JP2003043843A - Fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an on-demand fixing device whose operation speed is made much higher, whose diameter is made smaller to realize miniaturization and whose thermal responsiveness is improved. SOLUTION: This fixing device has a heating member 3, an endless fixing member 1 sliding and rotating in a state where its inner surface abuts on the member 3, and a pressure member 2 pressuring and rotating in a state where it is opposed to the member 3 through the member 1. In the device, a member to be fixed P carrying an image is held and carried by a nip N between the members 1 and 2 so as to heat the image on the member P with the heat of the member 3 through the member 1. Then, a seamless aluminum alloy belt or sleeve having flexibility is used as the base material of the member 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device and an image forming apparatus equipped with the fixing device.

More specifically, a heating member, an endless fixing member whose inner surface abuts on the heating member to rotate and rotate, and a pressing member which presses and rotates facing the heating member via the fixing member. A fixing member carrying an image at a nip between the fixing member and the pressure member, and conveying the sandwiched member by a heat of the heating member through the fixing member to heat the image on the fixing member. And a image forming apparatus including the fixing device.

[0003]

2. Description of the Related Art As an issue that has recently become more important in image forming apparatuses such as electrophotographic systems used in copying machines, printers, fax machines, etc., there is a problem of energy saving.

The fixing device used in the image forming apparatus as described above consumes electric power directly as heat energy in order to melt the toner and fix it on the sheet, and is used in the entire image forming apparatus main body. It is a major factor in power consumption.

As one of the important directions for reducing the power consumption of the fixing device, the fixing device is on-demand.

Specifically, by making the fixing member a thin roller or a thin belt or film,
The heat capacity is reduced to accelerate the temperature rise, and at the same time, the heating power consumption is suppressed.

With the on-demand system, there is almost no waiting time when a print signal is received, and printing is started immediately. Therefore, it is not necessary to keep the fixing member at a high temperature near the printing temperature during non-printing. At room temperature, it should be kept at a moderately low temperature. The heat radiation during heat retention of the fixing device increases in proportion to the temperature difference between the environmental temperature and the set temperature of the fixing member, and these constantly consume electric power even when not printing. Therefore, in a situation where printing is repeated intermittently, the on-demand operation brings about a great power saving effect.

In the heat fixing type fixing device, generally, a method of heating the heater from the inner surface of the fixing member is mainly used. When the halogen lamp heating fixing roller is used, the temperature of the glass surface of the halogen lamp reaches a temperature far exceeding 200 ° C., but the actual temperature control is performed at about 180 ° C. by detecting the surface temperature of the fixing roller.

In the structure of a so-called on-demand fixing device using a heating member (heating element) such as a ceramic heater and a fixing film which have been commercialized in recent years, the heater temperature is 190.
At a low temperature of ~ 200 ° C, the same fixing performance as roller fixing with halogen lamp heating is obtained, so the top temperature can be reduced to almost the fixing temperature, and heat dissipation loss is lower than that of roller fixing system with halogen lamp heating. It can be said that there is little and is efficient.

Similarly, a method in which the fixing member itself generates heat, for example, a method using a self-heating element or magnetic induction heating,
It is a highly efficient system that can lower the top temperature. Also, since the area near the surface of the fixing member can be heated directly, the thermal response is improved, and stable temperature control with less ripple is possible compared to roller fixing by normal halogen lamp heating, and high temperature offset The latitude between the region and the low temperature offset region can be effectively taken. As a result, it is possible to obtain a stable image with high fixability and no uneven gloss.

In the on-demand fixing structure using a heating member and a thin fixing film which have been commercialized in recent years, generally, a heater such as ceramic or metal is brought into contact with the back surface of the fixing film so that the pressure member faces the pressing member. It is a heat transfer system in which a member to be fixed is nipped and conveyed, and a heat flow is directly sent to the image surface between the fixing nip via a fixing film to heat the image surface.

[0012]

However, even in the case of an on-demand fixing structure using a heating member and a thin fixing film, when the fixing speed is in a high speed region, the nip passage time becomes short, and the heater directly contacts the image surface between the nips. The amount of heat transport of is reduced. Therefore, as a heat transfer mechanism, there is a time lag in which heat is temporarily transferred from the heater to the film itself between the nips and the heat amount stored after one or several revolutions of the film is radiated in the nip portion to transfer the heat. There is a tendency to shift to the same heat storage type fixing. This time lag is confirmed as a direct thermal responsiveness delay by measuring with a thermoviewer or measuring the heating of the heater and the rise of the film surface temperature with time.

The time lag of heat transfer means an increase in the heat radiation time of the stored heat, the heat radiation amount of the entire fixing unit increases, and the thermal efficiency decreases.

When the time lag reaches a level of several seconds, the film having a small heat capacity is heated and controlled only by the temperature detection signal delayed by the thermistor of the heater temperature, and it is difficult to stabilize the film surface temperature.

As a result, a large amount of heat is always required to be stored in the film, and there is a tendency that the fixing property of the film or the roller after the first round is lowered not only during continuous paper feeding but also during intermittent paper feeding.

Therefore, in terms of design, it is difficult to reduce the diameter and size of the high-speed fixing device.

At present, a resin material such as polyimide having heat resistance and mechanical strength is used as a base material for the film. However, the resin originally has low thermal conductivity, and if the heat conductive filler is increased in the external addition ratio, the film is However, since it causes a decrease in strength, the thermal response is inevitably less than one digit with respect to a metal material.

According to the present invention, a heating member, an endless fixing member having an inner surface abutting against the heating member and slidingly rotating, and a pressurizing member which is rotated by pressing the heating member so as to face the heating member. A fixing member carrying an image at a nip between the fixing member and the pressure member, and conveying the sandwiched member by a heat of the heating member through the fixing member to heat the image on the fixing member. It is an object of the present invention to improve the speed, reduce the diameter and size, and improve the thermal response of a fixing device for on-demand fixing.

[0019]

The present invention is a fixing device and an image forming apparatus characterized by the following configurations.

(1) A heating member, an endless fixing member whose inner surface abuts on the heating member and slides and rotates, and a pressing member which presses and rotates facing the heating member via the fixing member. A fixing member carrying an image is nipped and conveyed at a nip between the fixing member and the pressure member, and the image on the fixing member is heated by the heat of the heating member via the fixing member. In the fixing device, a flexible seamless aluminum alloy belt or sleeve is used as a base material of the fixing member.

(2) An aluminum alloy belt or a sleeve as a base material of the fixing member is provided with a sliding layer or an abrasion resistant layer for the heating member abutting on the inner surface of the aluminum alloy belt or sleeve. The fixing device described.

(3) The heating member is made of a material such as metal or ceramic having a lower thermal conductivity than the aluminum alloy belt or sleeve as the base material of the fixing member. ) Or the fixing device described in (2).

(4) The heating member is basically composed of a base material and an electric heating portion provided on one side of the base material, and the electric heating portion serves as the fixing member for the base material. The fixing device according to any one of (1) to (3), which is formed on the contact surface side with the heating member.

(5) A coating layer having an elastic surface effect is provided on the outer surface side of the aluminum alloy belt or sleeve as the base material of the fixing member, and the heat of the localized heating portion of the heating member is applied to the coating layer. The fixing device according to any one of (1) to (4), characterized in that the fixing device thermally diffuses in the circumferential direction of the base material of the fixing member before reaching the adhesion surface.

(6) An image forming apparatus having an image forming process means for forming and carrying an unfixed image on a recording material and an image fixing means for thermally fixing the unfixed image on the recording material,
An image forming apparatus, wherein the image fixing unit is the fixing device according to any one of (1) to (5).

(7) The image forming means is a color image fixing means for forming an unfixed color image of a multilayer toner on a recording material, and the image fixing means is the fixing device described in (5). The image forming apparatus according to (6).

<Operation> That is, as a means for improving the thermal responsiveness of the fixing device, the present inventors have proposed an endless fixing member whose inner surface abuts on a heating member (hereinafter referred to as a heater) and slides and rotates ( Attention was focused on improving the heat transfer efficiency of the belt-shaped or sleeve-shaped base material (base material) itself (hereinafter referred to as a fixing belt). Then, as a base material of the fixing belt, a thin metal belt or a sleeve having a high thermal conductivity was studied from a polyimide film having an excellent flexibility but a low thermal conductivity. As the metal material, nickel, stainless alloy, aluminum alloy, titanium or titanium alloy was selected from the viewpoint of mechanical strength.

The nickel material can be thin-walled with high precision by an electroforming process, has high strength, and has good thermal conductivity.

Stainless steel is SUS304, SUS31
It is possible to reduce the thickness to about 50 to 80 μm by extruding or drawing using No. 4 and the like. Titanium or alloy has high strength, but is expensive in cost.

The aluminum alloy is preferably a malleable one which can be extruded and drawn, and duralumin, super duralumin or ultra super duralumin can be used from the viewpoint of strength. Alternatively, an amorphous alloy obtained by extruding an aluminum alloy powder having an amorphous structure near the crystallization temperature may be used.

The fixing belt has a base material and a thickness of 10 to 15 μm.
Fluorine resin PFA, FEP, PTFE, ETFE
And a releasable surface layer.

Among aluminum alloys, duralumin has a specific heat about twice that of stainless steel, but its specific gravity is small, so that its heat capacity is rather small. The thermal conductivity is almost an order of magnitude higher.

Therefore, the thermal response is about 1/10 that of the SUS tube having the same thickness.

That is, in the present invention, by using aluminum alloy as the base material of the tube, heat flow heating by direct heat transfer in the nip portion is possible even in a high speed region, and high speed on-demand fixing is realized. .

It is well known that aluminum has high thermal conductivity, but by using a high-strength aluminum alloy such as duralumin, a fixing belt base material that takes advantage of the high thermal conductivity characteristic of aluminum can be obtained. .

As an aluminum alloy, duralumin is A20.
17, A2011, A2014, etc., super duralumin A2
024 etc., and ultra-super duralumin A7075 etc. Duralumin A2017 and the like can be used in consideration of the workability of tube forming, stress corrosion and cracking.

From high thermal conductivity Aluminum alloy> Nickel electroformed material> Titanium type> Stainless steel material In that order.

Although the heat capacities are different, the thermal responsiveness is still in the same order, and from good ones, aluminum alloy> nickel electroformed material>titanium-based> stainless steel material.

Although stainless steel itself has a high thermal conductivity of one digit or more with respect to the polyimide resin, nickel electroforming has a high half-range digit thermal conductivity with respect to stainless steel, and the duralumin-based material has a half-higher thermal conductivity with respect to nickel electroforming. Orders of magnitude higher

As described above, the aluminum alloy has a one-digit higher thermal conductivity than stainless steel which has been used as a fixing member base material in recent years, is very advantageous in terms of thermal responsiveness, and almost lowers the heater temperature. Without heat transfer to the surface of the fixing belt, a larger heat flow is immediately transferred. Since the heat conduction is high, the rise time of the pressure member (pressure roller) is shortened.

In terms of thermal efficiency, the heat conductivity of the fixing belt base material is set to be higher than that of the heater base material, so that heat escape from the back surface of the heater to the heater holder is reduced, and It has been found to be expensive to increase the heat flow from the heat transfer surface to the fixing belt to improve heat transfer efficiency. In particular, this effect is great in the structure in which the energizing heat generating portion is provided on the heater surface which is in contact with the fixing belt, but the same effect still exists even when the energizing heat generating portion is on the opposite surface.

Specifically, there are the following configurations as a combination of the heater base material / fixing belt base material. For simplicity,
The polyimide is abbreviated as PI, the stainless material is SUS, the aluminum nitride is AlN, the nickel electroformed material is Ni, and the titanium system is abbreviated as Ti.

.. Alumina / PI, Alumina / SUS,
Alumina / Ti, alumina / Ni, alumina / aluminum alloy. AlN / PI, AlN / SUS, AlN / Ti, A
1N / Ni, AlN / aluminum alloy. SUS / PI, SUS / SUS, SUS / Ti, S
US / Ni, SUS / aluminum alloy Of these, alumina / SUS, alumina / Ti, alumina / Ni, alumina / aluminum alloy, AlN / SUS, A
1N / Ti, AlN / Ni, AlN / aluminum alloy, SU
S / SUS, SUS / Ti, SUS / Ni, and SUS / aluminum alloy are advantageous in terms of the combination of heat conduction, and there is a difference of one digit or more as a particularly excellent combination, that is, alumina / aluminum alloy, AlN / It was an aluminum alloy, SUS / aluminum alloy, or the like.

The thickness of the heater base material is preferably 1 mm or less,
About 0.4 to 0.6 t is desirable.

The thickness of the fixing belt substrate is preferably 100 μm or less, and more preferably 50 to 80 μm.

In manufacturing, low-cost molding is possible by performing draw forming using an wrought aluminum alloy having a low deformation resistance.

In the case of duralumin, in the semi-seamless processing by welding, since the annealing occurs at the joint, seamless processing is desirable. In addition, a seamless belt obtained by cold drawing is less expensive than hot extrusion. In the latter case, it is easy to obtain a uniform wall thickness, roundness, and outer and inner diameters in terms of accuracy, and it is possible to reduce the thickness with high strength. A surface treatment, abrasion resistance, strength, and elongation may be improved by additionally performing a modification treatment such as heat treatment.

[0048]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [Embodiment 1] (1) Example of Image Forming Apparatus FIG. 1 is a schematic view of an image forming apparatus in this embodiment.
The image forming apparatus of this example is a copying machine or a laser beam printer using a transfer type electrophotographic process.

Reference numeral 21 denotes a rotary drum type electrophotographic photosensitive member as an image bearing member, which is rotationally driven at a predetermined peripheral speed in a clockwise direction indicated by an arrow. During the rotation of the photoconductor 21, the photoconductor 21 is uniformly charged with a predetermined polarity and potential by the charging device 22,
An electrostatic latent image of image information is formed by receiving image exposure L on the charging surface by an image exposure device (imaging projection optical system for original image, laser beam scanning exposure optical system, etc.) not shown. . The electrostatic latent image is developed as a toner image by the developing device 23.

On the other hand, the recording material P is fed from a paper feeding portion (not shown), and is fed at a predetermined control timing to the transfer nip portion which is the pressure contact portion between the photoconductor 21 and the transfer roller 24. The recording material P receives the transfer of the toner image on the surface of the photoconductor 21 in the process of being nipped and conveyed in the transfer nip portion.

The recording material on which the toner image has been transferred is the photosensitive member 2.
It is separated from one surface, introduced into the fixing device 25, subjected to heat fixing processing of the toner image, and discharged as an image formed product (copy / print).

The surface of the photoconductor 21 after the transfer of the toner image to the recording material P is cleaned by the cleaning device 26 to remove residual contaminants such as transfer residual toner, and is subjected to repeated image formation.

(2) Fixing device 25 FIG. 2 is a schematic cross-sectional model view of the fixing device 25.

Reference numeral 1 is a cylindrical fixing belt as a fixing member, and 7 is a gutter-shaped fixing belt holding member having a substantially semicircular cross section, and the fixing belt 1 is loosely fitted onto the fixing belt holding member 7. .

Reference numeral 3 denotes a ceramic heater (hereinafter referred to as a heater) as a heating member, and 5 a heater holder made of a heat-resistant resin or the like for holding the heater 3 in a heat-insulating manner. The heater 3 is fitted and held in a groove provided in the heater holder 5, and the heater holder 5 is fitted and held in a groove provided along the length of the fixing belt holding member 7 at the center of the lower surface thereof. The heater 3 is fixed to the fixing belt holding member 7 via the heater holder 5. The heating surface of the heater 3 is exposed downward and faces the inner surface of the fixing belt 1 fitted onto the fixing belt holding member 7.

Reference numeral 2 denotes an elastic pressure roller as a pressure member. The fixing belt 1 is sandwiched between the heater 3 and the elastic roller of the pressure roller 2 against the elasticity of the pressure roller 2 with a predetermined pressing force so as to have a predetermined width. The fixing nip portion N is formed.

Reference numeral 6 denotes a U-shaped steel reinforcing member having a U-shaped cross-section facing downward and having a small flexure, which is arranged inside the fixing belt holding member 7 so as to be backed. The fixing belt holding member 7 and the heater holder 5 are provided.
The heater 3 has a strength that opposes the pressure applied by the pressure roller 2.

When the elastic pressure roller 2 is used as a driving roller, the cylindrical fixing belt 1 is rotated in the counterclockwise direction indicated by the arrow by the driving system M by frictional force with the roller 2 so that the cylindrical fixing belt 1 moves in the fixing nip portion N with the heater 3. It is rotationally driven while sliding in close contact with the downward exposed surface. Between the fixing belt 1 and the heater 3, grease, a solid lubricant or the like can be applied in advance to reduce friction and improve heat transfer.

Then, when the pressure roller 2 is rotationally driven, the fixing belt 1 is driven to rotate, and the heater 3 is heated and adjusted to a predetermined temperature, the heat generated by the heater 3 is generated in the fixing nip portion N. The back surface of the fixing belt 1 (inner surface,
From the back) to the front.

At the time of fixing, the recording material P carrying the unfixed toner image t, which is passed through the fixing nip portion N, is nipped and pressed between the fixing belt 1 and the pressure roller 2, and both are rotated. At the same time, the fixing nip portion N is nipped and conveyed, and at the same time,
The toner is melted by the heat from the surface of the fixing belt 1 and the heat accumulated by the pressure roller 2, and the pressure is applied to anchor (fix) the surface of the recording material P. This process is continuous during fusing.

(3) Fixing Belt 1 The cylindrical fixing belt 1 as a fixing member has a diameter of 30φ.
Then, as shown in the partially enlarged cross-sectional model view of FIG.
And a surface release layer 1-2.

As the base material 1-1, a thickness 5 formed by pultrusion molding
0 μ of duralumin A2017 was adopted (duralumin fixing belt). Besides, A2011 and A2014 can also be used. Since it is a flexible seamless sleeve, it is in close contact with the downward exposed surface of the heater 3 in the fixing nip portion N and produces an excellent heat transfer effect.

The surface release layer 1-2 is formed as a fluororesin tube or coat layer of FEP or PTFE, CPTFE, PFA or the like having a thickness of 50 μm or less. Considering heat transfer and durability, the fluororesin tube is 30 ~
The thickness of the coat layer is preferably about 50 μm, and the thickness of the coat layer is preferably about 10 to 15 μm.

(4) Pressure roller 2 The pressure roller 2 as a pressure member has a diameter of 30φ and a diameter of 18φ.
Core metal 2-1 and an outer circumference of the HTV silicone rubber layer (heat resistant elastic layer) 2-2 having a thickness of 6.0 t formed concentrically and integrally with each other, and a fixing belt further provided on the outer peripheral surface thereof. The same surface release layer 2-3 as the first surface release layer 1-2.

A sponge type having improved heat insulation may be used instead of the solid type. The pressure roller 2 was pressed against the fixing belt 1 to be driven and rotated in a state where a nip was formed between the two, and the nip width when stationary was 6.5 mm in the central portion.

(5) Heater 3 The ceramic heater 3 serving as a heating member is shown in the partially enlarged cross-sectional model view of FIG. 3, the partially cutaway plan view of the front side and the plan view of the back side of FIG. So that the thickness is 0.
Heater base (base) 3 made of alumina such as 4 to 1.0 mm or ceramic such as aluminum nitride which is more resistant to thermal shock 3
-1, and a resistance heating layer (electric heating portion) 3-2 containing molybdenum or the like is formed on the heater base 3-1 and
Further, it is based on the structure in which a thin insulating glass layer 3-3 is provided. More specifically: A heater base 3-1 made of a ceramic such as alumina having a horizontally long flat plate shape whose length is in the direction orthogonal to the sheet passing direction of the recording material P.
When, . On one surface side (front surface side) of the heater base material 3-1, a pattern is printed and fired in a strip shape along the length at a substantially central portion within the width of the heater base material 3-1 in the sheet passing direction. Resistance heating layer 3-2 ,. First and second power supplies such as Ag / Pd, which are electrically connected to both ends of the resistance heating layer 3-2, and printed and fired on the surface portions on both ends of the substrate. Electrode patterns 3-4 ,. An insulating protective glass layer 3-3 formed on the surface of the heater base material so as to cover the resistance heating layer 1-2 except for the portions of the first and second power feeding electrode patterns 3-4, and. On the other surface side (back surface side) of the heater base material 3-1,
It comprises a temperature measuring element 4 such as a thermistor arranged in contact with the heater base 3-1 at a substantially central portion in the longitudinal direction of the heater base.

The heater 3 is fixedly held on the fixing belt holding member 7 via the heater holder 5 by exposing the surface side on which the resistance heating layer b is provided downward.

Then, the first and second power feeding electrode patterns 3
Power is supplied from a power supply circuit (AC power supply circuit) (not shown) to the -4 through the power supply connector, so that the resistance heating layer 3-2 generates heat over substantially the entire length, and the heater 3 rapidly rises in temperature. To do. The temperature rise of the heater 3 is detected by the temperature detection element 4, and the temperature detection information is input to a control circuit (CPU) not shown. The control circuit controls the power supplied from the power supply circuit to the resistance heating element 3-2 (wavenumber control or phase control, etc.) so that the input heater temperature detection information of the temperature detection element 4 is maintained at a predetermined constant temperature. The temperature of the heating element is controlled.

In order to make the fixing device on-demand at the time of rising, it is necessary to send a large electric power of about 1000 W in a time of several tens of seconds. Once the print temperature is reached, it is necessary to send power of about 80 to 100 W for keeping the heat and about 400 to 500 W during paper fixing.

It took about 50 seconds to rise from the room temperature to a print temperature of 180 ° C. at which fixing is possible. this is,
Although the surface temperature of the fixing belt 1 rises fairly quickly, in the configuration in which the pressure roller 2 does not have a heat source, the fixability from a cold state becomes low, so that the multi-rotation process (starting of the image forming apparatus (starting (Startup) Operation period (warming period): When the main power switch is turned on, the main motor of the device is driven to rotationally drive the photoconductor, and the preparatory operation of the required process equipment is performed. This is because it requires The surface temperature ripple of the fixing belt 1 was about ± 4 ° C. Peripheral speed of pressure roller 30-120mm / s, pressure 196N (20kg
f).

It is possible to realize a small-diameter and miniaturized fixing device for high speed. As the diameter of the fixing image becomes smaller, at the trailing edge of the fixed image, the heating length of the fixing belt or the pressure roller becomes larger, and more divided heating regions corresponding to a plurality of turns are generated. Also, since the heat is absorbed by the paper, the amount of heat that is accumulated by the heat from the pressure roller cools and decreases, so that the fixability usually decreases.

In order to make the fixability uniform on the entire surface of the image,
It is necessary to sequentially increase the heat supply amount from the fixing belt side every one week in response to the decrease in heat supply from the pressure roller. The duralumin fixing belt has excellent thermal responsiveness even during high-speed driving, and by uniformly controlling the amount of heat supplied from the surface, uniform fixing properties can be obtained.

[Embodiment 2] In the embodiment 1, when the abrasion powder is generated on the inner surface of the fixing belt 1 using the aluminum alloy base material 1-1 such as duralumin due to the friction with the heater 3, the heater is generated. There is a tendency that the efficiency of heat transfer from the heater 3 is reduced, and at the same time, the sliding resistance between the inner surface of the fixing belt 1 and the surface of the heater 3 is increased to increase the torque of the drive motor.

Therefore, as shown in FIG. 5, the fixing belt substrate 1
-1 is applied to the inner surface of the slide coating layer 1-3 as a heat-resistant polyimide resin-based varnish and dried to a thickness of 1 to 1.
A thin coat layer having a thickness of about 0 μm was formed. With this thickness, there is no significant effect on heat transfer.

Any material may be used as long as it is excellent in abrasion resistance and heat resistance, and has high adhesiveness so that peeling due to bending of the fixing belt base material 1-1 does not occur. A small amount of solid lubricant such as boron nitride may be externally added for sliding. It is even better to apply a lubricant such as silicone grease to the sliding surface.

As a result, there was almost no change in the characteristics of thermal efficiency and torque even after fixing 50,000 sheets of paper.

[Embodiment 3] In addition to the improvements made in Embodiment 2, as shown in FIG. 6, the end portion of the fixing belt 1 is subjected to bulging tube expansion molding, and R to 1 is applied to both ends or one end of the fixing belt.
It is possible to provide a curvature of about mm so that the sliding coat layer 1-3 on the back surface bears the sliding friction of the end portion of the fixing belt against the abutting member 9 for preventing the deviation of the fixing belt.

In FIG. 6, the reinforcing member 6 and the fixing belt holding member 7 are omitted. The end of the fixing belt 1 is prevented from shifting by the abutting member 9. Reference numeral 11 is a fixing unit side plate.

The pressure roller 2 is rotationally driven by the drive shaft 2-1 passed over the bearing 10. The length of the pressure roller was set to be short so as not to reach this end position in order to prevent scratches.

[Embodiment 4] FIG. 7 shows a structure in which a temperature leveling member in the axial direction of the fixing belt is added to prevent the temperature rise of the end portion of the fixing belt.

Axial heat transfer members 12-1 and 12-2 such as aluminum are brought into contact with the inner surface of the fixing belt 1. Heat transfer member 12
-1, 12-2 may be fixed members, or may be rotating members that follow the rotation of the fixing belt 1, such as a hollow pipe shape. It is preferable to provide a coat or film having a high slidability on the contact surface with the inner surface of the fixing belt.

Since the base material 1-1 of the fixing belt 1 is an aluminum alloy and has high heat conductivity, the heat transfer members 12-1, 12-
The heat exchange with 2 is carried out promptly. Then, the temperature distribution is made uniform in the axial direction inside the heat transfer member. Of course, even within the fixing belt 1 itself, the temperature distribution is made uniform in the axial direction due to the high heat transfer characteristics at the fixing nip portion N and other portions. Here, the heat transfer members 12-1 and 12-2 are brought into contact with each other from the inside by utilizing the slight elasticity of the fixing belt 1, and the shape of the fixing belt is slightly crushed in the lateral direction. It also has a function of extending the life of the fixing belt by reducing the bending of a certain belt base material 1-1 in and out of the fixing nip portion.

[Embodiment 5] FIG. 8 shows a configuration in which a metal heater (stainless steel heater) having a heater base material a of stainless steel is used as the heater 3 and a fixing belt 1 having a base material 1-1 of duralumin is combined. .

The metal heater 3 has a structure in which a resistance heating layer 3-2 is formed on a stainless steel base 3-1 via a glass insulating layer 3-5, and a glass insulating layer 3-3 is further provided. .

The resistance heating layer 3-2 is located immediately below the thin protective glass layer 3-3, which is the sliding surface with the fixing belt 1, and when the energization heating is performed, it is a heater base material. Three
Since the thermal conductivity of duralumin of the fixing belt base material 1-1 is much higher than that of stainless steel of -1, the heat is efficiently transferred to the duralumin of the fixing belt base material 1-1, and from the back surface of the heater base material of stainless steel. Heater holder 5
Relatively prevent the escape of heat through.

Although a stainless steel heater has been described as an example here, it is obvious that a ceramic-based heater (ceramic heater) such as alumina or aluminum nitride, which is inferior in heat conductivity to stainless steel, is used for the above reasons. It is effective. However, the heater based on the stainless steel has an advantage peculiar to the metal heater in that the material is inexpensive and there is no fear of cracking. Since the metal heater itself has high heat conduction, the heat escape from the back of the heater increases at the same set temperature, and the thermal efficiency tends to decrease.
By combining duralumin, which has a higher thermal conductivity, with the fixing belt 1 having the base material 1-1, the heat transfer to the surface of the fixing belt is enhanced and the thermal efficiency is relatively increased.

As shown in FIG. 9, the above-mentioned metal heater 3 is arranged reversely to the upper surface and the lower surface (back surface heating type), and a glass sliding layer 3-6 is further provided on the sliding surface with the inner surface of the fixing belt. A heater structure of the base material is also possible, and in this case also, the same effect can be obtained by combining with a fixing belt using duralumin as the base material 1-1.

[Embodiment 6] Although a full-color image forming apparatus using toner is omitted in the drawing, a composite superposition layer (multi-layer toner) of color toner images of three or four colors is formed on a recording material and heated. It is melted and mixed for fixing. FIG. 10 shows a fixing belt having a three-layer structure in order to give the fixing belt 1 an elastic wrapping effect with respect to the multi-layered toner in order to cope with color fixing of such a thick toner layer. That is, the surface release layer 1 made of fluororesin
-2 and a fixing belt substrate 1-1 made of an aluminum alloy, a low hardness silicone rubber such as RTV, LTV or HTV having a thickness of 30 to 350 μm was provided as an elastic intermediate layer 1-4.

Since the silicone rubber enhances heat conduction, it is preferable to add a heat conduction filler such as silica, alumina or carbon to the outside. In this fixing belt structure, since the heat transfer is still reduced by the rubber layer, it is difficult for the heating mechanism itself to immediately apply the heat flow to the image fixing surface at the fixing nip portion N due to the heat conductivity of the aluminum alloy as described above. However, since heat is efficiently transferred to the entire surface of the duralumin, which is an aluminum alloy, only in the base material 1-1 portion on the inner surface of the fixing belt, even by the fixing nip portion N having a limited area,
Heat can be transmitted to the surface of the fixing belt 1 through the rubber layer 1-4 while the fixing belt 1 makes one to several turns and returns to the fixing nip portion N again.

Since heat diffuses in the circumferential direction inside the fixing belt base material 1-1 having high thermal conductivity, a local high temperature is generated at the bonding surface between the rubber layer 1-4 and the belt base material 1-1. There is almost no. Therefore, it is rather advantageous in terms of life.

In the color OHT fixing mode, in order to improve the transparency, the speed is a few times lower than that in the plain paper mode, but the heat flow in the fixing nip portion N is indicated by an arrow as shown in FIG. In that case, since the resistance heating portion b on the heater 3 surface tends to be locally heated,
Heat damage is likely to occur at the position of the bonding interface indicated by the ellipse. In order to prevent this heat damage, there is a method of increasing the thickness of the belt base material and utilizing heat diffusion in the belt circumferential direction, but since the heat capacity increases, the rise time is extended. Alternatively, the rise time can be shortened in this case by increasing the thermal conductivity of the belt substrate itself. Therefore, this tendency is more likely to occur in a ceramic-based heater having a low thermal conductivity, but as described above, the aluminum alloy belt base material 1-1 having a significantly high thermal conductivity is used.
10 is a relative to that shown in FIG. 11, as shown by the arrows in FIG. 10 indicating the flow of heat, the damage is prevented by the heat diffusion effect in the circumferential direction, and at the same time, the heating area is spread over the entire nip. It can be used effectively. This effect is remarkable because the heat transfer is higher by one digit in the fixing belt 1 having the base material 1-1 of duralumin, which is an aluminum alloy, as compared with the fixing belt of the stainless steel base material. In addition, since the amount of heat required for fixing is rather stable, temperature control does not require expensive phase control or wave number control, so it is inexpensive.
It is possible to use a -OFF control method.

The case where the fixing belt 1 has a three-layer structure has been described. However, even when the fixing belt 1 has a two-layer structure in which an elastic fluororesin layer is provided on the surface of the base material, the toner wrapping effect is slightly inferior. Therefore, the same effect can be obtained in heat transfer.

[Others] 1) Whether the fixing device is an oil-based fixing device or an oil-less fixing device, the same effect is obtained.

2) The heating member (heater) may be an electromagnetic induction heat generating member.

3) The fixing device of the present invention also includes an image heating device for hypothetically fixing the image on the recording material, an image heating device for modifying the image surface property of gloss and the like.

[0096]

As described above, the present invention speeds up,
The small-diameter fixing belt reduces size, saves energy, is on-demand, and improves heat conduction in the axial direction, which is advantageous for increasing the temperature at the end.

The structure is simple and low-cost, and the fixing is efficiently performed at high speed.

Unlike the conventional on-demand structure fixing, since the heat conduction of the belt base material is very high, the ratio of the wasteful heat flow leaking from the heating heater to the holding member on the back surface is relatively high even if the metal base heater is used. The thermal energy can be reduced by minimizing the unnecessary heating of the inner surface and preventing the surface from overshooting due to the heat that moves to the belt heating more effectively. Is used effectively to save energy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus according to a first exemplary embodiment.

FIG. 2 is a schematic configuration diagram of a fixing device.

FIG. 3 is an enlarged cross-sectional model view of the main part of the fixing device.

FIG. 4 is an explanatory diagram of a heater configuration.

FIG. 5 is an enlarged cross-sectional model view of a main part of the fixing device according to the second exemplary embodiment.

FIG. 6 is an enlarged vertical cross-sectional model diagram of a main part of a fixing device according to a third exemplary embodiment.

FIG. 7 is an enlarged cross-sectional model view of a main part of the fixing device according to the fourth exemplary embodiment.

FIG. 8 is an enlarged cross-sectional model view of a main part of the fixing device of Example 5 (No. 1)

FIG. 9 is an enlarged cross-sectional model view of a main part of the fixing device of Example 5 (No. 2)

FIG. 10 is an enlarged cross-sectional model view of a main part of the fixing device according to the sixth exemplary embodiment.

FIG. 11 is an enlarged cross-sectional model view of a main part of a fixing device of a comparative example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fixing belt, 1-1 ... Fixing belt base material, 1-2 ... Surface release layer, 1-3 ... Abrasion resistant sliding layer, 2 ... Pressure roller, 3
... Heating heater, 3-1 ... Heater base material, 3-2 ... Heating resistance layer, 3-3 ... Insulating protective glass layer, 3-4 ... Feeding electrode part, 3-5 ... Insulating layer, 3-6 ... Sliding layer, 4 ... Thermistor, 5 ... Heater holder, 6 ... Pressure reinforcing member, 7 ... Belt stability holding member, 2-1 ... Pressure roller drive shaft, 9 ... Deviation preventing butting member, 10 ... Pressure roller Bearings, 11 ... Fixing unit side plates, 12-1, 12-2 ... Temperature equalizing member

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masaharu Okubo             3-30-2 Shimomaruko, Ota-ku, Tokyo             Non non corporation F-term (reference) 2H030 AA05 AD01 AD04                 2H033 AA20 AA21 AA30 BB03 BB05                       BB06 BB13 BB14 BB15 BB18                       BB21 BB29 BB30                 3K058 AA03 BA18 CA12 CA61 CE19                       DA01

Claims (7)

[Claims] 1. A heating member, an endless fixing member having an inner surface abutting on the heating member and slidingly rotating, and a pressing member facing the heating member via the fixing member and rotating under pressure. And a fixing member that carries an image in a nip between the fixing member and the pressure member, and conveys the fixing member by heating, and heats the image on the fixing member by the heat of the heating member via the fixing member. A fixing device characterized by using a flexible seamless aluminum alloy belt or sleeve as a base material of the fixing member. 2. An aluminum alloy belt or a sleeve as a base material of the fixing member is provided with a sliding layer or an abrasion resistant layer for the heating member abutting against the inner surface of the aluminum alloy belt or the sleeve. Fixing device. 3. The heating member is made of a material such as metal or ceramic having a lower thermal conductivity than an aluminum alloy belt or sleeve as a base material of the fixing member. Or the fixing device described in 2. 4. The heating member comprises a base material and an energizing heat generating portion provided on one surface side of the base material as a basic constituent body, and the energizing heat generating portion is provided on the base material with the fixing member and the fixing member. The fixing device according to any one of claims 1 to 3, wherein the fixing device is formed on the contact surface side with the heating member. 5. A coating layer having an elastic surface effect is provided on the outer surface side of an aluminum alloy belt or sleeve as a base material of the fixing member, and heat of a localized heat generating portion of the heating member is bonded to the coating layer. The fixing device according to any one of claims 1 to 4, wherein heat is diffused in the circumferential direction of the base material of the fixing member before reaching the surface. 6. An image forming apparatus comprising: an image forming process means for forming and carrying an unfixed image on a recording material; and an image fixing means for thermally fixing the unfixed image on the recording material. An image forming apparatus, which is the fixing device according to any one of 1 to 5. 7. The image forming means is a color image fixing means for forming an unfixed color image of a multi-layer toner on a recording material, and the image fixing means is the fixing device according to claim 5. The image forming apparatus according to claim 6.