JP2021047221A - Fixation device and image formation apparatus - Google Patents

Abstract

To more effectively reduce the heat radiation loss than a conventional technique.SOLUTION: A fixation device 4 comprises: a fixing member 40 which has a heater 44 being the heat source and fixes an image on a sheet by performing heating processing and pressurizing processing to the sheet to which the image is transferred; a heating object member 50 which is arranged on the periphery or inner side of the fixation member 40 in the state of being in non-contact with the fixation member 40; and a partition member 70 which is arranged in a space between the fixation member 40 and the heating object member 50.SELECTED DRAWING: Figure 2

Description

The present invention relates to a fixing device and an image forming device, and more particularly to a technique for reducing heat dissipation loss in the fixing device.

Electrophotographic image forming devices such as printers and MFPs (Multifunction Peripherals)
It is equipped with a fixing device for fixing the toner image transferred to a sheet such as printing paper. The fixing device fixes the image on the sheet by applying heat treatment and pressure treatment to the sheet on which the toner image is transferred.

In recent years, it has been strongly desired that the above-mentioned image forming apparatus have improved performance related to energy saving. Therefore, in the fixing device, it is desired to improve the thermal conductivity for heat-treating the sheet and reduce unnecessary heat dissipation loss. For example, the heat dissipation loss in the fixing device is improved by suppressing heat conduction from the fixing member having a heat source to the member arranged around the fixing member.

Conventionally, in order to improve heat dissipation loss in a fixing device, for example, a technique of attaching an aluminum sheet member to the surface of an opposing member arranged to face the fixing member has been proposed (for example, Patent Document 1). In this conventional technique, since the aluminum sheet member is attached to the surface of the opposing member arranged around the fixing member, the radiant heat from the fixing member is reflected by the sheet member, and the temperature of the opposing member rises. The degree can be suppressed.

Japanese Unexamined Patent Publication No. 2013-15661

However, in the above-mentioned prior art, since the sheet member is directly attached to the surface of the opposing member facing the fixing member, the thermal conductivity from the sheet member to the opposing member is high, and the temperature of the sheet member rises. Therefore, the temperature of the opposing member tends to rise easily. Therefore, it is desired to further reduce heat dissipation loss as compared with the above-mentioned conventional technique.

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a fixing device and an image forming device capable of reducing heat dissipation loss more effectively than before.

In order to achieve the above object, the invention according to claim 1 is a fixing device, which has a heat source and fixes an image on a sheet by subjecting a sheet to which an image has been transferred to heat treatment and pressure treatment. A fixing member to be heated, a heated member arranged around or inside the fixing member in a non-contact state with the fixing member, and a partition member arranged in a space between the fixing member and the heated member. , Is a configuration characterized by being provided with.

According to a second aspect of the present invention, in the fixing device of the first aspect, the fixing member is arranged so as to face the first fixing member which has the heat source and heats the sheet and the first fixing member. A second fixing member that forms a nip portion between the first fixing member and presses the sheet to be passed through the nip portion is provided, and the partition member includes the first fixing member and the first fixing member. (1) The configuration is characterized by having a first heat shield member arranged in a space between the fixing member and the heated member.

The invention according to claim 3 is the fixing device according to claim 2, wherein the first heat shield member includes a first resin film, and the thermal deformation temperature of the first resin film is for the heat treatment. The configuration is characterized in that the temperature is equal to or higher than the set temperature.

According to a fourth aspect of the present invention, in the fixing device according to the second or third aspect, the first fixing member is hung on a heating roller having the heat source and the heating roller, and the first fixing member and the nip portion. The partition member further includes a fixing belt that circulates between the fixing belt and the first fixing member, and the heated member arranged around the first fixing member inside the fixing belt. The configuration is characterized by having a second heat shield member arranged in the space between the two.

According to the invention of claim 5, in the fixing device of claim 4, the fixing belt includes a resin base material, the second heat shield member includes a second resin film, and the second resin. The structure is characterized in that the thermal deformation temperature of the film is equal to or higher than the thermal deformation temperature of the resin base material.

The invention according to claim 6 is the fixing device according to any one of claims 2 to 5, wherein the partition member has a metal reflecting surface on a surface facing the first fixing member.

The invention according to claim 7 is the fixing device according to any one of claims 1 to 6, wherein the partition member forms an air layer on the back surface side facing the heated member.

The invention according to claim 8 further includes a plurality of spacer members attached to the heated member in the fixing device according to any one of claims 1 to 7, and the partition member is stretched by the plurality of spacer members. It is a configuration characterized in that it is supported in a state of being in a state of being.

The invention according to claim 9 is the fixing device according to claim 8, wherein the support member is a member having a lower thermal conductivity than the partition member.

The invention according to claim 10 is an image forming apparatus, wherein an image is transferred to the fixing device according to any one of claims 1 to 9 and an image is transferred to the fixing device, and the sheet is conveyed to the fixing device. It is a configuration characterized by having a unit and a unit.

According to the present invention, the partition member arranged in the space between the fixing member and the heated member can further effectively reduce heat dissipation loss as compared with the conventional case.

It is a figure which shows the conceptual structure of the image forming apparatus. It is sectional drawing which shows the structural example of the fixing device in 1st Embodiment. It is a figure which shows the partition member in an enlarged manner. It is a figure which shows the example of a spacer member. It is a perspective view of the fixing member seen from diagonally above. It is sectional drawing which shows the structural example of the fixing device in 2nd Embodiment. It is a perspective view which shows one structural example of a frame member. It is an enlarged view which shows the connection part of a frame member and a roller support plate.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments described below, elements that are common to each other are designated by the same reference numerals, and duplicate description thereof will be omitted.

(First Embodiment)
FIG. 1 is a diagram showing a conceptual configuration of an image forming apparatus 1 according to an embodiment of the present invention. The image forming apparatus 1 shown in FIG. 1 is a printer capable of forming a color image in a tandem manner. The image forming apparatus 1 has a paper feed tray 8 that accommodates a plurality of sheets 9 such as printing paper and feeds them one by one, and a color image or a monochrome image is printed on the sheets 9 fed from the paper feed tray 8. Is formed, and the sheet 9 is discharged onto the paper discharge tray 6 from the discharge port 5 provided in the upper part of the main body of the apparatus. The image forming apparatus 1 includes a conveying unit 2 that conveys the sheet 9 inside the apparatus main body, and an image forming unit 3 that transfers an image to the sheet 9 conveyed by the conveying unit 2 to form an image. The sheet 9 to which the image is transferred is provided with a fixing device 4 for fixing the image to the sheet 9 by subjecting the sheet 9 to heat treatment and pressure treatment. The image forming apparatus 1 forms an image on the sheet 9 by operating the conveying unit 2, the image forming unit 3, and the fixing device 4 in synchronization with each other. Further, the image forming apparatus 1 is provided with a control unit 7 inside the main body of the apparatus, and the control unit 7 controls the operation of each unit such as the conveying unit 2, the image forming unit 3, and the fixing device 4.

The transport unit 2 includes a paper feed tray 8, a pickup roller 10, a transport roller 12, a transport path 13, a timing roller 14, a secondary transfer roller 15, and a discharge roller 16.

The paper feed tray 8 is a container for storing sheets 9 such as printing paper. There are various types of sheets 9 that can be stored in the paper feed tray 8, and examples thereof include thin paper, thick paper, plain paper, recycled paper, coated paper, and OHP film. Although FIG. 1 shows a case where the image forming apparatus 1 has one paper feed tray 8, a plurality of paper feed trays 8 may be provided.

A pickup roller 10 and a transport roller 12 are provided near the paper feed tray 8. The pickup roller 10 and the transfer roller 12 are rollers for sending the sheet 9 stored in the paper feed tray 8 to the transfer path 13. The pickup roller 10 comes into contact with the uppermost sheet 9 housed in the paper feed tray 8 and sends out the uppermost sheet 9 toward the transfer roller 12. The transfer roller 12 includes a paper feed roller 12a and a separation roller 12b, and when a plurality of sheets 9 are sent out by the pickup roller 10, only the uppermost sheet 9 is supplied to the downstream transfer path 13. It has a paper function.

The sheet 9 fed to the transport path 13 is then fed toward the secondary transfer roller 15, which is the position where the image is transferred by the timing roller 14. The transport path 13 is a path for transporting the sheet 9 in the direction of the arrow F2 when the image forming apparatus 1 forms an image on the sheet 9. For example, when the tip of the sheet 9 being conveyed along the transfer path 13 reaches the timing roller 14, the transfer unit 2 temporarily stops the sheet 9 there. Then, the transport unit 2 drives the timing roller 14 at the timing when the toner image formed on the intermediate transfer belt 33 in the image forming unit 3 reaches the position of the secondary transfer roller 15, and causes the sheet 9 to be transferred to the secondary transfer roller 15. Transport to position 15. As a result, the toner image (image) is transferred to the surface of the sheet 9 when it passes through the position of the secondary transfer roller 15. After that, the sheet 9 is guided by the fixing device 4 to be subjected to a toner image fixing treatment including a heat treatment and a pressure treatment.

The image forming unit 3 forms a toner image of four colors of Y (yellow), M (magenta), C (cyan), and K (black), and the sheet 9 conveyed by the conveying unit 2 is a secondary transfer roller 15. When passing through the position of, the toner images of those four colors can be transferred to the sheet 9 at the same time. The image forming unit 3 corresponds to a plurality of toner bottles 19 (19Y, 19M, 19C, 19K) corresponding to each color, a plurality of image forming units 20 (20Y, 20M, 20C, 20K) corresponding to each color, and each color. It is provided with a plurality of exposed units 25 (25Y, 25M, 25C, 25K) and a transfer unit 30.

The transfer unit 30 is intermediate between a pair of rollers 31 and 32 arranged at predetermined intervals and an intermediate transfer belt 33 which is composed of endless belts and is arranged so as to be hung on the pair of rollers 31 and 32. It is a unit having a plurality of primary transfer rollers 34 (34Y, 34M, 34C, 34K) arranged at positions facing each image forming unit 20 inside the transfer belt 33, and these are integrally assembled. ..

Of the pair of rollers 31 and 32, one roller 31 is a drive roller that is mounted on a drive shaft provided inside the apparatus main body 1a and rotates, and the intermediate transfer belt 33 is driven by the rotation drive of the drive shaft. Circularly move in the direction of arrow F1. The other roller 32 is mounted on a driven shaft provided inside the apparatus main body 1a, and rotates driven as the intermediate transfer belt 33 circulates. The pair of rollers 31 and 32 are installed at positions separated by a predetermined distance inside the apparatus main body 1a in a state where a constant tension is applied to the intermediate transfer belt 33. The roller 31 is mounted on the drive shaft and is installed at a position facing the secondary transfer roller 15, and is pushed by the intermediate transfer belt 33 with the intermediate transfer belt 33 sandwiched between the roller 31 and the secondary transfer roller 15. Applying pressure. Then, the roller 31 sandwiches the sheet 9 conveyed by the transfer unit 2 between the intermediate transfer belt 33 and the secondary transfer roller 15 and presses the sheet 9 to obtain a toner image formed on the surface of the intermediate transfer belt 33. Secondary transfer is performed on the sheet 9.

The image forming units 20Y, 20M, 20C, 20K corresponding to each color are provided at the lower positions of the transfer unit 30, and the exposure units 25Y, 25M, 25C, 25K corresponding to each color are the image forming units 20Y, 20M, 20M, respectively. It is provided at a position further below 20C and 20K. The toner bottles 19Y, 19M, 19C, 19K are arranged above the transfer unit 30, and a developer containing toner of each color is supplied to each image forming unit 20Y, 20M, 20C, 20K.

Each image forming unit 20Y, 20M, 20C, 20K has the same configuration, only the color of the toner used is different. That is, each image forming unit 20Y, 20M, 20C, 20K has an image carrier 21 configured as a photoconductor drum, a charging unit 22 arranged around the image carrier 21, a developing device 23, and cleaning. It is equipped with a blade 24. In the following, when it is not necessary to distinguish each image forming unit 20Y, 20M, 20C, 20K, they may be collectively referred to as an image forming unit 20.

The image carrier 21 has a photosensitive layer on the surface of the drum, and is in contact with the intermediate transfer belt 33 to which the transfer pressure applied by the primary transfer roller 34 of the transfer unit 30 is applied, for example, in the clockwise direction (clockwise direction). Rotate to. A cleaning blade 24, a charging unit 22, and a developing device 23 are arranged around the image carrier 21 along the rotation direction. The charging unit 22 is configured to include a charging roller that is in contact with the surface of the image carrier 21, and charges the surface of the image carrier 21 to a predetermined charge. The exposure unit 25 forms an electrostatic latent image on the surface of the image carrier 21 by exposing the photosensitive layer charged by the charging unit 22 based on the image data. The developer 23 is filled with a developer containing toner and carriers, supplies the developer to the surface of the image carrier 21, and supports the image by visualizing an electrostatic latent image with toner. A toner image is formed on the surface of the body 21. The toner image formed on the image carrier 21 is primarily transferred to the intermediate transfer belt 33 at a position where it comes into contact with the intermediate transfer belt 33. A bias voltage having a polarity opposite to that of the charged toner image formed on the surface of the image carrier 21 is applied to the primary transfer roller 34, and the toner image formed on the surface of the image carrier 21 by electrostatic force. Can be primarily transferred to the intermediate transfer belt 33.

Each image forming unit 20Y, 20M, 20C, 20K cooperates with the respective primary transfer rollers 34Y, 34M, 34C, 34K to display toner images of each color on the intermediate transfer belt 33 that circulates in the direction of arrow F1. Primary transfer is performed while sequentially superimposing. Therefore, when the intermediate transfer belt 33 passes the position of the most downstream image forming unit 20K, a color image on which four color toner images are superimposed is formed on the surface of the intermediate transfer belt 33. When forming a monochrome image on the sheet 9, the image forming units 20Y, 20M, and 20C do not operate, and only the image forming unit 20K corresponding to K (black) operates and the intermediate transfer belt 33 has K. A monochrome image is formed using only toner.

Then, when the toner image formed on the intermediate transfer belt 33 passes through the position facing the secondary transfer roller 15, it comes into contact with the sheet 9 fed by the transport unit 2, and is secondary to the surface of the sheet 9. Transcribed. That is, the secondary transfer roller 15 is provided at a position facing the roller 31 with the intermediate transfer belt 33 interposed therebetween, and is charged when the toner image primary transferred to the intermediate transfer belt 33 comes into contact with the sheet 9. The toner image is secondarily transferred to the sheet 9 by applying a bias voltage having a polarity opposite to that of the toner.

The sheet 9 on which the toner image is transferred at the position of the secondary transfer roller 15 is then transferred to the fixing device 4. The fixing device 4 has a fixing member 40 that fixes the toner image to the sheet 9 by subjecting the sheet 9 on which the toner image is transferred to heat treatment and pressure treatment. The fixing member 40 has a first fixing member 41 and a second fixing member 42. The first fixing member 41 and the second fixing member 42 are in contact with each other to form a nip portion, and the sheet 9 is heat-treated and pressurized by passing the sheet 9 through the nip portion. Hereinafter, such a fixing device 4 will be described in detail.

FIG. 2 is a cross-sectional view showing a configuration example of the fixing device 4 according to the first embodiment. As shown in FIG. 2, the fixing device 4 is formed with a path 43 through which the sheet 9 is passed, and the first fixing member 41 and the second fixing member 42 are positioned so as to face each other with the path 43 interposed therebetween. Be placed.

The first fixing member 41 includes a heating roller 45 in which a heater 44 serving as a heat source is arranged inside, a support member 56 arranged to face the heating roller 45, and a first pad arranged above the support member 56. It includes a 46, a second pad 47 arranged on the side surface of the support member 56, a heating roller 45, and a fixing belt 48 arranged so as to be hung on the first pad 46 and the second pad 47. .. The first fixing member 41 circulates and moves the fixing belt 48 in the F3 direction by rotating the heating roller 45 in the R1 direction. The heater 44 heats the heating roller 45 to raise the temperature of the fixing belt 48 to a predetermined temperature. The fixing belt 48 includes a resin base material, and heat-treats the sheet 9 passing through the path 43 as it circulates in the F3 direction in a heated state.

The second fixing member 42 includes a pressure roller 49 arranged so as to face the first fixing member 41. The pressure roller 49 abuts on the first fixing member 41 at a position facing the second pad 47 to form a nip portion P. That is, the pressure roller 49 forms a nip portion P with the fixing belt 48. Then, when the sheet 9 passes through the nip portion P, the pressurizing roller 49 applies a predetermined pressing force to the sheet 9 to perform a pressurizing process.

Various members to be heated 50 are arranged around or inside the fixing member 40 in a non-contact state with the fixing member 40. For example, at a position above the first pad 46 of the first fixing member 41, a first guide member 61 for guiding the sheet 9 toward the discharge port 5 and a support member 51 for supporting the first guide member 61 are provided. Is placed. Further, a thermostat 62 for adjusting the temperature of the fixing belt 48 and a support member 52 for supporting the thermostat 62 are arranged above the heating roller 45 of the first fixing member 41. Further, a temperature sensor 63 for detecting the temperature and a support member 53 for supporting the temperature sensor 63 are arranged below the heating roller 45. Further, a second guide member 64 for guiding the sheet 9 toward the discharge port 5 and a support member 54 for supporting the second guide member 64 are arranged above the pressure roller 49. Further, a guide member 55 for guiding the sheet 9 to the nip portion P between the first fixing member 41 and the second fixing member 42 is arranged at a lower position of the pressure roller 49. Further, as described above, a support member 56 for supporting the first pad 46 and the second pad 47 is arranged inside the fixing member 40, more specifically, inside the first fixing member 41. Among these members, the support members 51, 52, 53, 54, 56 and the guide member 55 are made of metallic members having a predetermined thickness in order to maintain a certain rigidity, and are, for example, L-shaped or U-shaped. It is composed of sheet metal members that are bent in a character shape. The support members 51, 52, 53, 54, 56 and the guide member 55 are all members 50 to be heated as the temperature of the fixing member 40 rises, and as the temperature of the member 50 rises, the temperature of the member 50 increases. The heat dissipation loss in the fixing device 4 becomes large.

When the sheet 9 is passed through the fixing device 4, the fixing belt 48 heated by the heating roller 45 becomes a high temperature state (about 150 ° C.), so that the fixing belt 48 is arranged close to the outer periphery of the fixing belt 48. The support members 51, 52, and 53 may be in a high temperature state due to radiation and convection from the surface of the fixing belt 48. For example, when about 30 sheets are printed, the temperature of the support members 51, 52, 53 is raised to about 50 ° C. If the room temperature is 25 ° C., the temperature of the support members 51, 52, 53 will be raised by about 25 ° C. due to the thermal energy radiated from the first fixing member 41. In order to reduce the heat dissipation loss, the fixing device 4 of the present embodiment reduces the conduction of heat energy in the space between the first fixing member 41 and the support members 51, 52, 53 which are the members to be heated 50. A partition member 70 for the purpose is provided.

On the other hand, the temperature rise rate of the support member 54 and the guide member 55 arranged close to the periphery of the pressure roller 49 is lower than that of the support members 51, 52, 53, and the temperature rise is about 3 ° C. That is, since the heat dissipation loss to the support member 54 and the guide member 55 is small, the fixing device 4 of the present embodiment adopts a configuration in which the partition member 70 is not provided to the support member 54 and the guide member 55.

Further, the support member 56 arranged inside the fixing belt 48, in addition to radiation and convection from the respective surfaces of the heating roller 45 and the fixing belt 48, further heat conduction through the first pad 46 and the second pad 47. The temperature rise rate is the largest, and the temperature rises to about 100 ° C. Therefore, in the fixing device 4 of the present embodiment, in order to reduce heat dissipation loss due to radiation and convection from the surfaces of at least the heating roller 45 and the fixing belt 48 raising the temperature of the support member 56, the heating roller 45 and the fixing device 4 are combined with the heating roller 45. A partition member 70 for reducing the conduction of heat energy is provided in the space between the support member 56.

The partition member 70 is, for example, a member based on a thin resin film having flexibility, and is arranged in a space between the first fixing member 41 and the support members 51, 52, 53, 56. A space having an air layer is formed on both the front surface side and the back surface side, and the conduction of heat energy due to radiation and convection from the heating roller 45 and the fixing belt 48 is blocked. Such a partition member 70 has two functions, that is, a function of reflecting radiant heat and a function of suppressing diffusion of high-temperature air due to heat convection.

Further, the partition member 70 is stretched on each member arranged around the outside and inside of the first fixing member 41 via a spacer member 73 having a predetermined height and having heat insulating properties. Attached to. For example, at an upper position of the first pad 46, spacer members 73 are attached to a plurality of locations of the first guide member 61 and the support member 51, and a partition member 70 is stretched between the plurality of spacer members 73. .. Further, at the upper position of the heating roller 45, spacer members 73 are attached to a plurality of positions of the support member 51 and the support member 52, and a partition member 70 is stretched between the plurality of spacer members 73. Further, at the lateral position of the heating roller 45, spacer members 73 are attached to a plurality of positions of the support member 52 and the support member 53, and a partition member 70 is stretched between the plurality of spacer members 73. Further, inside the fixing belt 48, spacer members 73 are attached to a plurality of positions of the support member 56, and a partition member 70 is stretched between the plurality of spacer members 73. That is, the partition member 70 is stretched between the plurality of spacer members 73 in a state where a predetermined tension is applied around and inside the first fixing member 41. For bonding the partition member 70 and the spacer member 73, for example, a silicone-based double-sided tape having high heat resistance can be used.

Such a partition member 70 is arranged around and inside the outside of the first fixing member 41 as a heat shield member. The partition member 70 arranged around the outside of the first fixing member 41 is arranged as the first heat shield member 71. Further, the partition member 70 arranged inside the first fixing member 41 (inside the fixing belt 48) is arranged as the second heat shield member 72. The first heat shield member 71 and the second heat shield member 72 may be formed of the same material or may be formed of different materials. For example, since the inside of the first fixing member 41 is in a higher temperature state than the outside, a material having a higher thermal deformation temperature than the first heat shield member 71 is used as the material of the second heat shield member 72. Is also good. Here, the heat distortion temperature is one of the index values indicating the heat resistance of the resin, and refers to the temperature at which a predetermined deformation occurs when the temperature is raised at a constant speed under a constant load, and is the deflection temperature under load. Is synonymous with.

FIG. 3 is an enlarged view showing the partition member 70 attached to the member to be heated 50. In order for the partition member 70 to effectively exert the above-mentioned two functions, it is required to satisfy the following four conditions. First, the heat capacity of the partition member 70 is small. Second, the thermal conductivity of the base material in the partition member 70 is low. Thirdly, the reflectance of radiant heat on the surface of the partition member 70 is high. Fourth, the partition member 70 itself has heat resistance. By satisfying these four conditions, the partition member 70 functions as an effective heat shield member.

Therefore, as shown in FIG. 3, the partition member 70 is supported by the spacer member 73 in a state of floating from the surface of the heated member 50, and the space 59 having an air layer between the partition member 70 and the heated member 50. Is forming. Since the space 59 exists between the partition member 70 and the member 50 to be heated, heat is not directly conducted from the partition member 70 to the member 50 to be heated, so that the member 50 to be heated becomes hot. I'm preventing it.

When the partition member 70 is configured as the first heat shield member 71, the first resin film 74 is used as the base material. When the partition member 70 is configured as the second heat shield member 72, the second resin film 75 is used as the base material. By using the first resin film 74 and the second resin film 75 as the base material, the above-mentioned first condition and second condition can be satisfied. For example, the thermal conductivity of SPCC (cold rolled steel sheet), which is a general-purpose sheet metal, is 65 W / m · K, whereas the thermal conductivity of a resin film is generally 0.5 W / m · K or less. .. As the first resin film 74 and the second resin film 75, it is preferable to use a thin film having a thickness of 200 μm or less.

On the other hand, the resin film itself has a low reflectance of radiant heat. Therefore, the partition member 70 forms a metal reflecting surface 76 with respect to the surfaces of the first resin film 74 and the second resin film 75, which are the base materials. The metal reflecting surface 76 may be formed, for example, by attaching an aluminum foil to the surfaces of the first resin film 74 and the second resin film 75, or may be formed as an aluminum vapor-deposited film. .. By providing such a thin-film metal reflecting surface 76, the first heat shield member 71 and the second heat shield member 72 can reflect the radiant heat H with high reflectance as shown in FIG. 3, as described above. The third condition is satisfied.

Further, the first resin film 74 and the second resin film 75 are required not to be deformed by the heat radiated by the fixing member 40. Therefore, the heat deformation temperature of the first resin film 74, which is the base material of the first heat shield member 71 arranged around the outside of the first fixing member 41, is such that the fixing device 4 heat-treats the sheet 9. It is preferable that the temperature is equal to or higher than the set temperature set in. Further, the heat deformation temperature of the second resin film 75, which is the base material of the second heat shield member 72 arranged inside the first fixing member 41, is equal to or higher than the heat deformation temperature of the resin base material of the fixing belt 48. Is preferable. By setting the thermal deformation temperatures of the first resin film 74 and the second resin film 75 in this way, the first heat shield member 71 and the second heat shield member 72 have sufficient heat resistance. The above-mentioned fourth condition is satisfied.

Here, the relationship between the general resin material and the thermal deformation temperature is as shown in Table 1 below.

For example, when the set temperature set for the fixing device 4 to heat-treat the sheet 9 is 135 ° C., the polycarbonate in Table 1 is used as the first resin film 74 which is the base material of the first heat shield member 71. (PC) One resin material may be selected from the following plurality of resin materials.

Further, in the case of the second resin film 75, which is the base material of the second heat shield member 72 arranged inside the first fixing member 41, heat resistance at a higher temperature than that of the first heat shield member 71 is required. Become. In particular, when a jam or the like occurs in the image forming apparatus 1 and the operation of the fixing apparatus 4 is stopped urgently, the inside of the fixing belt 48 may be in an extremely high temperature state such as 230 ° C. As the resin base material of the fixing belt 48, a material that retains its original shape without being deformed even in such a high temperature state is used, and for example, polyimide (PI) or the like is adopted. Therefore, even for the second resin film 75, which is the base material of the second heat shield member 72, it is sufficient to select one of the resin materials of polyamide-imide (PAI) and polyimide (PI) in Table 1. Heat resistance can be obtained. Since polyamide-imide is more expensive than polyimide, if polyimide is selected, sufficient heat resistance can be ensured at low cost.

Further, the spacer member 73 may also be formed of a resin material having a low thermal conductivity. In particular, since the spacer member 73 is a member that is directly attached to the member to be heated 50, the partition member 70 (specifically, the first heat shield member 71) is used to keep the heat conduction to the member to be heated 50 low. ), It is more preferable to be formed of a resin material having a lower thermal conductivity. For example, polyphenylene sulfide glass 40% (PPS-GF40) resin or the like can be suitably used as the material of the spacer member 73. In addition, for example, glass cloth, silicone sponge rubber, or the like may be used as the material of the spacer member 73.

FIG. 4 is a diagram showing an example of the spacer member 73. For example, as shown in FIG. 4A, the spacer member 73 is configured by arranging two rod-shaped bodies having a predetermined length in parallel with each other. In this case, both ends of the first heat shield member 71 or the second heat shield member 72 are attached to the upper end surfaces of the two spacer members 73, respectively.

Further, as shown in FIG. 4B, the spacer member 73 has a connecting portion 73b for connecting both ends of two rod-shaped bodies 73a parallel to each other, and has a frame shape as a whole. It doesn't matter. In this case, the peripheral edge of the first heat shield member 71 or the second heat shield member 72 is attached to the upper end surface of the frame shape.

Further, the heat dissipation loss in the fixing device 4 occurs not only around the fixing belt 48 in the normal direction but also around the side of the fixing belt 48. Therefore, the partition member 70 described above is also arranged on the side of the fixing belt 48. FIG. 5 is a perspective view of the fixing member 40 as viewed from diagonally above. As shown in FIG. 5, on the left and right sides of the fixing member 40, a roller support plate 81 for supporting the heating roller 45, the support member 56, and the pressure roller 49, and a heater support plate 82 for supporting the heater 44 are arranged. To. The heater support plate 82 is provided at a position rearward of the roller support plate 81, and supports the heater 44 inside the heating roller 45 via an opening 83 provided in the roller support plate 81. In such a configuration, since the roller support plate 81 and the heater support plate 82 serve as the heated member 50 on the side of the fixing member 40, the surfaces of the roller support plate 81 and the heater support plate 82 (opposing the fixing member 40). The partition member 70 is arranged with respect to the surface). As described above, the partition member 70 is also stretched via the spacer member 73 so as to be separated from the surfaces of the roller support plate 81 and the heater support plate 82.

As described above, in the fixing device 4 of the present embodiment, the partition member 70 is arranged in the space between the heat source portion and the heated member 50 around and inside the fixing member 40, and the partition member 70 is used. The member 50 to be heated is prevented from being in a high temperature state, and the heat radiation loss from the heat source is reduced, so that the effect of reducing the heat radiation loss can be further improved as compared with the conventional case.

(Second Embodiment)
Next, the second embodiment of the present invention will be described. In this embodiment, an example in which the installation mode of the partition member 70 on the outside of the fixing member 40 is different from that of the first embodiment will be described.

FIG. 6 is a cross-sectional view showing a configuration example of the fixing device 4 according to the second embodiment. As shown in FIG. 6, in the fixing device 4 of the present embodiment, a frame member 85 is arranged around the fixing belt 48 on the outside of the first fixing member 41, and the surface of the frame member 85 facing the fixing belt 48. It has a heat-shielding structure in which a partition member 70 is stretched.

FIG. 7 is a perspective view showing a configuration example of the frame member 85. The frame member 85 includes a plurality of first frames 86 arranged along the width direction of the fixing belt 48, and a plurality of second frames 87 connecting between two adjacent first frames 86, as a whole. It has a U-shaped gutter shape. The partition member 70 is stretched on the inner surface side of the frame member 85. Further, as in the first embodiment, for example, a silicone-based double-sided tape having high heat resistance can be used for adhering the partition member 70 and the frame member 85.

Such a frame member 85 is preferably formed of a resin material having a low thermal conductivity. However, on the other hand, in terms of strength and mounting accuracy, it is preferably formed of a metal material. For example, if a gap of about 2 to 5 mm can be secured between the fixing belt 48 and the partition member 70, high strength and mounting accuracy are not important, so a frame member 85 made of a resin material may be used. On the other hand, when the gap between the fixing belt 48 and the partition member 70 is less than 2 mm, the frame member 85 is required to have high strength and mounting accuracy. In that case, the frame member 85 made of a metal material may be used.

Mounting portions 88 for mounting on the spacer member 73 are provided at both ends of each first frame 86. The frame member 85 is attached to the spacer member 73 via its attachment portion 88. Then, the spacer member 73 is attached to the roller support plates 81 arranged on both the left and right sides of the fixing member 40. For example, the spacer member 73 is a member having a low thermal conductivity and is made of a resin material such as polycarbonate (PC).

FIG. 8 is an enlarged view showing the connection portion between the frame member 85 and the roller support plate 81. As shown in FIG. 8, the mounting portion 88 of the frame member 85 is fixed to the spacer member 73 by the screw member 91. The tip of the screw member 91 stays inside the spacer member 73 and does not come into contact with the roller support plate 81. Therefore, even if the frame member 85 is in a high temperature state, the heat of the frame member 85 is not directly conducted to the roller support plate 81 via the screw member 91.

Further, the spacer member 73 is fixed at a predetermined position on the roller support plate 81 by the screw member 92. The screw member 92 fixes the spacer member 73 to the roller support plate 81 without contacting the frame member 85. Therefore, even if the frame member 85 is in a high temperature state, the heat of the frame member 85 is not directly conducted to the roller support plate 81 via the screw member 92.

As described above, in the fixing device 4 of the present embodiment, the partition member 70 is arranged in the space between the first fixing member 41 and the heated member 50 by using the frame member 85. By using such a frame member 85, the partition member 70 can be relatively easily attached to the periphery of the fixing member 40, and the number of parts arranged around the fixing member 40 can be reduced. There are advantages.

In this embodiment, the configurations other than those described above are the same as those described in the first embodiment.

(Modification example)
The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the contents described in each of the above embodiments, and various modifications can be applied.

For example, in the above embodiment, a configuration example in which the partition member 70 is not provided for the support member 54 and the guide member 55 arranged close to each other around the pressure roller 49 has been described. However, the present invention is not limited to this, and adopts a configuration in which the partition member 70 is provided even if the anti-fixing member is provided on the support member 54 and the guide member 55 arranged close to each other around the pressure roller 49. You may.

Further, in the above embodiment, a configuration example in which the fixing belt 48 is provided on the first fixing member 41 has been described. However, the first fixing member 41 may not necessarily include the fixing belt 48. For example, the first fixing member 41 has only a heating roller 45 in which a heater 44 is arranged inside, and the heating roller 45 comes into contact with the pressurizing roller 49 to form a nip portion P between the heating roller 49 and the pressurizing roller 49. It may be formed.

Further, the heated member 50 arranged around the fixing member 40 in the above embodiment is only an example, and a heated member 50 different from the member described in the above embodiment is arranged around the fixing member 40. If so, the partition member 70 may be arranged in the space between such a member and the fixing member 40.

1 Image forming device 4 Fixing device 40 Fixing member 41 First fixing member 42 Second fixing member 44 Heater (heat source)
48 Fixing belt 50 Heated member 51, 52, 53, 54, 56 Support member (heated member)
55 Guide member (member to be heated)
59 Space 70 Partition member 71 First heat shield member (partition member)
72 Second heat shield member (partition member)
73 Spacer member 74 First resin film 75 Second resin film 76 Metal reflective surface

Claims (10)

A fixing member having a heat source and fixing the image to the sheet by applying heat treatment and pressure treatment to the sheet on which the image is transferred.
A member to be heated that is arranged around or inside the fixing member in a non-contact state with the fixing member.
A partition member arranged in the space between the fixing member and the heated member,
A fixing device characterized by being provided with. The fixing member is
A first fixing member having the heat source and heating the sheet,
A second fixing member which is arranged to face the first fixing member, forms a nip portion between the first fixing member, and pressurizes the sheet to be passed through the nip portion.
With
The partition member has a first heat shield member arranged in a space between the first fixing member and the heated member arranged around the first fixing member. The fixing device according to 1. The first heat shield member includes a first resin film, and the first heat shield member includes a first resin film.
The fixing device according to claim 2, wherein the thermal deformation temperature of the first resin film is equal to or higher than a set temperature for the heat treatment. The first fixing member is
A heating roller having the heat source and
A fixing belt that is hung on the heating roller and circulates between the first fixing member and the nip portion.
Further prepare
The partition member is a second heat shield member arranged in a space between the first fixing member and the heated member arranged around the first fixing member inside the fixing belt. The fixing device according to claim 2 or 3, wherein the fixing device has. The fixing belt includes a resin base material and has a resin base material.
The second heat shield member includes a second resin film and has a second resin film.
The fixing device according to claim 4, wherein the heat deformation temperature of the second resin film is equal to or higher than the heat deformation temperature of the resin base material. The fixing device according to any one of claims 2 to 5, wherein the partition member has a metal reflecting surface on a surface facing the first fixing member. The fixing device according to any one of claims 1 to 6, wherein the partition member forms an air layer on the back surface side facing the heated member. A plurality of spacer members attached to the heated member,
Further prepare
The fixing device according to any one of claims 1 to 7, wherein the partition member is supported in a state of being stretched by the plurality of spacer members. The fixing device according to claim 8, wherein each of the plurality of spacer members is a member having a lower thermal conductivity than the partition member. The fixing device according to any one of claims 1 to 9,
An image forming unit that transfers an image to a sheet and conveys the sheet to the fixing device.
An image forming apparatus comprising.

Images