JP2008304714A - Cleaning mechanism and fixing device using the same, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning mechanism that reliably removes toner deposited on a surface of a roller member without damaging the surface by changing an abutting state of the roller member with a web sheet, and to provide a fixing device and image forming apparatus using the same. <P>SOLUTION: In the cleaning mechanism 63, a web sheet 64 is press-contacted to a circumference surface of a rotating heat roller 61 to clean the surface of the heat roller 61. The mechanism includes a web member press-contacting means 65 for changing the abutting state of the heat roller 61 with the web sheet 64. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cleaning mechanism, a fixing device using the same, and an image forming apparatus, and more particularly to a cleaning mechanism that presses a web member against the outer peripheral surface of a rotating roller member to clean the surface of the roller body. The present invention relates to an image forming apparatus that includes a fixing device and a fixing device that uses the cleaning mechanism, and that outputs an image by transferring a toner image onto a recording medium.

  Conventionally, in an image forming apparatus such as a printer using an electrophotographic method, a photosensitive drum that is rotationally driven is charged by a charger, and an electrostatic latent image is formed on the photosensitive drum by light irradiation according to image information. The developing device attaches toner to the electrostatic latent image to form a toner image, and transfers the toner image to a recording medium such as a sheet material or paper to output an image.

  In this image forming apparatus, a fixing device for fusing and fixing unfixed toner on a recording medium to be conveyed is disposed, and a pair of rollers including a heating roller and a pressure roller at a portion for melting and fixing the unfixed toner A heat fixing roller system in which a member is used and heat is applied to the toner on the recording medium in the pressure contact area (fixing nip portion) of both rollers to fix the toner onto the recording medium is often used.

Here, an example of a fixing device used in a conventional image forming apparatus will be described.
As shown in FIG. 8, the conventional fixing device 160 includes a heating roller 161 and a pressure roller 162 as main constituent members, and a plurality of heating members (heat generation sources) 161a and 162a for heating both rollers to a predetermined temperature. I have. That is, a heat source is included inside the heating roller 161 and the pressure roller 162. Then, the unfixed toner having image information transferred onto the sheet by the print processing unit of the image forming apparatus is heated from the heating roller 161 and the pressure roller 162 in the fixing nip portion A of the pressure roller 162 and the pressure roller 162. The fixing process is executed by giving and receiving.
In the figure, reference numerals 611 and 622 denote paper peeling claws, 612 denotes a roller surface temperature detection member (thermistor), and 623 denotes a roller surface cleaning member.

  The predetermined temperature of the heating roller 161 is a temperature necessary for melting and fixing unfixed toner on the conveyed paper on the surface of the heating roller 161 at the fixing nip portion A, and is used in the image forming apparatus. In general, the toner melting temperature is + (30 to 40 ° C.), and the surface temperature of the heating roller is generally controlled at 160 to 200 ° C.

  The pressure roller 162 may or may not have a heat source inside the roller. This is because the function of the pressure roller itself is to press the sheet through the heating roller 161 at the fixing nip portion A when the conveyed sheet passes through the fixing device 160, and the fiber component ( The pressure roller 162 is disposed in order to allow the molten toner on the paper to penetrate into the cellulose and the like, and to exert a throwing action on the paper when the molten toner is solidified. May or may not have a heat source.

  The length of the throwing action (penetration distance to the paper) of the molten toner that exerts the throwing action on the conveyance paper differs depending on the temperature of the conveyance paper. The higher the paper temperature, the less the molten toner cools and the longer the penetration distance. Thus, the adhesion force of the toner fixed on the paper can be increased, and the fixing performance can be improved. Usually, when the printing processing speed (process speed) of the image forming apparatus is low, the sheet interval of continuous printing paper is long, and the surface temperature of the heating roller heats the surface of the pressure roller through the fixing nip portion. To do so, the pressure roller does not require a heat source.

  However, when the printing processing speed is increased, the interval between the conveyance sheets is short, and the surface temperature of the heating roller is insufficient to heat the surface of the pressure roller via the fixing nip portion. Requires an external heat source. The surface temperature of the pressure roller 162 is lower than the surface temperature of the heating roller 161 and is controlled at about 110 to 150 ° C., and the sheet is thrown by warming the sheet through the pressure roller 162 at the fixing nip portion A. The action will be promoted. The unfixed toner on the sheet conveyed in this way is fixed on the sheet at the fixing nip A.

As described above, the heating roller 161 includes the heating member 161a as a heat source for heating the surface of the heating roller 161 therein.
When the print processing speed is low, the amount of heat taken by the paper and the toner is small, so heating the heating roller with a single heater has been the mainstream, but when the print processing speed has become high as in recent years, The number of passing sheets per unit time increases, the amount of heat taken by the sheets and toner increases, and a method of arranging a plurality of heat sources inside the heating roller is often employed.

  Furthermore, when passing small-sized paper so as to be suitable for the paper size used for printing, ON / OFF control of one heat source that replenishes the amount of heat deprived at the center of the heating roller is performed, and large-sized paper is When passing the paper, a technique is used in which the surface temperature of the heating roller is made consistent with the paper passing size by performing ON-OFF control of the other heat source that replenishes the amount of heat taken from the entire surface of the heating roller. .

  On the other hand, the pressure roller 162 also has a heating member 162a as a heat source therein, and a method for improving the toner fixing performance in the fixing nip portion A in a state where the conveyed paper is heated and the paper is warmed in recent years. This high-speed image forming apparatus is frequently used.

  That is, the temperature of the fixing nip portion A is 160 to 200 ° C. on the surface of the heating roller, whereas the surface temperature of the conveyance sheet is the temperature in the apparatus (generally 15 to 35 ° C.), and the temperature difference is too large. Therefore, when the melted toner penetrates into the cellulose in the paper by the throwing action, it is cooled rapidly, and the throwing action becomes weak. In order to avoid such an adverse effect, a heat source is disposed to heat the conveying sheet from the surface opposite to the fixing surface (one surface of the sheet holding unfixed toner) and increase the throwing action. Sometimes.

  However, the toner forming the image information is melted and fixed on the outer periphery of the heating roller 161 at the fixing nip portion A, but all the toner in the fixing process is fixed on the paper. Therefore, a part of the toner is in a molten state and attached to the surface of the heating roller, and rotates together with the heating roller 161. When the next printing process is performed in this state, there arises a problem that the back side of the paper and the printing stain are caused.

  Therefore, conventionally, as a technique for cleaning the surface of the heating roller, the toner is applied to the surface of the heating roller by an oil roller impregnated with silicon oil so that the toner is not easily attached, and the toner attached to the heating roller by the felt roller. Is known (see Patent Document 1).

  Here, as another method, a cleaning member 163 using a web sheet 164 for cleaning the surface of the heating roller 161 is disposed on the surface of the heating roller 161 to clean the surface. In the figure, reference numerals 611 and 622 denote paper peeling claws, and 612 denotes a thermistor for detecting the surface temperature of the heating roller.

The cleaning member 163 is configured to clean toner stains adhering to the heating roller 161 in a state where the web sheet 164 is pressed with a predetermined pressure by the pressure roller 165 facing the heating roller 161 (cleaning unit).
Specifically, the web sheet 164 includes a feed roller 164a, a take-up roller 163b for winding the web sheet 164, tension rollers 166a and 166b for fixing the tension of the web sheet 164, and a pressure roller 165.

  The web sheet 164 is bridged by the feeding roller 164a and the take-up roller 164b, and is pressed against the surface of the heating roller 161 by the pressing force of the pressing roller 165 disposed between the bridged distances. Further, during the distance that the web sheet 164 is cross-linked, “tarmi” is generated in the web sheet at the site where the roller surface is cleaned, or the web moves by driving each of the feed roller 164a and the take-up roller 164b. The tension rollers 166a and 166b keep a constant tension and always obtain a constant cleaning performance so that the sheet 164 is not skewed.

  The web sheet 164 is composed of fibers having a thickness of 50 to 150 μm, and the melted toner on the heating roller 161 penetrates into the fiber weave of the web sheet 164 at the press contact portion with the heating roller 161. The connection with 164 is strengthened and the web sheet 164 is collected. Further, in the pressure contact portion of the web sheet 164 with the heating roller, the pressure contact force by the pressure roller 165 prevents the dirty toner from passing through the pressure contact portion when the web sheet 164 is pressed against the heating roller 161 by the pressure of the pressure roller 165. This is considered at the device design stage and is set at a constant pressure.

Further, the web sheet 164 is always moved by a predetermined amount by driving the feeding roller 164a and the take-up roller 164b when the number of sheets to be printed (the number of sheets passing through the fixing mechanism) reaches a certain number. The heating roller 161 is controlled to be cleaned by an unused web sheet surface.
In this way, the toner adhering to the heating roller 161 is cleaned.

In addition, as a cleaning mechanism using the above-described web cleaning method, two pressure rollers that press the web sheet are provided, and the web sheet is brought into contact with the heating roller in a wide range to further improve the cleaning effect. A cleaning mechanism has been proposed (see Patent Document 2).
JP 2001-166626 A JP 2006-65230 A

  However, the cleaning mechanism using the conventional web cleaning method has the following problems.

  When energization of the fixing mechanism of the apparatus is continued (during the printing process, in the standby mode, in the energy saving mode, etc.), the recovered toner at the portion in pressure contact with the surface of the heating roller on the web sheet It is in a molten state by a control temperature (generally referred to as “fixing set temperature”). This fixing set temperature is a temperature that is set so that the melting temperature of the toner is sufficiently lower than the fixing set temperature, and the sheet passing through the fixing nip is warmed and unfixed toner is melted and fixed on the sheet. is there. The fixing set temperature is approximately 160 to 200 ° C. when the melting temperature of the toner is 120 to 150 ° C.

  However, during the warm-up immediately after the energization of the apparatus is started, only a part of the control unit and the display unit of the apparatus are energized and the energization power to the fixing mechanism is 0 W during the power saving mode. During the return from the printing process to the print processing step, the surface temperature of the heating roller is lower than the set fixing temperature, so the collected toner staying in the pressure contact portion of the web sheet cleaned in the previous step is not in a molten state. It is in a solidified state.

  When the heating roller rotates in contact with the solidified recovered toner, the surface of the heating roller is damaged, not only the life characteristic of the heating roller is deteriorated, but also the web sheet pressed against the damaged heating roller There was a problem that the cleaning performance also deteriorated.

  Further, when a print request is made immediately after the heating roller surface reaches the fixing set temperature, the toner on the web sheet does not reach the melting temperature even if the heating roller surface reaches the fixing set temperature. It is in a semi-molten state (change process from a solidified state to a softened state). When newly collected molten toner is added to the collected toner in such a surface state by the next cleaning operation, the collected toner on the web sheet in the semi-molten state (the previously collected toner) is used for the current collected toner. The amount of heat is lost, and the state rapidly changes from the molten state to the semi-molten state. A “cleaning failure” occurs in the web cleaning section.

  Specifically, the semi-molten recovered toner passes through the web sheet pressed by the pressure roller and adheres again to the surface of the heating roller, leading to a reduction in cleaning performance, and the toner adhering to the surface of the heating roller is reduced. There has been a problem in that so-called “fogging toner” or “stain on the back side of the printing paper” is transferred onto the paper, leading to a reduction in printing quality. Such a problem becomes particularly prominent when there is one pressure contact roller.

  Here, an example of the temperature transition of the toner collected by the web sheet will be described with reference to the drawings. FIG. 9 is a graph showing the temperature transition of the toner collected by the cleaning mechanism of the fixing device mounted on the conventional image forming apparatus.

  As shown in FIG. 9, the toner collected by the web sheet of the cleaning mechanism is not in a molten state but in a semi-molten state immediately after completion of warm-up of the fixing device. In this state, if a print request is made immediately after the warm-up is completed, the contaminated toner (molten state) on the surface of the heating roller comes into contact with the surface of the collected toner in the semi-molten state, so that the temperature is deprived and the surface of the heating roller is cleaned. As a result, the performance deteriorates and toner smears on the paper.

  The present invention has been made in view of the above-described conventional problems. By changing the contact state between the roller member to be cleaned and the web sheet, the surface of the roller member adheres to the surface without being damaged. It is an object of the present invention to provide a cleaning mechanism capable of reliably removing toner, a fixing device using the same, and an image forming apparatus.

In order to solve the above-described problems, the cleaning mechanism according to the present invention, a fixing device using the same, and an image forming apparatus are configured as follows.
The cleaning mechanism according to claim 1 is a cleaning mechanism that cleans the surface of the roller body by pressing the web member against the outer peripheral surface of the rotating roller member, and the contact state between the roller member and the web member is changed. A web member pressing means for changing is provided.
In the present invention, the contact state between the roller member and the web member includes the size of the contact area between the roller member and the web member, and the magnitude of the pressure contact force of the web member against the roller member.

  In addition to the configuration described in claim 1, the cleaning mechanism described in claim 2 includes, as the configuration of the web member press contact unit, a plurality of press rollers that press the web member against the roller member, and the press roller It comprises roller contact / separation means for performing contact / separation operation with respect to the roller member, and drive means for driving the roller contact / separation means.

  The cleaning mechanism described in claim 3 is characterized in that, in addition to the configuration described in claim 2, as the configuration of the web member press contact unit, the roller contact / separation unit is driven by one drive unit. is there.

  According to a fourth aspect of the present invention, in addition to the configuration described in the second or third aspect, the web member press-contacting unit is configured such that any one of the plurality of press-contact rollers is the roller member. The other pressure contact rollers are separated from the roller member when they are pressed against each other.

According to a fifth aspect of the present invention, in addition to the configuration described in any one of the second to fourth aspects, the web member press-contacting unit includes any one of the plurality of press-contact rollers. A web tension adjusting means for keeping the tension of the web member constant even when the roller is in pressure contact with the roller member is provided.
In the present invention, as the web tension adjusting means, a tension roller may be used so as to apply tension to the web member.

  A cleaning mechanism according to a sixth aspect of the invention includes a holding member that simultaneously holds the plurality of pressure contact rollers as a configuration of the roller contact / separation means in addition to the configuration according to any one of the second to fifth aspects. And an eccentric cam that acts on the holding member in conjunction with the driving means, and an elastic member that acts on the holding member and urges some of the pressure rollers to the roller member side. These are provided.

  The fixing device according to claim 7, wherein at least one roller member includes a pair of roller members each having a heating unit, and a recording in which an unfixed toner image is formed at a nip portion where the roller members are pressed against each other. A fixing roller including a fixing roller that melts the toner image by passing the medium and fixes the toner image on the recording medium, and a cleaning mechanism that cleans the roller surface by bringing a web member into contact with the outer peripheral surface of the fixing roller. It is an apparatus, The cleaning mechanism as described in any one of Claims 1 thru | or 6 is used as the said cleaning mechanism.

  The image forming apparatus according to claim 8, wherein an electrostatic latent image is formed and a toner image is formed based on the electrostatic latent image, and an image forming unit including a photosensitive drum, and toner is applied to the photosensitive drum. A developing unit having a developing roller to be supplied; a transfer unit for transferring a toner image formed on the photosensitive drum to a conveyed recording medium; and at least one roller member having a heating unit. A fixing unit that melts the toner image and fixes the toner image on the recording medium by passing a recording medium on which an unfixed toner image is formed through a nip portion where the roller members are pressed against each other. And a fixing device including a roller and a cleaning mechanism that cleans the surface of the roller by bringing a web member into contact with the outer peripheral surface of the rotating fixing roller, and is formed on the surface of the photosensitive drum by electrophotography. In the image forming apparatus for transferring and outputting a toner image onto a recording medium, the cleaning mechanism includes a web member pressing means for changing a contact state between the fixing roller and the web member. It is.

  An image forming apparatus according to a ninth aspect includes, in addition to the configuration according to the eighth aspect, the cleaning mechanism according to any one of the second to sixth aspects as the cleaning mechanism. To do.

  The image forming apparatus according to claim 10, in addition to the configuration according to claim 9, includes a plurality of operation modes including a standby mode for controlling the operation of the fixing device, an energy saving mode, and a power saving mode, and the web member When the pressure roller, which is arranged downstream of the fixing roller in the rotation direction of the fixing roller, is pressed against the fixing roller among the plurality of pressure rollers constituting the pressure contact means, the fixing device is used for printing processing from the standby mode during warm-up. And during the return process, and after the surface temperature of the fixing roller reaches the set temperature, the process proceeds to the print processing process.

  In the present invention, the standby mode includes a state in which the fixing device is energized to maintain the surface of the fixing roller at the fixing set temperature, and the energy saving mode is a state in which the surface of the fixing roller is set higher than the fixing set temperature. The power-saving mode includes a state in which a part of the control unit and the display unit of the image forming apparatus are energized and heating of the fixing roller is stopped, that is, the fixing device. This includes a state in which the energization power is set to 0 W (watts).

  An image forming apparatus according to an eleventh aspect of the invention includes, in addition to the configuration according to the ninth or tenth aspect, a pressure roller disposed on the upstream side in the rotation direction of the fixing roller among the plurality of pressure rollers. When the pressure contact is made, the fixing device is moved to a printing process step after a predetermined time has elapsed after the warm-up is completed.

  The image forming apparatus according to a twelfth aspect is the image forming apparatus according to the twelfth aspect, in addition to the configuration according to the eleventh aspect, in a state where the pressing roller disposed downstream in the rotation direction of the fixing roller is in pressure contact with the fixing roller. After the cleaning process by the web member, the time until the temperature of the collected toner becomes equal to or higher than the melting temperature of the toner is used. That is, the predetermined time is a period of time until the surface temperature of the fixing roller becomes equal to or higher than the melting temperature of the toner after the dirty toner on the roller is collected by the web member, and the collected toner is in a molten state. To do.

  According to a thirteenth aspect of the present invention, in addition to the configuration described in the eleventh aspect, the pressing roller disposed downstream in the rotation direction of the fixing roller is in contact with the fixing roller for the predetermined time. After the cleaning process by the web member is performed, it is a time until the web member is moved by a predetermined amount. That is, for the predetermined time, the web member used for the cleaning process is wound up in a state where the pressure roller disposed downstream in the rotation direction of the fixing roller is in pressure contact with the fixing roller, and the unused portion is disposed. It takes time to complete.

  In addition to the configuration described in claim 13, the image forming apparatus according to claim 14 is configured such that the moving amount of the web member is longer than the distance between the axes of a plurality of pressure rollers that are alternately pressed against the fixing roller. This is a feature. That is, the amount of movement of the web member that is wound and moved when the pressure contact state of the plurality of pressure contact rollers with the fixing roller is at least longer than the distance between the positions where the plurality of pressure contact rollers are disposed. .

According to the first aspect of the present invention, there is provided a cleaning mechanism for cleaning the surface of the roller body by pressing the web member against the outer peripheral surface of the rotating roller member, wherein the roller member and the web member are in contact with each other. By changing the contact state between the roller member and the web member in accordance with the surface state of the roller member to be cleaned, the surface of the roller member is not damaged. The toner adhering to the toner can be reliably removed.
Here, the surface state of the roller member includes the surface temperature of the roller member and the state of toner attached to the surface.

In addition to the common effects obtained by the inventions according to claims 1 to 14, according to the inventions described in the claims, the following effects can be obtained.
Specifically, according to the invention described in claim 2, in addition to the effect obtained by the invention described in claim 1, in addition to the structure described in claim 1, as the structure of the web member press contact means, A plurality of pressure rollers that press the web member against the roller member; roller contact / separation means that performs contact / separation operation of the pressure roller with respect to the roller member; and drive means that drives the roller roller contact / separation means. Thus, any one of the plurality of pressure rollers can be selectively brought into pressure contact with the roller member, and the contact state between the roller member and the web member can be easily changed.

  According to the invention described in claim 3, in addition to the effect obtained by the invention described in claim 2, as the configuration of the web member press contact means, the roller contact / separation means is driven by one drive means. As a result, the configuration of the apparatus can be simplified, and the pressure contact roller that performs the contact / separation operation with a simple configuration can be synchronized.

  According to the invention described in claim 4, in addition to the effect obtained by the invention described in claim 2 or 3, as a configuration of the web member pressing means, any one of the plurality of pressing rollers is pressed. When the roller is in pressure contact with the roller member, the other pressure contact rollers are separated from the roller member, so that the roller according to the contact position between each pressure contact roller and the roller member. The contact state between the member and the web member can be easily changed.

According to the invention described in claim 5, in addition to the effect obtained by the invention described in any one of claims 2 to 4, the configuration of the web member pressing means includes the plurality of pressing rollers. Even if any one of the pressure contact rollers is in pressure contact with the roller member, the web member is provided with web tension adjusting means for making the tension of the web member constant, so that the web member does not become slack and the web member The cleaning performance can be stabilized without causing wrinkles or tears due to the slanting.
In the present invention, the apparatus configuration can be simplified by using a tension roller as the web tension adjusting means to apply tension to the web member.

  According to the invention described in claim 6, in addition to the effect obtained by the invention described in any one of claims 2 to 5, the plurality of press contact rollers are provided as the configuration of the roller contact / separation means. A holding member that holds simultaneously, an eccentric cam that acts on the holding member in conjunction with the driving means, and a portion of the plurality of pressure rollers that act on the holding member toward the roller member side A plurality of pressing rollers simultaneously held by the holding member can be easily brought into and out of contact with the roller member by the eccentric cam. By disposing the eccentric cam on the side opposite to the side on which the eccentric cam acts, it is possible to achieve the followability of the pressure roller that makes contact and separation with a simple configuration, and to press the pressure roller against the roller member.

According to the seventh aspect of the present invention, at least one roller member is provided with a pair of roller members provided with heat generating means, and an unfixed toner image is formed at a nip portion where the roller members are pressed against each other. A fixing roller that melts the toner image by passing the recording medium and fixes the toner image on the recording medium; and a cleaning mechanism that cleans the roller surface by bringing a web member into contact with the outer peripheral surface of the fixing roller. In the fixing device, by using the cleaning mechanism according to any one of claims 1 to 6 as the cleaning mechanism, the fixing roller and the web member are arranged in accordance with the surface state of the fixing roller. By changing the contact state, the toner adhering to the surface can be surely removed without damaging the surface of the fixing roller.
Here, the surface state of the fixing roller includes the surface temperature of the fixing roller and the state of adhered toner.

According to the invention described in claim 8, an image forming unit including a photosensitive drum on which an electrostatic latent image is formed and a toner image is formed based on the electrostatic latent image, and toner is applied to the photosensitive drum. A developing unit having a developing roller to be supplied; a transfer unit for transferring a toner image formed on the photosensitive drum to a conveyed recording medium; and at least one roller member having a heating unit. A fixing unit that melts the toner image and fixes the toner image on the recording medium by passing a recording medium on which an unfixed toner image is formed through a nip portion where the roller members are pressed against each other. And a fixing device including a roller and a cleaning mechanism that cleans the surface of the roller by bringing a web member into contact with the outer peripheral surface of the rotating fixing roller, and is formed on the surface of the photosensitive drum by electrophotography. In the image forming apparatus that transfers and outputs a toner image onto a recording medium, the cleaning mechanism includes a web member pressure contact unit that changes a contact state between the fixing roller and the web member. By changing the contact state between the fixing roller and the web member according to the surface state of the toner, it is possible to reliably remove the toner adhering to the surface without damaging the surface of the fixing roller.
Here, the surface state of the fixing roller includes the surface temperature of the fixing roller and the state of toner adhering to the surface.

  According to the invention described in claim 9, in addition to the effect obtained by the invention described in claim 8, the cleaning mechanism according to any one of claims 2 to 6 is provided as the cleaning mechanism. Thus, any one of the plurality of pressure rollers can be selectively brought into pressure contact with the fixing roller, and the contact state between the fixing roller and the web member can be easily changed.

  According to the invention described in claim 10, in addition to the effect obtained by the invention described in claim 9, a plurality of operation modes including a standby mode for controlling the operation of the fixing device, an energy saving mode, and a power saving mode are provided. When the pressure roller arranged on the downstream side in the rotation direction of the fixing roller among the plurality of pressure rollers constituting the web member pressure contact means is pressed against the fixing roller, the fixing device is warming up and is in a standby mode. From the time when the fixing roller surface temperature reaches the set temperature to the time when the process proceeds to the printing process step, the pressure contact disposed on the downstream side in the rotation direction of the fixing roller. The surface of the fixing roller can be cleaned before the printing process is performed in a state where the web member is pressed against the roller.

  According to the invention described in claim 11, in addition to the effect obtained by the invention described in claim 9 or 10, the pressure contact roller disposed on the upstream side in the rotation direction of the fixing roller among the plurality of pressure contact rollers. Is pressed to the fixing roller when the fixing device shifts to the print processing step after a predetermined time has elapsed after the warm-up is completed, and the pressing roller is arranged on the downstream side in the rotation direction of the fixing roller. The surface of the fixing roller when the printing process is performed can be cleaned by changing the pressed state from the state in which the web member is pressed.

  According to the invention described in claim 12, in addition to the effect obtained by the invention described in claim 11, the pressure contact roller arranged on the downstream side in the rotation direction of the fixing roller is applied to the fixing roller for the predetermined time. After the cleaning process by the web member in the pressed state, the time until the temperature of the collected toner becomes equal to or higher than the melting temperature of the toner is set so that the newly collected toner is collected first. Since the toner is recovered by the web member in a melted state without taking heat away, the surface of the fixing roller before the printing process can be better cleaned.

  According to the invention described in claim 13, in addition to the effect obtained by the invention described in claim 11, the pressure roller disposed on the downstream side in the rotation direction of the fixing roller is applied to the fixing roller for the predetermined time. The time until the web member is moved by a predetermined amount after the web member is cleaned in the pressed state, that is, until the web member used in the cleaning process is wound up and an unused portion is arranged. Therefore, even when the toner collected during the pretreatment process (the toner collected by the pressure roller on the upstream side in the rotation direction of the fixing roller) is solidified, the unused portion of the web member is pressed against the fixing roller. This is possible and will not be rubbed by the already collected toner when the fixing roller rotates, so it will be stable without damaging the surface of the fixing roller. It is possible to perform the cleaning.

  According to the invention described in claim 14, in addition to the effect obtained by the invention described in claim 13, the movement amount of the web member is set between the shafts of a plurality of press rollers that are alternately pressed against the fixing roller at least. The web member is pressed against the upstream pressure roller from the downstream pressure roller in the rotation direction of the fixing roller by setting the length equal to or longer than the distance, that is, the length equal to or longer than the arrangement distance at which the plurality of pressure rollers are arranged. When the pressure roller switching operation is performed, the unused portion of the web member can be pressed against the fixing roller, so that stable cleaning performance can be maintained, and print quality can be improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram showing the overall configuration of an image forming apparatus employing a cleaning mechanism according to the present invention, and FIG. 2 is a partial detail view showing the configuration of the main body of the image forming apparatus.

  The image forming apparatus 1A according to the present embodiment uses a predetermined sheet-like recording sheet (hereinafter, referred to as a sheet) that serves as a recording medium by electrophotographic processing of image data read by a scanner or the like or image data transmitted from the outside. An image forming unit 14 including a photosensitive drum 3 on which an electrostatic latent image is formed and a toner image is formed based on the electrostatic latent image, and a photosensitive member. A developing device (developing unit) 2 provided with a developing roller 2a for supplying toner to the drum 3, a transfer mechanism (transfer unit) 10 for transferring a toner image formed on the photosensitive drum 3 to the conveyed paper, And a fixing unit (fixing device) 6 for fixing an unfixed toner image on a sheet, and image formation controlled to transfer the toner image formed on the surface of the photosensitive drum 3 to the sheet P by electrophotography. apparatus In A, the surface of the heating roller (fixing roller) 61 constituting the fixing unit 6 as a cleaning mechanism for cleaning, in which a cleaning mechanism 63 according to the present invention.

First, the overall configuration of the image forming apparatus 1A according to the present embodiment will be described.
As shown in FIGS. 1 and 2, the image forming apparatus 1 </ b> A mainly includes an exposure unit 1, a developing device (developing unit) 2, a photosensitive drum 3, a charger 4, a charge eliminating device 41, a cleaner unit 5, and a fixing unit. 6, an apparatus main body 1A1 including a paper transport device 7, a paper feed tray 8, a paper discharge tray 9, a transfer mechanism (transfer unit) 10, and the like, and an automatic document processing apparatus 1A2.

  A document placing table 21 made of transparent glass on which a document is placed is provided on the upper surface of the apparatus main body 1A1. Above the document placing table 21, the automatic document processing device 1A2 is swingably opened upward. On the other hand, a scanner unit 22 serving as a document reading unit that reads image information of a document is disposed below the document placement table 21.

  Below the scanner unit 22, an exposure unit 1, a developing device 2, a photosensitive drum 3, a charger 4, a charge removal device 41, a cleaner unit 5, a fixing unit 6, a paper transport device 7, a paper discharge tray 9, and a transfer mechanism. 10 is disposed, and a paper feed tray 8 in which the paper P is stored is disposed below.

  The exposure unit 1 performs exposure by irradiating the surface of the photosensitive drum 3 uniformly charged by the charger 4 with laser light according to image data (image information for printing) output from an image processing unit (not shown). Thus, it has a function of writing and forming an electrostatic latent image corresponding to image data on the surface of the photosensitive drum 3.

  The exposure unit 1 is disposed immediately below the scanner unit 22 and above the photosensitive drum 3, and employs laser scanning units (LSU) 13 a and 13 b including a laser irradiation unit 11 and a reflection mirror 12. In the present embodiment, in order to perform high-speed printing processing, a technique of using a plurality of laser beams to reduce the irradiation timing is adopted, and a two-beam technique is adopted.

  In this embodiment, the laser scanning units (LSU) 13a and 13b are used for the exposure unit 1, but a light emitting element arranged in an array, for example, an EL or LED writing head may be used. .

  As shown in FIG. 2, the photosensitive drum 3 has a cylindrical shape, is disposed below the exposure unit 1, and is rotated in a predetermined direction (the direction of arrow A in the figure) by a driving unit and a control unit (not shown). Is controlled. Along the outer peripheral surface of the photosensitive drum 3, the sheet peeling claw 31, the cleaner unit 5, the charger 4 as an electric field generating unit, and the development head toward the downstream side in the rotational direction of the photosensitive drum with reference to the position after completion of image transfer. The device 2 and the static eliminator 41 are arranged in this order.

  The sheet peeling claw 31 is disposed so as to be able to contact and separate from the outer peripheral surface of the photosensitive drum 3 by a solenoid 32. The sheet peeling claw 31 is stuck to the surface of the photosensitive drum 3 when the unfixed toner image on the photosensitive drum 3 is transferred to the sheet P in a state of being in contact with the outer peripheral surface of the photosensitive drum 3. The sheet P is peeled off.

  Note that a driving motor or the like may be employed as the driving means for the sheet peeling claw 31 instead of the solenoid 32, and other driving means may be selected.

  The developing device 2 visualizes the electrostatic latent image formed on the photosensitive drum 3 with black toner, and is downstream of the charger 4 in the rotating direction of the photosensitive drum (the direction of arrow A in the figure). It is arranged substantially horizontally (right side in the figure) on the side of the photosensitive drum 3. A registration roller 15 is disposed below the developing unit 2 on the upstream side in the recording medium conveyance direction.

  The registration roller 15 aligns the front end of the paper P supplied from the paper feed tray 8 and the toner image on the photoconductive drum 3 and conveys it between the photoconductive drum 3 and the transfer belt 103 (not shown). The operation is controlled by the drive means and the control means.

The charger 4 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential, and is disposed above the photosensitive drum 3 and in the vicinity of the outer peripheral surface thereof.
In this embodiment, the charger type charger 4 is used. However, a contact type roller type or a brush type may be used.

  The static eliminator 41 is a pre-transfer static eliminator for reducing the surface potential of the photosensitive drum 3 in order to facilitate the transfer of the toner image formed on the surface of the photosensitive drum 3 to the paper P. It is arranged downstream of the developing device 2 in the drum rotating direction and close to the outer peripheral surface below the photosensitive drum 3.

  In the present embodiment, the static eliminator 41 is configured using a static elimination electrode. However, a static elimination lamp may be used in place of the static elimination electrode, or other static elimination may be used.

  The cleaner unit 5 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer. The cleaner unit 5 is located at a position substantially opposite to the developing device 2 with the photosensitive drum 3 interposed therebetween. The drum 3 is disposed substantially horizontally (left side in the drawing) on the side.

  As described above, the electrostatic image visualized on the photosensitive drum 3 is applied from the transfer mechanism 10 onto the paper P on which the electric field having the opposite polarity to the electric charge of the electrostatic image is conveyed. Transferred onto P. For example, when the electrostatic image has a charge of (−) polarity, the applied polarity of the transfer mechanism 10 is (+) polarity.

As shown in FIG. 2, the transfer mechanism 10 is bridged by a driving roller 101, a driven roller 102, and other rollers, and has a predetermined resistance value (1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm in this embodiment). The transfer belt unit is disposed below the photosensitive drum 3 so that the surface of the transfer belt 103 contacts a part of the outer peripheral surface of the photosensitive drum 3. Has been. The transfer belt 103 conveys the paper P while pressing it against the photosensitive drum 3.

  An elastic conductive roller 105 capable of applying a transfer electric field with a conductivity different from that of the driving roller 101 and the driven roller 102 is disposed at the contact portion 104 between the photosensitive drum 3 and the transfer belt 103.

  The elastic conductive roller 105 is made of a soft material such as elastic rubber or foamable resin. Since the elastic conductive roller 105 has elasticity, the photosensitive drum 3 and the transfer belt 103 are not in line contact but in surface contact having a predetermined width (referred to as a transfer nip), so that the sheet P to be conveyed is conveyed. The transfer efficiency can be improved.

  Further, on the downstream side of the transfer area of the transfer belt 103 in the sheet conveyance direction, a discharge roller 106 for discharging the electric field applied to the sheet P to be transferred in the transfer area and smoothly transferring to the next process is transferred. It is arranged on the back side of the belt 103.

  In addition, the transfer mechanism 10 is provided with a cleaning unit 107 that removes dirt from the residual toner on the transfer belt 103 and a plurality of charge removal mechanisms 108 that perform charge removal on the transfer belt 103. As a technique for performing static elimination used in the static elimination mechanism 108, there is a technique of grounding through an apparatus, or a technique of positively applying a polarity opposite to the polarity of the transfer electric field.

  The electrostatic image (unfixed toner) transferred onto the paper P by the transfer mechanism 10 is conveyed to the fixing unit 6 and is pressurized and heated to melt the unfixed toner and be fixed on the paper P. .

  As shown in FIG. 2, the fixing unit 6 includes a heating roller 61 and a pressure roller 62 as a pair of fixing rollers, and the heating roller 61 in a state where the paper P is sandwiched between the heating roller 61 and the pressure roller 62. , And the toner image transferred on the paper P is melted and fixed by passing between the heating roller 61 and the pressure roller 62. A conveyance roller 16 that conveys the paper P is provided downstream of the fixing unit 6 in the paper conveyance direction.

  The heating roller 61 is provided with a sheet peeling claw 611, a roller surface temperature detecting member (thermistor) 612, and a cleaning mechanism 63 on the outer periphery thereof, and the heating roller surface is set to a predetermined temperature (fixing set temperature: approximately) on the inner periphery. 160 to 200 ° C.) is provided.

  The pressure roller 62 is provided with a pressure member 621 that can be pressed against the heating roller 61 at a predetermined pressure amount at both ends of the roller. Similarly to the outer periphery of the roller 61, a sheet peeling claw 622 and a roller surface cleaning member 623 are disposed, and a heat source 624 for heating the pressure roller surface from the inside is provided on the inner periphery.

  As shown in FIG. 2, the fixing unit 6 is configured to remove unfixed toner on the conveyed paper P at a pressure contact portion (called a fixing nip portion) 600 between the heating roller 61 and the pressure roller 62. The unfixed toner is fixed onto the paper P by the application of heat onto the paper P by the pressure contact force between the heating roller 61 and the pressure roller 62.

  The paper feed tray 8 is used for accumulating a plurality of sheets (paper sheets) on which image information is output (printed). The exposure unit 1, the developing device 2, the photosensitive drum 3, the charger 4, and the charge eliminating device. The image forming unit 14 is configured below the image forming unit 14 including the apparatus 41, the cleaner unit 5, the fixing unit 6, and the like. A paper pickup roller 8 a is disposed on the paper discharge side of the paper feed tray 8.

  The sheet pickup roller 8a picks up the sheets P stacked and accommodated in the sheet feed tray 8 one by one from the uppermost layer, and moves toward the downstream side (for convenience, the flow side (cassette side) of the sheet P is upstream and discharged). The paper side is the downstream side.) The paper is conveyed to the registration roller (also referred to as "idle roller") 15 side on the paper conveyance path 7a constituting the paper conveyance device 7.

  Further, in the image forming apparatus 1A according to the present embodiment, in order to perform high-speed printing processing, a plurality of standard size sheets P can be stored in each tray below the image forming unit 14 in a plurality of 500 to 1500 sheets. On the other hand, a large-capacity paper feed cassette 81 capable of storing a large amount of a plurality of paper types is arranged on the side of the apparatus, and mainly above the large-capacity paper feed cassette 81. A manual paper feed tray 82 corresponding to printing of an irregular size is provided.

  The paper discharge tray 9 is disposed on the side of the apparatus opposite to the manual paper feed tray 82. Further, instead of the paper discharge tray 9, a post-processing device (device for performing stapling, punching, etc.) of paper discharge, a multi-stage paper discharge tray, and the like can be arranged as options.

  Next, the characteristic cleaning mechanism 63 according to the present embodiment will be described in detail with reference to the drawings. FIG. 3 is an explanatory diagram showing a schematic configuration of the cleaning mechanism provided in the fixing unit constituting the image forming apparatus according to the present embodiment.

  As shown in FIG. 3, the cleaning mechanism 63 according to this embodiment is a cleaning mechanism that cleans the surface of the heating roller 61 by pressing a web sheet (web member) 64 against the outer peripheral surface of the rotating heating roller 61. The web member pressing means 65 is provided for changing the contact state between the heating roller 61 and the web sheet 64 by the first pressing roller 651 and the second pressing roller 652.

  The web sheet 64 is cross-linked by the feed roller 64a and the take-up roller 64b disposed in the vicinity of the heating roller 61, and is a first pressure roller that is disposed within the cross-linked range by the web member pressing means 65. It is brought into pressure contact with the surface of the heating roller 61 by the pressure contact force of any one of the pressure roller 651 and the second pressure roller 652. The web sheet 64 is composed of fibers having a thickness of 50 to 150 μm, and the molten dirt toner adhering to the heating roller 61 in contact with the heating roller 61 penetrates into the fiber weave of the web sheet 64 so that the web sheet 64 The sheet 64 is collected inside.

  Further, the web sheet 64 moves a predetermined amount by driving the feed roller 64a and the take-up roller 64b when the number of print processed sheets (the number of sheets passing through the fixing mechanism) reaches a predetermined number, and is always unused. The surface of the heating roller 61 is controlled to be cleaned by the web sheet surface. The moving direction of the web sheet 64 moves in the direction (the direction of arrow D in FIG. 3) opposite to the direction of rotation of the heating roller 61 in contact (the direction of arrow C in FIG. 3).

  The web member pressing means 65 is a first pressing roller 651 and a second pressing roller 652 that press the web sheet 64 against the heating roller 61, and the contacting and separating operation of the first pressing roller 651 and the second pressing roller 652 with respect to the heating roller 61. A roller contact / separation structure (roller contact / separation means) 653, and a drive motor (drive means) 654 for driving the roller contact / separation structure 653.

  Further, the web member pressing means 65 is a tension roller that makes the tension of the web sheet 64 constant even when any one of the first pressing roller 651 and the second pressing roller 652 is pressed against the heating roller 61. Web tension adjusting means) 66a, 66b. The tension rollers 66a and 66b are disposed between the feeding roller 64a and the second pressure roller 652 and between the first pressure roller 651 and the take-up roller 64b, respectively, within a range where the web sheet 64 is cross-linked, and heated. “Talmi” is generated in the web sheet 64 at the site where the surface of the roller 61 is cleaned (the site pressed against the heating roller 61 by the first pressure roller 651 or the second pressure roller 652), the feed roller 64a and the winding roller 64 A constant tension is maintained to always obtain a constant cleaning performance so that the web sheet 64 is not skewed when the roller 64b is driven by each drive.

  The roller contact / separation structure 653 mainly acts on one end of the holding bar 653a in conjunction with a holding bar (holding member) 653a that holds the first pressing roller 651 and the second pressing roller 652 at the same time, and the drive motor 654. The eccentric cam 653b and a coil spring (elastic member) 653c that acts on the other end side of the holding bar 653a and biases the second pressure roller 652 toward the heating roller side. The roller contact / separation structure 653 rotates the eccentric cam 653b by the drive motor 654 to perform the contact / separation operation of the first pressure contact roller 651 and the second pressure contact roller 652 held by the holding bar 653a with respect to the heating roller 61. It has become.

  The first pressure roller 651 and the second pressure roller 652 are connected to both ends of the holding bar 653a via connection bars 651a and 652a, respectively. The first pressure roller 651 is disposed on the upstream side of the second pressure roller 652 in the rotation direction (arrow C direction) of the heating roller 61. The first pressure roller 651 is formed with a larger outer diameter than the second pressure roller 652.

  The holding bar 653a is pivotally supported by a support shaft 653a1 at a substantially central portion in the longitudinal direction, and the holding bar 653a is in contact with the one end on the one end side to which the first pressure contact roller 651 is connected. An eccentric cam 653b that swings is arranged. A coil spring 653c that urges the second pressure roller 652 toward the heating roller 61 is disposed at the other end where the second pressure roller 652 is coupled.

  By the web member pressing means 65 configured as described above, the first pressing roller 651 causes the heating roller 61 to reach the fixing set temperature during normal printing processing, that is, immediately after warming up and returning from the power saving mode. Except for the printing process immediately after, the fixing device is driven and controlled so as to come into pressure contact with the surface of the heating roller 61 when the fixing device shifts to a printing process after a predetermined time has elapsed after the warm-up.

  In the present embodiment, the above-described predetermined time is collected after the cleaning process by the web sheet 64 is performed in a state where the second pressure roller 652 arranged on the downstream side in the rotation direction of the heat roller 61 is in pressure contact with the heat roller 61. The time until the temperature of the toner thus obtained becomes equal to or higher than the melting temperature of the toner.

In addition, the predetermined time is determined after the web sheet 64 is cleaned after the second pressure roller 652 disposed on the downstream side in the rotation direction of the heating roller 61 is in pressure contact with the heating roller 61. It shall include the time to move quantitatively.
The moving time of the web sheet 64 is a time required to move at least the length between the axes of the first pressing roller 651 and the second pressing roller 652.

  On the other hand, the second pressure roller 652 is a heating roller that is not in a normal printing process, that is, during the warming up of the fixing device, during the return process for the printing process from the standby mode, immediately after the warming up, and from the power saving mode. When the process shifts to the printing process immediately after 61 reaches the fixing set temperature, the drive is controlled so as to be in pressure contact with the surface of the heating roller 61.

  When one of the first pressure roller 651 and the second pressure roller 652 is pressed toward the heating roller 61, the other pressure roller is separated from the heating roller 61. Has been.

Next, the cleaning action of the heating roller 61 by the cleaning mechanism 63 of this embodiment will be described with reference to the drawings.
4 is an explanatory view showing a state in which the web sheet is pressed against the heating roller by the first pressure roller in the cleaning mechanism of the present embodiment, and FIG. 5 is a state in which the web sheet is pressed against the heating roller by the second pressure roller in the cleaning mechanism. It is explanatory drawing which shows.

  In the cleaning mechanism 63, when the web sheet 64 is pressed against the heating roller 61 by the first pressing roller 651, as shown in FIG. 4, the eccentric cam 653b is rotated, and the holding bar 653a on the first pressing roller 651 side is rotated. The contact position with the eccentric cam 653b moves in a direction approaching the heating roller 61.

  As a result, the first pressure roller 651 connected to the holding bar 653a is pushed toward the heating roller 61 and pressed against the heating roller 61 as the eccentric cam 653b rotates. At this time, the second pressure roller 652 side of the holding bar 653a moves away from the heating roller 61 against the spring force of the coil spring 653c, and the second pressure roller 652 is separated from the heating roller 61. Become.

  The web sheet 64 is pressed against the heating roller 61 at the nip B between the first pressing roller 651 and the heating roller 61. The pressing force to the web sheet 64 by the first pressure roller 651 is set by the outer shape (the amount of eccentricity) of the eccentric cam 653b. At this time, a part of the web sheet 64 positioned on the upstream side in the rotation direction of the heating roller 61 is disposed at an inclination angle θ <b> 1 with respect to the surface of the heating roller 61.

  On the other hand, when the web sheet 64 is pressed against the heating roller 61 by the second pressing roller 652, as shown in FIG. 5, the eccentric cam 653b is further rotated or rotated in the return direction, so that the first of the holding bar 653a. The position of contact with the eccentric cam 653 b on the pressure roller 651 side moves in a direction away from the heating roller 61.

  Thus, the first pressure roller 651 connected to the holding bar 653a is separated from the heating roller 61 with the rotation of the eccentric cam 653b. At this time, the second pressure roller 652 side of the holding bar 653a is pushed in the direction approaching the heating roller 61 by the spring force of the coil spring 653c, and the second pressure roller 652 is pressed against the heating roller 61. It becomes.

  The web sheet 64 is pressed against the heating roller 61 at the nip C between the second pressing roller 652 and the heating roller 61. The pressing force applied to the web sheet 64 by the second press contact roller 652 is set by a coil spring 653c. At this time, a part of the web sheet 64 positioned on the upstream side in the rotation direction of the heating roller 61 is arranged at an inclination angle θ <b> 2 with respect to the surface of the heating roller 61.

  As described above, the contact state of the web sheet 64 with the heating roller 61 is different between the first pressure roller 651 and the second pressure roller 652. That is, by forming the outer diameter of the first pressure roller 651 larger than the outer diameter of the second pressure roller 652, the nip amount of the nip portion B becomes larger than the nip portion C.

  Therefore, when the web sheet 64 is pressed against the heating roller 61 by the first pressure roller 651, the contact area between the web sheet 64 and the heating roller 61 can be increased as compared with the case where the second pressure roller 652 is used. Therefore, the molten toner can be effectively cleaned.

  Further, the arrangement state of the web sheet 64 positioned on the upstream side in the rotation direction of the heating roller 61 includes an inclination angle θ1 of the web sheet 64 by the first pressure roller 651 and an inclination angle θ2 of the web sheet 64 by the second pressure roller 652. In comparison, the inclination angle θ2 by the first pressure roller 651 is larger.

  Therefore, when the web sheet 64 is pressed against the heating roller 61 by the first pressure roller 651, when the web sheet 64 is moved after the cleaning process, the inclination angle θ1 of the web sheet 64 is large. As a result, the influence of rubbing against the toner collected inside the web sheet 64 can be reduced, so that the web sheet 64 can be moved without damaging the surface of the heating roller 61.

  In addition, when the web sheet 64 is pressed against the heating roller 61 by the second pressing roller 652, the inclination angle with respect to the heating roller 61 is small. For example, the surface of the heating roller 61 is impregnated with a lubricant or the like inside the web sheet 64. In the case where a function of applying the lubricant is provided, an improvement in the action of applying the lubricant by the web sheet 64 can be expected.

Next, the operation of the cleaning mechanism in the image forming apparatus of the present embodiment will be described based on a flowchart.
6 and 7 are flowcharts for explaining the operation of the cleaning mechanism in the image forming apparatus according to this embodiment.

  First, when energization is started for the image forming apparatus 1A (step S1), the control unit of the image forming apparatus 1A presses the web sheet 64 of the cleaning mechanism 63 constituting the fixing unit 6 with the heating roller 61. Is changed, the drive motor 654 that drives the eccentric cam 653b is energized (step S2).

  When it is confirmed that the second pressure roller 652 is pressed against the heating roller 61 by the rotation of the eccentric cam 653b in step S2 (step S3), the image forming apparatus 1A performs an initialization process (initialization of the photosensitive drum 3). Then, initialization of each sensor, processing for returning each drive unit to the home position, etc.) and warm-up of the fixing unit 6 are performed (step S4).

  Here, the reason why the driving motor 654 that rotates the eccentric cam 653b is driven to press the second pressing roller 652 against the heating roller 61 in step S2 and step S3 will be described below.

  In the present embodiment, the normal printing process is based on a technique in which the web sheet 64 is pressed against the heating roller 61 by the first pressing roller 651. According to this method, dirt toner on the surface of the heating roller 61 is collected at the upstream nip portion in the rotation direction of the first pressure roller 651 and the heating roller 61. In the normal printing process, the collected toner is in a molten state, penetrates into the gaps of the fibers constituting the web sheet 64 without damaging the heating roller 61, and is cleaned with a throwing effect on the web sheet 64. It is in a state.

  However, once energization is stopped, the surface of the heating roller 61 is generally lowered from the fixing set temperature to room temperature. In such a state, the first pressure roller 651 of the web sheet 64 and the heating roller 61 are heated. The collected toner collected at the pressure contact portion A of the roller 61 changes from a molten state to a solidified state. Then, when the fixing unit 6 is warmed up as part of the initialization process of the image forming apparatus 1A for the solidified collected toner, the heated roller 61 that does not reach the fixing set temperature rotates to be solidified. The collected toner will damage the surface of the heating roller.

  For this reason, in the present embodiment, the pressure contact state between the web sheet 64 and the heating roller 61 by the first pressure contact roller 651 or the second pressure roller 652 arranged in two is changed to the pressure contact state by the second pressure roller 652. Yes.

  For example, when the pressure roller during warm-up is the first pressure roller 651, the pressure roller during normal printing processing is the second pressure roller 652. In this state, the dirty web sheet 64 until the collected toner collected by the normal printing process is taken up by the take-up roller 64b reaches the fixing set temperature by the first pressure roller 651 during the warm-up process. There is a risk of scratching the surface of the heating roller 61 due to pressure contact with the non-heating roller 61.

  When the initialization process is processed in this manner (step S4), the control unit of the image forming apparatus 1A detects the heating roller surface temperature by the thermistor 612 disposed on the surface of the heating roller 61, and the heating roller 61 It is determined whether or not the surface has reached the fixing set temperature (step S5), and whether or not the initialization of the image forming apparatus 1A has been completed is determined (step S6).

  When the processes in steps S5 and S6 are completed, it is determined whether or not a print request has already been made based on whether or not there is image information that has been requested and stored in the control unit (step S7). When there is no print request, the image forming apparatus 1A enters a standby state, and the fixing unit 6 proceeds to a standby mode in which the surface of the heating roller 61 is maintained at the fixing set temperature.

  On the other hand, when there is a print request in step S7, it is determined whether or not printing conditions have been input (step S8). When it is confirmed that the input has been completed, printing processing is performed (step S7). S9).

  When the printing process is completed in step S9, the control unit of the image forming apparatus 1A determines whether it is time to move the web sheet 64 (step S10).

  The toner adhering to the surface of the heating roller 61 is collected at a contact point on the upstream side in the rotation direction of the heating roller 61 in the pressure contact portion of the web sheet 64 that is in pressure contact with the surface of the heating roller 61. In the determination of the movement timing, the web sheet 64 is sent out every time a predetermined number of printing processes elapses, and the roller 64a and the take-up roller 64b are driven to collect the collected toner on the unused web sheet surface, Since this is based on a web cleaning method that eliminates the contamination of the surface of the heating roller 61, the movement timing of the web sheet 64 is confirmed based on the number of times of printing processing, regardless of the degree of contamination of the press contact portion of the web sheet 64.

  If it is not necessary to move the web sheet 64 in the confirmation of the movement timing of the web sheet 64 in step S10, the presence or absence of the next printing is confirmed (step S11). When there is a next printing, the process returns to step S9, and when there is no next printing, a standby state is entered.

  On the other hand, if it is determined in step S10 that it is the movement timing of the web sheet 64, the feeding roller 64a and the take-up roller 64b of the web sheet 64 are driven, and the unused surface of the web sheet 64 is moved by the heating roller 61. The web sheet 64 is moved so as to face the surface (step S12).

  At this time, it is necessary to wind up the web sheet 64 until the portion of the web sheet 64 pressed by the second pressure roller 652 and attached with the collected toner moves from the pressure contact area by the first pressure roller 651 to the winding roller 46b side. is there. This is an indispensable control so that the collected toner collected by the web sheet 64 does not contaminate the heating roller 61 in the next printing process and cause deterioration in printing quality.

  When the web sheet 64 moves in this way (step S13), the eccentric cam 653b is changed to change the position of the web sheet 64 against the heating roller 61 from the position of the second pressure roller 652 to the position of the first pressure roller 651. The drive motor 654 to be rotated is driven to change the pressure contact position of the web sheet 64 to the heating roller 61 to the position by the first pressure contact roller 651 (step S14). If it is confirmed that the press contact position has been changed to the first press contact roller 651 (step S15), then the process returns to step S11, where the presence / absence of the next printing is confirmed, and the process is continued.

  With the above configuration, according to the present embodiment, the first pressure contact for pressing the web sheet 64 against the heating roller 61 as the cleaning mechanism 63 for cleaning the heating roller 61 of the fixing unit 6 in the image forming apparatus 1A. A roller 651 and a second pressure roller 652 are provided, and by changing the contact state between the heating roller 61 and the web sheet 64 by the web member pressing means 65, the toner adhered to the surface without damaging the surface of the heating roller 61 Can be reliably removed.

  Further, according to the present embodiment, as described above, by controlling to switch the pressure contact position by the first pressure contact roller 651 and the second pressure contact roller 652, the surface of the heating roller 61 is contacted via the pressure contact rollers. The web sheet 64 is always in a state in which a fresh surface (unused surface) is pressed against the heating roller 61 in the initial pressing state of the web sheet 64, and the recovery efficiency of the collected toner on the surface of the heating roller 61 is improved. As well as improving, proper cleaning performance can be maintained, and stable printing quality can be ensured.

  Furthermore, according to the present embodiment, the web member pressing means 65 is configured so that the eccentric cam 653b for pressing the first pressing roller 651 against the heating roller 61 and the second pressing roller 652 are pressed against the heating roller 61. Since the coil spring 653c is arranged so as to be interlocked by one drive motor 654, the apparatus configuration can be simplified and the structure can be made compact.

  In the present embodiment, the cleaning mechanism 63 is disposed corresponding to the heating roller 61 of the fixing unit 6. However, the present invention does not limit the roller member to be cleaned, and corresponds to the heating roller 62, for example. The cleaning mechanism according to the present invention may be configured.

  The preferred embodiments of the present invention have been described above. However, it goes without saying that the present invention is not limited to the above-described examples, and those skilled in the art will recognize various modifications within the scope of the claims. It is obvious that modifications can be conceived, and it is understood that they also belong to the technical scope of the present invention.

  For example, in the above-described embodiment, the present invention is applied to an image forming apparatus in which a monochrome developing device is installed. However, the present invention may be applied to a color image forming apparatus in which a plurality of developing devices are installed. Is possible. Furthermore, it is possible to develop the present invention in correspondence to an apparatus using a roller member that has a need to clean the roller member.

1 is an explanatory diagram illustrating an overall configuration of an image forming apparatus employing a cleaning mechanism according to an embodiment of the present invention. FIG. 2 is a partial detail view showing a configuration of an apparatus main body of the image forming apparatus. FIG. 2 is an explanatory diagram showing a schematic configuration of a cleaning mechanism provided in a fixing unit constituting the image forming apparatus. It is explanatory drawing which shows the state which pressed the web sheet to the heating roller with the 1st press roller in the said cleaning mechanism. It is explanatory drawing which shows the state which pressed the web sheet to the heating roller with the 2nd press-contact roller in the said cleaning mechanism. 5 is a flowchart for explaining the operation of a cleaning mechanism in the image forming apparatus. It is a flowchart explaining operation | movement of the said cleaning mechanism continuously from the flowchart shown in FIG. FIG. 10 is an explanatory diagram showing a schematic configuration of a cleaning mechanism provided in a fixing device mounted on a conventional image forming apparatus. 6 is a graph showing a temperature transition of toner collected by a cleaning mechanism of a fixing device mounted on a conventional image forming apparatus.

Explanation of symbols

1A image forming apparatus 2 developing unit (developing unit)
6 Fixing unit (fixing device)
14 Image forming section 61 Heating roller (fixing roller)
62 Pressure roller (fixing roller)
63 Cleaning mechanism 64 Web sheet (web member)
64a Delivery roller 64b Winding roller 65 Web member pressure contact means 66a, 66b Tension roller (web tension adjusting means)
612 Thermistor 614, 624 Heat source (heating means)
651 First pressure roller (pressure roller)
652 Second pressure roller (pressure roller)
653 Roller contact / separation structure (roller contact / separation means)
653a Holding bar (holding member)
653b Eccentric cam 653c Coil spring (elastic member)
654 Drive motor (drive means)

Claims (14)

A cleaning mechanism for cleaning the surface of the roller body by pressing the web member against the outer peripheral surface of the rotating roller member,
A cleaning mechanism comprising web member pressing means for changing a contact state between the roller member and the web member.   The web member pressing means drives a plurality of pressing rollers that press the web member against the roller member, a roller contacting / separating means that performs a contact / separation operation of the pressure roller with respect to the roller member, and driving the roller contacting / separating means The cleaning mechanism according to claim 1, further comprising: a driving unit that   The cleaning mechanism according to claim 2, wherein the web member pressing means drives the roller contacting / separating means by one driving means.   The web member pressing means is configured such that when any one of the plurality of pressing rollers is pressed against the roller member, the other pressing rollers are separated from the roller member. The cleaning mechanism according to claim 2 or 3, wherein:   The web member pressing means includes web tension adjusting means for making the tension of the web member constant even when any of the plurality of pressing rollers is in pressure contact with the roller member. Item 5. The cleaning mechanism according to any one of Items 2 to 4.   The roller contacting / separating means includes a holding member that simultaneously holds the plurality of pressure contacting rollers, an eccentric cam that acts on the holding member in conjunction with the driving means, and an action that acts on the holding member to move the plurality of pressure contacting rollers. The cleaning mechanism according to claim 2, further comprising: an elastic member that biases a part of the pressure contact rollers toward the roller member. The toner image is formed by passing a recording medium having an unfixed toner image formed in a nip portion provided with a pair of roller members provided with heat generating means on at least one roller member and pressing the roller members together. A fixing device comprising: a fixing roller for melting and fixing on the recording medium; and a cleaning mechanism for cleaning a roller surface by bringing a web member into contact with an outer peripheral surface of the fixing roller;
A fixing device using the cleaning mechanism according to claim 1 as the cleaning mechanism. An image forming unit including a photosensitive drum on which an electrostatic latent image is formed and a toner image is formed based on the electrostatic latent image; a developing unit including a developing roller that supplies toner to the photosensitive drum; A transfer unit that transfers a toner image formed on the photosensitive drum to a transported recording medium, and a pair of roller members including a heating unit in at least one roller member, and the roller member A fixing roller that melts and fixes the toner image on the recording medium by passing a recording medium on which an unfixed toner image is formed in a nip portion where the two are pressed against each other, and an outer peripheral surface of the rotating fixing roller. A fixing device having a cleaning mechanism for cleaning the surface of the roller by contacting the web member is provided, and a toner image formed on the surface of the photosensitive drum is transferred onto a recording medium by an electrophotographic method. In the image forming apparatus,
An image forming apparatus comprising: a web member pressing means for changing a contact state between the fixing roller and the web member as a configuration of the cleaning mechanism.   The image forming apparatus according to claim 8, comprising the cleaning mechanism according to claim 2 as the cleaning mechanism. The image forming apparatus includes a plurality of operation modes including a standby mode for controlling the operation of the fixing device, an energy saving mode, and a power saving mode.
When the pressure roller disposed on the downstream side in the rotation direction of the fixing roller among the plurality of pressure rollers constituting the web member pressure contacting means is pressed against the fixing roller, the fixing device is in a standby mode during warm-up. 10. The image forming apparatus according to claim 9, wherein the image forming apparatus is in a returning process for a printing process and when the surface temperature of the fixing roller reaches a set temperature and a transition is made to the printing process process.   When the pressure roller disposed on the upstream side in the rotation direction of the fixing roller among the plurality of pressure rollers is pressed against the fixing roller, the process proceeds to a print processing step after a predetermined time has elapsed after the fixing device has finished warming up. The image forming apparatus according to claim 9, wherein the image forming apparatus is configured to perform the operation.   During the predetermined time, after the cleaning process is performed by the web member in a state where the pressure roller disposed downstream in the rotation direction of the fixing roller is in pressure contact with the fixing roller, the temperature of the collected toner is changed to the melting of the toner. The image forming apparatus according to claim 11, wherein a time until the temperature is reached is set.   The predetermined time is a period of time until the web member is moved by a predetermined amount after the cleaning process is performed by the web member in a state where the pressure roller disposed downstream in the rotation direction of the fixing roller is in pressure contact with the fixing roller. The image forming apparatus according to claim 11, wherein time is set.   The image forming apparatus according to claim 13, wherein the movement amount of the web member is at least a length equal to or greater than an inter-axis distance between a plurality of pressure rollers that are alternately pressed against the fixing roller.

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