JP2005003739A - Release agent leveling roller, fixing device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leveling roller for preventing off-set toner adhesion by eliminating unevenness of a release agent caused by release agent or the like, and to provide a fixing device having it and an image forming apparatus having them. <P>SOLUTION: In the release agent leveling roller 100, the fixing device 12 having it and the image forming apparatus having them, the leveling roller 100 is arranged opposite to a roller 12A of which the size of a diameter of a center part is X1 and the size of diameters of both ends is Y1. When the size of the diameter of the center part is X2 and the size of the diameters of both the ends is Y2, the value of (X2-Y2)/2 is determined on the basis of the value of (X1-Y1)/2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a release agent leveling roller for leveling a release agent, a fixing device having the release agent, and an image forming apparatus having the release roller, and in particular, a small space, low cost, high durability, and unevenness of the release agent. It is related with the technology which cancels well.
[0002]
[Prior art]
An image forming apparatus such as a copying machine such as a digital copying machine, a facsimile such as a plain paper facsimile, or a printer such as a laser beam printer is generally applied to a sheet-like recording medium by an image forming process mechanism such as an electrophotographic method. A fixing device for supporting an unfixed toner image, melting and deforming the toner by applying heat, pressure, or both heat and pressure to the toner, cooling and solidifying the toner image, and permanently fixing the surface of the paper. Yes.
[0003]
As a fixing device, a fixing roller as a fixing member heated by a heater as a heating unit, and a pressure that rotates in the same direction as the fixing roller at a nip portion that is in contact with the fixing roller and is a contact area with the fixing roller. There is known a heat roller pair type fixing device having a roller or the like as a constituent element, and transporting and passing a sheet on which toner is fixed by rotation of both rollers, and fixing the toner image by heating and pressing. It has been.
[0004]
Further, as the fixing device, an endless fixing belt as a rotating fixing member that is heated by a heater as a heating unit and conveys a sheet-like recording medium on which toner is fixed, and a heating roller around which the fixing belt is wound And a nip portion which is a contact area formed by the fixing belt and the pressure roller, and a pressure roller as a pressure member disposed opposite to the fixing roller via the fixing roller and the fixing belt. In addition, a so-called belt fixing device of a type in which a sheet on which toner is fixed is conveyed and passed by these rotations and is heated and pressed to fix the toner image is known.
[0005]
In any type of fixing device, in order to improve the releasability of the sheet from the fixing member that is in pressure contact with the sheet, a release agent such as silicone oil is generally applied. However, if the fixing member to which the release agent is applied is left for a long time, the supply is continued without being consumed, the release agent is excessively supplied, and the surface has excessive release agent. Thus, there is a problem in that unevenness of gloss of the paper is caused by transferring the release agent onto the paper.
[0006]
In addition, if continuous fixing is performed on small-size paper, excessive release agent will occur in the non-sheet passing area of small-size paper and unevenness of the release agent will occur. If this is done, there is a problem that gloss unevenness occurs on the paper. Further, the fixing device is generally provided with a separation claw for separating the paper from the fixing member. However, the separation claw is generally configured to abut against the fixing member, so that the separation claw is not in contact with the contact portion of the separation claw. There is a problem that unevenness of the release agent is generated on the fixing member at the contact portion and streaks are generated, thereby causing uneven glossiness of the paper.
[0007]
Therefore, as shown in [Patent Document 1] and [Patent Document 2], a technique for making the release agent on the fixing member uniform has been proposed. The technology described in [Patent Document 1] prevents the occurrence of unevenness of the release agent by bringing the web into contact with the fixing roller, absorbing the release agent applied to the fixing roller, and uniformly reapplying the release agent. Is. The technique described in [Patent Document 2] is to uniformly apply a release agent by bringing a metering blade into contact with a release agent application roller for applying a release agent to a fixing roller. .
[0008]
[Patent Document 1]
JP 2001-42683 A
[Patent Document 2]
JP-A-6-83228
[0009]
[Problems to be solved by the invention]
However, the technique described in [Patent Document 1] has a problem that the configuration is complicated, it is difficult to reduce the space, and the apparatus is increased in size. The technique described in [Patent Document 2] also has the same problem due to its complicated structure, and also has a problem in durability because the metering blade and the fixing member are deteriorated.
[0010]
Therefore, from the viewpoint of small space, low cost, and high durability, a technique has been proposed in which a leveling roller for leveling the release agent is brought into contact with the fixing member. Using a leveling roller prevents uneven glossiness of the paper when fixing to a large size paper after continuous fixing to small size paper, and uneven glossiness of the paper due to contact of the separation claw. It is also effective for prevention.
[0011]
However, this technique has a problem that unevenness of the release agent on the surface of the fixing member due to excessive release agent after being left for a long time cannot be eliminated, and uneven glossiness of the paper occurs. Further, due to unevenness of the release agent, relative vibration between the release agent application member for applying the release agent to the fixing member and the fixing member, noise due to so-called chattering occurs, and this chatter further causes the release agent. There is a problem that unevenness occurs. Furthermore, the toner offset to the fixing member adheres to the leveling roller, so that the leveling performance and durability of the leveling roller decrease, or the toner adhering to the leveling roller peels off and adheres to the paper. There is a problem that I do.
[0012]
An object of the present invention is to provide a leveling roller that eliminates unevenness of a release agent due to excessive release agent and prevents adhesion of offset toner, a fixing device having the same, and an image forming apparatus having the same. There is to do.
[0013]
[Means for Solving the Problems]
The invention according to claim 1 is a release agent leveling roller for leveling the release agent, wherein the diameter of the central part is X1 and the diameters of both ends are Y1. In the release agent leveling rollers disposed opposite to each other, when the diameter of the central portion is X2, and the diameter of both ends is Y2, the value of (X2-Y2) / 2 is It is determined based on the value of (X1-Y1) / 2.
[0014]
According to the second aspect of the present invention, in the release agent leveling roller according to the first aspect, when (X1-Y1) / 2 = Z1 and (X2-Y2) / 2 = Z2, Z2 = 0.6 mm. -Z1 to 0.8 mm-Z1.
[0015]
According to a third aspect of the present invention, in the release agent leveling roller according to the first or second aspect, the hardness C1 at both ends is higher than the hardness C2 at the center.
[0016]
According to a fourth aspect of the present invention, in the release agent leveling roller according to the third aspect, C1 = C2 + 20 to 30 ° (Asker C).
[0017]
According to a fifth aspect of the present invention, in the release agent leveling roller according to the third or fourth aspect, C2 = 10 to 20 ° (Asker C).
[0018]
According to a sixth aspect of the present invention, in the release agent leveling roller according to any one of the first to fifth aspects, the releasability is greater than or equal to the releasability of a member leveling the release agent. It is characterized by.
[0019]
According to a seventh aspect of the present invention, the release agent leveling roller according to any one of claims 1 to 6 and the release agent leveling roller are arranged to face each other, and the diameter of the central portion is set to be large. The fixing device includes a roller having X1 and a diameter of Y2 at both ends.
[0020]
According to an eighth aspect of the present invention, in the fixing device according to the seventh aspect, the release agent leveling roller leveles the release agent on the roller.
[0021]
According to a ninth aspect of the present invention, in the fixing device according to the seventh aspect, the belt-like member wound around the roller is included, and the release agent leveling roller is a release agent on the belt-like member. It is characterized by leveling.
[0022]
According to a tenth aspect of the present invention, there is provided an image forming apparatus comprising the release agent leveling roller according to any one of the first to sixth aspects, or the fixing device according to any one of the seventh to ninth aspects. It is in.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic diagram of a release agent leveling roller, a fixing device, and an image forming apparatus having the same according to an embodiment to which the present invention is applied. The image forming apparatus shown in FIG. Show. The image forming apparatus is not limited to a copying machine, but may be a printer or a facsimile apparatus. The image forming apparatus 1 forms a single color image, but may be capable of forming a color image. The image forming apparatus 1 can use plain paper as well as special sheets such as thick paper and OHP sheets as paper that is transfer paper as a sheet-like recording medium.
[0024]
The image forming apparatus 1 is an in-cylinder discharge type image forming apparatus capable of discharging paper within the housing 1A, rather than discharging paper outside the housing 1A. The image forming apparatus 1 is provided with a paper discharge tray 2 that is a paper discharge unit at a substantially central portion in the height direction of the housing 1A. A forming unit 4 is provided.
[0025]
In the case of this embodiment, the image forming unit 4 includes a photosensitive drum 5 as an image carrier corresponding to a drum-like latent image carrier, and the photosensitive drum 5 is illustrated in FIG. Rotates counterclockwise. Around the photosensitive drum 5, a charging device 6, a writing device 7, a developing device 8, a transfer device 9 and a cleaning device 10 for performing an electrophotographic copying process along the rotational direction are arranged.
[0026]
Below the photosensitive drum 5, a paper feeding device 11 that stacks paper and supplies the loaded paper to the image forming unit 4 is disposed, and in the paper feeding direction indicated by a two-dot chain line arrow. A fixing device 12 as a belt fixing device as a belt fixing unit and a paper discharging device 13 as a paper discharging unit are disposed downstream of the transfer device 9 and upstream of the paper discharge tray 2.
[0027]
The document reading unit 3 is equipped with a light source 3A for scanning the document placed on the document placement table and an optical path conversion reflecting mirror 3B, and the reflected light from the document is read out via a reading optical system 3C such as a CCD. And is output to the control unit 14 as image information of the original by the optical element 3D.
[0028]
Although not shown in the drawing, the writing device 7 is a polygon through a semiconductor laser that performs irradiation according to image information and the like of the document input to the control unit 14, and a reflecting mirror and an imaging lens that form an imaging optical system. An electrostatic latent image is formed by irradiating the photosensitive drum 5 with scanning light from the mirror 7A.
[0029]
The sheet feeding device 11 includes a sheet feeding tray feeding roller and a registration roller having a known structure. As the sheet feeding device, as shown by a two-dot chain line in the figure, a single sheet feeding tray that can be opened and closed is provided at a part of the wall portion of the image forming apparatus 1, and the sheet feeding to the image forming unit 4 is performed by any one of them. It has come to be.
[0030]
The semiconductor laser is controlled to emit light based on an image signal from the control unit 14, and the control unit 14 not only provides image information from the document reading unit 3, but also print signals for use as a printer. Drive control of the semiconductor laser is performed by an image signal corresponding to a transmission signal when used as a facsimile apparatus. Here, the control unit 14 gives the image forming apparatus 1 a characteristic as a digital multi-function machine having functions as a printer and a facsimile machine as well as a copying machine.
[0031]
As shown in FIG. 2, the fixing device 12 is disposed so as to face the fixing roller 12 </ b> A and the fixing roller 12 </ b> A capable of interlocking rotation by contacting and facing each other so that the paper P can be nipped and conveyed. A heating belt 12C in which a heating belt 12C is stretched between a pressing roller 12B as a pressing member, a heating belt 12C as a fixing member that is a rotating fixing belt as a sheet conveying member, and the fixing roller 12A. A heating roller 12D for heating.
[0032]
The fixing device 12 also comes into contact with the heating belt 12C from the inside at a part of the extended surface of the heating belt 12C in order to increase the width of the nip portion 16 that is the contact area between the heating belt 12C and the pressure roller 12B, ie, the nip width. A tension roller 12E is provided as a fixing auxiliary roller for winding the belt 12C around the pressure roller 12B.
[0033]
The fixing device 12 also includes an application device 20 for applying oil as a release agent such as silicone oil for preventing offset to the heating belt 12C, an oil supply roller 21 to which oil is supplied by the application device 20, and an oil It has an application roller 22 as an oil application roller that is in contact with the supply roller 21 and is supplied with oil, and is in contact with the heating belt 12C at a position facing the fixing roller 12A and applies oil.
[0034]
The fixing device 12 is also in contact with the heating belt 12C at a position facing the fixing roller 12A, upstream of the application roller 22 in the rotation direction of the heating belt 12C, and releasing the silicone oil or the like applied to the heating belt 12C. An oil auxiliary roller 100 as a release agent leveling roller for leveling the oil as the agent is provided.
[0035]
The fixing device 12 is also in contact with the heating belt 12C at a position facing the fixing roller 12A upstream of the oil auxiliary roller 100 in the rotation direction of the heating belt 12C and is driven to rotate by the heating belt 12C. A cleaning roller 29 is provided as a belt cleaning roller for removing the foreign matter such as toner adhering to the toner and cleaning the heating belt 12C.
[0036]
The fixing device 12 also contacts the heating belt 12C at a position on the upstream side of the cleaning roller 29 in the rotation direction of the heating belt 12C and on the downstream side of the nip portion 16, facing the fixing roller 12A in the vicinity of the nip portion 16. A separation claw 30 is provided as a separation member for contacting the sheet P that has passed through the nip portion 16 and separating the sheet P from the heating belt 12C.
[0037]
Inside the pressure roller 12B and the heating roller 12D, a pressure heater 25 and a heater 26, which are heaters as heating sources and heating means, are arranged, respectively. Further, thermistors 27 and 28 as temperature detecting means are in contact with the peripheral surfaces of the pressure roller 12B and the heating roller 12D, respectively, and the energization to the pressure heater 25 and the heater 26 is controlled based on the detected temperature. Thus, the temperatures of the rollers 12B and 12D are controlled.
[0038]
As a result, the temperature of the heating belt 12C is controlled to be substantially uniform at the predetermined fixing temperature at the nip portion 16, and the sheet P carrying the toner image T is passed from the lower side in FIG. The toner image T on the paper P is fixed on the paper P by heating, melting, and pressing.
[0039]
The position of the tension roller 12E that comes into contact with the expansion surface of the heating belt 12C is a position facing the peripheral surface of the pressure roller 12B, and the contact range of the heating belt 12C with the pressure roller 12B is the tension roller 12E and the pressure roller. From the position opposed to 12B to the position opposed to the fixing roller 12A and the pressure roller 12B, the heating range for the paper P is widened. The heating belt 12C is wound around the fixing roller 12A, the pressure roller 12B, and the tension roller 12E.
[0040]
The coating device 20 improves the releasability by applying oil to the surface of the heating belt 12C to make it difficult for the unfixed toner constituting the toner image T carried on the paper P to reversely transfer to the surface of the heating belt 12C. It is provided for the purpose. The coating device 20 is mounted on the housing portion 12F of the fixing device 12.
[0041]
The coating device 20 holds oil to be applied to the heating belt 12C, and an oil holding unit 20C as an oil impregnated pad that is sealed except for an oil discharge unit 20A described later, and an oil holding unit 20C using osmotic pressure. The oil transporting part 20B capable of sucking up the oil held in the oil and the oil sucked up by the osmotic pressure provided at the position opposite to the oil holding part 20C in the oil transporting part 20B are delivered to the oil supply roller 21. And an oil discharge part 20A.
[0042]
For the oil holding portion 20C, it is possible to use a bag body that can enclose oil or a pad-like fiber member such as cotton that can be impregnated with oil. The oil transport section 20B is a member made of a porous or fiber member, and aramid felt, ceramic paper, or the like is used. Although not shown, an elastic body such as a leaf spring is integrated as a backing member to provide flexibility. It is provided.
[0043]
The oil discharge part 20A is positioned higher than the oil holding part 20C and integrated with the oil transport part 20B on the surface facing the oil supply roller 21 side. 20 A of oil discharge parts are comprised with the nonwoven fabric which consists of an aramid / PET mixed material which can ooze out oil. Since the oil discharge unit 20A is positioned higher than the oil holding unit 20C and is opposed to the weight direction, it is possible to prevent an excessive supply state from exceeding the suction amount due to the osmotic pressure.
[0044]
20 A of oil discharge parts are press-contacted to the oil supply roller 21 using the elastic restoring force of the oil transport part 20B at the time of bending deformation by contact | abutting to the oil supply roller 21. As shown in FIG. Specifically, the oil discharge portion 20 </ b> A is in pressure contact with the oil supply roller 21 with 1 kgf over the entire width toward the center of the oil supply roller 21.
[0045]
The heating belt 12C is an endless belt-like member having a diameter of 60 mm in a cylindrical state and a base made of polyimide belt resin having a thickness of 90 μm, and disposed on the outer periphery of the base. It has a surface layer that forms an oil-carrying layer with a thickness of 150 μm and is coated with high-release silicone rubber, and has a low heat capacity and good thermal responsiveness.
[0046]
The heating roller 12D is a hollow aluminum pipe having a thickness of 1 mm and a diameter of 30 mm. The pressure roller 12B is a silicon rubber roller having a diameter of 40 mm, which has a hollow core metal and a 1.5 mm thick silicon rubber elastic layer disposed on the outer periphery of the core metal. It is in contact with the surface layer forming the peripheral surface and rotates in the same direction as the heating belt 12C at the nip portion 16. The tension roller 12E is made of SUS and has a diameter of 8 mm. The separation claw 30 is in sliding contact with the central portion of the heating belt 12C in the axial direction of the fixing roller 12A, in other words, in the width direction of the heating belt 12C, that is, in the direction perpendicular to the paper surface in FIG.
[0047]
The fixing roller 12A is a silicon sponge roller having a solid metal cored bar made of iron and an elastic layer of silicon rubber that is foamed silicon disposed on the outer periphery of the cored bar. The cored bar has the same diameter throughout the axial direction of the fixing roller 12A. In the elastic layer, the thickness of the central portion in the axial direction is 0.3 mm thicker than the thickness of both end portions. Accordingly, the fixing roller 12A has a diameter Y1 at both ends of 30 mm, a center diameter X1 of 30.6 mm, and a center diameter X1 at both ends. It has a drum shape larger than the diameter Y1.
[0048]
Here, assuming that the diameter of the central portion of a general roller is X and the diameter of both ends is Y, the value Z obtained by (XY) / 2 is called the crown amount, and Z = When 0, the roller has a cylindrical shape, but when Z ≠ 0, the roller has a drum shape, in other words, a crown shape. When Z ≠ 0 and Z takes a positive value, the roller is said to be a positive crown roller, and when Z takes a negative value, the roller is said to be a reverse crown roller. .
[0049]
Since the crown amount Z1 of the fixing roller 12A = (X1-Y1) /2=0.3 (> 0) mm, the fixing roller 12A has a positive crown shape with a crown amount of 0.3 mm. Such a shape of the fixing roller 12A is formed by a difference in thickness between the central portion and both end portions of the elastic layer. This difference in thickness is formed by polishing the elastic layer. The fixing roller 12A may have a reverse crown shape instead of a regular crown shape.
[0050]
The application roller 22 is a silicon rubber roller having a diameter of 12 mm, which includes a cored bar and an elastic layer of 100 μm thick silicon rubber coated on the outer periphery of the cored bar, and has a surface layer that forms the peripheral surface of the heating belt 12C. It abuts and rotates following the heating belt 12C. The application roller 22 is in pressure contact with the heating belt 12C at 0.5 kgf at both ends toward the center of the fixing roller 12A.
[0051]
The oil supply roller 21 is a silicon rubber roller having a diameter of 10 mm having a cored bar and an elastic layer of silicon rubber having a thickness of 1 mm disposed on the outer periphery of the cored bar. The roller 22 is driven to rotate. Both ends of the oil supply roller 21 are in pressure contact with the application roller 22 at 0.5 kgf toward the center of the application roller 22.
[0052]
In this way, the application roller 22 abuts on the heating belt 12C and rotates following the heating belt 12C, so that the application roller 22 rotates in the same direction as the heating belt 12C at a position facing the heating belt 12C. Reference numeral 21 abuts on the application roller 22 and rotates following the application roller 22 to rotate in the same direction as the application roller 22 at a position facing the application roller 22.
[0053]
Therefore, the oil supply roller 21 supplies the oil delivered from the oil discharge unit 20A to the application roller 22, and the application roller 22 applies the oil supplied from the oil supply roller 21 to the heating belt 12C, thereby heating the oil. It will be applied to the belt 12C. The amount of oil applied to the heating belt 12C is controlled by the pressure among the oil discharge unit 20A, the oil supply roller 21, the application roller 22, and the heating belt 12C.
[0054]
The oil auxiliary roller 100 smoothes the release agent applied on the heating belt 12C. The oil auxiliary roller 100 is disposed to face the fixing roller 12A with the heating belt 12C interposed therebetween, and both ends of the oil auxiliary roller 100 are pressed against the heating belt 12C at 0.5 kgf toward the center of the fixing roller 12A. Yes. The oil auxiliary roller 100 contacts the heating belt 12C and rotates following the heating belt 12C, so that the oil auxiliary roller 100 rotates in the same direction as the heating belt 12C at a position facing the heating belt 12C.
[0055]
The oil auxiliary roller 100 is a silicon sponge roller having a solid metal cored bar made of iron and an elastic layer of silicon rubber that is foamed silicon disposed on the outer periphery of the cored bar. The cored bar has the same diameter throughout the axial direction of the oil auxiliary roller 100, that is, the direction perpendicular to the paper surface in FIG. In the elastic layer, the thickness of the central portion in the axial direction is 0.3 mm thicker than the thickness of both end portions.
[0056]
As a result, the oil auxiliary roller 100 has a positive diameter Y2 with a diameter Y2 of 30 mm and a central diameter X2 of 30.6 mm and a crown amount Z2 of 0.3 mm. It has a crown shape. Such a shape of the oil auxiliary roller 100 is formed by a difference in thickness between the central portion and both end portions of the elastic layer, and this difference in thickness is formed by polishing the elastic layer.
[0057]
The crown amount Z2 of the oil auxiliary roller 100 is determined based on the crown amount Z1 of the fixing roller 12A provided with the oil auxiliary roller 100 opposed thereto. Specifically, Z2 is determined to be in the range of Z2 = 0.6 mm−Z1 to 0.8 mm−Z1. In this example, Z2 is determined by Z1 = 0.3 mm and Z2 = 0.6 mm−Z1.
[0058]
The reason why the crown amount Z2 of the oil auxiliary roller 100 is determined to be in the range of Z2 = 0.6 mm−Z1 to 0.8 mm−Z1 is that heating due to excessive release agent that occurs after leaving without fixing for a long time. This is for eliminating unevenness of the release agent on the surface of the belt 12C and preventing uneven glossiness of the paper. Moreover, due to the unevenness of oil, the relative vibration generated by mechanical vibration between the application roller 22 and the heating belt 12C, that is, noise caused by chatter is eliminated, and further, the oil unevenness caused by such chatter is eliminated. This is to prevent uneven glossiness of the paper.
[0059]
In the conventional leveling roller, these unevenness in gloss is significantly generated in the central portion because the leveling effect of the oil in the central portion is lower than the leveling effect of the oil in the end portion. However, by determining the crown amount Z2 of the oil auxiliary roller 100 as described above, the leveling is performed well even in the central portion, and such uneven gloss is prevented. Depending on the value of the crown amount Z1 of the fixing roller 12A, the shape of the oil auxiliary roller 100 may be a reverse crown shape.
[0060]
The hardness C1 at both ends of the oil auxiliary roller 100 is set higher than the hardness C2 at the center. Specifically, C1 is Asker C with a hardness of 40 °, and C2 is Asker C with a hardness of 20 °. This difference in hardness is formed by varying the foaming degree of the foamed silicon forming the elastic layer. That is, the oil auxiliary roller 100 is configured by attaching three foamed silicons of substantially the same length on the core metal, and has a foaming degree larger than that of the foamed silicon attached to both ends. Silicon is used as foamed silicon attached to the central part.
[0061]
Although the hardness is set in this way, by setting the crown amount Z2 of the oil auxiliary roller 100 as described above, it is possible to sufficiently suppress oil unevenness that appears as gloss unevenness for paper that is plain paper, This is because when the OHP sheet is used as the paper, the oil unevenness is not sufficiently suppressed even if the crown amount Z2 is set as described above. When an OHP sheet is used as the paper, if the oil with unevenness is transferred to the OHP sheet, the oil unevenness appears prominently in the projected image when the OHP sheet is projected. It is necessary to suppress it.
[0062]
Specifically, the oil streaks generated in the central portion in the width direction of the heating belt 12C due to the contact of the separation claw 30 are sufficient to prevent uneven glossiness of plain paper by setting the crown amount Z2 as described above. However, when the image is transferred to the OHP sheet, streaks of a degree that can be visually confirmed are generated in the projected image. Therefore, the values of C1 and C2 and the difference between them are set as described above. Thereby, the leveling effect at the center of the heating belt 12C by the oil auxiliary roller 100 is further improved, and the streak in the OHP projection image caused by the oil streak generated by the separation claw 30 is also eliminated.
[0063]
The values of C1 and C2 and the difference between them are not limited to those described above. In Asker C, if C1 = C2 + 20 to 30 ° and C2 = 10 to 20 °, The streaks that are visually confirmed in the projected image caused by the transferred oil streaks generated by the separation claws 30 are eliminated. If the C1 portion and the C2 portion have the same length in the axial direction of the oil auxiliary roller 100, it is suitable for simplifying the manufacture of the oil auxiliary roller 100. However, these may not be the same length, The length can be set to an appropriate length so as to satisfactorily eliminate oil unevenness.
[0064]
Here, when the toner offset from the sheet P to the heating belt 12C adheres to the oil auxiliary roller 100, the oil leveling performance and durability of the oil auxiliary roller 100 deteriorates, or such toner adhered to the leveling roller. After peeling off, it may stick to the paper. In order to prevent this, the releasability on the surface of the oil auxiliary roller 100 may be equal to or higher than the releasability on the surface of the heating belt 12C.
[0065]
Therefore, the foamed silicon that is the material of the elastic layer that forms the surface layer of the oil auxiliary roller 100 is the same as the material of the high release silicone rubber that forms the surface layer of the heating belt 12C. Therefore, the surface releasability of the oil auxiliary roller 100 is the same as the surface releasability of the heating belt 12C. Since the surface releasability of the surface of the oil auxiliary roller 100 only needs to be greater than or equal to the surface releasability of the surface of the heating belt 12C, the surface releasability of the surface of the oil auxiliary roller 100 is determined as that of the surface of the heating belt 12C. This may be ensured by appropriately selecting materials that satisfy the surface layer of the auxiliary oil roller 100 and the surface layer of the heating belt 12C. Further, in order to make the releasability of the surface of the oil auxiliary roller 100 equal to or higher than the releasability of the surface of the heating belt 12C, a coating satisfying this is applied to the surface of the oil auxiliary roller 100 and the surface of the heating belt 12C. Is also possible.
[0066]
The oil auxiliary roller 100 as the release agent leveling roller to which the present invention is applied, the fixing device 12 having the same, and the image forming apparatus 1 having these have been described. The fixing device 12 is a so-called belt fixing device, and an example is shown in which the present invention is applied thereto. However, the fixing device to which the present invention is applied may be a heat roller pair type fixing device.
[0067]
The fixing device of the heat roller pair type includes, for example, a fixing roller as a fixing member heated by a heater as a heating unit, a pressure roller in contact with the fixing roller, and the like. A sheet-like recording medium on which toner is fixed is conveyed and passed through a nip portion that is a contact area with the roller by rotation of a fixing roller and a pressure roller, and a toner image is fixed by heating and pressing. is there.
[0068]
When the present invention is applied to this type of fixing device, the release agent leveling roller to which the present invention is applied is disposed to face the fixing roller, and equalizes the release agent on the fixing roller. The crown amount Z2 of the release agent leveling roller is determined in the same manner as described above by the crown amount Z1 of the fixing roller. Further, the releasability of the release agent leveling roller is greater than the releasability of the fixing roller.
[0069]
【The invention's effect】
The present invention relates to a release agent leveling roller for leveling the release agent, which is disposed opposite to a roller having a diameter at the center portion of X1 and a diameter of both ends at Y1. In the release agent leveling roller provided, the value of (X2-Y2) / 2 is (X1-Y1), where X2 is the diameter of the central portion and Y2 is the diameter of both ends. ) / 2 is determined based on the value of / 2, so that it has a small space, low cost, and high durability, and a mold suitable for leveling the mold release agent according to the shape of the opposing roller. Excessive agent, unevenness of release agent due to separation claw, and release agent unevenness when passing large size paper after passing small size paper can be eliminated, and this prevents so-called chatter Can contribute to the prevention of unevenness of the release agent due to chatter. It becomes possible, thus providing a release agent release agent smoothing roller which contributes to obtaining a good fixed image to prevent gloss unevenness due to unevenness of.
[0070]
When (X1−Y1) / 2 = Z1 and (X2−Y2) / 2 = Z2, assuming that Z2 = 0.6 mm−Z1 to 0.8 mm−Z1, small space, low cost, In addition to having high durability, the shape of the release agent is determined according to the shape of the opposing roller so that the shape is suitable for preventing unevenness of the release agent. Excessive mold material, unevenness of release agent due to separation nails, and unevenness of release agent when passing large-size paper after passing small-size paper can be eliminated. Release agent leveling that can contribute to preventing unevenness of the release agent due to chattering, and thus can contribute to obtaining a good fixed image that prevents unevenness of gloss caused by unevenness of the release agent. A roller can be provided.
[0071]
If the hardness C1 at both ends is made higher than the hardness C2 at the central portion, the leveling effect of the release agent at the central portion can be further improved, and the uneven glossiness of the paper that occurs remarkably in the central portion can be improved. Further, it is possible to provide a release agent leveling roller that can be prevented well and contribute to obtaining a good fixed image.
[0072]
If C1 = C2 + 20 to 30 ° (Asker C), the leveling effect of the release agent in the central part can be further improved by defining the relationship between the hardness of the central part and the hardness of both end parts. In addition, it is possible to provide a release agent leveling roller that can better prevent uneven glossiness of the paper that occurs remarkably in the central portion and contribute to obtaining a good fixed image.
[0073]
If C2 = 10 to 20 ° (Asker C), the leveling effect of the release agent in the central part can be further improved by determining the hardness of the central part, and it is remarkably generated in the central part. Accordingly, it is possible to provide a release agent leveling roller that can further prevent uneven glossiness of the paper to be used and contribute to obtaining a good fixed image.
[0074]
If the releasability is equal to or higher than the releasability of the member that leveles the release agent, it prevents the offset toner from adhering and prevents the leveling performance and durability of the release agent from deteriorating. In addition, it is possible to provide a release agent leveling roller that can prevent the attached toner from being peeled off and then attached to the paper and contribute to obtaining a good fixed image over time.
[0075]
According to the present invention, the release agent leveling roller according to any one of claims 1 to 6 and the release agent leveling roller are disposed to face each other, the diameter of the central portion is X1, and both ends Since the fixing device has a roller whose diameter is Y2, it has a release agent leveling roller that exhibits the above-mentioned effects, and has a small space, low cost, high durability, and separation. It is possible to provide a fixing device capable of obtaining a good fixed image in which uneven gloss due to unevenness of the mold is prevented.
[0076]
If the release agent leveling roller equalizes the release agent on the opposite roller, it has a small space, low cost, high durability, and also prevents gloss unevenness due to release agent unevenness. It is possible to provide a heat roller pair type fixing device capable of obtaining a stable fixed image.
[0077]
If the release agent leveling roller has a belt-like member wound around the opposite roller, and the release agent leveling roller leveles the release agent on the belt-like member, a small space Thus, it is possible to provide a belt fixing device that is low in cost and high in durability, and that can obtain a good fixed image that prevents uneven gloss due to unevenness of a release agent.
[0078]
The present invention resides in an image forming apparatus having the release agent leveling roller according to any one of claims 1 to 6 or the fixing device according to any one of claims 7 to 9. Having a release agent leveling roller or fixing device that achieves the above-mentioned effects, it has a small space, low cost, high durability, and a good fixed image that prevents uneven gloss caused by unevenness of the release agent By obtaining the image forming apparatus, an image forming apparatus capable of performing good image formation can be provided.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a fixing device having a release agent leveling roller to which the present invention is applied and an image forming apparatus having the fixing device.
FIG. 2 is a schematic diagram of the fixing device shown in FIG.
[Explanation of symbols]
1 Image forming device
12 Fixing device
12A Roller with release agent leveling rollers facing each other
12C Belt-shaped member that is a member to level the release agent

Claims (10)

A release agent leveling roller for leveling the release agent, which is disposed opposite to a roller having a diameter of X1 at the center and a diameter of Y1 at both ends. In the mold leveling roller,
The value of (X2−Y2) / 2 is determined based on the value of (X1−Y1) / 2, where X2 is the diameter of the central portion and Y2 is the diameter of both ends. Release agent leveling roller. In the release agent leveling roller according to claim 1,
When (X1-Y1) / 2 = Z1 and (X2-Y2) / 2 = Z2,
Z2 = 0.6mm-Z1 to 0.8mm-Z1
A release agent leveling roller. In the release agent leveling roller according to claim 1 or 2,
A release agent leveling roller characterized in that the hardness C1 at both ends is higher than the hardness C2 at the center. In the release agent leveling roller according to claim 3,
C1 = C2 + 20-30 ° (Asker C)
A release agent leveling roller. In the release agent leveling roller according to claim 3 or 4,
C2 = 10-20 ° (Asker C)
A release agent leveling roller. The release agent leveling roller according to any one of claims 1 to 5, wherein the release property is equal to or higher than the release property of a member leveling the release agent. Roller. The release agent leveling roller according to any one of claims 1 to 6 and the release agent leveling roller are arranged to face each other, the diameter of the central part is X1, and the diameters of both ends are A fixing device having a roller having a size of Y2. 8. The fixing device according to claim 7, wherein the release agent leveling roller leveles the release agent on the roller. 8. The fixing device according to claim 7, further comprising a belt-like member wound around the roller, wherein the release agent leveling roller leveles the release agent on the belt-like member. Fixing device. An image forming apparatus comprising the release agent leveling roller according to any one of claims 1 to 6 or the fixing device according to any one of claims 7 to 9.

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