JP2941587B2 - Image heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image heating apparatus for heating an image on a recording material, and more particularly to an image heating apparatus suitable for an apparatus for heating and fixing an unfixed image on a recording material.

[0002]

[0003]

2. Description of the Related Art Conventionally, as an image heating apparatus for heating and fixing an unfixed image and improving the surface properties of an image, a heat roller for nipping and conveying a recording material supporting an image by a heating roller and a pressure roller is known. Although the heat roller method has been widely used, such a heat roller method has a problem that it takes a long time (so-called warm-up time) to heat the heat roller to a predetermined fixing temperature due to a large heat capacity of the heat roller. was there.

Therefore, in Japanese Patent Application Laid-Open No. 63-313182 and Japanese Patent Application Laid-Open No. 2-157878, a warm-up time is reduced by using a thermal head having a low heat capacity and a thin film which slides on the thermal head. A film fixing method has been proposed.

The above-mentioned heating apparatus is used in image forming apparatuses such as a copying machine, a laser beam printer, a facsimile, a micro film reader printer, an image display (display) device, and a recorder.
Recording materials (electrofax sheets, electrostatic recording sheets, transfer sheets, transfer sheets, etc.) using toner made of heat-meltable resin by appropriate image forming process means such as magnetic recording.
A visible image (unfixed toner image) corresponding to a target image formed on a surface of a printing paper or the like by a direct method or an indirect (transfer) method is heated as a permanently fixed image on a recording surface carrying the image. An image fixing device for performing a fixing process.

Further, this apparatus is not limited to an image fixing apparatus, and is widely used as a means or apparatus for heat-treating an image carrier, such as an apparatus for heating a recording material carrying an image to improve the surface properties. Things.

[0007]

However, according to the above conventional example, there are the following problems. A first problem relates to a cleaning roller as a cleaning member . In the above-described film heating method, a cleaner such as a felt roller may be brought into contact with a surface of the film in contact with a recording material or a surface of a pressure roller which comes into contact with a heater through the film in order to remove residual toner. is there.

However, according to the film type conventional apparatus in which the cleaner such as the felt roller is brought into contact, the time until the recording material is fixed after the start of energization is short, so that the pressure roller is prevented from being stained. Therefore, if the cleaning roller is always in contact with the pressure roller, the heat from the heater is transmitted to the pressure roller via the film and further transmitted to the cleaning roller. As a result, the temperature rise rate of the heater becomes smaller as compared with the case where there is no cleaning roller.
Therefore, in a low-temperature environment or when the input voltage is low, the first fixing process after the start of energization may be defective. If the cleaning roller is removed in order to prevent this type of fixing failure, the pressure roller may become dirty after long-term use, and the recording material may be soiled.

Further, when such a cleaning roller is provided, there is a problem that a so-called non-sheet-passing portion temperature rise occurs outside the recording material, and toner retransfer occurs. When the above-described apparatus is used for a long period of time, toner or the like adheres to the cleaning roller over the entire surface. Is generated, the temperature of the cleaning roller rises, and contaminants such as toner adhered to the surface of the cleaning roller are melted and transferred to the pressure roller. Immediately after that, if the recording material is changed from a small width recording material to a large width recording material and the fixing process is performed, contaminants transferred from the cleaning roller to the pressure roller adhere to the back surface of the recording material, and the recording material becomes dirty. There was a point.

[0010]

[0011]

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide a film-type image heating apparatus provided with a cleaning roller, which has a poor fixing property and a toner removed by a cleaning member.
An object of the present invention is to provide an image heating device that does not cause retransfer .

[0014]

[0015]

According to the present invention, the above object is achieved by firstly recording a heating member and rubbing the heating member.
Through a film member that moves with the material,
To form a nip for holding the recording material together with the heating member.
A recording member having a pressure member and a cleaning member for cleaning the pressure member;
Image heating device that heats the image on the recording material while nipping and transporting the material
Sheet when heating multiple recording materials continuously
During heating of the recording material, the cleaning member is separated from the pressing member.
And then contact the pressure member
This is achieved by the first invention .

Further, the above-mentioned object is to increase the temperature by energizing.
Moving with the recording material while rubbing against the heating member and the heating member
With the film member and the heating member via the film member
A pressure member for forming a nip for holding the recording material, and a pressure unit
Can be moved to the position where it comes into contact with the material and the position where it is separated from the pressure member
And a cleaning member for cleaning the pressing member.
Heating device that heats the image on the recording material while nipping and transporting
In the heating unit before energization to the heating member is started
The movement of the cleaning member after the start of energization is controlled according to the temperature of the material.
The present invention is also achieved by the second invention having a control means for controlling . Further, the above object is to raise the temperature by energizing
The heating member moves with the recording material while rubbing against the heating member.
Film member and the heating member via the film member.
A pressure member that forms a nip for holding the recording material
Moved to a position where it contacts the member and a position away from the pressure member
A cleaning member capable of cleaning the pressure member, and
Image heating device that heats the image on the recording material while nipping and transporting the material
The minimum size of recording material in the nip
The temperature of the heating member corresponding to the non-passage area
When the temperature exceeds a certain temperature, the cleaning member is moved from the pressure member.
This is also achieved by the third invention that is separated.

[0017]

[0018]

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments 1 to 11 of the present invention will be described with reference to the drawings.

<Embodiment 1> First, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 2 is a diagram illustrating a schematic configuration of an example of an image forming apparatus using the fixing device 60 of the present embodiment. As shown in FIG. 2, the image forming apparatus according to the present embodiment is an electrophotographic copying apparatus of a fixed platen type, a movable optical system, a rotating drum type, and a transfer type.

In the apparatus of this embodiment, as shown in FIG. 2, the original 19 is placed on a fixed original platen glass 20 as required, and after setting the necessary copying conditions, the copy start key is pressed. The body drum 39 is rotationally driven at a predetermined peripheral speed in a clockwise direction indicated by an arrow. Further, the light source 21 (22 is a reflection shade) and the first mirror 23 move at a predetermined speed V from the home position on the left side of the glass to the right side of the glass along the lower surface of the platen glass 20, and the second mirror 24 and the second mirror When the three mirrors 25 move in the same direction at a speed of V / 2, the downward image surface of the placed document 19 on the document table glass 20 is illuminated and scanned from the left side to the right side, and the surface of the document of the illumination scanning light is scanned. The reflected light is transmitted through the imaging lens 29 and the fixed fourth to sixth mirrors 26 and 2.
Image formation exposure (slit exposure) is performed on the surface of the rotating photoconductor drum 39 via 7, 28.

Before the exposure, the surface of the rotating photosensitive drum 39 is uniformly charged to a predetermined positive or negative potential by the primary charger 30, and the above-described exposure is performed on the charged surface. Thus, an electrostatic latent image having a pattern corresponding to the original image is sequentially formed on the surface of the drum 39. The electrostatic latent image formed on the surface of the photosensitive drum 39 is visualized as a toner image by the developing roller 32 of the developing device 31.

On the other hand, the recording material P is fed by the paper feed roller 51, is introduced into the transfer portion between the drum 39 and the transfer charger 34 at a predetermined timing through the guide 33, and receives the transfer corona. In contact with the drum 39, the toner visible image on the drum 39 side is sequentially transferred to the lower surface of the recording material.

The recording material P that has passed through the image transfer section is discharged
While being subjected to the charge removal of the back surface charge, the toner is sequentially separated from the surface of the drum 39, introduced into the fixing device 60 by the transport unit 38 and the entrance guide 10, subjected to the toner image fixing as described later, and is sent to the outside as an image-formed product. Is discharged.

After transfer, the surface of the drum 39 is cleaned and removed of residual toner and the like by a cleaning blade 37 of a cleaning device 36, and is repeatedly used for image formation.

The moving optical members 21 to 25 that have moved on the outward path as described above are set to move on the return path when reaching the predetermined end point on the outward path, return to the initial home position, and start the next copy cycle. Wait until
This step is called an optical system backing step).

If a plurality of (for example, 100) copies are designated before the copy start key is pressed, a microcomputer (hereinafter referred to as MPU) 18 shown in FIG. And the above steps are repeated at predetermined intervals.

Next, the fixing device 60 mounted on the apparatus of this embodiment will be described in detail with reference to FIG. In FIG.
Is a fixing film in the form of an endless belt, and the fixing film 6 includes a driving roller 7 on the left side and a driven roller 8 on the right side.
And a low-heat-capacity linear heater 1 fixedly disposed below the rollers 7 and 8.

The driven roller 8 also serves as a tension roller for applying tension in the direction in which the fixing film 6 is stretched outward. The fixing film is coated with silicone rubber or the like on its surface to increase the coefficient of friction of the driving roller 7 in the clockwise direction. With the rotation drive, wrinkles and meanders with a predetermined peripheral speed in the clockwise direction,
It is driven to rotate without delay.

Reference numeral 9 denotes silicone rubber or the like as a pressing means.
A pressure roller with a rubber elastic layer with good release properties.
The lower side fill of the endless belt-shaped fixing film 6 described above.
Between the heater 1 and the heater 1
On the other hand, for example, 5 to 10 kg /
cm Are pressed against each other with a contact force of
It rotates counterclockwise in the forward direction in the transport direction.

Reference numeral 13 denotes a cleaning roller as a cleaning member which is disposed so as to be able to freely contact and separate from the pressure roller 9. The cleaning roller 13 is provided with a silicone sponge layer around a metal core, and further has a surface thereof. It is covered with felt made of aramid fiber (trade name: Nomex, manufactured by DuPont). Further, the cleaning roller 13
Is set so that the solenoid 14 moves toward and away from the pressure roller 9 at a predetermined timing.

The rotationally driven endless fixing film 6 is repeatedly provided for heat-fixing of a toner image, so that it is excellent in heat resistance, releasability and durability.
A thin film having a thickness of not more than μm, preferably not more than 40 μm is used. As an example, a high heat resistant resin such as polyimide, polyetherimide, polyethersulfone, polyether, ether ketone, etc. having a thickness of 20 μm, nickel, SU
PTFE on the outer peripheral surface of a thin endless belt made of metal such as S
(Ethylene tetrafluoride resin), PFA (ethylene tetrafluoride / perfluoroalkyl vinyl ether copolymer resin)
And a release coat layer obtained by adding a conductive material such as carbon black to these resins.
It is an endless belt with a total thickness of 30 μm applied to a thickness of μm.

The low heat capacity heater 1 has a thickness of, for example, 1.0 mm.
A heat generating layer 3 is formed by coating a resistance material such as silver palladium or ruthenium oxide to a thickness of 10 μm and a width of 1.0 mm on an alumina substrate 2 having a width of 10 mm and a length of 340 mm in the longitudinal direction. A protective layer 4 made of glass or the like is formed in consideration of sliding with a film 6 having a thickness of 10 μm. The protective layer 4 is fixed to and supported by a heater support 11.

The heater support 11 has a heat insulating property, a high heat resistance and a rigidity for thermally supporting the heater 1 with respect to the fixing device 60 and the image forming apparatus, and includes, for example, PPS (polyphenylene sulfide) and PEEK (polyether ether). Ketones), high heat-resistant resins such as liquid crystal polymers, and composite materials of these resins with ceramics, metals, and the like.

Electric power is supplied to the heating layer 3 of the heater from both ends in the longitudinal direction. The energization is 100 V AC, and energization is controlled by the MPU 18 in accordance with the temperature detected by a thermistor 5 such as an NTC thermistor which is adhered or pressed to the back surface of the substrate 2 with a thermally conductive silicone rubber adhesive or the like or integrally formed.

FIG. 3 is a side view of the heater 1 as viewed from the sheet feeding side. The heat generating layer 3 is formed at the center of the lower surface of the substrate 2 in a straight line along the longitudinal direction of the substrate. Reference numerals 3a and 3b denote current-carrying electrodes (input terminals) made of a good conductive material such as silver provided on the left and right ends of the heat generating layer 3.

E is the effective entire length of the heat generating layer 3 between the electrodes 3a and 3b. In the case of this embodiment, the maximum size recording material which can be supplied to the apparatus and used is an A3 plate (297 mm width). The length is set to the length corresponding to the recording material width.

In the image forming apparatus of this embodiment, recording materials of various sizes are supplied on the basis of the base line A on the left side of the heat generating layer 3, that is, on the one-side basis. The paper passing area of the A6 plate (width 105 mm) is the paper passing area of the minimum size recording material that can be used in the image forming apparatus of the present embodiment.

5A is a thermistor which is a temperature detecting element provided in the minimum sheet passing area. At the time of fixing, the MPU 18 controls the heater drive circuit 16 so that the detection output of the thermistor 5A becomes a predetermined constant value, and controls energization to the heat generating layer 3. Reference numeral 5B denotes a thermistor which is a temperature detecting element provided outside the minimum sheet passing area. In this embodiment, the thermistor is disposed inside the maximum sheet passing area e and further outside the sheet passing area d of the B4 plate (width 257 mm).

Next, the fixing operation of this embodiment will be described with reference to the timing chart of FIG. Here, a case where ten fixing operations are set in advance by the user will be described. The image forming start signal at time T ₁ when the image forming apparatus starts the image forming operation, the cleaning roller solenoid 14 is turned on, leaving the cleaning roller 13 and the pressure roller 9. At the same time, the rotation of the fixing film 6 starts, and the time T is slightly delayed.
Power is supplied to the heater 1 at ₂ . The recording material P carrying the unfixed toner image T on the upper surface is conveyed from the transfer unit 34 to the fixing device 60. The recording material P is guided by the entrance guide 10 and rapidly reaches a predetermined fixing temperature (200 ° C. in this embodiment).
A heater 1 was heated to the unfixed toner at the time T ₃ to the pressure contact portion N between the pressure roller 9 enters in intimate contact with the fixing film 6 by the heater side. If time T ₁ = 0,
In the present embodiment, time T ₃ = 4 seconds.

The recording material P that has entered passes through the fixing nip N between the heater 1 and the pressure roller 9 while receiving a pinching pressure in an overlapping state with the movable fixing film 6 without causing surface deviation or wrinkling. The toner image carrying surface of the recording material P receives the heat of the heat generating layer 3 through the fixing film 6 while passing through the fixing nip portion N in a state of being pressed and fixed to the fixing film surface, so that the toner image is melted at a high temperature and the recording material P Image T softened and adhered to the surface
a.

In the case of the present embodiment, the recording material P is separated from the fixing film 6 when the recording material P passes through the fixing nip N and exits. At the time of this separation, the temperature of the molten toner Ta is still higher than the glass transition point of the toner. Since the toner Ta at a temperature higher than the glass transition point at this separation point has an appropriate rubber characteristic,
The toner image surface at the time of separation has an appropriate uneven surface property without following the fixing film surface, and this surface property is maintained and cooling and solidification occurs. High quality image quality without image gloss.

The recording material P separated from the fixing film 6 is guided by the paper ejection guide 12 and naturally reaches a temperature higher than the glass transition point while the toner Ta reaches the paper ejection roller pair 15 (natural cooling). The temperature becomes equal to or lower than the glass transition point and solidifies to reach the image Tb. After the recording material P which has passed through the fixing nip N at time T _5, the recording material P of the image fixing already is output.

[0044] Then, the solenoid 14 is turned off at time T ₆ with a slight delay from time T _5, the result cleaning roller abuts and again pressing roller, driven to rotate by the pressure roller, the pressure roller surface Remove residual toner.

Hereinafter, the fixing operation for the second and subsequent sheets is performed in the same manner.
Contact, continues to rotated, after 10 th fixing step at time T ₇ is completed, energization of the heater is completed at time T ₈ in. Thereafter, for cleaning the surface of the pressure roller, by moving the fixing film 6 to time T _9, rotates the pressure roller 9 and the cleaning roller 13.

The above operation was tested by changing the ambient temperature from 5 ° C. to 35 ° C.
Good fixability was obtained from the first sheet to the tenth sheet.
Even after the above cycle was repeated 10,000 times (total of 100,000 fixing operations), the pressure roller and the fixing film 6 were not stained.

<Comparative Example 1> In Example 1, when the cleaning roller was always in contact with the pressure roller 9 without providing the solenoid 14, the first recording material in a low temperature (5 ° C.) environment was used. There was a problem that P fixability was poor. The reason is that the cleaning roller 13 is in contact with the pressure roller 9 and is driven to rotate from the start of energization to the heater until the recording material enters the fixing nib portion, so that the pressure roller 13 does not warm up. This is because the amount of heat from the heater is transmitted to the pressure roller 9 via the fixing film 6 and then to the cleaning roller 13, so that the temperature rise rate of the heater is delayed.

<Comparative Example 2> In Example 1, when the cleaning roller 13 was not provided, after the fixing operation of about 10,000 sheets, the surface of the pressure roller was stained with toner, and transferred to the back surface of the recording material P. The recording material P was stained.

<Embodiment 2> Next, Embodiment 2 of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

FIGS. 5 and 6 are timing charts of the second embodiment. In this embodiment according to the detected temperature T _5A of the first thermistor 5A when the image formation start signal of the first sheet is issued at time T _1, operation of the solenoid 14 is different.

1) When the detected temperature T _5A ≦ 70 ° C. (FIG. 5) The solenoid 14 is turned on at time T ₁ and turned off at time T ₆ .

2) When the detected temperature T _{5A is} higher than 70 ° C. (FIG. 6) In such a case, the fixing operation is performed a while ago, indicating that the heater, the fixing film, the pressure roller, and the like are still warm. . Accordingly, the cleaning roller rotates following the pressure roller while the solenoid 14 remains off.

According to this embodiment, the cleaning performance of the pressure roller is improved without impairing the fixing property of the first sheet.

Third Embodiment Next, a third embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

FIG. 7 is a timing chart of this embodiment. On the solenoid 14 at time T _1, off solenoid 14 from the fixing nip portion at a time T ₅ immediately after the recording material has passed through, thereafter while the recording material P stays in the nip ON the solenoid, the cleaning roller pressure Release from pressure roller.

According to the present embodiment, when the cleaning roller becomes dirty with toner or the like after a large amount of fixing operation, the dirt on the surface of the cleaning roller adheres to the pressure roller, and further the dirt stains the recording material P. To prevent In particular, when a large number of small-size recording materials are continuously passed and a heater, a pressure roller, and a cleaning roller are heated by a temperature rise in a non-sheet passing portion, a large-size recording material is passed immediately thereafter. Even in this embodiment, however, no contamination of the cleaning roller adheres to the recording material.

According to this embodiment, the heat efficiency can be improved because the pressure roller can be further insulated from the cleaning roller compared to the first embodiment.

Fourth Embodiment Next, a fourth embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

As shown in FIG. 8, when the detected temperature T _5B of the second thermistor 5B is once turned T _5B ≧ 240 ° C., turns on the solenoid 14 to retract the cleaning roller from the pressure roller.

The toner used in this example has an excessively low melt viscosity at about 220 ° C., causing a so-called high-temperature offset. However, the second thermistor detection temperature T _5B is 240
When the temperature of the pressure roller is detected, the maximum temperature of the pressure roller surface is 210 ° C., which is still lower than the high-temperature offset occurrence temperature 220 ° C.
It is.

In this embodiment, when a small-size recording material is continuously passed, T _5B ≧ 240 ° C. at time T ₁₀ during the 49th sheet passing due to the temperature rise in the non-sheet passing portion. At this time, the solenoid 14 is turned on, and the cleaning roller is separated from the pressure roller. At this time, the maximum temperature of the pressure roller surface is still 21
Since the temperature is 0 ° C., dirt on the surface of the cleaning roller does not transfer to the pressure roller again. Again off the solenoid 14 to the time T ₁₁ became T _5B <240 ℃, then the cleaning roller for cleaning the surface of the pressure roller in pressure contact with the driven rotating the pressure roller.

According to this embodiment, when the pressure roller is in a high temperature state, the cleaning roller does not come into contact with the pressure roller, so that the dirt such as toner on the surface of the cleaning roller is melted or softened again and reapplied to the pressure roller. The transfer can be prevented, and the transfer to the recording material can be prevented.

Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

FIG. 9 is a timing chart of this embodiment. The solenoid 14 is turned on / off at the same timing as in the embodiment from the time when the image formation start signal is issued at the time T ₁ until the second recording material enters the nip, and thereafter the same as in the seventh embodiment. Take the timing.

According to the present embodiment, good fixability of the first sheet can be obtained, and retransfer of dirt on the surface of the cleaning roller to the pressure roller when the temperature of the non-sheet passing portion is increased can be prevented.

Embodiment 6 Next, Embodiment 6 of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

As shown in FIG. 10, as soon as T _5B ≧ 240 ° C., the cleaning roller is not released from the pressure roller. The recording material may be separated from the roller and contact the pressure roller immediately after the last recording material has passed through the fixing nip.

According to this embodiment, the state of heat radiation from the pressure roller during the fixing process can be kept constant, so that the fixing property is stabilized.

Embodiment 7 Next, Embodiment 7 of the present invention will be described. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description is omitted.

The cleaning roller 13 is formed of an aluminum bar. According to this embodiment, since the thermal conductivity of the cleaning roller is higher than that of the first embodiment, it is possible to reduce the temperature rise in the non-sheet passing portion after the small size paper is continuously passed.

The effect of reducing the temperature rise in the non-sheet passing portion is that the thermal conductivity W (W · m ⁻¹ · K ⁻¹ ) of the cleaning roller is W
It was remarkable when ≧ 1.0. The thermal conductivity of the member capable of forming the cleaning roller is as follows.

1) Pyrex glass: W = 1.1, more preferably W ≧ 10.

2) Stainless steel: W = 15 3) Aluminum: W = 240

Embodiment 8 In this embodiment, the cleaning rollers used in Embodiments 1 and 2 are impregnated with a release agent such as silicone oil. According to the present embodiment, contamination of the pressure roller can be further prevented.

Ninth Embodiment Next, a ninth embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a diagram illustrating a schematic configuration of an example of an image forming apparatus using the fixing device 60 according to the present embodiment. As shown in FIG. 12, the image forming apparatus according to the present embodiment is an electrophotographic copying machine of a fixed original platen, movable optical system type, rotating drum type, and transfer type.

In the apparatus of this embodiment, as shown in FIG. 12, the original 19 is placed on a fixed original platen glass 20 as required, and after setting the necessary copy conditions, the copy start key is pressed. The body drum 39 is rotationally driven at a predetermined peripheral speed in a clockwise direction indicated by an arrow. Further, the light source 21 (22 is a reflection shade) and the first mirror 23 move at a predetermined speed V from the home position on the left side of the glass to the right side of the glass along the lower surface of the platen glass 20, and the second mirror 24 and the second mirror When the three mirrors 25 move in the same direction at a speed of V / 2, the downward image surface of the placed document 19 on the document table glass 20 is illuminated and scanned from the left side to the right side, and the surface of the document of the illumination scanning light is scanned. The reflected light is transmitted through the imaging lens 29 and the fixed fourth to sixth mirrors 26 and 2.
Image formation exposure (slit exposure) is performed on the surface of the rotating photoconductor drum 39 via 7, 28.

The surface of the rotating photosensitive drum 39 is uniformly charged to a predetermined positive or negative potential by the primary charger 30 before the exposure, and the above-described exposure is performed on the charged surface. Thus, an electrostatic latent image having a pattern corresponding to the original image is sequentially formed on the surface of the drum 39. The electrostatic latent image formed on the surface of the photosensitive drum 39 is visualized as a toner image by the developing roller 32 of the developing device 31.

On the other hand, the recording material P is fed by the paper feed roller 51, is introduced into the transfer portion between the drum 39 and the transfer charger 34 at a predetermined timing through the guide 33, and receives the transfer corona. In contact with the drum 39, the toner visible image on the drum 39 side is sequentially transferred to the lower surface of the recording material.

The recording material P that has passed through the image transfer section is discharged
While being subjected to the charge removal of the back surface charge, the toner is sequentially separated from the surface of the drum 39, introduced into the fixing device 60 by the transport unit 38 and the entrance guide 10, subjected to the toner image fixing as described later, and is sent to the outside as an image-formed product. Is discharged.

After transfer, the surface of the drum 39 is cleaned and removed of residual toner and the like by the cleaning blade 37 of the cleaning device 36, and is repeatedly used for image formation.

The moving optical members 21 to 25 that have moved on the outward path as described above are set to move on the return path when they reach the predetermined end point on the outward path, return to the initial home position, and start the next copy cycle. Wait until
This step is called an optical system backing step).

If a plurality of copies (for example, 100 copies) are designated before the copy start key is pressed, a microcomputer (hereinafter referred to as MPU) 18 shown in FIG. And the above steps are repeated at predetermined intervals.

Next, the fixing device 60 mounted on the apparatus of this embodiment will be described in detail with reference to FIG. In FIG. 11, reference numeral 6 denotes an endless belt-shaped fixing film. The fixing film 6 includes a left driving roller 7, a right driven roller 8, and a low heat capacity wire fixedly disposed below the two rollers 7, 8. It is stretched between the heater 1.

The driven roller 8 also serves as a tension roller for applying tension in the direction in which the fixing film 6 is stretched outward. The fixing film is coated with silicone rubber or the like on its surface to increase the coefficient of friction of the driving roller 7 in the clockwise direction. With the rotation drive, wrinkles and meanders with a predetermined peripheral speed in the clockwise direction,
It is driven to rotate without delay.

Reference numeral 9 denotes silicone rubber or the like as a pressing means.
A pressure roller with a rubber elastic layer with good release properties.
The lower side fill of the endless belt-shaped fixing film 6 described above.
Between the heater 1 and the heater 1
On the other hand, for example, 5 to 10 kg /
cm Are pressed against each other with a contact force of
It rotates counterclockwise in the forward direction in the transport direction.

Since the endless fixing film 6 which is driven to rotate is repeatedly used for heating and fixing a toner image, it is excellent in heat resistance, release property and durability.
A thin film having a thickness of not more than μm, preferably not more than 40 μm is used. As an example, a high heat resistant resin such as polyimide, polyetherimide, polyethersulfone, polyether, ether ketone, etc. having a thickness of 20 μm, nickel, SU
PTFE on the outer peripheral surface of a thin endless belt made of metal such as S
(Ethylene tetrafluoride resin), PFA (ethylene tetrafluoride / perfluoroalkyl vinyl ether copolymer resin)
And a release coat layer obtained by adding a conductive material such as carbon black to these resins.
It is an endless belt with a total thickness of 30 μm applied to a thickness of μm.

The heater 1 having a low heat capacity has a thickness of, for example, 1.0 mm.
A heat generating layer 3 is formed by coating a resistance material such as silver palladium or ruthenium oxide to a thickness of 10 μm and a width of 1.0 mm on an alumina substrate 2 having a width of 10 mm and a length of 340 mm in the longitudinal direction. A protective layer 4 made of glass or the like is formed in consideration of sliding with a film 6 having a thickness of 10 μm. The protective layer 4 is fixed to and supported by a heater support 11.

The heater support 11 has a heat insulating property, a high heat resistance and a rigidity for thermally supporting the heater 1 with respect to the fixing device 60 and the image forming apparatus, and includes, for example, PPS (polyphenylene sulfide) and PEEK (polyether ether). Ketones), high heat-resistant resins such as liquid crystal polymers, and composite materials of these resins with ceramics, metals, and the like.

The heater layer 3 of the heater is energized from both ends in the longitudinal direction. The energization is 100 V AC, and the energization is controlled by the MPU 18 in accordance with the temperature detected by the temperature detecting element 5 such as an NTC thermistor that is adhered or pressed to the back surface of the substrate 2 with a thermally conductive silicone rubber adhesive or the like or integrally formed.

FIG. 13 is a side view of the heater 1 as viewed from the sheet feeding side. The heat generating layer 3 is formed at the center of the lower surface of the substrate 2 in a straight line along the longitudinal direction of the substrate. Reference numerals 3a and 3b denote current-carrying electrodes (input terminals) made of a good conductive material such as silver provided on the left and right ends of the heat generating layer 3.

Reference symbol e denotes the effective total length of the heat generating layer 3 between the electrodes 3a and 3b. In the case of this embodiment, the maximum size recording material supplied to the apparatus and used is an A3 plate (297 mm width). The length is set to the length corresponding to the recording material width.

In this embodiment, as shown in FIG. 14, the temperature of the metal plate of the entrance guide, which is the carry-in entrance of the fixing device, is controlled to 100 ° C. by a thermistor.

<Comparative Example 3> In Example 9, A4R8
After passing 200 sheets of 0g paper continuously, the temperature of the non-sheet passing portion is
It is about 240 ° C at 180 ° C temperature control, and 2000
Almost no change was observed even when the sheets were passed, and no damage was observed in each device. However, if preheating is not performed, 20
The temperature of the non-sheet passing portion after passing 0 sheets was 260 ° C., and when the temperature was continued thereafter, wrinkles occurred on the fixing film around 2000 sheets, and a part of the coating was damaged.

<Embodiment 10> Next, Embodiment 10 of the present invention will be described.
Will be described with reference to FIG. The same parts as in the ninth embodiment are denoted by the same reference numerals, and the description is omitted.

FIG. 15 is a view showing an apparatus according to a tenth embodiment of the present invention. In this embodiment, as shown in FIG. 15, a linear PT made of barium titanate is used just before the entrance of the fixing device.
A C heater is provided, the temperature is controlled by a thermistor so that the temperature becomes 80 ° C., and hot air having a temperature of 100 ° C. is blown from above to perform preheating.

According to the present embodiment, the temperature of the non-sheet passing portion and the damage of each device are almost the same as those of the first embodiment.
Since the hot air is applied from the upper portion, the leading end of the recording material can be adsorbed to the transport belt without any gap, and paper jam at the entrance of the fixing device due to the jumping up of the leading end of the recording material can be prevented.

<Embodiment 11> Next, Embodiment 11 of the present invention will be described.
Will be described with reference to FIG. The same parts as in the ninth embodiment are denoted by the same reference numerals, and the description is omitted.

FIG. 16 is a view showing an apparatus according to an eleventh embodiment of the present invention. In this embodiment, as shown in FIG. 16, after the paper is fed from the cassette into the main body, the temperature of the registration roller is adjusted to 60 ° C. by a thermistor, and the temperature of the drive roller of the transport belt from the fixing device to 80 ° C. The recording material is pre-heated by controlling the temperature with a thermistor.

According to this embodiment, A4R 80g paper is
The temperature of the non-sheet passing portion after passing 0 sheets is 2 degrees at 180 ° C.
Although slightly as 35 ° C., the temperature rise in the non-sheet passing portion was able to be reduced more than in Example 1. In addition, temperature 35 ° C, humidity 85%
The temperature rise of the non-sheet passing portion after passing 200 sheets was able to be reduced to 250 ° C. where practically no problem occurred even when the paper was left in the atmosphere for one week. Further, it was also effective against curling of the recording material after being discharged from the fixing device.

[0100]

As described above, a plurality of recording materials are connected in series.
When heating the first sheet of recording material,
It is separated from the pressure member and then abuts on the pressure member
There is a member to clean the pressure member
Before the recording material enters the nip, adjust the temperature of the pressure member
The effect of being able to start up to a suitable temperature is obtained.

In the second invention , the energization of the heating member is started.
Cleaning after the start of energization according to the temperature of the heating member before
It has a control means for controlling the movement of the member.
Recording material without reducing cleaning efficiency.
Before entering the pump, raise the temperature of the pressure member to an appropriate temperature.
The effect of being able to raise is obtained. Furthermore, the third
In the invention, the recording material of the minimum size does not pass through the nip.
The temperature of the heating element corresponding to the non-passage area exceeds the specified temperature.
When the cleaning member is separated from the pressing member,
As a result, the material removed by the cleaning member
The effect that adhesion can be prevented is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of a fixing device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of an image forming apparatus according to a first embodiment incorporating the apparatus in FIG. 1;

FIG. 3 is a diagram showing a schematic configuration of a heating element used in the apparatus shown in FIG. 1 and control means for the heating element.

FIG. 4 is a timing chart showing the operation of the cleaning roller of the apparatus shown in FIG. 1;

FIG. 5 is a timing chart illustrating a first mode of operation of the cleaning roller according to the second embodiment of the present invention.

FIG. 6 is a timing chart illustrating a second mode of the operation of the cleaning roller according to the second embodiment of the present invention.

FIG. 7 is a timing chart illustrating an operation of a cleaning roller according to a third embodiment of the present invention.

FIG. 8 is a timing chart illustrating an operation of a cleaning roller according to a fourth embodiment of the present invention.

FIG. 9 is a timing chart illustrating an operation of a cleaning roller according to a fifth embodiment of the present invention.

FIG. 10 is a timing chart illustrating the operation of a cleaning roller according to a sixth embodiment of the present invention.

FIG. 11 is a sectional view illustrating a schematic configuration of a fixing device according to a ninth embodiment of the present invention.

FIG. 12 is a diagram showing a schematic configuration of a copying machine according to a ninth embodiment of the present invention incorporating the apparatus shown in FIG. 11;

13 is a diagram showing a schematic configuration of a heating element used in the apparatus in FIG. 11 and a control means of the heating element.

FIG. 14 is a diagram illustrating a schematic configuration of a heating unit in front of a fixing device according to a ninth embodiment of the present invention.

FIG. 15 is a diagram illustrating a schematic configuration of a heating unit in front of a fixing device according to a tenth embodiment of the present invention.

FIG. 16 is a diagram illustrating a schematic configuration of a copier and a heating unit in front of a fixing device according to an eleventh embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 heater, heating element (heating element) 5A first thermistor (temperature detecting means) 5B second thermistor (second temperature detecting means) 6 film (film member) 9 pressure roller (pressure means) 13 cleaning roller (cleaning) Means) 14 solenoid (drive means) P recording material

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-88387 (JP, A) JP-A-3-287284 (JP, A) JP-A-4-180080 (JP, A) 3862 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 13/20 G03G 15/20

Claims (6)

(57) [Claims] An image recording apparatus includes : a heating member; and recording while rubbing the heating member.
Through a film member that moves with the material,
To form a nip for holding the recording material together with the heating member.
A recording member having a pressure member and a cleaning member for cleaning the pressure member;
In an image heating device that heats an image on a recording material while nipping and transporting the material , one sheet for heating multiple recording materials continuously
During heating of the recording material, the cleaning member is separated from the pressing member.
An image heating device which is in contact with the pressure member after that . 2. A cleaning member is provided each time a recording material enters the nip.
The image heating apparatus according to claim 1, wherein the image heating apparatus is separated from the pressure member and comes into contact each time it comes out of the nip . 3. A heating member which is heated by energization, and a heating unit.
A film member that moves with the recording material while rubbing the material,
Nipping the recording material with the heating member via the film member
The pressure member forming the nip and the position where it contacts the pressure member
And can be moved to a position away from the pressure member.
And a cleaning member for cleaning the recording material.
In an image heating apparatus for heating an image on a recording material,
According to the temperature of the heating member before the energization to the heating member starts
Control means for controlling the movement of the cleaning member after the start of energization.
An image heating device comprising: 4. When heating a plurality of recording materials continuously,
The control means is that the temperature of the heating member before the start of energization is lower than the predetermined temperature
Cleaning after the first recording material has passed through the nip
When the member is brought into contact with the pressure member,
Before the first recording material enters the nip, remove the cleaning member
4. The image heating device according to claim 3 , wherein the image heating device contacts the pressure member . 5. A heating member which rises in temperature when energized, and a heating unit
A film member that moves with the recording material while rubbing the material,
Nipping the recording material with the heating member via the film member
The pressure member forming the nip and the position where it contacts the pressure member
And can be moved to a position away from the pressure member.
And a cleaning member for cleaning the recording material.
In an image heating apparatus for heating an image on a recording material,
Non-passage area through which the smallest size recording material does not pass
If the temperature of the heating member corresponding to the temperature exceeds a predetermined temperature
Can, especially that the cleaning member is separated from said pressure member
An image heating apparatus according to symptoms. 6. A non-recording device while the recording material is entering the nip.
The temperature of the heating member corresponding to the passage area has exceeded the predetermined temperature
When the recording material entering the nip comes out of the nip
6. The image heating apparatus according to claim 5, wherein the cleaning member is separated from the pressing member .