Fixing apparatus and image forming apparatus

Abstract

This fixing device, with its simple structure, achieves suppression of excessive temperature rise in the non-paper-feeding section of the heating roller while minimizing cooling of the paper-feeding section. [Solution] The fixing unit 13 comprises a heating roller 31, a heating device 52 positioned inside the heating roller 31 to heat the heating roller 31, a pressure roller 32 positioned opposite the heating roller 31 and forming a nip portion N through which the paper to be fixed P is inserted between the heating roller 31 and the pressure roller 31, a transport guide member 61 that guides the paper P to the nip portion N and is provided with a gap G between it and the pressure roller 32, and a blower member 71. The blower member 71 is positioned in a region on the pressure roller 32 side of the transport guide member 71 in the direction in which the heating rollers 31 and 32 are aligned, and blows air from the gap between the pressure roller 32 and the transport guide member 71 to the heating unit 51.

Description

Technical Field

[0001] The present invention relates to a fixing device that thermally presses and fixes an image formed on a recording medium, and an image forming apparatus including the fixing device.

Background Art

[0002] An electrophotographic image forming apparatus includes a fixing device that fixes a toner image transferred onto a recording medium. The fixing device generally includes a heating roller that includes a heating member and a heating device that heats the heating member, a pressure roller that is disposed opposite to the heating member and forms a nip portion through which a recording medium to be fixed is inserted between the heating roller, and a conveyance guide member that guides the recording medium to the nip portion and is provided with a gap between the pressure roller in the conveyance direction of the recording medium. In the nip portion, there is a device that fixes the toner image onto the recording medium by heating and pressurizing (thermal pressure bonding).

[0003] In an image forming apparatus including a fixing device in which a heating roller contacts a recording medium, for example, when continuously printing on a small-sized recording medium, the area where the recording medium does not pass through the heating roller (non-paper passing portion) will be heated excessively. When the non-paper passing portion is overheated, there is a problem that the components of the fixing device are damaged by heat.

[0004] As a means for solving the above problems, in order to suppress excessive temperature rise of the non-paper passing portion of the heating roller, for example, an image forming apparatus including a blowing member that blows air toward the heating roller is disclosed in Patent Document 1. The image forming apparatus disclosed in Patent Document 1 includes an end temperature rise cooling device that cools the end portions of the heating roller, which is disposed in the region on the side of the heating roller of the recording medium. The end temperature rise cooling device includes an end cooling duct and a cooling fan near both end portions in the orthogonal direction orthogonal to the conveyance direction of the recording medium of the heating roller. The end temperature rise cooling device blows air when a small-sized recording medium continuously passes through the nip portion formed by the heating roller and the pressure roller, cools the non-paper passing portion of the heating roller, and suppresses the temperature rise.

[0005] In the above-described edge heating and cooling device, a duct shutter is positioned inside the cooling duct, and by moving the duct shutter, the airflow width of the air outlet in a direction perpendicular to the conveying direction of the recording medium can be changed. By adjusting the airflow width to match the width of the non-paper-passing section, it is possible to suppress the cooling of the area of ​​the heating roller through which the recording medium passes (paper-passing section) while suppressing excessive temperature rise in the non-paper-passing section of the heating roller. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2014-224992 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the above-described edge heating and cooling device has the problem that, in order to suppress the cooling of the paper-feeding portion of the heating roller while suppressing excessive temperature rise in the non-paper-feeding portion of the heating roller, the airflow width of the air outlet is adjusted by a duct shutter, which makes the structure of the edge heating and cooling device complex due to the presence of components such as duct shutters.

[0008] The present invention has been made in view of the above circumstances, and aims to achieve, with a simple structure, that the cooling of the paper-feeding portion of the heating roller is suppressed while suppressing excessive temperature rise in the non-paper-feeding portion of the heating roller. [Means for solving the problem]

[0009] A fixing device according to one aspect of the present invention comprises a heating roller, a heating device disposed inside the heating roller and heating the heating roller, a pressure roller disposed opposite the heating roller and forming a nip portion through which a recording medium to be fixed is inserted between the heating roller and the pressure roller, a transport guide member that guides the recording medium to the nip portion and is provided with a gap between it and the pressure roller in the direction in which the recording medium is guided, and a blower member, wherein the blower member is disposed in a region on the pressure roller side of the transport guide member in the direction in which the heating roller and the pressure roller are aligned, and blows air from the gap between the pressure roller and the transport guide member toward the heating roller.

[0010] Furthermore, an image forming apparatus according to another aspect of the present invention comprises an image forming unit that forms a toner image, and a fixing device that fixes the toner image formed by the image forming unit onto the surface of the recording medium. [Effects of the Invention]

[0011] According to the present invention, the blower member of the fixing device is positioned in a region on the pressure roller side of the transport guide member in the direction in which the heating roller and the pressure roller are aligned, and the blower member blows air from the gap between the pressure roller and the transport guide member toward the heating roller. As a result, the recording medium acts as a windbreak for the paper passage portion of the heating roller (the region through which the recording medium passes on the heating roller), suppressing the cooling of the paper passage portion by the air blower member. At the same time, the air blown by the blower member passes through the gap between the pressure roller and the transport guide member and hits the non-paper passage portion of the pressure roller (the region through which the recording medium does not pass), thereby suppressing excessive temperature rise in the non-paper passage portion. Thus, suppressing the cooling of the paper passage portion of the pressure roller while suppressing excessive temperature rise in the non-paper passage portion of the pressure roller can be achieved with a fixing device of a simple structure in which the blower member is positioned in a region on the pressure roller side of the transport guide member in the direction in which the heating roller and the pressure roller are aligned, and the blower member blows air from the gap between the pressure roller and the transport guide member toward the pressure roller. [Brief explanation of the drawing]

[0012] [Figure 1] This is a cross-sectional view showing the configuration of an image forming apparatus equipped with a fixing unit according to one embodiment of the present invention. [Figure 2] Figure 1 is a functional block diagram showing the electrical configuration of the image forming apparatus. [Figure 3] Figure 1 is a cross-sectional view showing the configuration of the fixing section. [Figure 4] Figure 3 is a schematic diagram showing the configuration of the fixing section. [Figure 5] Figure 3 is a schematic diagram showing the size of the heating device provided in the fixing section. [Figure 6] This figure shows a schematic representation of the temperature distribution of the heating rollers in the fixing section of Figure 3. [Figure 7] Figure 2 is a flowchart showing the control process by the control unit. [Modes for carrying out the invention]

[0013] Hereinafter, a fixing unit according to one embodiment of the present invention and an image forming apparatus equipped with said fixing unit will be described with reference to the drawings.

[0014] Figure 1 is a cross-sectional view showing the configuration of an image forming apparatus 1 equipped with a fixing unit 13 according to one embodiment of the present invention. Figure 2 is a functional block diagram showing the electrical configuration of the image forming apparatus 1 of Figure 1. The image forming apparatus 1 is a multifunction device equipped with multiple functions such as a copy function, a transmission function, a printer function, and a facsimile function.

[0015] As shown in Figure 1, the image forming apparatus 1 comprises a document transport unit 6, a document reading unit 11, an image forming unit 12, a fixing unit 13, a paper feeding unit 14, a display unit 15, an operation unit 16, and a transport unit 17.

[0016] The original document conveying unit 6 conveys the original documents placed on the original document table one by one to the reading position of the image reading unit 11. The original document conveying unit 6 is configured to be able to open and close the platen glass 7 by rotating in the vertical direction around the support shaft on the back side of the paper surface in FIG. 1. The original document conveying unit 6 also functions as a cover that presses the original document on the platen glass 7 from above.

[0017] The image reading unit 11 is a scanner that optically reads an original document and generates image data indicating the original document image. The image reading unit 11 reads the original document conveyed by the original document conveying unit 6 or the original document placed on the platen glass 7.

[0018] The image forming unit 12 includes a photosensitive drum, a charging device, an exposure device, a developing device, and a transfer device. The exposure device includes an LSU (Laser Scanning Unit). The image forming unit 12 forms a toner image on the paper P conveyed along the conveyance path T by the conveyance unit 17 based on the image data. When performing color printing, the magenta image forming unit 12M, the cyan image forming unit 12C, the yellow image forming unit 12Y, and the black image forming unit 12Bk of the image forming unit 12 form magenta, cyan, yellow, and black toner images on the photosensitive drum 121 through the processes of charging, exposure, and development. The formed toner images of each color are transferred onto the intermediate transfer belt 125 by the primary transfer roller 126 and overlapped to form a color toner image. The overlapped color toner image is transferred onto the paper P conveyed in the conveyance path T by the secondary transfer roller 127. When performing monochrome printing, the black image forming unit 12Bk of the image forming unit 12 forms a black toner image on the photosensitive drum 121 through the processes of charging, exposure, and development. The formed black toner image is transferred onto the intermediate transfer belt 125 by the primary transfer roller 126. The monochrome toner image transferred onto the intermediate transfer belt 125 is transferred onto the paper P conveyed in the conveyance path T by the secondary transfer roller 127.

[0019] The fixing unit 13 heats and presses the sheet P on which the toner image is formed to fix the toner image on the sheet P. The sheet P on which the toner image is fixed is discharged to the discharge tray 8.

[0020] The paper feeding unit 14 includes a manual feed tray and a plurality of paper feeding cassettes. The paper feeding unit 14 pulls out the sheets P stored in any of the plurality of paper feeding cassettes or the sheets placed on the manual feed tray one by one by a pickup roller and feeds them to the conveyance path T. Note that the sheet P is not limited to a paper medium and may be, for example, an OHP (Overhead Projector) sheet. The sheet P and the OHP sheet are an example and another example of the recording medium in the claims.

[0021] The display unit 15 includes a liquid crystal display or an organic EL (Organic Light-Emitting Diode) display. The display unit 15 displays various screens. The operation unit 16 includes a plurality of hard keys such as a start key for inputting an execution start instruction for copy processing or scan processing, etc., and a touch panel disposed over the display unit 15. Instructions from the user are input to the operation unit 16.

[0022] The conveyance unit 17 includes a pair of conveyance rollers 17A, a pair of discharge rollers 17A, a registration roller 17C, etc., and a conveyance motor. When the pair of conveyance rollers 17A, the pair of discharge rollers 17B, the registration roller 17C, etc. rotate by driving of the conveyance motor, the sheet P fed by the paper feeding unit 14 is conveyed along the conveyance path T to the image forming unit 12, the fixing unit 13, etc.

[0023] As shown in FIG. 2, the image forming apparatus 1 further includes a control unit 10, a storage unit 18, an image processing unit 19, an image memory 20, a facsimile communication unit 21, and a communication unit 22.

[0024] The control unit 10 is electrically connected to the document transport unit 6, image reading unit 11, image forming unit 12, fixing unit 13, paper feeding unit 14, display unit 15, operation unit 16, transport unit 17, storage unit 18, image processing unit 19, image memory 20, facsimile communication unit 21, and communication unit 22.

[0025] The control unit 10 controls the operation of each part of the image forming apparatus 1.

[0026] The storage unit 18 is a large-capacity storage device for storing various types of data, such as an HDD (Hard Disk Drive) or SSD (Solid State Drive), and stores various computer programs, such as various control programs, for realizing the operation of the image forming apparatus 1.

[0027] The image processing unit 19 performs image processing (rasterization, color conversion, rotation / aggregation, resolution conversion, screen processing, etc.) on the image data. The image memory 20 temporarily stores the image data. The facsimile communication unit 21 transmits and receives image data via a public network. The communication unit 22 includes a communication module such as a LAN (Local Area Network) board. The control unit 10 communicates data with external devices such as a host PC (Personal Computer) 23 connected to the network via the communication unit 22.

[0028] The control unit 10 includes a processor, RAM (Random Access Memory), and ROM (Read Only Memory), etc. The processor is, for example, a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), or an ASIC (Application Specific Integrated Circuit).

[0029] The control unit 10 functions as a control unit 100 that controls the operation of the document transport unit 6, document reading unit 11, image forming unit 12, fixing unit 13, paper feeding unit 14, display unit 15, operation unit 16, and transport unit 17, etc., by having the control program etc. stored in the ROM or storage unit 18 executed by the processor. The fixing unit 13 and the part of the control unit 100 that controls the operation of the fixing unit 13 constitute an example of a fixing device within the scope of the claims.

[0030] When the image forming apparatus 1 performs a document reading operation, under the control of the control unit 100, the document reading unit 11 optically reads the image of the document being transported by the document transport unit 6 or the document placed on the platen glass 7, and generates image data. The image data generated by the document reading unit 11 is stored in the image memory 20.

[0031] When the image forming apparatus 1 performs an image forming operation, under the control of the control unit 100, the image processing unit 19 performs image processing on the image data generated by the document reading operation and stored in the image memory 20, the image data stored in the storage unit 18, or the image data received from a network-connected computer. The image forming unit 12 then forms a toner image on the paper P fed from the paper feeding unit 14 based on the image data processed by the image processing unit 19. Under the control of the control unit 100, the fixing unit 13 heats and pressurizes the paper P on which the toner image has been formed to fix the toner image to the paper P. The paper P, on which the fixing process is complete, is discharged into the discharge tray 8.

[0032] Figure 3 is a cross-sectional view showing the configuration of the fixing unit 13 in Figures 1 and 2. Figure 4 is a schematic diagram showing the configuration of the fixing unit 13 in Figure 3. Figure 5 is a schematic diagram showing the size of the heating device 52 included in the fixing unit 13 in Figure 3.

[0033] The fixing unit 13 comprises a heating roller 31, a pressure roller 32, a housing 34, and a rotary drive unit 41 (see Figure 2). The heating roller 31 and the pressure roller 32 are housed within the resin housing 34.

[0034] The pressure roller 32 is constructed, for example, by providing an elastic layer of silicone rubber to an iron core and coating its outer surface with a 50 μm thick PFA resin film. The pressure roller 32 is pivotally supported within the housing 34 so as to be rotatable counterclockwise in the plane of the paper shown in Figure 3. During the fixing process, the rotation axis 33 of the pressure roller 32 is rotated by a rotation drive unit 41, which consists of a motor or the like, under the control of the control unit 100. The pressure roller 32 is positioned opposite the heating roller 31 (heating element 51 provided on the heating roller 31), forming a nip section N between the heating roller 31 (heating element 51 provided on the heating roller 31) and the pressure roller 32 through which the paper to be fixed is inserted. The heating roller 31 and the pressure roller 32 fix the toner image to the paper P inserted in the nip section N.

[0035] The heating roller 31 comprises a cylindrical belt-shaped heating element 51, and a heating device 52, a temperature sensor 53, a holding element 54, and a pressing element 55, etc., disposed inside the heating element 51.

[0036] The heating element 51 is constructed, for example, by coating the inner and outer surfaces of a stainless steel belt with an outer diameter of 30 mm and a thickness of 0.03 mm with fluororesin. The heating element 51 is pivotally supported within the housing 34 so as to be rotatable clockwise in the plane of Figure 3. The heating element 51 is pressed against the pressure roller 32 by a pressing member 55 made of a heat-resistant resin pad, and rotates in conjunction with the rotation of the pressure roller 32.

[0037] The heating device 52 is positioned inside the heating roller 31 and heats the heating roller 31; for example, it is a ceramic heater. More specifically, the heating device 52 is positioned inside the heating element 51, facing the inner circumferential surface of the heating element 51, and heats the inner circumferential surface of the heating element 51. The heating device 52 performs heating operations during the fixing process under the control of the control unit 100 and stops heating operations after the fixing process is completed.

[0038] The holding member 54 holds the heating device 52. For example, the holding member 54 holds the heating device 52 in a state where the heating device 52 is housed in a recess that is sized to accommodate the heating device 52.

[0039] The temperature sensor 53 is, for example, a thermistor, and faces the heating device 52. It detects the temperature of the heating device 52 and outputs a detection signal indicating the temperature value of the heating device 52 to the control unit 100. The temperature sensor 53 is inserted into a through hole formed in the holding member 54 and contacts the heating device material 52.

[0040] Furthermore, the fixing unit 13 is equipped with a transport guide member 61. The transport guide member 61 is, for example, a flat plate and is a guide member that guides the paper P moving from the transport path T toward the fixing unit 13 toward the nip section N, and is provided with a gap G between it and the pressure roller 32 in the direction of guiding the paper P.

[0041] Furthermore, the fixing unit 13 is equipped with a blower member 71.

[0042] The blower member 71 is, for example, a fan and includes blower member 71A and blower member 71B. As shown in Figure 3, one of the blower members 71A is located in a region that is on the side of the pressure roller 32 than the transport guide member 61 in the direction in which the heating roller 31 and the pressure roller 32 are aligned, and is located in a region outside one end 61A of the transport guide member 61 in an orthogonal direction (indicated by arrow D in Figure 4) that is perpendicular to the direction in which the transport guide member 61 guides the recording medium such as paper P (indicated by arrow C in Figure 4). Furthermore, as shown in Figure 3, the other blower member 71B is located in a region that is on the side of the pressure roller 32 than the transport guide member 61 in the direction in which the heating roller 31 and the pressure roller 32 are aligned, and is positioned in a region outside the other end 61B of the transport guide member 61 in an orthogonal direction (indicated by arrow D in Figure 4) that is perpendicular to the direction in which the transport guide member 61 guides the recording medium such as paper P (indicated by arrow C in Figure 4).

[0043] To put it another way, each blower member 71A, 71B is positioned in the region where the pressure roller 32 is located, which is one of two regions separated by a plane that includes the surface of the transport guide member 61 facing the paper P to be fixed and the surface opposite to it. Furthermore, each blower member 71A, 71B is positioned in the region outside the ends 61A, 61B of the transport guide member 61, which does not overlap with the surface of the transport guide member 61 when the surface of the transport guide member 61 facing the paper P to be fixed is viewed from a direction perpendicular to that opposite surface.

[0044] As shown in Figure 3, each blower member 71A, 71B blows air from the gap G between the pressure roller 32 and the transport guide member 61 to the heating roller 31 (the heating element 51 provided on the heating roller 31) (in the direction indicated by arrow A in Figure 3), and as shown in Figure 4, blows air toward the center of the transport guide member 61 in an orthogonal direction (in the direction indicated by arrow D in Figure 4) that is perpendicular to the direction in which the transport guide member 61 guides the recording medium such as paper P (in the direction indicated by arrow C in Figure 4) (in the direction indicated by arrows B1, B2 in Figure 4). The blower member 71 is provided to a predetermined length such that the range of air blowing in the orthogonal direction is greater than or equal to the length of the heating device 52 in the orthogonal direction. In other words, the two blower members 71A, 71B are provided to a predetermined length such that the combined air blowing range of the two blower members 71A, 71B in the orthogonal direction is greater than or equal to the length of the heating device 52 in the orthogonal direction.

[0045] Each air blower 71 sends air to the heating roller 32 through the gap G between the pressure roller 32 and the transport guide member 61. This causes the recording medium, such as paper P, to act as a windbreak for the paper-passing section of the heating roller 31 (the area through which the recording medium passes), preventing the air blown by the air blower 71 from hitting the paper-passing section of the heating roller 31. However, the recording medium, such as paper P, does not act as a windbreak for the non-paper-passing section of the heating roller 31 (the area through which the recording medium does not pass), so the air blown by the air blower 71 hits the non-paper-passing section of the heating roller 31.

[0046] Each blower member 71 blows air toward the center of the transport guide member 61 in the orthogonal direction, allowing the air blown by the blower members 71 to be efficiently directed towards the part of the heating roller 31 that is close to the paper-feeding section of the non-paper-feeding section.

[0047] Depending on the arrangement and direction of each air blower 71 as described above, the temperature distribution of the heating roller 31 when air is blown from the air blower 71 ("with cooling" in Figure 6) is compared with the temperature distribution of the heating roller 31 when air is not blown from the air blower 71 ("without cooling" in Figure 6), as shown in Figure 6. The temperature of the paper-feeding section, where the recording medium acts as an air shield, is approximately the same. The temperature of the non-paper-feeding section, where the recording medium does not act as an air shield and the air from each air blower 71 hits, decreases, and the temperature of the part of the non-paper-feeding section that is close to the paper-feeding section, where the air blown by the air blower 71 hits efficiently, decreases significantly.

[0048] As shown in Figure 5, the heating device 52 described above is provided such that the size S1 of the heating device 52 in the orthogonal direction (indicated by arrow D in Figure 5) perpendicular to the direction in which the transport guide member 61 guides the recording medium such as paper P (indicated by arrow C in Figure 5) corresponds to a predetermined size S2 of the recording medium such as paper P in the same orthogonal direction (indicated by arrow D in Figure 5). In this embodiment, a heating device 52 whose size S1 is approximately equal to the size S2 of the recording medium is used in the fixing unit 13. The predetermined recording medium such as paper P is a recording medium of a size that is expected to be used frequently.

[0049] The control unit 100 prevents the blower member 71 from performing an air blowing operation if the size of the paper P to be fixed in the orthogonal direction perpendicular to the guidance direction of the paper P of the transport guide member 61 (the direction indicated by arrow C in Figure 5) is greater than or equal to the length S1 of the heating device 52 in the orthogonal direction. If the size of the paper P to be fixed in the orthogonal direction is less than the length S1 of the heating device 52 in the orthogonal direction, the blower member 71 performs an air blowing operation. In other words, under the control of the control unit 100, the blower member 71 does not perform an air blowing operation if the size of the paper P to be fixed in the orthogonal direction perpendicular to the guidance direction of the paper P of the transport guide member 61 (the recording medium through which the nip portion N formed by the heating roller 31 and the pressure roller 32 is inserted) is greater than or equal to the length S1 of the heating device 52 in the orthogonal direction. On the other hand, the air blower 71, under the control of the control unit 100, performs an air blowing operation if the size of the recording medium such as paper P to be fixed in the orthogonal direction perpendicular to the guidance direction of the transport guide member 61 for the recording medium such as paper P is less than the length S1.

[0050] The control of the control unit 100 with respect to the fixing unit 13 described above will be explained below. For example, the control unit 100 drives the heating device 52 using PID (Proportional-Integral-Differential Controller) control so that the temperature detected by the temperature sensor 53 reaches a predetermined target temperature. The control unit 100 supplies power to the heating device 52, and when the temperature detected by the temperature sensor 53 rises above the target temperature, it reduces the power supplied to the heating device 52. Subsequently, when the detected temperature falls below the target temperature, it increases the power supplied to the heating device 52.

[0051] Figure 7 is a flowchart showing the control process by the control unit 100.

[0052] The control unit 100 determines, based on the print settings, whether the size of the recording medium such as paper P that is to be fixed in the orthogonal direction perpendicular to the guidance direction of the transport guide member 61 is greater than or equal to the length S1 of the heating device 52 in the orthogonal direction (step S1).

[0053] In the determination process of step S1, if the control unit 100 determines that the size of the recording medium such as the paper P to be fixed is greater than or equal to the length S1 (S1: YES), the control unit 100 decides not to perform the blowing operation of the blowing member 71 and does not allow the blowing member 71 to perform the blowing operation (step S2).

[0054] In the determination process of step S1, if the control unit 100 determines that the size of the recording medium such as the paper P to be fixed is less than S1 (S1: NO), the control unit 100 decides to perform the blowing operation of the blowing member 71 and causes the blowing member 71 to perform the blowing operation (step S3).

[0055] According to the above embodiment, the air blowers 71A and 71B of the air blower 71 are positioned in a region on the side of the pressure roller 32 that is closer to the transport guide member 61 than the heating roller 31, in the direction in which the heating roller 31 and the pressure roller 32 are aligned, and the air blowers 71A and 71B blow air from the gap G between the pressure roller 32 and the transport guide member 61 to the heating member 51. As a result, the recording medium acts as a windbreak for the paper-feeding portion of the heating roller 31, suppressing the cooling of the paper-feeding portion by the air blower 71, while the air blower 71 blows through the gap between the pressure roller 32 and the transport guide member 61 and hits the non-paper-feeding portion of the heating roller 31, thereby suppressing an excessive temperature rise in the non-paper-feeding portion. In this way, suppressing the cooling of the paper-feeding portion of the heating roller 31 while suppressing excessive temperature rise in the non-paper-feeding portion of the heating roller 31 can be achieved with a simple fixing unit 13 structure in which the blowing members 71A and 71B are positioned in a region on the pressure roller 32 side of the transport guide member 61 in the direction in which the heating roller 31 and the pressure roller 32 are aligned, and the blowing member 71 blows air from the gap G between the pressure roller 32 and the transport guide member 61 to the heating roller 31.

[0056] Furthermore, one blower member 71A is positioned in the area outside one end 61A of the transport guide member 61 in a direction perpendicular to the direction in which the transport guide member 61 guides the recording medium, and blows air toward the center of the transport guide member 61 in the aforementioned perpendicular direction. The other blower member 71B is positioned in the area outside the other end 61B of the transport guide member 61 in a direction perpendicular to the direction in which the transport guide member 61 guides the recording medium, and blows air toward the center of the transport guide member 61 in the aforementioned perpendicular direction. This allows the air from the blower members 71 to be directed towards the part of the heating roller 31 closest to the paper-feeding section of the non-paper-feeding section, which is most prone to temperature rise, thereby preventing excessive temperature rise of the heating roller 31.

[0057] Furthermore, by setting the airflow range in the orthogonal direction perpendicular to the guidance direction of the recording medium by the transport guide member 61 of the air blower member 71 (the combined airflow range of the two airflow ranges of the air blowers 71A and 71B in the orthogonal direction) to be longer than the length of the heating device 52 in the orthogonal direction, the non-paper-passing portion of the heating roller 31 can be cooled even when a small recording medium less than the length S1 of the heating device 52 in the orthogonal direction is transported.

[0058] Furthermore, if the size of the recording medium, such as paper P, to be fixed in the orthogonal direction perpendicular to the guidance direction of the transport guide member 61 is greater than or equal to the length S1 of the heating device 52 in the orthogonal direction, there is no heating device 52 in the area corresponding to the non-paper-passing portion of the heating roller 31, so there is no need to cool the non-paper-passing portion of the heating roller 31. However, if the size of the recording medium, such as paper P, to be fixed in the orthogonal direction is less than the length S1 of the heating device 52 in the orthogonal direction, there is a heating device 52 in the area corresponding to the non-paper-passing portion of the heating roller 31, so it is necessary to cool the non-paper-passing portion of the heating roller 31. In the former case, the blower member 71 is not made to blow air, and only in the latter case is the blower member 71 made to blow air. This makes it possible to reduce the power consumption of the fixing unit 13.

[0059] It should be noted that the present invention is not limited to the configuration of the above embodiments and various modifications are possible. Furthermore, the configuration and process shown in the above embodiments using Figures 1 to 7 are merely one embodiment of the present invention and are not intended to limit the present invention to such configuration and process. [Explanation of Symbols]

[0060] 1. Image forming apparatus 12 Image forming unit 31 Heating rollers 32 Pressure Rollers 51 Heating element 52 Heating device 61 Conveyor guide member 71 Air blower 100 Control Unit

Claims

1. Heating rollers, A heating device provided on the heating roller, which is positioned inside the heating roller and heats the heating roller, A pressure roller is positioned opposite the heating roller and forms a nip portion through which the recording medium to be fixed is inserted between it and the heating roller, A transport guide member is provided to guide the recording medium to the nip portion, with a gap between it and the pressure roller in the direction in which the recording medium is guided, Blower component, Equipped with, The blowing member is positioned in a region that is closer to the pressure roller than the transport guide member in the direction in which the heating roller and the pressure roller are aligned, and blows air from the gap between the pressure roller and the transport guide member toward the heating roller. Fixing device.

2. The fixing device according to claim 1, wherein the blowing member is positioned in an area outside the end of the transport guide member in a direction perpendicular to the direction in which the transport guide member guides the recording medium, and blows air toward the center of the transport guide member in the direction perpendicular to the direction perpendicular to the direction perpendicular to the transport guide member.

3. The heating roller is equipped with a heating element that is shaped like a cylindrical belt, The fixing device according to claim 1, wherein the heating device is disposed inside the heating member and heats the inner circumferential surface of the heating member.

4. The system further includes a control unit that drives and controls the air blowing operation of the aforementioned air blowing member. The control unit, If the size of the recording medium to be fixed in the orthogonal direction is greater than or equal to the length of the heating device in the orthogonal direction, the blowing member will not perform the blowing operation. If the size of the recording medium to be fixed in the orthogonal direction is less than the length of the heating device, the blowing member is made to perform a blowing operation. The fixing device according to claim 1.

5. The fixing device according to claim 1, wherein the blowing member is provided to a predetermined length such that the range of blowing air in the orthogonal direction is greater than or equal to the length of the heating device in the orthogonal direction.

6. An image forming unit that forms a toner image, An image forming apparatus comprising a fixing device according to any one of claims 1 to 5, which fixes a toner image formed by the image forming unit onto the surface of the recording medium.

Images