JP2003248390A - Fixing device, electrophotographic device and image forming apparatus equipped with fixing device, and fixing method and electrophotographic image forming method using them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device surely preventing faulty fixing. <P>SOLUTION: The fixing device has a pressure roller 13 which has a surface layer consisting of a flexible elastic body 16 whose inner surface is coated with a metallic thin film 17, a metallic core 19, and a hollow space 18 formed by the surface layer and the shaft center 19, whose space 18 is filled with gas of fixed pressure, and in which the contact of the thin film 17 with the core 19 is set as a switch. The fixing device adopting a belt fixing system as a fixing system, and the electrophotographic device and the image forming apparatus equipped with the fixing device, and the fixing method and the electrophotographic image forming method using them are provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a fax machine,
In an electrophotographic recording device such as an electrophotographic printer, a heat fixing device that heats an image made of heat-fusible toner formed on the surface of a recording material such as paper to fix it as a permanently fixed image on the surface of the recording material. An image forming apparatus including a device,
The present invention relates to a fixing method and an image forming method using the fixing device and the image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, a fixing device for forming a toner image on a recording medium by an electrophotographic method or an electrostatic recording method and fixing the toner image on the recording medium by heat and pressure, and an electronic device having the fixing device. The so-called heat roller fixing method has been widely used in photographic devices. However, in the heat roller fixing method, it usually takes about 5 to 20 minutes to start up, and the heat capacity of a predetermined member constituting the fixing device is large. If the amount of heat is not supplied, the high temperature state cannot be maintained, which causes transfer failure, resulting in a large energy consumption.

Further, Japanese Patent Laid-Open No. 8-286535 discloses a fixing device adopting a so-called belt system, in which a fixing belt is stretched between a fixing roller and a heating roller, and the fixing belt is provided. It is disclosed that a pressure roller for pressing the fixing roller from below is provided via the fixing roller to fix the belt using the heat of the belt as a preheating source.

Further, a belt system is also used in a similar manner.
Japanese Patent Laid-Open No. 314303 proposes a fixing device and the like that consumes less power, can obtain a high-quality image without applying a release agent, and can perform fixing at a constant speed regardless of the type of recording medium. ing.

In the above belt system, the nip becomes long and heating can be performed for a long time, so that the temperature can be lowered or the fixing can be performed at high speed. However, there is a problem that the longer the nip, the easier the offset is.

Examples of the layer structure of the fixing roller and the fixing belt will be given. As a first example, there is a material made of an elastic release material, which is represented by silicone rubber. As a second example, there is one made of a releasing material, which is represented by a fluororesin (typically tetrafluoroethylene perfluoroalkoxy vinyl ether copolymer (hereinafter abbreviated as PFA)).
No. 00). Further, as a third example, there is one in which a release material is laminated on an elastic release material, and one in which a fluororesin is laminated on a silicone rubber.

In the above-mentioned first example of the layer structure of the fixing roller and the fixing belt, the elastic body is applied to secure the nip, but in this example, the material is not sticky. Therefore, there is a problem in offset of the paper such as a problem in conveyance or dust is easily attached.

In the second example, since a thin film having a thickness of about 40 μm is usually applied, elasticity is insufficient, the nip cannot be removed, sufficient heat cannot be supplied, and fixing property is insufficient. It has a problem of fear.

In the third example, silicone is used for elasticity, and fluorine resin is used for releasability, so that the above problem can be solved. However, both the heat roller fixing method and the belt method, when the material to be heated (recording medium) is inserted,
There is a problem that the temperature of the nip portion cannot be measured directly, the temperature decrease of the nip portion due to the insertion of the material to be heated cannot be detected, and the temperature decrease of the nip portion causes defective fixing.
On the other hand, Japanese Patent Application Laid-Open No. 11-231705 discloses a structure that detects the temperature of a nip portion when a material to be heated is inserted to prevent fixing failure.

Further, in the electrophotographic image forming apparatus, the toner electrostatically transferred from the photosensitive member to the paper is easily peeled off, so that the toner may be permanently fixed to the paper by heating or pressing. Will be needed. This step is called the fixing process.

There are various fixing methods. For example, the heat roller fixing method is most widely used because of its high thermal efficiency and safety. In this method, two rollers are pressed against each other, at least one of the rollers is heated, and a material to be heated (paper, OHP sheet, etc.) is passed through the pressure contact portion (nip part) of these two rollers, thereby unfixing. In this method, toner is heated and fixed on paper.

When heating one of the two rollers,
The heating roller is called a fixing roller, and the other roller is called a pressure roller. A heat source such as a halogen lamp or an electric heater is provided inside the fixing roller in the axial direction of the fixing roller. A temperature sensor is attached to the outer surface of the fixing roller, and the amount of power supplied to the heat source is controlled so that the temperature of the nip portion is maintained at a temperature suitable for fixing.

In recent years, in a heat roller fixing type fixing device, in order to save energy, an attempt has been made to reduce the heat capacity of the fixing roller and the pressure roller to shorten the startup time until the temperature reaches the set temperature. There is. However, this reduces the ratio of the heat capacities of the fixing roller and the pressure roller to the heat capacity of the sheet on which the toner image is placed, and stores a sufficient amount of heat in the fixing roller and the pressure roller for fixing one sheet of paper. However, there is a problem that fixing failure occurs due to a temperature decrease in the second half of the sheet or in repeat copying. On the other hand, if it is attempted to prevent such a fixing failure by raising the set temperature of the fixing roller, this time, the temperature rises too much in the first half of the paper, and the toner melts too much and adheres to the fixing roller. This causes a problem of causing a problem (hot offset) that stains the surface of the paper.

In order to avoid such a problem,
JP-A-6-75504, JP-A-6-130843
Japanese Patent Laid-Open No. 5-281875 and Japanese Patent Laid-Open No. 5-281875 are disclosed. In Japanese Unexamined Patent Publication No. 6-75504, when a low-temperature paper passes through the nip portion, the surface temperature of the fixing roller is high in the first half of the paper and becomes lower toward the second half, so that the first half of the paper passes through the nip portion. And the fixing temperature of the latter half of the sheet changes, the surface temperature of the fixing roller is detected and the heater of the fixing roller heater is controlled so that the temperature becomes constant. There is disclosed a fixing device configured to increase the temperature and prevent the temperature of the fixing roller from dropping. In addition, JP-A-6
In JP-A-130843, a nip portion is provided by providing a heat conduction roller inside the fixing roller and bringing the outer circumferential surface of the heat conduction roller into contact with the inner circumferential surface of the fixing roller to increase the heat supply amount to the nip portion. There is disclosed a fixing device configured to prevent the temperature drop of the above. In addition, JP-A-5
In Japanese Patent No. 2881875, instead of a single sheet of paper,
Measures the temperature when the leading edge of the paper reaches the nip and the temperature of the fixing roller when the trailing edge exits the nip when the temperature drop occurs during repeat copying. Then, a method of changing the set temperature of the fixing roller by setting the value obtained by adding the temperature difference to the standard control temperature as the set temperature is disclosed.

In the prior arts disclosed in the above-mentioned respective publications, the one in which the temperature of the fixing roller is changed, even if the amount of increase in the heat value of the heater is decided by predicting the amount of temperature decrease in advance, Since the amount of temperature decrease varies depending on the type, initial temperature, moisture content, etc., it is difficult to make an accurate prediction. The method of providing a heat transfer roller inside the fixing roller to increase the amount of heat supplied to the nip portion has a limit to the amount of heat supply that can be increased because there is thermal resistance between the fixing roller and the heat transfer roller. In the case of thick or high-speed copying, it is doubtful whether sufficient effect can be obtained. The method of changing the set temperature of the fixing roller by measuring the temperature when the leading edge of the paper reaches the nip portion and the temperature of the fixing roller when the trailing edge leaves the nip portion is There is a problem that the mechanism is complicated, such as a means for detecting that the rear end has reached the nip portion. In view of these points, a structure that detects the temperature of the nip portion when the material to be heated is inserted and prevents fixing failure is disclosed in Japanese Patent Laid-Open No. 2000-2000.
No. 338814.

[0016]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The pressure roller disclosed in Japanese Patent No. 1705 has a surface layer made of a flexible elastic body whose inner surface is coated with a metal thin film, a metal shaft core, and a hollow space formed by the surface layer and the shaft core. And is provided. The space is filled with a gas having a constant pressure, and when the two metals, the metal thin film on the surface layer and the shaft core, come into contact with each other, the operation of preventing fixing failure is started. However, the pressure roller disclosed in Japanese Unexamined Patent Application Publication No. 11-231705 is applied to the heat roller fixing system, and the contact area between the material to be heated and the pressure roller is small, that is, the pressure rollers are metal-metal. Has a problem that the contact area is small and the reliability is low. Further, since the contact area between the material to be heated and the pressure roller is small, the degree of contraction of the gas in the space of the pressure roller is small, so that there is a problem that the sensitivity is lowered.

Further, the pressure roller disclosed in Japanese Unexamined Patent Publication No. 2000-338814 has a surface layer made of a flexible elastic body having a light emitting portion and a light receiving portion made of an optical fiber, and a shaft for reflecting light. It has a core and a hollow part formed by the surface layer and the shaft core, and has a structure in which the hollow part is filled with a gas at a constant pressure, and the operation to prevent fixing failure by changing the width of the hollow part is started. To do. However, Japanese Patent Application Laid-Open No. 2000-338814 discloses a heat roller fixing method, and this heat roller fixing method has a small contact area between the material to be heated and the pressure roller,
There is a problem that the hollow portion of the pressure roller also has a small shrinkage amount and the sensitivity is low.

Therefore, in the present invention, the pressure roller has the same structure as the conventional one, but by adopting the belt system, the fixing device for surely preventing the defective fixing due to the temperature decrease, and the electrophotographic apparatus equipped with this fixing device. Provided are an apparatus, an image forming apparatus, a fixing method using the same, and an electrophotographic forming method.

[0019]

According to a first aspect of the invention, a surface layer made of a flexible elastic body having an inner surface coated with a metal thin film, a metal shaft core, a surface layer and a shaft core are provided. And a hollow space formed by the above, wherein the space is filled with a gas having a constant pressure, and a pressure roller that serves as a switch by contacting both metals of the metal thin film of the surface layer and the shaft core is provided. A fixing device having the above-mentioned fixing device is a belt fixing system.

According to a second aspect of the invention, there is provided a fixing device characterized in that a switch for raising the temperature of the fixing belt is turned on by the contact of the two metals.

In a third aspect of the invention, a surface layer made of a flexible elastic body having an inner surface coated with a metal thin film, a metal shaft core, and a hollow space formed by the surface layer and the shaft core. In a belt fixing device having a space and a gas having a constant pressure filled in the space, both the metal of the metal thin film and the metal shaft core are brought into contact with each other so that the periphery of the fixing belt and / or the pressure of the fixing belt are increased. A fixing device characterized in that a heating lamp arranged around the pressure roller is operated to heat the fixing belt.

According to a fourth aspect of the present invention, there is provided a fixing device characterized in that a switch for reducing the rotation speed of the fixing belt is turned on by the contact of the two metals.

According to a fifth aspect of the invention, there is provided a fixing device characterized in that a switch for increasing the pressure contact force between the fixing belt and the pressure roller is turned on by the contact of the two metals.

According to the sixth aspect of the invention, in the fixing device for fixing the toner image carried on the sheet-shaped recording medium to the sheet-shaped recording medium, the unfixed toner image is fixed on the sheet-shaped recording medium. For fixing the first fixing device, a second fixing device provided after the first fixing device, and between the first fixing device and the second fixing device. The first fixing device has a fixing means, which has a conveying path switching means for switching the conveying path between an unloading path and a path toward the second fixing device, and control means for controlling the operation of the conveying path switching means. A belt and a pressure roller that rotates in pressure contact with the fixing belt, and heats and presses the toner image while the sheet-shaped recording medium is conveyed under pressure, and is provided on the pressure roller of the first fixing device. Of the sensor By knowledge state, by the control means, to provide a fixing device characterized by switching the conveying path.

According to a seventh aspect of the invention, there is provided a fixing device characterized in that the shaft core is non-conductive and the shaft core is coated with a metal thin film.

According to an eighth aspect of the invention, there is provided a fixing device characterized in that the gas filled in the hollow space is an inert gas.

According to a ninth aspect of the present invention, the pressure roller of the first fixing device reflects light on a surface layer made of a flexible elastic body having a light emitting portion and a light receiving portion made of optical fibers. And a hollow space portion (hollow portion) formed by the surface layer and the shaft core, and the hollow portion is filled with gas at a constant pressure, and the light receiving portion of the optical fiber is sensed. A fixing device is provided.

In a tenth aspect of the present invention, the pressure roller of the first fixing device reflects light on a surface layer made of a flexible elastic body having a light emitting portion and a light receiving portion made of optical fibers. It has a shaft core and a hollow portion formed by the surface layer and the shaft core, and the hollow portion is filled with a gas of a constant pressure, and the state of the light receiving portion is determined by a fixing device that senses the light receiving portion of the optical fiber. This detection function is used as a distance sensor, and when the distance between the surface layer and the shaft core reaches a certain distance, the second fixing unit located after the first fixing device is detected.
A fixing device is characterized in that a switch for heating a fixing roller or a fixing belt of the fixing device is turned on.

The invention according to claim 11 provides the fixing device according to claim 9 or 10, characterized in that the gas filled in the hollow portion is an inert gas.

According to a twelfth aspect of the present invention, there is provided an electrophotographic apparatus comprising a fixing device for fixing a toner image carried on a sheet-shaped recording medium to the sheet-shaped recording medium, the sheet-shaped recording medium being undetermined. Between the first fixing device for fixing the toner image on the second fixing device, the second fixing device provided in the latter stage of the first fixing device, and between the first fixing device and the second fixing device. A delivery path switching unit for switching the delivery path of the sheet-shaped recording medium between the delivery path and the path toward the second fixing device; and a control unit for controlling the operation of the delivery path switching unit. The first fixing device is composed of a fixing belt and a pressure roller which rotates in pressure contact with the fixing belt, and heats and presses the toner image while conveying the sheet-shaped recording medium under pressure.
An electrophotographic apparatus is characterized in that the control means switches the transport path according to the state detected by a sensor provided on a pressure roller of the fixing device.

According to a thirteenth aspect of the present invention, the pressure roller of the first fixing device reflects light on a surface layer made of a flexible elastic body having a light emitting portion and a light receiving portion made of optical fibers. And a hollow portion formed by the surface layer and the shaft core, wherein the hollow portion is filled with a gas having a constant pressure, and the fixing device is characterized by sensing the light receiving portion. Provided is an electrophotographic apparatus.

According to a fourteenth aspect of the present invention, the pressure roller of the first fixing device reflects a light and a surface layer made of a flexible elastic body having a light emitting portion and a light receiving portion made of optical fibers. And a hollow portion formed by the surface layer and the shaft core, and the hollow portion is filled with a gas having a constant pressure, and the state of the light receiving portion is determined by a fixing device that senses the light receiving portion of the optical fiber. When the distance between the surface layer and the shaft core reaches a specific distance, the fixing roller or the fixing belt of the second fixing device located after the first fixing device is detected. Provided is an electrophotographic apparatus including a fixing device, which is characterized in that a switch for heating is heated.

According to a fifteenth aspect of the invention, there is provided an electrophotographic apparatus comprising a fixing device, wherein the gas filled in the hollow portion is an inert gas.

According to the sixteenth aspect of the present invention, a photoconductor, a means for forming an electrostatic latent image on the photoconductor, a developing means for developing the formed electrostatic latent image into a toner image, and a photoconductor. An image having a transfer unit that transfers the toner image formed on the body directly to a sheet-shaped recording medium or via an intermediate transfer medium, and a fixing unit that fixes the toner image transferred to the recording medium to the recording medium An image forming apparatus is provided which uses the fixing device according to any one of claims 1 to 8 as a fixing unit in the forming device.

According to a seventeenth aspect of the invention, there is provided a fixing method using a fixing device for fixing the toner image carried on the sheet-shaped recording medium to the sheet-shaped recording medium.
The fixing device includes a first fixing device for fixing an unfixed toner image on a sheet-shaped recording medium, a second fixing device provided at a stage subsequent to the first fixing device, and a first fixing device. And a second fixing device, the transfer route switching means for switching the transport route of the sheet-shaped recording medium between the carry-out route and the route toward the second fixing device, and the operation of the transport route switching means. A control means for controlling the first
The fixing device includes a fixing belt and a pressure roller that rotates in pressure contact with the fixing belt. The fixing device heats and presses the toner image while the sheet-shaped recording medium is nipped and conveyed. The pressure roller has a surface layer made of a flexible elastic body having a light emitting portion and a light receiving portion made of optical fibers, a shaft core that reflects light, and a hollow portion formed by the surface layer and the shaft core. However, the hollow portion is configured to be filled with a gas having a constant pressure, the light receiving portion of the optical fiber is sensed, and the control means switches the transport path according to the state. A characteristic fixing method is provided.

According to the eighteenth aspect of the invention, depending on the state of the light receiving portion of the pressure roller of the first fixing device,
The distance between the surface layer and the shaft core is detected, and when a specific distance is reached, a switch for heating the fixing roller or the fixing belt of the second fixing device in the subsequent stage of the first fixing device is turned on. A characteristic fixing method is provided.

According to a nineteenth aspect of the present invention, there is provided a fixing method, wherein the gas filled in the hollow portion is an inert gas.

According to a twentieth aspect of the invention, there is provided an electrophotographic forming method using an electrophotographic apparatus equipped with a fixing device for fixing the toner image carried on the sheet-shaped recording medium to the sheet-shaped recording medium, The fixing device is a first fixing device for fixing an unfixed toner image on a sheet-shaped recording medium.
Fixing device and the second fixing device provided after the first fixing device.
Of the fixing device and the first fixing device and the second fixing device, and the conveyance route of the sheet-shaped recording medium is provided between the carry-out route and the route toward the second fixing device. The first fixing device has a fixing belt and a pressure roller that rotates in pressure contact with the fixing belt, and has a conveying path switching unit that switches and a control unit that controls the operation of the conveying path switching unit. The toner image is heated and pressed while the sheet-shaped recording medium is conveyed under pressure. The pressure roller of the first fixing device has a flexible structure including a light emitting portion and a light receiving portion formed of optical fibers. A surface layer made of an elastic body, a shaft core that reflects light, and a hollow portion formed by the surface layer and the shaft core, and the hollow portion is configured to be filled with gas at a constant pressure. , Sensing the light receiving part , Depending on the state, by the control means, to provide an electrophotographic forming method characterized by switching the conveying path.

According to a twenty-first aspect of the invention, depending on the state of the light receiving portion of the pressure roller of the first fixing device,
The distance between the surface layer and the shaft core is detected, and when a specific distance is reached, a switch for heating the fixing roller or fixing belt of the second fixing device in the latter stage of the first fixing device is turned on. An electrophotographic forming method is provided.

The invention according to claim 22 provides the electrophotographic forming method, wherein the gas filled in the hollow portion is an inert gas.

According to the present invention, the fixing failure due to the temperature decrease due to the insertion of the paper is caused by raising the temperature of the fixing belt, operating the mechanism for decreasing the rotational speed of the fixing belt and the pressure roller, or nip. It can be avoided by increasing the time.

[0042]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, specific embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the examples shown below.

(Embodiment 1) FIG. 1 is a schematic sectional view of a main part of a belt fixing device 10 according to the present invention. The belt fixing device 10 includes a fixing belt 15, a heater 11 serving as a heating source, a fixing roller 14, a heating roller 12, and a pressure roller 13. Fixing belt 15
As shown in FIG. 1, is a rotatable fixing roller 14 and a heating roller 1 having a function of heating and tensioning roller.
It is stretched between 2 and. The fixing roller 14 is rotationally driven by a drive source such as a motor (not shown), so that the fixing belt 15 can be stably rotated without slipping or loosening. Further, the heating roller 12 and the pressure roller 13 are driven to rotate by the rotation of the fixing belt 15.

FIG. 2 is a cross-sectional view of the main part of the fixing device according to claim 1 of the present application, which is perpendicular to the axial direction near the axial center. FIG. 2A is an enlarged view of a region surrounded by a chain line in FIG. Reference numerals 11 to 15 in FIGS. 2A and 2B indicate common portions with the corresponding portions in FIG. Reference numeral 16 is an elastic body, which is formed by applying, for example, silicone rubber or the like. Reference numeral 17 is a metal thin film coated on the elastic body 16. The metal thin film 17 can be formed by a known sputtering method or the like. The elastic body 16 and the metal thin film 17 form the surface layer 21 shown in FIG.

The space 18 is filled with a predetermined gas, the temperature of the fixing belt 15 is the temperature at the time of fixing, and when the pressure roller 13 is in pressure contact with the fixing belt 15, the filling is most filled. It is inflated so that the surface of the elastic body 16 is the most stretched at that time. At the time of copying, heat is taken by the paper, and the temperature of the pressure roller 13 drops. Then, the filled gas contracts. Since the fixing belt 15 and the pressure roller 13 are in pressure contact with each other and the elastic body 16 is flexible, the metal thin film 17 and the shaft core 19 are different from each other in FIG.
Contact as shown in. Since the shaft core 19 is made of metal, various operations are started by using these contacts as switches. That is, the predetermined operation is started depending on the actual temperature of the nip portion.

Reference numeral 20 is a spacer interposed in the space 18, and is preferably a columnar shape formed of a flexible and elastic material such as sponge. At the spacer 20 portion, both metals of the metal thin film 17 and the shaft core 19 are in non-contact, but if they are not in contact for a certain specific time or more, it is considered that they are in contact. FIG. 4 shows a process flowchart of the fixing operation when the fixing device of the present invention is used.

(Embodiment 2) FIG. 5 is a schematic sectional view of a main part of the fixing device 30 according to claim 2 of the present application. The details of the pressure roller 13 are omitted in FIG.
In the fixing device 30 shown in FIG. 5, the heater 11 and the pressure roller 13 of the heating roller 12 are arranged in the temperature control circuit 3
1 and is controlled to a predetermined temperature. As in the above-described (Example 1), when the temperature of the fixing belt 15 is the temperature at the time of fixing (when there is no paper), the filling material in the space of the pressure roller 13 is the most expanded, and at that time, The surface of the elastic body 16 is made to be the most tense.

At the time of copying, heat is taken by the paper and the temperature of the pressure roller 13 drops. When the temperature of the surface of the pressure roller 13 decreases, the filler in the space 18 contracts, and the coated metal thin film 17 and the shaft core 19 come into contact with each other. The temperature control circuit 31 is operated so as to raise the temperature of the fixing belt 15 by using such a contact between both metals as a switch. By doing so, the temperature of the fixing belt 15 can be increased by the actual temperature of the nip portion, and the fixing failure due to the temperature decrease can be effectively avoided. FIG. 6 shows a flowchart of the steps of the fixing operation when the fixing device 30 is used.

(Embodiment 3) FIG. 7 shows a cross-sectional view of an essential part of the fixing device 60 according to the third aspect of the present invention, which is perpendicular to the axial direction near the axial center. In FIG. 7, the detailed structure of the pressure roller 13 is omitted.

Similar to the above-described (Embodiment 1), when the temperature of the fixing belt 15 is the temperature at the time of fixing (when there is no paper) and the pressure roller 13 is in pressure contact with the fixing belt 15, charging is performed. The thing is made to expand most, and the surface of the elastic body 16 is made to be the most tense at that time. At the time of copying, heat is taken by inserting a sheet, and the temperature of the pressure roller 13 drops. Then, the filled gas contracts.
Since the fixing belt 15 and the pressure roller 13 are pressed against each other and the elastic body 16 is flexible, the metal thin film 17 and the shaft core 19 are in contact with each other. Since the surface of the shaft core 19 is made of metal, the heating lamp 61 around the fixing belt 15 is operated by using this contact as a switch to operate the heating lamp control circuit 61 for irradiating the fixing belt 15 and the like. By doing so, the fixing belt 15 can be heated according to the actual temperature of the nip portion, and the defective fixing can be effectively avoided. FIG. 8 shows a flowchart of the fixing process when the fixing device 60 shown in FIG. 7 is used.

(Embodiment 4) FIG. 9 shows a sectional view of the essential parts of a fixing device 40 according to a fourth aspect of the present invention. In FIG. 9, details of the pressure roller 13 are omitted. In the fixing device 40 shown in FIG. 9, the pressure roller 13 and the fixing roller 14 are connected to a rotation speed control circuit 41, which controls the fixing belt 15 to have a predetermined rotation speed.

Similar to the above-described (Embodiment 1), when the temperature of the fixing belt 15 is the temperature at the time of fixing (when there is no paper), the filling material in the space 18 of the pressure roller 13 is the most expanded. At that time, the surface of the elastic body 16 is made to be the most stretched. At the time of copying, heat is taken away by inserting a sheet, and the temperature of the pressure roller 13 drops. When the temperature of the surface of the pressure roller 13 decreases, the filling material in the space 18 contracts, and the coated metal thin film 17 and the shaft core 19 come into contact with each other. This is used as a switch to operate the rotation speed control circuit 41 so as to reduce the rotation speed of the fixing belt 15. By doing this, the nip time can be adjusted according to the actual change in the temperature of the nip part,
It is possible to effectively avoid the fixing failure due to the temperature decrease. FIG. 10 shows a process flowchart of the fixing operation when the fixing device 40 is used.

(Embodiment 5) FIG. 11 shows claim 5 of the present application.
3 is a schematic sectional view of a main part of the fixing device 50 in FIG. Figure 1
1, the detailed structure of the pressure roller 13 is omitted. In the fixing device 50 shown in FIG. 11, the heating roller 12, the pressure roller 13 and the fixing roller 14 are connected to the pressure contact force control circuit 51, whereby the fixing belt 15 and the pressure roller 13 are pressed against each other. Power is controlled.

Similar to the above-described (Embodiment 1), when the temperature of the fixing belt 15 is at the fixing temperature (when there is no paper), the filling material in the space 18 of the pressure roller 13 is the most expanded. At that time, the surface of the elastic body 16 is made to be the most stretched. At the time of copying, heat is taken away by the paper, so that the temperature of the pressure roller 13 decreases. Pressure roller 1
When the temperature of the surface of 3 decreases, the filling material of the space 18 contracts, and the coated metal thin film 17 and the shaft core 19 come into contact with each other. This is used as a switch to operate the pressure contact force control circuit 51 that increases the pressure contact force between the fixing belt 15 and the pressure roller 13. By doing so, the nip pressure is adjusted in accordance with the actual temperature of the nip portion, and fixing failure can be effectively avoided. FIG. 12 shows a process flow chart of the fixing operation when the fixing device 50 of FIG. 11 is used.

(Embodiment 6) FIG. 13 shows a sectional view of another example of the fixing device of the present invention in the vicinity of the axial center and perpendicular to the axial direction. 13, the detailed structure of the pressure roller 13 is omitted. The fixing device 70 of FIG.
In the above, the heater 11 and the pressure roller 13 of the heating roller are connected to the temperature control circuit 31, which controls the temperature of the fixing belt 15. Further, the pressure roller 13 and the fixing roller 14 are connected to a rotation speed control circuit 41, which controls the fixing belt 15 to have a predetermined rotation speed.

As in the above-described (Embodiment 1), when the temperature of the fixing belt 15 is the temperature at the time of fixing (when there is no paper) and the pressure roller 13 is in pressure contact with the fixing belt 15, the charging is performed. The thing is made to expand most, and the surface of the elastic body 16 is made to be the most tense at that time. At the time of copying, heat is taken by inserting a sheet, and the temperature of the pressure roller 13 is lowered. Then, the filled gas contracts.
Since the fixing belt 15 and the pressure roller 13 are pressed against each other and the elastic body 16 is flexible, the metal thin film 1
7 and the shaft core 19 contact each other. Since the surface of the shaft core 19 is metal, this contact is used as a switch, as shown in FIG. 13 (however, the detailed configuration of the pressure roller 13 is omitted),
The temperature of the fixing belt 15 is raised by the temperature control circuit 31, and the rotation speeds of the fixing belt 15 and the pressure roller 13 are reduced by the rotation speed control circuit 41. That is, the temperature of the fixing belt 15 can be raised in accordance with the actual temperature of the nip portion to control the nip pressure, and the fixing failure can be effectively avoided.

By the way, if the temperature of the fixing belt 15 is raised, it is possible to prevent the fixing failure due to the temperature decrease caused by passing the paper through. However, since the fixing belt 15 has a predetermined heat capacity, it is immediately The temperature does not rise.
On the other hand, since the rotation speed of the roller can be immediately reduced, the nip time can be lengthened, which has an immediate effect. However, this alone is not enough to prevent defective fixing. Therefore, as in the fixing device 70 shown in FIG. 13, by combining the temperature increase of the fixing belt 15 by the temperature control circuit 31 and the decrease of the rotation speeds of the fixing belt 15 and the pressure roller 13 by the rotation speed control circuit 41, It is possible to more reliably prevent defective fixing. That is, it is possible to prevent the fixing failure depending on the actual temperature of the nip portion. FIG. 14 shows a flowchart of a fixing process when the fixing device 70 of FIG. 13 is used.

(Embodiment 7) FIG. 15 is a sectional view of another example of the fixing device of the present invention, which is perpendicular to the axial direction near the axial center. In FIG. 15, the detailed structure of the pressure roller 13 is omitted. In the fixing device 80 of FIG. 15, the heater 11 of the heating roller and the pressure roller 13 are connected to the temperature control circuit 31 to control the temperature of the fixing belt 15. Also,
The pressure roller 13 and the fixing roller 14 are connected to a pressure contact force control circuit 51, whereby the fixing belt 15
The pressure contact force between the pressure roller 13 and the pressure roller 13 is controlled.

As in the first embodiment, when the temperature of the fixing belt 15 is the temperature at the time of fixing (without paper) and the pressure roller 13 is in pressure contact with the fixing belt 15, the filling gas is the most It is expanded so that the surface of the pressure roller 13 is the most stretched at that time. Due to the temperature drop of the pressure roller 13 due to the insertion of the material to be heated, the shaft core 19 of the pressure roller 13
The gas between the elastic body 16 and the elastic body 16 contracts, and the two metals come into contact with each other. Using this as a switch, the temperature of the fixing belt 15 is raised and the pressure contact force control circuit 51 for increasing the pressure contact force between the fixing belt 15 and the pressure roller 13 is operated to prevent fixing failure.

Raising the temperature of the fixing belt 15 prevents the fixing failure due to the temperature decrease caused by the passage of paper, but since the fixing belt 15 has a predetermined heat capacity,
The temperature does not rise immediately. On the other hand, since the pressure contact force can be immediately increased, increasing the nip pressure is superior in terms of immediate effect, but this alone is not sufficient to prevent defective fixing. Therefore, FIG.
As in the fixing device 80 shown in FIG. 2, by combining the temperature increase of the fixing belt 15 by the temperature control circuit 31 and the increase of the pressure contact force between the fixing belt 15 and the pressure roller 13 by the pressure contact force control circuit 51, it is possible to more reliably. Fixing failure can be prevented. That is, it is possible to effectively avoid the defective fixing depending on the actual temperature of the nip portion. FIG. 16 shows a flowchart of a fixing process when the fixing device 80 shown in FIG. 15 is applied.

(Embodiment 8) FIG. 17 shows a schematic sectional view of another example of the fixing device of the present invention. As in the above-described (Embodiment 1), the temperature of the fixing belt 15 is the temperature at the time of fixing (when there is no paper), and the gas filled when the pressure roller 13 is in pressure contact with the fixing belt 15. Is the most expanded and the surface of the pressure roller 13 is the most expanded at that time. Due to the temperature drop of the pressure roller 13 due to the insertion of the material to be heated, the shaft core 19 of the pressure roller 13 and the elastic body 1
The gas between 6 and 6 contracts, and both metals contact. Using this as a switch, the heating lamp 62 around the fixing belt 15 and the pressure roller 13 or around the fixing belt 15 or the pressure roller 13 is operated to heat the fixing belt 15 and to press the fixing belt 15 and the pressure. The rotation speed control circuit 41 that reduces the rotation speed of the roller 13 is operated to lengthen the nip time and prevent fixing failure.

The heating lamp 62 is heated to fix the fixing belt 1.
Raising the temperatures of the pressure roller 5 and the pressure roller 13 prevents the fixing failure due to the temperature decrease caused by the passing of paper, but since the fixing belt 15 and the pressure roller 13 have a predetermined heat capacity, they are immediately The temperature does not rise. On the other hand, since the rotation speed of the roller can be immediately reduced, the nip time can be lengthened and the immediate effect is excellent, but this alone is not sufficient to prevent defective fixing. Therefore, in the fixing device 90 shown in FIG. 17, the temperature rises of the fixing belt 15 and the pressure roller 13, and the fixing belt 15 and the pressure roller 1
By combining the reduction of the rotation speed of 3, it is possible to more reliably avoid the occurrence of fixing failure. By doing so, it is possible to effectively avoid the fixing failure in accordance with the actual temperature of the nip portion. FIG. 18 shows a flowchart of a fixing process when the fixing device 90 shown in FIG. 17 is applied.

(Embodiment 9) FIG. 19 shows a schematic sectional view of another example of the fixing device of the present invention. Similar to the above-described (Embodiment 1), the temperature of the fixing belt 15 is the temperature at the time of fixing (when there is no paper), and the pressure roller 13 is the fixing belt 15.
The gas filled therein is the most expanded when it is pressed against, and the surface of the pressure roller 13 is made the most expanded at that time. Due to the temperature drop of the pressure roller 13 due to the insertion of the material to be heated, the gas between the shaft core 19 of the pressure roller 13 and the elastic body 16 contracts and both metals come into contact with each other. Using this as a switch, the heating lamp 62 around the fixing belt 15 and the pressure roller 13 or around the fixing belt 15 or the pressure roller 13 is operated, and the pressure contact force between the fixing belt 15 and the pressure roller 13 is reduced. The pressure contact force control circuit 51 to be increased is operated to prevent defective fixing.

The heating lamp 62 is heated to fix the fixing belt 1.
Raising the temperatures of the pressure roller 5 and the pressure roller 13 prevents the fixing failure due to the temperature decrease caused by the passing of paper, but since the fixing belt 15 and the pressure roller 13 have a predetermined heat capacity, they are immediately The temperature does not rise. On the other hand, since the pressure contact force is immediately increased, increasing the nip pressure is excellent in terms of immediate effect, but this is not enough to prevent improper fixing. Therefore, by combining the temperature rise of the fixing belt 15 and the pressure roller 13 and the pressure contact force increase of the fixing belt 15 and the pressure roller 13,
It was decided to prevent the fixing failure more reliably. By doing so, it is possible to prevent the fixing failure corresponding to the actual temperature of the nip portion. FIG. 20 shows the fixing device 10 shown in FIG.
The flowchart of the fixing process when 0 is applied is shown.

(Embodiment 10) FIG. 21 is a schematic structural diagram of a fixing device 110 according to the sixth aspect of the invention. In this example, a sheet-shaped recording medium has a first fixing device 111 for fixing an unfixed toner image, and a second fixing device 112 provided at a stage subsequent to the first fixing device 111. is doing. First fixing device 111 and second fixing device 1
12, a sheet-shaped recording medium conveyance path, an unloading path (B side), and a path (A) toward the second fixing device 112.
It is assumed to have a transport path switching means (not shown) for switching between the above and the other side) and a control means (not shown) for controlling the operation of this transport path switching means. The first fixing device 111 includes the fixing belt 15 and the fixing belt 15
And a pressure roller 13 that rotates in pressure contact with the sheet, and heats and presses the toner image while the sheet-shaped recording medium is conveyed under pressure. The pressure roller 13 of the first fixing device 111 is used.
It is assumed that the control means switches the transport route according to the state detected by the sensor provided in the.

The first fixing device 111 shown in FIG. 21 has the same structure as the belt fixing device 10 shown in FIG.
That is, the fixing belt 15 and the heater 1 serving as a heating source.
1, fixing roller 14, heating roller 12, pressure roller 13
It is composed by. The fixing belt 15 is stretched between the rotatable fixing roller 14 and the heating roller 12 which is a heating / tensioning roller. The fixing roller 14 is rotationally driven by a drive source such as a motor (not shown), and the fixing belt 15 is stably rotated without slipping or loosening. Further, the heating roller 12 and the pressure roller 13 are driven to rotate by the rotation of the fixing belt 15.

The pressure roller 13 constituting the first fixing device 111 of FIG. 21 has the same structure as that shown in FIGS. 2 (a) and 2 (b). That is, the elastic body 16 and the metal thin film 17 are arranged to face the shaft core 19 with the spacer 20 interposed in the space 18. The space 18 is filled with gas, and the temperature of the fixing belt 15 is the temperature at the time of fixing (without paper),
When the pressure roller 13 is in pressure contact with the fixing belt 15, the filling is expanded most, and the surface of the elastic body 16 is stretched most at that time. At the time of copying, heat is taken by the paper, and the temperature of the pressure roller 13 drops. Then, the filled gas contracts. Since the fixing belt 15 and the pressure roller 13 are pressed against each other and the elastic body 16 is flexible, the metal thin film 17 and the shaft core 19 are in contact with each other. Since the surface of the shaft core 19 is made of metal, contact between these two metals serves as a switch. The two parts of the spacer 20 are not in contact with each other, but if they are not in contact for a certain period of time, they are considered to be in contact with each other.

The contact between the surface layer of the pressure roller 13 of the first fixing device 111 and the shaft core 19 described above is used as a switch, and the second fixing device positioned after the first fixing device 111 is used. A mechanism for guiding the material to be heated to 112 is operated. Specifically, when the switch is turned on as described above, the sheet guide 133 is moved to the A side by the solenoid 136 and the spring 135, and the fixing roller 13 of the second fixing device 112 is moved.
It is guided to the second fixing device 112 composed of 1 and the pressure roller 132. The fixing roller 131 has a heating element inside. The material to be heated is the first fixing device 11
The second fixing device 11 is heated by 1, and the temperature is increased.
Since it is heated again by 2, the fixing failure can be prevented.

As described above, the operation can be started depending on the temperature of the nip portion of the first fixing device 111. Although the second fixing device 112 is a fixing roller here, a fixing belt may be applied.

(Embodiment 11) FIG. 22 shows a sectional view of the essential part of another example of the fixing device of the present invention. Above (Example 1
As in the case of the fixing device 110 of 0), the contact state between the metal thin film on the surface of the pressure roller 13 of the first fixing device 111 and both metals of the shaft core is detected, and it is in the latter stage of the first fixing device 111. The heater of the fixing roller 141 of the second fixing device 112 is turned on. Since the material to be heated is heated by the first fixing device 111 and is heated again by the fixing roller 141 of the second fixing device 112 while the temperature is rising, the occurrence of defective fixing can be effectively avoided. The fixing roller 141 of the second fixing device 112 is turned on only when the switch is turned on.
Is heated, the power consumption is reduced as compared with the above-described (Example 10). FIG. 23 shows a flowchart of a fixing process when the fixing devices 110 and 120 shown in FIGS. 21 and 22 are used. Although the fixing roller 131 is applied to the second fixing device 112 in the fixing device 110 shown in FIG. 22, a fixing belt may be used.

(Embodiment 12) In the invention according to claim 7, the shaft core 19 constituting the fixing device shown in each of the above embodiments is formed of a non-conductive material. According to this, the manufacturing cost of the fixing device can be reduced, and the shaft core 19
Good switch characteristics can also be ensured by coating with a thin metal layer.

(Embodiment 13) In the invention according to claim 8, the gas filled in the space 18 constituting the fixing device shown in each of the above-mentioned embodiments is an inert gas. By doing so, good switching is possible without corrosion even when exposed to high temperatures.

(Embodiment 14) FIG. 24 shows a belt fixing device which constitutes a main part of a fixing device according to the inventions of claims 6 and 9 and an electrophotographic apparatus according to the inventions of claims 12 and 13. A schematic cross-sectional view of 200 is shown.

As shown in FIG. 24, the belt fixing device 200
Is a fixing belt 205 and a heater 20 serving as a heating source.
1, a fixing roller 204, a heating roller 202, and a pressure roller 203. Fixing belt 205
Is stretched between a rotatable fixing roller 204 and a heating roller 202 having a heating function and a tension function. The fixing roller 204 is rotationally driven by a drive source such as a motor (not shown), and the fixing belt 205 is stably rotated without slipping or loosening. Further, the fixing belt 20
By the rotation of 5, the heating roller 202 and the pressure roller 203
Is driven to rotate.

25 (a) and 25 (b), in the axial direction near the axial center of the main part of the pressure roller 203 of the fixing device and the first fixing device constituting the electrophotographic apparatus in this example. A vertical sectional view is shown. Note that FIG.
It is an enlarged view of the area | region b enclosed with the dashed line in (b).

Reference numeral 206 in FIGS. 25A and 25B denotes an elastic body (surface layer), which is made of, for example, silicon rubber or the like. Reference numeral 207 denotes an optical fiber, which is composed of one light emitting optical fiber 207a and a plurality of light receiving optical fibers 207b in the elastic body 206 (surface layer). The light emitted from the light emitting optical fiber 207a is reflected by the shaft core 209 and is detected by a predetermined optical fiber among the light receiving optical fibers 207b through the opening 211h of the light shielding plate 211. Using these optical fibers, the width of the hollow portion 208 is measured by utilizing triangulation used for autofocus of a camera. The optical fiber 207a for light emission is LE
A distance sensor or the like is applied to the optical fiber 207b for receiving light such as D. Since the pressure roller 203 has a high temperature to some extent, the light from the LED or the like at room temperature is carried by the optical fiber, and the reflected light is received by the light receiving optical fiber 207b to perform various processes. Since the pressure roller 203 rotates, pay attention to how to attach the optical fiber 207.

The hollow portion 208 is filled with a predetermined gas, the temperature of the fixing belt 205 is the temperature at the time of fixing (there is no paper), and the pressure roller 203 causes the fixing belt 20 to rotate.
The gas filled is most expanded when it is pressed against 5, and the surface of the elastic body 206 (surface layer) is made the most expanded at that time.

At the time of copying, heat is taken by the paper and the temperature of the pressure roller 203 gradually decreases. Then the hollow part 208
The gas filled in is gradually contracted. Fixing belt 2
05 and the pressure roller 203 are in pressure contact with each other, and since the elastic body 206 (surface layer) is easily deformed, the distance between the optical fiber 207 and the shaft core 209 is shortened as shown in FIG. In this way, the optical fiber 207 and the shaft core 209
Is detected by the light receiving section of the optical fiber 207 (a detection mechanism will be described later with reference to FIG. 27), and the distance between the elastic body 206 (surface layer) and the shaft core 209 becomes a certain value. When it becomes, switch on. Note that 210 is a columnar spacer, and is formed of a soft and elastic sponge or the like.

Next, the detection mechanism of the optical fiber 207 will be described with reference to FIG. 27 (a)
Shows a state when the gas filled in the hollow portion 208 is expanded, and FIG. 27B shows a state when the gas filled in the hollow portion 208 is contracted. When the paper is inserted into the nip, the heat of the pressure roller 203 is taken by the paper, and the hollow portion 208 contracts, and the interval is narrowed as shown in FIG. 27B.

As shown in FIG. 27, the light emitted from the light emitting optical fiber 207a is reflected by the shaft core 209,
From the opening 211h of the light shielding plate 211 to the light receiving optical fiber 2
It is incident on 07b. As shown in FIG. 27 (b), the hollow portion 2
When the gas of 08 contracts and the width is narrowed, the reflected light is incident on only the optical fiber installed at the end of the light receiving optical fiber 207b from the opening 211h, as shown in FIG. 27 (b). To be done. That is,
The width of the hollow portion 208 can be detected by detecting which of the plurality of light receiving optical fibers 207b has received light.

Next, the operation principle of the fixing device according to claims 6 and 9 and the electrophotographic apparatus according to claims 12 and 13 will be described with reference to the drawings. FIG. 28 is a schematic view of the fixing device of the present invention and the fixing device constituting the essential part of the electrophotographic apparatus of the present invention. In this example, a first fixing device 221 for fixing the toner image on the sheet-shaped recording medium and a second fixing device 222 provided at the subsequent stage of the first fixing device 221 are provided. Between the first fixing device 221 and the second fixing device 222, a sheet-shaped recording medium conveying path is provided with a carry-out path (B side) and a path toward the second fixing apparatus 222 (A side). It is assumed to have a transport path switching means (not shown) for switching between the two and a control means (not shown) for controlling the operation of the transport path switching means. The first fixing device 221 includes a fixing belt 205 and a pressure roller 203 that rotates in pressure contact with the fixing belt 205. The first fixing device 221 heats and presses a toner image while nipping and conveying a sheet-shaped recording medium. ,
It is assumed that the control unit switches the transport path according to the state detected by the sensor provided on the pressure roller 203 of the first fixing device 221.

The first fixing device 221 has the same structure as the belt fixing device shown in FIG. That is, the fixing belt 205, the heater 201 serving as a heating source, the fixing roller 204, the heating roller 202, and the pressure roller 203 are included. The pressure roller 203 that constitutes the first fixing device 221 is assumed to have the configuration shown in FIGS. 25 to 27. That is, the elastic body 206 and the shaft core 20
9 are arranged so as to face each other by a spacer 210 via a hollow portion 208.

The hollow portion 208 is filled with gas,
When the temperature of the fixing belt 205 is the temperature at the time of fixing (no paper), and the pressure roller 203 is in pressure contact with the fixing belt 205, the filler is most expanded, and at that time, the surface of the elastic body 206 is inflated. To be the most tense. At the time of copying, heat is taken by the paper and the temperature of the pressure roller 203 decreases. Then, the filled gas contracts.

In the fixing device having such a structure, as shown in FIG.
7 (a) and the mechanism shown in FIG. 27 (b), the distance between the surface layer of the pressure roller 203 of the first fixing device 221 and the shaft core 209 is detected, and the switch is turned on according to the distance. The second fixing device 221 is provided in the second stage after the first fixing device 221.
The mechanism for guiding the material to be heated to the fixing device 222 is operated.

Specifically, the surface layer of the pressure roller 203,
When the switch is turned on according to the distance from the shaft core 209, the paper guide 233 causes the solenoid 236 and the spring 235 to move to the A position.
The fixing roller 231 and the pressure roller 232 in the rear stage.
Is guided to the second fixing device 222. The fixing roller 231 has a heating element inside.
The pressure roller 232 of the second fixing device 222 may have a general structure. The material to be heated is heated by the first fixing device 221, and is heated again by the second fixing device 222 while the temperature is rising, so that fixing failure can be prevented. By doing so, the operation can be started depending on the actual temperature of the nip portion of the first fixing device 221. Although the second fixing device 222 is the fixing roller 231 here, it may be a fixing belt.

(Embodiment 15) Next, the fixing device of claim 10, the electrophotographic device of claim 14, the fixing method of claims 17 and 18, and the electrophotographic forming method of claims 20 and 21 will be described with reference to the drawings. Explain.

In this example, FIG. 27 (a) described above is used.
And by the mechanism shown in FIG. 27 (b),
Of the pressure roller 203 of the fixing device 221 and the shaft core 20
9 is detected, and the heater (not shown) of the fixing roller 231 of the second fixing device 222 in the latter stage of the first fixing device 221 is turned on. The material to be heated is heated by the first fixing device 221, and is heated again by the fixing roller 231 of the second fixing device 222 while the temperature is rising, so that defective fixing can be prevented. Further, since the fixing roller 231 of the second fixing device 222 is heated only when the switch is turned on, the power consumption can be reduced.

FIG. 30 shows a flow chart of a fixing process when the fixing device shown in FIG. 29 is used. Although the fixing roller 231 is applied to the second fixing device 222 in the fixing device shown in FIG. 29, a fixing belt may be used.

(Embodiment 16) In the fixing device according to claim 11, the electrophotographic device according to claim 15, the fixing method according to claim 19, and the electrophotographic forming method according to claim 22, a fixing device is constituted. The gas filled in the hollow portion 209 is an inert gas. As a result, it functions as a good light medium without being corroded even when exposed to high temperatures.

(Embodiment 17) An image forming apparatus according to a sixteenth aspect of the present invention is directed to a photoconductor, means for forming an electrostatic latent image on the photoconductor, toner formed by developing the formed electrostatic latent image. Image developing means, transfer means for transferring the toner image formed on the photoreceptor to a sheet-shaped recording medium directly or via an intermediate transfer medium, and the toner image transferred to the recording medium on the recording medium. The fixing device according to the present invention is applied as the fixing device. According to this, it is possible to achieve good fixing and good image formation.

[0091]

According to the present invention, various operations can be started and ended at the actual temperature of the nip portion.

According to the present invention, the fixing failure due to the temperature decrease (monitoring at the nip portion) due to the insertion of the paper can be prevented by increasing the temperature of the fixing belt.

According to the present invention, the fixing failure due to the temperature decrease (monitoring at the nip portion) due to the insertion of the paper can be prevented by decreasing the rotation speed of the fixing belt.

According to the present invention, the fixing failure due to the temperature decrease (monitoring at the nip portion) due to the insertion of the paper can be prevented by increasing the pressure contact force between the fixing belt and the pressure roller.

According to the present invention, even when the shaft core is non-conductive, by coating the shaft core with a metal thin film,
The manufacturing cost was reduced and good switching was possible.

According to the present invention, by making the gas filled in the hollow portion an inert gas, good switching can be performed without corrosion even when exposed to high temperature.

According to the present invention, the fixing failure due to the temperature drop (monitoring at the nip portion) due to the insertion of the paper can be prevented by turning on the heating lamp around the fixing belt and raising the belt temperature. .

According to the present invention, the fixing failure due to the decrease in the temperature of the nip of the first fixing device due to the insertion of the paper is heated by the fixing roller of the second fixing device arranged in the subsequent stage of the first fixing device. , Could be avoided by passing the material to be heated there.

According to the image forming apparatus of the present invention, good fixing can be realized and good image formation can be realized.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a belt fixing device of the present invention.

FIG. 2A is a cross-sectional view perpendicular to the axial direction near the axial center of the main part of the pressure roller of the fixing device. (B) A schematic configuration diagram of a pressure roller constituting the fixing device of the present invention is shown.

FIG. 3 is a diagram showing a positional relationship between a pressure roller and a fixing belt which constitute the fixing roller of the present invention.

FIG. 4 shows a flowchart when the fixing device of the present invention is used.

FIG. 5 shows a schematic configuration diagram of a belt fixing device of the present invention.

FIG. 6 shows a flowchart when the fixing device of the present invention is used.

FIG. 7 is a schematic configuration diagram of a belt fixing device of the present invention.

FIG. 8 shows a flowchart when the fixing device of the present invention is used.

FIG. 9 shows a schematic configuration diagram of a fixing device of the present invention.

FIG. 10 shows a flowchart when the fixing device of the present invention is used.

FIG. 11 shows a schematic configuration diagram of a fixing device of the present invention.

FIG. 12 shows a flowchart of a fixing process when the fixing device of the present invention is used.

FIG. 13 shows a schematic configuration diagram of a fixing device of the present invention.

FIG. 14 shows a flowchart of a fixing process when the fixing device of the present invention is used.

FIG. 15 shows a schematic configuration diagram of a fixing device of the present invention.

FIG. 16 shows a flowchart of a fixing process when the fixing device of the present invention is used.

FIG. 17 shows a schematic configuration diagram of a fixing device of the present invention.

FIG. 18 shows a flowchart of a fixing process when the fixing device of the present invention is used.

FIG. 19 is a schematic configuration diagram of a fixing device of the present invention.

FIG. 20 shows a flowchart of a fixing process when the fixing device of the present invention is used.

FIG. 21 shows a schematic configuration diagram of a fixing device of the present invention.

FIG. 22 shows a schematic configuration diagram of a fixing device of the present invention.

FIG. 23 shows a flowchart of a fixing process when the fixing device of the present invention is used.

FIG. 24 is a schematic configuration diagram of another example of the fixing device of the present invention.

FIG. 25A is a schematic configuration diagram of a main part of a pressure roller that constitutes the fixing device and the electrophotographic apparatus of the present invention. (B) A schematic configuration diagram of a pressure roller constituting the fixing device of the present invention is shown.

FIG. 26 is a schematic configuration diagram of a pressure roller that constitutes the fixing device of the present invention.

FIG. 27A is a schematic configuration diagram of a main part of a pressure roller that constitutes the fixing device and the electrophotographic apparatus of the present invention. (B) A schematic configuration diagram of a main part of a pressure roller constituting the fixing device and the electrophotographic apparatus of the present invention is shown.

FIG. 28 is a schematic configuration diagram of a fixing device of the present invention.

FIG. 29 shows a schematic configuration diagram of a fixing device of the present invention.

FIG. 30 shows a flowchart of a fixing process when the fixing device of the present invention is used.

[Explanation of symbols]

10: Belt fixing device 11 ... Heating heater 12 ... Heating roller 13 ... Pressure roller 14 ... Fixing roller 15 ... Fusing belt 16 ... Elastic body 17 ... Metal thin film 18 ... space 19: Shaft core 20: Spacer 30: Fixing device 31 ... Temperature control circuit 40: Fixing device 41 ... Rotation speed control circuit 50: Fixing device 51 ... Pressure contact control circuit 60: Fixing device 61 ... Heating lamp control circuit 62 ... Heating lamp 70: Fixing device 80: Fixing device 90: Fixing device 100: Fixing device 110: Fixing device 111 ... First fixing device 112 ... Second fixing device 131: fixing roller 132 ... Pressure roller 133 …… Paper guide 136 ... Solenoid 200: Belt fixing device 201 ... Heating heater 202 ... Heating roller 203 ... Pressure roller 204 ... Fusing roller 205 ... Fusing belt 206 ... Elastic body 207a ... Optical fiber for light emission 207b ... Optical fiber for receiving light 208 ... Hollow part 209 ... Shaft core 210: Spacer 211 ... Shading plate 220: fixing device 221 ... First fixing device 222 ... Second fixing device 231 ... Fusing roller 232 ... Pressure roller 233 ... Paper guide 234 ... Conveyor roller 235 ...... spring

Claims (22)

[Claims] 1. A surface layer made of a flexible elastic body having an inner surface coated with a metal thin film, a metal shaft core, and a hollow space formed by the surface layer and the shaft core, The hollow space is filled with gas at a constant pressure, and a fixing device having a pressure roller that serves as a switch when each metal of the surface metal thin film and the shaft core comes into contact Is a belt fixing system. 2. The fixing device according to claim 1, wherein a switch for raising the temperature of the fixing belt is turned on when the two metals come into contact with each other. 3. A surface layer made of a flexible elastic body having an inner surface coated with a metal thin film, a metal shaft core, and a hollow space formed by the surface layer and the shaft core.
In a belt fixing device in which the space is filled with a gas having a constant pressure, the metal thin film and the metal shaft contact each other, so that the metal is distributed around the fixing belt and / or the pressure roller. The fixing device according to claim 1 or 2, wherein a heating lamp provided is operated to heat the fixing belt. 4. The fixing device according to claim 1, wherein a switch for reducing the rotation speed of the fixing belt is turned on when the two metals come into contact with each other. 5. The switch for increasing the pressure contact force between the fixing belt and the pressure roller when the both metals come into contact with each other is turned on. Fixing device. 6. A fixing device for fixing a toner image carried on a sheet-shaped recording medium to the sheet-shaped recording medium, the first fixing device for fixing an unfixed toner image on the sheet-shaped recording medium. And a second fixing device provided downstream of the first fixing device, and between the first fixing device and the second fixing device, and a conveyance path for the sheet-shaped recording medium is provided. The first fixing device comprises a fixing belt, and a conveyance route switching device for switching between a carry-out route and a route toward the second fixing device, and a control device for controlling the operation of the transportation route switching device. And a pressure roller that rotates in pressure contact with the fixing belt and heats and presses the toner image while conveying the sheet-shaped recording medium under pressure, and pressurizes the first fixing device. Deployed to Laura The detection state of the sensor, fixing device, characterized in that the said control means switches the transport path. 7. The fixing device according to claim 1, wherein the shaft core is non-conductive, and the shaft core is coated with a metal thin film. 8. The fixing device according to claim 1, wherein the gas filling the hollow space is an inert gas. 9. The pressure roller of the first fixing device comprises a surface layer made of a flexible elastic body having a light emitting portion and a light receiving portion made of optical fibers, a shaft core for reflecting light, and It has a hollow portion formed by the surface layer and the shaft core, the hollow portion is filled with a gas of constant pressure,
7. The fixing device according to claim 6, having a function of sensing a light receiving portion of the optical fiber. 10. The pressure roller of the first fixing device comprises:
A surface layer made of a flexible elastic body having a light emitting portion and a light receiving portion made of an optical fiber, a shaft core that reflects light, and a hollow portion formed by the surface layer and the shaft core, The hollow part is filled with gas at a constant pressure,
The state of the light receiving portion is detected by the fixing device having the function of sensing the light receiving portion of the optical fiber, the detection function is used as a distance sensor, and when the distance between the surface layer and the shaft core reaches a certain distance, 7. The fixing device according to claim 6, wherein a switch for heating a fixing roller or a fixing belt of the second fixing device provided at a stage subsequent to the first fixing device is turned on. 11. The gas filled in the hollow portion,
The fixing device according to claim 9, wherein the fixing device is an inert gas. 12. An electrophotographic apparatus comprising a fixing device for fixing a toner image carried on a sheet recording medium to the sheet recording medium, wherein an unfixed toner image is fixed on the sheet recording medium. A first fixing device for fixing, a second fixing device provided at a stage subsequent to the first fixing device, and provided between the first fixing device and the second fixing device, The sheet-shaped recording medium has a transport path switching means for switching the transport path between the carry-out path and the path toward the second fixing device, and a control means for controlling the operation of the transport path switching means. The first fixing device includes a fixing belt and a pressure roller that rotates in pressure contact with the fixing belt, and heats and presses the toner image while conveying the sheet-shaped recording medium under pressure. The first The detection state of the sensors deployed pressure roller wearing device, an electrophotographic apparatus, characterized in that the said control means switches the transport path. 13. The pressure roller of the first fixing device comprises:
A surface layer made of a flexible elastic body having a light emitting portion and a light receiving portion made of an optical fiber, a shaft core that reflects light, and a hollow portion formed by the surface layer and the shaft core, The hollow portion is filled with a gas having a constant pressure,
The electrophotographic apparatus according to claim 12, further comprising a fixing device having a function of sensing a light receiving portion of the optical fiber. 14. The pressure roller of the first fixing device comprises:
A surface layer made of a flexible elastic body having a light emitting portion and a light receiving portion made of an optical fiber; a shaft core that reflects light; and a hollow portion formed by the surface layer and the shaft core. The hollow portion is filled with a gas having a constant pressure, the state of the light receiving portion is detected by a fixing device having a function of sensing the light receiving portion of the optical fiber, and the detection function is used as a distance sensor. When the distance between the surface layer and the shaft core reaches a certain distance, a switch for heating the fixing roller or the fixing belt of the second fixing device in the subsequent stage of the first fixing device is turned on. 13. A fixing device comprising:
The electrophotographic apparatus according to 1. 15. The electrophotographic apparatus according to claim 12, further comprising a fixing device characterized in that the gas filled in the hollow portion is an inert gas. 16. A photoconductor, means for forming an electrostatic latent image on the photoconductor, developing means for developing the formed electrostatic latent image into a toner image, and a photoconductor formed on the photoconductor. An image forming apparatus having a transfer unit that transfers a toner image directly to a sheet-shaped recording medium or via an intermediate transfer medium, and a fixing unit that fixes the toner image transferred to the recording medium to the recording medium. An image forming apparatus using the fixing device according to claim 1 as a unit. 17. A fixing method using a fixing device for fixing a toner image carried on a sheet-shaped recording medium to the sheet-shaped recording medium, wherein the fixing device is an unfixed toner image on the sheet-shaped recording medium. A first fixing device for fixing the first fixing device, a second fixing device provided at a stage subsequent to the first fixing device, and the first fixing device.
Between the fixing device and the second fixing device.
The first fixing device has a fixing belt and a pressing contact with the fixing belt. The first fixing device has a conveying path switching means for switching between a path toward the fixing device and a control means for controlling the operation of the conveying path switching means. And a rotating pressure roller, which heats and presses the toner image while conveying the sheet recording medium under pressure, and the pressure roller of the first fixing device is an optical fiber that emits light. A surface layer made of a flexible elastic body having a portion and a light receiving portion, a shaft core that reflects light, and a hollow portion formed by the surface layer and the shaft core, the hollow portion A fixing method characterized by being configured to be filled with a gas of a constant pressure, sensing the light receiving portion of the optical fiber, and switching the transport path by the control means according to the state thereof. Law. 18. The distance between the surface layer and the shaft core is detected by the state of the light receiving portion of the optical fiber forming the pressure roller of the first fixing device, and the first fixing device is detected when a specific distance is reached. 18. The fixing method according to claim 17, wherein a switch for heating the fixing roller or the fixing belt of the second fixing device in the subsequent stage is turned on. 19. The fixing method according to claim 17, wherein the gas filling the hollow portion is an inert gas. 20. An electrophotographic forming method using an electrophotographic apparatus comprising a fixing device for fixing a toner image carried on a sheet-shaped recording medium to the sheet-shaped recording medium, wherein the fixing device is sheet-shaped. A first fixing device for fixing an unfixed toner image on a recording medium; a second fixing device provided after the first fixing device;
Between the fixing device and the second fixing device.
The first fixing device has a fixing belt and a pressing contact with the fixing belt. The first fixing device has a conveying path switching means for switching between a path toward the fixing device and a control means for controlling the operation of the conveying path switching means. And a rotating pressure roller, which heats and presses the toner image while conveying the sheet recording medium under pressure, and the pressure roller of the first fixing device is an optical fiber that emits light. A surface layer made of a flexible elastic body having a portion and a light receiving portion, a shaft core that reflects light, and a hollow portion formed by the surface layer and the shaft core, the hollow portion, An electrophotographic forming method comprising a gas filled with a constant pressure, sensing the light receiving portion of the optical fiber, and switching the transport path by the control means according to the state. 21. The distance between the surface layer and the shaft core is detected according to the state of the light receiving portion of the pressure roller of the first fixing device, and when the distance reaches a specific distance, it is in the subsequent stage of the first fixing device. 21. The electrophotographic forming method according to claim 20, wherein a switch for heating the fixing roller or the fixing belt of the second fixing device is turned on. 22. The electrophotographic forming method according to claim 20, wherein the gas filling the hollow portion is an inert gas.