JPH11119581A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device which prevents a transfer material from being stained due to toner stain on a pressure roller. SOLUTION: This image forming device is provided with, as a fixing device for fixing a toner image T formed on the surface of a transfer material P by an image forming means which transfers the toner image on an image carrier to the transfer material P, a pressure member 28 disposed opposite a heating member 20b, a fixing film 25 held between the heating member 20b and pressure member 28, a cleaning member 33 in the form of a roller disposed opposite the pressure member 28, and a rotation control means which controls the rotation of the cleaning member 33. In the image forming device, a reciprocation means 50 is provided for reciprocating the cleaning member 33 in its axial direction for a specified period of time during a cleaning process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine and a laser beam printer, and more particularly to an image forming apparatus having a fixing device having a fixing film for fixing a toner image to a transfer material. is there.

[0002]

2. Description of the Related Art A conventional image forming apparatus of this type irradiates an image exposure corresponding to an original image or an image signal input from a computer onto the surface of an image carrier uniformly charged by a charging means, thereby obtaining the image carrier. Forming an electrostatic latent image on the body surface, developing the electrostatic latent image into a toner image by a developing unit, transferring the toner image to a transfer material by a transfer unit, and fixing the toner image on the transfer material by a fixing unit; There is an electrophotographic copying machine or a printer which fixes the image on the transfer material and outputs the image.

[0003] As a fixing device for fixing a toner image on a transfer material to a transfer material, a heat-resistant fixing film is slid on a heat-generating member, and a pressure member is pressed on the heat-generating member via the fixing film. A fixing device of a film fixing type that applies heat energy from a heat generating member via a fixing film to a transfer material nipped and conveyed by the pressing portion while the fixing film moves is used.

FIG. 4 shows an example of this film fixing type fixing device. In FIG. 4, reference numeral 20 denotes a heater serving as a heat generating member supported by a stay 21 as a support. The heater 20 has an endless belt-shaped fixing film 25 coated with a material having high heat resistance and a material having good releasability. Are provided so as to be suspended and slidably contacted between a driving roller 26 and a driven roller 27 disposed substantially parallel to the heater 20.

A pressing roller 2 serving as a pressing member is provided on the lower surface of the heater 20 so as to sandwich the fixing film 25.
8 are pressed against each other by an urging means at a contact pressure of, for example, about 5 kg weight, and the pressing roller 28 A fixing nip N is formed therebetween.

When the driving roller 26 is driven to rotate in a direction indicated by an arrow by a driving motor M as a rotation driving means, a fixing film 25 to which a predetermined tension is given by a driven roller 27 also serving as a tension roller.
Is rotated at a predetermined peripheral speed in the direction of arrow a, and the pressure roller 28 is also driven to rotate counterclockwise as the fixing film 25 rotates, so that the transfer material P is nipped and conveyed.

Therefore, the transfer material P after the transfer of the toner image T is sequentially fed into the fixing device by a transfer material supply means (not shown), and when the transfer material P enters the fixing nip N, the transfer material P is fixed. The toner image T on the transfer material P is fixed to the transfer material P while being conveyed while being held and transported by the rotation of the film 25 and the pressure roller 28, and the thermal energy generated by the heater 20 is applied.

In this type of film fixing type fixing device, a heater 20 as a heating member and a heater 2
Since the heat capacity of the fixing film 25 as a member for transmitting the heat energy of 0 to the transfer material P can be reduced, there is an advantage that power saving and shortening of the wait time (quick start property) are possible.

[0009]

However, there are cases where the above-mentioned prior art has the following problems.

When the toner image T passes through the fixing nip N, a so-called offset phenomenon in which a small amount of toner transfers from the transfer material P to the fixing film 25 occurs. A part of the offset toner is transferred to the rear end of the transfer material P again after the fixing film 25 makes one rotation, or remains on the fixing film 25 and is then transferred to the next transfer material P passing through the fixing nip N. Transcribed. Since the amount of the toner transferred to the transfer material P is extremely small, there is no practical problem.

However, part of the offset toner is transferred to the pressure roller 28. Once the toner adheres to the pressure roller 28, the surface energy is significantly reduced at that portion, and the toner is more likely to adhere. As a result, a thin layer of toner is formed on the pressure roller 28 in an island shape or a planar shape. The adhesion of the thin layer of the toner to the pressure roller 28 becomes weak when the surface temperature of the pressure roller 28 is low (particularly lower than the glass transition temperature of the toner).

In the case of this type of film fixing device, the heater 20 is not energized when the device is in a standby normal state. Therefore, the pressure roller 28 is also normally kept at about room temperature, at least below the glass transition temperature. When the fixing operation is started in that state, the temperature of the surface of the fixing film 25 in the fixing nip N rapidly rises. Transfer material P is fixing nip N
Before reaching the temperature, the surface of the toner layer adhered to the surface of the pressure roller 28 with a small force is softened and adheres to the fixing film 25. Then, a part of the toner layer is separated from the pressure roller 28 and transferred to the fixing film 25. The transferred toner immediately thereafter reaches the fixing nip N and is sequentially thermally transferred to the transfer material P passing therethrough. As a result, spot-like stains are generated on the surface of the transfer material P.

As shown in FIG. 4, the transfer material P is made of a metal having good heat conductivity and high surface energy such as aluminum as shown in FIG. An example in which a roller 33 is provided is known.

However, in normal use, the surface temperature of the roller 33 does not exceed the glass transition temperature of the toner.
The upper toner did not soften and deform, and the efficiency of collecting the toner on the roller 33 was poor.

On the other hand, every time a predetermined number of fixing operations are performed, at least the cleaning member and the pressing member are rotated for a predetermined time. By providing the pressure member cleaning step, the surface temperature of the roller 33 is raised to a temperature equal to or higher than the glass transition temperature of the toner, and the toner on the pressure roller 28 in contact with the roller 33 is softened and deformed, thereby improving the toner collection efficiency to the roller 33. I try to increase.

However, according to this method, the softened toner on the roller 33 is crushed while rotating at the contact portion with the pressure roller.
It tends to aggregate with the softened toner in the three circumferential directions. Therefore, after long-term use, a stripe-shaped toner pool is formed on the roller 33 in the circumferential direction, and the ability of collecting the toner from the pressure roller 28 is extremely reduced in the concave portion.

An object of the present invention is to provide an image forming apparatus capable of preventing spot-like stains on a transfer material caused by toner stains on a pressure roller and always obtaining a good fixed image. It is.

[0018]

A first structure for realizing the object of the invention according to the present application is an image forming means for transferring a toner image on an image carrier to a transfer material, and the image forming means A fixing device for fixing the toner image formed on the transfer material, wherein the fixing device includes a pressing member arranged to face a heat generating member, and a pressing member sandwiched between the heat generating member and the pressing member. An image forming apparatus including a fixing film, a roller-shaped cleaning member disposed to face the pressure member, and rotation control means for controlling rotation of the cleaning member. And reciprocating means for reciprocating in the axial direction for a predetermined period.

According to a second configuration for realizing the object of the present invention, during at least a part of the cleaning step, the surface temperature of the cleaning member is changed to the glass transition temperature of the toner forming the toner image. This is the configuration described above.

A third configuration for realizing the object of the invention according to the present application is an image forming means for transferring a toner image on an image carrier onto a transfer material, and an image forming means formed on the transfer material by the image forming means. A fixing device for fixing the toner image,
The fixing device includes a pressing member disposed to face the heating member, a fixing film sandwiched between the heating member and the pressing member, and a roller-shaped member disposed to face the pressing member. A reciprocating means for reciprocating the cleaning member in the axial direction for a predetermined period during a cleaning process, and a surface of the cleaning member. Temperature detection means for detecting temperature;
When the temperature detecting means detects a predetermined temperature range,
The reciprocating means is operated.

In the above-described first configuration, every predetermined number of sheets
The cleaning member and the pressing member are rotated for a predetermined time, and the cleaning member is reciprocated in the axial direction to clean the pressing member by the cleaning member and to uniformly adhere the toner on the cleaning member. This can prevent image stains due to toner stains on the pressure roller.

In the above-described second configuration, the surface temperature of the cleaning member may be equal to or higher than the glass transition temperature of the toner forming the toner image during at least a part of the period of the pressure member cleaning step. By reciprocating the cleaning member in the axial direction at
Image stains due to toner stains on the pressure roller can be prevented.

In the third configuration, the cleaning member is reciprocated by the temperature detected by the surface temperature detecting means of the cleaning member, thereby preventing image contamination due to toner contamination of the pressure roller. it can.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIGS. 1 and 2 show a first embodiment of the present invention.

FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to a first embodiment of the present invention.

In FIG. 1, reference numeral 10 denotes a drum type electrophotographic photosensitive member as an image carrier (hereinafter, referred to as "photosensitive drum").
The photosensitive drum 10 is, for example, an OPC photosensitive drum.

Above the photosensitive drum 10, a primary charging device 11 as charging means is provided. The primary charging device 11 uniformly charges the surface of the photosensitive drum 10 at the time of image formation, and the charged surface of the photosensitive drum 10 corresponds to an image signal such as a document image from the image exposure device 12. Is irradiated with the image exposure light L
As a result, an electrostatic latent image is formed. And the developing device 1
Reference numeral 3 denotes a unit for developing the electrostatic latent image on the photosensitive drum 10 to form a toner image.

The toner used in the present embodiment is a one-component negative toner having a volume average particle size of about 7 μm, and the binder resin is mainly polyester. The glass transition temperature (Tg) of this toner is about 60 ° C., and the softening temperature or fixable temperature (Tm) is about 130 ° C.

The transfer charging device 14 as a transfer means transfers the toner image on the photosensitive drum 10 to a transfer sheet P as a transfer material. The transfer sheet P after the transfer of the toner image on the photosensitive drum is Then, the toner image is conveyed to the fixing device 19 by the transfer material conveying device 32, where the toner image is fixed, formed as an output image, and discharged. The photosensitive drum 10, the primary charging device 11, the developing device 13
The transfer charging device 14 constitutes an image forming device.

The fixing device 19 in the image forming apparatus according to the present embodiment is a film fixing type fixing device as shown in FIG. 2, and is an endless belt-shaped fixing film 25 made of a material having high heat resistance. Is suspended between the heater 20, the driving roller 26, and the driven roller 27 so as to be in sliding contact with the heater 20, which is a heating member supported by a support (not shown).

On the lower surface of the heater 20, a pressing roller 28 as a pressing member with a fixing film 25 interposed is pressed by a biasing means (not shown), for example, at a total pressure of 5 k.
They are opposed to each other with a contact pressure of about g weight. The pressure roller 28 is a rubber elastic layer having good releasability such as silicone rubber,
In addition, a fluororesin layer such as PFA, PTFE, FEP or the like, which has better releasability than silicone rubber, is formed on the surface thereof. The outer diameter of the pressure roller 28 is 20 mm or 30 mm.

When the driving roller 26 is driven to rotate clockwise by a driving motor M as a rotation driving means, the fixing film 25 to which a predetermined tension is given by a driven roller 27 also serving as a tension roller is applied.
The fixing roller 25 rotates clockwise at a predetermined peripheral speed, and the pressure roller 28 is also driven to rotate counterclockwise with the rotation of the fixing film 25, thereby transferring the transfer material P to the fixing film 25 and the pressure roller 28. Are conveyed while being held between them.

The drive motor M can rotate at a predetermined timing according to a detection signal selected by a pressure roller cleaning mode selection switch 31 described later.

The fixing film 25 circulated in this way
Is a film excellent in heat resistance, releasability, and abrasion resistance, and generally has a total thickness of 100 μm or less, preferably 4
Use a thin material of 0 μm or less. For example, polyimide, polyetherimide, a single layer of heat-resistant resin such as PES,
Alternatively, the surface of these heat-resistant resins is made of PFA, PTF
It is preferable to use a film covered with a fluororesin layer composite layer such as E or FEP. The circumference is 30 to 60 mm.

The heater 20 has a thickness of 1.0 mm, a width of 10.0 mm, and a length of 350 mm.
An electric resistance material 20b is applied to a substrate 20c made of alumina, aluminum nitride, or the like so as to have a width of 2.5 mm and a length of 300 mm, and thermal energy is generated by energizing the electric resistance material 20b. .

Further, a temperature sensor 20d as temperature detecting means is mounted on the back surface of the substrate 20a of the heater 20, and the temperature sensor 20d is provided with a predetermined substrate during the image forming operation. An energization control unit 30, which is an energization control unit that controls electric power supplied to the heater 20 according to the temperature detected by the temperature sensor, is connected so that the temperature becomes a set temperature (a regulated temperature). Further, the power supply control unit 30 controls electric power supplied to the heater 20.

Further, in a pressure roller cleaning step to be described later, the control unit 29 synchronizes the operation of the power supply control unit 30 and the drive motor M with a predetermined signal based on a detection signal selected by the pressure roller cleaning mode selection switch 31. It is possible to control the temperature of the heater 20 at a predetermined temperature for a predetermined time.

Below the pressing roller 28, an aluminum roller 33 is opposed to and pressed by a biasing means (not shown) at a contact ratio of, for example, a total pressure of 500 g or 2 kg. The outer diameter of the roller 33 is 10 mm.

The roller 33 is reciprocating in the axial direction (reciprocating operation in the axial direction) by a reciprocating mechanism that operates in accordance with a command from the control unit 29 in the cleaning process.
It is possible.

FIG. 5 shows a reciprocating apparatus according to this embodiment.
Shown in

The roller 33 is supported by bearings 51 and 52 fixedly disposed on the housing of the fixing device.
Further, a pressure blade 53 is arranged between the bearing 51 and the roller, and the roller 33 is pressed in the direction of arrow a in FIG.

An eccentric cam 54 shown in (b) and (c) is arranged at the other end of the roller 33, and the shaft end of the roller 33 is abutted on the circumference thereof. As shown in (d), the drive motor 55 that rotates the eccentric cam 54 is driven by being supplied with a voltage from a power supply 56 that receives an instruction from the control unit 29.

During a predetermined period of the cleaning process, the control unit 29
When the eccentric cam 54 is rotated by a motor 55 supplied with a voltage from a power source 56 in accordance with an instruction from the
The roller 33 whose shaft end is brought into contact with the shaft is pressed by the outer periphery of the cam surface of the eccentric cam 54 and moves in the direction b from the position shown in FIG. When the eccentric cam 54 further rotates, as shown in FIG. 5A, the eccentric cam 54 is moved by being pressed in the direction of the arrow a by the pressing spring 53 arranged on the shaft at the other end.

As described above, the roller 33 is operated to reciprocate according to an instruction from the control unit 29, but the present invention is not limited to this method.

In the case of the conventional example in which the roller 33 is not mounted, when the transfer material having a width smaller than the length of the heater 20 is continuously processed, the heater 2 is placed in a place where the transfer material does not pass.
The temperature of the fixing film 25 and the pressure roller 28 in the portion opposed to the heater 0 and the heater 20 becomes extremely high, and a phenomenon called so-called edge temperature rise that causes thermal damage to components occurs.

In the case of this embodiment in which the roller 33 is mounted, the roller 33 is driven to rotate clockwise with the rotation of the pressure roller 28. As a result, since the heat conduction of the roller 33 is good, the axial temperature distribution of the pressing roller 28 that is in pressure contact with the roller 33 is made uniform. Then, the temperature distribution in the longitudinal direction of not only the pressure roller 28 but also the heater 20 and the fixing film 25 can be made uniform, and the above-described phenomenon of temperature rise at the end does not occur. That is, the roller 33 plays a role of a temperature rise prevention member at the end of the fixing device.

Further, since the surface energy of the roller 33 is higher than that of the surface of the pressure roller 28, the roller 33 also has an ability to collect toner adhered to the surface of the pressure roller. Therefore, the roller 33 also functions as a pressure roller cleaning member.

In particular, the surface temperature of the roller 33 is set to 60 ° C., which is the glass transition temperature of the toner used in the present embodiment.
As described above, when the temperature is raised to preferably 10 ° C. or more, more preferably 20 ° C. or more than the glass transition temperature, the toner in contact with the roller 33 is deformed and adheres firmly to the roller 33. Therefore, the surface of the roller 33 is heated to 60 ° C. or 80 ° C.
By rotating the pressure roller 28 while keeping it in contact with the pressure roller 28 for a predetermined time, the toner stain on the pressure roller 28 can be collected.

When the surface temperature of the roller 33 is higher than the glass transition point and the toner is softened, toner aggregation on the roller 33 occurs. In the case of normal rotation only, aggregation in the circumferential direction of rotation is mainly performed, but aggregation in the axial direction is also promoted by the reciprocating operation (reciprocating movement in the axial direction) of the roller 33 in the cleaning process. It is possible to form a small and uniform toner adhesion state.

The pressure roller cleaning step in this embodiment will be described below. When the number of sheets recorded on a counter (not shown) that counts the number of transfer sheets subjected to the fixing process by the fixing device 19 reaches a predetermined value, the driving motor M drives the fixing film 2 at a predetermined timing for a predetermined time.
The heater 20 is temperature-controlled by the power supply control unit 30 while running or rotating the pressure roller 5 and the pressure roller 28 around.
Further, in synchronization with this, the roller 33 is operated to reciprocate.

The pressing roller cleaning mode selection switch 31 is used to determine whether or not the pressing roller cleaning step is performed, when to perform the pressing roller cleaning step, and between when the pressing roller cleaning step is performed and when the next pressing roller cleaning step is performed. The interval, the execution time of one pressure roller cleaning step, and the temperature control condition of the heater 20 in the pressure roller cleaning step can be selected.

Regarding the presence or absence of the pressure roller cleaning step, “Yes” and “No”.

The timing at which the fixing operation is performed is either immediately before the start of the fixing operation (during the pre-rotation) or immediately after the end (at the post-rotation).

The interval, the execution time, and the heater 20
Can be set arbitrarily. However, in the present embodiment, the following fixed values are set in advance.

-Presence / absence of a pressure roller cleaning step: Yes.

Timing of execution: Immediately after the fixing operation is completed (during post-rotation).

Interval between the pressing roller cleaning step and the next pressing roller cleaning step: 1000 sheets.

Execution time of one pressure roller cleaning step: 60 seconds.

Temperature control condition of the heater 20 in the pressure roller cleaning step: constant at 230 ° C.

In the image forming apparatus of this embodiment, A4 size paper having poor fixability (for example, paper having a large amount, thick paper, or paper having poor formation) is used as the transfer paper and has an image ratio of 5%. When the image is continuously output in an intermittent mode for one image every five minutes, the saturation temperature of the roller 33 is about 35 ° C.
(At room temperature of 15 ° C.). When an image is output in such a mode, a part of the toner on the transfer paper is transferred to the pressure roller 28 via the fixing film 25 as described above. However, since the temperature of the roller 33 is lower than the glass transition temperature of the toner, the toner on the pressure roller 28 is hardly collected by the roller 33.

The roller 33 is heated from the heater 20 via the fixing film 25 and the pressure roller 28 to reach Tg in about 30 seconds and to Tg + 1 in 40 seconds.
0 ° C., Tg + 20 ° C. in 50 seconds, and Tg + 3 in 60 seconds
The temperature is raised to 90 ° C., which is 0 ° C. The time during which the surface of the roller 33 is maintained at Tg or more during the pressure roller cleaning step is about 30 seconds. The pressure roller 28 is slightly stained with toner while outputting 1,000 sheets of transfer paper.
Almost all of the toner on 8 is collected by the roller 33.

Therefore, no thin layer of toner is formed on the surface of the pressure roller 28.

As a conventional device example, a fixing device that does not perform a reciprocating operation under the above configuration and conditions will be described. Although image stains are not generated at all from 10,000 to 100,000 sheets, when images are output on about 150,000 sheets, the unevenness of the toner collected on the roller 33 becomes large. Then, the contact area between the pressure roller 28 and the roller 33 is effectively reduced,
In addition, the efficiency of heat transfer to the rollers 33 decreases.

As a result, a small amount of toner remains on the surface of the pressure roller 28, and the binding force of the toner collected on the roller 33 to the roller 33 also decreases. However, the image stain at this point is at a level where there is no practical problem.

However, when the output is up to 300,000 sheets, the unevenness of the toner accumulated on the surface of the roller 33 is further increased, and the contact area between the pressure roller 28 and the roller 33 is reduced. The binding force of the toner collected on the roller 33 to the roller 33 further decreased.

When an image is output after a long pause in this state, the toner collected by the roller 33 is heated to about 20 ° C. to 60 ° C. from the glass transition temperature by the heater 20 via the fixing film 25 during the previous rotation. Pressure roller 2 which has increased its temperature to a high temperature and has increased adhesion to toner.
8 causes a phenomenon of peeling. This toner is
The toner originally remaining on the surface of the pressure roller 28 adhered to the fixing film 25 at the time of the pre-rotation of the fixing device 19, and an unacceptable level of image stain was generated.

On the other hand, a phenomenon in the fixing device which performs the reciprocating operation according to the present invention will be described.

Except that the reciprocating operation is performed, the operation is exactly the same as that of the conventional example.

No image stains occurred from 10,000 to 150,000 sheets from the start of image output. Also, there are almost no irregularities on the roller 33.

When the process was further continued, the thickness of the toner layer reached 500 μm on average at about 250,000 sheets. In addition, irregularities on the surface have become conspicuous. At this time, the dirt on the pressure roller 28 could not be completely removed, and image dirt slightly occurred. However, it was at a sufficiently practical level.

When the toner is further continued, at approximately 450,000 sheets, the toner having a weak adhesive force attached to the surface of the roller 33 immediately before the cleaning step is peeled off, and the pressure roller 28
And transferred to the fixing film 25, and unacceptable image stains occurred.

The reason for this is that the temperature rise becomes gentle due to the increase in the heat capacity of the entire roller due to the increase in the thickness of the toner layer on the roller 33, and the decrease in the effective heat conduction efficiency due to the occurrence of irregularities on the surface. Accordingly, it is considered that the adhesion of the toner on the surface layer was reduced, and the toner was dropped because the reciprocating operation was performed in the axial direction in this state.

However, as compared with the above conventional example, the cleaning effect of the pressure roller can be maintained for a long time,
The occurrence of image stains was suppressed.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
An embodiment will be described.

FIG. 3 is a schematic sectional view of the fixing device 19 in the image forming apparatus of the present embodiment. In addition to the configuration of the fixing device 19 in the image forming apparatus according to the first embodiment, a second temperature sensor 34 that is in contact with or close to the roller 33 is provided. The second temperature sensor 34 is connected to the control device 29.

Since other structures are the same as those of the image forming apparatus of the first embodiment shown in FIG. 1, the description of the structure of the image forming apparatus other than the fixing device 19 is omitted.

In the image forming apparatus of this embodiment, the temperature detected by the non-contact second temperature sensor 34 is a predetermined temperature Tc.
(For example, 70, which is 10 ° C. higher than the glass transition temperature of the toner)
C), the controller 29 controls the reciprocating operation of the roller to be started by the reciprocating control means 50. This temperature Tc can be changed by the second pressure roller cleaning mode selection switch 37. In this example, the temperature is set to 75 ° C.

First, an example will be described in which the reciprocating operation is started simultaneously with the start of the cleaning step regardless of the temperature detected by the second temperature sensor.

Using an A4 size paper having poor fixability (for example, paper having a large amount of paper, thick paper, or paper having poor formation), an image having an image ratio of 5% is output in an intermittent mode per minute. , The saturation temperature of the roller 33 was about 55 ° C. (when the room temperature was 23 ° C.). As described above, a part of the toner on the transfer paper is transferred to the pressure roller 28 via the fixing film 25. However, during the image forming operation, the temperature is applied to the heater, and the temperature of the roller surface exceeds the glass transition point, so that the toner slightly moves from the pressure roller to the roller 33. However, since the roller 33 does not maintain a sufficient temperature, the toner on the roller 33 adheres in a convex shape. The contact area between the adhered toner particles and the roller 33 is small, and the adhesive force is extremely small.

When the image formation is further continued, the toner is further attached to the convex portion formed by the toner on the roller 33, and the toner is piled up like a spike. Roller 3
Since the temperature of the roller 3 does not rise so much, the toner
3, the attached toner grows so as to extend in the radial direction of the roller 33.

In this state, in the cleaning process after the image formation of about 100,000 sheets, the reciprocating operation is started before the roller surface reaches the softening point of the toner. I do. This adhered to the fixing film via the pressure roller, causing image stains after the cleaning process.

On the other hand, when the temperature Tc = 75 ° C. at which the toner on the roller is sufficiently softened is detected after the start of the cleaning process, the reciprocating device 50 is operated by the command from the control device 29 to start the reciprocating of the roller 33. When the reciprocating operation starts, the toner does not drop because the toner is already softened. Not only that, bonding between the adjacent spikes occurred, and the toner was sufficiently softened to increase the contact area with the roller, so that sufficient adhesive force on the roller was obtained.

When the cleaning was continued under these conditions, the toner did not drop off during the cleaning process even at the time of 400,000 sheets, and no image contamination occurred.

(Third Embodiment) When the image forming operation is continuously performed, the temperature of the roller 33 is higher than the glass transition point of the toner. For example, when 200 sheets were continuously passed, the surface temperature was 100 ° C. When 500 sheets were continuously fed, the surface temperature reached 140 ° C. (both in a 23 ° C. environment). As described above, since the glass transition point of the toner used in the present embodiment is about 60 ° C. and the softening temperature is about 130 ° C., in such a case, the toner on the roller is sufficiently softened.

When image formation is frequently performed under such conditions, it is preferable to perform the reciprocating operation of the roller according to the temperature detected by the second temperature sensor in normal image formation without providing a cleaning step. By doing so, the illusion of the user as if the device is operating when the user is not operating is not caused, and the operability is improved.

[0086]

As described above, according to the first aspect of the present invention, the cleaning member is reciprocated at the time of the pressure roller cleaning step, and the toner adheres uniformly, thereby causing toner contamination on the pressure roller. This prevents the image from becoming dirty.

According to the second aspect of the present invention, the temperature of the pressure roller cleaning member is raised to a temperature equal to or higher than the glass transition temperature of the toner during at least a part of the period of the pressure member cleaning step. Since the operation was performed, image contamination due to toner contamination of the pressure roller could be prevented.

According to the third aspect of the present invention, by detecting the surface temperature of the cleaning member and reciprocating the cleaning member after reaching the glass transition point of the toner, the image due to the toner falling off at the start of the reciprocation. Dirt can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an example of a film fixing type fixing device.

FIG. 3 is a sectional view of an example of a film fixing type fixing device.

FIG. 4 is a sectional view of a fixing device of a conventional device.

FIGS. 5A to 5D are views showing a reciprocating mechanism according to the first embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 image carrier (photosensitive drum) 11 primary charging device 12 image exposure device 13 developing device 14 transfer charging device 19 fixing device 20 heating member (heater) 25 fixing film 26 driving roller 27 driven roller 28 pressure member (pressure roller) Reference Signs List 30 energization control means 33 roller 50 reciprocating device P transfer material

Claims (3)

[Claims] An image forming means for transferring a toner image on an image carrier onto a transfer material; and a fixing device for fixing the toner image formed on the transfer material by the image forming means. The fixing device includes a pressing member disposed to face the heating member, a fixing film sandwiched between the heating member and the pressing member, and a roller-shaped member disposed to face the pressing member. An image forming apparatus comprising: a cleaning member; and rotation control means for controlling rotation of the cleaning member, comprising: reciprocating means for reciprocating the cleaning member in an axial direction for a predetermined period during a cleaning process. Forming equipment. 2. The cleaning device according to claim 1, wherein a surface temperature of the cleaning member is equal to or higher than a glass transition temperature of a toner forming the toner image during at least a part of the cleaning process. The image forming apparatus according to claim 1. 3. An image forming means for transferring a toner image on an image carrier onto a transfer material, and a fixing device for fixing the toner image formed on the transfer material by the image forming means, The fixing device includes a pressing member disposed to face the heating member, a fixing film sandwiched between the heating member and the pressing member, and a roller-shaped member disposed to face the pressing member. An image forming apparatus comprising: a cleaning member; and a rotation control unit that controls rotation of the cleaning member. A reciprocating unit that reciprocates the cleaning member in an axial direction for a predetermined period during a cleaning process; and a surface temperature of the cleaning member. And an image forming apparatus for operating the reciprocating means when the temperature detecting means detects a predetermined temperature range.