JP2016194732A - Structure of fixing part and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a configuration in which means to convey and a member to guide a recording medium are provided on the upstream side of fixing means in a direction of conveyance of the recording medium and a fixing member projects to a side of the conveyance means, and suppress a difference in temperature in a width direction of the recording medium.SOLUTION: A structure 100 of a fixing part comprises a conveyance part 80, a guide member 125, a fixing device 110 that includes a fixing belt 112 projecting to a side of conveyance belts 81A and 81B, and a heat shielding member 123 that is provided on the upstream side of the guide member 125 in a direction of conveyance of a recording sheet P. Since a heat moving from the fixing belt 112 to the conveyance part 80 is shielded by the heat shielding member 123, an increase in temperature of the conveyance belts 81A and 81B having a narrower width than that of the recording sheet P is suppressed. Since the guide member 125 heats the recording sheet P substantially uniformly in the width direction, a difference in temperature in the width direction of the recording sheet P can be suppressed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a structure of a fixing unit and an image forming apparatus.

  The image forming apparatus disclosed in Patent Document 1 includes a relay conveyance unit that includes a conveyance belt that is shorter than the width of the transfer paper and conveys the transfer paper from the transfer unit toward the fixing inlet guide plate of the fixing unit. In the image forming apparatus of Patent Document 1, the end portion of the fixing entrance guide plate on the relay conveyance unit side is formed in a concave shape so that the portion facing the conveyance belt is recessed toward the fixing unit than the portion not facing the conveyance belt. ing.

JP 2011-246224 A

  The present invention provides a recording medium conveying means and a guide member upstream of the fixing means in the recording medium conveying direction, and the fixing member protrudes to the conveying means side, and the temperature difference in the width direction of the recording medium is reduced. It is an object of the present invention to obtain a fixing unit structure and an image forming apparatus that can be suppressed.

  The structure of the fixing unit according to claim 1 of the present invention is such that the width of contact with the recording medium in the width direction intersecting with the conveyance direction of the recording medium is narrower than the width of the recording medium, and conveying means for conveying the recording medium; A width in the width direction equal to or greater than the width of the recording medium, a guide member for guiding the recording medium conveyed by the conveying means to the downstream side in the conveying direction, and an endlessly formed at least part of the recording medium when viewed in the vertical direction Fixing member that has a fixing member that can be moved around so as to overlap with the conveying unit, and a heating unit that heats the fixing member, and that fixes the developer on the recording medium guided by the guiding member to the recording medium. And a heat shield means provided on the upstream side of the guide member in the transport direction and shields heat between the fixing member and the transport means.

  In the structure of the fixing unit according to claim 2 of the present invention, the heat shield means includes a heat insulating member, and the heat insulating member is disposed between the transport means and the guide member in the transport direction and the width direction. And an extending portion that extends in a direction intersecting with.

  According to a third aspect of the present invention, there is provided an auxiliary heating means for heating the guide member.

  According to a fixing unit structure of a fourth aspect of the present invention, the fixing member is in contact with the heating unit between the heating unit and the conveying unit, and the conveying unit is in contact with the recording medium to record the recording medium. The heat shield means shields heat between the transport section and a portion where the fixing member and the heating means are in contact with each other.

  According to a fifth aspect of the present invention, there is provided a developer image forming unit for forming a developer image on a recording medium, and a developer image formed by the developer image forming unit on a recording medium by the fixing unit. The fixing portion structure according to any one of claims 1 to 4, wherein the fixing portion is fixed.

  According to a first aspect of the present invention, there is provided a recording medium conveyance unit and a guide member provided upstream of the fixing unit in the recording medium conveyance direction, and the fixing member projects to the conveyance unit side. The temperature difference in the width direction of the recording medium can be suppressed as compared with the configuration in which no heat shield means is provided between them.

  According to the second aspect of the present invention, the temperature of the guide member can be increased in a short time compared to a configuration in which a heat insulating member having an extending portion between the conveying means and the guide member is not provided.

  According to the invention of claim 3, the temperature of the guide member can be raised in a short time as compared with the configuration in which the auxiliary heating means is not provided.

  According to the fourth aspect of the present invention, the temperature difference in the width direction of the recording medium can be further suppressed as compared with the case where this configuration is not provided.

  According to the fifth aspect of the present invention, as compared with a configuration having a fixing device in which no heat shield means is provided between the fixing member and the conveying means, the deterioration in image quality due to the temperature difference in the width direction of the recording medium is suppressed. Can do.

1 is an overall configuration diagram of an image forming apparatus according to a first embodiment. FIG. 2 is a configuration diagram of an image forming unit according to the first embodiment. FIG. 2 is a configuration diagram of a structure of a fixing unit according to the first embodiment. FIG. 3 is a schematic diagram in plan view from the conveyance belt to the nip portion of the fixing device according to the first embodiment. It is a schematic diagram which shows the heat insulation state of the radiant heat by the cover member which concerns on 1st Embodiment. FIG. 4A is a schematic diagram illustrating a temperature distribution in the width direction of a recording sheet in the fixing device according to the first embodiment. FIG. 6B is a schematic diagram illustrating a temperature distribution in the width direction of the recording paper in a comparative example. It is a schematic diagram which shows the thermal insulation state of the radiant heat by the cover member in the structure of the fixing part which concerns on 2nd Embodiment. It is a schematic diagram which shows the heat shielding state of the radiant heat by the cover member in the structure of the fixing unit according to the third embodiment and the heating state of the guide member.

[First embodiment]
An example of the structure of the fixing unit and the image forming apparatus according to the first embodiment will be described.

(overall structure)
FIG. 1 shows an image forming apparatus 10 as an example of the first embodiment. The image forming apparatus 10 includes a sheet storage unit 12, a main operation unit 14 that is provided on the sheet storage unit 12 and performs image formation, and a main operation unit 14. And a document reading unit 16 provided on the top. In addition, the image forming apparatus 10 includes an apparatus main body 15 that includes a member including a plurality of frames and plate materials. The main operation unit 14 is provided with a control unit 20 that controls the operation of each unit of the image forming apparatus 10.

  In the figure, "X" in the circle means an arrow heading from the front to the back, and "." In "○" in the figure is from the back. This means an arrow pointing toward you. Further, when the image forming apparatus 10 is viewed from the side where a user (not shown) stands, the X direction is the right direction, the -X direction is the left direction, the Y direction is the upward direction, the -Y direction is the downward direction, and the Z direction is the The depth direction and the −Z direction correspond to the front direction. When distinguishing one side from the other side, it may be described as X side, -X side, Y side, -Y side, Z side, -Z side.

(Paper compartment)
The paper storage unit 12 includes a first storage unit 22, a second storage unit 24, a third storage unit 26, and a fourth storage unit 28 that can store recording paper P as an example of recording media having different sizes. Yes. The first storage unit 22, the second storage unit 24, the third storage unit 26, and the fourth storage unit 28 include a feed roll 32, a transport roll 34, and a sensor that acquires size information of the recording paper P (not shown). ) And are provided. The delivery roll 32 delivers the recording paper P stored in each storage unit one by one. The transport roll 34 transports the recording paper P fed by the feed roll 32 to a transport path 30 provided in the image forming apparatus 10.

  A plurality of transport rolls 36 that transport the recording paper P one by one are provided on the downstream side of the transport roll 34 in the transport path 30. Further, the recording paper P is stopped at one end downstream of the transport roll 36 in the transport direction of the recording paper P in the transport path 30 and sent to a secondary transfer position described later at a predetermined timing. An alignment roll 38 for performing alignment is provided.

  The upstream portion of the conveyance path 30 is provided in a straight line from the −X side of the sheet storage unit 12 to the −X side lower portion of the main operation unit 14 in the arrow Y direction in the front view of the image forming apparatus 10. . Further, the downstream portion of the transport path 30 is provided from the −X side lower part of the main operation unit 14 to the paper discharge unit 13 provided on the X side surface of the main operation unit 14. Further, a double-sided conveyance path 31 through which the recording paper P is conveyed and reversed in order to form an image on both sides of the recording paper P is connected to the conveyance path 30. The conveyance direction of the recording paper P when the double-sided conveyance is not performed is indicated by an arrow A.

  The double-sided conveyance path 31 includes a reversing unit 33 that reverses the recording paper P and a conveyance unit 35 that conveys the reversed recording paper P when the image forming apparatus 10 is viewed from the front. Specifically, the reversing unit 33 is linearly provided in the Y direction from the lower X side of the main operating unit 14 to the X side of the paper storage unit 12. The transport unit 35 transports the recording paper P toward the −X side (shown by an arrow B) as shown in FIG.

  The downstream end of the transport unit 35 is connected to the upstream side of the alignment roll 38 of the transport path 30 by a guide member (not shown). In FIG. 1, a plurality of transport rolls are provided at intervals in the reversing unit 33 and the transport unit 35, but the illustration is omitted. Further, a switching member that switches between the conveyance path 30 and the double-sided conveyance path 31 and a switching member that switches between the reversing unit 33 and the conveyance unit 35 are also omitted in the drawing.

(Original reading section)
The document reading unit 16 has a document table 41 on which a plurality of documents (not shown) can be placed, a platen glass 42 on which a single document is placed, and a document reading device 44 that reads a document placed on the platen glass 42. And a document discharge portion 43 for discharging the read document.

  The document reading device 44 includes a light irradiation unit 46, one full-rate mirror 48 and two half-rate mirrors 52, an imaging lens 54, and a photoelectric conversion element 56. The light irradiating unit 46 irradiates the document placed on the platen glass 42 with light. The full-rate mirror 48 and the half-rate mirror 52 reflect the reflected light irradiated from the light irradiation unit 46 and reflected from the document in a direction parallel to the platen glass 42 to be folded. Specifically, the full rate mirror 48 moves at the full rate along the platen glass 42, and the half rate mirror 52 moves at the half rate along the platen glass 42.

  Reflected light reflected by the full-rate mirror 48 and the half-rate mirror 52 is incident on the imaging lens 54. The photoelectric conversion element 56 converts the reflected light imaged by the imaging lens 54 into an electric signal. The electrical signal converted by the photoelectric conversion element 56 is subjected to image processing by an image processing apparatus (not shown) and used for image formation.

(Main operation part)
The main operation unit 14 includes an image forming unit 60 as an example of a developer image forming unit that forms a toner image (developer image) on the recording paper P in the apparatus main body 15 and a developer image on the recording paper P. And a fixing device 110 as an example of a fixing unit that fixes the toner. The fixing device 110 is attached to the apparatus main body 15 or can be pulled out from the apparatus main body 15.

  The image forming unit 60 includes photosensitive members 62K, 62C, 62M provided corresponding to toners of yellow (Y), magenta (M), cyan (C), and black (K) as an example of a developer. The image forming units 64K, 64C, 64M, and 64Y having 62Y are included. In addition, the image forming unit 60 includes exposure units 66K, 66C, 66M, and 66Y that emit light beams L toward the outer peripheral surfaces of the photoreceptors 62K, 62C, 62M, and 62Y and perform exposure.

  Further, the image forming unit 60 includes a transfer unit 68 that transfers the toner images formed by the image forming units 64K, 64C, 64M, and 64Y onto the recording paper P. In the following description, if it is necessary to distinguish Y, M, C, and K, an alphabetic letter Y, M, C, or K will be added after the numeral, and the same configuration will be used. , M, C, and K need not be distinguished from each other, description of Y, M, C, and K is omitted.

  The exposure unit 66 scans a light beam emitted from a light source (not shown) with a rotating polygon mirror (polygon mirror: no symbol) and reflects it with a plurality of optical components including a reflection mirror to correspond to each toner. The light beam L is emitted toward the photoconductor 62. The photoconductor 62 is provided on the −Y side (lower side) of the exposure unit 66.

  As shown in FIG. 2, the image forming unit 64 includes a photoconductor 62, a charger 72, a developer 74, and a charger 72 arranged in order from the upstream side to the downstream side in the rotation direction so as to face the outer peripheral surface of the photoconductor 62. And a cleaning unit 76. The charger 72 and the developing device 74 are irradiated with the light beam L from the exposure unit 66 (see FIG. 1) at a position between the charger 72 and the developing device 74 on the outer peripheral surface of the photosensitive member 62. Has been placed. An intermediate transfer belt 82 described later is in contact with a position between the developing device 74 and the cleaning unit 76 on the outer peripheral surface of the photosensitive member 62.

  The photosensitive member 62 is made of aluminum or the like and has a conductive and grounded cylindrical base material (not shown), and a charge generation layer and a charge transport layer sequentially stacked in the radial direction on the outer peripheral surface of the base material. And a surface layer (not shown) including a protective layer. The photosensitive member 62 can be rotated in the arrow + R direction by driving a motor (not shown).

  As an example, the charger 72 includes a corotron charging unit that applies a voltage to the wire and charges the outer peripheral surface of the photosensitive member 62 to the same polarity as the toner by corona discharge. Here, a latent image (electrostatic latent image) is formed by irradiating the outer peripheral surface of the charged photoconductor 62 with the light beam L based on the image data.

  As an example, the developing device 74 contains a developer G in which carrier particles made of a magnetic material and toner are mixed. For example, the toner includes a resin that is negatively charged. The developing device 74 is provided with a cylindrical developing sleeve 75 in which a magnet roll (not shown) having a plurality of magnetic poles in the circumferential direction is provided inside.

  In the developing device 74, a magnetic brush is formed at a portion facing the photoconductor 62 as the developing sleeve 75 rotates. In the developing device 74, a developing bias is applied to the developing sleeve 75 by a voltage applying means (not shown), whereby the latent image on the outer peripheral surface of the photosensitive member 62 is made visible with toner, and a toner image (developer image). Example). Each developing device 74 is supplied with toner from each toner cartridge 79 (see FIG. 1) provided above the image forming unit 60.

  The cleaning unit 76 has a cleaning blade 77 that is disposed with the front end facing in the rotational direction of the photoconductor 62 and that contacts the outer peripheral surface of the photoconductor 62. The cleaning unit 76 is configured to scrape and collect the residual toner remaining on the outer peripheral surface of the photosensitive member 62 with a cleaning blade 77. Further, an intermediate transfer belt 82 on which the toner image developed by the developing device 74 is primarily transferred is provided downstream of the developing device 74 in the rotation direction of the photosensitive member 62 so as to be movable in the direction of arrow C.

  As shown in FIG. 1, the transfer unit 68 includes an intermediate transfer belt 82 and a primary transfer roll 84 that primarily transfers a toner image from the photosensitive member 62 onto the intermediate transfer belt 82. Further, the transfer unit 68 faces the secondary transfer roll 86 via the intermediate transfer belt 82 and a secondary transfer roll 86 that secondarily transfers the toner images sequentially stacked on the intermediate transfer belt 82 onto the recording paper P. An auxiliary roll 88 is included.

  As an example, the intermediate transfer belt 82 is formed of a film-like endless belt in which carbon black (antistatic agent) is contained in a resin made of polyimide or polyamide. Further, inside the intermediate transfer belt 82, a drive roll 92 that is disposed near the image forming unit 64Y and the primary transfer roll 84Y and is driven to rotate by a motor (not shown), and a plurality of conveyance units that are rotatably provided. A roll 94 is disposed.

  Further, the intermediate transfer belt 82 is wound around primary transfer rolls 84K, 84C, 84M, and 84Y, a drive roll 92, a transport roll 94, and an auxiliary roll 88. As a result, the intermediate transfer belt 82 rotates in the direction of arrow C (counterclockwise direction in the figure) when the drive roll 92 rotates counterclockwise in the figure.

  As an example, the primary transfer roll 84 has a structure in which a sponge layer (not shown) is formed around a cylindrical shaft made of a metal such as stainless steel, and both end portions of the shaft (shaft portion) are formed. It is rotatable by being supported by a bearing. Further, the primary transfer roll 84 is configured such that a voltage having a polarity opposite to the polarity of the toner is applied to the shaft from a power source (not shown).

  As an example, the secondary transfer roll 86 has the same configuration as the primary transfer roll 84, and is disposed downstream of the alignment roll 38 in the transport path 30 and is rotatably provided. Further, the secondary transfer roll 86 is in contact with the outer peripheral surface of the intermediate transfer belt 82 so as to sandwich the intermediate transfer belt 82 with the auxiliary roll 88. In the present embodiment, as an example, the secondary transfer roll 86 is grounded.

  The auxiliary roll 88 forms a counter electrode of the secondary transfer roll 86, and a secondary transfer voltage is applied via a metal power supply roll (not shown) disposed in contact with the outer peripheral surface of the auxiliary roll 88. It has become so. Here, when the secondary transfer voltage is applied and a potential difference is generated between the auxiliary roll 88 and the secondary transfer roll 86, the recording paper conveyed to the contact portion between the secondary transfer roll 86 and the intermediate transfer belt 82. The toner image on the intermediate transfer belt 82 is secondarily transferred onto P.

  A cleaning blade 95 that removes residual toner and paper dust on the intermediate transfer belt 82 after the secondary transfer is provided near the drive roll 92 at a position facing the outer peripheral surface of the intermediate transfer belt 82. As an example, a seal member (not shown) that reflects light is fixed at the reference position of the non-transfer area where the toner image is not transferred on the outer peripheral surface of the intermediate transfer belt 82. Further, the reference position of the intermediate transfer belt 82 is detected by irradiating the non-transfer area of the intermediate transfer belt 82 with light at a position where it can face the seal member and receiving the light reflected by the seal member. A position sensor (not shown) is provided. Thereby, in the image forming unit 60, the image forming operation of each unit is performed based on the signal of the reference position obtained by the position sensor.

  On the downstream side of the secondary transfer roll 86 in the moving direction of the recording paper P, a transport unit 80 is provided as an example of a transport unit that transports the recording paper P on which the secondary transfer of the toner image has been completed to the fixing device 110. ing. Here, as shown in FIG. 3, a fixing unit structure 100 as an example of the first embodiment is formed by a conveyance unit 80, a guide member 125 described later, a fixing device 110, and a heat shield member 123 described later. It is configured.

(Main part configuration)
Next, an example of the fixing unit structure 100 and the fixing device 110 will be described.

<Transport section>
As shown in FIGS. 3 and 4, the transport unit 80 includes transport belts 81 </ b> A and 81 </ b> B as examples of transport members, support rolls 83 </ b> A and 83 </ b> B and drive rolls 85 </ b> A and 85 </ b> B around which the transport belts 81 </ b> A and 81 </ b> B are wound. And an intake portion 90 that intakes air inside the conveyor belts 81A and 81B.

  The support rolls 83 </ b> A and 83 </ b> B are cylindrical members having the Z direction as an axial direction, and are arranged at an interval in the Z direction on the −X side from the intake portion 90. The support rolls 83A and 83B are attached to a common (one) rotation shaft 87 whose axial direction is the Z direction, and the rotation shaft 87 is supported by a frame bearing member (not shown). , Can be rotated.

  The driving rolls 85 </ b> A and 85 </ b> B are cylindrical members having the Z direction as an axial direction, and are arranged at an interval in the Z direction on the X side from the intake portion 90. The drive rolls 85A and 85B are attached to a common (one) rotary shaft 89 whose axial direction is the Z direction, and the rotary shaft 89 is supported by a frame bearing member (not shown). It is rotated by being driven by a motor (not shown).

  The support roll 83A and the drive roll 85A are arranged with the air intake portion 90 sandwiched in the conveyance direction of the recording paper P (hereinafter also referred to as the A direction), and the support roll 83B and the drive roll 85B are inhaled in the A direction. The portions 90 are arranged to face each other. The -X side is the upstream side in the A direction, and the X side is the downstream side in the A direction.

  As an example, the conveyance belt 81A is made of an endless silicon rubber belt material, and has a plurality of through holes 91 penetrating from the inside to the outside. The conveyor belt 81A is wound around the support roll 83A and the drive roll 85A. A conveyance belt 81A and a conveyance belt 81B, which will be described later, are separated from the recording sheet P by a linear portion LA as an example of a conveyance portion that contacts the recording paper P and conveys the recording paper P, and are more in the conveyance direction than the linear portion LA. It has a configuration including a delivery unit LB that delivers the recording paper P to the downstream side.

  As an example, the delivery unit LB is a portion wound around drive rolls 85A and 85B in the transport belt 81A and a transport belt 81B described later. Since the conveyance unit is a part that contacts the recording paper P, the conveyance unit is not limited to the linear part LA that is linear when viewed in the XY cross section, and may include a part of the part wound around the drive rolls 85A and 85B. Good.

  Similarly, the conveyance belt 81B is made of an endless silicon rubber belt material as an example, and has a plurality of through holes 91 penetrating from the inside to the outside. The conveyance belt 81A and the conveyance belt 81B have the same size and shape. The conveyor belt 81B is wound around the support roll 83B and the drive roll 85B. As a result, the transport belts 81A and 81B can be moved around so as to transport the recording paper P to the fixing device 110 by the rotational shaft 89 being driven to rotate.

(Intake section)
As shown in FIG. 4, the intake section 90 includes a duct 96 inserted along the Z direction inside the conveyor belts 81 </ b> A and 81 </ b> B, and an intake fan 97 that sucks air from inside the duct 96. The duct 96 is formed in a rectangular tube shape, and a plurality of through holes (not shown) are formed on the Y-side surface (ceiling surface), and the inside of the duct 96 is connected to the outside. Further, the −Z side of the duct 96 is closed, and a part of the Z side is opened. In addition, an intake fan 97 is disposed in the opened portion of the duct 96.

  When the intake fan 97 is rotationally driven by a motor (not shown), the inside of the duct 96 is in a negative pressure state, and is sucked through the through holes of the duct 96 and the plurality of through holes 91 of the conveying belts 81A and 81B, and the recording paper P is attracted onto the conveyor belts 81A and 81B.

  As shown in FIG. 1, in the image forming apparatus 10, a rail-shaped guide member (not shown) is provided on the lower side in the X direction of the conveyor belts 81A and 81B. It can be pulled out (to the near side). Then, the fixing device 110 is mounted on the apparatus main body 15 by being placed on the drawn-out guide member and being pushed into the illustrated Z side (back side). Further, when the fixing device 110 is taken out from the apparatus main body 15, it can be taken out by moving the fixing device 110 in the Y direction after the guide member and the fixing device 110 are pulled out to the front side in the figure.

<Fixing device>
As shown in FIG. 3, the fixing device 110 records an endless fixing belt 112 as an example of a fixing member, a heating unit 114 as an example of a heating unit that heats the fixing belt 112, and recording toward the fixing belt 112. And a pressure roll 116 that pressurizes the paper P. The fixing device 110 includes an upper cover member 122, a lower cover member 124, and a guide member 125 as an example of a guide member. A heat shield member 123 as an example of a heat shield means and a heat insulation member is attached to the upper cover member 122.

  The upper cover member 122 and the lower cover member 124 are arranged at an interval in the Y direction. Between the end portion on the −Y side of the upper cover member 122 and the end portion on the Y side of the lower cover member 124, The recording paper P can pass in the X direction. Further, the upper cover member 122 and the lower cover member 124 cover the fixing belt 112, the heating unit 114, and the pressure roll 116. In FIG. 3, hatching in the drawing is omitted for easy understanding of each member.

(Fixing belt)
As an example, the fixing belt 112 has a configuration in which a surface of a base material made of polyamide is coated with a fluororesin, and has an annular shape (endless shape) that opens in the Z direction. The fixing belt 112 is set in a posture determined by being wound around the pad member 115, the first heating roll 117, and the second heating roll 118, and maintains the posture (on the orbit along the posture). 3) Move around in the direction of arrow R shown in FIG.

  Specifically, the fixing belt 112 is wound around the pad member 115, the first heating roll 117, and the second heating roll 118, and the XY cross section has an obtuse angle at the nip portion N. It has an inverted triangular shape. The fixing belt 112 is in contact with the second heating roll 118 between the second heating roll 118 and the conveying belts 81A and 81B. As a result, a portion from the portion wound around the second heating roll 118 to the nip portion N in the moving direction (R direction) of the fixing belt 112 projects to the upper side on the X side of the conveying belts 81A and 81B. That is, at least a part of the fixing belt 112 can be moved around so as to overlap the conveying belts 81A and 81B when viewed in the Y direction (vertical direction).

(Pad member)
The pad member 115 is fixed to the main body (not shown) of the fixing device 110 inside the fixing belt 112 so that the fixing belt 112 contacts and slides on the −Y side surface (lower surface) of the pad member 115. Yes. The pad member 115 receives a pressing (nip) load from the pressure roll 116, thereby forming a nip portion N between the fixing belt 112 and the pressure roll 116.

(First heating roll)
The first heating roll 117 is disposed on the downstream side of the pad member 115 in the circumferential direction (R direction) of the fixing belt 112. Specifically, the first heating roll 117 is supported on the X side and the Y side from the pad member 115 so as to be rotatable about the Z direction as an axial direction. The first heating roll 117 is formed in a cylindrical shape, and a halogen heater 114A described later is provided inside. In the present embodiment, as an example, the first heating roll 117 is rotationally driven by a motor (not shown).

(Second heating roll)
The second heating roll 118 is disposed downstream of the first heating roll 117 in the circumferential direction (R direction) of the fixing belt 112. Specifically, the second heating roll 118 is supported rotatably on the −X side and the Y side of the pad member 115 with the Z direction as the axial direction. The second heating roll 118 is formed in a cylindrical shape, and a halogen heater 114B described later is provided inside. In the present embodiment, as an example, the height position of the second heating roll 118 in the Y direction is set lower than the height position of the first heating roll 117 in the Y direction. The first heating roll 117 and the second heating roll 118 are examples of heating means (included in an example).

(Heating section)
As an example, the heating unit 114 includes a halogen heater 114 </ b> A inserted inside the first heating roll 117 and a halogen heater 114 </ b> B inserted inside the second heating roll 118. The halogen heaters 114A and 114B generate heat when energized from a power source (not shown). Note that a heating source may be provided in the pad member 115 to serve as a heating unit.

(Temperature sensor)
A temperature sensor 119 for detecting the temperature of the outer peripheral surface of the second heating roll 118 is provided at a position close to the second heating roll 118 inside the fixing belt 112. The temperature detected by the temperature sensor 119 is converted into the surface temperature of the fixing belt 112 in the control unit 20 (see FIG. 1). Then, the control unit 20 determines whether the converted temperature of the fixing belt 112 is lower than the set temperature or higher than the set temperature. When the temperature is low, the halogen heaters 114A and 114B are turned on. 114A and 114B are turned OFF.

(Pressure roll)
As an example, the pressure roll 116 is configured by covering the outer periphery of an aluminum cylindrical roll body (not shown) with an elastic layer made of silicon rubber. A release layer made of fluorine resin or the like is formed on the outer peripheral surface of the elastic body layer. Note that the pressure roll 116 is driven to rotate as the fixing belt 112 is rotated by the rotation of the first heating roll 117. The fixing belt 112 and the pressure roll 116 move in the same direction at the nip portion N.

(Upper cover member)
The upper cover member 122 has a first side wall 122A, a ceiling wall 122B, and a second side wall 122C in order from the entry side to the discharge side of the recording paper P when viewed in the XY plane, and is in the Z direction. A pair of side walls (not shown) are provided on both sides.

  The first side wall 122A extends along the Y direction on the recording paper P entry side, and the ceiling wall 122B extends from the Y side end (upper end) of the first side wall 122A to the X side. The ceiling wall 122B is bent so that the −X side is lowered to the −Y side at the center in the X direction. The second side wall 122C extends in the Y direction from the X side end of the ceiling wall 122B to the -Y side.

(Lower cover member)
The lower cover member 124 has a first side wall 124A, a bottom wall 124B, and a second side wall 124C in order from the entry side to the discharge side of the recording paper P as viewed in the XY plane, and is in the Z direction. A pair of side walls (not shown) are provided on both sides. The first side wall 124A extends along the Y direction on the entry side of the recording paper P, and the bottom wall 124B extends from the −Y side end (lower end) of the first side wall 124A to the X side. The second side wall 124C stands upright along the Y direction at the X-side end of the bottom wall 124B.

(Guide member)
On the −X side of the nip portion N (the entry side of the recording paper P to the nip portion N), on the X side of the conveyance belts 81A and 81B on the X side (X side of the straight line K), the conveyance belt. A guide member 125 for guiding the recording paper P conveyed by 81A and 81B to the nip portion N is provided.

  As an example, the guide member 125 is made of an iron-based rectangular metal plate (plate material). The guide member 125 is attached to the Y side end (upper end) of the second side wall 124C with the direction along the conveyance direction of the recording paper P as the short direction. The guide member 125 may be made of a resin plate material.

  On the other hand, on the X side of the nip portion N (the discharge side of the recording paper P from the nip portion N), a guide member 126 that guides the recording paper P conveyed by the fixing belt 112 to the outside (X side) of the fixing device 110. Is provided. For example, the guide member 126 is formed of a rectangular resin plate, and a direction along the conveyance direction of the recording paper P is a short direction, and the Y side end portion (upper end portion) of the first side wall 124A. It is attached.

  As a result, in the fixing device 110, the recording paper P conveyed by the conveying unit 80 (the toner image T is not fixed) is guided by the guide member 125 and enters the nip N on the downstream side in the conveying direction. It has become. Then, the recording paper P on which the toner image T is fixed is guided by the guide member 126 and discharged to the outside of the fixing device 110.

<Heat shield member>
For example, PET (polyethylene terephthalate) containing glass is used for the heat shield member 123. Further, the heat shield member 123 is disposed obliquely downward from the vicinity of the −Y side end (lower end) of the first side wall 122A along the moving direction of the fixing belt 112 so that the X side is lowered to the −Y side. The upper cover member 122 is attached via a bracket (not shown).

  Further, the end portion (lower end portion) on the −Y side of the heat shield member 123 is from a straight line K (indicated by a one-dot chain line) drawn in the Y direction (vertical direction) between the conveyor belts 81A and 81B and the guide member 125. Is also located on the -X side. That is, the heat shield member 123 is provided on the upstream side of the guide member 125 in the conveyance direction of the recording paper P, and does not extend to above the guide member 125.

  Here, the first side wall 122 </ b> A and the heat shielding member 123 are surrounded by the ceiling wall 122 </ b> B, the first side wall 122 </ b> A, and the heat shielding member 123 so that the portion wound around the second heating roll 118 of the fixing belt 112 is surrounded. Has been placed. That is, the first side wall 122A and the heat shield member 123 are arranged so as to cover the portion of the fixing belt 112 that protrudes toward the conveyance belts 81A and 81B. The first side wall 122A and the heat shield member 123 overlap with the X-side portions of the transport belts 81A and 81B (as an example, the range where the drive rolls 85A and 85B are disposed) as viewed in the Y direction.

(Arrangement of each member in the width direction)
As shown in FIG. 4, when the conveyance belts 81 </ b> A and 81 </ b> B and the guide member 125 are viewed in the Y direction (from the Y side to the −Y side), the width direction orthogonal to the A direction that is the conveyance direction of the recording paper P is Z It shall be along the direction. Here, positions A, B, C, D, E, F, G, H, and I are set in order from the Z side to the −Z side along the Z direction.

  The guide member 125 has one end in the Z direction disposed at the position A and the other end in the Z direction disposed at the position I. The recording paper P has one end in the Z direction disposed at the position B and the other end in the Z direction disposed at the position H. The transport belt 81A has one end in the Z direction disposed at the position C and the other end in the Z direction disposed at the position D. The conveyance belt 81B has one end in the Z direction disposed at the position F and the other end in the Z direction disposed at the position G. The position E is the center position of the recording paper P in the Z direction, and is between the transport belt 81A and the transport belt 81B. In the present embodiment, the width of the recording paper P in the Z direction means the width of the maximum size recording paper P to be conveyed.

  As described above, in the fixing unit structure 100, the width of the guide member 125 in the Z direction (section AI) is wider than the maximum width of the recording paper P in the Z direction (section BH). The total width of the width in the Z direction (section CD) of the conveyance belt 81A and the width in the Z direction (section FG) of the conveyance belt 81B is the maximum width in the Z direction of the recording paper P (section B). It is narrower than -H).

(Comparative example)
In the fixing unit structure 100 of the first embodiment shown in FIG. 3, the structure of the fixing unit of the comparative example has no heat shield member 123 and the guide member 125 has a lower thermal conductivity than the present embodiment. In the structure of the fixing unit of the comparative example, in the arrangement of each member shown in FIG. 4, the radiant heat Q (see FIG. 5) from the fixing belt 112 reaches the conveyor belts 81A and 81B, and the temperature of the conveyor belts 81A and 81B increases. To do.

  Here, since the width in the Z direction of the transport belts 81A and 81B is narrower than the maximum width in the Z direction of the recording paper P, the temperature of the portion that is in contact with the transport belts 81A and 81B in the recording paper P of the comparative example. It becomes higher than the temperature of the part which is not in contact. For this reason, in the comparative example, the temperature distribution in the Z direction of the recording paper P entering the nip portion N is different from the portions corresponding to the sections CD and FG as shown in FIG. It becomes a state higher than the part.

  In FIG. 6B, the temperature T1-T0 corresponds to the amount of change caused by the guide member 125 heated by the radiant heat Q, and the temperature difference ΔT2 = T4-T1 is the difference between the conveyance belts 81A and 81B. This corresponds to the amount of change in temperature due to contact. Further, T0 <T1 <T4.

  Thus, in the structure of the fixing unit of the comparative example, a maximum temperature difference of ΔT2 occurs in the Z direction of the recording paper P. For this reason, in the structure of the fixing unit of the comparative example, when fixing at the nip N at the same temperature in the Z direction, the amount of heat given to the toner T in the sections CD and FG of the recording paper P is The toner image becomes excessive by an amount corresponding to the difference ΔT2, and the glossiness of the toner image after fixing differs in the Z direction. That is, image unevenness occurs.

(Function)
Next, the operation of the first embodiment will be described.

  As shown in FIG. 5, in the fixing unit structure 100 of the first embodiment, when the fixing belt 112 is heated by the heating unit 114, radiant heat Q is radiated from the heated fixing belt 112. Since the fixing belt 112 protrudes above the conveyance belts 81A and 81B, in the range from the second heating roll 118 to the nip portion N, the fixing belt 112 is directed toward the conveyance belts 81A and 81B and the guide member 125. Thus, radiant heat Q is emitted. In addition, in FIG. 5, illustration of the intake part 90 is abbreviate | omitted.

  Here, the radiant heat Q from the fixing belt 112 toward the transport belts 81A and 81B is shielded by the heat shield member 123 between the fixing belt 112 and the transport belts 81A and 81B. Thereby, the temperature rise of conveyance belt 81A, 81B is suppressed. In particular, the heat shield member 123 shields heat between the linear portion LA of the conveyor belts 81A and 81B and a portion where the fixing belt 112 and the second heating roll 118 (halogen heater 114B) are in contact with each other. , 81B is further suppressed from rising.

  On the other hand, the radiant heat Q from the fixing belt 112 toward the guide member 125 is radiated to the guide member 125 as it is because there is no member that shields heat between the fixing belt 112 and the guide member 125. Thereby, the temperature of the guide member 125 rises.

  With these actions, in the fixing unit structure 100 according to the first embodiment, the temperature distribution in the Z direction of the recording paper P entering the nip portion N is as shown in FIG. The temperature difference is suppressed. Note that the temperature T2-T0 in FIG. 6A corresponds to the amount of change in temperature caused by the guide member 125 heated by the radiant heat Q, and the temperature difference ΔT1 = T3-T2 is in contact with the conveyor belts 81A and 81B. This corresponds to the amount of change caused by the temperature rise. Further, T0 <T1 <T2 <T3 <T4.

  Specifically, in the fixing unit structure 100 of the first embodiment shown in FIG. 5, since the thermal conductivity of the guide member 125 is higher than that of the comparative example, the temperature rise of the recording paper P by the guide member 125 is the temperature. The temperature rises from T1 to temperature T2. Further, since the guide member 125 has a width equal to or larger than the maximum width of the recording paper P, the recording paper P is evenly warmed in the Z direction (width direction).

  Furthermore, in the fixing unit structure 100 of the first embodiment, the temperature increase of the conveyor belts 81A and 81B is suppressed by the heat shielding action of the heat shielding member 123 compared to the comparative example. For this reason, in the recording paper P, the temperature difference ΔT1 between the portion in contact with the conveyance belts 81A and 81B and the portion not in contact is smaller than the temperature difference ΔT2 in the comparative example (see FIG. 6B) (ΔT1). <ΔT2).

  Thus, in the fixing unit structure 100 according to the first embodiment, the temperature difference caused by the conveyance belts 81A and 81B in the width direction of the recording paper P is suppressed. In the fixing unit structure 100 according to the first embodiment, the recording paper P is evenly heated in the width direction by the guide member 125 having a width wider than that of the recording paper P. As a result, in the fixing unit structure 100 of the first embodiment, the ratio of the temperature difference to the absolute value of the temperature (the effect of the temperature difference) is smaller than in the comparative example, and thus the temperature difference in the width direction of the recording paper P. Is suppressed.

  Further, in the image forming apparatus 10 of the first embodiment, the difference in the amount of heat applied to the toner T in the width direction of the recording paper P is small, so that the glossiness of the toner image T after fixing varies in the width direction. It is suppressed. As a result, deterioration in image quality (gloss unevenness) due to the difference in the amount of heat applied to the toner T is suppressed.

[Second Embodiment]
Next, the structure of the fixing unit and an example of the image forming apparatus according to the second embodiment of the present invention will be described. Note that the same reference numerals as those in the first embodiment are given to the same members and parts as those in the first embodiment described above, and the description thereof is omitted.

  FIG. 7 shows a structure 130 of the fixing unit according to the second embodiment. The fixing unit structure 130 is provided in place of the fixing unit structure 100 (see FIG. 1) in the image forming apparatus 10 (see FIG. 1) of the first embodiment. Further, the fixing unit structure 130 has a configuration in which a heat shielding member 132 is provided instead of the heat shielding member 123 in the fixing unit structure 100 of the first embodiment, and other members excluding the heat shielding member 132 are provided. The parts are the same as those of the fixing unit structure 100.

  As an example, the heat shielding member 132 is made of glass-filled PET (polyethylene terephthalate). Moreover, the heat shield member 132 has an inclined portion 132A and an extending portion 132B, which are integrated.

  The inclined portion 132A extends obliquely downward from the vicinity of the −Y side end (lower end) of the first side wall 122A along the moving direction of the fixing belt 112 so that the X side is lowered to the −Y side.

  The extending part 132B extends from the X-side end part of the inclined part 132A to the −Y side (downward) along the Y direction. In other words, the extending portion 132B extends in the vertical direction intersecting the conveyance direction of the recording paper P between the conveyance belts 81A and 81B and the guide member 125. Moreover, the extension part 132B is arrange | positioned on the above-mentioned straight line K (it shows with a dashed-dotted line) as an example. Thus, the heat shield member 132 is provided on the upstream side of the guide member 125 in the conveyance direction of the recording paper P, and does not extend to above the guide member 125.

  Here, the first side wall 122 </ b> A and the heat shielding member 132 are surrounded by the ceiling wall 122 </ b> B, the first side wall 122 </ b> A, and the heat shielding member 132 so that the portion wound around the second heating roll 118 of the fixing belt 112 is surrounded. Has been placed. That is, the first side wall 122A and the heat shield member 132 are arranged so as to cover the portion of the fixing belt 112 that protrudes toward the conveyance belts 81A and 81B. The first side wall 122A and the heat shield member 132 overlap the X-side portion of the conveyor belts 81A and 81B when viewed in the Y direction.

(Function)
Next, the operation of the second embodiment will be described.

  As shown in FIG. 7, in the fixing unit structure 130 of the second embodiment, when the fixing belt 112 is heated by the heating unit 114, the heated fixing belt 112 is transferred to the conveyance belts 81 </ b> A and 81 </ b> B and the guide member 125. Radiant heat Q is radiated toward it.

  Here, the radiant heat Q from the fixing belt 112 toward the transport belts 81A and 81B is shielded by the heat shield member 132 (the inclined portion 132A and the extension portion 132B) between the fixing belt 112 and the transport belts 81A and 81B. . Thereby, the temperature rise of conveyance belt 81A, 81B is suppressed. In particular, the heat shield member 132 shields heat between the linear portions LA (see FIG. 5) of the transport belts 81A and 81B and a portion where the fixing belt 112 and the second heating roll 118 (halogen heater 114B) are in contact with each other. Therefore, the temperature rise of the conveyor belts 81A and 81B is further suppressed. In addition, in FIG. 7, illustration of the intake part 90 is abbreviate | omitted.

  On the other hand, the radiant heat Q from the fixing belt 112 toward the guide member 125 is radiated to the guide member 125 as it is because there is no member that shields heat between the fixing belt 112 and the guide member 125. Further, in the fixing unit structure 130, a triangular heating chamber 134 is formed outside the fixing belt 112 when viewed from the XY plane by the extending portion 132 </ b> B and the guide member 125. As a result, the guide member 125 is more easily heated with respect to the comparative example, and the temperature of the guide member 125 rises in a short time. Then, the recording paper P is evenly warmed in the Z direction (width direction).

  By these actions, the temperature difference in the width direction of the recording paper P is suppressed in the fixing unit structure 130 of the second embodiment. Further, in the image forming apparatus 10 of the second embodiment, the difference in the amount of heat applied to the toner T in the width direction of the recording paper P is small, so that the glossiness of the toner image T after fixing varies in the width direction. It is suppressed. As a result, deterioration in image quality (gloss unevenness) due to the difference in the amount of heat applied to the toner T is suppressed.

[Third embodiment]
Next, the structure of the fixing unit and an example of the image forming apparatus according to the third embodiment of the present invention will be described. The same reference numerals as those in the first and second embodiments are given to the same members and parts as those in the first and second embodiments described above, and the description thereof is omitted.

  FIG. 8 shows a structure 140 of the fixing unit according to the third embodiment. The fixing unit structure 140 is provided in place of the fixing unit structure 130 (see FIG. 7) of the second embodiment. The fixing unit structure 140 has a configuration in which a planar heating element 142 as an example of auxiliary heating means is attached to the lower surface of the guide member 125 in the fixing unit structure 130 of the second embodiment. These members and parts are the same as those of the fixing unit structure 130.

  The planar heating element 142 is formed in a rectangular shape whose longitudinal direction is the Z direction in plan view. The planar heating element 142 is fixed to the −Y side (lower surface) of the guide member 125 with an adhesive. The sheet heating element 142 is electrically connected to the power supply 144, generates heat when energized from the power supply 144, and heats the guide member 125 from the lower surface side.

(Function)
Next, the operation of the third embodiment will be described.

  As shown in FIG. 8, in the fixing unit structure 140 of the third embodiment, when the fixing belt 112 is heated by the heating unit 114, the heated fixing belt 112 is transferred to the conveyance belts 81 </ b> A and 81 </ b> B and the guide member 125. Radiant heat Q is radiated toward it. In addition, illustration of the intake part 90 is abbreviate | omitted in FIG.

  Radiant heat Q from the fixing belt 112 toward the guide member 125 is radiated to the guide member 125 as it is because there is no member that shields heat between the fixing belt 112 and the guide member 125. Further, in the fixing unit structure 140, a triangular heating chamber 134 is formed outside the fixing belt 112 when viewed from the XY plane by the extending portion 132 </ b> B and the guide member 125. Further, in the fixing unit structure 140, the guide member 125 is heated by the planar heating element 142. Due to these actions, in the fixing unit structure 140, the guide member 125 is further heated as compared with the comparative example, so that the temperature of the guide member 125 rises in a shorter time. Then, the recording paper P is evenly warmed in the Z direction (width direction).

  As described above, in the fixing unit structure 140 according to the third embodiment, in the width direction of the recording paper P, the temperature difference between the respective units is suppressed and the difference in the amount of heat given to the toner T is reduced. It is suppressed that the glossiness of the image T differs in the width direction. As a result, in the image forming apparatus 10 of the third embodiment, deterioration in image quality (gloss unevenness) due to the difference in the amount of heat applied to the toner T is suppressed.

  In addition, this invention is not limited to said embodiment.

  As the heat shielding means and the heat insulating member, the upper cover member 122 itself may be a heat shielding member. That is, the heat shield member 123 is not limited to a member separate from the upper cover member 122, and may be integrally molded with the upper cover member 122. Further, the inclination angle of the heat shield member 123 may or may not be along the moving direction of the fixing belt 112.

  The conveying means is not limited to the conveying unit 80 having the conveying belts 81A and 81B, and the conveying belt may be one or three or more. Further, the conveyance unit 80 is not limited to the one that performs intake by the intake unit 90, and the intake unit 90 may be omitted.

  The heating means is not limited to the halogen heaters 114A and 114B and the one that energizes the resistor to generate heat, but an electromagnetic that provides a heat generating layer on the fixing belt 112 and energizes the coil to generate heat by the action of the generated magnetic field. A guidance system may be used.

  The developer image forming means is not limited to the dry image forming unit 60, and may be a wet type that performs development using a liquid developer.

10 Image forming apparatus 60 Image forming section (an example of developer image forming means)
80 Conveying section (an example of conveying means)
81A Conveying belt (an example of a conveying member)
81B Conveying belt (an example of a conveying member)
100 Fixing Unit Structure 110 Fixing Device (Example of Fixing Unit)
112 Fixing belt (an example of a fixing member)
114 Heating part (an example of heating means)
117 1st heating roll (an example of heating means)
118 Second heating roll (an example of heating means)
123 Heat shielding member (an example of heat shielding means and heat insulating member)
125 Guide member (an example of a guide member)
130 Fixing Unit Structure 132B Extension Unit 140 Fixing Unit Structure 142 Planar Heating Element (An Example of Auxiliary Heating Unit)
LA straight section (an example of a transport section)

The present invention includes a transport hand stage of the recording medium is provided on the upstream side of the fixing unit in the conveying direction of the recording medium, in a configuration in which the fixing member is projecting to the conveying means side, suppressing the temperature difference in the width direction of the recording medium It is an object of the present invention to obtain a structure of a fixing unit and an image forming apparatus that can be used.

The structure of the fixing unit according to claim 1 of the present invention is such that the width of contact with the recording medium in the width direction intersecting the conveyance direction of the recording medium is narrower than the width of the recording medium, and there is no conveyance means for conveying the recording medium. A fixing member which is formed in an end shape and is capable of moving around so that at least a part thereof overlaps with the conveying unit when viewed in a direction intersecting the conveying direction and the width direction ; and a heating unit for heating the fixing member. A fixing unit that fixes the developer on the recording medium conveyed by the conveying unit to the recording medium, a cover member that covers the fixing unit, and a cover member that is integrally formed with the fixing member and the conveying unit. And a heat shielding means for shielding heat between the two.

According to a second aspect of the present invention , there is provided a guide member for guiding the recording medium conveyed by the conveying unit to the downstream side in the conveying direction , wherein the width in the width direction is equal to or larger than the width of the recording medium. And the heat shield means is provided upstream of the guide member in the transport direction. In the structure of the fixing unit according to claim 3 of the present invention , the heat shield unit includes a heat insulating member, and the heat insulating member is disposed between the transport unit and the guide member in the transport direction and the width direction. And an extending portion that extends in a direction intersecting with.

According to a fourth aspect of the present invention, there is provided an auxiliary heating means for heating the guide member. In the fixing unit structure according to a fifth aspect of the present invention, both ends in the width direction of the transport unit are disposed on the inner side than both ends in the width direction of the recording medium transported by the transport unit.

In the structure of the fixing unit according to a sixth aspect of the present invention, the fixing member is in contact with the heating unit between the heating unit and the conveying unit, and the conveying unit is in contact with the recording medium to record the recording medium. The heat shield means shields heat between the transport section and a portion where the fixing member and the heating means are in contact with each other.

According to a seventh aspect of the present invention, there is provided a developer image forming unit for forming a developer image on a recording medium, and a developer image formed by the developer image forming unit on a recording medium by the fixing unit. The fixing portion structure according to any one of claims 1 to 6 , wherein the fixing portion is fixed.

Claim 1, claim 2, the invention of claim 5, the conveying hand stage of the recording medium is provided on the upstream side of the fixing unit in the conveying direction of the recording medium, in a configuration in which the fixing member is projecting to the conveying means side, A temperature difference in the width direction of the recording medium can be suppressed as compared with a configuration in which a heat shield unit is not provided between the fixing member and the transport unit.

According to the invention of claim 3 , the temperature of the guide member can be increased in a short time compared to a configuration in which a heat insulating member having an extending portion is not provided between the conveying means and the guide member.

According to the invention of claim 4 , the temperature of the guide member can be raised in a short time compared to a configuration in which no auxiliary heating means is provided.

According to the sixth aspect of the present invention, the temperature difference in the width direction of the recording medium can be further suppressed as compared with the case without this configuration.

According to the seventh aspect of the present invention, as compared with a configuration having a fixing device in which no heat shield means is provided between the fixing member and the conveying means, a reduction in image quality due to a temperature difference in the width direction of the recording medium is suppressed. Can do.

Claims (5)

A width of contact with the recording medium in the width direction intersecting the conveyance direction of the recording medium is narrower than the width of the recording medium, and conveying means for conveying the recording medium;
A guide member for guiding the recording medium conveyed by the conveying means to the downstream side in the conveying direction, wherein the width in the width direction is equal to or larger than the width of the recording medium;
The fixing member is formed in an endless shape and has a fixing member that can be moved around so that at least a portion thereof overlaps the conveying unit when viewed in the vertical direction, and a heating unit that heats the fixing member, and is guided by the guide member Fixing means for fixing the developer on the recording medium to the recording medium;
A heat shield means provided on the upstream side of the guide member in the transport direction and shields heat between the fixing member and the transport means;
The structure of the fixing unit having   The heat shield means includes a heat insulating member, and the heat insulating member includes an extending portion extending in a direction intersecting the transport direction and the width direction between the transport means and the guide member. The structure of the fixing unit according to claim 1.   The structure of the fixing unit according to claim 1, wherein auxiliary heating means for heating the guide member is provided. The fixing member is in contact with the heating unit between the heating unit and the conveying unit;
The transport means includes a transport member including a transport unit that transports the recording medium in contact with the recording medium,
4. The fixing unit structure according to claim 1, wherein the heat shielding unit shields heat between the conveyance unit and a portion where the fixing member and the heating unit are in contact with each other. 5. Developer image forming means for forming a developer image on a recording medium;
The structure of the fixing unit according to any one of claims 1 to 4, wherein the developer image formed by the developer image forming unit is fixed to a recording medium by the fixing unit.
An image forming apparatus.