JP2012113089A - Fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of suppressing temperature unevenness on a member surface in an axis direction and of obtaining excellent image quality, and further to provide an image forming device.SOLUTION: A fixing device comprises: a fixing member of a rotating endless belt; a pressure member for forming a nip part by being pressed against an outer peripheral surface of the fixing member; a heating member, which is a pipe member and of which an outer peripheral surface is brought into sliding contact with an inner peripheral surface of the fixing member, fixed to inside of the fixing member; heaters 25, which are halogen heaters, fixed to an inside of the heating member for heating the heating member; and a reflection member 24 fixed to the inside of the heating member in such a manner that the reflection member 24 is opposite to the heaters 25 having a reflection surface 24r, which reflects light emitted from the heaters 25 to an inner peripheral surface of the heating member. The reflection surface 24r of the reflection member 24 has recesses 24b and/or protrusions 24a corresponding to a dense state of winding density of filaments 25f in an axis direction of the heaters 25.

Description

  The present invention relates to a fixing device for fixing toner on a recording medium by heat and pressure, and image formation such as FAX, printer, copying machine or their combined machine using an electrophotographic system, electrostatic recording system, etc. equipped with the fixing device. It relates to the device.

  Conventionally, a heat roller fixing device is known as a fixing device used in an image forming apparatus such as a printer or a copying machine. In the heat roller fixing device, a heat source such as a halogen lamp is provided inside, and a contact nip portion (fixing nip portion) of two heating rollers (fixing roller and pressure roller) which are heated and pressed against each other to rotate. Then, a transfer material on which an unfixed developer image is placed is passed, where the developer image is melted and fixed on the transfer material.

  On the other hand, in recent years, the demand for energy saving and shortening of the wait time has increased, so by adopting a heating device that uses a belt or thin film instead of a heating roller, the heat capacity of the fixing device has been reduced, and transfer A so-called on-demand type fixing device has been widely adopted in which the heat transfer efficiency to the material is improved and the waiting time (warm-up time) required for heating is greatly shortened (see, for example, Patent Document 1).

Specifically, the fixing device disclosed in Patent Document 1 includes a fixing belt as a fixing member, a substantially cylindrical metal member (opposing member) fixed so as to face part or all of the inner peripheral surface of the fixing belt, In order to heat the metal member, a heater provided in the metal member, a pressure roller as a pressure rotating body that presses against the fixing belt to form a nip portion, and the like are configured.
The fixing belt is heated by the metal member heated by the heater, and the toner image on the recording medium conveyed toward the nip portion is fixed on the recording medium by receiving heat and pressure at the nip portion. It will be.

  Patent Document 1 discloses a fixing device in which a fixing member that presses against a pressure roller via a fixing belt to form a nip portion and a reinforcing member that reinforces the fixing member are installed. Furthermore, a technique is disclosed in which part or all of the surface of the reinforcing member facing the heater is mirror-finished and heat directed from the heater toward the reinforcing member is used to heat the metal member.

  In Patent Documents 2 and 3, in a fixing device using a halogen heater, the temperature rise efficiency is improved by providing a reflecting member that reflects light (infrared rays) radiated from the halogen heater and condenses locally. A technique for shortening the heating time and reducing power consumption is disclosed.

  However, in such a fixing device, the temperature unevenness in the axial direction appears remarkably on the surface of the fixing member (fixing belt), and the gloss unevenness of the fixed image is generated.

  The present invention has been made in view of the above-described problems in the prior art, and provides a fixing device that suppresses temperature unevenness in the axial direction on the surface of a fixing member and obtains good image quality, and an image forming apparatus including the fixing device. The purpose is to provide.

The present invention provided to solve the above problems is as follows. In addition, the site | part and code | symbol etc. which respond | correspond in the form for implementing this invention in a parenthesis are shown.
[1] A rotating endless belt fixing member (fixing belt 21), a pressure member (pressure roller 31) that presses against an outer peripheral surface of the fixing member to form a nip portion, and an inside of the fixing member A heating member (heating member 22), which is a fixed pipe member whose outer peripheral surface is in sliding contact with the inner peripheral surface of the fixing member, and a halogen heater (heater) which is fixed inside the heating member and heats the heating member. 25) and a reflection surface (reflection surface 24r) that is fixed inside the heating member so as to face the halogen heater and reflects light emitted from the halogen heater to the inner peripheral surface of the heating member. A reflecting surface of the reflecting member corresponding to the density of the winding density of the filament in the axial direction of the halogen heater, and / or a protruding portion (convex portion). 24a) A fixing device (fixing device 20, FIGS. 2 to 5) characterized by comprising:
[2] The halogen heater has a light emitting region in which a plurality of coiled filaments (filament 25f) are connected in series, and the coil portion (coil portion 25a) of the filament has a winding density in the light emitting region. The fixing device according to [1] (FIGS. 3 and 4), wherein the fixing portion (FIG. 3 and FIG. 4) is a dense region and a connecting portion (connecting portion 25b) of the filament is a region having a low winding density.
[3] The fixing device according to [1] or [2], wherein the concave portion of the reflecting surface is formed to correspond to a region where the winding density of the filament is coarse. 4).
[4] The fixing device according to any one of [1] to [3], wherein the convex portion of the reflecting surface is formed to correspond to a region where the winding density of the filament is dense. 3 and 4).
[5] The fixing device according to any one of [1] to [4], wherein the reflecting member is a plate member having the reflecting surface (FIGS. 3 and 4).
[6] The method according to any one of [1] to [5], wherein the region of the reflecting surface in the axial direction of the reflecting member is in a suspended state that is not in contact with another member. Fixing device (FIGS. 3 and 4).
[7] The fixing device according to any one of [1] to [6], wherein the reflecting member is supported at both end portions outside the region of the reflecting surface in the axial direction. 3, FIG. 4).
[8] The fixing device according to any one of [1] to [7], wherein the reflecting surface of the reflecting member is formed by depositing Ag on an Al surface.
[9] The reflecting surface of the reflecting member has an inclination (inclined surface 24c) in which the reflecting surface gradually approaches the halogen heater as it goes toward the end in each of the axially opposite end regions. The fixing device according to any one of [1] to [8] (FIG. 4).
[10] An image forming apparatus (image forming apparatus main body 1, FIG. 1) comprising the fixing device (fixing device 20) according to any one of [1] to [9].

According to the fixing device of the present invention, the reflection surface of the reflection member has the recesses and / or protrusions corresponding to the density of the winding density of the filament in the axial direction of the halogen heater. However, the light from the area where the filament winding density of the halogen heater is coarse is condensed in the axial direction on the inner peripheral surface of the heating member, or the light from the area where the projection on the reflecting surface is dense with the filament heating density of the halogen heater. Since it is scattered in the axial direction, it is possible to reduce the influence of the light emission unevenness in the axial direction of the halogen heater on the fixing member, and to suppress temperature unevenness in the axial direction of the fixing member and to prevent uneven glossiness of the fixed image. It becomes possible.
According to the image forming apparatus of the present invention, since the fixing device of the present invention is provided, the temperature rise time is short, the power consumption is reduced, and an image with better image quality can be formed.

1 is a cross-sectional view showing an overall configuration of an image forming apparatus according to the present invention. 1 is a cross-sectional view showing a basic configuration (1) of a fixing device according to the present invention. It is sectional drawing which shows the structural example (1) of the reflection member used for the fixing apparatus of this invention. It is sectional drawing which shows the structural example (2) of the reflection member used for the fixing apparatus of this invention. FIG. 3 is a cross-sectional view showing a basic configuration (2) of the fixing device according to the present invention.

  The configurations of the fixing device and the image forming apparatus according to the present invention will be described below. In addition, about embodiment, a modification, etc., about the components, such as a member and a component which have the same function, a shape, etc., after having demonstrated once by attaching | subjecting the same code | symbol, the description is abbreviate | omitted. In order to simplify the drawings and the description, even components that are to be represented in the drawings may be omitted as appropriate without being specifically described in the drawings.

A configuration example of the entire image forming apparatus according to the present invention will be described with reference to FIG.
As shown in FIG. 1, the image forming apparatus 1 is a tandem type color printer. Four bottles 102Y, 102M, 102C, and 102K corresponding to the respective colors (yellow, magenta, cyan, and black) are detachably (replaceable) installed in the bottle housing portion 101 above the image forming apparatus main body 1. ing.
An intermediate transfer unit 85 is disposed below the bottle housing portion 101. Image forming units 4Y, 4M, 4C, and 4K corresponding to the respective colors (yellow, magenta, cyan, and black) are arranged in parallel so as to face the intermediate transfer belt 78 of the intermediate transfer unit 85.

  Photosensitive drums 5Y, 5M, 5C, and 5K are disposed in the image forming units 4Y, 4M, 4C, and 4K, respectively. Further, around each of the photosensitive drums 5Y, 5M, 5C, and 5K, a charging unit 75, a developing unit 76, a cleaning unit 77, a charge eliminating unit (not shown), and the like are disposed. Then, an image forming process (charging process, exposure process, development process, transfer process, cleaning process) is performed on each of the photoconductive drums 5Y, 5M, 5C, and 5K. An image of each color is formed on 5K.

The photosensitive drums 5Y, 5M, 5C, and 5K are rotationally driven in a clockwise direction in FIG. 1 by a drive motor (not shown). Then, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K are uniformly charged at the position of the charging unit 75 (a charging process).
Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach the irradiation position of the laser light L emitted from the exposure unit 3, and electrostatic latent images corresponding to the respective colors are formed by exposure scanning at this position. (It is an exposure process.)

Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach a position facing the developing device 76, and the electrostatic latent image is developed at this position to form toner images of each color (developing process). .)
Thereafter, the surfaces of the photoconductive drums 5Y, 5M, 5C, and 5K reach the positions facing the intermediate transfer belt 78 and the first transfer bias rollers 79Y, 79M, 79C, and 79K, and at these positions, the photoconductive drums 5Y, 5M. The toner images on 5C and 5K are transferred onto the intermediate transfer belt 78 (this is a primary transfer process). At this time, a small amount of untransferred toner remains on the photosensitive drums 5Y, 5M, 5C, and 5K.

Thereafter, the surfaces of the photoconductive drums 5Y, 5M, 5C, and 5K reach a position facing the cleaning unit 77, and untransferred toner remaining on the photoconductive drums 5Y, 5M, 5C, and 5K is removed at this position. 77 is mechanically collected by a cleaning blade (cleaning process).
Finally, the surfaces of the photoconductive drums 5Y, 5M, 5C, and 5K reach a position facing a neutralization unit (not shown), and the residual potential on the photoconductive drums 5Y, 5M, 5C, and 5K is removed at this position. The
Thus, a series of image forming processes performed on the photosensitive drums 5Y, 5M, 5C, and 5K is completed.

Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the developing process are transferred onto the intermediate transfer belt 78 in an overlapping manner. In this way, a color image is formed on the intermediate transfer belt 78.
Here, the intermediate transfer unit 85 includes an intermediate transfer belt 78, four primary transfer bias rollers 79Y, 79M, 79C, and 79K, a secondary transfer backup roller 82, a cleaning backup roller 83, a tension roller 84, and an intermediate transfer cleaning unit 80. , Etc. The intermediate transfer belt 78 is stretched and supported by the three rollers 82 to 84 and is endlessly moved in the direction of the arrow in FIG.

The four primary transfer bias rollers 79Y, 79M, 79C, and 79K sandwich the intermediate transfer belt 78 with the photosensitive drums 5Y, 5M, 5C, and 5K, respectively, thereby forming primary transfer nips. Then, a transfer bias reverse to the polarity of the toner is applied to the primary transfer bias rollers 79Y, 79M, 79C, and 79K.
The intermediate transfer belt 78 travels in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 79Y, 79M, 79C, and 79K. In this way, the toner images of the respective colors on the photosensitive drums 5Y, 5M, 5C, and 5K are primarily transferred while being superimposed on the intermediate transfer belt 78.

Thereafter, the intermediate transfer belt 78 onto which the toner images of the respective colors are transferred in an overlapping manner reaches a position facing the secondary transfer roller 89. At this position, the secondary transfer backup roller 82 sandwiches the intermediate transfer belt 78 between the secondary transfer roller 89 and forms a secondary transfer nip. The four color toner images formed on the intermediate transfer belt 78 are transferred onto the recording medium P conveyed to the position of the secondary transfer nip. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 78.
Thereafter, the intermediate transfer belt 78 reaches the position of the intermediate transfer cleaning unit 80. At this position, the untransferred toner on the intermediate transfer belt 78 is collected.
Thus, a series of transfer processes performed on the intermediate transfer belt 78 is completed.

  Here, the recording medium P transported to the position of the secondary transfer nip is transported from the paper feeding unit 12 disposed below the apparatus main body 1 via the paper feeding roller 97 and the registration roller pair 98. It is a thing. Specifically, a plurality of recording media P such as transfer paper are stored in the paper supply unit 12 in an overlapping manner. When the paper feed roller 97 is rotationally driven in the counterclockwise direction in FIG. 1, the uppermost recording medium P is fed between the rollers of the registration roller pair 98.

  The recording medium P conveyed to the registration roller pair 98 is temporarily stopped at the position of the roller nip of the registration roller pair 98 that has stopped rotating. Then, the registration roller pair 98 is rotationally driven in synchronization with the color image on the intermediate transfer belt 78, and the recording medium P is conveyed toward the secondary transfer nip. In this way, a desired color image is transferred onto the recording medium P.

Thereafter, the recording medium P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the position of the fixing device 20. At this position, the color image transferred on the surface is fixed on the recording medium P by heat and pressure generated by the fixing belt 21 and the pressure roller 31.
Thereafter, the recording medium P is discharged out of the apparatus through a pair of paper discharge rollers 99. The recording medium P discharged out of the apparatus by the discharge roller pair 99 is sequentially stacked on the stack unit 100 as an output image.
Thus, a series of image forming processes in the image forming apparatus is completed.

Next, the fixing device according to the present invention will be described.
FIG. 2 is a sectional view showing a basic configuration (1) of the fixing device according to the present invention. Here, a cross-sectional configuration of the sheet passing portion, which is a region through which the recording medium P passes in the nip portion, is illustrated.
As shown in FIG. 2, the fixing device 20 includes a fixing belt 21 as a fixing member, a heating member 22, a reinforcing member (also referred to as a backing member) 23, a contact member 26 that forms a nip portion, and a heater 25 as a heat source. And a temperature sensor (not shown) for controlling the heater 25 by detecting the temperature of the reflecting member 24, the pressure roller 31 as a pressure member, and the fixing belt 21.

  Here, the fixing belt 21 as a fixing member is a thin and flexible endless belt, and rotates (runs) in an arrow direction (counterclockwise) in FIG. The fixing belt 21 is formed by sequentially laminating an elastic layer and a release layer on a base material, and the entire thickness thereof is set to 1 mm or less.

The base material of the fixing belt 21 has a layer thickness of 30 to 100 μm, and is formed of a metal material such as nickel or stainless steel or a resin material such as polyimide.
Further, the elastic layer of the fixing belt 21 has a layer thickness of 100 to 300 μm and is formed of a rubber material such as silicone rubber, foamable silicone rubber, or fluorine rubber. By providing the elastic layer, minute irregularities on the surface of the fixing belt 21 in the nip portion are not formed, and heat is uniformly transmitted to the toner image T on the recording medium P, thereby suppressing the generation of a scum skin image.
The release layer of the fixing belt 21 has a layer thickness of 10 to 50 μm, and includes PFA (tetrafluoroethylene bar fluoroalkyl vinyl ether copolymer resin), PTFE (tetrafluoroethylene resin), polyimide, polyetherimide, It is made of a material such as PES (polyether sulfide). By providing the release layer, the releasability (peelability) for the toner (toner image) is ensured.

Further, the diameter of the fixing belt 21 is set to be 15 to 120 mm. In the present embodiment, the diameter of the fixing belt 21 is set to 30 mm, for example.
Inside the fixing belt 21 (inner peripheral surface side), a heater 25 (heat source), a reflecting member 24, a heating member 22, a reinforcing member 23, a contact member 26, and the like are fixed. As a result, the fixing belt 21 is pressed by the contact member 26 reinforced by the reinforcing member 23 to form a nip portion with the pressure roller 31.

  The heating member 22 is a substantially pipe-shaped member formed by bending a thin metal plate, for example, and is formed in a substantially circular shape so as to face the inner peripheral surface of the fixing belt 21 at a position excluding the nip portion. ing. In addition, you may form a recessed part so that the contact member 26 may be accommodated and hold | maintained in the position of a nip part. Further, both ends of the heating member 22 in the width direction (axial direction) are fixedly supported on the side plate of the fixing device 20.

  The reinforcing member 23 is a member that reinforces the strength of the contact member 26 in the nip portion, and is formed so that the length in the width direction (axial direction) is equal to the length in the longitudinal direction of the contact member 26. The both ends in the width direction are fixedly supported on the side plate of the fixing device 20 on the inner peripheral side of the fixing belt 21.

  The heater 25 is a halogen heater, and both ends thereof are fixed to the side plate of the fixing device 20. The reflecting member 24 is disposed between the reinforcing member 23 and the heater 25 so as to cover the surface of the reinforcing member 23 with respect to the heater 25 while being supported by the reinforcing member 23 (details will be described later).

  Here, the heater 25 emits light by being output-controlled by the power supply unit of the apparatus main body. Among the radiant heat, the radiant heat directed downward in the figure reaches the inner peripheral surface of the heating member 22 directly, and the radiant heat directed upward in the figure. Is also reflected toward the heating member 22 by the reflecting member 24, and the heating member 22 is efficiently heated. Further, the fixing belt 21 is entirely heated by the heating member 22, and heat is applied to the toner image on the recording medium introduced into the nip portion from the surface of the heated fixing belt 21. The output control of the heater 25 is performed based on the detection result of the belt surface temperature by a temperature sensor such as a thermistor facing the surface of the fixing belt 21. Further, the temperature of the fixing belt 21 (fixing temperature) can be set to a desired temperature by such output control of the heater 25.

  The heating member 22 is a thin-walled pipe (tubular) member that is fixed so as to face the entire inner peripheral surface of the fixing belt 21, and is heated by the radiant heat of the heater 25 to heat the fixing belt 21 (convey heat). .) As a material of the heating member 22, it is preferable to use a metal thermal conductor (a metal having thermal conductivity) such as aluminum, iron, and stainless steel.

  The contact member 26 is formed in a concave shape so that the surface facing the pressure roller 31 follows the curvature of the pressure roller 31. Thereby, since the recording medium P is sent out from the nip portion so as to follow the curvature of the pressure roller 31, the problem that the recording medium P after the fixing process is not attracted to the fixing belt 21 and separated is suppressed. be able to.

  Further, as a material for forming the contact member 26, a material having a certain degree of rigidity (for example, a highly rigid metal, ceramic, or the like) is used so that the contact member 26 does not bend greatly even if the pressure applied by the pressure roller 31 is applied. .).

  The pressure roller 31 has a diameter of 30 mm and is formed by forming an elastic layer on a hollow cylindrical cored bar. The elastic layer of the pressure roller 31 is made of a material such as foamable silicone rubber, silicone rubber, or fluororubber. A thin release layer made of PFA, PTFE or the like can be provided on the surface layer of the elastic layer.

  Further, both ends of the pressure roller 31 in the width direction are rotatably supported on the side plate of the fixing device 20 via bearings and are movable toward the contact member 26 side. The pressure roller 31 is provided with pressure means (not shown) that presses the roller shafts at both axial ends of the pressure roller 31 toward the contact member 26 side. The pressure roller 31 is pressed against the contact member 26 via the fixing belt 21 to form a desired nip portion between both members.

  Further, the pressure roller 31 is provided with a gear that meshes with a drive gear of a drive mechanism (not shown), and the pressure roller 31 is rotationally driven in an arrow direction (clockwise direction) in FIG. A heat source such as a halogen heater can be provided inside the pressure roller 31.

  When the pressure roller 31 rotates, the fixing belt 21 also rotates due to the reaction force of the frictional force with the pressure roller 31. In order to prevent the fixing belt 21 from slipping, a lubricant such as grease is applied to the inner surface of the fixing belt 21 to reduce the frictional resistance. Further, the frictional resistance may be reduced by coating the inner surface of the fixing belt 21 and the outer peripheral surface of the heating member 22 with a low sliding coating film.

The fixing device 20 configured as described above operates as follows.
First, when the power switch of the apparatus main body is turned on, electric power is supplied to the heater 25, and the pressure roller 31 presses the contact member 26 via the fixing belt 21 by the pressing means in FIG. Rotation drive in the direction of the arrow is started. Thereby, the fixing belt 21 is also driven (rotated) in the direction of the arrow in FIG. 2 by the frictional force with the pressure roller 31.
Thereafter, the recording medium P is fed from the paper supply unit 12, and an unfixed color image is carried (transferred) on the recording medium P at the position of the secondary transfer roller 89. The recording medium P carrying the unfixed image (toner image T) is guided by a guide plate (not shown) and fed into the nip portion of the fixing belt 21 and the pressure roller 31 that are in a pressure contact state.
The recording medium P is heated by the fixing belt 21 heated by the heating member 22 (heater 25, reflecting member 24) and the pressing force of the contact member 26 reinforced by the reinforcing member 23 and the pressure roller 31. The toner image T is fixed on the surface of the toner. Thereafter, the recording medium P is discharged from the nip portion.

  As described above, in the fixing device 20 according to the present embodiment, the fixing belt 21 is heated almost entirely in the circumferential direction by the heating member 22 without locally heating only a part of the fixing belt 21. Therefore, even when the speed of the apparatus is increased, the fixing belt 21 is sufficiently heated and the occurrence of fixing failure can be suppressed. That is, since the fixing belt 21 can be efficiently heated with a relatively simple configuration, the warm-up time and the first print time are shortened, and the size of the apparatus is reduced.

  However, as described above, the heat capacity of the fixing device is reduced, and the light (infrared rays) directed toward the reinforcing member 23 of the heater 25 is reflected to the heating member 22 side by using a reflecting member, thereby shortening the temperature rising time and power consumption. When the reduction was attempted, uneven gloss occurred in the fixed image.

  When the inventors investigated the problem, it was found that the problem was caused by uneven light emission in the axial direction of the heater 25 itself. That is, since the fixing device itself (for example, the fixing belt 21 and the heating member 22) has a low heat capacity, the light emission unevenness in the axial direction of the heater 25 appears as the temperature unevenness in the axial direction of the surface of the fixing belt 21 as it is. As a result, gloss unevenness occurs in the fixed image. Further, it has been clarified that the uneven light emission in the axial direction of the heater 25 itself corresponds to the winding position of the filament in the halogen heater glass tube. More specifically, in the portion where the winding density of the filament in the heater 25 is high and the light emission is strong, the temperature of the fixing belt 21 is high at the corresponding position, and in the portion where the winding density of the filament is low and the light emission is weak. The temperature of the fixing belt 21 was low at the corresponding position. The reflecting member used here has a flat reflecting surface in the axial direction, and reflects incident light as it is to the heating member 22 side without changing the luminous intensity distribution in the axial direction. It was.

  Accordingly, the inventors cancel the light emission unevenness in the axial direction of the heater 25 and reduce the light (infrared rays) to the heating member 22 in order to reduce (eliminate) the temperature unevenness in the axial direction of the fixing belt 21 based on these findings. ) In the axial direction as much as possible to irradiate as uniformly as possible, and earnestly studied, and improved the reflecting member to achieve the present invention. Hereinafter, the configuration of the main part of the present invention will be described.

[Structure of reflecting member]
In the fixing device 20, the reflecting surface of the reflecting member 24 has a concave portion and / or a convex portion corresponding to the density state of the filament winding density in the axial direction of the heater 25. .
Accordingly, the concave portion on the reflecting surface of the reflecting member 24 collects light from the region where the filament winding density of the heater 25 is coarse on the inner peripheral surface of the heating member 22, or the convex portion on the reflecting surface is the filament winding of the heater 25. Since the light from the dense region is scattered, the influence of the uneven emission of the light in the axial direction of the heater 25 on the fixing belt 21 can be reduced, and the uneven temperature in the axial direction of the fixing belt 21 is suppressed to suppress the fixing image. It becomes possible to prevent uneven gloss.

Hereinafter, specific examples of the reflecting member 24 and the like will be described with reference to the drawings.
Note that the axial direction herein refers to the width direction of the fixing belt 21, the pipe longitudinal direction of the heating member 22, the tube axis direction of the heater 25, and the roller axis direction of the pressure roller 31 in the fixing device 20. This is all in parallel with each other.

(First embodiment)
FIG. 3 is a schematic diagram showing a configuration example (1) of the reflecting member 24 used in the fixing device of the present invention. Here, the left-right direction in the drawing is the axial direction, and the sectional shape in the axial direction of the reflecting member 24 is shown together with the heater 25 and the reinforcing member 23.

  As shown in FIG. 3, in the heater 25, a plurality of coiled filaments 25f are arranged along the tube axis direction of the bulb 25g in a straight tubular bulb 25g made of quartz glass sealed at both ends. . The coiled filament 25f is made of, for example, tungsten, and is arranged in a straight line so as to be supported by a supporter member (not shown) in the tube of the valve 25g. A halogen gas is sealed in the bulb 25g.

  In the heater 25, when electric power is supplied to lead wires (not shown) drawn at both ends thereof, a region where a plurality of coiled filaments 25f are connected in series becomes a light emitting region. At this time, in this light emitting region, the coil portion 25a of the filament 25f is a dense region as a winding density, and the light emitting intensity distribution in the axial direction of the heater 25 is a portion where light emission is strong. Further, the connecting portion 25b of the filament 25f is a region having a coarse winding density, and the light emission intensity distribution in the axial direction of the heater 25 is a portion where light emission is weak.

  The reflecting member 24 is a plate member having a reflecting surface 24r disposed to face the heater 25, and is fixed to the reinforcing member 23 between the reinforcing member 23 and the heater 25 with respect to the heater 25 of the reinforcing member 23. It is arranged so as to cover the surface. By making the reflecting member 24 into a plate shape, the heat capacity of the reflecting member 24 itself can be reduced, and the fixing device 20 can shorten the temperature rise time and power consumption.

  The plate thickness of the reflecting member 24 may be appropriately determined from the balance between the rigidity of the reflecting member 24 and the heat capacity (influence on power consumption). In addition, the target member to which the reflecting member 24 is fixed can be any member other than the reinforcing member 23 as long as the target member can be disposed at an appropriate position between the reinforcing member 23 and the heater 25. It is good to fix with.

  Moreover, it is preferable that the region portion of the reflection surface 24 r in the axial direction of the reflection member 24 is in a suspended state that is not in contact with another member, for example, the reinforcing member 23. Specifically, as shown in FIG. 3, the reflecting member 24 is supported at the end of the reinforcing member 23 by bending both end portions outside the region of the reflecting surface 24r in the axial direction to the reinforcing member 23 side. The region portion of the reflection surface 24r between the both end portions, particularly the concave portion 24b is suspended so that it does not come into contact with the reinforcing member 23. Thereby, useless heat conduction from the reflecting member 24 to the reinforcing member 23 can be prevented, and the fixing device 20 can further shorten the temperature raising time and reduce the power consumption.

The reflecting surface 24r of the reflecting member 24 is a surface that efficiently reflects light (infrared rays) emitted from the heater 25. For example, the reflecting surface 24r is preferably formed by vapor-depositing Ag on the Al surface. Specifically, it is preferable that the reflecting member 24 is made of an Al substrate, and the surface facing the heater 25 is a mirror surface, and then Ag is evaporated to form the reflecting surface 24r.
Note that the configuration of the reflecting surface 24r of the reflecting member 24 is not limited to the material and the layer configuration, and the material and the layer configuration are not limited as long as it has a function of reflecting the light (infrared rays) of the heater 25. .

  Here, the reflection surface 24r of the reflection member 24 is formed with a recess and / or a protrusion corresponding to the density state of the winding density of the filament 25f in the axial direction of the heater 25. That is, the convex portion 24a of the reflecting surface 24r is formed corresponding to a region where the winding density of the filament 25f is dense, that is, the coil portion 25a, and the concave portion 24b of the reflecting surface 24r has a coarse winding density of the filament 25f. The region is formed corresponding to the connection portion 25b.

  In FIG. 3, as the uneven shape in the axial direction of the reflection surface 24 r, a region where the winding density of the filament 25 f is coarse is provided at a position facing the dense area (coil portion 25 a) of the filament 25 f. At the position facing the (connecting portion 25b), the concave portion 24b is provided, and the convex portion 24a and the concave portion 24b are alternately connected in the axial direction.

  Further, the surface of the reflecting surface 24r in the direction orthogonal to the axial direction (the left-right direction in FIG. 2) need not be provided with irregularities. 2, the dotted line shown above and below the reflecting member 24 is such that the lower dotted line is the lower limit position (downward protruding position) of the convex part 24a, and the upper dotted line is the upper limit position (upward protruding position) of the concave part 24b. Is shown. Therefore, the entire reflecting surface 24r has a corrugated shape having a length direction in a direction orthogonal to the axial direction (left-right direction in FIG. 2), for example.

  As a result, the convex portion 24a on the reflecting surface 24r of the reflecting member 24 reflects the light (infrared light) having a high emission intensity from the heater 25 at the opposing position to the heating member 22 side while dispersing in the axial direction, and the concave portion 24b Since light (infrared light) having low emission intensity from the heater 25 at the facing position is reflected in the axial direction while being condensed in the axial direction, the light irradiation amount to the heating member 22 is made constant in the axial direction. The temperature unevenness can be uniformly suppressed, and the surface temperature of the fixing belt 21 can be made constant by eliminating the temperature unevenness in the axial direction.

(Second Embodiment)
FIG. 4 is a schematic diagram showing a configuration example (2) of the reflecting member 24 used in the fixing device of the present invention. Here, the horizontal direction in the figure is the axial direction, and the sectional shape in the axial direction of the reflecting member 24 is shown together with the heater 25 and the reinforcing member 23.
In the present embodiment, the shape of both ends in the axial direction of the reflecting member 24 is different from that of the first embodiment, and the other configurations are the same as those of the first embodiment.

  That is, as shown in FIG. 4, the reflecting surface 24 r of the reflecting member 24 has an inclination in which the reflecting surface 24 r gradually approaches the heater 25 as it goes toward the end in each of the axially opposite end regions. Specifically, as in the first embodiment, the surface of the reflection surface 24r has a shape in which the convex portions 24a and the concave portions 24b are alternately connected in a straight line in the axial direction paper passing region. In the region, the surface shape is an arc shape, and an inclined surface 24c is provided so as to approach the heater 25 toward the end.

  As a result, in the sheet passing area, as in the first embodiment, the convex portion 24a on the reflecting surface 24r of the reflecting member 24 is heated while dispersing light (infrared light) having a high emission intensity from the heater 25 at the opposite position. Since the light is reflected to the member 22 side, and the concave portion 24b is reflected toward the heating member 22 while condensing light (infrared light) having a low light emission intensity from the heater 25 at the opposite position, the light irradiation to the heating member 22 is performed. The amount can be equalized to a constant amount in the axial direction to suppress temperature unevenness. In addition to this, in the region outside the paper passing region, the inclined surface 24c reflects the light (infrared rays) of the heater 25 that leaks outward from the end portion to the inner side (paper passing region side), so the heating member 22 The temperature drop at the end in the axial direction can be prevented, and a uniform temperature distribution can be obtained over the entire width of the fixing belt 21.

Examples of the present invention will be described below.
Example 1
The fixing device 20 shown in FIG. 2 and the reflecting member 24 shown in FIG. 3 were set as follows.
Fixing belt 21: An elastic layer made of silicone rubber having a thickness of 100 μm is applied and formed on a Ni base of an endless belt having a thickness of 30 μm, a diameter of 30 mm, and an axial length of 270 mm, and further a thickness of 50 μm is formed thereon. A release layer made of PFA was applied and formed.
Heating member 22: A stainless steel plate having a thickness of 20 μm formed into a cylindrical shape having a diameter of 30 mm and an axial length of 270 mm was used.
Reinforcing member 23: A plate-shaped stainless steel plate having a thickness of 6 mm and an axial length of 270 mm was used.
Reflective member 24: The structure shown in FIG. 3 was used as a reflective surface 24r by vapor-depositing Ag on a plate-like Al substrate having a thickness of 0.5 mm and an axial length of 273 mm. The surface shape of the reflecting surface 24r was formed such that a convex portion 24a having a top height of 0.2 mm and a concave portion 24b having a bottom surface depth of 0.1 mm with respect to the center target position in the thickness direction of the reflecting surface 24r. . In addition, the top axial center of the convex portion 24a is located in the axial central portion of the coil portion 25a of the filament 25f in the heater 25, and the bottom axial direction center of the concave portion 24b is located in the axial central portion of the connecting portion 25b of the filament 25f. The boundary part between the coil part 25a and the connection part 25b of the filament 25f is formed to be the boundary part between the convex part 24a and the concave part 24b.
Heater 25: A halogen heater in which the light emission intensity of the coil portion 25a of the filament 25f has a difference of about 1.2 times the light emission intensity of the connection portion 25b was used.
A contact member 26; a member made of Al was used.
Pressure roller 31: An elastic layer made of silicone rubber with a thickness of 2.5 mm was formed on a core metal with a diameter of 25 mm, and a total of 30 mm in diameter and 260 mm in axial length was used.

  When the fixing process is performed using the fixing device 20 having the above configuration, no uneven gloss is observed in the fixed image, and the shape of the reflecting surface 24r of the reflecting member 24 is used to suppress the temperature unevenness in the axial direction of the fixing belt 21. It was confirmed that the shape is optimal.

  The arrangement position and axial length (width) of the convex portion 24a on the reflection surface 24r of the reflection member 24 and the arrangement position and axial length (width) of the concave portion 24b are the same as those of the fixing device 20 as a target. Since the optimum conditions differ depending on the difference in winding density between the coil portion 25a and the connection portion 25b of the filament 25f of the heater 25, it is desirable to set appropriately.

(Example 2)
In Example 1, the reflecting member 24 shown in FIG. 4 was used, and other conditions were set under the conditions of Example 1.
Reflective member 24: The distance from the center in the thickness direction (the center of the unevenness) to the surface of the bulb 25g of the heater 25 is 1.2 mm at the center and end of the paper passing area in FIG. 4, and at the end of the light emitting area. The shape of the inclined surface 24c in the reflecting surface 24r and the arrangement of the reflecting member 24 were set so that the thickness was 0.9 mm and 0.5 mm at the end of the reflecting member installation region. The other conditions are the same as in Example 1.
Heater 25: A halogen heater having a light emitting region length of 250 mm was used.

  When the fixing process is performed using the fixing device 20 having the above-described configuration, no gloss unevenness is observed in the fixed image, and the temperature unevenness in the axial direction of the fixing belt 21 is further increased as the shape of the reflecting surface 24r of the reflecting member 24. It was confirmed that it was the optimum shape that could be suppressed.

  Note that the shape and arrangement of the reflecting member 24 shown here are merely examples, and the distance between the heater 25 and the reflecting member 24 in the axial direction depends on the configuration of the fixing device 20, the light emission intensity at the end of the heater 25, the sheet passing area, and the light emission. It is desirable to set appropriately depending on the width of the region.

  Although the present invention has been described with the embodiments shown in the drawings, the present invention is not limited to the embodiments shown in the drawings, and those skilled in the art have conceived other embodiments, additions, modifications, deletions, and the like. It can be changed within the range that can be performed, and any embodiment is included in the scope of the present invention as long as the operation and effect of the present invention are exhibited.

For example, the basic configuration of the fixing device 20 may be the configuration shown in FIG. Here, in the configuration shown in FIG. 2, the contact member 26 is omitted, and the heating member 22 is in contact with the pressure roller 31 via the fixing belt 21 in the nip portion. At this time, the heating member 22 has a substantially circular cross section and is formed so that the position corresponding to the nip portion is a flat surface. Further, the reinforcing member 23 is configured to support the heating member 22 at the nip portion position from the back side, and a heat insulating member 27 is provided between the reinforcing member 23 and the heating member 22 so as not to reduce the heating efficiency. Yes. The other configuration is the same as that shown in FIG.
Further, the pressure member may be configured as a pressure belt type instead of the heating roller 31.

  Further, the heater 25 has been described on the assumption that the heater 25 is composed of one halogen heater, but two heaters, a center heater and an end heater, for heating the axially central portion and the end portion of the fixing belt 21, respectively. The present invention can also be applied to a configuration comprising the halogen heater. That is, when two halogen heaters of the center heater and the end heater are mounted as the heater 25, the reflection surface 24r of the reflection member 24 is uneven at a position corresponding to the winding density of the filament 25f in each halogen heater. In addition to providing, it is desirable to appropriately adjust the surface shape of the reflecting surface 24r in the positional relationship between the central heater and the end heater. For example, at the boundary portion between the central heater and the end heater, the emission intensity becomes strong at the boundary position, and the temperature of the fixing belt 21 tends to increase locally. It is desirable to form a convex portion 24a at the position to disperse light emission and suppress a local temperature rise. Further, as the heater 25, a reflective film is provided on the outer peripheral surface (or inner peripheral surface) of the tube 25g that is the inner peripheral surface side of the fixing belt 21, and all the emitted light (infrared rays) is irradiated to the reflecting member 24 side. You may be made to do.

1. Image forming device (device main body)
3 Exposure unit 4Y, 4M, 4C, 4K Image forming unit 5Y, 5M, 5C, 5K Photosensitive drum 12 Paper feed unit 20 Fixing device 21 Fixing belt (fixing member)
22 Heating member 23 Reinforcing member 24 Reflective member 24a Convex part 24b Concave part 24c Inclined surface 24r Reflective surface 25 Heater (heat source)
25a Coil part 25b Connection part 25f Filament 25g Valve 26 Contact member 27 Heat insulation member 31 Pressure roller (pressure member)
32 Core Bar 33 Elastic Layer 75 Charging Unit 76 Developing Device 77 Cleaning Unit 78 Intermediate Transfer Belt 79Y, 79M, 79C, 79K Primary Transfer Bias Roller 80 Intermediate Transfer Cleaning Unit 82 Secondary Transfer Backup Roller 83 Cleaning Backup Roller 84 Tension Roller 85 Intermediate transfer unit 89 Secondary transfer roller 97 Paper feed roller 98 Registration roller pair 99 Paper discharge roller pair 100 Stack unit 101 Bottle storage unit 102Y, 102M, 102C, 102K Toner bottle P Recording medium T Toner (toner image)

JP 2009-003410 A JP 2009-115969 A JP 2010-113200 A

Claims (10)

A fixing member for a rotating endless belt;
A pressure member that presses against the outer peripheral surface of the fixing member to form a nip portion;
A heating member fixed inside the fixing member and having a pipe member whose outer peripheral surface is in sliding contact with the inner peripheral surface of the fixing member;
A halogen heater fixed inside the heating member for heating the heating member;
A reflecting member fixed inside the heating member so as to face the halogen heater, and having a reflecting surface that reflects light emitted from the halogen heater to an inner peripheral surface of the heating member;
With
The fixing device according to claim 1, wherein the reflecting surface of the reflecting member has a concave portion and / or a convex portion corresponding to a density state of a winding density of the filament in the axial direction of the halogen heater.   The halogen heater has a light emitting region in which a plurality of coiled filaments are connected in series, and the coil portion of the filament is a region with a high winding density in the light emitting region, and the connecting portion of the filament is The fixing device according to claim 1, wherein the winding density is a rough region.   The fixing device according to claim 1, wherein the concave portion of the reflecting surface is formed to correspond to a region where the winding density of the filament is rough.   The fixing device according to claim 1, wherein the convex portion of the reflecting surface is formed corresponding to a region where the winding density of the filament is dense.   The fixing device according to claim 1, wherein the reflection member is a plate member having the reflection surface.   The fixing device according to claim 1, wherein an area portion of the reflection surface in the axial direction of the reflection member is in a suspended state that is not in contact with another member.   The fixing device according to claim 1, wherein the reflecting member is supported at both end portions outside the region of the reflecting surface in the axial direction.   The fixing device according to claim 1, wherein the reflecting surface of the reflecting member is formed by vapor-depositing Ag on an Al surface.   The reflection surface of the reflection member has an inclination in which the reflection surface gradually approaches the halogen heater as it goes toward the end portion in each of the axially opposite end regions. The fixing device according to 1.   An image forming apparatus comprising the fixing device according to claim 1.

Images