JP2023168018A - Unit fixing structure, fixing device, and image forming apparatus - Google Patents

Abstract

To simplify a unit fixing structure to save space.SOLUTION: A unit fixing structure of the present invention detachably fixes a unit 100a to a device body, and the unit fixing structure inserts a projection 70 disposed on the device body into a positioning hole 69 of the unit 100a to position the unit 100a, and fixes the unit 100a in the positioned state to the device body 1a with fastening members (screws B1, B2). In the unit fixing structure, insertion holes 67, 68 for inserting the fastening members are formed in the unit 100a, the positioning hole 69 is formed below the insertion holes 67, 68, and a receiving part 70a for the fastening members is formed in the projection 70 projecting from the positioning hole 69.SELECTED DRAWING: Figure 2

Description

The present invention relates to a unit fixing structure for removably fixing a unit to an apparatus main body, and a fixing device and an image forming apparatus having the fixing structure.

2. Description of the Related Art A fixing unit of an image forming apparatus is generally removably fixed to a machine body for purposes such as replacing the unit in the event of a failure or for maintenance. The fixing unit is fixed by positioning and fastening (screwing) the fixing unit to the machine body.

If this positioning and fastening are performed using the same member, the structure of the member will become complicated and large. Therefore, positioning and fastening are often performed using separate members.

That is, the fixing unit is positioned by inserting a protrusion (locating pin) provided on the machine body into a positioning hole of the fixing unit. Further, the fixing unit is fastened by inserting a screw into the insertion hole of the fixing unit and tightening the tip of the screw into the screw hole of the machine body.

When fastening the fixing unit to the machine body with screws, the screws may fall off by mistake. The parts around the fixing unit are crowded and there are many narrow gaps. If a screw falls into such a narrow gap, it takes time to recover the screw.

Conventionally, there is a device in which a screw receiving recess is formed to prevent the screw from falling off, as disclosed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2011-107334). That is, a screw receiving recess is formed above the screw through hole, and a positioning recess is formed below. However, if the positioning recess and the screw receiving recess are formed separately, the structure becomes complicated and takes up space.

Therefore, an object of the present invention is to simplify the unit fixing structure and save space.

In order to solve the above problems, the unit fixing structure of the present invention is a unit fixing structure that removably fixes a unit to an apparatus main body, the protrusion provided on the apparatus main body being connected to a positioning hole of the unit. In the unit fixing structure, the unit is positioned by inserting the unit into the device body, and in the positioned state, the unit is fixed to the device main body by a fastening member, an insertion hole for inserting the fastening member is formed in the unit; The positioning hole is formed below the insertion hole, and the receiving portion of the fastening member is formed on the protrusion projecting from the positioning hole.

According to the present invention, the unit fixing structure can be simplified and space can be saved.

1 is a schematic configuration diagram of a color printer, which is an embodiment of an image forming apparatus. (a) A conventional perspective view, (b) an enlarged conventional view, (c) a perspective view of this embodiment, and (d) a sectional view of this embodiment, showing a unit fixing structure. FIG. 3 is a side view showing the unit fixing structure of the present embodiment. FIG. 3A is a perspective view, FIG. 1B is a vertical cross-sectional side view, and FIG. 3C is a horizontal cross-sectional plan view, showing a fixing structure of a unit having a resin cover. FIG. 2 is a schematic configuration diagram of a fixing device. FIG. 3 is an exploded perspective view of a nip forming member.

Embodiments of the present invention will be described below based on the accompanying drawings. Note that components such as members and components having the same function or shape in each drawing are given the same reference numerals as far as possible to distinguish them, and the description thereof will be omitted once it has been described.

(Image forming device)
FIG. 1 is a schematic configuration diagram showing a cross section of a color printer, which is an embodiment of an image forming apparatus 1. As shown in FIG. Although this color printer is of a tandem type in which image forming units that form a plurality of color images are arranged side by side along the extending direction of the belt, the present embodiment is not limited to this type. Furthermore, it is possible to target not only printers but also copying machines, facsimile machines, and the like.

As shown in FIG. 1, in the center of the image forming apparatus 1, photoreceptors 20Y, 20C, 20M, and 20Bk, which are image carriers, are arranged side by side. Each of the photoreceptors 20Y, 20C, 20M, and 20Bk can form images corresponding to yellow (Y), cyan (C), magenta (M), and black (Bk), respectively. Note that these image forming means have the same configuration except for the difference in developer (toner) color, so in the following description, the suffixes Y, C, M, and Bk in the reference numerals will be omitted as appropriate.

A charging member 30 , a developing device 40 , and a cleaning means 50 are provided around each photoreceptor 20 . The photoreceptor 20 is rotated clockwise, and a charging member 30 is pressed against the surface of the photoreceptor 20, and the charging member 30 rotates as the photoreceptor 20 rotates.

Further, a predetermined bias voltage is applied to the charging member 30 by a high-voltage power supply, so that the surface of the photoreceptor 20 that is rotationally driven can be uniformly charged. Note that the photoreceptor 20, the charging member 30, the developing device 40, and the cleaning means 50 are each arranged to be detachable from the image forming apparatus 1.

An exposure device 8 is provided diagonally below the four photoreceptors 20 and in parallel therewith. This exposure device 8 has constituent members such as a light source, a polygon mirror, an f-theta lens, and a reflecting mirror.

The exposure device 8 exposes each photoreceptor 20 charged by the charging member 30 to light based on image information formed according to image data of each color toner, and forms an electrostatic latent image on each photoreceptor 20. produce. The electrostatic latent image formed on the photoconductor 20 using the exposure device 8 is developed and visualized by applying toner of each color when the photoconductor 20 rotates and passes through the development device 40. .

Note that toner bottles 9Y, 9C, 9M, and 9Bk filled with yellow, cyan, magenta, and black toners are arranged above the interior of the image forming apparatus 1. A predetermined amount of toner is replenished from these toner bottles 9Y, 9C, 9M, and 9Bk to the respective color developing devices 40Y, 40C, 40M, and 40Bk via a transport path (not shown).

Furthermore, an endless belt-shaped intermediate transfer belt 11 configured as an intermediate transfer member is arranged opposite to the photoreceptor 20 of each image forming means, and each photoreceptor 20 is in contact with the surface of this intermediate transfer belt 11. ing. The intermediate transfer belt 11 is configured to be wound around a plurality of support rollers (for example, support rollers 72, 73, etc.).

In the illustrated example, the support roller 73 is connected to a drive motor as a drive source (not illustrated), and the intermediate transfer belt 11 is rotated counterclockwise in the figure by the drive of this drive motor, and accordingly, the intermediate transfer belt 11 is moved counterclockwise in the figure. The rotatable support roller 73 also rotates. Further, a primary transfer roller 12 is arranged inside the intermediate transfer belt 11 and is positioned opposite to the photoreceptor 20 with the belt interposed therebetween.

A primary transfer bias is applied to the primary transfer roller 12 from a high-voltage power source, and the toner image developed by the developing device 40 is primarily transferred onto the intermediate transfer belt 11 . Note that the primary transfer residual toner remaining on the photoreceptor 20 without being primarily transferred is removed by the cleaning means 50 in preparation for the next image forming operation by the photoreceptor 20, and the toner on the photoreceptor 20 is completely removed. removed.

Furthermore, a secondary transfer roller 5 as a secondary transfer device is provided downstream of the intermediate transfer belt 11 in the driving direction. The secondary transfer roller 5 faces a support roller 72 with the intermediate transfer belt 11 in between, and the secondary transfer roller 5 and the support roller 72 form a secondary transfer nip portion with the intermediate transfer belt 11 in between. ing.

The image forming apparatus 1 also includes a sheet feeding device 61 serving as a stacking section for sheets S serving as recording materials, a feeding roller 3, and a pair of registration rollers 4. Furthermore, a fixing device 100 and a pair of paper ejection rollers 7 are provided downstream in the conveyance direction of the paper S when viewed from the secondary transfer roller 5 .

Next, the image forming operation will be explained. First, the photoreceptor 20 is rotated clockwise by a drive source, and at this time, the surface of the photoreceptor 20 is irradiated with light from a static eliminator (not shown) to initialize the surface potential.

Next, the surface of the photoreceptor 20 is uniformly charged to a predetermined polarity by the charging member 30. Next, the surface of the photoreceptor 20 is irradiated with laser light from the exposure device 8, thereby forming an electrostatic latent image on the surface of the photoreceptor 20.

The image information exposed to each photoreceptor 20 at this time is monochrome image information obtained by separating a desired full-color image into toner color information of yellow, cyan, magenta, and black. The electrostatic latent image formed on the photoreceptor 20 is applied with each color toner (developer) from the developing device 40 when passing through the developing device 40, and is visualized as a developed toner image.

Further, while the intermediate transfer belt 11 is driven to run counterclockwise in the figure, a primary transfer voltage having a polarity opposite to the toner charging polarity of the toner image formed on the photoreceptor 20 is applied to the primary transfer roller 12. be done. As a result, a transfer electric field is formed between the photoreceptor 20 and the intermediate transfer belt 11, and the toner image on the photoreceptor 20 is electrostatically transferred onto the intermediate transfer belt 11, which is rotated in synchronization with the photoreceptor 20. primary transfer. In this way, the primary transferred toner images of each color are sequentially superimposed on the intermediate transfer belt 11 at the same timing from the upstream side in the conveyance direction of the intermediate transfer belt 11, thereby forming a desired full-color image.

On the other hand, the sheets S on which images are to be formed are separated and fed one by one from a stack of sheets stacked on the sheet feeding device 61 to the pair of registration rollers 4 by a conveying member such as the feeding roller 3. At this time, the leading edge of the transported sheet S hits the nip portion of the pair of registration rollers 4 that have not started rotating, forming a loop, and registration of the sheet S is performed. Thereafter, the rotation of the registration roller pair 4 is started in synchronization with the full-color toner image carried on the intermediate transfer belt 11, and a secondary transfer nip portion formed by the support roller 72 and the secondary transfer roller 5 is started. The paper S is sent out toward.

In the present embodiment, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt 11 is applied to the secondary transfer roller 5, so that the full-color toner image formed on the surface of the intermediate transfer belt 11 is transferred to the sheet S. It is transferred all at once on top. Next, the paper S onto which the toner image has been transferred is conveyed to the fixing device 100, where heat and pressure are applied as it passes through the fixing device 100, and the toner image is fixed onto the paper S as a permanent image.

Then, the paper S is discharged to a paper discharge section such as a paper discharge tray 17 via the paper discharge roller pair 7, and the image forming operation is completed. Note that residual toner remaining on the intermediate transfer belt 11 without being transferred at the secondary transfer nip portion is removed and collected by the intermediate transfer belt cleaning means 13.

The above description is about the image forming operation when forming a full-color image on the paper S. It can also be formed. Further, when performing monochrome printing using the printer of this embodiment, an electrostatic latent image is formed only on the photoreceptor 20Bk, developed by the same means, transferred to the paper S, and fixed by the fixing device 100. Bye.

(Unit fixed structure)
FIG. 2 shows a unit fixing structure for detachably fixing a fixing unit 100a, which is a unitized version of the fixing device 100 in FIG. 1, to the main body 1a of the image forming apparatus 1. FIGS. 2(a) and 2(b) are diagrams showing a conventional unit fixing structure, and FIGS. 2(c) and 2(d) are diagrams showing a unit fixing structure of the present embodiment.

The fixing unit 100a in FIG. 2 shows only a part of the unit, and the illustrated example shows bracket portions at both longitudinal ends of the fixing unit 100a. In this unit fixing structure, the unit 100a of the fixing device 100 is detachably fixed to the main body 1a of the image forming apparatus 1.

Conventionally, two cylindrical protrusions 60 and 61 are disposed on the side surface of the main body 1a, separated from each other in the left and right directions. The unit 100a is positioned by these projections 60 and 61.

Further, two screw holes 62 and 63 are formed near the protrusions 60 and 61 on the side surface of the main body 1a. By screwing two screws B1 and B2 as fastening members, which will be described later, into the screw holes 62 and 63, the unit 100a is fastened and fixed to the side surface of the main body 1a.

On the other hand, positioning holes 64 and 65 into which the two projections 60 and 61 can be inserted are formed in the unit 100a. By inserting (fitting) the protrusions 60 and 61 into the positioning holes 64 and 65, respectively, the unit 100a can be positioned with respect to the main body 1a. One (right) positioning hole 64 has a circular shape corresponding to the outer diameter of the protrusion 60, while the other (left) positioning hole 65 has a horizontally long elliptical shape. This is because the horizontally elongated elliptical shape allows for positional errors in the left and right direction of the protrusion 61 inserted into the positioning hole 65.

Insertion holes 67 and 68 for inserting two screws B1 and B2 are formed near the positioning holes 64 and 65. These insertion holes 67 and 68 are round holes corresponding to the outer diameters of the screws B1 and B2, and are preferably formed approximately 1 to 2 mm larger than the screw diameters to avoid interference with the screw diameters.

In the conventional unit fixing structure shown in FIGS. 2(a) and 2(b), if the screws B1 and B2 fall out when inserted into the insertion holes 67 and 68, the screws enter the machine and it takes time and effort to recover them. If the screws are left uncollected, they may damage other parts and cause problems such as abnormal images, poor sheet conveyance, and damaged parts.

Therefore, in this embodiment, as shown in FIGS. 2(c) and 2(d), a screw receiving portion 70a is formed on the positioning projection 70. That is, the protrusion 70 is made to protrude outward (to the front side in FIG. 2(c)) below the insertion holes 67 and 68 through which the screws B1 and B2 are inserted, and the protrusion 70 has a U-shaped cross section that is open upward. is formed. The "U-shape" used here means a shape in which the central part is lower than the peripheral part. Therefore, a so-called dish shape with a shallow depth is also included in the U-shape.

The positioning hole 69 for inserting (penetrating) the protrusion 70 is also formed in a U-shape that opens upward, as shown in FIG. 2(d). It is relatively easy to form the protrusion 70 to have a U-shaped cross section and to form the positioning hole 69 to have a U-shape in terms of processing. Therefore, it is easy to achieve positioning accuracy of the unit 100a.

It is preferable that the width and height of the U-shape of the protrusion 70 and the axial length of the protrusion 70 are appropriately optimized depending on the size and visibility of the screws B1 and B2, and the positional relationship with peripheral parts. Furthermore, it is also possible to use a sheet metal that is easy to process as the frame material of the unit 100a. In this way, the degree of freedom in design layout can be increased.

If the fall prevention members for the screws B1 and B2 are added as special parts, the increase in the number of parts will increase the cost and deteriorate the ease of assembly. On the other hand, in this embodiment, the projections 70 essential for positioning the unit 100a are used to form the receiving parts 70a for the screws B1 and B2, so problems such as an increase in the number of parts and costs are not caused. do not have. Further, by making the insertion holes 67 and 68 and the positioning hole 69 separate, it is possible to downsize the unit 100a.

As shown in FIG. 2(d), the width W1 on the right side of the right positioning hole 69 is formed to be slightly wider than the width W2 on the right side of the protrusion 70 so that the unit 100a does not wobble in the left-right direction. (W2<W1). Further, the height H1 of the horizontal portion of the positioning hole 69 is also formed to be slightly wider than the height H2 of the horizontal portion of the protrusion 70 so that the unit 100a does not wobble in the vertical direction (H2<H1). . In this way, by reducing the fitting tolerance at the right corner of the positioning hole 69, it is possible to prevent the unit 100a from shaking in the vertical and horizontal directions.

On the other hand, other parts, such as the width of the left side of the right positioning hole 69, are determined by It is formed wider and with more room than the original. This makes it easier to insert the protrusion 70 into the positioning hole 69.

On the other hand, the left and right widths W1' of the left positioning hole 69 in FIG. It is formed wider than the width W2' with a margin. Further, the height H1' of the horizontal portion of the positioning hole 69 is slightly wider than the height H2' of the horizontal portion of the protrusion 70 so that the unit 100a does not wobble in the vertical direction (H2' <H1').

Although FIG. 2D shows a case in which the unit 100a is positioned using the right positioning hole 69 and the protrusion 70 as a reference, it is also possible to position the unit 100a using the left positioning hole 69 as a reference. In that case, either the left or right width W1' is formed to be slightly wider than the width W2' of the protrusion 70 (W2'<W1'). Further, although FIG. 2D shows a case where the width W1 on the right side of the protrusion 70 is used as a reference, it is also possible to use the width W1 on the left side of the protrusion 70 as a reference.

FIG. 3 shows the actual shape of the protrusion 70 shown in FIG. 2(d). The right pair of the protrusion 70 and the positioning hole 69 can position the unit 100a in the horizontal and vertical directions as shown in FIG. 2(d). Further, the other pair of the protrusion 70 and the positioning hole 69 on the left side can position the unit 100a in the vertical direction.

A protrusion 70 protruding outward from the positioning hole (positioning hole 69 in FIG. 2(d)) of the unit 100a is located below the insertion holes 67 and 68. The protrusion 70 has a U-shaped cross section that is open upward.

A concave receiving portion 70a is formed inside the U-shape of the protrusion 70. The screws B1 and B2 that have fallen out of the insertion holes 67 and 68 can be received and housed in the receiving portion 70a.

(●Resin cover)
FIG. 4 shows a unit 100a in which a heat-resistant resin cover 100b as a cover member is attached to the outer surface of the unit 100a on the side opposite to the apparatus main body 1a. The unit 100a as a fixing device has a heat source 82 (halogen heater) as described later. For this reason, when the unit frame is made of sheet metal, the frame may reach a high temperature due to its high thermal conductivity. As a countermeasure, it is common practice to integrally provide a heat-resistant resin cover on the outer surface of the frame of the unit 100a to prevent burns.

On the other hand, when the positioning hole 69 is formed into a U-shape as described above, the rigidity of the frame decreases as the positioning hole 69 becomes larger. Therefore, in this embodiment, as shown in FIG. 4, in order to ensure the rigidity of the frame, the protrusion 70 and the positioning hole 69 are formed into an L-shape. Since the L-shape can increase the frame rigidity more than the U-shape, the degree of freedom in design such as the size of the positioning hole 69 can be increased.

If the protrusion 70 is simply L-shaped, the screw may fall off because the protrusion 70 is open in the lateral direction. Therefore, it was decided to form an I-shaped convex portion 71 extending in the vertical direction on the inner surface of the resin cover 100b.

The I-shaped convex portion 71 and the L-shaped protrusion 70 can form a U-shaped receiving portion 70a that is open upward as a whole. The screw B1 dropped from the insertion hole 67 can be accommodated in the receiving part 70a formed inside the convex part 71 and the protruding part 70. Although FIG. 4 shows the receiving portion 70a for one screw B1, the receiving portion 70a for the opposite screw B2 may be similarly configured. According to this embodiment, while preventing screws from falling off, it is possible to increase the degree of freedom in design layout, such as miniaturization and selection of sheet metal.

It is also possible to change the convex part 71 of the resin cover 100b from an I-shape to a U-shape, and configure the screw receiving part only with the U-shaped convex part. However, this will lead to an increase in cost due to an increase in the amount of resin material used for the resin cover 100b. Furthermore, since the protrusion 70 that does not have a receiving portion must be disposed at a different position, it becomes difficult to downsize the unit 100a.

(Fixing device)
The configuration of the fixing device 100 shown in FIG. 1 will be described below with reference to FIGS. 5 and 6. FIG. 5 is a schematic configuration diagram showing a fixing device according to one embodiment of the present embodiment, and FIG. 6 is an exploded perspective view of a nip forming member. The fixing device 100 includes a rotatable endless fixing belt 81 , a heat source 82 (halogen heater) that heats the fixing belt 81 , and a pressure roller 83 that is a pressure member that comes into contact with the outer peripheral surface of the fixing belt 81 . Be prepared.

A nip forming member 86 that indirectly slides on the inner surface of the fixing belt 81 via a sliding sheet is provided within the fixing belt 81 . This nip forming member 86 forms a nip portion N together with the pressure roller 83 facing to each other with the fixing belt 81 interposed therebetween.

Although the nip portion N has a flat shape in FIG. 5, it may have a concave shape or other shapes. When the nip portion N has a concave shape, the discharge direction of the leading edge of the recording material is closer to the pressure roller 83, improving separation performance and suppressing the occurrence of jams.

The fixing belt 81 can be a metal belt such as nickel or SUS, an endless belt made of a resin material such as polyimide, or a film. The surface layer of the fixing belt 81 has a release layer such as a PFA or PTFE layer, and has release properties to prevent toner from adhering.

It is desirable that there is an elastic layer formed of a silicone rubber layer or the like between the base material of the fixing belt 81 and the PFA or PTFE layer. When there is no silicone rubber layer, the heat capacity is reduced and the fixing properties are improved.

However, when crushing and fixing an unfixed image, minute irregularities on the belt surface are transferred to the image, and there is a risk that citron skin-like gloss unevenness (citron skin image) may remain in solid areas of the image. To improve this, it is sufficient to provide a silicone rubber layer with a thickness of 100 μm or more, and the deformation of the silicone rubber layer absorbs minute irregularities and improves the citron skin image.

Furthermore, a support member 87 (stay) for supporting the nip portion N is provided inside the fixing belt 81. This prevents the nip forming member 86 from being bent due to the pressure of the pressure roller 83, and provides a uniform nip width in the axial direction.

This support member 87 is held and fixed at both ends by a holding member 88 (flange) and positioned. Furthermore, a reflective member 89 is provided between the heat source 82 and the support member 87 to suppress wasteful energy consumption due to the support member 87 being heated by radiant heat from the heat source 82.

Instead of providing the reflective member 89, the same effect can be obtained by subjecting the surface of the supporting member 87 to heat insulation treatment or mirror finishing. Note that the heat source 82 may be the illustrated halogen heater, but may also be an IH, a resistance heating element, a carbon heater, or the like.

The pressure roller 83 has a core metal 84 and an elastic rubber layer 85, and a release layer (PFA or PTFE layer) is provided on the surface to obtain release properties. The pressure roller 83 rotates as driving force is transmitted from a drive source such as a motor provided in the image forming apparatus 1 via a gear.

Further, the pressure roller 83 is pressed against the fixing belt 81 side by a spring or the like, and the elastic rubber layer 85 is crushed and deformed to have a predetermined nip width. The pressure roller 83 may be a hollow roller, or may include a heat source such as a halogen heater inside the pressure roller 83.

The elastic rubber layer 85 may be made of solid rubber, but if there is no heat source inside the pressure roller 83, sponge rubber may be used. Sponge rubber is more desirable because it has better heat insulation and makes it difficult for the fixing belt 81 to lose heat.

When the pressure roller 83 is rotated by the drive source, the driving force is transmitted to the fixing belt 81 at the nip portion N, so that the fixing belt 81 rotates together with the fixing belt 81 . The fixing belt 81 rotates while being sandwiched in the nip portion N, and is guided by holding members 88 (flanges) at both ends outside the nip portion N and runs. With the above configuration, it is possible to realize a fixing device that is inexpensive and warms up quickly.

(Nip forming member)
FIG. 6 is an exploded perspective view of the nip forming member according to one embodiment of the present embodiment. This configuration is aimed at reducing the excessive temperature rise in the non-sheet passing area, and has the function of reducing the number of heat sources (reducing the number of halogen heaters to two) and substituting the light shielding member 90. Therefore, the light shielding member 90 and the drive unit that drives it are not required, and costs can be significantly reduced.

As shown in FIG. 6, the nip forming member 86 includes a heat equalizing member 66 as a first heat transfer means and a sliding sheet 67 provided on the heat equalizing member 66. When the fixing belt 81 rotates, the fixing belt 81 slides against the sliding sheet 67, thereby reducing the driving torque generated on the fixing belt 81 and reducing the load due to frictional force on the fixing belt 81. Ru.

The heat equalizing member 66 is made of a material with high thermal conductivity, such as copper, and is formed along the length of the fixing belt 81 . Then, it is possible to absorb heat excessively accumulated in the non-sheet passing portion of the fixing belt 81 and move the heat in the longitudinal direction.

As shown in FIG. 6, the nip forming member 86 includes a first heat insulating member 77a, a second heat insulating member 77b, a first heat absorbing member 76, and a second heat absorbing member 75. The first heat insulating member 77 a is made of, for example, resin, and has a lower thermal conductivity than the heat equalizing member 66 , and partially extends in the longitudinal direction of the fixing belt 81 between the heat equalizing member 66 and the second heat absorbing member 75 . , is arranged at a position where the first heat absorbing member 76 is not present.

By having the first heat insulating member 77a, excessive absorption of heat from the fixing belt 81 is avoided. As a result, a drop in temperature at the paper passing section can be prevented. Additionally, warm-up time and power consumption can be reduced.

The second heat insulating member 77b is made of, for example, a resin having a lower thermal conductivity than the heat equalizing member 66, and is provided between the heat equalizing member 66 and the first heat absorbing member 76. By providing the second heat insulating member 77b, the amount of heat transferred from the heat equalizing member 66 to the second heat absorbing member 75 via the first heat absorbing member 76 can be reduced.

Note that if the second heat insulating member 77b is made too thick, the heat accumulated in the fixing belt 81 will not be transferred to the second heat absorbing member 75, so that the temperature of the non-paper-passing area will likely rise. Therefore, the thickness and length of the second heat insulating member 77b need to be optimized depending on the magnitude of the temperature rise in the non-sheet passing portion, but the thickness is smaller than the thickness of the first heat insulating member 77a.

The second heat absorbing member 75 is made of a material having higher thermal conductivity than the first heat insulating member 77a and the second heat insulating member 77b. The second heat absorbing member 75 extends in the longitudinal direction of the fixing belt 81 and is disposed in contact with the first heat insulating member 77a and the first heat absorbing member 76.

The first heat absorbing member 76 is also made of a material with higher thermal conductivity than the first heat insulating member 77a and the second heat insulating member 77b, and partially extends in the longitudinal direction of the fixing belt 81. It is arranged between two heat absorbing members 75. In particular, the first heat absorbing member 76 is provided at a position other than the central region of the fixing belt 81, that is, at a position where a temperature increase occurs in the non-sheet passing portion of the fixing belt 81.

Note that in this embodiment, the first heat absorbing member 76 is provided corresponding to the non-sheet passing area, but the present invention is not limited to this aspect. For example, the first heat absorbing member 76 may be extended and provided in the longitudinal direction of the first heat absorbing member 76 to a position corresponding to the paper passing area.

The heat equalizing member 66 has a function of promoting heat transfer in the longitudinal direction, uniformizing the temperature of the fixing belt 81, and suppressing a rise in temperature of the non-sheet passing portion. On the other hand, the first heat absorbing member 76 and the second heat absorbing member 75 have the role of promoting heat transfer in the thickness direction and absorbing heat.

That is, the first heat absorbing member 76 and the second heat absorbing member 75 compensate for the lack of heat capacity of the heat equalizing member 66. Therefore, it is particularly desirable that the second heat absorbing member 75 has a large heat capacity or a large surface area in order to increase the amount of heat dissipation.

The heat absorbing member, the heat insulating member, and the bent portions 66b and 66c sandwich the end region of the sliding sheet 67 in the sliding direction, so that the sliding sheet 67 can be more firmly fixed. Furthermore, it is possible to prevent the temperature from dropping in the paper passing section. Furthermore, warm-up time and power consumption can be reduced.

Next, the characteristic configuration of this embodiment will be explained. Generally, in order to improve the durability of the fixing belt 81, the sliding sheet 67 is often made of a material with low friction properties and coated with a lubricant. A low-viscosity material is used as the lubricant, but because of its high fluidity, it easily flows out from the fixing belt 81, resulting in an increase in sliding load (torque).

Furthermore, the lubricant applied to the sliding sheet 67 tends to flow in one direction due to the nip deviation in the longitudinal direction, the texture direction of the sliding sheet 67, and the like. Here, the nip deviation is a pressure deviation caused by a static load deviation during pressurization or a dynamic load deviation during driving by the one-sided drive method.

When the lubricant is partially depleted in the longitudinal direction of the sliding sheet 67, fluctuations in the linear velocity of the fixing belt 81 in the longitudinal direction (fluctuations in friction between the fixing belt 81 and the sliding sheet 67) occur, resulting in poor conveyance such as wrinkles on the recording material. occurs. Furthermore, since the shift speed of the fixing belt 81 also increases, the load on the end surface of the fixing belt 81 increases, resulting in a problem that the service life of the fixing belt 81 is shortened.

This embodiment has been described above in detail using the embodiments. This embodiment is an example, and various changes can be made without departing from the scope of the invention. For example, the unit to which the fixing structure of the present invention is applied is not limited to the fixing unit 100a. The fixing structure of the present invention is applicable to all types of units fixed to the main body of the device. Furthermore, the fastening member is not limited to screws. For example, bolts may be used instead of screws.

Further, as the fixing device 100 and the image forming apparatus 1, any configuration can be adopted as long as this embodiment is applicable. The image forming apparatus 1 is not limited to a copying machine or a printer, but may also be a facsimile machine or a multifunction device having multiple functions.

1: Image forming device 1a: Apparatus main body 3: Feeding roller 4: Registration roller pair 5: Secondary transfer roller 7: Paper ejection roller pair 8: Exposure device 9Y, 9M, 9C, 9Bk: Toner bottle 11: Intermediate transfer belt 12Y, 12M, 12C, 12Bk: Primary transfer roller 13: Intermediate transfer belt cleaning means 17: Paper ejection tray
20Y, 20M, 20C, 20Bk: Photoreceptor 30Y, 30M, 30C, 30Bk: Charging member
40Y, 40M, 40C, 40Bk: Developing device 50Y, 50M, 50C, 50Bk: Cleaning means 61: Sheet feeding device 62, 63: Screw holes 64, 65: Positioning hole 66: Uniform heat member 66a: Contact portion 66b, 66c: Bending portion 66d: Holding portion 67: Sliding sheet 67a: Opening portion 68: Convex portion 70: Protrusion portion 70a: Receiving portion 71: Convex portion 72, 73: Support roller 74: Sliding sheet 75: Second heat absorption Member 76: First heat absorbing member 77a: First heat insulating member 77b: Second heat insulating member 81: Fixing belt 82: Heat source 83: Pressure roller 84: Core bar 85: Elastic rubber layer 86: Nip forming member 87: Supporting member 88 : Holding member 89: Reflective member 90: Light shielding member 100: Fixing device 100a: Fixing unit 100b: Resin cover B1, B2: Screw N: Nip part S: Paper (recording material) t: Texture

JP2011-107334A

Claims (7)

A unit fixing structure that removably fixes a unit to a device body, the unit is positioned by inserting a protrusion provided on the device body into a positioning hole of the unit, and the unit is in the positioned state. In a unit fixing structure in which the unit is fixed to the device main body by a fastening member,
An insertion hole for inserting the fastening member is formed in the unit, the positioning hole is formed below the insertion hole, and a receiving part for the fastening member is formed in the protrusion projecting from the positioning hole. A unit fixed structure characterized by: 2. The fixing structure according to claim 1, wherein the receiving portion has a U-shaped cross section with an upward opening. 2. The fixing structure according to claim 1, wherein the receiving portion has an L-shaped cross section with an upward opening. A side of the unit opposite to the device main body is covered with a cover member, and a convex portion formed on the inner surface of the cover member and the receiving portion form a U-shaped cross section that is open upward. The fixing structure according to claim 3. The protrusion, the positioning hole, and the insertion hole are formed in at least two places, and one set of the protrusion and the positioning hole positions the unit in the horizontal and vertical directions, and the other of the protrusion and the positioning hole 5. The fixing structure according to claim 1, wherein the units are vertically positioned in one set. A fixing device as the unit, wherein the fixing device is configured to be fixable to the device main body by the fixing structure according to claim 5. An image forming apparatus comprising the fixing device according to claim 6.

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