JP2001201969A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of preventing a fixing roller member from being damaged by metal fatigue, making the fixing roller member thin in thickness, small in diameter, large in nip width, reduced in energy consumption, and capable of shortening the warming-up time, suppressing the deforming amount of the fixing roller member and preventing an irregular fixing caused by irregular rotation. SOLUTION: The fixing roller member is made a thin cylindrical elastic body, and both ends of the fixing roller member are held by a holding member having an inside diameter larger than the outside diameter of the fixing roller member, and the deforming amount of the fixing roller member to a fixed load is made smaller than that of the pressurizing roller member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used for an image forming apparatus such as a copying machine, a printer, a facsimile, etc., and more particularly to a fixing device capable of saving energy and shortening a warm-up time.

[0002]

2. Description of the Related Art Conventionally, as a fixing device used in an image forming apparatus such as a copying machine, a printer, a facsimile, etc., a fixing roller member (fixing roller) having a heating means inside as a stable device having high technical perfection has been proposed. The heat roller fixing method used is widely used from low-speed machines to high-speed machines and from monochrome machines to full-color machines.

[0003]

However, in a conventional heat roller fixing type fixing device, it is necessary to heat a fixing roller member (fixing roller) having a large heat capacity when heating a transfer material or toner. Inefficient,
It is disadvantageous in terms of energy saving, and there is a problem that it takes time to warm up the fixing device at the time of printing and the printing time (warming-up time) becomes longer.

In order to solve this problem and make the fixing roller member having a short warm-up time with energy saving, it is necessary to reduce the thickness and diameter of the fixing roller member. There is a problem that the fixing roller member is damaged (damage) due to metal fatigue due to the deformation, and if the diameter is reduced, the nip width (width of the nip portion) is insufficient, resulting in poor fixing. Also, when the thickness is reduced, uneven rotation due to deformation of the fixing roller member causes
The problem of uneven fixing occurs.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, reduces the thickness of the fixing roller member without damaging the fixing roller member due to metal fatigue, reduces the diameter of the fixing roller member, increases the nip width, saves energy, and increases the warm-up time. It is an object of the present invention to provide a fixing device that reduces the amount of deformation of the fixing roller member and prevents the fixing unevenness due to the rotation unevenness.

[0006]

An object of the present invention is to provide a fixing roller member having a heating means and a pressure roller member having elasticity opposed to the fixing roller member to fix a toner image on a transfer material. In the fixing device, the fixing roller member is a thin cylindrical elastic body, and both ends of the fixing roller member are held by holding members having an inner diameter larger than an outer diameter of the fixing roller member. This is achieved by a fixing device (first invention), wherein the amount of deformation of the fixing roller member with respect to the load is smaller than the amount of deformation of the pressure roller member.

The above object is also achieved by a fixing device for fixing a toner image on a transfer material, comprising a fixing roller member having a heating means, and an elastic pressure roller member opposed to the fixing roller member. The fixing roller member is a thin cylindrical elastic body, and both ends of the fixing roller member are held by holding members having an inner diameter larger than the outer diameter of the fixing roller member. This is achieved by a fixing device (second invention), wherein the outer diameter is smaller than the outer diameter of the pressure roller member.

The above object is also achieved by a fixing device for fixing a toner image on a transfer material, comprising a fixing roller member having a heating means, and an elastic pressure roller member opposed to the fixing roller member. The fixing roller member is a thin cylindrical elastic body, and both ends of the fixing roller member are held by holding members having an inner diameter larger than an outer diameter of the fixing roller member. Where L2 / L1 = 0.90 to 0.99, where L2 (mm) is the width of the fixing roller member and L1 (mm) is the width between the holding member center positions of the fixing member. This is achieved by a fixing device (third invention).

The above object is also achieved by a fixing device for fixing a toner image on a transfer material, comprising a fixing roller member having a heating means, and an elastic pressure roller member opposed to the fixing roller member. The fixing roller member is a thin cylindrical elastic body, and both ends of the fixing roller member are held by holding members having an inner diameter larger than the outer diameter of the fixing roller member. When the width is L (mm) and the width between the center positions of the holding portions of the fixing roller member by the holding member is L1 (mm),
L1 / L = 0.70 to 0.95 is achieved by a fixing device (fourth invention).

[0010]

Embodiments of the present invention will be described below. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Further, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning or technical scope of the terms of the present invention.

An image forming process and each mechanism of an embodiment of an image forming apparatus using a fixing device according to the present invention will be described with reference to FIGS. FIG.
1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of an image forming apparatus using a fixing device according to the present invention,
FIG. 2 is a side sectional view of the image forming body of FIG. 1, FIG. 3 is a schematic sectional view of a fixing device according to the present invention, and FIG.
FIG. 5 is a schematic side view illustrating an example of a holding method of the fixing device in FIG. 3, FIG. 5 is a diagram illustrating a layer configuration and a function of a fixing roller member, and FIG. FIG. 7 is a diagram showing deformation amounts of the fixing roller member and the pressure roller member, and FIG. 8 is a diagram showing deformation amounts of the fixing roller member and the pressure roller member. FIG.
FIG. 10 is a diagram illustrating an arrangement of a fixing roller member and a pressing roller member, and a dimensional relationship between a width between holding center positions of the fixing roller member and a pressing roller member width or a fixing roller member width. FIG. 5 is a diagram showing a problem when pressing a fixing roller member using a cylindrical elastic body.

According to FIG. 1 or FIG. 2, a photosensitive drum 10, which is an image forming body, is provided on the outer periphery of a cylindrical base formed of a light-transmitting member such as glass or light-transmitting acrylic resin. It is formed by forming a photoconductive layer and a photoconductor layer of an organic photosensitive layer (OPC).

The photosensitive drum 10 is rotated clockwise as indicated by an arrow in FIG. 1 with the light-transmitting conductive layer grounded by power from a drive source (not shown).

In the present invention, the exposure beam for image exposure is
The photoconductor layer of the photoconductor drum 10, which is the image forming point, only needs to have an exposure light amount of a wavelength that can provide an appropriate contrast with respect to the light attenuation characteristic (photocarrier generation) of the photoconductor layer. . Therefore, the light transmittance of the light-transmitting substrate of the photosensitive drum in the present embodiment does not need to be 100%, and may have a characteristic of absorbing a certain amount of light when transmitting the exposure beam. . The point is that any suitable contrast can be provided. As a material of the light-transmitting substrate, an acrylic resin, particularly one obtained by polymerizing a methyl methacrylate monomer, is preferably used because of its excellent light-transmitting properties, strength, accuracy, surface properties, etc. Various translucent resins such as acryl, fluorine, polyester, polycarbonate, polyethylene terephthalate and the like used for the above can be used. Further, as long as it has a light-transmitting property with respect to the exposure light, it may be colored. As the light-transmitting conductive layer, indium tin oxide (I
TO), tin oxide, lead oxide, indium oxide, copper iodide, or a metal thin film of Au, Ag, Ni, Al, or the like that maintains light transmissivity. Reactive deposition method, various sputtering methods, various CV
D method, dip coating method, spray coating method and the like can be used.
Various organic photosensitive layers (OPC) can be used as the photoconductor layer.

The organic photosensitive layer serving as the photosensitive layer of the photoconductor layer includes a charge generation layer (CGL) mainly composed of a charge generation substance (CGM) and a charge transport layer (CTM) mainly composed of a charge transport substance (CTM). And CTL). An organic photosensitive layer having a two-layer structure has high durability as an organic photosensitive layer due to its thick CTL and is suitable for the present invention.
The organic photosensitive layer may have a single layer structure containing a charge generation material (CGM) and a charge transport material (CTM) in one layer. ,
Usually, a binder resin is contained.

A scorotron charger 11 as a charging means described below, and an exposure optical system 1 as an image writing means will be described.
2. The developing device 13 as a developing unit is prepared for an image forming process for each color of yellow (Y), magenta (M), cyan (C) and black (K), respectively. Are arranged in the order of Y, M, C, and K with respect to the rotation direction of the photosensitive drum 10 indicated by the arrow in FIG.

Scorotron charger 11 as charging means
Is mounted so as to face and be close to the photosensitive drum 10 in a direction perpendicular to the moving direction of the photosensitive drum 10 as an image forming body (the direction perpendicular to the plane of FIG. 1). A control grid (no symbol) maintained at a predetermined potential with respect to the body layer;
As a, for example, a sawtooth electrode is used, and a charging action (in this embodiment, negative charging) is performed by corona discharge having the same polarity as that of the toner, thereby giving a uniform potential to the photosensitive drum 10. As the corona discharge electrode 11a, a wire electrode or a needle electrode may be used.

The exposure optical system 12 for each color is a linear exposure element (LED) in which a plurality of LEDs (light emitting diodes) as light emitting elements of image exposure light are arranged in an array parallel to the axis of the photosensitive drum 10. (Not shown) and a selfoc lens (not shown) as an equal-magnification imaging element are configured as an exposure unit attached to a holder. An exposure optical system 1 for each color is placed on a cylindrical holder 20 as an exposure optical system holding member.
2 is mounted and housed inside the substrate of the photosensitive drum 10. Other exposure elements include FL (phosphor emission),
A linear element in which a plurality of light emitting elements such as EL (electroluminescence) and PL (plasma discharge) are arranged in an array is used.

An exposure optical system 12 as an image writing means for each color sets an exposure position on the photosensitive drum 10 between the scorotron charger 11 and the developing unit 13 and the photosensitive unit with respect to the developing unit 13. It is arranged inside the photoconductor drum 10 in a state provided on the upstream side in the rotation direction of the drum 10.

The exposure optical system 12 performs image processing based on image data of each color sent from a separate computer (not shown) and stored in a memory, and then forms an image on a uniformly charged photosensitive drum 10. Exposure is performed to form a latent image on the photosensitive drum 10. The emission wavelength of the light-emitting element used in this embodiment is usually 6 for the toners of Y, M, and C, which have high translucency.
The wavelength in the range of 80 to 900 nm is good, but the wavelength may be shorter than this, since the color toner does not have sufficient translucency since image exposure is performed from the back surface.

The developing device 13 as a developing means for each color includes
Inside yellow (Y), magenta (M), cyan (C)
Alternatively, it contains a black (K) two-component (or one-component) developer and is formed of, for example, a cylindrical non-magnetic stainless steel or aluminum material having a thickness of 0.5 to 1 mm and an outer diameter of 15 to 25 mm, respectively. And a developing sleeve 13a as a developer carrier.

In the developing area, the developing sleeve 13a is kept out of contact with the photosensitive drum 10 with a predetermined gap, for example, 100 to 1000 μm, by abutting rollers (not shown). At the closest position, it rotates in the forward direction, and at the time of development, an AC voltage AC is superimposed on a DC voltage of the same polarity as the toner (in the present embodiment, a negative polarity) or a DC voltage with respect to the developing sleeve 13a. By applying the developing bias voltage, non-contact reversal development is performed on the exposed portion of the photosensitive drum 10. At this time, the precision of the development interval needs to be about 20 μm or less in order to prevent image unevenness.

As described above, the developing device 13 transfers the electrostatic latent image on the photosensitive drum 10 formed by the charging by the scorotron charger 11 and the image exposure by the exposure optical system 12 in a non-contact state. Reversal development is performed with toner having the same polarity as the charge polarity of No. 10 (in the present embodiment, the photosensitive drum is negatively charged, and the toner has a negative polarity).

As shown in FIG. 2, the photosensitive drum 10 and a holder 20 as an exposure optical system holding member rotatably support the photosensitive drum 10 at the rear and front ends of the apparatus. Drum flanges 10A and 10B as photoconductor drum support members, and optical system flanges 120A and 1 as exposure optical system support members that support holder 20
20B is integrally formed through press-fitting or means such as screws. The photoreceptor drum 10 includes a drum flange 10A and a drum flange 10B serving as a photoreceptor drum support member and an optical system flange 120A of the holder 20.
Shaft 121 and optical system flange 1 integrated with each other
20B is rotatably supported via bearings B1 and B2, respectively.

The shaft 121 has a shaft portion 121A for holding the photosensitive drum 10, and a support shaft 130 as shaft holding means having an engagement hole 130A is provided on the back side device substrate 70. The linear bearing B4 is fitted into the engagement hole 130A, and the receiving member 13
The support shaft 130 is fixed to the device substrate 70 on the rear side by screws or the like with the Oa interposed therebetween. The support shaft 130 is located at the center of the gear G2 that meshes with the drive gear G1, and rotatably supports a conductive member 131 that integrates the gear G2 via a bearing B3. On the other hand, the apparatus substrate 70 on the front side of the apparatus has an opening 70A through which the photosensitive drum 10 having the exposure optical system 12 fixed to the holder 20 can be inserted and removed.

The holder 20 inserts the shaft portion 121A of the shaft 121 into the linear bearing B4 provided on the support shaft 130 with respect to the device board 70 on the back side, and the shaft portion 121A
The engaging pin 121P inserted into the
The exposure optical system 12 is attached by regulating the angular relation position of the exposure optical system 12 by engaging with a V-shaped groove formed on the front side of the exposure optical system 12. With the optical system flange 120C as a support member sandwiching the cushioning material K and pressing the front lid 120D in the axial direction, the screw 5
2 to be mounted at a predetermined position.

A coupling 10C attached to a side surface of a drum flange 10A as a photosensitive drum supporting member for supporting the photosensitive drum 10, a drive pin 131A attached to a side surface of a conductive member 131 integrated with a gear G2;
With the set screw 51, the drum flange 10A and the gear G
When the photosensitive drum 10 with the holder 20 is integrated, the drum flange 1
Coupling 10C attached to the side of 0A is gear G2.
After the engagement, the conductive member 131 having the gear G2 and the photosensitive drum 10 having the drum flange 10A are aligned with the center and the outer peripheral surface. , From the side of the photosensitive drum 10 using the set screw 51
1A and the coupling 10C are fixed, and the drum flange 10A and the gear G2 are connected and fixed.

When the image forming body drive motor (not shown) is started by the start of image formation, the rotational power of the drive gear G1 is transmitted to the photosensitive drum 10 via the coupling portion by the gear G2, and the photosensitive drum 10 is moved to the position shown in FIG. , And at the same time, application of a potential to the photosensitive drum 10 is started by the charging action of the Y scorotron charger 11.
After a potential is applied to the photosensitive drum 10, exposure (image writing) by a first color signal, that is, an electrical signal corresponding to Y image data is started in the Y exposure optical system 12, and the rotation of the photosensitive drum 10 is started. By scanning, an electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer on the surface. This latent image is reversely developed in a non-contact state by the Y developing device 13, and a yellow (Y) toner image is formed on the photosensitive drum 10.

Next, the photoreceptor drum 10 places an M scorotron charger 11 on the yellow (Y) toner image.
A potential is applied by the charging action of the M exposure optical system 12
Exposure (image writing) is performed using an electrical signal corresponding to the second color signal of m, i.e., magenta (M) image data.
The magenta (M) toner image is formed on the yellow (Y) toner image by non-contact reversal development by the developing device 13.

By the same process, the cyan (C) toner image corresponding to the third color signal is further processed by the C scorotron charger 11, the exposure optical system 12, and the developing device 13, and the K scorotron charger 11 , Exposure optical system 1
A black (K) toner image corresponding to the fourth color signal is sequentially superimposed and formed by the second and developing units 13, and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10. You.

As described above, in this embodiment, Y, M,
The exposure of the organic photosensitive layer of the photoconductor drum 10 by the C and K exposure optical systems 12 is performed through a transparent substrate from the inside of the photoconductor drum 10. Therefore, the exposure of the image corresponding to the second, third, and fourth color signals can form an electrostatic latent image without being shielded by the previously formed toner image, which is preferable. Photoconductor drum 1
0 may be exposed from outside.

On the other hand, the recording paper P as a transfer material is sent out from a paper feed cassette 15 as a transfer material storage means by a feed roller (no code), and fed by a feed roller (no code) to a timing roller. It is conveyed to 16.

The recording paper P is synchronized with the color toner image carried on the photosensitive drum 10 by the driving of the timing roller 16, and the paper charger 1 as paper charging means is synchronized.
Due to the electrification of 50, the toner is attracted to the conveyor belt 14a and fed to the transfer area. The recording paper P, which is closely transported by the transport belt 14a, is moved around the photosensitive drum 10 by a transfer unit 14c as a transfer unit to which a voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied in a transfer area. The color toner images on the surface are collectively transferred to the recording paper P.

The recording paper P on which the color toner image has been transferred is
The paper is discharged by a paper separation AC neutralizer 14h as a transfer material separating unit, separated from the transport belt 14a, and transported to the fixing device 17.

As will be described in detail later, the fixing device 17 includes a resin bearing 171j as a ring-shaped holding member.
The fixing roller 17a is a thin plate-shaped fixing roller 17a, which is an upper fixing roller member (color toner image side on the recording paper P) for fixing a color toner image, and a lower elastic pressing roller 47a. The fixing roller 17a
Is provided with a halogen heater 171g which is a heating means having a heating filament as a heating source.

The recording paper P is sandwiched by a nip N formed between the fixing roller 17a and the elastic pressure roller 47a, and the color toner image on the recording paper P is fixed by applying heat and pressure. Then, the recording paper P is sent by the paper discharge roller 18 and discharged to a tray on the upper part of the apparatus.

The toner remaining on the peripheral surface of the photosensitive drum 10 after the transfer is transferred to a cleaning blade 19 provided in a cleaning device 19 as an image forming body cleaning means.
Cleaning is performed by a. The photosensitive drum 10 from which the residual toner has been removed is uniformly charged by the scorotron charger 11, and enters the next image forming cycle.

According to FIG. 3 to FIG.
Is a thin cylindrical elastic body on the upper side (on the side of the color toner image on the recording paper P) which is held by a resin bearing 171j as a ring-shaped holding member and has a spring property for fixing the color toner image. A fixing roller 17a as a fixing roller member using a thin plate elastic roller 171a is disposed, and a pressing roller 47a as a pressing roller member having elasticity is disposed below the fixing roller 17a. Inside the heater 17a, there is provided a halogen heater 171g, which is a heating means having a heat-generating filament (no symbol) as a heat source.

As shown in FIG. 5, the fixing roller 17a, which is a thin plate-like fixing roller member on the upper side, is a thin sheet elastic roller 171a which is a thin cylindrical elastic body having a spring property, and an outer side of the thin sheet elastic roller 171a. (Outer peripheral surface) rubber layer 17
1b.

The thickness (thickness) t (mm) of the thin plate elastic roller 171a is 0.07 to 0.7, depending on the diameter.
For example, nickel having a thickness of about 0 mm can be used, but preferably a spring (thin wall) metal member having a spring property using stainless steel, phosphor bronze, or the like is used. The use of the metal member can prevent the occurrence of fatigue failure due to the elastic deformation of the thin plate elastic roller 171a, which is a cylindrical elastic member, when the thin plate elastic roller 171a is applied to the fixing device 17. To prevent the occurrence of fatigue fracture due to elastic deformation,
At Plane Bending Fatigue Test method (JIS, Z2275), by repeating several 10 ⁷ times, it is preferable that a metal member of a thin plate (thin) with 140 N / mm ² or more fatigue strength has been confirmed experimentally Was.

The thickness t of the thin plate elastic roller 171a
(Mm), the outer diameter of the thin plate elastic roller 171a is R
(Mm), the following condition is satisfied: R / 50>t> R / 300.
In this case, the width of the nip portion N can be increased to 5 to 30 mm without deformation or breakage. Outer diameter R of thin plate elastic roller 171a
Is preferably 15 to 40 mm. t ≧ R / 5
In the case of 0, when the thin plate elastic roller 171a is too thick and applied to the fixing device 17, it does not deform into an elliptical shape and the width of the nip portion N does not become wide. There is also a disadvantage that the rate of temperature rise is slow due to a large heat capacity. When t ≦ R / 300, the thickness of the thin plate elastic roller 171a is too thin, and when applied to the fixing device 17, the strength is too low and the pressing force is insufficient, resulting in uneven fixing. Further, the heat capacity is small, which causes a temperature difference during paper passing.

Outside (outer peripheral surface) of the thin plate elastic roller 171a
It is preferable that the rubber layer 171b provided with a thickness of about 0.3 to 1 mm as silicon or fluorine-based rubber. By providing the rubber layer 171b, occurrence of fixing unevenness is reduced. Thereby, it can be used also as a fixing device for color fixing that can give glossiness.

The pressure roller 47a as the lower pressure roller member is, for example, a rod-shaped core metal 47 made of stainless steel.
1a and a rubber roller layer 471b having a rubber hardness of 20Hs to 70Hs (JIS, A rubber hardness), preferably 30Hs to 40Hs, for example, using a silicon material outside the metal core 471a. Is done. The pressure roller 47a is pressed (pressed) against the fixing roller 17a (the fixing roller 17a may be pressed against the pressure roller 47a as described later), and the nip portion N is formed. The rubber hardness is preferably the same for the rubber layer 171b used on the surface of the thin plate elastic roller 171a.

An elastic rubber roller having a high heat insulating property is used for the lower pressing roller 47a, and an upper thin elastic roller 171a is used.
Of the heat to the lower pressure roller 47a, and a wide nip width of 5 to 30 mm is secured.

As shown in FIG. 4, both ends of a fixing roller 17a which is a fixing roller member using a thin plate elastic roller 171a which is a thin cylindrical elastic body having a spring property are provided.
For example, a resin bearing 171j as a ring-shaped holding member using a heat-insulating resin member such as a fluororesin is fitted, and both ends of the fixing roller 17a serve as holding members having an inner diameter larger than the outer diameter of the fixing roller 17a. It is held by a resin bearing 171j. The fixing roller 17a integrated with the resin bearings 171j at both ends is rotatable by bearings B5 as bearing members fitted into the resin bearings 171j as holding members at both ends. At this time, the fixing roller 17a can be directly held by the bearings B5 at both ends. At both ends of the fixing roller 17a, receiving plates PLb made of a resin member having good slipperiness, for example, using a fluorine resin or the like are provided, and the fixing roller 17a is positioned from both ends. Also, the lower pressure roller 47a
A gear G12 is fixedly provided at one end of a metal core 471a of the pressure roller 47a, and a gear G22 driven and rotated by the fixing drive motor M1 is connected to the gear G12, and the fixing drive motor M1 The pressure roller 47 is driven by the
is driven to rotate, and the fixing roller 17a pressed by the pressing roller 47a is driven to rotate. Due to the driven rotation, the rotation of the fixing roller 17a is made uniform, and uneven fixing is prevented.

The rubber layer 171b of the fixing roller 17a, which is indicated by oblique lines in FIG.
It is preferable that the rubber layer 171b is prevented from being scraped by the resin bearing 171j when the fixing roller 17a is rotated.

As described above, the fixing roller member is a thin thin elastic roller 171a having a spring property.
The pressing force of the pressing roller 47a is received by the elastic force of the thin plate elastic roller 171a of the fixing roller 17a (as described later, the fixing roller 17a is pressed against the pressing roller 47a,
The pressing force against the pressing roller 47a may be received by the elastic force of the thin thin elastic roller 171a having the spring property of the fixing roller 17a). As a result, the thin plate elastic roller 171a expands in an elliptical shape without plastic deformation, and presses the soft rubber roller layer 471b of the pressure roller 47a on the surface of the thin plate elastic roller 171a that is almost planar, thereby forming a convex 5 to 5 below. A wide nip N of 30 mm is formed. 5-3
Good fixing of the toner image is performed by the wide nip portion N of 0 mm.

As described above, even if the fixing roller member has a small diameter, the nip width can be made as wide as 5 to 30 mm, so that a fixing device which saves energy and has a short warming-up time can be realized. In order to secure a wide nip portion N of 5 to 30 mm, the curvature of the nip portion N is set such that the pressure roller 4
It is necessary to balance the rubber hardness of the rubber roller layer 471b of 7a, but the radius of curvature of the nip N formed on the pressure roller 47a side by the fixing roller 17a and the pressure roller 47a is set to 50 mm or more. Is preferred. As a result, the occurrence of poor fixing and wrinkling on thick paper, particularly the occurrence of fixing wrinkles on a double transfer material such as an envelope, is reduced. Further, the radius of curvature of the exit portion of the nip portion N is reduced by this deformation, and the separation from the transfer material is improved.

As described above, the thickness of the fixing roller member can be reduced without plastic deformation by the thin cylindrical elastic body, and the fixing roller member can be stably held by the bearing member. A fixing device having a large warming-up time with a large energy saving of up to 30 mm is possible.

The resin bearing 171 described above with reference to FIG.
6, a resin flange 171i is formed as shown in FIG. 6, and the fixing roller 17a is fixed by the resin flanges 171i at both ends.
May be held. Resin flange 171 at both ends
The fixing roller 17a is rotatably held by the bearing B5 fitted into the fixing roller 17a.

According to FIG. 7, as described above with reference to FIG. 3, the fixing device 17 includes a resin bearing 171 as a ring-shaped holding member on the upper side (color toner image side on the recording paper P).
j, a fixing roller member using a thin plate elastic roller 171a (see FIG. 5, not shown in FIG. 7) as a thin cylindrical elastic body having a spring property for fixing a color toner image. The fixing roller 17a includes a fixing roller 17a and a pressing roller 47a as a lower pressing roller member having elasticity. Both ends of the fixing roller 17a are held by a resin bearing 171j as a holding member having an inner diameter larger than the outer diameter of the fixing roller 17a.

As described above with reference to FIG. 5, the fixing roller 17a, which is an upper thin plate-shaped fixing roller member, is a thin plate elastic roller 171a which is a thin cylindrical elastic body having a spring property.
And a rubber layer 171b on the outer side (outer peripheral surface) of the thin plate elastic roller 171a.

The thickness (thickness) t (mm) of the thin plate elastic roller 171a is 0.07 to 0.7, although it depends on the diameter.
For example, nickel having a thickness of about 0 mm can be used, but preferably a spring (thin wall) metal member having a spring property using stainless steel, phosphor bronze, or the like is used. The use of the metal member can prevent the occurrence of fatigue failure due to the elastic deformation of the thin plate elastic roller 171a, which is a cylindrical elastic member, when the thin plate elastic roller 171a is applied to the fixing device 17. To prevent the occurrence of fatigue fracture due to elastic deformation,
At Plane Bending Fatigue Test method (JIS, Z2275), by repeating several 10 ⁷ times, it is preferable that a metal member of a thin plate (thin) with 140 N / mm ² or more fatigue strength has been confirmed experimentally Was.

The thickness t of the thin elastic roller 171a is
(Mm), the outer diameter of the thin plate elastic roller 171a is R
(Mm), the following condition is satisfied: R / 50>t> R / 300.
In this case, the width of the nip portion N can be increased to 5 to 30 mm without deformation or breakage. Outer diameter R of thin plate elastic roller 171a
Is preferably 15 to 40 mm. t ≧ R / 5
In the case of 0, when the thin plate elastic roller 171a is too thick and applied to the fixing device 17, it does not deform into an elliptical shape and the width of the nip portion N does not become wide. There is also a disadvantage that the rate of temperature rise is slow due to a large heat capacity. When t ≦ R / 300, the thickness of the thin plate elastic roller 171a is too thin, and when applied to the fixing device 17, the strength is too low and the pressing force is insufficient, resulting in uneven fixing. Further, the heat capacity is small, which causes a temperature difference during paper passing.

Outside (outer peripheral surface) of the thin plate elastic roller 171a
It is preferable that the rubber layer 171b provided with a thickness of about 0.3 to 1 mm as silicon or fluorine-based rubber. By providing the rubber layer 171b, occurrence of fixing unevenness is reduced. Thereby, it can be used also as a fixing device for color fixing that can give glossiness.

The pressure roller 47a as the lower pressure roller member is, for example, a rod-shaped core metal 47 made of stainless steel.
1a and a rubber roller layer 471b having a rubber hardness of 20Hs to 70Hs (JIS, A rubber hardness), preferably 30Hs to 40Hs, for example, using a silicon material outside the metal core 471a. Is done. The rubber hardness is preferably the same for the rubber layer 171b used on the surface of the thin plate elastic roller 171a.

The pressure roller 47a is pressed (pressed) against the fixing roller 17a (the fixing roller 17a is
a), a nip portion N is formed, but the fixing roller 17a (the thin plate elastic roller 171a of the fixing roller 17a with respect to a fixed load, pressing the fixing roller 17a and the pressure roller 47a) is formed. The deformation amount ΔD1 (mm) of FIG. 5 and not shown in FIG.
It is preferable to set smaller than the deformation amount ΔD2 (mm) of 7a (ΔD1 <ΔD2). That is, the fixing roller 17a
Is harder, suppresses the amount of deformation, prevents uneven fixing caused by uneven rotation due to deformation of the fixing roller 17a, and prevents damage (breakage) due to metal fatigue.
The pressure roller 47a is made of a soft material to increase the width of the nip N and to improve the separation performance of the recording paper P at the exit of the nip N.

The fixing roller 17a (a thin elastic roller 171a of the fixing roller 17a (see FIG. 5; not shown in FIG. 7)) is applied as a fixed load, for example, a load of 50 to 500N.
It has been experimentally confirmed that the deformation amount ΔD1 of the pressure roller 47a is approximately 1 to 5 mm, and the deformation amount ΔD2 of the pressure roller 47a is preferably approximately 3 to 15 mm. The ratio of the deformation amount ΔD2 (mm) of the fixing roller 17a to the deformation amount ΔD1 (mm) of the fixing roller 17a, ΔD
It is preferable to set 2 / ΔD1 as follows: ΔD2 / ΔD1 = 2-5. The value of the ratio ΔD2 / ΔD1 is set to 2 or more so that the pressure roller 47a is too hard, the width of the nip N is too narrow, and the separation performance is not reduced. The thin plate elastic roller 171a of the fixing roller 17a (see FIG. 5,
The value of the ratio ΔD2 / ΔD1 is set to 5 or less so that the fixing roller 17a is not deformed or damaged so that the fixing roller 17a is not deformed or damaged.

In the above description, the pressure roller 47a is
The sponge layer (upper layer) instead of the rubber material described above
It is also possible to use a resin pipe, and the separation performance of the transfer material is slightly reduced. However, it is possible to improve the heat insulating layer and increase the width of the nip portion N.

With the above setting, the thickness of the fixing roller member can be reduced without damaging the cylindrical elastic body of the fixing roller member due to metal fatigue, the nip width is small, the nip width is wide, and the warm-up time is shortened by saving energy. At the same time, the amount of deformation of the cylindrical elastic body of the fixing roller member is suppressed, and a fixing device in which uneven fixing due to uneven rotation is prevented can be realized.

According to FIG. 8, as described above with reference to FIG. 3, the fixing device 17 includes a resin bearing 171 as a ring-shaped holding member on the upper side (on the side of the color toner image on the recording paper P).
j, a fixing roller member using a thin plate elastic roller 171a (see FIG. 5, not shown in FIG. 8) as a thin cylindrical elastic body having a spring property for fixing a color toner image. The fixing roller 17a includes a fixing roller 17a and a pressing roller 47a as a lower pressing roller member having elasticity. Both ends of the fixing roller 17a are held by a resin bearing 171j as a holding member having an inner diameter larger than the outer diameter of the fixing roller 17a.

As described above with reference to FIG. 5, the fixing roller 17a, which is an upper thin fixing roller member, is a thin elastic roller 171a which is a thin cylindrical elastic body having a spring property.
And a rubber layer 171b on the outer side (outer peripheral surface) of the thin plate elastic roller 171a.

The thickness (wall thickness) t (mm) of the thin plate elastic roller 171a is 0.07 to 0.7, depending on the diameter.
For example, nickel having a thickness of about 0 mm can be used, but preferably a spring (thin wall) metal member having a spring property using stainless steel, phosphor bronze, or the like is used. The use of the metal member can prevent the occurrence of fatigue failure due to the elastic deformation of the thin plate elastic roller 171a, which is a cylindrical elastic member, when the thin plate elastic roller 171a is applied to the fixing device 17. To prevent the occurrence of fatigue fracture due to elastic deformation,
At Plane Bending Fatigue Test method (JIS, Z2275), by repeating several 10 ⁷ times, it is preferable that a metal member of a thin plate (thin) with 140 N / mm ² or more fatigue strength has been confirmed experimentally Was.

The thickness t of the thin plate elastic roller 171a
(Mm), the outer diameter of the thin plate elastic roller 171a is R
(Mm), the following condition is satisfied: R / 50>t> R / 300.
In this case, the width of the nip portion N can be increased to 5 to 30 mm without deformation or breakage. Outer diameter R of thin plate elastic roller 171a
Is preferably 15 to 40 mm. t ≧ R / 5
In the case of 0, when the thin plate elastic roller 171a is too thick and applied to the fixing device 17, it does not deform into an elliptical shape and the width of the nip portion N does not become wide. There is also a disadvantage that the rate of temperature rise is slow due to a large heat capacity. When t ≦ R / 300, the thickness of the thin plate elastic roller 171a is too thin, and when applied to the fixing device 17, the strength is too low and the pressing force is insufficient, resulting in uneven fixing. Further, the heat capacity is small, which causes a temperature difference during paper passing.

Outside (outer peripheral surface) of the thin plate elastic roller 171a
It is preferable that the rubber layer 171b provided with a thickness of about 0.3 to 1 mm as silicon or fluorine-based rubber. By providing the rubber layer 171b, occurrence of fixing unevenness is reduced. Thereby, it can be used also as a fixing device for color fixing that can give glossiness.

The pressure roller 47a as the lower pressure roller member is, for example, a rod-shaped core metal 47 made of stainless steel.
1a and a rubber roller layer 471b having a rubber hardness of 20Hs to 70Hs (JIS, A rubber hardness), preferably 30Hs to 40Hs, for example, using a silicon material outside the metal core 471a. Is done. The rubber hardness is preferably the same for the rubber layer 171b used on the surface of the thin plate elastic roller 171a.

The pressing roller 47a is pressed (pressed) against the fixing roller 17a (the fixing roller 17a is
a), a nip portion N is formed, but the outer diameter D1 (mm) of the fixing roller 17a and the outer diameter D1 of the fixing roller 17a are determined by the thin plate elastic roller 1 described above.
71a) is set to be smaller than the outer diameter D2 (mm) of the pressure roller 47a (D1 <D).
2) is preferred. By making the outer diameter D1 of the fixing roller 17a smaller than the outer diameter D2 of the pressing roller 47a, the separation performance of the recording paper P is improved, the heat capacity is reduced, and the temperature rising speed of the fixing roller 17a is increased.

The fixing roller 17a has an outer diameter D1 of 1
Experiments have been carried out using a roller having an outer diameter D2 of about 20 to 50 mm as a pressure roller 47a using a roller having a diameter of about 5 to 40 mm. In order to increase the temperature speed, the ratio of the outer diameter D2 (mm) of the pressure roller 47a to the outer diameter D1 (mm) of the fixing roller 17a, D2 / D1, is D2 / D1 = 1.2 to It was experimentally confirmed that it is preferable to set 2.0.

In addition to the above settings, the fixing roller 17a is made harder to suppress the amount of deformation, to prevent fixing unevenness caused by uneven rotation due to deformation of the fixing roller 17a, and to prevent damage (breakage) due to metal fatigue, The pressure roller 47a uses a soft material to increase the width of the nip portion N and to press the fixing roller 17a and the pressure roller 47a described above with reference to FIG. The deformation amount ΔD1 (mm) of the fixing roller 17a (the thin plate elastic roller 171a of the fixing roller 17a (see FIG. 5, not shown in FIG. 7)) is
a is set to be smaller than the deformation amount ΔD2 (mm) (a
D1 <ΔD2) is preferable (see FIG. 7).

With the above setting, the fixing roller member is reduced in diameter, the heat capacity of the fixing roller member is reduced, the rate of temperature rise of the fixing roller member is increased, and the separability is improved.
In addition, the cylindrical elastic body is damaged (damaged) by metal fatigue.
The thickness of the fixing roller member is reduced, the nip width is large and the nip width is wide, energy saving reduces the warm-up time, and the deformation of the cylindrical elastic body is suppressed, preventing uneven fixing due to uneven rotation. The fixing device can be used.

According to FIG. 9, the fixing device 17 is
In the same manner as described above, on the upper side (on the side of the color toner image on the recording paper P), a thin wall having a spring property for fixing the color toner image is held by a resin bearing 171j as a ring-shaped holding member. A fixing roller 17a as a fixing roller member using a thin plate elastic roller 171a as a cylindrical elastic body is disposed, and a pressure roller 47a as a pressure roller member having elasticity is disposed below. Inside the fixing roller 17a, a halogen heater 171g, which is a heating unit having a heating filament (not shown) as a heating source, is provided.

The upper fixing roller 17a, which is a thin plate-like fixing roller member, is a thin plate elastic roller 171a which is a thin cylindrical elastic body having a spring property, as described above with reference to FIG.
And a rubber layer 171b on the outer side (outer peripheral surface) of the thin plate elastic roller 171a.

The thickness (thickness) t (mm) of the thin plate elastic roller 171a is 0.07 to 0.7, depending on the diameter.
For example, nickel having a thickness of about 0 mm can be used, but preferably a spring (thin wall) metal member having a spring property using stainless steel, phosphor bronze, or the like is used. The use of the metal member can prevent the occurrence of fatigue failure due to the elastic deformation of the thin plate elastic roller 171a, which is a cylindrical elastic member, when the thin plate elastic roller 171a is applied to the fixing device 17. To prevent the occurrence of fatigue fracture due to elastic deformation,
At Plane Bending Fatigue Test method (JIS, Z2275), by repeating several 10 ⁷ times, it is preferable that a metal member of a thin plate (thin) with 140 N / mm ² or more fatigue strength has been confirmed experimentally Was.

The thickness t of the thin elastic roller 171a is
(Mm), the outer diameter of the thin plate elastic roller 171a is R
(Mm), the following condition is satisfied: R / 50>t> R / 300.
In this case, the width of the nip portion N can be increased to 5 to 30 mm without deformation or breakage. Outer diameter R of thin plate elastic roller 171a
Is preferably 15 to 40 mm. t ≧ R / 5
In the case of 0, when the thin plate elastic roller 171a is too thick and applied to the fixing device 17, it does not deform into an elliptical shape and the width of the nip portion N does not become wide. There is also a disadvantage that the rate of temperature rise is slow due to a large heat capacity. When t ≦ R / 300, the thickness of the thin plate elastic roller 171a is too thin, and when applied to the fixing device 17, the strength is too low and the pressing force is insufficient, resulting in uneven fixing. Further, the heat capacity is small, which causes a temperature difference during paper passing.

Outside (outer peripheral surface) of the thin plate elastic roller 171a
It is preferable that the rubber layer 171b provided with a thickness of about 0.3 to 1 mm as silicon or fluorine-based rubber. By providing the rubber layer 171b, occurrence of fixing unevenness is reduced. Thereby, it can be used also as a fixing device for color fixing that can give glossiness.

The pressure roller 47a as the lower pressure roller member is, for example, a rod-shaped core metal 47 made of stainless steel.
1a and a rubber roller layer 471b having a rubber hardness of 20Hs to 70Hs (JIS, A rubber hardness), preferably 30Hs to 40Hs, for example, using a silicon material outside the metal core 471a. Is done. The pressure roller 47a is pressed (pressed) against the fixing roller 17a (the fixing roller 17a may be pressed against the pressure roller 47a as described later), and the nip portion N is formed. The rubber hardness is preferably the same for the rubber layer 171b used on the surface of the thin plate elastic roller 171a.

An elastic rubber roller having a high heat insulating property is used for the lower pressing roller 47a, and the upper thin elastic roller 171a is used.
Of the heat to the lower pressure roller 47a, and a wide nip width of 5 to 30 mm is secured.

A ring using a heat-insulating resin member such as a fluororesin, for example, at both ends of a fixing roller 17a as a fixing roller member using a thin plate elastic roller 171a as a thin cylindrical elastic body having a spring property. A resin bearing 171j as a holding member is fitted, and both ends of the fixing roller 17a are held by a resin bearing 171j as a holding member having an inner diameter larger than the outer diameter of the fixing roller 17a. The fixing roller 17a integrated with the resin bearings 171j at both ends is rotatable by bearings B5 as bearing members fitted into the resin bearings 171j as holding members at both ends. At this time, bearing bearings B at both ends
5, it is also possible to directly hold the fixing roller 17a. A receiving plate PL made of a resin member having good slipperiness using, for example, fluororesin is provided on both ends of the fixing roller 17a.
b, and the fixing roller 17a is positioned from both ends.

The pressing roller 47 is held between resin bearings 171j as holding members provided at both ends of the fixing roller 17a.
a, a center position of a bearing B5 as a bearing member at both ends to be fitted in alignment with a center position of the resin bearings 171j at both ends is pressed by a pressing spring SPa as a pressing member, and the fixing roller is pressed. 17a and pressure roller 47
a is crimped. The center position between the center positions of the holding portions of the bearing B5 as the bearing member pressed by the pressing springs SPa at both ends (the position interval of the width indicated by L1 in FIG. 9) is the center position of the resin bearing 171j as the holding member at both ends. Resin bearings 171j and bearing bearings B5 at both ends are provided with the same spacing.

The lower pressure roller 47a is provided with a gear G12 fixed to one end of a metal core 471a of the pressure roller 47a, and the gear G22 driven and rotated by the fixing drive motor M1. Is connected to the gear G12, and the pressing roller 47a is rotationally driven by the driving of the fixing driving motor M1, and the fixing roller 17 which is pressed against the pressing roller 47a
a is driven and rotated. Following rotation, the fixing roller 17
The rotation of a is made uniform, and uneven fixing is prevented.

As described above, the fixing roller member is a thin thin elastic roller 171a having a spring property.
The pressing force against the pressing roller 47a is received by the elastic force of the thin plate elastic roller 171a of the fixing roller 17a. This allows
The thin plate elastic roller 171a spreads in an elliptical shape without plastic deformation, and presses the soft rubber roller layer 471b of the pressing roller 47a on the surface of the thin plate elastic roller 171a which is almost flat, and has a wide downward convex shape of 5-30 mm. A nip N is formed. Good fixing of the toner image is performed by the wide nip portion N of 5 to 30 mm.

As described above, even if the fixing roller member has a small diameter, the nip width can be made as wide as 5 to 30 mm, so that it is possible to realize a fixing device which saves energy and has a short warm-up time.

However, in the fixing device 17, the fixing roller 17 a using the cylindrical elastic body pressed by the pressing springs SPa at both ends, when the fixing roller 17 a is supported at both ends, the width of the fixing roller 17 a is smaller than that of the fixing roller 17 a. Upon receiving the pressing force of the pressure roller 47a, as shown in FIG.
The pressing force at the nip portion N becomes non-uniform, or the deformation at the end of the fixing roller 17a becomes large, so that the fixing roller 17a
Causes uneven rotation, causing uneven fixing. For this reason, in order to achieve uniform pressing between the fixing roller member and the pressure roller member using the cylindrical elastic body and to prevent deformation of the end portion of the fixing roller 17a, the following dimensional relationship is preferable.

First, the width of the pressure roller 47a, which is narrower than the fixing roller 17a, is set to L2 (m
m), the width between the center positions of the holding portions by the bearings B5 as the bearing members at both ends of the fixing roller 17a as the fixing roller member (same as the width between the center portions of the holding portions by the resin bearing 171j as the holding member) is L1 ( mm), it is preferable that L2 / L1 = 0.90 to 0.99 in order to uniformly press the fixing roller member and the pressure roller member. 90% or more of the width L2 of the pressure roller 47a is defined as the width of the width L1 between the center positions of the holding portions of the resin bearings 171j (or the bearing B5 as the bearing member) as the holding members at both ends, and the width of the fixing roller 17a. Mutual deformation of the pressure roller 47a and the pressure roller 47a is prevented, and uniform pressing is achieved. Specifically, for example, when the A-3 vertical feed size is used as the maximum transfer material size, the width L2 of the pressing roller 47a narrower than the width L1 between the holding portion center positions is the A-3 vertical feed size. A width slightly wider than the width (297 mm) of about 300 to 340 mm is used, but a resin bearing 171j as a holding member at both ends is used.
90-99% of the width L1 between the center positions of the holding portions of the bearings (or the bearing B5 as a bearing member) is
7a, the width of the pressing roller 47a of the fixing roller 17a
Roller 17a generated by deformation
Prevents uneven fixing due to uneven rotation. Therefore, when the width between the center positions of the holding portions by the bearings B5 as the bearing members at both ends of the fixing roller 17a (same as the width between the center positions of the holding portions by the resin bearing 171j as the holding member) is L1 (mm), A-3 Width L1 between the center positions of the holding units corresponding to the vertical feed size width (297 mm)
Is preferably about 300 to 380 mm.

With the above setting, uniform pressing between the cylindrical elastic body of the fixing roller member and the pressure roller member is achieved, and uneven fixing due to uneven rotation of the fixing roller member is prevented.

As a second condition, the width of the fixing roller 17a as a fixing roller member using a cylindrical elastic body is set to L.
(Mm), the width between the center positions of the holding parts by the bearings B5 as the bearing members at both ends of the fixing roller 17a (the same as the width between the center parts of the holding parts by the resin bearing 171j as the holding member) is L1 (mm). At this time, setting L1 / L = 0.70 to 0.90 is determined by pressing the end of the fixing roller member.
It is preferable to prevent deformation of the end of the fixing roller 17a using a cylindrical elastic body. Width Lj of resin bearing 171j
(Mm) is for holding the wide fixing roller 17a.
It is preferable to provide a width of about 10 to 30 mm in order to receive uniform pressing, and the end of the fixing roller 17a is the same as the outer end of the resin bearing 171j, or the outer end of the resin bearing 171j. It is preferable that the end portion of the fixing roller 17a is not directly pressed, the deformation of the end portion of the fixing roller 17a is prevented, and the end portion of the fixing roller 17a is uniformly pressed. A gap L1 of about 0 to 20 mm with the end of 17a
It is preferable to provide 1 (mm). Therefore, specifically, in order to prevent deformation of the end portion of the fixing roller 17a and prevent uneven fixing due to uneven rotation of the fixing roller 17a resulting from the deformation, for example, the A-3 vertical feed size width (297
mm), the width L1 between the center positions of the holding portions by the bearings B5 as the bearing members at both ends of the fixing roller 17a (same as the width between the center positions of the holding portions by the resin bearing 171j as the holding member) is L × (0.70
0.90) = L1, about 300 to 380 mm, and the width L of the fixing roller 17a as a fixing roller member
Is preferably set to about 420 mm.

With the above setting, the deformation of the end of the cylindrical elastic body of the fixing roller member is prevented, the deformation of the cylindrical elastic body is made uniform, and the fixing roller member using the cylindrical elastic body is stably held. And fixing unevenness due to uneven rotation of the fixing roller member is prevented.

[0088]

According to the first aspect of the present invention, the thickness of the fixing roller member can be reduced without causing the cylindrical elastic body to be damaged (damaged) by metal fatigue, the nip width is small, the nip width is wide, energy is saved, and the warm-up time is reduced. While being shortened,
A fixing device in which the amount of deformation of the cylindrical elastic body is suppressed and uneven fixing due to uneven rotation of the fixing roller member is prevented is enabled.

According to the second aspect, the fixing roller member is made small in diameter, the heat capacity of the fixing roller member is reduced, the rate of temperature rise of the fixing roller member is increased, and the separability is improved.

According to the third aspect, the diameter of the fixing roller member is reduced, the heat capacity of the fixing roller member is reduced, the temperature rising speed of the fixing roller member is increased, the separability is improved, and the cylindrical elastic member is improved. The thickness of the fixing roller member is reduced without being damaged by metal fatigue.
The fixing device has a small diameter, a wide nip width, saves energy, shortens the warm-up time, suppresses the deformation of the cylindrical elastic body, and prevents uneven fixing due to uneven rotation of the fixing roller member.

According to the fourth aspect, it is possible to increase the nip width without deformation and breakage of the cylindrical elastic body and obtain an appropriate pressing force.

According to the fifth aspect, uniform pressing between the cylindrical elastic body of the fixing roller member and the pressure roller member is achieved, and uneven fixing due to uneven rotation of the fixing roller member is prevented.

According to the sixth aspect, the deformation of the end portion of the cylindrical elastic body of the fixing roller member is prevented, the deformation of the cylindrical elastic body is made uniform, and the fixing roller member using the cylindrical elastic body is deformed. Stable holding is enabled, and uneven fixing due to uneven rotation of the fixing roller member is prevented.

According to the seventh aspect, it is possible to increase the nip width without deformation and breakage of the cylindrical elastic body, and to obtain an appropriate pressing force.

[Brief description of the drawings]

FIG. 1 is a sectional view of a color image forming apparatus showing an embodiment of an image forming apparatus using a fixing device according to the present invention.

FIG. 2 is a side sectional view of the image forming body of FIG. 1;

FIG. 3 is a schematic sectional view of a fixing device according to the present invention.

FIG. 4 is a schematic side view showing an example of a method of holding the fixing device of FIG.

FIG. 5 is a diagram illustrating a layer configuration and a function of a fixing roller member.

FIG. 6 is a schematic side view showing another example of a method of holding the fixing device.

FIG. 7 is a diagram illustrating deformation amounts of a fixing roller member and a pressure roller member.

FIG. 8 is a diagram illustrating deformation amounts of a fixing roller member and a pressure roller member.

FIG. 9 is a diagram illustrating an arrangement of a fixing roller member and a pressing roller member, and a dimensional relationship between a width between holding center positions of the fixing roller member and a pressing roller member width or a fixing roller member width.

FIG. 10 is a diagram illustrating a problem when pressing a fixing roller member using a cylindrical elastic body.

DESCRIPTION OF SYMBOLS 10 Photoreceptor drum 11 Scorotron charger 12 Exposure optical system 13 Developing device 17 Fixing device 17a Fixing roller 47a Pressure roller 171a Thin plate elastic roller 171j Resin bearing 171g Halogen heater B5 Bearing bearing N Nip P Recording paper

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yotaro Sato 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation F-term (reference) 2H033 AA02 AA21 AA23 AA30 AA32 BB02 BB12 BB28 BB33 3J103 AA02 AA14 BA03 BA31 BA41 CA52 CA78 FA02 FA12 FA18 FA20 FA26 GA02 GA57 GA58 GA60 GA66 HA03 HA05 HA12 HA33 HA36 HA53

Claims (7)

[Claims] 1. A fixing device for fixing a toner image on a transfer material, comprising: a fixing roller member having a heating unit; and a pressure roller member having elasticity opposed to the fixing roller member. Is a thin cylindrical elastic body, and both ends of the fixing roller member are held by a holding member having an inner diameter larger than the outer diameter of the fixing roller member. A fixing device, wherein the amount of deformation is smaller than the amount of deformation of the pressure roller member. 2. A fixing device for fixing a toner image on a transfer material, comprising: a fixing roller member having a heating unit; and an elastic pressure roller member facing the fixing roller member, wherein the fixing roller member is provided. Is a thin cylindrical elastic body, and both ends of the fixing roller member are held by a holding member having an inner diameter larger than an outer diameter of the fixing roller member. A fixing device having a diameter smaller than an outer diameter of the pressure roller member. 3. The fixing device according to claim 2, wherein the amount of deformation of the fixing roller member with respect to a constant load is smaller than the amount of deformation of the pressure roller member. 4. When the outer diameter of the cylindrical elastic body is R (mm), the thickness t (mm) of the cylindrical elastic body is R / 50>t> R / 300. The fixing device according to claim 1, wherein: 5. A fixing device for fixing a toner image on a transfer material, comprising: a fixing roller member having a heating unit; and a pressure roller member having elasticity opposed to the fixing roller member. Is a thin cylindrical elastic body, and both ends of the fixing roller member are held by a holding member having an inner diameter larger than the outer diameter of the fixing roller member. The width of the pressure roller member is L2. (Mm), the width between the center positions of the holding portions of the fixing roller member by the holding member is L
The fixing device according to claim 1, wherein L2 / L1 = 0.90 to 0.99. 6. A fixing device for fixing a toner image on a transfer material, comprising: a fixing roller member having a heating unit; and an elastic pressure roller member facing the fixing roller member, wherein the fixing roller member is provided. Is a thin cylindrical elastic body, and both ends of the fixing roller member are held by a holding member having an inner diameter larger than the outer diameter of the fixing roller member. The width of the fixing roller member is L ( mm), the width between the center positions of the holding portions of the fixing roller member by the holding member is L1
(1) where L1 / L = 0.70 to 0.95. 7. When the outer diameter of the cylindrical elastic body is R (mm), the thickness t (mm) of the cylindrical elastic body is R / 50>t> R / 300. The fixing device according to claim 5, wherein: