Particulate matter collection device and image forming apparatus

Abstract

To suppress an increase of UFPs due to an increase in temperature of hot air discharge channels.SOLUTION: A fine particle collecting device is provided with ozone discharge channels 31, 33 through which ozone generated in an electrifying device 6 (ozone generating unit) is discharged, and hot air discharge channels 32, 33 that discharge hot air generated in a fixing device 20 (hot air generating unit). The ozone discharge channels 31, 33 and the hot air discharge channels 32, 33 are provided with the confluent discharge channel 33 where channels are joined to each other on their downstream side. The fine particle collecting device is further provided with heat dissipation fins 53, 54 (cooling means) that can cool air at some midpoints of the hot air discharge channels 32, 33 and at positions not in the confluent discharge channel 33.SELECTED DRAWING: Figure 2

Description

Technical Field

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[0001] This invention relates to a particulate collection device for collecting particulate matter, and an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine equipped with the same.

Background Art

[0002] Conventionally, in image forming apparatuses such as copying machines and printers, an ozone discharge path for discharging ozone generated by a charging device (ozone generation unit) that charges a photoreceptor drum (image carrier), and a hot air discharge path for discharging hot air generated by a fixing device (hot air generation unit) that heats a toner image and fixes it on a sheet, are provided with a combined discharge path that merges downstream (see, for example, Patent Document 1). And in Patent Document 1, a suction fan and an ozone filter are installed in the middle of the ozone discharge path, and an electrostatic filter is installed in the middle of the combined discharge path to efficiently collect UFP (ultrafine particles).

Summary of the Invention

Problems to be Solved by the Invention

[0003] The technology described in Patent Document 1 and the like has an increased amount of UFP (ultrafine particles) generated due to a temperature rise at the upstream position in the hot air discharge path with respect to the combined discharge path where the hot air discharge path and the ozone discharge path merge.

[0004] This invention has been made to solve the above-mentioned problems, and an object thereof is to provide a particulate collection device and an image forming apparatus in which an increase in UFP due to a temperature rise in the hot air discharge path is unlikely to occur.

Means for Solving the Problems

[0005] The particulate matter collection device of this invention comprises an ozone discharge path through which ozone generated in an ozone generation unit is discharged, and a hot air discharge path through which hot air generated in a hot air generation unit is discharged. The ozone discharge path and the hot air discharge path are joined together downstream of each other in a combined discharge path, and a cooling means capable of cooling the air is installed in the middle of the hot air discharge path, but not in the combined discharge path. Furthermore, a second cooling means capable of cooling the air is installed in the middle of the ozone discharge path, but not in the confluence discharge path, and the second cooling means is a heat dissipation fin provided on at least one of the inner wall and outer wall of the ozone discharge path. . [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a particulate matter collection device and an image forming apparatus that are less prone to an increase in UFP due to a rise in temperature in the hot air exhaust path. [Brief explanation of the drawing]

[0007] [Figure 1] This is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention. [Figure 2] This is a diagram showing the configuration of a particulate matter collection device. [Figure 3] This is a schematic top view of the particulate matter collection device, showing it in the width direction. [Figure 4] This is a schematic perspective view showing the interior of the hot air exhaust pathway (or ozone exhaust pathway). [Modes for carrying out the invention]

[0008] Hereinafter, embodiments for carrying out this invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and redundant explanations will be simplified or omitted as appropriate.

[0009] First, Figure 1 will explain the overall configuration and operation of the image forming apparatus 1. In Figure 1, 1 is a copier as an image forming apparatus, 2 is a document reading unit that optically reads image information from the original document D, and 3 is an exposure unit that irradiates exposure light L onto the photoreceptor drum 5 based on the image information read by the document reading unit 2. Furthermore, 4 is a developing device that develops the latent image formed on the photoreceptor drum 5 to form a toner image (image), 5 is a photoreceptor drum as an image carrier, 6 is a charging device (charging charger) that generates ozone to charge the surface of the photoreceptor drum 5, 7 is a transfer device (transfer roller) that transfers the toner image formed on the photoreceptor drum 5 to the sheet P, and 8 is a cleaning device that removes any untransferred toner remaining on the photoreceptor drum 5. Furthermore, 10 is a document transport unit that transports the set document D to the document reading unit 2, 12 is a paper feed unit (paper feed cassette) in which a sheet P such as paper is stored, 20 is a fixing device that serves as a hot air generation unit that heats the toner image (unfixed image) on the sheet P and fixes it to the sheet P, 21 is a fixing roller installed in the fixing device 20, 22 is a pressure roller installed in the fixing device 20, 30 is a particle collection device that collects fine particles in the image forming apparatus 1, and 45 is a timing roller (resist roller) that transports the sheet P toward the transfer device 7 (transfer nip).

[0010] Referring to Figure 1, the normal operation of the image forming apparatus during image formation will be explained. First, the original document D is transported from the document table in the direction of the arrow in the diagram by the transport rollers of the document transport unit 10 and passes over the document reading unit 2. At this time, the image information of the original document D passing over it is optically read by the document reading unit 2. The optical image information read by the document reading unit 2 is then converted into an electrical signal and transmitted to the exposure unit 3 (writing device). The exposure unit 3 then emits exposure light L (laser light) based on the image information in the electrical signal, directed towards the photosensitive drum 5.

[0011] Meanwhile, the photoreceptor drum 5, acting as an image carrier, rotates clockwise in the diagram, and after a predetermined image formation process (charging, exposure, and development), an image (toner image) corresponding to the image information is formed on the photoreceptor drum 5. Subsequently, the image formed on the photoreceptor drum 5 is transferred onto the sheet P, which is transported by the timing roller 45, at a position opposite the transfer device 7 (transfer nip).

[0012] More specifically, the photoreceptor drum 5 rotates clockwise in Figure 1. First, the surface of the photoreceptor drum 5 is uniformly charged at the position opposite the charging device 6 (this is the charging process). In this way, a charge potential is formed on the photoreceptor drum 5. In this embodiment, a known corona discharge type charging charger is used as the charging device 6. Subsequently, the surface of the charged photoreceptor drum 5 reaches the irradiation position of the exposure light L. Then, an electrostatic latent image based on the image information read by the document reading unit 2 is formed on the surface of the photoreceptor drum 5 (this is the exposure process). Subsequently, the surface of the photoreceptor drum 5, on which the electrostatic latent image has formed, reaches a position opposite the developing device 4. Then, toner is supplied from the developing device 4 onto the photoreceptor drum 5, and the latent image on the photoreceptor drum 5 is developed (this is the developing process). Subsequently, the surface of the photoreceptor drum 5 after the development process reaches the position opposite the transfer device 7 (transfer nip). At the position of the transfer device 7, the toner image formed on the photoreceptor drum 5 is transferred onto the sheet P (this is the transfer process). A transfer bias with a polarity different from that of the toner is applied to the transfer device 7 (transfer roller). Then, the surface of the photoreceptor drum 5 after the transfer process reaches a position opposite the cleaning device 8. The cleaning device 8 then removes and recovers any untransferred toner remaining on the photoreceptor drum 5 (this is the cleaning process). Subsequently, the surface of the photoreceptor drum 5 passes through the static elimination section, and the series of imaging processes in the photoreceptor drum 5 is completed.

[0013] On the other hand, the sheet P, which is transported to the position of the transfer device 7 (transfer nip), operates as follows. First, the uppermost sheet P stored in the paper feed unit 12 is fed by the paper feed roller towards a transport path where multiple transport roller pairs are installed. Then, the sheet P reaches the position of the timing roller 45. Once the sheet P reaches the position of the timing roller 45, it is transported towards the transfer device 7 (transfer nip) in order to align with the image formed on the photoreceptor drum 5.

[0014] After that, after the sheet P passes through the position of the transfer device 7 after the transfer process, it reaches the fixing device 20 through the conveyance path. The sheet P that has reached the fixing device 20 (the sheet P carrying the unfixed image) is fed between the fixing roller 21 (which has a heater as a heat source installed inside) and the pressure roller 22, and the toner image (image) is fixed by the heat received from the fixing roller 21 and the pressure received from both members 21 and 22. The sheet P on which the toner image has been fixed is discharged from the image forming apparatus main body 1 after being sent out from between the fixing roller 21 and the pressure roller 22 (the fixing nip). In this way, a series of image forming processes is completed.

[0015] Next, in the present embodiment, the fine particle collection device 30 installed in the image forming apparatus 1 will be described in detail. Referring to FIGS. 1 to 3, the image forming apparatus 1 in the present embodiment is provided with a fine particle collection device 30 for collecting fine particles existing inside the device and not discharging them outside the device. The fine particle collection device 30 in the present embodiment is particularly for collecting ultrafine particles of 7 to 300 nm (hereinafter, appropriately referred to as "UFP") defined by the BA (Blue Angel, RAL-UZ171) standard.

[0016] Then, the fine particle collection device 30 in the present embodiment is provided with ozone discharge paths 31 and 33 through which ozone generated by the ozone generation unit (the charging device 6 that charges the photosensitive drum 5 as an image carrier) is discharged, and an electrostatic filter 37 is installed in the middle of the ozone discharge paths 31 and 33. When ozone is generated by high-voltage discharge by the charging device 6 during image formation (during the charging process), a part of the organic substances existing around it (for example, various members constituting the image forming unit, toner and paper powder floating around the photosensitive drum 5, etc.) becomes UFP ionized by the ozone.

[0017] In this embodiment, an electrostatic filter 37 is installed in the middle of the ozone discharge paths 31 and 33 (between the suction port A1 and the discharge port B). In particular, in this embodiment, an electrostatic filter 37 is installed in the middle of the confluence duct 33 (confluence discharge path). Specifically, the electrostatic filter 37 is detachably installed at the position of the discharge port B of the ozone discharge path (confluence duct 33). The electrostatic filter 37 has a very fine mesh of filter fibers, and the filter fibers are always charged positively and negatively. On the other hand, although the UFPs generated together with ozone by the charging device 6 as the ozone generation unit are in an ionized state and can hardly be collected by the ozone filter 35 described later, they can be sufficiently collected electrostatically by the electrostatic filter 37.

[0018] Therefore, even if an ion generator is not provided in the ozone discharge paths 31 and 33, the problem that UFPs are released to the outside of the image forming apparatus 1 can be sufficiently reduced. In this embodiment, as the charging device 6, a corona discharge type charger that easily generates ozone is used, and as the transfer device 7, a roller application type transfer roller that hardly generates ozone is used. Therefore, the suction port A1 of the ozone discharge path is provided near the charging device 6. On the other hand, when a corona discharge type transfer charger that easily generates ozone is used as the transfer device 7, it is preferable to provide a suction port of the ozone discharge path near the transfer device 7. In addition, when there is an ozone generation unit in the image forming apparatus 1 (for example, when a pre-transfer charger is provided), it is preferable to provide a suction port of the ozone discharge path near the ozone generation unit. Also, even when a charging roller or a transfer roller that hardly generates ozone is used, in a high-speed image forming apparatus with a high printing speed, the amount of ozone generated is larger than that of a low-speed one. Therefore, it is preferable to provide a suction port of the ozone discharge path near those ozone generation units (charging roller or transfer roller).

[0019] [[ID= In this embodiment, the particulate matter collection device 30 is provided with a first duct 31, a second duct 32, and a confluence duct 33. The first duct 31 is for exhausting air from the vicinity of the charging device 6, which serves as the ozone generation unit, to the outside of the image forming apparatus body 1. The first duct 31 has a suction port A1 at its upstream end, near the charging device 6, and a suction fan 41 and an ozone filter 35 are installed along its path, with its downstream end connected to the confluence duct 33. The second duct 32 is for exhausting air from the vicinity of the fixing device 20, which serves as a hot air generation unit, toward the outside of the image forming apparatus body 1. The second duct 32 has a suction port A2 at its upstream end, near the fixing device 20, a VOC filter 36 is installed in its path, and its downstream end is connected to the confluence duct 33. The confluence duct 33 has the first duct 31 and the second duct 32 connected at its upstream end, an electrostatic filter 37 is provided along its path, and an outlet B is provided at its downstream end.

[0020] In other words, the ozone emission path consists of the first duct 31 and the confluence duct 33. Furthermore, an ozone filter 35 is installed upstream of the electrostatic filter 37, in the middle of the ozone discharge paths 31 and 33 (first duct 31), to decompose ozone generated by the high-voltage discharge of the charging device 6. The ozone filter 35 can be one that uses manganese oxide as a catalyst. Even if the ozone is decomposed after passing through the ozone filter 35, the ionized state of the UFPs remains unchanged, so the collection efficiency of the electrostatic filter 37 does not decrease. Additionally, because the ozone is decomposed by the ozone filter 35 upstream of the electrostatic filter 37, further generation of UFPs by ozone becomes difficult, thus increasing the collection efficiency of the electrostatic filter 37. Furthermore, a suction fan 41 is installed in the middle of the ozone discharge paths 31 and 33 (first duct 31), upstream of the ozone filter 35, which generates an airflow from right to left as shown in Figures 1 and 2. With this configuration, in the ozone discharge paths 31 and 33, the ozone generated by the high-voltage discharge from the charging device 6 is decomposed by the ozone filter 35, and air with a low ozone content is discharged outside the device. Furthermore, as described above, in the ozone discharge paths 31 and 33, UFP generated along with ozone by the high-voltage discharge from the charging device 6 is collected (removed) by the electrostatic filter 37, and air with a low UFP content is discharged outside the device.

[0021] On the other hand, the second duct 32 and the confluence duct 33 function as a hot air discharge path for discharging the hot air (high-temperature air) generated by the fixing device 20, which acts as a hot air generation unit. Therefore, the ozone discharge path and the hot air discharge path are combined into a confluence discharge path (confluence duct 33) where their downstream sides merge. The electrostatic filter 37 is installed in the middle of this confluence discharge path (confluence duct 33).

[0022] The hot air exhaust paths 32 and 33 are for exhausting (relieving heat) from the vicinity of the fixing device 20 toward the outside of the image forming apparatus 1. A VOC filter 36 is installed in the middle of these hot air discharge paths 32 and 33, at a location that is not part of the combined discharge path 33 (the location of the second duct 32), to collect volatile organic compounds (VOCs) generated from the fixing device 20. Furthermore, in this embodiment, a blower fan 44 is installed to send air (outside air) towards a location in the hot air discharge path that is not part of the confluence discharge path (the second duct 32). As a result, an airflow in the second duct 32 is generated in the direction of the white arrow in the figure (an airflow from right to left in Figures 1 and 2). With this configuration, in the hot air discharge path, volatile organic compounds generated by the fixing process by the fixing device 20 are collected (removed) by the VOC filter 36, while the heat generated by the fixing device 20 is discharged (wasted heat) outside the device.

[0023] Here, UFP is generated not only by the charging device 6, which serves as the ozone generation unit, along with ozone, as described above, but also at the location of the fixing device 20 (hot air generation unit). Specifically, the UFPs generated by the fixing device 20 are thought to be formed when high-boiling-point substances (such as low-molecular-weight siloxine or paraffin) contained in the fixing device 20 and toner are cooled and agglomerated by the thermal energy during the fixing process, resulting in the formation of fine particles. However, unlike the UFP generated in the hot air generation unit (fixing device 20), most of the UFP generated in the ozone generation unit (charging device 6) are not ionized. Furthermore, such UFPs have very small particle sizes and are almost impossible to capture with the VOC filter 36.

[0024] In this embodiment, ionized UFP flowing through the ozone discharge path and unionized UFP flowing through the hot air discharge path are combined in a combined discharge path (combined duct 33). As a result, the ionized UFPs absorb the non-ionized UFPs, causing both types of UFPs to aggregate and become larger. These aggregated UFPs maintain their ionized (charged) state and, due to their larger particle size, can be efficiently collected by the electrostatic filter 37 installed in the middle of the confluence discharge path (at the location of discharge port B). In other words, even if an electrostatic filter is installed in the middle of the hot air discharge path without a combined discharge path, UFP flowing through the hot air discharge path is hardly ionized, so electrostatic collection by the electrostatic filter is not sufficient, and a large portion of the UFP is released outside the device. In contrast, in this embodiment, a combined discharge path is provided where the ozone discharge path and the hot air discharge path merge, and the unionized UFP in the combined discharge path agglomerates with the ionized UFP and becomes ionized, so electrostatic collection by the electrostatic filter 37 becomes possible, and a large portion of the UFP is not released outside the device.

[0025] One possible approach is to connect the downstream end of the ozone discharge path with the upstream end of the hot air discharge path, so that the hot air generated in the hot air generation section (fixing device 20), which is high-temperature air containing unionized UFP, is directly combined with the UFP that has been ionized at the location of the hot air generation section. However, if configured in this way, the ozone flowing in from the ozone discharge path will be heated to a high temperature by the hot air generation section, increasing its reactivity and generating even more UFP. Furthermore, if the system is configured as described above, and an ozone filter is installed in the ozone discharge path to allow the air after ozone collection (air containing ionized UFPs) to merge with the hot air generation unit, the hot air from the hot air generation unit will inhibit the aggregation of ionized and unionized UFPs, making collection by the electrostatic filter difficult. In contrast, in this embodiment, the downstream side of the ozone discharge path and the downstream side of the hot air discharge path are connected to provide a combined discharge path, where ionized UFP and unionized UFP are combined. Therefore, the electrostatic filter 37 can efficiently and sufficiently capture both types of UFP without the problems of increased UFP due to high ozone temperatures or the inhibition of aggregation of both types of UFP due to high temperatures.

[0026] In this embodiment, the ozone filter 35 is installed in the middle of the ozone discharge paths 31 and 33, but not in the combined discharge path 33 (it is in the path of the first duct 31). Specifically, the ozone filter 35 is installed in the ozone discharge paths 31 and 32 just before reaching the combined discharge path 33 (it is a downstream position of the first duct 31). This makes it possible to improve the collection efficiency of UFP by the electrostatic filter 37 compared to the case where the electrostatic filter 37 is installed in the combined discharge path 33 (where unionized UFP and ionized UFP are combined and then ozone decomposition is performed by an ozone filter). In detail, in the combined discharge path 33, the aggregation of unionized UFPs and ionized UFPs causes the average particle size of unionized UFPs discharged from the second duct 32 to increase from tens of nanometers to hundreds of nanometers. However, when UFPs aggregate in this way, if the ozone concentration in the surrounding air is too high, it can also cause other substances in the air to become finer, potentially increasing the amount of UFPs. Therefore, in this embodiment, an ozone filter 35 is installed in the first duct 31 to reduce the ozone concentration in the air flowing from the first duct 31 into the combined discharge path 33. This reduces the generation of new UFPs in the combined discharge path 33 while promoting the aggregation and enlargement of UFPs, thereby improving the collection efficiency of UFPs by the electrostatic filter 37.

[0027] In this embodiment, a suction fan 41 is installed in the middle of the ozone discharge paths 31 and 33, but not in the combined discharge path 33 (it is in the path of the first duct 31). Also, a blower fan 44 is installed in the hot air discharge paths 32 and 33, but not in the combined discharge path 33 (it is at the uppermost position of the second duct 32). This configuration promotes the aggregation of both UFPs (ionized UFPs flowing in from the first duct 31 and unionized UFPs flowing in from the second duct 32) in the combined discharge path (combined duct 33) compared to when the suction fan is installed in the combined discharge path. In other words, if the suction fan is installed in the combined discharge path, both UFPs tend to flow downstream before they can aggregate sufficiently, which may result in insufficient collection by the electrostatic filter. In contrast, in this embodiment, the suction fan 41 and the blower fan 44 are installed sufficiently upstream of the combined discharge path, making such problems less likely to occur.

[0028] The following describes the more characteristic configuration and operation of the particulate matter collection device 30 in this embodiment. As shown in Figures 2 and 4(A), the particulate matter collection device 30 in this embodiment is equipped with heat dissipation fins 53 and 54 (first heat dissipation fins) as a cooling means (first cooling means) capable of cooling the air, located in the middle of the hot air discharge path but not in the confluence discharge path (in the path of the second duct 32). More specifically, the first heat dissipation fins 53 and 54, which serve as cooling means, are made of a highly heat-dissipating metal material such as aluminum, are formed in a flat plate shape, and are provided on the inner and outer walls of the second duct 32 (hot air discharge path), respectively. Multiple first heat dissipation fins 53 are installed on the outer wall of the second duct 32 so as to protrude inward at intervals, and multiple first heat dissipation fins 54 are also installed on the inner wall of the second duct 32 so as to protrude inward at intervals.

[0029] In this way, by providing heat dissipation fins 53 and 54 (cooling means) that dissipate and cool the hot air (air) flowing in the second duct 32, the problem of increased UFP (ultrafine particles) generation due to a rise in the temperature of the second duct 32 becomes less likely to occur. In other words, the increase in UFP due to a rise in the temperature of the hot air discharge path becomes less likely. As explained earlier, in the confluence duct 33 (confluence discharge path), ionized UFP from the first duct 31 and unionized UFP from the second duct 32 are combined. This makes it easy for problems to occur, such as an increase in UFP due to the high temperature of the ozone, or the inhibition of aggregation of both types of UFP due to the high temperature. In contrast, in this embodiment, the second duct 32, which is prone to becoming hot due to the hot air, is directly cooled, making it difficult for the first duct 31 and the confluence duct 33 adjacent to the second duct 32 to become hot. Therefore, an increase in UFP due to the high temperature of the ozone in the first duct 31 is less likely to occur, and the inhibition of aggregation of both types of UFP (ionized UFP and unionized UFP) due to the high temperature in the confluence duct 33 is also less likely to occur. Consequently, both types of UFP can be efficiently and sufficiently collected by the electrostatic filter 37. In this embodiment, the first heat dissipation fins 53 and 54, which serve as cooling means, are provided on the inner wall and outer wall of the second duct 32 (hot air discharge path), respectively. However, they can also be provided on at least one of the inner wall and outer wall of the second duct 32 (hot air discharge path).

[0030] In this embodiment, the particulate matter collection device 30 has a first cooling fan 43 installed as a cooling means (first cooling means) at a position facing the outer wall of the second duct 32. This first cooling fan 43 blows air toward the outer wall of the second duct 32 itself or toward the heat dissipation fins 53 installed on that outer wall, thereby cooling the second duct 32. By installing the first cooling fan 43 in this manner, problems such as an increase in the amount of UFP generated due to a rise in the temperature of the second duct 32, and problems such as UFP agglomeration in the confluence duct 33, become even less likely to occur.

[0031] Furthermore, as explained earlier, the particulate matter collection device 30 in this embodiment is equipped with a blower fan 44 that sends air toward the second duct 32. This blower fan 44 has the function of increasing the airflow within the second duct 32, and also has the function of blowing air onto the heat dissipation fins 54 installed on the inner wall of the second duct 32 to cool them. Therefore, problems such as an increase in the amount of UFP generated due to a rise in temperature in the second duct 32, and the aggregation of UFP in the confluence duct 33, become even less likely to occur.

[0032] Referring to Figures 2 and 4(A), etc., in this embodiment, the particulate matter collection device 30 is located in the middle of the ozone discharge path but not in the confluence discharge path (it is in the path of the first duct 31), and heat dissipation fins 51 and 52 (second heat dissipation fins) are installed as a second cooling means capable of cooling the air. More specifically, the second heat dissipation fins 51 and 52, which serve as the second cooling means, are made of a highly heat-dissipating metal material such as aluminum, are formed in a flat plate shape, and are provided on the inner and outer walls of the first duct 31 (ozone discharge path), respectively. Multiple second heat dissipation fins 51 are installed on the outer wall of the first duct 31 so as to protrude inward at intervals, and multiple second heat dissipation fins 52 are also installed on the inner wall of the first duct 31 so as to protrude inward at intervals.

[0033] In this way, by providing heat dissipation fins 51 and 52 (second cooling means) that dissipate and cool the hot air (air) flowing in the first duct 31, the problem of increased UFP generation due to high temperature in the first duct 31 becomes less likely to occur. In other words, the increase in UFP due to the temperature rise of the ozone discharge path itself becomes less likely. In this embodiment, the first duct 31 is directly cooled, making it less likely to overheat. Therefore, an increase in UFP due to high ozone temperatures in the first duct 31 is less likely to occur. Furthermore, inhibition of aggregation due to high temperatures of both types of UFP (ionized UFP and unionized UFP) in the confluence duct 33 adjacent to the first duct 31 is also less likely to occur. Consequently, both types of UFP can be efficiently and sufficiently collected by the electrostatic filter 37. In this embodiment, the second heat dissipation fins 51 and 52, which serve as the second cooling means, are provided on the inner wall and outer wall of the first duct 31 (ozone discharge path), respectively. However, they can also be provided on at least one of the inner wall and outer wall of the first duct 31 (ozone discharge path).

[0034] Furthermore, in this embodiment, the particulate matter collection device 30 is equipped with a second cooling fan 42 as a second cooling means, positioned opposite the outer wall of the first duct 31. This second cooling fan 42 blows air towards the outer wall of the first duct 31 itself and the second heat dissipation fins 51 installed on that outer wall, thereby cooling the first duct 31. By installing the second cooling fan 42 in this manner, problems such as increased UFP generation due to high temperatures in the first duct 31 and condensation of UFP in the confluence duct 33 become even less likely to occur.

[0035] In this embodiment, although not shown in the illustration, a third cooling means (which can be composed of, for example, heat dissipation fins or a cooling fan) can also be provided to directly cool the confluence duct 33 (air flowing through the confluence discharge path). In such cases, among the effects described above, the problem of UFP aggregation in the confluence duct 33 becomes less likely to occur.

[0036] As explained earlier using Figure 4(A), in this embodiment, the first heat dissipation fin 54 provided on the inner wall of the second duct 32 (hot air discharge path) and the second heat dissipation fin 52 provided on the inner wall of the first duct 31 (ozone discharge path) are formed in a flat plate shape. The heat dissipation fins 52 and 54 installed inside the duct are not limited to those exemplified in Figure 4(A), as long as they can cool the air inside the duct without obstructing the airflow inside the duct. As a specific example, the heat dissipation fins 52 and 54 shown in Figure 4(B) can also be made with multiple notches (or through holes). Furthermore, the heat dissipation fins 52 and 54 shown in Figure 4(C) can also be arranged to follow the direction of the airflow of hot air (or ozone) flowing through the hot air discharge path. At least two of the heat dissipation fins 52 and 54 shown in Figures 4(A) to (C) can also be used in combination.

[0037] As described above, the particulate matter collection device 30 in this embodiment is provided with ozone discharge paths 31 and 33 through which ozone generated in the charging device 6 (ozone generation unit) is discharged, and hot air discharge paths 32 and 33 through which hot air generated in the fixing device 20 (hot air generation unit) is discharged. Furthermore, a combined discharge path 33 is provided through which the downstream sides of the ozone discharge paths 31 and 33 and the hot air discharge paths 32 and 33 merge. In addition, heat dissipation fins 53 and 54 (cooling means) capable of cooling the air are installed in the middle of the hot air discharge paths 32 and 33, but not in the combined discharge path 33. This makes it less likely for the UFP to increase due to the temperature rise in the hot air exhaust paths 32 and 33.

[0038] In this embodiment, the present invention was applied to a particulate collection device 30 installed in a monochrome image forming apparatus 1, but the present invention can naturally also be applied to a particulate collection device installed in a color image forming apparatus. Furthermore, in this embodiment, the outlets B of the hot air exhaust paths 32 and 33 (and the ozone exhaust paths 31 and 33) are located on the side of the image forming apparatus 1. However, the location of the outlets B is not limited to this, and for example, the outlets B can also be located on the back of the image forming apparatus 1 (opposite the front where the user operates the apparatus). Furthermore, even in those cases, the same effects as those of this embodiment can be obtained.

[0039] Furthermore, although this embodiment applies the present invention to a particulate collection device 30 installed in an image forming apparatus 1, the application of the present invention is not limited to this. The present invention can be applied to any device other than an image forming apparatus that generates UFPs. Furthermore, in this embodiment, the particulate collection device 30 is installed internally in the image forming apparatus 1, but it is also possible to configure the image forming apparatus 1 to have the particulate collection device 30 installed externally. Furthermore, even in those cases, the same effects as those of this embodiment can be obtained.

[0040] Furthermore, in this embodiment, a corona discharge type charging charger was used as the charging device 6, but a roller application type charging roller can also be used as the charging device. Furthermore, in this embodiment, a known thermal heater type fixing device using a heater as a heat source was used as the fixing device 20. However, a known electromagnetic induction heating type fixing device equipped with an excitation coil can also be used as the fixing device, or a known resistance heating type fixing device equipped with a resistance heating element can also be used. Furthermore, in this embodiment, one suction fan 41 (or blower fan 44) is installed in both the ozone discharge path and the hot air discharge path, but the number of suction fans and blower fans is not limited to this. Furthermore, even in those cases, the same effects as those of this embodiment can be obtained.

[0041] It is clear that the present invention is not limited to this embodiment, and that this embodiment can be modified as appropriate within the scope of the technical concept of the present invention, in addition to what is suggested here. Furthermore, the number, position, shape, etc. of the constituent members are not limited to this embodiment, and can be set to a number, position, shape, etc. that is suitable for carrying out the present invention.

[0042] In this specification, the expression "~partway along the route" is defined as indicating any location (including the upstream end and the downstream end) from the upstream end to the downstream end of that route. [Explanation of Symbols]

[0043] 1. Image forming apparatus (image forming apparatus main unit), 5. Photosensitive drum (image carrier), 6. Charging device (ozone generation unit), 20 Fixing device (hot air generation unit), 30 Particulate collection device, 31. First duct (ozone discharge path), 32. Second duct (hot air exhaust path), 33. Confluence duct (confluence discharge route, ozone discharge route, hot air discharge route), 35 Ozone filters, 36 VOC filters, 37 Electrostatic filter, 41 Suction fan, 42 Second cooling fan (second cooling means), 43 First cooling fan (cooling means, first cooling means), 44. Blower fan, 51, 52 Second heat dissipation fin (second cooling means, heat dissipation fin), 53, 54 First heat dissipation fin (cooling means, first cooling means, heat dissipation fin), A1, A2 suction port, B discharge port, P sheet (paper).

[0044] Furthermore, the embodiments of the present invention can also be, for example, combinations of appendices 1 to 10 as follows. (Note 1) The ozone discharge path through which the ozone generated in the ozone generation unit is discharged, A hot air discharge path for discharging the hot air generated in the hot air generation section, Equipped with, The ozone discharge path and the hot air discharge path are provided with a combined discharge path where their downstream sides merge. A particulate matter collection device characterized in that a cooling means capable of cooling the air is installed in the middle of the hot air discharge path, but not in the confluence discharge path. (Note 2) The particulate matter collection device according to Appendix 1, characterized in that the cooling means is a heat dissipation fin provided on at least one of the inner wall and the outer wall of the hot air discharge path. (Note 3) The heat dissipation fins provided on the inner wall of the hot air discharge path are It is formed in a flat plate shape, The particulate matter collection device according to Appendix 2, characterized in that it is at least one of the following: one that is arranged along the airflow direction of the hot air flowing through the hot air discharge path, and one that has a plurality of notches or through holes formed therein. (Note 4) The particulate matter collection device according to any one of the appendices 1 to 3, characterized in that a second cooling means capable of cooling the air is installed in the middle of the ozone discharge path, but not in the confluence discharge path. (Note 5) The particulate matter collection device according to Appendix 4, characterized in that the second cooling means is a heat dissipation fin provided on at least one of the inner wall and the outer wall of the ozone discharge path. (Note 6) The heat dissipation fins provided on the inner wall of the ozone discharge path are It is formed in a flat plate shape, The particulate matter collection device according to Appendix 5, characterized in that it is at least one of the following: one that is arranged along the direction of the airflow of ozone flowing through the ozone discharge path, and one that has a plurality of notches or through holes formed therein. (Note 7) A particulate matter collection device according to any one of the appendices 1 to 6, characterized in that a blower fan is installed to send air towards a position in the hot air discharge path that is not the confluence discharge path. (Note 8) The particulate matter collection device according to any one of the appendices 1 to 7, characterized in that an ozone filter is installed in the ozone discharge path at a position immediately before reaching the confluence discharge path. (Note 9) A particulate matter collection device according to any one of the appendices 1 to 8, characterized in that an electrostatic filter is installed in the middle of the aforementioned combined discharge path. (Note 10) An image forming apparatus characterized by being equipped with a particulate matter collection device as described in any of Appendix 1 to Appendix 9. [Prior art documents] [Patent Documents]

[0045] [Patent Document 1] Japanese Patent Publication No. 2020-27158

Claims

1. The ozone discharge path through which the ozone generated in the ozone generation unit is discharged, A hot air discharge path for discharging the hot air generated in the hot air generation section, Equipped with, The ozone discharge path and the hot air discharge path are provided with a combined discharge path where their downstream sides merge. A cooling means capable of cooling the air is installed in the middle of the aforementioned hot air discharge path, but not in the aforementioned confluence discharge path. A second cooling means capable of cooling the air is installed in the middle of the ozone discharge path, but not in the confluence discharge path. The particulate matter collection device is characterized in that the second cooling means is a heat dissipation fin provided on at least one of the inner wall and outer wall of the ozone discharge path.

2. The particulate matter collection device according to claim 1, characterized in that the cooling means is a heat dissipation fin provided on at least one of the inner wall and the outer wall of the hot air discharge path.

3. The heat dissipation fins provided on the inner wall of the hot air discharge path are It is formed in a flat plate shape, The particulate matter collection device according to claim 2, characterized in that it is at least one of the following: one which is arranged along the airflow direction of the hot air flowing through the hot air discharge path, and one which has a plurality of notches or through holes formed therein.

4. The heat dissipation fins provided on the inner wall of the ozone discharge path are It is formed in a flat plate shape, The particulate matter collection device according to claim 1 or 2, characterized in that it is at least one of the following: one which is arranged along the direction of the airflow of ozone flowing through the ozone discharge path, and one which has a plurality of notches or through holes formed therein.

5. The particulate matter collection device according to claim 1 or 2, characterized in that a blower fan is installed to send air toward a position in the hot air discharge path that is not the confluence discharge path.

6. The particulate matter collection device according to claim 1 or 2, characterized in that an ozone filter is installed in the ozone discharge path at a position immediately before reaching the confluence discharge path.

7. The particulate matter collection device according to claim 1 or 2, characterized in that an electrostatic filter is installed in the middle of the combined discharge path.

8. An image forming apparatus characterized by comprising the particulate matter collection device described in Claim 1 or Claim 2.

Images