JP2023163689A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device that can retain lubricant near a nip part.SOLUTION: A fixing device comprises a fixing pad 60 that is in contact with the inside of a fixing belt to form a nip part NP for pressing a sheet together with a pressing member. The fixing pad 60 has a base 61, and a slide sheet 62 fixed to the base 61 and sliding with the inside of the fixing belt. The slide sheet 62 is impregnated with lubricant, and has a first slide area (corresponding to non-adhesion part SE) with low density, and a second slide area with a density higher than that of the first slide area. The first slide area is provided at a position including the nip part NP, and the second slide area is provided at a position surrounding the outer periphery of the first slide area.SELECTED DRAWING: Figure 5A

Description

The present disclosure relates to a fixing device and an image forming apparatus that fix an image to paper.

2. Description of the Related Art Conventionally, in a fixing device used in an electrophotographic image forming apparatus such as a copying machine or a printer, a toner image is fixed by pressurizing and heating a sheet on which an unfixed toner image is formed. In recent years, a fixing device using an endless fixing belt has been proposed. In such a fixing device, a nip forming member is disposed inside an endless fixing belt, and a pressure roller is pressed against the nip forming member via the fixing belt to form a nip portion. In the nip portion, a sliding sheet impregnated with a lubricant is provided to reduce frictional resistance between the inner peripheral surface of the fixing belt and the nip forming member (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2017-167349

A conventional fixing device includes a rotatable fixing member in the form of an endless belt, a heat source that heats the fixing member, a nip forming member disposed inside the fixing member, and a device that faces the nip forming member through the fixing member. , a pressure member forming a nip portion with the fixing member, and a first sliding member impregnated with a lubricant and installed between the nip forming member and the fixing member. The fixing device further includes a second sliding member that contacts the inner surface of the fixing member in a part of the region other than the nip portion, and the second sliding member has a weave direction that is different from the weave direction of the first sliding member. It has different textures.

By the way, since the sliding sheet (sliding member) is formed into a sheet shape by weaving fibers, the flow direction of the impregnated lubricant is determined by the texture of the sliding sheet, and the edge of the sliding sheet There was a risk of lubricant leaking from the parts. In the fixing device described above, the second sliding member having a different weave direction is provided on the upstream side of the nip portion to prevent lubricant from leaking from the first sliding member. There is a risk that the lubricant may leak from the portion that does not face the second sliding member.

The present disclosure has been made, for example, to solve the above problems, and can provide a fixing device and an image forming device that can retain lubricant near the nip portion.

A fixing device according to the present disclosure is a fixing device that heats and presses a sheet of paper held between a cylindrical endless belt and a pressure member to fix an image on the sheet of paper, the fixing device being in contact with the inside of the endless belt, A fixing pad that forms a nip portion that presses paper together with a pressure member, and the fixing pad has a base and a sliding sheet that is fixed to the base and slides on the inside of the endless belt. , the sliding sheet is impregnated with a lubricant and has a first sliding region with a low density and a second sliding region with a higher density than the first sliding region, The moving area is provided at a position that includes the nip portion, and the second sliding area is provided at a position surrounding the outer periphery of the first sliding area.

In the fixing device according to the present disclosure, the sliding sheet may be fixed to the base with an adhesive impregnated in the second sliding area.

In the fixing device according to the present disclosure, the sliding sheet may be baked together with the adhesive and fixed to the base.

In the fixing device according to the present disclosure, the fixing pad may have a fixing part that fixes the base and the sliding sheet, and the second sliding area may be fired.

In the fixing device according to the present disclosure, the base has a base pressing surface facing the inside of the fixing belt, and a base side surface extending from an outer edge of the base pressing surface, and the sliding sheet is configured to press the base pressing surface. A configuration may be adopted in which a pressing surface fixing section fixed to the surface and a side surface fixing section fixed to the base side surface are provided in the second sliding region.

An image forming apparatus according to the present disclosure includes a fixing device according to the present disclosure.

According to the present disclosure, since the sliding sheets have different densities, it is possible to impregnate and enclose a large amount of lubricant in the vicinity of the nip portion, thereby retaining the lubricant in the vicinity of the nip portion.

1 is a schematic side view of an image forming apparatus according to a first embodiment of the present disclosure. FIG. 2 is an enlarged schematic side view showing the vicinity of the fixing device in FIG. 1; FIG. 3 is a schematic explanatory diagram showing a nip portion in a fixing pad. FIG. 2 is a schematic cross-sectional view showing a conventional fixing pad. FIG. 3 is a schematic plan view showing the position of a nip portion in a conventional fixing pad. FIG. 1 is a schematic cross-sectional view showing a fixing pad according to a first embodiment of the present disclosure. FIG. 3 is a schematic plan view showing the position of a nip portion in the fixing pad according to the first embodiment of the present disclosure. FIG. 3 is a schematic cross-sectional view showing a fixing pad according to a second embodiment of the present disclosure.

(First embodiment)
An image forming apparatus according to a first embodiment of the present disclosure will be described below with reference to the drawings.

FIG. 1 is a schematic side view of an image forming apparatus according to a first embodiment of the present disclosure.

The image forming apparatus 1 according to the first embodiment of the present disclosure includes a main body section that performs image formation, a document reading section 44 and a document transport section 45 provided at the top, and a paper feeding device 50 provided at the bottom. Be prepared. The paper feeding device 50 includes a device main body 52 and a paper feeding cassette 51 inserted into the device main body 52.

The document reading unit 44 is provided with a document placing table 43 on its upper surface on which a document is placed, reads an image of the document on the document placing table 43, creates image data, and transmits the image data to the image forming apparatus 1. The document transport unit 45 automatically transports the document onto the document mounting table 43. Further, the document transport section 45 is rotatably attached to the image forming apparatus 1, and by rotating it and opening the top of the document placement table 43, the document can be placed manually. can.

The main body of the image forming apparatus 1 includes an exposure device 11, a developing device 12, a photosensitive drum 13, a cleaning device 14, a charger 15, a transfer unit 20, a fixing device 17, a paper discharge tray 39, and a paper conveyance path R1. A multicolor image and a monochrome image are formed on a predetermined sheet of paper according to image data transmitted from the outside or from the document reading section 44.

Image data handled by the image forming apparatus 1 corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Therefore, four developing devices 12, photoreceptor drums 13, chargers 15, and cleaning devices 14 are provided so as to form four types of latent images corresponding to each color. These settings constitute four image stations Pa, Pb, Pc, and Pd.

The photosensitive drum 13 is arranged approximately at the center of the image forming apparatus 1 . The charger 15 uniformly charges the surface (circumferential surface) of the photoreceptor drum 13 to a predetermined potential. The exposure device 11 exposes the surface of the photoreceptor drum 13 to form an electrostatic latent image. The developing device 12 develops the electrostatic latent image on the surface of the photoreceptor drum 13 to form a toner image on the surface of the photoreceptor drum 13 . Through the series of operations described above, toner images of each color are formed on the surface of each photoreceptor drum 13. The cleaning device 14 removes and collects residual toner on the surface of the photosensitive drum 13 after development and image transfer.

The transfer unit 20 includes a transfer drive roller 22, a transfer driven roller 23, and an intermediate transfer belt 21 (an example of a transfer belt). The intermediate transfer belt 21 is suspended between a transfer drive roller 22 rotated by a connected drive source and a transfer driven roller 23, and is driven together with the transfer driven roller 23 in accordance with the rotation of the transfer drive roller 22. The intermediate transfer belt 21 rotates in the direction of arrow C, residual toner is removed and collected by the intermediate transfer belt cleaning device 25, and the toner images of each color formed on the surface of each photoreceptor drum 13 are sequentially transferred. The toner images are superimposed on each other to form a color toner image on the surface of the intermediate transfer belt 21.

The image forming apparatus 1 further includes a secondary transfer device 26 including a transfer roller 26a. A transfer nip area is formed between the transfer roller 26a and the intermediate transfer belt 21, and the paper conveyed through the paper conveyance path S is sandwiched in the transfer nip area and conveyed. When the paper passes through the transfer nip area, the toner image on the surface of the intermediate transfer belt 21 is transferred to the paper.

The image forming apparatus 1 performs image formation using the sheets stored in the paper feed cassette 51. Paper feeding device 50 is provided below exposure device 11 . Further, the paper ejection tray 39 is provided below the document reading section 44, and is a tray on which paper on which an image has been formed is placed.

The paper is pulled out from the paper feed cassette 51 by the paper feed roller 33 and supplied to the S-shaped paper transport path R1. Further, a conveyance roller 35, a registration roller 34, a secondary transfer device 26, a fixing device 17, and a paper discharge roller 36 are arranged along the paper conveyance path R1.

The registration roller 34 temporarily holds the paper being conveyed from the paper feed cassette 51, and conveys the paper to the transfer roller 26a at a timing to align the leading edge of the toner image on the photosensitive drum 13 with the leading edge of the paper. The conveyance roller 35 is a small roller for promoting and assisting the conveyance of paper.

The fixing device 17 receives a sheet of paper on which an unfixed toner image has been formed, and heats and presses the sheet by sandwiching the sheet between a fixing belt 31 and a pressure roller 32 (an example of a pressure member), thereby fixing the toner image on the sheet. Fix the toner image. After the fixing, the paper is discharged onto a paper discharge tray 39 by a paper discharge roller 36. In this embodiment, the fixing device 17 is of a belt fixing type, and has a configuration in which a fixing pad 60 is arranged inside a fixing belt 31 that is a cylindrical endless belt. The fixing pad 60 contacts the inside of the fixing belt 31 and forms a nip portion NP (see FIG. 3) that presses the paper together with the pressure roller 32. Note that the fixing device will be described in detail with reference to FIG. 2, which will be described later.

When forming an image not only on the front side but also on the back side of the paper, the paper is conveyed in the opposite direction from the paper ejection roller 36 to the reversing path Rr, the front and back sides of the paper are reversed, and the paper is transferred to the registration rollers 34. The paper is guided again, an image is formed on the back side in the same manner as on the front side, and the paper is conveyed to the paper discharge tray 39.

FIG. 2 is a schematic side view showing the vicinity of the fixing device in FIG. 1 in an enlarged manner.

As described above, the fixing device 17 includes the fixing belt 31, the pressure roller 32, and the fixing pad 60. Although FIG. 2 shows the main parts of the fixing device 17, the present invention is not limited to this, and a heat source for heating the fixing belt 31, a fixture for supporting the fixing pad 60, etc. may be provided. good. The toner image is fixed on the paper fed in the transport direction H along the paper transport path R1 when it passes through the nip NP between the fixing belt 31 and the pressure roller 32.

FIG. 3 is a schematic explanatory diagram showing a nip portion in the fixing pad.

In FIG. 3, the fixing pad 60 and the pressure roller 32 are shown extracted, and a nip portion NP formed by pressing them together via the fixing belt 31 is schematically shown. The fixing pad 60 has a flat surface facing the pressure roller 32 , and the center portion of this surface is pressed against the pressure roller 32 . That is, a part of the flat surface of the fixing pad 60 that faces the pressure roller 32 corresponds to the nip portion NP.

Next, a comparison between the conventional fixing pad (comparison pad 160) and the fixing pad 60 in this embodiment will be described with reference to FIGS. 4A to 5B.

FIG. 4A is a schematic cross-sectional view showing a conventional fixing pad, and FIG. 4B is a schematic plan view showing the position of a nip portion in the conventional fixing pad.

The conventional fixing pad (comparison pad 160) includes a rectangular parallelepiped base (comparison base 161) and a sliding sheet (comparison sheet 162) fixed to the base. The longitudinal direction of the comparison base 161 is the direction along the width direction W of the paper. The comparison sheet 162 is fixed to the comparison base 161 using an adhesive (comparison adhesive 163). Specifically, the comparison base 161 has a surface that is located inside the fixing belt 31 and faces the pressure roller 32, and a side surface extending from the outer edge of the surface. The comparison sheet 162 covers the surface of the comparison base 161 that faces the pressure roller 32 and the side surface. The comparative adhesive 163 is impregnated throughout the comparative sheet 162, and adheres all the parts where the comparative base 161 and the comparative sheet 162 face.

In FIG. 4A, the hatching of the comparison base 161 and the comparison sheet 162 is omitted in consideration of the legibility of the drawing. The comparative adhesive 163 is hatched to emphasize the difference in position from this embodiment.

The pressure roller 32 is arranged so as to be pressed against the comparison pad 160 approximately at the center in the transport direction H and the width direction W. As a result, a nip portion NP is formed approximately at the center of the surface of the comparison pad 160 that faces the pressure roller 32 .

FIG. 4B shows a state in which the comparison sheet 162 is removed from the comparison pad 160 and the surface facing the pressure roller 32 is viewed. As shown in FIG. 4B, the comparison adhesive 163 covers the entire comparison base 161, and the comparison adhesive 163 is also present in the portion corresponding to the nip portion NP.

Conventionally, in the fixing pad, the sliding sheet is impregnated with lubricant in order to reduce friction with the fixing belt 31, but when the sliding sheet is penetrated (impregnated) with adhesive, the lubricant is Holding power deteriorates. In response to this, increasing the amount of lubricant applied may be considered, but this may result in the lubricant leaking from the sliding sheet. Therefore, in the present embodiment, the lubricant is retained in the vicinity of the nip portion NP without increasing the amount of lubricant applied by varying the penetration power of the lubricant depending on the location.

FIG. 5A is a schematic cross-sectional view showing the fixing pad according to the first embodiment of the present disclosure, and FIG. 5B is a schematic plan view showing the position of the nip portion in the fixing pad according to the first embodiment of the present disclosure. In FIG. 5A, similar to FIG. 4A, hatching of the base 61 and sliding sheet 62 is omitted, and the adhesive 63 is hatched, considering the ease of viewing the drawing. In addition, in FIG. 5A, in order to make the presence of the adhesive 63 noticeable, the thickness of the adhesive 63 is increased so that there is a gap between the base 61 and the sliding sheet 62. However, the thickness of the adhesive 63 may be reduced so that the base 61 and the sliding sheet 62 are in contact with each other.

The fixing pad 60 of this embodiment includes a substantially rectangular parallelepiped base 61 and a sliding sheet 62 fixed to the base 61. The longitudinal direction of the base portion 61 is the direction along the width direction W of the paper. The sliding sheet 62 is fixed to the base 61 using an adhesive 63.

The base 61 is located inside the fixing belt 31 and has a base pressing surface 61a facing the pressure roller 32, and a base side surface 61b extending from the outer edge of the base pressing surface 61a.

The sliding sheet 62 covers the base pressing surface 61a and the base side surface 61b of the base 61. The sliding sheet 62 is impregnated with a lubricant and has a first sliding region with a lower density and a second sliding region with a higher density than the first sliding region. The second sliding region is provided with a pressing surface fixing portion 62a fixed to the base pressing surface 61a and a side surface fixing portion 62b fixed to the base side surface 61b. The adhesive 63 is impregnated into a part of the sliding sheet 62, and adheres a part of the area where the base 61 and the sliding sheet 62 face each other.

The pressure roller 32 is arranged so as to be pressed against the fixing pad 60 approximately at the center in the transport direction H and the width direction W. As a result, a nip portion NP is formed in the fixing pad 60 at a portion corresponding to approximately the center of the base pressing surface 61a. The first sliding area described above is provided at a position that includes the nip portion NP, and the second sliding area is provided at a position surrounding the outer periphery of the first sliding area.

In this embodiment, the part of the sliding sheet 62 that is not fixed to the base 61 by the adhesive 63 corresponds to the first sliding area, and the part fixed to the base 61 by the adhesive 63 corresponds to the second sliding area. Corresponds to the sliding area. The sliding sheet 62 has a first sliding area (corresponding to the non-adhesive area SE) that is not bonded to the base 61 at approximately the center in the conveying direction H and the width direction W with respect to the base pressing surface 61a. The end portions in the direction H and the width direction W are the second sliding region (pressing surface fixing portion 62a) bonded to the base portion 61. Furthermore, the entire portion of the sliding sheet 62 that covers the base side surface 61b (side surface fixing portion 62b) is adhered to the base portion 61.

Similar to FIG. 4B, FIG. 5B shows a state in which the sliding sheet 62 is removed from the fixing pad 60 and the base pressing surface 61a is viewed. As shown in FIG. 5B, the adhesive 63 covers the outer periphery of the base pressing surface 61a, and the portion corresponding to the nip portion NP is defined as a non-adhesive portion SE where the adhesive 63 does not exist. The non-bonded part SE includes the nip part NP and is set to have a slightly wider range than the nip part NP. In this manner, by using the adhesive 63, it is possible to freely set the portion to be bonded between the sliding sheet 62 and the base portion 61, and it is possible to fix the appropriate portion.

The sliding sheet 62 is bonded to the base 61 with an adhesive 63 and then fired. By firing the adhesive 63 that bonds the base 61 and the sliding sheet 62 in this way, the sliding sheet 62 can be more firmly fixed. As described above, the sliding sheet 62 is formed into a sheet shape by weaving fibers, and when fired, the fibers become tighter and have a higher density. In addition, in the part of the sliding sheet 62 impregnated with the adhesive 63, the gap is filled with the fired adhesive 63, so the density of the second sliding area can be increased, and the density of the first sliding area can be increased. can be differentiated from the density of In this way, since the sliding sheets 62 have different densities, a large amount of lubricant can be impregnated and enclosed in the vicinity of the nip part NP, and the lubricant can be retained in the vicinity of the nip part NP.

In this embodiment, since the sliding sheet 62 is fixed not only to the base pressing surface 61a but also to the base side surface 61b, the frictional force with the fixing belt 31 is transmitted in the direction along the base pressing surface 61a ( Even if it is applied in the conveyance direction H), it is suppressed by the base side surface 61b, and the sliding sheet 62 can be prevented from shifting.

(Second embodiment)
Next, an image forming apparatus according to a second embodiment of the present disclosure will be described with reference to the drawings.

The second embodiment differs from the first embodiment in the structure of the fixing pad 60. Note that the second embodiment has substantially the same configuration as the first embodiment shown in FIGS. 1 to 5A, so the explanation will be omitted and only the different points will be explained.

FIG. 6 is a schematic cross-sectional view showing a fixing pad according to a second embodiment of the present disclosure.

In the second embodiment, the base 61 and the sliding sheet 62 are fixed by the fixing part 64 without using the adhesive 63. In this embodiment, the sliding sheet 62 covers the base 61 so as to wrap around the base pressing surface 61a and the base side surface 61b as well as the surface on the opposite side of the base pressing surface 61a. The fixing part 64 is, for example, a screw, a stud, a winding tool, a hook part provided on the base 61, etc., and fixes the base 61 and the sliding sheet 62 on the surface opposite to the base pressing surface 61a. ing. Note that the present invention is not limited to this, and the base 61 and the sliding sheet 62 may be fixed at the base side surface 61b. Although FIG. 6 shows a structure in which the fixing part 64 is provided separately from the base 61, the present invention is not limited to this, and a structure in which the fixing part 64 is provided in the base 61 itself may be used.

The fixing pad 60 is made by fixing a base 61 and a sliding sheet 62, and then heating and firing a part of the sliding sheet 62. Specifically, in the sliding sheet 62, a non-fired part M1 (corresponding to the first sliding area) that includes the nip part NP and is not fired in a slightly wider area than the nip part NP in the conveying direction H and the width direction W. The portion other than the unfired portion M1 is a fired portion M2 (corresponding to the second sliding region). In this way, by using the fixing part 64, the base part 61 and the sliding sheet 62 can be firmly fixed. Moreover, by firing the sliding sheet 62 itself, the density of the second sliding area can be increased, and the density can be made different from that of the first sliding area.

It should be noted that the embodiments disclosed this time are illustrative in all respects and are not the basis for a limited interpretation. Therefore, the technical scope of the present disclosure should not be interpreted only by the above-described embodiments, but should be defined based on the claims. Furthermore, all changes within the meaning and scope of the claims are included.

1 Image forming device 17 Fixing device 31 Fixing belt 32 Pressure roller (an example of a pressure member)
60 Fixing pad 61 Base 61a Base pressing surface 61b Base side surface 62 Sliding sheet 62a Pressing surface fixing part 62b Side fixing part 63 Adhesive 64 Fixing part M1 Non-baking part M2 Baking part NP Nip part SE Non-adhesive part H Conveying direction W Width direction

Claims (6)

A fixing device that heats and presses paper held between a cylindrical endless belt and a pressure member to fix an image on the paper,
a fixing pad that contacts the inside of the endless belt and forms a nip portion that presses the paper together with the pressure member;
The fixing pad has a base and a sliding sheet that is fixed to the base and slides on the inside of the endless belt,
The sliding sheet is impregnated with a lubricant and has a first sliding region with a low density and a second sliding region with a higher density than the first sliding region,
The first sliding region is provided at a position that includes the nip portion,
The fixing device, wherein the second sliding area is provided at a position surrounding the outer periphery of the first sliding area. The fixing device according to claim 1,
The fixing device according to claim 1, wherein the sliding sheet is fixed to the base with an adhesive impregnated in the second sliding area. The fixing device according to claim 2,
The fixing device according to claim 1, wherein the sliding sheet is baked together with the adhesive and fixed to the base. The fixing device according to claim 1,
The fixing pad has a fixing part that fixes the base and the sliding sheet,
The fixing device, wherein the second sliding area is fired. The fixing device according to claim 1,
The base has a base pressing surface facing the inside of the fixing belt, and a base side surface extending from an outer edge of the base pressing surface,
In the sliding sheet, a pressing surface fixing part fixed to the base pressing surface and a side fixing part fixed to the base side surface are provided in the second sliding area. Device. An image forming apparatus comprising the fixing device according to any one of claims 1 to 5.

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