JP2001215831A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small diameter, and wide nip width fixing device capable of preventing the uneven deformation of the central part and the end part of a cylindrical elastic body, in a fixing roller member using the cylindrical elastic body, and capable of preventing the cylindrical elastic body from being damaged due to the metal fatigue by the deformation of the cylindrical elastic body, and also, capable of making the fixing roller member thin in thickness, reducing energy consumption and shortening a warming up time. SOLUTION: The fixing roller member is formed of the thin cylindrical elastic body, and also, both ends of the fixing roller member are held by a holding member whose inside diameter is larger than the outside diameter of the fixing roller member, and the fixing roller member is installed while passing through the holding member, and the fixing device is provided with a supporting means for supporting the end part of the fixing roller member from a pressure roller member side.

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.

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. In addition, there is a problem that it takes time to warm up the fixing device during printing, and the printing time (warming-up time) becomes longer.

In order to solve this problem and to make the fixing roller member energy-saving and have a short warm-up time, the fixing roller member needs to be thinner and smaller in diameter. The fixing roller member is constructed using a cylindrical elastic body having a ramp, and the fixing roller member is made thinner and smaller in diameter, and a fixing device that has a small diameter, a wide nip width, saves energy, and shortens the warm-up time is studied. And Japanese Patent Application No. 11-230499
Issue.

[0005]

However, in the fixing device using the fixing roller member using the above-described cylindrical elastic body, the deformation of the central and end portions of the cylindrical elastic body occurs, and the rotation of the fixing roller member is caused. There is a problem that uneven fixing occurs due to unevenness. Further, the fixing roller member may be damaged (damage) due to metal fatigue due to deformation, or if the diameter of the fixing roller member is reduced, the nip width (width of the nip portion) may be insufficient, resulting in poor fixing.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in a fixing roller member using a cylindrical elastic body, prevents unevenness in deformation between a central portion and an end portion of the cylindrical elastic body, and deforms the cylindrical elastic body. It is an object of the present invention to provide a fixing device capable of reducing the thickness of a fixing roller member without damaging a cylindrical elastic body due to metal fatigue, having a small diameter, a wide nip width, saving energy, and shortening a warm-up time.

[0007]

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. Wherein the fixing roller member is provided so as to penetrate through the fixing roller member, and has a support means for supporting an end of the fixing roller member from the pressure roller member side (first invention)
Achieved by

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. A pressing member that presses at least one of the pressure roller members by a pressing unit and that prevents a distance between the fixing roller member and the pressing roller member by the pressing unit from becoming equal to or less than a predetermined distance. This is achieved by a fixing device (second 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. At least one of the pressure roller members abuts a gap maintaining means by the pressing of a pressing means to maintain a gap between the fixing roller member and the pressure roller member. 3 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. In the following description of each example of the fixing device, members having similar functions and structures are denoted by the same reference numerals.

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 view of a color image forming apparatus showing an embodiment of an image forming apparatus using a fixing device according to the present invention, and FIG. 2 is a side cross-sectional view of the image forming body of FIG. 3 is a schematic sectional view of the fixing device, FIG. 4 is a schematic side view of the fixing device of FIG. 3, and FIG. 5 is a diagram illustrating a layer configuration and functions of the fixing roller member.

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 member 17a is a thin plate-shaped fixing roller 17a which is an upper fixing roller member (on the side of the color toner image on the recording paper P) for fixing a color toner image, and a lower pressing roller member having elasticity. A heating means for emitting heat rays such as infrared rays or far infrared rays including visible light depending on the light source, preferably a halogen lamp 171g or a xenon lamp (not shown) is provided inside the fixing roller 17a. Are provided.

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. A heating means for emitting heat rays such as infrared rays or far infrared rays including visible light depending on the light source, preferably a halogen lamp 171g or a xenon lamp (not shown) is provided inside 17a. Halogen lamp 171g
The thin plate elastic roller 171a is heated by light emitted from a light source such as a xenon lamp (not shown) or the like.

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 a spring material having a fatigue limit which can be used as a spring material is preferably formed of a thin metal member having a spring property using stainless steel, phosphor bronze, or the like. By using the metallic member of the above, it is possible to prevent the occurrence of fatigue failure due to the elastic deformation of the thin plate elastic roller 171a that is a cylindrical elastic body when the thin plate elastic roller 171a is applied to the fixing device 17. In preventing the occurrence of fatigue failure due to elastic deformation, at Plane Bending Fatigue Test method (JIS, Z2275), by repeating several 10 ⁷ times, a thin metal plate (thin) with 140 N / mm ² or more fatigue strength It has been experimentally confirmed that it is preferable to use a conductive member.

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
The thickness of the rubber layer 171b is preferably 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 includes, for example, a rod-shaped metal pipe 471a made of stainless steel, and a silicon hardness of 10 Hs or more made of, for example, silicon outside the metal pipe 471a. 70Hs (J
IS, A rubber hardness), preferably 15Hs to 40Hs
Thus, it is configured as an elastic soft roller having a rubber roller layer 471b having a thickness of 3 mm to 10 mm. The rubber hardness is preferably the same for the rubber layer 171b used on the surface of the thin plate elastic roller 171a.
The fixing roller 17a presses (presses) the pressing roller 47a (the pressing roller 47a may press the fixing roller 17a), and the nip portion N is formed. An elastic rubber roller having a high heat insulating property is used for the lower pressing roller 47a to prevent the diffusion of heat from the upper thin plate elastic roller 171a to the lower pressing roller 47a and to reduce the thickness by 5 to 30 mm.
Wide nip width.

As shown in FIG. 4, both ends of the fixing roller 17a are penetrated through 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. 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 are used 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 the fixing roller bearings B5 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 fixing roller bearings B5 at both ends. A receiving plate P made of a resin member having good slipperiness using, for example, a fluororesin is provided at both ends of the fixing roller 17a.
Lb is provided, and the fixing roller 17a is positioned from both ends.

The center positions of the fixing roller bearings B5 at both ends, which are fitted in alignment with the center positions of the resin bearings 171j at both ends provided through the fixing roller 17a, are fixedly loaded by the fixing roller pressing spring SPa. For example, the fixing roller 17a is pressed via the resin bearing 171j with a load of, for example, 50 to 500N, and the fixing roller 17a and the pressure roller 47a are pressed. A resin bearing 171 as a holding member at both ends is provided between the center positions of the holding portions of the fixing roller bearings B5 pressed by the fixing roller pressing springs SPa at both ends (positional intervals having a width indicated by L1 in FIG. 4).
j, the resin bearings 17 on both ends
1j and the fixing roller bearing B5.
Thus, the pressure roller 4 narrower than the fixing roller 17a
7a prevents deformation of the end of the thin plate elastic roller 171a which receives the pressing force.

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

As described above, the fixing roller 17a serving as the fixing roller member is a thin thin elastic roller 171a having a spring property, and the resin bearing 171j holding the fixing roller 17a is pressed to form an elastic pressure roller. The pressing force of 47a is applied to the thin elastic roller 1 of the fixing roller 17a.
(The pressing roller 47a is pressed against the fixing roller 17a, and the pressing force against the pressing roller 47a is received by the elastic force of the thin thin elastic roller 171a having the spring property of the fixing roller 17a.) May be done). As a result, the thin elastic roller 171a expands in an elliptical shape without plastic deformation, and a soft rubber roller layer 471b of the pressing roller 47a is formed on the surface of the thin elastic roller 171a which is almost flat.
To form a convex wide nip portion N of 5 to 30 mm on the lower side. 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 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 large curvature (the radius of the curved surface is small) of the pressure roller 47a at the outlet of the nip portion N improves the separability from the recording paper P.

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.

However, in the fixing device 17, in the fixing roller 17a using a cylindrical elastic body pressed against the pressure roller 47a, the fixing roller 17a
Are supported at both ends, and the fixing roller pressing springs SPa at both ends are provided.
Roller 17 using cylindrical elastic body pressed by
a, a thin plate elastic roller 171a as a cylindrical elastic body;
Of the fixing roller 17a.
This causes a problem that fixing unevenness occurs due to rotation unevenness.

The means for supporting the cylindrical elastic body for preventing the fixing roller member from being deformed unevenly will be described with reference to FIG. 6 or FIG. 7 and FIG. FIG. 6 is a schematic sectional view of a fixing device using a first example of a fixing roller member supporting unit, and FIG. 7 is a schematic sectional view of a fixing device using a second example of a fixing roller member supporting unit. is there.

According to FIG. 6 and FIG. 5, the fixing device 17 is held on the upper side (on the side of the color toner image on the recording paper P) by a resin bearing 171j as a ring-shaped holding member. Thin plate elastic roller 1 as a thin cylindrical elastic body having a spring property for fixing a toner image
Fixing Roller 17 as Fixing Roller Member Using 71a
a pressure roller 47a as a pressure roller member having elasticity is disposed on the lower side, and an infrared ray including visible light depending on a light source is provided inside the fixing roller 17a. Alternatively, a heating unit that emits heat rays such as far infrared rays, preferably a halogen lamp 171 g or a xenon lamp (not shown) is provided. Halogen lamp 1
The thin plate elastic roller 171a is heated by light emitted from 71g or a xenon lamp (not shown).

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

The thickness (thickness) t (mm) of the thin 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 a spring material having a fatigue limit which can be used as a spring material is preferably formed of a thin metal member having a spring property using stainless steel, phosphor bronze, or the like. By using the metallic member of the above, it is possible to prevent the occurrence of fatigue failure due to the elastic deformation of the thin plate elastic roller 171a that is a cylindrical elastic body when the thin plate elastic roller 171a is applied to the fixing device 17. In preventing the occurrence of fatigue failure due to elastic deformation, at Plane Bending Fatigue Test method (JIS, Z2275), by repeating several 10 ⁷ times, a thin metal plate (thin) with 140 N / mm ² or more fatigue strength It has been experimentally confirmed that it is preferable to use a conductive member.

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
The thickness of the rubber layer 171b is preferably 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 composed of, for example, a rod-shaped metal pipe 471a made of stainless steel, and a silicon hard material made of, for example, silicon outside the metal pipe 471a. 70Hs (J
IS, A rubber hardness), preferably 15Hs to 40Hs
Thus, it is configured as an elastic soft roller having a rubber roller layer 471b having a thickness of 3 mm to 10 mm. The rubber hardness is preferably the same for the rubber layer 171b used on the surface of the thin plate elastic roller 171a.
The fixing roller 17a presses (presses) the pressing roller 47a (the pressing roller 47a may press the fixing roller 17a), and the nip portion N is formed. An elastic rubber roller having a high heat insulating property is used for the lower pressing roller 47a to prevent the diffusion of heat from the upper thin plate elastic roller 171a to the lower pressing roller 47a and to reduce the thickness by 5 to 30 mm.
Wide nip width.

A heat insulating property such as fluororesin is applied to both ends of the fixing roller 17a by passing through the 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. A resin bearing 171j as a ring-shaped holding member using a resin 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 the fixing roller bearings B5 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 fixing roller bearings B5 at both ends. Fixing roller 1
A receiving plate PLb made of a resin member having good slipperiness, for example, using a fluororesin or the like is provided at both ends of 7a, and the fixing roller 17a is positioned from both ends.

The center positions of the fixing roller bearings B5 at both ends, which are fitted in alignment with the center positions of the resin bearings 171j at both ends provided through the fixing roller 17a, are fixedly loaded by the fixing roller pressing spring SPa. For example, the fixing roller 17a is pressed via the resin bearing 171j with a load of, for example, 50 to 500N, and the fixing roller 17a and the pressure roller 47a are pressed. A resin bearing 171 as a holding member at both ends is provided between the center positions of the holding portions of the fixing roller bearing bearings B5 pressed by the fixing roller pressing springs SPa at both ends (positional intervals having a width indicated by L1 in FIG. 6).
j, the resin bearings 17 on both ends
1j and the fixing roller bearing B5.
Thus, the pressure roller 4 narrower than the fixing roller 17a
7a prevents deformation of the end portion of the thin plate elastic roller 171a which receives the pressing force. In particular, in order to prevent uneven deformation of the center portion and the end portion of the thin plate elastic roller 171a of the fixing roller 17a, a resin as a holding member is used. On both ends of the metal pipe 471a of the pressure roller 47a with the bearing 171j interposed therebetween,
A support roller SR1 as a support member having the same diameter as the pressure roller 47a is provided as support means for the fixing roller 17a, and the support roller SR1 is abutted against the fixing roller 17a to support both ends of the fixing roller 17a.

As described above, the deformation of the central portion and 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 using the cylindrical elastic body is formed. The members can be stably held.

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

As described above, the fixing roller 17a serving as a fixing roller member is a thin thin elastic roller 171a having a spring property, and a resin bearing 171j holding the fixing roller 17a is pressed to form an elastic pressure roller. The pressing force of 47a is applied to the thin elastic roller 1 of the fixing roller 17a.
Received by the elastic force of 71a. 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 warm-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 large curvature (the radius of the curved surface is small) of the pressure roller 47a at the outlet of the nip portion N improves the separability from the recording paper P.

As described above, the thickness of the fixing roller member can be reduced without plastic deformation by the thin cylindrical elastic body, and the stable fixing roller member can be stably held by the bearing member. It is possible to provide a fixing device having a large warming-up time with a large energy saving of 30 to 30 mm, and prevent the deformation of the central portion and the end portion of the cylindrical elastic body of the fixing roller member, thereby preventing the cylindrical elastic body from being deformed. As a result, it is possible to stably hold the fixing roller member using the cylindrical elastic body, to prevent uneven fixing due to uneven rotation of the fixing roller member, and to provide a fixing device capable of performing satisfactory fixing.

In the above, as shown in FIG. 7, both ends of the pressure roller 47a as the lower pressure roller member are provided.
The resin bearing 171j as a holding member into which the fixing roller bearing B5 is fitted escapes to form a concave portion LS, and the support portions SJ on both side ends of the concave portion LS abut against the fixing roller 17a as support means. Both ends of the fixing roller 17a are supported by support portions SJ at both ends having the same diameter as the pressure roller 47a.

According to the above configuration, deformation unevenness between the central portion and the end portion of the cylindrical elastic body of the fixing roller member can be prevented.
The deformation of the cylindrical elastic body is made uniform, the fixing roller member using the cylindrical elastic body can be stably held, the fixing unevenness due to the uneven rotation of the fixing roller member is prevented, and the fixing is performed with good fixing. The device becomes possible.

Further, in the fixing device 17 described with reference to FIGS. 3 to 5, the fixing roller 17a using the pressure roller 47a and the thin plate elastic roller 171a as a cylindrical elastic body pressed against each other is different from the fixing roller 17a. There is a problem that the fixing roller member is damaged (damaged) by metal fatigue due to deformation of the thin plate elastic roller 171a.

A method for preventing damage due to metal fatigue due to deformation of the fixing roller member will be described with reference to FIGS. 8 to 10 and FIG. FIG. 8 is a schematic sectional view of a fixing device using a first example of a method of preventing damage to a fixing roller member due to metal fatigue, and FIG. 9 is a second example of a method of preventing damage to the fixing roller member due to metal fatigue. FIG. 10 is a schematic cross-sectional view of a fixing device using an example, and FIG. 10 is a schematic cross-sectional view of a fixing device using a third example of a method of preventing damage to a fixing roller member due to metal fatigue.

According to FIG. 8 and FIG. 5, the fixing device 17 is held on the upper side (on the side of the color toner image on the recording paper P) by a resin bearing 171j as a ring-shaped holding member. Thin plate elastic roller 1 as a thin cylindrical elastic body having a spring property for fixing a toner image
Fixing Roller 17 as Fixing Roller Member Using 71a
a pressure roller 47a as a pressure roller member having elasticity is disposed on the lower side, and an infrared ray including visible light depending on a light source is provided inside the fixing roller 17a. Alternatively, a heating unit that emits heat rays such as far infrared rays, preferably a halogen lamp 171 g or a xenon lamp (not shown) is provided. Halogen lamp 1
The thin plate elastic roller 171a is heated by light emitted from 71g or a xenon lamp (not shown).

The fixing roller 17a, which is an upper thin plate-like fixing roller member, is a thin plate elastic roller 171 which is a thin cylindrical elastic body having a spring property, as described above with reference to FIG.
a and a rubber layer 171b on the outside (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 a spring material having a fatigue limit which can be used as a spring material is preferably formed of a thin metal member having a spring property using stainless steel, phosphor bronze, or the like. By using the metallic member of the above, it is possible to prevent the occurrence of fatigue failure due to the elastic deformation of the thin plate elastic roller 171a that is a cylindrical elastic body when the thin plate elastic roller 171a is applied to the fixing device 17. In preventing the occurrence of fatigue failure due to elastic deformation, at Plane Bending Fatigue Test method (JIS, Z2275), by repeating several 10 ⁷ times, a thin metal plate (thin) with 140 N / mm ² or more fatigue strength It has been experimentally confirmed that it is preferable to use a conductive member.

The thickness t of the thin plate 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 elastic roller 171a
The thickness of the rubber layer 171b is preferably 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 composed of, for example, a rod-shaped metal pipe 471a using a stainless steel material, and a rubber material using a silicon material outside the metal pipe 471a. 70Hs (J
IS, A rubber hardness), preferably 15Hs to 40Hs
Thus, it is configured as an elastic soft roller having a rubber roller layer 471b having a thickness of 3 mm to 10 mm. The rubber hardness is preferably the same for the rubber layer 171b used on the surface of the thin plate elastic roller 171a.
The fixing roller 17a presses (presses) the pressing roller 47a (as described later, the pressing roller 47a
7a may be pressed), and a nip portion N is formed. An elastic rubber roller having high heat insulation properties is used for the lower pressure roller 47a to prevent the diffusion of heat from the upper thin plate elastic roller 171a to the lower pressure roller 47a, and a wide nip width of 5 to 30 mm. Secure.

A heat insulating property such as a fluororesin is applied to both ends of the fixing roller 17a by passing through the 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. A resin bearing 171j as a ring-shaped holding member using a resin 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 the fixing roller bearings B5 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 fixing roller bearings B5 at both ends. Fixing roller 1
A receiving plate PLb made of a resin member having good slipperiness, for example, using a fluororesin or the like is provided at both ends of 7a, and the fixing roller 17a is positioned from both ends.

The center positions of the fixing roller bearings B5 at both ends, which are fitted so as to match the center positions of the resin bearings 171j at both ends provided through the fixing roller 17a, are fixed to the fixing roller pressing spring SPa as pressing means. Thus, the fixing roller 17a is pressed via the resin bearing 171j with a constant load, for example, a load of 50 to 500N, and the fixing roller 17a and the pressure roller 47a are pressed. Between the center positions of the holding portions of the fixing roller bearing B5 pressed by the fixing roller pressing springs SPa at both ends (L1 in FIG. 8).
Is set to be the same as the center position interval of the resin bearings 171j as the holding members at both ends, and the resin bearing 171j at both ends and the fixing roller bearing B5 are disposed. This prevents deformation of the end of the thin plate elastic roller 171a which is pressed by the pressing roller 47a which is narrower than the fixing roller 17a. However, the deformation increases, and the fixing roller 17a is deformed due to metal fatigue. The fixing roller 17a and the pressing roller 47 are fixed by a fixing roller pressing spring SPa as pressing means so that the thin plate elastic roller 171a is not damaged.
In order to prevent the pressing interval (center interval) from being smaller than the specified interval (in order to prevent the deformation amount from being larger than the specified value), the position of the specified interval (the interval smaller than the damaged interval) is used. At the deformation allowable maximum reference position), for example, a stopper ST1 as an abutting member that abuts against the resin bearing 171j is provided. As shown by a dashed line in FIG. 8, a pressing roller pressing spring S for pressing the pressing roller 47a is provided.
Pressurizing roller pressing spring SP as pressing means provided with Pb
In order to prevent the pressing interval (center interval) between the fixing roller 17a and the pressing roller 47a by b from becoming smaller than the specified interval (to prevent the deformation amount from being larger than the specified value), the position of the specified interval is set. For example, a stopper ST11 as an abutting member that abuts against the metal pipe 471a of the pressure roller 47a may be provided at the (deformation allowable maximum reference position at an interval smaller than the interval at which the breakage occurs). It is good also as a structure provided with a stopper member simultaneously.

As described above, the thickness of the fixing roller member can be reduced without damaging the cylindrical elastic body due to metal fatigue caused by the deformation of the cylindrical elastic body of the fixing roller member. The amount of deformation is suppressed.

A gear G12 is fixed to one end of a metal pipe 471a of the pressure roller 47a, and a gear G22 driven and rotated by a fixing drive motor M1 is provided on the lower pressure roller 47a. The fixing roller 17a is connected to the gear G12, and rotates the pressing roller 47a by driving the fixing driving motor M1, so that the fixing roller 17 is pressed by the pressing roller 47a.
a is driven to rotate. Following rotation, the fixing roller 17
The rotation of a is made uniform, and uneven fixing is prevented.

As described above, the fixing roller 17a as a fixing roller member is a thin thin elastic roller 171a having a spring property, and a resin bearing 171j holding the fixing roller 17a is pressed to form an elastic pressure roller. The pressing force of 47a is applied to the thin elastic roller 1 of the fixing roller 17a.
(As described above, the pressing roller 47a is pressed against the fixing roller 17a and the pressing roller 4a is pressed).
The pressing force with the fixing roller 7a may be received by the elastic force of the 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 which is almost planar, thereby forming a convex 5 to 5 below. 30mm
A wide nip portion 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 a fixing device which is energy saving 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 large curvature (the radius of the curved surface is small) of the pressure roller 47a at the outlet of the nip portion N improves the separability from the recording paper P.

As described above, the thickness of the fixing roller member can be reduced without plastic deformation by the thin cylindrical elastic body, and the stable fixing roller member can be stably held by the bearing member. A fixing device having a large warming-up time with energy savings of up to 30 mm is possible, and the cylindrical elastic body is damaged (damaged) due to metal fatigue due to deformation of the cylindrical elastic body of the fixing roller member.
The thickness of the fixing roller member is reduced, the nip width is wide, the energy saving reduces the warm-up time, and the amount of deformation of the cylindrical elastic body is suppressed, resulting in uneven rotation of the fixing roller member. Fixing unevenness is prevented, and a fixing device in which good fixing is performed can be realized.

According to FIG. 9 and FIG. 5, the fixing device 17 is held on the upper side (on the side of the color toner image on the recording paper P) by a resin bearing 171j as a ring-shaped holding member. Thin plate elastic roller 1 as a thin cylindrical elastic body having a spring property for fixing a toner image
Fixing Roller 17 as Fixing Roller Member Using 71a
a pressure roller 47a as a pressure roller member having elasticity is disposed on the lower side, and an infrared ray including visible light depending on a light source is provided inside the fixing roller 17a. Alternatively, a heating unit that emits heat rays such as far infrared rays, preferably a halogen lamp 171 g or a xenon lamp (not shown) is provided. Halogen lamp 1
The thin plate elastic roller 171a is heated by light emitted from 71g or a xenon lamp (not shown).

The upper fixing roller 17a, which is a thin plate-like fixing roller member, is a thin plate elastic roller 171 which is a thin cylindrical elastic body having a spring property, as described above with reference to FIG.
a and a rubber layer 171b on the outside (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 a spring material having a fatigue limit which can be used as a spring material is preferably formed of a thin metal member having a spring property using stainless steel, phosphor bronze, or the like. By using the metallic member of the above, it is possible to prevent the occurrence of fatigue failure due to the elastic deformation of the thin plate elastic roller 171a that is a cylindrical elastic body when the thin plate elastic roller 171a is applied to the fixing device 17. In preventing the occurrence of fatigue failure due to elastic deformation, at Plane Bending Fatigue Test method (JIS, Z2275), by repeating several 10 ⁷ times, a thin metal plate (thin) with 140 N / mm ² or more fatigue strength It has been experimentally confirmed that it is preferable to use a conductive member.

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
The thickness of the rubber layer 171b is preferably 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 composed of, for example, a rod-shaped metal pipe 471a made of a stainless steel material, and a rubber material having a rubber hardness of 10 Hs or more made of, for example, a silicon material outside the metal pipe 471a. 70Hs (J
IS, A rubber hardness), preferably 15Hs to 40Hs
Thus, it is configured as an elastic soft roller having a rubber roller layer 471b having a thickness of 3 mm to 10 mm. The rubber hardness is preferably the same for the rubber layer 171b used on the surface of the thin plate elastic roller 171a.
The fixing roller 17a presses (presses) the pressing roller 47a (as described later, the pressing roller 47a
7a may be pressed), and a nip portion N is formed. An elastic rubber roller having high heat insulation properties is used for the lower pressure roller 47a to prevent the diffusion of heat from the upper thin plate elastic roller 171a to the lower pressure roller 47a, and a wide nip width of 5 to 30 mm. Secure.

A heat insulating property such as a fluororesin is applied to both ends of the fixing roller 17a by passing through the 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. A resin bearing 171j as a ring-shaped holding member using a resin 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 the fixing roller bearings B5 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 fixing roller bearings B5 at both ends. Fixing roller 1
A receiving plate PLb made of a resin member having good slipperiness, for example, using a fluororesin or the like is provided at both ends of 7a, and the fixing roller 17a is positioned from both ends.

The center positions of the fixing roller bearings B5 at both ends, which are fitted in alignment with the center positions of the resin bearings 171j at both ends provided through the fixing roller 17a, are fixed to the fixing roller pressing spring SPa as pressing means. Thus, the fixing roller 17a is pressed via the resin bearing 171j with a constant load, for example, a load of 50 to 500N, and the fixing roller 17a and the pressure roller 47a are pressed. Between the center positions of the holding portions of the fixing roller bearing B5 pressed by the fixing roller pressing springs SPa at both ends (L1 in FIG. 9).
Is set to be the same as the center position interval of the resin bearings 171j as the holding members at both ends, and the resin bearing 171j at both ends and the fixing roller bearing B5 are disposed. This prevents deformation of the end of the thin plate elastic roller 171a which is pressed by the pressing roller 47a which is narrower than the fixing roller 17a. However, due to metal fatigue due to the deformation, the thin plate elastic roller 17a of the fixing roller 17a is prevented.
A position where the distance between the fixing roller 17a and the pressing roller 47a by the pressing of the fixing roller pressing spring SPa as a pressing unit is a fixed amount (a fixed deformation amount reference position) so that the fixing roller 1a is not damaged. ), A stopper ST2 is provided as gap maintaining means, and for example, a resin bearing 171j holding the fixing roller 17a is abutted against the stopper ST2 to maintain a constant distance between the fixing roller 17a and the pressure roller 47a. 9, a pressure roller pressing spring SPb for pressing the pressing roller 47a is provided, and the fixing roller 17a and the pressing roller 47a are pressed by the pressing roller pressing spring SPb as pressing means. The stopper ST21 is provided as a gap maintaining means at a position where the distance between the two is constant (constant deformation reference position), and the stopper ST2
For example, the metal roller 471a of the pressing roller 47a may be abutted against the fixing roller 1 to maintain a constant distance between the fixing roller 17a and the pressing roller 47a, or both spring members and stopper members may be provided at the same time. It may be.

As described above, the thickness of the fixing roller member can be reduced without damaging the cylindrical elastic body due to metal fatigue caused by the deformation of the cylindrical elastic body of the fixing roller member. The amount of deformation is suppressed.

Further, a gear G12 is fixed to one end of a metal pipe 471a of the pressure roller 47a, and a gear G22 driven and rotated by a fixing drive motor M1 is provided on the lower pressure roller 47a. The fixing roller 17a is connected to the gear G12, and rotates the pressing roller 47a by driving the fixing driving motor M1, so that the fixing roller 17 is pressed by the pressing roller 47a.
a is driven to rotate. Following rotation, the fixing roller 17
The rotation of a is made uniform, and uneven fixing is prevented.

As described above, the fixing roller 17a serving as the fixing roller member is a thin thin elastic roller 171a having a spring property, and a resin bearing 171j holding the fixing roller 17a is pressed to form an elastic pressure roller. The pressing force of 47a is applied to the thin elastic roller 1 of the fixing roller 17a.
(As described above, the pressing roller 47a is pressed against the fixing roller 17a and the pressing roller 4a is pressed).
The pressing force with the fixing roller 7a may be received by the elastic force of the 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 which is almost planar, thereby forming a convex 5 to 5 below. 30mm
A wide nip portion 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 a fixing device which saves energy and has a short warm-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 large curvature (the radius of the curved surface is small) of the pressure roller 47a at the outlet of the nip portion N improves the separability from the recording paper P.

As described above, the thickness of the fixing roller member can be reduced without plastic deformation by the thin cylindrical elastic body, and the stable fixing roller member can be stably held by the bearing member. A fixing device having a large warming-up time with energy savings of up to 30 mm is possible, and the cylindrical elastic body is damaged (damaged) due to metal fatigue due to deformation of the cylindrical elastic body of the fixing roller member.
The thickness of the fixing roller member is reduced, the nip width is wide, the energy saving reduces the warm-up time, and the amount of deformation of the cylindrical elastic body is suppressed, resulting in uneven rotation of the fixing roller member. Fixing unevenness is prevented, and a fixing device in which good fixing is performed can be realized.

As shown in FIG. 10, a metal pipe 471a of a pressure roller 47a as a lower pressure roller member is provided.
A pressure roller holding bearing B6 is provided at both ends of the fixing roller 17a, and a fixing roller bearing bearing B5 fitted into a resin bearing 171j as a holding member at both ends of the fixing roller 17a as an upper fixing roller member, and a lower pressure roller 47a. The two ends of the metal pipe 471a are fitted with the pressure roller holding bearings B6 at both ends thereof as gap maintaining means, and are fitted in alignment with the center positions of the resin bearings 171j at both ends provided through the fixing roller 17a. The center position of the roller bearing B5 is fixed by a fixed load, for example, 50 to 50 by a fixing roller pressing spring SPa as a pressing unit.
With a load of 0N, the fixing roller 17a is pressed through the resin bearing 171j, and the fixing roller bearing B5 and the pressure roller holding bearing B used as gap maintaining means are used.
6 and the fixing roller 17a and the pressure roller 4
The fixing roller 17a and the pressure roller 47a are pressed against each other so that the distance between the fixing roller 17a and the pressure roller 47a is maintained such that the distance between the fixing roller 17a and the pressure roller holding bearing B6 abuts at a constant deformation amount reference position. Configuration. At this time, as shown by a dashed line in FIG. 10, a pressing roller pressing spring SPb for pressing the pressing roller 47a is provided, and the fixing roller 17a and the pressing roller 47a are pressed by the pressing roller pressing spring SPb as pressing means. May be configured to be pressed. Further, a configuration may be adopted in which both spring members are provided at the same time.

According to the above, the thickness of the fixing roller member can be reduced without damaging the cylindrical elastic member due to metal fatigue caused by deformation of the cylindrical elastic member of the fixing roller member. Is suppressed.

As described above, the lower pressure roller 47
a has a metal pipe 471a of the pressure roller 47a.
A gear G12 is fixedly provided at one end of the gear G12, and the gear G22 driven and rotated by the fixing drive motor M1 is connected to the gear G12.
Then, the pressure roller 47a is driven to rotate by the driving of the fixing drive motor M1, and the fixing roller 17a pressed by the pressure 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.

In the same manner as described above, the fixing roller 17a as the fixing roller member is a thin thin elastic roller 171a having a spring property, and the resin bearing 171j holding the fixing roller 17a is pressed to press the elastic roller 171j. The pressing force of the roller 47a is received by the elastic force of the thin plate elastic roller 171a of the fixing roller 17a (as described above, the pressing roller 47a is pressed against the fixing roller 17a, and the pressing force with the pressing roller 47a is adjusted by the fixing roller 17a. 17a may be received by the elastic force of the thin elastic roller 171a having a spring property. Thereby, the thin plate elastic roller 171a
Presses the soft rubber roller layer 471b of the pressing roller 47a against the surface of the thin plate elastic roller 171a which is almost flat and spreads out in an oval shape without plastic deformation.
A wide nip N of m 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 a fixing device which is energy saving and has a short warm-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 large curvature (the radius of the curved surface is small) of the pressure roller 47a at the outlet of the nip portion N improves the separability from the recording paper P.

Also in the above-described example, the fixing roller member can be thinned without plastic deformation by the thin cylindrical elastic body, and the fixing roller member can be stably held by the bearing member. Is as wide as 5-30mm,
A fixing device with a short warm-up time can be saved with energy saving, and the thickness of the fixing roller member can be reduced without damaging the cylindrical elastic member due to metal fatigue caused by deformation of the cylindrical elastic member of the fixing roller member. In addition, the nip width is small, the nip width is wide, the warm-up time is shortened with energy saving, the deformation amount of the cylindrical elastic body is suppressed, and the uneven fixing due to the uneven rotation of the fixing roller member is prevented, and excellent fixing is performed. A fixing device becomes possible.

[0101]

According to the first to third aspects, the deformation of the central portion and the end portion of the cylindrical elastic body of the fixing roller member is prevented, and the deformation of the cylindrical elastic body is made uniform. The fixing roller member using the elastic body can be stably held, and the fixing unevenness due to the rotation unevenness of the fixing roller member is prevented, and the fixing device capable of performing satisfactory fixing can be realized.

According to the fourth or fifth aspect, the thickness of the fixing roller member can be reduced without damaging the cylindrical elastic body due to metal fatigue due to deformation of the cylindrical elastic body of the fixing roller member. A fixing device that has a small diameter and a wide nip width, saves energy, shortens the warm-up time, suppresses deformation of the cylindrical elastic body, prevents uneven fixing due to uneven rotation of the fixing roller member, and performs excellent fixing. Becomes possible.

[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.

FIG. 4 is a schematic side view of the fixing device of FIG. 3;

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

FIG. 6 is a schematic cross-sectional view of a fixing device that uses a first example of a fixing roller member supporting unit.

FIG. 7 is a schematic cross-sectional view of a fixing device using a second example of a fixing roller member supporting unit.

FIG. 8 is a schematic cross-sectional view of a fixing device using a first example of a method for preventing damage to a fixing roller member due to metal fatigue.

FIG. 9 is a schematic cross-sectional view of a fixing device using a second example of a method of preventing damage to a fixing roller member due to metal fatigue.

FIG. 10 is a schematic cross-sectional view of a fixing device using a third example of a method for preventing damage to a fixing roller member due to metal fatigue.

[Explanation of symbols]

 Reference Signs List 10 photosensitive 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 lamp B5 fixing roller bearing bearing B6 pressure roller holding bearing N nip P Recording paper LS Recess SJ Supporting part SPa Fixing roller pressing spring SPb Pressure roller pressing spring SR1 Supporting rollers ST1, ST11, ST2, ST21 Stopper

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yotaro Sato 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation F-term (reference) 2H033 AA23 AA30 BB12 BB14 BB15 BB32

Claims (5)

[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 an outer diameter of the fixing roller member, and the fixing roller member penetrates the holding member. A fixing device for supporting an end of the fixing roller member from the pressure roller member side. 2. A fixing device according to claim 1, wherein said support means is a support member provided coaxially with said pressure roller member and provided at both ends of said pressure roller member. 3. The fixing device according to claim 1, wherein the support unit is a support unit provided at a concave side end of both ends of the pressure roller member. 4. 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. And a holding member having an inner diameter larger than an outer diameter of the fixing roller member, and the fixing roller member or the pressure roller. Fixing means for pressing at least one of the members by a pressing means and providing a pressing member for preventing a distance between the fixing roller member and the pressure roller member by the pressing means from becoming less than a specified distance. apparatus. 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. And a holding member having an inner diameter larger than an outer diameter of the fixing roller member, and the fixing roller member or the pressure roller. A fixing device, wherein at least one of the members abuts on a gap maintaining unit by pressing of a pressing unit to maintain an interval between the fixing roller member and the pressing roller member.