JP2012063463A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an operator from touching a high temperature member even if the operator touches a fixing device when removing a jam or the like.SOLUTION: The fixing device 130 includes a pressure roller 133 and an endless fixing belt 131 forming a nip part 136 in contact with the pressure roller 133. A heating means 132, a pressure pad 134, and a reflection plate 135 are provided inside the fixing belt 131. The reflection plate 135 is composed of reflection members 135a, 135b and 135c and functions as a surrounding member driven by a driving means and disposed so as to surround the heating means 132. The driving means disposes the reflection members 135a and 135c in a heating position where a predetermined function is exhibited by the heating means when the heating means 132 is heating, and disposes them in the position where the heating means 132 is surrounded to prevent fingers 50 from touching the heating means 132 via the fixing belt 131 when the heating means 132 is not heating.

Description

  The present invention relates to a fixing device and an image forming apparatus, and in particular, includes a heating unit, a reflecting plate, and a fixing pad in a cylindrical fixing belt, and is formed between the fixing pad and a pressure roller with the fixing belt interposed therebetween. The present invention relates to a fixing device that fixes a toner image on a recording medium at a nip portion, and an image forming apparatus including the fixing device.

  In an image forming apparatus such as a copying machine, a printer, or a facsimile machine, an electrostatic latent image formed on a photoreceptor is developed with toner to create a toner image, and the toner image is placed on a recording medium such as printing paper. Transcript. Then, the recording medium carrying the toner image is pressed and heated at a fixing nip portion in a pressure contact state of the fixing device, and the toner image is fused on the recording medium for fixing.

  One example of such a fixing device is one that uses a fixing roller. FIG. 8 is a sectional view conceptually showing a conventional fixing device using a fixing roller. The fixing device 10 includes a fixing roller 11 including a heating unit 12 such as a halogen heater, and a pressure roller 13 in contact with the fixing roller 11. The recording medium on which the toner image is formed is inserted from the sheet feeding direction into the nip portion 14 formed between the fixing roller 11 and the pressure roller 13 that rotate along the arrow in the figure, and is added at the nip portion 14. The toner image is fixed on the recording medium by pressure and heating.

  Also, there is a fixing device that uses a fixing belt having a smaller heat capacity than the fixing roller in order to shorten the heating time for fixing and improve usability. FIG. 9 is a sectional view conceptually showing a conventional fixing device using a fixing belt. The fixing device 20 includes a heating roller 21 including a heating unit 22 such as a halogen heater, a fixing roller 23 disposed away from the heating roller 21, and an endless wound around the heating roller 21 and the fixing roller 23. And a pressure roller 25 that contacts the fixing roller 23 via the fixing belt 24 and pressurizes the fixing belt 24 with the fixing roller 23. The recording medium on which the toner image is formed is inserted from the sheet passing direction and is pressed and heated by a nip portion 26 formed between the fixing belt 24 and the pressure roller 25, and the toner image is fixed on the recording medium. The

  Furthermore, in order to shorten the heating time, there is a fixing device in which the heat roller is omitted and the heat capacity is reduced. FIG. 10 is a sectional view conceptually showing a conventional fixing device in which a heating roller is omitted. FIG. 10A shows a schematic configuration of the fixing device, and FIG. 10B is a schematic diagram showing a state in which a finger contacts the fixing device. As shown in FIG. 10A, the fixing device 30 includes a substantially cylindrical flexible endless fixing belt 31, heating means 32 including a halogen heater that directly heats the fixing belt 31, and a fixing belt. A reflection pad 33 disposed between the fixing pad 34 and the heating unit 32 and the fixing pad 34, which shields heat toward the fixing pad 34 and reflects heat toward the anti-fixing pad 34; And a pressure roller 35 that presses against the fixing belt 24 via the fixing belt 31 to form a nip portion 36 (see Patent Document 1).

  Further, there are the following fixing devices including a reflecting plate that reflects the heat radiation of the heating means. In Patent Document 2, a rod-shaped heater lamp is provided in a heat roller that is rotationally driven, and a plurality of heater lamps are provided between the heater lamp and the heat roller at different positions in a radial direction with the heater lamp as a substantial center. A fixing device provided with a single reflector (reflector) is described.

  Further, Patent Document 3 discloses a heat reflecting member having a U-shaped cross section extending along the heater lamp between the heater lamp and the inner surface of the fixing rotator and with the opening portion extending toward the heater lamp side ( A fixing device including a reflector) and a driving device that drives at least one of a heater lamp and a heat reflecting member is described.

  By the way, the fixing device 30 using the endless fixing belt by omitting the heating roller among the conventional fixing devices described above has a reduced heat capacity by the amount of the abolition of the heating roller, shortening the heating time, and improving usability. Although there is an advantage, the operator touches the fixing device 30 at the time of the jam processing for eliminating the paper jam, and as shown in FIG. 10B, the operator contacts the high temperature heating means 32 through the fixing belt 24, and burns. May incur.

  In such a fixing device 30, the fixing set temperature is set to 150 to 180 ° C., whereas the temperature of the heating means such as a halogen heater is set to a high value of about 800 ° C. For this reason, as shown in FIG. 10B, when the fixing belt 31 that is in contact with or close to the heating unit 32 is touched with the finger 50, the fixing belt 31 is deformed and the finger 50 passes through the fixing belt 31. Thus, the heating means 32 is brought into contact. When the heating unit 22 is provided in the heating roller 21 as in the fixing device 10 illustrated in FIG. 8, the possibility that the user directly touches the heater unintentionally is extremely low. In the fixing device 30 shown in a), there is a possibility that the fixing belt 31 is deformed and the heating means 32 is touched via the fixing belt 31.

  Accordingly, an object of the present invention is to provide a fixing device and an image forming apparatus that can prevent a high temperature member from coming into contact with the fixing device even when an operator touches the fixing device when a jam is resolved.

  According to a first aspect of the present invention, an endless fixing belt having flexibility, a pressure member disposed inside the fixing belt, and a pressure member that is pressed against the pressure member via the fixing belt, the fixing belt A pressure roller that forms a nip portion therebetween, a heating unit that is disposed inside the fixing belt and heats the fixing belt, and a reflector that is disposed between the heating member and the pressure member. And a fixing device for fixing a recording medium carrying an unfixed toner image in the nip portion, wherein the surrounding member is movable to a position surrounding the heating means inside the fixing belt, and an arrangement position of the surrounding member Driving means for changing the heating means, and when the heating means is in a heated state, the driving means arranges the enclosure member at a position that does not hinder the heating function of the heating means, and the heating means is not heated. When in a state The enclosure member is a fixing device, characterized in that said fixing belt surrounds said heating means is disposed at a position spaced apart from the heating means when deformed by an external force.

  According to a second aspect of the present invention, in the fixing device according to the first aspect, the reflecting plate includes a plurality of reflecting members, and at least a part of the reflecting members among the plurality of reflecting members is the enclosure member. It is characterized by being driven by driving means.

  According to a third aspect of the present invention, in the fixing device according to the second aspect, the driving unit rotationally drives the reflecting member about a rotation axis disposed along a longitudinal direction of the fixing belt. To do.

  According to a fourth aspect of the present invention, in the fixing device according to the first aspect, the enclosing member is configured as a separate member from the reflecting plate, and the driving means moves the enclosing member along the longitudinal direction of the fixing belt. The position that does not hinder the heating function is set in an area outside the fixing belt, and the position apart from the heating means when deformed by the external force is inside the fixing belt. In this case, the region is set between the heating unit and the fixing member.

  According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fourth aspects, a portion of the enclosure member that contacts the fixing belt has a smooth surface shape that does not damage the fixing belt. It is characterized by providing.

  A sixth aspect of the present invention is an image forming apparatus comprising the fixing device according to any one of the first to fifth aspects.

  According to the present invention, when the heating means is in the non-heated state, the surrounding member is disposed at the contact prevention position surrounding the heating means, so that even if the finger of the operator touches the fixing device such as when the jam is resolved, the finger is fixed. The heating means is not contacted via the belt, the operator can be prevented from contacting a high temperature member, and safety can be ensured.

1 is a cross-sectional view illustrating a configuration of an image forming apparatus according to an embodiment. 1 is a cross-sectional view illustrating a configuration of a fixing device according to an embodiment. FIG. 3 is a schematic diagram illustrating an operation of a reflecting plate in the fixing device illustrated in FIG. 2. FIG. 3 is a schematic diagram illustrating an operation of the fixing device illustrated in FIG. 2. FIG. 3 is a schematic diagram illustrating a state where a finger is brought into contact with the fixing device illustrated in FIG. 2. FIG. 10 is a schematic diagram illustrating a configuration and an operation of a fixing device according to a second example. FIG. 10 is a schematic diagram illustrating a configuration and an operation of a fixing device according to a third example. It is a schematic diagram showing a conventional fixing device using a fixing roller. It is a schematic diagram showing a conventional fixing device using a fixing belt. It is a schematic diagram showing a conventional fixing device in which a heating roller is omitted.

  The fixing device according to the embodiment includes an endless fixing belt having flexibility, a pressure member disposed inside the fixing belt, and a pressure member that is in pressure contact with the pressure member via the fixing belt. A pressure roller that forms a nip portion with the belt, a heating unit that is disposed inside the fixing belt and heats the fixing belt, and a reflector that is disposed between the heating member and the pressure member. Is provided. Then, a recording medium carrying an unfixed toner image is passed through the nip portion and fixed. The fixing device includes an enclosing member that can move to a position that surrounds the heating unit within the fixing belt, and a driving unit that changes an arrangement position of the enclosing member. When the heating unit is in a heated state, the driving unit arranges the surrounding member at a position that does not hinder the function of the heating unit. Further, when the heating means is in a non-heated state, the enclosing member is disposed at a position separated from the heating means when the fixing belt is deformed by an external force surrounding the heating means. As a result, even if the fixing belt is deformed by an external force, the fixing belt is kept away from the heating unit, and the operator's finger or the like comes into almost direct contact with the heating unit via the fixing belt. Prevent situations from occurring.

<Example 1>
Embodiments of the image forming apparatus according to the present invention will be described below. In the following, several embodiments of the present invention are shown and described, but it is obvious that the present invention is not limited thereto. It will be apparent to those skilled in the art that numerous modifications, changes, variations, substitutions and equivalents can be devised without departing from the spirit and scope of the invention.

  FIG. 1 is a cross-sectional view showing a configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 performs full color printing, and performs printing using yellow (Y), cyan (C), magenta (M), and black (K) toners. In the apparatus main body 101 of the image forming apparatus 100, four image forming apparatuses 110Y, 110C, 110M, and 110K corresponding to the respective colors are arranged. In each of the image forming devices 110Y, 110C, 110M, and 110K, a photoconductor 102 is disposed. Around the photoconductor 102, a charging device 103, an LED head 104 that is a light source, a developing device 105, A transfer device 106 and a cleaning device (not shown) are provided. In addition, the transfer device 106 conveys the printing paper that is a recording medium by the endless belt member 108 and superimposes the toner images formed on the charging devices 103 of the respective colors and transfers them onto the printing paper.

  The charging device 103 is a conductive member formed in a roller shape, and a charging bias voltage is supplied from the power supply device to uniformly charge the surface of the photosensitive member 102.

  The LED head 104 exposes the photosensitive member 102 with LED light. That is, the LED head 104 irradiates the surface of the photoreceptor 102 with LED light that is turned on or off based on the image data, and forms an electrostatic latent image on the photoreceptor 102.

  Each developing device 105 visualizes the electrostatic latent image formed on the correspondingly arranged photoconductor 102 with each color developer (toner). The transfer device 106 transfers the visible image on the photoconductor 102 from the photoconductor 102 to printing paper. The cleaning unit removes the developer remaining on the photosensitive member 102 after the transfer.

  When printing an image on a printing paper, the printing paper is separated one by one by a paper feeding roller 107a of a paper feeding means 107, conveyed to a registration roller 107b, and then conveyed to the transfer device 106 described above. The printing paper on which the images of the respective colors are transferred and transferred in the transfer device 106 is conveyed to the fixing device 130, the toner image is heated and pressurized and fixed, conveyed to the upper discharge roller 109, and discharged to the outside of the device. .

  Next, the fixing device 130 of the image forming apparatus 100 will be described. 2 is a cross-sectional view showing the configuration of the fixing device, FIG. 3 is a schematic diagram showing the operation of the reflecting plate in the fixing device, and FIG. 4 is a schematic diagram showing the operation of the fixing device. As shown in FIG. 2, the fixing device 130 is in contact with a fixing belt 131 that is an endless belt, a heating unit 132 that is disposed inside the fixing belt 131 and directly heats the fixing belt 131, and an inner periphery of the fixing belt 131. The pressure pad 134 is a pressure unit and the pressure roller 133 is in pressure contact with the fixing belt 131.

  Further, on the inner side of the fixing belt 131 having a cylindrical shape, a reflection plate 135 that reflects the radiant heat of the heating means 132 to the opposite side of the pressure pad 134 is provided between the heating means 132 and the pressure pad 134. . The reflecting plate 135 is composed of three divided reflecting members 135a, 135b, and 135c and has a concave surface as a whole, and also serves as an enclosing member in this embodiment as will be described later.

  The recording medium to be fixed is inserted along the sheet passing direction (arrow) from the right side in the figure, and heated by the nip portion 136 composed of the fixing belt 131 and the pressure roller 133 driven along the arrow in the figure. And pressed and fixed.

  The fixing belt 131 is a substantially cylindrical member having flexibility, and is configured as an endless belt made of a metal material such as nickel or stainless steel or a heat-resistant resin material such as polyamideimide or polyimide. In the present specification, in the above and the following, a direction along the axis of the fixing belt 131 formed in a cylindrical shape (a direction perpendicular to the paper surface of FIG. 2) is referred to as a longitudinal direction.

  The heating means 132 is composed of, for example, a halogen heater, and is disposed in the fixing belt 131 along the longitudinal direction of the fixing belt 131 to uniformly heat the fixing belt 131.

  In addition, the reflecting members 135a, 135b, and 135c that constitute the reflecting plate 135 are made of a metal or a material such as a heat insulating resin in which a metal is vapor-deposited on a reflecting surface, and each has a long cross section with an arc shape or a shape close to an arc shape. It is a member and is disposed along the longitudinal direction of the fixing belt 131 between the heating means 132 and the pressure pad 134. The reflecting member 135b disposed at the center of the three reflecting members 135a, 135b, and 135c is fixed to the heating means 132, and the reflecting members 135a and 135c disposed at both ends are configured to be movable. .

  These two reflecting members 135a and 135c are driven by a known driving means (not shown) using a motor or an electromagnetic solenoid as a driving source, and are heated when the heating means 132 is heated, that is, when the recording medium is fixed. As shown in FIG. 3A together with the reflecting member 135b, the entire surface is concave and exhibits a predetermined function of the reflecting plate 135. That is, in this state, the reflection plate 135 reflects the heat from the heating means 132 upward (in the direction opposite to the pressure pad 134), and the fixing belt 131 is heated to a state suitable for fixing.

  On the other hand, when the heating means 132 is not heated, that is, when the recording medium is not fixed, as shown in FIGS. 3B and 4, the reflecting members 135a and 135c are moved upward by the driving means (FIG. 3). (See middle arrows A and B). Then, as shown in FIG. 4, the reflecting members 135a, 135b, and 135c are in a state of surrounding the heating means 132 from three directions. In this state, the reflecting members 135 a, 135 b, and 135 c are disposed at the contact prevention position that surrounds the periphery of the heating unit 132, and prevents the finger 50 from contacting the heating unit 132. At this time, as shown in FIG. 4, the fixing belt 131 is pressed and deformed by the reflecting members 135 a and 135 b from below the inside.

  FIG. 5 is a schematic diagram for explaining a state in which an operator or the like makes his / her finger contact the fixing belt 131 in the fixing device according to the first embodiment. In the illustrated fixing device 130, when the fixing operation is performed and the heating unit 132 is in a heating state, the reflecting members 135a, 135b, and 135c are arranged at the heating position as shown in FIG. Radiant heat is reflected by the reflecting plate 135 including the reflecting members 135a, 135b, and 135c.

  On the other hand, when the finger 50 is inserted into the apparatus main body 101, such as during a jam process in which the recording medium is taken out of the apparatus with a finger, the heating unit 132 is turned off and enters a non-heated state. As the heating means 132 is turned off, the reflecting members 135a and 135c are pulled upward by the driving means (not shown) as shown in FIGS. 3B, 4 and 5C, and the heating means It arrange | positions so that the circumference | surroundings of 132 may be enclosed. In this state, the fixing belt 131 is separated from the heating unit 132 and becomes a temperature lower than a predetermined fixing temperature.

  In this state, for jam processing, an operator removes the cover of the apparatus main body 101 and inserts the finger 50 into the inside. In this embodiment, since the reflecting members 135a, 135c, 145a, and 145c are disposed around the heating means 132, the finger 50 only needs to contact the fixing belt 131 having a low temperature. Further, even if the fixing belt 131 is pushed from above or from the side by the finger 50, as shown in FIGS. 5D and 5E, the fixing belt 131 is surrounded by the reflecting members 135a, 135c, 145a, and 145c. Therefore, the fixing belt 131 does not contact or approach the heating unit 132, and the finger 50 does not contact the high-temperature heating unit 132.

  On the other hand, if the reflecting members 135a and 135c are not moved, as shown in FIG. 5B, when the finger 50 touches the fixing device 130, the fixing belt 131 is deformed and the finger 50 is fixed to the fixing belt 131. There is a risk of contact with the heating means 132 via. The fixing device 130 according to the present embodiment can prevent such a situation.

  Further, according to the fixing device 130 according to the present embodiment, since the reflecting members 135a, 135b, and 135c constituting the reflecting plate 135 also serve as an enclosing member, it is necessary to provide a separate member from the reflecting plate as the enclosing member. The number of parts can be reduced and the cost can be reduced.

<Example 2>
Next, a second embodiment will be described. In the first embodiment, the reflecting members 135a, 135c arranged at both ends of the reflecting members 135a, 135b, 135c are linearly moved upward. In contrast, in the fixing device 140 according to the second embodiment, among the reflecting members 145a, 145b, and 145c constituting the reflecting plate 145, the reflecting members 145a and 145c arranged at both ends are rotationally moved.

  FIG. 6 is a schematic diagram illustrating the configuration and operation of the fixing device according to the second embodiment. In the fixing device 140 according to the embodiment, the fixing belt 141, the heating unit 142, and the pressure pad 144 as a pressure member have the same configuration as that of the first embodiment. Further, the reflecting members 145a, 145b, and 145c constituting the reflecting plate 145 have the same configuration as the reflecting members 135a, 135b, and 135c of the first embodiment. In the fixing device 140 according to the present embodiment, the reflecting members 145a and 145c disposed at both ends are driving means (not shown) using a motor or the like as a driving source, and the axis O along the longitudinal direction of the fixing belt 141 is the center. Thus, it is rotated in the fixing belt 141 (arrows C and D in FIGS. 6A and 6C). Accordingly, the reflecting members 145a and 145c are moved upward in the drawing of the heating unit 142 by deforming the fixing belt 141. At this time, in the fixing device 140, when the reflecting members 145a and 145c are rotated and disposed at the contact prevention position, the convex surfaces of the reflecting members 145a and 145c come into contact with the inner surface of the fixing belt 141. For this reason, a local force is not applied to the fixing belt 141 or an unreasonable deformation does not occur.

  In the fixing device 140 according to the present embodiment, when the fixing operation is performed and the heating unit 142 is in the heating state, the reflecting members 145a, 145b, and 145c are disposed at the heating positions as shown in FIG. The radiant heat from the means 142 is reflected by the reflecting plate 145 constituted by the reflecting members 145a, 145b, and 145c, and efficiently heats the upper part of the fixing belt 131 (on the side opposite to the pressure pad 134).

  On the other hand, when the heating unit 142 is turned off, the reflecting members 145a and 145c are rotated upward by a driving unit (not shown) as the heating unit 142 is turned off, as shown in FIG. C, D). As a result, the reflecting members 145a, 145b, and 145c are arranged around the heating unit 142 and function as an enclosure member. In this state, the fixing belt 141 is separated from the heating unit 142 and is lower than a predetermined fixing temperature. In this state, when the jam processing is performed, even if the finger 50 touches the fixing device 140, the finger 50 only needs to come into contact with the fixing belt 141 having a low temperature. Further, as shown in FIG. 6D, even if the fixing belt 141 is pushed with the finger 50, the fixing belt 141 is prevented from being deformed by the reflecting members 145a, 145b, and 145c, and is in contact with or close to the heating unit 142. The finger 50 does not come into contact with the high-temperature heating means 142.

  On the other hand, if the reflecting members 145a and 145c are not moved, as shown in FIG. 6B, when the finger 50 touches the fixing device 140, the fixing belt 141 is deformed, and the finger 50 is fixed to the fixing belt 141. There is a risk of contact with the high-temperature heating means 132 via. In the fixing device 140 according to the present embodiment, such a situation can be prevented.

  Further, according to the present embodiment, the reflecting members 145a, 145b, and 145c constituting the reflecting plate 145 function as an enclosing member, so there is no need to provide an enclosing member as a separate member from the reflecting plate. The number of parts can be reduced and the cost can be reduced. Further, when the reflecting members 145a and 145c are arranged at the contact prevention position, the convex surfaces of the reflecting members 145a and 145c come into contact with the inner surface of the fixing belt 141, so that a local force is applied to the fixing belt 141 or the fixing belt 141 cannot be forced. It becomes difficult to cause a certain deformation.

<Example 3>
Next, a third embodiment will be described. FIG. 7 is a schematic diagram illustrating the configuration and operation of the fixing device according to the third embodiment. 7A and 7C, (I) is a front view and (II) is a side view.

  The fixing device 150 according to the present exemplary embodiment includes a fixing belt 151, a heating unit 152, a pressure pad 154 that is a pressure member, and a reflection plate 155. The fixing belt 151, the heating unit 152, and the pressure pad 154 have the same configuration as in the first embodiment. The reflector 155 is composed of a single member and is fixedly disposed in the fixing belt 151. The reflector 155 is made of a metal or an arc-shaped cross section made of a material such as a heat insulating resin having a metal deposited on the reflection surface.

  The fixing device 150 according to the present exemplary embodiment includes five cylindrical rod-shaped members 156 as enclosure members. As shown in FIG. 7A, these rod-shaped members 156 are formed slightly longer than the longitudinal dimension of the fixing belt 151, and are arranged so as to form a roof shape as a whole. The rod-shaped member 156 is moved between the heating position and the contact prevention position along the longitudinal direction of the fixing belt 141 by a driving unit (not shown) while maintaining the overall shape (arrow E in the figure). ). That is, the rod-shaped member 156 is a driving unit and is disposed at a heating position located outside the fixing belt 151 when the heating unit 152 is heated, and is inserted into the fixing belt 151 when the heating unit 152 is not heated. It is arranged at a contact prevention position surrounding the upper part of 152. In addition, as a drive means, the well-known thing provided with the motor, the electromagnetic solenoid, etc. can be used.

  In the fixing device 150 according to the present exemplary embodiment, the contact prevention position is set in a region corresponding to the nip portion through which the recording medium passes in the longitudinal direction of the fixing belt 141. The heating position is set outside the area corresponding to the nip portion through which the recording medium passes, for example, outside the opening of the fixing belt 151. The enclosing member is not limited to a rod-like member, and other shape members such as a plate-like member having an arcuate cross section can be used as long as the heating unit 152 can be covered.

  In the fixing device 150 according to the present embodiment, when the fixing operation is performed and the heating unit 152 is in the heating state, the rod-shaped member 156 extends from the inside of the fixing belt 151 to the longitudinal direction of the fixing belt 151 as shown in FIG. Extracted outward in the direction. In this state, the radiant heat from the heating unit 152 is reflected by the reflecting plate 155 and efficiently heats the fixing belt 131 at the upper part (the anti-pressure pad 154 side).

  On the other hand, when the heating unit 152 is turned off, the rod-shaped member 156 is moved in the longitudinal direction of the fixing belt 151 by the driving unit as shown in FIG. 7C, and around the upper side of the heating unit 152 in the fixing belt 151. Arranged to function as an enclosure member. In this state, the fixing belt 151 is separated from the heating unit 152 without being brought into contact with or close to the heating unit 152, and thus becomes a temperature lower than a predetermined fixing temperature. In this state, when the jam processing is performed, even if the finger 50 touches the fixing device 150, the finger 50 only needs to come into contact with the fixing belt 151 having a low temperature. Further, as shown in FIG. 7D, even when the fixing belt 151 is pushed with the finger 50, the fixing belt 151 is prevented from being deformed by the rod-shaped member 156, and does not come into contact with or close to the heating means 152. The finger 50 does not come into contact with the high temperature heating means 152.

  On the other hand, if the rod-shaped member 156 is not provided, as shown in FIG. 7B, when the finger 50 touches the fixing device 150, the fixing belt 151 is deformed and the finger 50 passes through the fixing belt 151. Thus, the heating means 152 is brought into contact. In contrast, the fixing device 150 according to the present embodiment can prevent such a situation.

  In addition, according to the present embodiment, the reflector and the enclosure member are separate members, and the enclosure member is disposed outside the fixing belt during heating, so that the enclosure member does not lose heat during heating and is fixed. The belt can be heated quickly.

<Example 4>
In the first and second embodiments, if the reflecting members 135a, 135c, 145a, and 145c are chamfered at the end portions that are in contact with the fixing belts 131 and 141, or are formed in a circular arc shape, the smooth shape is obtained. When the reflecting members 135a, 135c, 145a, 145c are driven to the contact preventing position, there is no possibility of damaging the fixing belts 131, 141. Also, as shown in FIGS. 5D, 5E, and 6D, the fixing belts 131 and 141 are damaged when the finger 50 touches the fixing belts 131 and 141 and the fixing belts 131 and 141 are deformed. Can be prevented.

<Example 5>
Similarly, in the third embodiment, a case where a round bar is used as the bar-shaped member 156 has been described as an example. However, when a member having another shape is used as the enclosing member, a member having no corner or pointed portion is used. Can be used to prevent the fixing belt 151 from being damaged.

50 Finger 100 Image forming apparatus 101 Main body 102 Photoconductor 103 Charging device 104 LED head 105 Development device 106 Transfer device 107 Paper feed means 107a Paper feed roller 107b Registration roller 108 Endless belt member 109 Paper discharge rollers 110Y, 110C, 110M, 110K Image forming device 130 Fixing device 131 Fixing belt 132 Heating means 133 Pressure roller 134 Pressure pad (pressure member)
135 Reflecting plates 135a, 135b, 135c Reflecting member (enclosure member)
136 Nip part 140 Fixing device 141 Fixing belt 142 Heating means 144 Pressure pad (pressure member)
145 Reflector 145a, 145b, 145c Reflective member (enclosure member)
150 Fixing Device 151 Fixing Belt 152 Heating Unit 154 Pressure Pad (Pressure Member)
155 Reflector 156 Bar-shaped member (enclosure member)

Japanese Patent No. 4320234 Japanese Patent No. 4130898 JP 2009-198732 A

Claims (6)

A flexible endless fixing belt, a pressure member disposed inside the fixing belt, a pressure member that is pressed against the pressure member via the fixing belt, and a nip portion between the fixing belt and the fixing belt. A pressure roller to be formed; heating means disposed inside the fixing belt for heating the fixing belt; and a reflector disposed between the heating member and the pressure member; In a fixing device for fixing by passing a recording medium carrying a toner image,
A surrounding member movable to a position surrounding the heating means inside the fixing belt;
Drive means for changing the position of the enclosure member;
With
The driving means includes
When the heating means is in a heated state, the surrounding member is disposed at a position that does not hinder the heating function of the heating means,
When the heating unit is in a non-heated state, the enclosing member is disposed at a position separated from the heating unit when the fixing belt is deformed by an external force surrounding the heating unit. . The reflecting plate is composed of a plurality of reflecting members,
The fixing device according to claim 1, wherein at least some of the plurality of reflecting members are driven by the driving unit as the enclosure member.   The fixing device according to claim 2, wherein the driving unit rotationally drives the reflecting member about a rotation axis disposed along a longitudinal direction of the fixing belt. The enclosure member is configured as a separate member from the reflector,
The drive means moves the enclosure member along the longitudinal direction of the fixing belt,
The position that does not hinder the heating function of the heating means is set in a region outside the fixing belt,
The fixing device according to claim 1, wherein the position spaced apart from the heating unit is set in an area between the heating unit and the fixing member inside the fixing belt.   5. The fixing device according to claim 1, wherein a portion of the surrounding member that contacts the fixing belt has a smooth surface shape that does not damage the fixing belt. 6. An image forming apparatus comprising the fixing device according to claim 1.