JPH08220921A - Fixing device - Google Patents

Abstract

(57) [Abstract] [Purpose] While reducing the number of parts to achieve cost reduction and size reduction, it also prevents the deterioration of image quality due to the drop of toner particles adhering to the web at the start of operation of the image forming apparatus main body. It is an object of the present invention to provide a fixing device that can be used. A heating roller 12 provided with a heater, and a pressure roller 13 that rotates while being pressed against the outer peripheral surface of the heating roller.
And a cleaning web 16 for cleaning by contacting the outer peripheral surface of the heating roller, and a feeding roller and a take-up roller for the cleaning web, and recording in which a nip portion between the heating roller and the pressure roller holds unfixed toner. In the image forming apparatus provided with the fixing device that fixes the toner onto the recording paper when the paper passes, the take-up roller is also used as the means 26 for pressing the cleaning web against the outer peripheral surface of the heating roller.

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 and a facsimile, and more particularly to a fixing device using a cleaning web as a means for cleaning the peripheral surface of a heating roller. In the above, the present invention relates to a fixing device that realizes a cleaning mechanism with a reduced number of parts.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, a developing device supplies an electrostatic latent image obtained by irradiating image information such as reflected light of an original onto a photoconductor uniformly charged in advance. A toner image obtained by developing with toner is transferred onto a recording paper, and then fixed by heating and pressing with a fixing device. The fixing device has a heating roller provided with a heating element (heater or the like) inside or near the surface thereof, and a pressure roller that presses against the outer peripheral surface of the heating roller. FIG. 3 is a diagram showing the configuration of a conventional fixing device disclosed in Japanese Patent Laid-Open No. 55-26531.
A cleaning mechanism 9 is provided for cleaning and removing the toner adhering to the peripheral surface of the heating roller when the toner 8 on the recording paper 7 is fixed by passing the toner. The cleaning mechanism 9 removes the toner 8 on the peripheral surface of the heating roller 1 by pressing the cleaning web 3 delivered from the delivery roller 5 and wound by the winding roller 6 against the peripheral surface of the heating roller 1 by the press roller 4. . However, since the cleaning mechanism 9 uses three rollers, that is, the press roller 4, the feed roller 5, and the take-up roller 6, the apparatus becomes large in size and the cost increases due to an increase in the number of parts.

Next, it is general to match the timing of moving the cleaning web with the heat generation and rotation of the heating roller, and the heating roller is in a heated state when the image forming apparatus main body is in operation when the power is turned on. A small amount of toner adhering to the surface of the heating roller is heated and melted by the heating roller, and when it reaches the web that is in sliding contact with the surface of the heating roller, it is dammed by the web and the circumferential surface of the heating roller is moved by the movement of the web. Removed from. When the heating of the heating roller is stopped by turning off the power source of the apparatus main body, the toner, which is blocked by the web on the circumferential surface of the heating roller, solidifies together with the paper dust and the like. Dust containing once solidified toner, paper powder, etc., is difficult to melt again even if it is heated, and even if it reaches the pressure contact position of the web, it cannot pass through the web, passes through the web, and cannot be cleaned. Becomes

In Japanese Patent Laid-Open No. 59-30575, the temperature of the heating roller is detected by a detection means, and when the temperature of the heating roller reaches or exceeds a certain temperature, the web is moved by a certain amount, thereby wasting the web. However, if pre-rotation (reload) is performed to eliminate temperature unevenness of the heating roller before moving the web, the toner residue coagulated on the surface of the heating roller is The particles are dispersed on the entire surface of the heating roller, and in the subsequent printing, toner dust is offset on the surface of the recording paper, which deteriorates the image quality of the copy. Even if the web is moved before the pre-rotation of the heating roller, the portion of the web that was in contact with the surface of the heating roller immediately before the start of movement is caught in the roll of the take-up roller and the adhered toner does not drop. During this period, the toner residue solidified on the web is peeled off from the web due to the vibration during the operation of the main body of the apparatus and falls on the peripheral surface of the heating roller or the recording paper, which causes the deterioration of the image quality.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and aims at cost reduction and size reduction by reducing the number of parts, and at the same time, the dust of the toner adhered to the web at the start of operation of the image forming apparatus main body. An object of the present invention is to provide a fixing device capable of preventing deterioration of image quality due to dropping.

[0006]

In order to achieve the above object, the present invention provides a heating roller provided with a heater, a pressure roller which rotates while being in pressure contact with the outer peripheral surface of the heating roller, and an outer peripheral surface of the heating roller. A cleaning web to be cleaned by cleaning, and a feeding roller and a take-up roller for the cleaning web. When the recording paper holding unfixed toner passes through the nip portion between the heating roller and the pressure roller, the toner is recorded on the recording paper. In the image forming apparatus equipped with the fixing device for fixing to the above, the take-up roller is also used as a means for pressing the cleaning web against the outer peripheral surface of the heating roller. According to a second aspect of the present invention, when the surface temperature of the heating roller rises to a predetermined temperature after the surface temperature of the heating roller reaches from the normal temperature to the fixable temperature after the image forming apparatus is powered on. In addition, the heating roller is pre-transferred to eliminate temperature unevenness in the heating roller, and the cleaning web is moved immediately before the pre-rotation. According to a third aspect of the present invention, the moving length in one movement of the cleaning web performed immediately before the pre-rotation of the heating roller is the web length of the web portion which was in contact with the heating roller before the movement. It is characterized in that it is set to a minimum necessary amount until it is caught inside the web roller on the outer circumference of the take-up roller.

[0007]

According to the first aspect of the present invention, the take-up roller of the cleaning web is also used as the press roller, and the length of the web stretched between the delivery roller and the delivery roller is shortened.
The number of parts can be reduced, and the size and cost can be reduced. According to the second aspect of the invention, since the web is moved before the pre-rotation of the heating roller, it is possible to prevent the solidified dust of the toner from being scattered on the surface of the heating roller. According to the third aspect of the present invention, the cleaning is completed and the web portion to which the toner or the like is attached is completely wound into the web roll around the take-up roller (press rolling roller) by the movement before the pre-rotation. It is possible to prevent the solidified dust of the toner from being scattered on the surface of the heating roller. Further, since the moving length of one web is minimized, the amount of web used per unit number of copies (per day) can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a front view of an embodiment of the present invention,
FIG. 2 is a perspective view. The fixing device 10 is used in a fixing portion of an electrophotographic image forming apparatus, and includes a heating roller 12 having a heater 11 therein and a pressure roller 1.
3, a thermistor 14 that detects the surface temperature of the heating roller 12, a control unit 15 that controls the temperature of the heater by receiving the temperature information detected by the thermistor 14, and toner that adheres to the outer peripheral surface of the heating roller 12 and the like. And a cleaning mechanism 17 having a web 16 for removing foreign matter. The recording paper 21 holding the unfixed toner 20 on the surface is the rollers 1
The toner is fixed by being pressed while being heated when passing through the nip portions 2 and 13. Although a part of the toner on the recording paper adheres to the surface of the heating roller when passing through the recording paper, the cleaning mechanism 17 removes the adhered toner by the web 16.

The cleaning mechanism 17 winds the unused web 16 and feeds it out.
A press rolling roller (winding roller) 26 that winds the wound web 16 and presses the wound web around the outer circumferential surface of the heating roller 12, a motor 27 that drives the press rolling roller 26, and a motor Universal joint (universal joint) that connects the output shaft 27a of 27 to one end of the press rolling roller 26
28 and. The motor is controlled by a control unit such as a microcomputer (not shown). The universal joint 28 is used because the vertical position of the press rolling roller 26 (distance between the heating roller and the heating roller) varies depending on the diameter of the web wound around the press rolling roller 26. This is because if the positional relationship between the output shaft 27a and the press rolling roller 26 is fixed, the press rolling roller 26 cannot move in the vertical direction.

According to the present invention, since the heating roller starts to rotate when the image forming apparatus starts operating as in the conventional case, the toner residue adhered to the web is dropped and adhered to the heating roller or the recording paper. In order to solve the problem caused by the above, the timing for moving the web is devised as follows. That is, similarly to the conventional example, in the present invention, the thermistor 14 is used to detect the surface temperature of the heating roller 12,
The temperature information detected by the thermistor 14 is output to the control unit 15. Further, the instruction to start the pre-rotation (reload) after the power of the image forming apparatus main body is turned on is transmitted from the control unit 15 to the driving unit (not shown) of the heating roller. In addition to such a configuration, the present invention is characterized by a configuration in which the motor 27 is driven to move the web 16 immediately before the heating roller starts pre-rotation, and the web is moved in one movement. The moving length (winding length) of the web roll in which the contact portion of the web 16 before moving with the heating roller 12 is wound around the press rolling roller 26 (corresponding to the winding roller of the conventional example). The minimum moving length is sufficient to prevent the toner that is caught inside and adhered from being exposed. As a result, the toner solidification debris that was blocked by the web at the contact area between the heating roller and the web before the start of the web movement before the pre-rotation is pressed in advance by the movement of the web before the pre-rotation is started. Since it is taken up by the rolling roller 26 and is wound inside the web roller on the outer periphery of the roller 26, the solidified debris is scattered on the outer peripheral surface of the heating roller at the time of pre-rotation or separated from the web due to vibration during operation of the image forming apparatus. The situation such as dropping onto recording paper disappears. Therefore, the image quality of the copy does not deteriorate.

Next, comparing the moving length of the web between the case of the conventional example shown in FIG. 3 and the case of the present invention, the moving length of the web shown in FIG. 3 is the outer peripheral length (D1) of the winding roller 6. × π)
And the axial distance L between the take-up roller 6 and the press roller 4 is added, but in the case of the embodiment of FIG. 1 of the present invention, the press rolling roller 26 serves as a take-up roller and a press roller. Since it also serves, the moving length of the web is only the outer peripheral length (D2 × π) of the press rolling roller 26. Then, the roll outer diameter (D
1) and the roll outer diameter (D2) of the press rolling roller 26 of the present invention change relative to each other over time, but can be considered to be relatively the same, so that the present invention using the press rolling roller 26 is better. Becomes a value smaller by at least the distance L between the axes. Therefore, according to the present invention, the consumption of the web can be reduced.

The structure of a press rolling roller in which the take-up roller also serves as a press roller, the structure of moving the web before pre-rotation, or the amount of movement when moving the web before pre-rotation is set to a predetermined value. The composition is
They can be combined with each other, and all combinations of these configurations are included in the scope of the present invention.

[0013]

As described above, according to the first aspect of the present invention, the heating roller provided with the heater, the pressure roller that rotates while being in pressure contact with the outer peripheral surface of the heating roller, and the outer peripheral surface of the heating roller are provided. A cleaning web for contacting and cleaning, and a feeding roller and a winding roller for the cleaning web are provided, and the toner is recorded when the recording paper holding the unfixed toner passes through the nip portion between the heating roller and the pressure roller. In an image forming apparatus having a fixing device for fixing on paper, the take-up roller is also used as a means for bringing the cleaning web into pressure contact with the outer peripheral surface of the heating roller, and the take-up roller of the cleaning web is also used as a press roller. Since the length of the web stretched between the feeding roller and the roller is shortened, the number of parts can be reduced, and the size and cost can be reduced.

According to the second aspect of the present invention, after the power supply to the image forming apparatus is turned on, the surface temperature of the heating roller reaches a predetermined temperature until the surface temperature of the heating roller reaches from the room temperature to the fixable temperature. When the temperature rises, the heating roller is pre-transferred to eliminate temperature unevenness in the heating roller, and the cleaning web is moved immediately before the pre-rotation. It is possible to prevent deterioration of copy image quality due to scattering on the surface of the heating roller or dropping on the recording paper.

According to the third aspect of the present invention, the moving length in one movement of the cleaning web performed immediately before the pre-rotation of the heating roller is the web portion which was in contact with the heating roller before the movement. Was set to the minimum necessary for being wound inside the web roller on the outer circumference of the winding roller. In other words, after the cleaning is completed, the web portion on which the toner or the like adheres is completely wound into the web roll around the take-up roller (press rolling roller) by the movement before the pre-rotation, so that the solidified residue of the toner is generated. It can be prevented from being scattered on the surface of the heating roller. Further, since the moving length of one web is minimized, the amount of web used per unit number of copies (per day) can be reduced.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention.

FIG. 2 is a perspective view of FIG. 1;

FIG. 3 is an explanatory diagram of a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 heating roller, 2 pressure roller, 3 cleaning web, 4 pressing roller, 5 feeding roller, 6 winding roller, 7 recording paper, 8 toner, 9 cleaning mechanism, 10 fixing device, 11 heater, 12 heating roller, 13 Pressure roller, 12 heating roller, 14 thermistor, 15 control section, 16 web, 17 cleaning mechanism, 20 unfixed toner, 21 recording paper, 25
Feed roller, 26 press rolling roller (winding roller), 27 motor, 28 universal joint (universal joint).

Claims (3)

[Claims] 1. A heating roller provided with a heater, a pressure roller that rotates while being pressed against the outer peripheral surface of the heating roller, a cleaning web that contacts the outer peripheral surface of the heating roller for cleaning, and a cleaning web of the cleaning web. A fixing device comprising a feed-out roller and a take-up roller, wherein the toner is fixed on the recording paper when the recording paper holding the unfixed toner passes through a nip portion between the heating roller and the pressure roller. Is also used as a means for pressing the cleaning web against the outer peripheral surface of the heating roller. 2. After powering on the image forming apparatus,
When the surface temperature of the heating roller rises to a predetermined temperature before the surface temperature of the heating roller reaches the fixing temperature, the heating roller is pre-transferred to eliminate temperature unevenness in the heating roller. The fixing device according to claim 1, wherein the cleaning web is moved immediately before the pre-rotation. 3. The moving length in one movement of the cleaning web performed immediately before the pre-rotation of the heating roller is such that the web portion which was in contact with the heating roller before the movement is the outer circumference of the winding roller. The fixing device according to claim 1 or 2, wherein the fixing device is made to have a minimum necessary amount before it is caught in the web roller.