JP7512744B2 - Heating member, heating device, fixing device and image forming apparatus - Google Patents

Description

The present invention relates to a heating member, a heating device, a fixing device, and an image forming device.

One example of a heating device installed in an image forming device such as a copier or printer is a fixing device that fixes a toner image on paper using heat.

In addition, some fixing devices have a heating member such as a ceramic heater arranged inside an endless belt member. In this type of fixing device, when the belt member rotates, it slides against the heating member arranged inside it, generating sliding resistance (friction) between the belt member and the heating member. This sliding resistance increases the rotation torque of the belt member and accelerates wear of the belt member. Therefore, as a measure to reduce sliding resistance, it is common to apply a lubricant such as grease or oil to the inner surface of the belt member.

However, the amount of lubricant between the belt member and the heating member tends to decrease over time, and as the amount of lubricant decreases, a good sliding resistance reduction effect cannot be obtained. In response to this problem, Patent Document 1 (JP 2003-77621 A) proposes a method in which the surface of the heating member (ceramic heater) is polished to form multiple tiny recesses (polishing marks), and the lubricant is retained in these recesses, thereby maintaining the frictional resistance reduction effect of the lubricant for a long period of time.

However, the method proposed in Patent Document 1 requires additional processing such as polishing the surface of the heating element, which increases costs.

In order to solve the above problems, the present invention provides a heating member having a heat generating portion and a sliding surface along which a mating member slides relative to the heat generating portion via a lubricant, the sliding surface having a convex portion that is convex where the heat generating portion is provided, the convex portion having a concave portion that is concave toward the sliding direction of the mating member, a plurality of the concave portions being provided across the sliding direction of the mating member, and the concave portions being provided at different positions across the sliding direction being arranged so as to be offset from each other along the sliding surface in a direction intersecting the sliding direction .

According to the present invention, it is possible to form a recess on the sliding surface of the heating member without performing additional processing.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a fixing device according to the present embodiment. FIG. 3 is a diagram of the fixing device according to the present embodiment as viewed from above in FIG. 2 . 1 is a cross-sectional view of a heater according to a first embodiment of the present invention. FIG. 1 is a plan view of a heater according to a first embodiment of the present invention. 4 is an enlarged cross-sectional view showing a contact portion between a heater and a fixing belt. FIG. FIG. 5 is a plan view of a heater according to a second embodiment of the present invention. FIG. 11 is a plan view of a heater according to a third embodiment of the present invention. FIG. 4 is an enlarged plan view showing a recessed portion that does not have an inclined portion. FIG. 4 is an enlarged plan view showing a recess having an inclined portion. FIG. 10 is a plan view of a heater according to a fourth embodiment of the present invention. 13 is an enlarged plan view showing a heat generating portion in which recesses are arranged offset in the longitudinal direction. FIG. 13 is an enlarged plan view showing a heat generating portion in which recesses are arranged at the same position along the longitudinal direction. FIG. FIG. 13 is a plan view of a heater according to a fifth embodiment of the present invention. FIG. 13 is a plan view showing a modified example of the heat generating portion. FIG. 13 is a diagram showing the configuration of another fixing device. FIG. 13 is a diagram showing the configuration of another fixing device. FIG. 13 is a diagram showing the configuration of still another fixing device.

The present invention will be described below with reference to the attached drawings. In each drawing for explaining the present invention, components such as parts and components having the same function or shape are given the same reference numerals as far as possible to distinguish them, and the description will be omitted after the first description.

Figure 1 is a schematic diagram of an image forming apparatus according to one embodiment of the present invention.

The image forming device 100 shown in FIG. 1 includes an image forming unit 200, a transfer unit 300, a fixing unit 400, a recording medium supply unit 500, and a recording medium discharge unit 600.

The image forming section 200 is provided with four imaging units 1Y, 1M, 1C, and 1Bk, and an exposure device 6. Each imaging unit 1Y, 1M, 1C, and 1Bk is configured to be detachable from the image forming apparatus main body. In addition, each imaging unit 1Y, 1M, 1C, and 1Bk has a basically similar configuration except that it contains developers of different colors, yellow, magenta, cyan, and black, which correspond to the color separation components of a color image. Specifically, each imaging unit 1Y, 1M, 1C, and 1Bk includes a photoconductor 2, which is an image carrier that carries an image on its surface, a charging roller 3, which is a charging means for charging the surface of the photoconductor 2, a developing device 4, which is a developing means for forming a toner image on the photoconductor 2, and a cleaning blade 5, which is a cleaning means for cleaning the surface of the photoconductor 2. The exposure device 6 is a latent image forming means that exposes the charged surface of the photoconductor 2 based on image information to form an electrostatic latent image.

The transfer unit 300 is provided with a transfer device 8 that transfers an image onto a recording medium, which is paper. The recording medium on which an image is formed (transferred) may be paper (including plain paper, thick paper, thin paper, coated paper, label paper, envelopes, etc.), or a resin sheet such as an OHP sheet. The transfer device 8 has an intermediate transfer belt 11, four primary transfer rollers 12, and a secondary transfer roller 13. The intermediate transfer belt 11 is a transfer member that carries an image on its surface and transfers the image onto paper, and is composed of an endless belt member. Each primary transfer roller 12 contacts a different photoconductor 2 via the intermediate transfer belt 11. As a result, a primary transfer nip is formed between the intermediate transfer belt 11 and each photoconductor 2, where the intermediate transfer belt 11 and each photoconductor 2 contact each other. On the other hand, the secondary transfer roller 13 contacts one of the multiple rollers that stretch the intermediate transfer belt 11 via the intermediate transfer belt 11, and forms a secondary transfer nip between the intermediate transfer belt 11 and the secondary transfer roller 13.

The fixing section 400 is provided with a fixing device 9, which is a heating device that heats the paper and fixes the image on the paper by heat.

The recording medium supply unit 500 is provided with a paper feed cassette 14 that stores paper P, and a paper feed roller 15 that feeds paper P from the paper feed cassette 14.

The recording medium ejection section 600 is provided with a pair of ejection rollers 17 that eject paper outside the image forming device, and an ejection tray 18 on which the paper ejected by the ejection rollers 17 is placed.

Next, the printing operation of the image forming device 100 according to this embodiment will be described with reference to FIG.

When an instruction to start the printing operation is given, the photoconductors 2 of each of the imaging units 1Y, 1M, 1C, and 1Bk and the intermediate transfer belt 11 start to rotate. In addition, the paper feed roller 15 rotates, causing paper P to be fed out of the paper feed cassette 14. The fed paper P comes into contact with a pair of timing rollers 16 and is temporarily stopped.

In each imaging unit 1Y, 1M, 1C, 1Bk, the surface of the photoconductor 2 is first charged to a uniform high potential by the charging roller 3. Next, the exposure device 6 exposes the surface (charged surface) of each photoconductor 2 based on the image information of the document read by the document reading device or the print image information instructed to be printed from the terminal. This reduces the potential of the exposed part and forms an electrostatic latent image on the surface of each photoconductor 2. Toner is then supplied from the developing device 4 to this electrostatic latent image, and a toner image is formed on each photoconductor 2. When the toner image formed on each photoconductor 2 reaches the primary transfer nip (the position of the primary transfer roller 12) as each photoconductor 2 rotates, it is transferred to the rotating intermediate transfer belt 11 so as to be overlapped in sequence. Thus, a full-color toner image is formed on the intermediate transfer belt 11. After the toner image is transferred from the photoreceptor 2 to the intermediate transfer belt 11, the toner and other foreign matter remaining on each photoreceptor 2 is removed by the cleaning blade 5, and the photoreceptor 2 is prepared for the formation of the next electrostatic latent image.

The toner image transferred onto the intermediate transfer belt 11 is transported to the secondary transfer nip (the position of the secondary transfer roller 13) as the intermediate transfer belt 11 rotates, and is transferred onto the paper P that has been transported by the timing roller 16. The paper P onto which the toner image has been transferred is then transported to the fixing device 9, which fixes the toner image onto the paper P. The paper P is then discharged onto the paper discharge tray 18 by the paper discharge rollers 17, completing the printing process.

The above description of the printing operation is for forming a full-color image, but it is also possible to use any one of the four imaging units to form a monochrome image, or to use two or three imaging units to form a two- or three-color image.

Next, we will explain the configuration of the fixing device 9 according to this embodiment.

As shown in FIG. 2, the fixing device 9 according to this embodiment includes a fixing belt 20, a pressure roller 21, a heater 22, a heater holder 23, a stay 24, and a temperature sensor 19.

The fixing belt 20 is a rotating member (first rotating member) that contacts the unfixed toner carrying surface of the paper P to fix the toner image to the paper P. The fixing belt 20 is composed of an endless belt member having a cylindrical substrate with an outer diameter of 25 mm and a thickness of 40 to 120 μm. The substrate may be made of a heat-resistant resin such as PEEK or a metal material such as nickel or SUS, in addition to polyimide. In addition, in order to increase durability and ensure releasability, a release layer made of a fluororesin such as PFA or PTFE may be provided on the outer peripheral surface of the substrate. An elastic layer made of rubber or the like may be provided between the substrate and the release layer. Furthermore, a sliding layer made of polyimide, PTFE, or the like may be provided on the inner peripheral surface of the substrate.

The fixing belt 20 is rotatably held by a pair of belt holding members 28 (see FIG. 3) that serve as rotating holding members provided on a pair of side plates 29. Each belt holding member 28 is formed, for example, in a flange shape, and is inserted with some slack into both ends of the fixing belt 20 in the longitudinal direction Z. Therefore, in a non-rotating state with the pair of belt holding members 28 inserted into both ends, the fixing belt 20 is basically held in a state where no circumferential tension is applied, in other words, in a so-called free belt method.

The pressure roller 21 is a rotating member (second rotating member) that is arranged to face the outer circumferential surface of the fixing belt 20. The pressure roller 21 is, for example, 25 mm in outer diameter and is composed of a roller having an iron core, an elastic layer made of silicone rubber provided on the outer circumferential surface of the core, and a release layer made of fluororesin provided on the outer circumferential surface of the elastic layer.

The pressure roller 21 is pressed against the fixing belt 20 by a biasing member such as a spring, and a nip portion N is formed between the fixing belt 20 and the pressure roller 21. When the pressure roller 21 rotates while being pressed against the fixing belt 20, the rotational drive force is transmitted to the fixing belt 20 at the nip portion N, and the fixing belt 20 rotates accordingly. Then, as shown in FIG. 2, when a sheet P carrying an unfixed image enters between the rotating fixing belt 20 and the pressure roller 21 (nip portion N), the sheet P is heated and pressurized by the fixing belt 20 and the pressure roller 21, and the unfixed image is fixed to the sheet P.

The heater 22 is a plate-shaped heating member that heats the fixing belt 20. The heater 22 is disposed inside the fixing belt 20 and is in contact with the inner peripheral surface of the fixing belt 20. The heater 22 may be disposed so as to be in contact with the outer peripheral surface of the fixing belt 20. However, in that case, if the outer peripheral surface of the fixing belt 20 is damaged by contact with the heater 22, there is a risk that the quality of the fixed image will deteriorate. Therefore, in order to avoid deterioration in image quality, it is preferable to have the heater 22 in contact with the inner peripheral surface of the fixing belt 20.

Specifically, the heater 22 is composed of a plate-shaped substrate 50, a first insulating layer 51 provided on the substrate 50, a conductor layer 52 provided on the first insulating layer 51, a second insulating layer 53 covering the conductor layer 52, and a third insulating layer 54 provided on the surface of the substrate 50 opposite to the surface on which the first insulating layer 51 is provided. The conductor layer 52 has a heat generating portion 60 that generates heat when power is supplied. In addition to the heat generating portion 60, the conductor layer 52 also has a plurality of electrode portions for supplying power to the heat generating portion 60, and a power supply line (conductive portion) connecting the electrode portions and the heat generating portion 60. A connector as a power supply member is connected to each electrode portion, and power is supplied to the heat generating portion 60 from the power supply of the image forming apparatus main body via the connector, causing the heat generating portion 60 to generate heat.

In addition, in order to reduce the sliding resistance of the fixing belt 20 against the heater 22 when the fixing belt 20 rotates, a lubricant such as grease or oil is interposed between the sliding surfaces of the fixing belt 20 and the heater 22. As the lubricant, a liquid lubricant containing any one of silicone oil, silicone grease whose base oil is silicone oil, fluorosilicone oil, fluorosilicone grease whose base oil is fluorosilicone oil, fluorine oil, or fluorine grease whose base oil is fluorine oil, or a combination of these, is preferable.

The heater holder 23 is a holding member that holds the heater 22 inside the fixing belt 20. The heater holder 23 is desirably made of a heat-resistant material because it is prone to becoming hot due to the heat of the heater 22. In particular, when the heater holder 23 is made of a heat-resistant resin with low thermal conductivity such as LCP or PEEK, the heat resistance of the heater holder 23 is ensured while heat transfer from the heater 22 to the heater holder 23 is suppressed, making it possible to efficiently heat the fixing belt 20.

The stay 24 is a reinforcing member disposed on the inside of the fixing belt 20. The stay 24 supports the surface of the heater holder 23 opposite the surface on the nip portion N side, thereby preventing the heater holder 23 from bending due to the pressure of the pressure roller 21. This forms a nip portion N of uniform width between the fixing belt 20 and the pressure roller 21. The stay 24 is preferably formed from an iron-based metal material such as SUS or SECC to ensure its rigidity.

The temperature sensor 19 is a temperature detection means for detecting the temperature of the heater 22. The output of the heater 22 is controlled based on the detection result of the temperature sensor 19, thereby maintaining the temperature of the fixing belt 20 at a desired temperature (fixing temperature). As the temperature sensor 19, a known sensor such as a thermopile, thermostat, thermistor, or NC sensor can be used.

Figures 4 and 5 are a cross-sectional view and a plan view of the heater 22 according to the first embodiment of the present invention.

4 and 5, the direction indicated by the arrow A is the sliding direction (belt rotation direction) in which the fixing belt 20 slides relative to the heater 22. That is, when the fixing belt 20 rotates, the fixing belt 20 moves and slides in the direction of the arrow A relative to the heater 22. In this embodiment, the second insulating layer 53 of the heater 22 contacts the inner peripheral surface of the fixing belt 20, which is the mating member, via a lubricant (see FIG. 2), so that the contact surface of the second insulating layer 53 with the fixing belt 20 (the upper surface in FIG. 4) becomes the sliding surface S on which the fixing belt 20 slides relatively. In this specification, the direction B (see FIG. 5) that intersects with the sliding direction A of the fixing belt 20 along this sliding surface S is referred to as the "longitudinal direction" of the heater 22, and the direction C (see FIG. 4) that intersects with both the longitudinal direction B and the sliding direction A of the fixing belt 20 is referred to as the "thickness direction" of the heater 22. The configuration of the heater 22 will be described in detail below.

As shown in FIG. 4, the heater 22 is constructed by stacking a base material 50, a heat generating portion 60 (conductor layer 52), and each insulating layer 51, 53, and 54 in the thickness direction C.

The substrate 50 is made of a metal material such as stainless steel (SUS), iron, or aluminum. In addition to metal materials, ceramics, glass, and the like can also be used as the material for the substrate 50. When an insulating material such as ceramics is used for the substrate 50, the first insulating layer 51 between the substrate 50 and the conductor layer 52 can be omitted. On the other hand, metal materials are excellent in durability against rapid heating and are easy to process, making them suitable for reducing costs. Among metal materials, aluminum and copper are particularly preferred because they have high thermal conductivity and are less likely to cause temperature unevenness. Stainless steel also has the advantage of being cheaper to manufacture than these.

The heating portion 60 of the conductor layer 52 is composed of a resistive heating element with a thickness of about 1 μm to 5 μm. The resistive heating element is formed, for example, by applying a paste made of silver palladium (AgPd) and glass powder to the substrate 50 or the first insulating layer 51 by a method such as screen printing, and then firing the paste. Resistive materials such as silver alloy (AgPt) and ruthenium oxide (RuO2) may also be used as the material for the resistive heating element.

Each of the insulating layers 51, 53, 54 is made of an insulating material such as heat-resistant glass. These materials may also be ceramic or polyimide. Increasing the thickness of each of the insulating layers 51, 53, 54 can improve the insulation. However, making these layers too thick can reduce the thermal conductivity from the heat generating section 60 to the fixing belt 20 and increase costs, so the thickness of each of the insulating layers 51, 53, 54 is preferably 10 μm to 300 μm, and more preferably 30 μm to 150 μm.

As shown in FIG. 4, when the second insulating layer 53 is coated on the heating portion 60, the heating portion 60 has a certain thickness, so the surface of the second insulating layer 53 becomes convex in the area where the heating portion 60 is provided, and a step of approximately the thickness of the heating portion 60 (for example, approximately 1 μm to 5 μm) is formed. In other words, the sliding surface S of the second insulating layer 53 has a convex portion 30 that is convex in the thickness direction C in the area where the heating portion 60 is provided.

In this manner, in this embodiment, the convex portion 30 is formed following the shape of the heat generating portion 60, and this convex portion 30 is used to form a lubricant reservoir as described below.

That is, a rectangular recess 61 (see FIG. 5) recessed toward the sliding direction A of the fixing belt 20 is formed in advance in the heat generating portion 60, and the second insulating layer 53 is coated on the heat generating portion 60. As a result, a protrusion 30 having a recess 40 is formed in the second insulating layer 53 following the shape of the heat generating portion 60. In the portion where the recess 40 is provided, the surface of the second insulating layer 53 has a low step in the thickness direction C. Therefore, as shown in FIG. 6, when the fixing belt 20 contacts the sliding surface S of the heater 22, a gap G is formed between the fixing belt 20 and the recess 40.

The lubricant 70 is held in this gap G (recess 40), so that the lubricant 70 is well interposed between the fixing belt 20 and the heater 22, reducing sliding resistance. Furthermore, since the recess 40 is formed to be recessed in the sliding direction A, when the fixing belt 20 rotates, even if the lubricant receives a force in the rotational direction, the lubricant moves in the direction in which it is accommodated within the recess 40. This allows the lubricant to be well held within the recess 40.

In this manner, in this embodiment, the sliding surface S of the heater 22 is formed with a recess 40 recessed toward the sliding direction A of the fixing belt 20, so that the lubricant can be well retained between the fixing belt 20 and the heater 22 for a long period of time, and the wear of the fixing belt 20 and the increase in rotational torque caused by the sliding resistance can be effectively suppressed. Furthermore, in this embodiment, such a recess 40 can be formed simply by changing the shape of the heat generating portion 60, so additional processing such as polishing the surface of the heater to form the recess 40 is not required. Therefore, according to the configuration of this embodiment, a configuration that can well retain the lubricant for a long period of time can be realized at low cost.

Next, an embodiment that differs from the first embodiment described above will be described. Note that in the following explanation, the differences from the first embodiment will be mainly described, and the other parts will be omitted as they are basically configured in the same way.

Figure 7 is a plan view of a heater 22 according to a second embodiment of the present invention.

In the heater 22 shown in FIG. 7, multiple recesses 40 serving as lubricant reservoirs are provided along the longitudinal direction B of the heater 22 (a direction intersecting the sliding direction A along the sliding surface S).

In this way, in the second embodiment, by providing multiple recesses 40 in the longitudinal direction B, it is possible to hold the lubricant over a wide range and increase the amount of lubricant held. This makes it possible to reduce sliding resistance more effectively.

Figure 8 is a plan view of a heater 22 according to a third embodiment of the present invention.

In the heater 22 shown in FIG. 8, the recess 40 is formed in a trapezoidal or triangular shape. Therefore, the recess 40 has a pair of inclined portions 41 that approach each other in the sliding direction A of the fixing belt 20.

In this way, in the third embodiment, the recess 40 has a pair of inclined portions 41, which makes it possible to suppress wear of the fixing belt 20 compared to the heaters of the first and second embodiments described above.

That is, as shown in FIG. 9, in the recess 40 without the inclined portion 41, a pair of opposing side surfaces 40a, 40b extend in the sliding direction A of the fixing belt 20, so that when the fixing belt 20 rotates, the edges (steps) of the side surfaces 40a, 40b hit the same part of the fixing belt 20 in a concentrated manner, and the fixing belt 20 is likely to wear out. In contrast, as shown in FIG. 10, in the recess 40 with the inclined portion 41, the pair of side surfaces 40a, 40b are inclined with respect to the sliding direction A, so that the edges of the side surfaces 40a, 40b can be prevented from concentrating and contacting a specific part of the fixing belt 20. This makes it possible to suppress the promotion of wear in a specific part of the fixing belt 20, and to improve the durability of the fixing belt 20. In addition, since the recess 40 has a pair of inclined portions 41, when the fixing belt 20 rotates, the lubricant is guided to the center of the recess 40 along the inclined portions 41, so that the lubricant is easily collected and retained in the recess 40.

The inclination angles of the inclined portions 41 with respect to the sliding direction A do not have to be the same as each other, but may be different angles. Furthermore, the inclined portions 41 may be straight lines (flat surfaces) or curved lines (curved surfaces).

However, when recesses 61 are formed in the heat generating section 60 as in the above-described embodiments, the width of the heat generating section 60 varies in the longitudinal direction B, causing variation in the resistance value of the heat generating section 60 between the portion where the recesses 61 are formed and the other portions. This causes a change in the amount of heat generated, causing variation in the heat generation distribution of the heater 22 in the longitudinal direction B. This variation in the heat generation distribution may affect the fixing quality, such as causing uneven gloss in the image.

In the fourth embodiment of the present invention shown in FIG. 11, in order to suppress the variation in the heat distribution of the heater 22, the heat generating parts 60 are arranged in two rows across the sliding direction A, and the recesses 61 of the heat generating part 60 on the upper side of the figure and the recesses 61 of the heat generating part 60 on the lower side of the figure are shifted from each other in the longitudinal direction B (a direction that crosses the sliding direction A along the sliding surface S). That is, as shown in FIG. 12, in the longitudinal direction B of the heater 22, the central part β of the recess 61 on the lower side of the figure is located between the central parts α of the recesses 61 on the upper side of the figure. In this example, the central part β of the lower recess 61 is located at a middle position that is the same distance away from the central parts α of the adjacent upper recesses 61, but the position of the lower recess 61 may be shifted from the middle position.

In this way, the recesses 61 (upper recess 61 and lower recess 61) provided at different positions in the sliding direction A are arranged offset in the longitudinal direction B, so that the narrower portion of one heat generating part 60 corresponds to the wider portion of the other heat generating part 60. In other words, the lower portion of the heat generating part 60 corresponds to the higher portion of the heat generating part 60, so that the variation in the heat distribution in the longitudinal direction B can be suppressed. In this case, the recesses 40 functioning as lubricant reservoirs are also arranged offset from each other in the longitudinal direction B, so that the lubricant can be dispersed and held over a wide range, and the sliding resistance can be reduced more effectively. In addition, in this embodiment, the heat generating parts 60 may be arranged in three or more rows (multiple) in the sliding direction A.

The example shown in FIG. 13, on the other hand, is different from the example shown in FIG. 12 above, in that the recess 61 on the upper side of the figure and the recess 61 on the lower side of the figure are arranged at the same position in the longitudinal direction B. From the viewpoint of suppressing the variation in the heat generation distribution of the heater 22, it is preferable to adopt the example shown in FIG. 12, but the present invention is not limited to this. If the variation in the temperature distribution is tolerable, it is also possible to adopt the example shown in FIG. 13.

As another measure against the variation in temperature distribution of the heater 22, the heat generating portion 60 may be formed in a curved shape, such as a wave shape that extends at a constant width, as in the fifth embodiment of the present invention shown in FIG. 14. In this case, the resistance value of the heat generating portion 60 does not change across the longitudinal direction B of the heater 22, so no variation in temperature distribution occurs.

Therefore, by making the heat generating portion 60 curved with a constant width, it is possible to form the recess 40 that functions as a lubricant reservoir without causing variation in heat distribution. Also, in the case of the example shown in FIG. 14, the recess 40 has an inclined portion 41 that is inclined with respect to the sliding direction A, so that, as in the third embodiment (see FIG. 8) described above, it is possible to prevent the edge of the recess 40 from concentrating and hitting a specific portion of the fixing belt 20, and the inclined portion 41 makes it easier to collect lubricant in the recess 40.

The shape of the heat generating section 60 may be a shape other than a curved shape. For example, as shown in the example of FIG. 15, the heat generating section 60 may be a broken line shape made up of multiple straight lines connected in different directions. The shape of the heat generating section 60 may also be a shape that combines a curve and a broken line.

The above describes the embodiments and examples of the present invention, but the present invention is not limited to the above-mentioned embodiments or examples, and various modifications can be made without departing from the spirit of the invention.

The present invention is not limited to the fixing device shown in FIG. 2, but can also be applied to fixing devices such as those shown in FIGS. 16 to 18.

The fixing device 9 shown in FIG. 16 differs from the fixing device shown in FIG. 2 in that the nip portion N through which the paper P passes and the portion where the fixing belt 20 is heated by the heater 22 are located at different positions. Specifically, the heater 22 and the nip forming member 90 are located 180° opposite each other in the rotation direction of the fixing belt 20, and pressure rollers 91 and 92 are pressed against them via the fixing belt 20.

The fixing device 9 shown in FIG. 17 is an example in which the pressure roller 92 on the heater 22 side shown in FIG. 16 is omitted, and furthermore, the heater 22 is formed in an arc shape to match the curvature of the fixing belt 20. Other than that, it is the same as the configuration shown in FIG. 16. In this case, by forming the heater 22 in an arc shape, the contact length between the fixing belt 20 and the heater 22 in the belt rotation direction is secured, and the fixing belt 20 can be heated efficiently.

The fixing device 9 shown in FIG. 18 is an example in which belts 94 and 95 are arranged on either side of a roller 93. In this case, as in the examples shown in FIG. 16 and FIG. 17, the nip portion N through which the paper P passes and the portion heated by the heater 22 are set in different positions. That is, the nip forming member 90 contacts the roller 93 via one belt 94 on the right side of the figure, and the heater 22 contacts the roller 93 via the other belt 95 on the opposite side.

By applying the present invention to a fixing device such as that shown in Figures 16 to 18, a recess 40 that functions as a lubricant reservoir can be formed in the heater 22 without additional processing, making it possible to retain the lubricant well for a long period of time.

The present invention is not limited to a configuration in which the fixing belt 20 is held in a free belt manner as shown in FIG. 3, but can also be applied to a configuration in which the fixing belt is stretched by multiple rollers, etc.

In addition, in each of the above-described embodiments, the present invention has been described as being applied to a fixing device, which is an example of a heating device, but the present invention is not limited to being applied to fixing devices. For example, the present invention can also be applied to a heating device such as a drying device that heats paper to dry ink (liquid) on the paper in an inkjet image forming device.

9 Fixing device (heating device)
20 Fixing belt (belt member)
21 Pressure roller (opposing member)
22 Heater (heating member)
30 Convex portion 40 Concave portion 41 Inclined portion 60 Heat generating portion 70 Lubricant 100 Image forming apparatus A Sliding direction P Paper (recording medium)
S Sliding surface

JP 2003-77621 A

Claims (7)

A heating member having a heat generating portion and a sliding surface on which a mating member slides relatively via a lubricant,
the sliding surface has a convex portion that is convex at a portion where the heat generating portion is provided,
The protruding portion has a recessed portion recessed toward a sliding direction of the counter member,
The recessed portion is provided in a plurality of portions across the sliding direction of the mating member,
The recesses provided at different positions across the sliding direction are arranged along the sliding surface so as to be shifted from each other in a direction intersecting the sliding direction . The heating member according to claim 1, wherein the recess has an inclined portion that is inclined with respect to the sliding direction of the mating member. The heating member according to claim 2, wherein the recess has a pair of inclined portions that are inclined toward each other in the sliding direction of the mating member. 4. The heating member according to claim 1, wherein the heat generating portion is formed in a curved shape extending with a constant width, in a broken line shape, or in a shape combining a curved line and a broken line. A rotatable endless belt member;
an opposing member that contacts an outer circumferential surface of the belt member;
The heating member according to any one of claims 1 to 4, which is in contact with an inner circumferential surface of the belt member via a lubricant and slides relatively against the rotating belt member;
A heating device comprising : A fixing device for fixing an image on a recording medium by using the heating device according to claim 5 . An image forming apparatus comprising the heating device according to claim 5 or the fixing device according to claim 6 .

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