JP2009025519A - Fixing device, and image forming device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of positively removing toner deposited on the surface of a fixing roller, and capable of providing a fine print image even when using a glossy recording medium. <P>SOLUTION: This fixing device includes a web sheet switching means 135 provided with an oil impregnated web sheet 132a impregnated with an oil member having releasability, and an oil non-impregnated web sheet 133a impregnated with no oil member, as constitution of a cleaning unit 131, and for bringing either of the oil impregnated web sheet 132a or the oil non-impregnated web sheet 133a selectively into contact with a heating roller 123, in a fixing unit 27 provided with the cleaning unit 131 for bringing the web sheet into contact with the heating roller 123 for fixing a toner image onto the sheet formed with the toner image unfixed not yet, so as to clean the roller surface. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fixing device used in an electrophotographic image forming apparatus such as a copying machine, a facsimile machine, and a printer, and an image forming apparatus using the same, and more particularly, a fixing device having a cleaning mechanism for cleaning the surface of a fixing roller. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus capable of high-quality color printing by fixing a toner image on a recording medium by the apparatus and an image forming apparatus using the same.

Conventionally, in an image forming apparatus such as a facsimile or a printer using an electrophotographic system, image formation is performed as follows.
That is, in an image forming apparatus, a rotating electrophotographic photosensitive member (photosensitive drum) is uniformly charged with a predetermined polarity by a charger, and light exposure is performed on the photosensitive drum based on image information to perform image exposure. An electrostatic latent image is formed on the photosensitive drum. The developing device supplies a developer to the surface of the photosensitive drum to develop the electrostatic latent image to form a toner image on the surface of the photosensitive drum. The toner image is transferred to a transfer roller or a transfer corona. The image is transferred onto a predetermined transfer paper (recording medium) using a charger. The transfer paper onto which the toner image has been transferred is introduced into a fixing device, and the toner image is fixed on the transfer paper surface by heat or pressure. On the other hand, after the transfer is completed, the toner remaining on the surface of the photosensitive drum is cleaned. In some cases, static elimination is performed thereafter, and the image forming process ends.

  A fixing device used in the image forming apparatus as described above includes a fixing roller composed of a roller pair of a heating roller including a heat source and a pressure roller arranged to face the heating roller with a predetermined nip width, While the heating roller is heated to a predetermined fixing temperature, the transfer paper on which the toner image is formed is passed through the nip region of the pair of rollers, so that the toner image is pressed against the transfer paper surface by the heated fixing roller. Thus, the toner image is fixed on the transfer paper.

In a conventional fixing device, a cleaning mechanism using a web member impregnated with silicone oil or the like is widely used as a cleaning member for removing toner adhering to a fixing roller (for example, Patent Document 1, Patent). Reference 2). Further, in recent image forming apparatuses compatible with color high image quality, it is possible to cope with various types of transfer paper, and it is the actual situation that fixing conditions are changed according to each transfer paper.
Japanese Patent Laid-Open No. 4-275584 Japanese Patent Laid-Open No. 11-38815

However, in the fixing device as described above, when glossy transfer paper is used, there is a problem that unevenness (gloss unevenness) occurs in print image quality due to the influence of oil.
For example, the fixing device disclosed in Patent Document 1 improves the cleaning performance by bringing a cleaning member into contact with the fixing roller via a roller impregnated with oil, and cannot cope with the above problem.

  Further, the fixing device disclosed in Patent Document 2 includes a reversing unit that reverses the front surface and the back surface of the cleaning member in order to use the cleaning member efficiently. Since the above problem occurs because oil is impregnated in the same manner as in Patent Document 1, there is a problem that the print image quality is deteriorated when a glossy transfer paper is used.

  The present invention has been made in view of the above-described conventional problems, and reliably removes the toner adhering to the surface of the fixing roller to prevent toner contamination of the recording medium due to the residual toner and to provide glossy recording. It is an object of the present invention to provide a fixing device capable of realizing clean print image quality even when a medium is used, and an image forming apparatus using the same.

The configurations of the fixing device according to the present invention and the image forming apparatus using the same for solving the above-described problems are as follows.
The fixing device according to claim 1 includes a pair of roller members each having at least one roller member provided with a heat generating unit, and a recording in which an unfixed toner image is formed in a nip portion where the roller members are pressed against each other. 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 cleaning member into contact with the outer peripheral surface of the rotating fixing roller. In the apparatus, the configuration of the cleaning mechanism includes an oil impregnated cleaning member impregnated with an oil member having releasability as the cleaning member, and an oilless cleaning member not impregnated with the oil member, and Either one of the oil impregnated cleaning member or the oilless cleaning member is cleaned. Is characterized in further comprising a cleaning member switching means for selectively abuts the fixing roller member.

  According to a second aspect of the present invention, in addition to the configuration described in the first aspect, when the recording medium passing through the fixing device has gloss as the cleaning member switching unit, the oilless cleaning member is used as the fixing roller. It is characterized by comprising control means for controlling so as to abut.

  According to a third aspect of the present invention, in addition to the configuration described in the second aspect, the oilless cleaning member is provided as a function of the control unit when a glossy recording medium is selected during the operation of the fixing device. It has a function of contacting the fixing roller.

  According to a fourth aspect of the present invention, in addition to the configuration described in any one of the first to third aspects, the fixing member is configured by a tape-shaped web member that can be wound. It is what.

  According to a fifth aspect of the present invention, in addition to the configuration described in the fourth aspect, as a function of the cleaning mechanism, the cleaning mechanism periodically performs the cleaning when the number of recording media fixed by the fixing roller reaches a predetermined number. It has a function of winding a predetermined amount of members.

  A fixing device according to a sixth aspect is characterized in that, in addition to the configuration according to any one of the first to fifth aspects, the oil impregnated cleaning member is formed of felt or non-woven fabric. is there.

  According to a seventh aspect of the present invention, there is provided a fixing device according to any one of the first to third aspects, wherein the oil impregnated cleaning member is impregnated with an oil member having releasability. A roller member is used.

  An image forming apparatus according to an eighth aspect includes 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. A fixing device including a roller and a cleaning mechanism that cleans the surface of the roller by bringing a cleaning 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. An image forming apparatus that outputs a toner image transferred onto a recording medium and uses the fixing device according to any one of claims 1 to 7 as the fixing device. is there.

  The image forming apparatus described in claim 9 is characterized in that, in addition to the configuration described in claim 8, a gloss detecting means for detecting whether or not the recording medium has gloss is provided.

  According to the first 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 cleaning member into contact with the outer peripheral surface of the rotating fixing roller. In the fixing device, the cleaning mechanism includes an oil impregnated cleaning member impregnated with an oil member having releasability as the cleaning member, and an oil-free cleaning member not impregnated with the oil member, and , One of the oil impregnated cleaning member and the oilless cleaning member. By providing a cleaning member switching means for selectively contacting the fixing member with the fixing roller, even when a glossy recording medium is used, poor image quality such as uneven gloss can be prevented, and unfixed toner is fixed. It is difficult to adhere to the roller, it is possible to effectively avoid the flow of unfixed toner to the other roller member when the fixing roller is activated, and it is possible to effectively prevent toner contamination of the recording medium due to the remaining unfixed toner.

Moreover, in addition to the common effect obtained by the inventions according to claims 1 to 9, 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, as the cleaning member switching means, when the recording medium passing through the fixing device has gloss, By providing a control means for controlling the oilless cleaning member to contact the fixing roller, in the case of glossy transfer paper, it is not affected by oil having releasability. It is possible to prevent image quality defects such as.

  According to the invention described in claim 3, in addition to the effect obtained by the invention described in claim 2, when a recording medium having gloss is selected as the function of the control means when the fixing device is operated, By having the function of bringing the oil-free cleaning member into contact with the fixing roller, since the switching is completed before the recording medium reaches the fixing roller, the recording medium is not affected by the oil member and gloss unevenness, etc. Image quality defects can be reliably prevented.

  According to the invention described in claim 4, in addition to the effect obtained by the invention described in any one of claims 1 to 3, the cleaning member is formed by a tape-like web member that can be wound. By configuring, the used part can be taken up and the unused part can be fed out, so that the cleaning operation can be performed continuously.

  According to the fifth aspect of the present invention, in addition to the effect obtained by the fourth aspect of the invention, as a function of the cleaning mechanism, when the number of fixing processes of the recording medium by the fixing roller reaches a predetermined number. By providing a function of periodically winding a predetermined amount of the cleaning member, the fixing roller can always be kept clean.

  According to the invention described in claim 6, in addition to the effect obtained by the invention described in any one of claims 1 to 5, the oil impregnated cleaning member is formed of felt or non-woven fabric. The oil can be applied uniformly without damaging the fixing roller.

  According to the invention described in claim 7, in addition to the effect obtained by the invention described in any one of claims 1 to 3, an oil member having releasability is provided as the oil impregnated cleaning member. By using the impregnated oil impregnated roller member, it is not necessary to specially provide an oil pan or the like, and space can be saved with a simple configuration.

  According to an eighth aspect of the present invention, 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 supplied to the photosensitive drum. A pair including a developing unit including a developing roller and a transfer unit that transfers the toner image formed on the photosensitive drum to a conveyed recording medium, and at least one roller member includes a heating unit. A fixing roller that melts the toner image and fixes it on the recording medium by passing a recording medium on which an unfixed toner image is formed in a nip portion where the roller members are pressed against each other. A fixing device having a cleaning mechanism for cleaning the roller surface by bringing a cleaning member into contact with the outer peripheral surface of the rotating fixing roller, and formed on the surface of the photosensitive drum by electrophotography In an image forming apparatus that transfers a toner image onto a recording medium and outputs the image, many kinds of transfer media can be obtained by using the fixing device according to any one of claims 1 to 7 as the fixing device. Therefore, good image quality can be maintained.

  According to the ninth aspect of the invention, in addition to the effect obtained by the eighth aspect of the invention, the glossiness detecting means for detecting whether or not the recording medium has glossiness is provided, so that the user can obtain glossiness. Even if it is not possible to determine whether or not the recording medium is a recording medium, it is possible to automatically determine the recording medium. Thereby, it is possible to always maintain a good image quality.

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 fixing unit according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing the configuration of the fixing unit.

  As shown in FIGS. 1 and 2, the image forming apparatus 100 according to the present embodiment forms an image by an electrophotographic printing process, and includes a photosensitive drum 21 that is a rotating body, and a photosensitive drum 21. A charger 22 for charging the surface, an optical writing unit (exposure device) 23 for forming an electrostatic latent image on the photosensitive drum 21, and a photosensitive member by developing the electrostatic latent image with a developer. A developing device 24 for forming a toner image on the drum 21 and a transfer unit (transfer device) for transferring the toner image on the photosensitive drum 21 to a sheet (for example, a sheet-like recording medium such as recording paper or OHP) S 25) and a fixing roller 27A for fixing an unfixed toner image on the sheet S to the sheet S, and a cleaning unit for removing residual toner adhering to the surface of the fixing roller 27A. An image forming apparatus comprising a fixing device having a Tsu bets (cleaning mechanism) 131, a fixing device, in which with a characteristic fixing unit 27 according to the present invention.

First, the overall configuration of the image forming apparatus 100 according to the present embodiment will be described.
The image forming apparatus 100 acquires image data read from a document, or acquires image data received from the outside, and forms a monochrome image indicated by the image data on the sheet S. When roughly classified, the document feeding unit (ADF) 101, the image reading unit 102, the printing unit 103, the sheet conveying unit 104, and the paper feeding unit 105 are included.

  When at least one document is set on the document set tray 11, the document transport unit 101 pulls out the document one by one from the document set tray 11 and transports the document to the document reading window 102 a of the image reading unit 102. The document is guided and passed, and the document is discharged to the discharge tray 12.

  A CIS (Contact Image Sensor) 13 is disposed above the document reading window 102a. When the document passes through the document reading window 102a, the CIS 13 repeatedly reads the image on the back side of the document in the main scanning direction and outputs image data indicating the image on the back side of the document.

  Further, the image reading unit 102 exposes the document surface by the lamp of the first scanning unit 15 when the document passes through the document reading window 102a, and the mirror of the first and second scanning units 15 and 16 from the document surface. The reflected light is guided to the imaging lens 17, and an image of the document surface is formed on a CCD (Charge Coupled Device) 18 by the imaging lens 17. The CCD 18 repeatedly reads an image on the document surface in the main scanning direction and outputs image data indicating the image on the document surface.

  Further, when the document is placed on the platen glass on the upper surface of the image reading unit 102, the first and second scanning units 15 and 16 are moved while maintaining a predetermined speed relationship with each other. The document surface on the platen glass is exposed, the reflected light from the document surface is guided to the imaging lens 17 by the first and second scanning units 15 and 16, and the image on the document surface is connected to the CCD 18 by the imaging lens 17. Image.

The image data output from the CIS 13 or the CCD 18 is subjected to various types of image processing by an image processing device 248 (see FIG. 4) and then output to the printing unit 103.
The printing unit 103 records the document image indicated by the image data on the sheet S. The photosensitive drum 21, the charger 22, the optical writing unit 23, the developing unit 24, the transfer unit 25, and the cleaning unit described above. 26, a fixing unit 27, and the like.

  The photosensitive drum 21 has a cylindrical shape and is disposed below the optical writing unit 23. The surface of the photosensitive drum 21 is moved in a predetermined direction (in the direction of arrow A in the figure) by a driving unit and a control unit (not shown). 26 is cleaned, and the cleaned surface is uniformly charged by the charger 22. The charger 22 may be of a charger type or of a roller type or a brush type that contacts the photosensitive drum 21.

  The optical writing unit 23 is a laser scanning unit (LSU) including two laser irradiation units 28a and 28b and two mirror groups 29a and 29b. In the optical writing unit 23, image data is input, laser light corresponding to the image data is emitted from the laser irradiation units 28a and 28b, and the laser light is exposed through the mirror groups 29a and 29b. The surface of the photosensitive drum 21 is irradiated by irradiating the photosensitive drum 21 to expose the surface, and an electrostatic latent image is formed on the surface of the photosensitive drum 21.

  The optical writing unit 23 employs a two-beam system including two laser irradiation units 28a and 28b in order to cope with high-speed printing, thereby reducing the burden associated with increasing the irradiation timing. As the optical writing unit 23, an EL writing head or an LED writing head in which light emitting elements are arranged in an array can be used instead of the laser scanning unit.

  The developing device 24 visualizes the electrostatic latent image formed on the photosensitive drum 21 with toner, and supplies the toner to the surface of the photosensitive drum 21 to develop the electrostatic latent image. An image is formed on the surface of the photosensitive drum 21. The transfer unit 25 transfers the toner image on the surface of the photosensitive drum 21 onto the sheet S conveyed by the sheet conveying unit 104. The fixing unit 27 heats and pressurizes the sheet S to fix the toner image on the sheet S. Thereafter, the sheet S is further conveyed to the sheet discharge tray 47 by the sheet conveying unit 104 and discharged. The cleaning unit 26 removes and collects toner remaining on the surface of the photosensitive drum 21 after development and transfer.

Here, the transfer unit 25 includes a transfer belt 31, a drive roller 32, a driven roller 33, an elastic conductive roller 34, and the like, and the transfer belt 31 is stretched between the rollers 32 to 34 and other rollers. Rotating. The transfer belt 31 has a predetermined resistance value (for example, 1 × 10 ⁹ to 1 × 10 ¹³ Ω / cm), and conveys the sheet S placed on the surface thereof. The elastic conductive roller 34 is pressed against the surface of the photosensitive drum 21 via the transfer belt 31, and presses the sheet S on the transfer belt 31 against the surface of the photosensitive drum 21.

  An electric field having a polarity opposite to the charge of the toner image on the surface of the photosensitive drum 21 is applied to the elastic conductive roller 34, and the toner image on the surface of the photosensitive drum 21 is transferred onto the transfer belt 31 by the electric field having the opposite polarity. The sheet S is transferred. For example, when the toner image has a charge of (−) polarity, the polarity of the electric field applied to the elastic conductive roller 34 is set to (+) polarity.

  As shown in FIG. 2, the fixing unit 27 includes a pair of fixing rollers (here, a heating roller 123 and a pressure roller 124) 27A that are rotating bodies. A heating roller heater 128 is provided in the heating roller 123 as a heat source for setting the surface of the heating roller 123 to a predetermined temperature (heating temperature: approximately 160 to 200 ° C.). A pressure roller heater 129 is provided as a heat source for assisting the heating by 123.

  Further, pressure means (not shown) are arranged at both ends of the pressure roller 124 so that the pressure roller 124 is pressed against the heating roller 123 with a predetermined pressure. When the sheet S is conveyed to a pressure contact portion (referred to as a fixing nip portion) 127 between the heating roller 123 and the pressure roller 124, the sheet S is conveyed while being conveyed by the heating roller 123 and the pressure roller 124. The upper unfixed toner image is heated and melted and pressed to fix the toner image on the sheet S.

  The sheet conveyance unit 104 includes a plurality of pairs of conveyance rollers 41 for conveying the sheet S, a pair of registration rollers 42, a conveyance path 43, a reverse conveyance path 44, a plurality of branching claws 45, a pair of discharge rollers 46, and the like. I have.

  In the conveyance path 43, the sheet S is received from the sheet feeding unit 105 and is conveyed until the leading edge of the sheet S reaches the registration roller 42. At this time, since the registration roller 42 is temporarily stopped, the leading edge of the sheet S reaches the registration roller 42 and comes into contact therewith, and the sheet S bends. The leading edge of the sheet S is aligned parallel to the registration roller 42 by the elastic force of the bent sheet S. Thereafter, the rotation of the registration roller 42 is started, the sheet S is conveyed to the transfer unit 25 of the printing unit 103 by the registration roller 42, and the sheet S is further conveyed to the sheet discharge tray 47 by the sheet discharge roller 46.

  The registration roller 42 is stopped and rotated by switching the clutch between the registration roller 42 and the drive shaft between an on state and an off state, and switching a motor that is a driving source of the registration roller 42 on and off.

Also, when recording an image on the back side of the sheet S, the plurality of branch claws 45 are rotated to switch the branch path between the transport path 43 and the reverse transport path 44, and the reverse side of the sheet S is reversed by the reverse transport path 44. After that, the sheet S is returned to the registration roller 42 in the conveyance path 43 through the reverse conveyance path 44. Thereby, an image is also recorded on the back surface of the sheet S.
In the conveyance path 43 and the reverse conveyance path 44, sheet detection sensors for detecting the position of the sheet S and the like are arranged in various places, and the conveyance roller and the registration roller are driven and controlled based on the position of the sheet S detected by each sensor. Thus, the sheet S is conveyed and positioned.

The paper feed unit 105 includes a plurality of paper feed trays 51. Each paper feed tray 51 is a tray for storing sheets S, and is provided below the image forming apparatus 100. Each paper feed tray 51 is provided with a pickup roller or the like for pulling out the sheets S one by one, and sends the pulled sheets S to the transport path 43 of the sheet transport unit 104.
Since the image forming apparatus 100 according to the present embodiment performs high-speed printing, the interval between continuously conveyed sheets is narrow (for example, narrow at an interval of about 50 mm). In addition, since the image forming apparatus 100 of the present embodiment is intended for high-speed printing, each of the paper feed trays 51 has a capacity capable of storing 500 to 1500 sheets of standard size sheets.

  Further, on the side surface of the image forming apparatus 100, a large-capacity sheet feeding cassette (LCC) 52 capable of storing a large amount of a plurality of types of sheets S and a manual feed tray 53 for supplying mainly irregular-size sheets S are provided. ing.

  The paper discharge tray 47 is disposed on the side surface opposite to the manual feed tray 53. Instead of the paper discharge tray 47, a post-processing device for paper discharge sheets (stapling, punching, etc.) and a plurality of stages of paper discharge trays can be arranged as options.

  Next, a characteristic configuration of the fixing unit 27 according to the present embodiment will be described in detail with reference to the drawings.

  As shown in FIG. 2, the fixing unit 27 according to the present embodiment includes a pair of a heating roller 123 and a pressure roller 124 as a fixing roller 27A. The heating roller 123 and the pressure roller 124 are arranged to face each other and are configured to rotate in the direction of arrow B and the direction of arrow C in the drawing, respectively. A fixing nip 127 is formed at a pressure contact portion between the heating roller 123 and the pressure roller 124.

  The heating roller 123 has a configuration in which an elastic layer 123b is provided on the circumferential surface of a cylindrical metal cored bar 123a, and includes a heating roller heater 128 made of a halogen heater lamp in the inner space of the cored bar. .

  Specifically, the core metal 123a is formed of a metal or an alloy material such as iron, aluminum, copper, nickel, and stainless steel. The elastic layer 123b is made of, for example, silicon rubber, polybutadiene rubber, chloroprene rubber, isoprene rubber, polyurethane rubber, or copolymer rubber such as EPDM. The elastic layer 123b is preferably formed of an elastic material having a high heat capacity in order to minimize the change in surface temperature of the heating roller 123 as much as possible. In addition, a fluorine-containing resin layer may be coated on the elastic layer 123b in order to prevent toner adhesion and fusion to the surface of the elastic layer 123b.

  Further, the heating roller 123 detects the surface temperature of the outer periphery by the temperature detector 130, and the surface temperature is in the range of 160 to 200 ° C. (generally, the fixing temperature is 130 to 180 ° C.). Thus, the operation (energization) of the heater 128 for the heating roller is controlled.

  Around the heating roller 123, there are a temperature detector 130 composed of a non-contact type thermistor in the vicinity, and a web sheet type cleaning unit (cleaning mechanism) 131 for wiping off residual toner adhering to the outer peripheral surface of the heating roller 123. Is provided.

On the other hand, the pressure roller 124 has a cylindrical shape, and is provided with a pressure roller heater 129 made of a halogen heater lamp in its internal space. The pressure roller 124 is made of, for example, a metal or alloy material such as iron, aluminum, copper, nickel, and stainless steel.
The configuration of the pressure roller 124 may be a core metal and an elastic layer, similar to the heating roller 123 described above.

  Next, the characteristic cleaning unit 131 according to the present embodiment will be described in detail with reference to the drawings. FIG. 3 is an explanatory view showing the configuration of the cleaning member switching means constituting the cleaning unit according to the present embodiment, and FIG. 4 is an explanatory view showing a state where the web sheet is switched by the cleaning member switching means.

  As shown in FIG. 2, the cleaning unit 131 mainly includes an oil-impregnated cleaning web unit 132 including an oil-impregnated web sheet (cleaning member) 132a containing oil, and an oil-free web sheet (cleaning member) that does not contain oil. ) The oilless cleaning web unit 133 provided with 133a and the web sheet (cleaning member) used for either the oil impregnated cleaning web unit 132 or the oilless cleaning web unit 133 are selectively applied to the heating roller 123. Web sheet switching means (cleaning member switching means) 135 to be contacted.

As shown in FIG. 2, the oil-impregnated cleaning web unit 132 is mainly composed of an oil-impregnated web sheet roll 132a1 obtained by winding a long oil-impregnated web sheet 132a into a cylindrical shape, and the oil-impregnated web sheet roll 132a1 The feed roller 132b that feeds out the web sheet 132a, a pressure roller 132c that presses the oil-impregnated web sheet 132a against the outer peripheral surface of the heating roller 123, and a winding roller 132d that winds up the used oil-impregnated web sheet 132a. ing.
The oil impregnated cleaning web unit 132 is a regular replacement part that is replaced according to a predetermined replacement cycle.

On the other hand, the oil-free cleaning web unit 133 mainly feeds the oil-free web sheet roll 133a1 obtained by winding a long oil-free web sheet 133a into a cylindrical shape, and the oil-free web sheet roll 133a1 sends out the oil-free web sheet 133a. The feeding roller 133b, a pressure contact roller 133c that presses the oilless web sheet 133a against the outer peripheral surface of the heating roller 123, and a winding roller 133d that winds the used oilless web sheet 133a.
The oil-free cleaning web unit 133 is also a regular replacement part that is replaced according to a predetermined replacement cycle, like the oil-impregnated cleaning web unit 132.

  The oil-impregnated web sheet 132a and the oil-free web sheet 133a are made of felt or non-woven fabric having a thickness of 50 to 150 μm, and each of the contaminated dirty toner adhering to the heating roller 123 in contact with the outer peripheral surface of the heating roller 123 It is made to collect | recover in the inside of a web sheet by making it infiltrate into the fiber texture of a web sheet.

  The oil-impregnated web sheet 132a and the oil-free web sheet 133a are fed out rollers 132b and 133b and a take-up roller 132d, respectively, when the number of print processed sheets (for example, the number of sheets passing through the fixing unit 27) reaches a certain number. , 133d is controlled so as to move the web sheet by a predetermined amount by selectively driving according to the web sheet to be used, and to clean the surface of the heating roller 123 with the unused web sheet. The movement direction of the oil impregnated web sheet 132a and the oilless web sheet 133a is opposite to the direction of rotation of the heating roller 123 in contact (the direction of arrow B in FIG. 2) (the direction of arrow D in FIG. 2). It is supposed to move.

  In the present embodiment, the heating roller 123 can always be kept clean by winding the oil-impregnated web sheet 132a and the oil-free web sheet 133a every time a predetermined number of sheets (recording paper) S pass. . Specifically, a sufficient effect can be achieved by moving the oil-impregnated web sheet 132a and the oil-free web sheet 133a by about 2 mm for every 100 sheets processed.

  As shown in FIG. 3, the web sheet switching means 135 mainly includes a switching arm 136 that is rotatably supported by pressure rollers 132c and 133c at both ends, and a solenoid 137 that operates the switching arm. A tension coil spring 139 for returning the arm 136 to the initial operation state is constituted.

  The switching arm 136 is rotatably supported at one end 136a by a pressure contact roller 132c for pressure contact with the oil-impregnated web sheet 132a, and is rotatably supported at the other end 136b by a pressure contact roller 133c for pressure contact with the oilless web sheet 133a. In addition, a substantially central portion 136c in the arm longitudinal direction between the pressure roller 132c and the pressure roller 133c is pivotally supported on the main body side of the fixing unit 27 (not shown).

  The solenoid 137 is a drive unit that constitutes a part of a control unit for controlling the operation of the switching arm 136, and selectively operates the pressure rollers 132c and 133c provided on the switching arm 136 by operating the switching arm 136. It is brought into pressure contact with the heating roller 123. A plunger 137 a is configured to be able to appear and retract at the end of the solenoid 137. A switching arm operation member 138 connected to one end side of the switching arm 136 is connected to the end of the plunger 137a.

  In this embodiment, the switching arm connecting member 138 is connected to the end of the switching arm 136 on the pressure contact roller 133c side, and the pressure contact roller 133c is moved upward in FIG. 3 with the plunger 137a protruding from the main body of the solenoid 137. It is arranged to push up.

  That is, in the non-operating state, the solenoid 137 separates the pressure roller 133c from the heating roller 123 with the plunger 137a protruding upward as shown in FIG. On the other hand, in the operating state, as shown in FIG. 4, the plunger 137 a is pulled toward the main body, and the pressure roller 133 c is brought into contact with the heating roller 123.

  One end of the tension coil spring 139 is engaged with the end of the switching arm 136 on the pressure roller 133c side, and the other end is locked to the main body side of the fixing unit 27 (not shown). It arrange | positions so that it may urge in the direction pulled up upwards. In other words, the tension coil spring 139 is disposed so as to urge the pressing roller 132c provided at the other end of the switching arm 136 in the normal state in a direction in which the tension roller spring 139 is lowered and brought into contact with the heating roller 123.

  Next, the electrical configuration of the fixing unit 27 of the present embodiment will be described with reference to the drawings. FIG. 5 is a block diagram showing an electrical configuration relating to the control of the fixing function by the fixing unit of the present embodiment.

As shown in FIG. 5, the control unit 240 of the fixing unit 27 includes a CPU (Central Processing Unit) 241 and a storage unit 242. The storage unit 242 stores various control programs and necessary functions, and includes a ROM (Read Only Memory) and a RAM (Random Access Memory).
The control unit 240 reads various control programs from the storage unit 242 by the CPU 241, and controls the fixing function in the fixing unit 27 by executing the read control programs.

  The control unit 240 may be configured to control not only the fixing unit 27 illustrated in FIG. 2 but also the overall operation of the image forming apparatus 100 illustrated in FIG. In that case, the control unit 240 has a function of further performing process control related to printing of the image forming apparatus 100. When the control unit 240 only controls the fixing unit 27 shown in FIG. 2, the control unit 240 communicates with a control unit (not shown) that controls the overall operation of the image forming apparatus 100 to perform heating unit (fixing roller 27A). ) Drive control may be performed.

In the present embodiment, the control unit 240 controls the overall operation of the image forming apparatus 100.
In the present embodiment, as shown in FIG. 5, the control unit 240 includes a heating roller heater 128 that is a heat source of the heating roller 123, a pressure roller heater 129 that heats the pressure roller 124, a temperature detector 130, and a motor 243. These are connected to the take-up roller driving units 245 and 246, the solenoid 137, and the image processing device 248 to control the operation of each unit.

  The heating roller heater 128 and the pressure roller heater 129 are connected to the control unit 240 via respective drivers 128a and 129a. The controller 240 controls on / off of energization to each heater. In addition, on / off control of energization to each heater 128, 129 can be performed independently.

  The temperature detector 130 detects the surface temperature of the heating roller 123. The controller 240 adjusts the surface temperature of the heating roller 123 and the pressure roller 124 by controlling on / off of the energization of the heater 128 for the heating roller and the heater 129 for the pressure roller based on the detection signal from the temperature detector 130. Is supposed to do.

  The motor 243 is a drive motor that rotationally drives the heating roller 123 and the pressure roller 124, and is connected to the control unit 240 via the driver 243a and controlled in operation.

  Winding roller driving units 245 and 246 are driving motors that respectively drive a winding roller 132d that winds up the oil-impregnated web sheet 132a and a winding roller 133d that winds up the oilless web sheet 133a. The operation is controlled by being connected to the control unit 240 via the H.246a.

  The solenoid 137 is driving means for operating the switching arm 136 to selectively press the pressure rollers 132c and 133c provided on the switching arm 136 against the heating roller 123, and is connected to the controller 240 via the driver 137b. Operation is controlled.

Next, the effect | action by the cleaning unit 131 in this embodiment is demonstrated with reference to drawings.
In the cleaning unit 131 according to the present embodiment, as shown in FIG. 3, the oil-impregnated web sheet 132 a is controlled to contact the heating roller 123 in a normal state.

  When a glossy sheet S is selected as a recording sheet used in the image forming apparatus 100 according to an instruction from the operation panel or an external apparatus, the web sheet switching unit 135 causes the oil-free web sheet 133a to be displayed as shown in FIG. Selected.

  Specifically, as shown in FIG. 3, the switching arm 136 is, as shown in FIG. 3, the end on the pressure roller 133 c side is pulled upward by the tension coil spring 139 (upward in the drawing). By pressing against the heating roller 123 side, the oil impregnated web sheet 132a is pressed against the heating roller 123 by the pressure roller 132c.

  When a signal indicating that a glossy sheet has been selected by the control unit 240 is input to the control unit 240, the solenoid 137 is driven based on the signal and the plunger 137a is pulled into the main body.

  By the pulling-in operation of the plunger 137a, the spring force of the tension coil spring 139 is resisted and the pressure roller 133c side of the switching arm 136 is pulled downward, and the oilless web sheet 133a is pressed against the heating roller 123 by the pressure roller 133c. Simultaneously with this operation, the pressure roller 132c side moves upward, so that the oil-impregnated web sheet 132a is separated from the heating roller 123. In this way, the web sheet to be used is switched.

  Next, when a non-glossy sheet is selected, that is, when returning to the normal state, the solenoid 137 is driven and the plunger is driven based on a signal indicating that the non-glossy sheet is selected by an instruction from the operation panel or an external device. 137a protrudes outward from the main body side.

  Since the pulling force of the switching arm 136 is released by the protrusion of the plunger 137a, the pressure roller 133c side of the switching arm 136 is pulled upward by the spring force of the tension coil spring 139. As a result, the oil-free web sheet 133 a is separated from the heating roller 123. Simultaneously with this operation, the pressure roller 132c side is pushed downward, whereby the oil-impregnated web sheet 132a is pressed against the heating roller 123. In this way, the web sheet to be used is switched.

  As described above, according to the cleaning unit 131 in the present embodiment, either the oil-impregnated web sheet 132a or the oil-free web sheet 133a is automatically selected according to the presence or absence of gloss of the sheet to be used. The web sheet can be brought into contact with the heating roller 123.

  Since configured as described above, according to the present embodiment, in the cleaning unit 131 for cleaning the surface of the heating roller 123, an oil-impregnated web sheet 132a impregnated with an oil member having releasability as a cleaning member; And an oil-free web sheet 133a that is not impregnated with an oil member, and either one of the oil-impregnated web sheet 132a and the oil-free web sheet 133a is selectively brought into contact with the heating roller 123. By providing the sheet switching means 135, image quality defects such as uneven gloss can be prevented even when a glossy sheet is used. Furthermore, since the unfixed toner can hardly adhere to the heating roller 123, the unfixed toner can be effectively prevented from flowing out to the other roller member when the fixing unit 27 is started, and the toner contamination of the recording medium due to the remaining unfixed toner can be avoided. Can be effectively prevented.

  Further, according to the present embodiment, since the web sheet can be switched by the web sheet switching unit 135 according to the recording medium to be used, the web sheet can be easily switched without bothering the operator. .

  Furthermore, according to the present embodiment, when the glossy sheet S is selected as the sheet S to be used by the control unit 240, the web sheet to be used is switched, so that the sheet S reaches the fixing unit 27. The switching can be completed before the operation is performed, whereby the oil remaining on the surface of the heating roller 123 can be removed, so that image quality defects such as uneven gloss due to the influence of oil can be reliably prevented.

  In addition, according to the present embodiment, since the oil impregnated web sheet 132a and the oilless web sheet 133a are configured as a cylindrical body wound up in a cylindrical shape, it is easy to continuously move the web sheet, and the heating roller is always used. The surface of 123 can be kept clean.

  Further, according to the present embodiment, the oil-impregnated web sheet 132a and the oil-free web sheet 133a are cleaned at an unused portion by winding a predetermined amount of the portion used for cleaning every time a predetermined number of printing processes are performed. Thus, the heating roller 123 can always be kept clean throughout its life, and stable printing quality can be ensured.

  Further, according to the present embodiment, since the material of the oil-impregnated web sheet 132a is made of felt or non-woven fabric, the oil-impregnated web sheet 132a and the heating roller 123 are formed even if the toner to be removed is a small particle size toner. Cleaning can be performed without slipping through the nip region. As a result, the heating roller 123 can be kept normal, and the oil can be uniformly applied to the surface of the heating roller 123 without being damaged by the heat roller 123.

  In addition, according to the present embodiment, by using the oil impregnated web sheet 132a as a cleaning member impregnated with releasable oil, the oil naturally penetrates into the oil impregnated web sheet 132a itself, so that oil dripping is prevented. Since it does not occur, it is not necessary to provide a special oil pan or the like, and space can be saved.

  In the present embodiment, when the sheet S as the recording medium to be used is selected, the sheet S is selected by the operation of the operation panel by the user or the instruction from the external device. However, the present invention selects the recording medium. For example, the image forming apparatus may include a detecting unit that automatically detects whether or not the recording medium is glossy. Specifically, as the detection means, for example, a reflection type density sensor is disposed at a paper inlet for supplying a recording medium of the image forming apparatus, and the recording medium has gloss by reading the reflection intensity. It can be determined whether or not there is.

  With such a configuration, even when the user cannot determine that the paper is glossy, the recording medium can be automatically determined, so that high-quality image quality can be ensured.

  In this embodiment, the cleaning unit 131 is disposed corresponding to the heating roller 123 of the fixing unit 27. However, the present invention does not limit the roller member to be cleaned, and corresponds to, for example, the pressure roller 124. Thus, a fixing unit (fixing device) 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 these are naturally understood to fall within 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 fixing unit according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a configuration of the fixing unit. FIG. 4 is an explanatory diagram illustrating a configuration of a cleaning member switching unit of a cleaning unit that constitutes the fixing unit. It is explanatory drawing which shows the state which switched the web sheet by the said cleaning member switching means. FIG. 2 is a block diagram showing an electrical configuration relating to control of a fixing function by the fixing unit.

Explanation of symbols

27 fixing unit 27A fixing roller 100 image forming apparatus 123 heating roller 124 pressure roller 127 fixing nip portion 128 heating roller heater 129 pressure roller heater 130 temperature detector 131 cleaning unit 132 oil impregnated cleaning web unit 132a oil impregnated web sheet 132a1 Oil impregnated web sheet rolls 132b, 133b Feed rollers 132c, 133c Pressure rollers 132d, 133d Winding roller 133 No oil cleaning web unit 133a No oil web sheet 133a1 Web sheet roll 135 Web sheet switching means (cleaning member switching means )
136 Switching arm 137 Solenoid (control means)
138 Arm operation member 139 Tension coil spring 240 Control unit (control means)

Claims (9)

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. In a fixing device comprising a fixing roller that is melted and fixed on the recording medium, and a cleaning mechanism that cleans the roller surface by bringing a cleaning member into contact with the outer peripheral surface of the rotating fixing roller.
The cleaning mechanism includes, as the cleaning member, an oil-impregnated cleaning member impregnated with an oil member having releasability, and an oil-free cleaning member not impregnated with the oil member, and the oil-impregnated cleaning member Alternatively, the fixing device includes a cleaning member switching unit that selectively contacts one of the cleaning members without oil with the fixing roller.   2. The control unit according to claim 1, wherein the cleaning member switching unit includes a control unit that controls the oilless cleaning member to contact the fixing roller when the recording medium passing through the fixing device has gloss. The fixing device described.   The fixing device according to claim 2, wherein the control unit causes the oilless cleaning member to abut against the fixing roller when a glossy recording medium is selected when the fixing device is operated.   The fixing device according to claim 1, wherein the cleaning member is formed of a tape-shaped web member that can be wound.   5. The fixing according to claim 4, wherein the cleaning mechanism has a function of winding a predetermined amount of the cleaning member periodically when the number of fixing processes of the recording medium by the fixing roller reaches a predetermined number. apparatus.   The fixing device according to claim 1, wherein the oil-impregnated cleaning member is formed of felt or non-woven fabric.   The fixing device according to claim 1, wherein the oil impregnated cleaning member uses an oil impregnated roller member impregnated with an oil member having releasability. 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 a roller surface by contacting a cleaning member is provided, and a toner image formed on the surface of the photosensitive drum is transferred onto a recording medium by electrophotography. In Te image forming apparatus for outputting,
An image forming apparatus using the fixing device according to claim 1 as the fixing device.   The image forming apparatus according to claim 8, further comprising a gloss detecting unit configured to detect whether the recording medium has gloss.

Images