Fixing device and image forming apparatus

Abstract

To reduce a conveyance failure occurring in a recording medium to be conveyed, compared with a case where air blown to a pressure roll to cool the pressure roll directly hits the recording medium released from holding by holding parts.SOLUTION: A fixing device comprises: a conveying unit that conveys a recording medium; a heating roll that rotates to heat the recording medium conveyed by the conveying unit; a pressure roll that is arranged opposite to the heating roll, rotates to have at least a part of the recording medium to be conveyed wound therearound, and applies pressure to a portion of the recording medium wound therearound toward the heating roll; holding parts that are provided in the conveying unit, hold a leading end of the recording medium to be conveyed, and release the holding of the leading end of the recording medium when the recording medium passes through a portion where the pressure roll and the heating roll face each other; and a blowing unit that blows air in a direction different from a direction directed to the recording medium released from the holding by the holding parts, thereby cooling the pressure roll.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a fixing device and an image forming apparatus. [Background technology]

[0002] The printing device described in Patent Document 1 is a printing device equipped with a drying device that dries printed paper printed in a printing unit as it is transported to a paper discharge unit, and is equipped with a plurality of clamping means that clamp the printed sheet-like printed material, a transporting means that circulates the clamping means along an endless transporting path, thereby causing the clamping means to run along a first transporting path from the printing unit to the paper discharge unit while clamping the printed material, and to run along a second transporting path from the paper discharge unit back to the printing unit without clamping the printed material, a drying means installed near the first transporting path for drying the printed material, and a wind shielding means provided along the transporting path so that warm air generated by the drying means is guided substantially only toward the first transporting path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-39635 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a configuration in which a conveying section is provided that conveys the recording medium by gripping the leading edge of the recording medium with a gripping section and moving the gripping section, the conveyed recording medium is heated by passing through a position where a rotating pressure roll and a heating roll face each other. Then, the gripping section that grips the leading edge of the recording medium releases the grip of the leading edge of the recording medium after the gripping section passes through the position where the pressure roll and the heating roll face each other. In addition, since the pressure roll is heated by the heating roll, the pressure roll needs to be cooled.

[0005] Here, if the air blown onto the pressure roll to cool it hits the recording medium that has been released from the gripping portion directly, this can cause transport problems with the recording medium being transported.

[0006] The objective of the present disclosure is to suppress transport defects that occur in the transported recording medium, compared to when the air for cooling the pressure roll directly hits the recording medium that has been released from the gripping portion. [Means for solving the problem]

[0007] The fixing device according to the first aspect of the present disclosure is characterized in that it comprises a transport section for transporting a recording medium, a heating roll for rotating to heat the recording medium transported by the transport section, a pressure roll arranged opposite the heating roll, which rotates and around which at least a portion of the recording medium transported is wrapped and which pressurizes the wrapped portion of the recording medium toward the heating roll, a gripping section provided in the transport section for gripping a leading end of the recording medium being transported and releasing the grip on the leading end of the recording medium when the recording medium passes an opposing position where the pressure roll and the heating roll face each other, and a blowing section for blowing air in a direction different from the direction toward the recording medium whose grip by the gripping section has been released to cool the pressure roll.

[0008] A fixing device according to a second aspect of the present disclosure is characterized in that, in the fixing device described in the first aspect, the pressure roll faces the heating roll from below, and the blowing section blows air onto the pressure roll in a portion below the center of rotation of the pressure roll.

[0009] A fixing device according to a third aspect of the present disclosure is the fixing device according to the second aspect, characterized in that the blowing section blows air onto the pressure roll so that the air flows in the rotation direction of the pressure roll.

[0010] A fixing device according to a fourth aspect of the present disclosure is the fixing device according to the third aspect, characterized in that the blowing section blows air downward with respect to a horizontal direction.

[0011] A fixing device according to a fifth aspect of the present disclosure is characterized in that, in the fixing device described in the second aspect, a suppression member is provided downstream of the opposing position in the rotation direction of the pressure roll and upstream of the pressure roll of the portion where air is blown by the blowing unit, for suppressing the air blown onto the pressure roll by the blowing unit from flowing along the outer peripheral surface of the pressure roll and reaching the portion of the recording medium that has passed the opposing position.

[0012] A fixing device according to a sixth aspect of the present disclosure is characterized in that, in the fixing device described in the second aspect, a concave accommodating portion is formed on the outer peripheral surface of the pressure roll in which the gripping portion is accommodated, and the fixing device further comprises a forming member which is arranged downstream of the opposing position in the rotation direction of the pressure roll and upstream of the pressure roll of the portion where air is blown by the blowing portion, and which has an opposing portion formed to face the rotating accommodating portion.

[0013] A fixing device according to a seventh aspect of the present disclosure is characterized in that, in the fixing device described in the sixth aspect, when the facing portion faces the storage portion and the forming member is viewed from the radial outside of the pressure roll, the facing portion completely covers the storage portion.

[0014] An image forming apparatus according to an eighth aspect of the present disclosure is characterized by comprising a transfer unit that transfers a toner image to a recording medium, and a fixing device according to any one of claims 1 to 7 that fixes the toner image transferred to the recording medium to the recording medium. Effect of the Invention

[0015] According to the fixing device of the first aspect of the present disclosure, it is possible to suppress transport problems occurring in the transported recording medium compared to when the air blown onto the pressure roll to cool the pressure roll directly hits the recording medium that has been released from the gripping portion.

[0016] According to the fixing device of the second aspect of the present disclosure, it is possible to suppress transport problems occurring in the recording medium being transported, compared to when the blowing section blows air onto the portion of the pressure roll that is above the center of rotation of the pressure roll.

[0017] According to the fixing device of the third aspect of the present disclosure, it is possible to suppress transport problems occurring in the recording medium being transported, compared to a case in which the blowing section blows air onto the pressure roll so that the air is returned by the rotating pressure roll.

[0018] According to the fixing device according to the fourth aspect of the present disclosure, it is possible to suppress transport defects occurring in the transported recording medium, compared to a case in which the blowing section blows air in an upward direction relative to the horizontal direction.

[0019] According to the fixing device of the fifth aspect of the present disclosure, transport defects occurring in the recording medium being transported can be suppressed compared to a case in which the air blown onto the pressure roll flows freely along the outer peripheral surface of the pressure roll to the portion of the recording medium that has passed the opposing position.

[0020] According to the fixing device of the sixth aspect of the present disclosure, transport problems occurring in the recording medium being transported can be suppressed compared to a case in which the air blown onto the pressure roll freely flows into and out of the storage section.

[0021] According to the fixing device of the seventh aspect of the present disclosure, when the opposing curved surface faces the storage section and the forming member is viewed from the radial outside of the pressure roll, transport problems occurring in the recording medium being transported can be suppressed compared to when a portion of the storage section is visible from around the forming member.

[0022] According to the image forming apparatus of the eighth aspect of the present disclosure, clogging of the recording medium can be suppressed compared to a case where the image forming apparatus is equipped with a fixing device that blows air directly onto the recording medium after it has been released from the gripping portion. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present disclosure. [Diagram 2] 1 is a schematic configuration diagram illustrating a toner image forming unit of an image forming apparatus according to an embodiment of the present disclosure. [Diagram 3] FIG. 2 is a perspective view illustrating a conveying mechanism of the image forming apparatus according to the embodiment of the present disclosure. [Figure 4] FIG. 2 is a configuration diagram illustrating a cooling unit of an image forming apparatus according to an embodiment of the present disclosure. [Diagram 5] FIG. 2 is a perspective view illustrating a conveying mechanism of the image forming apparatus according to the embodiment of the present disclosure. [Figure 6] FIG. 2 is a configuration diagram illustrating a fixing device according to an embodiment of the present disclosure. [Figure 7] FIG. 2 is a perspective view showing a main heating unit of the fixing device according to the embodiment of the present disclosure. [Figure 8] FIG. 2 is a configuration diagram illustrating a preheating unit of a fixing device according to an embodiment of the present disclosure. [Figure 9] FIG. 2 is a configuration diagram showing a main heating section of a fixing device according to an embodiment of the present disclosure. [Figure 10] 4 is an explanatory diagram showing a main heating section of the fixing device according to an embodiment of the present disclosure, in a state in which the pressure roll is rotating; FIG. [Figure 11] 4 is an explanatory diagram showing a main heating section of the fixing device according to an embodiment of the present disclosure, in a state in which the pressure roll is rotating; FIG. [Figure 12] 4 is an explanatory diagram showing a main heating section of the fixing device according to an embodiment of the present disclosure, in a state in which the pressure roll is rotating; FIG. [Figure 13] 4 is an enlarged configuration diagram of a main heating unit of a fixing device according to an embodiment of the present disclosure, illustrating a suppressing member, a storage unit, and the like. FIG. [Figure 14] 4 is a diagram showing a fluid analysis result of a fixing device according to an embodiment of the present disclosure. [Figure 15] 4 is a diagram showing a fluid analysis result of a fixing device according to an embodiment of the present disclosure. [Figure 16] FIG. 4 is a configuration diagram showing a fixing device according to a comparative example to the embodiment of the present disclosure. [Figure 17] 11 is a diagram showing a result of a fluid analysis of a fixing device according to a comparative example to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An example of a fixing device and an image forming apparatus according to an embodiment of the present disclosure will be described with reference to Figures 1 to 17. Note that, in the drawings, arrow H indicates the up-down direction (vertical direction) of the device, arrow W indicates the width direction (horizontal direction) of the device, and arrow D indicates the depth direction (horizontal direction) of the device.

[0025] (Image forming apparatus 10) The image forming apparatus 10 according to this embodiment is an electrophotographic image forming apparatus that forms a toner image on a sheet member P as a recording medium. As shown in Fig. 1, the image forming apparatus 10 includes a medium storage section 50, a discharge section 52, an image forming section 12, a conveying mechanism 60, a fixing device 100, a cooling section 90, and a control section 14 that controls each section.

[0026] [Medium storage section 50] 1, the medium containing section 50 is disposed on one side in the width direction (the right side in the figure) of the image forming apparatus 10, and two medium containing sections 50 are provided side by side in the vertical direction. Each medium containing section 50 contains a sheet material P, and the sheet material P is selectively sent out from the two medium containing sections 50.

[0027] [Discharge section 52] 1, the discharge section 52 is disposed on the other side in the width direction (the left side in the figure) of the image forming apparatus 10, and is adapted to discharge the sheet member P on which the toner image has been formed. Specifically, after the toner image has been fixed to the sheet member P by the fixing device 100, the sheet member P cooled by the cooling section 90 is discharged to the discharge section 52.

[0028] [Image forming unit 12] As shown in FIG. 1, the image forming unit 12 is disposed between the medium storage unit 50 and the discharge unit 52 in the width direction, and includes a toner image forming unit 20 that forms a toner image, and a transfer device 30 that transfers the toner image formed in the toner image forming unit 20 to a sheet member P.

[0029] Furthermore, a plurality of toner image forming units 20 are provided so as to form a toner image for each color. The image forming apparatus 10 is provided with toner image forming units 20 for a total of four colors: yellow (Y), magenta (M), cyan (C), and black (K). (Y), (M), (C), and (K) shown in Fig. 1 indicate components corresponding to the above-mentioned respective colors. In the following description, Y, M, C, and K may be omitted when there is no particular distinction between them.

[0030] -Toner image forming unit 20- The toner image forming units 20 for each color are basically configured in the same way except for the toner used. Specifically, as shown in Fig. 2, the toner image forming units 20 for each color include a photoconductor drum 21 that rotates in the direction of the arrow A in the figure, and a charger 22 that charges the photoconductor drum 21. Furthermore, the toner image forming units 20 for each color include an exposure device 23 that exposes the photoconductor drum 21 charged by the charger 22 to form an electrostatic latent image on the photoconductor drum 21, and a developing device 24 that develops the electrostatic latent image formed on the photoconductor drum 21 by the exposure device 23 using toner.

[0031] -Transfer device 30- 1, the transfer device 30 includes a transfer belt 31 as an intermediate transfer body, a primary transfer roll 33, a secondary transfer roll 34, and an opposing roll 36. The transfer device 30 is an example of a transfer section.

[0032] The primary transfer roll 33 is configured to transfer the toner image formed on the photosensitive drum 21 onto the transfer belt 31 at a primary transfer position T (see FIG. 2) between the photosensitive drum 21 and the primary transfer roll 33.

[0033] The transfer belt 31 is endless and its position is determined by being wound around a plurality of rolls 32. When at least one of the plurality of rolls 32 is driven to rotate, the transfer belt 31 rotates in the direction of arrow B, and transports the primarily transferred image to the secondary transfer position NT.

[0034] A part of the transfer belt 31 is wound around the secondary transfer roll 34, and the opposing roll 36 is disposed so as to face the secondary transfer roll 34 with the transfer belt 31 interposed therebetween (see FIG. 5).

[0035] As a result, the secondary transfer roll 34 rotates along with the rotating transfer belt 31, is sandwiched between the rotating opposing roll 36 and the transfer belt 31, and transfers the toner image of the transfer belt 31 to the sheet material P passing through the secondary transfer position NT.

[0036] [Transport mechanism 60] As shown in FIG. 1, the conveying mechanism 60 includes a feed roll 62 that sends out the sheet material P stored in the medium storage section 50 to a conveying path 58 for the sheet material P, a plurality of conveying rolls 64a, 64b that convey the sheet material P sent out to the conveying path 58, and a chain gripper 66.

[0037] The multiple transport rolls 64a transport the sheet material P sent out from the feed roll 62 to the chain gripper 66, and the multiple transport rolls 64b transport the sheet material P transported by the chain gripper 66 to a cooling section 90 (see Figure 4).

[0038] 3, the chain gripper 66 has a pair of chains 72 and a holding portion 68 that holds the leading end of the sheet material P. Since the chain gripper 66 is also a component of the fixing device 100, it will be described together with the fixing device 100 described later.

[0039] [Fixing device 100] As shown in FIG. 6, the fixing device 100 includes a chain gripper 66 and a transfer device 30 (see FIG. 1) disposed downstream of the transfer device 30 in the conveying direction of the sheet material P.

[0040] The fixing device 100 further includes a main heating section 120 that comes into contact with the sheet member P to apply heat and pressure thereto, a blowing unit 170, and a fan 180. The fixing device 100 includes a heating section 160 that includes the preheating section 102 and the main heating section 120 and heats the sheet member P.

[0041] [Chain Gripper 66] 3, the chain gripper 66 includes a pair of chains 72 and a holding portion 68 that holds the sheet material P. The chain gripper 66 is an example of a conveying portion.

[0042] -Chain 72- The pair of chains 72 are arranged to be spaced apart in the device depth direction, as shown in Fig. 3. The pair of chains 72 are arranged on one end side and the other end side of the opposing roll 36 in the axial direction, as shown in Fig. 5, and are wound around a pair of sprockets 73 whose axial direction is the device depth direction, a pair of sprockets 71 (see Fig. 7) arranged on one end side and the other end side of a pressure roll 140 described below in the axial direction, and a pair of sprockets 74 (see Fig. 1) arranged at an interval in the device depth direction. When any one of these pairs of sprockets rotates, the chain 72 goes around in the direction of arrow C.

[0043] Further, both ends of the holding portion 68 that holds the sheet material P are attached to the pair of chains 72. The chains 72 are an example of a moving portion.

[0044] -Holding part 68- 3, the holding portion 68 has both ends attached to a pair of chains 72, respectively, and includes an attachment member 75 extending in the device depth direction, and a gripper 76 attached to the attachment member 75. A plurality of holding portions 68 are provided, and are arranged at predetermined intervals along the circumferential direction (circumferential direction) of the chains 72. The gripper 76 is an example of a gripping portion.

[0045] A plurality of grippers 76 are provided and attached to the attachment member 75 at predetermined intervals along the device depth direction. Specifically, the gripper 76 has a claw 76a. The attachment member 75 is formed with a contact portion 75a with which the claw 76a comes into contact. As a result, the gripper 76 grips the leading end of the sheet material P by pinching the leading end of the sheet material P between the claw 76a and the contact portion 75a. For example, the claw 76a of the gripper 76 is pressed against the contact portion 75a by a spring or the like, and the claw 76a is moved toward and away from the contact portion 75a by the action of a cam or the like.

[0046] 1 receives the sheet material P transported by the transport roll 64a, and transports the sheet material P to the secondary transfer position NT while gripping the leading edge of the sheet material P. Furthermore, the chain gripper 66 causes the sheet material P to pass through the preheating unit 102, and then transports it to the main heating unit 120.

[0047] [Main heating section 120] 6, the main heating section 120 is disposed downstream of the preheating section 102 in the conveying direction of the sheet member P. The main heating section 120 includes a heating roll 130 that contacts the conveyed sheet member P to heat the sheet member P, a pressure roll 140 that presses the sheet member P toward the heating roll 130, and a driven roll 150 that rotates following the rotation of the rotating heating roll 130.

[0048] -Heating Roll 130- 6, the heating roll 130 is disposed so as to contact the upwardly facing surface of the sheet member P being conveyed and extend in the device depth direction with the axial direction being the device depth direction. The heating roll 130 also has a heater 138 housed therein.

[0049] 7, shaft portions 139a extending in the device depth direction are formed on both ends of the heating roll 130 in the device depth direction. Support members 139b are provided to support the shaft portions 139a. Thus, the heating roll 130 is rotatably supported by the support members 139b at both ends of the heating roll 130.

[0050] -Driven roll 150- 6 and 7, the driven roll 150 is disposed on the opposite side of the sheet member P conveyed across the heating roll 130, so as to extend in the device depth direction with the axial direction being the device depth direction. The driven roll 150 also has a heater 154 housed therein.

[0051] In this configuration, the driven roll 150 rotates while being driven by the heating roll 130. Then, the driven roll 150 heats the heating roll 130.

[0052] -Pressure Roll 140- 7, the pressure roll 140 is disposed on the opposite side of the heating roll 130 with the sheet member P being conveyed therebetween, in contact with the downward surface of the sheet member P being conveyed, and extending in the device depth direction with the axial direction being the device depth direction. The pressure roll 140 has a pair of shaft portions 148 formed at both ends in the device depth direction. The outer diameter of the pressure roll 140 is larger than the outer diameter of the heating roll 130.

[0053] 9, a concave accommodation portion 140a extending in the device depth direction is formed on the outer circumferential surface of the pressure roll 140. When the sheet material P passes between the pressure roll 140 and the heating roll 130, the gripper 76 that grips the leading end of the sheet material P is accommodated in the accommodation portion 140a.

[0054] -Fan 180- 6, the fan 180 is disposed so as to face the pressure roll 140 in the device width direction, and is adapted to cool the pressure roll 140. The fan 180 will be described in detail later.

[0055] -others- 7, the main heating section 120 includes a support member 156 that supports the pressure roll 140, and a biasing member 158 that biases the pressure roll 140 toward the heating roll 130 via the support member 156. A pair of support members 156 are provided. The pair of support members 156 are respectively disposed so as to rotatably support the pair of shaft portions 148 of the pressure roll 140 from below.

[0056] As shown in FIG. 6, a sensor 110, which is an optical sensor that detects the sheet member P being transported, is disposed downstream of the opposing position of the heating roll 130 and the pressure roll 140 in the transport direction of the sheet member P.

[0057] In this configuration, the pair of biasing members 158 bias the pressure roll 140 toward the heating roll 130, so that the pressure roll 140 presses the sheet member P, at least a part of which is wound around the pressure roll 140, toward the heating roll 130. Furthermore, the pressure roll 140 rotates by a rotational force transmitted from a driving member (not shown). Then, the heating roll 130 rotates following the rotating pressure roll 140, and the driven roll 150 rotates following the rotating heating roll 130. Furthermore, the heating roll 130 and the pressure roll 140 sandwich and transport the sheet member P to which the toner image has been transferred, so that the toner image is fixed to the sheet member P. In this way, the heating roll 130 and the pressure roll 140 sandwich and transport the sheet member P while rotating, and the sheet member P is heated, so that the toner image is fixed to the sheet member P.

[0058] [Preheating section 102] 6, the preheating unit 102 is disposed downstream of a secondary transfer position NT (see FIG. 1) where a toner image is transferred to the sheet member P, and upstream of the main heating unit 120, in the conveying direction of the sheet member P. Furthermore, the preheating unit 102 is disposed above the sheet member P being conveyed. In other words, the preheating unit 102 is disposed on the side of the sheet member P being conveyed where the toner image is transferred.

[0059] The preheating section 102 includes a reflecting member 104, a plurality of infrared heaters 106 (hereinafter referred to as “heaters 106”), a heating plate 114, a wire mesh 112, and a shutter 132.

[0060] -Reflective material 104- The reflecting member 104 is made of an aluminum plate, and is in the shape of a shallow box with an open side facing the sheet material P to be transported, as shown in Fig. 6. Inside the reflecting member 104, a heating plate 114 and a heater 106 are arranged in this order from the side facing the sheet material P to be transported, as shown in Fig. 8. The reflecting member 104 is formed with a reflecting surface 104a that reflects infrared rays, which are heat rays emitted by the heater 106, toward the heating plate 114 side.

[0061] -Heater 106- The heater 106 is an infrared heater having a cylindrical outer shape, and faces the reflecting surface 104a of the reflecting member 104 in the vertical direction of the device and extends in the depth direction of the device, as shown in Fig. 8. Furthermore, a plurality of heaters 106 are provided and are arranged in the width direction of the device, as shown in Fig. 6.

[0062] -Heating plate 114- As shown in FIG. 6, the heating plates 114 are disposed between the chains 72 and the heaters 106, and a plurality of heating plates 114 are arranged in the width direction of the apparatus.

[0063] In this configuration, the heating plate 114 absorbs infrared rays emitted by the heater 106 and infrared rays reflected by the reflective surface 104a, and the temperature of the heating plate 114 increases and the heating plate 114 dissipates heat. Then, the heating plate 114, whose temperature has increased, heats the sheet material P being conveyed in a non-contact manner.

[0064] -Wire Mesh 112- The wire mesh 112 is fixed to the edge of the reflecting member 104 by a fixing member (not shown), and separates the inside of the reflecting member 104 from the outside of the reflecting member 104, as shown in Fig. 6. In this way, the wire mesh 112 prevents the sheet member P being transported from coming into contact with the heating plate 114.

[0065] -Shutter 132- As shown in FIG. 6, the shutter 132 is disposed next to the reflecting member 104 in a rolled-up state, and is adapted to cover the opening of the reflecting member 104 in an unrolled state.

[0066] In this configuration, when the preheating unit 102 is operating, the shutter 132 opens the opening of the reflecting member 104, and when the preheating unit 102 is not operating, the shutter 132 covers the opening of the reflecting member 104.

[0067] [Spraying unit 170] 6, the blowing unit 170 is disposed so as to face the preheating section 102 in the vertical direction of the apparatus, and the conveyed sheet material P passes between the blowing unit 170 and the preheating section 102. The blowing unit 170 also includes a plurality of fans 172 arranged in the width direction and the depth direction of the apparatus.

[0068] In this configuration, the plurality of fans 172 blow air toward the sheet material P being transported, thereby stabilizing the transport posture of the sheet material P being transported.

[0069] [Cooling section 90] 1, the cooling section 90 is disposed downstream of the fixing device 100 in the conveying direction of the sheet member P. The cooling section 90 also includes two cooling rolls 92 arranged side by side in the device width direction. Since the two cooling rolls 92 have the same configuration, only one of the cooling rolls 92 will be described.

[0070] As shown in Figure 4, the cooling roll 92 includes a cylindrical cooling roll 92a arranged on the upper side across the transport path 58 of the sheet material P, and a cylindrical cooling roll 92b arranged on the lower side across the transport path 58 of the sheet material P.

[0071] In this configuration, the temperature of the surface of the cooling roll 92 is reduced by the air flow generated by a blowing mechanism (not shown) flowing inside the cylindrical cooling roll 92. Furthermore, the cooling roll 92b is rotated by a rotational force transmitted from a driving member (not shown). Furthermore, the cooling roll 92a rotates following the rotation of the cooling roll 92b. The cooling rolls 92a and 92b sandwich and transport the sheet member P, thereby cooling the sheet member P.

[0072] (Overall structure) Next, the operation of the image forming apparatus 10 will be described. In the image forming apparatus 10 shown in FIG. 1, an image is formed as follows.

[0073] 2 to which a voltage is applied, the charger 22 for each color shown in FIG. 2 uniformly negatively charges the surface of the photoconductor drum 21 for each color to a predetermined potential. Next, based on image data input from the outside, the exposure device 23 irradiates the charged surface of the photoconductor drum 21 for each color with exposure light to form an electrostatic latent image.

[0074] As a result, an electrostatic latent image corresponding to the image data is formed on the surface of each photoconductor drum 21. The developing device 24 for each color develops the electrostatic latent image and visualizes it as a toner image. The primary transfer roll 33 of the transfer device 30 transfers the toner image formed on the surface of the photoconductor drum 21 for each color onto the transfer belt 31.

[0075] 1 to the transport path 58 by the delivery roll 62 and then handed over from the transport roll 64a to the chain gripper 66, the sheet material P is sent to the secondary transfer position NT where the transfer belt 31 comes into contact with the opposing roll 36. Specifically, the gripper 76 grips the leading edge of the sheet material P, so that the sheet material P is handed over from the transport roll 64a to the chain gripper 66.

[0076] At the secondary transfer position NT, the sheet member P is conveyed while being sandwiched between the transfer belt 31 and the opposing roll 36, so that the toner image on the surface of the transfer belt 31 is transferred onto the surface of the sheet member P.

[0077] Furthermore, the chain gripper 66 transports the sheet material P onto which the toner image has been transferred. Also, the fan 172 shown in Fig. 6 is operated to blow air onto the sheet material P from below so that the sheet surface of the sheet material P faces in the vertical direction.

[0078] Furthermore, a voltage is applied to the heater 106 of the preheating unit 102. The heating plate 114 absorbs infrared rays emitted by the heater 106 to which a voltage is applied and infrared rays reflected by the reflective surface 104a, and thereby the temperature increases and the heating plate 114 dissipates heat. Then, the heating plate 114, whose temperature has increased, heats the sheet material P conveyed by the chain gripper 66 from above in a non-contact manner. As the sheet material P is heated, the toner constituting the toner image transferred to the sheet material P is softened.

[0079] Furthermore, in the main heating section 120, the heating roll 130 and the pressure roll 140 sandwich and transport the sheet member P heated by the heating plate 114 of the preheating section 102, and fix the toner image onto the sheet member P. The sheet member P on which the toner image has been fixed is released from the gripper 76, transported by the transport roll 64b shown in FIG. 1, and then discharged to the discharge section 52 through the cooling section 90.

[0080] (Main part configuration) Next, a description will be given of the fan 180, a prevention member 190 that prevents the air blown from the fan 180 to the pressure roll 140 from flowing toward the conveyed sheet member P, and the like. The fan 180 is an example of a blowing section.

[0081] [Fan 180] 9, the fan 180 is disposed on the other side of the pressure roll 140 in the device width direction (the left side in the figure) so as to face the lower portion of the pressure roll 140 in the device width direction. The fan 180 extends in the device depth direction and is disposed so as to blow air to the lower portion of the pressure roll 140 over the entire area in the device depth direction. The fan 180 includes a fan body 182 that blows out air, and a guide portion 184 that guides the air blown out by the fan body 182. The fan body 182 and the guide portion 184 are arranged in this order from the other side to one side in the device width direction.

[0082] The fan body 182 includes a plurality of propellers 182b arranged in the device depth direction, and an opening 182a of the fan body 182 faces the pressure roll 140 side.

[0083] Furthermore, guide portion 184 is shaped like a cylinder that opens in the device width direction, and the base end portion of guide portion 184 is attached to fan body 182 so as to surround opening 182a of fan body 182.

[0084] The cross section of guide portion 184 is a rectangular cylinder, and guide portion 184 is configured to include a bottom plate 186, a ceiling plate 188, and a pair of side plates (not shown). Bottom plate 186 has a plate thickness direction that is the up-down direction, and is rectangular when viewed from above.

[0085] The outer shape of the ceiling plate 188 overlaps with the outer shape of the bottom plate 186 when viewed from above, and the ceiling plate 188 has a horizontal portion 188a extending in the device width direction when viewed from the device depth direction, and an inclined portion 188b inclined with respect to the device width direction. The horizontal portion 188a and the inclined portion 188b are lined up in this order from the other side to one side in the device width direction.

[0086] The inclined portion 188b is inclined with respect to the horizontal direction so that the portion on the pressure roll 140 side is disposed lower than the portion on the fan main body 182 side. The outlet 180a of the fan 180 faces the lower portion of the pressure roll 140 in the device width direction. Here, the lower portion of the pressure roll 140 refers to the portion below the center of rotation of the pressure roll 140.

[0087] In this configuration, the fan 180 blows air onto a portion of the pressure roll 140 that is below the center of rotation of the pressure roll 140. Furthermore, since the inclined portion 188b of the ceiling plate 188 of the guide portion 184 is inclined with respect to the horizontal direction, the fan 180 blows air onto the pressure roll 140 so that the blowing direction of the air is downward with respect to the horizontal direction.

[0088] 9, the pressure roll 140 rotates counterclockwise, and the fan 180 blows air onto the pressure roll 140 so that the air flows in the rotation direction E of the pressure roll 140.

[0089] [Prevention member 190] 9, the prevention member 190 is disposed downstream of an opposing position N where the pressure roll 140 and the heating roll 130 oppose each other in the rotation direction E of the pressure roll 140, and upstream of a portion of the pressure roll 140 where air is blown by the fan 180. The prevention member 190 opposes the pressure roll 140 in the radial direction of the pressure roll 140, and extends in the depth direction of the device.

[0090] This prevention member 190 includes a suppression plate 192 that suppresses the air blown by the fan 180 to the pressure roll 140 from moving along the outer circumferential surface of the pressure roll and flowing toward the sheet member P, and a curved plate 194 on which an opposing curved surface 194a that faces the rotating storage section 140a is formed. The suppression plate 192 is an example of a suppression member, the curved plate 194 is an example of a forming member, and the opposing curved surface 194a is an example of a facing portion.

[0091] The suppression plate 192 has a rectangular shape extending in the depth direction of the device when viewed from above, with the plate thickness direction being the up and down direction. A curved plate 194 is attached to one end of the suppression plate 192 in the device width direction.

[0092] The curved plate 194 extends in the device depth direction and has an arc-shaped cross section. When the curved surface 194a faces the storage portion 140a in the radial direction of the pressure roll 140, the curved surface 194a is formed so as to entirely cover the storage portion 140a when the curved plate 194 is viewed from the outside in the radial direction (see FIG. 13).

[0093] In this configuration, when the sheet material P passes through the opposing position N between the pressure roll 140 and the heating roll 130, the gripper 76 gripping the leading edge of the sheet material P is stored in the storage section 140a as shown in Fig. 9. Then, the gripper 76 rotates while being stored in the storage section 140a as shown in Fig. 10, and releases the grip on the leading edge of the sheet material P when the leading edge of the sheet material P passes through the opposing position N where the pressure roll 140 and the heating roll 130 face each other.

[0094] Here, if the grip of the leading edge of the sheet material P by the gripper 76 is released and air is blown onto the sheet material P, it is conceivable that the traveling posture of the sheet material P will change, causing a conveyance failure. However, the suppression plate 192 of the prevention member 190 suppresses the air blown onto the pressure roll 140 by the fan 180 from flowing along the outer circumferential surface of the pressure roll 140 toward the sheet material P being conveyed.

[0095] 11, the gripper 76 rotates while being accommodated in the accommodation portion 140a, and the accommodation portion 140a faces the opposing curved surface 194a of the curved plate 194. In addition, the leading end portion of the sheet member P is sandwiched between the transport rolls 64a.

[0096] Here, it is conceivable that the air blown onto the pressure roll 40 will flow through the storage section 140a toward the sheet material P, causing a change in the running posture of the sheet material P and resulting in poor conveyance. However, the curved plate 194 prevents air from flowing through the storage section 140a toward the sheet material P. Specifically, the curved plate 194 prevents air from freely flowing in and out of the storage section 140a, thereby preventing air from flowing through the storage section 140a toward the sheet material P.

[0097] Furthermore, the gripper 76 rotates while being accommodated in the accommodation portion 140a, and the accommodation portion 140a passes through the blowing port 180a of the fan 180, as shown in FIG.

[0098] (action) Next, the functions of the fan 180 and the prevention member 190 provided in the fixing device 100 will be described using the results of an analysis of the air flow generated by the fan 180. First, the configuration of the fixing device 300 according to the comparative embodiment and the results of the analysis will be described, and then the results of the analysis of the fan 180 and the prevention member 190 provided in the fixing device 100 according to the present embodiment will be described.

[0099] [Fixing device 300 according to a comparative example] The configuration of the fixing device 300 according to the comparative embodiment will be described mainly with respect to the differences from the configuration of the fixing device 100 according to the present embodiment. As shown in FIG. 16, the fixing device 300 includes a fan 380 and does not include a prevention member. The fan 380 extends in the device depth direction and includes a fan body 182 and a guide portion 384. The guide portion 384 is cylindrical and includes a ceiling plate 388 having a horizontal portion 188a, a bottom plate 186, and a pair of side plates (not shown). Thus, the guide portion 384 does not include an inclined portion. The ceiling plate 388, the bottom plate 186, and the pair of side plates form an outlet 380a of the fan 380.

[0100] The analysis results of fixing device 300 according to the comparative embodiment are shown in FIG. 17. The direction of the arrows in the figure indicates the direction in which the air flows. The thickness of the arrows indicates the flow speed. Specifically, the thicker the arrow, the faster the flow speed is compared with a thinner arrow. As shown in the analysis results of FIG. 17, the air blown out from outlet 380a of fan 380 does not have an inclined portion (see FIG. 8), so it flows horizontally as it is and is blown onto pressure roll 140.

[0101] The air blown onto the pressure roll 140 flows along the outer circumferential surface of the rotating pressure roll 140. Specifically, the air blown onto the pressure roll 140 flows to the downstream side in the rotation direction of the pressure roll 140 and to the upstream side in the rotation direction of the pressure roll 140.

[0102] The air that has flowed to the upstream side in the rotation direction of the pressure roll 140 flows directly upward and reaches the transport path 58 for the sheet member P.

[0103] [Fixing device 100 according to this embodiment] The analysis results of the fixing device 100 according to this embodiment are shown in Fig. 14 and Fig. 15. As shown in the analysis results in Fig. 14, in a state in which the gripper 76 faces the heating roll 130 and is accommodated in the accommodation section 140a, the air blown out from the outlet 180a of the fan 180 flows downward relative to the horizontal direction and is blown onto the pressure roll 140.

[0104] The air blown onto the pressure roll 140 flows along the outer circumferential surface of the rotating pressure roll 140. Specifically, the air blown onto the pressure roll 140 flows to the downstream side in the rotation direction of the pressure roll 140 and to the upstream side in the rotation direction of the pressure roll 140.

[0105] Most of the air that has flowed upstream in the rotation direction of the pressure roll 140 hits the suppression plate 192 of the prevention member 190 and is suppressed from flowing toward the transport path 58. Another part of the air that has flowed upstream in the rotation direction of the pressure roll 140 flows between the curved plate 194 of the prevention member 190 and the outer circumferential surface of the pressure roll 140 toward the transport path 58. However, due to flow path resistance generated by the curved plate 194 and the pressure roll 140, the air that flows toward the transport path 58 does not reach the transport path 58.

[0106] 15, when the pressure roll 140 rotates and the accommodation section 140a in which the gripper 76 is accommodated faces the curved plate 194 of the prevention member 190, the curved plate 194 suppresses air flowing through the accommodation section 140a toward the sheet material P. Specifically, the curved plate 194 suppresses air flowing through the accommodation section 140a toward the sheet material P by suppressing air from freely flowing in and out of the accommodation section 140a. In this way, the curved plate 194 suppresses air flowing through the accommodation section 140a toward the sheet material P.

[0107] (summary) As described above, in the fixing device 100, the fan 180 cools the pressure roll 140 by blowing air in a direction different from the direction toward the opposing position N where the pressure roll 140 and the heating roll 130 face each other. In other words, the fan 180 cools the pressure roll by blowing air in a direction different from the direction toward the sheet member P released from gripping by the gripper 76. This suppresses conveyance defects occurring in the conveyed sheet member P compared to the case where the air blown onto the pressure roll to cool the pressure roll directly hits the sheet member P released from gripping by the gripper 76.

[0108] In the fixing device 100, the pressure roll 140 faces the heating roll 130 from below, and the fan 180 blows air onto the pressure roll 140 at a portion below the center of rotation of the pressure roll 140. This suppresses transport defects occurring in the transported sheet member P, as compared to a case in which the fan blows air onto the pressure roll at a portion above the center of rotation of the pressure roll.

[0109] Furthermore, in the fixing device 100, the fan 180 blows air onto the pressure roll 140 so that the air flows in the rotation direction E of the pressure roll 140. This prevents the air from flowing toward the sheet member P, as compared to a case in which the fan blows air onto the pressure roll so that the air is returned by the rotation of the pressure roll, thereby suppressing transport defects occurring in the sheet member P being transported.

[0110] Moreover, in the fixing device 100, the fan 180 blows air in a horizontally downward direction toward the pressure roll 140. This prevents air from flowing toward the sheet member P, as compared to a case in which the fan blows air in a horizontally upward direction toward the pressure roll, thereby suppressing conveyance defects occurring in the sheet member P being conveyed.

[0111] Furthermore, in the fixing device 100, a suppression plate 192 is provided that suppresses the air blown by the fan 180 onto the pressure roll 140 from flowing toward the sheet member P being transported along the outer circumferential surface of the pressure roll 140. This suppresses transport defects occurring in the transported sheet member P compared to a case where air flows freely along the outer circumferential surface of the pressure roll toward a portion of the sheet member P that has passed the opposing position. In other words, compared to a case where a flow path is secured through which air flows along the outer circumferential surface of the pressure roll toward a portion of the sheet member P that has passed the opposing position, transport defects occurring in the transported sheet member P are suppressed.

[0112] Furthermore, the fixing device 100 is provided with a curved plate 194 having an opposing curved surface 194a formed thereon that faces the rotating storage section 140a. This prevents air from flowing through the storage section 140a toward the sheet material P, as compared to a case where the air blown onto the pressure roll flows freely into and out of the storage section, thereby preventing transport defects occurring in the transported sheet material P. In other words, compared to a case where no member is provided for preventing the air blown onto the pressure roll from flowing into the storage section, this prevents air from flowing through the storage section 140a toward the sheet material P, as compared to a case where no member is provided for preventing the air blown onto the pressure roll from flowing into the storage section, thereby preventing transport defects occurring in the transported sheet material P.

[0113] In the fixing device 100, when the opposing curved surface 194a faces the storage section 140a in the radial direction of the pressure roll 140, the opposing curved surface 194a covers the entire storage section 140a when viewed from the outside in the radial direction of the pressure roll 140. As a result, compared to a case in which a part of the storage section is visible from around the curved plate when viewed from the outside in the radial direction of the pressure roll when the opposing curved surface faces the storage section, air is prevented from flowing through the storage section 140a to the sheet material P side, thereby suppressing conveyance defects occurring in the sheet material P being conveyed.

[0114] In addition, in the image forming apparatus 10, the transport posture of the sheet material P is stabilized, thereby reducing paper jams of the sheet material P, compared to a case where the image forming apparatus 10 is equipped with a fixing device that blows air directly onto the sheet material P that has been released from gripper 76 in order to cool the pressure roll.

[0115] Although the present disclosure has been described in detail with respect to a specific embodiment, it is clear to a person skilled in the art that the present disclosure is not limited to the embodiment, and various other embodiments are possible within the scope of the present disclosure. For example, in the above embodiment, the fan 180 blows air onto the pressure roll 140 so that the air flows in the rotation direction E of the pressure roll 140, but the air may be blown so that the air is pushed back against the rotating pressure roll. However, in this case, the effect of blowing air onto the pressure roll 140 so that the air flows in the rotation direction E of the pressure roll 140 is not achieved.

[0116] In the above embodiment, the fan 180 blows air downward relative to the horizontal direction toward the pressure roll 140, but the air may be blown horizontally or upward relative to the horizontal direction. However, in this case, the effect of blowing air downward relative to the horizontal direction is not achieved.

[0117] In the above embodiment, air is blown onto the pressure roll 140 using the fan 180, but air may be blown onto the pressure roll 140 using a blower or the like.

[0118] In the above embodiment, the pressure roll 140 faces the heating roll 130 from below, but the pressure roll 140 may face the heating roll from a side other than the below. In this case, the effect achieved by the pressure roll 140 facing the heating roll 130 from below is not achieved.

[0119] In the above embodiment, the suppression plate 192 is provided to suppress the air blown by the fan 180 to the pressure roll from flowing along the outer circumferential surface of the pressure roll 140 toward the sheet member P, but the suppression plate 192 does not have to be provided. In this case, however, the effect achieved by providing the suppression plate 192 is not achieved.

[0120] In addition, in the above embodiment, the curved plate 194 is provided with the opposing curved surface 194a that faces the rotating storage portion 140a, but the curved plate 194 may not be provided. In this case, however, the effect achieved by providing the curved plate 194 is not achieved.

[0121] Also, although not specifically described in the above embodiment, in order to form images on both sides of the sheet material P, an inversion path for inverting the sheet material P may be provided downstream of the opposing position N, an image may be formed on the back side of the sheet material P, and the sheet material P with the image formed on the back side may pass through the opposing position N again.

[0122] In addition, in the above embodiment, a conveying roll 64b that clamps and conveys the sheet material P is provided downstream of the opposing position N in the conveying direction of the sheet material P, but a belt conveying member that adsorbs the sheet material P to an endless belt and conveys it may also be provided.

[0123] (((1))) A conveying unit that conveys the recording medium; a heating roll that rotates to heat the recording medium transported by the transport unit; a pressure roll disposed opposite the heating roll, rotating, and wrapping at least a portion of the recording medium being transported around the pressure roll and pressing the wrapped portion of the recording medium toward the heating roll; a gripping section provided in the conveying section, gripping a leading end of the recording medium being conveyed, and releasing the grip of the leading end of the recording medium when the recording medium passes through a position where the pressure roll and the heating roll face each other; a blowing unit that blows air in a direction different from a direction toward the recording medium that has been released from the gripping unit to cool the pressure roll; A fixing device comprising:

[0124] (((2))) The pressure roll faces the heating roll from below, The blowing unit blows air onto the pressure roll at a portion below the center of rotation of the pressure roll. The fixing device according to (((1))).

[0125] (((3))) The blowing unit blows air onto the pressure roll so that the air flows in the rotation direction of the pressure roll. The fixing device according to (((2))).

[0126] (((4))) The blowing unit blows air downward relative to the horizontal direction. The fixing device according to (((3))).

[0127] (((5))) a suppression member is provided downstream of the opposing position in the rotation direction of the pressure roll and upstream of the pressure roll of the portion to which air is blown by the blowing unit, the suppression member suppressing the air blown to the pressure roll by the blowing unit from flowing along the outer circumferential surface of the pressure roll and reaching the portion of the recording medium that has passed the opposing position; The fixing device according to any one of (((2))) to (((4))).

[0128] (((6))) The pressure roll has an outer circumferential surface formed with a recessed accommodation portion for accommodating the gripping portion, a forming member disposed downstream of the opposing position in the rotation direction of the pressure roll and upstream of the pressure roll of a portion to which air is blown by the blowing unit, the forming member having an opposing portion formed to face the rotating storage unit; The fixing device according to any one of (((2))) to (((5))).

[0129] (((7))) When the forming member is viewed from the outside in the radial direction of the pressure roll in a state in which the facing portion faces the storage portion, the facing portion entirely covers the storage portion. The fixing device according to (((6))).

[0130] (((8))) a transfer section for transferring a toner image onto a recording medium; A fixing device according to any one of ((1))) to (((7))) that fixes a toner image transferred to a recording medium onto the recording medium; An image forming apparatus comprising:

[0131] According to the fixing device of (((1))), it is possible to suppress transport defects occurring in the transported recording medium, compared to a case in which the air blown onto the pressure roll to cool the pressure roll directly hits the recording medium that has been released from the gripping portion.

[0132] According to the fixing device of (((2))), it is possible to suppress transport defects that occur in the recording medium being transported, compared to a case in which the blowing section blows air onto the part of the pressure roll that is above the center of rotation of the pressure roll.

[0133] According to the fixing device of (((3))), it is possible to suppress transport problems occurring in the recording medium being transported, compared to a case in which the blowing section blows air onto the pressure roll so that the air is returned by the rotating pressure roll.

[0134] According to the fixing device of (((4))), transport defects occurring in the transported recording medium can be suppressed, compared to a case in which the blowing section blows air upward with respect to the horizontal direction.

[0135] According to the fixing device of (((5))), transport defects occurring in the recording medium being transported can be suppressed compared to a case in which the air blown onto the pressure roll flows freely along the outer peripheral surface of the pressure roll to the portion of the recording medium that has passed the opposing position.

[0136] According to the fixing device of (((6))), it is possible to suppress transport problems occurring in the recording medium being transported, compared to a case in which the air blown against the pressure roll freely flows in and out of the storage section.

[0137] According to the fixing device of (((7))), when the opposing curved surface is facing the storage section and the forming member is viewed from the radial outside of the pressure roll, transport problems occurring in the recording medium being transported can be suppressed compared to a case in which part of the storage section can be seen from around the forming member.

[0138] According to the image forming apparatus of (((8))), clogging of the recording medium can be suppressed compared to a case where the image forming apparatus is equipped with a fixing device that blows air directly onto the recording medium after the recording medium has been released from its grip by the gripping section. [Explanation of symbols]

[0139] 10 Image forming device 30 Transfer device (an example of a transfer section) 66 Chain gripper (an example of a conveying unit) 76 Gripper (an example of a gripping part) 100 Fixing device 130 Heating Roll 140 Pressure Roll 140a Storage section 180 Fan (Example of blowing section) 192 Restraint plate (an example of a restraint member) 194 Curved plate (an example of a forming member) 194a Opposing curved surface (an example of an opposing part) N Opposite position

Claims

1. A conveying unit that conveys the recording medium; a heating roll that rotates to heat the recording medium transported by the transport unit; a pressure roll disposed opposite the heating roll, rotating, and wrapping at least a portion of the recording medium being transported around the pressure roll and pressing the wrapped portion of the recording medium toward the heating roll; a gripping section provided in the conveying section, gripping a leading end of the recording medium being conveyed, and releasing the grip of the leading end of the recording medium when the recording medium passes through a position where the pressure roll and the heating roll face each other; a blowing unit that blows air in a direction different from a direction toward the recording medium that has been released from the gripping unit to cool the pressure roll; A fixing device comprising:

2. The pressure roll faces the heating roll from below, The blowing unit blows air onto the pressure roll at a portion below the center of rotation of the pressure roll. The fixing device according to claim 1 .

3. The blowing unit blows air onto the pressure roll so that the air flows in the rotation direction of the pressure roll. The fixing device according to claim 2 .

4. The blowing unit blows air downward relative to the horizontal direction. The fixing device according to claim 3 .

5. a suppression member is provided downstream of the opposing position in the rotation direction of the pressure roll and upstream of the pressure roll of the portion to which air is blown by the blowing unit, the suppression member suppressing the air blown to the pressure roll by the blowing unit from flowing along the outer circumferential surface of the pressure roll and reaching the portion of the recording medium that has passed the opposing position; The fixing device according to claim 2 .

6. The pressure roll has an outer circumferential surface formed with a recessed accommodation portion for accommodating the gripping portion, a forming member disposed downstream of the opposing position in the rotation direction of the pressure roll and upstream of the pressure roll of a portion to which air is blown by the blowing unit, the forming member having an opposing portion formed to face the rotating storage unit; The fixing device according to claim 2 .

7. When the forming member is viewed from the outside in the radial direction of the pressure roll in a state in which the facing portion faces the storage portion, the facing portion entirely covers the storage portion. The fixing device according to claim 6 .

8. a transfer section for transferring a toner image onto a recording medium; The fixing device according to any one of claims 1 to 7, which fixes the toner image transferred onto the recording medium onto the recording medium; An image forming apparatus comprising:

Images