JP7172307B2 - Fixing device, image forming device - Google Patents

Description

The present invention relates to fixing devices and image forming apparatuses.

The heating device described in Patent Document 1 includes a flat heating body, a heater holder that supports the heating body on the outer surface, and a heat-resistant film that is pressed against the heating body to convey a material to be heated that is introduced into the pressure contact portion. and a rotating body. Between the heating body and the heater holder in the area where the heating body and the heater holder come into contact and receive force, in the non-paper-passing area in the minimum size of the material to be heated that can be passed, and in the range where the energized heating resistor exists. is interposed by a curable resin.

JP-A-2001-23756

2. Description of the Related Art There is a fixing device that includes a rotating endless belt and a plate-like heat generating plate having a heat generating portion extending in the axial direction of the endless belt, the surface of which is in contact with the inner peripheral surface of the endless belt. Further, the fixing device includes a pressure member that forms a fixing nip with the endless belt and presses the recording medium against the outer peripheral surface of the endless belt, and a resin that contacts the entire back surface of the heat generating plate to hold the heat generating plate. and a holding portion made of

In such a fixing device, when fixing an image on a recording medium of the smallest size, the heat of the heating plate generated in the portion not facing the recording medium is not transmitted to the recording medium. is transmitted to the holding part made of steel. Then, the portion of the holding portion to which the heat is transferred may be melted and deformed by the heat.

An object of the present invention is to suppress melting and deformation of a holding portion when fixing an image on a recording medium of a minimum size, as compared with the case where the holding portion is in contact with the entire back surface of a heating plate. is.

A fixing device according to a first aspect of the present invention includes an endless belt that rotates in a circumferential direction, and a heating plate that extends in the axial direction of the endless belt and that is in contact with the inner peripheral surface of the endless belt to generate heat. a pressurizing unit arranged on the opposite side of the heat generating plate with the endless belt interposed therebetween for pressing the conveyed recording medium against the outer peripheral surface of the endless belt; A holding part made of resin for holding, wherein a gap is formed outside a range in which the smallest size recording medium to be conveyed passes in the axial direction, connecting the back surface of the heating plate and a space open to the outside. and the holding portion.

A fixing device according to a second aspect of the present invention is the fixing device according to the first aspect, wherein in a cross section crossing the axial direction, the gap faces the entire rear surface of the heating plate. Characterized by

A fixing device according to a third aspect of the present invention is characterized in that, in the fixing device according to the second aspect, the gap faces a side surface of the heating plate in the cross section.

A fixing device according to a fourth aspect of the present invention is the fixing device according to any one of the first to third aspects, wherein at least one of the spaces is open to the outside in the axial direction. do.

A fixing device according to a fifth aspect of the present invention is the fixing device according to the fourth aspect, wherein the pressure unit rotates, and the drive unit that generates a rotational force for rotating the pressure unit rotates in the axial direction. , and the space is open at least at the other side in the axial direction opposite to the side on which the drive section is arranged.

A fixing device according to a sixth aspect of the present invention is characterized in that, in the fixing device according to the fourth aspect, both of the spaces are open to the outside in the axial direction.

An image forming apparatus according to a seventh aspect of the present invention includes a forming unit that forms an image on a recording medium of a plurality of sizes including a minimum size, and first to sixth aspects that fix the image formed on the recording medium to the recording medium. and a fixing device according to any one of the aspects .

According to the fixing device of the first aspect of the present invention, the holding portion melts when fixing an image on a recording medium of the minimum size, compared to the case where the holding portion is in contact with the entire back surface of the heating plate. deformation can be suppressed.

According to the fixing device of the second aspect of the present invention, in the cross section that intersects with the axial direction, the holding portion is melted and deformed compared to the case where the gap faces only a part of the back surface of the heating plate. can be suppressed.

According to the fixing device of the third aspect of the present invention, it is possible to prevent the holding portion from being melted and deformed as compared with the case where the side surface of the heating plate is in contact with the holding portion.

According to the fixing device of the fourth aspect of the present invention, it is possible to prevent the holding portion from being melted and deformed in the axial direction, compared to the case where both spaces are closed.

According to the fixing device of the fifth aspect of the present invention, it is possible to prevent the holding section from being melted and deformed, as compared with the case where only the driving section side of the space is open.

According to the fixing device of the sixth aspect of the present invention, it is possible to prevent the holding portion from being melted and deformed, as compared with the case where only one side of the space is open to the outside in the axial direction.

According to the image forming apparatus of the seventh aspect of the present invention, the quality of the output image on the recording medium of the maximum size deteriorates compared to the case where the fixing device according to any one of the first to sixth aspects is not provided. can be suppressed.

4 is a cross-sectional view showing a portion where a gap is formed in the fixing device according to the exemplary embodiment of the invention; FIG. 3 is a cross-sectional view showing a portion where a detection member (temperature sensor) is arranged in the fixing device according to the exemplary embodiment of the invention; FIG. 1 is a cross-sectional view showing a fixing device according to an embodiment of the invention; FIG. 3 is a plan view showing a heat generating plate provided in the fixing device according to the exemplary embodiment of the invention; FIG. 3 is a perspective view showing a holding member and the like provided in the fixing device according to the exemplary embodiment of the invention; FIG. 1 is a front view showing a fixing device according to an embodiment of the invention; FIG. 3 is a block diagram showing a control system of a control unit provided in the fixing device according to the embodiment of the invention; FIG. 1 is a schematic configuration diagram showing an image forming apparatus according to an embodiment of the invention; FIG.

An example of a fixing device and an image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 to 8. FIG. An arrow H shown in the drawing indicates the vertical direction of the device, an arrow W indicates the width direction of the device (horizontal direction), and an arrow D indicates the depth direction of the device (horizontal direction).

(overall structure)
As shown in FIG. 8, in the image forming apparatus 10 according to the present embodiment, a storage portion for storing a sheet member P as a recording medium is arranged from the lower side to the upper side in the vertical direction (direction of arrow H). 14, a conveying unit 16 that conveys the sheet member P accommodated in the accommodating unit 14, and an image forming unit 20 that forms an image on the sheet member P conveyed from the accommodating unit 14 by the conveying unit 16, in this order. are provided.

[Accommodating portion 14]
The storage unit 14 is provided with a storage member 26 that can be pulled out from the main body 10A of the image forming apparatus 10 toward the front side in the depth direction of the apparatus. Further, the storage unit 14 is provided with a delivery roll 30 that delivers the sheet members P stacked on the storage member 26 to the transport path 28 that constitutes the transport unit 16 .

[Conveyor 16]
The transport unit 16 is provided with a plurality of transport rolls 32 that transport the sheet member P along a predetermined transport path 28 .

[Image forming unit 20]
The image forming section 20 includes four image forming units 18Y, 18M, 18C, and 18K for yellow (Y), magenta (M), cyan (C), and black (K). In the following description, Y, M, C, and K may be omitted when Y, M, C, and K need not be distinguished.

The image forming unit 18 for each color includes an image carrier 36, a charging roll 38 that charges the surface of the image carrier 36, and an exposure device 42 that irradiates the charged image carrier 36 with exposure light. . Further, the image forming section 20 is provided with a developing device 40 that develops the electrostatic latent image formed by exposing the charged image carrier 36 by the exposing device 42 and visualizes it as a toner image.

The image forming unit 20 also has an endless transfer belt 22 that rotates in the direction of arrow A in the drawing, and a primary transfer roll 44 that transfers the toner images formed by the image forming units 18 of each color onto the transfer belt 22 . are provided. Further, the image forming unit 20 includes a secondary transfer roll 46 that transfers the toner image on the transfer belt 22 to the sheet member P, and a fixing device 50 that heats and presses the sheet member P to fix the toner image onto the sheet member P. and are provided. Details of the fixing device 50 will be described later. The image forming unit is an example of a forming section.

(Action of image forming apparatus)
The image forming apparatus 10 forms an image as follows.
First, the charging roll 38 of each color to which a voltage is applied contacts the surface of the image carrier 36 of each color and uniformly negatively charges the surface of the image carrier 36 with a predetermined potential. Subsequently, based on data input from the outside, the exposure device 42 irradiates the surface of the charged image carrier 36 of each color with exposure light to form an electrostatic latent image.

Thereby, an electrostatic latent image corresponding to the data is formed on the surface of the image carrier 36 for each color. Further, the developing device 40 for each color develops this electrostatic latent image and visualizes it as a toner image. Further, the toner images formed on the surface of the image carrier 36 of each color are transferred onto the transfer belt 22 by the primary transfer roll 44 .

Then, the sheet member P delivered from the storage member 26 to the transport path 28 by the delivery roll 30 is delivered to the transfer position T where the transfer belt 22 and the secondary transfer roll 46 are in contact with each other. At the transfer position T, the toner image on the surface of the transfer belt 22 is transferred to the sheet member P as the sheet member P is sandwiched and conveyed between the transfer belt 22 and the secondary transfer roll 46 .

The toner image transferred onto the sheet member P is fixed onto the sheet member P by the fixing device 50 . Then, the sheet member P on which the toner image has been fixed is discharged to the outside of the apparatus main body 10A by the conveying rolls 32 .

(main part configuration)
Next, the fixing device 50 will be described.
The fixing device 50 is detachable from the apparatus main body 10A, and as shown in FIG. and a heating unit 60 facing the pressure roll 52 in the device width direction. Further, the fixing device 50 includes a control section 98 (see FIG. 7) that controls each section. Motor 58 is an example of a drive unit.

[Pressure roll 52]
As shown in FIG. 3, the pressure roll 52 has a metal shaft portion 54 extending in the depth direction of the apparatus, a cylindrical elastic layer 56 into which the shaft portion 54 is inserted, and the elastic layer 56. and a release layer (not shown). As shown in FIG. 6, the shaft portion 54 protrudes outward from both ends of the elastic layer 56, and a gear 54a is attached to the protruding portion on the far side (right side in the drawing) in the depth direction of the device. there is

The shaft portion 54 is made of, for example, a metal material such as steel, stainless steel, or aluminum, the elastic layer 56 is made of, for example, a rubber material, and the release layer is made of, for example, ethylene fluoride-perm. It is made of fluoroalkoxyethylene copolymer (PFA) or the like. The pressure roll 52 is an example of a pressure section.

The pressure roll 52 is grounded and biased toward the heating section 60 by a biasing member (not shown). As a result, the pressure roller 52 presses the sheet member P having the toner image transferred thereon against the outer peripheral surface of the endless belt 62, which will be described later.

[Motor 58]
As shown in FIG. 6, the motor 58 is arranged on the back side of the pressure roll 52 in the depth direction of the apparatus. A gear 58a attached to the motor 58 meshes with the gear 54a. In this configuration, the motor 58 rotates while generating heat. Then, the pressure roll 52 shown in FIG. 3 rotates in the direction of arrow R1 (clockwise) in FIG. In this embodiment, the pressure roll 52 rotates so that the outer peripheral surface of the elastic layer 56 has a peripheral speed of 230 [mm/sec].

[Heating unit 60]
As shown in FIG. 3, the heating unit 60 has a cylindrical endless belt 62 extending in the depth direction of the apparatus, a heat generating plate 64 that generates heat to heat the endless belt 62, and a heat generating plate 64. and a holding member 90 . Furthermore, the heating unit 60 includes a frame 80 that supports the holding member 90, a detection member 82 (see FIG. 2) that detects the temperature of the heating plate 64, and a thermostat 84 (see FIG. 1). The holding member 90 is an example of a holding portion.

-Endless belt 62-
The endless belt 62 is in contact with the pressure roll 52 on its outer peripheral surface, as shown in FIG. In this embodiment, for example, the endless belt 62 is made of a polyimide resin having a fluorine-coated surface, and the thickness of the endless belt 62 is 100 [μm].

Cylindrical support members (not shown) for supporting the inner peripheral surface of the endless belt 62 are arranged at both ends of the endless belt 62 in the longitudinal direction. Further, the inner peripheral surface of the endless belt 62 is coated with lubricating oil S (an example of a liquid, such as silicon oil) in order to reduce the frictional resistance with the heating plate 64 .

In this configuration, the endless belt 62 rotates (circulates) in the direction of an arrow R2 (counterclockwise) in the figure while being driven by the rotating pressure roll 52 while maintaining its circular shape.

- Heating plate 64 -
As shown in FIG. 3, the heating plate 64 is arranged on the opposite side of the pressure roll 52 with the endless belt 62 interposed therebetween, and is in contact with the inner peripheral surface of the endless belt 62 at its surface. The heating plate 64 is a plate-like member whose plate surface faces the device width direction, and extends from one end side to the other end side of the endless belt 62 in the device depth direction. When viewed from the plate thickness direction, the heating plate 64 has a rectangular shape extending in the depth direction of the device, as shown in FIG.

The heating plate 64 has an electrically insulating base material 66, an insulating film 68 made of a heat-resistant resin material, and a heat transfer layer 70 (see FIG. 3) for transferring heat in the depth direction of the device. . Further, the heating plate 64 has a pair of voltage application electrodes 72 and a conductive portion 74 through which current flows when voltage is applied to the electrodes 72 . The conductive portion 74 is formed with two resistive heat generating portions 74a (hatched portions in the drawing) that generate heat when current flows. Here, insulating means having an electric conductivity of 1×10 −10 [S/m] or less.

The base material 66 is an electrically insulating ceramic compact. Also, the pair of electrodes 72 and the conductive portion 74 are formed on the surface of the base material 66 (the surface on the inner peripheral surface side of the endless belt 62). Specifically, the pair of electrodes 72 are formed on the front side portion of the substrate 66 in the depth direction of the device, and arranged side by side in the vertical direction. Furthermore, the conducting portion 74 is formed in a U shape extending in the depth direction of the apparatus, and the electrodes 72 are arranged at both ends of the conducting portion 74 . Also, the conducting portion 74 is covered with the insulating film 68 .

Further, a resistance heating portion 74a is formed in a linear portion of the conducting portion 74. As shown in FIG. The resistive heating portion 74a is formed so as to cover a range in the depth direction of the apparatus (the width direction of the sheet member P1) through which the conveyed sheet member P of the largest size (P1 in the figure) passes.

3, the heat transfer layer 70 is formed on the rear surface of the base material 66 and is made of a material having a higher thermal conductivity than the base material 66. The heat transfer layer 70 is made of copper or aluminum, for example.

In this configuration, when a voltage is applied to the pair of electrodes 72, heat is generated in the resistance heating portion 74a, and the heating plate 64 generates heat. Further, the heat transfer layer 70 transfers the heat generated in the resistance heating portion 74a in the depth direction of the device, thereby suppressing temperature unevenness of the heat generating plate 64 in the depth direction of the device.

-Holding member 90-
As shown in FIG. 3, the holding member 90 is arranged inside the endless belt 62 and on the opposite side of the pressure roll 52 with the heating plate 64 interposed therebetween. The holding member 90 is made of, for example, a resin material such as LCP (liquid crystal polymer), and extends in the depth direction of the apparatus. A cross section perpendicular to the longitudinal direction of the holding member 90 is U-shaped with an opening on the side opposite to the pressure roll 52 side. Furthermore, the space 110 inside the U-shaped holding member 90 is open to the outside in the device depth direction. Here, the space 110 is a space inside the endless belt 62, and being open to the outside means, as shown in FIG. A member (lid member) is not provided, and the space 110 is continuously connected to the space outside the fixing device 50 in the depth direction of the device. Further, the outside of the fixing device 50 is an area not surrounded by the inner peripheral surface of the endless belt 62 .

Further, as shown in FIG. 3, the holding member 90 is formed with a contact surface 92 that contacts the rear surface of the heating plate 64 and a pair of contact surfaces 94 that contact the side surfaces of the heating plate 64 .

Further, a through hole 95 is formed in the central portion of the holding member 90 in the depth direction of the device, as shown in FIG.

As shown in FIGS. 1 and 4, in the depth direction of the apparatus (the axial direction of the endless belt 62), the holding member outside the range through which the conveyed minimum size sheet member P (P2 in the drawings) passes. A gap 96 is formed in 90 to open the back surface of the heating plate 64 to the space 110 . Specifically, the gaps 96 are formed on the depth side and the front side of the range through which the conveyed minimum size sheet member P2 passes in the depth direction of the apparatus. Each of the gaps 96 is arranged at a position overlapping with a part of the resistance heating portion 74a in the device depth direction. Note that the image forming apparatus 10 employs a so-called center registration method (pressing the recording sheet from both sides in the width direction and aligning the positions with reference to the center in the width direction).

As shown in FIGS. 4 and 5, the space 96 has a rectangular shape when viewed from the width direction of the device, and is formed by penetrating the portion of the holding member 90 that supports the heating plate 64 in the width direction of the device. ing. 1, the entire back surface of the heat generating plate 64 and the pair of side surfaces of the heat generating plate 64 are connected to the space 110 through the space 96. ing. In other words, the gap 96 faces the entire rear surface of the heat generating plate 64 and the pair of side surfaces of the heat generating plate 64 in the cross section that intersects with the device depth direction.

Thus, the gap 96 connects a portion of the heating plate 64 to the space 110 . In other words, the gap 96 functions as opening means for opening a portion of the heating plate 64 to the space 110 .

Furthermore, the air gap 96 is arranged at a position overlapping with a part of the resistance heating portion 74a in the device depth direction. In this way, the space 96 overlaps with a part of the resistance heating portion 74a, so that the heat generated by the portion of the resistance heating portion 74a that overlaps with the space 96 is released from the heating plate 64 to the space 110 through the space 96. It is designed to be In other words, the air gap 96 functions as a radiating means for radiating heat to the space 110 .

Regarding the gap 96, when fixing the toner image on the minimum size sheet member P2, the heat generated in the outer portion of the range through which the minimum size sheet member P2 passes is released to the space 110. Wider is preferred. On the other hand, when fixing the toner image on the sheet member P1 of the maximum size, the gap 96 is preferably narrow from the viewpoint of fixing the toner image on the sheet member P1 of the maximum size.

Therefore, in the device depth direction, it is preferable that the space 96 overlaps 60% or more and 98% or less of the resistive heating portion 74a outside the range where the sheet member P2 of the minimum size passes. It is more preferable to overlap 70% or more and 95% or less, and it is particularly preferable to overlap 80% or more and 90% or less.

In this configuration, when the heating plate 64 generates heat, the heat in the portion of the heating plate 64 where the gap 96 is formed is released to the space 110 via the gap 96 without being transmitted to the holding member 90 . Further, since the space 110 is open to the outside in the device depth direction, the air in the space 110 flows in the device depth direction.

-Frame 80-
The frame 80 is arranged inside the endless belt 62 and on the opposite side of the heating plate 64 with the holding member 90 interposed therebetween, as shown in FIG. The frame 80 is formed by bending a sheet metal and extends in the depth direction of the device. A cross section perpendicular to the longitudinal direction of the frame 80 is U-shaped with an opening on the side of the holding member 90 .

Furthermore, the frame 80 supports the holding member 90 by attaching the front end portion of the holding member 90 to the front end portion of the U-shaped frame 80 with a mounting member such as an adhesive (not shown). is doing. A region surrounded by the frame 80 and the holding member 90 is the aforementioned space 110 .

Both ends of the frame 80 in the longitudinal direction protrude from the endless belt 62, and the protruding portions are fixed to frame members (not shown).

- Detection member 82 -
As shown in FIG. 2 , the detection member 82 is partially arranged in a through hole 95 formed in the holding member 90 and is in contact with the rear surface of the heating plate 64 . Thereby, the detection member 82 detects the temperature of the heating plate 64 . Then, the control unit 98 controls on/off of a power switch (not shown) so that the temperature of the heat generating plate 64 detected by the detection member 82 falls within a predetermined range, applies voltage to the electrode 72, Alternatively, the application is stopped.

-Thermostat 84-
A pair of thermostats 84 are provided, and as shown in FIG. When the temperature of the heating plate 64 detected by the thermostat 84 reaches the threshold temperature, the thermostat 84 stops applying the voltage to the electrode 72 .

[Control unit 98]
As shown in FIG. 7, the control unit 98 controls on/off of a power switch (not shown) based on the detection result of the detection member 82 to control the application of voltage to the electrode 72. . The control of each unit by the control unit 98 will be described together with the operation described later.

(action)
Next, operation of the fixing device 50 will be described. Before the fixing device 50 starts to operate as shown in FIG. 3, voltage application to the electrode 72 (see FIG. 4) is stopped, and the pressure roll 52 is stopped.

When the toner image transferred to the sheet member P is to be fixed on the sheet member P, the control section 98 (see FIG. 7) controls the motor 58 to transmit the rotational force to the pressure roll 52 . Then, the pressure roller 52 shown in FIG. 3 rotates in the arrow R1 direction in the figure. As a result, the endless belt 62 in contact with the pressure roll 52 rotates in the direction of arrow R2 in the figure following the rotating pressure roll 52 .

When the endless belt 62 rotates, the controller 98 turns on a power switch (not shown) to start applying voltage to the electrodes 72 . As a result, heat is generated in the resistance heating portion 74a, and the heating plate 64 generates heat. Furthermore, the heating plate 64 heats the rotating endless belt 62 from the inner peripheral surface.

Then, when the temperature of the heating plate 64 detected by the detecting member 82 (see FIG. 2) reaches 200[deg. The fixing mode is changed to the fixing mode.

In the fixing mode, the toner image is fixed on the sheet member P by sandwiching and conveying the sheet member P having the toner image transferred between the heating unit 60 and the pressure roller 52 . Further, the sheet member P having the toner image transferred thereon is conveyed while being sandwiched between the heating unit 60 and the pressure roller 52, so that the heat of the heating plate 64 at the portion through which the sheet member P passes is removed. As a result, the temperature of the heating plate 64 is lowered. Therefore, the control unit 98 controls on/off of a power switch (not shown) so that the temperature of the heat generating plate 64 is 190° C. or more and 230° C. or less, for example.

Here, for example, when a toner image is to be fixed on a minimum size sheet member P2, as shown in FIG. F01) exists.

Since the heat generated in the region F01 of the resistance heating portion 74a is not taken away by the sheet member P2, when the holding member 90 is in contact with the entire back surface of the heating plate 64, the heating plate in the region F01 is It is conceivable that the temperature of 64 rises, and in region F01, the portion of holding member 90 that is in contact with heating plate 64 melts and deforms.

However, as described above, the holding member 90 has the gap 96 that connects the back surface of the heating plate 64 and the space 110 . Therefore, the heat generated in the region F01 is released to the space 110 through the air gap 96. FIG. In other words, the air gap 96 suppresses the temperature rise of the heating plate 64 in the area F01.

On the other hand, when an unexpected event occurs and the temperature of the heating plate 64 detected by the thermostat 84 reaches a threshold temperature (for example, 250[° C.]), the thermostat 84 stops applying voltage to the electrode 72. .

(summary)
As described above, in the fixing device 50, the space 96 connecting the back surface of the heating plate 64 and the space 110 is formed in the portion of the holding member 90 outside the range through which the conveyed minimum size sheet member P2 passes. ing. As described above, the air gap 96 suppresses the temperature rise of the heating plate 64 in the area F01. For this reason, compared to the case where the holding member is in contact with the entire back surface of the heating plate, the holding member 90 made of resin is less likely to melt and deform when fixing a toner image on the sheet member P2 of the minimum size. Suppressed.

Further, in the fixing device 50 , the entire rear surface of the heating plate 64 is connected to the space 110 through the gap 96 at the portion where the gap 96 is formed. Therefore, for example, compared to the case where the back surface of the heat generating plate is partially covered with the holding member, the amount of heat emitted from the heat generating plate 64 to the space 110 through the gap 96 increases, and the This prevents the holding member 90 from being melted and deformed.

Also, in the fixing device 50 , the pair of side surfaces of the heating plate 64 are connected to the space 110 via the gap 96 at the portion where the gap 96 is formed. Therefore, for example, the amount of heat emitted from the heat generating plate 64 to the space 110 through the gap 96 increases compared to the case where the side surface of the heat generating plate is in contact with the holding member. is suppressed from melting and deformation.

Further, in the fixing device 50, at least one of the spaces 110 is open to the outside in the depth direction of the device. Therefore, the air in the space 110 from which heat is released flows in the depth direction of the device and is discharged to the outside without changing the flow direction, as compared with the case where both the depth directions of the space are blocked. As a result, the amount of heat emitted from the heating plate 64 to the space 110 through the space 96 increases, so that the holding member 90 made of resin melts more than when the space is closed in both the depth direction of the apparatus. Deformation is suppressed.

Further, in the fixing device 50, both of the spaces 110 are open to the outside in the depth direction of the device. Therefore, compared to the case where only one side of the space in the depth direction of the device is open to the outside, the flow rate of the air flowing in the depth direction of the device increases, and the air is discharged from the heating plate to the space 110 through the gap 96. The amount of heat generated increases. This suppresses melting and deformation of the holding member 90 made of resin compared to the case where only one side of the space in the device depth direction is open to the outside.

In addition, in the image forming apparatus 10, melting and deformation of the holding member 90 made of resin is suppressed when the sheet member P2 of the minimum size is used, compared to when the fixing device 50 is not provided. , deterioration in the quality of the output image of the sheet member P of the maximum size is suppressed.

Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments are possible within the scope of the present invention. It is clear to those skilled in the art. For example, although not specifically described in the above embodiment, if only one side of the space 110 in the apparatus depth direction is open to the outside, the side opposite to the side where the motor 58 shown in FIG. The other should be open. As a result, heating of the air in the space 110 by the heat of the motor 58 is suppressed compared to the case where only the motor 58 side of the space is open, so that the holding member 90 made of resin is melted and deformed. is suppressed.

Also, although not specifically described in the above embodiment, the length of the space 96 on the side where the motor 58 that generates heat when operating is arranged in the device depth direction is the length of the space 96 on the opposite side in the device depth direction. It may be longer than the length. By doing so, compared to the case where the length of the gap 96 on the side where the motor 58 is arranged in the device depth direction is shorter than the length of the gap 96 on the opposite side in the device depth direction, the motor The heat of 58 suppresses the amount of heat emitted from the heating plate to space 110 via gap 96 on the motor 58 side from decreasing.

Although not specifically described in the above embodiment, the vertical length of the space 96 on the side where the motor 58 that generates heat when operating is arranged is the length of the space 96 on the opposite side in the vertical direction of the device. It may be longer than the length. By doing so, the length of the space 96 on the side where the motor 58 is arranged in the vertical direction of the device is shorter than the length of the space 96 on the opposite side in the vertical direction of the device. The heat of 58 suppresses the amount of heat emitted from the heating plate to space 110 via gap 96 on the motor 58 side from decreasing.

Moreover, although not specifically described in the above embodiment, the gap 96 may be divided. Thereby, a crosspiece is formed to partition the divided gap, and the heat generating plate is supported by this crosspiece.

Further, in the above embodiment, the gap 96 faces the side surface of the heating plate 64, but the gap does not have to face the side surface of the heating plate. In this case, the effect caused by the gap facing the side surface of the heating plate does not occur.

10 image forming device 18 image forming unit (an example of a forming unit)
50 fixing device 52 pressure roll (an example of a pressure unit)
58 motor (an example of a drive unit)
62 endless belt 64 heating plate 90 holding member (an example of a holding portion)
96 air gap 110 space

Claims (6)

an endless belt that rotates in the circumferential direction;
a heating plate extending in the axial direction of the endless belt and generating heat by coming into contact with the inner peripheral surface of the endless belt at the surface;
a pressure unit disposed on the opposite side of the heat generating plate with the endless belt interposed therebetween for pressing the conveyed recording medium against the outer peripheral surface of the endless belt;
A holding part made of resin for holding the heat generating plate in contact with the back surface of the heat generating plate, wherein the back surface of the heat generating plate and the heat generating plate and the holding part in which a gap is formed to connect the space open to the outside,
The fixing device in which the gap faces the entire rear surface of the heat generating plate in a cross section that intersects with the axial direction . 2. The fixing device according to claim 1 , wherein in the cross section, the gap faces the side surface of the heating plate. 3. The fixing device according to claim 1 , wherein at least one of the spaces is open to the outside in the axial direction. The pressure unit rotates,
a drive unit that generates a rotational force for rotating the pressure unit is arranged on one side of the pressure unit in the axial direction;
4. The fixing device according to claim 3, wherein in the axial direction, the space is open at least on the other side opposite to the side on which the drive section is arranged. 4. The fixing device according to claim 3 , wherein both of said spaces are open to the outside in said axial direction. a forming unit that forms an image on a recording medium of a plurality of sizes including a minimum size;
a fixing device according to any one of claims 1 to 5, which fixes an image formed on a recording medium to the recording medium;
image forming apparatus.

Images