JP2005321624A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of obtaining a high quality image by uniformly applying wax to a fixing rotary body, thereby restraining a toner offset phenomenon, wrapping of a transfer material around the fixing rotary body, and nonuniform glossiness, wax streaks, etc. of an obtained fixed image, and to provide an image forming apparatus. <P>SOLUTION: The fixing device includes the fixing rotary body for fixing a toner image onto a transfer material under heat. The fixing rotary body is provided with a wax-applying means for applying wax to the surface of the fixing rotary body, the wax having an releasing action. The wax-applying means includes: a web impregnated with the wax; and a wax-applying rotary body for applying the wax to the fixing rotary body by rotating in contact with the web and the fixing rotary body. In a position downstream of a wax supply area where the web and the surface of the wax-applying rotary body are in contact with each other in the rotating direction, a wax-spreading member is disposed opposite to and in contact with the surface of the wax-applying rotary body. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device and an image forming apparatus.

  In general, in an electrophotographic image forming apparatus, in order to fix a toner image formed on one surface of a transfer material such as paper to the transfer material by heating, one fixing rotator which is in contact with the one surface of the transfer material In addition, a fixing device is widely used that includes the other fixing rotator arranged so as to be in pressure contact with the one fixing rotator.

In such a fixing device, a transfer material such as paper is sandwiched and pressed in a fixing nip portion formed by a pressure contact portion of a fixing roller which is one fixing rotator and a pressure roller which is the other fixing rotator. The unfixed toner image that is conveyed and formed on the transfer material is fixed by heating.
Thus, during the fixing process by such a fixing device, an offset phenomenon occurs in which toner or the like migrates from the transfer material and adheres to the surface of the fixing roller. In order to solve these problems, there are problems such as smearing, and fixing of a transfer material on which a toner image with a large amount of toner is formed, such as the transfer material wraps around a fixing roller. Conventionally, a fixing device configured to apply silicone oil to a fixing rotating body has been proposed (see, for example, Patent Documents 1 to 3).

  However, in such a fixing device, as a result of the silicone oil applied to the fixing rotator moving to the transfer material, a sticky feeling is generated in the transfer material, and the quality of the obtained fixed image is low. .

Therefore, as a method for solving the above problem without using silicone oil, a toner containing a releasing agent is used as a toner for forming a toner image.
According to the toner containing the wax having a releasing action, when the toner is melted by the heat applied during the fixing process, the wax oozes out between the toner resin and the fixing roller, so that the toner resin The adhesion force to the fixing roller is reduced, and as a result, the toner is prevented from transferring to the fixing roller and the transfer material carrying a large amount of toner is prevented from being wound around the fixing roller.

However, using a toner containing a wax having such a releasing action can suppress the offset phenomenon and the wrapping of the transfer material without applying silicone oil, but the same after the fixing process. If the wax is unevenly distributed on the surface of the transfer material, image defects such as uneven gloss and wax lines may occur in the obtained fixed image, and image quality may be deteriorated.
JP 2002-258657 A JP-A-7-104602 JP-A-9-166933

The present invention has been made on the basis of the above circumstances, and its purpose is to uniformly apply wax to a fixing rotating body, and as a result, toner offset phenomenon and fixing material fixing rotation. An object of the present invention is to provide a fixing device capable of obtaining a high-quality fixed image by suppressing the phenomenon of wrapping around the body and the occurrence of uneven gloss and wax streaks in the obtained fixed image without causing image defects. .
Another object of the present invention is to provide an image forming apparatus including the above-described fixing device.

The fixing device of the present invention is a fixing device including a fixing rotator for thermally fixing a toner image on a transfer material, and for applying a wax having a releasing action on the surface of the fixing rotator. Wax application means are provided,
The wax application means includes a web impregnated with wax, and a wax application rotating body that contacts the web and rotates while contacting the fixing rotation body to apply the wax to the fixing rotation body. ,
A wax spreading member that is in contact with the surface of the wax coating rotator is provided at a position downstream of the wax supply region in contact with the web on the surface of the wax coating rotator in the rotation direction.

  In the fixing device of the present invention, the web is fed out from the original winding portion and conveyed so as to be taken up by the winding portion, and in the conveyance path, the web is fixed at a location downstream of the wax supply region in the conveying direction. It can be set as the structure by which the cleaning area | region which contacts the rotary body for operation is provided.

  In the fixing device of the present invention, the wax spreading member is preferably made of a blade member made of silicone rubber or fluorine rubber.

  Further, the fixing rotator has a heat-resistant elastic layer made of a heat-resistant elastic body having a thickness of 0.2 mm or more. Tetrafluoroethylene (PFA), tetrafluoroethylene is provided on the outermost surface of the fixing rotator. A release layer comprising a release resin containing a fluororesin selected from a copolymer of PTFE and perfluoroalkoxyethylene (PTFE) and a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP) is provided. It can be set as the structure currently provided.

  An image forming apparatus according to the present invention includes the above-described fixing device.

  According to the fixing device of the present invention, the wax is applied to the fixing rotator so that the molten wax basically exists between the toner and the fixing rotator on the surface of the fixing rotator. As a result, excellent releasability of the toner from the fixing rotator is exhibited, and image smearing in the fixed image due to the transfer of the toner to the fixing rotator is suppressed, and a wax coating for applying a wax is performed. By providing the wax spreading member so as to come into contact with the rotating body for fixing, it is possible to obtain a coating state having high uniformity with respect to the wax on the surface of the fixing rotating body. High image quality without image defects such as gloss unevenness and wax streaks that occur due to the coating state having low uniformity. Fixed image can be obtained.

  Further, according to the configuration in which the cleaning area that comes into contact with the fixing rotator is provided in the web after supplying the wax, the deposits on the surface of the fixing rotator are effectively removed in the cleaning area. In addition, toner and other deposits do not migrate to the wax coating rotor, and toner and other deposits are prevented from intervening between the wax coating rotor and the wax spreading member. On the surface of the body, a state having high uniformity with respect to the wax is reliably formed, and it is not necessary to provide a separate cleaning member independently.

  According to the image forming apparatus of the present invention, since the above fixing device is provided, an excellent fixed image can be obtained.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram showing an example of the configuration of the image forming apparatus of the present invention.

The image forming apparatus in this example is a color image forming apparatus, and an image reading unit 11 that optically scans a document to read a document image and forms image data in the image forming apparatus main body, and the image reading device Based on the image data from the section 11, the photoreceptors 31Y, 31M, 31C, and 31K on which toner images are formed, and toner images for forming the toner images on the photoreceptors 31Y, 31M, 31C, and 31K. The pressing rollers 36Y, 36M that press the toner images formed by the developing devices 30Y, 30M, 30C, 30K and the developing devices 30Y, 30M, 30C, 30K to the photoreceptors 31Y, 31M, 31C, 31K. , 36C, 36K, an intermediate transfer member 51 for primary transfer and carrying, and a primary transfer toner image formed on the surface of the intermediate transfer member 51 on paper or the like A secondary transfer portion 39 for transferring to the surface of the transfer material P (see FIG. 2), a fixing device 40 for fixing the secondary transfer toner image transferred to the surface of the transfer material P by heating, and the transfer material P A transport mechanism for transporting and a discharge port 15 for discharging the transfer material P on which visible image formation has been completed are provided.
In the figure, reference numerals 37Y, 37M, 37C, and 37K denote a photoreceptor cleaning section, 54 denotes an intermediate transfer body cleaning section, and 18a, 18b, and 18c denote transfer material accommodation cassettes.

The photoreceptors 31Y, 31M, 31C, and 31K are linearly supported by an intermediate transfer member 51 that is an endless belt that is movably supported by a plurality of rollers 52a, 52b, 52c, and 52d. The intermediate transfer members 51 are arranged in parallel in the circulation direction along the downward portion of the shape, and the developing devices 30Y, 30M, 30C, and 30K correspond to the photoconductors 31Y, 31M, 31C, and 31K, respectively. Is arranged.
Here, the developing device 30Y forms a yellow toner image, the developing device 30M forms a magenta toner image, the developing device 30C forms a cyan toner image, and the developing device 30K. According to this, a black toner image is formed.

In the developing device 30Y, the photoconductor 31Y is placed along the rotation direction on the outer peripheral surface area of the photoconductor 31Y that rotates to move in the forward direction (the arrow direction in FIG. 1) at the transfer position with the intermediate transfer body 51. For example, a charger 32Y for uniformly charging by corona discharge using a grid and a corona discharge wire, and a uniformly charged photoreceptor 31Y based on image data of the image reading unit 11, for example, a laser diode (FIG. An image exposure unit 33Y that forms an electrostatic charge image on the surface thereof by radiating a laser beam from a laser beam (not shown), and a developing device 34Y that develops the electrostatic charge image formed on the surface of the photoreceptor 31Y. Is provided.
In addition, the other developing devices 30M, 30C, and 30K each have the same configuration as the developing device 30Y.

  In such an image forming apparatus, all four developing devices 30Y, 30M, 30C, and 30K are operated, so that a so-called full-color color image can be formed, and the four developing devices 30Y, 30M can be formed. , 30C, and 30K, by selectively using the developing device 30K, it is possible to form a monochrome image using only black toner, for example.

  As shown in FIG. 2, the fixing device 40 is one fixing rotator arranged so as to be in contact with one surface (for example, the upper surface of the transfer material P in FIG. 2) on which the unfixed toner image of the transfer material P is formed. A fixing roller 41, a pressure roller 43, which is the other fixing rotating body provided in pressure contact with the fixing roller 41, and a wax application unit 60 provided in contact with the surface of the fixing roller 41. A fixing nip portion N is formed by a pressure contact portion between the fixing roller 41 and the pressure roller 43. In FIG. 2, 49a and 49b are non-contact type temperature detecting means.

  The fixing roller 41 includes a heating source HLa made of, for example, a halogen heater lamp. The fixing roller 41 has a cylindrical cored bar 41a made of, for example, aluminum, in which the heating source HLa is disposed, and the cored bar. The heat-resistant elastic layer 41b made of, for example, silicone rubber and the like formed on the outer peripheral surface of 41a and the heat-resistant layer through an adhesive layer (not shown) made of, for example, coated and baked mixed latex of fluororubber and fluororesin. It is a soft roller which consists of the coating layer 41c formed in the outer peripheral surface of the elastic layer 41b.

  The heating source HLa is arranged to extend in the length direction of the fixing roller 41 inside the cored bar 41a, so that the temperature of the outer peripheral surface of the fixing roller 41 that is a direct heating target is maintained in the set temperature range. Based on the surface temperature of the fixing roller 41 detected by the temperature detection means 49a, for example, the lighting state is on-off controlled by a control means (not shown).

  The heat-resistant elastic layer 41b preferably has a thickness in the range of 0.2 mm to 2.0 mm. When the thickness is 0.2 mm or more, a high-quality fixed image can be formed, and even if the roller application rotating body 63 described later has a high roller hardness, the web 61 is impregnated. The wax being applied is reliably applied to the fixing roller 41 via the wax applying rotator 63. On the other hand, when the thickness of the heat-resistant elastic layer 41b is 2.0 mm or less, it is possible to sufficiently ensure the thermal response when the surface of the fixing roller 41 is heated by the heating source HLa.

The coating layer 41c is a layer having a function as a release layer for preventing the toner from adhering, and is a polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene (PFA). ), A releasable resin containing a fluororesin selected from a copolymer (FEP) of tetrafluoroethylene and hexafluoropropylene, and the thickness is preferably 20 to 50 μm.
Specifically, the coating layer 41c is formed, for example, by (1) means for forming a thickness of 20 to 50 μm by applying and baking a release resin in a dispersion state, and (2) a thickness of 20 to 50 μm. It can be formed by a means for forming and releasing the releasable resin tube by coating and other means.

Since the covering layer 41c is made of a releasable resin containing a fluororesin, the surface releasability of the fixing roller 41 with respect to the toner is enhanced by the releasable action, so that the deposits derived from the toner during the fixing process In addition to being difficult to adhere to the surface of the fixing roller 41, the peelability of the transfer material P from the fixing roller 41 is increased.
By setting the thickness of the coating layer 41 c to 50 μm or less, a high-quality fixed image can be formed, and the wax application performance of the wax application rotator 63 to the fixing roller 41 is sufficiently exhibited.

As shown in FIG. 2, the pressure roller 43 includes a cylindrical cored bar 43a made of, for example, aluminum, and a heat-resistant elastic layer 43b made of, for example, silicone rubber formed on the outer peripheral surface of the cored bar 43a. A soft roller made of a coating layer 43c made of, for example, a fluororesin, formed on the outer peripheral surface of the heat resistant elastic layer 43b can be used.
In the example of this figure, the pressure roller 43 has a built-in heating source HLa such as a halogen heater lamp, like the fixing roller 41. This heating source HLa is arranged inside the metal core 43a so as to extend in the length direction of the pressure roller 43, and the temperature of the outer peripheral surface of the pressure roller 43, which is a direct heating target, is maintained in the set temperature range. Thus, based on the surface temperature of the pressure roller 43 detected by the temperature detecting means 49b, for example, the lighting state is on-off controlled by a control means (not shown).

  The fixing device 40 is in pressure contact with the fixing roller 41 at a position upstream of the fixing nip portion N in the rotation direction of the fixing roller 41, and is driven by the fixing roller 41 or driven by an appropriate driving unit. A wax applying rotator 63 that is rotated counterclockwise (in the direction of the arrow in FIG. 2) is provided, and is a long sheet-like member that travels in contact with the outer peripheral surface of the wax applying rotator 63. A web 61 is provided.

In addition, the wax application area that is in the rotation direction downstream of the wax supply area A formed by the web 61 being pressed against the surface of the wax application rotating body 63 by the tension of the web 61 and that contacts the fixing roller 41. A wax spreading member 67 is provided in a state of being pressed by the wax applying rotator 63 at a location upstream of B in the rotational direction.
The wax applying means 60 is configured by the above-described rotating body for wax application 63, the web 61, the wax spreading member 67, and the conveying means (not shown) for conveying the web 61.

  The transport means for transporting the web 61 includes an original winding portion 64 having an original winding shaft 64A around which a web 61 impregnated with wax is wound and a reverse tension is applied to prevent the web 61 from loosening. A take-up portion 65 having a take-up shaft 65A rotated clockwise (in the direction of the arrow in FIG. 2) by a source, and a tension roller 62A disposed on the web conveyance path from the original take-up shaft 64A to the take-up shaft 65A, 62B, and these constituent members form a wax supply area A on the path from the web 61 to the tension roller 62B, and the running direction of the web 61 is the wax application direction in the wax supply area A. It arrange | positions so that it may become the same direction as the moving direction of the surface of the rotary body 63. FIG.

  In the wax supply region A, the length extending in the circumferential direction of the wax application rotating body 63 is preferably 10 mm or more. If the length is too small, the wax supplied from the web 61 to the wax applying rotator 63 cannot be reliably applied to the surface of the fixing roller 41.

  The axial width in the wax application area A is preferably equal to or greater than the maximum width of the transfer material P used for image formation. The width in the axial direction in the wax supply region B is also preferably equal to or greater than the maximum width of the transfer material P used for image formation. As a result, image defects such as an offset phenomenon, a wrapping phenomenon of the transfer material, and uneven gloss can be suppressed for any type of transfer material.

  In the wax application unit 60, the web 61 wound around the original winding shaft 64A is rotated by the winding shaft 65A driven by the transport unit, and is wound through the tension rollers 62A and 62B. Thus, it is conveyed so as to pass through the wax supply area A along the web conveyance path.

The web 61 of the wax applying means 60 is impregnated with a wax having a releasing action, and is, for example, a nonwoven fabric containing an aromatic polyamide and / or polyester. For example, the aromatic polyamide and the polyester are 40:60. A sheet having a thickness of 70 μm and a weight per unit area of 30 g / m ² produced by combining them, and preferably having a value having a large Beck smoothness on the surface thereof is used.
Any material may be used for the web 61 as long as it can be impregnated with wax. However, it is preferable to use a nonwoven fabric containing aromatic polyamide and / or polyester from the viewpoint of heat resistance.
Here, “Beck smoothness” refers to a smooth value measured by a smoothness test (JIS P 8119) using a Beck tester.

  Examples of the wax impregnated into the web 61 include paraffin wax, polyolefin wax, modified products thereof (for example, oxides and grafted products), higher fatty acids, and metal salts thereof, amide wax, ester wax, and the like. The conventionally known wax can be exemplified, and for example, higher fatty acid ester wax is preferably used.

The melting point of the wax is preferably 90 ° C. or higher and 120 ° C. or lower.
By setting the melting point of the wax as low as about 120 ° C. or less, if the temperature of the fixing roller 41 is maintained at about 160 ° C. or more, the fixing roller 41 and the rotating body for wax application 63 come into contact with each other. Since the surface temperature in the supply region A can be higher than the melting point of the wax, and the wax is smoothly melted in the wax supply region A, the efficiency of supplying the wax from the web 61 to the rotating body for wax application 63 is improved. improves. Further, by setting the melting point of the wax to 90 ° C. or more, the liquefied wax may fall into the fixing device or fall from the web 61 wound around the original winding shaft 64A to contaminate the device or the transfer material. Disappear.

The conveying speed of the web 61 by the conveying means is preferably in the range of 0.04 to 0.20 mm / copy (when A3 paper is vertically fed).
By setting the conveyance speed of the web 61 to 0.04 mm / copy or more, the wax is reliably applied to the rotating body 63 for wax application, and by setting the conveyance speed to 0.20 mm / copy or less, the service life of the web 61 is extended. As a result, it is possible to obtain an advantage in terms of cost and reduce the necessity of using a very long web 61, so that the accommodation space for the web 61 can be reduced. .

As a material constituting the wax applying rotary body 63 of the wax applying means 60, for example, for a cylindrical cored bar made of aluminum, for example, having a wall thickness of 0.8 to 2 mm, preferably 1 mm and an outer diameter of 24 mm. For example, a film having a thickness of 30 μm and having a Vickers surface hardness Hv of 350 to 400 kg / mm ² is obtained. In this example, it is preferable that the thickness of the core metal is thin as long as no bending occurs. Since the core bar has high thermal conductivity and the surface layer is thin, the surface temperature of the rotating body for wax application 63 for melting the wax can be obtained quickly.
Here, the “Vickers surface hardness Hv” is a hardness that can be measured according to the micro hardness test method of JIS Z 2251. Specifically, using a diamond square pyramid indenter with a diagonal angle of 136 degrees, the load F (kgf) when a depression is made on the test surface is the surface area obtained from the diagonal length d (mm) of the depression. The quotient obtained by dividing is calculated by the following formula (1). However, in Formula (1), d is the average (mm) of the diagonal length of a hollow.
Formula (1): Surface hardness (Hv) = 1.8544 F / d ²

  In the wax applying rotator 63, the surface in the wax supply area A is heated by heat from the fixing roller 41 so that a part of the wax impregnated in the web 61 is melted and supplied to the wax applying rotator 63. The temperature is higher than the melting point of the wax having a releasing action contained in the web 61.

In such a rotating body for wax application 63, the surface roughness Rz is preferably 1.6 μm or less, and particularly preferably 1.0 μm or less.
While the temperature equal to or higher than the melting point of the wax is maintained, a liquid layer is formed with liquid wax on the surface of the wax coating rotating body 63, and the layer thickness is 1 μm or less. By making the value as small as described above, the wax application performance to the surface of the fixing roller 41 is more evenly exhibited.
Here, the “surface roughness Rz” means the average absolute value of the altitude of the highest peak from the highest peak in the region of the reference length of 0.8 mm in JIS B 0601-1982, and 5 from the lowest valley bottom. It is the sum of the absolute values of the elevation of the valley bottom up to the th.

  The wax applying rotator 63 is rotated, for example, at a linear velocity of 220 mm / sec. The wax applying rotator 63 is rotated at this linear speed and the web 61 is conveyed at the above conveying speed, whereby the wax applying rotator 63 is rotated and the web 61 is conveyed in the wax supply region A. Along with this, the web 61 is rubbed, whereby the molten wax impregnated in the web 61 is supplied to the rotating body 63 for wax application.

  The wax application rotator 63 is in contact with the fixing roller 41 with a load of 19.6 to 98N. When the load is 19.6 N or more, the contact state between the wax coating rotator 63 and the fixing roller 41 becomes stable, and when it is 98 N or less, permanent deformation in the heat-resistant elastic layer 41 b of the fixing roller 41 is suppressed. Can do.

  The wax spreading member 67 is formed of a blade member, and a coating layer is formed on a surface of a blade base material formed of an elastic material such as silicone rubber with a fluoro rubber or the like, and the thickness thereof is, for example, 3 mm. It is said.

  For the purpose of forming a state in which the wax supplied from the web 61 has high uniformity on the surface of the wax applying rotator 63, the wax spreading member 67 is formed from the wax application region B on the surface of the wax applying rotator 63. Is provided at a location upstream of the rotation direction and downstream of the wax supply area A, and extends at the contact location in the same direction as the rotation direction of the wax application rotator 63. The pressing force is set in a range of, for example, 50 to 500 mN / cm.

In the fixing device 40 of this example, the fixing roller 41 is pressed against the fixing roller 41 via the web 61 at a location upstream of the wax application region B in the rotational direction and downstream of the fixing nip N. Accordingly, a cleaning pressing member 66 that forms the cleaning region C is provided.
The cleaning pressing member 66 has a roller shape, for example, an elastic layer formed of a silicone sponge on the outer peripheral surface of a core metal such as aluminum, and 20 to 50 N on the fixing roller 41 via the web 61. It is in contact with the load.

  The cleaning pressing member 66 has a cleaning region C formed on a path from the tension roller 62B of the conveying unit to the take-up shaft 65A. In the cleaning region C, the traveling direction of the web 61 moves on the surface of the fixing roller 41. It arrange | positions so that it may become a reverse direction.

  As the toner, for example, toner composed of colored particles containing a binder resin and a colorant is used. The binder resin for the toner is not particularly limited, and a known resin such as a styrene resin, a styrene acrylic copolymer resin, or a polyester resin can be used. The toner particles may further contain a wax having a releasing function as required, but it is preferably suppressed to 5% by weight or less, and it is usually unnecessary to contain the wax. As a result, even when the amount of heat supplied to the toner at the fixing nip is increased, an increase in the amount of the wax exuded from the toner can be suppressed, so that an increase in the amount of wax on the image surface can be suppressed, and the gloss caused thereby. Generation of unevenness can be suppressed.

The operation of the image forming apparatus as described above is as follows.
When all the developing devices 30Y, 30M, 30C, and 30K are operated to form a color image, an image of the original is read by the image reading unit 11 to obtain image data, and based on this image data, By performing exposure in the image exposure sections 33Y, 33M, 33C, and 33K of the developing devices 30Y, 30M, 30C, and 30K, electrostatic images are formed on the surfaces of the photoreceptors 31Y, 31M, 31C, and 31K. The development of the electrostatic charge image is performed by the developing devices 34Y, 34M, 34C, and 34K, whereby toner images of different colors are obtained. The toner images formed on the surfaces of the photoreceptors 31Y, 31M, 31C, and 31K are transferred to the surface of the intermediate transfer member 51 that circulates in this order in the primary transfer portions 35Y, 35M, 35C, and 35K. A primary transfer toner image is superimposed and formed.
Here, after the primary transfer, the photoreceptors 31Y, 31M, 31C, and 31K pass through the photoreceptor cleaning sections 37Y, 37M, 37C, and 37K, respectively, so that the toner remaining on the surface is removed.
On the other hand, for example, the transfer material P is sent out from the transfer material accommodation cassette 18 a by the transport mechanism, and is transported toward the secondary transfer unit 39 in synchronization with the intermediate transfer member 51.

The primary transfer toner image formed on the surface of the intermediate transfer member 51 in this way is secondarily transferred to the transfer material P conveyed in the secondary transfer unit 39. Thereafter, the transfer material P onto which the secondary transfer toner image has been transferred is conveyed toward the fixing device 40, where the toner image is thermally fixed, and a visible image corresponding to the image of the document is formed on the transfer material P. It is formed. Then, the transfer material P on which the visible image is formed is transported by the transport mechanism and discharged to the outside from the discharge port 15, thereby forming a color image.
Further, the intermediate transfer member 51 after the transfer material P is separated passes through the intermediate transfer member cleaning unit 54, whereby the toner remaining on the surface is removed.

  On the other hand, when only one of the four developing devices 30Y, 30M, 30C, and 30K is operated to form a monochrome image, the image reading unit 11 reads the original image based on the image data. The toner image is formed on the surface of the photoreceptor 31K only by the developing device 30K, and the image forming process similar to that for forming the color image is performed except that the primary transfer is performed in the primary transfer unit 35K. A monochrome image is formed.

  During the visible image forming operation of the image forming apparatus as described above, in the wax applying unit 60 of the fixing device 40, the web 61 is wound around the winding shaft 65A, and is then fed out from the original winding shaft 64A to be waxed. In the supply area A, the wax melted by the heat from the heating source HLa is supplied from the web 61 to the wax applying rotator 63 and applied to the surface of the fixing roller 41 by the wax applying rotator 63 in the wax application area B. The

  Then, the transfer material P is conveyed while being pinched by the fixing roller 41 and the pressure roller 43, and the melted wax exists between the toner and the fixing roller 41 in the fixing nip portion N. The heat of the fixing roller 41 and the pressure roller 43 heated by the heating source HLa is transferred to the transfer material P in a state where the excellent releasability from the fixing roller 41 is exhibited and the toner is prevented from moving to the fixing roller. And a fixing process for fixing the toner image on the transfer material P by heating is performed. Thereafter, the toner image is carried out from the discharge port 15 to the outside of the apparatus.

  Thus, in the fixing process, since the melted wax exists between the toner and the fixing roller 41 on the surface of the fixing roller 41, the excellent release property of the toner from the fixing roller 41 is exhibited. Thus, image smearing in the fixed image due to the transfer of toner to the fixing roller 41 is suppressed.

Since the wax spreading member 67 is provided on the wax applying rotator 63, a state of high uniformity of the wax is formed on the surface of the wax applying rotator 63, whereby the fixing roller 41. An application state having a high uniformity with respect to the wax is formed on the surface of the substrate.
As a result, image defects such as gloss unevenness and wax streaks caused by a coating state having low uniformity of wax on the surface of the fixing roller 41 do not occur in the obtained fixed image, and high quality fixing is performed. An image can be obtained.

  Further, the web 61 in which the wax is lost after passing through the wax supply area A is conveyed in the direction opposite to the moving direction of the surface of the fixing roller 41 in the cleaning area C, and slides on the surface of the fixing roller 41, In the fixing nip portion N, deposits derived from the toner transferred from the transfer material P and deposits such as paper dust derived from paper used as the transfer material are removed.

  As described above, since the deposits on the surface of the fixing roller 41 are effectively removed in the cleaning region C, the deposits such as toner do not migrate to the wax applying rotator 63, and therefore the wax applying rotator. No deposits such as toner intervene between 63 and the wax spreading member 67, and a state having a sufficiently high uniformity of the wax is formed on the surface of the rotating body 63 for wax application. There is no need to provide a cleaning member independently.

  According to the image forming apparatus of the present invention, since the above fixing device is provided, an excellent fixed image can be obtained.

Although the embodiment of the present invention has been specifically described above, the present invention is not limited to the above example, and various modifications can be made.
For example, the case where the fixing device of the present invention is applied to a color image forming apparatus has been described above, but the fixing device is not limited to this, and may be applied to, for example, a monochrome image forming apparatus. it can.

It is explanatory drawing which shows an example of a structure of the image forming apparatus of this invention. FIG. 2 is an explanatory diagram illustrating an example of a configuration of a fixing device in the image forming apparatus of FIG. 1.

Explanation of symbols

11 Image reading unit 15 Ejection ports 18a, 18b, 18c Transfer material storage cassettes 30Y, 30M, 30C, 30K Developing devices 31Y, 31M, 31C, 31K Photoconductors 32Y, 32M, 32C, 32K Chargers 33Y, 33M, 33C, 33K Image exposure units 34Y, 34M, 34C, 34K Developers 35Y, 35M, 35C, 35K Primary transfer units 36Y, 36M, 36C, 36K Pressure roller 37Y, 37M, 37C, 37K Photoconductor cleaning unit 39 Secondary transfer unit 40 Fixing device 41 Fixing roller 41a Core metal 41b Heat resistant elastic layer 41c Cover layer 43 Pressure roller 43a Core metal 43b Heat resistant elastic layer 43c Cover layers 49a, 49b Temperature detecting means 51 Intermediate transfer members 52a, 52b, 52c, 52d Roller 54 Intermediate transfer Body cleaning part 60 Wax application means 61 Web 2A, 62B Tension roller 63 Rotating body for wax application 64 Original winding part 64A Original winding shaft 65 Winding part 65A Winding shaft 66 Cleaning pressing member 67 Wax spreading member A Wax supply area B Wax application area C Cleaning area N Fixing Nip part P Transfer material
HLa heating source

Claims (5)

A fixing device including a fixing rotator for thermally fixing a toner image on a transfer material, wherein a wax applying means for applying a wax having a releasing action is provided on the surface of the fixing rotator. And
The wax application means includes a web impregnated with wax, and a wax application rotating body that contacts the web and rotates while contacting the fixing rotation body to apply the wax to the fixing rotation body. ,
Fixing, characterized in that a wax spreading member that comes into contact with the surface of the wax coating rotator is provided at a position downstream of the wax supply area in contact with the web on the surface of the wax coating rotator in the rotation direction. apparatus.   The web is transported so as to be unwound from the original winding unit and wound up by the winding unit, and in the transport path, the web is in contact with the fixing rotating body at a location downstream of the wax supply region in the transport direction. The fixing device according to claim 1, wherein the fixing device is provided.   The fixing device according to claim 1, wherein the wax spreading member is a blade member formed of silicone rubber or fluorine rubber.   The fixing rotator has a heat-resistant elastic layer made of a heat-resistant elastic body having a thickness of 0.2 mm or more, and tetrafluoroethylene (PFA), tetrafluoroethylene, and the like are provided on the outermost surface of the fixing rotator. A release layer made of a release resin containing a fluororesin selected from a copolymer of perfluoroalkoxyethylene (PTFE) and a copolymer of tetrafluoroethylene and hexafluoropropylene (FEP) is provided. The fixing device according to claim 1, wherein the fixing device is a fixing device. An image forming apparatus comprising the fixing device according to claim 1.

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