JP7471563B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming device.

Known heating devices installed in image forming devices such as copiers and printers include fixing devices that fix images on recording media using heat, and drying devices that dry ink on recording media.

For example, Patent Document 1 (JP 2017-187806 A) proposes a fixing device equipped with a fan that blows air onto the film or roller to improve the problem of temperature rise in non-paper passing areas of the film or roller that sandwiches and heats the recording medium, and the problem of recording medium slippage when water vapor condenses.

In the fixing device described in Patent Document 1, air is blown from a fan to cool the non-paper passing areas of the film and roller, preventing excessive temperature rise, and water vapor is expelled from the vicinity of the film and roller to another location, preventing slippage of the recording medium due to condensation.

However, in the fixing device described in Patent Document 1, the range in which air is blown from the fan to the film or roller is mainly the non-paper passing areas on both ends of the film or roller in the longitudinal direction, so it is difficult to obtain the effect of blowing air in the paper passing area on the central side in the longitudinal direction. Therefore, the object is to effectively remove water vapor generated especially on the central side in the longitudinal direction (paper passing area) from around the heating device.

In order to solve the above problems, the present invention provides an image forming apparatus including a heating device for heating a recording medium, an airflow generating device for generating an airflow, and a flow path forming member for guiding the airflow generated by the airflow generating device, wherein the heating device includes a heat source, a heating member heated by the heat source, and an opposing member facing the heating member to form a nip portion between the heating member and the opposing member, the flow path forming member having a pair of cooling flow paths and a water vapor recovery flow path in which the pair of cooling flow paths join at respective upper portions of the pair of cooling flow paths, and being a cylindrical duct extending from below the opposing member toward above the opposing member, the passage has a cooling port arranged to face the opposing member, the water vapor recovery flow path has a water vapor inlet arranged above the opposing member and at a position closer to the longitudinal center of the opposing member than the cooling port , the duct draws air into the pair of cooling flow paths from below the opposing member, blows the drawn air onto the opposing member through the cooling ports of the pair of cooling flow paths, causes at least a portion of the water vapor generated when the recording medium is heated to flow from the water vapor inlet into the water vapor recovery flow path, and discharges the water vapor to the outside together with the air blown onto the opposing member .

The present invention allows water vapor to be effectively removed from the surroundings of the heating device.

1 is a schematic diagram 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. 2 is a side view of the blower fan and the duct according to the embodiment. FIG. 2 is a rear view of the blower fan and the duct according to the embodiment. FIG. 2 is a perspective view of a blower fan and a duct according to the embodiment. FIG. 13 is a diagram showing a configuration according to another embodiment of the present invention.

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 the 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 device 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. In FIG. 1, only the photoconductor 2, charging roller 3, developing device 4, and cleaning device 5 of one imaging unit 1Bk are labeled with reference numerals, and the reference numerals of the other imaging units 1Y, 1M, and 1C are omitted.

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 of the imaging units 1Y, 1M, 1C, and 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. Then, toner is 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 that the toner images are overlapped one after another. Thus, a full-color toner image is formed on the intermediate transfer belt 11. After the toner image is transferred from the photoconductor 2 to the intermediate transfer belt 11, the toner and other foreign matter remaining on each photoconductor 2 is removed by the cleaning device 5, and the photoconductor 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 nip forming member 23, a stay 24, a reflecting member 25, a high thermal conductivity member 26, and a separating member 27.

The fixing belt 20 is a heating member that is heated by the heater 22, and is also a fixing member that fixes an unfixed image on the paper P. Specifically, the fixing belt 20 is composed of an endless belt member (including a film) having a base material formed of a metal material such as nickel or SUS, or a resin material such as polyimide (PI), and a release layer formed on the outer peripheral surface of the base material and made of tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA) or polytetrafluoroethylene (PTFE). In addition, an elastic layer formed of a rubber material such as silicone rubber, foamed silicone rubber, or fluororubber may be interposed between the base material and the release layer.

The pressure roller 21 is an opposing member arranged to face the outer peripheral surface of the fixing belt 20, and is a pressure member that presses the fixing belt 20. Specifically, the pressure roller 21 is composed of a core metal, an elastic layer made of foamed silicone rubber, silicone rubber, or fluororubber, etc., provided on the surface of the core metal, and a release layer made of PFA or PTFE, etc., provided on the surface of the elastic layer. The pressure roller 21 is pressed (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. In addition, the pressure roller 21 is configured to be rotated by a drive source provided in the image forming apparatus body. When the pressure roller 21 is rotated, the driving force is transmitted to the fixing belt 20 at the nip portion N, and the fixing belt 20 is rotated. As shown in FIG. 2, when a sheet of paper P carrying an unfixed image enters the nip N between the rotating fixing belt 20 and pressure roller 21, the sheet of paper P is heated and pressurized by the fixing belt 20 and pressure roller 21, and the unfixed image is fixed to the sheet of paper P.

In this embodiment, the pressure roller 21 is a solid roller, but it may be a hollow roller. In that case, a heater may be disposed inside the pressure roller 21. Also, if the pressure roller 21 does not have an elastic layer, the heat capacity is reduced, and the fixing performance is improved. However, on the other hand, when fixing unfixed toner, minute irregularities on the belt surface may be transferred to the image, causing uneven gloss in the solid part of the image. To prevent this, it is desirable for the pressure roller 21 to have an elastic layer with a thickness of 100 μm or more. By having an elastic layer with a thickness of 100 μm or more, minute irregularities can be absorbed by the elastic deformation of the elastic layer, and the occurrence of uneven gloss can be avoided. The elastic layer of the pressure roller 21 may be solid rubber, but if there is no heater inside the pressure roller 21, sponge rubber can also be used. Sponge rubber is more desirable than solid rubber in that it has higher insulation properties and is less likely to take away heat from the fixing belt 20.

The heater 22 is a heat source that heats the fixing belt 20. In this embodiment, a halogen heater is used as the heater 22. In addition to the halogen heater, other radiant heat heaters such as carbon heaters and ceramic heaters may be used. It is also possible to use an electromagnetic induction heating type heat source. In this embodiment, two heaters 22 are arranged in the fixing belt 20, but the number of heaters 22 may be one, or three or more.

The nip forming member 23 is disposed inside the fixing belt 20 and forms a nip portion N between the fixing belt 20 and the pressure roller 21 by receiving pressure from the pressure roller 21. It is preferable to use a heat-resistant material having a heat resistance temperature of 200°C or higher as the material of the nip forming member 23. Specifically, the material of the nip forming member 23 includes general heat-resistant resins such as polyethersulfone (PES), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyethernitrile (PEN), polyamideimide (PAI), and polyetheretherketone (PEEK). By constructing the nip forming member 23 from such a heat-resistant material, it is possible to prevent the nip forming member 23 from deforming due to heat in the fixing temperature range, so that a stable state of the nip portion N can be ensured and the output image quality can be stabilized.

The stay 24 is a support member that contacts the side of the nip forming member 23 opposite the pressure roller 21 side and supports the nip forming member 23. By supporting the nip forming member 23 with the stay 24, deflection of the nip forming member 23 due to the pressure of the pressure roller 21, particularly deflection of the nip forming member 23 across the longitudinal direction of the fixing belt 20, is suppressed, and a nip portion N of uniform width is formed. In order to ensure rigidity, an iron-based metal material such as SUS or SECC is preferable as the material for the stay 24.

The reflective member 25 is a member that reflects heat and light (e.g., infrared light) radiated from the heater 22. The reflective member 25 reflects the heat and light of the heater 22 toward the fixing belt 20, thereby efficiently heating the fixing belt 20. In addition, the reflective member 25 is disposed between the stay 24 and the heater 22, and can also suppress heating of the stay 24 by the heater 22. This reduces the wasteful consumption of thermal energy, and also contributes to energy conservation.

The function of the reflective member 25 may also be imparted to the stay 24. For example, the surface of the stay 24 facing the heater 22 may be mirror-finished so that the stay 24 also functions as the reflective member 25. In this case, there is no need to provide a separate reflective member 25, which is advantageous for miniaturization and cost reduction.

The highly thermally conductive member 26 is interposed between the nip forming member 23 and the fixing belt 20, and functions as a heat equalizing member that transfers the heat of the fixing belt 20 in its longitudinal direction and equalizes the surface temperature of the fixing belt 20. The highly thermally conductive member 26 is made of a material having a higher thermal conductivity than the nip forming member 23. For example, copper, aluminum, or silver can be used as the material for the highly thermally conductive member 26.

The separating member 27 is a member that separates the paper P discharged from the nip portion N from the fixing belt 20. The separating member 27 is disposed so as to face the outer peripheral surface of the fixing belt 20 on the exit side (downstream side in the paper transport direction) of the nip portion N. When the paper P is discharged from the nip portion N, the leading edge of the paper P comes into contact with the separating member 27, thereby separating the paper P from the surface of the fixing belt 20 and preventing the paper P from wrapping around the fixing belt 20.

In the nip area where paper passes through, the heat of the fixing belt and pressure roller tends to be absorbed by the paper, whereas in the non-paper passing area where paper does not pass through, the heat of the fixing belt and pressure roller tends not to be absorbed as easily. For this reason, especially when multiple sheets of paper are fixed in succession, the heat of the fixing belt and pressure roller accumulates in the non-paper passing area, causing a rise in temperature, a problem known as edge temperature rise.

In addition, when the paper is heated during the fixing process in the fixing device, the moisture contained in the paper turns into water vapor and is released into the surroundings from the nip. This water vapor then condenses in the fixing device and its surroundings. If the water droplets formed by the condensation adhere to the surface of the pressure roller, slippage occurs between the paper and the pressure roller, which causes problems such as poor image quality and poor transport. In addition, if the water droplets formed by the condensation adhere to guide members installed in the paper transport path, water droplet marks may be left on the paper, resulting in poor image quality, or in the case of double-sided printing, water droplets may adhere to the back side of the paper, making it impossible to form an image.

In this embodiment, therefore, in order to prevent temperature rises in the fixing belt and pressure roller in non-paper passing areas and slippage due to condensation of water vapor, a blower fan 30 and duct 31 are provided around the fixing device 9 as shown in Figures 3 to 5. The configuration of the blower fan 30 and duct 31 will be described below.

Figures 3 to 5 are a side view, a rear view, and a perspective view, respectively, of the blower fan 30 and duct 31 according to this embodiment.

As shown in Figures 3 to 5, the image forming apparatus 100 according to this embodiment is provided with a blower fan 30 as an airflow generating device that generates an airflow around the fixing device 9, and a duct 31 as a flow path forming member that guides the airflow generated by the blower fan 30. The duct 31 is provided so as to extend from roughly below the pressure roller 21, passing through the side opposite the nip portion N of the pressure roller 21, toward above the pressure roller 21. The blower fan 30 is disposed below the duct 31, and the airflow from the blower fan 30 is configured to be guided upward through the duct 31.

As shown in Figures 4 and 5, the duct 31 has a pair of cooling channels 32 arranged at positions spaced apart from each other in the longitudinal direction X of the pressure roller 21, and a water vapor recovery channel 33 where the cooling channels 32 join. Note that in this specification, the "longitudinal direction X of the pressure roller 21" refers to the axial direction of the pressure roller 21, and means the same direction as the paper width direction (recording medium width direction) that is perpendicular to the paper feed direction (recording medium passing direction).

The pair of cooling channels 32 have cooling ports 34 that face the surface of the pressure roller 21 on the side opposite the nip portion N. Therefore, at the locations where each cooling port 34 is provided, the air flow passing through the cooling channels 32 is blown onto the surface of the pressure roller 21.

The water vapor recovery passage 33 has multiple water vapor inlets 35 provided on the surface facing downward above the pressure roller 21. Therefore, water vapor generated from the paper during the fixing process flows from the water vapor inlets 35 into the water vapor recovery passage 33 of the duct 31.

Here, the symbol W1 in FIG. 4 is the minimum paper passing area through which the minimum width paper passes. On the other hand, the symbol W2 in FIG. 4 is the maximum paper passing area through which the maximum width paper passes. For example, if the minimum width paper is A6 size and the maximum width paper is A4 size, the minimum paper passing area W1 is 105 mm and the maximum paper passing area W2 is 210 mm. In this embodiment, the water vapor inlet 35 is located within the minimum paper passing area W1, and each cooling port 34 is located outside the minimum paper passing area W1 and within the maximum paper passing area W2.

In the image forming apparatus according to the present embodiment, when multiple sheets of paper of the minimum width are passed continuously, the temperature of the fixing belt 20 and the pressure roller 21 rises because the heat of the fixing belt 20 and the pressure roller 21 is not easily taken away by the paper in the non-paper passing area outside the minimum paper passing area W1. However, in the image forming apparatus according to the present embodiment, a pair of cooling ports 34 are arranged in the non-paper passing area where the minimum width paper does not pass (specifically, the area W3 outside the minimum paper passing area W1 and within the maximum paper passing area W2 shown in FIG. 4), so that the non-paper passing area of the pressure roller 21 is cooled by the airflow blown from each cooling port 34. This also cools the non-paper passing area of the fixing belt 20. That is, the airflow flowing through the duct 31 is mainly blown onto the surface portion of the pressure roller 21 opposite the nip portion N through each cooling port 34, and the surface portion of the pressure roller 21 cooled in this way comes into contact with the fixing belt 20 at the nip portion N as the pressure roller 21 rotates, and absorbs the heat of the fixing belt 20, thereby indirectly cooling the fixing belt 20. This makes it possible to suppress excessive temperature rise of the fixing belt 20 and the pressure roller 21 in the non-paper passing area.

In addition, in the image forming apparatus according to the present embodiment, even if water vapor is generated from the paper during the fixing process, at least a part of the generated water vapor is collected by flowing into the duct 31 (water vapor recovery passage 33) through the water vapor inlet 35 arranged above the pressure roller 21. In particular, since the water vapor inlet 35 is arranged corresponding to the paper passage area W1 where water vapor is likely to be generated, water vapor generated in the paper passage area W1 can be efficiently collected. The collected water vapor passes through the duct 31 along the flow of the air flow and is discharged to the outside of the image forming apparatus from the exhaust port 36 (see FIG. 4) provided at the most downstream of the duct 31. This reduces the water vapor remaining around the fixing device 9, and suppresses paper slippage and image defects caused by condensation of water vapor. In addition, the exhaust port 36 also discharges air that has been warmed by being blown against the pressure roller 21, so that hot air can be suppressed from remaining around the fixing device 9. This makes it possible to lower the temperature around the fixing device 9 and improve cooling efficiency. The exhaust port 36 of the duct 31 may be located inside the image forming device, not in a portion facing the outside of the image forming device. Even in such a case, by locating the exhaust port 36 outside the paper transport path (outside the recording medium transport path), it is possible to remove hot air and water vapor from the periphery of the fixing device 9 and the periphery of the paper transport path, and it is possible to prevent paper slippage and image defects caused by condensation.

As described above, in the image forming apparatus according to this embodiment, the duct 31 has a cooling port 34 arranged in the non-paper passing area W3 and a water vapor inlet 35 arranged in the paper passing area W1, so that it is possible to effectively suppress both an excessive temperature rise of the fixing belt 20 and the pressure roller 21 in the non-paper passing area W3 and condensation of water vapor generated from the paper. This reduces the risk of damage to parts due to an excessive temperature rise of the fixing belt 20 and the pressure roller 21, and paper slippage and image defects due to condensation, improving reliability. In addition, by adopting a duct structure such as that of this embodiment, it is no longer necessary to take measures to suppress the temperature rise of the fixing belt 20 and the pressure roller 21, such as slowing down the fixing process speed, and it is also possible to improve the productivity of small size paper.

As shown in FIG. 4, in the image forming apparatus according to this embodiment, one blower fan 30 is provided for each cooling flow path 32, but the upstream side of each cooling flow path 32 may be a common flow path, and one blower fan may be provided in the common flow path. Also, an airflow generating device other than a fan may be used. Furthermore, in addition to the blower fan 30, an exhaust fan 37 (see the two-dot chain line in FIG. 4) may be provided at or near the exhaust port 36 as an exhaust device that exhausts airflow from the exhaust port 36. In that case, it is possible to increase the speed of the airflow, thereby increasing the cooling effect and the amount of water vapor recovered.

In this embodiment, the cooling port 34 and the water vapor inlet 35 are arranged separately in the paper passage area W1 for the minimum width paper and the non-paper passage area W3, but the paper passage area and non-paper passage area where the cooling port 34 and the water vapor inlet 35 are arranged may be paper passage areas and non-paper passage areas for paper other than the minimum width size. In other words, the water vapor inlet 35 is arranged in a recording medium passage area where a recording medium of a specific width size specified from various width sizes such as the minimum width size, the maximum width size, or an intermediate width size between these passes, and the cooling port 34 is arranged in a non-passage area where a recording medium of that specific width size does not pass.

In addition, this embodiment employs a so-called center-based transport method in which paper of various width sizes is transported based on the center of each width, and therefore both sides (outside) of the paper-passing area in the width direction are non-paper-passing areas. For this reason, in this embodiment, the water vapor inlet 35 is positioned closer to the longitudinal center C of the pressure roller 21 (see FIG. 4) than the cooling port 34 (closer to the center). However, the present invention is not limited to image forming devices using the center-based transport method, but can also be applied to image forming devices using the so-called end-based transport method in which paper of various width sizes is transported based on one end of the width direction.

The water vapor inlet 35 may be arranged in the non-paper passing area in addition to the paper passing area. In that case, water vapor can be collected over a wider area, and condensation can be further suppressed. On the other hand, it is preferable that the cooling port 34 is not arranged in the paper passing area. If the cooling port 34 is arranged in the paper passing area, the airflow may be blown directly onto the paper passing area of the pressure roller 21, lowering the temperature of the paper passing area of the fixing belt 20, which may cause poor fixing. In this regard, in the image forming apparatus according to this embodiment, the cooling port 34 is arranged only in the non-paper passing area, so that a drop in temperature in the paper passing area can be prevented and good fixing properties can be obtained.

In addition, in the image forming apparatus according to this embodiment, the cooling port 34 is arranged to face the pressure roller 21, not the fixing belt 20, so that it is possible to avoid the air flow being blown directly onto the surface of the fixing belt 20. This makes it possible to prevent the temperature of the paper passing area of the fixing belt 20 from being directly affected by the air blowing and causing a drop or variation in temperature, stabilizing the temperature of the paper passing area and achieving good fixing performance. Note that the position of the cooling port 34 is not limited to the position on the opposite side of the nip portion N of the pressure roller 21, but may be any other position facing the pressure roller 21.

On the other hand, it is preferable that the water vapor inlet 35 is located above the nip portion N as shown in FIG. 3. Since water vapor generated from the paper usually moves upward, by arranging the water vapor inlet 35 above the nip portion N or the pressure roller 21, water vapor can easily flow into the water vapor inlet 35. Therefore, when the water vapor inlet 35 is located above the nip portion N or the pressure roller 21, water vapor can be efficiently collected, and paper slippage and image defects caused by condensation can be more effectively suppressed. Note that "above the nip portion N or the pressure roller 21" here is not limited to directly above the nip portion N or the pressure roller 21 (vertically above), but broadly includes positions higher than the nip portion N or the pressure roller 21, and may be a position other than directly above the nip portion N or the pressure roller 21 as long as it is a position that can collect at least a portion of the water vapor generated from the paper during the fixing process.

In addition, in the image forming apparatus according to this embodiment, the water vapor inlet 35 is located downstream of the cooling port 34 in the air flow guide direction of the duct 31, so that the air that is blown onto the pressure roller 21 at the position of the cooling port 34 and heated is sent to the water vapor inlet 35 on the downstream side. Therefore, in the image forming apparatus according to this embodiment, the water vapor collected from the water vapor inlet 35 is less likely to condense inside the duct 31, and the water vapor can be effectively exhausted from the exhaust port 36.

In addition, in the image forming apparatus according to this embodiment, the water vapor inlet 35 is configured as a slit-shaped hole that extends long in a direction intersecting (perpendicular or diagonal) the longitudinal direction X of the pressure roller 21, so that even if condensed water droplets adhere to the edge of the water vapor inlet 35, the water droplets can be moved in the longitudinal direction along the water vapor inlet 35, thereby moving the water droplets away from above the pressure roller 21 and the paper transport path. This makes it possible to prevent the water droplets from adhering to the pressure roller 21 or guide members of the paper transport path, and more reliably suppresses the occurrence of paper slippage and image defects.

Also, unlike this embodiment, the water vapor inlet 35 may be formed to extend long in the longitudinal direction X of the pressure roller 21, as in the example shown in FIG. 6. In this case, water vapor can be collected evenly across the longitudinal direction X of the pressure roller 21.

The shape, size, and number of the water vapor inlets 35 can be changed as appropriate. For example, the water vapor inlets 35 can be circular holes, and multiple holes can be provided on the wall of the water vapor recovery passage 33.

In addition, in this embodiment, the pair of cooling channels 32 and the water vapor recovery channel 33 are integrally configured, but they may be configured separately. By configuring each cooling channel 32 and the water vapor recovery channel 33 as separate bodies, the ease of assembly when installing them around the fixing device 9 is improved.

In addition, in order to prevent deformation of the pressure roller 21 and to improve the ease of jam clearance, if the pressure roller 21 is configured to be able to move toward and away from the fixing belt 20, it is preferable to have each cooling passage 32 work in conjunction with the approaching and separating action of the pressure roller 21. This allows the pressure roller 21 to be separated from the fixing belt 20, preventing deformation (plastic deformation) of the pressure roller 21 and making jam clearance easier.

Although the above describes each embodiment of the present invention, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made without departing from the spirit of the invention. In the above-mentioned embodiments, a fixing device equipped with a fixing belt and a pressure roller was described as an example, but the present invention is also applicable to a fixing device equipped with a fixing roller instead of a fixing belt. Also, a fixing device using a pressure belt instead of a pressure roller may be used.

The fixing device according to the present invention is not limited to a fixing device that transports paper from bottom to top as shown in Figures 1 and 2, but may be a fixing device that transports paper horizontally.

Furthermore, the present invention is not limited to application to a fixing device, which is an example of a heating device installed in an image forming apparatus. For example, the present invention can also be applied to a heating device such as a drying device that heats paper to dry the ink (liquid) on the paper in an inkjet image forming apparatus.

9 Fixing device (heating device)
20 Fixing belt (heating member)
21 Pressure roller (opposing member)
22 Heater (heat source)
30 Blower fan (airflow generating device)
31 Duct (flow path forming member)
32 Cooling flow path 33 Water vapor recovery flow path 34 Cooling port 35 Water vapor inlet 36 Exhaust port 37 Exhaust fan 100 Image forming apparatus C Center of pressure roller in longitudinal direction N Nip portion P Paper (recording medium)
X: Longitudinal direction of pressure roller

JP 2017-187806 A

Claims (9)

a heating device for heating the recording medium;
An airflow generating device that generates an airflow;
a flow path forming member that guides the airflow generated by the airflow generating device;
An image forming apparatus comprising:
The heating device includes:
A heat source;
A heating member heated by the heat source;
an opposing member facing the heating member and forming a nip portion between the opposing member and the heating member;
Equipped with
the flow passage forming member has a pair of cooling flow passages and a water vapor recovery flow passage where the pair of cooling flow passages join at upper portions of the pair of cooling flow passages, and is a cylindrical duct extending from below the opposing member toward above the opposing member,
the cooling passage has a cooling port arranged to face the opposing member,
the water vapor recovery passage has a water vapor inlet that is disposed above the opposing member and at a position closer to a longitudinal center of the opposing member than the cooling port,
The duct draws air into the pair of cooling flow paths from below the opposing member, blows the drawn air onto the opposing member through the cooling ports of the pair of cooling flow paths, causes at least a portion of the water vapor generated when the recording medium is heated to flow into the water vapor recovery flow path from the water vapor inlet, and discharges the water vapor to the outside together with the air blown onto the opposing member . a heating device for heating the recording medium;
An airflow generating device that generates an airflow;
a flow path forming member that guides the airflow generated by the airflow generating device;
An image forming apparatus comprising:
The heating device includes:
A heat source;
A heating member heated by the heat source;
an opposing member facing the heating member and forming a nip portion between the opposing member and the heating member;
Equipped with
the flow passage forming member has a pair of cooling flow passages and a water vapor recovery flow passage where the pair of cooling flow passages join at upper portions of the pair of cooling flow passages, and is a cylindrical duct extending from below the opposing member toward above the opposing member,
the cooling passage has a cooling port disposed so as to face the opposing member in a non-passage area where the recording medium does not pass,
the water vapor recovery passage has a water vapor inlet that is disposed above the opposing member and at a position corresponding to a recording medium passing area through which the recording medium passes,
The duct draws air into the pair of cooling flow paths from below the opposing member, blows the drawn air onto the opposing member through the cooling ports of the pair of cooling flow paths, causes at least a portion of the water vapor generated when the recording medium is heated to flow into the water vapor recovery flow path from the water vapor inlet, and discharges the water vapor to the outside together with the air blown onto the opposing member . The image forming apparatus according to claim 1 or 2, wherein the water vapor inlet is disposed downstream of the cooling port in the air flow guide direction of the flow path forming member. The image forming apparatus according to any one of claims 1 to 3, wherein the water vapor inlet is disposed above the nip portion. The image forming apparatus according to any one of claims 1 to 4, wherein the water vapor inlet is formed long in a direction intersecting the longitudinal direction of the opposing member. The image forming apparatus according to any one of claims 1 to 4, wherein the water vapor inlet is formed long in the longitudinal direction of the opposing member. the flow passage forming member has the cooling port on each end side of the opposed member in a longitudinal direction relative to the water vapor inlet,
7. The image forming apparatus according to claim 1, further comprising one airflow generating device corresponding to each of the cooling ports. The image forming apparatus according to any one of claims 1 to 7, further comprising an exhaust port for discharging the airflow guided by the flow path forming member to the outside of the image forming apparatus or to the outside of the recording medium transport path. 9. The image forming apparatus according to claim 8 , further comprising an exhaust device that exhausts airflow from the exhaust port to the outside of the image forming apparatus or to the outside of the recording medium transport path.

Images