JP5116422B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a printer, a facsimile, or a multifunction machine thereof, and a fixing device installed therein.

Conventionally, in an image forming apparatus such as a copying machine or a printer, a fixing member such as a fixing roller and a pressure belt are pressed against each other to form a nip portion, and a recording medium carrying a toner image on the nip portion is formed. A fixing device that transports and fixes a toner image on a recording medium is known (see, for example, Patent Document 1 and Patent Document 2).
Specifically, in Patent Document 1 and the like, a nip portion is formed by pressing a pressure pad (pressure pad) against a fixing roller via a pressure belt (endless belt).
Such a fixing device using a pressure pad and a pressure belt has a relatively small number of parts, and can sufficiently secure the nip width in the conveyance direction at the nip portion without complicating and increasing the size of the device. Since the amount of heat taken away from the fixing member can be reduced by setting the heat capacity of the pressure belt small, better fixability can be obtained as compared with an apparatus using a pressure roller.

  On the other hand, Patent Document 1 discloses a technique for installing a sheet-like member (low friction sheet) between a pressure belt and a pressure pad for the purpose of reducing the frictional resistance of the pressure belt. Yes. In Patent Document 1 and the like, the sheet-like member is fixed on the side surface of the support member (peeling nip member) by a low friction sheet fixing member at a position away from the nip portion.

JP 2006-65218 A JP 2006-267409 A

  When the conventional fixing device using the pressure pad and the pressure belt is operated, the sheet-like member installed between the pressure belt and the pressure pad may be wrinkled. . When wrinkles are generated in the sheet-like member, wrinkles are generated on the surface of the pressure belt that forms the nip portion, and wrinkles are generated on the recording medium conveyed through the nip portion. The transportability has deteriorated.

  The present invention has been made to solve the above-described problems, and even when a sheet-like member is installed between the pressure pad and the pressure belt, wrinkles are generated in the sheet-like member. It is another object of the present invention to provide a fixing device and an image forming apparatus that do not cause wrinkles on the recording medium or defective conveyance of the recording medium.

  As a result of repeated researches to solve the above problems, the inventors of the present application fixed (fixed) a sheet-like member so as to be close to the nip portion on the side surface on the upstream side of the nip portion of the support member that supports the pressure pad. As a result, it has been found that wrinkles are less likely to occur in the sheet-like member.

The present invention is based on the above-described matters, that is, the fixing device according to the first aspect of the present invention is a fixing device for fixing a toner image on a recording medium, and heating the toner image. And a pressurizing unit that forms a nip portion to which the recording medium is conveyed in pressure contact with the heating unit, and the pressurizing unit includes an endless belt member that travels in a predetermined direction, and the belt member A pressure pad that is in pressure contact with the heating means, a support member that supports the pressure pad and is biased toward the nip portion together with the pressure pad by a biasing means, and the belt member. A sheet-like member sandwiched between the pressure pads to reduce the frictional resistance of the belt member, and the sheet-like member is close to the nip portion on the upstream side of the nip portion. Belt member Is fixed on the surface of the side surface of the support member erected towards the inside, on the surface side of said support member proximate to the nip portion at the downstream side of the nip portion erected toward the inside of said belt member Is also fixed to the support member such that the fixing force on the side surface downstream of the nip portion is smaller than the fixing force on the side surface upstream of the nip portion .

According to a second aspect of the present invention, there is provided a fixing device for fixing a toner image onto a recording medium, the heating means for heating the toner image, and the recording medium being conveyed in pressure contact with the heating means. A pressurizing unit that forms a nip portion, and the pressurizing unit includes an endless belt member that travels in a predetermined direction, a pressurizing pad that presses against the heating unit via the belt member, and the pressurizing unit. A support member that supports the pressure pad and is urged toward the nip portion together with the pressure pad by the urging means; and is sandwiched between the belt member and the pressure pad, and A sheet-like member that reduces frictional resistance, and the sheet-like member is proximate to the nip portion on the upstream side of the nip portion, and stands on the inner surface of the belt member. Fixed on top The pressurizing means may be fixed to the side surface of the support member across the sheet member is obtained by including a plate-shaped member formed in a dogleg shape.

The fixing device according to a third aspect of the present invention is the fixing device according to the second aspect, wherein the sheet-like member includes a through hole, and the plate-like member is supported by a screw passing through the through hole. It is fastened on the side surface of the member.

According to a fourth aspect of the present invention, in the fixing device according to the second aspect, the side surface of the plate-like member or the support member is provided with a protrusion, and the sheet-like member is a through hole. The plate-like member is fixed on the side surface of the support member by the protrusion passing through the through hole.

The fixing device according to a fifth aspect of the present invention is the fixing device according to any one of the first to fourth aspects, wherein the sheet-like member is close to the nip portion on the upstream side of the nip portion. The support member that is folded and fixed onto the surface of the side surface of the support member that stands up toward the inside of the belt member, and that stands up toward the inside of the belt member in the vicinity of the nip portion on the downstream side of the nip portion. It is also folded and fixed on the surface of the side surface of this.

According to a sixth aspect of the present invention, there is provided the fixing device according to any one of the first to fifth aspects, wherein the pressing means includes a fixing member that holds the urging means. It is.

The fixing device according to a seventh aspect of the present invention is the fixing device according to any one of the first to sixth aspects, wherein the pressurizing unit includes a guide member that holds the posture of the belt member. Is.

The fixing device according to an eighth aspect of the present invention is the fixing device according to any one of the first to seventh aspects, wherein the sheet-like member is a lubricant holding member that holds a lubricant. is there.

The fixing device according to a ninth aspect of the present invention is the fixing device according to any one of the first to eighth aspects, wherein the heating means includes an elastic layer and the heating member is interposed via the belt member. A fixing roller that is in pressure contact with the pressure pad; and a heat source that heats the fixing roller.

The fixing device according to a tenth aspect of the present invention is the fixing device according to any one of the first to eighth aspects, wherein the heating means includes a fixing belt stretched around a plurality of roller members, A fixing belt, an elastic member pressed against the pressure pad via the belt member, and a heat source for heating the fixing belt.

An image forming apparatus according to an eleventh aspect includes the fixing device according to any one of the first to tenth aspects.

  According to the present invention, a sheet-like member installed between a pressure pad and a pressure belt is fixed on the side surface on the upstream side of the nip portion of the support member that supports the pressure pad so as to be close to the nip portion. Therefore, it is possible to provide a fixing device and an image forming apparatus in which the sheet-like member is not wrinkled, and the recording medium is not wrinkled or the recording medium is not conveyed.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

Embodiment 1 FIG.
A first embodiment of the present invention will be described in detail with reference to FIGS.
First, the configuration and operation of the entire image forming apparatus will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an apparatus main body of a tandem color copier as an image forming apparatus, 2 a writing unit that emits laser light based on input image information, and 3 an original conveying unit that conveys an original D to an original reading unit 4. 4 is a document reading unit that reads image information of the document D, 7 is a paper feed unit that accommodates a recording medium P such as cut paper, 9 is a registration roller that adjusts the conveyance timing of the recording medium P, and 11Y, 11M, and 11C. , 11BK are photosensitive drums on which toner images of respective colors (yellow, magenta, cyan, and black) are formed, 12 is a charging unit that charges the photosensitive drums 11Y, 11M, 11C, and 11BK, and 13 is each photosensitive drum. A developing unit that develops the electrostatic latent images formed on 11Y, 11M, 11C, and 11BK, and a toner image formed on each of the photosensitive drums 11Y, 11M, 11C, and 11BK Transfer bias roller for transferring superimposed on the recording medium P (1 transfer bias roller), 15 denotes the photosensitive drums 11Y, 11M, 11C, cleaning unit for collecting the untransferred toner on 11BK, a.

  Reference numeral 16 denotes an intermediate transfer belt cleaning unit that cleans the intermediate transfer belt 17, 17 an intermediate transfer belt on which toner images of a plurality of colors are transferred and superimposed, and 18 a color toner image on the intermediate transfer belt 17 on the recording medium P. A secondary transfer bias roller 20 for transferring the toner image onto the recording medium P is a fixing device for fixing the toner image (unfixed image) on the recording medium P.

Hereinafter, an operation during normal color image formation in the image forming apparatus will be described.
First, the document D is transported from the document table in the direction of the arrow in the drawing by the transport rollers of the document transport unit 3 and placed on the contact glass 5 of the document reading unit 4. Then, the document reading unit 4 optically reads the image information of the document D placed on the contact glass 5.

  Specifically, the document reading unit 4 scans the image of the document D on the contact glass 5 while irradiating light emitted from an illumination lamp. Then, the light reflected by the document D is imaged on the color sensor via the mirror group and the lens. The color image information of the document D is read for each RGB (red, green, blue) color separation light by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.

  Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the writing unit 2. The writing unit 2 emits laser light (exposure light) based on the image information of each color toward the corresponding photosensitive drums 11Y, 11M, 11C, and 11BK.

On the other hand, the four photosensitive drums 11Y, 11M, 11C, and 11BK are rotated clockwise in FIG. First, the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK are uniformly charged at a portion facing the charging unit 12 (this is a charging process). Thus, a charged potential is formed on the photosensitive drums 11Y, 11M, 11C, and 11BK. Thereafter, the charged surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK reach the irradiation positions of the respective laser beams.
In the writing unit 2, laser light corresponding to the image signal is emitted from the four light sources corresponding to each color. Each laser beam passes through a separate optical path for each of the yellow, magenta, cyan, and black color components (this is an exposure process).

  Laser light corresponding to the yellow component is irradiated on the surface of the first photosensitive drum 11Y from the left side of the drawing. At this time, the yellow component laser light is scanned in the rotation axis direction (main scanning direction) of the photosensitive drum 11Y by a polygon mirror that rotates at high speed. Thus, an electrostatic latent image corresponding to the yellow component is formed on the photosensitive drum 11Y charged by the charging unit 12.

  Similarly, the laser beam corresponding to the magenta component is irradiated onto the surface of the second photosensitive drum 11M from the left side of the paper, and an electrostatic latent image corresponding to the magenta component is formed. The cyan component laser light is applied to the surface of the third photosensitive drum 11C from the left side of the paper, thereby forming an electrostatic latent image of the cyan component. The black component laser beam is applied to the surface of the fourth photosensitive drum 11BK from the left side of the paper, and an electrostatic latent image of the black component is formed.

Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK on which the electrostatic latent images of the respective colors are formed reach positions facing the developing unit 13, respectively. Then, the respective color toners are supplied from the developing units 13 onto the photosensitive drums 11Y, 11M, 11C, and 11BK, and the latent images on the photosensitive drums 11Y, 11M, 11C, and 11BK are developed (development process). .)
Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK after the development process reach the facing portions of the intermediate transfer belt 17, respectively. Here, a transfer bias roller 14 is installed at each facing portion so as to contact the inner peripheral surface of the intermediate transfer belt 17. Then, the toner images of the respective colors formed on the photosensitive drums 11Y, 11M, 11C, and 11BK are sequentially superimposed and transferred onto the intermediate transfer belt 17 at the position of the transfer bias roller 14 (in the primary transfer process). is there.).

Then, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK after the transfer process reach positions facing the cleaning unit 15, respectively. Then, the untransferred toner remaining on the photosensitive drums 11Y, 11M, 11C, and 11BK is collected by the cleaning unit 15 (this is a cleaning process).
Thereafter, the surfaces of the photoconductive drums 11Y, 11M, 11C, and 11BK pass through a neutralization unit (not shown), and a series of image forming processes on the photoconductive drums 11Y, 11M, 11C, and 11BK is completed.

On the other hand, the intermediate transfer belt 17 on which the toners of the respective colors on the photosensitive drums 11Y, 11M, 11C, and 11BK are transferred (carrying) are run in the clockwise direction in the drawing and are connected to the secondary transfer bias roller 18. Reach the opposite position. Then, a color toner image carried on the intermediate transfer belt 17 is transferred onto the recording medium P at a position facing the secondary transfer bias roller 18 (secondary transfer step).
Thereafter, the surface of the intermediate transfer belt 17 reaches the position of the intermediate transfer belt cleaning unit 16. Then, the untransferred toner adhered on the intermediate transfer belt 17 is collected by the intermediate transfer belt cleaning unit 16, and a series of transfer processes in the intermediate transfer belt 17 is completed.

Here, the recording medium P transported between the intermediate transfer belt 17 and the secondary transfer bias roller 18 (secondary transfer nip) is transported from the paper supply unit 7 via the registration roller 9 and the like. It is a thing.
Specifically, the recording medium P fed by the paper feeding roller 8 from the paper feeding unit 7 that stores the recording medium P is guided to the registration roller 9 after passing through the conveyance guide. The recording medium P that has reached the registration roller 9 is conveyed toward the secondary transfer nip at the same timing.

Then, the recording medium P on which the full-color image is transferred is guided to the fixing device 20 by the transport belt. In the fixing device 20, the color image (toner) is fixed on the recording medium P at the nip portion between the fixing roller and the pressure belt.
Then, the recording medium P after the fixing step is discharged as an output image outside the apparatus main body 1 by a paper discharge roller, and a series of image forming processes is completed.

Next, the configuration and operation of the fixing device 20 installed in the image forming apparatus main body 1 will be described in detail with reference to FIGS.
FIG. 2 is a configuration diagram showing the fixing device, and FIG. 3 is an enlarged view showing the vicinity of the nip portion.

Referring to FIG. 2, the fixing device 20 includes heating units 21 and 25 that heat the toner image T, a pressurizing unit 31 that presses against the heating units 21 and 25 and forms a nip portion where the recording medium P is conveyed, Etc.
The heating means mainly includes a fixing roller 21 that is in pressure contact with the pressure pad 33 via a pressure belt 32 (belt member), and a heater 25 as a heat source that heats the fixing roller 21 by radiant heat.
The pressure unit 31 includes a pressure belt 32 as an endless belt member that travels in the direction of the arrow in FIG. 2, and a pressure pad 33 (pressure) that is in pressure contact with the fixing roller 21 (heating unit) via the pressure belt 32. Member), a support member 34 (support plate) for supporting the pressure pad 33, a spring 35 as a biasing means for biasing the pressure pad 33 and the support member 34 toward the nip portion, and a spring 35 (biasing means). A fixing member 38 that holds the pressure belt, guide members 36A to 36C that hold the posture of the pressure belt 32, and a sheet that is sandwiched between the pressure belt 32 and the pressure pad 33 to reduce the frictional resistance of the pressure belt 32. It is comprised with the lubricant holding member 37 etc. as a shape member.

  Here, the fixing roller 21 is a thin cylindrical body that is rotationally driven clockwise in FIG. 2 by a drive motor (not shown), and a heater 25 (heat source) is fixed inside the cylindrical body. Yes. The fixing roller 21 is a multilayer structure in which an elastic layer 23 and a release layer 24 (surface coating layer) are sequentially laminated on a cylindrical cored bar 22.

The elastic layer 23 of the fixing roller 21 is made of an elastic material such as fluorine rubber, silicone rubber, or foamable silicone rubber. In particular, when silicone rubber is used as the elastic layer 23, it is preferable to coat a fluorine layer on the elastic layer 23 in order to improve the swelling resistance.
By providing the elastic layer 23 on the cored bar 22 of the fixing roller 21, the separation property of the recording medium P after passing through the nip portion is improved, and the glossiness of the output image when forming a color image is improved. . In order to ensure the above effect, it is preferable to set the thickness of the elastic layer 23 to 0.5 to 3 mm.

  Further, as the release layer 24 of the fixing roller 21, PFA (tetrafluoroethylene bar fluoroalkyl vinyl ether copolymer resin), polyimide, polyetherimide, PES (polyether sulfide), or the like can be used. By providing the release layer 24 on the surface layer of the fixing roller 21, the releasability (peelability) for the toner T (toner image) is secured.

  The heater 25 (heat source) of the fixing roller 21 is a rod-shaped heater having a heating wire inside, and both ends thereof are fixed to the side plate of the fixing device 20. The fixing roller 21 is heated by the heater 25 whose output is controlled by the power supply unit of the apparatus main body 1, and heat is applied to the toner image T on the recording medium P from the surface thereof. The output control of the heater 25 is performed based on the detection result of the roller surface temperature by a thermistor (not shown) that contacts the surface of the fixing roller 21. Further, the temperature of the fixing roller 21 (fixing temperature) can be set to a desired temperature by such output control of the heater 25.

  The pressure belt 32 of the pressure means 31 is obtained by forming a surface layer made of PFA (tetrafluoroethylene bar fluoroalkyl vinyl ether copolymer resin) on a base layer made of polyimide or the like. The pressure belt 32 is held by guide members 36 </ b> A to 36 </ b> C, and travels (rotates) counterclockwise in FIG. 2 as the fixing roller 21 rotates.

  The pressure pad 33 (pressure member) has a rubber layer (elastic layer) made of silicone rubber, fluorine rubber, or the like. The rubber layer of the pressure pad 33 is set to have a layer thickness of 0.5 to 3 mm and a rubber hardness of 5 to 50 Hs. The pressure pad 33 held by the support member 34 (support plate) is urged by the spring 35 together with the support member 34, and is fixed via the lubricant holding member 37 (sheet-like member) and the pressure belt 32. The roller 21 is pressed. In this way, a desired nip portion is formed between the pressure belt 32 and the fixing roller 21. The surface shape of the pressure pad 33 (the surface that forms the nip portion) may be a planar shape or a curved surface shape in accordance with the curvature of the fixing roller 21.

The fixing member 38 (fixing plate) is formed in a U-shape so as to cover the support member 34 (the pressure pad 33 is supported on the surface) having a U-shaped cross section. Yes. The fixing member 38 is a plate material made of a metal material, and is fixedly supported on the side plate of the fixing device 20. On the fixing member 38, springs 35 (urging members) for urging the pressure pad 33 and the support member 34 toward the nip portion are installed at both ends in the width direction and at the center in the width direction, respectively. .
With such a configuration, the pressure pad 33 comes into almost uniform pressure contact with the fixing roller 21 (pressure belt 32) in the width direction. Accordingly, the nip width at the nip portion between the fixing roller 21 and the pressure pad 33 (pressure belt 32) is almost uniform in the width direction, and uneven fixing is less likely to occur on the output image.

  36 A of 1st guide members hold | maintain the attitude | position of the pressure belt 32 from the exit side (it is the left side of FIG. 2) of a nip part to the downstream (it is the downstream of the running direction of the pressure belt 32). The third guide member 36C holds the posture of the pressure belt 32 from the inlet side (the right side in FIG. 2) of the nip portion to the upstream side (the upstream side in the traveling direction of the pressure belt 32). The second guide member 36B maintains the posture of the pressure belt 32 between the first guide member 36A and the third guide member 36C.

A lubricant holding member 37 as a sheet-like member is disposed between the pressure belt 32 and the pressure pad 33. Specifically, the lubricant holding member 37 is supported by the pressure pad 33 in accordance with the shape of the support member 34 (the pressure pad 33 is supported on the surface) having a U-shaped cross section. It is disposed so as to cover the member 34. Then, the lubricant held by the lubricant holding member 37 is supplied (applied) to the inner peripheral surface (sliding surface) of the pressure belt 32, whereby the inner peripheral surface (sliding surface) of the pressure belt 32. ) Will decrease.
Note that fluorine grease can be used as the lubricant held by the lubricant holding member 37. Moreover, as the lubricant holding member 37, a mesh formed of aramid fibers can be used.

Here, referring to FIG. 3, the lubricant holding member 37 (sheet-like member) is a side surface of the support member 34 on the upstream A side of the nip portion (a side surface standing toward the inside of the pressure belt 32). ) And are fixed (adhered) by being folded via an adhesive 90 so as to be close to the nip portion. Further, the lubricant holding member 37 is folded without being bonded onto the surface of the side surface of the support member 34 on the downstream B side of the nip portion (the side surface rising toward the inside of the pressure belt 32). Yes. That is, the lubricant holding member 37 is fixed in the vicinity of the inlet A of the nip portion.
With such a configuration, when the fixing device 20 is operated, the lubricant holding member 37 easily follows the running of the pressure belt 32, and the lubricant holding member 37 is less likely to be wrinkled. Accordingly, the surface of the pressure belt 32 is less likely to be wrinkled (wrinkled), the wrinkles are generated on the recording medium P passing through the nip portion, and the transportability of the recording medium P is deteriorated. The trouble is reduced.

Finally, the operation of the fixing device 20 configured as described above will be described.
When the power switch of the apparatus main body 1 is turned on, power is supplied to the heater 25, and the rotation driving of the fixing roller 21 in the direction of the arrow in FIG. 2 is started. The running (rotation) in the direction of the arrow is started.
Thereafter, the recording medium P is fed from the paper supply unit 7, and an unfixed image is carried on the recording medium P at the position of the secondary transfer bias roller 18. The recording medium P carrying the unfixed image T (toner image) is conveyed in the direction of the broken-line arrow (−X direction) in FIG. 2 and reaches the nip portion between the fixing roller 21 and the pressure belt 32 that are in a pressure contact state. Sent in. The toner image T is fixed on the surface of the recording medium P by the heating by the fixing roller 21 and the pressing force of the fixing roller 21 and the pressure belt 32 (pressure pad 33). Thereafter, the recording medium P sent out from the nip portion by the rotating fixing roller 21 and the pressure belt 32 is conveyed in the direction of the broken line arrow (−X direction).
The fixing device 20 according to the first embodiment has a relatively small number of parts, and the pressure belt 32 is disposed without making the fixing device 20 complicated and large, so that a good fixing property can be obtained. . Furthermore, in the first embodiment, since the lubricant holding member 37 is fixed (fixed) on the side surface of the support member 34 on the upstream side of the nip portion and close to the nip portion, the lubricant holding member It is possible to suppress the occurrence of wrinkles in 37.

  As described above, in the first embodiment, the lubricant holding member 37 (sheet-like member) installed between the pressure pad 33 and the pressure belt 32 is supported by the support member that supports the pressure pad 33. 34 is fixed so as to be close to the nip portion on the side surface on the upstream side of the nip portion. Therefore, the lubricant holding member 37 is not wrinkled, and the recording medium P is wrinkled. It is possible to suppress problems such as poor conveyance.

Embodiment 2. FIG.
The second embodiment of the present invention will be described in detail with reference to FIG.
FIG. 4A is an enlarged view showing a part of the fixing device in the second embodiment, and corresponds to FIG. 3 in the first embodiment. FIG. 4B is a diagram showing the plate-like member 91 installed in the fixing device 20 of FIG.

  As in the first embodiment, the fixing device 20 according to the second embodiment also includes heating means 21 and 25, a pressing means 31, and the like. The heating means is composed of the fixing roller 21 and the heater 25, and the pressure means 31 is a pressure belt 32, a pressure pad 33, a support member 34, a fixing member 38, guide members 36A to 36C, and a lubricant holding member 37 ( Sheet-like member), and the like.

Here, unlike the first embodiment, the pressurizing means 31 in the second embodiment is provided with a plate-like member 91 for fixing to the side surface of the support member 34 with the lubricant holding member 37 interposed therebetween. ing.
Specifically, referring to FIG. 4A, the plate-like member 91 is supported by a screw 92 passing through a through-hole (a through-hole formed in the lubricant holding member 37 or the plate-like member 91). It is fastened on the side surface 34 (the side surface on the upstream side of the nip portion adjacent to the nip portion). That is, the lubricant holding member 37 is pressed (fixed) on the side surface of the support member 34 by being pressed by the plate-like member 91.
With such a configuration, when the fixing device 20 is operated, the lubricant holding member 37 easily follows the running of the pressure belt 32, and the lubricant holding member 37 is less likely to be wrinkled. Further, in the second embodiment, the lubricant holding member 37 on the support member 34 is compared with the case where the adhesive 90 is used to fix the support member 34 (in the case of the first embodiment). It becomes easy to perform positioning (positioning performed at the position of the through hole). Therefore, workability when installing the lubricant holding member 37 on the support member 34 is improved.

  Here, in this Embodiment 2, as shown to FIG. 4 (B), the plate-shaped member 91 (plate spring member) is formed in the U shape. Specifically, a bent portion 91 a is formed in the plate-like member 91, and the bent portion 91 a is disposed so as to contact the upper portion of the side surface via the lubricant holding member 37. Thereby, the spring property of the plate-like member 91 is added, and the pressing force against the lubricant holding member 37 is increased. Further, since the pressing force against the lubricant holding member 37 is difficult to be dispersed by making line contact with the lubricant holding member 37 at the tip of the bent portion 91a, the lubricant holding member 37 on the support member 34 is fixed. It is possible to suppress a problem that the wearing force is reduced.

  As described above, also in the second embodiment, the lubricant holding member 37 (sheet-like member) installed between the pressure pad 33 and the pressure belt 32 is the same as in the first embodiment. Since the support member 34 that supports the pressure pad 33 is fixed on the side surface on the upstream side of the nip portion so as to be close to the nip portion, the lubricant holding member 37 is not wrinkled and the recording medium P is not wrinkled. Inconveniences such as wrinkles and poor conveyance of the recording medium P can be suppressed.

Embodiment 3 FIG.
A third embodiment of the present invention will be described in detail with reference to FIG.
FIG. 5 is an enlarged view showing a part of the fixing device in the third embodiment, and corresponds to FIG. 4A in the second embodiment.

  The fixing device 20 according to the third embodiment is also composed of heating means 21 and 25, a pressing means 31, and the like as in the second embodiment. The heating means is composed of the fixing roller 21 and the heater 25, and the pressure means 31 is a pressure belt 32, a pressure pad 33, a support member 34, a fixing member 38, guide members 36A to 36C, and a lubricant holding member 37 ( Sheet-like member), and the like.

Here, as shown in FIG. 5, the pressurizing means 31 in the third embodiment is different from the second embodiment in that it is fixed to the side surface of the support member 34 with the lubricant holding member 37 interposed therebetween. A plate-like member 91B is also installed on the downstream side of the nip portion.
Specifically, on the upstream side of the nip portion, the plate-like member 91 </ b> A has a side surface (the side surface of the support member 34) by a screw 92 </ b> A passing through a through-hole (a through-hole formed in the lubricant holding member 37 and the plate-like member 91 </ b> A). It is a side surface on the upstream side of the nip portion adjacent to the nip portion. Further, on the downstream side of the nip portion, the plate-like member 91B has a side surface (nip) of the support member 34 by a screw 92B passing through a through-hole (a through-hole formed in the lubricant holding member 37 or the plate-like member 91B). It is a side surface on the downstream side of the nip part close to the part. That is, the lubricant holding member 37 (sheet-like member) is also on the surface of the side surface of the support member 34 on the downstream B side of the nip portion (the side surface rising toward the inside of the pressure belt 32). The plate member 91B is folded and fixed (adhered) so as to be close to the portion.

  With such a configuration, when the fixing device 20 is operated, the lubricant holding member 37 easily follows the running of the pressure belt 32, and the lubricant holding member 37 is less likely to be wrinkled. Further, in the third embodiment, the lubricant holding member 37 on the support member 34 is compared with the case where the adhesive 90 is used to fix the support member 34 (in the case of the first embodiment). It becomes easy to perform positioning (positioning performed at the position of the through hole). Therefore, workability when installing the lubricant holding member 37 on the support member 34 is improved.

  In order to secure the above-described effect, the lubricant holding member 37 has a fixing force on the side surface on the downstream side of the nip portion that is smaller than the fixing force on the side surface on the upstream side of the nip portion. Further, it is preferably fixed to the support member 34. Specifically, for example, the spring property of the plate-like member 91A installed on the upstream side of the nip portion (the bending angle of the bent portion 91a) is larger than the spring property of the plate-like member 91B installed on the downstream side of the nip portion. Set as follows. As a result, the lubricant holding member 37 is strongly fixed to the side surface of the support member 34 on the upstream side of the nip portion, and the lubricant holding member 37 can easily follow the running of the pressure belt 32. 37 is less likely to wrinkle.

  As described above, also in the third embodiment, the lubricant holding member 37 (sheet-like member) installed between the pressure pad 33 and the pressure belt 32 is the same as in the above embodiments. Since the support member 34 that supports the pressure pad 33 is fixed on the side surface on the upstream side of the nip portion so as to be close to the nip portion, the lubricant holding member 37 is not wrinkled and the recording medium P is not wrinkled. Inconveniences such as wrinkles and poor conveyance of the recording medium P can be suppressed.

Embodiment 4 FIG.
A fourth embodiment of the present invention will be described in detail with reference to FIG.
FIG. 6 is an enlarged view showing a part of the fixing device in the fourth embodiment, and corresponds to FIG. 4A in the second embodiment.

  The fixing device 20 according to the fourth embodiment is also composed of heating means 21 and 25, a pressing means 31, and the like as in the second embodiment. The heating means is composed of the fixing roller 21 and the heater 25, and the pressure means 31 is a pressure belt 32, a pressure pad 33, a support member 34, a fixing member 38, guide members 36A to 36C, and a lubricant holding member 37 ( Sheet-like member), and the like.

Here, as shown in FIG. 6, unlike the second embodiment, the pressurizing means 31 in the fourth embodiment has a side surface of the support member 34 with a lubricant holding member 37 sandwiched between plate-like members 91. A protrusion 34 a for adhering to the support member 34 is formed on the side surface of the support member 34.
Specifically, a protrusion 34 a (engagement portion) that passes through a through hole (a through hole formed in the lubricant holding member 37 or the plate-like member 91) is formed on the upstream side surface of the support member 34. ing. Then, the plate-like member 91 is fixed on the side surface of the support member 34 (the side surface on the upstream side of the nip portion close to the nip portion) by the protruding portion 34a passing through the through hole. That is, the lubricant holding member 37 is pressed (fixed) on the side surface of the support member 34 by being pressed by the plate-like member 91 that engages with the protrusion 34 a.
With such a configuration, when the fixing device 20 is operated, the lubricant holding member 37 easily follows the running of the pressure belt 32, and the lubricant holding member 37 is less likely to be wrinkled. Further, in the fourth embodiment, the lubricant holding member 37 on the support member 34 is compared with the case where the adhesive 90 is used to fix the support member 34 (in the case of the first embodiment). It becomes easy to perform positioning (positioning performed at the position of the through hole). Therefore, workability when installing the lubricant holding member 37 on the support member 34 is improved.

In the fourth embodiment, the protrusion 34a is formed on the support member 34. However, the protrusion 91a can be formed on the plate-like member 91 as shown in FIG.
Specifically, referring to FIG. 7, a protrusion 91 a (engagement portion) that passes through a through hole (a through hole formed in the lubricant holding member 37 or the support member 34) is formed in the plate-like member 91. To do. The plate-like member 91 is fixed on the side surface of the support member 34 by a protrusion 91a that passes through the through hole. That is, the lubricant holding member 37 is pressed (fixed) on the side surface of the support member 34 by being pressed by the plate-like member 91 engaged with the support member 34 by the protrusion 91 a. Even in such a case, the same effect as in the fourth embodiment is obtained.

  As described above, also in the fourth embodiment, the lubricant holding member 37 (sheet-like member) installed between the pressure pad 33 and the pressure belt 32 is the same as in the above embodiments. Since the support member 34 that supports the pressure pad 33 is fixed on the side surface on the upstream side of the nip portion so as to be close to the nip portion, the lubricant holding member 37 is not wrinkled and the recording medium P is not wrinkled. Inconveniences such as wrinkles and poor conveyance of the recording medium P can be suppressed.

Embodiment 5 FIG.
A fifth embodiment of the present invention will be described in detail with reference to FIG.
FIG. 8 is a configuration diagram illustrating the fixing device according to the fifth embodiment, and corresponds to FIG. 2 according to the first embodiment. The fixing device according to the fifth embodiment is different from that of the first embodiment in which a fixing roller is used as the heating unit in that a fixing belt is used as the heating unit.

As shown in FIG. 8, the fixing device 20 according to the fifth exemplary embodiment conveys the recording medium P in pressure contact with the heating units 25 and 41 to 51 and the heating units 25 and 41 to 51 that heat the toner image T. The pressurizing means 31 and the like for forming the nip portion are configured.
The heating means is applied to the pressure pad 33 via the endless fixing belt 41 that travels in the direction of the arrow in FIG. 8, a plurality of roller members 42 to 44 that stretch the fixing belt 41, the fixing belt 41, and the pressure belt 32. A fixing pad 46 as an elastic member to be pressed, a support plate 47 that supports the fixing pad 46, a spring 51 that biases the fixing pad 46 toward the pressure belt 32, and a tension roller 44 that biases toward the fixing belt 41. The fixing belt 41 is provided inside the spring 50, a pressure contact pad 49 that presses against the tension roller 44 via the fixing belt 41, a heating roller 45 that circumscribes the fixing belt 41, and the heating roller 45 and a plurality of roller members 42 to 44. The heater 25 as a heat source for heating the toner, the low friction member 48 disposed between the fixing pad 46 and the fixing belt 41, and the like. It has been.

  Further, the pressurizing means 31 is configured in the same manner as in the first embodiment. Also in the fifth embodiment, the lubricant holding member 37 is fixed on the side surface of the support member 34 on the upstream side of the nip portion and close to the nip portion.

In the fixing device 20 configured as described above, the heating roller 45 is driven to rotate by a drive motor (not shown), so that the fixing belt 41 travels in the direction of the arrow and the plurality of roller members 42 to 44 rotate in the clockwise direction. Followed rotation. The toner image T on the recording medium P sent to the nip portion is heated by the fixing belt 41 and the pressing force of the fixing belt 41 (fixing pad 46) and the pressure belt 32 (pressure pad 33). Then, it is fixed on the surface of the recording medium P.
In the fifth embodiment, the heater 25 as a heat source is provided in all the four roller members 42 to 45, but the number of roller members in which the heater 25 is provided may be three or less. In addition, a roller member serving as a driving source of the fixing belt 41 may be roller members 42 to 44 other than the heating roller 45.

  As described above, also in the fifth embodiment, the lubricant holding member 37 (sheet-like member) installed between the pressure pad 33 and the pressure belt 32 is the same as in the above embodiments. Since the support member 34 that supports the pressure pad 33 is fixed on the side surface on the upstream side of the nip portion so as to be close to the nip portion, the lubricant holding member 37 is not wrinkled and the recording medium P is not wrinkled. Inconveniences such as wrinkles and poor conveyance of the recording medium P can be suppressed.

In each of the above-described embodiments, the present invention is applied to the fixing device 20 using a heating method using a heater. However, the present invention can also be applied to a fixing device using an electromagnetic induction heating method. . Also in these cases, the lubricant holding member 37 (sheet-like member) is fixed on the side surface on the upstream side of the nip portion of the support member 34 that supports the pressure pad 33 so as to be close to the nip portion. The same effects as those in the above embodiments can be obtained.
In each of the above embodiments, the lubricant holding member 37 is used as the sheet-like member, but a sheet-like member formed of a low friction material can also be used.

  It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the technical idea of the present invention, the embodiments can be modified as appropriate in addition to those suggested in the embodiments. Is clear. In addition, the number, position, shape, and the like of the constituent members are not limited to the above embodiments, and can be set to a number, position, shape, and the like that are suitable for carrying out the present invention.

1 is an overall configuration diagram illustrating an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is a configuration diagram illustrating a fixing device installed in the image forming apparatus of FIG. 1. It is an enlarged view which shows the vicinity of a nip part. FIG. 5 is an enlarged view showing a part of a fixing device according to Embodiment 2 of the present invention. It is an enlarged view which shows a part of fixing device in Embodiment 3 of this invention. It is an enlarged view which shows a part of fixing device in Embodiment 4 of this invention. It is an enlarged view showing a part of another fixing device. It is a block diagram which shows the fixing device in Embodiment 5 of this invention.

Explanation of symbols

1 image forming apparatus body (apparatus body),
20 fixing device,
21 fixing roller (heating means),
22 cored bar, 23 elastic layer, 24 release layer,
25 Heater (heat source),
31 Pressurizing means,
32 Pressure belt (belt member),
33 Pressure pad,
34 support members, 34a, 91a protrusions,
35 Spring (biasing means),
36A-36C guide members,
37 Lubricant holding member (sheet-like member),
38 fixing member,
41 fixing belt (heating means),
90 adhesives,
91, 91A, 91B plate-like member, 92, 92A, 92B screw,
P Recording medium.

Claims (11)

A fixing device for fixing a toner image on a recording medium,
Heating means for heating the toner image;
A pressurizing unit that forms a nip portion in which the recording medium is conveyed in pressure contact with the heating unit;
With
The pressurizing means is
An endless belt member traveling in a predetermined direction;
A pressure pad in pressure contact with the heating means via the belt member;
A support member that supports the pressure pad and is biased toward the nip portion together with the pressure pad by a biasing means;
A sheet-like member sandwiched between the belt member and the pressure pad to reduce the frictional resistance of the belt member;
Comprising
The sheet-like member is fixed on the surface of the side surface of the support member that stands inward of the belt member in the vicinity of the nip portion on the upstream side of the nip portion, and the nip portion on the downstream side of the nip portion. Is also fixed on the surface of the side surface of the support member that stands up toward the inner side of the belt member, and the fixing force on the side surface on the downstream side of the nip portion is on the side surface on the upstream side of the nip portion. The fixing device is fixed to the support member so as to be smaller than the fixing force . A fixing device for fixing a toner image on a recording medium,
Heating means for heating the toner image;
A pressurizing unit that forms a nip portion in which the recording medium is conveyed in pressure contact with the heating unit;
With
The pressurizing means is
An endless belt member traveling in a predetermined direction;
A pressure pad in pressure contact with the heating means via the belt member;
A support member that supports the pressure pad and is biased toward the nip portion together with the pressure pad by a biasing means;
A sheet-like member sandwiched between the belt member and the pressure pad to reduce the frictional resistance of the belt member;
Comprising
The sheet-like member is fixed on the surface of the side surface of the support member that rises toward the inside of the belt member in the vicinity of the nip portion on the upstream side of the nip portion,
The fixing device is characterized in that the pressing means includes a plate-like member formed in a U-shape while being fixed to the side surface of the support member with the sheet-like member interposed therebetween. The sheet-like member includes a through hole,
The fixing device according to claim 2, wherein the plate-like member is fastened on the side surface of the support member by a screw passing through the through hole. The side surface of the plate member or the support member includes a protrusion,
The sheet-like member includes a through hole,
The fixing device according to claim 2, wherein the plate-like member is fixed on the side surface of the support member by the protrusion passing through the through hole. The sheet-like member is folded and fixed on the surface of the side surface of the support member that stands inward of the belt member in the vicinity of the nip portion on the upstream side of the nip portion, and on the downstream side of the nip portion. 5. The fixing according to claim 1, wherein the fixing member is also folded and fixed onto a surface of a side surface of the support member that stands in the vicinity of the nip portion and toward the inner side of the belt member. apparatus. The fixing device according to claim 1, wherein the pressure unit includes a fixing member that holds the biasing unit. The fixing device according to claim 1, wherein the pressure unit includes a guide member that holds the posture of the belt member. The fixing device according to claim 1, wherein the sheet-like member is a lubricant holding member that holds a lubricant. The heating means includes
A fixing roller having an elastic layer and being in pressure contact with the pressure pad via the belt member;
A heat source for heating the fixing roller;
The fixing device according to claim 1, wherein the fixing device is provided. The heating means includes
A fixing belt stretched around a plurality of roller members;
An elastic member that presses against the pressure pad via the fixing belt and the belt member;
A heat source for heating the fixing belt;
The fixing device according to claim 1, wherein the fixing device is provided. An image forming apparatus comprising the fixing device according to claim 1.

Images