JP2001166619A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of shotening the warming up time by accelerating the temperature rise of a belt member low in thermal conductivity, capable of fixing a toner image on the transfer material in a nip part with less fixation unevenness by eliminating the temperature change of the belt member and the nonuniformity of the temperature at the time of continuous printing, and having a high-speed adaptability. SOLUTION: A planar fixed heat generating body for heating the belt member abutting on the belt member from the inside of the belt member is arranged between a 1st fixing roller member and a heat generating roller member. The length L2 (mm) of the belt member in contact with the fixed heat generating body is defined as L2/L>=1/5 when the circumferential length of the belt member is L (mm).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a belt-type fixing device used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile.

[0002]

2. Description of the Related Art Conventionally, a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile or the like includes a heating rubber roller having an elastic layer and maintained at a predetermined temperature, and a heating rubber roller. A heat roller fixing method in which a transfer material on which an unfixed toner image is formed is heated while being nipped and conveyed by a pressurized rubber roller having an elastic layer while being pressed against the roller.

However, in this type of apparatus, the heat capacity of the heat-generating rubber roller is large, so that the warm-up time is long, the temperature inside the elastic layer is high, and the life of the heat-generating rubber roller is shortened.

Further, many color images have a large solid area, and many of the solid images are other than black, so that uneven gloss is noticeable. When a hard roller is used as the heating rubber roller and the pressure rubber roller, there is a problem that image quality is deteriorated because uneven gloss is generated in accordance with unevenness of the paper or toner layer.

In order to solve the above problems, a fixing method using a metal belt (belt member) provided with a rubber layer and a heating roller (heating roller member) for heating the belt member inside the belt member has been proposed. It is disclosed in Japanese Patent Application Laid-Open No. 9-138599.

[0006]

However, in the fixing device disclosed in Japanese Patent Application Laid-Open No. 9-138599, a good image quality is obtained by using a belt member (metal belt) having an elastic layer (rubber layer). However, the temperature rise of the belt member having poor thermal conductivity is slow due to the elastic layer, so that it takes time to warm up.
In addition, when the temperature is excessively increased, the belt member is deteriorated mainly at the interface between the elastic layer and the base of the belt member, or the fixing unevenness occurs due to the temperature change and uneven temperature of the belt member during continuous printing. The problem is that good fixability cannot be obtained. Furthermore, it is difficult for heat to move from the heat-generating roller member (heat-generating roller) included in the belt member to heat the belt member to the inside of the belt member, it takes time to conduct heat to the surface of the belt member, and high-speed printing is difficult. There is a problem that.

The present invention solves the above problems, speeds up the temperature rise of a belt member having poor thermal conductivity, shortens the warm-up time, and eliminates temperature changes and uneven temperature of the belt member during continuous printing. In addition, it is an object of the present invention to provide a fixing device that performs good fixing with little fixing unevenness when fixing a toner image on a transfer material at a nip portion and has high-speed capability.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a first fixing roller member which stretches a belt member on one side and forms a nip portion for fixing a toner image on a transfer material;
In a fixing device having a fixing roller member and a heating roller member that stretches the other side of the belt member, the belt member is disposed between the first fixing roller member and the heating roller member from the inside of the belt member. And a planar fixed heating element for heating the belt member, and a length L2 of the belt member contacting the fixed heating element.
(Mm) is achieved by the fixing device (first invention), wherein L2 / L ≧ 1/5 with respect to the circumferential length L (mm) of the belt member.

In addition, the above object is to provide a first fixing roller member which stretches a belt member on one side and forms a nip portion for fixing a toner image on a transfer material, and a first fixing roller member together with the first fixing roller member. A fixing device having a heating roller member that stretches the other side of the belt member, between the first fixing roller member and the heating roller member, abutting on the belt member from inside the belt member; A planar fixed heating element for heating the belt member is provided, and a length L2 (mm) of the belt member that contacts the fixed heating element and a length L1 (m) of the belt member that contacts the heating roller member.
m) is (L2 + L1) / L ≧ 1 / (L2 + L1) / L with respect to the circumferential length L (mm) of the belt member.
5 is achieved by a fixing device (second invention).

The above object is also achieved by a first fixing roller member which stretches a belt member on one side, a heating roller member which stretches the other side of the belt member together with the first fixing roller member, A second fixing roller member that is provided to face the first fixing roller member with a belt member interposed therebetween and that forms a nip portion with the first fixing roller member;
In a fixing device for fixing a toner image on a transfer material, between the first fixing roller member and the heat-generating roller member, a planar surface that contacts the belt member from inside the belt member and heats the belt member. And a length L2 of a belt member that comes into contact with the fixed heating element.
(Mm) is the width Ln (mm) of the nip,
This is achieved by a fixing device (third invention), wherein L2 / Ln = 2 to 20.

The above object is also achieved by a first fixing roller member which stretches a belt member on one side and forms a nip portion for fixing a toner image on a transfer material, and a first fixing roller member together with the first fixing roller member. A fixing device having a heating roller member that stretches the other side of the belt member, between the first fixing roller member and the heating roller member, abutting on the belt member from inside the belt member; A planar fixed heating element for heating the belt member is provided, and a length L2 (mm) of the belt member that contacts the fixed heating element and a length L1 (m) of the belt member that contacts the heating roller member.
m) is (L2 + L1) / Ln = 4 to 4 with respect to the width Ln (mm) of the nip portion N.
0 is achieved by a fixing device (fourth invention).

The above object is also achieved by a first fixing roller member which stretches a belt member on one side and forms a nip portion for fixing a toner image on a transfer material, and a first fixing roller member together with the first fixing roller member. A fixing device having a heating roller member that stretches the other side of the belt member, between the first fixing roller member and the heating roller member, abutting on the belt member from inside the belt member; A planar fixed heating element for heating the belt member is provided, and the length L2 (mm) of the belt member that contacts the fixed heating element is set to the length L1 (m) of the belt member that contacts the heating roller member.
m) is achieved by a fixing device (fifth invention), wherein L2 / L1 = 1.0 to 3.0.

The above object is also achieved by a first fixing roller member which stretches a belt member on one side and forms a nip portion for fixing a toner image on a transfer material, and the first fixing roller member together with the first fixing roller member. A fixing device having a heating roller member that stretches the other side of the belt member, between the first fixing roller member and the heating roller member, abutting on the belt member from inside the belt member; A fixed heating element having a planar shape for heating the belt member is provided, and a curvature radius at which the fixed heating element contacts the belt member is R (mm);
When the radius of the heating roller member is R1 (mm),
This is achieved by a fixing device (sixth invention), wherein R ≧ 5 × R1.

The object of the present invention is to provide a first fixing roller member which stretches a belt member on one side and forms a nip portion for fixing a toner image on a transfer material, and a first fixing roller member together with the first fixing roller member. A fixing device having a heating roller member that stretches the other side of the belt member, between the first fixing roller member and the heating roller member, abutting on the belt member from inside the belt member; A fixing device (seventh invention) is characterized in that a planar fixed heating element for heating the belt member is provided, and the fixed heating element acts as tension applying means for applying tension to the belt member. Is done.

The object of the present invention is to provide a first fixing roller member which stretches a belt member on one side and forms a nip portion for fixing a toner image on a transfer material, and a first fixing roller member together with the first fixing roller member. A fixing device having a heating roller member that stretches the other side of the belt member, between the first fixing roller member and the heating roller member, abutting on the belt member from inside the belt member; A fixing device (8) in which a planar fixed heating element for heating the belt member is provided, and the fixed heating element acts as a belt shift regulating unit for regulating the shift of the belt member.
Invention).

[0016]

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 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. FIG. 3 is an explanatory diagram of the structure and setting conditions of the fixing device.

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 by a power from a drive source (not shown) with the light-transmitting conductive layer grounded.

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 unit described below, and an exposure optical system 1 as an image writing unit 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 for 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. Cylindrical holding member 2
At 0, the exposure optical system 12 for each color is attached and housed inside the base of the photosensitive drum 10. In addition, as the exposure element, a linear element in which a plurality of light emitting elements such as FL (phosphor emission), 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 performs image processing on the 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 by a contact roller (not shown) with a predetermined gap, for example, 100 to 1000 μm, and is kept in contact with the rotating direction of the photosensitive drum 10. It rotates in the forward direction at the closest position, and at the time of development, an AC voltage AC is superimposed on a DC voltage of the same polarity as the toner (in this 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 formed on the photosensitive drum 10 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 that are photosensitive drum support members, and optical system flanges 120A and 120B that are exposure optical system support members that support holder 20
And are integrally formed via means such as press fitting or screws. The photosensitive drum 10 includes a drum flange 10A as a photosensitive drum support member and a drum flange 1.
0B is the bearing B1 and the bearing B respectively with respect to the shaft 121 and the optical system flange 120B integrated with the optical system flange 120A of the holder 20.
It is rotatably supported via 2.

The shaft 121 has a shaft portion 121A for holding the photosensitive drum 10, and a support shaft 130 as a shaft holding means having an engagement hole 130A is provided on the rear device board 70. The linear bearing B4 is fitted into the engagement hole 130A, and the receiving member 130
The support shaft 130 is fixed to the device substrate 70 on the rear side by screws or the like with the a 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 rear 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. The optical system flange 120C, which is a support member, is
With the front lid 120D pressed in the axial direction.
It is mounted at a predetermined position by fixing with.

A coupling 10C attached to the side surface of a drum flange 10A which is 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, and a set screw 51, the drum flange 10A and the gear G2
When the photoreceptor drum 10 having the holder 20 is integrated, the drum flange 10
A coupling 10C attached to the side of A is a drive pin 1 attached to the side of a conductive member 131 having a gear G2.
31A, and after engagement, the photoconductive drum 1 having the conductive member 131 having the gear G2 and the drum flange 10A
The drive pin 131 is set from the side of the photoreceptor drum 10 by using the set screw 51 with the center and the outer peripheral surface aligned.
A and the coupling 10C are fixed, and the drum flange 1
0A 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 , 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 by the first color signal, that is, an electric signal corresponding to Y image data is started in the Y exposure optical system 12, and the surface of the photosensitive drum 10 is rotated by the rotational scanning. An electrostatic latent image corresponding to the yellow (Y) image of the original image is formed on the photosensitive layer. 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 is performed using an electrical signal corresponding to the second color signal of m, i.e., magenta (M) image data.
Yellow (Y) by non-contact reversal development
A toner image of magenta (M) is formed on the toner image of FIG.

According to the same process, the cyan (C) toner image corresponding to the third color signal is further obtained 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), fed by a feed roller (no code), and fed 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 separated from the conveyor belt 14 a by a static electricity eliminator 14 h as a transfer material separating unit, and is conveyed to the fixing device 700.

The fixing device 700 includes a first fixing roller 17a as a first fixing roller member on one side, a heating roller 17A as a heating roller member on the other side, and a first fixing roller 17A.
A fixing belt 27A as a belt member stretched around the fixing roller 17a and the heat generating roller 17A;
A second fixing roller 17b as a second fixing roller member provided opposite to the first fixing roller 17a with A interposed therebetween;
A guide plate 173 is provided. Inside the heating roller 17A as a heating roller member, a halogen lamp HL1 or a xenon lamp (not shown) is provided as a heat ray irradiating unit for emitting heat rays such as infrared rays or far infrared rays for heating the heat generation roller 17A. A heating element unit 170 having a ceramic heater 171 as a heating element and a planar fixed heating element for heating the fixing belt 27A is provided.
The fixing belt 27A is provided in contact with (in contact with) the inside of the fixing belt 27A. A nip portion N is formed between the first fixing roller 17a and the second fixing roller 17b with the fixing belt 27A interposed therebetween. A recording paper P as a transfer material is provided below the fixing belt 27A.
Are guided to the nip portion N, and a guide plate 173 is provided for receiving the heat of the fixing belt 27A to form a preheating area.

While receiving the residual heat from the guide plate 173 and the heat from the upper fixing belt 27A, the recording paper P is conveyed by being guided by the heated guide plate 173, and the recording paper P and the toner image on the recording paper P are conveyed. Is preheated while the nip portion N between the fixing belt 27A and the second fixing roller 17b.
The recording paper P enters the nip portion N and is heated by the heat of the fixing belt 27A and pressurized by the first fixing roller 17a and the second fixing roller 17b.
The upper color toner image is fixed.

The recording paper P on which the color toner image has been fixed is fed by a paper discharge roller 18 and discharged to a tray at the top 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.

As shown in FIG. 3, a fixing device 700 includes a first fixing roller member having elasticity on one side.
A fixing roller 17a, a heating roller 17A as a heating roller member on the other side, a fixing belt 27A as a belt member stretched by the first fixing roller 17a and the heating roller 17A, and a fixing belt 27A The first fixing roller 17b includes a second fixing roller 17b as a second fixing roller member provided to face the first fixing roller 17a, and a guide plate 173.

Heat generation roller 17A as heat generation roller member
A halogen lamp HL1 and a xenon lamp (not shown) are provided inside as a heat ray irradiating means for emitting heat rays such as infrared rays or far infrared rays for heating the heat generating roller 17A.

Further, a fixing belt 27 as a belt member
A includes a ceramic heater 171 as a heating element, which contacts (contacts) the fixing belt 27A inside the fixing belt 27A on the conveyance side of the recording paper P between the heating roller 17A and the first fixing roller 17a. A heating element unit 170 as a fixed heating element having, for example, a rectangular shape and a width corresponding to the maximum transfer material size to be used is provided in a planar shape integrally formed with the heater holder 172. The heating unit 170 heats the fixing belt 27A. In this case, the ceramic heater 171 as the heating element does not necessarily need to directly contact the fixing belt 27A, and may be configured to contact the fixing belt 27A via the heater holder 172.

The heater holder 172 and the ceramic heater 171 provided on the heating element unit 170 as a planar fixed heating element have a large diameter curvature, which will be described in detail later, and come into contact (contact) with the fixing belt 27A as a belt member. ) To form a wide belt member heating area. The contact surfaces (contact surfaces) of the heater holder 172 and the ceramic heater 171 provided on the heating element unit 170 with the fixing belt 27A are provided (in the case where the ceramic heater 171 is not in direct contact with the fixing belt 27A, the heater holder 172 On the contact surface (contact surface) with the fixing belt 27A, in order to make the sliding with the fixing belt 27A good,
It is preferable to apply a fluorine coating process of about 5 to 20 μm, and the inside (inner peripheral surface) of the fixing belt 27A.
In addition, it is preferable to apply a fluorine coating process in order to improve the sliding of the fixing belt 27A.

A fixing belt 27A as a belt member
Is provided with a fixing separation claw TR3, a fixing oil cleaning roller TR1, and an oil application roller TR2 in the rotation direction of the fixing belt 27A from the position of the nip portion N, and a felt member impregnated with oil is provided by a cylindrical aluminum pipe or the like. Oil is applied to the fixing belt 27A by an oil application roller TR2 wound around a paper tube or the like. The oil on the peripheral surface of the fixing belt 27A is cleaned by the fixing oil cleaning roller TR1.

The fixing belt 27A as a belt member has a thickness of about 250 to 500 mm and a thickness of about 20 to 200 μm as a base, for example, a metal belt using a nickel electroformed belt. 30 to 3
One coated with an insulating silicon rubber of about 00 μm is used.

Heat generation roller 17A as heat generation roller member
The outer diameter is about 20-40mm and the thickness is 0.5-2m
A metal pipe made of an aluminum material and having a thickness of about 10 to 100 μm coated with a fluororesin is used on the outside (outer peripheral surface). Inside the heating roller 17A, a halogen lamp HL1 or a xenon lamp (not shown) is provided as a heat ray irradiating unit for emitting heat rays such as infrared rays or far infrared rays for heating the heating roller 17A.

Ceramic heater 171 as heating element
Is formed integrally with the heater holder 172 in a state of being in contact with or not in contact with the fixing belt 27A to form the heating element unit 170, and has a thickness of about 0.5 to 2 mm.
An alumina substrate having a width of about 0 to 80 mm (width in the moving direction of the fixing belt 27A), in which a resistance heating layer and an overcoat glass having a thickness of about 10 μm as a surface protection layer are sequentially provided by thick film printing. Is used. The ceramic heater 17 is made of overcoat glass as a surface protection layer.
1, the thermal resistance between the fixing belts 27A is reduced. The surface protective layer also functions to protect the resistance heating layer and prevent the fixing belt 27A from being worn. When the ceramic heater 171 is in contact with the fixing belt 27A, a smooth surface such as a fluorine coat is provided on at least a contact surface of the ceramic heater 171 with the fixing belt 27A.
The rotation with the fixing belt 27A is facilitated. The ceramic heater 171 as a heating element provided in the heating element unit 170 as a planar fixed heating element having a wide contact surface with the fixing belt 27A enables responsive heating of the fixing belt 27A.

The heater holder 172 for holding the ceramic heater 171 has a width of about 20 to 100 mm (width in the moving direction of the fixing belt 27A), and is formed of a metal member having good heat conductivity using, for example, aluminum or iron. A ceramic heater 171 as a heating element is provided inside, and abuts (contacts) with a fixing belt 27A as a belt member, and serves as a traveling guide for the fixing belt 27A. A smooth surface such as a fluorine coat is provided on at least the contact surface of the heater holder 172 with the fixing belt 27A to facilitate the rotation with the fixing belt 27A.

The first fixing roller 17a as the upper first fixing roller member is provided with a foamed silicone rubber layer (unsigned) on the outside (outer peripheral surface) of a core metal (unsigned) having an outer diameter of about 5 to 10 mm. It is a low-hardness sponge roller (soft roller) having an outer diameter of about 10 to 20 mm and a rubber hardness of 20 to 60 Hs (JIS, A rubber hardness).

The second fixing roller 17b serving as a second fixing roller member for pressing the first fixing roller 17a with the fixing belt 27A interposed therebetween is provided outside a cored bar (not shown) having an outer diameter of about 5 to 10 mm (not shown). Surface) with an outer diameter of 10-20 mm
And a silicone rubber layer (no sign) having a rubber hardness of 40 Hs to 80 Hs (JIS, A rubber hardness) is provided.
It is formed as a hard roller that is harder than the fixing roller 17a.

The fixing belt 27A is sandwiched between the first fixing roller 17a as a soft roller and the second fixing roller 17b as a hard roller, and the upper side has a convex shape. A relatively narrow nip N is formed. As a result, the curvature of the first fixing roller 17a on the exit side of the recording paper P in the nip portion N becomes large, and the separation of the recording paper P after fixing the toner image is performed satisfactorily.

A metal guide plate 173 using, for example, an aluminum plate or a stainless steel plate for guiding the recording paper P to the nip portion N is provided below the ceramic heater 171 and below the fixing belt 27A. As it approaches the nip N from about 5 to 15 mm of the opening on the entrance side of
The intervals gradually become narrow, and the guide plate 173 is heated by receiving heat from the fixing belt 27A heated by the heating element unit 170 in which the ceramic heater 171 is integrated,
A wide preheating area for preheating the toner image is formed between the fixing belt 27A and the fixing belt 27A.

TS1 is attached to the heat generating roller 17A and has a halogen lamp HL1 as an internal heat ray irradiating means.
A temperature sensor as a temperature detecting means using, for example, a contact-type thermistor for controlling the temperature of heating of the heat roller 17A by a heater or a xenon lamp (not shown);
TS2 is embedded in the heater holder 172 provided in the heating element unit 170 in the direction of movement of the fixing belt 27A so as to be embedded downstream of the ceramic heater 171 and is fixed. For example, a contact type thermistor for controlling the temperature of the heater 171 is a temperature sensor as a temperature detecting means using a thermistor. TS3 is a contact type for controlling the temperature attached to the lower second fixing roller 17b. Is a temperature sensor as a temperature detecting means using a thermistor, and TS4 is a temperature sensor mounted on the lower guide plate 173 as a temperature detecting means using a contact type thermistor for performing temperature control. .
As the temperature sensors TS1, TS2, TS3, and TS4, a non-contact type sensor can be used in addition to a contact type sensor.

The guide plate 173 is heated by the heat from the fixing belt 27A, which is heated by the heating unit 170 in which the ceramic heater 171 is integrated. While receiving the heat from the upper fixing belt 27A, the recording paper P is guided by the heated guide plate 173 and is conveyed.
While the toner image on the recording paper P is melted, the relatively narrow nip portion N having a width of about 5 to 15 mm between the fixing belt 27A and the second fixing roller 17b.
Then, in the nip portion N, the toner image on the recording paper P is fixed by the heating of the fixing belt 27A by the heat and the pressing by the first fixing roller 17a and the second fixing roller 17b.

By the fixing device 700 described with reference to FIG. 3, the toner image on the transfer material is previously melted by the belt member heated by the heating of the heating roller member and the fixed heating element and the heated guide plate. Is fixed at the nip, so that the warm-up time is reduced,
By the heat generating roller member using the heat ray irradiating means and the fixed heat generating element abutting (contacting) with the belt member, the temperature rise of the belt member having poor thermal conductivity is accelerated, and the warm-up time is shortened. Further, the heating by the heating roller member and the fixed heating element using the heat ray irradiating means eliminates the temperature change and the temperature non-uniformity of the belt member during the continuous printing, thereby obtaining a good fixing property with less fixing unevenness. In addition, a fixing device having high-speed capability can be provided. In the early stage of heating,
It is also necessary to raise the temperature of the first fixing roller member and the second fixing roller member in the nip portion via the belt member, and the temperature of the belt member has not reached a fixing temperature. Therefore, as described above, the fixed heating element is set to be responsive, and assists in increasing the temperature of the belt member at the beginning of heating. Even during continuous printing, even if the temperature of the belt member fluctuates due to heating by the heating roller member, the temperature of the belt member can be adjusted with good response by responsive heating by the downstream fixed heating element.

However, in order to speed up the temperature rise of the belt member having poor thermal conductivity to shorten the warm-up time, and to further prevent the belt member temperature change and the temperature non-uniformity during continuous printing, It is preferable to set the following conditions.

First, the heat capacity (Q1 (J / deg)) of the heat generating roller 17A as the heat generating roller member is determined by using the ceramic heater 171 as the heat generating element and the heater holder 17.
Heating element unit 1 as a fixed heating element integrated with 2
Preferably, the heat capacity is set to be larger than the heat capacity (Q2 (J / deg)) of 70 (Q1> Q2). Thereby, the temperature rise of the fixing belt 27A having poor thermal conductivity is accelerated, the warm-up time is shortened, and the temperature change and the temperature non-uniformity of the fixing belt 27A during the continuous printing are eliminated, so that the fixing property is good. It is possible to realize a simple fixing device.

Specifically, when the heat capacity of the heat generating roller 17A is Q1 (J / deg) and the heat capacity of the heat generating unit 170 is Q2 (J / deg), the heat capacity Q1 of the heat generating roller 17A and the heat generating unit 170 It is preferable to set the ratio Q1 / Q2 of the heat capacity Q2 to Q1 / Q2 = 1.5-10. It is preferable that the heat capacity Q1 of the heat generating roller 17A is large and the heat capacity Q2 of the heat generating unit 170 is small. The heat capacity Q1 of the heating roller 17A is
This is because a sufficient heat capacity is required to sufficiently warm the fixing belt 27A, which has a remarkable decrease in temperature after fixing. The heating roller 17A plays the role of this heat reservoir, while the heating element unit 170 plays a role of temperature control utilizing good responsiveness. When the heat capacity Q2 of the heat generating unit 170 is too large and the ratio of the heat capacity Q1 of the heat generating roller 17A to the heat capacity Q2 of the heat generating unit 170, Q1 / Q2, is less than 1.5, the heat generating unit 170 by the ceramic heater 171 is activated. The heating time becomes longer and the responsiveness is reduced. The temperature control of the fixing belt 27A becomes insufficient. Further, the heat capacity Q2 of the heat generating unit 170 is too small, and the heat capacity Q1 of the heat generating roller 17A and the heat capacity Q
If the ratio Q2 / Q2 exceeds 10, the heat capacity of the heating element unit 170 becomes insufficient, and the fixing belt 27A cannot be sufficiently heated.

By setting the above conditions in the fixing device 700 described with reference to FIG. 3, the transfer is performed by the belt member heated by the heating of the heating roller member and the fixed heating element and the heated guide plate. Since the toner image on the material is previously melted and fixed at the nip portion, the warming-up time is shortened, and the heat conductivity is poor due to the heating by the heating roller member and the fixed heating element using the heat ray irradiation means. The temperature rise of the belt member is further accelerated, and the warm-up time is further reduced. In addition, for a fixed heat generating element having a small heat capacity, a heat generating roller member having a large heat capacity on the upstream side of the nip serves as a heat reservoir, so that the temperature of the belt member during continuous printing is stabilized, and
A wide pre-heating area for pre-heating the toner image is provided at the lower part, and the fixed heating element having a small heat capacity allows the temperature of the belt member entering the nip portion to be responsively heated at the time of continuous printing. The change in the temperature of the members and the non-uniformity of the temperature are more eliminated, and a good fixing property with less fixing unevenness can be obtained, and a fixing device having high-speed capability can be provided. Further, in the initial stage of heating, the first fixing roller member and the second fixing roller member in the nip portion through the belt member are not sufficiently heated, so that the belt member does not reach a fixing temperature. Also in this case, as described above, the warming-up time can be substantially shortened by setting the fixed heating element to be responsive and assisting the belt member to raise the temperature at the initial stage of heating. In addition, during continuous printing, even if the temperature of the belt member fluctuates due to heating by the heating roller member, the temperature of the belt member at the nip can be adjusted to a constant temperature by responsive heating by the downstream fixed heating element. Further, the fixing temperature setting condition can be changed in accordance with the type of the transfer material by changing the temperature setting of the fixed heating element.

Second, the surface temperature T1 (° C.) of the heat generating roller 17A as the heat generating roller member is set as T1 ≦ T2 when the surface temperature of the heat generating unit 170 as the fixed heat generating element is T2 (° C.). Is preferred. Downstream heating element unit 1
It is preferable that a high heat supply is performed at 70 so that the front surface of the fixing belt 27A has a high temperature distribution with respect to the back surface so as to have responsiveness, and T1 ≦ T2. Normally, the surface temperature T1 of the heating roller 17A is maintained at about 150 to 180 ° C., which is the fixing temperature when the fixing temperature of thin paper or the like is low, and the surface temperature T2 of the heating element unit 170 is the surface temperature of the heating roller 17A. It is kept equal to or higher than the temperature T1.

Specifically, the ratio of the surface temperature T2 of the heating element unit 170 to the surface temperature T1 of the heating roller 17A,
It is preferable to set T2 / T1 as follows: T2 / T1 = 1.05 to 1.25. The surface temperature T2 of the heating element unit 170 is too low, and the ratio of the surface temperature T2 of the heating element unit 170 to the surface temperature T1 of the heating roller 17A, T
When 2 / T1 is less than 1.05, the heating element unit 1
No responsive control of heating of the fixing belt 27A by 70 is performed. The surface temperature T1 of the heating roller 17A is too low, and the ratio of the surface temperature T2 of the heating element unit 170 to the surface temperature T1 of the heating roller 17A, T2 / T1, is 1.2.
5, the fixing belt 27 by the heat-generating roller 17A
A is not sufficiently heated, and fixing defects such as uneven fixing occur.

By setting the above conditions in the fixing device 700 described with reference to FIG. 3, the transfer is performed by the belt member heated by the heating of the heating roller member and the fixed heating element and the heated guide plate. Since the toner image on the material is preheated (preliminary heating) and fixed at the nip portion, the warm-up time is shortened, and the belt having poor heat conductivity is heated by the heating roller member and the fixed heating element. The temperature rise of the member is faster, and the warm-up time is further reduced. In addition, the heat generating roller member serves as a heat reservoir, stabilizes the temperature of the belt member during continuous printing, and has a wide pre-heating area for pre-heating the toner image. The temperature of the belt member entering the nip during continuous printing is quickly and responsively controlled by the fixed heating element with a fast heating rate (the temperature control of the belt member is performed responsively), and the temperature change of the belt member during continuous printing In addition to eliminating unevenness in temperature and temperature, good fixing performance with less fixing unevenness is obtained,
A fixing device having high-speed capability can be provided. Further, even if the substantial heating rate of the fixed heating element is high, the temperature of the first fixing roller member and the second fixing roller member in the nip portion is not sufficiently increased via the belt member in the initial stage of heating, and the belt is not heated. The member has not reached the fixing temperature. Again,
As described above, the warming-up time can be substantially reduced by setting the temperature rising speed of the fixed heating element to be high and setting the temperature of the fixed heating element to be high to assist in increasing the temperature of the belt member at the beginning of heating. . Also, during continuous printing,
Even if the temperature of the belt member fluctuates due to the heating by the heating roller member, the responsive heating at the downstream fixed heating element allows
The temperature of the belt member at the nip portion can be adjusted to be constant. Further, the fixing temperature setting condition can be changed in accordance with the type of the transfer material by changing the temperature setting of the fixed heating element.

Third, the maximum power (W1 (W)) of a halogen lamp HL1 or a xenon lamp (not shown) as a heat ray irradiating means provided inside a heat roller 17A as a heat roller member is used as a fixed heat generator. (W1> W2) is preferably set to be larger than the maximum power (W2 (W)) of the ceramic heater 171 as a heating element provided in the heating element unit 170. The sum of the respective maximum powers that can be consumed for normal fixing, W1 + W2, is limited to about 0.8 to 1.2 kW due to use conditions as a printer function.

Halogen lamp HL as heat ray irradiation means
1 or xenon lamp (not shown)
(W)) is set to be larger than the maximum power (W2 (W)) of the ceramic heater 171 as the heating element (W1> W).
2) As a result, it is possible to supply sufficient power to the heat generating roller 17A having a role of a heat reservoir.

Specifically, when the maximum power of the halogen lamp HL1 or the xenon lamp (not shown) is W1 (W) and the maximum power of the ceramic heater 171 is W2 (W),
Maximum power W1 of halogen lamp HL1 or xenon lamp (not shown) and maximum power W2 of ceramic heater 171
It is preferable to set the ratio of W1 / W2 to W1 / W2 = 1.5 to 5. The maximum power W1 of the heating roller 17A is large, and the maximum power W of the ceramic heater 171 is large.
2 is preferably smaller. The maximum power W1 of the heating roller 17A is too small, and the ratio of the maximum power W1 of the heating roller 17A to the maximum power W2 of the ceramic heater 171 is expressed as W1 /
If W2 is less than 1.5, the heating of the heating roller 17A is insufficient, and the fixing belt 27A whose temperature has decreased after fixing is not sufficiently warmed. Also, the maximum power W2 of the ceramic heater 171 is too small, and the maximum power W1
Of the maximum power W2 of the ceramic heater 171 and W1
When / W2 exceeds 5, the ceramic heater 171 cannot sufficiently heat the fixing belt 27A with responsiveness.

As described above, the maximum power W1 (W) of the heat generating roller 17A is used as the fixed heater for the ceramic heater 1.
71 is larger than the maximum power W2 (W) (W1> W2)
In addition, it is preferable to increase the temperature of the ceramic heater 171 quickly.

Therefore, the heat capacity of the heat generating roller 17A as the heat generating roller member is Q1 (J / deg), and the heat capacity of the heat generating unit 170 as a fixed heat generating element in which the ceramic heater 171 as the heat generating element and the heater holder 172 are integrated. Is defined as Q2 (J / deg), the ratio of the maximum power W2 of the ceramic heater 171 to the heat capacity Q2 of the heating element unit 170, W2 / Q2,
It is preferable to set the ratio W1 / Q1 between the maximum power W1 of the halogen lamp HL1 and the xenon lamp (not shown) inside the lamp A and the heat capacity Q1 of the heat generating roller 17A as (W2 / Q2)> (W1 / Q1). .

That is, (W2 / Q2) is the value of the heating element unit 17 in the heating element unit 170 itself (in the state of the heating element unit 170 alone separated from the fixing belt 27A).
0, and (W1 / Q1) is the substantial heating rate of the heating roller 17A itself (in the state of the heating roller 17A alone separated from the fixing belt 27A). The substantial heating rate of the body unit 170 (W2 /
The actual temperature rise rate (W1 / Q1) of the heat generating roller 17A with respect to Q2) is increased ((W2 / Q2)> (W1 / Q)
1)) It is preferable to set.

Specifically, it is preferable to set (W2 / Q2) / (W1 / Q1) = 2-7. Originally heating element unit 170
Of the heat generating roller 17A, the substantial temperature increasing speed (W1 / Q1) of the heat generating roller 17A is increased.
A slows down. The substantial heating rate (W2 / Q2) of the heating element unit 170 is slow (small), and the substantial heating rate (W2 / Q2) of the heating element unit 170 and the substantial heating of the heating roller 17A. The ratio to the speed (W1 / Q1), (W2 / Q2) / (W1 / Q1), is preferably 2 or more in view of the responsiveness of the substantial heating rate of the fixing belt 27A in the heating element unit 170. In addition, the substantial temperature increase rate (W1 / Q1) of the heat generating roller 17A is slow (small), and the substantial temperature increase rate (W2
/ Q2) and the substantial temperature increase rate (W1
/ Q1) and (W2 / Q2) / (W1 / Q1) is 7
When the temperature exceeds the setting, the temperature rise of the fixing belt 27A becomes faster, but the heat capacity Q2 of the heating element unit 170 with respect to the fixing belt 27A becomes too small, and the fixing belt 27A
Temperature becomes unstable. Further, even if the speed is excessively high, it is not effective because there is time for heat conduction from the back surface to the front surface of the fixing belt 27A, and a value of 7 or less is sufficient.

By setting the above conditions in the fixing device 700 described with reference to FIG. 3, the transfer is performed by the belt member heated by the heating of the heating roller member and the fixed heating element and the heated guide plate. Since the toner image on the material is preheated (preliminary heating) and fixed at the nip portion, the warm-up time is shortened, and the belt having poor heat conductivity is heated by the heating roller member and the fixed heating element. The temperature rise of the member is faster, and the warm-up time is further reduced. In addition, for a fixed heating element with small heat capacity and maximum power, a heat roller member that increases heat capacity and maximum power on the upstream side of the nip serves as a heat reservoir, stabilizing the temperature of the belt member during continuous printing. Has a wide pre-heating area for pre-heating the toner image, and the temperature of the belt member that enters the nip during continuous printing is quickly (The temperature control of the belt member is performed with good response), and the temperature change and the temperature non-uniformity of the belt member at the time of continuous printing are further eliminated, so that good fixing performance with less fixing unevenness can be obtained, and high speed printing can be achieved. A fixing device having compatibility can be provided. Further, even if the substantial heating rate of the fixed heating element is high, the temperature of the first fixing roller member and the second fixing roller member in the nip portion is not sufficiently increased via the belt member in the initial stage of heating, and the belt is not heated. The member has not reached the fixing temperature. In this case, as described above, the warming-up time is substantially reduced by setting the heating rate of the fixed heating element to be high and setting the temperature of the fixed heating element to be high to assist the heating of the belt member at the beginning of heating. Can be shortened. In addition, during continuous printing, even if the temperature of the belt member fluctuates due to heating by the heating roller member, the temperature of the belt member at the nip can be adjusted to a constant temperature by responsive heating by the downstream fixed heating element. Further, the fixing temperature setting condition can be changed in accordance with the type of the transfer material by changing the temperature setting of the fixed heating element.

Fourth, the setting of the second substantial heating rate is defined, and the halogen lamp HL as a heat ray irradiating means provided inside the heat generating roller 17A is provided.
1 and a heating roller 17A alone as a heating roller member heated by a xenon lamp (not shown) (fixing belt 2
The heating rate (S1 (deg) at the fixing belt 27A contact surface position in the state of the heating roller 17A alone separated from the fixing roller 7A.
/ Sec)), the heating element unit 170 alone as the fixed heating element in which the ceramic heater 171 as the heating element and the heater holder 172 are integrated (the fixing belt 2).
In the state of the heating element unit 170 alone separated from 7A,
The temperature rising speed (S2 (d) at the fixing belt 27A contact surface position)
eg / sec)) is preferably set faster.

More specifically, the heating rate S is determined by the time Δt (se
c) is determined by the temperature rise temperature ΔT (°) (S = ΔT / Δt), the rate of temperature rise of the heating roller 17A as a heating roller member is S1 (deg / sec), and the heating element unit 170 as a fixed heating element. The temperature rise rate of S2 (deg / s
When ec), it is preferable to set S2 / S1 = 2 to 7. Originally heating element unit 170
The temperature rise speed S2 of the heat roller 17A is made quicker while the temperature rise speed S1 of the heat roller 17A is reduced by the heat roller 17A having a large heat capacity Q1. Heating element unit 170
Of the heating element unit 170 and the heating rate S2 of the heating roller 17A are slow (small).
The ratio S2 / S1 to 1 is preferably 2 or more because the responsiveness of the heating rate of the fixing belt 27A in the heating element unit 170 is lost. Further, the temperature rise speed S1 of the heat generating roller 17A is slow (small) and the heat generating unit 170
When the ratio S2 / S1 of the temperature rising speed S2 of the heat roller 17A to the temperature rising speed S2 of the heating roller 17A exceeds 7, the fixing belt 27
Even if the temperature rise of A is fast, the heat capacity Q1 of the heat generating roller 17A with respect to the fixing belt 27A is too small, and the temperature of the fixing belt 27A becomes unstable. Further, even if the speed is excessively high, it is not effective because there is time for heat conduction from the back surface to the front surface of the fixing belt 27A, and a value of 7 or less is sufficient.

By setting the above conditions in the fixing device 700 described with reference to FIG. 3, the transfer is performed by the belt member heated by the heating of the heating roller member and the fixed heating element and the heated guide plate. Since the toner image on the material is pre-heated and fixed at the nip, the warm-up time is shortened, and the temperature of the belt member having poor thermal conductivity is increased by the heating of the heating roller member and the fixed heating element. Is faster and the warm-up time is shorter. Further, the heat generating roller member on the upstream side of the nip portion having a low temperature rising rate acts as a heat reservoir with respect to the fixed heating element having a high temperature rising rate, so that the temperature of the belt member during continuous printing is stabilized. At the same time, the temperature of the belt member entering the nip portion during continuous printing is quickly and responsively controlled by the fixed heating element having a high temperature rising speed (the temperature control of the belt member is performed with good response), and the belt member during continuous printing is heated. Temperature changes and temperature non-uniformity are further eliminated, and a good fixing performance with less fixing unevenness can be obtained, and a fixing device having high-speed capability can be provided. Further, since the fixed heating element has a wide preheating area for preheating the toner image, heating of the belt member is easy, and temperature control is facilitated by increasing the temperature rising speed of the fixed heating element. . Further, even if the heating rate of the fixed heating element is high, the temperature of the first fixing roller member and the second fixing roller member in the nip portion is not sufficiently increased via the belt member at the initial stage of heating, and the belt member is not fixed. Not at a possible temperature. Also in this case, as described above, the warming-up time is increased by setting the heating rate of the fixed heating element to be high and by setting the temperature of the fixed heating element to be high to assist in increasing the temperature of the belt member at the beginning of heating. Can be substantially reduced. In addition, during continuous printing, even if the temperature of the belt member fluctuates due to heating by the heating roller member, the temperature of the belt member at the nip can be adjusted to a constant temperature by responsive heating by the downstream fixed heating element. Further, the fixing temperature setting condition can be changed in accordance with the type of the transfer material by changing the temperature setting of the fixed heating element.

Further, since a rubber member is used, the temperature of the belt member having poor thermal conductivity is increased more quickly, the warm-up time is further reduced, and the temperature change and the temperature non-uniformity of the belt member during continuous printing are reduced. In order to further prevent this, it is preferable to set the dimensional relationship described below with reference to FIGS. 4 to 8 in the fixing device described with reference to FIG. FIG. 4 shows the dimensional relationship between the circumference of the belt member and the length of the fixed heating element that contacts the belt member, and the circumference of the belt member, and the length of the fixed heating element and the heating roller member that contacts the belt member. FIG. 5 is an explanatory diagram of a dimensional relationship with the sum of
Is the dimensional relationship between the width of the nip and the length of the fixed heating element that contacts the belt member, and the sum of the width of the nip and the length of the fixed heating element and the length of the heating roller member that contacts the belt member. FIG. 6 is an explanatory diagram of a dimensional relationship, and FIG. 6 is an explanatory diagram of a dimensional relationship between a length of a fixed heating element that contacts a belt member and a length of a heating roller member that contacts the belt member.
FIG. 8 is an explanatory view of a dimensional relationship when a plurality of fixed heating elements in FIGS. 4 to 6 are provided, and FIG. 8 is a dimensional relationship between a radius of curvature of a fixed heating element that contacts a belt member and a radius of a heating roller member; FIG. 9 is an explanatory diagram of a dimensional relationship between a radius of curvature of a fixed heating element that contacts a belt member and a contact length of a fixed heating element that contacts the belt member.

As shown in FIG. 4, the fixing device 700 includes a first elastic member on one side, as described with reference to FIG.
A first fixing roller 17a as a fixing roller member, and a heat roller 17A as a heat roller member on the other side
A fixing belt 27A as a belt member stretched by the first fixing roller 17a and the heat generating roller 17A; It is composed of two fixing rollers 17b and a guide plate 173.

Heat generation roller 17A as heat generation roller member
A halogen lamp HL1 and a xenon lamp (not shown) are provided inside as a heat ray irradiating means for emitting heat rays such as infrared rays or far infrared rays for heating the heat generating roller 17A.

Further, a fixing belt 27 as a belt member
A includes a ceramic heater 171 as a heating element, which contacts (contacts) the fixing belt 27A inside the fixing belt 27A on the conveyance side of the recording paper P between the heating roller 17A and the first fixing roller 17a. A heating element unit 170 as a fixed heating element, for example, having a width corresponding to the maximum transfer material size to be used and having a planar shape integrally formed with the heater holder 172 is provided, and the fixing unit 27A is heated by the heating element unit 170. I do. In this case, the ceramic heater 171 as the heating element does not necessarily need to directly contact the fixing belt 27A, and may be configured to contact the fixing belt 27A via the heater holder 172.

The first fixing roller 17a as a soft roller and the second fixing roller 17b as a hard roller sandwich the fixing belt 27A so that the upper side has a convex shape.
A relatively narrow nip portion N of about 15 mm is formed.

The guide plate 173 is heated by the heat from the fixing belt 27A which is heated by the heating element unit 170 in which the ceramic heater 171 is integrated. While receiving the heat from the upper fixing belt 27A, the recording paper P is guided by the heated guide plate 173 and is conveyed.
While the toner image on the recording paper P is melted, the relatively narrow nip portion N having a width of about 5 to 15 mm between the fixing belt 27A and the second fixing roller 17b.
Then, in the nip portion N, the toner image on the recording paper P is fixed by the heating of the fixing belt 27A by the heat and the pressing by the first fixing roller 17a and the second fixing roller 17b.

The fixing belt 27A as a belt member has an inner diameter of 250 to 500 as a base.
Outside (outer peripheral surface) of a metal belt having a thickness of about 20 mm to about 200 μm and using, for example, a nickel electroformed belt.
Is coated with an insulating silicon rubber having a thickness of about 30 to 300 μm, and the circumference L (m) of the fixing belt 27A is used.
m) is approximately the same as the inner diameter of the substrate, that is, about 250 to 500 mm.

A ceramic heater 1 as a heating element
The heating element unit 170 as a planar fixed heating element, in which the heating element 71 and the heater holder 172 are integrated,
7A and the first fixing roller 17a, on the conveyance side of the recording paper P, from the inside of the fixing belt 27A, a width of 20 to 100 mm.
It contacts (contacts) the fixing belt 27A with a contact length (contact width) L2 (mm) of a degree (width in the moving direction of the fixing belt 27A).

The heat roller 17A as a heat roller member on which the fixing belt 27A is stretched on one side is a metal pipe made of an aluminum material having an outer diameter of about 20 to 40 mm and a thickness of about 0.5 to 2 mm. Outside (outer peripheral surface), thickness 1
Using a coating of about 0 to 100 μm fluororesin, a length of 30 to 80
With a contact length (contact width) L1 (mm) of about mm,
It contacts the fixing belt 27A.

As described above with reference to FIG. 3, the surface temperature T1 of the heat generating roller 17A is usually maintained at about 150 to 180 ° C., which is the fixing temperature when the fixing temperature of thin paper or the like is low. The surface temperature T2 of the body unit 170 is kept equal to or higher than the surface temperature T1 of the heating roller 17A.

The length L2 (mm) of the fixing belt 27A in contact with the heating element unit 170 (the contact length (contact width) L2 (m) between the fixing belt 27A and the heating element unit 170
m)) is preferably set to L2 / L ≧ １ ／ with respect to the circumferential length L (mm) of the fixing belt 27A. It is preferable that the ratio L2 / L is set to 1/5 or more, and the fixed heating element unit 170 is used to contact the fixing belt 27A over a wide area (wide). When the ratio L2 / L is less than 1/5, the heating element unit 17
Responsive temperature control by 0 becomes difficult. Further, since the heat roller 17A is present, contact with the whole area is difficult, and the ratio L2 / L is set to 3/5 or less (L2 / L <3/5). As will be described later with reference to FIG. 7, it is also possible to increase the contact width with the fixing belt 27A by using a plurality of fixed heating elements.

Further, the length L2 (mm) of the fixing belt 27A that comes into contact with the heating element unit 170 (the fixing belt 27A
Length (contact width) L2 between the heater and the heating element unit 170
(Mm)) and the length L1 (mm) of the fixing belt 27A in contact with the heating roller 17A (the contact length (contact width) L1 (mm) between the fixing belt 27A and the heating roller 17A) (L2 + L1). (Mm) is preferably set to (L2 + L1) / L ≧ １ ／ with respect to the peripheral length L (mm) of the fixing belt 27A. The ratio (L2 + L1) / L is
Heating unit 170 and heating roller 1
It is preferable to use 7A and the fixing belt 27A in a wide area (wide). The ratio (L2 + L1) / L is 1
If it is less than / 5, it is difficult to respond quickly by the heating element unit 170 and to control the temperature of the heating roller 17A as a heat reservoir. Further, since the heating roller 17A is also provided, contact can be made in almost the entire area, and the ratio (L2 + L1) / L is reduced to 4/5.
Hereinafter, ((L2 + L1) / L <4/5). As will be described later with reference to FIG. 7, it is also possible to increase the contact width with the fixing belt 27A by using a plurality of fixed heating elements.

By setting the above dimensional relationship, the temperature rise of the belt member having poor thermal conductivity due to the use of the rubber member is further accelerated, the warm-up time is further shortened, and the temperature of the belt member during continuous printing is reduced. Changes and non-uniformity in temperature are further prevented.

Further, as shown in FIG.
Is a first fixing roller 17a as a first fixing roller member having elasticity on one side, as described with reference to FIG.
And a heating roller 17A as a heating roller member on the other side, a first fixing roller 17a and a heating roller 17A.
Belt 27A as a belt member stretched by
And a second fixing roller 17b as a second fixing roller member provided to face the first fixing roller 17a with the fixing belt 27A interposed therebetween, and a guide plate 173.

Heating roller 17A as heating roller member
A halogen lamp HL1 and a xenon lamp (not shown) are provided inside as a heat ray irradiating means for emitting heat rays such as infrared rays or far infrared rays for heating the heat generating roller 17A.

Further, a fixing belt 27 as a belt member
A includes a ceramic heater 171 as a heating element, which contacts (contacts) the fixing belt 27A inside the fixing belt 27A on the conveyance side of the recording paper P between the heating roller 17A and the first fixing roller 17a. A heating element unit 170 as a fixed heating element, for example, having a width corresponding to the maximum transfer material size to be used and having a planar shape integrally formed with the heater holder 172 is provided, and the fixing unit 27A is heated by the heating element unit 170. I do. In this case, the ceramic heater 171 as the heating element does not necessarily need to directly contact the fixing belt 27A, and may be configured to contact the fixing belt 27A via the heater holder 172.

The upper side is convex between the first fixing roller 17a as a soft roller and the second fixing roller 17b as a hard roller with the fixing belt 27A interposed therebetween.
A relatively narrow nip portion N of about 15 mm is formed.

The guide plate 173 is heated by the heat from the fixing belt 27A which is heated by the heating element unit 170 in which the ceramic heater 171 is integrated. While receiving the heat from the upper fixing belt 27A, the recording paper P is guided by the heated guide plate 173 and is conveyed.
While the toner image on the recording paper P is melted, the relatively narrow nip portion N having a width of about 5 to 15 mm between the fixing belt 27A and the second fixing roller 17b.
Then, in the nip portion N, the toner image on the recording paper P is fixed by the heating of the fixing belt 27A by the heat and the pressing by the first fixing roller 17a and the second fixing roller 17b.

The fixing belt 27A as a belt member has an inner diameter of 250 to 500 as a base.
Outside (outer peripheral surface) of a metal belt having a thickness of about 20 mm to about 200 μm and using, for example, a nickel electroformed belt.
Which is coated with an insulating silicon rubber having a thickness of about 30 to 300 μm.

The ceramic heater 1 as a heating element
The heating element unit 170 as a planar fixed heating element, in which the heating element 71 and the heater holder 172 are integrated,
7A and the first fixing roller 17a, on the conveyance side of the recording paper P, from the inside of the fixing belt 27A, a width of 20 to 100 mm.
It contacts (contacts) the fixing belt 27A with a contact length (contact width) L2 (mm) of a degree (width in the moving direction of the fixing belt 27A).

The heat roller 17A as a heat roller member on which the fixing belt 27A is stretched on one side is a metal pipe made of an aluminum material having an outer diameter of about 20 to 40 mm and a thickness of about 0.5 to 2 mm. Outside (outer peripheral surface), thickness 1
Using a coating of about 0 to 100 μm fluororesin, a length of 30 to 80
With a contact length (contact width) L1 (mm) of about mm,
It contacts the fixing belt 27A.

As described above, the first fixing roller 17a as a soft roller and the second fixing roller 17b as a hard roller are sandwiched between the fixing belt 27A and the fixing belt 27A.
The width Ln (m
m) is about 5 to 15 mm.

As described above with reference to FIG. 3, the surface temperature T1 of the heat generating roller 17A is normally maintained at about 150 to 180.degree. The surface temperature T2 of the body unit 170 is kept equal to or higher than the surface temperature T1 of the heating roller 17A.

The length L2 (mm) of the fixing belt 27A in contact with the heating element unit 170 (the contact length (contact width) L2 (m) of the fixing belt 27A and the heating element unit 170
m)) is preferably set in the range of L2 / Ln = 2 to 20 with respect to the width Ln (mm) of the nip portion N. A contact area wider than the width of the nip portion N is defined between the heating roller 17A and the nip portion N (between the heating roller 17A and the first fixing roller 17a).
The fixing belt 27A made of a rubber member having no heat resistance can be secured in the belt member heating area by the heating element unit 170 upstream in the rotation direction of the fixing belt 27A.
Is sufficiently heated at a low temperature, and the nip portion N having a width Ln (mm) of about 5 to 15 mm so that the temperature of the fixing belt 27A made of a rubber member having a low thermal conductivity is sufficiently uniform including the surface. In contrast, the ratio L2 / Ln is set to 2 or more and 20 or less (L2 / Ln = 2 to 20). As will be described later with reference to FIG. 7, it is also possible to increase the contact width with the fixing belt 27A by using a plurality of fixed heating elements.

The length L2 (mm) of the fixing belt 27A (the fixing belt 27A)
Length (contact width) L2 between the heater and the heating element unit 170
(Mm)) and the length L1 (mm) of the fixing belt 27A in contact with the heating roller 17A (the contact length (contact width) L1 (mm) between the fixing belt 27A and the heating roller 17A) (L2 + L1). (Mm) is the width Ln (m) of the nip N
It is preferable to set (L2 + L1) / Ln = 10 to 40 with respect to m). By expanding the contact area wider than the width of the nip portion N with the heating element unit 170 and the heating roller 17A, the fixing belt 27A made of a rubber member having no heat resistance is sufficiently heated at a low temperature, and the thermal conductivity is increased. The width Ln is adjusted so that the temperature of the fixing belt 27A made of a rubber member having a poor
(Mm) is about 5 to 15 mm.
The ratio (L2 + L1) / Ln is 4 or more and 40 or less (L2 / L
n = 4 to 40). As will be described later with reference to FIG. 7, it is also possible to increase the contact width with the fixing belt 27A by using a plurality of fixed heating elements.

By setting the above dimensional relationship, the temperature of the belt member having a poor thermal conductivity is increased more quickly because the rubber member is used, the warm-up time is further shortened, and the temperature of the belt member during continuous printing is reduced. Changes and non-uniformity in temperature are further prevented.

Further, as shown in FIG.
Is a first fixing roller 17a as a first fixing roller member having elasticity on one side, as described with reference to FIG.
And a heating roller 17A as a heating roller member on the other side, a first fixing roller 17a and a heating roller 17A.
Belt 27A as a belt member stretched by
And a second fixing roller 17b as a second fixing roller member provided to face the first fixing roller 17a with the fixing belt 27A interposed therebetween, and a guide plate 173.

Heating roller 17A as heating roller member
A halogen lamp HL1 and a xenon lamp (not shown) are provided inside as a heat ray irradiating means for emitting heat rays such as infrared rays or far infrared rays for heating the heat generating roller 17A.

A fixing belt 27 as a belt member
A includes a ceramic heater 171 as a heating element, which contacts (contacts) the fixing belt 27A inside the fixing belt 27A on the conveyance side of the recording paper P between the heating roller 17A and the first fixing roller 17a. A heating element unit 170 as a fixed heating element, for example, having a width corresponding to the maximum transfer material size to be used and having a planar shape integrally formed with the heater holder 172 is provided, and the fixing unit 27A is heated by the heating element unit 170. I do. In this case, the ceramic heater 171 as the heating element does not necessarily need to directly contact the fixing belt 27A, and may be configured to contact the fixing belt 27A via the heater holder 172.

The first fixing roller 17a as a soft roller and the second fixing roller 17b as a hard roller sandwich the fixing belt 27A so that the upper side has a convex shape.
A relatively narrow nip portion N of about 15 mm is formed.

The guide plate 173 is heated by the heat from the fixing belt 27A which is heated by the heating unit 170 having the ceramic heater 171 integrated therewith. While receiving the heat from the upper fixing belt 27A, the recording paper P is guided by the heated guide plate 173 and is conveyed.
While the toner image on the recording paper P is melted, the relatively narrow nip portion N having a width of about 5 to 15 mm between the fixing belt 27A and the second fixing roller 17b.
Then, in the nip portion N, the toner image on the recording paper P is fixed by the heating of the fixing belt 27A by the heat and the pressing by the first fixing roller 17a and the second fixing roller 17b.

The fixing belt 27A as a belt member has an inner diameter of 250 to 500 as a base.
Outside (outer peripheral surface) of a metal belt having a thickness of about 20 mm to about 200 μm and using, for example, a nickel electroformed belt.
Which is coated with an insulating silicon rubber having a thickness of about 30 to 300 μm.

Further, the ceramic heater 1 as a heating element
The heating element unit 170 as a planar fixed heating element, in which the heating element 71 and the heater holder 172 are integrated,
7A and the first fixing roller 17a, on the conveyance side of the recording paper P, from the inside of the fixing belt 27A, a width of 20 to 100 mm.
It contacts (contacts) the fixing belt 27A with a contact length (contact width) L2 (mm) of a degree (width in the moving direction of the fixing belt 27A).

The heat roller 17A as a heat roller member on which the fixing belt 27A is stretched on one side is a metal pipe made of an aluminum material having an outer diameter of about 20 to 40 mm and a thickness of about 0.5 to 2 mm. Outside (outer peripheral surface), thickness 1
Using a coating of about 0 to 100 μm fluororesin, a length of 30 to 80
With a contact length (contact width) L1 (mm) of about mm,
It contacts the fixing belt 27A.

As described above with reference to FIG. 3, the surface temperature T1 of the heat generating roller 17A is normally maintained at about 150 to 180 ° C., which is the fixing temperature when the fixing temperature of thin paper or the like is low. The surface temperature T2 of the body unit 170 is kept equal to or higher than the surface temperature T1 of the heating roller 17A.

The length L2 (mm) of the fixing belt 27A in contact with the heating element unit 170 (the contact length (contact width) L2 (m) between the fixing belt 27A and the heating element unit 170
m)) is a fixing belt 27 that contacts the heat generating roller 17A.
It is possible to set L2 / L1 = 1.0 to 3.0 with respect to the length L1 (mm) of A (the contact length (contact width) L1 (mm) between the fixing belt 27A and the heat generating roller 17A). preferable. Fixed heating element unit 1
It is preferable that the heating unit 70 is used to contact the fixing belt 27A in a wide area (wide range) in order to enable responsive temperature control of the fixing belt 27A by the heating element unit 170, and that the ratio L2 / L1 is 1.0 or more. And In order to ensure the function of the heat roller 17A as a heat reservoir, the ratio L2 / L1 is set to 3.0 or less. As will be described later with reference to FIG. 7, it is also possible to increase the contact width with the fixing belt 27A by using a plurality of fixed heating elements.

By setting the above dimensional relationship, the temperature rise of the belt member having poor thermal conductivity due to the use of the rubber member is accelerated, the warm-up time is further shortened, and the temperature of the belt member during continuous printing is reduced. Changes and non-uniformity in temperature are further prevented.

FIG. 7 shows a case where a plurality of planar fixed heating elements shown in FIGS. 4 to 6 are provided.
6, in the rotation direction of the fixing belt 27A and on the downstream side of the heating roller 17A, the fixing belt 2
7A, a heating element unit 170A as a planar fixed heating element is provided, and a heating element unit 170B as a planar fixed heating element shown by a dashed line in FIG.
Is provided in the rotation direction of the fixing belt 27A, on the upstream side of the heat generating roller 17A, in contact with the fixing belt 27A. Heating element units 170A and 170B as planar fixed heating elements
Is similar to that described with reference to FIG. 3, and a ceramic heater 171 as a heating element and a heater holder 172 are integrally formed.

The length of the fixing belt 27A in contact with the heating element unit 170A is L21 (mm) (the fixing belt 27A
The contact length (contact width) between the heating element 170 and the heating element unit 170 is L2
1 (mm)), the length of the fixing belt 27A in contact with the heating element unit 170B is set to L22 (mm) (the fixing belt 27).
The contact length (contact width) between A and the heating element unit 170 is L
22 (mm), the length L2 (mm) (fixing belt 2) of the fixing belt 27A that is in contact with the heating element unit 170 as the fixed heating element described with reference to FIGS.
Contact length (contact width) L between 7A and heating element unit 170
2 (mm)) is defined as L2 = L21 + L22, and the contact length (contact width) of the fixed heating element with the fixing belt 27A in FIGS. 4 to 6 is the same as that described above with reference to FIGS. Set the relationship. By using a plurality of fixed heating elements, the fixing belt 27 can be spread over a wider area (wider).
A, and the belt member heating area is greatly expanded. Therefore, in this case, the heating roller 17 as a heating roller member is used.
Halogen lamp HL as a heating element provided inside A
It is not necessary to generate heat from the xenon lamp 1 or a xenon lamp (not shown). Further, the heat capacity of the heat roller 17A can be reduced.

The length L2 (L2 = L21 +) of the fixing belt 27A in contact with the heating element units 170A and 170B.
L22) (mm) (contact length (contact width) between fixing belt 27A and heating element units 170A, 170B) L2 (L2)
= L21 + L22) (mm)) is the length L1 (mm) of the fixing belt 27A in contact with the heating roller 17A (the contact length (contact width) between the fixing belt 27A and the heating roller 17A).
L1 (mm)) is preferably set to L2 / L1 = 2.0 to 5.0. In order to reduce the heat capacity of the heat generating roller 17A by reducing the diameter of the heat generating roller 17A as much as possible, and to increase the contact width of the fixed heat generating element with the belt member, the ratio L2 / L1 is set to 2.0 or more and 5.0 or less. (L2 / L1 = 2.0 to 5.0). Heating roller 1
If the outer diameter of 7A is too small, the heat generating roller 17A will be deformed. Further, if the outer diameter of the heat roller 17A is too small, the halogen lamp HL1 or the xenon lamp (not shown) as a heat element cannot be provided inside the heat roller 17A. In order to ensure the function of the heat generating roller 17A as a heat reservoir, the ratio L2 / L1 is set to 5.0 or less. Further, by using a plurality of fixed heating element units 170A and 170B to contact the fixing belt 27A in a wide area (wide), it is possible to control the temperature of the fixing belt 27A responsively by the heating element units 170A and 170B. It is preferable to set the ratio L2 / L1 to 2.0 or more.

As described above, since the rubber member is used, the temperature rise of the belt member having poor thermal conductivity is further accelerated, the warm-up time is further shortened, and the temperature change and the temperature change of the belt member at the time of continuous printing. Non-uniformity is further prevented.

Further, as shown in FIG.
Is a first fixing roller 17a as a first fixing roller member having elasticity on one side, as described with reference to FIG.
And a heating roller 17A as a heating roller member on the other side, a first fixing roller 17a and a heating roller 17A.
Belt 27A as a belt member stretched by
And a second fixing roller 17b as a second fixing roller member provided to face the first fixing roller 17a with the fixing belt 27A interposed therebetween, and a guide plate 173.

Heating Roller 17A as Heating Roller Member
A halogen lamp HL1 and a xenon lamp (not shown) are provided inside as a heat ray irradiating means for emitting heat rays such as infrared rays or far infrared rays for heating the heat generating roller 17A.

A fixing belt 27 as a belt member
A includes a ceramic heater 171 as a heating element, which contacts (contacts) the fixing belt 27A inside the fixing belt 27A on the conveyance side of the recording paper P between the heating roller 17A and the first fixing roller 17a. A heating element unit 170 as a fixed heating element, for example, having a width corresponding to the maximum transfer material size to be used and having a planar shape integrally formed with the heater holder 172 is provided, and the fixing unit 27A is heated by the heating element unit 170. I do. In this case, the ceramic heater 171 as the heating element does not necessarily need to directly contact the fixing belt 27A, and may be configured to contact the fixing belt 27A via the heater holder 172.

The first fixing roller 17a as a soft roller and the second fixing roller 17b as a hard roller sandwich the fixing belt 27A so that the upper side has a convex shape.
A relatively narrow nip portion N of about 15 mm is formed.

The guide plate 173 is heated by the heat from the fixing belt 27A which is heated by the heating unit 170 having the ceramic heater 171 integrated therewith. While receiving the heat from the upper fixing belt 27A, the recording paper P is guided by the heated guide plate 173 and is conveyed.
While the toner image on the recording paper P is melted, the relatively narrow nip portion N having a width of about 5 to 15 mm between the fixing belt 27A and the second fixing roller 17b.
Then, in the nip portion N, the toner image on the recording paper P is fixed by the heating of the fixing belt 27A by the heat and the pressing by the first fixing roller 17a and the second fixing roller 17b.

In the above, the fixing belt 27A as a belt member has an inner diameter of 250 to 500 as a base.
Outside (outer peripheral surface) of a metal belt having a thickness of about 20 mm to about 200 μm and using, for example, a nickel electroformed belt.
Which is coated with an insulating silicon rubber having a thickness of about 30 to 300 μm.

The ceramic heater 1 as a heating element
The heating element unit 170 as a planar fixed heating element, in which the heating element 71 and the heater holder 172 are integrated,
7A and the first fixing roller 17a, on the conveyance side of the recording paper P, from the inside of the fixing belt 27A, a width of 20 to 100 mm.
It contacts (contacts) the fixing belt 27A with a contact length (contact width) L2 (mm) of a degree (width in the moving direction of the fixing belt 27A).

The upper limit of the heater holder 172 and the ceramic heater 171 provided on the heating element unit 170 as a planar fixed heating element is 1000 mm (R ≦ 1000 m).
With a radius of curvature R of m), the belt contacts (contacts) the fixing belt 27A as a belt member to form a wide belt member heating region.

The heating roller 17A as a heating roller member that stretches the fixing belt 27A on one side has a radius R1 (mm) of about 10 to 20 mm (outer diameter of 20 to 40 mm).
mm) and a thickness of about 10 to 1 mm on the outside (outer peripheral surface) of a metal pipe using an aluminum material having a thickness of about 0.5 to 2 mm.
One coated with a fluororesin of about 00 μm is used.

As described above with reference to FIG. 3, the surface temperature T1 of the heat generating roller 17A is normally maintained at about 150 to 180 ° C., which is the fixing temperature when the fixing temperature of thin paper or the like is low. The surface temperature T2 of the body unit 170 is kept equal to or higher than the surface temperature T1 of the heating roller 17A.

In the above description, the fixing belt 27A has a wide contact width with the heating element unit 170, and the fixing belt 27A moves while sliding against the heating element unit 170 without floating. R1 (mm) is 1
For the heating roller 17A of about 0 to 20 mm, the lower limit of the radius of curvature R (mm) at which the heating element unit 170 comes into contact with the fixing belt 27A is R (mm) at which the heating element unit 170 comes into contact with the fixing belt 27A. mm) and the radius of the heat generating roller 17A is R1 (mm), it is preferable that R ≧ 5 × R1. If the radius of curvature R of the heating element unit 170 is less than five times the radius R1 of the heating roller 17A, the contact surface becomes deep, and the fixing belt 27A does not slide. Further, the contact width is short and the heat conduction becomes insufficient.

Second, the upper limit of the radius of curvature R (mm) at which the heating element unit 170 contacts the fixing belt 27A is 10
It is preferable that the thickness be not more than 00 mm (R ≦ 1000 mm). The radius of curvature R of the heating element unit 170 is 1000 mm
Larger than the contact belt, the contact surface becomes shallow and the fixing belt 27
Since A easily floats, heat conduction becomes insufficient.

It is preferable that the fixed heating element unit 170 be used to contact the fixing belt 27A in a wide area (wide) so that the heating element unit 170 can control the fixing belt 27A in a responsive manner. , Width 2
The fixing belt 27 of the heating element unit 170 that contacts (contacts) the fixing belt 27A with about 0 to 100 mm.
A contact length (contact width) L2 (mm) of (the width in the moving direction of the fixing belt 27A) with the heating roller 17A is substantially equal to the contact length of the heating roller 17A with the fixing belt 27A.
It is preferable to set the contact width (L2 ≧ πR1) to be wider than the half circumference πR1.

By setting the above-mentioned dimensional relationship, the temperature of the belt member having poor thermal conductivity due to the use of the rubber member is increased more quickly, the warm-up time is further shortened, and the temperature of the belt member during continuous printing is reduced. Changes and non-uniformity in temperature are further prevented.

Further, as a means for imparting tension to the belt member, the fixed heating element of the fixing device described with reference to FIG. 3 is used to prevent the belt member from shifting and to improve the adhesion of the fixed heating element to the belt member. The configuration for securing the belt and the configuration using the fixed heating element of the fixing device described with reference to FIG. 3 as the belt deviation regulating means for preventing the deviation of the belt member will be described with reference to FIGS. 9 to 11. FIG.
FIG. 10 is a schematic explanatory diagram of a fixing device when a fixed heating element is used as a tension applying unit and a belt shift regulating unit. FIG. 10 is a diagram illustrating a mechanism that can adjust a pressing unit used in FIG. FIG. 4 is an explanatory view of prevention of belt deviation by a fixed heating element.

According to FIG. 9 or FIG.
0 denotes a first fixing roller 17a as a first fixing roller member having elasticity on one side, as described with reference to FIG.
And a heating roller 17A as a heating roller member on the other side, a first fixing roller 17a and a heating roller 17A.
Belt 27A as a belt member stretched by
And a second fixing roller 17b as a second fixing roller member provided to face the first fixing roller 17a with the fixing belt 27A interposed therebetween, and a guide plate 173.

Heating roller 17A as heating roller member
A halogen lamp HL1 and a xenon lamp (not shown) are provided inside as a heat ray irradiating means for emitting heat rays such as infrared rays or far infrared rays for heating the heat generating roller 17A.

The fixing belt 27 as a belt member
A includes a ceramic heater 171 as a heating element, which contacts (contacts) the fixing belt 27A inside the fixing belt 27A on the conveyance side of the recording paper P between the heating roller 17A and the first fixing roller 17a. A heating element unit 170 as a fixed heating element, for example, having a width corresponding to the maximum transfer material size to be used and having a planar shape integrally formed with the heater holder 172 is provided, and the fixing unit 27A is heated by the heating element unit 170. I do. In this case, the ceramic heater 171 as the heating element does not necessarily need to directly contact the fixing belt 27A, and may be configured to contact the fixing belt 27A via the heater holder 172.

With the fixing belt 27A interposed between the first fixing roller 17a as a soft roller and the second fixing roller 17b as a hard roller, the upper side has a convex shape.
A relatively narrow nip portion N of about 15 mm is formed.

The guide plate 173 is heated by the heat from the fixing belt 27A, which is heated by the heating element unit 170 in which the ceramic heater 171 is integrated. While receiving the heat from the upper fixing belt 27A, the recording paper P is guided by the heated guide plate 173 and is conveyed.
While the toner image on the recording paper P is melted, the relatively narrow nip portion N having a width of about 5 to 15 mm between the fixing belt 27A and the second fixing roller 17b.
Then, in the nip portion N, the toner image on the recording paper P is fixed by the heating of the fixing belt 27A by the heat and the pressing by the first fixing roller 17a and the second fixing roller 17b.

In the above, as shown in FIG. 9, the heating element unit 170 is displaceable (movable) with the guide frame GW1 relative to the surface of the fixing belt 27A, and serves as pressing means attached to the fixed spring receiver SPA. The back of the heating element unit 170 (the surface opposite to the fixing belt 27A side) is pressed by the pressing spring SPa, and the heating element unit 1 is pressed.
70 presses the fixing belt 27A. The heating element unit 170 may be fixed, and the heating element unit 170 may press the fixing belt 27A. Fixing belt 27A of heating element unit 170 by pressing spring SPa
It is preferable that the heat generating unit 170 be pressed against a back surface of the heat generating unit 170 with a heat insulating plate (not shown) interposed therebetween to prevent the heat generating unit 170 made of a metal member from generating heat.

As described above, the heating element unit 170 as a fixed heating element acts as a means for applying tension to the fixing belt 27A (or a belt deviation restricting means), thereby preventing the fixing belt 27A from shifting and the heating element unit 170. Good adhesion to the fixing belt 27A.
As a result of using a rubber member, the temperature of the belt member with poor thermal conductivity is increased more quickly, the warm-up time is shortened, and the belt member changes in temperature during continuous printing and the temperature becomes non-uniform. Is prevented.

As shown in FIG. 10, in order to apply a more uniform pressing force to the fixing belt 27A of the heating element unit 170, the nuts NT at both ends of the fixing plate KP1 are screwed into the nuts NT of the spring receiver SPA. None), and the spring receivers SPA at both ends are rotated to adjust the pressing forces P1 and P2 to the heating element unit 170 by the pressing springs SPA at both ends as pressing means. Appropriate adjustment of the pressing forces P1 and P2 is performed, and the heating element unit 170 is uniformly pressed against the fixing belt 27A. Thereby, the heating element unit 1 as a fixed heating element
70 acts as tension applying means (or belt deviation regulating means) to the fixing belt 27A.
A is further prevented, and the heating element unit 17
0 is more closely adhered to the fixing belt 27A.
By using a rubber member, the temperature rise of the belt member with poor thermal conductivity can be further accelerated by ensuring further adhesion,
Warm-up time is further reduced,
The temperature change and non-uniformity of the temperature of the belt member during continuous printing are further prevented.

As shown in FIG. 11, a drum-shaped crown portion CR of, for example, (30 to 100 μm) / 20 cm is provided on the contact surface of the heating element unit 170 as a fixed heating element with the fixing belt 27A. Heating element unit 17
0 acts as a belt deviation regulating means, and the fixing belt 2
7A is moved to the center to prevent the fixing belt 27A from shifting, and prevent the heating element unit 170 from bending due to the force from the fixing belt 27A.

Further, a belt-side guide flange BG as a belt-side guide member is provided at both ends of the heating element unit 170.
It is preferable to provide the fixing belt 1 to surely prevent the fixing belt 27A from shifting.

As described above, the heating element unit 170 functions as a belt deviation regulating means, and the deviation of the fixing belt 27A is prevented.

[0146]

According to the present invention, the temperature rise of the belt member having poor thermal conductivity is accelerated, the warm-up time is shortened, and the temperature change and the temperature non-uniformity of the belt member during continuous printing are eliminated. In addition, when the toner image is fixed on the transfer material at the nip portion, good fixing performance with less fixing unevenness can be obtained, and a fixing device having high-speed capability can be realized.

[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 an explanatory diagram of a structure of a fixing device and setting conditions.

FIG. 4 is a dimensional relationship between the circumference of a belt member and the length of a fixed heating element that comes into contact with the belt member, and the circumference of the belt member, and the length of a fixed heating element and a heating roller member that comes into contact with the belt member. FIG. 4 is an explanatory diagram of a dimensional relationship with the sum of.

FIG. 5 is a dimensional relationship between the width of the nip portion and the length of the fixed heating element in contact with the belt member, and the sum of the width of the nip portion and the lengths of the fixed heating element and the heating roller member in contact with the belt member. FIG. 4 is an explanatory diagram of a dimensional relationship with the dashed line.

FIG. 6 is an explanatory diagram of a dimensional relationship between the length of a fixed heating element that contacts a belt member and the length of a heating roller member that contacts a belt member.

FIG. 7 is an explanatory diagram of a dimensional relationship when a plurality of fixed heating elements in FIGS. 4 to 6 are provided.

FIG. 8 is a dimensional relationship between a radius of curvature of a fixed heating element in contact with a belt member and a radius of a heating roller member, a radius of curvature of a fixed heating element in contact with a belt member, and a shape of a fixed heating element in contact with a belt member. It is explanatory drawing of the dimensional relationship with a contact length.

FIG. 9 is a schematic explanatory view of a fixing device when a fixed heating element is used as a tension applying unit and a belt shift regulating unit.

FIG. 10 is a view showing a mechanism that enables adjustment of a pressing unit used in FIG. 9;

FIG. 11 is an explanatory view of prevention of belt deviation by a fixed heating element.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 photoconductor drum 11 scorotron charger 12 exposure optical system 13 developing device 17A heating roller 17a first fixing roller 17b second fixing roller 27A fixing belt 170, 170A, 170B heating unit 171 ceramic heater 172 heater holder 173 guide plate 700 fixing device BG1 Belt-side guide flange CR Crown shape portion HL1 Halogen lamp P Recording paper SPA Spring receiver SPA Pressing spring

Claims (20)

[Claims] A first member for stretching a belt member on one side to form a nip portion for fixing a toner image on a transfer material;
A fixing device comprising: a fixing roller member; and a heat generating roller member that stretches the other side of the belt member together with the first fixing roller member, wherein the first fixing roller member and the heat generating roller member include: A planar fixed heating element that contacts the belt member from the inside of the belt member and heats the belt member is provided, and a length L2 (m) of the belt member that contacts the fixed heating element.
m), wherein L2 / L ≧ １ ／ with respect to the circumferential length L (mm) of the belt member. 2. The fixing device according to claim 1, wherein L2 / L <3/5. 3. A first member which stretches a belt member on one side to form a nip portion for fixing a toner image on a transfer material.
A fixing device comprising: a fixing roller member; and a heat generating roller member that stretches the other side of the belt member together with the first fixing roller member, wherein the first fixing roller member and the heat generating roller member include: A planar fixed heating element that contacts the belt member from the inside of the belt member and heats the belt member is provided, and a length L2 (m) of the belt member that contacts the fixed heating element.
m) and the length L1 (mm) of the belt member in contact with the heat roller member is (L2 + L1) (mm) with respect to the circumferential length L (mm) of the belt member. A fixing device, wherein ≧ 1/5. 4. The fixing device according to claim 3, wherein (L2 + L1) / L <4/5. 5. A first fixing roller member that stretches a belt member on one side, a heating roller member that stretches the other side of the belt member together with the first fixing roller member, and a belt that sandwiches the belt member. A second fixing roller member provided to face the first fixing roller member and forming a nip portion with the first fixing roller member, and fixing the toner image on the transfer material. A planar fixed heating element that contacts the belt member from the inside of the belt member and heats the belt member, between the first fixing roller member and the heating roller member; Length L2 (m
m) is L2 / Ln = 2 to 20 with respect to the width Ln (mm) of the nip portion. 6. A first member which stretches a belt member on one side to form a nip portion for fixing a toner image on a transfer material.
A fixing device comprising: a fixing roller member; and a heat generating roller member that stretches the other side of the belt member together with the first fixing roller member, wherein the first fixing roller member and the heat generating roller member include: A planar fixed heating element that contacts the belt member from the inside of the belt member and heats the belt member is provided, and a length L2 (m) of the belt member that contacts the fixed heating element.
m) and the length L1 (mm) of the belt member that comes into contact with the heat-generating roller member, (L2 + L1) (mm) is: (L2 + L1) / Ln = Ln (mm) of the nip portion N A fixing device comprising: 4 to 40. 7. The fixing device according to claim 5, wherein Ln is 5 to 15 mm. 8. A first member which stretches a belt member on one side and forms a nip portion for fixing a toner image on a transfer material.
A fixing device comprising: a fixing roller member; and a heat generating roller member that stretches the other side of the belt member together with the first fixing roller member, wherein the first fixing roller member and the heat generating roller member include: A planar fixed heating element that contacts the belt member from the inside of the belt member and heats the belt member is provided, and a length L2 (m) of the belt member that contacts the fixed heating element.
m): L2 / L1 = 1.0 to 3.0 with respect to the length L1 (mm) of the belt member contacting the heat roller member. 9. A first member which stretches a belt member on one side and forms a nip portion for fixing a toner image on a transfer material.
A fixing device comprising: a fixing roller member; and a heat generating roller member that stretches the other side of the belt member together with the first fixing roller member, wherein the first fixing roller member and the heat generating roller member include: A planar fixed heating element that contacts the belt member from the inside of the belt member and heats the belt member is provided, and a radius of curvature at which the fixed heating element contacts the belt member is R.
(Mm), when the radius of the heat roller member is R1 (mm), R ≧ 5 × R1. 10. The fixing device according to claim 9, wherein a length L2 (mm) of contact of the fixed heating element with the belt member satisfies L2 ≧ πR1. 11. The fixing device according to claim 9, wherein L2 = 20 to 100 mm. 12. The fixing device according to claim 9, wherein R ≦ 1000 mm. 13. A first fixing roller member which stretches a belt member on one side to form a nip portion for fixing a toner image on a transfer material, and a first fixing roller member together with the first fixing roller member. In a fixing device having a heating roller member extending on the other side, between the first fixing roller member and the heating roller member, the fixing member abuts on the belt member from the inside of the belt member, and fixes the belt member. A fixing device comprising: a fixed heating element having a planar shape to be heated; and wherein the fixed heating element functions as tension applying means for applying tension to the belt member. 14. The fixing device according to claim 13, wherein a pressing unit is provided on the fixed heating element. 15. The fixing device according to claim 14, wherein the fixed heating element is displaceable and the pressing unit is adjustable. 16. A first fixing roller member which stretches a belt member on one side to form a nip portion for fixing a toner image on a transfer material, and a first fixing roller member together with the first fixing roller member. In a fixing device having a heating roller member extending on the other side, between the first fixing roller member and the heating roller member, the fixing member abuts on the belt member from the inside of the belt member, and fixes the belt member. A fixing device, comprising: a fixed heating element having a planar shape to be heated; and the fixed heating element acting as a belt deviation regulating unit for regulating the deviation of the belt member. 17. A contact surface of the fixed heating element with the belt member has a crown shape.
7. The fixing device according to item 6. 18. The fixing device according to claim 16, wherein a belt-side guide member is provided on the fixed heating element. 19. The fixing device according to claim 16, wherein a pressing unit is provided on the fixed heating element. 20. The fixing device according to claim 19, wherein the fixed heating element is displaceable and the pressing unit is adjustable.