JP5063267B2 - 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 or a fixing belt and a pressure belt are pressed against each other to form a nip portion, and a toner image is carried on the nip portion. 2. Description of the Related Art A fixing device that conveys a recording medium and fixes a toner image on the recording medium is known (see, for example, Patent Document 1 and Patent Document 2).
Such a fixing device using a pressure belt can secure a sufficient nip width in the conveyance direction at the nip portion, and can reduce the amount of heat taken from the fixing member by setting the heat capacity of the pressure belt small. Therefore, better fixability can be obtained as compared with an apparatus using a pressure roller.

  On the other hand, in Patent Document 1 and the like, a pressure roller that stretches the pressure belt upstream is provided for the purpose of equalizing the pressing force between the fixing member and the pressure belt in the axial direction (width direction). Has been disclosed that comprises a cylindrical outer roll and a crown-shaped inner roll.

On the other hand, Patent Document 3 discloses a fixing device using a fixing film and a pressure roller, and for the purpose of stabilizing the running property of the fixing film, the sliding surface on which the fixing film slides and fixing. A technique in which a lubricant is interposed between the film and the film is disclosed.
Patent Document 4 and the like disclose a technique that uses a lubricant application device that applies a lubricant to the surface of a photosensitive drum and has a viscosity of 50 to 10000 CS at 25 ° C. as the lubricant.

JP 2006243321 A JP-A-1-279278 JP 2005-317519 A JP-A-11-212398

Although the conventional fixing device using a pressure belt can obtain good fixability, it has more parts than a fixing device using a pressure roller, making the device more complicated and larger. It was.
In order to solve this, it is conceivable to form a nip portion (fixing nip portion) by pressing a pressure pad against a heating means via a pressure belt (including a pressure film). However, in that case, since the pressure belt slides against the pressure pad, abnormal noise may occur due to stick-slip, and the transportability of the recording medium may decrease. is there.

  The present invention has been made in order to solve the above-described problems, and has a relatively small number of parts, which can obtain good fixing properties without complicating or increasing the size of the apparatus. It is an object of the present invention to provide a fixing device and an image forming apparatus that do not cause deterioration in transportability and abnormal noise.

According to a first aspect of the present invention, there is provided a fixing device for fixing a toner image onto a recording medium, a heating unit for heating the toner image, and the recording medium being conveyed in pressure contact with the heating unit. Pressurizing means for forming a nip portion, wherein the pressurizing means includes an endless belt member that travels in a predetermined direction, a pressurizing pad that presses against the heating means via the belt member, A guide member that maintains the posture of the belt member, a support member that has a U-shaped or rectangular cross section and supports the pressure pad on the surface, and a lubricant having a viscosity of 70 to 500 CS at 25 ° C. agent holds the, is placed between the pressure pad and the belt member, anda lubricant holding member for supplying the lubricant to the inner circumferential surface of the belt member, the lubricant holding The material is its exhibition Figure is formed so that a cross shape, in which is arranged by folding a cross-shaped section so as to cover the pressure pad and the support member in accordance with the shape of the support member.

The fixing device according to a second aspect of the present invention is the fixing device according to the first aspect, wherein the lubricant holding member is formed in a mesh shape with aramid fibers.

The fixing device according to a third aspect of the present invention is the fixing device according to the second aspect, wherein the lubricant holding member has a mesh braiding angle of 45 ± 15 degrees with respect to the recording medium conveyance direction. It is formed as follows.

A fixing device according to a fourth aspect of the present invention is the fixing device according to any one of the first to third aspects, wherein the lubricant retaining member is a mesh formed of aramid fibers. And a holding layer in contact with the pressure pad.

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 at least a part of the lubricant holding member is the support member and the plate-like member. It is sandwiched between.

According to a sixth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects , at least a part of the lubricant holding member is welded to the support member. Is.

A 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 lubricant holding member is stretched on the support member. .

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 pressing means is provided between the lubricant holding member and the belt member. And a sliding member formed of a low friction material.

According to a ninth aspect of the present invention, in the fixing device according to the eighth aspect, the sliding member is formed of a fiber material made of a tetrafluoroethylene bar fluoroalkyl vinyl ether copolymer resin. Is.

A fixing device according to a tenth aspect of the present invention is the fixing device according to any one of the first to ninth aspects, wherein the lubricant is fluorine grease.

According to an eleventh aspect of the present invention, in the fixing device according to any one of the first to tenth aspects, the belt member includes a base layer made of polyimide.

The fixing device according to a twelfth aspect of the present invention is the fixing device according to any one of the first to eleventh aspects, wherein the belt member is made of a tetrafluoroethylene barfluoroalkyl vinyl ether copolymer resin. A surface layer is provided.

A fixing device according to a thirteenth aspect of the present invention is the fixing device according to any one of the first to twelfth aspects, wherein the pressure pad includes a rubber layer having a layer thickness of 0.5 to 3 mm. It is a thing.

According to a fourteenth aspect of the present invention, in the fixing device according to any one of the first to thirteenth aspects, the pressure pad comprises a rubber layer having a rubber hardness of 5 to 50 Hs. It is.

According to a fifteenth aspect of the present invention, in the fixing device according to any one of the first to fourteenth aspects, 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.

According to a fifteenth aspect of the present invention, in the fixing device according to the fifteenth aspect, the elastic layer is formed to have a layer thickness of 0.5 to 3 mm.

An image forming apparatus according to a seventeenth aspect includes the fixing device according to any one of the first to sixteenth aspects.

  In the present invention, the pressure means is mainly composed of a belt member, a pressure pad, and a holding member, and the viscosity of the lubricant supplied to the inner peripheral surface of the belt member is optimized, so the number of parts is relatively small, It is possible to provide a fixing device and an image forming apparatus that can obtain a good fixing property without increasing the complexity and size of the device, and that do not cause a decrease in transportability of the recording medium and abnormal noise.

  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.
The 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 20. FIG. 3A is a cross-sectional view showing the lubricant holding member 37 installed in the pressure unit 31 of the fixing device 20, and FIG. 3B shows an enlarged mesh layer 37 a of the lubricant holding member 37. It is a top view.

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. Members), a support member 34 (support plate) that supports the pressure pad 33, a spring 35 that biases the pressure pad 33 toward the fixing roller 21, and guide members 36A to 36C that hold the posture of the pressure belt 32. A lubricant holding member 37 for supplying a lubricant to the inner peripheral surface (sliding surface) of the pressure belt 32 is configured.

  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 and is brought into pressure contact with the fixing roller 21 via the lubricant holding member 37 and the pressure belt 32. 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.

  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. These guide members 36 </ b> A to 36 </ b> C are all fixed to the side plate of the fixing device 20.

The lubricant holding member 37 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. The lubricant holding member 37 is held by the fixing device 20 so as to be movable in the vertical direction of FIG. 2 together with the pressure pad 33 and the support 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 friction coefficient of the inner peripheral surface of the pressure belt 32 is increased. Will be reduced.
Here, the lubricant held by the lubricant holding member 37 has a viscosity at 25 ° C. of 70 to 500 CS. Thereby, the above-described effect is ensured. Fluorine grease can be used as a lubricant satisfying such conditions.

In the first embodiment, the lubricant holding member 37 is made of an aramid fiber and formed in a mesh shape. Specifically, referring to FIG. 3A, the lubricant holding member 37 includes two layers, a mesh layer 37a formed in a mesh shape with an aramid fiber and a holding layer 37b in contact with the pressure pad 33. It has a layered structure. Then, the mesh layer 37a is impregnated (held) with a lubricant, and the lubricant is supplied to the inner peripheral surface of the pressure belt 32 that is in sliding contact with the mesh layer 37a. Thus, the retention of the lubricant can be enhanced by providing the mesh layer 37a. Further, by providing the holding layer 37b, it is possible to improve the installation property on the support member 34 as compared with the case where the lubricant holding member 37 is configured only by the mesh layer 37a. The holding layer 37b can be formed of a thin resin material having good adhesion to the mesh layer 37a and the support member 34 (made of a metal material).
Furthermore, in the first embodiment, as shown in FIG. 3B, the mesh weaving angle in the mesh layer 37a is 45 with respect to the conveyance direction of the recording medium P (the white arrow direction in the figure). It is formed to be ± 15 degrees. As a result, the lubricant impregnated in the mesh layer 37 a is uniformly supplied to the inner peripheral surface of the pressure belt 32.

  In order to make the pressure belt 32 slide with lower friction, a low friction material (for example, ethylene fluoride fluorotetrafluoroalkyl) is interposed between the lubricant holding member 37 (mesh layer 37a) and the pressure belt 32. It is possible to install a sliding member formed of a fiber material (PFA fiber) made of vinyl ether copolymer resin. Specifically, a PFA fiber layer can be formed on the mesh layer 37 a of the lubricant holding member 37.

The fixing device 20 configured as described above operates as follows.
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. . Further, in the first embodiment, since the lubricant having the optimum viscosity is supplied to the inner peripheral surface of the pressure belt 32, stick slip does not easily occur during the travel of the pressure belt 32. In addition, it is possible to suppress problems such as the generation of sound and the deterioration of the transportability of the recording medium P, and it is possible to reduce the increase and fluctuation of the driving torque of the fixing device 20 (pressure means 31).

FIG. 4 is a table showing experimental conditions and experimental results of an experiment conducted by the present inventor in order to confirm the effect of the first embodiment described above.
In the experiment in FIG. 4, the fixing device 20 according to the first embodiment is used to vary the viscosity of the lubricant (the viscosity at 25 ° C.) and the friction coefficient of the lubricant holding member 37. Regarding the conditions, the presence or absence of abnormal noise and the device torque were measured. Specifically, in Comparative Example 1, the lubricant viscosity is 65 CS and the friction coefficient of the lubricant holding member 37 is 0.1. In Example 1, the lubricant viscosity is 200 CS and the friction coefficient of the lubricant holding member 37 is 0. In Example 2, the lubricant viscosity is 200 CS and the friction coefficient of the lubricant holding member 37 is 0.05. In Comparative Example 2, the lubricant viscosity is 600 CS and the friction coefficient of the lubricant holding member 37 is 0. .05. In Example 2 and Comparative Example 2, the friction coefficient was adjusted by providing a PFA fiber layer (sliding member) on the mesh layer 37 a of the lubricant holding member 37.

From the experimental results shown in FIG. 4, in Example 1 and Example 2, the sound generated from the apparatus was 35 to 45 db (decibel), which was lower than the target value of 50 db. That is, no abnormal noise was generated. Further, the driving torque (device torque) of the fixing device 20 is 0.5 to 0.7 N · m, which is lower than the target value of 1.5 N · m. In addition, there was little torque fluctuation and no stick-slip occurred.
On the other hand, in Comparative Example 1, although the apparatus torque was low, an abnormal sound of 70 db exceeding the target value (50 db) was generated from the apparatus. Further, in Comparative Example 2, although no abnormal noise was generated, the device torque exceeded the target value (1.5 N · m) to 1.6 N · m, and the torque fluctuation also increased.
From the above, it was found that the optimum viscosity of the lubricant supplied to the inner peripheral surface of the pressure belt 32 is in the range of 70 to 500 CS at 25 ° C.

  As described above, in the first embodiment, the pressurizing unit 31 mainly includes the pressurizing belt 31 (belt member), the pressurizing pad 33, and the holding members 36A to 36C, and the pressurizing belt 32. Since the viscosity of the lubricant supplied to the inner peripheral surface of the recording medium is optimized, the number of parts is relatively small, and the fixing device 20 can be obtained with good fixing properties without being complicated and enlarged. It is possible to suppress problems that P transportability is reduced and abnormal sounds are generated.

Embodiment 2. FIG.
5 and 6, the second embodiment of the present invention will be described in detail.
FIG. 5A is a development view showing the lubricant holding member 37 installed in the fixing device according to the second embodiment, and FIG. 5B shows the lubricant holding member 37 as the pressure pad 33 and the support member 34. It is a perspective view which shows the state installed in. 6A is a top view showing a state where the lubricant holding member 37 is installed on the pressure pad 33 and the support member 34, and FIG. 6B is a cross-sectional view showing the AA cross section thereof. FIG. 6C is a cross-sectional view showing the BB cross section.

  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 unit includes the fixing roller 21 and the heater 25, and the pressing unit 31 includes the pressing belt 32, the pressing pad 33, the support member 34, the spring 35, the guide members 36A to 36C, the lubricant holding member 37, and the like. (See FIG. 2).

Here, as shown in FIG. 5A, the lubricant holding member 37 according to the second embodiment is formed so that its developed view has a cross shape. 5 (B) and FIGS. 6 (A) to 6 (C), the lubricant holding member 37 includes a support member 34 (a pressure pad 33 on the surface) having a U-shaped cross section. The cross-shaped portion is folded and disposed so as to cover the pressure pad 33 and the support member 34 in accordance with the shape of
With such a configuration, the lubricant holding member 37 is wrinkled to the lubricant holding member 37 when installed (attached) to the support member 34 in order to be adapted to the shape of the support member 34 as compared with the case where the lubricant holding member 37 is formed in a rectangular shape. (Skin) is less likely to occur Accordingly, the surface of the pressure belt 32 that forms the nip portion is less likely to be wrinkled, thereby preventing the occurrence of wrinkles on the recording medium P conveyed through the nip portion, and the conveyance of the recording medium P. Can be improved.

  In the second embodiment, the lubricant holding member 37 is formed in a cross shape. However, even if the lubricant holding member 37 is not installed, the sheet that covers the pressure pad 32 and the support member 34 is provided. By forming the members in a cross shape, it is possible to achieve the effect of suppressing the occurrence of wrinkles on the recording medium P conveyed through the nip portion.

  In the second embodiment, a cross-shaped lubricant holding member 37 is formed so as to cover the pressure pad 33 and the support member 34 in accordance with the shape of the support member 34 having a U-shaped cross section. Arranged. On the other hand, even if the cross section of the support member 34 is formed in a rectangular shape (b-shaped), the pressure pad 33 and the support member 34 are connected in accordance with the shape of the support member 34. By disposing the cross-shaped lubricant holding member 37 so as to cover, the same effect as described above can be obtained.

  As described above, also in the second embodiment, as in the first embodiment, the pressurizing unit 31 mainly includes the pressurizing belt 31 (belt member), the pressurizing pad 33, and the holding members 36A to 36C. Since the viscosity of the lubricant supplied to the inner peripheral surface of the pressure belt 32 is optimized, the number of parts is relatively small, and the fixing device 20 can be fixed well without being complicated and enlarged. Performance can be obtained, and it is possible to suppress the problem that the transportability of the recording medium P is reduced and abnormal sounds are generated.

Embodiment 3 FIG.
A third embodiment of the present invention will be described in detail with reference to FIG.
FIG. 7A is a top view showing a state where the lubricant holding member 37 is installed on the pressure pad 33 and the support member 34, and FIG. 7B is a cross-sectional view showing the AA cross section thereof. FIG. 7C is a cross-sectional view showing the BB cross section, and corresponds to FIG. 6 in the second embodiment.
The fixing device according to the third embodiment is different from that according to the second embodiment in that a part of the lubricant holding member 37 is sandwiched between the support member 34 and the plate-like member 38.

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 unit includes the fixing roller 21 and the heater 25, and the pressing unit 31 includes the pressing belt 32, the pressing pad 33, the support member 34, the spring 35, the guide members 36A to 36C, the lubricant holding member 37, and the like. (See FIG. 2).
Further, the lubricant holding member 37 according to the third embodiment is also formed so that the developed view thereof has a cross shape, similar to that of the second embodiment, as shown in FIGS. 7 (A) to (C). As described above, the cross-shaped portion is folded and disposed so as to cover the pressure pad 33 and the support member 34 in accordance with the shape of the support member 34 having a U-shaped cross section.
With this configuration, as in the second embodiment, the lubricant holding member 37 is less likely to wrinkle when installed (attached) to the support member 34, and is conveyed through the nip portion. It is possible to suppress the occurrence of wrinkles on the recording medium P and improve the transportability of the recording medium P.

Here, in Embodiment 3, as shown in FIGS. 7A to 7C, the lubricant holding member 37 is sandwiched between the lubricant holding member 37 installed on the support member 34. A plate-like member 38 made of a metal material or the like is installed.
With such a configuration, since the lubricant holding member 37 can be installed (attached) on the support member 34 with tension, wrinkles are not likely to occur in the lubricant holding member 37. Therefore, it is possible to surely prevent the occurrence of wrinkles on the recording medium P conveyed through the nip portion, and to improve the conveyance performance of the recording medium P with certainty.

  In the third embodiment, a part of the lubricant holding member 37 is sandwiched between the support member 34 and the plate-like member 38, but a part of the lubricant holding member 37 is welded to the support member 34. Even in such a configuration, the same effect as described above can be obtained.

  As described above, also in the third embodiment, the pressurizing means 31 is mainly used as the pressurizing belt 31 (belt member), the pressurizing pad 33, and the holding members 36A to 36C, as in the above-described embodiments. Since the viscosity of the lubricant supplied to the inner peripheral surface of the pressure belt 32 is optimized, the number of parts is relatively small, and the fixing device 20 can be fixed well without being complicated and enlarged. Performance can be obtained, and it is possible to suppress the problem that the transportability of the recording medium P is reduced and abnormal sounds are generated.

Embodiment 4 FIG.
A fourth embodiment of the present invention will be described in detail with reference to FIG.
FIG. 8A is a top view showing a state where the lubricant holding member 37 is installed on the pressure pad 33 and the support member 34, and FIG. 8B is a cross-sectional view showing the AA cross section thereof. FIG. 8C is a cross-sectional view showing the BB cross section, and corresponds to FIG. 6 in the second embodiment.
The fixing device according to the fourth embodiment is different from that according to the second embodiment in that a lubricant holding member 37 is stretched on a support member 34.

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 unit includes the fixing roller 21 and the heater 25, and the pressing unit 31 includes the pressing belt 32, the pressing pad 33, the support member 34, the spring 35, the guide members 36A to 36C, the lubricant holding member 37, and the like. (See FIG. 2).
Further, the lubricant holding member 37 according to the fourth embodiment is also formed so that the developed view thereof has a cross shape, similar to that of the second embodiment, as shown in FIGS. As described above, the cross-shaped portion is folded and disposed so as to cover the pressure pad 33 and the support member 34 in accordance with the shape of the support member 34 having a U-shaped cross section.
With this configuration, as in the second embodiment, the lubricant holding member 37 is less likely to wrinkle when installed (attached) to the support member 34, and is conveyed through the nip portion. It is possible to suppress the occurrence of wrinkles on the recording medium P and improve the transportability of the recording medium P.

Here, in the fourth embodiment, as shown in FIGS. 8A to 8C, plate members 38 are installed at both ends of the lubricant holding member 37, and the tension spring 39 is interposed between the plate members 38. Is installed.
With such a configuration, the lubricant holding member 37 is stretched and installed (attached) from four directions on the support member 34, so that the lubricant holding member 37 is less likely to be wrinkled. Therefore, it is possible to surely prevent the occurrence of wrinkles on the recording medium P conveyed through the nip portion, and to improve the conveyance performance of the recording medium P with certainty.
In the fourth embodiment, the lubricant holding member 37 is stretched on the support member 34 using the tension spring 39, but the lubricant holding member 37 is supported using another elastic member. It can also be configured to be stretched on the member 34.

  As described above, also in the fourth embodiment, the pressurizing means 31 is mainly used as the pressurizing belt 31 (belt member), the pressurizing pad 33, and the holding members 36A to 36C as in the above-described embodiments. Since the viscosity of the lubricant supplied to the inner peripheral surface of the pressure belt 32 is optimized, the number of parts is relatively small, and the fixing device 20 can be fixed well without being complicated and enlarged. Performance can be obtained, and it is possible to suppress the problem that the transportability of the recording medium P is reduced and abnormal sounds are generated.

  In each of the above embodiments, the present invention is applied to the fixing device 20 using the fixing roller 21, but the present invention can also be applied to a fixing device using a fixing belt. Further, in each of the above 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. it can. Also in these cases, by optimizing the viscosity of the lubricant supplied to the inner peripheral surface of the pressure belt 32, the same effects as those of the above embodiments can be obtained.

  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 a figure which shows a lubricant holding member. It is a table | surface figure which shows experimental conditions and an experimental result. It is a figure which shows the lubricant holding member installed in the fixing device in Embodiment 2 of this invention. It is a figure which shows the state by which the lubricant holding member was installed in the pressurization pad. It is a figure which shows the state by which the lubricant holding member was installed in the pressurization pad in Embodiment 3 of this invention. It is a figure which shows the state by which the lubricant holding member was installed in the pressurization pad in Embodiment 4 of this invention.

Explanation of symbols

1 image forming apparatus body (apparatus body),
20 fixing device,
21 fixing roller,
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,
36A-36C guide members,
37 Lubricant holding member,
37a mesh layer, 37b retaining layer,
38 Plate-like member, P recording medium.

Claims (17)

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 guide member for holding the posture of the belt member;
A support member that has a U-shaped or rectangular cross section and supports the pressure pad on the surface;
A lubricant holding member that holds a lubricant having a viscosity of 70 to 500 CS at 25 ° C. and that supplies the lubricant to the inner peripheral surface of the belt member, which is installed between the belt member and the pressure pad. When,
Comprising
The lubricant holding member is formed so that a developed view thereof has a cross shape, and is arranged by folding a cross-shaped portion so as to cover the pressure pad and the support member according to the shape of the support member. A fixing device characterized by that. The fixing device according to claim 1, wherein the lubricant holding member is formed in a mesh shape with an aramid fiber. The fixing device according to claim 2, wherein the lubricant holding member is formed so that a mesh weaving angle is 45 ± 15 degrees with respect to a conveyance direction of the recording medium. The said lubricant holding member was equipped with the mesh layer formed in mesh shape with the aramid type fiber, and the holding layer contact | abutted to the said pressure pad, The any one of Claims 1-3 characterized by the above-mentioned. A fixing device according to claim 1. The fixing device according to claim 1, wherein at least a part of the lubricant holding member is sandwiched between the support member and a plate-like member. The fixing device according to claim 1, wherein at least a part of the lubricant holding member is welded to the support member. The fixing device according to claim 1, wherein the lubricant holding member is stretched on the support member. The said pressurization means comprised the sliding member formed with the low friction material between the said lubricant holding member and the said belt member, The any one of Claims 1-7 characterized by the above-mentioned. Fixing device. The fixing device according to claim 8, wherein the sliding member is formed of a fiber material made of a tetrafluoroethylene bar fluoroalkyl vinyl ether copolymer resin. The fixing device according to claim 1, wherein the lubricant is a fluorine grease. The fixing device according to claim 1, wherein the belt member includes a base layer made of polyimide. The fixing device according to claim 1, wherein the belt member includes a surface layer made of a tetrafluoroethylene bar fluoroalkyl vinyl ether copolymer resin. The fixing device according to claim 1, wherein the pressure pad includes a rubber layer having a layer thickness of 0.5 to 3 mm. The fixing device according to claim 1, wherein the pressure pad includes a rubber layer having a rubber hardness of 5 to 50 Hs. 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, further comprising: The fixing device according to claim 15, wherein the elastic layer is formed to have a layer thickness of 0.5 to 3 mm. An image forming apparatus comprising the fixing device according to claim 1.

Images