JP2000242128A - Fixing device for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove an adhesion substance staying at a nip part between a fixing rotating body and a cleaning web with a simple constitution by moving a stopped web member when an image forming device does not execute image- forming operation and the surface temperature of the fixing rotating body is equal to or above a specified temperature. SOLUTION: The web member 3 is brought into press-contact with a heating roll 1 by a press-contact roll 30. The member 3 is previously impregnated with releasing agent. When power is supplied to the image forming device, the surface temperature of the roll 1 rises and attains the temperature at which an adhesion substance is peeled from the nip part between the member 3 and the roll 1. According to a signal from a temperature sensor, a controller transmits a control signal to a driving motor 40 so that the member 3 is moved at a specified speed for a specified time. The adhesion substance staying at the nip part is removed with the movement of the member 3. When the surface temperature of the roll 1 continues to rise further and somewhat exceeds fixing temperature, the image-forming operation can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile, etc., and more particularly, to supplying a releasing agent to a fixing rotator or a fixing rotator. The present invention relates to a fixing device including a cleaning web for cleaning a surface.

[0002]

2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine, a fixing device for fixing a toner image formed on a recording sheet by an electrophotographic process by the action of heat and pressure has been widely used. ing. Further, in order to supply a release agent to a fixing rotating body of a fixing device and to clean the surface of the fixing rotating body, a cleaning web impregnated with a releasing agent is pressed against the fixing rotating body. .

In such a fixing device, a nip portion (pressure contact portion) between the cleaning web and the fixing rotating body is provided.
There has been a problem that toner adhered matter stays in the toner. That is, part of the toner (so-called offset toner) adhering to the fixing rotator during fixing, and paper fibers adhering to the fixing rotator when the recording sheet is of paper quality, are damped at the nip portion between the cleaning web and the fixing rotator. And accumulate as cohesion. The adhered matter sometimes slips through the nip portion following the rotation of the fixing rotator, and may cause problems such as fixing the image on the recording sheet to stain the image and damaging the surface of the fixing rotator.

In recent years, there has been an increasing tendency to form images having a relatively high image ratio, such as pictures and photographic images, instead of only text images, and to form full-color images instead of single-color images. Further, from the viewpoint of improving the image quality and ensuring the writing properties and adhesiveness of the recording sheet on which the image is formed, it is preferable that the amount of the release agent is as small as possible. For these reasons, the amount of offset toner tends to increase, so the above problem is becoming more serious.

As a conventional technique for solving such a problem, Japanese Patent Application Laid-Open No. 5-158376 discloses a technique in which the pressure contact portion between a fixing rotating body and a cleaning web is changed so that the cleaning web is clean or dirty. There is disclosed a technique in which a small portion of the adhesive is brought into contact with the deposit at a lower pressure to remove the deposit by a cleaning web.

[0006]

However, this technique requires a special mechanism for changing the contact portion, which makes the apparatus complicated and increases the cost. Therefore, it is difficult to apply this technology to a small and inexpensive image forming apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a fixing device capable of removing, by a simple structure, a deposit remaining in a nip portion between a fixing rotating body and a cleaning web. To provide.

[0008]

Means for Solving the Problems The present invention comprises a web member which is pressed with a predetermined nip part fixing rotator of the fixing device, and a driving means for moving the web member at a predetermined speed V _n, the image forming apparatus A control unit for controlling the driving and stopping of the driving unit in accordance with the operating state of the image forming apparatus, wherein the control unit is used when the image forming apparatus is not performing image formation, and When the surface temperature T _S of the rotating body is equal to or higher than a temperature T _{m at} which the adhered matter staying in the nip portion between the fixing rotating body and the web member can be peeled off, the driving means is controlled to move the stopped web member. (Claim 1).

[0009] By configuring the fixing device of the image forming apparatus in this manner, the web member that has been stopped up to that point is moved, which triggers the web member to stay in the nip portion between the fixing rotating body and the web member. The kimono is peeled off, held on the web member, and removed as it moves. Further, the attached matter can be removed with a simple configuration without adding a special mechanism to the conventional fixing device.

In this case, the image forming apparatus is not performing image formation, and the surface temperature T _S of the fixing rotator is the temperature T at which the adhered matter staying at the nip portion between the fixing rotator and the web member can be peeled off. _As an example of the case of not less than _m , there is a case where the surface temperature T _S of the fixing rotating body is the economic temperature _Te for a predetermined time continuously (Claim 2). That is, when the image forming apparatus does not perform image formation for a predetermined time, the surface temperature T _S of the fixing rotating body is set to the fixing temperature T because of the demand for quick re-image formation (re-fixing) and the need for energy saving. _May be maintained at a lower economic temperature Te.
In such economic temperature T _e, if the coagulation kimono can peeling (in the case of T _m <T _e is), by moving the web member, it is to remove the coagulation kimono.

Further, the image forming apparatus is a case not performing image formation, and the fixing rotator surface temperature fixing rotator and the web member and above a temperature T _m which can peel off coagulation kimono staying in the nipping portion of the As another example of the case, after the power of the image forming apparatus is turned on and the surface temperature T of the fixing rotating body is changed.
Before _S reaches the fixing temperature T (claim 3).
That is, after the power of the image forming apparatus is turned on, the surface temperature T _S of the fixing rotator gradually increases, and if the adhered substance can be peeled before reaching the fixing temperature T (when T _m <T, A) to move the web member to remove the deposits.

In the present invention, the web member is moved at these timings. However, if the moving distance is too short, it is difficult to sufficiently remove the deposits. On the other hand, if the length is too long, the web member is unnecessarily consumed and the replacement cycle is accelerated, which is not appropriate. Therefore, in the present invention, the web member is moved at these timings by the nip portion width between the web member and the fixing rotating body (claim 4). That is, by configuring the fixing device in this way, it is possible to prolong the life of the replacement cycle of the web member while reliably removing the adhered matter.

[0013] Also, the web member is intended to be moved in normal use at a predetermined moving velocity V _n. Here, in the present invention can also move the web member at the timing described above in the moving speed V _n, the moving velocity V _n
Is generally relatively slow in consideration of extending the life of the replacement cycle of the web member. However, it is preferable that the moving speed of the web member be high to some extent in order to form the image quickly and remove the deposits more effectively. Therefore, the web member in the above timing is also intended to move at a faster rate V _h than the predetermined speed V _n in the present invention (Claim 5).

By the way, the fixing rotating body of the fixing device is one used as a pair of fixing rotating bodies. At least one of the pair of fixing rotators has a heat source, rotates while being pressed against each other, and when a recording sheet holding an unfixed toner image on its surface passes through the pressed portion, heat and pressure are applied. Is to fix the toner image on the recording sheet. The shape of the fixing rotator may be a cylindrical roll, or may be an endless belt, a stretch roll, or the like.

The web member 3 is pressed against the surface of the fixing rotator to apply a release agent and to perform cleaning. Therefore, as the material, an appropriate material that can withstand the fixing temperature, for example, a nonwoven fabric made of polyamide and polyester can be used, and a woven fabric may be used if the heat resistance can be satisfied. Generally, the web member can be impregnated with a release agent such as silicone oil. This release agent may be impregnated beforehand, or may be one to which the release agent is supplied from the outside.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram illustrating a fixing device according to this embodiment. In this fixing device, a heating roll 1 is used as a pair of fixing rotating bodies.
The pressure roll 2 and the pressure roll 2 are configured to rotate while being pressed against each other. Each of the heating roll 1 and the pressure roll 2 has a multilayer structure including a hollow portion, an intermediate layer, and a surface layer from the shaft portion toward the outer peripheral direction. 10 are provided. And
When the unfixed toner image T held on the recording sheet P passes through the pressure contact portion between the heating roll 1 and the pressure roll 2, the unfixed toner image T is fixed by the action of heat and pressure to become a permanent image.

The web member 3 is pressed against the heating roll 1 at a predetermined nip portion by a pressing roll 30.
The web member 3 is pre-impregnated with a release agent,
The releasability of the recording sheet is improved. A driving motor 4 having a variable rotation speed as a driving means of the web member;
0, a drive transmission system (not shown) constituted by gears and the like for transmitting the driving force of the drive motor 40 to the winding shaft 41, a driving shaft 41 for winding the web member 3, a driven shaft 42 for feeding the web member 3, and the like. Consists of In the initial state, the web member 3 is wound around the driven shaft 42,
As it is used, it is gradually wound around the drive shaft 41. The drive shaft 41 and the driven shaft 42 are provided with one-way clutches (not shown), respectively, to prevent reverse rotation thereof.

The halogen lamp 10, a temperature sensor (not shown) for measuring the temperature of the surface of the heating roll 1, the measured values from the temperature sensor, and the operation of the image forming apparatus from the main controller (not shown). A temperature control system (not shown) for controlling the amount of heat generated by the halogen lamp 10 based on a situation or the like forms a temperature control system of the heating roll 1.

FIG. 2 is a block diagram illustrating a control system for winding the web member 3 of the fixing device according to the present embodiment. A signal indicating the operation status of the image forming apparatus is transmitted from the main controller 6 of the image forming apparatus to the control device 5, and a signal indicating the temperature of the surface of the heating roll is transmitted from the temperature sensor 7. Based on those signals, the control device 5 determines whether or not to move the web member 3 and stops,
Moving at a velocity V _n, the three kinds of control signals moving at a velocity V _h transmits the drive motor 40. Then, based on the signal, the drive motor 40 drives the drive shaft 41 to rotate, so that the desired movement of the web member can be achieved. The temperature sensor 7 has been conventionally used in the temperature control system of the heating roll 1 as described above, and is not newly required for carrying out the present invention.

Hereinafter, the web member 3 will be described with reference to FIGS.
And the operation of removing the deposits remaining in the nip between the web member 3 and the heating roll 1 will be described. FIG. 3 illustrates the timing of the movement of the web member 3, FIG. 4 is a flowchart showing the control procedure of the web member 3 after the power is turned on, FIG. 5 shows the operation of removing the deposits, and FIG. 6 is a flowchart illustrating a control procedure of a member 3.

In the graph of FIG. 3, the horizontal axis indicates the elapsed time, and the vertical axis indicates the surface temperature of the fixing rotating body.
Shows the timing of the rotational driving of the fixing rotator, the timing of the movement of the web member according to the present invention, and the timing of the movement of the conventional web member for reference. In addition, in the case of “〜”, “high” indicates a state of being driven for rotation or movement, and “low” indicates each stopped state.
Further, the surface temperature of the heating roll 1, the fixing temperature T, coagulation kimono may melting temperature T _m, indicates the standby temperature T _w,
It has the size relationship of T _w <T _m <T. Incidentally, economic temperature T _e, to lower than the temperature the T _m in the present embodiment, not shown in the graph. Hereinafter, description will be given along the time axis of this graph.

In the initial state, the surface temperature T of the heating roll 1 is
_S is the environmental temperature T ₀ . At time t ₀ (= 0), the image forming apparatus is turned on. Then, heating roll 1
The heating of the halogen lamp 10 is started by the temperature control system of
The rotation of the heating roll 1 and the pressure roll 2 is also started in order to transmit the heat uniformly to each surface. The control device 5 includes a main control device 6
It recognizes that the image forming apparatus has been powered on (see S10 in FIG. 4) and monitors the surface temperature T _S of the heating roll 1 (see S11 in FIG. 4).

[0023] The surface temperature T _S of the heating roll 1 over time increases, exceeding the temperature T _w, the temperature T _m, i.e. adhesive products web member 3 and the heating roll 1 at time t ₁
To a temperature at which it can be peeled from the nip. When the control device 5 recognizes this by a signal from the temperature sensor 7,
The controller 5 sends a control signal to the speed _{V h [mm / s] (} V n <V h) in time Delta] t [s] by the drive motor 40 to move the web member 3 (see S12 in FIG. 4) . Here, the moving distance of the web member 3 is the web member 3
And the nip width l _nip [mm] of the heating roll 1.
That is, the time Δ for moving the web member 3 at the speed V _h
t was set to Δt = 1 _nip / V _h [s].

FIG. 5A is an enlarged view of a nip portion between the heating roll 1 and the web member 3 at time t ₁ , and FIG.
Is an enlarged view of the nip portion at time t ₁ + Δt. At time t ₁ , the deposits generated by the previous image formation stay in the nip portion, particularly in the upstream portion thereof. Then, the web member 3 is moved, and a new web member 3 is supplied to the nip portion, so that the deposits that have been staying in the nip portion are removed with the movement of the web member 3. Therefore, it is possible to prevent the adhered substance from being retransferred to the heating roll and contaminating the next recording sheet.

Time t₁At + Δt, the web member 3
After stopping, the surface temperature T of the heating roll 1 is further increased._SIs above
Continue rising, time t_TwoImage slightly exceeds the fixing temperature T
An image can be formed. Then, time t_Two~ T_ThreeAnd time t_Four
~ T_FiveImage formation is performed continuously
Was. During image formation, the heating roll 1 (and the pressure roll 2)
It is always rotating to perform fixing (see FIG. 3).
Also, apply a release agent, and the offset
In order to clean the toner, the web member 3 is driven at a speed.
V_n(See FIG. 3). Sand
That is, a signal indicating the image forming state is received from main controller 6.
The control device 5 sets the speed V_n[Mm / s] (V _n<V_h)
The web member 3 is moved while receiving the signal at
The control signal is continuously transmitted to the drive motor 40 so that the drive signal is transmitted.
During continuous image formation, the recording sheet
Since the heat of the heating roll 1 is taken away by P, its surface temperature
Degree T_SSlightly decreases (see FIG. 3).

When the image formation stops at time t ₅ ,
The rotation of the heating roll 1 (also the pressure roll 2) is stopped, and the movement of the web member 3 is also stopped (see FIG. 3). Further, when the control device 5 recognizes that the image formation has been stopped by the signal from the main control device 6 (see S20 in FIG. 6), it monitors the surface temperature of the heating roll 1 (S2 in FIG. 6).
1). If then the predetermined time has elapsed, the time t _6,
The image forming apparatus is in the standby mode, and the surface temperature T _S of the heating roll 1 is set to the temperature T _w (T _w <
T) is controlled.

[0027] Then, the surface temperature T _S of the heating roll 1 is gradually decreased, reached the standby temperature T _w at time t _7.
Thereafter, at time t ₈ , the heating roll 1 is heated again in preparation for operating the image forming apparatus, and at time t ₉
In step (2), the control device 5, which has recognized that the surface temperature T _S has reached T _m (see S21 in FIG. 6), sets the speed V _h [m
_{m / s] (V n <} V h) transmitting a control signal to the drive motor 40 so as to move the time Delta] t [s] by the web member 3 (see S22 in FIG. 6). Here, the moving distance of the web member 3 is l _nip [mm], as in the previous case.
The operation for removing the adhered substance is the same as that described with reference to FIG.

In this embodiment, the control unit 5 recognizes that the image forming apparatus is in the standby state by a signal from the main control unit 6, and moves the web member 3 when the heating roll 1 is reheated. moving but this in addition to, when the surface temperature T _S of the heating roll 1 is not less than T _m, e.g., the time of time t ₅ ~t _6, a portion of the time period t ₆ ~t _7, the web member It may be controlled so that

Further, these fixing temperature T, the temperature coagulation kimono can melt T _m, but the standby temperature T _w can be determined according to various designs of each fixing device, in this example T = 170 [ ° C], _Tm = 160 [° C], _Tw = 1
00 [° C].

If the power of the image forming apparatus is turned off early (earlier than the time t ₉ ), the web member 3 shown in the flowchart of FIG. 6 cannot be moved. Also, since the movement of the web member 3 shown in the flowchart of FIG. 4 can be performed, the image formation can be performed with the adhered matter removed.

[0031]

As described above in detail, according to the present invention, it is possible to provide a fixing device which can remove, by a simple structure, a deposit remaining in a pressure contact portion between a fixing rotating body and a cleaning web. Can be.

[Brief description of the drawings]

FIG. 1 schematically illustrates a fixing device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a control system that controls movement of a web member.

FIG. 3 illustrates the surface temperature of the heating roll, rotation of the heating roll, and movement timing of the web member.

FIG. 4 is a flowchart illustrating a control procedure of a web member after power is turned on.

FIG. 5 is a diagram for explaining the operation of removing adhered substances.

FIG. 6 is a flowchart illustrating a control procedure of the web member 3 in a standby state.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heating roll, 10 ... Halogen lamp, 2 ... Pressure roll, 3 ... Web member, 30 ... Pressing roll, 40 ... Drive motor, 41 ... Drive shaft, 42 ... Drive shaft, 5 ... Control device

Claims (5)

[Claims] 1. A web member that is pressed against a fixing rotator of a fixing device at a predetermined nip portion, a driving unit that moves the web member at a predetermined speed, and a driving unit that moves the web member at a predetermined speed according to an operation state of the image forming apparatus. A fixing device for controlling driving and stopping of the image forming apparatus, wherein the control device is configured to control a case where the image forming apparatus is not performing image formation, and that a surface temperature of the fixing rotator is different from that of the fixing rotator. A fixing device for an image forming apparatus, wherein a driving unit is controlled so as to move a stopped web member when a temperature higher than a temperature at which an adhered substance staying in a nip portion with a web member can be peeled off. 2. The image forming apparatus according to claim 1, wherein the control unit controls the driving unit to move the web member when the surface temperature of the fixing rotator is the economic temperature for a predetermined time continuously. Fixing device. 3. The control unit controls the driving unit to move the web member after the power of the image forming apparatus is turned on and before the surface temperature of the fixing rotating body reaches the fixing temperature. A fixing device for an image forming apparatus according to claim 2. 4. The control unit according to claim 1, wherein the image forming apparatus is not performing image formation, and the surface temperature of the fixing rotator is capable of peeling off deposits staying in a nip portion between the fixing rotator and the web member. 4. The fixing device of an image forming apparatus according to claim 1, wherein the driving unit is controlled to move the web member stopped when the temperature is equal to or higher than the temperature by a nip portion width with respect to the fixing rotating body. 5. The control unit according to claim 1, wherein the image forming apparatus is not performing image formation, and the surface temperature of the fixing rotator is capable of peeling off deposits staying in a nip portion between the fixing rotator and the web member. The fixing device according to claim 1, wherein the driving unit controls the driving unit to move the stopped web member at a speed higher than the predetermined speed when the temperature is equal to or higher than the temperature.