JPWO2016203826A1 - Fixing apparatus and image forming apparatus - Google Patents

Abstract

A fixing member such as a fixing belt (80) and a heating means such as a halogen heater (82a, 82b) for heating the fixing member are provided to heat unfixed toner on a recording material such as a conveyed recording sheet. In the fixing device (150) for fixing the unfixed toner on the recording material, a sheet-like hydrofluoric acid absorbent (95) is pasted on the upper surface of the casing (150a) containing the fixing member and the heating means. .

Description

  The present invention relates to a fixing device and an image forming apparatus.

  2. Description of the Related Art Conventionally, as a fixing device with a short warm-up time and low power consumption, an image forming apparatus including a belt fixing device that forms a fixing nip by pressing a fixing pad against a pressure roller while sandwiching a fixing belt is known. ing.

  Patent Document 1 describes a belt fixing device that contains, as a lubricant, fluorine oil having higher heat stability than silicone oil in the fixing pad in order to reduce wear between the fixing pad and the fixing belt.

  In rare cases, malfunction of the control unit may cause the energization control to the heating means of the fixing device to become uncontrollable, and so-called thermal runaway may occur where abnormal heating occurs. When such a thermal runaway occurs, the image forming apparatus is overheated by forcibly shutting off the energization of the heating means by a safety device such as a thermal fuse or a thermo switch incorporated in the energization circuit of the heating means. To prevent becoming.

  However, in the above-described belt fixing device configured to raise the temperature to a specified temperature in a short time, the fixing belt and the fixing pad are not yet supplied until the energization of the heating means is forcibly cut off by the safety device. However, the temperature instantaneously becomes 400 ° C. or higher. When a fluorine compound is used in the fixing device such as fluorine oil as a lubricant as in the belt fixing device described in Patent Document 1, decomposition of the fluorine compound starts at a high temperature of 400 ° C. or higher. Fluorine gas is generated from the fluorine compound. The generated fluorine gas reacts with moisture in the atmosphere to generate toxic hydrofluoric acid, which may leak out of the machine.

  In order to solve the above-described problems, the present invention includes a fixing member and a heating unit that heats the fixing member. The unfixed toner is heated by heating the unfixed toner on the recording material being conveyed. A fixing device for fixing on the recording material, which has a hydrofluoric acid absorbent.

  According to the present invention, it is possible to suppress the leakage of hydrofluoric acid to the outside of the apparatus.

FIG. 1 is a schematic configuration diagram illustrating a configuration example of the entire image forming apparatus according to the embodiment. FIG. 2 is a schematic configuration diagram illustrating a configuration example of the fixing device. FIG. 3 is a schematic configuration diagram illustrating another example of the fixing device. 4 is a perspective view showing a nip forming member main body of the fixing device shown in FIG. FIG. 5 is a diagram showing a first halogen heater, a second halogen heater, and an end heater. FIG. 6 is a perspective view showing a nip forming member body showing an example in which a covering member is provided on the nip forming member body and the end heater. FIG. 7 is a diagram showing electrical connection between the first and second halogen heaters and the end heater. FIG. 8 is a diagram showing an example of the arrangement of the hydrofluoric acid absorbent. FIG. 9 is an exploded perspective view showing another example of the arrangement of the hydrofluoric acid absorbent. FIG. 10 is a diagram showing still another example of the arrangement of the hydrofluoric acid absorbent.

  Hereinafter, an embodiment of an image forming apparatus according to the present invention will be described. In each drawing for explaining the present embodiment, components such as members and components having the same function or shape, once described by attaching the same reference numerals as much as possible, The description is omitted.

First, a basic configuration of the image forming apparatus according to the embodiment will be described.
FIG. 1 is a schematic configuration diagram illustrating a configuration example of the entire image forming apparatus 100 according to the embodiment.
An image forming apparatus 100 shown in FIG. 1 is a tandem type color laser printer. From an image forming section (four image forming sections in the illustrated example) that forms a plurality of color images at the center of the apparatus main body. An image station is provided. The plurality of image forming units are juxtaposed along the extending direction of an intermediate transfer belt (hereinafter referred to as “transfer belt”) 11 as an endless belt-like intermediate transfer member. The configuration is the same except that developers of different colors such as yellow (Y), magenta (M), cyan (C), and black (Bk) corresponding to the color separation components of the color image are used. .

  In the image forming apparatus, a plurality of drum-shaped photoconductors 20Y, 20C, 20M, and 20Bk are arranged side by side as latent image carriers corresponding to yellow, cyan, magenta, and black, respectively. The Y, C, M, and Bk toner images formed on the surfaces of the photoconductors 20Y, 20C, 20M, and 20Bk move endlessly in the direction of the arrow A1 while facing the photoconductors 20Y, 20C, 20M, and 20Bk. The image is primarily transferred while being superimposed on the belt 11. Thereafter, the Y, C, M, and Bk toner images superimposed and transferred to the transfer belt 11 are collectively transferred to the recording sheet P by a secondary transfer process for the recording sheet P.

  Around the photoconductors 20Y, 20C, 20M, and 20Bk, various devices for performing an image forming process as the photoconductor rotates are arranged. The photoconductor 20Bk that performs black image formation will be described as an example. The following various devices are disposed around the photoconductor 20Bk. That is, the charging device 30Bk, the developing device 40Bk, the primary transfer roller 12Bk as a primary transfer unit, and the cleaning device 50Bk. For writing of the electrostatic latent image performed on the photosensitive member 20Bk after charging, the optical writing device 8 is used as an exposure unit that exposes the surface of the photosensitive member 20Bk.

  The optical writing device 8 includes a semiconductor laser as a light source, a coupling lens, an fθ lens, a toroidal lens, a folding mirror, a rotating polygon mirror (polygon mirror) as an optical deflecting unit, and the like. The optical writing device 8 irradiates the surface of each of the photoconductors 20Y, 20C, 20M, and 20Bk with writing light (laser light) Lb based on the image data, and electrostatic latent images are applied to the photoconductors 20Y, 20C, 20M, and 20Bk. It is configured to form an image.

  In the superimposing transfer to the transfer belt 11, the Y, C, M, and Bk toner images formed on the photoconductors 20Y, 20C, 20M, and 20Bk are the same on the transfer belt 11 in the process in which the transfer belt 11 moves in the A1 direction in the figure. It is executed so that the image is transferred to the position. Specifically, a primary transfer bias is applied to each of a plurality of primary transfer rollers 12Y, 12C, 12M, and 12Bk disposed facing the photoconductors 20Y, 20C, 20M, and 20Bk with the transfer belt 11 interposed therebetween. In this state, the primary transfer rollers 12Y, 12C, 12M, and 12Bk cause the Y, C, M, and Bk toner images formed on the photoreceptors 20Y, 20C, 20M, and 20Bk to be downstream from the upstream side of the transfer belt 11 in the A1 direction. The images are superimposed and transferred with the timing shifted toward the side.

  The plurality of primary transfer rollers 12Y, 12C, 12M, and 12Bk sandwich the transfer belt 11 with the corresponding photoreceptors 20Y, 20C, 20M, and 20Bk to form a primary transfer nip. The primary transfer rollers 12Y, 12C, 12M, and 12Bk are connected to a power source, and a primary transfer bias including a predetermined DC voltage (DC) and / or AC voltage (AC) is supplied to the primary transfer rollers 12Y, 12C, and 12B. Applied to 12M and 12Bk.

  The photoconductors 20Y, 20C, 20M, and 20Bk are arranged in this order from the upstream side in the A1 direction in the drawing. The photoreceptors 20Y, 20C, 20M, and 20Bk are provided in the plurality of image forming units that respectively form yellow, cyan, magenta, and black images.

  The image forming apparatus includes a transfer belt unit (transfer device) 10 disposed above the photoreceptors 20Y, 20C, 20M, and 20Bk, a secondary transfer roller 5 as a secondary transfer unit, a transfer belt cleaning device 13, and a plurality of transfer belt units. An optical writing device 8 disposed below the image forming unit is also provided.

  In addition to the transfer belt 11 and the plurality of primary transfer rollers 12Y, 12C, 12M, and 12Bk, the transfer belt unit 10 includes a plurality of belt support members such as a driving roller 72 and a driven roller 73 around which the transfer belt 11 is wound. ing. When the drive roller 72 is driven to rotate, the transfer belt 11 travels (rotates) in the direction indicated by the arrow A1 in the drawing. The drive roller 72 also functions as a secondary transfer backup roller that faces the secondary transfer roller 5 via the transfer belt 11. The driven roller 73 also functions as a cleaning backup roller that faces the cleaning device 13 through the transfer belt 11. Further, since the driven roller 73 also has a function as a tension urging unit for the transfer belt 11, the driven roller 73 is provided with an urging unit using a spring or the like. The transfer device 71 is configured to include the transfer belt unit 10, the primary transfer rollers 12Y, 12C, 12M, and 12Bk, the secondary transfer roller 5, and the transfer belt cleaning device 13.

  The secondary transfer roller 5 is disposed to face the transfer belt 11, and is driven by the transfer belt 11. Further, the secondary transfer roller 5 sandwiches the transfer belt 11 with the driving roller 72 that also functions as a secondary transfer backup roller, thereby forming a secondary transfer nip. Similarly to the primary transfer rollers 12Y, 12C, 12M, and 12Bk, a power source is also connected to the secondary transfer roller 5, and secondary transfer composed of a predetermined DC voltage (DC) and / or AC voltage (AC). A bias is applied to the secondary transfer roller 5.

  The transfer belt cleaning device 13 is disposed so as to face the driven roller 73 with the transfer belt 11 interposed therebetween, and cleans the surface of the transfer belt 11. In the illustrated example, the belt cleaning device 35 includes a cleaning brush and a cleaning blade disposed so as to contact the transfer belt 11. The waste toner transfer hose extending from the belt cleaning device 35 is connected to the entrance of the waste toner container.

  The image forming apparatus 100 is provided with a paper feed cassette (recording sheet feeding device) 61 as a sheet storage unit that stores the recording sheet P, a pair of registration rollers 4, and a recording sheet leading edge sensor. The paper feed cassette 61 is disposed at the lower part of the main body of the image forming apparatus, has a feed roller 3 that contacts the upper surface of the uppermost recording sheet P, and the feed roller 3 is driven to rotate counterclockwise. As a result, the uppermost recording sheet P is fed toward the registration roller pair 4.

  In the printer main body, a recording sheet conveyance path R for discharging the recording sheet P from the sheet feeding cassette 61 through the secondary transfer nip to the outside of the apparatus is disposed. A registration roller pair 4 for conveying the recording sheet P to the secondary transfer nip is disposed upstream of the position of the secondary transfer roller 5 in the recording sheet conveyance path R in the recording sheet conveyance direction. The registration roller pair 4 transfers the recording sheet P conveyed from the paper feed cassette 61 to the secondary transfer roller 5 and the transfer at a predetermined timing in accordance with the toner image formation timing by the image station composed of a plurality of image forming units. It feeds out toward the secondary transfer nip with the belt 11. The recording sheet leading edge sensor detects that the leading edge of the recording sheet P has reached the registration roller pair 4.

  As the recording sheet as the recording material, plain paper, thick paper, postcard, envelope, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, OHP sheet, and the like can be used. In addition to the paper feed cassette 61 such as a paper feed cassette, a manual paper feed mechanism may be provided so that recording sheets can be supplied manually.

  The image forming apparatus includes a fixing device 150 for fixing the toner image on the recording sheet P to which the toner image is transferred, a paper discharge roller 7, a paper discharge tray 17, and toner bottles 9Y and 9C as a plurality of toner containers. , 9M, 9Bk. The paper discharge roller 7 discharges the fixed recording sheet P to the outside of the main body of the image forming apparatus. The paper discharge tray 17 is disposed at the upper part of the main body of the image forming apparatus, and stacks the recording sheets P discharged to the outside of the main body of the image forming apparatus by the paper discharge roller 7.

  Each of the plurality of toner bottles 9Y, 9C, 9M, and 9Bk contains toner of each color of yellow, cyan, magenta, and black, and is a plurality of bottles provided on the upper side of the printer body and below the paper discharge tray 17. It is detachably attached to each accommodating part. Replenishment paths are provided between the toner bottles 9Y, 9C, 9M, 9Bk and the developing devices 40Y, 40C, 40M, 40Bk. The toner is replenished from the toner bottles 9Y, 9C, 9M, and 9Bk to the developing devices 40Y, 40C, 40M, and 40Bk through the replenishment path.

  The cleaning device 13 provided in the transfer device 71 includes a cleaning brush, a cleaning blade, and the like disposed so as to face and contact the transfer belt 11. By this cleaning brush and cleaning blade, foreign matters such as residual toner on the transfer belt 11 are scraped off and the transfer belt 11 is cleaned. The cleaning device 13 has discharge means for carrying out and discarding the residual toner removed from the transfer belt 11.

  When the image forming operation is started in the image forming apparatus, the photoconductors 20Y, 20C, 20M, and 20Bk are rotated in the clockwise direction in the drawing by the driving device. The surfaces of the photoconductors 20Y, 20C, 20M, and 20Bk are uniformly charged to a predetermined polarity by the charging devices 30Y, 30C, 30M, and 30Bk. The surfaces of the charged photoreceptors 20Y, 20C, 20M, and 20Bk are respectively irradiated with laser light from the optical writing device 8, and electrostatic latent images are formed on the surfaces of the photoreceptors 20Y, 20C, 20M, and 20Bk. The At this time, the image information exposed to the photoconductors 20Y, 20C, 20M, and 20Bk is single-color image information obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. The toner is supplied to the electrostatic latent images formed on the photoconductors 20Y, 20C, 20M, and 20Bk in this way by the developing devices 40Y, 40C, 40M, and 40Bk, so that the electrostatic latent images appear as toner images. Imaging (visualization).

  When the image forming operation is started, the drive roller 72 is rotationally driven in the counterclockwise direction of FIG. 1 to move the transfer belt 11 endlessly in the direction of the arrow A1 in the drawing. Then, a primary transfer bias subjected to constant voltage control or constant current control with a polarity opposite to the toner charging polarity is applied to the primary transfer rollers 12Y, 12C, 12M, and 12Bk. As a result, a predetermined primary transfer electric field is formed at the primary transfer nip between the primary transfer rollers 12Y, 12C, 12M, and 12Bk and the photoreceptors 20Y, 20C, 20M, and 20Bk.

  Thereafter, as the photoconductors 20Y, 20C, 20M, and 20Bk rotate, the Y, C, M, and Bk toner images on the photoconductors 20Y, 20C, 20M, and 20Bk enter the primary transfer nip for Y, C, M, and Bk. Reach. The Y, C, M, and Bk toner images on the photoconductors 20Y, 20C, 20M, and 20Bk are sequentially transferred onto the transfer belt 11 by the primary transfer electric field formed in the primary transfer nip for Y, C, M, and Bk. Overlaid and primary transferred. As a result, a four-color superimposed toner image is carried on the surface of the transfer belt 11. Transfer residual toner on the photoconductors 20Y, 20C, 20M, and 20Bk that could not be transferred to the transfer belt 11 is removed by the cleaning devices 50Y, 50C, 50M, and 50Bk. Thereafter, the surface of the photoconductors 20Y, 20C, 20M, and 20Bk is neutralized by the static eliminator, and the surface potential is initialized.

  In the lower part of the image forming apparatus, the feeding roller 3 starts to rotate, and the recording sheet P is sent out from the paper feeding cassette 61 to the conveyance path. The recording sheet P sent to the conveyance path is timed by the registration roller pair 4 and sent to the secondary transfer nip between the secondary transfer roller 5 and the drive roller 72. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the transfer belt 11 is applied to the secondary transfer roller 5, thereby forming a predetermined secondary transfer electric field in the secondary transfer nip. Has been.

  Thereafter, when the toner image on the transfer belt 11 reaches the secondary transfer nip as the transfer belt 11 moves endlessly, the four-color overlay on the transfer belt 11 is generated by the transfer electric field formed in the secondary transfer nip. The combined toner image is transferred onto the recording sheet P at once. At this time, the transfer residual toner on the transfer belt 11 that could not be transferred onto the recording sheet P is removed by the transfer belt cleaning device 13, and the removed toner is conveyed to a waste toner container and collected.

  Thereafter, the recording sheet P is conveyed to the fixing device 150, and the toner image on the recording sheet P is fixed to the recording sheet P by the fixing device 150. Then, the recording sheet P is discharged out of the apparatus by the paper discharge roller 7 and stocked on the paper discharge tray 17.

  The above description is an image forming operation when a full-color image is formed on the recording sheet P. A single-color image is formed using any one of the four image forming units, or two or It is also possible to form a two-color or three-color image using three image forming units.

  When the recording sheet is heated by the fixing device, the moisture of the recording sheet evaporates, the absolute humidity of the fixing atmosphere becomes very high, and condensation tends to occur. Therefore, an exhaust fan 101 serving as an exhaust mechanism that exhausts air in the atmosphere around the fixing device 150 to the outside of the fixing device 150 on the back side plate of the image forming apparatus 100 is provided. As a result, the air around the fixing device 150 having a high absolute humidity can be exhausted to the outside by the exhaust fan 101, and the occurrence of condensation can be suppressed.

FIG. 2 is a schematic configuration diagram illustrating a configuration example of the fixing device 150.
The fixing device 150 is provided with a pressure roller 84 that is a contact member that is rotationally driven, and a fixing belt 80 that is a fixing member. In the fixing belt 80, there are provided a nip forming member 86, a stay member 90, a first halogen heater 82a and a second halogen heater 82b as heating means, which will be described later. In this fixing device 150, a nip portion N is formed by pressing a fixing belt 80 against a rotationally driven pressure roller 84 by a nip forming member 86, and the nip portion N formed between the fixing belt 80 and the pressure roller 84. To hold the recording sheet. Then, heat is applied to the toner on the recording sheet from the surface of the fixing belt 80 heated by the first halogen heater 82a and the second halogen heater 82b, and the toner on the recording sheet is fixed by the action of heat and pressure.

  The pressure roller 84 is obtained by providing an elastic layer made of silicone rubber on the surface of a hollow metal roller. Furthermore, a release layer (PFA or PTFE layer) having a layer thickness of 5 to 50 μm is provided on the surface in order to obtain release properties. The pressure roller 84 is rotated by a driving force transmitted from a driving source such as a motor provided in the image forming apparatus via a gear. The pressure roller 84 is pressed against the fixing belt 80 side by a spring or the like. The pressure roller 84 and the fixing belt 80 are pressed against each other, and the elastic layer is crushed and deformed to form a predetermined nip width. To do. The pressure roller 84 may be a solid roller, but a hollow roller may have a smaller heat capacity. The elastic layer may be solid rubber or sponge rubber. The use of sponge rubber is more preferable because the heat insulating property is increased and the heat of the fixing belt 80 is hardly taken. Further, from the viewpoint of reducing the heat capacity, it is preferable to reduce the diameter of the pressure roller 84 as much as possible. Further, the pressure roller 84 may have a heating source such as a halogen heater.

  The fixing belt 80 is an endless belt member having flexibility. As the belt substrate, a metal belt such as nickel or SUS having a layer thickness of 30 to 50 μm, or an endless belt (or film) using a resin material such as polyimide is used. The surface layer of the fixing belt 80 has a release layer made of PFA or PTFE, and has a release property so that toner does not adhere. An elastic layer such as silicone rubber may be provided between the belt substrate and the release layer. When there is no elastic layer, the heat capacity is reduced and the fixability is improved, but when the unfixed image is crushed and fixed, subtle irregularities on the belt surface are transferred to the image, and a crusty skin-like mark is printed on the solid portion of the image. This causes a defect that remains. In order to improve this, it is preferable to provide an elastic layer of 100 μm or more such as silicone rubber. Due to the deformation of the elastic layer, subtle unevenness is absorbed and the skin image is improved.

  The fixing belt 80 is driven by the pressure roller 84 that is driven to rotate by a driving source, and the driving force is transmitted to the fixing belt 80 at the nip portion. Outside the nip portion, the fixing belt 80 is guided from both ends and is guided by a flange 104, and the cross-sectional shape rotates stably while maintaining a circular shape.

  The nip forming member 86 opposes the pressure roller 84 and holds the nip forming member main body 88 disposed inside the fixing belt 80 and the nip forming member main body 88 against the pressure applied from the pressure roller 84. It is comprised from the stay member 90. FIG.

  The nip forming member main body 88 slides directly on the inner peripheral surface of the fixing belt 80 or indirectly through a sliding sheet. Further, by applying a lubricant such as fluorine grease or fluorine oil to the inner peripheral surface of the fixing belt 80, the sliding torque is reduced. As a result, the fixing belt 80 is stably brought to the pressure roller 84. Further, by using fluorine grease or fluorine oil as the lubricant, the heat resistance stability is higher than when silicone oil is used as the lubricant, and good lubricity can be maintained over a long period of time.

  In FIG. 2, the nip portion N formed by the nip forming member main body 88 has a flat shape, but may have a concave shape or other shapes as viewed from the pressure roller side. In the case of the concave shape, the discharge direction of the front end of the paper is from the pressure roller 84, the separability is improved, and the occurrence of jam is suppressed.

  The stay member 90 has a sufficient bending strength to support the nip forming member main body 88 pressed by the pressure roller 84. As the material, a metal material such as stainless steel or iron, or a metal oxide such as ceramics is used. The stay member 90 is positioned with both axial ends fixed to the side plate of the fixing device 150. A fixing roller can be used in place of the fixing belt 80. In that case, the nip forming member 86 and the stay member 90 are unnecessary.

  The first halogen heater 82a and the second halogen heater 82b as heating means are arranged so that the three surfaces including the nip portion side are surrounded by the stay member 90 and the other surface faces the fixing belt 80. The first halogen heater 82a and the second halogen heater 82b are controlled in output (ON / OFF) by the control unit 200 (see FIG. 7) and heat the opposing fixing belt 80 by radiant heat. The heated fixing belt 80 moves to the nip portion N by rotation and applies heat to the toner on the recording paper. The first halogen heater 82a is a halogen heater having a dense light distribution at the center, and the second halogen heater 82b is a halogen heater having a dense light distribution at the end (see FIG. 5).

  Further, as shown in FIG. 2, a reflecting member 94 may be provided on the inner peripheral surface of the stay member 90. The reflecting member 94 is used by polishing the surface of a metal material into a mirror surface. The reflecting member 94 reflects the radiant heat emitted from the first halogen heater 82a and the second halogen heater 82b, thereby reducing the amount of heat flowing into the stay member 90 and improving the heating efficiency for the fixing belt 80. Further, the same effect can be obtained by performing a mirror surface treatment on the surface of the stay member 90 instead of providing the reflecting member 94. Also, providing a heat insulating member on the surface of the stay member 90 can reduce the amount of heat flowing into the stay member 90 and improve the heating efficiency for the fixing belt 80.

  Further, the fixing device 150 is provided with a flange 104 having an opening corresponding to the nip portion N that guides both end portions of the fixing belt 80 other than the nip portion N. The flange 104 has an outer diameter substantially equal to the inner diameter of the fixing belt 80, and has a length that enters 5 to 10 mm inward from both ends of the fixing belt 80. In other words, the flange 104 serves as a circumferential guide convex portion, and is inserted into the end portion of the fixing belt 80 and slides to maintain the cross-sectional shape of the fixing belt 80 in a circular shape.

Further, a thermistor 92 as temperature detecting means and a thermo switch 91 as a safety device are provided so as to face the outer peripheral surface of the fixing belt 80. The thermistor 92 is connected to a control unit 200 (see FIG. 7) described later, and the first halogen heater 82a and the second halogen heater 82b are controlled based on the detection result of the thermistor 92.
The thermo switch 91 is provided in an electric circuit for supplying power to the first halogen heater 82a and the second halogen heater 82b. And when the thermo switch 91 becomes 250 degreeC or more, a switch will switch from ON to OFF and the excessive heating by each halogen heater is prevented.

  In the fixing device 150 in FIG. 2, the maximum recording sheet width capable of image formation of the image forming apparatus is adapted. The recording sheet width in which image formation is overwhelming is usually A4 size vertical (A3 size horizontal), but some users require A3 nobi or 13 inches, so the image forming apparatus can cope with them. There are many. Therefore, in the fixing device 150 of FIG. 2, when fixing an image on the A4 size vertical recording sheet used by most users, A3 nobi or a width corresponding to 13 inches is heated. For this reason, extra heating is required for the difference between A4 size vertical and A3 nobi or 13 inches, which is a waste of energy. Note that “A4 size portrait” means that the A4 size paper is set so that the short side direction of the A4 size paper is the recording sheet conveyance direction, and “A3 size landscape” means that the longitudinal direction of the A3 size paper is When the sheet is set so as to be in the recording sheet conveyance direction.

  For this reason, the heating means (first and second halogen heaters) that heat the A4 size vertical width where an overwhelming user forms an image is separated from the heating means (end heater) that heats the outside of the A4 size length. It is preferable to do this. Usually, heating means (first and second halogen heaters) for heating the vertical width of A4 size is used. On the other hand, the heating means (first and second halogen heaters) for heating the A4 size vertical width and the means for heating the outside of the A4 size vertical (edges) only when image formation wider than the A4 size vertical is required. (Heater) is activated at the same time. This is advantageous in terms of energy.

  FIG. 3 is a schematic configuration diagram illustrating an example of a fixing device in which a heating unit that heats the A4 size vertical width and a heating unit that heats the outside of the A4 size vertical are separated. 4 is a perspective view showing the nip forming member main body 88 of the fixing device 150 shown in FIG. FIG. 5 is a diagram showing a first halogen heater 82a and a second halogen heater 82b that are heating means for heating the vertical width of the A4 size, and an end heater 112 that is a heating means for heating outside the A4 size vertical length. .

As shown in FIGS. 3 and 4, the end heater 112 as a heating means for heating the outside of the A4 size vertical is held in the nip forming member main body 88.
The difference between A4 vertical size (A3 horizontal size width) and A3 nobi (329 mm) and 13 inches (330 mm) is 32-33 mm. Therefore, if the heating is performed from both sides in the axial direction, the width corresponding to the paper can be changed from A4 vertical size (A3 horizontal size width) to 13 inches as shown in FIG. spread. Therefore, the end heater 112 may be a small heater having a length of about 20 mm.

  When passing a large size sheet such as A3 Nobi or 13 inches, the halogen heaters 82a and 82b and the end heater 112 are energized. On the other hand, when passing a sheet of A3 size or smaller, only the first and second halogen heaters 82a and 82b or the first halogen heater 82a are energized, and the end heater 112 is not energized. If the halogen heater 82b is configured to be able to handle large size paper such as A3 Novi, even if the large size paper is not passed through, the portion is heated and wasteful energy is consumed.

  As the end heater 112, it is preferable to use a heater having PTC characteristics. By using a heater having PTC characteristics, a resistance value increases above the set temperature and does not rise above the set temperature, and a safe fixing device can be realized. Accordingly, it is not necessary to provide a thermistor or the like to detect the temperature, and to control the ON / OFF of the power supply to the heater based on the detection result, and the control of the end heater 112 can be simplified. .

  However, when a heater having PTC characteristics is used as the end heater 112, it takes a longer time to heat up than the halogen heater. For this reason, if the end heater 112 and each of the halogen heaters 82a and 82b are heated at the same timing, only the inner side of the central portion is heated first, and wasteful energy is consumed.

  For this reason, the interval between sheets and the first printer time become longer and productivity is lowered. However, it is preferable to control the heating of the halogen heaters 82a and 82b in accordance with the heating cycle of the end heater 112. Thereby, temperature variation can be suppressed at the center and the end. That is, when the end heater 112 that heats the vicinity of both ends of the fixing belt 80 is used, the halogen heaters 82a and 82b corresponding to other normal size papers are heated in accordance with the temperature rise at the end of the fixing belt 80. To control. In this way, by controlling the heating, power is supplied to the halogen heater in order to maintain the central portion that has been previously heated to the predetermined temperature until the end of the fixing belt has been heated to the predetermined temperature. Can be prevented from consuming more energy than necessary.

  When a heater having a PTC characteristic is used as the end heater 112, if the heat is taken away by passing paper, the heating time is longer than the halogen heater to return to the target temperature due to the PTC characteristic. For this reason, the conveyance speed when conveying the paper of the size using the end heater 112 is made slower than the conveyance speed of the paper of other sizes. Thereby, the temperature fall of the heater which has a PTC characteristic can be suppressed, and favorable fixability can be maintained.

Further, as shown in FIG. 4, heater holding portions 88a and 88b are provided at both axial ends of the nip forming member main body 88, and the end heaters 112 are held by the heater holding portions 88a and 88b, respectively. Thereby, the end heater 112 can be disposed inside the fixing belt 80 in a space-saving manner. It is preferable to hold the end heater 112 so that the heating surface 112 a of the end heater 112 is flush with the contact surface 88 c that contacts the fixing belt 80 of the nip forming member main body 88. Accordingly, the fixing belt 80 is brought into close contact with the heating surface 112a of the end heater 112 by the pressure applied by the pressure roller 84, and the fixing belt 80 can slide on the heating surface 112a of the end heater 112 without a gap. Accordingly, heat can be conducted from the end heater 112 to the fixing belt 80 well, and the end of the fixing belt 80 can be efficiently heated.
Further, since the end heater 112 is provided inside the fixing belt 80, the end portion of the fixing belt can be satisfactorily heated without increasing the size of the apparatus.

  Further, as shown in FIG. 6, by providing a cover member 89 on the nip forming member main body 88 and the end heater 112, the fixing belt 80 is connected to the end heater 112, the notch-shaped heater holding portion 88a, It is possible to rotate smoothly without being caught in the gap between 88b. In addition, it is possible to form a uniform nip between the end portion and the central portion. The covering member 89 is preferably a thin and thermally conductive material, specifically, a steel material or aluminum material having good thermal conductivity is preferable, and the thickness is preferably 0.3 to 0.5 mm.

FIG. 7 is a diagram showing electrical connection between the first and second halogen heaters 82 a and 82 b and the end heater 112.
As shown in FIG. 7, each circuit that supplies power from the power source 120 to the halogen heaters 82a and 82b and the end heater 112 is provided with a switch 121 such as a relay switch. These switches 121 are connected to the control unit 200, and ON / OFF of the switches is controlled by the control unit 200.

  The first halogen heater 82a and the second halogen heater 82b are electrically connected in parallel. The end heaters 112 are electrically connected in series, and are connected in parallel to the halogen heaters 82a and 82b. In the present embodiment, since the recording sheet is conveyed based on the center, the end heater 112 is always driven to be heated at the same time. Therefore, by connecting the end heaters 112 in series, the control can be simplified as compared with the case where they are connected in parallel.

  As shown in FIG. 7, a thermo switch 91 is incorporated in this electric circuit, and when the thermo switch 91 reaches a predetermined temperature (250 ° C. in this embodiment), the switch is turned off, The power supply to the second halogen heaters 82a and 82b is forcibly cut off. Thereby, it is possible to prevent the fixing device 150 from being abnormally heated.

  Since the recording sheet to which the unfixed toner image is transferred has a large heat capacity, it is necessary to precisely control the temperature at the nip portion N through which the recording sheet passes. The temperature control of the fixing device 150 is performed by the control unit 200, and the supply power of each of the halogen heaters 82a and 82b is controlled based on the temperature information detected by the thermistor 92, the image formation instruction information, and the like. It is controlled so that the temperature between the nips is at an appropriate temperature.

  Very rarely, the malfunction of the control unit 200 may cause the energization control of the halogen heaters 82a and 82b to become uncontrollable, and so-called thermal runaway may occur where abnormal heating occurs. In this embodiment, when the thermistor 92 senses an abnormally high temperature, the power supply to the first and second halogen heaters 82a and 82b can be shut off by software different from the temperature control software, and thermal runaway occurs. To prevent it from continuing. In some cases, the switch 121 that cuts off the power supply to the halogen heaters 82a and 82b breaks down, so that the power supply to the halogen heaters 82a and 82b cannot be cut off. Even in such a situation, when the thermo switch 91 reaches a predetermined temperature or more, the switch is turned off and the power supply to the halogen heaters 82a and 82b is forcibly cut off. Thus, in this embodiment, a plurality of measures are taken so that the fixing device 150 does not become abnormally high temperature.

  However, the thermistor 92 and the thermo switch 91 are arranged at locations away from the outer peripheral surface of the fixing belt 80 as shown in FIGS. Therefore, in the fixing belt 80 or the fixing belt, the temperature may reach 400 ° C. or more before the thermistor 92 or the thermo switch 91 detects an abnormally high temperature and the power supply to the halogen heaters 82a and 82b is cut off. is there. In particular, the fixing device according to the present embodiment uses a thin fixing belt having a low heat capacity in order to shorten the warm-up time and the first print time. It tends to be over ℃.

  In the fixing device 150 of the present embodiment, a release layer made of PFA or PTFE fluororesin is provided on the surface of the pressure roller 84 or the surface of the fixing belt 80. Further, fluorine oil or fluorine grease is applied to the inner peripheral surface of the fixing belt 80 as a lubricant. Thus, a very large number of fluorine compounds are used in the fixing device 150 of this embodiment. When the fluorine compound is heated at 400 ° C. or higher, decomposition starts and fluorine gas is generated from the fluorine compound. This fluorine gas reacts with moisture in the atmosphere to generate hydrofluoric acid (hydrogen fluoride), which is a harmful substance. The generated hydrofluoric acid is exhaust 5 provided in the vicinity of the fixing device 150 shown in FIG. There was a risk of being discharged out of the machine by the fan 101.

Therefore, in the present embodiment, a hydrofluoric acid absorbent that absorbs hydrofluoric acid is provided to absorb hydrofluoric acid generated by thermal runaway so that the hydrofluoric acid is not discharged out of the machine.
FIG. 8 is a diagram illustrating an example of the arrangement of the hydrofluoric acid absorbent 95.
As shown in FIG. 8, a sheet-like hydrofluoric acid absorbent 95 is affixed to the inner peripheral surface of the housing 150a. The portion where the sheet-like hydrofluoric acid absorbent is applied is attached to a place where the generated hydrofluoric acid is likely to come into contact in consideration of a decrease in the specific gravity of the air due to heating and the air flow caused by exhaust. As described above, by providing the housing 150a with the hydrofluoric acid absorbent, the hydrofluoric acid generated in the fixing device can be brought into contact with the hydrofluoric acid absorbent before diffusion, and the hydrofluoric acid absorbent can be brought out of the fixing device. Compared with the case where an acid absorbent is provided, hydrofluoric acid can be favorably absorbed.

  As the hydrofluoric acid absorbent, alkali metal, alkaline earth metal, magnesium, aluminum or silicon hydroxide salt, carbonate, phosphate, aluminate, nitrate, oxide can be used. Further, lithium, calcium, aluminum metal soap or complex soap can be used. In particular, calcium carbonate, magnesium carbonate, and magnesium oxide are preferable because of their extremely high reaction rate with hydrofluoric acid. Calcium carbonate, magnesium carbonate, and magnesium oxide are inexpensive materials, and are themselves stable and harmless materials in a normal environment, and are preferable as a hydrofluoric acid absorbent. Furthermore, calcium carbonate, magnesium carbonate, and magnesium oxide are preferable because the product reacted with hydrofluoric acid is harmless and stable.

  As the calcium carbonate, either chemically synthesized light calcium carbonate, heavy calcium carbonate obtained by pulverizing limestone, marble, shells or the like can be used. Since heavy calcium carbonate is derived from natural products, it contains Al, Mg, and Si, but even if these impurities react with hydrofluoric acid, there is no problem because the reaction product is stable and harmless. Calcium carbonate reacts quickly with hydrofluoric acid to form calcium fluoride.

Magnesium carbonate may be either a natural product or a synthetic product, but considering the quality and cost, a synthetic product is preferred. As magnesium carbonate, which is a composite, basic magnesium carbonate (mMgCO ₃ .Mg (OH) ₂ .nH ₂ O), basic magnesium carbonate, pure magnesium carbonate (MgCO ₃ ) can be used. Magnesium carbonate reacts quickly with hydrofluoric acid to become magnesium fluoride.

  Magnesium carbonate turns into magnesium oxide at a temperature of 350 ° C. or higher. However, magnesium oxide itself is a very stable material even at high temperatures. It reacts quickly with hydrofluoric acid and is harmless and stable with magnesium fluoride. Become. Therefore, hydrofluoric acid can be satisfactorily absorbed even when magnesium oxide is formed at a high temperature due to thermal runaway. Further, magnesium oxide may be used from the beginning as the hydrofluoric acid absorbent.

  In the above description, the sheet-like hydrofluoric acid absorbent 95 is attached to the housing 150a. However, the hydrofluoric acid absorbent may be applied to the housing 150a. In this case, in consideration of a decrease in the specific gravity of air due to heating and an air flow due to exhaust or the like, it is preferable to apply a large amount of hydrofluoric acid absorbent to a portion where the generated hydrofluoric acid is likely to come into contact. Further, the housing 150a may be formed of a material containing a hydrofluoric acid absorbent.

FIG. 9 is an exploded perspective view showing another example of the arrangement of the hydrofluoric acid absorbent 95.
As shown in FIG. 9, in this example, a sheet-like hydrofluoric acid absorbent 95 is provided at both ends of the fixing belt 80 so as to block the inside of the fixing belt 80. When the thermal runaway occurs, the highest temperature is in the fixing belt 80 in which the halogen heaters 82a and 82b are disposed. As described above, the lubricant is applied to the inner peripheral surface of the fixing belt 80, and the lubricant is likely to have a high temperature of 400 ° C. or higher. Accordingly, fluorine oil or fluorine grease used as a lubricant is decomposed to generate fluorine gas inside the fixing belt 80, and fluorine gas reacts with water vapor inside the fixing belt to generate hydrofluoric acid.

  In the configuration shown in FIG. 9, the inside of the fixing belt 80 is closed by the hydrofluoric acid absorbent 95, so that the hydrofluoric acid generated inside the fixing belt 80 can be reliably absorbed by the hydrofluoric acid absorbent 95. Thereby, it is possible to suppress discharge of hydrofluoric acid to the outside of the image forming apparatus.

  Further, when a hydrofluoric acid absorbent is provided in the housing 150a as shown in FIG. 8, or a hydrofluoric acid absorbent 95 is provided at both ends of the fixing belt 80 so as to close the inside of the fixing belt 80 as shown in FIG. Calcium carbonate is preferably used as the hydrofluoric acid absorbent. Calcium carbonate has high heat insulation (low thermal conductivity), so by using calcium carbonate as the hydrofluoric acid absorbent 95, heat outflow can be suppressed, making it easy to control the fixing temperature and saving energy. Can be achieved.

  In addition, the sheet-like hydrofluoric acid absorbent 95 may be disposed on the stay member 90, or the hydrofluoric acid absorbent may be attached to the surface of the stay member 90 by applying the hydrofluoric acid absorbent or the like. Also in this case, it is preferable to use calcium carbonate as the hydrofluoric acid absorbent because heat outflow to the stay member 90 is suppressed.

  Further, the material forming the fixing belt 80 and the pressure roller 84 may be mixed. When mixed with the material forming the fixing belt 80 and the pressure roller 84, it is preferable to use magnesium oxide having high thermal conductivity as the hydrofluoric acid absorbent.

  Further, a hydrofluoric acid absorbent may be contained in the lubricant applied to the inner peripheral surface of the fixing belt 80. As the hydrofluoric acid absorbent to be contained in the lubricant (fluorine oil / fluorine grease), calcium carbonate, lithium, calcium, aluminum metal soap or complex soap, and magnesium oxide are preferable. Of these, metal soaps or complex soaps of lithium, calcium, and aluminum are preferable because they can be used as a thickener for grease. In particular, complex soaps of lithium, calcium, and aluminum are preferable because of high thermal stability and high reactivity with hydrofluoric acid. Further, magnesium oxide is also preferable as the hydrofluoric acid absorbent to be contained in the lubricant (fluorine oil / fluorine grease). Magnesium oxide is highly reactive with hydrofluoric acid and has relatively good thermal conductivity, so even if it is contained in a lubricant, it does not hinder the temperature rise of the fixing belt 80.

FIG. 10 is a diagram showing still another example of the arrangement of the hydrofluoric acid absorbent.
As shown in FIG. 10, in this example, the exhaust fan 101 is provided with a filter 195 containing a hydrofluoric acid absorbent. Even when the fixing thermal runaway starts, the exhaust fan 101 normally continues to rotate and continues to exhaust the air around the fixing device 150 to the outside of the apparatus. Therefore, the hydrofluoric acid generated in the fixing device 150 is exhausted outside the apparatus through the exhaust fan together with the air around the fixing device 150 by the intake air by the exhaust fan 101. Therefore, by providing the exhaust fan 101 with the filter 195 containing hydrofluoric acid absorbent, the air containing hydrofluoric acid is exhausted to the outside of the machine through the filter 195 containing hydrofluoric acid absorbent. Become. At this time, hydrofluoric acid is absorbed by the hydrofluoric acid absorbent contained in the filter 195. As a result, discharge of hydrofluoric acid to the outside of the machine can be suppressed.

Next, verification experiments conducted by the applicant will be described.
[Verification Experiment 1]
[Comparative Example 1]
A fixing device (image MPC5002 (manufactured by Ricoh)) in which the lubricant is replaced by fluorine grease from silicone oil is placed in a chamber of 1 m ³ with an inner wall having a polymethyl methacrylate plate, and the temperature of the fixing belt surface is monitored. A thermal runaway was intentionally generated until the thermistor 92 detected detected an abnormally high temperature and switched off. The atmosphere in the chamber was absorbed into an absorbing solution (distilled water), and the total amount of hydrofluoric acid discharged was measured by ion chromatography to be 1.23 mg.

[Example 1]
About 100 μm was applied to the upper inner surface of the case of the fixing device of Comparative Example 1 with a paint containing calcium carbonate as a hydrofluoric acid absorbent, and the same experiment as in Comparative Example 1 was performed to measure the total amount of hydrofluoric acid discharged. 0.19 mg. This is because calcium carbonate as a hydrofluoric acid absorbent coated and adhered to the upper inner surface of the housing absorbed hydrofluoric acid generated by thermal runaway, resulting in a large total hydrofluoric acid discharge compared to Comparative Example 1. It is thought that it was suppressed.

[Example 2]
In the fixing device of Example 1, magnesium oxide powder was mixed as a hydrofluoric acid absorbent as a filler in the lubricant applied to the inner surface of the fixing belt, the same experiment as in Comparative Example 1 was performed, and the total discharge amount of hydrofluoric acid was measured. As a result, it was 0.05 mg. Thus, by mixing magnesium oxide powder as a hydrofluoric acid absorbent in the lubricant, the magnesium oxide mixed in the lubricant reacted with the generated hydrofluoric acid to absorb the hydrofluoric acid. It is considered that the total discharge amount of hydrofluoric acid was further suppressed than 1.

[Example 3]
Calcium carbonate paper (thickness: 0.23 mm) as a sheet-like hydrofluoric acid absorbent mainly composed of calcium carbonate, aluminum hydroxide, and pulp was attached to the inner surface of the fixing casing used in Comparative Example 1. An experiment similar to that of Comparative Example 1 was performed, and the total discharge amount of hydrofluoric acid was measured and found to be 0.08 mg. Also in this Example 3, as a result of the calcium carbonate paper absorbing the hydrofluoric acid generated by the thermal runaway as the hydrofluoric acid absorbent attached to the inner surface of the casing, the total discharge amount of hydrofluoric acid is significantly larger than that of Comparative Example 1. It is thought that it was suppressed.

[Comparative Example 2]
In Comparative Example 1, thermal runaway was intentionally generated until the thermistor detected an abnormally high temperature and switched off in the same manner as in Comparative Example 1, except that the thermistor was further moved away from the fixing belt by 1 mm. The total amount of hydrofluoric acid discharged was measured and found to be 9.6 mg. In Comparative Example 2, the experiment was performed with a longer thermal runaway time than in Comparative Example 1. Therefore, the total amount of hydrofluoric acid discharged was significantly higher than that of Comparative Example 1. However, the amount of hydrofluoric acid in Comparative Example 2 is 0.096 ppm in terms of concentration, and the management concentration is 0.5 ppm (Ministry of Health, Labor and Welfare Ordinance No. 95 “A Case for Partial Revision of Work Environment Evaluation Criteria” 2009.7. This is a sufficiently low value compared to .1 implementation). However, for higher safety, it is desirable to reduce the concentration of hydrofluoric acid.

[Example 4]
In the fixing device having the same configuration as that of the third embodiment, the thermal thermistor is intentionally performed until the thermistor detects an abnormally high temperature and is turned off in the same manner as in the first comparative example except that the position of the thermistor is further 1 mm away from the fixing belt. Generated. The total amount of hydrofluoric acid discharged was measured and found to be 0.91 mg. Thus, by providing the hydrofluoric acid absorbent, the total discharge amount of hydrofluoric acid could be satisfactorily suppressed even under severe conditions where the thermal runaway time was further prolonged.

[Verification experiment 2]
[Comparative Example 3]
An image forming apparatus in which the fixing device of the image forming apparatus (image MPC5002 (manufactured by Ricoh)) is used as the fixing apparatus of Comparative Example 1 is placed in a chamber having an inner volume of 1 m ³ having an inner wall made of a polymethylmethacrylate plate, and the thermistor is abnormally hot Thermal runaway was deliberately generated until it was detected and switched off. And the air | atmosphere in a chamber was made to absorb in absorption liquid (distilled water), and the total discharge amount of hydrofluoric acid was measured by the ion chromatography method. As a result, the amount of hydrofluoric acid generated was 0.09 mg.

[Example 5]
In Comparative Example 3, a filter added with calcium carbonate as a hydrofluoric acid absorbent was set at the exhaust port for discharging the atmosphere near the fixing device to the outside of the apparatus. As a result of the measurement, hydrofluoric acid was not detected. Thus, it was confirmed that the release of hydrofluoric acid to the outside of the image forming apparatus can be prevented by providing a filter to which calcium carbonate is added as a hydrofluoric acid absorbent.

[Example 6]
In Comparative Example 3, the same test as in Comparative Example 3 was performed in the same manner except that the fixing device prepared in Example 3 was used. When the amount of hydrofluoric acid generated was measured, no hydrofluoric acid was detected. This is because the calcium carbonate paper as a hydrofluoric acid absorbent attached to the inner surface of the casing absorbs hydrofluoric acid generated by thermal runaway, and the hydrofluoric acid discharged from the fixing device into the image forming apparatus is greatly reduced. It is considered that even a small amount of hydrofluoric acid that was not absorbed by the hydrofluoric acid absorbent was absorbed by reacting with members in the apparatus, and as a result, release of hydrofluoric acid to the outside of the image forming apparatus could be prevented.

  By providing a hydrofluoric acid absorbent from Example 5 and Example 6, it is possible to prevent the hydrofluoric acid from leaking out of the image forming apparatus, and to provide an image forming apparatus with higher safety. I understand.

  In the above description, the fixing device using the fixing belt has been described. However, the hydrofluoric acid absorbent may be disposed in the fixing device using the fixing roller and the image forming apparatus including the fixing device using the fixing roller. Good. For example, when a fluorine compound is used, such as providing a release layer of fluorine resin such as PFA or PTFE on the surface layer of the fixing roller, hydrofluoric acid may be generated when thermal runaway occurs. Accordingly, even in a fixing device using a fixing roller and an image forming device including a fixing device using a fixing roller, when a thermal runaway occurs due to the arrangement of the hydrofluoric acid absorbent, the hydrofluoric acid image forming device. Release to the outside can be prevented.

What was demonstrated above is an example, and there exists an effect peculiar for every following aspect.
(Aspect 1)
A fixing member such as the fixing belt 80 and heating means such as halogen heaters 82a and 82b for heating the fixing member are provided, and the unfixed toner on the recording material such as the recording sheet P being conveyed is heated, thereby A fixing device 150 for fixing unfixed toner on the recording material, which has a hydrofluoric acid absorbent.
According to this, since the hydrofluoric acid absorbent is provided, even if hydrofluoric acid is generated due to thermal runaway, it can be absorbed by the hydrofluoric acid absorbent. Thereby, it can suppress that hydrofluoric acid leaks out of an apparatus, and can improve the safety | security of an apparatus.

(Aspect 2)
(Aspect 1) wherein the hydrofluoric acid absorbent is an alkali metal, alkaline earth metal, magnesium, aluminum or silicon hydroxide salt, carbonate, phosphate, aluminate salt, nitrate, oxide, or Lithium, calcium and aluminum metal soaps or complex soaps thereof.
According to this, it reacts quickly with the hydrofluoric acid generated by the thermal runaway, and the hydrofluoric acid can be absorbed well.

(Aspect 3)
(Aspect 2) The hydrofluoric acid absorbent is calcium carbonate, magnesium carbonate, or magnesium oxide.
These are inexpensive materials and are themselves preferable because they are stable and harmless materials in a normal environment. Furthermore, these materials are preferred because the products reacted with hydrofluoric acid are harmless and stable.

(Aspect 4)
In (Aspect 1) to (Aspect 3), the hydrofluoric acid absorbent is provided in the casing 150a that houses the fixing member such as the fixing belt 80 and heating means such as the halogen heaters 82a and 82b.
According to this, as shown in Examples 1, 3, 4, and 6 in the verification experiment, hydrofluoric acid can be favorably absorbed, and the hydrofluoric acid can be prevented from being discharged from the image forming apparatus. it can.

(Aspect 5)
In any one of (Aspect 1) to (Aspect 4), the fixing member such as the fixing belt 80 is an endless belt member that is rotatably provided, and is in contact with the pressure roller 84 that is in contact with the outer peripheral surface of the fixing member. And a nip forming member 86 which is disposed on the inner peripheral side of the belt member and abuts against the contact member via the belt member to form a nip portion N. The recording material such as the recording sheet P is provided in the nip portion N. The unfixed toner on the recording material is heated.
According to this, as described in the embodiment, the fixing belt 80 can be quickly heated to a specified temperature, and the warm-up time and the first print time can be shortened. On the other hand, when a thermal runaway occurs, the fixing belt 80 is heated to 400 ° C. or more, and fluorine gas is generated from the release layer made of the fluororesin of the fixing belt. Acid is likely to be generated.
However, in this embodiment, since the hydrofluoric acid absorbent is provided, it is possible to satisfactorily suppress the hydrofluoric acid from leaking out of the image forming apparatus even in an apparatus configuration in which hydrofluoric acid is likely to be generated.

(Aspect 6)
In (Aspect 5), a lubricant is interposed between the inner peripheral surface of a belt member such as the fixing belt 80 and the nip forming member 86, and the hydrofluoric acid absorbent is contained in the lubricant.
According to this, as shown in Example 2 of the verification experiment, hydrofluoric acid generated due to thermal runaway can be absorbed well, and discharge of hydrofluoric acid can be suppressed well.

(Aspect 7)
In (Aspect 5) or (Aspect 6), a lubricant is interposed between the inner peripheral surface of a belt member such as the fixing belt 80 and the nip forming member 86, and the lubricant is fluorine oil or fluorine grease. It is.
According to this, as described in the embodiment, it is possible to improve the heat resistance stability as compared with the case where silicone oil is used as the lubricant, and it is possible to maintain good lubricity over a long period of time.
Further, by using fluorine oil or fluorine grease as a lubricant, when heated at 400 ° C. or more due to thermal runaway, fluorine gas is decomposed and fluorine gas reacts with water vapor to generate hydrofluoric acid. There is. However, in this embodiment, since the hydrofluoric acid absorbent is provided, the hydrofluoric acid generated by using the lubricant of fluorine oil or fluorine grease can be absorbed well.

(Aspect 8)
Toner image forming means (comprising charging device 30, optical writing device 8, developing device 40, etc.) for forming a toner image on an image carrier such as photoreceptor 20, and recording the toner image from the image carrier. In an image forming apparatus comprising transfer means such as a transfer device 71 for transferring onto a recording material such as a sheet, and fixing means such as a fixing device 150 for fixing the toner image transferred onto the recording material to the recording material. As the fixing means, the fixing device according to any one of (Aspect 1) to (Aspect 7) is used.
According to this, even when the fixing device 150 is thermally runaway, it is possible to suppress leakage of hydrofluoric acid from the image forming apparatus, and it is possible to provide a highly safe image forming apparatus.

(Aspect 9)
(Aspect 8) includes an exhaust mechanism such as an exhaust fan 101 that exhausts air in the fixing unit atmosphere such as the fixing device 150 to the outside of the device, and the exhaust mechanism includes a filter containing a hydrofluoric acid absorbent, Air in the apparatus is exhausted through the filter.
According to this, as shown in the fifth embodiment of the verification experiment, it is possible to suppress the leakage of hydrofluoric acid from the image forming apparatus even if the fixing device 150 is thermally runaway.

(Aspect 10)
Toner image forming means (comprising charging device 30, optical writing device 8, developing device 40, etc.) for forming a toner image on an image carrier such as photoreceptor 20, and recording the toner image from the image carrier. In an image forming apparatus comprising transfer means such as a transfer device 71 for transferring onto a recording material such as a sheet, and fixing means such as a fixing device 150 for fixing the toner image transferred onto the recording material to the recording material. It has an exhaust mechanism such as an exhaust fan 101 that exhausts the air in the fixing unit atmosphere to the outside of the apparatus. The exhaust mechanism includes a filter containing a hydrofluoric acid absorbent, and exhausts the air in the apparatus through the filter. To do.
According to this, as shown in the fifth embodiment of the verification experiment, it is possible to suppress the leakage of hydrofluoric acid from the image forming apparatus even if the fixing device 150 is thermally runaway.

(Aspect 11)
In (Aspect 10), the hydrofluoric acid absorbent is an alkali metal, alkaline earth metal, magnesium, aluminum or silicon hydroxide salt, carbonate, phosphate, aluminate salt, nitrate salt, oxide, or lithium. , Calcium and aluminum metal soaps or complex soaps thereof.
According to this, it reacts quickly with the hydrofluoric acid generated by the thermal runaway, and the hydrofluoric acid can be absorbed well.

(Aspect 12)
In (Aspect 11), the hydrofluoric acid absorbent is calcium carbonate, magnesium carbonate, or magnesium oxide.
These are inexpensive materials and are themselves preferable because they are stable and harmless materials in a normal environment. Furthermore, these materials are preferred because the products reacted with hydrofluoric acid are harmless and stable.

DESCRIPTION OF SYMBOLS 8 Optical writing device 20 Photoconductor 30 Charging device 40 Developing device 71 Transfer device 80 Fixing belt 82a First halogen heater 82b Second halogen heater 84 Pressure roller 86 Nip forming member 88 Nip forming member main body 88a, 88b Heater holding portion 88c Contact surface 89 Cover member 90 Stay member 91 Thermo switch 92 Thermistor 94 Reflective member 95 Hydrofluoric acid absorbent 100 Image forming device 101 Exhaust fan 104 Flange 112 End heater 112a Heating surface 120 Power supply 121 Switch 150 Fixing device 150a Housing 195 Filter 200 Control part N Nip part P Recording sheet

JP 2005-84225 A

Claims (12)

A fixing device comprising a fixing member and a heating unit for heating the fixing member, and fixing the unfixed toner on the recording material by heating the unfixed toner on the recording material being conveyed. ,
A fixing device comprising a hydrofluoric acid absorbent.   The hydrofluoric acid absorbent is an alkali metal, alkaline earth metal, magnesium, aluminum or silicon hydroxide salt, carbonate, phosphate, aluminate, nitrate, oxide or lithium, calcium or aluminum metal The fixing device according to claim 1, wherein the fixing device is soap or a complex soap thereof.   The fixing device according to claim 2, wherein the hydrofluoric acid absorbent is calcium carbonate, magnesium carbonate, or magnesium oxide.   The fixing device according to claim 1, wherein the hydrofluoric acid absorbent is provided in a housing that houses the fixing member and the heating unit. The fixing member is an endless belt member rotatably provided;
A contact member in contact with the outer peripheral surface of the fixing member;
A nip forming member disposed on the inner peripheral side of the belt member and abutting the contact member via the belt member to form a nip portion;
With
The fixing device according to claim 1, wherein the recording material is passed through the nip portion to heat unfixed toner on the recording material. A lubricant is interposed between the inner peripheral surface of the belt member and the nip forming member,
The fixing device according to claim 5, wherein the lubricant contains the hydrofluoric acid absorbent. A lubricant is interposed between the inner peripheral surface of the belt member and the nip forming member,
The fixing device according to claim 5, wherein the lubricant is fluorine oil or fluorine grease. Toner image forming means for forming a toner image on the image carrier;
Transfer means for transferring the toner image from the image carrier onto a recording material;
Fixing means for fixing the toner image transferred onto the recording material to the recording material;
An image forming apparatus comprising:
An image forming apparatus using the fixing device according to claim 1 as the fixing unit. An exhaust mechanism for discharging the air in the fixing unit atmosphere out of the apparatus;
The image forming apparatus according to claim 8, wherein the exhaust mechanism includes a filter containing the hydrofluoric acid absorbent, and exhausts air in the apparatus through the filter. Toner image forming means for forming a toner image on the image carrier;
Transfer means for transferring the toner image from the image carrier onto a recording material;
Fixing means for fixing the toner image transferred onto the recording material to the recording material;
An image forming apparatus comprising:
An exhaust mechanism for discharging the air in the fixing unit atmosphere out of the apparatus;
The image forming apparatus, wherein the exhaust mechanism includes a filter containing a hydrofluoric acid absorbent, and exhausts air in the apparatus through the filter.   The hydrofluoric acid absorbent is an alkali metal, alkaline earth metal, magnesium, aluminum or silicon hydroxide salt, carbonate, phosphate, aluminate, nitrate, oxide or lithium, calcium or aluminum metal The image forming apparatus according to claim 10, wherein the image forming apparatus is soap or a complex soap thereof.   The image forming apparatus according to claim 11, wherein the hydrofluoric acid absorbent is calcium carbonate, magnesium carbonate, or magnesium oxide.

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