, and the like. The optical writing device 8 emits writing light Lb corresponding to each color to each photosensitive drum 20Y, 20C, 20M, 20Bk to form an electrostatic latent image on the photosensitive drums 20Y, 20C, 20M, 20Bk It is configured to In addition, regarding the writing light Lb, in FIG. 7, for convenience, only the image station of the black image is marked for the sake of convenience, but the same applies to the other image stations.

  In the image forming apparatus 100, a sheet feeding device 61 as a sheet feeding cassette, a pair of registration rollers 4 for feeding the recording material S conveyed from the sheet feeding device 61, and a tip of the recording material S is a pair of registration rollers 4 And a sensor for detecting that the vehicle has arrived. The recording material S from the sheet feeding device 61 includes the photosensitive drums 20Y, 20C, 20M, and 20Bk and the transfer belt 11 by the registration roller pair 4 at a predetermined timing according to the timing of forming a toner image by the image station. It is fed out toward the transfer section between the two.

  In the image forming apparatus 100, the fixing device 200 for fixing the toner image on the recording material S to which the toner image has been transferred, and the recording material S on which the toner image has been fixed are discharged to the outside of the main body of the image forming apparatus 100. The sheet discharge roller 7 is provided. A sheet discharge tray 17 is disposed on the upper portion of the main body of the image forming apparatus 100 and carries the recording material S discharged to the outside of the main body of the image forming apparatus 100 by the sheet discharge roller 7. Toner bottles 9Y, 9C, 9M, 9Bk are provided. The toner bottles 9Y, 9C, 9M and 9Bk are filled with toners of respective colors of yellow, cyan, magenta and black.

  The transfer belt unit 10 includes, in addition to the transfer belt 11, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, a drive roller 72 and a driven roller 73 around which the transfer belt 11 is wound.

  The driven roller 73 also has a function as a tension urging means for the transfer belt 11. For this purpose, the driven roller 73 is provided with an urging means using a spring or the like. A transfer device 71 is configured by the transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 5, and the cleaning device 13.

  The sheet feeding device 61 is disposed at the lower portion of the main body of the image forming apparatus 100, and has a feeding roller 3 in contact with the top surface of the top recording material S, and the feeding roller 3 rotates counterclockwise. By being driven, the uppermost recording material S is fed toward the registration roller pair 4.

  The cleaning device 13 equipped in the transfer device 71 has a cleaning brush and a cleaning blade, which are disposed to face and abut on the transfer belt 11, although the detailed illustration is omitted. Then, foreign matters such as residual toner on the transfer belt 11 are scraped and removed by the cleaning brush and the cleaning blade, and the transfer belt 11 is cleaned.

  The cleaning device 13 also has discharge means (not shown) for carrying out and discarding the residual toner removed from the transfer belt 11.

  The preferred embodiments and modifications of the present invention have been described above. The present invention is not limited to the specific embodiment, and various modifications and changes may be made within the scope of the spirit of the present invention described in the claims unless particularly limited in the above description. It is possible.

  Further, the effects described in the embodiments of the present invention only list the most preferable effects resulting from the present invention, and the effects according to the present invention are not limited to those described in the embodiments of the present invention.

Reference Signs List 3 feeding roller 4 registration roller pair 5 secondary transfer roller 7 discharge roller 8 optical writing device 9Y, 9M, 9C, 9Bk toner bottle 10 transfer belt unit 11 transfer belt 12Y, 12M, 12C, 12Bk primary transfer roller 13 Cleaning device 17 Paper discharge tray 20, 20Y, 20M, 20C, 20Bk Photosensitive drum 30Bk Charging device 40Bk Developing device 50Bk Cleaning device 61 Sheet feeding device 71 Transfer device 72 Drive roller 73 Driven roller 100 Image forming device 200 Fixing device 201 Fixing Belt 202 halogen heater 203 pressure roller 204 core metal 205 elastic rubber layer 206 nip forming member 207, 230 sliding sheet 208 stay 209 flange 210 reflecting member 220 base material 222 first high heat conducting member 224 first 2 high thermal conductivity members 232 low thermal conductivity members A1 arrow Lb writing light N fixing nip S recording material

JP 2007-334205 A JP 2015-145950 A

Claims (10)

A rotatable fixing member,
A pressure member provided on the outside of the fixing member and facing the fixing member;
A heat source provided inside the fixing member to heat the fixing member;
A nip forming member provided inside the fixing member and forming a fixing nip between the fixing member and the pressure member;
And a holding member provided at both ends in the longitudinal direction of the fixing member and guiding rotation of the fixing member.
The nip forming member is composed of a plurality of members having different thermal conductivity,
The nip forming member in a passage area through which the recording material passes includes a substrate and a first high heat conduction member disposed on the fixing nip side of the substrate.
The nip forming member in the non-passing area where the recording material does not pass has a second high heat conduction member,
A fixing device characterized in that the second high heat conduction member protrudes to the outside of the holding member in its longitudinal direction.   The fixing according to claim 1, wherein the first high thermal conductivity member and the second high thermal conductivity member are connected via a low thermal conductivity member having a thermal conductivity lower than that of the high thermal conductivity members. apparatus.   The fixing device according to claim 2, wherein the low heat conductive member is formed of the base material.   The fixing device according to any one of claims 1 to 3, wherein the first and second high thermal conductivity members are made of copper or aluminum. A rotatable fixing member,
A pressure member provided on the outside of the fixing member and facing the fixing member;
A heat source provided inside the fixing member to heat the fixing member;
A nip forming member provided inside the fixing member and forming a fixing nip between the fixing member and the pressure member;
And a holding member provided at both ends in the longitudinal direction of the fixing member and guiding rotation of the fixing member.
The thermal conductivity of the nip forming member in the passage area through which the recording material passes is 0.6 W / (m · K) or less.
The thermal conductivity of the nip forming member in the non-passing area where the recording material does not pass is 200 W / (m · K) or more.
The fixing device according to claim 1, wherein the nip forming member in the non-passing area protrudes outward of the holding member in its longitudinal direction.   The fixing device according to any one of claims 1 to 5, wherein the width of the passage area is equal to the maximum width of the recording material defined in the fixing device.   The fixing device according to any one of claims 1 to 6, wherein the nip forming member in the passage area is provided with a low friction sliding member.   The nip forming member in the passage area slides with the fixing member via the sliding member, and the nip forming member in the non-passage area slides directly with the fixing member. Item 8. A fixing device according to item 7.   9. The fixing device according to claim 8, wherein a lubricant is applied to the nip forming member in the non-passing area.   An image forming apparatus comprising the fixing device according to any one of claims 1 to 9.

Images